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Use of fluorescamine-labeled casein as a substrate for assay of proteinases.
|
Conditions have been investigated for the use of fluorescamine-labeled casein as a substrate for fluorometric assay of proteinases. Fluorescamine-labeled casein can be prepared simply by mixing solutions of casein and fluorescamine at pH 8.0 and used without removal of the excess reagent or its hydrolysis product. The fluorescence of the labeled casein and its enzymatic digest is moderately stable in the range of pH 7.0 to 10.0. Activities can be determined by measuring the fluorescence of the hydrolysis products soluble in 0.1 M trichloro acetic acid solution at pH 4.0 after adjusting the pH of the acid-soluble fraction to 7.7. This method is suited for assay of proteinases active at neutral to slightly alkaline pH values, and is capable of quantitating about 0.05 microgram of trypsin or 0.5 microgram of alpha-chymotrypsin or papain. The assay can be done in the presence of large amounts of contaminating amino acid, protein and/or exopeptidases which may interfere with the ordinary assay of proteinases.
| 27,504
|
Effects of methylprednisolone on hydrogen ion absorption in the canine stomach.
|
The effect of methylprednisolone (2 mg/kg per day given parenterally for 3 doses, 2 wk or 12 wk) on the permeability of mammalian gastric mucosa to hydrogen ion (H(+)) was examined with denervated fundic pouches in dogs with antrectomies. Transmucosal electric potential difference (PD) and net fluxes of H(+) and Na(+) were determined for luminal [H(+)] from 20 to 160 mM and [Na(+)] from 1 to 140 mM ([H(+)] and [Na(+)] were varied reciprocally). The PD was 50-60 mV lumen negative and was constant over the entire range of Na(+) and H(+) concentration tested. Net H(+) flux varied linearly with [H(+)]. Extrapolation indicated apparent H(+) loss at zero luminal concentration, suggesting a basal HCO(3) (-) secretion. Addition of acetylsalicylic acid (ASA) or taurocholate decreased the PD to 30-40 mV and increased threefold the slope of the relation between net H(+) flux and [H(+)] (k(H)). Calculation of PD-independent permeability constants for H(+) (P(H)) with the Goldman constant field equation indicated that this increase in k(H) could not be attributed solely to the associated decrease in PD. Prednisolone administered for 3 doses had no effect on either the basal mucosal permeability to H(+) or the altered permeability induced by ASA or taurocholate. Chronic administration induced a low rate of basal acid secretion (at 12 wk) but had no effect on either PD or k(H). However, the increase in k(H) and P(H) that developed upon addition of ASA or taurocholate in chronically treated dogs was more than one and a half times that of controls. These data suggest that prolonged treatment with glucocorticoids increases susceptibility of the gastric mucosa to damage by agents that increase permeability to H(+).
| 27,530
|
Passive transfer by cells of type II collagen-induced arthritis in rats.
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To investigate the role of immunologic hypersensitivity to collagen in the causation of type II collagen-induced arthritis in rats, passive transfer experiments were performed. Wistar/Lewis rats used in these experiments were demonstrated to be histocompatible by prolonged skin graft survival and mixed lymphocyte cultures. Popliteal lymph node weight assays excluded a potential for graft-vs.-host reactivity in this strain. 9 of 32 naive rats developed arthritis after intravenous receipt of pooled spleen and lymph node cells from donors that had been injected intradermally with type II collagen emulsified in incomplete Freund's adjuvant. This passively transferred synovitis was evident clinically as well as histologically. In control cell transfer experiments involving a total of 97 recipients, transfer of arthritis was shown to require viable cells sensitized to type II collagen. These controls included 17 rats receiving cells from unimmunized donors, 20 recipients of cells from donors injected with incomplete Freund's adjuvant alone, and 24 recipients of cells from rats injected with type I collagen in adjuvant. Deliberate addition of solubilized type II collagen to unsensitized cells at the time of transfer or injection of heat-killed sensitized cells also did not cause arthritis in a total of 36 recipients. These latter two control groups indicate that disease transfer was not the result of antigen carry-over. Intravenous injection of sera from arthritic donors was incapable of passively transferring clinical or histologic synovitis in 30 recipients. Thus, these studies directly implicate immunologic sensitivity to the cartilage type of collagen in the etiology of this autoimmune disease.
| 27,533
|
The indirect assay for leukocyte migration inhibitory factor (LIF)--standardization and the effect of pH.
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In the indirect assay for leukocyte migration inhibitory factor (LIF), lymphokine-rich supernatants were obtained by culture of stimulated lymphocytes and then tested for LIF activity in agarose plates using purified granulocytes as target cells. Studies on the standardization of the conditions under which LIF acts on the target cells are described, with emphasis on the use of "standard" supernatants of known LIF activity and the influence of pH on the action of LIF and the sensitivity of the assay. The observation that LIF activity is reduced when the ambient pH falls below 7.2 is suggested as an explanation firstly for the "escape" phenomenon seen particularly in capillary tube assays for LIF, and secondly for the reduced sensitivity of the capillarly tube assay in comparison with the corresponding agarose plate assay.
| 27,562
|
Neuroleptics related to butaclamol. Synthesis and some psychopharmacological effects of a series of 3-aryl analogues.
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The synthesis and some pharmacological effects of 16 3-aryl analogues of butaclamol, a new antipsychotic drug, are described. The animal models were predictive of neuroleptic activity as well as side effects commonly associated with neuroleptic therapy. The results indicate that the 3-substituent plays a critical role with regard to the potency of the compounds as well as to their tendencies to induce extrapyramidal side effects and/or hypotension.
| 27,637
|
[Acetic acid, a catabolite repressor of cholinesterase synthesis by an Arthrobacter simplex culture].
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Acetic acid was found to repress cholinesterase synthesis in the cells of Arthrobacter simplex var. cholinesterasus even at very low concentrations (0.1%). The repression is very stable. It is not eliminated by glucose or an organic acid of the Krebs cycle being added to the medium with acetic acid. The combination of acetic and butyric acids decreases the repression but does not eliminate it. The kinetics of cholinesterase synthesis was different in the cells grown on the medium with acetic acid and the cells cultivated on the medium with acetic acid and glucose, then washed and transferred to a fresh growth medium with glucose and acetylcholine as the sources of carbon.
| 27,705
|
Thiamine deficiency: selective impairment of the cerebellar serotonergic system.
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To explore the role of thiamine deficiency in synaptic transmission, the high-affinity uptake and release systems for putative neurotransmitters were studied in synaptosomal preparations isolated from the telencephalon, hypothalamus, and cerebellum of rats made thiamine deficient by diet or pyrithiamine. There was significant decrease in the uptake of serotonin by the synaptosomal preparations of the cerebellum. Although thiamine and its phosphorylated forms added in vitro did not restore the decreased serotonin uptake, the administration of the vitamin in vivo resulted in a significant reversibility of the inhibition of serotonin uptake, coinciding with dramatic clinical improvement. The study supports the possibility of an important serotonergic innervation of the cerebellum and suggests a selective involvement of this system in the pathogenesis of some of the neurologic manifestations of thiamine deficiency.
| 27,736
|
31P nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic Escherichia coli cells.
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31P nuclear magnetic resonance spectra of glycolyzing, anaerobic Escherichia coli cells and their perchloric acid extracts were obtained at 145.7 MHz. Time-dependent intracellular concentrations of nucleoside di- and triphosphates, Pi, and sugar phosphates were measured during glycolysis with 2-min resolution, while intracellular and extra-cellular pH values were monitored simultaneously. Upon glucose addition, anaerobic E. coli cells rapidly produce acids and develop a transmembrane pH gradient (delta pH). Glycolysis rates were calculated from the changes in the external pH. It was found that glycolysis rates are strongly dependent on internal pH, sharply decreasing when the pH drops below approximately 7.2. The ATPase inhibitor, dicyclohexylcarbodiimide (DCCD), prevented NTP hydrolysis and inhibited delta pH formation. The uncoupler, carbonyl cyanide p-triflouromethoxyphenyl hydrazone (FCCP), drastically reduced both the delta pH and the NTP level. When the cells were previously treated with DCCD, FCCP collapsed the delta pH while the NTP levels remained high. It is concluded that ATP produced by glycolysis is hydrolyzed by the membrane ATPase to generate a delta pH and that FCCP stimulates ATP hydrolysis by ATPase and collapses the proton gradient.
| 27,785
|
[Treatment of pain with psychotropic drugs (author's transl)].
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30 patients suffering from therapy-resistant chronic pain were divided into three groups according to drive and mood: I. psychomotor inhibition combined with depressive mood, II. agitation and depressive mood, III. agitation combined normal mood. The psychopharmacological treatment of pain showed sufficient results, when the drugs were directed to the target symptoms "agitation", "lack of drive", and "depression". The differentiated administration of activating or sedative antidepressants and neuroleptics caused reduction or absence of pain while the routine administration of neuroleptics (i.e. chlorpromazine) was less effective.
| 27,829
|
Intracellular acid-base state at a variable temperature in air-breathing vertebrates and its representation.
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When temperature changes are superimposed on changes in the control variables of acid-base state (PCO2, strong ion difference), the understanding of acid-base changes becomes difficult. A solution has recently been proposed for blood (Malan, 1977); it was based on the assumption that closed system conditions correspond to a minimal change in the overall acid-base state when temperature varies. The feasibility of extending these concepts to muscle intracellular acid-base vs temperature relationships is evaluated on the basis of a model study; the errors made by replacing closed conditions (which require knowledge of chemical composition) by more convenient approximations are estimated. A representation of both extracellular and intracellular acid-base data on a temperature-corrected bicarbonate-pH diagram is derived. It allows the interpretation of variable-temperature intracellular acid-base changes in terms of changes in control variables, 'respiratory (PCO2) or 'metabolic' (strong ion difference).
| 27,849
|
Intracellular buffering.
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In the quantification of buffering the distinct roles of bicarbonate and of other buffers must be taken into account. The determination of the total non-bicarbonate buffer value, betaa, in intact tissues is complicated by active pH regulation and by heterogeneity of cytoplasm with respect to betaa, while heterogeneity with respect to pH in vivo could cause errors in estimates made with homogenates. Available estimates of betaa are discussed, as are the individual contributions of proteins, dipeptides and phosphates. A high betaa is appropriate in cells which sometimes have high rates of glycolysis, or which buffer extracellular fluid, but non-protein buffer concentrations can be well below the limits imposed by osmolarity, perhaps because buffering can upset ionic gradients.
| 27,854
|
[Preventive practice in dentistry and its current meaning].
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Improvements in the field of sealants and of adhesive restorations based thereon represent the most important new development in preventive dentistry. Caries prevention by means of better nutritional habits is greatly enhanced by newly developed and marketed sugar-free and tooth sparing products. Statistical mortality studies have again demonstrated that prevention by means of fluorides constitutes no danger to public health. Considerable advances have been made in the field of fluoridation of domestic salt. Newer Scandinavian studies revealed that intensive care programs with children including dental hygiene sessions every 3-5 weeks resulted in moderate decreases of caries incidence. By contrast, intensive care programs with adults were extremely successful. By means of 4-6 recall sessions with dental hygienists it was possible to completely stop periodontal destruction for 4, even for 7 years. Apart from initial restorative and conservative dental work, the success of periodontal treatment may be guaranteed only by prevention of recurring gingivitis. Extensive dental statistics from Switzerland reveal a marked success of applied preventive dental medicine. The work of dental practitioners is by now greatly influenced by the new scientific insight gained from research in the prevention of dental disease.
| 27,863
|
The adrenergic mechanism of the haemodynamic effects of massive doses of hydrocortisone in controlled haemorrhagic shock in the dog.
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Haemorrhagic shock was induced in anaesthetized dogs by bleeding them into a blood reservoir system. By adjusting the blood level of the reservoir at a certain distance over the heart level the mean arterial blood pressure was kept at 6.7 kPa (50 mmHg). As has been found earlier, massive doses of hydrocortisone (80-560 mg.kg-1 body weight) caused a dose-dependent decrease in the total peripheral resistance. The degree of vasodilation distinctly increased during concomitant alpha-receptor blockade induced by phenoxybenzamine. The beta-receptor blocking drug propranolol efficiently inhibited the vasodilation caused by hydrocortisone and phenoxybenzamine. The findings fit with the hypothesis that massive doses of hydrocortisone induce an increased stimulation of the adrenergic beta2-receptors of the vascular smooth muscles.
| 27,935
|
Neuromuscular blockade of fazadinium bromide (AH 8165) in renal failure patients.
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Fazadinium bromide (AH 8165) is a new non-depolarizing neuromuscular blocking agent with rapid onset of action and intermediate duration of effect. The characteristics of the neuromuscular blockade induced were compared in normal and renal failure patients by monitoring the mechanical responses of thumb adductor muscle to ulnar nerve stimulation. The data suggest that renal failure, even in anephric patients, does not influence the depth of neuromuscular relaxation when judged from the identical dose-effect curves in both groups of patients. Moreover, the duration of the neuromuscular block was not significantly increased in end-stage kidney failure patients, whether the initial or late phases of the spontaneous recovery of neuromuscular transmission were considered, and this occurred over the entire therapeutic range. However, additional incremental injections of fazadinium bromide should be used cautiously, as evidence appeared of prolonged duration of action. This agent, fazadinium bromide, may therefore present useful advantages to other non-depolarizing neuromuscular blocking agents as to clinical safety and effects in patients with renal insufficiency.
| 27,936
|
Quantitative immunoelectrophoresis of human interferon. A new approach to characterization of interferon preparations.
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The electroimmunoassay (quantitative "rocket" immunoelectrophoresis) method was adopted for analysis and characterization of interferon preparations. Ammonium sulphate-precipitated anti-interferon globulin also containing unknown antibodies against antigens that contaminate interferon preparations was used in the tests. By comparing the results of the electroimmunoassay of fractions obtained by polyacrylamide gel electrophoresis of human leukocyte interferon with the antiviral activity of the fractions, an excellent dissociation of molecules with interferon activity from the bulk of contaminating antigens was achieved. The method is extremely sensitive and requires very small volumes for assay.
| 27,974
|
Khasan virus, a new ungrouped bunyavirus isolated from Haemaphysalis longicornis ticks in the Primorie region.
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Strain LEIV-776P, possessing no haemagglutinating activity was isolated in 1971 in the Primorie region (U.S.S.R.) from Haemaphysalis longicornis Neumann 1091 tick. Complement fixation (CF) tests revealed no antigenic relationship with 24 antigenic groups of arboviruses or 21 ungrouped viruses isolated from ticks. The virus isolate contains RNA and is relatively sensitive to ether and sodium deoxycholate; it is pathogenic for suckling mice and two-week-old white mice by the intracerebral route, and replicates in primary cultures of chick and duck fibroblasts and green monkey kidneys and in a continuous line of pig embryo kidney cells without any cytopathic effect. According to electron microscopy, its size is 90-110 nm. Its morphological properties permit to classify it as a member of the family Bunyaviridae.
| 27,977
|
Butanol extraction of serum and urinary gamma-glutamyltransferase and its application in clinical diagnosis.
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Gamma-glutamyltransferase (gamma-GT) activity was measured in serum and urine before and after extraction with n-butanol. Residual gamma-GT activity after extraction of normal serum with butanol was more than 75%, whereas for normal urine the figure was less than 68%. The loss of activity from urine was not affected by prior dialysis, and the stabilisation which resulted from adding bovine serum albumin at a concentration of 40 g/l did not approach the residual activity with normal serum. In patients with a variety of renal diseases, residual gamma-GT activity in the urine after butanol extraction was inversely correlated with the creatinine clearance. Butanol extraction was performed on serum samples from 182 patients with a variety of diseases. Eighty-one per cent of patients with elevated gamma-GT activities caused by hepatobiliary disease had an increased loss of activity after butanol extraction. By contrast, only 34% of patients with increases gamma-GT activities in whom there was no clinical or other biochemical evidence of hepatic disease, had increased loss of gamma-GT activity after butanol. The reasons for differences between urinary and serum gamma-GT in response to butanol, and the implications in interpreting serum gamma-GT activities are discussed.
| 28,067
|
Changes in liver tyrosine aminotransferase after acute and chronic administration of morphine in the rat.
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Acute administration of Morphine (20 mg/kg/s.c.) in the rat results in a rise of liver tyrosine aminotransferase (TAT) expressed as mumoles of p-hydroxyphenylpyruvate/100 mg/h. With chronic administration, a tolerance develops to this enzymatic effect. TAT induction is not evident in pregnant rats, given the narcotic, in which enzyme levels are already initially high. After delivery TAT returns to normal levels and it is possible to show both induction and tolerance developing to morphine. Enzyme activity in fetal livers is much lower than that of adult animals: after maternal administration of morphine only a modest TAT increase is seen which is not, however, statistically significant. TAT activity is fully evident in livers of offspring, with much higher mean levels in newborn rats from morphine-treated animals, as a possible consequence of morphine deprivation. In this latter group of newborn rats narcotic administration causes TAT activity to return to levels as high as those of naive animals. On the other hand, morphine administration to the prole of naive rats results in an induction of liver TAT.
| 28,112
|
Glycogenosis type II: the infantile- and late-onset acid maltase deficiency observed in one family.
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The concurrence of the infantile and adult form of acid maltase deficiency in one family is presented. The muscle of both cases possesses residual activity. The glycogen amount in the infantile form is increased tremendously, while in the late-onset the amount of glycogen is normal.
| 28,188
|
Considerations on physiopathological approaches to the treatment of hypertension.
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1. Two main physiopathological approaches to the treatment of hypertension are discussed, the first based on renin profiling and the second on haemodynamic measurements. 2. Reduction in plasma renin activity does not appear to be a clinically important mechanism in the hypotensive effect of beta-adrenergic blockers and of alpha-methyldopa. In particular, alpha-methyldopa has been found equally effective as a hypotensive agent both in normal renin and in low renin hypertensive patients. 3. Diuretics are certainly possessed of a renin-stimulating action, but in most patients this action does not obscure the hypotensive effect of these drugs. 4. Responders and non-responders to the hypotensive activity of beta-adrenergic blockers do not differ among them in their control haemodynamics.
| 28,189
|
alpha-Methyldopa and beta-blockers in hypertension--a comparison of their haemodynamic effects.
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1. During acute injection of alpha-methyldopa there is a reduction in the blood pressure within a period of a few hours and a modest reduction in the cardiac output, sometimes due to a modest decrease in heart rate. Frequently the total peripheral resistance is decreased. In contrast, acute injection of beta-blockers induces a marked decrease in heart rate and cardiac output, a compensatory increase in the total peripheral resistance and no decrease in the blood pressure. 2. During long-term use alpha-methyldopa frequently reduces the total peripheral resistance and the reduction in cardiac output is usually modest, at rest as well as during exercise. The beta-blockers reduce the blood pressure, but induce a marked decrease in cardiac output and heart rate. The total peripheral resistance is little affected compared to the pre-treatment level.
| 28,190
|
Urinary dopamine in man and rat: effects of inorganic salts on dopamine excretion.
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1. Plasma and urine free dopamine (3,4-dihydroxyphenethylamine) were measured in six normal male volunteer subjects and the urinary clearance of dopamine was calculated for each subject. 2. The excretion rates for free dopamine in man were greater than could be explained by simple renal clearance. It was concluded that free dopamine must, therefore, be formed in the kidney. 3. Changes in urinary dopamine excretion were studied in four groups of rats initially maintained on low sodium diet and then given equimolar dietary supplements of NaCl, NaHCO3, KCl or NH4Cl, to study the specificity of the previously observed increase in dopamine excretion after increased dietary NaCl. 4. The mean dopamine excretion increased significantly in rats given NaCl, KCl and NH4Cl, whereas dopamine excretion decreased in those given NaHCO3. 5. The failure of dopamine excretion to rise in response to loading with NaHCO3 was unexpected, and argues against a simple effect of volume expansion by the sodium ion. The increase in dopamine excretion with KCl and NH4Cl showed that this response was not specific to the sodium ion.
| 28,196
|
Adenylate cyclase of human gastric mucosa. Stimulation of enzyme activity by histamine and catecholamines.
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Human gastric mucosal adenylate cyclase has been shown to be sensitive to histamine and catecholamines. Stimulation of enzyme activity by histamine and catecholamines were selectively blocked by cimetidine and propranolol, respectively. Combination of both hormones at maximally effective concentrations were additive, indicating that human gastric mucosa contains at least two separate hormone-sensitive adenylate cyclases.
| 28,260
|
Non-beta islet cell tumor calcification assoicated with Zollinger-Ellison syndrome and multiple endocrine adenomatosis.
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The radiographic triad of a calcified pancreatic mass, duodenal ulcers, and nephrocalcinosis should suggest the Zollinger-Ellison syndrome, as part of the multiple endocrine adenomatosis complex. The clinical and radiographic features of the entity are described in this case report.
| 28,264
|
Homologous and cross-reactive precipitins in anti-pneumococcal sera raised in mules.
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Serial bleedings were obtained from two mules during prolonged immunization, one with type XXV the other with type VIII pneumococcal vaccine. IgGa, IgGb, IgGc, IgB, IgG(T) and IgM present among purified Pn anti-XXV and Pn anti-VIII immunoglobulin isolated from various bleedings were identified by use of rabbit anti-equine heavy chain specific reagents. Radioimmunodiffusion with 14C-labelled type XXV pneumococcal capsular polysaccharide and horse and donkey reagents with species specificity directed against donkey or horse IgGa respectively, demonstrated both parental horse and donkey IgGa heavy chain isotypes among the anti-PnXXV antibodies of the interspecies hybrid. Qualtitative and quantitative examination of the cross-precipitation of mule anti-PnXXV sera with the capsular polysaccharides of pneumococcal types IV, X and XA, with birch sap, ketha gum, and with polysaccharides of E. coli, Klebsiella and Rhizobium was carried out and compared with data obtained with anti-PnXXV raised in a horse. Analysis of supernatants from the cross-reactions showed that distinct subfractions had reacted. indicating a marked heterogeneity of the antibodies.
| 28,285
|
Acetylcholine: a possible neurotransmitter in Setaria cervi.
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The total and free acetylcholine (Ach) and cholinesterase (CHE) content of adult Setaria cervi were estimated. The Ach was estimated by bioassay on rectus abdominis muscle of frog and the CHE by measuring the drop in pH following incubation of worm homogenate with Ach chloride. The free and total Ach contents (4.0 +/- 0.57 and 6.0 +/- 0.48 microgram/g wet weight of worms respectively) were as high as found in mammalian brain cortex. The cholinesterase activity was found to be 5.57 +/- 0.6 units/g wet weight of worms. It is possible that there may exist a well developed system responsible for the synthesis, storage, release and destruction of Ach and that Ach may be acting as an excitatory neurohormone in S. cervi.
| 28,290
|
Inhibition of allergic reactions by a new antiallergic drug, LC-6 (trans-2,3b,4,5,7,8b,9,10-octahydronaphthol[1,2-c:5,6-c'] dipyrazole). I. Inhibition of the rat reaginic passive cutaneous anaphylaxis.
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A new synthetic compound, LC-6, has been shown to inhibit the passive cutaneous anaphylaxis reactions induced in rats by mouse reaginic antibody. In this system, the ED50 was 35 mg/kg body weight of LC-6 administered per os. LC-6 prevented neither histamine skin reactions nor the reactions to histamine and other chemical mediators released by 48/80. Therefore, its inhibitory activity is comparable to that of the model anti-allergic compound, disodium cromoglycate (DSCG). In contrast to DSCG, the new drug exhibits the distinct advantage of being active per os and over prolonged periods of time. Its activity has been shown to persist for at least 6 h when doses 4 times higher than the ED50 were administered. The duration of the drug effect was clearly dose-dependent. Predoses of the compound increased its effectiveness. The long-lasting association of LC-6 with mast cells, as indicated by its prolonged inhibitory activity, makes it a valuable tool in the search for receptors involved in anaphylactic reactions.
| 28,295
|
Assessment of long-acting neuroleptics. Methods and problems.
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Long-acting neuroleptics, without offering a therapeutic breakthrough in the treatment of schizophrenia, are nevertheless a definite step in the management of patients with this disorder. The adequate assessment of these agents necessitates methodological considerations to ensure first, just and adequate patient selection, secondly, adaptations to the drug's characteristics, thridly, sufficient duration of the study and finally, special precautions in the assessment of toxicity. Furthermore, the patient management in these studies must ensure continued and easy accessibility of the simultaneously investigating and treating team.
| 28,300
|
Alpha-adrenergic receptors in human and canine tracheal and bronchial smooth muscle.
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We studied the reactions of human tracheal and bronchial smooth muscle and canine trachealis muscle to adrenergic agonists. Human tissue was obtained from recent autopsies of patients with normal lungs and patients with respiratory disorders, and canine tissue was obtained from animals used in other experiments. The muscle was mounted in tissue baths fitted with platinum wire electrodes and the mechanical activity was recorded. Norepinephrine added to the normal human or canine tissue in concentrations up to 10(-5) M caused no reaction. In the normal human and in the dog, pretreatment with histamine or KCl changed this response and when norepinephrine was added the tissue contracted. This contraction was blocked by phentolamine or N,N'-bis-(O-methoxybenzylaminohexyl)-cystamine tetrahydrochloride (BHC). In diseased tissue, the addition of norepinephrine resulted in a contraction that was blocked by phentolamine or BHC and no pretreatment with histamine or KCl was required. These findings demonstrate alpha-receptors in human and canine airway smooth muscle, and there is a difference between normal and diseased human tissue in the reaction of these tissues to alpha-adrenergic agonists.
| 28,308
|
A microelectronic pH sensor.
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This paper presents preliminary data on a new integrated circuit microelectronic pH sensor. The device is extremely miniaturized by the use of integrated circuit technology, and uses the intrinsic hydrogen ion selective properties of the gate insulator material. In order to make the device compatible with aqueous solution monitoring, the silicon dioxide-silicon nitride gate insulator structure is used. The integrated circuit chip was designed, processed, and packaged by a variety of techniques which protect all metal parts from the aqueous solution. Test data are reported on leakage current, sensitivity, reproducibility, linearity, stability, response time, and life. The results indicate that this type of pH sensor may have many significant advantages for biomedical research and application.
| 28,314
|
Reduction in enamel dissolution by liquorice and glycyrrhizinic acid.
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Liquorice extracts and confections reduced enamel dissolution in acidic buffers and saliva/glucose incubations by a direct effect on solubility, and by inhibiting the fall in pH on incubation. These actions may be attributed to the solubility-reducing, glycolysis-inhibiting, and buffering properties of glycyrrhizinic acid, a constituent of liquorice.
| 28,339
|
Effect of 4.5--year use of xylitol and sorbitol on plaque.
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The pH values of xylitol-containing plaque suspensions of persons who habitually used xylitol and sorbitol during 3.2 to 4.5 years did not significantly differ from those observed with suspensions containing no added carbohydrates. Sorbitol produced in 22-hour incubations pH values as low as 3.9 to 5.5. The activity of plaque xylitol dehydrogenase was almost nil, whereas sorbitol dehydrogenase activity was higher. The nonacidogenic nature of xylitol in relation to plaque did not change in prolonged use of xylitol.
| 28,341
|
Low molecular weight C1q-precipitins in hypocomplementemic vasculitis-urticaria syndrome: partial purification and characterization as immunoglobulin.
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A lupus-like syndrome involving chronic urticaria with cutaneous vasculitis, systemic symptoms, hypocomplementemia with preferential depletion of C1q, and low m.w. (7S) C1q-precipitins has recently been defined. The C1q-precipitin activity (C1q-p) seems to represent a diagnostic marker of the disease, but its chemical nature is not yet clear. We have partially purified and characterized C1q-p from the serum of two patients with this syndrome and compared its activity with the C1q-precipitating activity of aggregated human gamma-globulin (AHGG) anti-C1q antibodies, and several polynucleotides including DNA and polyinosinic acid. C1q-p was found to partition with IgG during precipitation by ammonium sulfate and low ionic strength buffer as well as during column chromatography on DEAE-cellulose and G-200 Sephadex. Like AHGG, but in complete contrast to the polynucleotides, the C1q-precipitating activity of C1q-p was sensitive to pepsin, trypsin, and acidic conditions, but unaffected by DNAse or RNAse; the C1q-precipitating activity of anti-C1q antibody was not diminished by any of these procedures. Thus, C1q-p consists of gamma-migrating protein of low m.w., and its C1q-precipitating activity is indistinguishable from that of AHGG. These results are consistent with the concept that C1q-p is comprised, at least in part, of IgG that binds C1q via the Fc portion of the molecule.
| 28,369
|
Renal regulation of acid-base balance in a freshwater fish (1).
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Intra-arterial injection of a fixed acid load caused only a short-lived (less than 2h) disturbance of blood pH but a long lived (2-3 days) elevation of urinary acid excretion in freshwater trout (Salmo gairdneri). The renal response comprised an immediate increase in acid output in the form of titratable acidity minus bicarbonate, and a slower rise in acid output in the form of ammonia. The total elevation in urinary acid efflux over 72h was such that no other mechanism besides renal function is needed to explain the ultimate compensation of this experimental acid-base disturbance.
| 28,376
|
[Disorders of motility of the stomach and pylorus: pathological significance (author's transl)].
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Five different disorders of motility of the pyloric region may be distinguished if direction and velocity of chyme passing through the pylorus are taken into account: 1. Accelerated emptying of food and overacidification of the bulbus duodeni: 2. Bolus emptying of the stomach and rapid increasing hyperosmolarity in the small intestine: 3. Delayed emptying of the stomach and gastric retention: 4. Duodeno-gastric reflux and inflammatory lesions of the gastric mucosa: 5. Other disorders causing pain. Gastric disroders cannot yet be classified on the basis of abnormal motility patterns. It is well known, that the gastric and duodenal motility are regulated by two separate pacemakers located in the distal corpus area and in the bulbus duodeni. Thus it may be speculated that distrubed motility patterns may be due to abnormal pacemaker function.
| 28,457
|
[Methods and problems of investigation of psychopharmacological effect illustrated by the comparison of a novel pyridylbenzodiazepine with diazepam (author's transl)].
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Comparison of two compounds being investigated should take into consideration the most comprehensive spectrum of all psychic variables affected. Consequently, besides 15 standardized investigational methods, three open methods, history, observation of behavior and in particular free exploration were used. The investigation was carried out in 18 ambulant patients who were given the preparations under investigation in a double-blind cross-over trial. Particular problems of the method were the interference of psychotherapeutic effect of the intensive exploration discussions on the action of the preparations, which could be controlled by comparison with a placebo phase, and the effects of learning and stereotype on repeated presentation.
| 28,480
|
[Effect of anions on inhibition of lactate dehydrogenase by pyruvate].
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The effect of anions Cl- and I- on structural and kinetic properties of LDH was investigated. It was shown that anions are specific inhibitors of LDH competing with pyruvate in the active ternary complex, LDHNADHpyq. The following dissociation constants for the anions were obtained from inhibition data: 0.4 +/- 0.02 and 0.07 +/- 0.01 M for Cl- and I-, respectively. The slope of Hill plot are near 1.0. The anions abolished the inhibition of LDH at high pyruvate concentrations. The following dissociation constants were obtained from these data: 0.1 and 0.015 M for Cl- and I- respectively. The inhibition by anions and the abolishing of substrate inhibition by anions were studied also for the lactate oxidation reaction. The dissociation constants for anions obtained from these data are in good correlation with the constants obtained for the pyruvate reduction reaction. It was concluded that anions do not interact with the group at the catalytic site with pK approximately 7.8, presumably His-195. The degree of pyruvate inhibition does not depend on the buffer system. The differences in the degree of inhibition obtained previously in phosphate, imidazole and tris-buffer systems can be explained by the presence of Cl- anions in the last two buffer. The rate constants of hydroxy leads to keto pyruvate transition was obtained in various buffer systems. It was shown that the hydroxy-form of pyruvate does not cause the inhibition of LDH.
| 28,475
|
Fluorescence probe measurement of the intralysosomal pH in living cells and the perturbation of pH by various agents.
|
A quantitative method is described for the measurement of intralysosomal pH in living cells. Fluorescein isothiocyanate-labeled dextran (FD) is endocytized and accumulates in lysosomes where it remains without apparent degradation. The fluorescence spectrum of this compound changes with pH in the range 4-7 and is not seriously affected by FD concentration, ionic strength, or protein concentration. Living cells on coverslips are mounted in a spectrofluorometer cell and can be perfused with various media. The normal pH inside macrophage lysosomes seems to be 4.7-4.8, although it can drop transiently as low as 4.5. Exposure of the cells to various weak bases and to acidic potassium ionophores causes the pH to increase. The changes in pH are much more rapid than is the intralysosomal accumulation of the weak bases. Inhibitors of glycolysis (2-deoxyglucose) and of oxidative phosphorylation (cyanide or azide) added together, but not separately, cause the intralysosomal pH to increase. These results provide evidence for the existence of an active proton accumulation mechanism in the lysosomal membrane and support the theory of lysosomal accumulation of weak bases by proton trapping.
| 28,524
|
Presynaptic modulation of voltage-dependent Ca2+ current: mechanism for behavioral sensitization in Aplysia californica.
|
Behavioral sensitization of the gill-withdrawal reflex of Aplysia is the result of a prolonged increase in transmitter release from the presynaptic terminals of sensory neurons. Earlier work suggested that this presynaptic facilitation might be mediated by a serotonin-sensitive adenylate cyclase in the sensory neuron terminals. Here we present evidence that presynaptic facilitation results from a cyclic AMP-dependent increase in the calcium current that underlies action potentials in the sensory neurons. The action potentials of sensory neuron cell bodies have, in addition to a sodium current, a calcium current that is enhanced by blocking the opposing potassium current with tetraethylammonium. Under these conditions, the action potentials show a slowly repolarizing plateau that follows the Nernst potential for a calcium electrode and serves as a sensitive assay for changes in calcium current. Stimulation of the pathway that mediates sensitization, incubation with serotonin or phosphodiesterase inhibitors, or intracellular injection of cyclic AMP produces an increase in the calcium plateau in the presence of tetraethylammonium. In addition, both before and after sensitizing stimulation, the duration of the plateau potential parallels transmitter release as measured by the amplitude of monosynaptic excitatory postsynaptic potentials evoked in the motor neurons by intracellular stimulation of single sensory neurons. These results are consistent with the idea that presynaptic facilitation is caused by a cyclic AMP-mediated increase in a voltage-sensitive calcium current in sensory neuron presynaptic terminals. This synaptic action is novel in that it can produce little or no change in the resting potential, is of long duration, and exerts its influence directly on a conductance triggered by the action potential, rather than on non-voltage-sensitive conductances, as is typical of conventional synaptic actions.
| 28,527
|
Effect of benzodiazepines on age of vaginal perforation and first estrus in mice.
|
Female mice which received chlordiazepoxide, diazepam, oxazepam, prazepam, flurazepam, or nitrazepam prenatally and postnatally had delays in the age of vaginal perforation and first estrus concomitant with reduced postnatal growth. Females exposed prenatally showed no growth deficits, but in four treatments had delayed vaginal opening. However, the age of first estrus was generally less than the control.
| 28,555
|
Granulomatous hepatitis associated with salicylazosulfapyridine therapy.
|
Granulomatous hepatitis has been associated with many conditions, including chronic ulcerative colitis and sulfonamide therapy. We report a patient with ulcerative colitis in whom hepatic granulomatosis was associated with salicylazosulfapyridine (Azulfidine). Sulfonamides should be considered a possible cause of hepatotoxicity when used therapeutically in inflammatory bowel disease.
| 28,568
|
Utilization of industrial and agricultural by-products for fungal amylase production.
|
Attempts were made for using industrial and agricultural by-products and wastes as carbon and nitrogen sources in fermentation medium for alpha-amylase production by Aspergillus niger NRRL-337. The original carbon source of the basal medium was replaced by one of the following materials: rice bran, wheat bran, corn bran, corn starch, cane molasses, and glucose syrup. Rice bran proved to be the best carbon source that secured the highest amylase activity. The nitrogen source of the basal medium was then replaced by different cheap materials, viz: dried yeast, corn steep liquor, gluten-30, gluten-50, and corn steep precipitate. Corn steep precipitate proved to be superior in amylase production. In consideration of these results an economical medium that secured high activity, containing the following ingredients, was suggested: 2.5% corn steep precipitate, 7.2% rice bran, 0.1% MgSO4, 0.1% KH2PO4, and 0.1% CaCO3. From this medium fungal amylase was precipitated and purified. The pure enzyme gave the highest activity at 40 degrees C and pH 4.3.
| 28,620
|
Accuracy and reproducibility of arterial blood-gas and pH measurements.
|
In 30 patients blood samples were taken from both radial arteries and analysed for PCO2, PO2 and pH. The influence of sampling technique on the accuracy of blood-gas analysis was determined. The 95% confidence limits for PCO2 measurements were +/-0.32 kPa (2.4 mmHg), and for PO2 measurements were +/-1.16 kPa (8.8 mmHg) in the range below 20 kPa, and +/-2.94 kPa (22.0 mmHg) above 20 kPa. For pH, the 95% confidence limits were +/-0.014. Only the PO2 measurements were significantly influenced by the sampling procedure.
| 28,631
|
Carbohydrate metabolism in renal failure.
|
Hyperglycemia and impaired glucose tolerance are well known phenomena occurring in patients with renal failure. In contrast to true diabetic subjects, an elevated ratio of insulin to glucose during the glucose tolerance test is consistently observed indicating a peripheral insulin insensitivity. Among the possible reasons, a disturbance at the cellular level seems to be most likely. There is some evidence of reduced peripheral glucose utilization on the one hand and increased hepatic glucose output--probably by stimulation of gluconeogenesis--on the other. Agents that have been suggested to be involved in these alterations of carbohydrate metabolism in uremia are hormones, electrolytes, pH, and "toxic" metabolic intermediates or end-products. Of these, an increase in insulin antagonistic hormones; among them growth hormone, catecholamines, and glucagon, seems to be of most significance. Although for the individual hormones no equivocal correlation with glucose intolerance has been proved, the interaction of all of them may result in a preponderance of insulin antagonism thus leading to an apparent insulin resistance.
| 28,664
|
Persistent pulmonary hypertension in the neonate: development of an animal model.
|
Chronic intrauterine hypoxia was induced in third-trimester lamb fetuses by daily embolization of the maternal side of the placenta with nonradioactive microspheres. After delivery at term, the chronically hypoxic fetuses had significantly increased pulmonary artery pressures when compared to nonhypoxic control measurements. This preparation appears to be a satisfactory model for experimental study of persistent pulmonary hypertension in the neonate.
| 28,670
|
Glutathione depletion following inhalation anesthesia.
|
Glutathione depletion following inhalation of halogenated anesthetics was investigated as a possible mechanism of toxic reactions associated with anesthesia. Concentrations of reduced glutathione were measured in the blood, liver, lung and kidney of the mouse after anesthesia with enflurane, fluroxene, halothane, isoflurane, methoxyflurane, or trichloroethylene. The anesthetic had no effect on glutathione concentrations in tissues except when fluroxene was used. After two hours of fluroxene anesthesia, glutathione in liver, lung, kidney, and blood was depleted by 93, 85, 85, and 61 per cent, respectively. The depletion was dose-dependent and was more extensive in animals anesthetized after phenobarbital pretreatment. Glutathione was also depleted in livers and lungs of rats anesthetized with fluroxene (60 and 38 per cent, respectively). In blood of rhesus monkeys anesthetized with fluroxene, glutathione was depleted by only 13 per cent. Extents of glutathione depletion are related to fluroxene toxicities in the three species studied.
| 28,682
|
The neuropharmacological actions of amoxapine.
|
Amoxapine possesses a broad spectrum of psychotropic actions, including antidepressant and neuroleptic effects in animals. Antidepressant activity is characterized by its ability to inhibit tetrabenazine-induced depression, antagonize reserpine-induced hypothermia and enhance yohimbine lethality. Neuroleptic activity is demonstrated by the ability of amoxapine to decrease locomotor activity, induce ptosis and catalepsy, inhibit apomorphine gnawing and amphetamine stereotyped behavior and by characteristic changes in monkey discriminated avoidance behavior. The fact that punished responding in squirrel monkeys was present was present after repeated administration may indicate an anti-anxiety action of this drug. Evidence is offered that the conversion of the tertiary terminal nitrogen to a secondary amine may alter the pharmacologica properties of dibenzoxazepines in a similar way to the for the phenothiazines.
| 28,699
|
The effect of chronic administration of digitoxin on the activity of the myocardial (Na + K)-ATPase in guinea-pigs.
|
When guinea-pigs were treated for 24 days with digitoxin 0.3 mg/kg s.c., the activity of the (Na + K)-ATPase of the heart muscle increased by about 30% compared to controls, whereas the enzymes prepared from kidney and brain showed no significant alteration in their activity. In animal species treated with digitoxin for 1 to 5 days, no increase of enzyme activity was observed. Only after 10 to 15 days of treatment, a significant increase of the (Na + K)-ATPase activity was noted which increased no further with treatment up to 24 days. There was no significant difference in the kinetic properties of the (Na + K)-ATPase prepared from digitoxin-treated animals compared to those from control animals; the KM-values for ATP remained unchanged, and there was the same dependence of the activity on the K+-concentration and the same sensitivity towards digitoxin. As there appears to be no significant change in the specific properties of the enzyme, the increase in activity may possibly be caused by an increase in the amount of enzyme as a result of an adaptive enzyme regulation.
| 28,701
|
A characterization of the nucleotide uptake of chromaffin granules of bovine adrenal medulla.
|
Chromaffin granules isolated from bovine adrenal gland were incubated with (3)H-labelled nucleotides and [(14)C]noradrenaline to study the uptake of these substances. [(3)H]ATP, [(3)H]ADP and [(3)H]AMP are taken up by these organelles by the same temperature-dependent mechanism. The apparent K(m) for ATP and ADP is 1.4mm, and for AMP it is 2.9mm. The uptake of ATP has a flat pH optimum, whereas the catecholamine uptake increases with more alkaline pH. Atractyloside and carboxyatractyloside are competitive and specific inhibitors of nucleotide uptake, whereas reserpine inhibits only that for catecholamines. Mg(2+) ions activate uptake of both catecholamine and nucleotides, whereas EDTA and N-ethylmaleimide inhibit these processes. Nucleotide and catecholamine uptakes are inhibited by uncouplers of oxidative phosphorylation and by two ATP analogues. NH(4) (+) ions and nigericin in the presence of KCl inhibit only catecholamine uptake. It is concluded that nucleotide uptake, as proposed previously for catecholamine uptake, depends on an electrochemical proton gradient produced by a proton-translocating adenosine triphosphatase localized in the membrane of chromaffin granules. Furthermore, as suggested by the effect of NH(4) (+) and nigericin, catecholamine uptake apparently depends on the chemical part of this gradient, whereas the results for nucleotide uptake are consistent with its dependence on the electrical component.
| 28,725
|
Quantitation of hydrogen ion and potential gradients in gastric plasma membrane vesicles.
|
The ATP-dependent uptake of H+ by hog gastric parietal cell vesicles was quantitated by using the pH indicator dyes bromcresol green and malachite green, the weak bases, aminopyrine and 9-aminoacridine, and the pH electrode. A K+-dependent H+ uptake was found, with a significant difference between the quantity of H+ disappearing from the medium (deltaHo) and the quantity appearing inside the vesicle (deltaHi). 9-Aminoacridine gave a lower value for the deltaHi than any of the other probes. Probes of potential such as diethyloxadicarbocyanine or oxonol dyes showed that only secondary diffusion potentials occurred during H+ uptake and that the cationic dyes in the presence of protonophores could also be used to quantitate H+ uptake. The potential in the presence of protonophore indicated a deltaHi greater than that found with the other probes. Binding sites for acridine orange were generated either by ATP or an artificial pH gradient and corresponded to the deltaHi indicated by aminopyrine. SCN- (30mM) only partially inhibited the H+ gradient, and this, coupled with the failure to detect the physiological deltapH of 6.6, indicated that these vesicles may be an incomplete model of gastric acid secretion.
| 28,748
|
Sidedness of inhibition of energy transduction in oxidative phosphorylation in rat liver mitochondria by ethidium bromide.
|
Ethidium bromide, a new type of inhibitor of energy transduction in oxidative phosphorylation, inhibited ATP synthesis in intact mitochondria but not in submitochondrial particles, the latter being inside-out relative to the membranes of intact mitochondria. Ethidium bromide incorporated inside the submitochondrial particles inhibited ATP synthesis in the particles. The decrease of the membrane potential by valinomycin (plus KCl) inhibited only slightly the energy-dependent binding of ethidium bromide to the mitochondria. The present results show clearly that ethidium bromide inhibited energy transduction in oxidative phosphorylation by acting on the outer side (C-side) of the inner mitochondrial membrane, perhaps by neutralizing negative charges created on the surface of the C-side, and that it had no inhibitory activity on the inner side (M-side) of the membrane. Th present results show also that the energy-dependent binding of ethidium is not due to electrophoretic transport down the membrane potential; ethidium may bind to negative charges on the surface of the C-side. The present study suggest that an anisotropic distribution of electric charge in the inner mitochondrial membrane is an intermediary high energy state of oxidatvie phosphorylation.
| 28,755
|
Mechanism of generation and regulation of photopotential by bacteriorhodopsin in bimolecular lipid membrane.
|
Photoelectric properties of bacteriorhodopsin incorporated into a bimolecular lipid membrane were investigated with special regard to the mechanism of photoelectric field generation. It was shown that besides its proton pump and electric generator functions bacteriorhodopsin works as a possible molecular regulator of the light-induced membrane potential. When a bimolecular lipid membrane containing bacteriorhodopsin is continuously illuminated in its main visible absorption band, and afterwards by superimposed blue light matching the absorption band of the long-living photobleached bacteriorhodopsin (M412) as well, the latter either enhances or decreases the steady-state photoresponse, depending upon the intensity of the green light. Thus, the additional blue-light illumination tends to cause the resultant photoelectric membrane potential to become stabilized. Two alternative schemes are tentatively proposed for the photochemical cycle of bacteriorhodopsin whereby blue light can control photovoltage generation. A kinetic model of the proton pump and the regulation of the photoelectric membrane potential is presented. This model fits all the experimental findings, even quantitatively. From the model some kinetic and physical parameters of this light-driven pump could be determined.
| 28,756
|
Zinc stoichiometry in Escherichia coli alkaline phosphatase. Studies by 31P NMR and ion-exchange chromatography.
|
31P nuclear magnetic resonance spectra and enzymatic activities are compared for alkaline phosphatase (orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1) species with different zinc contents. The enzyme containing two Zn2+ per protein dimer exists in two forms; one, prepared by dialysis of native enzyme, has full enzymatic activity and a 31P magnetic resonance spectrum similar to but distinguishable from that of the native enzyme containing four or more Zn2+. The other form, prepared by restoring two Zn2+ to apoenzyme, has low enzymatic activity and a 31P magnetic resonance spectrum that indicates stoichiometric binding of phosphate, but otherwise altered properties. Reconstituted enzyme with four Zn2+ is similar to but distinguishable from native enzyme with four Zn2+. Chromatography on DEAE-cellulose can separate apoenzyme and enzyme containing two Zn2+ and suggests that the binding of a pair of Zn2+ is cooperative.
| 28,775
|
3-Chloroacetylpyridine adenine dinucleotide phosphate, an alkylating analogue of NADP+.
|
An alkylating analogue of NADP+ the 3-chloroacetylpyridine adenine dinucleotide phosphate was prepared from 3-diazoacetylpyridine adenine dinucleotide phosphate which was obtained by enzymatic transglucosidation of NADP+. The 3-diazoacetylpyridine adenine dinucleotide phosphate proved to be more unstable when compared to the corresponding NAD+ analogue. The alkylation of several dehydrogenases using this alkylating analogue is mentioned.
| 28,788
|
Immunological profile in sarcoidosis patients. The in vitro and in vivo effect of thymic humoral factor.
|
A study was made of the lymphocytes obtained from 25 patients suffering from sarcoidosis as proved by the Kveim-Siltzbach test and/or organ biopsy. The number of T lymphocytes was determined by the E rosette technique and functional activity by a local xenogeneic graft-versus-host reaction (GVHR) as well as skin tests with PPD, SK-SD, Candida and Trichophyton. In most cases the absolute number of T cells was low and there was an evident impairment of their functional activity. There was also a clear correlation between the severity of impairment of cell-mediated immunity and the clinical stage and activity of the disease. In vitro incubation of the lymphocytes with thymic humoral factor resulted in recovery of the functional activity of the T lymphocytes of 4 of the 7 patients tested, with the previously negative GVHR becoming positive. One of these patients was treated with thymic humoral factor with a resulting restoration of the cell-mediated immune response although there was no evident clinical improvement.
| 28,795
|
The isolation and identification of 2,4-diketones present in human and animal tissues and in urine.
|
The chemical isolation of 2,3-diketone fraction from hydrolysates of various mammalian tissues has been accomplished by the use of a modified Girard T procedure. This fraction, which constitutes a new lipid class, has been resolved by gas chromatography into a number of homologous 2,4-diketones, ranging in chain length from C13 to C25. After separation by preparative gas chromatography, the following compounds have been unequivocally identified: 2,4-heptadecanedione, 2,4-nonadecanedione, 2,4-heneicosanedione, 2,4-docosanedione, and delta12-2,4-heneicosenedione. The 2,4-diketones appear to exist in tissues in the free state or in labile combination. They are present also in human urine.
| 28,820
|
Properties of poly(ADP-ribose) synthetase from rat pancreas and poly(ADP-ribosylation) of basic nuclear proteins.
|
The isolated nuclei of rat pancreas contain an enzyme system that will incorporate 3H-labeled NAD into an acid-insoluble product, which is shown to be poly(ADP-ribose). The enzyme has an optimum pH of 7.8 and the optimum temperature is between 20 and 30 degrees C. Optimum Mg2+ concentration is 8 mM and dithiothreitol also stimulates the enzyme at a concentration of 8 mM. Under standard conditions, the Km value for the reaction is 0.25 mM and an inhibition by the substrate is observed at high substrate concentrations. It has also been found that only one basic nuclear protein, that is, histone H1, is modified by the synthetase. An average chain length of 5.0 is found in the nuclei and of 4.5 on histone H1. Radioautographic studies show that poly(ADP-ribose) is closely associated with chromatin.
| 28,822
|
Disposition of 4,5-diphenyl-2-oxazolepropionic acid (oxaprozin) in beagle dogs and rhesus monkeys.
|
Following intragastric doses of 14C-oxaprozin to beagle dogs and rhesus monkeys, oxaprozin was rapidly absorbed and was essentially the only drug-related substance in the plasma for at least 24 hr. Recovery of radioactivity in the excreta was 87% in both species, with the fecal route accounting for almost all of the excretion by the dog, and the urinary route predominating in the monkey. The drug was slowly eliminated by both species. The concentrations in tissues of monkeys were generally less than those in plasma, and their decline with time paralleled that in plasma. High concentrations of 14C were found in the bile and urine. Qualitative and quantitative metabolite patterns of both fluids were similar. About 90% of the 14C in both bile and urine was recovered as identified compounds in the free, ester conjugate, and ether conjugate fractions. The ester conjugate fraction, mainly consisting of oxaprozin glucuronide, was quantitatively the most important in both fluids. Two phenolic metabolites were characterized by mass spectrometry and co-chromatography. They were present in free form and as ester and ether glucuronides.
| 28,928
|
Comparative metabolism of hydrocodone in man, rat, guinea pig, rabbit, and dog.
|
The metabolism of hydrocodone was studied in man, rat, guinea pig, rabbit, and dog. Routes of metabolism included O-demethylation, N-dealkylation, and 6-keto-reduction to the corresponding 6-alpha- and 6-beta-hydroxy metabolites, where each metabolic pathway produces an active metabolite. Mean total recovery of drug and metabolites as percentage of administered dose ranged from a low of 10.6% for the rabbit to a high of 46.8% for the guinea pig; man was intermediate at 25.7%. For man, approximately 70% of the total drug recovered was excreted in the first 24 hr, and the remainder by 72 hr. Considerable species differences were observed in the patterns of metabolism of hydrocodone. Also, stereoselectivity of 6-keto reduction to the beta-form was observed for all species in the reduction of hydrocodone and hydromorphone with the exception of the reduction of hydrocodone by man.
| 28,931
|
[The effect of etilefrine and dihydroergotamine on sympathetic nervous system activity when standing up (author's transl)].
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Systolic blood pressure, heart rate and concentrations of adrenaline, noradrenaline and dopamine as well as plasma dopamine-beta-hydroxylase (DBH) were measured in 22 subjects in recumbency and on standing up. Six subjects each had previously been given intravenously dihydroergotamine (0.5 mg) or etilefrine (0.25 mg/min) or a placebo. It was demonstrated that orthostasis leads to an increased activity of the sympathetic nervous system and the adrenal system. After administration of dihydroergotamine there was a diminished reaction of the sympathetic nervous system with an increase of venous tone which counteracted the decrease in cardiac output. Etilefrine, on the other hand, inhibited the sympatho-adrenal reaction on orthostasis and decreased the liberation of adrenaline. It acts directly via stimulation of alpha-and beta-receptors and is thus predominantly indicated if there is insufficient response of the baroreceptor reflex at its efferent limb.
| 28,936
|
Characterization of glucuronide metabolites of carbamazepine in human urine by gas chromatography and mass spectrometry.
|
Glucuronide metabolites of carbamazepine (5 H-dibenz[b,f]azepine-5-carboxamide) were identified in human urine following chromatography on XAD-2 resin, permethylation, and combined gas chromatography and mass spectrometry with an SE-30 capillary column. Eight glucuronide metabolites, previously unidentified in man, were characterized as their permethylated derivatives. These included carbamazepine N-glucuronide (M+. 482), three isomers of dihydroxycarbamazepine O-glucuronide (M+. 542), three isomers of hydroxymethoxycarbamazepine O-glucuronide (M+. 542), and one isomer of hydroxycarbamazepine O-glucuronide (M+. 512). Other glucuronide metabolites, previously identified following enzymatic hydrolysis, were characterized as the unhydrolyzed, permethylated glucuronides, 10,11-dihydro-10,11-di--hydroxy carbamazepine O-glucuronide (M+. 544), and three isomers of monohydroxycarbamazepine O-glucuronide (M+. 512).
| 28,932
|
[Comparative trials on sultopride and fluanisone].
|
A therapeutic trial has been carried out on 50 patients, most of them being hospitalized, in order to compare the characteristics of a new benzamide, Sultopride, to those of a butyrophenone, Fluanisone, for the treatment of important and chronic agitation states. Clinically, they were essentially psychotic states, with dissociation. From this trial it appeared that sultopride is superior to fluanizone with regard to their sedative effects and that it has specific characteristics: a very powerful antipsychotic action, an increasing efficiency over time, as well as an improvement of incoercible agitation in children. Thus, the present trial has checked out the well-known sedative action of Fluanisone, and has revealed a new major antipsychotic drug, Sultopride, the superiority of which lies on a much wider therapeutic field.
| 28,939
|
Benign hydatidiform mole in Ibadan, Nigeria.
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A study was conducted to analyze 61 patients with benign hydatidiform mole (HM) who were admitted to the University College Hospital in Ibadan, Nigeria, during a 5-year period. The hospital incidence of HM was 1:205 pregnancies, and the condition was seen most commonly in young women, probably because early marriage is customary in our culture. Management of the condition generally was conservative because of the patients' youth. There was no correlation between HM and parity. Vaginal secondaries due to an embolic phenomenon were detected in 5% of the patients. Subsequent pregnancies followed within 6 months of treatment because the majority of the patients failed to heed medical advice to delay pregnancy for 2 years. No diagnostic problems were encountered in the patients who became pregnant during the follow-up period.
| 28,968
|
Respiration and oxidative phosphorylation in Treponema pallidum.
|
Exogenous and endogenously generated reduced pyridine nucleotides caused marked stimulation of O(2) uptake when added to treponemal cell-free extracts, which indicated that terminal electron transport was coupled to the consumption of O(2). Oxidation of reduced nicotinamide adenine dinucleotide (NADH) was shown to correlate stoichiometrically with O(2) reduction, suggesting that NADH was being oxidized through a mainstream respiratory chain dehydrogenase. Oxygen evolution in treponemal extracts was observed after the completion of O(2) uptake which was stimulated by exogenous NADH and endogenously generated reduced NAD phosphate. Oxygen evolution was inhibited by both cyanide and pyruvate, which was consistent with O(2) release from H(2)O(2) by catalase. The addition of exogenous H(2)O(2) to treponemal extracts caused rapid O(2) evolution characteristic of a catalase reaction. A spectrophotometric assay was used to measure ATP formation in T. pallidum cell-free extracts that were stimulated with NADH. P/O ratios from 0.5 to 1.1 were calculated from the amounts of ATP formed versus NADH oxidized. Phosphorylating activity was dependent on P(i) concentration and was sensitive to cyanide, N, N'-dicyclohexylcarbodiimide, and carbonyl cyanide m-chlorophenyl hydrazone. Adenine nucleotide pools of T. pallidum were measured by the firefly luciferin-luciferase assay. Shifts in adenine nucleotide levels upon the addition of NADH to cell-free extracts were impossible to evaluate due to the presence of NAD(+) nucleosidase. However, when whole cells, previously incubated under an atmosphere of 95% N(2)-5% CO(2), were sparged with air, ATP and ADP levels increased, while AMP levels decreased. The shift was attributed to both oxidative phosphorylation and to the presence of an adenylate kinase activity. T. pallidum was also found to possess an Mg(2+) - and Ca(2+) -stimulated ATPase activity which was sensitive to N, N' -dicyclohexylcarbodiimide. These data indicated a capability for oxidative phosphorylation by T. pallidum.
| 29,009
|
Antibiotics excretion in canine vaginal and urethral secretions.
|
Trimethroprim, erythromycin, ampicillin, and rosamicin, a new macrolide antibiotic, were administered to dogs by constant intravenous infusion. Their concentrations in plasma, urine, vaginal and urethral secretions, saliva, and tears were determined by bioassay. Trimethoprim, rosamicin, and, to a lower degree, erythromycin were concentrated in the secretions of the vagina and the urethra whereas the ampicillin concentrations in these secretions never exceeded the simultaneous plasma concentrations. Inasmuch as rosamicin and trimethoprim have antibacterial spectra well suited for the treatment of bacterial urethritis and vaginitis they should be investigated clinically in this respect.
| 29,017
|
Psychoactive drug interactions.
|
Interactions can arise from serial or simultaneous administration of 2 or more drugs. Interactions with other medications can enhance or diminish either the clinical usefulness of a drug, or its toxic effects. Interactions can arise from changes in absorption, protein binding, metabolism, excretion or activity at a common site of action. Drug interactions of clinical interest to psychiatrists are described. The drugs include: stimulants, neuroleptics, tricyclic antidepressants, monoamine oxidase inhibitors, lithium, anticonvulsants, and sedatives and hypnotics.
| 29,033
|
Membrane bioenergetic parameters in uncoupler-resistant mutants of Bacillus megaterium.
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Mutants of Bacillus megaterium displaying malate-driven ATP synthesis resistant to uncouplers of oxidative posphorylation are further characterized. Both the pH gradient and electrical potential generated across the membrane by malate respiration are equally sensitive to uncouplers in the wild type and uncoupler-resistant mutants. The mutants possess 0 to 10% of the wild type ATPase activity which is not activated by pretreatment with heat or trypsin. Despite this inability to measure ATPase activity, the mutants demonstrate acid-pulse-driven ATPase synthesis which is sensitive to uncouplers as well as malate-driven ATP synthesis which becomes uncoupler sensitive at pH 5.5. N,N' -Dicyclohexylcarbodiimide and valinomycin plus potassium inhibition of ATP synthesis is reversed by uncouplers in the mutants but not in the wild type. The data support the existence of a specific site on the ATPase complex for uncoupler binding which, if altered by mutation, affects uncoupler binding to the complex. The retention of malate-driven ATP synthesis in the absence of a significant pH gradient or electrical potential suggests that an alternative intermediate is involved in coupling oxidation to phosphorylation.
| 29,041
|
Direct evidence of participation of rat lung carbonic anhydrase in CO2 reactions.
|
Isolated rat lungs were ventilated with air and perfused with a blood-free Krebs-Ringer bicarbonate solution under conditions of net CO2 elimination in the lung. Some of the effluent perfusate was drawn through a stop-flow pH electrode apparatus, arriving at the electrode within 4 s after passing through the pulmonary capillaries. pH and temperature of the fluid in the electrode chamber were continuously monitored both before and after withdrawal was suddenly stopped. Little or no change was observed in the pH of the perfusate after flow was stopped, despite the fact that CO2 was eliminated in the lung, suggesting that the conversion of H2CO3 to CO2 in the blood-free perfusion fluid was markedly accelerated and the rise in pH was complete by the time the perfusate reached the electrode. Because the effluent perfusate was shown to be free of carbonic anhydrase activity, the catalysis must have occurred during transit through the isolated lung. When acetazolamide was added to the perfusate, a rise in the pH of the perfusate after stopping flow was consistently seen. These results suggest that the carbonic anhydrase of isolated lungs accelerates the conversion of H2CO3 to CO2 and enhances COW elimination as perfusate passes through the pulmonary capillaries, and that the enzyme may be present on the capillary endothelial surface.
| 29,055
|
Selective defect of precursor T cells associated with apparently normal B lymphocytes in severe combined immunodeficiency disease.
|
Two patients, one with an autosomal and the other a sex-linked form of severe combined immunodeficiency, had more than 95% B cells in their peripheral blood. Despite an increased absolute number of B lymphocytes, the patients were unable to produce serum antibodies. In each patient, geno- or pheno-identical bone marrow transplantation was followed by the visualization of a thymus shadow and the appearance of both cellular and humoral functions. Chromosome of allotype studies showed that the T cell originated from the donor whereas serum immunoglobulins were synthesized by host B cells. In these patients the pathogenesis appears to be a selective defect of bone marrow precursor T cells without concomitant intrinsic B cell defect. The successful outcome of the graft in these two patients, who are now, respectively, 5 years and 11 months of age and free of infections, indicates that the preferred form of therapy in such patients is transplantation of bone marrow stem cells, which populate the thymus and mature slowly into T cells that cooperate fully with host B cells in synthesis of antibody.
| 29,085
|
The effect of microcapsule size on the oxidative decomposition of core material.
|
The factors that affect the size of microcapsules and the oxidation of their benzaldehyde core have been examined. The pH of the preparation changed the overall size of the microcapsules which reached a maximum diameter at pH 4.1. The size of the core droplets also varied with the preparative pH and their oxidation rate depended on the bulk droplet size rather than their surface area. A rapid oxidation of benzaldehyde associated with the microcapsule wall resulted in a preliminary peak in the oxidation curve. Explanations for these phenomena are discussed.
| 29,089
|
Developmental restrictions on hormone modulated gene transcription. II. Hormone induced interactions of RNA polymerase with chromatin.
|
Chromatin-bound and soluble RNA polymerase subspecies have been isolated and fractionated by isoelectric focusing at various times (0, 6, 12 and 18 h) following auxin treatment of 4 day (responsive) and 8 day (unresponsive) soybean hypocotyls. Young 4 day seedlings displayed two well defined phases of auxin induced gene transcription. Phase I (6 h) evidenced the selective dissociation of many RNA polymerase subspecies from the chromatin complex which was accompanied by the retention of three class II enzymes. Phase II occurred after 12 h of treatment when the dissociated enzymes including some species which were soluble in the 0 h controls became re-associated with chromatin. These induced RNA polymerases may be responsible for the synthesis of auxin induced RNAs. In contrast, the unresponsive 8 day hypocotyl did not display two phases of auxin induction. Phase one, the dissociation of the chromatin bound enzymes, occurred at 12 h (compared to 6 h for the 4 day seedling) and was not followed by the later translocation of any soluble enzymes towards the chromatin complex. The results support earlier findings suggesting that the developmental "phasing out" of RNA polymerase subspecies limits the hormone induced growth response of this tissue and thus is regarded as an off switch for the transcription of such hormone controlled gene sequences.
| 29,171
|
High pyruvate kinase activity causes low concentration of 2,3-diphosphoglycerate in fetal rabbit red cells.
|
1. The high oxygen affinity of fetal blood in rabbits is due to a very low concentration of 2,3-diphosphoglycerate (2,3-DPG) in the red cells. In order to gather informations on the factors responsible for this characteristic we have studied synthesis and break-down of 2,3-DPG in fetal and adult rabbit red cells in vitro and examined possible regulative pathways which may lead to the low 2,3-DPG concentration in vivo. 2. Under conditions where 2,3-DPG and 3-phosphoglycerate (3-PGA) accumulate in adult erythrocytes, i.e. in a solution containing inosine, pyruvate and inorganic phosphate, the amount of 2,3-DPG synthetized in fetal red cells was only 40% of the adult value and 3-PGA was not measurable. Upon inhibition of enolase by NaF, however, both 2,3-DPG and 3-PGA increased to a similar extent in fetal and adult red cells. These findings point towards differences in the pyruvate kinase (PK) reaction which is one of the rate limiting steps of glycolysis. Direct measurements revealed an over tenfold higher PK activity in fetal compared to adult red cells. This higher activity of PK will lead to a decreased concentration of 3-PGA with a consecutive fall in 2,3-DPG concentration. 3. Other factors, like a decreased glucose utilization, a decreased activity of 2,3-DPG mutase or an increased 2,3-DPG phosphatase activity could be excluded as a cause for the low 2,3-DPG concentration in fetal red blood cells. The same holds for extraerythrocytic factors like glucose concentration or pH value in fetal blood. 4. During the postnatal development of rabbits the PK activity decreased. 50 days after birth, PK activity was 20% of the fetal value but still somewhat higher than in adult erythrocytes. This change is paralleled by an increase in 2,3-DPG concentration and half saturation oxygen pressure. With respect to the synthesis of 2,3-DPG and ATP, the fetal rabbit red cell is comparable to hereditary high PK activity in human erythrocytes.
| 29,278
|
A new putative neuroregulator of the extrapyramidal system.
|
A putative neurotransmitter, 2-phenylethylamine, which is most highly concentrated in the extrapyramidal system of human brain, is able to reverse reserpine-induced parkinsonism in animals and elicit stereotypy. This action is only partially antagonized after catecholamine depletion by pretreatment with a-methyl-para-tyrosine, and fully blocked by pretreatment with haloperidol, a dopamine receptor blocker. Therefore, via direct and/or indirect actions, 2-phenylethylamine may serve a neuroregulatory role in the extrapyramidal system.
| 29,315
|
[Neuroleptics and sexual dysfunction in man. Neuroendocrine aspects].
|
Sexual behaviour and fertility of schizophrenic patients are discussed. The various sexual dysfunctions induced by neuroleptics, such as decrease in libido, troubles of ejaculation and impotence, are described and related to their various mechanisms of action. The central antidopaminergic effect of neuroleptics would be responsible for an overall non-specific decrease in libido. Their effect upon the autonomous nervous system would explain ejaculation disturbances. Their endocrine action (increase in prolactine) would produce impotence. The possibility of treatment of these endocrinological troubles by bromocriptine is discussed.
| 29,337
|
[Acid-base state disorders and their correction in acute mesenteric vascular obstruction].
|
The results of the investigation of main indices of acid-base equilibrium in 28 patients with acute obstruction of the mesenteric vessels are set forth. 12 patients out of 28 developed subcompensated or decompensated metabolic acidosis. The authors believe that the correction of acid-base equilibrium disorders is an efficacious factor of intense therapy and recommend to use it at all the stages of the treatment.
| 29,372
|
In vitro and in vivo studies on Leydig cell function in old rats.
|
Young adult (3 months old) and old (26-28 months old) male Wistar rats were studied. Testicular weight was 1.66 g (range: 1.33--2.86) in the younger group and 1.62 g (range: 1.04--1.90) in the older group. The total Leydig cell volume as measured by a quantitative histometric method was significantly larger in the old animals (-x = 0.153 ml vs. -x = 0.089 ml). The testicular HCG binding capacity was 2.54 ng HCG per 100 mg tissue (range: 1.88--3.77) in the younger animals and 1.83 ng HCG per 100 mg tissue (range: 0.80--3.02) in the older ones (P less than 0.01). Plasma testosterone was on an average 242 ng/100 ml (range: 72--1162) in the young adult rats and 91 ng/100 ml (range: 23--277) in the older rats. Plasma LH was only slightly (P less than 0.05) decreased and was 49 ng LH-RP-1/ml (range: 14--120) in the younger group and 40 ng LH-RP-1 ng/ml (range: 5--98) in the older. When the testicular tissue pieces were incubated with different doses of HCG or dibutyryl cAMP and testosterone production was measured, identical dose-response curves for old and young tissue were obtained. After in vitro incubation with a NADPH generating system, which under the conditions used was a much stronger stimulus for steroid biosynthesis than HCG or dibutyryl cAMP, the tissue of young rats produced about twice the amount of testosterone precursors (pregnenolone, progesterone, 17alpha-hydroxyprogesterone and androstenedione) than old tissue.
| 29,425
|
Studies on calcium uptake by myometrial microsomes with particular reference to the dependence on inorganic phosphate and oxalate.
|
Ca uptake by microsomes isolated from non-pregnant rabbit myometrium was potentiated by both inorganic phosphate (Pi) and oxalate anions. Both Pi and oxalate had little effect on the initial rate of uptake but a pronounced effect on the capacity of Ca uptake measured after 20 min which was greater in the presence of oxalate than that of Pi (5 mM each). The presence or absence of sucrose in the uptake medium had a significant effect on oxalate-induced potentiation of Ca uptake but not on that potentiated by Pi or that measured in the absence of either potentiating anion. A part of Ca accumulated additionally under the influence of sucrose could be removed by washing microsomes with KCl. Another significant difference between the pontentiating effect of oxalate and Pi was observed when the pH of the incubation medium was varied. In the presence of oxalate the pH optimum was between 6.4--6.8, whereas that in its absence or in the presence of Pi the optimal pH was around 7.2. Reduction in pH from 7.2 to 6.8 along with the substitution of KCl by sucrose resulted in 3-fold increase in Ca uptake when oxalate was used as the potentiating anion. The results suggest that Ca is taken up by a different mechanism in the presence of oxalate than that in its absence or when oxalate anion is substituted with inorganic phosphate.
| 29,440
|
A controlled long-term study of flunitrazepam, nitrazepam and placebo, with special regard to withdrawal effects.
|
The hypnotic effect of flunitrazepam (Ro 5-4200), nitrazepam and a placebo was studied in 117 outpatients using hypnotics for at least 3 months prior to the study. They obtained various neurotropic drugs and this and other treatments were unchanged throughout the trial period of 13 weeks. This consisted of 3 weeks on the previously used hypnotic, 3 weeks on a test drug (during the first of these a doubling of the dose was permitted if the initial dose of 1 mg flunitrazepam, 5 mg nitrazepam or one tablet of placebo was not satisfactory) and 4 weeks' observation after a request to stop medication with the test drug. The effects were evaluated every week by self-ratings. Also noted were: the frequency of dose increase after 1 week of the test period, number of drop-outs in the test period, and failure in the attempt to stop taking the test drug. A "psychological concentration test" was done, as was a follow-up interview. The self-ratings had a good reliability and showed that more patients experienced shorter sleep induction, longer sleep time, better sleep quality and a subjective feeling of having had a better rest with flunitrazepam than with either nitrazepam or placebo. There were no differences between the nitrazepam and the placebo groups. Tiredness was the most common side effect and appeared in the same frequency in all groups. The number of patients who increased the dose after 1 week's medication, as well as the number of drop-outs, was significantly higher in the nitrazepam and placebo groups than in the flunitrazepam group. There was no difference in the ability to discontinue the medication between the test groups or between groups having previously used different hypnotics. The "psychological concentration test" did not reveal any differences between groups. It was concluded that withdrawal of a hypnotic in chronic users was not facilitated by the use of a placebo. This was interpreted as due to a strong psychological dependence upon the hypnotics and their lack of pharmacological effects during long-term treatment.
| 29,441
|
Interaction between PCO2 and plasma [HCO-3] in regulation of CSF [HCO-3] in respiratory alkalosis and metabolic acidosis.
|
The results of studies presented may be interpreted in light of the dual contribution theory of regulation of CSF acid-base balance, indicating significant interaction between systemic and local CNS mechanisms in H+ homeostasis in the brain and CSF. Both systemic and local mechanisms are at work in H+ homeostasis in the brain and CSF and depending on the specific acid-base disorder or the duration of the imbalance one or the other of the two factors may be the dominant one in maintaining H+ levels in the "normal" range. These factors come into play only when there has been a change in central pH with the primary aim of bringing the CNS [H+] towards normal.
| 29,457
|
Strain differences in electrophoretic mobility of influenzavirus A polypeptides.
|
Slab polyacrylamide gel electrophoresis of Influenza-virus A strains varying in antigenic composition of the envelope and in the natural host species showed the nucleprotein and membrane proteins to have a standard molecular weight of 58,000 and 24,000 daltons, respectively. The electrophoretic mobility and molecular weights of the light and heavy chains of haemagglutinin varied in the strains under study. The differences observed persisted on passaging and were transferred upon genome recombination.
| 29,472
|
Evaluation of the counterimmunoelectrophoretic (CIE) procedure in a clinical laboratory setting.
|
The counterimmunoelectrophoretic (CIE) procedure was evaluated under clinical laboratory conditions to determine its validity and comparability with culture methods. The procedure was further evaluated to determine applicability to a variety of clinical samples. An inexpensive set-up was developed to utilize the CIE procedure at bench level. Results indicated the procedure to be sensitive in detecting Haemophilus influenzae, type b, and Neisseria meningitidis (meningococcus), group B. The procedure was more sensitive for detection of H. influenzae, type b, than for meningococcus, group B. The authors have confirmed the usefulness of the CIE procedure in the detection of group B streptococci, pneumococci and teichoic acid antibody to Staphylococcus aureus. Detection of Escherichia coli K 1 antigen was also accomplished by CIE. In the authors' laboratory the CIE procedure was superior to culture methods when used for the detection of H. influenzae, type b, and meningococcus group B.
| 29,483
|
Ammonia metabolism.
|
The pathways responsible for an the mechanisms underlying the adaptive increase in ammonia production in response to acidosis are considered. It seems unlikely that the cytosolic pathways (glutamine synthetase, glutaminase II, phosphate-independent glutaminase, and gamma-glutamyl transferase) are of primary importance in the adaptive process, but the role of the purine nucleotide cycle has not been resolved. The intramitochondrially located phosphate-dependent glutaminase pathway is generally believed to be of primary importance. Adaptation involved either enhanced glutamine entry into the mitrochondria and/or activation of phosphate-dependent glutaminase, but the relative importance of each has not been resolved definitively. The overall adaptive response is probably modulated by factors regulating alpha-ketoglutarate metabolism to phosphoenolpyruvate, and possibly also by metabolism of TCA cycle intermediates. It seems unlikely that a decrease in systemic pH is the direct effector for the acidosis-induced increase in ammonia formation; however, the resulting decrease in urine pH may play a critical role. Other potential messengers, including potassium, glucocorticoids, mineralocorticoids, cyclic AMP, and calcium probably do not serve a primary function, but the importance of other circulating factor(s) is unclear.
| 29,492
|
Psychotropic drugs, summer heat and humidity, and hyperpyrexia: a danger restated.
|
The authors note an apparent unawareness of, as well as a paucity of recent literature pertaining to, hyperpyrexia as a complication of psychotropic drug treatment. They report a case of hyperpyrexia in a patient receiving psychotropic agents during a summer heat wave; massive muscle destruction (rhabdomyolysis) with myoglobinuria and acute renal failure make this case of particular interest. Causative mechanisms, preventive measures, and the benefits of prompt recognition and treatment of this condition are discussed.
| 29,501
|
Hydrogen peroxide and superoxide radical formation in anaerobic broth media exposed to atmospheric oxygen.
|
Fourteen different broth media were autoclaved under anaerobic conditions and then exposed to atmospheric oxygen. The hydrogen peroxide and superoxide radical formation as well as the bactericidal effect of the media were studied. The rate of killing of Peptostreptococcus anaerobius VPI 4330-1 was high in media that rapidly autoxidized and accumulated hydrogen peroxide. In actinomyces broth (BBL), 50% of the cells were killed within 2 min, and in Brewer thioglycolate medium (Difco), 50% were killed within 11 min, whereas more than 50% of the cells survived for more than 2 h in Clausen medium (Oxoid), fluid thioglycolate medium (BBL), and thioglycolate medium without dextrose or indicator (Difco). Only media that contained phosphate and glucose had a tendency to accumulate hydrogen peroxide. A solution of phosphate and glucose autoxidized when it had been heated to 120 degrees C for at least 5 min and when the pH of the solution was higher than 6.5. Transitional metal ions catalyzed the autoxidation, but they were not necessary for the reaction to occur. Of the other substances heated in phosphate buffer, only alpha-hydroxycarbonyl compounds autoxidized with accumulation of hydrogen peroxide. Superoxide dismutase decreased the autoxidation rate of most of the broth media. This indicated that superoxide radicals were generated in these media.
| 29,560
|
Establishment of a heat inactivation curve for Clostridium botulinum 62A toxin in beef broth.
|
A procedure is described for establishing a heat inactivation curve for the toxin of Clostridium botulinum 62A in beef broth. The effect of toxin titer, pH, and the type of acid employed for pH adjustment on the heat stability of the toxin is described.
| 29,566
|
Utilization of D-amino acids by dadR mutants of Salmonella typhimurium.
|
Utilization of D-amino acids being substrates of D-amino acid dehydrogenase of Salmonella typhimurium was examined. The experiments were done with wild type strains and the mutants dadA missing the enzyme activity and dadR in which its synthesis is released from catabolite repression. Growth on D-tryptophan, D-histidine and D-methionine used as precursors of the L-amino acids was faster when the respective auxotrophs carried dadR mutations. The dadR mutants grew faster when D-or L-alanine was present as a sole source of nitrogen. Experiments with D-amino acid dehydrogenase in vitro provided evidence that D-tryptophan is its substrate with a very low affinity to the dehydrogenase.
| 29,590
|
Critical ionization states in the reaction catalyzed by triosephosphate isomerase.
|
To allow the detailed interpretation of the pH dependences of the steady-state parameters for the reaction catalyzed by triosephosphate isomerase, three kinds of experiments have been performed. First, the value of kcat/Km for enzyme-catalyzed isomerization of the phosphonate analogue of D-glyceraldehyde 3-phosphate (2-hydroxy-4-phosphonobutyraldehyde) has been shown to titrate with an apparent pKa of 7.5, which is close to the phosphonate's second ionization constant. Secondly, the sulfate ester analogue of dihydroxyacetone phosphate (dihydroxyacetone sulfate), which exists only as a monoanion over the pH range of interest, has been shown not to bind detectably to the enzyme. Thirdly, an isotopic discrimination experiment at pH 5.2 has been compared with a similar investigation at pH 7.6. The results together demonstrate that both enzyme and substrate ionizations control the reaction rate in the pH range 5 to 8.
| 29,659
|
Refolding transition of alpha-chymotrypsin: pH and salt dependence.
|
It is well known that alpha-chymotrypsin can exist in two major conformational states, only one of which is active. We have examined the pH (pH 2.0--11.0) and salt (ionic strength 0.01--1.0) dependence of the transition between the active and inactive forms in detail. At low pH (pH 2.0--6.0) the equilibrium is very dependent on salt concentration, with high salt concentrations effectively stabilizing the active conformation. This apparent stabilization is an artifact due to the salt-dependent dimerization of alpha-chymotrypsin, and our data show that only active species form dimers and higher aggregates. At neutral pH (6.0--8.0) dimerization is absent, yet an ionic strength dependence remains. The effects show no lyotropic order and appear to be due to preferential salt binding to the active conformation at one or possibly a few sites. Above pH 6 (pH 6.0--11.0), the pH dependence can be described by a two-ionization mechanism at all ionic strengths. We report values for all seven equilibrium constants in the proposed mechanism at four ionic strengths (mu = 0.01, 0.05, 0.2, and 1.0). The transition is the first "refolding" transition to be studied at high precision, but, even so, certain decisions about the mechanism must await higher experimental precision not available with present methods.
| 29,661
|
Estradiol receptor analysis in human breast cancer tissue by isoelectric focusing in polyacrylamide gel.
|
Isoelectric focusing in polyacrylamide gel combined with limited proteolysis is a simple and specific method for quantitation of estradiol receptors in breast cancer tissue. At least eight different samples can be analyzed simultaneously on one gel, and the whole procedure, including sample preparation, takes less than 7 hr. In comparison with sucrose gradient centrifugation, isoelectric focusing is more sensitive, possibly due to the short time (1.5 to 2 hr) needed for the analysis. Furthermore, only one incubation with tritium-labeled estradiol is needed for an analysis, which means that a smaller amount of tumor tissue is needed than for most other methods. This fact allows analysis of the estrogen receptor content in tumor material obtained from fine-needle biopsy.
| 29,706
|
[Effects of levophacetoperane, pemoline, fenozolone, and centrophenoxine on catecholamines and serotonin uptake in various parts of the rat brain].
|
These drugs, except centrophenoxine, inhibit in vitro in a competitive manner, norepinephrin uptake in Rat hypothalamus and cortex, and dopamine uptake in corpus striatum and cortex, at higher concentrations than d.l. amphetamine; this alone inhibits serotonin uptake in hypothalamus.
| 29,714
|
Kinetics of the reactions of unconjugated and conjugated bilirubins with p-diazobenzenesulfonic acid.
|
We report the kinetics of the reactions of unconjugated bilirubin and conjugated bilirubin with p-diazobenzene sulfonic acid in aqueous media. Our studies confirm that each reaction proceeds in two steps and that the second step is catalyzed by sulfanilic acid. In the presence of an excess of p-diazobenzenesulfonic acid and in the absence of sulfanilic acid, the reaction for either unconjugated or conjugated bilirubin proceeds in two successive first-order steps, the second step being much the slower. This study emphasizes the first step in the reaction for each species and includes data on the effects of p-diazobenzenesulfonic acid, albumin, benzoate, and caffeine concentrations, pH in the range from 4 to 12, and temperature. Mechanisms proposed for reactions with and without caffeine are used to develop rate equations, and the kinetic data are used to evaluate rate constants, acid dissociation constants for the different bilirubin species, and formation constants for bilirubin-caffeine complex species that are proposed.
| 29,720
|
Lactosyl ceramidosis: deficient activity of neutral beta-galactosidase in liver and cultivated fibroblasts?
|
Neutral beta-galactosidase was partially purified from liver of normal controls, a patient with Niemann-Pick disease type A and the previously described patient with lactosyl ceramidosis using Concanavalin A-Sepharose adsorption and Sephadex G-100 gel filtration. The partially purified fractions were essentially free of galactosyl ceramide beta-galactosidase and GM1 beta-galactosidase activities. The normal and Niemann-Pick fractions were found to hydrolyze lactosyl ceramide, in the presence of sodium taurodeoxycholate, at a pH optimum of 5.6 as well as aryl beta-galactosides and aryl beta-glucosides at pH 6.2. The corresponding fraction from the lactosyl ceramidosis liver contained only 1--4% of the normal activity towards artificial substrates and lactosyl ceramide. Cross-reacting material identical to the normal was demonstrated in this fraction with antiserum raised against purified neutral beta-galactosidase, but no activity was observed in the precipitin line when stained with naphthol AS-LC-beta-galactoside or naphthol AS-LC-beta-glucoside. A similar deficiency of neutral beta-galactosidase activity was demonstrated in cultivated fibroblasts of the patient with lactosyl ceramidosis. Following adsorption on Concanavalin A-Sepharose and anti-GM1 beta-galactosidase antibody-Sepharose conjugates and chromatography on DEAE cellulose, fibroblast lysates from the patient exhibited 3% of normal activity towards 4-methyl-umbelliferyl beta-glucoside at pH 6.2 and 12% of normal activity towards lactosyl ceramide at pH 5.6. These data suggest that neutral beta-galactosidase may have an in vivo role in the cleavage of lactosyl ceramide and that a deficiency of this activity may be related to the lactosyl ceramide accumulation observed in the patient with lactosyl ceramidosis.
| 29,729
|
The influence of dialysis fluid composition on the blood pressure response during dialysis.
|
To elucidate the relative role of osmolar (sodium) and acetate shifts during dialysis, 6 patients with problems of overhydration underwent rapid ultrafiltration for 1 hr (mean weight reduction 2.0 kg), using the 1 m2 RP 6 dialyzer. Ultrafiltration was carried out at the beginning of each of 5 dialysis treatments at weekly intervals. Ultrafiltration was undertaken without dialysis (controls) and with simultaneous dialysis using acetate (40 mmoles/1) or bicarbonate (25 mmoles/1) in the dialysis fluid with dialyzate sodium concentration of 133 and 145 mmoles/1. The systolic blood pressure and mean arterial pressure which were stable with ultrafiltration only fell slightly when a high dialyzate sodium concentration was used and much further when the dialyzate sodium concentration was kept low. These changes were apparently related to the changes in plasma osmolality. Acetate had no effect on blood pressure at the higher sodium concentration, but a slight (insignificant) additive effect when used in the low-sodium dialyzate. Shifts in osmolality (sodium concentration) seem to be more important than the effect of acetate in inducing dialysis-associated hypotension.
| 29,737
|
(-)-2-Hydroxy-n-cyclopropylmethylmorphinan: radioimmunoassay and phamacokinetic profile.
|
The pharmacokinetic profile of (-)-2-hydroxy-N-cyclopropylmethylmorphinan (HCMM), a narcotic antagonist and analgesic, has been evaluated in man following administration of 25 to 50 mg of the drug orally and 10 to 15 mg intramuscularly. A specific radioimmunoassay procedure was developed for the determination of HCMM in plasma and urine. The drug had a mean "apparent" elimination half-life in plasma of about 11 hr following both routes of administration. A mean of 47% of the oral dose was excreted in the urine as unconjugated and conjugated HCMM and only 5% of the dose was excreted as intact HCMM. In one subject studied, the plasma levels of conjugated HCMM were as much as 5-fold higher than the levels of unconjugated drug. Although there was considerable intersubject variability following both routes of administration, the overall pharmacokinetic parameters suggest that oral and intramuscular doses are bioequivalent.
| 29,740
|
[Scanning electromicroscopic studies of the surface of teeth. I. After manual treatment with tooth cleansers. II. Tooth cleaning with power-driven instruments].
|
Scanning electron microscopic examination of tooth surfaces after using manually operated instruments to remove calculus showed distinct lesions on the hard substances of the tooth. The extent of damage depends considerably on the area of the tooth treated (the border between the enamel and the cementum is particularly endangered), the amount of force used, and the length of time required for treatment. Examination of tooth surfaces following application of various types of power-driven scaling instruments revealed that lesions of the hard substances on the tooth are possible. The extent of the damage depends on several different factors, particularly the pressure applied and the area of the tooth treated. The border between the enamel and the cementum is particulary endangered.
| 29,748
|
Studies on renal dopamine receptors with a new agonist.
|
SK & F 38393 (2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine) is a new dopamine receptor agonist which selectively increased renal blood flow when administered i.v. to dogs at cumulative doses of 3.3-1333 microgram/kg. Consistent changes in arterial blood pressure heart rate and cardiac output were not observed. The renal response, which was mediated locally in the kidney, was not antagonized by adequate blocking doses of atropine, propranolol, metiamide and/or mepyramine nor by reserpinization or treatment with indomethacin. It was inhibited, however, by the selective peripheral dopamine receptor antagonist, bulbocapnine. Perhaps as a result of its action on renal blood flow, SK & F 38393 produced a diuresis in normally hydrated rats which was characterized by an increased excretion of sodium, potassium and chloride and a increased urinary pH. Compounds of this type may be useful in better defining dopaminergic receptors and in the treatment of disease states where renal ischemia is present.
| 29,762
|
Effect of adrenaline and adrenergic active drugs on growth hormone secretion in immature cockerels.
|
In immature cockerels adrenaline administration lowered the levels of plasma growth hormone. Both alpha and beta adrenergic receptor agonists also depressed the circulating growth hormone levels. In the presence of beta blockade, the suppressive effect of adrenaline on growth hormone secretion was not observed.
| 29,771
|
Birth interval study in a culturally stable urban population.
|
Five hundred women were interviewed within 2 days of delivery to examine indigenous birth spacing among the urban and rural population of Ife township. The crude birth interval was between 30 and 40 months due mainly to cultural attitudes towards lactation and sexual abstinence. The women studied possessed considerable knowledge of Western contraceptive methods, but they rejected them. The possible cause of this rejection is examined and solutions to the problem are suggested.
| 29,795
|
Long-term effect of pH on B-cell function in isolated islets of Langerhans in tissue culture.
|
Collagenase isolated mouse pancreatic islets were maintained in tissue culture for up to 5 months in a culture medium buffered with Hepes and the pH varying between 6.8 and 7.6. The amount of insulin released into the medium and the insulin response to glucose and glucose plus theophylline were measured during the culture period. It was found that islets cultured at pH 7.2 maintained the ability to release insulin into the medium for at least 5 months, which was longer than islets cultured at the other pH values. During the first weeks, the islets cultured at pH 7.6 had a higher response to both glucose and glucose plus theophylline than islets cultured at the other pH values, but later they lost their insulin releasing ability.
| 29,815
|
Reproduction and breeding of goats.
|
Reproduction and genetics of the goat are reviewed with a view of increasing their contribution to mankind. The goat contributes most in tropical regions (within 30 degrees of the equator). The most important product from the goat is milk with meat a close second. Other products are minor. Reproductive rate is a problem only with the Angora goat, but increased reproduction with any type of goat would contribute to improved efficiency. Also, a knowledge of the reproductive phenomenon is necessary for effective management. Genetic studies of goats are limited, but this should not limit improvement programs. Excellent genotypes for producing milk and fiber are available, but adaptation to tropical conditions is needed. Even within temperature regions, there is little evidence of progress in breeding for milk production. Little has been done on the development of the goat as a meat animal. Also, research on crossbreeding for milk or meat production is limited.
| 29,915
|
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