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An extrarenal source of "renin-like" activity in anephric man.
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To examine extrarenal sources of "renin-like" activity plasma was obtained from 19 anephric males. Plasma renin activity (PRA), concentration (PRC) (obtained after addition of exogenous renin substrate) and total renin concentration (TRC) (obtained after acid-activation of plasma and subsequent incubation with exogenous renin substrate) demonstrated values for several anephric patients comparable or above those seen in plasma from 10 normal subjects. Incubation of untreated plasma (PRA and PRC) and acid-dialyzed plasma (TRC) for angiotensin I generation was performed at pH 7.5, at 37 degrees C with EDTA, dimercaprol, and 8-OH-quinoline as angiotensinase and converting enzyme inhibitors. The pH optimum for acid-activation of TRC in anephric plasma was the same as that in normal plasma (pH 3.3). Molecular weight determinations following Sephadex gel chromatography demonstrated that the renin-like enzyme in normal plasma had a molecular weight of about 42,000 before and after acid-activation, while that in anephric plasma had a molecular weight of approximately 61,000. A saliva sample from one anephric subject with the highest levels of PRA, PRC, and TRC in plasma also demonstrated measurable amounts of PRA, PRC, and TRC. The molecular weight of this salivary "renin-like" activity also was 61,000. These observations suggest a possible extrarenal source of "renin-like" activity in anephric man. The physiological significance of these studies remains to be clarified.
| 15,733
|
An inactive renin in human plasma.
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Normal human plasma contains an active form of renin that is activated by acidification to pH 3.0 and comprises 56% of the total renin. In our study, inactive renin was also present in plasma from five anephric persons, and the proportion of active to inactive renin in these subjects was similar to normal. Plasma from normal pregnant women contained increased concentrations of inactive renin and the proportion of inactive renin was raised to around 66%. Plasma from persons with renal hypertension contained varying amounts of inactive renin but the mean percentage (35%) was lower than normal. An infusion of saralasin sufficient to lower the blood pressure in five subjects with renal hypertension resulted in a rise in active renin concentration but no change in the concentration of inactive renin. Plasma angiotensin II correlated with active renin but not with inactive renin, suggesting that the inactive renin does not produce angiotensin II in vivo.
| 15,736
|
Lung pH and pulmonary absorption of nonvolatile drugs in the rat.
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The effect of pH on pulmonary absorption of nonvolatile drugs was investigated in the rat. Krebs-Ringer phosphate solutions (pH 6.2 and 7.4), Krebs-Ringer pyrophosphate solution (pH 8.4), or an unbuffered salt solution containing a drug were administered through tight-fitting tracheal cannulas to anesthetized animals. After 3 min, the lungs were removed and assayed for the amount of drug that remained. Weak acids and a weak base were absorbed most rapidly at pH values at which the drugs were least ionized. For example, with the base procainamide, 36% of the dose was absorbed at pH 6.2 and 76% at pH 8.4. With the acid sulfisoxazole, 71% was absorbed at pH 6.2 and 55% at pH 8.4. Similarly, with p-aminosalicylic acid, 77% was absorbed at pH 6.2 and 40% at pH 8.4. In contrast to these results, compounds such as urea and amitrole, which remain completely nonionized over the pH range studied, showed no change in absorption rate when the pH was varied. The two weak acids and the weak base were absorbed from an unbuffered solution as though the pH at the site of drug absorption was between 6.2 and 7.4. The absorption rate for each weak electrolyte from unbuffered solution, when compared graphically with the respective absorption rates from buffered solutions, indicated that the pH at the site of drug absorption is about 6.6.
| 15,810
|
Metabolism of haloforms to carbon monoxide. I. In vitro studies.
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Trihalomethanes (haloforms) were metabolized to carbon monoxide by a rat liver microsomal fraction requiring both NADPH and molecular oxygen for maximal activity. GSH alone did not serve as a cofactor; however, GSH in the presence of NADPH and oxygen produced an 8-fold increase in the metabolism of bromoform to CO. Similar results were obtained with other sulfhydryl compounds. The biotransformation of bromoform to CO was characterized with respect to time course, microsomal protein concentration, pH and temperature. The metabolism of haloforms to CO followed the halide order; thus, iodoform yielded the greatest amount of CO, whereas chloroform yielded the smallest amount. A KM of 6.78 +/- 2.71 mM was established for bromoform and the Vmax was 1.09 +/- 0.19 nmol of CO per mg of microsomal protein per min. The energy of activation for this reaction was 6.5 +/- 0.18 kcal/mol. Cytochrome P-450 was found to bind bromoform to produce a type I binding spectrum. Treatment of rats with phenobarbital or 3-methylcholanthrene increased the rate of conversion of bromoform to CO. Cobaltous chloride treatment of rats or storage of microsomal preparations at 4 degrees C reduced the rate of formation of CO from bromoform. SKF 525-A inhibited the conversion of bromoform to CO. These results suggest that haloforms are metabolized to CO via a cytochrome P-450-dependent mixed-function oxidase system.
| 15,814
|
Neuropsychological deficit in polydrug users. A preliminary report of the findings of the collaborative neuropsychological study of polydrug users.
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The Collaborative Neuropsychological Study of Polydrug Users performed extensive neuropsychological assessments on 15 polydrug users 3 weeks after their enrollment in each of eight polydrug demonstration programs. Fifty-six (37%) of these subjects exhibited neuropsychological deficit. This deficit was partially related to increasing age, poor education and premorbid medical risk factors. The deficit was also associated with extensive and intensive use of two classes of drugs: sedatives (sleeping pills and minor tranquilizers) and opiates (heroin and other narcotic drugs). Seventeen (26%) of a comparison group of 66 psychiatric in-patients and day patients also demonstrated age- and education-correlated neuropsychological deficit. For these patients impairment was also related to lifetime experience with antipsychotic drugs and (perhaps) with clinical diagnosis of schizophrenia. Although both polydrug users and psychiatric patients revealed serious psychopathology as measured by the MMPI, the pattern of the neuropsychological test findings suggested that psychopathology alone did not account for impairment. The 3 month follow-up which is in progress should delineate further the time course and enduring features of neuropsychological deficit among polydrug users, and may establish more clearly the relationship of sedative and opiate use to such impairment. Changes in psychopathological status of both polydrug users and psychiatric patients should also help to clarify the influence of this variable on neuropsychological findings.
| 15,818
|
Disposition of carbamazepine and its 10,11-epoxide metabolite in the isolated perfused rat liver.
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The disposition of carbamazepine and its metabolite, the 10,11-epoxide, was investigated in isolated perfused livers from control and phenobarbital-pretreated rats. The mean hepatic clearance of carbamazepine was 0.28 ml per min per g of liver corresponding to a mean extraction ratio of 0.16 and a mean intrinsic clearance of 0.33 ml per min g of liver. In phenobarbital-pretreated rats, there was an approximately 40% increase in the hepatic clearance due to a concomitant increase in the mean extraction ratio from 0.16 to 0.26. The carbamazepine-10,11-epoxide generated in the liver approached and attained its peak concentration more rapidly in pretreated than in control rat livers. In the latter group there was virtually no disappearance of the epoxide from the perfusate, whereas in the pretreated rat livers the perfusate concentrations declined after 90 min. The extremely low clearance of the epoxide generated by metabolism in control rat liver was confirmed by administration of the epoxide per se to the perfusion system. The mean extraction ratio of the epoxide in this situation was only 0.016 and it was unaffected by prior treatment of the rats with phenobarbital. However, the epoxids exhibited dose-dependent kinetics with a 3-fold increase in the extraction ratio when the administered dose was reduced from 500 to 166 microng. The observed induction of the hepatic clearance of carbamazepine is supportive of the involvement of this mechanism in the interaction of this drug with various other anticonvulsants in both children and adults.
| 15,811
|
Purification of bovine thyroid peroxidase.
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Trypsin-solubilized peroxidase activity from beef subcellular particles was resolved by DEAE-cellulose chromatography into 5 fractions, which contained enzymatically active components that ranged in molecular size from 73,000 to 340,000 daltons. The most active fraction (mol wt, 92,000 by gel filtration) was further purified (59,000-fold overall) by chromatography on hydroxylapatite. This highly purified peroxidase preparation had an absorbance purity ratio (A410:A280) of 0.55 and oxidized iodide (I3-formation) and guaiacol at rates of 300 and 460 micronmol/min/mg, respectively, which were about 3 and 1 1/2 times, respectively, greater than any previously described preparations. The enzyme was contaminated with an inactive protein of equal size. The highly purified peroxidase preparation lost its activity within a few days even when stored at -15 C with iodide. Two of the other DEAE-cellulose fractions contained peroxidase components with estimated sizes (gel filtration) of 73,000, 96,000, and 98,000, which were further purified purified (1,600 and 15,600 fold) on hydroxylapatite. They were 1/4 to 1/40 as active as the highly purified preparation and also became increasingly labile on purification. The remaining two DEAE-cellulose fractions were heterogeneous mixtures of stable peroxidase components whose average molecular sizes (gel filtration) were 220,000, 300,000, and 340,000 daltons, and which were not amenable to further purification on hydroxylapatite. The ratio of guaiacol to iodide activity decreased from 3.0 in the particles to about 1.5 in the highly purified preparations. The turnover numbers of the purest peroxidase component (mol wt. 92,000) for iodide and guaiacol were very similar to those of highly purifed, commericial lacto- and horseradish peroxidases. The pH maxima for iodide oxidation were 7.4, 6.0, and 4.5 for thyroid, lacto-, and horseradish peroxidases, respectively, whereas guaiacol oxidation peaked at pH 7.0-7.8 for all three enzymes. On the basis of these results and the dissimilar molecular sizes reported for trypsin-solubilized thyroid peroxidase by several other investigators, it was concluded that the molecular size is primarily determined by the conditions of proteolysis.
| 15,822
|
The interaction of phospholipid membranes and detergents with glutamate dehydrogenase.
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1. Both the anionic detergent sodium dodecylsulphate and the cationic detergent cetyltrimethylammonium bromide quenched the protein fluorescence of glutamate dehydrogenase. The anionic compound was more effective and brought about 50% quenching at a detergent concentration of 0.4 mM. The zwitterionic amphiphile, lysolecithin, did not quench the protein fluorescence and neither did the short-chain detergent n-hexylsulphonate, which under the range of concentrations examined (less than 1 mM) does not form micelles. 2. The zwitterionic phospholipid, phosphatidylcholine, did not quench the protein fluorescence but the anionic phospholipids, phosphatidylserine and cardiolipin, induced a reversible quenching of the enzyme fluorescence. These observations confirm the specificity of the phospholipid-enzyme interactions as deduced from the kinetic studies of the preceding paper. The degree of quenching brought about by the phospholipids decreased with increasing ionic strength and increasing pH and could be substantially reduced by basic proteins. An electrostatic contribution to the interaction is inferred from these results. 3. The binding of the anionic phospholipids to the enzyme is manifested in a further enhancement of the fluorescence of a 1-anilinonaphthalene-8-sulphonate-enzyme complex. The presence of substrates and allosteric effectors affect the interaction of the lipids with the enzyme as indicated by the magnitude of this increase in fluorescence. The enhancement of fluorescence of NADH when bound to the enzyme was not affected by the binding of the lipids. 4. The complex formed between the enzyme and phosphatidylserine/phosphatidylcholine can be solubilized in isooctane. The photolability of the aqueous protein when subjected to irradiation at 280 nm is suppressed in the isooctane-soluble complex. 5. Phosphatidylserine brings about a rapid (t 1/2 is about 150 ms at a lipid concentration of 0.75 mM) dissociation of the linear aggregates formed between the enzyme oligomers. 6. A model of the enzyme-lipid-membrane complex, consistent with these results, is proposed. It is suggested that the enzyme is an allotopic protein and that the dissociation of the enzyme in vitro may involve binding sites on the protein which are designed for interaction with the cardiolipin of the inner mitochondrial membrane, when the enzyme is in the mitochondrial matrix.
| 15,832
|
The purification and properties of NADP-dependent isocitrate dehydrogenase from ox-heart mitochondria.
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The purification of NADP-linked isocitrate dehydrogenase from ox heart mitochondria is described. The molecular weight from gel filtration, sedimentation equilibrium and gel electrophoresis is 90000+/-4000, and there are two subunits in the molecule each of which binds NADPH with enhancement of the coenzyme fluorescence. The amino-acid composition is reported, and the absorption coefficient, A1/280%, estimated from dry weight measurements is 11.8 cm-1.
| 15,840
|
[Effect of narcotics on impulse conduction in the afferent pathways of visceral nerves].
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In tests set up on cats immobilized with pyraxolone and anatruxonium the effect of non-inhalation narcotics on the evoked potentials of the cortex and subcortical structures with visceral and also somatic, acoustic and photo-stimulation was studied. With stimuli of different modality sodium ethaminal was found to inhibit evoked potentials of the cerebral hemispheres, diencephalon and midbrain cortex. Hexabarbital sodium suppressed biopotentials in specific, associative and non- specific brain structures in the event of visceral and somatic stimulation. Viadril enhanced the amplitude of potentials in all types of stimulation Urethan inhibited potentials in specific pathways of visceral and somatic nerves as well as in associative and non-specific brain structures following visceral, somatic and acoustic stimulation, with the amplitude of potentials to photostimulation then increasing.
| 15,858
|
Laparoscopic sterilization in the puerperium: a review of international experience.
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The feasibility of using laparoscopic techinques for pueperal sterilization has been demonstrated on three continents. While the operation is not suggested to replace all other methods of pueperal sterilization, it is advantageous in selected situations.
| 15,906
|
Prophylactic antibiotic in elective gynaecological and obstetrical major surgery.
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A prospective controlled study of 580 patients who underwent non-radical major gynaecological or obstetrical surgery examined the use of prophylactic antibiotics. The test group of patients (290) showed a significantly lower (P=0.01) incidence of the total complications and the non-infective complication rate as against those among controls (290). The duration of hospitalisation was significantly reduced for both vaginal and abdominal surgery in the test group of patients as against those in the controls. There was no evidence of increased incidence of bacterial resistance or superinfection. The authors recommend the use of prophylactic antibiotic on a short term basis (for a total duration of 4 days), commencing preoperatively to achieve a significant reduction in the infective postoperative morbidity and a shorter stay by the patients.
| 15,908
|
[Mycoses. Pathogenicity and diagnosis of dermatophytes, yeasts and molds].
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Human beings today living in high industrialized areas suffer more frequently from fungal diseases than before. This is due to the management in animal production, but also to the use of cosmetics and contraceptives, smoking cigarettes, wearing clothes of synthetic polymers and application of new drugs, like antibiotics, cytostatics, immunosuppressives and others, which favours the growth of certain fungi in and on the skin and inside the human body. Some mechanisms are known from the macroorganism which are able to protect man from fungal invasion. Effective in this way are the normal flora of the skin, gut and the mucous membranes, the enzymes digestive and the natural low pH of the healthy skin. The fungal growths are favoured when primary diseases of not-infectious genesis due to disorders in metabolism or endocrinium, vitamin deficiency, malabsorption, maldigestion, false and malnutrition, and diseases of the haemopoetic system exist. But also viral and bacterial infections stimulate the development of secondary fungal diseases. The pathogens belong to three groups, dermatophytes, yeasts and molds, which can be differentiated according to their behaviour in culture and in tissue.
| 15,935
|
The differential diagnosis of crescentic glomerulonephritis. The pathology of specific lesions with prognostic implications.
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Combined findings from light and electron microscopy with immunofluorescence studies make a definitive diagnosis possible in most cases of crescentic glomerulonephritis. The patient's prognosis and pattern of response to therapy are matters of immediate concern in the light of recent developments in nephrology. The frequency of crescentic lesions varies depending on the specific types of disease, but the idiopathic lesion is seldom seen.
| 15,939
|
Early events in the induction of glutamine synthetase activity by hydrocortisone in embryonic chick neural retina.
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Primary cultures of 10-day embryonic chick neural retinas were used to investigate early aspects of the mechanism of hydrocortisone action on glutamine synthetase activity. As little as 2 hr of hydrocortisone exposure served to initiate significant increases in the glutamine synthetase activity levels assayed after 24 hr culture. Time course studies indicated that the increase in glutamine synthetase activity observed after 24 hr in culture resulted from a two-phase rise in activity and that cycloheximide was effective in suppressing the second-phase rise. Additional inhibition studies demonstrated that the second-phase increase in enzyme activity required continuous protein synthesis during the initial 6 hr. The evidence suggests a mechanism of hydrocortisone action involving the production of a protein which is important for the induction of glutamine synthetase activity by hydrocortisone.
| 15,942
|
The activation of intravascular coagulation by bromocarbamide.
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In the rabbit the application of a non-lethal, sleep-inducing dose of bromisovalerianyl carbamide (0.5 g/kg body weight) causes an activation of the coagulation system. This activation is manifested by shortened thrombin and partial thromboplastin times and a decrease of fibrinogen concentration and Factor V activity. In contrast, pentobarbital sodium at a dose (62.5 mg/kg) which causes the same changes in arterial partial oxygen pressure and arterial pH does not influence the coagulation system. The bromocarbamide-induced changes in the coagulation system are not to be considered as a result of hypoxia and acidosis but seem to be caused by early endothelial and tissue lesions which result in the release of procoagulatory substances. In healthy test persons a single dose of 1.5 g bromisovalerianyl carbamide has no demonstrable influence on the system of hemostasis.
| 15,952
|
Alkaline phosphatase of Blastocladiella emersonii: partial purification and characterization.
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Alkaline phosphomonoesterase (EC 3.1.3.1) activity from Blastocladiella emersonii, while displaying typically broad substrate specificity for phosphorylated organic compounds, exhibited nearly complete substrate preference for N-acetylglucosamine-6-phosphate over N-acetylglucosamine-1-phosphate. Enzyme in zoospore extracts was purified 43-fold by differential centrifugation followed by gel filtration (Sephadex G-200) and then by ion-exchange chromatography (diethylaminoethyl-cellulose). The partially purified enzyme displayed an apparent molecular weight (Sephadex G-200) of approximately 170,000. The activity of partially purified enzyme exhibited a pH optimum of pH 8.5, did not require a metal divalent cation, but was inhibitable by ethylenediaminetetraacetic acid. During the life cycle of the organism, the specific activity of the phosphatase decreased slightly during germination and early exponential growth but then increased about 4.5-fold during sporulation. B. emersonii alkaline phosphatase does not appear to be a repressible enzyme.
| 15,978
|
Localization of enzymes in Ureaplasma urealyticum (T-strain mycoplasma).
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Ureaplasma urealyticum cells were lysed by osmotic shock or by digitonin. The membrane fraction contained four to ten times as much protein as the cytoplasmic fraction. These values are in large excess of those reported for classical mycoplasmas, suggesting that the Ureaplasma membrane fraction was heavily contaminated with proteins derived from the growth medium. The U. urealyticum urease activity was localized in the cytoplasmic fraction, whereas the adenosine triphosphatase activity was localized in the membrane fraction. Significant urease activity could be detected also in nonviable cells. Urea, at concentrations above 0.25 M, was mycoplasmastatic to Acholeplasma laidlawii, Mycoplasma hominis, and U. urealyticum, so that the Ureaplasma urease did not afford preferential protection against urea toxicity. The intracellular localization of the urease would be expected to release ammonia from urea in the cytoplasm. The ammonia will take up protons to become ammonium ions. It can be hypothesized that the intracellular NH4+ plays a role in proton elimination or acid-base balance, which might be coupled to an energy producing ion gradient and/or transport mechanisms.
| 15,980
|
Regulation of galactose oxidase synthesis and secretion in Dactylium dendroides: effects of pH and culture density.
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The effects of pH and growth density on the amount of an extracellular enzyme, galactose oxidase, synthesized by the fungus Dactylium dendroides were studied. Growth at a pH below 6.7 caused a decrease in the ability of the organism to release galactose oxidase. The enzyme retained by these fungal cells was liberated whenever the pH was raised to 7.0. Cycloheximide addition failed to inhibit the appearance of this protein; [3H]leucine added prior to pH adjustment was not incorporated into the released protein, These observations indicate the released protein is not newly synthesized protein. The retained enzyme would be secreted slowly over a 2-day period if the pH was not increased. In addition to regulating protein retention, pH was also shown to be associated with vacuolization, cell volume, culture density, and inhibition of protein synthesis. Cultures maintained at low pH were characterized by a dense growth consisting of highly vacuolated, buoyant, fungal hyphae. Increasing the pH from 6 to 7 caused a decrease in vacuole size. Cells grown at neutral pH maintained a lower density of growth and, based on activity measurements, synthesized 33% more galactose oxidase. Furthermore, cultures grown at pH 6.0 and maintained at a lower cell density produced galactose oxidase at a level similar to that of cells grown at neutral pH. Thus, the elevated density of the cell culture was inhibitory to galactose oxidase synthesis. The observed effects on protein synthesis and release were rather specific for galactose oxidase, since other extracellular proteins appeared in the earliest stages of growth.
| 15,985
|
O-alkylhomoserine synthesis catalyzed by O-acetylhomoserine sulfhydrylase in microorganisms.
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An enzyme that can synthesize O-alkylhomoserine from alcohols and O-acetylhomoserine was purified from Corynebacterium acetophilum. The enzyme was found to be identical to O-acetylhomoserine sulfhydrylase; a preparation that appeared homogeneous on polyacrylamide gel electrophoresis showed both O-alkylhomoserine-synthesizing and O-acetylhomoserine sulfhydrylase activities. Its molecular weight was determined to be about 220,000, and it consisted of two subunits. Its pH and temperature optima for the two reactions were the same. Besides catalyzing the formation of homocysteine from O-acetylhomoserine and sulfide, it also catalyzed the syntheses of O-alkylhomoserines corresponding to the alcohols added form O-acetylhomoserine and ethyl alcohol, n-propylalcohol, n-butyl alcohol, methyl alcohol, and n-pentyl alcohol, its activities with these alcohols decreasing in that order. L-Homoserine, O-succinylhomoserine, and O-acetylserine reacted with sulfide. O-ethylhomoserine, O-acetylthreonine, O-succinylhomoserine, and O-acetylserine inhibited both enzyme activities. O-acetylhomoserine sulfhydrylase purified from Saccharomyces cerevisiae also showed O-alkylhomoserine-synthesizing activity. Thus, O-acetylhomoserine sulfhydrylase seems to catalyze O-alkylhomoserine synthesis in the presence of appropriate concentrations of alcohol and O-acetylhomoserine in microorganisms.
| 15,989
|
Enzymatic conversion of bilirubin monoglucuronide to diglucuronide by rat liver plasma membranes.
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Formation of bilirubin monoglucuronide from unconjugated bilirubin requires a microsomal enzyme, UDP-glucuronate glucuronyltransferase (EC 2.4.1.17). Conversion of bilirubin monoglucuronide to bilirubin diglucuronide, the major bilirubin conjugate in bile, was studied in subcellular fractions of rat liver. The highest specific activity for bilirubin diglucuronide formation occurred in a fraction highly enriched in plasma membranes. Studies of reaction stoichiometry and utilization of UDP-D-[14C]glucuronic acid revealed that conversion of bilirubin monoglucuronide to bilirubin diglucuronide is not catalyzed by UDP-glucuronyltransferase, and results from transglucuronidation of bilirubin monoglucuronide, with formation of bilirubin diglucuronide and unconjugated bilirubin. When unconjugated bilirubin was infused intravenously into rats at rates exceeding the maximal hepatic excretory capacity, bilirubin monoglucuronide accumulated in serum and bilirubin diglucuronide was found exclusively in bile as the predominant bilirubin metabolite. These results suggest that formation of bilirubin diglucuronide occurs at the surface membrane of the liver cell. Conversion of bilirubin monoglucuronide to bilirubin diglucuronide may play a role in the transport of bilirubin glucuronides from liver to bile.
| 15,996
|
Characterization of the m7G(5')pppN-pyrophosphatase activity from HeLa cells.
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The m7(G(5')pppN-pyrophosphatase activity previously detected in HeLa cells has been further characterized. Results from DEAE-cellulose column chromatography and polyacrylamide gel electrophoresis under nondenaturing conditions revealed only one enzyme activity in HeLa cell extracts which was capable of selectively hydrolyzing m7G(5')pppN to yield m7pG + ppN (where N = 2'-O-methylated or unmethylated ribonucleosides or oligonucleotides of up to 8 to 10 nucleosides in length). The majority (approximately 95%) of this activity was found in the cytoplasmic extract but appeared not to be associated with the lysosomal fraction. m7G(5')pppG was hydrolyzed by the partially purified enzyme in the absence of divalent cations at a pH optimum of 7.5 and a temperature optimum of 45 degrees, with a Michaelis constant (Km) of 1.7 micronM. Sedimentation analysis and gel filtration showed the molecular weight of the enzyme as approximately 81,000. Inhibition studies testing the effect of a number of prospective substrates on the rate of m7G(5')pppG hydrolysis have confirmed the importance of the methyl moiety at the N7 position of guanosine for enzyme-substrate interaction. Furthermore, the trimethylated guanosine-containing 5'-terminal structure derived from U-2 RNA was found not to serve as substrate, and 7-methylinosine, unlike 7-methylguanosine, was not an effective inhibitor of m7G(5')pppG hydrolysis. Thus, the 2-amino group of the 7-methylguanosine portion of m7G(5')pppN is also important for substrate interaction with this specific pyrophosphatase.
| 16,003
|
Epidermal nucleases. II. The multiplicity of ribonucleases in guinea-pig epidermis.
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Ribonuclease activity has been extracted from adult guinea-pig epidermis by sequential homogenization in dilute sodium acetate and sulfuric acid. The extracts were subjected to ammonium sulfate fractionation and to affinity and ion exchange chromatography. Three ribonucleases (I, II, III) were separated from the sodium acetate extract and 6(A, B1, B2, B3, C, D) were isolated from the sulfuric acid extract. The degree of purification varies from 65-fold to 8,700-fold and the apparent molecular weights of the active forms of 8 of the 9 ribonucleases range from 10,000 to 36,500. No phosphodiesterase activity is present in any of the 9 fractions, but there is alkaline phosphatase activity in one (I) and deoxyribonuclease activity in a second (B3). Two of the ribonucleases have acid pH optima (a1, B3), while the others are most active between PHs 6.8 and 7.8. The activity of 4 of the fractions is sensitive to added EDTA (III, A, B2, B3,), but no stimulatory metal ions were found. Low concentrations of the polyamine spermidine enhanced the activity of 3-fractions (III, C, D). Yeast ribonucleic acid is degraded exonucleolytically by 2 fractions (I, A) and endonucleolytically by the remaining 7. In experiments with homopolyribonucleotide substrates, poly U was generally the preferred substrate. Substantial hydrolysis of poly A occurred with 2 fractions (A, B3) and slight hydrolysis of poly G with 2 other fractions (B2, C).
| 16,063
|
Motor innervation of the smooth muscle of the rat seminal vesicle.
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Frequency-related isovolumetric contractions of the rat seminal vesicle elicited with transmural electrical stimulation were blocked by tetrodotoxin but unaffected by hexamethonium. The postganglionic motor innervation of the rat seminal vesicle is purely excitatory and contains both an adrenergic and a cholinergic component which are excited simultaneously during transmural stimulation. Contractions elicited by adrenergic nerve stimulation were mediated by norepinephrine acting via alpha adrenoceptors, i.e., 1) responses of untreated vesicles to transmural stimulation and to exogenous norepinephrine were antagonized by phentolamine and potentiated by cocaine, 2) pretreatment of animals with reserpine or 6-hydroxydopamine produced a marked depletion of tissue norepinephrine concentration and reduced the responses to transmural stimulation to a level which resembled that of untreated organs in the presence of phentolamine, 3) the residual responses of vesicles from pretreated rats were not modified by phentolamine or cocaine, and 4) responses to tyramine in untreated organs were antagonized by phentolamine but not by cocaine and were observed in organs from reserpine-pretreated rats only after repletion with exogenous norepinephrine. Responses elicited by cholinergic nerve stimulation were mediated by acetylcholine through muscarinic receptors, i.e., 1) responses of untreated vesicles to transmural stimulation and to exogenous acetylcholine were antagonized by atropine, 2) the residual responses to transmural stimulation of vesicles from animals pretreated with reserpine of 6-hydroxydopamine were nearly abolished by atropine and 3) physostigmine potentiated and prolonged the responses of organs from untreated and reserpine-pretreatd animals to transmural stimulation; these effects of physostigmine were abolished by atropine.
| 16,117
|
Urinary carbon dioxide tension in lithium carbonate-treated patients.
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Renal acidification was studied in 12 lithium carbonate-treated psychiatric patients. The urinary Pco2 response to oral sodium bicarbonate loading, a qualitative index of distal hydrogen ion secretion, was evaluated in all patients and the results were compared with those obtained in 10 control subjects. The average maximal urine to arterial blood Pco2 difference (U-A Pco2) in the psychiatric patients [26 +/- 3 (S.E.) mm Hg] was significantly lower (P less than .001) than that of control subjects (51 +/- 3 mm Hg) and only three patients had values greater than 31 mm Hg (2 S.D. below the mean control value). Eight of these patients were also evaluated with NH4CL acid loading. Seven of eight patients had a minimal urine pH less than 5.30 after NH4CL administration; only one of the seven had a normal U-APco2 after bicarbonate loading. Three patients were evaluated prior to treatment and after 2 weeks of lithium administration. Pretreatment U-APco2 values were normal. After therapy the values were lower in all three patients becoming definitely abnormal in two. The present investigation, in concert with previous animal studies, demonstrates that chronic lithium carbonate therapy in man may result in decreased U-A Pco2.
| 16,123
|
Possible explanations for the differences in secretory characteristics between conjugated and free bile acids.
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1. The hepatic extraction fraction and maximum excretory rate of conjugated cholate are greater than those of free cholate (studied after acute taurine depletion); the possibility that this difference might be due to greater bile-to-blood back-diffusion of un-ionized cholic acid (pKa 5-5) compared to that of taurocholic acid (pKa 2) has been investigated by varying the pH of bile by secretin or acetazolamide administration in the anaesthetized dog. 2. The mean biliary pH during free cholate excretion in the control state in twenty-three experiments was 7-5 (at which approximately 1% of cholate is un-ionized). Three to fourfold changes in the hydrogen ion activity of bile (which resulted in changes of the same magnitude in the percentage of un-ionized cholic acid) had no significant effect on the total (mainly free) cholate maximum excretory rate. It is concluded that back-diffusion of un-ionized cholic acid in the bile ducts is not an important determinant of the secretory performance of free cholate. 3. The bile flow rate associated with mainly free cholate excretion is much higher than that associated with taurocholate excretion at the same rate; the extra bile flow appears to arise largely by means that are independent of the osmotic effect of cholate excretion, as the osmotic coefficient (osmolality/total solute concentration) of bile containing mainly free free cholate (calculated directly) was only slightly greater than that of bile containing mainly taurocholate (obtained by extrapolation) at the same total cholate concentration. 4. The peak hepatic excretory rate of taurocholate following the instillation of the entire contents of the gall-bladder of a fasted dog into the distal ileum was only about one fifth of the maximum rate attainable; at the peak rate taurocholate is almost completely removed in the first passage of blood through the liver.
| 16,125
|
The effect of calcium injection on the intracellular sodium and pH of snail neurones.
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1. Ion-sensitive glass micro-electrodes were used to measure the intracellular pH (pHi) and the intracellular sodium ion concentration, [Na+]i, in identified Helix aspersa neurones. 2. The injection of small volumes of 0-1 McaCl2, which increased the membrane potential by 10-15 mV for 1-2 min, had little or no effect on [Na+]i. Increases of up to 1 mM in [Na+]i could be reversibly induced by larger injections. 3. Calcium injection caused an immediate decrease in pHi, which appeared to be directly proportional to the amount of calcium injected. Injections causing hyperpolarizations of 10-20 mV which recovered in 2-5 min caused pHi decreases of 0-04-0-15 units. After each of these injections both pHi and the membrane potential recovered exponentially but with different time constants. 4. The injection of calcium at a low rate could decrease pHi without affecting the membrane potential. 5. Neither membrane potential nor pHi were affected by the injection of small volumes of 0-1 M-MgCl2, Injection of CoCl2 produced a large transient decrease in pHi but no significant change in membrane potential. 6. Exposure of the cell to saline equilibrated with 2-5% CO2 greatly reduced the pHi decrease caused by calcium injection but had only small effects on the membrane potential response. 7. It is concluded that most of the injected calcium is exchanged for protons inside the cell.
| 16,126
|
Growth of a heterologous tumor cell line in neonatal rats with graft-versus-host disease.
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The ability of a hamster tumor cell line (T20) to grow and exhibit type H virus particles was significantly enhanced in neonatal DA rats with graft-versus-host disease (GVHD). Tumor growth peaked on days 4 and 7 in control littermates receiving adult syngeneic cells or no cells at birth, respectively, and then subsequently disappeared. However, tumor nodules in animals with GVHD became significantly larger than those in controls by day 7 and continued to grow until death. In addition, a marked plasma cell infiltration was noticed in such rapidly growing tumors from animals with GVHD only. In the light of previous studies, evidence is discussed for an environment within animals with GVHD conducive for tumor cell growth because of a depletion of T-cell areas within their tissues.
| 16,141
|
[Oto-palato-digital (Taybi) syndrome].
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A case of dysmorphogenetic syndrome, described by Taybi, is reported. The syndrome is characterized by hardness of hearing of conduction type, submucous cleft palate and anomalies involving the bony frame, especially the digits.
| 16,178
|
Cataract and gamma-glutamyl cycle in myotonic dystrophy.
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Gamma-Glutamyl transpeptidase (gamma-GT) may be responsible for the rapid catabolism and low levels of lenticular glutathione often associated with cataract formation. Elevated levels of serum gamma-GT in patients with myotonic dystrophy suggest that since the defect could be present in all tissues it might be responsible for the cataracts frequently observed in this genetic disease.
| 16,240
|
Pigment epithelial ensheathment and phagocytosis of extrafoveal cones in human retina.
|
The association between extrafoveal cone outer segments and pigment epithelial cells was studied by transmission electron microscopy in three human retinas; ages 5,45 and 60. The pigment epithelial apical surface from a fourth human retina, age 38,was viewed in the scanning electron microscope. Multiple villous-like apical processes protrude from the pigment epithelium into the space above each cone. Sometimes one or more of these processes is sheet-like in form and contains a wealth of intracellular organelles, including mitochondria. One or more of the villous-like procesess reaches the cone and expands to ensheath the upper one-third of the outer segment. Llike vertebrate rods, extrafoveal human cones shed their terminal disks in packets and these packets are phagocytosed by the ensheathing apical processes. The phagosomes then ascend in the processes toward the pigment epithelia soma. Digestion of phagosomes appears to begin in the apical processes.
| 16,301
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Alpha-adrenergic blockers on ventricular automatism in rat heart.
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The role of the alpha-adrenergic receptors in the genesis of cardiac arrhythmias induced in the isolated rat right ventricle has been studied. The administration of six alpha-adrenergic blocking agents (phenoxybenzamine, dibenamine, phentolamine, tolazoline, azapetine and SY-28) did not alter the automatism induced. Even when can not be excluded the existance of alpha-adrenergic receptors in the rat ventricle, it is clear that alpha-blocking drugs are ineffective to abolish the arrhythmias induced by an increase in the activity of the Purkinje fibers.
| 16,319
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[Isolation of the islands of Langerhans from rat pancreas and determination of proteolytic activity in them].
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A modified method for isolation of Langerhans islands from rat pancreas is described. The islands obtained were free from acinous tissue as shown by means of an amylase test and by microscopy. In homogenates of the islands proteolytic activities were observed (pH optimum at 5.3--5.5 and 6.9--7.2).
| 16,389
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Distribution of coronary blood flow in the left ventricular wall of dogs evaluated by the uptake of Xe-133.
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The distribution of coronary blood flow was estimated in anesthetized dogs by counting the activity in tissue blocks of the left ventricular free wall immediately after bolus injection of Xe-133 into the aortic root. No differences in the uptake of isotope were observed between the apex and the base of the heart; between areas supplied by the anterior descending and circumflex branches of the left coronary artery; or between the endo- and epicardial halves of the wall. In most experiments a bolus injection of the isotope into the left coronary artery was followed by a difference in activity between areas supplied by the left anterior descending and left circumflex branches. This indicated inadequate mixing of blood and isotope in the main stem of the artery. The uneven distribution did not result in differences between the epi- and endocardial activity concentrations. The results from one normal, anesthetized dog in which tissue activities were measured after constant rate infusion of Xe-133 into the left coronary artery for 8 min were in accordance with the general assumption of equal epi- and endocardial volumes of distribution (values of lambda).
| 16,436
|
Uric acid transport characteristics in human erythrocytes.
|
Taken all together the results show that the RBC transport of U.A. seems to be partly of passive nature, closely similar to others mineral or organic anions, and partly of active nature related to compound of the membrane playing a role in cellular metabolism. It remains to be precised the role of the membrane itself and to characterize the membrane site which could be responsible of a part of the transport of U.A. through erythrocyte membrane.
| 16,456
|
Observations on the feeding and defecation patterns of three triatomine species (Hemiptera: Reduviidae).
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A comparative laboratory study of feeding and defecation behavior of three species of tritomines (Rhodnius prolixus, Triatoma infestans and T. dimidiata) indicated evident differences among the species and among the different stages of same species. Time required for a full blood meal was related to the size of the specimen. Insects required an average of 11-28 min for engorgement although some finished within 10 min. T. dimidata frequently interrupted the act of feeding, a probable explanation of the higher number of defecations before finishing a blood meal observed in the species. R. prolixus was superior to the other two species in number of defecating insects and in rapidity and frequency of defecations within a given time. T. dimidiata was inferior in all three parameters and T. infestans was intermediate. Males of all species tended to be less effective. A "defecation index" is proposed for comparing this different behavior in triatomine specimens under standard conditions. Effectivity of the insects according to the measured parameters is discussed in relation to the prevalence of Chagas' disease in those areas where they are principal vectors.
| 16,468
|
Effect of gallstone-dissolution therapy on human liver structure.
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To assess potential toxic effects liver biopsies were performed before and after 6-8 months therapy with chenodeoxycholic acid (CDCA), 750 mg daily, in 6 patients with gallbladder stones. Minor fatty change and lipofuscin were seen prior to therapy, which tended to increase afterwards. Otherwise there was no consistent change on light microscopy. Electron microscopy showed parallel changes in the hepatocytes with no marked damage. There was a patchy loss of microvilli in the biliary epithelium. However, there was a significant increase in sinusoidal lipocytes or Ito cells, which was seen in every case. These 6 patients were representative of a group of 20 patients in whom serum liver function tests have been followed monthly for at least 6 months. During this period aspartate aminotransferase levels rose slightly but significantly, the mean remaining within the normal range. There was a trend to a decline in alpha-glutamyl transpeptidase levels, but this was less impressive and not statistically significant.
| 16,480
|
Computer simulation of rat heart metabolism after adding glucose to the perfusate.
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An experiment where perfused rat hearts receiving no substrate are suddenly given glucose with insulin in the perfusate is simulated with a computer model of cardiac energy metabolism. Mitochondrial metabolism is quantitatively reorganized under cytoplasmic control, with fatty acid oxidation undergoing a two-step decrease. There is an unspanning of the Krebs cycle (different reactions going at different rates) due primarily to slowing of alpha-ketoglutarate dehydrogenase; this ends when cytoplasmic glucose reaches a new steady state. Mitochondria in vitro are known to have higher pH than their surroundings; it is found here that this also holds in situ. Under these conditions, glycolysis is coherently substrate controlled, as is phosphofructokinase, usually considered the typical example of an allosteric enzyme. Limitations on simple methods of analyzing metabolic data of this type, e.g., use of lactate/pyruvate ratios to calculate NADH/NAD ratios, are discussed. Here a large volume of enzyme and other biochemical information has been integrated into a physiologically meaningful system.
| 16,503
|
Relationship between gastric mucosal pH and site of peptic ulceration.
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Measurements of mucosal pH of resected stomachs were carried out in gastric and duodenal ulcer patients. Low mucosal pH along the lesser curvature and relatively higher gastric pepsin levels were found. It is suggested that this lower pH affects gastric ulcer occurrence in the limited "lesser curvature area" where 63 per cent of the ulcers were situated. It is also suggested that increased pepsin activity present in gastric ulcer patients may be another factor affecting gastric ulcer formation by virtue of pepsins activated at higher pH. In duodenal ulcer patients, these factors are "overshadowed" by high acid-pepsin secretory activity of gastric juice.
| 16,504
|
[Membrane oxygenators in cardiac surgery: progress].
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This study tries to define if the membrane oxygenators are available during cardiac surgery under E.C.C., and if their performance are superior to those of conventional oxygenators. Two series of research are done. In the first one, we compare performance of two membrane oxygenators: the Rhône-Poulenc heart-lung machine (10 cases) and the Travenol TMO Teflo machine (100 cases). The general impression is good: the two proposed systems seem to be perfectly well adapted to surgical utilization conditions, avoiding excessive ventilations and eventually allowing to keep on E.C.C. in postoperative. In the second part of this work, two series of patients are studied, one oeprated under membrane oxygenator (Teflo), the second under bubble oxygenator (Bentley Q 100). Comparative study shows small differences between the two groups. Only the post-operative enzymatic profile is clearly for the membrane oxygenator which also insure a waking and a postoperative recovery of highest quality. These first observations justify to keep on using of membrane oxygenators in cardiac surgery.
| 16,518
|
[Methods of sampling and preservation of blood used during extracorporeal circulation].
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The blood supply of Cardiac Surgery Centers set quantitative and qualitative problems to the Centers of blood dispatch. In this work, from a Lyonese experience on 4,000 E.C.C., authors try to define the best preservative solution, especially for the respiratory function of the red blood cell. The C.P.D. solution (citrate, phosphate, dextrose) answers to requirements in this field when the blood used is less than 48 hours old. In the meantime, it is not impossible that studies based on definite criteriums of evaluation and on severe comparisons allows to adapt new process from which some are described and criticized in this work.
| 16,519
|
[Protection of the myocardium by hypothermia during extracorporeal circulation. Experimental and clinical study].
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Hypothermic protection of myocardia during E.C.C. has been estimated on a 35 dogs experimental series and on a clinical series of 700 acquired cardiopathies of adult, including 400 valvular replacements and 300 aorto-coronary by-pass. Experimental results have been estimated by biochemic and morphologic controls done on myocardic samples took up by drillbiopsy. The biochemical study includes among others a dosing of the high-energy phosphorus compounds (P.C. and A.T.P.). Morphological study was done by optic and electronic microscopy. Results made clear the superiority of the hypothermic ischemia at 10 degrees C on the continued perfusion at 32 degrees C with fibrillative heart. An hypothermic protection method with successively cold perfusion of the coronary system and a heart immersion in a salted solution at 4 degrees C has been utilized during valvular and coronary surgery on human in 700 cases. The total mortality was of 5,8 p. 100. The rate of post-operative infarcts was 2,4 p. 100. Incidence of intra-ventricular conduction troubles has been 1,1 p. 100. There was no relation between mortality and morbidity of myocardic origin and the lasting of the ischemic clamp, which were of 21 mn up to 165 mn. The low incidence of complications of myocardic origin is due to the hypothermic protection of the myocardia.
| 16,526
|
[Myocardial protection by coronary perfusion and specific problems of myocardial protection in combined valvular and coronary surgery].
|
The quality of the myocardial protection by bilateral coronary perfusion was studied in a consecutive series of 80 patients treated by isolated aortic replacements (47 cases) or multiple replacements (mitro-aortic, or mitro-aortic and tricuspid) 33 cases. Four low outputs (5 p. 100) were observed with only one death. Five post-operative necroses (6.25) were noted. The overall surgical mortality was 6.25 p. 100 (5 cases out of 80). There were two deaths in the series of the 47 single replacements and three deaths (9) in the series of multiple replacements. At the same time, the myocardial protection was studied in a consecutive series of 12 cases of valvular replacements combined with coronary shunts. In all of the cases, the shunt or shunts were carried out first, the myocardial protection was subsequently ensured by a coronary perfusion carried out by means of the shunts and directly through the coronary orifices. There were 2 deaths (16), 2 necroses (16) both responsible for deaths and no low output in the 10 survivors. Coronary perfusion very certainly ensures an excellent quality of myocardial protection if certain criteria are respected: hypothermia, moderate (28 degrees) bilateral perfusion with a mean perfusion pressure above 100 also ensuring a good flow through the sub-endocardial layer, which remains particularly sensitive to ischiemia. In cases of associated shunts, they must be carried out, first of all, in cases of tight senoses, over 60.
| 16,527
|
[Drug protection of the myocardium during cardiac surgery].
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During aortic clamping, drug protection of the myocardium, far from supplanting hypothermia, complements it, particularly in the case of left ventricular hypertrophy. Ultramicroscopy and new techniques of histobiological exploration of the myocite have enabled one to distinguish the lessions provoked by anoxia from those induced by reperfusion. At present, drug protection, extended to energetic solutions and electrolytes, aim at preserving energy metabolism by stocking of the substrate and at avoiding interferences which precipitate exhaustion of the adenosine triphosphate and phosphocreatinine reserves. In order to do this, hemodilution in particular is limited in subjects with decompensated cardiopathy; choice of anesthetics is orientated towards neuroleptanalgesia or fluothane, and it is attempted to neutralize the adrenergic reaction by the use of beta-blocking substances. Furthermore, it is preferred to interrupt electrogenesis at the stage of polarization: depolarizing cardioplegic solutions rich in potassium and sodium are rejected and in preference membrane stabilizers are used (procaine, magnesium, tetrodoxine...) The ultramicroscopic analysis of the structural modifications leads to sparing of the integrity of the lysosomial membrane by corticoids and alkalines. The use of calcium is deferred, anti-calcium techniques are even proposed (washing poor in calcium, verapamil). Cellular edema is prevented and treated by solution (mannitol - sorbitol) whose osmolarity must be less than 300 M osm/l. A conditioning of the biochemical and physicial structures and of cardiac work is being more and more thought of which leads to the classification of beta stimulating substances as negative, and their indications must be seriously thought of and used with reserve.
| 16,531
|
[Shivering during recovery after cardiac surgery under extracorporeal circulation. Inconveniences and methods of prevention].
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Among 109 subjects who had undergone cardiac surgery under ECC, the authors recorded 50 (45 p. 100) who suffered from shivering during the coming round period. Comparing the series of patients who shivered, with that of the subjects who did not shiver, the authors demonstrate in the first case, an increase in cellular metabolism, the cardiac index, heart rate, central venous pressure and cardiac work. They subsequently note the apprearance of mixed acidosis and an increase in the lactate-pyruvate ratio. Certain patients, in whom the cardiac output did not keep up with the metabolic demand considerably increased the arterio-venous oxygen difference. Blood loss is increased as well as coagulation time showing a more intense heparin rebound. The study of the drugs used during anesthesia showed that the patients who had received chlorprotixene, as the neuroleptic, a neuroleptic with adrenolytic properties, had a very decreased frequency of shivering in comparison with those who had received droperidol. The placing of the patient at the end of the intervention on a heating mattress, combined with the administration of chlorprotixene during anesthesia, prevented the appearance of shivering.
| 16,532
|
[Use of a membrane oxygenator in extracorporeal circulation in the child. Preliminary conclusions].
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The comparison of two types of oxygenators, the bubble and membrane oxygenator, in cardiac surgery under ECC, in infants. The results were not subjected to a statistical study. However, it seems that the membrane oxygenator enables one to obtain a satisfactory hematosis in a simpler fashion (the addition of CO2 being avoided) than with the bubble oxygenator and leads to less hemolysis than the latter. In the cases of closed circuit ECC with recirculation, the use of the membrane oxygenator also gives greater security of manipulation of the blood mass.
| 16,540
|
Renal function during and following obstruction.
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The effects of urinary-tract obstruction on renal function have been clarified using modern physiologic techniques in animal models. These effects are obviously dependent on the severity and duration of obstruction, together with the presence or absence of extrarenal factors, particularly uremia, as exemplified by the differences in renal function between bilateral and unilateral obstruction. The beneficial effects on the unilateral postobstructive kidney of volume expansion (5) and the importance of azotemia in determining POD (20, 21) have possible clinical applications. Further experimental work is required to understand the mechanism responsible for the altered renal hemodynamics and decreased GFR, as well as the abnormalities in medullary function resulting from obstruction. Improvement in the management of this common clinical problem may then be forthcoming.
| 16,559
|
Neurophysiologic and pathologic aspects of acute and chronic pain.
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Acute pain produced by disease or injury is the net effect of highly complex interactions of various neural systems and psychological factors. Through the interaction of the afferent systems and neocortical processes, the individual is provided perceptual information regarding location, magnitude, and spatial and temporal properties of the noxious stimulus that activates motivational tendencies toward escape or attack and permits analysis of multimodal information, past experience, and probability of outcome of different response strategies. In contrast, chronic pain is a malefic force that taxes the physical, emotional, and economic resources of the patient, his famiily, and society. Moreover, chronic pain is characterized by physiological affective and behavioral responses that are quite different than those of acute pain. The clinician must keep these differences in mind in order to provide patients with optimal relief of their pain.
| 16,580
|
The intracellular pH and the buffer capacity of the heart.
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The intracellular buffering (delta HCO3-/delta pH) in rats is lowest in skeletal muscle, intermediate in the diaphragm and highest in cardiac muscle. In the hypertrophic heart due to aortic constriction or to the Goldblatt mechanism the buffer value increases markedly during the first weeks, but returns to normal or even subnormal values during stable hypertrophy. There is an electrochemical disequilibrium for hydrogen ions caused by an active transport of ions across the cell membrane, which is possibly correlated to the myocardial activity.
| 16,587
|
Serum gonadotropins in the rat after prenatal damage to the testes by busulfan and their reaction to cryptorchidism, castration and administration of testosterone.
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Adult male rats prenatally treated with 1,4-bis-(methanesulfonyloxy)-butane (busulfan), which damages the gonocytes, undergo cryptorchidization, castration or testosterone treatment and the FSH, LH and testosterone levels in serum are measured. Basal values of these hormones do not differ from those of controls. After cryptorchidization FSH levels rise but the LH levels do not. Following orchidectomy both hormone levels increase significantly. Application of testosterone in various doses increases FSH in normal animals but not in busulfan treated rats 24 h post infectionem. FSH and LH levels 7 days after administration do not differ from controls. According to the hypothesis that the FSH release depends on an inhibin from the testes, these experiments show evidence for inhibin being produced only in the Sertoli cells.
| 16,621
|
Possible regulation of thiamine diphosphatase activity in rat brain microsomes by lipids.
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The effects of various treatments, which affect membrane structure, on microsomal thiamine diphosphatase and thiamine triphosphatase activities of rat brain, were examined. The treatment of micorosomes at alkaline pH caused a 2-fold activation of the thiamine diphosphatase, this being related to a change in membrane structure which was evidenced by a decrease of the turbidity of the microsomal suspension. Repeated freezing and thawing after hypo-osmotic treatment also increased the activity of microsomal thiamine diphosphatase. In addition, the thiamine diphosphatase activity was enhanced by treatment of the microsomes with phospholipase C or acetone. This lipid depletion resulted in a marked reduction in the apparent Km value of the thiamine diphosphatase with a corresponding loss in heat stability of the enzyme. We found further that brain thiamine diphosphatase was solubilized by Triton X-100. This decreased the phospholipid content in the preparation, but did not affect the apparent Km value and heat stability of the enzyme. In contrast with thiamine diphosphatase, thiamine triphosphatase was inactivated by treatment at alkaline pH or with acetone. However, treatment with phospholipase C did not affect the activity of thiamine triphosphatase.
| 16,655
|
The interaction of histone H3 with histone H4 and with other histones studied by 19F nuclear magnetic resonance.
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The behaviour, upon variations in ionic strength, pH and temperature of 19F nuclear nuclear magnetic resonance signals of the trifluoroacetonylated derivative of histone H3 is compared with those of the H3-H4 complex and of the Hv fraction (an equimolar mixture of H2A, H2B, H3 and h4). The line width of the 19F-labelled histone H3 signals increases with ionic strength or pH, an effect consistent with aggregation of the protein. In the case of H3-H4 complex or Hv the line width decreases at intermediate ionic strengths (0.1-0.25 M NaCl). This effect is interpreted as the consequence of the formation of a well defined structure with ionic strength. At high salt concentrations the line width increases as a consequence of the final rigid quaternary structure or of the formation of higher aggregates.
| 16,662
|
The denaturation of beta-lactoglobulin-A at pH 2.
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The denaturation of beta-lactoglobulin-A by heat and guanidine hydrochloride at pH 2 has been investigated. The effect of ethylene glycol on the thermal denaturation at this pH has also been studied. The conditions of the experiments have been chosen so as to eliminate complications arising out of disulfide interchange, changes in the degree of association of the protein during denaturation, and intermolecular aggregation. The physical parameters characterizing the denatured states of the protein which are produced by heat and guanidine hydrochloride have been determined. The thermodynamic parameters for these transitions have been estimated using a two-state hypothesis in each case. Both the physical and thermodynamic parameters indicate that the heat-denatured state of beta-lactoglobulin-A retains about 15-20% of residual structure which is destroyed on adding guanidine hydrochloride.
| 16,664
|
[Influence of pH on the steady state kinetics of electron transfer through the cytochrome chain of submitochondrial particles. Kinetic model for regulating the activity of carriers by the local concentration of hydrogen ions in the membrane].
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The kinetic parameters of the submitochondrial particles cytochrome chain obtained from steady-state kinetics were studied for pH dependence. The life-times of the activated states (tau) for cytochrome pairs b leads to c1 and a leads to a3 are shown to bear dissimilar dependence on pH of the medium, while for cytochrome pairs c1 leads to c and c leads to a they display practically no pH dependence at all. The rate constants of the non-activated state (alphai-kiCo) decreased for the pair b leads to c1 and increased for a leads to a3 with the increase of pH from 6.5 to 8.5. The apparent pK values obtained therefrom were 7.2 and 8.9, respectively. A kinetic model is proposed suggesting that local pH in the mitochondrial membrane, dependent on the rate of electron transfer, may be a controlling factor for the ratio of activated and non-activated carrier states. The model is in good consistence with the experimental dependences of k'i on V and the pH dependences of alpha2 for b leads to c1 and a leads to a3. It also gives a qualitative prediction for the pH dependences of the ordinate intercepts of the straight lines in l/(k'i--alphai) vs. l/V plots. The rate constants for the diffusion of hydrogen and hydroxyl ions in the membrane are estimated on the basis of our kinetic data to be 10(4)--10(5) s-1 and 10(2)--10(3) s-i, respectively.
| 16,667
|
Human cytomegalovirus. A review of developments between 1970 and 1976. I. Clinical developments.
|
Cytomegalovirus (CMV), like other members of the herpesviruses, is widely distributed in human populations where the frequency of seropositive individuals is influenced by such factors as age, sex and socio-economic conditions. While this virus causes such diseases as mononucleosis, it is also implicated in autoimmune phenomena and plays an adverse role renal and bone marrow transplantation. Perhaps the most menacing aspect of CMV is the role which it play in congenital malformations resulting from in utero or neo-natal infection. Indeed, this virus is one of the few which can be transmitted vertically. The above mentioned clinical aspects of CMV are discussed here in light of recent clinically studies. The second part of this review will be devoted to the great mass of information recently acquired through experimentation.
| 16,671
|
[Blood gas measurements and automatization (author's transl)].
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The Corning 175, a fully automatic new blood-gas analyzer, was tested and compared with manual analyzers (Eschweiler-Radiometer). The precision was evaluated by means of tonometered bloods and precision gas mixtures. With the Corning 175 four parameters are measured: pH, PCO2, PO2, barometric pressure, and four computed: HCO3-, BE, oxygen content, oxygen saturation. These are automatically corrected for patient hemoglobin and temperature. A microprocessor controls the sequencing of all operations during the calibrations and the measurements and continuously checks the performances of the electrodes and the entire system. The operator part is limited to the introduction of blood. The advantages and the fiability of the automatism in clinical routine are described.
| 16,678
|
Striatal lesions with kainic acid: neurochemical characteristics.
|
Stereotaxic injection of 2.5 microng of kainic acid, a rigid analogue of glutamate into the rat striatum caused a 70% reduction in the striatum of the cholinergic parameters, choline acetyltransferase, acetylcholine and synaptosomal uptake of choline and a similar reduction in the GABAergic parameters, glutamic acid decarboxylase, psi-aminobutyric acid (GABA) and synaptosomal uptake of GABA. In contrast, the striatal content of dopamine and the synaptosomal uptake of dopamine were unchanged, and the activity of tyrosine hydroxylase was significantly increased. Significant changes in the activity of neurotransmitter synthesizing enzymes were demonstrable within 6h after injection of 2.5 microng of kainic acid and maximal effects occurred at 48h; the activities of choline acetyltransferase and glutamic acid decarboxylase remained depressed up to 21 days after injection. The kinetic characteristics of striatal tyrosine hydroxylase were altered 48h after injection with a two-fold increase in the Vmax for tyrosine and a three-fold reduction in Km for the pteridine cofactor. In contrast to the effects of kainic acid, the injection of copper sulfate, a non-specific toxin, caused a proportionate reduction in the dopaminergic as well as the cholinergic and GABAergic presynaptic markers. The kainate lesion caused an 85% decrement in the activity of dopamine-sensitive adenylate cyclase, a 40% reduction in the specific binding of [3H]quinuclidinyl benzilate and a 195% increase in the specific binding of [3H]GABA in the striatum. The morphology of the kainate injected striatum was markedly altered with nearly a complete loss of intrinsic neurons, increased number of glial cells but intact internal capsule fibers. Intracerebral injection of nanomolar quantities of kainic acid appears to cause degeneration of neurons with cell bodies near the injection site while sparing axons terminating in or passing through the region.
| 16,686
|
Cardiovascular effects of total hip placement in man. With observations on the effects of methylmethacrylate on the isolated rabbit heart.
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The cardiovascular effects of total hip placement were evaluated in 10 surgical patients, aged 55 to 82, while receiving fluroxene-N2O-O2 anesthesia. The anesthetic regimen caused mild cardiovascular depression. The placement of the acrylic cement into the acetabulum and femoral shaft also induced mild cardiovascular depression, but these changes were not significant at p less than 0.05. In one 67-yr-old woman, there were significant reductions of cardiac output and stroke volume 2 min after the insertion of acrylic into the femoral shaft, despite careful replacement of intravascular loss and careful anesthetic management. Methylmethacrylate (1 X 10(-6) to 1 X 10(-4), v/v) was administered to 24 isolated perfused rabbits hearts. These concentrations of methylmetacrylate are of the same order as measurable blood levels in surgical patients. There was a dose-dependent depression of left ventricular dP/dt correlated with a depression of the spontaneous heart rate. When the bradycardia was prevented by electrically pacing the hearts or the administration of atropine, the depressed dP/dt rose to control levels. Reduction in myocardial temperature and heart rate by means of reduction in perfusate temperature of the isolated hearts reduced the myocardial depressant effect of methylmethacrylate.
| 16,717
|
Erythrocyte adenosine triphosphate and 2,3-diphosphoglycerate after human renal transplantation: dissociation from hypophosphataemia.
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1. Erythrocyte 2,3-diphosphoglycerate (2,3-DPG) and adenosine triphosphate (ATP) were determined in normal individuals, uraemic patients on chronic haemodialysis and patients who underwent renal transplantation, and correlated with plasma phosphate and arterial blood pH. 2. Significant increases in the 2,3-DPG and ATP content were found in the uraemic patients and these persisted after transplantation in spite of marked hypophosphataemia. 3. No correlation was established with plasma phosphate for either of the compounds but 2,3-DPG had a significant correlation with arterial blood pH. 4. Normal values for ATP and 2,3-DPG were observed in post-transplant patients with normal haematological values. The high amounts of erythrocyte 2,3-DPG and ATP in the early post-transplant period are independent of the circulating concentration of inorganic phosphate, and might represent the response of erythrocyte glycolysis to changing arterial blood pH.
| 16,718
|
Spontaneous variability of the hemoglobin affinity for oxygen.
|
In order to evaluate the accuracy of our method of P50 determination, we measured P50 and 2,3-DPG on different days on several members of our laboratory staff and were surprised to find significant variation. Initially, we indicted our methodology but subsequent data suggest that significant P50 variability occurs, not correlated to alterations in 2,3-DPG or red cell pH. The largest variability on different days. 8.5 torr, occurred in a laboratory staff member studied 7 days apart. The P50 determinations were made by fixing PO2 by tonometry and determining oxyhemoglobin saturation by Van Slyke analysis. In contrast to our in vivo data, serial studies over 5-20 days performed upon 3 samples of stored CPD bank blood demonstrated the expected progressive decline in both 2,3-DPG and P50.
| 16,729
|
Oxygen availability during hypothermic cardiopulmonary bypass.
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Oxygen availability during cardiopulmonary bypass was assessed in 22 patients under hypothermic and relatively normothermic conditions. The patients were divided into two groups, 17 of whom received ACD blood and 5, CPD blood. The mean P50 for all patients fell from a preoperative value of 25.9 +/- 2.4 (SD) to 15.6 +/- 2.1 during hypothermia confirming a leftward shift of the oxyhemoglobin dissociation curve. Oxygen uptake, calculated from a-v oxygen content differences (avDO2) and flow, was significantly lower during hypothermic bypass (65 +/- 27 ml/min) than during rewarming (121 +/- 41 ml/min). The increase in oxygen affinity during hypothermia was influenced also by changes in acid base and 2,3-DPG concentrations, the changes being similar in both the ACD and CPD groups of patients. During rewarming, however, oxygen availability was increased in the CPD group presumably from significantly increased 2,3-DPG concentrations. A "functional" value of hemoglobin, based upon the effects of the shift of the oxyhemoglobin dissociation curve and, therefore, reflecting the true capacity of hemoglobin to unload oxygen at the tissue level, was calculated. During the hypothermic phase of bypass, this functional hemoglobin was only 4.2 g/100 ml blood, suggesting that, in spite of reduced metabolic demands, oxygenation reserves are minimal.
| 16,730
|
Multi-clinic cross-over comparison of triazolam (Halcion) and placebo in the treatment of co-existing insomnia and anxiety in anxious out-patients.
|
In this multi-clinic double-blind cross-over designed study, forty-five anxious and insomniac out-patients received either triazolam (Halcion) 0.25 mg or placebo at bedtime. After seven days the medications were crossed over. The dosage was doubled after nights 2 and 9 if good sleep was not produced. Three patients dropped out, two on placebo (one for side effects and one for lack of efficacy) and one on triazolam (due to misunderstanding instructions). Analysis of sleep questionnaire data showed superiority of triazolam to placebo (p less .001) in all parameters. The incidence of dreams was not affected. Analysis of antianxiety efficacy showed that triazolam was superior to placebo (p less than .001) in all parameters, both physician's and self ratings. Thus, either triazolam or a good night's sleep significantly relieved the patient's anxiety. No side effects or abnormal laboratory values of significance were attributable to triazolam.
| 16,735
|
The phosphoenolpyruvate-dependent phosphotransferase system of Staphylococcus aureus. 3. 1H and 31P nuclear-magnetic-resonance studies on the phosphocarrier protein HPr; tyrosine titration and denaturation studies.
|
The phosphocarrier protein HPr has been investigated by proton nuclear magnetic resonance (NMR) at 270 MHz in order to evaluate structural properties of the whole molecule and its active site. The titration behaviour of the three tyrosines of the HPr protein was analysed by monitoring the chemical shifts of the aromatic proton resonances of these residues as a function of pH. It was found that the HPr protein contains a lot of slowly exchanging NH backbone protons which suggested a relatively rigid secondary structure of the protein molecule itself although it contains no disulfide bridges. The HPr protein shows a sharp reversible denaturation behaviour at alkaline pH values. Between pH 10.8 and 11.1 two C-2 proton resonance peaks for the single histidine residue could be observed together with abrupt changes in the aromatic and aliphatic absorption region of the HPr protein which are due to chemical exchange processes. The NMR spectrum of the HPr protein is only changed a little upon raising the temperature from 14 degrees C to 70 degrees C. At 76 degrees C all resonances in the spectrum broaden and almost disappear. This process is irreversible.
| 16,753
|
Preference studies of triazolam with standard hypnotics in out-patients with insomnia.
|
One hundred and four patients suffering from insomnia took part in four different two-night double-blind crossover trials of triazolam. In three separate studies, triazolam 0-5 mg was compared to placebo, flurazepam 30 mg and chloral hydrate 500 mg. Triazolam 0-5 mg was found to be preferred and to be superior to placebo, flurazepam and chloral hydrate in the treatment of insomnia. Analysis of sleep questionnaire data showed triazolam to be superior to the other treatments on the following: How much did the medication help you sleep, onset of sleep, duration of sleep and number of awakenings. Additionally, triazolam was superior to chloral hydrate on the feeling in the morning parameter. In another comparison of triazolam 0-25 mg to flurazepan 15 mg, triazolam was not significantly better than flurazepam on any of the efficacy parameters except that the patients felt more alert the morning following triazolam that following flurazepam. On all efficacy endpoints, trends for all parameters favoured triazolam 0-25 mg over flurazepam 15 mg. Untoward side-effects in these four studies were minimal.
| 16,801
|
Volume characteristics of extra- and intraparenchymal segments of the canine pulmonary artery.
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The volumes of the extraparenchymal segment (VpaEP) and intraparenchymal segment (VpaIP) of the pulmonary arterial tree were determined in intact anesthetized dogs during room air breathing and acute hypoxia. Total pulmonary arterial blood volume (Vpatotal) was calculated as the product of pulmonary blood flow and pulmonary arterial circulation time. An angiographic technique was used to estimate VpEP. VpaIP was calculated by subtracting VpaEP from Vpatotal. During room air breathing at functional residual capacity, mean +/- SD of VpaEP was 17.1 +/- 5.1 ml and of VpaIP was 31.7 +/- 20.8 ml, representing 40% and 60%, respectively, of Vpatotal. Vpatotal increased 22.2 +/- 10.5 ml during lung inflation, with proportional increases in VpaIP and VpaEP. VpaEP was found to be influenced equally by changes in transmural pulmonary arterial and transpulmonary pressures. Acute hypoxia was accompanied by an increase in pulmonary vascular resistance and a decrease in volume distensibility of the extraparenchymal segment. Vpatotal increased 76% without changes in the relative volume distribution of VpaEP and VpaIP. These findings can be best explained by active vasomotion with an increase in down-stream pulmonary vascular resistance.
| 16,859
|
Actin-induced local conformational change in the myosin molecule. I. Effect of metal ions and nucleotides on the conformational change around a specific thiol group (S2) of heavy meromyosin.
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As previously reported when a specific thiol group, S2, of myosin reacts with N-ethylmaleimide (NEM), its Ca2+-ATPase activity is decreased. Therefore, the reactivity of S2 can be estimated by measuring the decrement of the enzymatic activity. Using the change in the reactivity as a structural probe, we investigated whether F-actin affects the conformation around the region containing S2 under physiological conditions (at neutral pH and low ionic strength). 1. Experiments were carried out with heavy meromyosin (HMM), S1 of which had heen blocked with NEM, to observe the reactivity of S2 alone. In the experiments done in the presence of F-actin, the Ca2+-ATPase activity was measured using the heavy meromyosin fraction after actin had been removed by centrifugation and gel filtration. 2. ATP and other nucleotides activated the reactivity of S2 in the presence of Mg2+. On the other hand, F-actin markedly activated the reactivity of S2 which had been increased by ATP, but not by the other nucleotides. 3. The above cooperative action of F-actin with ATP was not observed in the presence of Ca2+ instead of Mg2+, or above 0.2 M KCl. These results suggest that the S2 region of the myosin molecule is a key region in the molecular interaction of the actin myosin-ATP system under physiological conditions.
| 16,877
|
Source of residual Bohr effect in hemoglobin oxidation.
|
The hemoglobin oxidation Bohr effect is larger than the ligation Bohr effect, even when the former is corrected for any ionization of the water molecule bound to the ferric iron of methemoglobin. This residual oxidation Bohr effect is here shown to be solely caused by the influence of the positively charged ferriheme, and is abolished when the oxidized heme binds an anion. This result frees the formal equivalence of hemoglobin ligation and oxidation from the last apparent experimental discrepancy.
| 16,881
|
Bovine adrenal tyrosine hydroxylase: purification and properties.
|
Bovine adrenal tyrosine hydroxylase has been obtained in a form that is 85 to 90% pure. Sodium dodecyl sulfate-gel electrophoresis and density gradient centrifugation studies have established that the subunit molecular weight of the chymotrypsin-solubilized enzyme is 34,000. The presence of iron in the purified enzyme (0.50 to 0.75 mol of iron/mol of enzyme) has been established. Crude particulate tyrosine hydroxylase can be activated by the phospholipid, phosphatidyl-L-serine, or by exposure to enzymatic phosphorylating conditions. Both forms of activation lower the Km of the enzyme for its 2-amino-4-hydroxypteridine cofactor. By contrast, tyrosine hydroxylase that has been solubilized by chymotrypsin cannot be activated by either of these methods.
| 16,885
|
Repressible alkaline phosphatase from Thermus aquaticus: associated phosphodiesterase activity.
|
A repressible alkaline phosphatase has been isolated from the extreme bacterial thermophile. Thermus aquaticus, and has been purified to homogeneity as judged by disc acrylamide electrophoresis and sodium dodecyl sulfate electrophoresis. Upon investigation, the purified enzyme was shown to hydrolyze certain phosphodiesters in addition to a wide variety of phosphomonoesters. The diesters included bis-p-nitro-phenyl phosphate and thymidine 3'-monophospho-p-nitro-phenyl ester. The temperature optimum for the diesterase activity was 80--85 degrees at pH 7.2. Orthophosphate competitively inhibited both activities. Nucleotides such as AMP, ADP, and ATP also inhibited both esterase activities as did alpha-D-glucose 1-phosphate and alpha-sodium glycerol phosphate. The isoelectric point of the enzyme was determined to be 8.4.
| 16,900
|
Use of 1-anilino-8-naphthalene-sulfonate as a probe of gastric vesicle transport.
|
The interaction of 1-anilino-8-naphthalene-sulfonate (ANS) with vesicles derived from hog fundic mucosa was studied in the presence of valinomycin and with the addition of ATP. Evidence was found for two classes of sites, those rapidly accessible to ANS with a KD of 7.5 micronM and those slowly accessible, but rapidly accessed in the presence of valinomycin with a KD of 2.5 micronM. ATP transiently increases the quantum yield of the latter ANS binding sites only in the presence of valinomycin, but does not alter the number of KD of those sites. The time course of this increase correlates with H+ uptake and Rb+ extrusion by those vesicles and H+ carries such as tetrachlorsalicylanilide or nigericin abolish the ATP response. With ATP addition in the presence of SC14N and valinomycin there is transient uptake of SCN-. It is concluded that ANS is acting as a probe of a structural change dependent on a potential and H+ gradient.
| 17,006
|
Costs and outcomes for different primary care providers.
|
This study examined the relationship between levels of medical training and direct costs for 1,700 episodes of acute illness treated in ambulatory-care clinics. Faculty, family practice residents, and physician assistants were included as the providers. Total cost and four component costs were examined. An outcome was defined as good if the patient returned to his usual level of functioning after an acute illness episode. Average total cost per episode was not related to type of provider, but there were significant (P less than .05) differences among providers in laboratory and medication costs. Faculty and physician assistants produced higher costs, especially for patients who experienced bad outcomes. Both costs and percentage of good outcomes achieved were similar in first-, second-, and third-year residents.
| 17,020
|
Purification of histamine receptor. (IV) Specificity of binding of various drugs to the histamine receptor-rich fraction and to solubilized binding sites.
|
Studies were made on tritiated histamine binding to the receptor-rich membrane fraction and solubilized sites and its displacement by various drugs. H1-Agonists and antagonists displaced histamine most effectively. A H2-agonist and atropine were less effective and propranolol, phentolamine and imidazole acetic acid had little effect. The solubilized binding sites showed the same specificity of binding as the membrane fraction. Membrane fragments had two binding constants, whereas solubilized sites had only one. Solubilized sites bound similar amounts of histamine and dibenamine: the latter was applied to intact tissue under conditions which would presumably cause specific binding to histamine receptors. These binding characteristics show that the method used was adequate for purification of histamine receptors from smooth muscle of cat small intestine.
| 17,028
|
[Prolongated amnesia after "rohypnol" i.v. before local anesthesia and responsiveness during operation (author's transl)].
|
An up-to-eight-hour lasting anterograde amnesia is achieved by "Rohypnol" i.v. causing no excitation before local anesthesia is given (prolongation by analgetics, anesthetics, neuroleptics). The cardiovascular functions remain stable with spontaneous breathing and preservation of the swallow and coughing reflexes. During the operation the patient is responsive and cooperative. The patient answers all questions, moves his body into any wanted position and when ordered he performs Valsalva's manoeuver without any remembrane. If not spoken to and having no pain he falls asleep right away. Postoperative vomiting is reduced. The patient feels relaxed after waking up. No complications have been noticed during more than 500 operations. The later questioning of all patients showed only 4 patients (with unsufficient preoperative sedation) who could remember part of the terminal phase of the operation.
| 17,038
|
Studies of yeast alcohol dehydrogenase with 3-aminopyridine monucleotide.
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3-Aminopyridine mononucleotide, a nicotinamide mononucleotide analog, was prepared by enzymatic cleavage of 3-aminopyridine adenine dinucleotide by a snake venom phosphodiesterase and isolated by means of ion exchange chromatography. The spectrophotometric and fluorometric properties of this analog were studied. Several anions were shown to quench the fluorescence intensity of this analog. pH was shown to have a pronounced effect on the fluorescence intensity. 3-Aminopyridine mononucleotide was shown to be a coenzyme-competitive inhibitor of yeast alcohol dehydrogenase. The 3-aminopyridine mononucleotide was diazotized with the use of nitrous acid. A time dependent irreversible inactivation of yeast alcohol dehydrogenase resulted from incubation with the diazotized 3-aminopyridine mononucleotide at pH 7.0. Incubation of the enzyme with NAD prior to the addition of the diazotized 3-aminopyridine mononucleotid protected the enzyme against inactivation.
| 17,065
|
A DNA nicking-closing enzyme encapsidated in vaccinia virus: partial purification and properties.
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Vaccinia virus cores contain an activity which is able to relax both left-and right-handed superhelical DNA. This virus-specific nicking closing enzyme has been highly purified and differs from the corresponding host enzyme in salt optimum, in sedimentation coefficient, and in polypeptide composition as determined on sodium dodecyl sulfate/polyacrylamide gels. The enzyme is probably newly synthesized after the cessation of host protein synthesis which follows virus infection. The most highly purified preparation contains two polypeptides, one of molecular weight 24,000 and the other 35,000. The former polypeptide is a major constituent of the virus (7% of total protein by weight), whereas the latter is present in a much smaller amount (0.2%). Chromatography with denatured DNA-cellulose reveals that the activity is predominately associated with those fractions enriched in the polypeptide of greater molecular weight.
| 17,115
|
[Desugarization of egg white by microorganisms].
|
Glucose was eliminated from egg whites, using microorganisms, to prevent melanoidin formation which may damage the product. Desugarization was achieved by means of Acetobacter xylinum, Streptococcus lactis, Propionibacterium shermanii, Pr. petersonii and propionicacid cocci. Optimal conditions of desugarization were found, depending on the physiological characteristics of the above microorganisms. Propionibacterium shermanii may be well used to ferment a liquid egg white. These bacteria have no proteolytic properties and make no use of the egg white. They enrich the egg white with vitamin B12 and propionate, a preserving agent, during fermentation.
| 17,113
|
[Migrating and recurrent superficial phlebitis and Takayasu's disease (apropos of a case)].
|
This case of recurrent migratory superficial phlebitis is reported because of the highly unusual nature of the lesion observed. The picture was dominated by periphlebitis with inflammatory granuloma, giant cells and elastophagia. When the condition had been present for sixteen months, an aortic arch syndrome developed in an inflammatory context. In this light, various auto-immunological etiologies were considered, among them Takayashu's arteritis of which, in the author's opinion, this would be the first case to be combined with venopathy.
| 17,133
|
[Gastro-esophageal reflux disease. A review of pathogenesis, diagnosis and therapy].
|
Gastro-esophageal reflux disease is caused by peptic damage from gastric contents to the distal esophagus. The principal cause of reflux is a decrease in pressure of the lower esophageal sphincter, which normally separates the esophagus from the stomach. Various hormonal, pharmacological or toxic agents are capable of altering resting sphincter tone. Treatment of esophageal reflux disease is a rewarding task for the general practitioner. An algorithm on appropriate use of diagnostic and therapeutic resources is presented.
| 17,158
|
[Beta blockaders and general pathology].
|
The authors review the literature on the undesirable side effects of beta blockaders (excluding the cardiovascular system) and report the new therapeutic propects in psychiatry and in various metabolic disorders. The necessity of sufficient follow up made us choose propanolol as reference product without neglecting acebutolol, pindolol and oxprenolol.
| 17,162
|
[Labilization of lysosomal and peroxisomal membranes in the kidneys preserved by transrenal gas perfusion].
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The total, free and unprecipitated activity of lysosomal (acid DNAase, acid RNAase, acid phosphate, acid beta-galactosidase) and peroxisomal (catalase, oxidase of D-amino acids) enzymes were studied in dog kidney cortex during storage of the tissues in solution of rheopolyglucin and under conservation of the kidney tissue by transrenal gas perfusion in hypothermia within 3 and 7 days. Labilization of lysosomal and peroxisomal membranes was observed during storage both in unperfused and in oxygenated kidney. Mechanisms of formation and functional significance of the alterations observed in structure of lysosomes and peroxisomes are discussed.
| 17,222
|
Contribution of arterial blood lactate measurement to the care of critically ill patients.
|
Arterial blood samples from 202 critically ill patients were studied. Lactate concentration, PO2, PCO2, pH, oxygen saturation, total CO2, and toe temperature were measured. Base excess, buffer base, actual bicarbonate, and standard bicarbonate were calculated. Analysis of the initial data obtained from each patient revealed that lactate concentration alone could not be used to predict survival. Elevations in lactate concentrations were observed in all types of acid-base disturbances. Survival was lowest (30%) for patients in metabolic acidosis with respiratory compensation, mean lactate concentration 10.5 mEq/l (mmol/l), and highest (65%) for patients in uncompensated respiratory alkalosis, mean lactate concentration, 2.57 mEq/l (mmol/l). Knowing the type of acid-base disturbance is necessary to evaluate the significance of elevated blood lactate values.
| 17,295
|
[Gerontology in rural and mountains regions aged people in the country and in mountain regions (author's transl)].
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The gerontologic problems of people living in the country and in mountain regions always were neglected in comparison to those of townsmen. In the last decade an important structural change has happened, caused on the one side by the fact that more and more people leave the country for the towns, and by the problem of overaged persons in the country; on the other side this change is a consequence of improvement by modern technical acquisitions (more agricultural machines, silos), living hygiene and the tourism. The living conditions in the past and today in Switzerland are shown, referring to various publications. The ecological change also hits the aged people, financially by revenues, completion of private help organizations, rebuilding of homes for the aged persons in every village and regional nursing home, as well as household helps for those elderly people who still live in the country in their own houses. The qualitative differences between living conditions in the country and in town will in the near future be equalized--which is especially mentionned.
| 17,312
|
[Living conditions of the rural population in France. Situation in 1974 and evolution from 1967 to 1974 (author's transl)].
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A survey of the living conditions of aged people in rural regions of France in 1974 and a comparison with the previous surveys of 1967/68 in 302 rural vallages are analysed. Of the 4,800 persons in 1967/68, by 1974 1,609 were dead (35%). After questioning the 2,191 living persons (1,275 farmers and 916 non farmers) an increased number of widowed people appeared in those 7 years. For men in 1967/68: 20%, now 28%; for women in 1967/68: 61%, now 72%. In the age group 75-79 three times more women lost their husbands than men lost their wives. 2/3 of the households remained identical, 1/5 became smaller, 1/8 increased. The comparison (excluding the dead persons) showed no significant differences in the health conditions. Detailed questions were asked regarding social relationships but it is very difficult to analyse the date due to the great number of dead persons. The difference between farmers (whose number decreases) and non farmers (whose number increases) is especially mentioned and specific problems are treated separately. In France ageing in rural areas is increasing rapidly: in 1968, 393 rural counties contained 20% of people aged 65 or more.
| 17,314
|
Fungal growth on C1 compounds: quantitative aspects of growth of a methanol-utilizing strain of Trichoderma lignorum in batch culture.
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A study was made of some salient parameters that influence growth of the methanol-utilizing fungus Trichoderma lignorum growing in batch culture on a minimal medium containing methanol as the sole source of carbon. Maximum cell yield was recorded at the expense of 1.58 g of methanol per liter. Inhibition was observed with methanol concentrations in excess of 4.7 g/liter. The optimum temperature for fungal growth was 23 degrees C. Growth of the fungus was directly proportional to an inorganic nitrogen concentration up to 0.2 g of NH4NO3 per liter. No inhibition of growth occurred at any concentration of NH4NO3 up to 11 g/liter. The pH of the growth medium decreased from 7.0 to 3.5 during growth of the fungus on methanol, which may have been due, in part, to the accumulation of trace amounts of organic acids in the growth medium. An analysis of the commercial potential of the fungus, as a source of edible protein, indicated that the strain of methanol-utilizing T. lignorum used was uneconomical in terms of the yield and the specific growth rate.
| 17,365
|
Identification of the virucidal agent in wastewater sludge.
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Anaerobically digested sludge contains an agent that causes irreversible inactivation of poliovirus. It has now been shown that the agent responsible for this activity is ammonia. The effect of ammonia on poliovirus appears to be typical for picornaviruses, but reovirus, an enteric virus of another group, is quite resistant to this compound. Because ammonia is not virucidal in its charged state, it expresses significant activity only at pH values greater than 8. Therefore, increasing the pH of sludge should cause rapid inactivation of indigenous picornaviruses.
| 17,367
|
Haemagglutination tests in the study of Ascaris epidemiology.
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Haemagglutination tests using adult Ascaris suum antigen were performed on sera from 810 people from three areas in Papua New Guinea and East Timor. In the area with the highest childhood Ascaris infection rates and egg-counts (Kaul), titres were highest and remained high throughout life. There was a significant negative correlation between titre and eosinophil count, and it is suggested that high titres in adult life result from continuous usually unsuccessful reinfection, and that the declining egg-counts and infection rates with increasing age may be the result of an immune mechanism, and not decreased exposure. In the two other populations the less intense Ascaris infection was reflected in the lower titres, with no correlation between titres, infection or eosinophilia. Although the haemagglutination test as used here is unsuitable as a diagnostic aid, it is valuable in studying the epidemiology of Ascaris infections.
| 17,370
|
Blood serum peptidases in patients with ovarian carcinoma treated with Ledakrin.
|
The authors observed changes in activity of leucine amino-peptidase (E.C. 3.4.1.1--LAP), gamma-glutamyl transpeptidase (F.C 2.3.2.2--GGTP) and Co++-activated acylase in blood serum of patients with ovarian carcinoma, with or without ascites, treated with Ledakrin (1-nitro-9-[3-dimethylaminopropylamino] acridine). It was stated that the activities of LAP and GGTP increased during the treatment and during tumor progression. The level of Co++-activated acylase increased only slightly during the treatment and therefore, the determination of this enzyme appeared to be of no use in monitoring the therapy of ovarian carcinoma.
| 17,375
|
The interaction of N-acetylhexosaminidase with insolubilized concanavalin A.
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The specific interaction between human N-acetylhexosaminidase and concanavalin A was evaluated with respect to temperature, time, pH and concentration of specific ligand in incubation mixtures containing the enzyme and insolubilized lectin. Elution of the enzyme from insolubilized concanavalin A is dependent on both temperature and concentration of alpha-methyl mannoside. Conditions for a high yield of the enzyme from chromatography on insolubilized concanavalin A are described.
| 17,397
|
[Treatment of coronary insufficiency with beta-receptor antagonists (author's transl)].
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The pathophysiology of the coronary insufficiency, the effect of beta-receptor antagonists, the understanding of these effects on the basis of the pathophysiology and the possibilities of testing beta-receptor antagonists in patients with coronary insufficiency are discussed. It is pointed out that the pathophysiology of the coronary insufficiency is based on the difference between oxygen demand of and oxygen supply to the myocardium. beta-Receptor antagonists compensate for this difference. Testing beta-receptor antagonists should include tolerance to exercise and controlled studies using standard medication for comparison.
| 17,414
|
[Quantitative parameters of sympatho-neuronal and sympatho-adrenal activities in man. The influence of beta-receptor blocking agents (author's transl)].
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Determination of both catecholamine concentrations (norepinephrine and epinephrine) and the activity of dopamine-beta-hydroxylase in the plasma of health volunteers and hypertensive patients leads to the conclusion that these parameters used together can be considered an index for sympathetic neuronal activity. However, highly specific and sensitive radiometric methods are necessary for the measurement of these biochemical parameters. In healthy volunteers and hypertensive patients after acute and chronic administration of beta-adrenergic blocking agents, e.g., propranolol, practolol or penbutolol, a significantly higher increase of catecholamine concentrations in the plasma has been observed during physical exercise. This pronounced increase in plasma catecholamine concentrations (mainly norepinephrine) is probably due to an enhanced compensatory sympathetic neuronal activity, accompanied by an increased peripheral resistance; this is obviously necessary in order to maintain a sufficient perfusion of peripheral tissues during work load under the influence of beta-adrenergic blocking agents, since an adequate cardiac output is prohibited by blockade of adrenergic beta-receptors. On the other hand, the pronounced increase in sympathetic tone after beta-blockade, especially after administration of high doses, could be responsible for certain reported side effects, such as hypertensive crisis in psychiatric patients or in patients with phaeochromocytoma.
| 17,416
|
The bacteriology of skin cysts.
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Thirty-nine clinically uninflamed cysts of the three most common varieties, epidermoid cysts, trichilemmal cysts and steatocystoma multiplex were removed under sterile conditions and the contents cultured under aerobic and anaerobic conditions. Seventy-three percent of epidermoid cysts grew significant numbers of organisms whereas none of the trichilemmal cysts did so. The organisms found were the common skin commensals, Staphylococcus epidermidis biotype I, anaerobic Gram positive cocci of the Gaffya type and Corynebacterium acnes Type I. This indicates that cysts which clinically have a punctum, namely epidermoid cysts, may become colonized with surface bacteria under normal circumstances. If they become colonized with pathogenic bacteria they become inflamed, a not uncommon clinical picture. The results from patients with steatocystoma multiplex were difficult to interpret because of the small numbers of patients involved and the unusual clinical appearance they presented.
| 17,428
|
Beta-adrenergic receptor blocking drugs: tear lysozyme and immunological screening for adverse reaction.
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Patients who had received long-term therapy with practolol and other beta-adrenergic receptor blocking drugs were examined ophthalmologically. Tear lysozyme concentration and serum autoantibodies (antinuclear antibodies, DNA-binding antibodies and intercellular cement substance antibodies) were measured. It was found that beta-adrenergic receptor blocking drugs may have a pharmacological effect on the lachrymal glands, but this was not associated with dry eyes or adverse reaction. Practolol was found to be capable of reducing tear lysozyme concentrations to very low levels, and this was initially associated with high titres of ICC antibody. No other drug tested produced these effects.
| 17,431
|
[Study of betacyanin-discolorating enzyme].
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An enzyme catalyzing the discoloration and breakdown of betacyanins was isolated from beet roots Beta vulgaris by centrifugation in sucrose density gradient (2.5 M, 2.0 M, 1.5 M, 1.0 M, tris-HCl buffer, 0.05 M, pH 7.2), and purified 100-fold. The enzyme activity induced the discoloration of betanin, betanidin. It was found that the beet root enzyme exists in an insoluble state and is firmly bound with subcellular structures, which were isolated by centrifugation in sucrose gradient. The optimal activity of the enzyme was observed at pH 3.4, +40 degrees C. The dependence of the enzymatic reaction on the enzyme concentration showed a linearity. Studies of the enzyme inhibition by sodium azide, sodium diethyldithiocarbamate, thiourea, demonstrated that the active site of the enzyme contains a metal. The enzymatic discoloration of betanin is followed by the oxygen uptake.
| 17,435
|
The turnover rate of gamma-aminobutyric acid in the nuclei of telencephalon: implications in the pharmacology of antipsychotics and of a minor tranquilizer.
|
The turnover rate of GABA is measured in substantia nigra, globus pallidus, N. accumbens, and striatum of rats injected with muscimol, a potent GABA agonist, and diazepam. The similarity of action of the two drugs on GABA turnover further supports the theory that diazepam acts as a GABA-mimetic drug. Haloperidol and clozapine affect GABA turnover differently in different nuclei. Haloperidol decreases GABA turnover in caudate but does not affect that in substantia nigra, whereas clozapine increases GABA turnover in both areas. However, both drugs accelerate GABA turnover in globus pallidus and N. accumbens. It is suggested that an increase of GABA turnover and perhaps of GABA release in striatum and substantia nigra may account for the lack of tardive dyskinesia and extrapyramidal side effects of clozapine.
| 17,436
|
Suitability of some enrichment broths and diluents for enumerating cold- and heat-stressed Vibrio parahaemolyticus.
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Vibrio parahaemolyticus cells were injured by chilling and heating, and their recovery was tested in glucose-salt-Teepol broth (GSTB), tryptic soy broth containing 7% NaCl (TSBS), Horie - arabinose - ethyl violet broth (HAEB), and water blue - alizarin yellow broth (WBAY). Exponential phase cells were more sensitive to cold shock than were stationary phase cells. Exposure of chill-injured V. parahaemolyticus to GSTB and TSBS resulted in 70 to 80% death; about 70% lethality was noted for heat-injured cells inoculated into TSBS. Neither HAEB nor WBAY enrichment media were lethal to stressed cells, although rates of growth were retarded. The 3% NaCl in 0.1 M potassium phosphate (pH 7.0) diluent proved to be most suitable for protecting against inactivation of cold- and heat-injured cells.
| 17,461
|
Properties of 1-phosphofructokinase from Pseudomonas putida.
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The 1-phosphofructokinase (1-PFK, EC 2.7.1.56) from Pseudomonas putida was partially purified by a combination of (NH4)2SO4 fractionation and DEAE-Sephadex column chromatography. In its kinetic properties, this enzyme resembled the 1-PFK's from other bacteria. With the substrates fructose-1-phosphate (F-1-P) and adenosine triphosphate (ATP) Michaelis-Menten kinetics were observed, the Km for one substrate being unaffected by a variation in the concentration of the other substrate. At pH 8.0, the Km values for F-1-P and ATP were 1.64 X 10(-4) M and 4.08 X 10(-4) M, respectively. At fixed concentrations of F-1-P and ATP, an increase in the Mg2+ resulted in sigmoidal kinetics. Activity was inhibited by ATP when the ratio of ATP:Mg2+ was greater than 0.5 suggesting that ATP:2 Mg2+ was the substrate and free ATP was inhibitory. Activity of 1-PFK was stimulated by K+ and to a lesser extent by NH4+ and Na+. The reaction rate was unaffected by 2 mM K2HPO4, pyruvate, phosphoenolpyruvate, adenosine monophosphate, adenosine 3',5'-cyclic monophosphate, fructose-6-phosphate, glucose-6-phosphate, 6-phosphogluconate, 2-keto-3-deoxy-6-phosphogluconate, or citrate. The results indicated that the 1-PFK from P. putida was not allosterically regulated by a number of metabolites which may play an important role in the catabolism of D-fructose.
| 17,464
|
Continuous-flow determination of serum inorganic phosphate with a single reagent--the vanadomolybdate method re-evaluated.
|
The merits of the vanadomolybdate method in the determination of inorganic phosphate are highly underestimated with regard to the simplicity of the method and the stability of both the reagents and the color that is formed. The absorption curve of the phosphovanadomolybdate complex, with its maximum at 335 nm, extends into the visible range of the spectrum. This permits measurements with inexpensive tungsten-lamp colorimeters. On-stream dialysis is best done in a nitric acid medium, 0.15 mol/liter. Paralleled by the change in the H2PO4-/H3PO4 ratio, appreciable protein binding and poor dialysis efficiency are seen at lower acid concentrations (pH greater than 1.0). Optimum reaction-mixture concentrations of vanadium and molybdenum appeared to be respectively 0.2 and 5 mmol/liter up to 3 mmol of phosphate per liter, in a final acid medium of 0.2 mol/liter, concentrations considerably lower than those used in some studies published earlier. Color development with the stable combined reagent is complete after only 20 s at room temperature and the color is stable for at least 2 h. Figures on precision and accuracy demonstrate the reliability of the method.
| 17,481
|
Recent developments in the clinical assessment of the metabolism of aromatics by high-performance, reversed-phase chromatography with amperometric detection.
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High-performance liquid chromatography with electrochemical detection has developed into a tool with excellent capability to monitor picomole amounts of individual metabolites in both tissue and body-fluid specimens. Significant technical advances in the area of microparticle chemically-bonded stationary phases have led to dramatic improvements in both sensitivity and resolution. Reversed-phase systems can be modified to include charged exchange sites by addition of detergents to the mobile phase. Adjustment of the surface charge in this manner permits capacity factors for ionic sample components to be increased or decreased. This concept is quite compatible with electrochemical detection and has provided the foundation for several clinical assays now in routine use. Examples of additional applications are presented for the determination of catecholamines in tissue, 3-methoxy-4-hydroxyphenylglycol in urine, and dopamine-beta-hydroxylase activity in human serum.
| 17,485
|
Flow cytometric measurement of peptidases with use of 5-nitrosalicylaldehyde and 4-methoxy-beta-naphthylamine derivatives.
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Enzyme activity can be measured in single cells or in cell suspensions by either static or flow microfluorometry when a fluorogenic substrate is used. We have used amino acid derivatives of arylamines as fluorogenic substrates for tagging cellular proteinases. The liberated aromatic amine, which can diffuse from the cell, is trapped as a fluorescent insoluble Schiff-base product with 5-nitrosalicylaldehyde, with the peak of fluorescence emission shifted from lambdaem 425 nm to lambdaem 530 and 595 nm. Although the reaction is faster at pH 4 than at higher pH's, the equilibrium during the assay of certain peptidase activities is such that the liberated aromatic amine is trapped in the cell at pH values as high as 7.5. 5-Nitrosalicylaldehyde causes almost no inhibition of substrate hydrolysis at 1 mmol/liter, a concentration exceeding that required for complete trapping of reaction product. The kinetics of enzymatic reactions with four synthetic substrates are demonstrated in intact Balb 3T3 cells and sonicated preparations in the presence of 5-nitrosalicylaldehyde. Hydrolytic rates for the substrate, CBZ-ala-arg-arg-4-methoxy-beta-naphthylamine, are given for single 3T3 cells by microfluorophotometry and for suspensions of 3T3 cells by flow cytometry. The clinical value of the method is demonstrated for differentiating mixed populations of leukocytes.
| 17,486
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The ventilatory response in uncomplicated diabetic ketoacidosis.
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The ventilatory response to uncomplicated sub-acute metabolic acidosis was studied by measuring arterial blood CO2 tension (PaCO2) and pH in 27 episodes of diabetic ketoacidosis without coexisting lactic acidosis. From those data, regression equations and 95% confidence bands were calculated for the relations between PaCO2 and pH. These relations were very similar to those previously described by others in patients with chronic uremic acidosis.
| 17,514
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