title stringlengths 0 901 | abstract stringlengths 3 9.89k | PMID int64 22 25.3M | embedding listlengths 768 768 |
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Pathogenesis of of cytomegalovirus infection. I. Activation of virus from bone marrow-derived lymphocytes by in vitro allogenic reaction. | After infection in utero or at birth with a cell culture adapted strain of mouse cytomegalovirus (MCMV), several mouse strains developed a latent virus infection in the presence of specific antiviral antibodies. Up to 5 mo after infection, MCMV could be activated and recovered from spleen lymphocytes of the infected animals that were co-cultivated with histoincompatible (H-2 foreign) mouse embryo cells from uninfected animals. In contrast, co-cultivation of lymphoid cells from infected mice with mouse embryo cells from syngeneic, histocompatible (H-2 similar) donors did not activate MCMV. Similarly, MCMV was not recovered from sonicated lymphoid cells. Virus was activated by treating viable lymphoid cells with lipopolysaccharide, a B-cell mitogen, but was not activated by a variety of other mitogens such as phytohemagglutinin, concanavalin A, or pokeweed mitogen. Subsequent purification of lymphoid cells from the infected mice by a variety of techniques indicated that MCMV was harbored in the B-lymphocyte population. | 163,887 | [
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A dual synaptic effect on hair cells in Hermissenda. | Type A photorecptors can produce an initial hyperpolarizing wave followed by a delayed long-lasting increase in firing which is usually accompanied by a small depolarizing wave. The initial hyperpolarizing wave arises from an increase in conductance while the depolarizing wave was shown to arise from a decrease in conductance. The data presented indicate that both effects produced by the type A photoreceptors in ipsilateral hair cells are synaptic. | 163,891 | [
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Differentiation of Entamoeba: a new medium and optimal conditions for axenic encystation of E. invadens. | Nutritional and culturing requirements for efficient axenic encystation of Entamoeba invadens have been studied. A simple and reliable axenic encystation medium has been developed. It contains 0.5% tryptic digest of casein, 0.5% yeast extract, and 5% dialyzed serum in 5 mM potassium phosphate, pH 7.0. Mass encystation (avg 70%) occurred within 30 hr when axenically growing trophozoites of E. invadens IP-l were transferred to this medium before they entered stationary growth phase. Mass encystation of E. invadens PZ occurred similarly, but less reproducibly. Two E. histolytica strains did not encyst. Experiments established that differentiation did not depend upon changes in the external environment after amebase were transferred to encystation medium and, therefore, was initiated by the shift from growth to encystation medium. | 163,898 | [
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RNA synthesis in cells infected with herpes simplex virus. X. Properties of viral symmetric transcripts and of double-stranded RNA prepared from them. | HEp-2 cells infected with herpes simplex 1 virus contain RNA transcripts capable of forming double-stranded (DS) RNA on annealing. The properties of purified DS RNA were as follows (i) DS RNA is resistant to depolymerization by RNase A or T-1 in 2 times 0.15 M NaCl, plus 0.015 M sodium citrate (SSC) but not 0.1 times SSC or following thermal denaturation. (ii) The Tm of the viral DS RNA was 100 C in 0.1 times SSC. (iii) Undenatured DS RNA does not hybridize with viral DNA: upon denaturation, excess unlabeled RNA drove 50 to 55% of labeled DNA into DNA-RNA hybrid. The kinetics of hybridization indicate that the DS RNA consists of at least two populations of transcripts arising from 29 and 26% of viral DNA and differing 40-fold in molar concentration. | 163,916 | [
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In vitro polyoma DNA synthesis: inhibition by 1-beta-d-arabinofuranosyl CTP. | The effects of 1-beta-D-arabinofuranosyl CTP (ara-CTP) on DNA replication were studied in an in vitro system from polyoma-infected BALB/3T3 cells. Ara-CTP concentrations of larger than or equal to 150 muM were found to block in vitro DNA synthesis completely, and concentrations of smaller than or equal to 0.3 muM had no inhibitory effect. Intermediate concentrations resulted in a concentration-dependent reduction of the in vitro synthesis rate. Long-term labeling with [alpha-32-P]ara-CTP demonstrated the incorporation of the analogue into cellular and viral DNA concomitantly with [3-H]TTP. In pulse-labeling experiments, at noninhibitory concentrations of the analogue, ara-CTP was incorporated into short DNA fragments and long growing strands to relatively the same extent as TTP. Partial venom phosphodiesterase digestion liberated the incoporated are-CTP at essentially the same rate as incorporated TTP, excluding a predominantly terminal incorporation, and after total venom phosphodiesterase digestion greater than 80% of the incorporated ara-CTP was recovered as 5'-ara-CMP. Analysis of the long-term in vitro viral DNA product made in the presence of partially inhibiting ara-CTP concentrations demonstrated that none of the steps leading to mature viral DNA were totally inhibited at the ara-CTP concentrations used. Pulse labeling of replicating viral DNA in the presence of ara-CTP revealed two consistent differences in the pattern found in control pulses: (i) predominant labeling of short chains (5S) with reduced amounts of radioactivity in the longer growing viral DNA strands (smaller than or equal to 16S), and (ii) a one-third to one-half reduction in size for short DNA chains labeled in the presence of ara-CTP. Release of the ara-CTP inhibition with excess dCTP resulted in covalent extension of these smaller short chans to approximately the size of regular short chains labeled in the absence of the inhibitor. Isolated short chains synthesized in the presence of ara-CTP exhibited a slightly lower degree of self-complementarity than regular short chains. The predominant labeling of short chains during pulses is, therefore, not a consequence of discontinuous growth on both sides of the replication fork. Similar results were obtained with ara-ATP and N-ethylmaleimide. The experiments indicate that ara-CTP acts primarily on DNA-polymerizing activities, affecting different DNA polymerases to varying degrees. The results are discussed in terms of the possible number and identity of polymerases involved in viral (and cellular) DNA replication. | 163,918 | [
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Temperature-sensitive host range mutants of herpes simplex virus type 2. | Herpesviruses are capable of several types of infection of a host cell. To investigate the early events which ultimately determine the nature of the virus-host cell interaction, a system was established utilizing temperature-sensitive mutants of herpes simplex virus type 2. Four mutants have been isolated which fail to induce cytopathic effects and do not replicate at 39 C in hamster embryo fibroblast cells. At least one mutant is virus DNA negative. Since intracellular complementation is detectable between pairs of mutants, a virus function is known to be temperature sensitive. However, all four mutants induce cytopathic effects and replicate to parental virus levels in rabbit kidney cells at 39 C. This suggests that a host cell function, lacking or nonfunctional in HEF cells but present in rabbit kidney cells at 39 C, is required for the replication of these mutants in hamster embryo fibroblasts cells at 39 C. Therefore, we conclude that these mutants are both temperature sensitive and exhibit host range properties. | 163,920 | [
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Hyperlipidemia in cerebrovascular diseases. | 1. Hypertriglyceridemia and hyper beta-lipoproteinemia are closely related to the pathophysiologic status of the cerebrovascular patients. 2. The electrophoretic analysis of serum lipoprotein is the usefull method for the study on hyperlipidemia in the cerebrovascular disease. 3. The electrophoretic analysis of the serum lipoprotein gives close relation to the clinical features in the patients with normal serum lipid levels as well as in those with the hyperlipidemia. 4. Hyperlipidemia relates closely to the renal impairment, which is supposed to originate from the sclerotic changes of renal artery. | 163,933 | [
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[Globular corpuscles in hepatomas of Swiss mice]. | In hapatomas formed spontaneously without cirrhosis at Swiss mice numerous globular corpuscules of eosinophil character were found. These corpuscules as revealed by electron microscopy are formed in cyternas of the rough surfaced endoplasmatic reticulum and are of the nature of protein. | 163,957 | [
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The effect of diuretics on Na+-K+-ATPase and c-AMP levels in toad bladder epithelial cells. | Na+-K+-ATPase was inhibited by 1 times 10-4M ethacrynic acid and mercuderamide, and by 1 times 10-3M hydrochlorothiazide and furosemide. A modification of Gilman's (1970) protein displacement assay has been used to measure c-AMP levels in toad bladder epithelial cells. Vasopressin (50 mU/ml) caused c-AMP levels to rise from 4.27 to 9.27 pmol/mg protein. Ethacrynic acid had no effect on cellular c-AMP levels after 10 min exposure to the drug, but at 90 min caused a reduction of both basal and vasopressin stimulated levels. Furosemide caused an apparent rise in c-AMP levels, dilution ratio measurements indicated interference by this drug in the assay procedure, mecuderamide also caused substantial interference with the c-AMP assay. Hydrochlorothiazide had no effect on basal or hormone stimulated levels of c-AMP. It was concluded that the inhibition of sodium transport produced by ethacrynic acid in toad bladder is probably due to inhibition of adenylate cyclase, an effect not shared by other dieuretics. | 163,990 | [
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Cytomegalovirus endometritis: report of a case associated with spontaneous abortion. | Maternal cytomegalovirus infection is a relatively common, yet very often silent complication of pregnancy. The association between early gestational wastage and cytomegalovirus endometritis has been documented in recent tissue culture studies without the morphologic demonstration of the virus. This case study presents the clinical and pathologic findings of a young, secundigravida female with cytomegalovirus endometritis and spontaneous abortion. The intranuclear inclusions were restricted to the endometrial glands; Involvement of the endocervix by cytomegalovirus has been the only site in the female reproductive tract, excluding fetal tissues, affected by this virus which has been demonstrated histologically. The data are still incomplete regarding the etiologic role, if any, of cytomegalovirus and the occurrence of spontaneous abortion. | 163,996 | [
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The antagonistic effect of an inhalation anesthetic and high pressure on the phase diagram of mixed dipalmitoyl-dimyristoylphosphatidylcholine bilayers. | Several workers have shown that phase transition-related changes in membrane lipids have a profound effect on membrane-solvated protein function. This phase transition temperature dependence has been explained as resulting from the formation of lateral phase separations within the membrane bilayer. The present study demonstrates that a clinical concentration of an inhalation anesthetic produces changes in both the phase transition temperature of pure lipid bilayers and the lateral phase separation temperature of mixed dipalmitoyl- and dimyristoylphosphatidylcholine bilayers of a magnitude sufficient to influence protein function. It is further shown that pressure is able to antagonize the effect of the anesthetic on these transition temperatures. It is proposed that anesthetic action within nerve membranes may be the result of changes in the lateral phase separation-controlled environment of the membrane-solvated proteins essential to nerve function. | 164,016 | [
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Competent Bacillus subtilis cultures synthesize a denatured DNA binding activity. | A protein activity has been detected in soluble extracts of competent cultures of bacillus subtilis which protects denatured DNA from nuclease solubilization. Both binding activity and competence development occur simultaneously but not coordinately, since the peak of binding activity appears 3 hr after the peak of competence. The binding activivity is not detected in physiologically noncompetent cultures, in an isogenic noncompetent cultures, in an isogenic noncompetent mutant grown through the competence regimen, or in early sporulating cells. The activity is included on Sephadex G-100 gel filtration columns but elutes in a broad nonhomogeneous peak. This binding activity may play a role in uptake of DNA and/or integration of exogenous DNA into the genome of competent B. subtilis cells. | 164,019 | [
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Effect of a low-molecular-weight DNA binding protein, H1 factor, on the in vitro transcription of the lactose operon in Escherichia coli. | H1 protein, a heat-stable low-molecular-weight DNA-binding factor previously described by Cukier-Kahn et al. [Proc. Nat. Acad. Sci USA (1972) 69, 3643-3647] markedly stimulates in vitro synthesis of lac-specific RNA directed by bacteriophage lambdah80 dlac or phi80 dlac DNA templates in the presence of purified E. coli RNA polymerase holoenzyme. The extent of stimulation obtained by addition of H1 alone is usually greater than that observed with the cAMP receptor protein-cAMP combination. H1 effect varies quite appreciably (from 4- to 16-fold) with the functional state of the promoter, being much larger with lambdah80 dlac p-s, a transducing DNA carrying a superpromoter mutation, than with lambdah80 dlac p+. H1 and cAMP receptor protein effects are nearly additive, although interpretation of the data obtained at high H1 concentration is complicated by the appearance of some inhibitory property. While the cAMP-receptor-protein-mediated synthesis is asymmetrical ("I" strand almost exclusively copied), the degree of asymmetry observed with H1 is less pronounced, suggesting asymmetrical copying from the lac promoter and symmetric transcription from other regions of the DNA. Synthesis of lac-specific RNA from lambdah80 dtrp/lac or phi80 dlac p-r uv5 templates, in which lac promoters are insensitive to cAMP receptor protein, either as a result of lac fusion to the trp operon or mutation in the lac promoter, is totally H1-insensitive. Glycerol (10-15% w/w) can fully substitute for H1 in stimulating lac RNA synthesis in a fashion analogous to that reported for the cAMP receptor protein-cAMP system. The possibility that H1 acts by causing conformational modifications at the promoter level in a way that increases its functional state, and that this effect is more pronounced with operons sensitive to cAMP receptor protein, is discussed. | 164,021 | [
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Idiopathic congenital hemihypertrophy with associated ipsilateral benign nephromegaly. | Two cases of idiopathic congenital hemihypertrophy with ipsilateral benign nephromegaly are presented. Excretory urography usually differentiates benign renal enlargement from Wilm's tumor in these patients. Angiography is indicated in equivocal cases. The clinical features, differential diagnosis, associated conditions, and importance of radiologic reevaluation in patients with hemihypertrophy are discussed. | 164,043 | [
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Angiographic signs of corpus callosal tumors: a reappraisal. | Angiographic findings of eleven corpus callosal tumors are analyzed. Three new angiographic signs are demonstration of the lateral ventricular roof veins, spreading of the septal veins, and actual demonstration of corpus callosal thickening. In contrast to traditional concepts, diagnostic abnormalities were angiographically demonstrated in all eleven cases. Biplane angiotomography is of vital importance in the angiographic diagnosis of this frequently subtle tumor. | 164,047 | [
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[Membrane antigens of Zajdela ascitic hepatoma]. | The membrane antigens of Zajdela ascitic hepatoma cells were investigated. Living cells were studied by immunofluorescence method, and solublized membrane preparations by the precipitation reacting in agar gel. Testing of the tumor cells with organospecific anti-kidney serum caused a specific fluorescence of tumor cells surface. This can be due to incorporation into the antigenic structure of the Zajdela hepatoma cell membranes of at least one organospecific antigen. Treatment of the tumor cells with organospecific anti-liver serum led to specific fluorescence of tumor cells surface. In solubilizates of the tumor cells one of the three organospecific antigens peculiar for the normal liver cells, was detected. | 164,069 | [
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Function of the fat-soluble vitamins. | Much has been learned about the function of the fat-soluble vitamins in recent years. Their mechanisms are divergent ranging from a role in transcription of DNA or differentiation to a direct enzymatic activation of the gamma-carboxylation of glutamate residues of a preexisting protein. Thus the only resemblance so far among these physiologically active agents is their lipid solubility. However, in general the fat-soluble vitamins play important roles in specialized functions carried out by highly differentiated organisms. | 164,114 | [
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Islet cell tumors of the pancreas and the alimentary tract. | Functioning tumors of the pancreatic islets are now recognized as the source of clinical syndromes affecting the gastrointestinal tract which have a wide variety of catastrophic symptoms. Experiences with thirty-six cases suggest at least four separate diagnostic categories in the ulcerogenic tumor syndrome. These include: a typical history, gastric analysis, and roentgenographic findings with boderline fasting serum gastrin levels; ulcerogenic tumor with evidence of hyperparathyroidism; iatrogenic ulcerogenic syndrome associated with failure of a previous operation for duodenal ulcer; and the classic ulcerogenic syndrome associated with a fulminating ulcer diathesis or diarrhea and high serum gastrin levels. The problems presented at operation include: decisions to be make in the presence of a negative exploration; the finding of a solitary tumor in the wall of the duodenum; solitary pancreatic tumors particularly in the body and tail; ulcerogenic tumors in the very young; liver metastases in the elderly; and the wisdom of removing gross metastases in combination with total gastrectomy. The long-term survival in the ulcerogenic tumor syndrome approximated 50 per cent, with 40 per cent of those having proved malignancy living five years. Evidence of hyperparathyroidism is relatively common in association with both the ulcerogenic and the diarrheogenic tumor syndromes. The association may by a result of a congenital abnormality, metabolic alkalosis, or a direct effect of the islet cell tumor. Parathyroidectomy may be indicated when both the serum calcium and parathormone levels are elevated in the presence of borderline fasting gastrin levels. The latter may return to normal after parathyroidectomy. The evidence of hyperparathyroidism closely parallels the episodes of diarrhea in the diarrheogenic syndrome, and hyperparathyroidism may regress spontaneously after total removal of the pancreatic tumor. Just as routine calcium determinations made the diagnosis of hyperparathyroidism more commonplace, it is suggested that the gastrointestinal syndromes associated with islet cell tumor would receive wider recognition if radioimmunoassays for gastrin as well as secretin, and the other secretin-like polypeptides, were carried out routinely. | 164,136 | [
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[Clinical considerations and genetics of the lattice dystrophy of the cornea]. | Lattice dystrophy of the cornea is reported in 4 families. For purposes of linkage analysis we did serological tests on pertinent family members, including marker testing of the blood group systems ABO, MNSs, Rh, K, Ky, and P; protein group systems Hp, Ge, Gm, and Inv; and enzyme polymorphisms SEP, PGM, ADA, and AK. | 164,138 | [
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Neuromuscular transmission in a mammalian preparation during exposure to enflurane. | The effects of enflurane on motor nerve terminals and muscle endplates were studied in the rat phrenic nerve-diaphragm preparation using standard microelectrode recording techniques. Muscle endplate interaction with enflurane was suggested by depression of the amplitude of miniature endplate potentials (MEPP's) without change in frequency, increased duration of MEPP's and endplate potentials (EPP's) increased threshold for generation of muscle action potentials, and inhibition of the endplate depolarization induced by succinylcholine. Evidence of nerve terminal effects of enflurane was limited to a greater relative decline of EPP amplitude during tetanus, indicative of failure to maintain transmitter output at rapid rates of stimulation. It is concluded that the depressant effect of enflurane on indirectly elicited muscle twitch is primarily due to an impairment of the action of muscle endplate on adjacent membrane; however, the relative importance of prejunctional depression, seen only during rapid nerve stimulation, cannot be assessed from the present data. | 164,141 | [
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Growth of SV 40, adeno 7 and SV 40-adeno 7 viruses in monkey and human cells at 29 degrees and 37 degrees C. | Adeno 7 virus replicated well in human diploid (LEP) cells but only to a low degree in green monkey kidney (GMK) cells at 37 degrees C; it did not replicate in either system at 29 degrees C. At 37 degrees C SV 40 virus replicated well in GMK cells but only moderately in LEP cells; at 29 degrees C it did not replicate in either system. SV 40-adeno 7 hybrid grew in both GMK cells and LEP cells at 37 degrees C. At 29 degrees C this virus replicated in GMK cells but not in LEP cells. While the formation of V-antigen generally corresponded to the infectious virus production in the respective system, considerable differences were encountered in the T-antigens production. Adeno 7 T-antigen was detected earlier and in a higher percentage of GMK cells than in the fully permissive LEP cells and its formation was only slightly influenced by the incubation temperature. SV 40 T-antigen was more efficiently formed in GMK cells than in LEP cells. At 29 degrees C SV 40 T-antigen was only found in GMK cells and was detected later than at 37 degrees C. The difference in the formation of SV 40 T-antigen in GMK cells infected with SV 40 and SV 40-adeno 7 hybrid virus was further analyzed. The results obtained suggest that an early step of the virus-cell interaction, but neither virus attachment nor penetration, was involved. | 164,162 | [
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Experimental egg-transmission of avian reovirus. | Two experiments with an avian reovirus (FDO isolant), serologically identical to the Fahey-Crawley and WVU 2937 isolants, provided conclusive proof that egg-transmission can occur. In the first experiment, 4-day-old chicken embryos were inoculated into the yolk sac with serial dilutions of virus and subsequently hatched. High virus doses killed all embryos, whereas low doses (14 or less plaque-forming units) allowed some embryos to hatch normally although infected. In the second experiment, virus was administered by the nasal, esophageal, and tracheal routes to twenty 15-month-old breeders. Eggs from -6 to 21 days and 58 to 64 days postinoculation were incubated. Three newly hatched chicks from eggs laid on successive days (17, 18, and 19 days postinoculation) and one infertile egg (61 days postinoculation) were found infected. Active infection, as judged by virus isolations from cloacal swabs, was over by the 17th day postinoculation. | 164,174 | [
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Evidence for glucocorticoid transport into AtT-20/D-1 cells. | Glucocorticoid uptake by AtT-20/D-1 mouse pituitary adenocarcinoma cells grown in tissue culture was examined. The binding of triamcinolone acetonide, a potent synthetic glucocorticoid, by intact cells and by cell cytosol was studied at both 4 and 25 degrees. Specific binding of [3H]triamcinolone acetonide by intact cells was markedly different from cell-free cytosol binding at 4 degrees. Intact cells bound a relatively small amount of labeled steroid within 2 min, after which no further binding was observed. In contrast, the receptor in a cell-free cytosol preparation was capable of binding steroid progressively at 4 degrees, indicating that the limited binding by intact cells was not a consequence of receptor characteristics. At 25 degrees, uptake by intact cells and cytosol was nearly identical and appeared to be limited only by the binding kinetics of the cytosol receptor. Estradiol-17 beta, a nonglucocorticoid steroid, was not bound by the AtT-20/D-1 cell at 4 degrees. Triamcinolone was not bound significantly at 4 or 25 degrees by an adrenal carcinoma cell that does not appear to be a glucocorticoid target cell. An Arrhenius plot of cell steroid uptake vs. the reciprocal of absolute temperature revealed an abrupt change in slope at 16 degrees, which is compatible with the temperature-dependent mechanism involved in glucocortidoid uptake being associated with lipid constituents of the cell membrane. These data suggest that glucocorticoid uptake by this target cell involves a mechanism of specific, temperature-dependent transport through the cell membrane. | 164,213 | [
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Stimulus-secretion coupling in platelets. Effects of drugs on secretion on adenosine 5'-triphosphate. | The mechanism of stimulus-secretion coupling in platelets was investigated by observing the effects of drugs on the kinetics on ATP secretion induced by either thrombin or the divalent cation ionophore A23187. The actual secretion is the same with either of these agents, since the rate constants and activation energies of secretion are the same and since drugs that affect the final, enzyme-independent steps of thrombin-induced secretion have the same effect on ionophore-induced secretion. Drugs that affect early steps of thrombin-induced secretion have no effect on ionophore-induced secretion. Drugs that act through cAMP (PGE1, theophylline, dibutyryl-cAMP) slow an early step in the mechanism of thrombin-induced secretion and completely block at higher levels, with the required concentration of inhibitor dependent on thrombin concentration. The inhibition of rate appears to be all-or-none, with no intermediate rates observed. By replacing thrombin with trypsin, which makes it possible to observe a complete change in rate-determining step from an enzyme-dependent to an enzyme-independent platelet step, it was found that these drugs slow the rate only when the enzyme-independent step is rate determining. These drugs have no effect on A23187-induced secretion. It was concluded that cAMP inhibits at a step after the enzyme step but before the final step by interfering with transmission of the stimulus-secretion coupling signal. Disruption of microfilament function by cytochalasin B (10 muM) accelerates the rate of secretion induced by either thrombin or ionophore. The microtubule agents colchicine, vinblastine, and vincristine had effects only at concentrations above those usually considered necessary for the specific inhibition of microtubule function. Drugs that inhibit prostaglandin synthesis (aspirin, indomethacin, eicosatetraynoic acid), drugs that block ATP production (antimycin A, deoxyglucose), or several other drugs previously reported to inhibit platelet function had no effect on secretion. | 164,214 | [
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Cold inactivation of glyceraldehyde-phosphate dehydrogenase from rat skeletal muscle. | Inactivation of apo-glyceraldehyde-phosphate dehydrogenase (D-glyceraldehyde-3-phosphate: NAD+ oxidoreductase(phosphorylating) (EC 1.2.1.12) from rat skeletal muscle at 4 degrees C in 0.15 M NaC1, 5 mM EDTA, 4 mM 2-mercaptoethanol pH 7.2 is a first-order reaction. The rate constant of inactivation depends on protein concentration. With one molecule of NAD bound per tetrameric enzyme, a 50 per cent loss in activity is observed and the rate constant of inactivation becomes independent of the protein concentration over a 30-fold range. Two moles of NAD bound per mole of enzyme fully protect it against inactivation. NADH affords a cooperative effect on enzyme structure similar to that of NAD. Inactivation of 7.8 S apoenzyme is reflected in its dissociation into 4.8-S dimers. In the case of enzyme-NAD1 complex, no direct relationship between the extent of inactivation and dissociation is observed, suggesting that these two processes do not occur simultaneously; we may say that dissociation is slower than inactivation. A mechanism in which the rate-limiting step for inactivation is a conformational change in the tetramer occurring prior to dissociation and affecting only the structure of the non-liganded dimer, is consistent with the experimental observations. Inorganic phosphate protects apoenzyme against inactivation. Its effect is shown to be due to the anion binding at specific sites on the protein with a dissociation constant of 2.6 plus or minus 0.4 mM. The NaC1-induced cold inactivation of glyceraldehyde-phosphate dehydrogenase is fully reversible at 25 degrees C in the presence of 20 mM dithiothreitol and 50 mM inorganic phosphate. The rate of reactivation is independent of protein concentration. Inactivated enzyme retains the ability to bind specific antibodies produced in rabbits, but diminishes its precipitating capability. | 164,222 | [
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Non-allosteric regulation of the uridine kinase from seeds of Zea mays. | Uridine kinase (ATP: uridine 5'-phosphotransferase, EC 2.7.1.48) has been partially purified from ungerminated hybrid corn seed. It is associated with a soluble high molecular weight fraction from which it apparently cannot be dissociated without loss of activity. The stability of the enzyme is enhanced by the addition of dithiothreitol, glycerol and nucleotide substrate. The nucleoside specificity of the enzyme is limited to nucleosides containing pyrimidine and ribose moieties, such as uridine and cytidine. High concentrations of nucleosides cause substrate inhibition, however. The Km values for uridine and cytidine are 53 muM and 125 muM, respectively, and under subsaturating conditions uridine is phosphorylated about five times faster than cytidine. The reaction follows an ordered Bi Bi kinetic pattern, with ATP and ADP in competition for the free form of the enzyme. Purine, but not pyrimidine, nucleoside triphosphates serve as phosphate donors without regard to the sugar moiety. However, all of these triphosphates appear to compete for the same site on the enzyme. (Km ATP equals 590 muM, Km (app) GTP equals 61 muM, and CTP and UTP are linear competitive inhibitors against ATP, with Ki values of 60 muM and 240 muM, respectively.) Therefore, end product control of uridine kinase apparently does not involve allosteric sites, but instead is envisioned as simple competition between relatively effective or ineffective phosphate donors for a position on the enzyme. | 164,226 | [
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The removal of cholesterol from aortic smooth muscle cells in culture and Landschutz ascites cells by fractions of human high-density apolipoprotein. | Ascites cells were labeled by intraperitoneal injection of [3H]cholesterol and aortic smooth muscle cells by addition of [3H]cholesterol to the serum component of the culture medium. The release of cholesterol from cells into a serum-free medium supplemented with the various "acceptors" was studied using ascites cells in suspension and aortic smooth muscle cells in a multilayer culture. Unfractionated human high-density apolipoprotein was somewhat more effective in the removal of labeled cellular free cholesterol, in both cell types, than apolipoprotein derived from rat high-density lipoprotein. Following separation of human high-density apolipoprotein into four fractions by Sephadex chromatography, the effect of each fraction on the removal of cellular cholesterol from ascites cells was studied. The individual fractions had a lower capacity for cholesterol removal than the original unfractionated high-density apolipoprotein and the lowest activity was detected in Fraction II which comprised 75% of the total apolipoprotein. The effectiveness to remove cholesterol could be restored to all the fractions, as well as enhanced, by addition of sonicated suspensions of lecithin or sphingomyelin, which by themselves promoted a more limited removal of cellular cholesterol. Negatively stained preparations of mixtures of the four fractions and sonicated dispersion of lecithin were shown to consist of vesicles and discs of various sizes. Addition of the apolipoprotein fractions (especially Fractions II and IV) to sonicated dispersion of sphingomyelin resulted in a pronounced formation of discs which showed a high tendency towards stack formation. Mixtures of Fraction II and lecithin or sphingomyelin were effective in the release of cellular cholesterol from multilayers of aortic smooth muscle cells in culture. These results show the feasibility of net removal of cholesterol from cells which grow in a form resembling a tissue and thus provide a model to study the role of apolipoprotein-phospholipid mixtures in cholesterol removal from cells and tissues in vivo. | 164,235 | [
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Solubilized DNA-dependent nuclear RNA polymerases from the mammary glands of late-pregnant rats. | Mammary gland nuclear extracts from late-pregnant Wistar or Sprague-Dwaley rats, analyzed by DEAE-Sephadex chromatography, were found to contain DNA-dependent RNA polymerases, cyclic nucleotide-binding proteins, and cyclic AMP-independent protein kinases. 1. The fractions from chromatographed nuclear extracts which contained nucleolar enzymes or nucleoplasmic enzyme II, bound radioactive cyclic AMP and cyclic GMP. Other fractions also bound cyclic nucleotides, some preferentially associating with one or the other compound. 2. Cyclic AMP increased the amount of RNA formed by several alpha-amanitin-insensitive fractions containing nucleolar enzymes. 3. Cyclic AMP reduced the amount of RNA formed by column fractions which included nucleoplasmic enzyme II. 4. Cyclic GMP increased the amount of RNA synthesized by column fractions containing enzyme II. 5. Two major cyclic AMP-independent protein kinases which did not elute with enzymes Ib and II, and several minor protein kinases were present. These findings may have important implications for understanding the proximate control of transcription. A relationship between them is not established, but is under study. | 164,243 | [
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The interaction of estradiol-receptor protein with the genome: an argument for the existence of undetected specific sites. | In extracts from rat and calf uterus, the steroid hormone 17 beta-estradiol stimulates the binding of its specific receptor protein to DNA. This interaction appears to be of low affinity (half of the estradiol-activated, 5S receptor bound at 300-400 mug/ml DNA) and nonspecific with respect to DNA base sequence. No binding to double-stranded RNA is observed. These findings are consistent with several in vivo observations. In particular, when the cytoplasmic receptor protein binds hormone, it migrates to the cell nucleus to an extent consistent with its affinity for DNA in vitro, and this in vivo nuclear binding is uniform and nonsaturable in the testable range (to greater than 3 times 10-4 sites per cell). The level of biological response appears to parallel the hormone dose up to these high levels of receptor binding. How are these observations to be reconciled with the prevalent view of steroid receptors as gene control proteins regulating transcription at specific loci on the genome? Our model is based on an analogy with the DNA binding properties of the E. coli lac repressor protein. We believe that the estradiol receptor exerts its effect by binding to a small number of high affinity sites on the genome, while also having a finite low affinity for nonspecific DNA sequences. These nonspecific loci, because of their vast number, completely mask the presence of the high affinity sites. We estimate that up to 10-3 specific sites, with affinities in the range 10- minus 8 minus 10- minus 10 M, could exist without being detected by bulk binding assays currently in use. However, alternative approaches should allow detection of these sites, and some of these are suggested. | 164,290 | [
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Effect of PGE1 and TSH on cAMP-dependent protein kinase activity in the thyroid. | PGE1, like TSH, can increase cAMP-dependent protein kinase activity in calf thyroid slices. The intracellular levels of cAMP produced by either of these agents alone appeared to correlate well with the degree of kinase activation. PG synthesis did not appear to be necessary for TSH action in this system, since indomethacin, and inhibitor of prostaglandin synthesis, did not alter either cAMP levels or kinase activity in slices incubated with TSH. Both the cAMP level and kinase activity rose when a submaximally effective dose of TSH was added to a maximal dose of PGE1. However, neither the cAMP levels nor the kinase activity produced by a maximal dose of TSH was affected by the addition of PGE1. | 164,339 | [
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Effect of Ricinus communis toxin on cyclic adenosine 3':5'-monophosphate metabolism in Yoshida ascites sarcoma cells. | Prostaglandin E1 (2.5 mug/ml) enhanced the level of cyclic adenosine 3':5'-monophosphate (cyclic AMP) three to four times in Yoshida ascites sarcoma (YS) cells cultured in vitro. When Ricinus communis toxin (RC-toxin) was added 30 min after the addition of prostaglandin E1, the enhanced level of cyclic AMP in the YS cells decreased rapidly. Of RC-toxin, 0.2 mug/ml was enough to produce the maximum effect. By addition of 5 mM lactose with RC-toxin, approximately 60% of the RC-toxin effect on the levels of cyclic AMP was abolished. This indicates that the specific binding of RC-toxin on the surface membrane is largely responsible for the observed decrease of the cyclic AMP level. The toxin treatment did not induce either leakage of cyclic AMP from the cell or change in the activity of cyclic AMP phosphodiesterase. However, the treatment of YS cells with RC-toxin caused a decrease of adenylate cyclase activity when the activity was measured at a substrate concentration of 0.15 mM ATP. In contrast, there was little difference with the control when the activity was assayed at a higher ATP concentration, 0.24 mM. It was found that the K-m of adenylate cyclase for ATP was changed by RC-toxin from 0.1 to 0.25 mM, and that the Mg2+ activation of the enzyme observable in untreated cells disappeared. These results suggested that the decrease in the level of cyclic AMP in YS cells induced by RC-toxin can be explained in terms of the change in K-m of the adenylate cyclase activity. | 164,448 | [
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Selective retention and formation of a delta5-androstenediol-receptor complex in cell nuclei of the rat vagina. | Cellular protein binding of a number of androstene and androstane derivatives that promote the growth of the vagina in rats has been studied. It was found that cell nuclei of the rat vagina contain a tissue-specific protein that binds 3beta,17beta-dihydroxy-androst-5-ene (delta5-androstenediol), a unique steroid causing growth and keratinization of the vaginal epithelium. The formation of the steroid-protein complex can be demonstrated by the administration of delta5-[3H]androstenediol to ovariectomized rats or by the incubation of minced vagina with the radioactive steroid. The steroid can interact with purified vaginal cell nuclei even in the absence of a cytosol preparation, forming the same steroid-protein complex. The formation of the complex is temperature-dependent; it occurs much more readily at 37 degrees than at 0 degrees. The delta5-[3H]androstenediol-protein complex migrated as about 4 S in a sucrose gradient medium containing 0.4 M KCl. A similar complex can be detected when nuclei of vaginal cells are incubated with 3alpha,17beta-dihydroxy-5alpha-androstane, 3beta,17beta-dihydroxy-5alpha-androstane, and 3beta-hydroxy-androst-5-en-17-one which also have the capability of stimulating vaginal epithelium, although in somewhat different ways. These steroids may bind to different groups of chromatin-bound receptor proteins in various layers of vaginal epithelium. The delta5-androstenediol binding protein is not found in the vaginal cytosol fraction that contains receptor proteins for estrogens and progestins, nor in the cytosol or nuclei of rat uterus cells, but not in muscle, brain, kidney, or liver. Testosterone and 5alpha-dihydrostestosterone bind weakly to the protein, whereas cortisol, androstenedione, 17beta-estradiol, and progesterone do not bind to the same protein by any significant extent. | 164,458 | [
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Vasopressin-sensitive kidney adenylate cyclase. Structural requirements for attachment to the receptor and enzyme activation: studies with vasopressin analogues. | Several vasopressin analogues were tested on pig kidney membranes for their ability to activate adenylate cyclase and to inhibit the binding of [8-lysine]vasopressin. Both the adenylate cyclase activation and hormonal binding were measured on the same enzyme preparation and under identical were measured on the same enzyme preparation and under identical experimental conditions. A preincubation period in the presence of hormone allowed the binding process to reach equilibrium. Peptide concentrations causing half-maximal adenylate cyclase activation (apparent Km) were, in the order of decreasing affinity:2.5 to 7.0 to 7.0 times 10-10 M [8-lysine] vasopressin, 3.1 to 4.0 times 10-9 M [8-arginine] vasopressin, 2.0 to 3.0 times 10-9 M [I,6-alpha-deaminocystathionine, 8-ornithine]vasopressin, 3.1 times 10-7 M des-9-glycineamide[8-lysine]vasopressin, 0.5 to 1.0 times 10-6 M[1,6-alpha-deaminocystathionine, 2-0-tert... | 164,461 | [
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... |
Properties of a subpopulation of T cells bearing histamine receptors. | C57BL/6 mice immunized i.p. with alloantigen (P815 mastocytoma cells) develop cytolytically active thymus-derived (T) splenic lymphocytes. The definition of specific histamine receptor sites on effector T cells has been studied by measuring the in vitro effects of the hormone on cytolytic activity. Histamine was found to inhibit cytolysis reversibly and to increase lymphoid cell cyclic AMP levels. Both of these histamine activities were reversed by burimamide and metiamide; neither activity was affected by diphenhydramine or pyrilamine. These findings indicate that modulation of effector T cell activity by histamine is mediated only by one of the subtypes of tissue histamine receptors, designated a histamine-type 2 receptor. This receptor appears to be present on cytolytically active cells; there is no evidence for activation by histamine of auxiliary or "suppressor" cells. The estimated dissociation constant (KB) for the burimamide-receptor complex (9 times 10-minus 6 tm) and for the metiamide-receptor complex (8 times 10-minus 7 M) indicated that the histamine receptor on T cells is quite similar to histamine-type 2 receptors in other tissues. Cells bearing such receptors could not be isolated by passage through a column of histamine-coated tsepharose beads. The cytolytic activity of spleen cells taken from mice early (days 7-9) after immunization is virtually unaffected by histamine in vitro. In contrast, the activity of spleen cells taken from mice later in the immune response is progressively more susceptible to inhibition by histamine. After reaching a maximum at day 11, the spleen cell cytolytic activity falls in a pattern that parallels the increase in susceptibility to histamine. The susceptibility of effector T cells to histamine appears also to reflect their site of origin, for peritoneal exudate effector cells were found to be significantly less sensitive than spleen cells to inhibition by histamine. The progressive increase in inhibition by histamine apparently reflects the appearance of greater numbers of specific histamine-type 2 receptors, and is probably a general phenomenon, for spleen cells from A/J or C3H mice immunized with either P815 mastocytoma (H-2d) or EL-4 (H-2b) cells showed the same effect. However, the appearance of histamine receptors could be altered by prior immunization with an unrelated alloantigen: thus, when A/J mice are preimmunized with EL-4, a subsequent immunization with mastocytoma cells results in peak spleen anti-H-2d activity at day 9 instead of days 11-13, and the appearance of significant (greater than 40 percent) inhibition by histamine as early as day 8 instead of day 16. The physiological role of the histamine receptors is as yet undefined, though their unexpected rate of appearance on effector T cells, coincident with a decline in the number of lytically active cells in vivo, may be a significant hint that hormone receptors play a role in the control of T-cell proliferation. | 164,483 | [
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Effect of adrenocorticotropic hormone on conditioned avoidance in rats interpreted as state-dependent learning. | Rats were given one training trial that was followed 2 days later by one test trial in a "step-out" passive avoidance task. Each rat was injected with either adrenocorticotropic hormone (ACTH) or placebo before training and before testing. Four groups of rats were used, representing the 4 possible training-testing injection combinations: placebo-placebo, placebo-ACTH, ACTH-placebo, and ACTH-ACTH. ACTH given in testing increased avoidance for subjects that had received ACTH in training and decreased avoidance for those that had received placebo in training. | 164,488 | [
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Respiratory viral infection in childhood. A survey in general practice, Roehampton 1967-1972. | The role of viruses and M. pneumoniae in episodes of acute respiratory illness in childhood has been studied in a London general practice. The total isolation rate was 31-7 per cent, but the rate varied from 32-6 per cent in upper respiratory infections to 64-0 per cent in pneumonia. The clinical features associated with infection were influenced not only by the type of agent but also by age and other host factors in infected children. Rhinoviruses were more commonly isolated than any other agent and were frequently associated with wheezy bronchitis. | 164,499 | [
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Sero-immunity to poliovirus in children and young women: England 1972-4. | A total of 292 children's sera and 706 antenatal sera from different parts of England were tested for the presence of poliovirus neutralizing antibodies. Little vairation was found between different areas and types of community, but a lower porportion of the 5-14 year old children had antibody than younger children and young adult women. The proportion of the young population with antibody, and the current acceptance rates for oral poliovirus vaccine are barely satisfactory. | 164,503 | [
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Congenital granular-cell myoblastoma. | The clinical and pathologic features of congenital granular-cell myoblastoma in five infant girls are reported. One lesion, treated expectantly, progressively decreased in size and after 3 yr and 9 mo could not be detected, while two lesions which were imcompletely excised did not recur. It is suggested that congenital granular-cell myoblastoma is caused by an intrauterine stimulus, and that this stimulus may possible be production of estrogen by the fetus. Congential granular-cell myoblastoma should be treated expectantly or by limited excision, and has an excellent prognosis. | 164,527 | [
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Nursing staff training for an effective geropsychiatric environment. | In describing an early training program of the Gerontological Manpower Project, we have attempted to demonstrate that short-term, on-site training with a frim theoretical and empirical base, can be an effective vehicle for translating research into application. In this case, research and theory based on the importance of the environment as therapeutic, and directed to maximizing geriatric patient independence was incorporated into a geriatric training programmthis was delivered to personnel working with the elderly in two institutional settings, differing in geriatric patient population and service orientation. To improve the effectiveness of future training programs, extensive evaluative research was included in the training processes. Although results were predictably tentative, they did yield much useful information both for subsequent program design as well as reinforcing a need for this process itself. Finally, a very satisfying and beneficial result of this project, as specified by the research staff and all participants, is that effective application of research results via appropriate training mechanisms are easily within reach of the nurse-practioner, and the oft-desired bridge between academia and the service delivery system is truly a collaborative reality. | 164,539 | [
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Stimulation of protein synthesis in vivo in immature mouse testis by FSH. | Human pituitary FSH was found to increase the incorporation of tritiated lysine into testicular protein in prepubertal mice in vivo. Radioactivity was measured in washed trichloracetic acid precipitates prepared from crude testicular homogenates. The time of maximum response was 8 to 16 hr after subcutaneous injection of the hormone. This was considerably later than the maximum response in vitro reported by other workers. Neither HCG nor dibutyryl cyclic 3',5'-adenosine monophosphate had a significant effect on the incorporation of lysine. | 164,545 | [
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Implantation in ovariectomized mice treated with dibutyryl adenosine 3',5'-monophosphate (dibutyryl cyclic AMP). | Experiments are described that demonstrate that uterine intraluminal injection of a 1-25 mM-solution of dibutyryl cyclic AMP (dcAMP) in phosphate buffered saline (PBS) induced implantation in ovariectomized pregnant mice. Pretreatment with progesterone was essential for this effect. When PBS was injected alone, it did not induce implantation in mice treated with progesterone. Bilateral adrenalectomy had no effect on the ability of dcAMP to substitute for oestradiol, showing that the effect was not due to dcAMP-induced oestrogen synthesis in the adrenal cortex. It is suggested that the dcAMP may act at the level of the uterus, the embryo, or both. | 164,548 | [
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Potential inhibitors of L-asparagine biosynthesis. 2. Chemistry and biological activity of beta-hydroxyaspartic acid and its derivatives. | Several derivatives of erythro-beta-hydroxy-DL-aspartic acid (1) were prepared as a potential inhibitors of L-asparagine synthetase (ASase) from rat Novikoff hepatoma. Benzylation of 1 gave the dibenzyl ester 2 which upon coupling with carbobenzoxyglycine afforded the blocked dipeptide 3. Deblocking of 3 gave glycl-erythro-beta-hydroxyl-DL-aspartic acid (4) which could not be diazotized. The dimethyl ester of 1 was coupled with carbobenzoxyglycine to give the blocked dipeptide 7a which was deblocked to give dimethyl glycel-erythro-beta-hydroxy-DL-aspartate hydrochloride (8). Diazotization of 8 gave impure diazo compound 9 which on reaction with HCl gave the chloro compound 10. The methods of isolation, assay, and inhibition of ASase are discribed. At 10 mM concentrations 10, 1, and its D and L enantiomers inhibit ASase by 45, 47, 36 and 66 percent, respectively. | 164,550 | [
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Distinction between Duchenne and other muscular dystrophies by ribosomal protein synthesis. | Ribosome concentration, ribosome distribution on sucrose density gradients, and in-vitro ribosomal amino-acid incorporation (noncollagen and collagen synthesis) were studied in muscle biopsy samples obtained from 30 patients with Duchenne muscular dystrophy, seven patients with Becker muscular dystrophy, and 10 with facioscapulohumeral muscular dystrophy. Ribosome concentration was normal in Duchenne and facioscapulohumeral and decreased in Becker muscular dystrophy. Distribution of ribosomes in sucrose density gradients showed abnormalities (sharp monosomal peak and fewer polyribosomes) only in Duchenne muscular dystrophy and was normal in the other two types. In-vitro amino-acid incorporation of ribosomes in Duchenne muscular dystrophy revealed high collagen and low noncollagen synthesis of the heavy polyribosomes. This abnormality is controlled by an undetermined enzymatic factor belonging to the soluble enzyme fraction. Supplementation of the dystrophic heavy polyribosomes with normal soluble enzymes restored the synthesis of collagen to that of the controls. Heavy polyribosomes extracted from normals or from carriers produce proportionately more collagen in the presence of soluble enzyme fraction from Duchenne muscular dystrophy than in the presence of their homologous enzymes. In Becker muscular dystrophy, both noncollagen and collagen synthesis of the heavy polyribosomes were increased, under the influence of ribosomal factors. The different protein synthesis in Duchenne and Becker muscular dystrophies suggests that these conditions are non-allelic. In facioscapulohumeral muscular dystrophy the changes in protein synthesis occurred only in the early stage of the disease and consisted of increased noncollagen synthesis of the light polyribosomes, while the heavy polyribosomes had normal activity including collagen synthesis. This reaction was controlled by ribosomal factors. | 164,552 | [
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Isolation and characterization of the plasma membrane from Yoshida hepatoma cells. | Plasma membranes isolated from Yoshida ascites hepatoma AH-130 by a modification of the method of T.K. Ray (Biochim. Biophys. Acta 196:1, 1970), were subfractionated into three fractions having densities (d) 1.12, 1.14 and 1.16 by discontinuous sucrose density-gradient. Membrane subfractions were characterized by electron-microscopy, by assay of marker enzymes and by lipid composition. All subfractions appeared to be essentially free from whole mitochondria, lysosomes and nuclei. Subfraction d 1.16 had the highest 5'-nucleotidase, Mg++-ATPase and (Na+ +K+)-ATPase activities; cytochrome c oxidase was undetectable in any fraction and glucose-6-phosphatase was measurable only in fraction d 1.14 and 1.16. Cyclic AMP phosphodiesterase was nearly equally distributed in the fractions. Adenylate cyclase, 5'-nucleotidase and Mg++-ATPase activities of tumor membrane were lower with respect to liver plasma membrane, while cyclic AMP phosphodiesterase and (Na" +K+)-ATPase were found to have similar activities in the two membrane preparations. With respect to liver membrane, hepatoma membrane contained a higher amount of glycolipids and a higher amount of phospholipids accounted for mainly by sphingomyelin, phosphatidylserine and phosphatidic acid. The possible significance of the decrease of adenylate activity in the hepatoma membrane is briefly discussed. | 164,555 | [
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Primary tissue culture of human wart-derived epidermal cells (keratinocytes). | The formation of human skin warts may depend on transformation by human papilloma virus or result from a productive virus infection. To explore this problem, methods were developed for the primary tissue culture of epidermal cells (keratinocytes) derived from wart tissues and normal skin. Wart-derived keratinocytes continued to proliferate for periods exceeding 3 months, but the patterns of cell growth were identical to normal keratinocytes. Electron microscopic and immunohistologic examination of wart-derived cultures did not evidence virion assembly. | 164,558 | [
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[Synthetic depot-ACTH, plasmacortisol levels, and asthmatic syndrome (author's transl)]. | Plasmacortisol levels were measured in 33 patients with asthmatic syndrome before and after they received treatment with 6 mg of depot-ACTH (Tetracosactid) over seven days. 75 percent of the patients showed improved VC and FEF after therapy. This effect was not in any way correlated to the basal level of cortisol, nor to the increment during treatment. | 164,616 | [
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Plasma lipids and lipoproteins in vegetarians and controls. | The possible effect of diet on plasma lipids was investigated in a group of vegetarians. Seventy-three men and 43 women who had adhered to a vegetarian diet for an average of three years were studied in the fasting state and compared with a randomly selected group of controls matched for age and sex. Mean cholesterol levels in milligrams per deciliter for vegetarians and controls, respectively, were 126 and 184; low-density lipoprotein, 73 and 118; very-low-density lipoprotein, 11.8 and 17.2; high-density lipoproteins, 42 and 49; and mean triglyceride levels 59 and 86. Mean weight and subscapular skinfold thicknesses were 58 kg and 6 mm for vegetarians and 73 kg and 17 mm for controls. Similar differences in lipid levels were found between subgroups of 42 vegetarians and controls with identical mean weights. Multiple regression analyses showed that consumption of dairy foods and eggs, but not body weight, was associated with the lipoprotein and cholesterol findings. | 164,628 | [
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Demonstration that monocytes rather than lymphocytes are the insulin-binding cells in preparations of humah peripheral blood mononuclear leukocytes: implications for studies of insulin-resistant states in man. | Insulin receptors have been demonstrated on mononuclear leukocytes prepared by centrifugation of buffy coats from normal blood donors on Ficoll-Hypaque gradients. The cell type that specifically binds insulin in this mixture of lymphocytes and monocytes has never been clearly identified, although it was assumed to be the lymphocyte since this cell constitutes about 80% of the population. In the present studies, insulin-binding assays were performed on the mononuclear leukocyte preparation before and after selective depletion or enrichment for monocytes using glass wool or Sephadex G-10 adherence columns. The amount of 125-I-labeled insulin specifically bound correlated significantly with the number of monocytes but not with the number of B or T lymphocytes. Approximately 90% of the specific insulin binding of this preparation could be accounted for by its content of monocytes. The amount of binding was unaffected by phagocytosis of latex particles or by metabolic inhibitors added to prevent endocytosis. Autoradiograms made on smears of whole peripheral blood and mononuclear leukocytes demonstrated that all of the cells that bound 125-I-labeled insulin were large mononulcear cells, 85-90% of which could be identified as monocytes by morphological criteria or by the functional criterion of latex particle ingestion. Since insulin receptor concentration may be altered in disease states in man, it is essential, when using this cell population for detecting such changes, to quantitate the number of monocytes in the preparation so that the insulin-binding data can be appropriately interpreted. | 164,655 | [
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Translation of Rous sarcoma virus RNA in a cell-free system from ascites Krebs II cells. | The template activities of the 60-70S RNA complex and of the 30-40S subunit RNA species of Rous sarcoma virus were tested in a cell-free protein-synthesizing system from mouse ascites Krebs II cells. Stimulation of protein synthesis over the endogenous background was about 2-fold with 30-40S viral RNA and about 1.3-fold with 60-70S viral RNA as template. Analysis by sodium dodecyl sulfate-gel electrophoresis showed that the predominant polypeptide synthesized in vitro in response to 30-40S RNA of Rous sarcoma virus had a molecular weight of 75,000-80,000. This polypeptide could be precipitated by antiserum against the group-specific antigens of the virus, although its molecular weight is higher than that of virion group-specific antigen proteins. Analysis of tryptic digests of the protein made in vitro indicates similarity to tryptic digests from authentic virion group-specific proteins. It is concluded that part of the RNA from Rous sarcoma virus is translated in vitro into a high-molecular-weight protein, perhaps a precursor of the virion group-specific proteins. | 164,661 | [
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Decrease in membrane-associated actin of fibroblasts after transformation by Rous sarcoma virus. | The actin content of membranes prepared from cultured chick embryo fibroblasts has been measured on polyacrylamide gels. The actin was identified by tryptic peptide mapping. After transformation of the cells by Rous sarcoma virus, the amount of actin associated with the membranes is decreased by 30-50%. This result is not due to infection per se, since infection by a temperature-sensitive strain of the virus decreases membrane-associated actin only at the permissive temperature. A shift from the nonpermissive (41 degrees) to the permissive (36 degrees) temperature results in an increase in the percentage of total cellular protein synthesis devoted to actin production, so that the decrease in membrane-associated actin appears to be a selective displacement from the membrane rather than a general decrease in total cellular actin. | 164,667 | [
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Influence of altering total body sodium on angiotensin I systemic converting activity (38573) | Studies were carried out in the dog to determine the extent to which alterations in total body sodium influence the systemic conversion of angiotensin 1. When the animals were maintained on a high salt diet and DOCA, conversion of angiotensin I increased signifcantly and returned to control levels when a normal salt diet was provided. When another group of animals were provided a low salt diet and mercuhydrin, angiotensin I conversion decreased significantly, although returning the animals to a normal salt diet had no further influence upon conversion. These experiments indicate that there is a direct relationship between total body sodium and the systemic conversion angiotensin 1. | 164,672 | [
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The effect of triazolam on the sleep of insomniacs. | The effects of three oral doses of bedtime triazolam (0.25 mg, 0.5 mg, and 1.0 mg) a new benzodiazepine, on the laboratory sleep of insomniacs were studied in a double blind design which used the following 14 consecutive night schedule: 1-4 placebo; 5-11 drug; 12-14 placebo. Effects on sleep were measured objectively by conventional EEG/EOG/EMG sleep recordings and subjectively by questionnaires administered each morning. Side or toxic effects were assessed by screening physicals and questionnaires administered each morning and each evening and by a comparison of the prestudy vs. end-study physical exams and clinical lab tests. At the 0.5 mg dose triazolam significantly reduced several objective and subjective measures of insomnia. It had lesser effects at the 0.25 mg dose and equal or greater effects at 1.0 mg dose. There were no remarkable side or toxic effects at any dose. | 164,680 | [
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Somatic hybridization and oncogenesis; (Mechanism of formation of malignant tumors and metastases by the action of antilymphocytic serum). | The results of experiments carried out to test some of the consequences of the earlier general theory of oncogenesis, according to which the malignant tumor cell can arise as a result of somatic hybridization of cells of different organ- and tissue-specificity, are described. In the first series a tumor induced by cellophane film, was grafted into syngeneic and allogeneic mice, and antilymphocytic serum (ALS) was then injected. Metastases occurred only in allogeneic recipients receiving ALS. It was thus shown that the ability of cells of this particular tumor to metastasize is not a property inherent in its cells but is acquired by them as a result of interaction with the recipient organism. In the second series it was shown by two immunological methods that the cells of metastases arising under these conditions contain tissue compatibility antigens of donor and recipient origin, i. e., that they are somatic hybridsmin the third series skin from individuals of another strain was grafted on to mice and ALS was injected; hepatomas developed in 74% of these mice. The theory is used to explain several phenomena of carcinogenesis not explicable by other theories: the phenotypic nature of cell transformation, the causes and nature of the duration of the latent period of tumor development, the mechanism responsible for the ability of tumors to overcome the system of immunological defense, the mechanism of activation of endogeneous oncogenic viruses, etc. Finally an answer is given to the question: what is a tumor? | 164,699 | [
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[Isolation of intact liver parenchymal cells by a modified enzymatic method]. | An enzymatic method is described for isolating intact parenchymal cells from rat livers. 3--4 g cells (wet weight) could be isolated from livers of rats weighing 180--230 g. After an in vitro preperfusion of 15 minutes with a Ca-free buffer, collagenase (200 mg/1) and calcium chloride (5.2 mmol/1) were added. Perfusion was continued for another 15 minutes at 37 degrees C. Micromorphological integrity of cell membranes was demonstrated by scanning electron microscopy. With regard to rates of gluconeogenesis and protein synthesis, parenchymal cells isolated according to our method were found to be superior to liver slices and cells isolated by other methods. Ratios of ATP/ADP (5.69) and of lactate/pyruvate (8.64) as parameters of the energetic situation and the redox state resp. were found within the physiological range. Integrity of cell surface receptors was proved by their sensitivity to epinephrine, glucagon and insulin. Glucagon (0.3 mumol/1) and epinephrine (1 mumol/1) and reduced glycogen deposition in hepatocytes of fasted rats by 84.9 % and 95.9 % resp. Both hormones stimulated glycogenolysis in parenchymal cells of fed rats to a similar extent. Urea synthesis was stimulated 29.5 % by glucagon (1 mumol/1), and inhibited 28.0 % by insulin (10 nmol/1). The stimulatory effect of glucagon (1 mumol/1) was abolished by insulin (10 nmol/1). | 164,741 | [
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Morphological observations of dysplastic gliomas heterotransplanted to experimental animals. | Observations concerning transplantation of 5 cases of malignant dysplastic gliomas to the anterior chamber of the guinea-pig eye have been presented. This type of gliomas, composed mainly of cytoplasm-abundant cells, show weak transplantability, slow rate of growth, and particular tendency to degeneration and necrosis. At the same time, in subsequent passages, an intensive proliferation of small-cell component occurs, comparing with cytoplasm-abundant cells. | 164,756 | [
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A cytoplasmic body in human fetal endothelium. | We describe a crystalloid-containing inclusion in the cytoplasm of human fetal cells believed to be endothelium. We do not know whether it is peculiar to the fetal period, nor do we know its function. | 164,775 | [
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An experimental mouse testicular teratoma as a model for neuroepithelial neoplasia and differentiation. I. Light microscopic and tissue and organ culture observations. | The various stages of divergent neuroepithelial differentiation were studied in the solid transplants of a transplantable mouse testicular teratoma (OTT-6050) maintained in both ascitic and solid forms. They included: a) areas of undifferentiated medullary epithelium corresponding to the rare human medulloepithelioma; b) areas of neuroblastic differentiation corresponding to neuroblastoma, with more mature neuronal differentiation corresponding to ganglioneuroma or, when mixed with glial elements, to ganglioglioma; and c) more mature neuroglial areas resembling astrocytoma, oligodendroglioma or ependymoma, as well as more primitive areas corresponding to ependymoblastoma. In tissue culture using collagen-coated coverslips, astrocytic differentiation was found in the outgrowth zone after 15 days, confirmed by immunofluorescence with antibodies to an astroglia-specific protein. In organ culture systems, glial components, including ependymal structures, were preserved in tumor explants, and astrocytic differentiation, as expressed by glial fiber formation, was increased after 4 to 6 weeks in vitro. No neuronal differentiation was demonstrable, however. The neuroepithelial component of this experimental teratoma may provide a model for the study of neoplastic neuroepithelial differentiation. | 164,776 | [
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Colon and rectal cancer in the young adult. | 801 patients with colon and rectal cancer were studied to assess the behavior of this cancer in the patient under 40 years of age as contrasted to the more commonly seen older patient. The younger patient had a greater frequency of advanced signs, later stages of cancer and mucoid carcinoma. However, when compared by clinical staging, the younger patient did as well or better than his older counterpart. Clinical staging was the most important prognostic factor irrespective of age. No inherent difference was found in the virulence of the cancer in the young, as the five-year survival in the younger patient (31 percent) was essentially the same as in the older patient (32 percent). | 164,809 | [
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Erythropoietin production in renal tumors. | A review of the pertinent literature on the relation of erythropoietin production to the presence of renal neoplasm suggests that erythropoietin may be produced either directly by the tumor or indirectly by its physical effect on the adjoining normal renal tissue. The most commonly found tumors which are associated with elevated levels of serum and urinary erythropoietin are the hypernephromas. However, the presence of erythropoietin and an associated erythrocytosis even here occurs only relatively infrequently. Some studies have demonstrated the presence of erythropoietin activity in tumor tissue itself but erythropoietin has not been isolated from renal tumor tissue. In some patients with Wilms' tumor, erythropoietin blood levels may also be increased; however, erythrocytosis in these patients is not a characteristic feature. Other renal tumors rarely produce erythrocytosis and presumably no erythropoietin. Possible explanations for the production of erythropoietin by renal tumors are discussed. | 164,817 | [
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Mechanism of colistin-induced neuromuscular depression. | The effect of a high concentration of the antibiotic colistin sulfate on neuromuscular transmission was examined by recording intracellularly from rat diaphragm blocked with tubocurarine chloride. The presynaptic effect of colistin was different from that of neomycin sulfate, which reduces the probability of acetylcholine release: Colistin reduced that the quantum content of the initial and the last 20 end-plate potentials of a train of 40 stimuli without altering the probability of acetylcholine release. The quantum size was reduced, while the frequency of miniature end-plate potentials was unchanged. | 164,847 | [
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Long-term effects on the health of men engaged in the manufacture of tolylene di-isocyanate. | A prospective study of workers engaged in the manufacture of tolylene di-isocyanate (TDI) was carried out over nine years. The study was in two parts: (1) assessment of the symptoms and ventilatory function of men working on the plants who did not complain of respiratory symptoms; (2) assessment of the long-term effects in men who were removed from the plants because of respiratory symptoms. Use of the MRC Questionnaire on Respiratory Symptoms in a group of 76 TDI workers showed no significant differences in symptoms compared with 76 control subjects. Annual lung function tests were carried out on 180 asymptomatic men with possible exposure to TDI. The relationship of the forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) to the height, age, and duration of exposure was examined by linear regression analysis. The equations formulated did not differ significantly from those calculated for non-TDI exposed subjects. Thus exposure to very small concentrations of TDI does not necessarily cause symptoms or a drop in ventilatory capacity. Forty-six TDI workers who had developed symptoms reported more long-term symptoms than a comparable number of controls. The difference was significant at the 1% level. Ventilation test records of 61 TDI workers who had developed symptoms were available since it was possible to use the records of men who had left the company. The lung function of this group was matched against predicted figures obtained from a control group of 608 subjects living in the same area as the exposed group but not exposed to TDI. It was found that the FEV1 of the affected men was on average 267 ml lower than predicted, and the FVC 269 ml lower. These findings are confirmed by examination of the indivdual records of a futher 20 men. | 164,881 | [
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Interaction of reduced nicotinamide adenine dinucleotide with beef heart s-malate dehydrogenase. | The interaction of NADH with s-malate dehydrogenase isolated from beef heart was studied in 20 mM potassium phosphate (pH 6.9)-1 mM EDTA, with forced dialysis, fluorescence, and temperature-jump techniques. Measurements of the change in fluorescence of NADH when it is titrated with enzyme indicate NADH bound to monomeric and dimeric enzyme have different fluorescence yields. These data and the results of direct binding studies can be explained in terms of a model in which the NADH binding sites on dimeric enzyme are equivalent or nearly equivalent, and NADH binding to monomeric enzyme occurs with an affinity very similar to that of the dimer. However, the fluorescence enhancement of NADH on binding to the enzyme is different for the monomer and for each of the two dimer sites. | 164,884 | [
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Conformational flexibility of angiotensin II. A carbon-13 spin-lattice relaxation study. | Carbon-13 spin-lattice relaxation times (T1) have been determined for the carbon in the octapeptide hormone [5-isoleucine]-angiotensin II in aqueous solution. Two possible models for molecular motion are considered: isotropic overall motion of the hormone with internal motion of some residues and anisotropic overall molecular motion. The data are interpreted in detail using the former model. The alpha carbons of the peptide backbone are all equally restricted in their motion. The correlation time for overall molecular reorientation, calculated from an everage T1 value of 95 msec for the alpha carbons in the peptide backbone, is ca. 5 times 10-10 sec. The carbons in the side chains are more mobile than those in the peptide backbone, with the exception of the side chain of the Tyr residue which does not undergo rapid segmental motion. We propose that [5-isoleucine]-angiotensin II has a restricted backbone conformation and that the alpha carbons of the N- and C-terminal residues are constrained to nearly the same extent as the remaining alpha carbons in the peptide backbone. Chemical shift data indicate that the Pro residue adopts the trans conformation about the His-Pro bond and that the imidazole ring of His has a strong preference for the N-tau -H tautomer. | 164,885 | [
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The assay and isolation of DNA rings using an ATP-dependent endonuclease. | The ATP-dependent endonuclease from Hemophilus influenzae is relatively inactive on closed or open DNA rings, yet rapidly hydrolyzes single- or double-chained linear DNA. This enzyme in combination with an exonuclease (exo VII) has been shown to spare various circular DNA molecules including those having single-chain regions of significant length. However, rings containing single-chained regions are broken at a rate depending on the length of these regions. By admixing a linear DNA of alternate radiolabel, a simple assay for DNA rings has been developed. The application of this procedure to the assay of folded rings from Drosophila DNA is demonstrated. | 164,888 | [
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Physicochemical characterization of Rhesus low density lipoproteins. | The serum low density lipoprotein (LDL; p 1.019-1.050 g/ml) of the normal Macaca mulatta monkey (rhesus), kept on a low-fat Purina primate chow diet, was isolated by ultracentrifugal flotation, and its physicochemical properties were compared with those previously reported for human LDL. Rhesus LDL was found to be chemically similar to human LDL. The values for the sedimentation (S25, w-O) and diffusion (D25,w-O) coefficients were 7.09 S and 2.50 times 10- minus-7 cm-2 sec- minus-1, respectively. The intrinsic viscosity was 3.40 ml g- minus-1. The partial specific volume of rhesus LDL, determined in an Anton Paar precision density meter, was 0.960 ml g- minus-1. Molecular weights, calculated from a combination of S-O and D-O and of S-O and [n], were in agreement with the weight-average molecular weight, Mw, of 2.29 times 10-6 obtained by high-speed sedimentation equilibrium. In addition, a Z-average molecular weight, Mz, of 2.73 times 10-6 was calculated because curvature in the graphs of log c vs. r-2 indicated that rhesus LDL was heterogeneous. From the frictional ratio of 1.02, a maximum hydration of 0.1 g of H2O/g of lipoprotein was obtained. On electron micrographs, rhesus LDL appeared spherical with a mean diameter of 196 A, which was substantiated by hydrodynamic analysis. | 164,895 | [
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Studies on the active transfer of reducing equivalents into mitochondria via the malate-aspartate shuttle. | 1. The effects of mitochondrial energy states onthe extramitochondrial NADH/NAD ratio via a reconstituted malate-aspartate shuttle have been investigated. 2. The transfer of reducing equivalents into isolated mitochondria is stimulated by ATP and by electron transport. The effect of ATP is inhibited by oligomycin. The effect of electron transport is inhibited by uncouplers. 3. Uncoupling of the mitochondria is required for rapid transfer of reducing equivalents out of the mitochondria. 4. A glutamate-stimulated entry of aspartate into energized mitochondria suggests that the malate-aspartate shuttle is to some extent reversible even in a high energy state of the mitochondria. 5. It is concluded that the malate-aspartate shuttle contributes to the formation of the skewed redox situation across the inner mitochondrial membrane, which has a more reduced inside. | 164,904 | [
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Hormone action at the membrane level. IV. Epinephrine binding to rat liver plasma membranes and rat epididymal fat cells. | [3-H]Epinephrine binding to isolated purified rat liver plasma membranes is a reversible process. An initial peak in binding occurs at about 15 min and a plateau occurs by 50 min. Optimal binding occurred at a membrane protein concentration of 125mug. Rat liver plasma membranes stored at-70 degrees C up to 4 weeks showed no difference in epinephrine binding capacity as compared to control fresh membranes. Epinephrine binding to liver plasma membranes was decreased by 79% by phospholipase A2 (phosphatide acylhydrolase EC 3.1.1.4), 81% by phospholipase C (phosphatidylcholine choline phosphohydrolase EC 3.1.4.3) and 59% by phospholipase D (phosphatidylcholine phosphatidohydrolase EC 3.1.4.4). Trypsin and pronase digestion of the membrane decreased epinephrine binding by 97 and 47% respectively. In the presence of 10-3M Mg-2+ ions, increasing concentrations of QTP decreased epinephrine binding to liver plasma membranes. A maximal effect was demonstrated with 10-5M GTP, representing an inhibition of 52% of the control. In a Mg-2+ -free system, epinephrine binding was unaffected by GTP. However, in a Mg-2+ -free system, increasing concentrations of ATP cause increasing inhibition of hormone binding. ATP at 10-3 M reduced epinephrine binding to 28% of the control. GRP (10-5 M) was shown to inhibit epinephrine uptake rather than epinephrine release from the membrane. [3-H]Epinephrine binding to isolated rat epididymal fat cells shows an initial peak within 5 min followed by a gradual rise which plateaus after 60 min. Epinephrine binding increased nearly linearly with increasing fat cell protein concentration (40-200 mug protein). GTP (10-5 M) and ATP (10-4 M) decreased epinephrine binding to rat epididymal fat cells by 41%. Nearly complete inhibition of binding was demonstrated with 10-2-10-3M ATP. Epinephrine analogs that contain two hydroxyl groups in the 3 and 4 position on the benzene ring act as inhibitors of [3-H]epinephrine binding to rat adipocytes. Alteration of the epinephrine side chain has relatively little influence on binding. Analogs in which one of the ring hydroxyl groups is missing or methylated are poor inhibitors of [3-H]epinephrine binding. Alpha-(phentolamine and phenoxybenzamine) and beta-(propranolol and dichorisoproterenol) adrenergic blocking agents were tested with respect to their ability to influence [3-H]epinephrine binding and their influence on epinephrine-stimulated lipolysis. Only dichloroisoproterenol significantly inhibited epinephrine binding (by 25%). The two beta-adrenergic blocking agents caused an inhibition of epinephrine-stimulated glycerol release, with propranolol being most effective. Phentolamine and phenoxybenzamine had no significant effect on the epinephrine stimulation of glycerol release by fat cells. | 164,909 | [
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Purification and characteriazation of collagenase from guinea pig skin. | Guinea pig skin col-agenase, isolated from culture medium of whole skin, was separated into two enzymatically active fractions. These two fractions have been purified extensively. Peak II fraction has been purified to homogeneity as examined by polyacrylamide gel electrophoresis. Their molecular weights are approximately 130 000 (peak I) and 40 000 (peak II). Both guinea pig skin collagenase fractions are capable of degrading the native collagen fibrils and are inhibited by serum, cysteine and EDTA. They appear to be glycoproteins. Guinea pig skin (peak II) and human skin collagenase were compared. They are both glycoproteins and have similar molecular size (Mr = 40 000). Immunodiffusion assay showed that no cross-reactivity was seen between the enzymes, indicating species specificity among collagenases. | 164,920 | [
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Essential arginine residues in D-glyceraldehyde-3-phosphate dehydrogenase. | Two arginyl residues per subunit of yeast D-glyceraldehyde-3-phoshphate dehydrogenase were modified by treatment with butanedione without significant changes in the compostion of other amino acid residues. The modified enzyme displays no dehydrogenase activity. It retains the capacity for interacting with the coenzyme NAD, but binds it less firmly than does the native enzyme. The molar absorbance of the enzyme-NAD complex is markedly reduced and the reactivity of the active-center SH groups is changed in the modified enzyme. The native and modified enzymes show identical fluorescence spectra, absorbance and CD spectra. | 164,934 | [
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Microsomal (Na- +K+)-activated ATPase from frog skin epithelium. Cation activations and some effects of inhibitors. | A method is described for the extraction of microsomal ouabain-sensitive (a- + K+)-activated ATPase from separated frog skin epithelium. The method yields a microsomal fraction containing (Na+ K+)-stimulated activity in the range of 30- 40 nmol - mg -1 - min -1 at 26 degrees C. This portion which is also ouabain sensitive, is about half of the total activity in media containing Mg2+, Na+ and K+. These preparations also contain Mg2+-dependent or Ca2+-dependent activities which are not additive and which are not significantly affected by ouabain, Na+, K+ or Li+. The activations of the ouabain-sensitive ATPase activity by Mg2+, Na+, and K+ are similar to those described in other tissues. It is found that Li+ does not substitute for Na+ as an activator but in high concentrations does produce partial activation in the presence of Na+ with no K+. These results are pertinent to the reported observations of ouabain-sensitive Li+ flux across frog skin. It is concluded that this flux is not apparently due to a direct activating effect of Li+ on the sodium pump. | 164,947 | [
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Effect of adrenergic agents on alpha-amylase release and adenosine 3',5'-monophosphate accumulation in rat parotid tissue slices. | The role of cyclic AMP in stimulus-secretion coupling with investigated in rat parotid tissue slices in vitro. Isoproterenol and norepinephrine stimulated a rapid intracellular accumulation of cyclic AMP, which reached a maximum level of 20-30 times the control value by 5 to 10 min after addition of the drug. Isoproterenol was approximately ten times more potent in stimulating both alpha-amylase release and cyclic AMP accumulation than were norepinephrine and epinephrine, which had nearly equal effects on these two parameters. Salbutamol and phenylephrine were less effectivema parallel order of potency and sensitivity was observed for the stimulation of adenylate cyclase activity in a washed particulate fractionmthe results suggest that these drugs are acting on a parotid acinar cell through a beta1-adrenergic mechanismmat the lowest concentrations tested, each of the adrenergic agonists stimulated significant alpha-anylase release with no detectable stimulation of cyclic AMP accumulationmeven in the presence of theophylline, phenylephrine at several concentrations increased alpha-amylase release without a detectable increase in cyclic AMP levels. However, phenylephrine did stimulate adenylate cyclase. These data suggest that, under certain conditions, large increases in the intra-cellular concentration of cyclic AMP may not be necessary for stimulation of alpha-amylase release by adrenergic agonists. Also consistent with this idea was the observation that stimulation of cyclic AMP accumulation by isoproterenol was much more sensitive to inhibition by propranolol than was the stimulation of alpha-amylase release by isoproterenol. Stimulation of alpha-amylase release by phenylephrine was only partially blocked by either alpha- or beta-adrenergic blocking agents, whereas stimulation of adenylate cyclase by phenylephrine was blocked by propranolol and not by phentolaminemphenoxybenzamine and phentolamine potentiated the effects of norepinephrine and isoproterenol on both cyclic AMP accumulation and alpha-amylase release by N-6,O-2'-dibutyryl adenosine 3',5'-monophosphate; These observations may indicate a non-specific action of phenoxybenzamine, and demonstrate the need for caution in interpreting evidence obtained using alpha-adrenergic blocking agents as tools for investigation of alpha- and beta-adrenergic antagonism. | 164,957 | [
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Two types of insomnia: too much waking or not enough sleep. | The stability of sleep was examined in two kinds of induced insomnia, namely after caffeine administration and after hypnotic drug withdrawal. The duration of each episode of any one sleep stage or any episode of intervening wakefulness plus drowsiness was determined. After caffeine there was an increase in longer episodes of intervening wakefulness plus drowsiness, but no significant change in the episode duration of any of the sleep stages. In the case of drug withdrawal there was no change in the episode duration of intervening wakefulness plus drowsiness, but there was a significant shortening of episode duration in sleep stages 2 and 3+4, with a similar trend for REM sleep episodes. Caffeine 'insomnia' thus seems characterized by increased stability of wakefulness, and hypnotic withdrawal 'insomnia' by decreased stability fo sleep. The type of analysis undertaken in this study could increase understanding of other types of insomnia. | 164,968 | [
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The conformational states of cytochrome oxidase in the mitochondrion. | THE Soret spectrum of "resting" cytochrome oxidase in cytochrome-c depleted mitochondria has been determined. The spectrum obtained is dependent on the rate at which the oxidase is turning over. In the least active preparations, the spectrum is almost pure "oxidized" oxidase. With increasing activity the spectrum is converted to a mixture of "oxidized" and "oxygenated" oxidases. It is concluded that the same conformational differences between the two non-reduced forms that are found in the purified enzyme also occur in these cytochrome-c depleted mitochondria. | 164,988 | [
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0.04856154... |
Relationship between serum cholinesterase and low density lipoproteins in children with nephrotic syndrome. | 1. A significant increase in the activity of serum cholinesterase and concentration of dextran sulphate precipitable lipoproteins, cholesterol and triglycerides was observed in sixteen children with a diagnosis of nephrotic syndrome when compared with the values obtained in 22 other normal children of comparable ages. 2. In 7 children with nephrotic syndrome serum concentrations of beta-lipoprotein and cholinesterase were markedly higher in the acute stage compared to the convalescent stage. A working hypothesis is proposed to explain the hyperlipoproteinemia in nephrotic syndrome. | 165,016 | [
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Triiodothyronine binding in rat anterior pituitary, posterior pituitary, median eminence and brain. | In vivo studies of the exchange of tracer [125-I]-L-triiodothyronine (T3) between plasma (P), and the anterior pituitary (AP), posterior pituitary (PP), median eminence (ME) and the frontal lobes of the brain (B), in the rat show that from 2.5 h onwards the concentration of new [125I]T3 in AP, PP and B were parellel to that of the plasma, with a t1/2 of 7.4 h; the t1/2 for ME was 10.3 h. The extrapolation of these curves to zero time was assumed to indicate the relative concentration of T3 per unit weight in terms of total body T3. T3 content of these tissues was determined by radioimmunoassay. The values obtained validated the steady state parameters derived from the radio-isotopic measurements. As an indicator of the concentration gradient between tissue and plasma the organ/plasma (O/P) ratio was calculated; these data indicate that under steady state conditions, the order of T3 concentration is AP greater than PP greater than ME greater than B. Binding studies have shown that AP and PP contain "specific," saturable binders while ME and B do not. Evaluation of the binding parameters of the high affinity binders in both AP and PP gave similar association constants. These associations constants, when corrected for the binding strength of T3 to plasma proteins, resulted in values similar to those of neuclear T3 binders. | 165,057 | [
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Effect of dexamethasone on the secretion of thyrotropin in the rat: dose and time relations. | Serum TSH and corticosterone concentrations were measured in intact rats and in rats given TRH or exposed to short-term cold 3 h and 12 h after pretreatment with dexamethasone in various doses. Dexamethasone given 3 h before experiemtns significantly depressed both TRH- and cold-induced TSH responses at all dose levels. Dose of 25 pg/100 g body weight significantly depressed serum TSH concentration when given 3 h before the experiment. However, when given 12 h before the experiment the drug augmented TRH-induced TSH secretion, although the cold response was unaltered. In intact rats dexamethasone significantly depressed serum TSH concentration in doses of 250 and 500 mug/100 g body weight. In all experiments the steroid blocked ACTH secretion. These results support the view that the effect of dexamethasone on thyroid function is highly dependent on the time relations. A single large dose of dexamethasone has first an inhibitory effect at the pituitary level and then facilitates pituitary to TRH and at the same time inhibits secretion of TRH in response to cold. | 165,068 | [
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Effect of temperature during preparation of rat adrenal quarters and isolated cell suspension of their ACTH responsiveness. | The effect of temperature during preparation of rat adrenal quarters or isolated adrenal cell suspension on their response to ACTH was examined through a comparison of amounts of corticosterone produced after their incubation. The response to ACTH added in vitro was considerably higher when adrenal quarters and isolated adrenal cell suspension were prepared at room temperature (25 degree C) than when prepared at ice-cold. Endogenous steroidogenesis was not affected by the temperature. It seemed unlikely that this higher response to ACTH of adrenal quarters or isolated adrenal cell suspension prepared at room temperature was due to an activation of the cells. A possibility was discussed that cooling adrenal quarters or isolated adrenal cell suspension during the preparation may create an unphysiological state in some place to related the cell membrane. | 165,070 | [
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Conformational studies of equilibrium structures in fragments of horse heart cytochrome c. | Ultraviolet absorption and circular dichroism studies have been carried out on horse heart apo-cytochrome c and heme-free peptide fragments obtained by cyanogen bromide cleavage of the native protein. It was noted that the various peptides assume predominantly an unordered conformation in water solution. Increasing ionic strength and addition of 2-chloroethanol increase the right-handed helical content. Guanidinium hydrochloride favors the coil state. It was also demonstrated that two non-interacting helical regions of different stability are present in the apo-protein in 2-chloroethanol. | 165,078 | [
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Restoration of potassium-stimulated respiration of glycerol-treated muscle. | Agent that produced contracture in skeletal muscle, such as caffeine or K-depolarization, also caused an increased rate of oxygen consumption. Both of these functions are calcium dependent. In this study the respiratory response to K-depolarization and to caffeine was monitored in glycerol-treated and normal frog sartorius muscles. Although glycerol-treated muscle does not contract in response to K-depolarization, it does develop normal caffeine contractures. The respiratory response to both potassium and caffeine is greatly inhibited in glycerol-treated muscles. Pretreatment with dibutyryl cyclic AMP restored the respiratory response to normal levels in glycerol-treated muscle. Pretreatment with low levels of caffeine that had no effect on oxygen uptake markedly enhanced oxygen uptake with higher concentrations of caffeine and resulted in a normal respiratory response to K-depolarization even though there was no tension development. Caffeine had no effect on adenyl cyclase activity even at concentrations that markedly stimulated oxygen uptake. The data suggest that potassium stimulation of oxygen uptake in glycerol treated muscle is uncoupled by a defect in the formation of a cyclic nucleotide cofactor, rather than a defect in calcium influx. | 165,082 | [
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Phosphorylation of purified thyroid plasma membranes incubated with [32-P]ATP. | Plasma membranes have been prepared from porcine thyroid glands using sucrose gradients. The fractions having a density in sucrose of 1.18 g/ml mainly contained plasma membranes and were moderately contaminated with other subcellular components as shown by marker enzyme data. Purified plasma membranes incubated in the presence of [32-P]gamma ATP incorporated 32-P. Kinetics of incorporation of 32-P into endogenous substrates studied in various buffers and with increasing ATP concentration suggest a phosphodephosphorylating system related to cAMP-dependent protein kinase and phosphoprotein phosphatase activities. The two enzymatic activities associated with plasma membranes have been demonstrated using exogenous substrates. cAMP increases and fluoride ions decrease the extent of membrane phosphorylation. The specific activity of protein kinase was 10-12 times higher than in the initial homogenate and was only slightly enhanced in the presence of 0.5% Nonidet as compared to microsomal fraction. cAMP binding to membrane proteins was 3 times higher than to the other particulate fractions. TSH present in the incubating medium or added after 5 min of 32-P labelling induced a rapid stimulation of endogenous phosphorylation followed by a rapid decrease. Phosphorylated membrane substrates were analyzed: high voltage paper electrophoresis after partial hydrolysis indicated that [32-P]phosphate is incorporated into serine and threonine residues as o-phosphate derivatives. SDS-polyacrylamide gel electrophoresis showed several 32--labelled fractions. When enhanced by cAMP, no specific phosphorylation of protein components was observed. | 165,113 | [
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The anamnestic response of the secretory immune system: A review. | Following topical immunization of the respiratory mucosa in man, persistence of antibody in the respiratory secretions can be demonstrated in some individuals for more than one year. The secretory response to replicating agents is generally more prolonged than the response to less persistent antigens. Repeat topical antigenic stimulation provokes a response which differs very little from the primary response in magnitude, duration or latency. Nevertheless, if more than 1 year following adequate primary intranasal immunization, at a time when secretory antibodies are no longer detectable, men are again vaccinated intranasally with a dose of formalin-inactivated rhinovirus vaccine which will not provoke a primary secretory immune response, some vaccinees will produce nasal antibody. Similarly in mice, a second topical immunization of the respiratory tract with a dose of tetanus toxoid which does not produce a detectable primary secretory immune response will cause 11S IgA antibodies to appear in bronchial and nasal washings. Thus, it is possible that the secretory immune system may possess certain attributes of immunologic memory as classifically defined by the responses of the internal immune system to repeated antigenic stimulation. | 165,117 | [
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Adenoviruses of man and animals. | Adenoviruses are capable of causing natural infections in a wide variety of vertebrates, including amphibia, birds and mammals. Although frequently causing inapparent infections, they may be associated with diseases of varying severity and localizations. The clinico-pathological manifestations most commonly associated with adenovirus infections involve the respiratory tract and the ocular conjunctiva. Involvement of the digestive, renal and nervous systems may also be observed. A state of latency with persistence of infection for prolonged periods has been described in many hosts. Many adenovirus types are oncogemic under experimental conditions but none have been associated with naturally occurring tumours. Although the diseases caused by adenoviruses tend to be mild, this is not invariably the case and these viruses may give rise to serious epidemiological situations and represent a threat to life under certain circumstances in which the use of prophylactic vaccination may be indicated. | 165,118 | [
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Immunity to infections of the respiratory system in man and animals. | Itis probable that RS virus is an important etiological agent in the bovine respiratory disease syndrome. This is the conclusion of groups of workers in Europe and Japan. In this country, significant levels of neutralizing antibody have been detected in 81 percent of cattle tested, while paired sera groups showed seroconversions of between 17 and 29 percent. RS virus has also been isolated from diseased calves and such isolates produce pyrexia and rhinitis in experimentally infected calves. The virus is localised in the respiratory tract. Serum antibody responses have not been consistent but it is likely that moderate serum antibody levels indicate that the animal is protected. These antibody levels can be achieved by injection of a formalin inactivated antigen. Calves vaccinated in this way showed no definite evidence of exacerbation of disease when challenged with infectious virus. | 165,132 | [
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Hepatic dearterialization in 3'-methyl-4-dimethylaminoazo-benzene-induced hepatocellular carcinoma with special reference to circulatory dynamics and mitochondrial functions. | This time trend of hemodynamics and mitochondrial functions were studied to determine whether the ligation of the hepatic artery would result in an antitumor effect on 3'-methyl-4-dimethylaminoazobenzene-induced hepatic carcinoma in rats. The studies revealed that the hepatic tumors were nourished predominantly by the artery and less by the portal vein; the size of the vascular beds in the hepatic tumors decreased as compared with those in the non-tumor area; and as the tumors grew larger, the artery became less predominant and the size of vascular beds decreased further. The mitochondria in the tumor were characterized by impaired growth, impaired oxidative phosphorylation, and by the low activity and nucleotide specificity of membrane bound ATPase. Hepatic dearterialization enhanced ischemia in the tumors and was accompanied by intensified impairment of the aerobic energy production, resulting in necrosis of the tumor. The effects of the dearterialization tended to decrease after the 5th day following the operation. In view of the gross findings upon relaparotomy and the recovery of hemodynamics and mitochondrial functions, this tendency appeared to be chiefly attributed to the increasing collateral circulation. | 165,134 | [
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Indirect sulphonation of mucopolysaccharides and glycogen in tissue sections with the use of bisulphite or dithionite after periodic acid oxidation. | Tissue mucopolysaccharides and glycogen can be indirectly sulphated after being oxidized by periodic acid and treated with sodium bisulphite or dithionite in aqueous solution. The sulphated sites are darkly stained by Roluidine Blue and realted dyes at pH less than 1.0. The background is very pale or colourless. The stained sections resist extraction with 1% hydrochloric acid for 48 hr, but can be extracted by 5% ammonium hydroxide in ethanol in 1 hr. Other oxidizing agents cannot be substituted for periodic acid. | 165,165 | [
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Regulation of galactose operon at the gal operator-promoter region in Escherichia coli K-12. | The capR (lon) product controls expression of the gal operon independently of the galR repressor. Previously, mutations of the gal operon have been isolated that are semiconstitutive and alter response to the capR and/or capT product. Such mutants imply the existence of a distinct site in the operon that responds to capR (capT) control. This mutation could be either in a site near the operator-distal end of the galE gene, which signals rho factor termination of transcription in vitro or in a site in the operator-promoter region. Bacteriophage U3 was used to isolate galE mutations in HC2142 (a mutant exhibiting reduced response to capR control). P1 transduction was used to cross these mutants with a set of galE gene deletion. Analysis of the resulting Gal+ recombinants indicates that the regulatory site is in the operator-promoter region. Hence, it is unlikely that capR functions in control as an anti-rho factor at the operator-distal end of the galE gene, but more likely as previously suggested, at a second operator distinct from one responding to galR repressor control. Upon induction with D-fucose, a promoter mutant (UV211) isolated previously expressed 20 to 30% of the galactose enzymes that the wild type exhibited in the presence of the inducer D-fucose. The effects of various mutations in cya, capR, and galR on galactokinase synthesis in this mutant were determined. Galactokinase was derepressed by capR as well as galR, but the presence or absence of the cya gene product was unimportant. | 165,171 | [
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Hydrophobic interactions of the apo-Gln-I polypeptide component of human high density serum lipoprotein. | Apo-Gln-I, the major polypeptide component of human serum high density lipoprotein, has four noninteracting hydrophobic sites which associate with alkanes, anionic detergents, and cationic detergents. Hexane and octane bind to these sites with association constants of 6.8 times 10-2 and 1.8 times 10-4 liters/mol, respectively, and compete with the anionic detergent, sodium dodecyl sulfate (C12OSO3-minus), at low detergent ligand binding ratios (i.e. smaller than or equal to 1.0 mol of C12OSO3-minus per mol of protein). At higher detergent binding ratios (larger than 2 mol of C12OSO3-minus per mol of protein) the polypeptide cooperatively binds alkanes and a conformational change is induced. | 165,177 | [
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Deoxyribinucleic acid-binding proteins in virus-transformed cell lines. | The synthesis of proteins with affinity for DNA has been studied in clones of a Syrian hamster cell line (NIL) and subclones of this line transformed by polyoma virus (NIL-Py) or hamster sarcoma virus (NIL-HSV). The results show that the synthesis of DNA-binding proteins in NIL and in its virus-transformed derivatives NIL-Py and NIL-HSV is very similar in exponentially growing cells, but in dense culture there is a very significant difference in the level of a protein (P8), which is much higher in the transformed lines than in untransformed NIL. The high levels of P8 in dense transformed cells have been observed in all the clones of transformed cells examined, indicating that this behavior of P8 is related to transformation and not simply due to a fortuitous clonal selection from the NIL. Experiments with synchronized cells indicate that the time of maximal P8 synthesis relative to cellular DNA synthesis in NIL-HSV precedes that observed in NIL cells. P8 has a molecular weight of 30,000 as determined by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and is present in large amounts in the transformed cells in dense culture, where it makes up 0.5 to 1% of the total soluble protein. | 165,180 | [
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Glycerol as an agent eliciting small conformational changes in alcohol dehydrogenase. | Yeast alcohol dehydrogenase is an example of a protein in which the K-m for substrate is substantially decreased by the presence of glycerol. The polyol has the effect at pH 8.0 or above of decreasing K-m and K-s for substrate and of altering both the protein's intrinsic fluorescence and ultraviolet absorption difference spectrum. The relationship between each of thse parameters and glycerol concentration displays a transition at a glycerol concentration of 20%. Circular dichroism values for the enzyme are not affected by glycerol over a large range of concentration and temperature. Treatment of the enzyme with glutaraldehyde results in the formation of cross-linked tetramers, the K-m of which are not altered by the presence of the solvent. The data are interpreted as reflecting a change in the conformation of the protein induced by glycerol. | 165,183 | [
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Nucleolar changes in liver before the onset of deoxyribonucleic acid replication. | A mixture of chemicals was previously devised (3, 3', 5'-triiodo-L-thyronine, amino acids, a butyryl derivative of cyclic adenosine 3':5'-monophosphate, theophylline, and heparin) that induces nuclear DNA replication in the liver of the unoperated rat (Short, J., Tsukada, K., Rudert, W.A. 7 Lieberman, I. (1975) J. Biol. Chem. 250, 3602-3606). The stimulation of DNA synthesis with the complete solution is greater than the sum of the responses to the thyroid hormone alone and to a mixture of the remaining components of the inductive solution alone. The effects of the complete mixture and of parts of it on three parameters involving the hepatocyte nucleolus have now been examined in intact animals. The complete solution increases the level of RNA polymerase I (measured with isolated nuclei), the rate of ribosome synthesis, and the total volume of nucleoli per nucleus. Nucleolar hypertrophy is unique among the three changes in showing a requirement, just as for DNA synthesis, for all or almost all of the components of the complete mixture, including the thyroid hormone, for a maximal effect. Enlargement of nucleoli is detectable as early as 2 hours after the start of treatment with the complete mixture and a large proportion of the total hepatocyte population is involved. Hypertrophy is accompanied by an increase in nucleolar RNA content. N2-Monobutyryl cyclic guanosine 3':5'-monophosphate is not able to substitute for the cyclic adenine nucleotide. | 165,195 | [
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Pitfalls in the use of lead nitrate for the histochemical demonstration of adenylate cyclase activity. | The biochemistry of the lead histochemical technique for demonstrating adenylate cyclase was studied. The enzyme activity of fat cell plasma membranes, using 5'-adenylyl-imidodiphosphate (AMP-PNP) as substrate, was completely inhibited at 1 times 10- minus 4 M Pb(NO3)2 and yet at 4 times 10- minus 3 M Pb(NO3)2 precipitate could be demonstrated by electron microscopy on both sides of plasma membrane vesicles. No lead-diphosphoimide or lead-phosphate precipitate could be visualized by electron microscopy when the lead was reduced to a level (2 times 10- minus 5 M) which caused only 50% inhibition of the enzyme. A solubility product coefficient of 1 times 10- minus 10 M was found necessary to allow precipitation of lead-phosphate complex in the adenylate cyclase medium. Varying the ratio of substrate or dextran relative to the lead failed to protect the inhibition of the enzyme. Increasing concentrations of beta-mercaptoethanol restored the basal and stimulated activity of adenylate cyclase but also prevented the precipitation reaction. Lead at 2 times 10- minus 3 M caused the nonenzymatic hydrolysis of AMP-PNP, resulting in the production of small but significant quantities of cyclic AMP and substantial amounts of AMP. This hydrolysis was inhibited by alloxan but unaffected by dextran of NaF. The adenylate cyclase activity of pancreatic islet homogenates and of fat pad capillaries was completely inhibited by lead concentrations equal to or less than those used in histochemical studies (Howell, S. L., and M. Whitfield. 1972. J. Histochem. Cytochem. 20:873-879. and Wagner, R. C., P. Kreiner, R. J. Barrnett, and M. W. Bitensky. 1972. Proc. Natl. Acad. Sci. U.S.A. 69:3175-3179.). The present study shows that the lead histochemical method cannot be used for localization of adenylate cyclase because of the inhibition of the enzyme and artifacts produced by high lead concentrations and the inability to produce a visible precipitate at low lead concentrations which only partially inhibit the enzyme. | 165,205 | [
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Radioligand receptor assay for urinary and serum hCG. | A radioligand receptor assay system for urinary hCG and serum hCG was developed, using 1100-2000 times g fractions of homogenates of pig testis. This method is specific for hCG and LH, and the limit of detection for hCG was 20 mIU, which could be significantly discriminated from zero at the 95% confidence level. A nonspecific inhibition reaction which exerts its influence on the assay system has been found in the urine and serum, and in performing assays for urinary and serum hCG, it was necessary to remove the inhibition reaction by diluting the urine more than eight fold or subject the serum to an extraction procedure. Since the hCG of normal pregnancy and trophoblastic neoplasia showed a dose response curve similar to that of the International Standard hCG, it became clear that these hCG could be assayed with this method. The potency ratio R/I measured by RRA and RIA of urinary hCG and serum hCG was different from those of normal pregnancy and trophoblastic neoplasia. | 165,212 | [
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Characterization of the glucagon receptor in a pheochromocytoma. | Glucagon activated adenylate cyclase in a homogenate of a pheochromocytoma over the concentration range 1 times 10 minus 8M to 1 times 10 minus 6M. Several other hormones including adrenocorticotropin, thyrotropin, parathyroid hormone and histamine were without effect. The tumor glucagon receptor was characterized and found to be similar in several ways to the glucagon receptor previously reported in normal tissue such as liver and heart. One, the receptor specifically bound 125-I-glucagon. Two, solubilization of the pheochromocytoma abolished glucagon-activation of the adenylate cyclase. Three, glucagon-responsiveness of the adenylate cyclase was partially restored by the addition of phosphatidylserine to the incubations. One major difference was observed between the glucagon receptor in tumor tissue and that in liver and heart, namely, a marked lability in 125-I-glucagon binding and adenylate cyclase activity. Within four days, despite storage in liquid nitrogen, 75% of the binding activity and all of the adenylate cyclase activity in the solubilized preparation were lost. The factor(s) responsible for this lability remains unidentified. | 165,216 | [
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Plasma growth hormone and slow wave sleep increase after interruption of sleep. | A comparison was made of plasma hGH and of sleep stages during one night of undistrubed sleep and one night in which sleep was interupted by an hour of enforced wakefulness folowing the end of the second NREM-REM sleep cycle in 8 normal subjects. Plasma was sampled at 15-min intervals. HGH and slow wave sleep were both significantly increased in the two cycles immediately following the period awake compared with the same two cycles during nights of uninterruped sleep. The difference arose predominantly in the fourth cycle of the night, i.e., in the second cycle after the sleep interuption. The findings are consistent with the belief that extra wakefulness brings additional sleep of high RESTORATIVE properties. | 165,220 | [
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The isolation and partial characterization of neutrophil chemotactic factors from Escherichia coli. | Heat-stable, chemotactically active peptides have been obtained from Escherichia coli culture filtrates. They range in size between 150 and 1500 daltons and are anionic at neutral pH. Free carboxyl groups but not free amino groups appear to be required for activity. The N-terminal group may be blocked. There do not appear to be internal aromatic or basic residues in the chemotactically active fractions. A highly purified, not completely characterized, fraction was found to contain aspartic acid, serine, glutamic acid, alanine, and glycine. | 165,239 | [
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Tumours of the parotid region. | Fifty-eight operatively treated tumours of the parotid region are presented. Of the tumours 85 per cent were benign and 15 per cent malignant. The percentage of pleomorphic adenomas was 36 per cent. During five years of observation there were no recurrences of benign tumours. Operative complications consisted of one paresis of the mandibular branch of the facial nerve and one death due to bleeding and aspiration during the first postoperative day. Frey's syndrome occurred postoperatively in 26 per cent of the cases. It is emphasized that parotid tumours should be concentrated to centres where surgeons have sufficient experience with these cases. | 165,250 | [
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Neutrophil-mediated tumor cell cytotoxicity: role of the peroxidase system. | A cytotoxic effect of human neutrophils on mammalian tumor cells is demonstrated. Cytotoxicity depends on the presence of intact neutrophils, phagocytosable particles, and a halide cofactor and is inhibited by azide, cyanide, and catalase. Neutrophils from patients with myeloperoxidase (MPO) deficiency or defective H1O2 production are not cytotoxic, but activity is resotred by addition of purified MPO or H2O2 respectively. The findings support a mechanism involving the phagocytosis-induced extracellular release of MPO and H2O2 and their reation with a halide cofactor to damage the target cells. | 165,258 | [
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Experimental optimization of current source-density technique for anuran cerebellum. | This paper represents a systematic, semirigorous attempt to optimize the technique of current source-density (CSD) analysis experimentally. We compared different spatial differentiation formulas in terms of accuracy, aliasing, and smoothing, and provide experimental and theoretical rationale for their use. Sources of error have also been investigated. Expressions were derived to enable one to estimate the relative magnitude of errors due to electrical noise, uncertainty in tip position of recording electrodes, and error in the conductivity tensor. Corresponding experiments illlustrating the validity of such estimates are also presented. Methods to determine the optimum interelectrode spacing are given, based on computations of spatial energy-density spectra in the anuran cerebellum. The application of the technique of CSD analysis developed in this, and the accompanying paper, to the vestibulocerebellar input in the toad cerebellum provided significantly better temporal and spatial resolution of neuronal events than conventional field-potential analysis. Considerations germane to the optimum application of this technique to other neural structures are also discussed. | 165,272 | [
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Effects of activity in single sensory fibres on the discharge patterns of dorsal spinocerebellar tract cells. | 1. Electrical activity of dorsal spinocerebellar tract (DSCT) was recorded extracellularly and intracellularly in Clarke's column nucleus. 2.Trains of impluses were elicited in DSCT cells by static stretch of the hind limb muscles, and the distributions of intervals between the impulses were computed. These distributions were essentially similar before and after impalement of the cells with the micropipette, suggesting that cell injury caused by penetration was insignificant. 3. Patterns of synaptic activity revealed that the DSCT cells examined were innervated by a limited number of muscle afferents. 4. In some DSCT neurons, all excitatory post-synaptic potentials (e.p.s.p.s) elicited by a single fibre were suprathreshold, and e.p.s.p.s elicited by other afferents were usually subthreshold. These neurons discharge very regularly during muscle stretch, and the spike initiation followed nearly one-to-one relation in response to activity of the sensory fibre eliciting suprathreshold e.p.s.p.s. 5. The discharge pattern was irregular in other DSCT cells. In these cases, single sensory fibres evoked e.p.s.p.s. which did not always reach the firing threshold because of random fluctuation in their amplitude. 6. DSCT neurons often show low frequency discharges (about 10/sec) in the absence of sensory activation. In these conditions only small e.p.s.p.s. were detected (average, 0.53 mV) suggesting that the average membrane potential is very close (1-i mV) to the firing threshold. 7. It is concluded that the statistical properties of firing patterns in DSCT neurons activated by muscle afferents depend on (a) the large amplitude of e.p.s.p.s., (b) their firing threshold and (c) random fluctuations in the e.p.s.p.s. amplitude. | 165,283 | [
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Detachment of structurally intact nerve endings from chromatolytic neurones of rat superior cervical ganglion during the depression of synaptic transmission induced by post-ganglionic axotomy. | 1. Electrophysiological studies showed that injury of post-ganglionic nerve fibres leads to severe and prolonged depression of synaptic transmission through the rat superior cervical ganglion, beginning within 24 h. This is in line with the results of previous studies in other species and upon other neurones. 2. electron microscopy after post-ganglionic axotomy revealed nerve endings of presynaptic type with all the specialized membrane-related features of a synaptic zone, but which were not apposed to any post-synaptic nervous element. These umusual profiles were interpreted as detached presynaptic nerve endings. In normal and control ganglia, such profiles formed at most 0-5% of all vesicle-containing profiles of presynaptic type; in ganglia with all major post-ganglionic branches cut the proportion rose to approximately 7%, between 3 and 7 d post-operatively. Over this period, the mean incidence of chromatolytic neurones was 74-6%. 3. Concomitantly, the incidence of synapses within the ganglion fell by about 75%, reaching its lowest levels between 3 and 7 d post-operatively. There was strikingly little evidence of persistence of post-synaptic membrane specializations ('membrane thickenings') following detachment of synapses. 4. At longer survival intervals the incidence of synapses gradually increased, and that of detached nerve endings gradually decreased; recovery was well advanced by 42 d. 5. The fall in the incidence of synapses was closely paralleled by a fall in the incidence of desmosome-like attachments in the ganglion; the incidence of such attachments was found to be correlated to a significant degree with that of synapses. 6. It is concluded that most or all of the synapses upon sympathetic neurones become physically dissociated during the chromatolytic reaction of these neurones to axotomy. The failure to persist of ultrastructurally specialized post-synaptic sites, and the loss of desmosomes (particularly marked for those involving purely post-ganglionic nervous elements) suggest that the post-ganglionic neurone is losing all its specializations for attachment. 7. Some evidence suggests that the satellite cells may effect the final separation between pre- and post-synaptic structures. | 165,288 | [
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