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The distribution of blood flow to the subendocardial, medium and subepicardial layers of the left ventricular free wall was studied in anaesthetized dogs under normoxic (A), hypoxic (B) conditions and under pharmacologically induced (etafenone) coronary vasodilation (C). Regional myocardial blood flow was determined by means of the particle distribution method. In normoxia a transmural gradient of flow was observed, with the subendocardial layers receiving a significantly higher flow rate compared with the subepicardial layers. In hypoxia induced vasodilation this transmural gradient of flow was persistent. In contrast a marked redistribution of regional flow was observed under pharmacologically induced vasodilation. The transmural gradient decreased. In contrast to some findings these experiments demonstrate that a considerable vasodilatory capacity exists in all layers of the myocardium and can be utilized by drugs. The differences observed for the intramural distribution pattern of flow under hypoxia and drug induced vasodilation support the hypothesis that this pattern reflects corresponding gradients of regional myocardial metabolism. | United Kingdom |
Seven distinct glycosidases (EC 3.2) have been characterized in guinea-pig epidermis. Their properties indicate them to be of lysosomal origin. The 'profile' of the epidermal glycosidases is significantly different from that reported for whole skin, the activities of beta-galactosidase and beta-acetylglucosaminidase being very high and those of the remaining enzymes relatively low in epidermis. | United Kingdom |
1. Based on incorporation of radioactively labeled N-ethylmaleimide, the readily reactive thiol groups of isolated myosin (EC 3.6.1.3) from fast, slow and cardiac muscles could be classified into 3 types. All 3 myosins contain 2 thiol-1, 2 thiol-2 and a variable number of thiol-3 groups per molecule. Both thiol-1 and thiol-2 groups which are essential for functioning of the K+-stimulated ATPase, are located in the heavy chains in all 3 myosin types. 2. The variation in the incorporation pattern of N-ethylmaleimide over the 3 thiol group classes under steady-state conditions of Mg(2+) - ATP hydrolysis allowed different conformations of some reaction intermediates to be characterized. In all 3 types of myosin the hydrolytic cycle of Mg(2+) - ATP was found to be controlled by the same step at 25 degrees C. In all three cases, this rate-limiting step is changed in the same way by lowereing temperature. 3. Using the chemically determined molecular weights for myosin light chains, their stoichiometry was found on the basis of sodium dodecyl sulfate electrophoresis to be 1.2 : 2.1 : 0.8 for light chain-1: light chain-2:light chain-3 per molecule of fast myosin, 2.0 : 1.9 for light chain-1:light chain-2 per molecule of slow myosin and 1.9 : 1.9 for light chain-1:light chain-2 per molecule of cardiac myosin. This qualitative difference in light subunit composition between the fast and the two types of slow myosin is not reflected in the small variations of the characteristics exhibited by the isolated myosins, but rather seems to be connected with their respective myofibrillar ATPase activities. | United Kingdom |
Experiments were conducted on male rats. A study was made of the content of nicotinamide coenzymes in the liver and myocardium 24 hours after the administration of 0.5 ml of dichloroethane into the stomach. In parallel with disturbance of the morphological structure of the liver and of the myocardium, increase in the activity of alanine and aspargic aminotranspherases in the blood serum, dichloroethane reduced the content of nicotinamide coenzymes and deranged the ratio of their oxidized and reduced forms in these organs. | United Kingdom |
(1) Crude synaptosomal fractions (P2) derived from guinea-pig cerebral cortex were incubated in the presence of 50 mM KCl in a Krebs-glucose medium. Torpedo marmorata electric organs were stimulated electrically in vivo at 5 pulses/sec for 30 min by electrodes placed on the electric lobe. Synaptic vesicles were isolated from each source and the phospholipid compositions analysed and compared with vesicles from unstimulated controls. (2) Lysophosphatidylcholine was the only lysophosphoglyceride demonstrable in the synaptic vesicles from either source and its low levels did not increase as a result of chemical or electircal stimulation. In each case there was a close similarity of the phospholipid distributions in the vesicles taken from control and stimulated samples. (3) Control experiments indicated extensive decreases in the acetylcholine content of the vesicles from the stimulated electric organ and smaller decreases in the acetylcholine content of the synaptic vesicles from stimulated crude synaptosomal fractions. These fractions were found to respire linearly in the presence of 10 mM glucose and the vesicle fractions were shown to have low levels of contaiminating membranes as judged by marker enzyme analyses. (4) Crude synaptosomal fractions from guinea-pig cerebral cortex were incubated in a Krebs-glucose medium with labelled fatty acids and [3H]glucose in the presence or absence of 50 mM KCl. Subsynaptosomal fractionation was carried out and specific radioactivities of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol were determined in fractions D (synaptic vesicles), E (microsomes) and H (disrupted synaptosomes). The release of neurotransmitter did not significantly enhance the labelling of phospholipids in any of the fractions studied as compared with phospholipids from unstimulated fractions. This was found after two incubation times and using [14C]oleate, [14C]arachidonate, [3H]palmitate and [3H]glucose. | United Kingdom |
The rate of coronary blood flow was varied in isolated working rat heart preparations to determine its influence on the rate of glocose utilization, tissue high-energy phosphates, and intracellular pH. A 60% reduction in coronary blood flow resulted in a 30% reduction in oxygen consumption, an accelerated rate of glusoe utilization, lower tissue levels of high-energy phosphate, and higher tissue levels of lactate and H+. Ventricular performance deteriorated as reflected by a decrease in heart rate and peak systolic pressure. Further reductions in coronary blood flow resulted in inhibition of glycolysis, a greater decrease in tissue levels of high-energy phosphates, and higher tissue levels of both lactate and H+. These changes in glycolytic flux, tissue metabolites, and ventricular performance were proportional to the degree of restriction in coronary blood flow. The importance of coronary blood flow and washout of the interstitial space in the maintenance of accelerated glycolytic flux in oxygen-deficient hearts is emphasized. It is concluded that acceleration of ATP production from glycolysis can occur only in the marginally ischemic tissue in the peripheral area of tissue supplied by an occluded artery. The central area of tissue which receives a low rate of coronary blood flow will have a reduced rate of ATP production due to both a lack of oxygen and an inhibition of glycolysis. | United Kingdom |
1. We measured the minute ventilation and arterial blood catecholamine concentrations in four normal men standing and at two levels of moderate treadmill exercise breathing 14% oxygen or air. 2. Minute ventilation was significantly higher during hypoxic exercise than during normoxic exercise at an oxygen uptake of 1500 ml/min. 3. Arterial plasma noradrenaline during hypoxic exercise at an oxygen uptake of 1500 ml/min was significantly greater than at rest. 4. Arterial plasma noradrenaline during normoxic exercise at an oxygen uptake of 1500 ml/min was not elevated above the resting concentration. 5. The results are compatible with the suggestion that increased concentrations of arterial plasma noradrenaline contribute to the hypoxic potentiation of the respiratory response to moderate exercise. | United Kingdom |
Some derivatives of isoindoline were prepared in order to test their cardiovascular activity. Pharmacological tests showed that some of the compounds had moderate alpha-blocking and coronarodilatory activity whereas others had some local anesthetic activity. | United Kingdom |
In order to clarify how the electrophoretic behavior reflects the conformational transition of globular proteins, moving boundary electrophoresis was applied to analysis of the acid conformational change of alpha-lactalbumin. The appearance of only a single electrophoretic boundary in the transition region of the protein suggests a very rapid transition with a half-time estimated to be smaller than 7 min on the basis of the theory of isomerizing systems in electrophoresis. The transition is clearly reflected in the dependence of the mobility on the protein net charge, which shows a sigmoidal curve closely similar to that obtained by a Linderstrøm-Lang pH-tritration plot for the carboxyl groups of alpha-lactalbumin. It was also concluded from the transition curves that the acidfication does not result in complete unfolding, but that a compact structure is maintained in the acidic region with an apparently expanded form as compared to the native state of the protein. All results obtained by electrophoresis were also supported by the results of pH-jump studies, analytical gel chromatography, and CD measurements. | United Kingdom |
Reduced coenzyme Q-cytochrome c reductase from bovine heart mitochondria (complex III) was incorporated into phospholipid vesicles by the cholate dialysis procedure. Soybean phospholipids or mixtures of purified phosphatidylcholine, phosphatidylethanolamine, and cardiolipin could be used. Oxidation of reduced coenzyme Q2 by the reconstituted vesicles with cytochrome c as oxidant showed the following energy-coupling phenomena. 1. Protons were translocated outward with a coupling ratio, H+/2e, of 1.9 +/- 0.2. Measurements with mitochondria under similar conditions showed an H+/2e ratio of 1.8. Proton translocation was not seen in the presence of uncoupling agents and was in addition to the net acidification of the medium from the over-all oxidation reaction. 2. Potassium ions were taken up by the reconstituted vesicles in the presence of valinomycin in a reaction coupled to electron transfer. The coupling ratio for K+ uptake, K+/2e, was 2.0 in the vesicles and approximately 1.5 in mitochondria. 3. The rate of oxidation of reduced coenzyme Q2 by the reconstituted vesicles was stimulated up to 10-fold by uncouplers or by valinomycin plus nigericin and K+ ions. Addition of valinomycin alone in a K+ medium caused a transient stimulation of electron transfer. The results indicate that energy coupling can be observed with isolated reduced coenzyme Q-cytochrome c reductase if the enzyme complex is properly incorporated into a phospholipid vesicle. | United Kingdom |
Experiments were carried out to define the kinetic parameters of the major phosphate transport processes of rat liver mitochondria, and to obtain information about the molecular properties of these systems. | United Kingdom |
Peptic and chymotryptic peptides were isolated form the NADP-specific glutamate dehydrogenase of Neurospora crassa and substantially sequenced. Out of 452 residues in the polypeptide chain, 265 were recovered in the peptic and 427 in the chymotryptic peptides. Together with the tryptic peptides [Wootton, J. C., Taylor, J. G., Jackson, A. A., Chambers, G. K. & Fincham, J. R. S. (1975) Biochem. J. 149, 749-755], these establish the complete sequence of the chain, including the acid and amide assignments, except for seven places where overlaps are inadequate. These remaining alignments are deduced from information on the CNBr fragments obtained in another laboratory [Blumenthal, K. M., Moon, K. & Smith, E. L. (1975), J. Biol. Chem. 250, 3644-3654]. Further information has been deposited as Supplementary Publication SUP 50054 (17 pages) with the British Library (Lending Division), Boston Spa, Wetherby, W. Yorkshire LS23 7BQ, U.K., from whom copies may be obtained under the terms given in Biochem. J. (1975) 145, 5. | United Kingdom |
Four distinct peptide hydrolases (EC 3-4) have been characterized in guinea-pig epidermis; these are cathepsin B1, cathepsin C, cathepsin D and arylamidase. Their properties are consistent with those of lysosomal enzymes. Cathepsin E was not detected. | United Kingdom |
The mean PNK activity in red blood cells from black subjects was only about 40% of that in whites. Among 51 whites examined, one was found to have enzyme deficiency. The estimated gene frequencies for PNKH (the common allele in whites which codes for higher enzyme activity) and PNKL (the common allele in blacks which codes for lower enzyme activity) were .35 and .65, respectively, for black donors, and .81 and .19, respectively, for white donors, The variant enzyme in persons with enzyme deficiency was associated with an increased rate of degradation in red cells during aging. No other biochemical or electrophoretic differences were detected. | United Kingdom |
This project involved designing, developing and evaluating a simulation module, utilizing the latent image technique. The general topic chosen for this simulation was the laboratory characterization of anemias. Target learner populations included medical technology students, physician assistant students, and pathology residents. Members of all three groups participated in the evaluation of the module and responded to its use in varied settings. | United Kingdom |
A review of drug treatment for Down's syndrome individuals was presented. Drugs used to modify behavior, as well as drugs used with the goal of affecting cognitive processes, were discussed. Some observations were offered as to the effectiveness of past and current drugs on Down's syndrome and some methodological problems relating to drug studies presented. There have not been any drugs that have demonstrated remarkable improvement in the status of Down's syndrome individuals that have been widely accepted as effective. | United Kingdom |
Using a combined special glass electrode it is possible to monitor pH ratios and pH variation in the subcutaneous tissue of the infant scalp continuously. Tests on a normal sample of newborn babies immediately after birth showed a significant correlation between tissue pH and capillary blood pH, with the trend of pH variation being broadly similar in both measurement media. | United Kingdom |
We conducted a controlled, prospective trial to evaluate the effectiveness of rapidly infusing sodium bicarbonate (NaHCO3) and salt-poor albumin into high-risk, premature infants in the first 2 hours of life. Fifty-three infants, randomized into one of four treatment groups, received 8 ml. per kilogram of a solution containing either (A) glucose in water, (B) salt-poor albumin, (C) NaHCO3, or (D) a combination of albumin and NaHCO3. After the initial infusion, the babies received no colloid or alkali solutions until 4 hours of age. We managed them supportively with warmth, appropriate oxygen administration, isotonic fluid infusion, and close monitoring. Among the infants who received alkali, 14 of 26 acquired the respiratory distress syndrome (RDS), 11 died, and four had intracranial hemorrhage. Among babies who received no alkali, RDS occurred in 11 of 27, 5 died, and none had intracranial hemorrhage. These results do not support the common practice of rapidly infusing NaHCO3 into high-risk, premature infants, and they suggest that the early management of such infants needs renewed critical evaluation. | United Kingdom |
The effects of pH variation on ionic exchange and mechanical function were studied in the arterially perfused rat and rabbit septa. The pH and PCO2 of the control perfusate were 7.40 and 39 mmHg, respectively. In the rabbit septum a metabolic acidosis (pH equals 6.82, PCO2 equals 39 mmHg) caused a loss of 16% of control tension in 12 min. Na+ and K+ exchange were unaltered. A comparable respiratory acidosis (pH equals 6.81, PCO2 equals 159 mmHg) caused a 51% loss of tension in 2 min. Na+ exchange was unaltered but K+ efflux fell from 8.9 +/- 0.6 (mean +/- SE) to 4.9 +/- 0.3 mmol/kg dry wt per min (P less than 0.001, n equals 10). A net gain of K+ of 16.9 +/- 1.7 (n equals 14) mmol/kg dry wt occurred and was attributable to a delayed fall in K+ influx relative to efflux over 15 min. The net gain could not be mimicked by epinephrine administration or blocked by propranolol and was absent in the beating rat septum and the quiescent rabbit septum. These results suggest that the net uptake of K+, which appears to be dependent on a period of depolarization, and the changes of contractility are controlled by the H+ ion concentration at a cellular site whose exchange with the extracellular space is characterized by a considerable restriction of diffusion. Changes of contractility are not related to the net uptake of K+. | United Kingdom |
It has been established that H+ secretion can be maintained in frog stomach in the absence of exogenous CO2 by using a nutrient bathing fluid containing 25 mM H2PO4 (pH approximately equal to 4.5) or by lowering the pH of a nonbuffered nutrient solution to about 3.0-3.6. Exogenous CO2 in the presence of these nutrient solutions uniformly caused a marked decrease in H+ secretion, PD, adn short-circuit current (Isc) and an increase in transmucosal resistance (R). Elevation of nutrient [k+] to 83 mM reduced R significantly but transiently without change in H+ when nutrient pH less than 5.0, whereas R returned to base line and H+ increased when nutrient pH greater than 5.0. Acidification of the nutrient medium in the presence of exogenous CO2 results in inhibition of the secretory pump, probably by decreasing intracellular pH, and also interferes with conductance at the nutrient membrane. Removal of exogenous CO2 from standard bicarbonate nutrient solution reduced by 50% the H+, PD, and Isc without change in R; K+-free nutrient solutions reverse these changes in Isc and PD but not in H+. The dropping PD and rising R induced by K+-free nutrient solutions in 5% CO2 - 95% O2 are returned toward normal by 100% O2. Our findings support an important role for exogenous CO2 in maintaining normal acid-base balance in frog mucosa by acting as an acidifying agent. | United Kingdom |
A method of isolation of alpha-1-antitrypsin (alpha-1-AT) in good yield from normal human plasma is described. A key step was affinity chromatography employing an antiserum which had been depleted of alpha-1-AT antibodies. The final preparations were homogeneous by immunological and physicochemical criteria. The specific activity of the purified alpha-1-AT was 0.363 mg of active bovine trypsin inhibited per 1.0 mg of inhibitor. Polyacrylamide gel patterns at both alkaline and acid pH of highly pure preparations frequently, but not invariably, showed multiple hands. Molecular weight studies by sedimentation equilibrium ultracentrifugation in aqueous buffer and in 6 M guanidine as well as sodium dodecyl sulfate polyacrylamide gel electrophoresis suggest that alpha-1-AT is a single polypeptide chain having a molecular weight of 49,500. Other physical and chemical properties of the inhibitor are described. A limited N-terminal sequence (Glu-Asp-Pro-Gln-Gly-Asx-Ala-Ala) was obtained. It was found that alpha-1-AT easily forms polymers and higher aggregates when exposed to denaturing agents such as 8 M urea and 6 M guanidine. The results suggest that aggregation is determined by both covalent and noncovalent forces. | US |
Highly purified L-asparaginase having a specific activity of 500+/- +/-40 IU./mg protein is isolated from Pseudomonas fluorescens AG cells. The purification procedure includes isopropanol fractionation, gel filtration through Sephadex G-100, chromatography on hydroxylapatite and DEAE-cellulose columns. The asparaginase preparation is homogenous on the basis of polyacrylamide gel electrophoresis data. The pH optimum is found to be 8.0-9.0, isoelectric point and molecular weight are 4.5+/-0.05 and 70,000+/-5,000 respectively, Km for L-asparagine being-4.1-10(-4)M. The enzyme does not hydrolyse L-glutamine. The hydrolysis rate of D-glutamine is less than 1% of the deamydation rate of L-isomer. p-Chloro-mercurium benzoate at a concentration of 10(-4) M completely inhibits the asparaginase activity. Asparaginase from Ps. fluorescens AG possesses and antileucosic activity, inhibiting 3H-thymidine incorporation into DNA of Berkit lymphoma cells. | United Kingdom |
A method for assessing the binding of 3H-labeled prostaglandin E1 ([3H]PGE1) to cell membranes has been developed and used to study the interaction of [3H]PGE1 with membranes from cultured mammalian cells. Receptor sites were identified by correlation of the potency of a series of compounds to compete for [3H]PGE1 binding sites and to stimulate adenylate cyclase activity, by correlation of rates of binding and change in enzyme activity, and by the correspondence of [3H]PGE1-binding activity with the presence or absence of PGE1-sensitive adenylate cyclase in several clones. In clone B82, a murine L-cell, [3H]PGE1 binds with an activation energy of 14 kcal/mol to a class of sites with an affinity of 0.5 X 10(8) M-1 and a capacity of 150 fmol/mg of protein. Concentration dependence of adenylate cyclase activation by PGE1 (KD =30 nM) and kinetic analysis of [3H]PGE1 binding (k1 = 4 X 10(6) liters/mol/min, k-1 0.15/min) verify this affinity. Concentration dependence and specificity of binding and activation of adenylate cyclases in neuroblastoma clone N4TG1 and N18TG2 substantiate the method. In several clones that lack PGE1-responsive adenylate cyclase, no specific [3H]PGE1 binding is detectable. | US |
Urticaria is a problem often as vexing to the physician as to the patient. The approach to the patient with hives first demands a search for the etiology, whether endogenous and triggered by emotions or occult systemic disease, exogenous and triggered by allergy to inhaled or ingested antigens, or physical and due to abnormal sensitivity to heat, cold, light, or pressure. Often a fruitless search, the diagnostic evaluation must be accompanied by appropriate symptomatic therapy requiring familiarity with the antihistamines and their relative advantages in the various forms of urticaria. Elimination diets are of diagnostic as well as therapeutic value: pencillin-free, yeast-free, and salicylate-free diets are particularly useful. Therapeutic trials of tetracycline, nystatin and griseofulvin may be helpful, while corticosteroids and specific desensitization are rarely of value. | United Kingdom |
We have studied the mechanism of the specific inhibition of ribosomal RNA synthesis by ppGpp in a purified system using as templates E. coli DNA and DNA from lambdad5ilv, which carries a rRNA cistron from E. coli. Ribosomal RNA synthesis, as well as its inhibition by ppGpp, are critically salt-dependent. Of a number of guanosine phosphates tested, only pppGpp (MS II) mimicked the action of ppGpp, establishing the specificity of ppGpp. The two templates gave similar results for rRNA synthesis in all experiments. By using the initiation inhibitor rifampicin, we could show that the specific inhibition of rRNA synthesis by ppGpp is due to its effect on rRNA initiation. The somewhat variable inhibition of RNA synthesis in general by ppGpp is mainly or wholly a consequence of premature chain termination. We propose that ppGpp specifically inhibits rRNA synthesis by acting on the formation of the so-called "closed-promoter complex". | United Kingdom |
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. | United Kingdom |
The activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase, EC 1.1.1.34) has been demonstrated both in homogenates and microsomes of the S3G strain of HeLa cells. It was increased 8- to 10-fold by the removal of serum from the growth medium. The presence of steroids, specifically of the glucocorticoid series, in the serum-less growth medium elicited an additional 100 to 345% increase over the serum-less control, whereas the addition of N6,O2'-dibutyryl adenosine 3':5'-monophosphate to the medium or dexamethasone to the assay mixture was without any stimulatory effect. Both inductions were blocked by cycloheximide and actinomycin D, suggesting a protein synthesis-dependent elevation of enzyme activity. Glucocorticoids were effective in the induction at concentrations ranging from 10(-6) to 10(-8) M and there was a demonstrated parallel between the magnitude of enzyme induction and glucocorticoid potency. The HMG-CoA reductase activities from steroid-induced and control cultures had identical assay characteristics (pH optima and apparent Km values for both NADPH and HMG-CoA). This induction of the rate-controlling enzyme of cholesterogenesis occurred despite the observation that glucocorticoids specifically depress the rate of acetate or water, but not mevalonate, incorporation into cholesterol. | United Kingdom |
The central hypotensive action of clonidine, infused into the vertebral artery of chloralose-anaesthetized cats was antagonized by several phenothiazine-neuroleptics (chlorpromazine, promazine, promethazine, thiethylperazine, thioridazine), by chlorprothixene and to a limited extent by haloperidol administered via the same route. Pimozide and some benzodiazepines (chlordiazepoxide, diazepam and flurazepam) hardly influenced the central hypotensive response to clonidine. The antagonism between clonidine and the psychotropic drugs is probably associated with central alpha-adrenoceptors, clonidine being the agonist and the neuroleptic agents the antagonists at these receptors. Virtually the same type of antagonism was observed in conscious, spontaneously hypertensive rats where both clonidine and the neuroleptic drugs were injected intravenously. The phenothiazines and also piperoxane effectively diminished the centrally induced hypotensive response to clonidine, whereas the initial pressor effect to clonidine was not reduced. | United Kingdom |
The adenylate energy charge of human ejaculated spermatozoa was studied when the sperm motility was perturbed by varying pH, prolonged incubation, and caffeine. Between pH 8 and 9, which was optimal for the sperm motility, the energy charge was in the physiological range of 0.8 to 0.9. Above pH 9, the mobility, ATP content, and adenine nucleotide pool declined rapidly but the energy charge was maintained slightly below 0.8. Below pH 8, the motility also dropped drastically, but the ATP, nucleotide pool, and energy charge fell only slightly. Prolonged incubations of the spermatozoa decreased the motility, ATP, and nucleotide pool. However, the energy charge would remain above 0.6. Caffeine stimulation of the motility caused a rapid fall of ATP and the reduction of the physiological energy charge by 0.2 unit, unless glucose was added. Imidazole which reduced the caffeine-stimulated motility did not alter the physiological energy charge of the spermatozoa. The study showed that the spermatozoa could maintain the energy charge above 0.6 under stress. | United Kingdom |
The pH effect on the nisine biosynthesis during the cultivation of Streptococcus lactis was studied at pH 5,8 6,7 and 7,2. The pH maintenance at the specified level did not stimulate the growth of Str. lactis, did not increase the total yield of nisine and did not produce a significant effect on the level or cellular nisine. This indicates an important physiological difference between the culture-nisine producer described by Hirsh and our culture Str. lactis, str. Moscow University. | United Kingdom |
The effect of copper ions and unfavourable pH values of the medium on the incorporation of labelled precursors of protein and RNA was studied in Candida utilis. Specific inhibition of protein synthesis by copper ions and alkaline conditions was found. No specific inhibition of protein or RNA was detected at low pH values of the medium. | United Kingdom |
Glutamine-dependent CPSase, ATCase, and DHOase from Drosophila, the first three enzymes in pyrimidine biosynthesis, show coordinate variation in activity throughout development. The three activities were highest in first instar larvae and decreased as development proceeded. The three activities cosediment in sucrose gradients as a single peak with a relative sedimentation coefficient of approximately 30S. CPSase, ATCase, and DHOase copurify during (NH4)2SO4 fractionation and during DEAE-cellulose and hydroxylapatite chromatography. | United Kingdom |
The acyl-carrier protein (ACP) of Escherichia coli is a protein of molecular weight 8847 with a 4'-phosphopanthetheine prosthetic group. ACP functions (via the SH of the prosthetic group) as a coenzyme in the synthesis of fatty acids and complex lipids. We report proton nuclear magnetic resonance (NMR) studies of the structure of ACP under various experimental conditions. The motion of the fatty acyl chain of acyl-ACP has been investigated by 19FNMR studies of difluorotetradecanoyl-ACP. 31PNMR studies of the prosthetic group phosphorus of ACP and acyl-ACP are also reported. We make the following conclusions: (1) the structure of ACP is stabilized by surface charge, and (2) the fatty acid residue of acyl-ACP does not move freely and seems immobilized by an interaction with the protein moiety. | US |
The axial projection of the glutamine synthetase molecule has been reconstructed from electron micrographs of a stained preparation by using a new method of correlation search and averaging. The average over 50 individual molecules appears as a radial pattern with sixfold symmetry. The handedness evident in the average is attributed to nonuniformity of the negative stain. | US |
A simple, reproducible and quantitative method for evaluating certain non-specific immunological inhibitors in a variety of biological fluids is described. Human lymphocytes were stimulated with PHA in the presence of colchicine. Phytohaemagglutinin stimulated a large percentage of cells and colchicine's selective blockage of mitosis limited the stimulated cells to one S phase. These conditions effectively established a maximum amount of DNA synthesis within each culture. Quantification of suppression was then achieved by measuring a decrease from this maximum. The PHA-colchicine assay was successfully used to quantify inhibition by normal plasma, normal mouse sera, mouse neonate sera, murine Ehrlich's and sarcoma I ascitic fluids and an immunoregulatory alpha-globulin peptide preparation. Because of the ability to obtain a specific inhibitory activity for the suppressive factors, this assay was particularly suited for following the isolation of inhibitors during the fractionation of suppressive substances from complex fluids. | US |
Benzodiazepine derivatives are the most commonly prescribed anti-anxiety agents in clinical practice. Six benzodiazepine anxiolytics are now available in the United States. Additional drugs are used in other parts of the world, and many others are in various stages of clinical testing. All these benzodiazepine derivatives have similar neuropharmacological properties--they reduce anxiety, produce sedation and sleep, have anticonvulsant effects, and can produce muscle relaxation. Faced with this bewildering array of drugs from the same class which are very similar in intrinsic effects upon the brain, the clinician may well ask how best to make a rational choice among the available derivatives. Despite neuropharmacological similarities, there are differences among benzodiazepines in patterns of absorption, distribution, and elimination by the human body. These pharmacokinetic differences may in turn lead to apparent differences in clinical action. This review summarizes pertinent pharmacokinetic characteristics of benzodiazepine anti-anxiety agents. | US |
The awareness of extrapyramidal reactions during initiation of neuroleptic treatment was studied in 14 patients. Only one patient spontaneously identified the presence of dystonia. The other 13, including 3 who had experienced extrapyramidal reactions during previous hospitalizations, did not fully identify the presence of symptoms, although several had vague discomfort. There was marked variability in acknowledgement of symptoms in response to prompting by staff members. The findings are similar to reports of agnosia for hemiparesis after parietal lobe injury and also to descriptions of agnosia in animals caused by destruction of dopaminergic neurons. Since extrapyramidal reactions represent blockade of dopaminergic neurotransmission, patients' inability to perceive the reactions may represent evidence for catecholaminergic modulation of sensory perception. | US |
Neuroendocrine studies that examine the changes in serum prolactin levels following intramuscular (im) neuroleptics have usually monitored prolactin levels before and for 90 minutes to 3 hours after neuroleptic injection. Recent studies have suggested that this may be an inadequate period of time. In the present study, six male and four female psychiatric inpatients, who had not received neuroleptic medication for at least 1 week before the study began, received an injection of chlorpromazine (CPZ) 25 mg im; serum prolactin levels were monitored for 6 hours after injection. Peak serum prolactin levels occurred at 60 minutes in one subject, 90 minutes in three subjects, 120 minutes in two subjects, 180 minutes in three subjects, and 240 minutes in one subject. Area under the serum prolactin curve at 2 hours and area under the curve at 3 hours after CPZ injection were found to be good predictors (r = 0.86; r = 0.95, respectively) of 6-hour area under the curve. Two-hour studies should therefore not be considered inadequate; however, a 3-hour study length results in more precise characterization of prolactin response to im CPZ. | US |
Chlorpromazine and thioridazine are widely used antipsychotic agents that are extensively metabolized. Parent compounds and metabolites have diverse pharmacologic activities, and differences in patterns of metabolism may explain differences in therapeutic and side effects from individual to individual. Radioreceptor assays were used to determine the neuroleptic, antimuscarinic, and anti-alpha-noradrenergic potency of chlorpromazine, thioridazine, and their metabolites. The results indicate that these metabolites show a wide range of potencies. The spectrum of activity of a metabolite may be quite different from that of its parent compound. The clinical relevance of these findings to individual differences in drug response is discussed. The combined use of radioreceptor assays and chemical assays in future clinical research is proposed. | US |
We have isolated temperature resistant revertants from temperature sensitive E. coli strains containing either a thermolabile glutaminyl-tRNA synthetase or leucyl-tRNA synthetase. Among the revertants which still contained the thermolabile leucyl-tRNA synthetase we found two classes of regulatory mutants (leuX and leu Y) which have elevated levels of this enzyme. The leuX mutation specifies an operator-promoter region adjacent to the structural gene (leuS) for the enzyme. The leuY gene maps away from the leuS gene and codes for a protein. Using these mutants we demonstrated that the levels of leucyl-tRNA are related to the derepression of the leucine and isoleucine-valine operons. Among the revertants which still contained the thermolabile glutaminyl-tRNA synthetase were characterized three classes of mutants, glnT, glnU, and glnR. The glnT and glnU mutants contain elevated levels of tRNAgln, while the glnR mutant possesses elevated levels of glutaminyl-tRNA synthetase. The level of glutamine synthetase, the enzyme responsible for the formation of glutamine, is also derepressed in the glnT and glnR mutants. | US |
As a function of buffer pH, [125I]-insulin binding to rat mammary cells, rat adipocytes, or membranes prepared therefrom, at 4 degrees or 20 degrees C, showed 2 peaks in different buffers. Specific insulin binding at the pH 7.7. peak (100 +/- 11%) was lower than at pH 8.8 (140 +/- 17%) with no change in nonspecific binding. Although insulin stimulation of glucose uptake into fat cells was highest at pH 7.5, this response was also seen at pH 8.6. Scatchard affinity profiles, or in the kinetics of dissociation. Insulin degradation (< 10%) and binding to insulin antibody were similar over the pH range of 7 to 9. | US |
Bicarbonate was found to stimulate ATP breakdown by rabbit or cat ciliary body-iris homogenates. Maximum HCO3- stimulation of ATPase with Tris-Hepes buffer occured at pH 8.0. Acid pH and chloride ions in the media reduced the activity of the HCO3--stimulated ATPase. The Km for ATP was 0.55 mmolar and for HCO3-, 20 mmlar. HCO3- ATPase was not inhibited by acetazolamide added to in vitro. It is postulated that ATPase represents the linkage step of energy donor mechanism and active CT secretion in acid aqueous humors (human, cat.) or HCO3- secretion in alkaline aqueous humor (rabbit, guinea pig). Inhibition of Cl- or HCO3- secretion by acetazolamide results from decreased intracellular HCO3- levels which, in turn, reduces the stimulation of the HCO3- ATPase. | US |
The relative contribution of the renin-angiotensin system, adenocorticotrophic hormone (ACTH) and plasma electrolytes in the response of plasma aldosterone to 30 minutes of 65 degrees head-up tilt was assessed in 10 essential hypertensive patients. Studies were carried out before and during acute blockade of renin release by propranolol, ACTH suppression by dexamethasone and combined renin and ACTH blockade. In control studies orthostasis induced significant increases only in plasma renin activity and aldosterone. In contrast, when the renin response to tilt was acutely suppressed by propranolol administration, the aldosterone response was nonetheless maintained but now appeared to be under ACTH control, since concurrent increases in cortisol were observed. During ACTH suppression aldosterone increased during tilt and so did renin. However, during combined ACTH and renin blockade aldosterone failed to increase during tilt. These studies suggest that the aldosterone secretory response to head-up tilt is normally mediated by the renin-angiotensin system but, when the renin response is suppressed, an ACTH response is elicited which assumes a backup role. However, when these two systems are blocked other factors appear unable to respond during tilt to support a normal aldosterone response. | US |
Pulmonary mixed function oxidations are altered by in vivo exposure to paraquat or ozone. The cytochrome P-450-mediated benzphetamine N-demethylase activity was inhibited by low doses of both oxidants (paraquat, 20 mg/kg, ip; ozone, 1 ppm, 24 hrs). The effect of paraquat did not appear until 4 days after treatment and was still apparent after 2 weeks. The inhibition following exposure to ozone appeared immediately (1 day) and had resolved by one week. Cytochrome b5-mediated lipid desaturation was unaffected by the paraquat treatment and was stimulated by ozone. These alterations in pulmonary mixed function oxidase activities could not be explained by microsomal lipid peroxidation. The concentrations of cytochromes P450 and b5 also did not accurately reflect the altered enzymatic activities. The sites of the paraquat- and ozone-mediated alterations are still unknown. | US |
The circadian rhythms of sucrase, maltase, isomaltase, trehalase, lactase, gamma-glutamyltransferase, leucylnaphthylamide hydrolyzing activity, alkaline phosphatase and monosaccharide transport were assessed in each fifth of the small intestine of the rat in order to determine if an entire enzyme or transport system population responded in a similar manner or if there were regional differences. Animals were maintained under a light-dark cycle and fed from 1400-1800, EST for 7 days. Functional activities were assessed every 4 h for 24 h, inclusively. Quantitative, and in a few instances, qualitative differences in different areas of the intestine were found for all functions. There were portions of the lactase and alkaline phosphatase populations which displayed no rhythmicity in activity. When rhythmicity was observed there were differences in the activity patterns along the intestine for all functions. Thus, the rhythm patterns obtained from homogenates of the entire small intestine are a composite of the patterns in regions of high average activity. Also, there appears to be a reasonable amount of local control of the various functions. | US |
The fluorescence parameters of ethenoadenosine derivatives are influenced by metal cations and pH, as summarized here. The pH profile of ethenoadenosine determined by fluorescence intensity gives a normal titration curve and is not affected by ionic strength. In contrast, the pH titration curves of etheno-ATP, etheno ADP, and etheno AMP depend upon ionic strength. At high ionic strength normal curves are obtained, whereas at low ionic strength anomalies are obtained; this suggests that the phosphates can interact with the ring, possibly by hydrogen binding to the ring nitrogens. The room temperature fluorescence of ethenoadenosine occurs from the base form, although excitation of either the acid or base forms can contribute to the emission. This result can be explained if the excited state pK is lower than the ground state pK, and if deprotonation occurs within the time scale of the excited state. At low pH values the fluorescence lifetime of the base form is dependent upon the buffer concentration, indicating that the reverse reaction, protonation, occurs. The affinity constants for the binding of metals to the ethenoadenosine phosphates resemble those for the corresponding adenosine phosphates. Ni(II) and Co(II) are more effective than Mn(II) in quenching the fluorescence of ethenoadenosine phosphates; this result is predicted by Förster's theory for energy transfer based upon the overlap between donor emission spectrum and acceptor absorption spectrum. The diamagnetic ions Mg(II), Ca(II), and Zn(II) do not appear to affect the fluorescence of the ethenoadenosine phosphates directly, but rather to affect the conformation of the molecule, thereby affecting the quantum yield. | US |
A quasi-short-circuit (tunable voltage clamp) measurement method with microsecond time resolution was applied to a bacteriorhodopsin model membrane formed by a novel interfacial technique. A new component (B1) of the displacement photocurrent was recorded: it has no detectable latency at an instrumental time constant of 1.5 museconds, and persists at 5 degrees C. In addition, a slower component (B2) of opposite polarity inhibited by low temperature (5 degrees C) and low pH (pH = 3.0) was recorded. The technique is very sensitive for the study of fast capacitative photoresponses in model membranes, and allows the detection of charge displacements in bacteriorhodopsin associated with distinct stages of the photochemical transformation. | US |
The effects of low pH, and of alkaline earth cations, were examined on calcium uptake by pinched-off nerve terminals (synaptosomes). This uptake appears to be mediated by voltage-sensitive Ca channels (J. Physiol. 247:617, 1975). Ca uptake was measured in low (5 mM) or high (77 mM) potassium media. The extra uptake promoted by depolarizing (K-rich) media was almost maximal at pH 7.5, and decreased as the pH was lowered. Data relating depolarization-induced 45Ca uptake to pH fit a titration curve with a pKa approximately 6. Experiments in which Ca concentration and pH were both varied indicated that Ca2+ and H+ compete for a common binding site. Inhibition of depolarization-induced 45Ca uptake by the alkaline earth cations was studied to determine the apparent binding sequence for these cations in the Ca channels: Ca greater than Sr greater than Ba greater than Mg. This sequence resembles that observed for block of Ca channels in other preparations. The apparent binding sequence of the alkaline earth cations and the apparent pKa (approximately 6) of the Ca-binding site indicate that the Ca channel is a "high field strength" system. Protonation of a Ca channel binding site could explain the inhibitory effect of low pH on Ca-dependent neurotransmitter release (cf. Del Castillo et al., J. Cell. Comp. Physiol. 59:35, 1962). | US |
Lipid bilayer permeation coefficients for the neutral maleic acid molecule and the maleate monoanion have been determined by proton magnetic resonance techniques. Phosphatiydylcholine-cholesterol (2:1) unilamellar vesicles were prepared having an initial maleate anion concentration gradient stabilized by coupling to an impermeant potassium counterion. The coupling was released by addition of valinomycin, and the time evolution of external pH, internal pH, and maleate concentration followed using nuclear magnetic resonance areas and chemical shifts. Transport rate equations were numerically integrated to fit the date, yielding best fit permeation coefficients of 4 X 10(-9) and 4 X 10(-5) cm/s for maleate monoanion and maleic acid, respectively. | US |
The viscoelastic behavior of rat 9L cellular DNA was studied as a function of the detergent used for lysis, the pH and duration of lysis, and gamma ray dose. For nondenaturing lysis conditions, a model of the DNA was proposed to account for the effects of these agents on the viscoelastic retardation time. It was concluded that these agents affect the hydrodynamic radius of the DNA rather than its molecular weight. For denaturing lysis conditions, molecular weights calculated from the relaxation time were consistent with those calculated from alkaline sucrose sedimentation profiles. | US |
The Hodgkin-Huxley kinetic parameters, alpha h and beta h, which govern the rate of recovery from and development of sodium channel inactivation, respectively, have been measured as a function of membrane potential and external pH using a three-pulse protocol. alpha h but not beta h is substantially accelerated by reducing external pH from 7.4 to 6.4. The alpha h vs. voltage curve appears to be selectively shifted in the depolarizing direction by approximately 12 mV for this pH change, giving an apparent, h infinity curve shift of approximately 6 mV in the same direction (less inactivation). | US |
Recent evidence suggests that of calcitonin (CT) and parathyroid hormone (PTH) is controlled by factors other than the ambient serum calcium concentration. We studied the effects of infusions of four neuroendocrine modulators upon CT and PTH levels: isoproterenol (beta-adrenergic agonist), methoxamine (alpha adrenergic agonist), prostaglandin E2, and somatostatin. Isoproterenol was a consistent secretagogue for both hormones. Maximal CT increments during isoproterenol infusion in normal subjects were 13 +/- 2 pg/ml (mean +/- SEM, n = 6, P less than 0.001; basal, 26 +/- 5). Maximal increments in PTH were 113 +/- 22 pg/ml (P less than 0.01, n = 6; basal, 430 +/- 11). Infusions of methoxamine increased CT by 13 +/- 5 pg/ml (n = 5, P less than 0.05; basal, 43 +/- 13), but had no effect on PTH. The means of the maximal CT increments during isoproterenol (21 +/- 8 pg/ml) and methoxamine infusion (28 +/- 11 pg/ml) were not statistically different from those achieved by acute elevations of serum calcium levels within the physiological range (41 +/- 23 pg/ml). Infusions of somatostatin and prostaglandin E2 had no or only transient effects on basal or stimulated CT or PTH levels. Our data suggest that adrenergic input modulates CT and PTH secretion in humans independently of changes in serum calcium. | US |
In human placental explants cultured in vitro, dopamine inhibited human chorionic somatomammotropin (hCS) secretion into the culture media. In the control flasks, the level of hCS secretion was 130.5 +/- 7.8 micrograms/g tissue (n = 6). When 1 mM dopamine was added, hCS levels decreased to 80.2 +/- 11.5 micrograms/g tissue (P less than 0.01). Dopamine (5 and 10 mM) further lowered hCS levels. In contrast, 1 mM pimozide enhanced hCS secretion by 2-fold as compared to control levels (248.2 +/- 44.8 vs. 130.5 +/- 7.8, P less than 0.02). The simultaneous addition of dopamine did not alter the stimulatory effect of pimozide on hCS secretion. In separate experiments, arginine (1 and 5 mM) and somatostatin (1 microgram/ml culture media) did not alter hCS secretion from placental explants. These results suggest that hCS secretion is modulated by dopaminergic receptors. | US |
The zoological specificity of human thyroid-stimulating antibody (TSAb) that occurs in the blood in Graves' disease was examined by assessing its effect on the thyroid of the dog, guinea pig, calf, and mouse as well as that of man. With all but murine glands, thyroid stimulation was assayed by measuring the increase in the concentration of cAMP in the thyroid slices or fragments after 2 h of incubation in buffer containing TSAb. Effects on the thyroid of the mouse were monitored by the in vivo bioassay for LATS. Sera from 33 patients with Graves' disease were obtained and concentrates of TSAb were prepared by precipitation of IgG with 1.64 M (NH4)2SO4. These all stimulated the human thyroid, 13 were LATS-positive, and they variably affected the tissues of other species; of 27 tested, 14 stimulated the thyroid of the dog, 8 out of 23 stimulated the thyroid of the guinea pig, and 12 out of 16 stimulated the gland of the calf. The more potent the TSAb as assayed with human tissue, the more likely was it to stimulate other species of thyroid; however, frequent exceptions occurred. In a separate analysis of 35 LATS-positive preparations of TSAb, correlation between the responses in the LATS and human thyroid slice assays was statistically significant (P less than 0.001). The data are compatible with the view that stimulation by TSAb of nonhuman thyroids, including the murine as in the LATS bioassay, reflects cross-reaction of this immunoglobulin with an antigen that has sufficient similarity to the human molecule to be recognized by the human antibody. | US |
To determine if the adrenergic nervous system, and specifically tyrosine hydroxylase, plays a role in the extrathyroidal conversion of T4 to T3, normal male volunteers were treated with T4 and subsequently with T4 and alpha-methyl-p-tyrosine (alpha-MPT), an inhibitor of tyrosine hydroxylase, for 2 weeks. The mean serum T4 and T3 concentrations increased during T4 administration and remained at the same levels during combined T4 and alpha-MPT administration. Urinary vanillylmandelic acid excretion declined significantly during alpha-MPT administration. These results do not support the hypothesis that tyrosine hydroxylase is involved in extrathyroidal T3 production. | US |
Normal human plasma contains "inactive renin," whose ability to generate angiotensin I increases after exposure to pH 3.3. Big renin is a partially inactive enzyme of larger molecular weight, which is also activated at pH 3.3, and is found of pregnant women, and in amniotic fluid, but not in normal plasma. We have compared the effects of acid exposure and storage at 4 and -4 C on normal plasma and plasma containing big renin. The concentration of inactive renin in normal plasma was approximately equal to that of normal active renin, and its activity increased slowly on prolonged standing at -4 but not 4 C. In contrast, the activity of big renin increased by 50% as early as 1-3 days at 4 C and increased even more quickly at -4 C. Acid treatment of plasma containing big renin caused 4-10 times greater increase in active renin than similar treatment of normal plasma. During gel filtration, both cold-activated and previously acidified big renin coeluted with unactivated big renin. These data indicate that big renin is highly susceptible to cold or acid activation and that such activation of big renin does not result in a detectable decrease in its molecular weight of 60,000 daltons. Furthermore, acid and cold seem to activate the same pool of inactive renin in normal plasma. Although both normal and big renin are stable for long periods below -20 C, a serious overestimate of plasma renin activity can occur if plasma is stored just above its freezing point before assay. | US |
Plasma PRL was measured at 20-min intervals in six patients with Parkinson's disease under various treatment protocols. In addition, 24-h mean GH levels were measured. The results of these studies showed that two untreated patients with Parkinson's disease had normal 24-h mean PRL levels with the normal increase during sleep. During chronic treatment with L-dopa-carbidopa (Sinemet), the 24-h PRL level was 12.8 +/- 4.9 ng/ml (mean +/- SD) and there was persistence of augmented PRL secretion during sleep. The 24-h mean GH level ranged from 1.5-4.4 ng/ml, with a mean of 2.5 ng/ml. The addition of a dopamine agonist (Lergotrile mesylate) resulted in a significant (P less than 0.01) suppression of the 24-h mean PRL levels and abolition of the normal sleep augmentation after 2 weeks of therapy. This suppression was maintained in one patient who was restudied 4 months after the addition of dopamine agonist therapy to L-dopa-carbidopa. The 24-h mean GH levels did not change significantly after the addition of the dopamine agonist when compared to L-dopa-carbidopa alone. These results suggest a dichotomy between the PRL and GH responses to combined L-dopa-carbidopa and dopamine agonist therapy. In addition, the preservation of normal PRL regulation in the two untreated patients with Parkinson's disease suggests that dopaminergic neurons are not universally affected in this disorder. | US |
The effect of somatostatin (SRIF) on human chorionic somatomammotropin (hCS) secretion was studied in human placental explants cultured in vitro. In the experimental flasks, SRIF was added in a concentration of 10, 100, and 1000 ng/ml media; hCS levels measured by RIA were not different from those found in the control flasks. In separate experiments, we investigated the action of SRIF on hCG secretion by a human malignant choriocarcinoma cell line maintained in tissue culture. SRIF (1000 ng/ml) did not inhibit basal or dibutyryl cAMP-induced stimulation of hCG secretion. These results suggest that somatostatin does not suppress hCS or hCG release in vitro from normal or malignant trophoblast, respectively. | US |
The rise and subsequent return to basal of glucose production (Ra) during a constant glucagon infusion ("downregulation") has suggested to some workers that glucagon's effects are evanescent. To examine whether glucagon displays persistent biological activity even after downregulation, 6 healthy males received an 8 hour infusion of somatostatin and glucagon, with 3H-3-glucose to measure glucose turnover. Ra rose from 2.8 +/- 0.3 to 4.2 +/- 0.3 mg/kg . min at 90 minutes, returned to basal levels at 150 minutes, and remained at this level for the ensuing 330 minutes. Six additional subjects received an 8 hour somatostatin infusion, with glucagon administered concomitantly for the first 5 hours. Glucagon withdrawal at 5 hours produced an immediate decline in Ra from 1.8 +/- 0.2 to 0.9 +/- 0.2 mg/kg . min. Thus, even after downregulation the maintenance of basal Ra is dependent on circulating glucagon. | US |
We used a modification of the TSH radioreceptor assay to detect TSH-binding inhibition (TBI) activity in serum and serum fractions from normal subjects and patients with Graves' disease. TBI activity is present in normal IgG prepared by DEAE-Sephadex chromatography and in normal globulins prepared by precipitation at 1.6 M ammonium sulfate. Other normal serum proteins also had TBI activity when large concentrations were tested. Gel filtration chromatography and powder block electrophoresis were used to prepare fractions of normal and Graves' disease sera. In these fractions from normal serum. TBI activity was found in both gamma-globulin and alpha-globulin-albumin fractions electrophoretically and in both 7S and 4S peaks from gel filtration. TBI activity from Graves' disease patients' sera was similarly distributed, but relatively more TBI accompanied the electrophoretic gamma-globulins. Sepharose Protein-A and anti-IgG were used as immunoabsorbents to isolate and purify IgG from normal and Graves' disease sera. TBI activity in IgG was proportional to the IgG concentration, indicating that the TBI which migrates as a gamma-globulin electrophoretically is an IgG and thus may possibly be an antibody. Inhibitory activity found in normal serum globulins and the non-IgG fractions of both normal and abnormal sera seriously interferes with attempts to use the TSH radioreceptor assay to study the hypothesized anti-TSH, receptor antibody in the serum of patients with Graves' disease. | US |
Intensive laboratory investigation of patients with recurrent infections, and with infections with microbial species not usually considered to be pathogenic, have led to the identification of several defects in granulocyte function. The two functions of granulocytes which have received most attention in the past decade have been locomotion (especially response to chemotactic stimulation) and microbicidal activity. Defective granulocyte chemotaxis has been demonstrated in patients with clinical manifestations suggesting abnormalities related to vasoactive amines, i.e., patients with eczema and extreme IgE hyperimmunoglobulinemia. The depressed granulocyte chemotactic responsiveness found in these patients can be reproduced in vitro when histamine and beta adrenergic agents are incubated with control granulocytes. Since these compounds have been shown to increase levels of intracellular cyclic AMP in other cells, there appears to be an association between cyclic nucleotide metabolism and regulation of granulocyte locomotion. Defective granulocyte microbicidal activity is found in patients with chronic granulomatous disease and it has been shown that there is little increase in oxidative metabolism during phagocytosis by these cells. Methods for quantitating the oxidative metabolism of granulocytes and monocytes include oxygen uptake, reduction of nitroblue tetrazolium, formate oxidation, and chemiluminescence response during phagocytosis. Since products of oxygen metabolism, i.e., hydrogen peroxide, superoxide or singlet oxygen do not accumulate in granulocyte phagocytic vacuoles, intracellular microbes are not killed (except bacterial species that produce hydrogen peroxide). The biochemical basis for defective oxidative metabolism in granulocytes from patients with chronic granulomatous disease appears to be associated with abnormal nucleotide oxidase activity. | US |
The clinical effectiveness of published algorithms in correcting serum total calcium (CaT) for the effects of protein, albumin, and pH was tested. Corrected calcium (CaC) values obtained by 13 of these methods were compared with values of measured free calcium (CaF) in 55 samples from normal controls and 404 samples from patients with various disorders of calcium metabolism. Three criteria were used to compare either CaC or CaT with measured CaF: 1) the correlation coefficient, 2) the average absolute deviation from measured CaF of the values of CaF predicted by the linear regression of CaF on each CaC, and 3) the number of samples in which CaC or CaT gave a different impression of normality than measured CaF. Application of the 13 published algorithms produced varied results, but none produced substantially better agreement between CaC and CaF than was found between CaT and CaF. The application of additional algorithms derived by multiple linear regression using our data base gave slightly better results than any of the published algorithms, but many values of CaC remained which were disparate from the measured value of CaF. Correction of measured total calcium by using other concurrently obtained chemistry values does not seem to adequately predict calcium status as measured by free calcium. | US |
Four characteristics of culture medium that are important to embryo development and nutrition of the blastocyst have been discussed. An examination of several of the most commonly used media for embryo culture demonstrates many similarities among them. The milliosmolarities of the media range from the hypoosmotic optimums (256 milliosmols) demonstrated in several in vitro studies to the physiologic range (308 to 315 milliosmols). Media between these extremes generally allow good development. Low oxygen concentrations (5%) in the culture environment allow somewhat better development of early cleavage stages, but recent studies suggest the difference between development in 5 and 20% oxygen to be less than originally thought. The media most commonly employed for early embryo culture contain bicarbonate as the buffer, but maintenance of pH is probably not the most crucial role of the CO2-bicarbonate content of the media. Likewise, since 1965 almost all media used to culture embryos have used pyruvate as the primary energy source. This is particularly important when early stages, before blastocyst development, are cultured. The concentration used generally falls within the optimum range of 2.5 to 5.0 X 10(-4)M first reported. Although glucose is not oxidized well by the early cleavage stages, it is an important energy source for all blastocysts. Furthermore, glucose contributes more than any other carbon source, including amino acids, to protein formation. Much is yet to be learned concerning the nutrition of the blastocyst, but our knowledge has increased immensely during the last 15 years. Hopefully our progress will be at least as rapid in the coming decade. | US |
The kinetics of cell wall turnover in Bacillus subtilis have been examined in detail. After pulse labeling of the peptidoglycan with N-acetylglucosamine, the newly formed peptidoglycan is stable for approximately three-quarters of a generation and is then degraded by a process that follows first-order kinetics. Deprivation of an auxotroph of amino acids required for protein synthesis results in a cessation of turnover. If a period of amino acid starvation occurs during the lag phase of turnover, then the initiation of turnover is delayed for a period of time equivalent to the starvation period. During amino acid starvation, new cell wall peptidoglycan is synthesized and added to preexisting cell wall. This peptidoglycan after resumption of growth is also subject to degradation (turnover). It is suggested that cell wall turnover is dependent on cell growth and elongation. Several possible control mechanisms for cell wall autolytic enzymes are discussed in light of these observations. | US |
Earlier studies indicated that the gene of an ammonium-inducible glutamate dehydrogenase (GDH) was inducible throughout the cell cycle and was expressible shortly after replication early in the S-phase in synchronous Chlorella cells growing at a rate of 13% per h in the absence of inducer. In the present study, synchronous cells cultured at the same growth rate in the continuous presence of inducer accumulated this enzyme in a linear manner, with a positive rate change observed late instead of early in the S-phase. At a growth rate of 26% per h, the positive rate change appeared to be displaced to 1.5 h before the S-phase in the next cell cycle. With 2'-deoxyadenosine, an in vivo inhibitor of deoxyribonucleic acid (DNA) synthesis, the magnitude of the positive rate change was shown to be proportional to the relative increase in DNA in the previous cell cycle. Collectively, these data support the idea that expression of newly replicated genes of this enzyme can be delayed into the subsequent cell cycle in cells in the continuous presence of inducer. Studies with cycloheximide indicated that the inducible GDH and another GDH isozyme were stable in fully induced cells in the absence of protein synthesis. However, after ammonium was removed from the culture medium, the activity of the inducible GDH decreased rapidly in vivo, with a half-time of 5 to 10 min at 38.5 degrees C, whereas the rate of accumulation of the other GDH isozyme did not change. Addition of cycloheximide, at the time of inducer removal, prevented this loss in activity of the inducible GDH. The inability to rescue the activity of the inducible GDH, by readdition of ammonium during the deinduction period, indicates that this enzyme probably underwent irreversible inactivation and/or proteolytic degradation. | US |
The effect of different extraction procedures on the yields of water-soluble and water-insoluble glycogen fractions from a number of Saccharomyces strains was studied by using a specific method for glycogen determination. The similarity of the yields obtained by the different procedures showed that neither form of glycogen is an artifact, and variations in the relative amounts of glycogen in the two fractions during cell growth and in different yeast strains suggest that they represent different pools of storage material with specific roles in cell development and differentiation. A proportion of the water-insoluble glycogen fraction, solubilized by mechanical agitation, was shown to be strongly associated with a beta-glucan-like polysaccharide that may be a cell wall component. | US |
Enzymatic methyl ester formation in Escherichia coli ribosomal proteins was observed. Alkali lability of the methylated proteins and derivatization of the methyl groups as methyl esters of 3,5-dinitrobenzoate indicate the presence of protein methyl esters. The esterification reaction occurs predominantly on the 30S ribosomal subunit, with protein S3 as the major esterified protein. When the purified 30S subunit was used as the methyl acceptor, protein S9 was also found to be esterified. The enzyme responsible for the esterification of free carboxyl groups in proteins, protein methylase II (S-adenosyl-L-methionine:protein carboxyl methyltransferase, EC 2.1.1.24), was identified in E. coli Q13. This enzyme is extremely unstable when compared with that from mammalian origin. By molecular sieve chromatography, E. coli protein methylase II showed multiple peaks, with a major broad peak around 120,000 daltons and several minor peaks in the lower-molecular-weight region. Rechromatography of the major enzyme peak showed activities in several fractions that are much lower in molecular weight. The substrate specificity of the E. coli enzyme is similar to that of the mammalian enzyme. The Km value for S-adenosyl-L-methionine is 1.96 X 10(-6) M, and S-adenosyl-L-homocysteine was found to be a competitive inhibitor, with a Ki value of 1.75 X 10(-6) M. | US |
Preservation of donor tissue for human keratoplasty has been evaluated using modified M-K medium. The medium has been modified by changing the antibiotic and buffer and adding a pH indicator. These changes offered theoretical and practical advantages. There were no primary donor failures in 50 consecutive penetrating keratoplasties with an overall success rate of 92 percent. Clinical specular microscopy revealed good endothelial cell survival. | US |
The various neurohumoral and intrinsic factors that control the uteroplacental hemodynamics in health and disease and in responses to physiologic and pharmacologic stimuli have been reviewed. The following conclusions may be derived: We still need improvement in our methodology of monitoring uterine blood flow. The present methods, which have some reliability, are not easily applicable to human subjects and even in animals their use presents problems of accuracy and sensitivity with which the investigator must become familiar. The marked and progressive increase in uterine blood flow that occurs during pregnancy is caused by complex factors, some of which are hormonal and hemodynamic in nature. The increased vascularity of the pregnant uterus and the opening of the arterioles during the process of formation of the intervillous space are important factors that facilitate the increase in uterine blood flow. The increment seems to be totally derived from the increment in the cardiac output that occurs during pregnancy. There seems to be no redistribution among the regional blood flows of the body. In the anesthetized condition the blood flow to the uterus depends largely on the perfusing pressure; the critical closing pressure seems to be around the 40 mm Hg level. This linear flow-pressure relationship does not, however, apply to the unanesthetized condition. A rise or fall in the perfusing pressure in the conscious state may be accompanied by an increase or decrease in the uterine blood flow, depending on the underlying mechanisms. Factors that lead to alpha-adrenergic stimulation produce an increase in uterine vascular resistance and a decrease in flow, irrespective of the status of the perfusing pressure. beta-adrenergic stimulation may increase uterine blood flow either through their vasodilating action or through their myometrial relaxing effects. Hypertensive diseases are most often accompanied by a decrease in uterine blood flow, whereas hypoxic states may decrease the flow even though the arterial pressure may not change significantly. It is extremely risky to extrapolate from information obtained in the anesthetized animal to the unanesthetized, conscious animal. Likewise, data obtained from normotensive conditions may not hold true for the hypertensive or hypotensive states. This is of particular relevance when one is dealing with the effects of pharmacologic agents that act on the cardiovascular system. Uterine contractions, whether induced through spontaneous or oxytocin-induced labor, produce a decrease in uterine blood flow.(ABSTRACT TRUNCATED AT 400 WORDS) | US |
The reinforcing properties of etonitazene, both conditioned and unconditioned, were measured in rats that had received saline only by continuous intravenous infusion ("saline" group) and in two groups of rats that had been physically dependent on morphine to equal degrees (and presumably had developed equal degrees of tolerance to morphine): one by once daily passive intravenous injection of morphine ("injection" group) and the other by passive continuous intravenous morphine infusion at the same daily doses for approximately the same number of days ("infusion" group). Prior to passive saline and morphine administration, all rats were trained to press right- and left-sided levers for water reinforcement from 1600 to 0800 hrs to a not more than 60-40 split, and these and other measures ("baselines") were repeated after recovery from the early (acute) morphine-abstinence syndromes. Then etonitazene, 5 micrograms/ml, was substituted for water on the nonpreferred side and all measures were repeated from 1600 to 0800 hrs once every two weeks for 20 weeks (10 "relapse" tests). It was postulated that the daily cycles of morphine-abstinence and suppression of abstinence in the injection group only would generate latent interoceptively conditioned reinforcing properties of morphine because of conditioning of suppression of abstinence to the concomitant internal sensorial effects of morphine, which would persist after morphine withdrawal and be transferred to the internal effects of another opioid, etonitazene. It was found that across the first nine relapse tests, the injection group consumed significantly more etonitazene than the infusion group, while there were no significant differences in water consumption.(ABSTRACT TRUNCATED AT 250 WORDS) | US |
Emergence of antibiotic resistance is related to the ease of mutation, to the extent of exchange of genetic information in bacteria by conjugation, transformation, and transduction, and to the large-scale use of antimicrobial agents in the biosphere. In addition to the development of resistance through chromosomal mutation and exchange of chromosomal genes among organisms, there is a more profound enlargement of the gene pool by the dissemination and amplification of plasmids. Two examples of the exchange of antibiotic resistance are analyzed: the transfer of plasmids from Bacteroides fragilis to Escherichia coli and the emergence of antibiotic-resistant strains of STreptococcus pneumoniae. Plasmids encoding antibiotic resistance in B. fragilis were transferred to E. coli by DNA-mediated transformation and conjugation. The beta-lactamase in the transformants and transconjugants displayed the same substrate specificity and electrophoretic mobility as the donor strain. The plasmid apparently was integrated rapidly into the chromosome of the recipient strain. Multiple antibiotic-resistant strains of S. pneumoniae were analyzed for plasmids, and none were detected. Furthermore, no evidence of linkage between the traits of multiple antibiotic resistance was observed. beta-Lactamase was not detected in the penicillin-resistant strains; therefore, it is likely that the resistance in these strains was chromosomal rather than plasmid-mediated. The range of genetic exchange and the use of Koch's postulates in determining the genetic mechanism of antibiotic resistance are illustrated and discussed. | US |
1. After separation by SDS gel-chromatography, analysis of AEP-containing glycoproteins from M. senile, indicated 66% amino acids with 220 AEP res./1000 res. and 30% carbohydrate for high mol. wt (greater than 10(7) forms and 80% amino acids with 25-50 AEP res./1000 res. and 10% carbohydrate for low mol. wt (2-4 x 10(4) forms. 2. Uronic acids, sulfate, lipid, and sialic acids were absent. 3. Mild base digestion released AEP-hexosamine containing oligosaccharides and destroyed ser-thr residues in the high mol. wt components. 4. Phosphonoglycoproteins appear to be acidic connective tissue components with AEP linked to hexosamine containing oligosaccharide side chains. | US |
1. The adenosine deaminase has an approximate molecular weight of 130,000-140,000 and the composition of two polypeptide units (mol. wt about 68,000) is suggested, by means of SDS disc electrophoresis. 2. Both the alpha (Vm/Km) and beta (Vm) parameters were varied with pH and temperature. RSS (relative substrate specificity) adenosine and deoxyadenosine values for alpha and beta were 1.2 and 1.1, respectively. 3. Adenine, 2'-, 3', 5'-AMP, 5'-deoxyAMP, ADP and ATP were not deaminated by the enzyme. 4. Inhibition by Mg2+ was found in reaction with adenosine at pH 8 but not with deoxyadenosine at the same pH. Mn2+, which did not affect the reaction rate at pH 4 and 5, showed competitive inhibitory effects at pH 6, 7 and 8. | US |
1. 2,4-Dinitrophenol (2,4-DNP) in substrate level concentrations (200 microM-1 mM) temporarily inhibits H2 production by Tritrichomonas foetus and Trichomonas vaginalis as well as the accumulation of metronidazole, dependent on its reduction by the two trichomonad species and by Entamoeba invadens. 2. 2,4-DNP competes for the reducing equivalents which are necessary for H2 production or for the reduction of metronidazole, thereby inhibiting these processes. 2,4-DNP is reduced to 2-amino, 4-nitrophenol. 3. 2,4-DNP in concentrations up to 800 microM has no effect on the uptake of O2 by these organisms. 4. 2,4-DNP has some toxicity for T. foetus. | US |
1. Two peroxidases, differing in ionic character and substrate specificity, have been isolated from the tropical marine sponge Iotrochota birotulata. 2. Both peroxidases catalyze the oxidation of a number of substrates, and one peroxidase possesses a specificity similar to the terrestrial fungal enzyme chloroperoxidase. 3. Based on inhibition studies utilizing sodium azide, potassium cyanide and 8-hydroxyquinoline, it appears that the peroxidases from I. birotulata are haemoprotein complexes. 4. One peroxidase appears to possess subunit structure, and requires bound divalent metal cations for activity. | US |
1. The synthesis of gamma-glutamylhydroxamate from glutamate and hydroxylamine has been utilized as an approximation of glutamine synthetase activity in kidneys of rabbit, rat, dog, monkey and man. 2. Kidneys of rabbit contain glutamine synthetase in high activity; those of rat, in intermediate activity; and those of dog, monkey and man, in negligible activity. 3. No more enzyme is present in kidneys of the latter two species than in those of the dog, in which the enzyme is generally considered to be absent. | US |
1. An NADP-specific glutamate dehydrogenase (E.C. 1.4.1.4) of mitochondrial origin has been detected in M. senile, a sea anemone. 2. Substrate specificity and starch gel electrophoresis experiments indicated an absence of the NAD(P) glutamate dehydrogenase (E.C. 1.4.1.3). 3. This NADP specific GDH activity appears to be the sole GDH activity in species of the animal phylum Coelenterata. | US |
1. In vitro assay conditions have been defined for measurement of delta 9 desaturase activity in Tetrahymena pyriformis W. 2. The reaction depends on the presence of oxygen and a reduced pyridine nucleotide cofactor. FAD supports a low level of enzymatic activity. 3. Both stearyl-CoA and palmityl-CoA are acceptable substrates. Oleate formation is maximal at 30 degrees C. 4. Delta-9 desaturase activity appears to be localized in the microsomal fraction. Delta-6 and/or delta 12 desaturase activities have also been observed. 5. When the specificity of the delta 9 desaturase towards stearyl-CoA and palmityl-CoA was observed at 30 and 16 degrees C it was found that lowering the assay temperature did not affect specificity. Stearyl-CoA was more readily desaturated at both temperatures. 6. Exogenous oleyl-CoA and diisopropylfluorophosphate had little effect on delta 9 desaturase activity. However, cyanide strongly inhibited desaturation and a sensitivity to sulfhydryl-binding reagents has also been demonstrated. | US |
1. The P50 of Cancer Magister hemocyanin in hemolymph was 40.0 mm at 25 degrees C, nmax = 3.9; at 14 degrees C, 15.0 mm and 3.4; and at 10 degrees C. 10.2 mm and 3.3. 2. In the absence of Ca2+ and Mg2+, the P50 at 25 degrees C was in the range of 150 to 250 mm, depending upon pH. 3. Our results show that temperature variation and pH variation may be important factors in the physiological regulation of oxygen delivery in this species. 4. The automatic recording device of Imai et al. (1970) previously used for the study of hemoglobins, was found to be eminently suitable for the study of O2 affinities of hemocyanins. | US |
1. Human haptoglobin type 1-1, porcine haptoglobin, and equine haptoglobin were isolated and purified. 2. These haptoglobins were similar in polyacrylamide gel electrophoresis and in subunit structure but showed microheterogeneity in isoelectric focusing. 3. Isoelectric points of human haptoglobin as determined with photopolymerized gels were found to be 4.03-4.24, of porcine haptoglobin 4.0-4.30, and of horse haptoglobin 3.80-4.15, respectively. 4. Results obtained with chemically polymerized gels were 0.08-0.3 pH units higher. 5. Examined haptoglobins differed also in the ability of complex formation with hemoglobin, in sialic acid content and in antigenic specificity. | US |
1. Kinetic data for avian erythrocyte AMP-deaminase in lysate supernatants and 2000-fold purified enzyme were consistent with an allosteric model having four binding sites for substrate. 2. Relative to the purified enzyme, AMP-deaminase in lysate supernatants exhibited a greater S0.5 and enhanced sensitivity toward phytic acid, but was far less sensitive toward potassium ion. 3. In the absence of potassium chloride, the enzymatic activity in lysates exhibited hysteresis at subsaturating 5'-AMP. This response was modified reversibly by allosteric ligands. 4. It is concluded that the characteristics of avian RBC AMP-deaminase, as expressed in lysates, may reflect important intermolecular interactions and better represent the regulatory properties of this enzyme in erythrocytes. | US |
1. Crithidia fasciculata adapted to growth in the presence of 10(-5) M carbonyl cyanide m-chlorophenylhydrazone (CCCP), an uncoupler of oxidative phosphorylation, maintained adenosine phosphate pools and an adenylate energy charge comparable to those of control cells. 2. CCCP-adapted cells in the presence of the uncoupler respire endogenous substrate at a greater rate than control cells and this effect of CCCP appears readily reversible. 3. CCCP-treated, adapted cells, supporting high endogenous respiration rates, were not responsive to added substrates which significantly stimulated the oxygen utilization of normal C. fasciculata. 4. CCCP-adapted cells, provided with [U-14C]-labeled proline, utilize this substrate at 67% the rate of control cells, but divide the isotopic label between CO2 and protein in a ratio identical to that of normal cells. 5. The transport of alanine and proline by adapted C. fasciculata was severely impaired, while the transport of tyrosine and leucine was unaffected. | US |
1. Some mechanisms of action of neuroleptics at cellular level are reviewed, mainly the effects on synaptic transmission and the effects on chromatin. 2. As regard to the effects at synaptic level, a brief review is presented on the available evidence in support of the currently prevailing dopamine hypothesis. 3. Studies carried out on the mechanisms and sites of action of neuroleptics on chromatin show that: a. Behavioral changes caused by psychotropic drugs in experimental animals are associated with chromatin alterations and induced macromolecular syntheses. b. Parkinsonian and possibly drug-induced extrapyramidal symptoms are associated with aberrations in protein synthesis. c. Destabilization under "stress" of the heterochromatin in schizophrenics seems to be due to histone modifications and is partly prevented by neuroleptic treatment. | US |
1. Central injection of a long lasting enkephalin analog (D-Ala2-leu-enkephalin-amide) produced a syndrome of stereotyped motor activity. 2. This activation syndrome was significantly reduced by two dopamine (DA) blockers (pimozide, fluspririlene) and by an agonist of inhibition-mediating DA receptors [(3,4-dihydroxyphenylamino)-2-imidazoline]. 3. Intact DA functioning is necessary for the occurrence of this enkephalin-mediated behavioral syndrome. | US |
Intrarenal infusion of somatostatin in anesthetized dogs produced a prompt increase in urine flow in association with a decrease in urinary osmolality and an increase in free water clearance. These changes occurred in the absence of changes in arterial pressure, renal plasma flow, osmolar clearance, electrolyte excretion or cyclic AMP excretion. The diuretic effect occurred primarily in the infused kidney indicating a direct intrarenal action rather than suppression of vasopressin secretion. This diuretic action of somatostatin may result from inhibition of the action of vasopressin on the renal medulla but other possible mechanisms cannot be excluded. | US |
The objective of this study was to investigate changes in the secretion of prolactin (PRL) and growth hormone (GH) occurring during a 24 h period in the mouse. Adult female mice of the C57BL/St strain and male mice of the C3H/St strain, maintained on a 14 h light and 10 h dark schedule, were used. Serum and pituitary concentrations of PRL and GH were measured by radioimmunoassay in samples collected by decapitation at hourly intervals through 24 h. Serum PRL concentrations in female mice averaged higher during the daylight hours and lower at night. However, the pattern was just the opposite in males: the values were lower during the day time and higher and variable during the night. Pituitary PRL levels dropped significantly after the onset of the dark phase in mice of both sexes. Serum GH concentrations of female mice did not fluctuate significantly with the time of the day, but those of male mice displayed a distinct flux: the levels were low from 0800 h until 1500 h, began to rise in the afternoon, and remained relatively high throughout the night. Pituitary levels of GH did not change with time in mice of either sex. The data suggest the existence of daily rhythms in the secretion of PRL and GH in mice, with marked differences related to sex. In general, the changes were most pronounced for serum PRL in females and for serum GH in males. | US |
Immunoelectrophoresis revealed in phenol extracts from S. faecalis and S. faecium a mixture of free and lipid-bound teichoic acids, both reactive with Group D antisera. In phenol extracts from S. suis only lipid-bound teichoic acid, also reactive with Group D antiserum, was seen. This difference probably accounts for the low yield of Group D antigen from S. suis as compared with S. faecalis and S. faecium when heating at pH 2 is used for extraction. When phenol is used good yields are obtained from S. suis as well as from S. faecalis and S. faecium. Lipoteichoic acids from S. faecalis and S. faecium have a backbone structure the same as or similar to that of Group A streptococcal teichoic acid. Lipoteichoic acid from S. suis has a structure differing from that of S. faecalis and S. faecium, e.g., possibly in the attachment of its glucosyl substituents. Precipitation reactions between S. suis lipoteichoic acid and Group D antisera were specifically inhibited by glucose. Reactions between S. bovis phenol extracts and some Group D antisera were also specifically inhibited by glucose, but extracts from S. faecalis and S. faecium were not. This may indicate a monosaccharide glucosyl substituent in teichoic acid from S. suis and S. bovis instead of the di- or trisaccharide previously postulated as the glucosyl substituent in the teichoic acid of S. faecalis. | US |
Graft-vs.-host (GVH) reactivity of parental lymph node (LN) cells was assayed by measurements of 3H-thymidine incorporation in vivo in spleens of irradiated F1 recipients. Preincubation of parental LN cells with vesicular stomatitis virus (VSV) for 2 h at 37 degrees C followed by washing resulted in an 85-90% reduction in splenic radioactivity, as did injection of VSV on days 0-2 after recipients received untreated parental LN cells. In contrast, 3H-thymidine incorporation in the spleens or irradiated F1 hosts was not affected by VSV when F1 bone marrow cells were incubated with the virus. In addition, preincubation of F1 B cells with VSV still allowed these syngeneic B cells to be recruited into proliferation by mitomycin-treated parental LN cells. The inhibitory effect of VSV, thus, seems to be specific for T-cell proliferation. These observations suggest that viral immunosuppression might be capable of being developed into a useful strategy for selective deletion of lymphocytes capable of reacting against histocompatibility antigens and initiating GVH reactions. | US |
Frequencies of different staphylococcal nasal carrier classes were studied in groups of students of nursing and of laboratory personnel in Cologne, West Germany, and in Krakow, Poland, by six consecutive samplings of their nasal vestibules. The general number of persistent carriers of S. aureus appeared to be lower than in previous studies, paralleling the diminished numbers of staphylococcal infections in populations. Differences in numbers of persistent carriers between the Cologne and Krakow groups were probably related to the incidence and types of S. aureus in the environment. | US |
A DNA replication mutant of yeast, cdc8, was found to decrease UV-induced reversion of lys2-1, arg4-17, tyr1 and ura1. This effect was observed with all three alleles of cdc8 tested. Survival curves obtained following UV irradiation in cdc8 rad double mutants show that cdc8 is epistatic to rad6, as well as to rad1; cdc8 rad51 double mutants seem to be more sensitive than the single mutants. Since UV-induced reversion in cdc8 rad1 and cdc8 rad51 double mutants is like that of the cdc8 single mutants, we conclude that CDC8 plays a direct role in error-prone repair. To test whether CDC8 codes for a DNA polymerase, we have purified both DNA polymerase I and DNA polymerase II from cdc8 and CDC+ cells. The purified DNA polymerases from cdc8 were no more heat labile than those from CDC+, suggesting that CDC8 is not a structural gene for either enzyme. | US |
Assuming that unrecognized or inadequately corrected hypovolemia results in higher mortality and morbidity rates, we developed a systematic approach to resuscitation that would: 1) identify criteria to aid in the recognition of hypovolemia and ensure the expeditious correction of this defect without interfering with diagnostic workup and management; 2) define criteria to prevent fluid overload which may jeopardize the patient's course, and 3) express these criteria in an explicit, systematic, patient care algorithm, ie, protocol, useful to both the resident and the practicing physician. We are now conducting prospective clinical trials with one service using the algorithm and the others acting as the control group. Preliminary results comparing patient outcomes suggest that the algorithm improves patient care by shortening resuscitation time and results in fewer hospital days, intensive care unit days, febrile days, and days on mechanical ventilation as well as reduced mortality. The algorithm provides a systematic plan to organize patient care so that the most urgently needed procedures are not delayed or overlooked. | US |
Variation in the assessment of basic clinical data gathered by emergency medical technicians and emergency department nurses was studied. Prior to testing, precise definitions, categories and procedures were developed and tolerance limits for the quantitative variables were created. Each participant evaluated four consecutive patients simultaneously with another evaluator setting the standard. The results indicate that the error rate is low to moderate for the different variables. For the quantitative variables, the error rate is over 20% and, when an error does occur, it is often very large. This indicates a need for ongoing emphasis on accurate measurement and, in cases where highly accurate data is essential, the use of multiple observers. | US |
There is a need at both the emergency department and national level for a systematic method to prioritize clinical and nonclinical areas for research and quality assessment. A method has been developed and applied that allows frequently presenting diagnoses and management issues to be rated in terms of morbidity generated, efficacy of (optimal) clinical intervention, discrepancy between optimal and current treatment, and the impact of an evaluative intervention study on improving care. Also, a summary research priority score was derived. When this method was used by physicians, nurses and administrators at the Johns Hopkins Hospital Adult Emergency Department, a reasonable level of agreement between the three responding groups emerged. | US |
A hypertonic albuminated fluid demand regimen (HALFD) for resuscitation has been used in burn patients since January 1, 1976. The effects of the HALFD method were compared with hypertonic fluid and Ringer's lactate resuscitation. Specific attention was directed to fluid, colloid, and volume changes. Resuscitation was guided by maintaining the mean arterial pressure between 60 to 110 torr, and urine volume at 30 to 50 ml/hr. Patients treated with the HALFD method fared significantly better clinically, needed less fluid, had less weight gain and plasma leak, and experienced slower plasma volume repletion than those treated more traditionally. We conclude that the HALFD method is a physically and physiologically appropriate paradigm for resuscitating the volume-depleted patient. | US |
A karyological analysis of the G-banded chromosomes of the serially transplantable GW-39 human colonic carcinoma was undertaken. GW-39 cells harvested from hamsters, nude (athymic) mice and cell cultures from 1972 to 1976 revealed a hypodiploid stemline of 45 human chromosomes, with a consistent loss of a 21-chromosome. No apparent alterations of the near-diploid stemline resulted during long-term xenogeneic propagation of this human cancer line. | US |
The postulated role of macrophages in the primary infection of human lymphocytes by Epstein-Barr virus (EBV) was examined. Macrophage removal had no effect on the blastogenic response but slightly reduced the percentage of EBNA-positive cells induced by the B 95-8 virus strain. Both the rate of DNA synthesis and the appearance of EBNA-positive cells could rather be related to the number of B cells in the infected populations. Macrophages are thus not required for the initiation of EBV-induced lymphocyte transformation. | US |
Protein modification with dimethylnitrosamine was studied in vitro in the presence of hamster liver microsomal fraction. Incorporation of radioactive methyl groups from dimethylnitrosamine into the exogenously added protein was dependent on the microsomal mixed function oxidase system. The methylation yielded chemically labile and stable products. The former was completely hydrolyzed by the mild alkaline treatment, pH 7.4, 100 degrees C, for 5 min and the hydrolytic product was identified as methanol indicating that the activated methyl groups from dimethylnitrosamine were incorporated into a protein as a carboxyl-methyl ester. Thus, it is suggested that methanol, recovered as one of the products during the biodegradation of dimethylnitrosamine [8], is derived, at least in part, from protein carboxyl-methyl ester which is unstable under physiological conditions. | US |
Phorbolol myristate acetate, a metabolite of the tumor promotor phorbol muristate acetate in mouse skin, has one-fiftieth the potency of the parent molecule for the induction of cell division in stationary cultures of BALB/c-3T3 mouse embryo cells. Similarly, in a mixed cell culture assay devised for detection of tumor-promoting agents, phorbolol myristate acetate exhibited only a small fraction of the activity of unmetabolized phorbol ester. The results indicate that the biological activity of phorbol esters either does not require metabolic conversion or is converted by the cells used in this system and that phorbolol myristate acetate would be a tumor promotor of low potency for mouse skin compared to phorbol myristate acetate. | US |
Binding capacities of membrane suspensions and dissolved compounds for mercurials were titrated by a new potentiometric method. Critical steps included a silver electrode of new design, the use of L-cysteine as a thiol buffer, a nitrogen atmosphere, and pretreatment of samples with equimolar mercurial and cysteine. Titrations had a sharp endpoint, accurate +/- 26 nmole methylmercury or +/- 8 nmole mercuric salt. Measurements of binding capacity of bovine serum albumin averaged 93% of the titer predicted for one SH group per molecule; those of human hemoglobin yielded 86-91% of the titer predicted for two SH groups per molecule. Yields dropped with exposure of protein solutions or membrane suspensions to atmospheric oxygen. Brain microsomes had significantly higher binding capacities (per milligram of protein) than red blood cell ghosts. The ratio of endpoint titers of CH3HgCl to HgCl2 averaged 2:1 in assays of cysteine, proteins, and membranes, showing that the assay was free of denaturation artifacts and protein-protein interference. Solutions of EDTA showed measurable binding of Hg2+ but not of CH3Hg+. Satisfactory titrations were also obtained with N-ethylmaleimide. | US |
The effect of semistarvation on small intestinal transport of D-glucose, L-valine, and NaCl was studied in an in vitro system of isolated rat brush border membrane vesicles. Whereas semistarvation enhanced the transport rate for L-valine by 19-29%, there was no change in D-glucose transport. When energy in the form of a NaSCN gradient was supplied to the membrane vesicles prepared from semistarved animals, L-valine was concentrated to a greater extent than those from well-fed animals. Strain differences were observed in the manner semistarvation affected NaCl transport across the brush border membrane. Semistarvation increased the NaCl transport rate by a factor of 3.5 in one rat strain and not at all in another. These results provide a partial explanation for the cellular basis of elevated neutral amino acid absorption by the small intestine in semistarvation. | US |