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A study of the interaction between D-amino acid oxidase and quasi-substrates.
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To study the interaction between D-amino acid oxidase [EC 1.4.3.3] and quasi-substrates such as benzoate and o-, m-, and p-aminobenzoate, visible circular dichroism spectra (CD spectra) were measured and the binding rate and affinity of o-aminobenzoate to the enzyme were observed by following the absorption changes at various wavelengths. We found a new CD band around 560 nm, corresponding to the charge-transfer complexes which result from the formation of aminobenzoate complexes with the enzyme. The ellipticity of this band was positive for the p-aminobenzoate complex, but negative for the o- and m-aminobenzoate complexes. Crossover points in CD spectra were observed at 470 nm for the m-aminobenzoate complex and at 475 nm for the o-aminobenzoate complex. They probably resulted from overlapping of the positive CD band of FAD bound with the enzyme and the negative CD band of the charge-transfer complex. We propose that the amino group in aminobenzoate, not the pi-electrons of the benzene ring, is the electron donor in the charge-transfer complex and that the position of the amino group is very important for the charge-transfer interaction. The binding rate and affinity of o-aminobenzoate to the enzyme were determined using the absorption changes at 370 nm (380 nm), caused by the modification of electronic states of FAD bound with the enzyme, and at 550 nm (565 nm), caused by the formation of the charge-transfer complex of o-aminobenzoate with the enzyme. No differences between these parameters with wavelength were observed. This independence of wavelength simplifies discussion of the experimental data obtained from absorption changes.
| 12,151
|
Metabolism of triacylglycerol in Mycobacterium smegmatis.
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Mycobacterium smegmatis cells incorporated [1-14C]oleic acid into triacylglycerols (TG) from the medium more rapidly than shorter chain fatty acids, caprilic and butyric acids. This incorporation was inhibited more strongly by 10(-3) M N-ethylmaleimide than by 10(-3) M KCN. [14C]TG in the bacterial cells was utilized when the cells were in poor nutritional conditions, such as phosphate buffer (pH 7.0) containing oleic acid. Accumulation of TG was observed in the cells at late stages of growth. Diglyceride acyltransferase [EC 2.3.1.20] activity was detected in a cell-free extract from this bacterium. The pH optimum of this enzyme was between pH 7 and 9. F- and Tween 20 showed remarkable enhancing and inhibitory effects, respectively.
| 12,154
|
Activation of soluble guanylate cyclase from rat lung by incubation or by hydrogen peroxide.
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A 37,000 X g supernatant fraction prepared from fat lung homogenate demonstrated a 2- to 3-fold increase in guanylate cyclase activity after incubation at 30 degrees for 30 min (preincubation). Treatment of the supernatant fraction with Triton X-100 increased activity to approximately the same extent as preincubation, but would not increase the activity after preincubation. By chromatography on Sepharose 2B, before and after preincubation, it was demonstrated that the increase in activity was only associated with the soluble guanylate cyclase, and not the particulate enzyme. Activation by preincubation required O2. It was completely inhibited by thiols such as 2-mercaptoethanol, and by bovine serum albumin, KCN, and sodium diethyldithiocarbamate. These inhibitors suggested a copper requirement for activation, and this was confirmed by demonstrating that 20 to 60 muM CuCl2 could relieve the inhibition by 0.1 mM sodium diethyldithiocarbamate. 2-Mercaptoethanol inhibition could also be reversed by removal of the thiol on a Sephadex G-25 column, however, this treatment partially activated the enzyme. Addition of 2-mercaptoethanol to a preincubated preparation would not reverse the activation. H2O2 was found to activate guanylate cyclase, either by its generation in the lung supernatant with glucose oxidase and glucose, or by its addition to a preparation in which the catalase was inhibited with KCN. KCN or bovine serum albumin was able to partially inhibit activation by glucose oxidase plus glucose, however, larger amounts of glucose oxidase could overcome that inhibition, indicating a catalytic role for Cu2+ at low H2O2 concentrations. No direct evidence for H2O2 formation during preincubation could be found, however, indirect evidence was obtained by the spectrophotometric detection of choleglobin formation from hemoglobin present in the lung supernatant fluid. The H2O2 is believed to result from the reaction of oxyhemoglobin with ascorbate.
| 12,160
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Synthesis of bound adenosine triphosphate from bound adenosine diphosphate by the purified coupling factor 1 of chloroplasts. Evidence for direct involvement of the coupling factor in this "adenylate kinase-like" reaction.
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Electrophoretically homogeneous coupling factor 1 from spinach chloroplasts binds ADP and converts the bound ADP to bound ATP and AMP. That this transphosphorylation of enzyme-bound ADP is catalyzed by the coupling factor itself, and not be a conventional adenylate kinase which might possibly contaminate preparations of the coupling factor, is supported by the following evidence. 1. The procedure for isolatio of the coupling factor is designed to separate this large (approximately 13 S) enzyme from the smaller (4.2 S) conventional adenylate kinase of spinach chloroplasts. The conventional adenylate kinase cannot be detected in purified preparations of the coupling factor by biochemical assay or by polyacrylamide gel electrophoresis. 2. The activity of spinach adenylate kinase is completely dependent upon magnesium ions. However, the production of bound ATP and AMP from bound ADP by the coupling factor can be assayed in the total absence of added magnesium ions or even in the presence of added EDTA. 3. Comparative studies with inhibitors show that the coupling factor can produce bound ATP from ADP under conditions where the activity of adenylate kinase is strongly inhibited. Conversely, the coupling factor is prevented from synthesizing bound ATP from ADP under other conditions where the conventional adenylate kinase has high levels of activity. 4. AMP, when added in solution to the coupling factor, does not bind to this enzyme, even in the presence of APT. Thus, it is unlikely that the appearance of AMP bound to the coupling factor after its incubation with ADP is due to the production of free AMP by contaminating adenylate kinase. These results demonstrate that the isolated, homogeneous coupling factor from spinach chloroplasts has the intrinsic capacity to perform a phosphoryl group transfer between two bound ADP molecules and thus to synthesize ATP. This reaction may have an important role in the photosynthetic production of ATP by the chloroplast, as is discussed in this communication.
| 12,178
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Comparison of the size and physical properties of gamma-glutamyltranspeptidase purified from rat kidney following solubilization with papain or with Triton X-100.
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gamma-Glutamyltranspeptidase is associated with the brush border membrane of kidney proximal straight tubule cells. It can be solubilized qualitatively by treatment with papain or Triton X-100. Neither procedure affects its catalytic activity but the two resulting forms of the enzyme differ considerably in their physical properties. The papain-solubilized transpeptidase is soluble in aqueous buffers and was purified 430-fold. It has an s20,w of 4.9 S, a Stokes radius of 36 A, and a calculated molecular weight of 69,000. It appears homogeneous by sedimentation equilibrium centrifugation (Mr=66,700). In contrast, the Triton-solubilized transpeptidase is soluble only in the presence of detergents and was purifed 300-fold. This form of the enzyme has a Stokes radius of 70 A but an s20,w of only 4.15 S. Aggregation of the enzyme just below the critical micelle concentration of Triton X-100 and its ability to bind 1.16 mg of Triton X-100-protein complex was calculated to be 169,000, but the glycoprotein portion of the complex is 52% of the total mass (87,000). The mass of Triton X-100 (82,000) is consistent with its reported micelle molecular weight. Treatment of the Triton-purified transpeptidase with papain or bromelain results in a form of the enzyme identical in all respects with the papain-purified enzyme. Both the Triton- and papain-purified transpeptidase exhibit two protein bands on sodium lauryl sulfate-polyacrylamide gel electrophoresis. The smaller subunits of the two forms appear identical (Mr=27,000), while the larger subunits of the Triton- and papain-purified enzyme have apparent molecular weights of 54,000 and 51,000, respectively. These data suggest that a peptide (3,000 to 19,000) in the larger subunit of gamma-glutamyltranspeptidase is responsible for its binding to Triton micelles and probably for holding the enzyme in the brush border membrane.
| 12,182
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Plasma protein synthesis by isolated rat hepatocytes.
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A system of preparation of rat hepatocytes with extended viability has been developed to study the role of hormones and other plasma components upon secretory protein synthesis. Hepatocytes maintained in minimal essential medium reduced the levels of all amino acids in the medium except the slowly catabolized amino acids leucine, isoleucine, and valine, which steadily increase as the result of catabolism of liver protein. Although the liver cells catabolize 10-15% of their own protein during a 20-h incubation, the cells continue to secrete protein in a linear fashion throughout the period. The effects of insulin, cortisol, and epinephrine on general protein synthesis, and specifically on fibrinogen and albumin synthesis, have been tested on cells from both normal rats and adrenalectomized rats. Cells from normal animals show preinduction of tyrosine amino transferase (TAT), having at the time of isolation a high level of enzyme which shows only an increase of approximately 60% upon incubation with cortisol. In contrast, cells from adrenalectomized animals initially have a low level of enzyme which increases fourfold over a period of 9 h. The effects of both epinephrine and cortisol on protein synthesis are also much larger in cells from adrenalectomized animals. After a delay of several hours, cortisol increases fibrinogen synthesis sharply, so that at the end of the 20-h incubation, cells treated with hormone have secreted nearly 2.5 times as much fibrinogen as control cells. The effect is specific; cortisol stimulates neither albumin secretion nor intracellular protein synthesis. The combination of cortisol and epinephrine strongly depresses albumin synthesis in both types of cells. Insulin enhances albumin and general protein synthesis but has little effect on fibrinogen synthesis.
| 12,183
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Inhibition of mammalian soluble guanylate cyclase activity by adenosine 5'-tetraphosphate, guanosine 5'-tetraphosphate and other nucleotides.
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The effects of a variety of purine and pyrimidine nucleotides were tested for their capacity to inhibit mammalian soluble guanylate cyclase activity. Adenosine 5'-tetraphosphate (ATetP), ATP, ADP, AMP, guanosine 5'-tetraphosphate (GTetP) and GDP were found to inhibit soluble guanylate cyclase activity from rat lung and other mammalian tissues. The corresponding cytosine and thymine nucleotides showed little or no inhibitory activity, except for thymidine 5'-tetraphosphate, which inhibited glanylate cyclase activity but to a lesser extent than did the purine nucleoside tetraphosphates. ATetP and GTetP were found to be potent inhibitors of soluble guanylate cyclase activity from rat, guinea pig and mouse lung, rat heart and rat brain. Both purine nucleoside tetraphosphates were competitive inhibitors of the rat lung soluble enzyme. ATetP and GTetP had Ki values of 1 muM and 2.5 muM, respectively. The experimental data suggest that purine nucleoside tetraphosphates, and perhaps other purine nucleotides, may play a biologic role in modulating mammalian soluble guanylate cyclase activity.
| 12,193
|
Acetylcholine synthesis in sympathetic human neuroblastoma.
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The synthesis of acetylcholine, as well as catecholamines, was studied by assaying the activities of choline acetyltransferase (ChA) and tyrosine hydroxylase (TH) in the tumor tissues and the culture cells of human neuroblastoma. In the majority of 20 neuroblastomas of sympathetic origin, both ChA and TH activities were detected at a significantly high level. In the culture cells of five cell lines of human neuroblastoma, ChA activity was high, but TH was negative in four of the lines. However, it was observed that these enzyme activities changed significantly while in the long-term culture. ChA assay is a useful diagnostic test for neuroblastomas that synthesize acetylcholine. Future studies of neuroblastoma should consider cholinergic activity.
| 12,256
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The adhesion of film coatings to tablet surfaces--instrumentation and preliminary evaluation.
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The strength of the adhesive bond between a film coating and a tablet surface has been studied using a specially designed tensile testing apparatus. The adhesion has been taken as the force required to remove the film from unit area of the tablet surface and has been shown to be dependent on the compression pressure used to prepare the tablet and on changes in the film formulation. Although plasticizers did not show any significant effect on the adhesion of a hydroxypropyl methylcellulose film, a reduction of 45% was found on the addition of 10% w/w titanium dioxide.
| 12,264
|
[Arteritis of the large vessels originating at the aorta (Takayasu arteritis) in childhood (author's transl)].
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A 9-month-old female child with extensive inflammatory lesions in the large arterial trunks originating at the aorta (Takayasu arteritis) was reported. Severe cerebral, intestinal and coronary circulatory disturbances as well as insufficient blood supply in both arms, particularly the left arm, developed as a result of the stenoses and obliterations. Clinical course, postmortem findings and the results of EKG, EEG and carotid angiography were discussed. The onset in infancy and the very rapid progression of the disease were unusual.
| 12,403
|
[Cyclic AMP and plasma renin activity in renal vein blood after amitryptiline, theophylline, furosemide and beta adrenergic blocking substances (author's transl)].
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The influence of amitryptiline, theophylline and furosemide on the concentration of cyclic-AMP and plasma renin activity (PRA) was investigated in renal vein plasma. Additionally, the stimulating effect of furosemide on the PRA after application of the beta-adrenergic receptor antagonists propranolol and practolol and the cyclic AMP concentration in the plasma were measured. All drugs were given intravenously. After amitryptiline cyclic-AMP concentration increased about 1.5-fold compared with the basal value,PRA was not altered. After theophylline cyclic-AMP concentration increased about 1.2-fold, PRA 2.0-fold compared with the basal value, PRA was not altered. After theophylline cyclic-AMP concentration increased about 1.2-fold, PRA 2.0-fold coa increased within 7 min and no further increase was observed till the 15th min. After practolol cyclic-AMP concentration and PRA decreased about 20% compared with the basal value within 10 min. The stimulating effect of subsequently applied furosemide on PRA was not altered, but the cyclic-AMP concentration was not changed in this time by furosemide. After propranolol cyclic-AMP concentration and PRA decreased about 20% compared with the basal value. The cyclic-AMP concentration was not influenced by the following furosemide application, in agreement with the findings after practolol, however, PRA could be stimulated only in 36% of these patients under beta-receptor blockade. Our results show that changes of the concentrations of cyclic-AMP and of PRA are independent of each other. An elevated intracellular cyclic-AMP level due to the inhibition of phosphodiesterase is as a single factor unable to stimulate renin release. Our results give no evidence of a direct involvement of the adenylcyclase-system in the mechanism of renin release. The effect of propranolol and practolol on the basal value of PRA and cyclic-AMP is equal. The different influence of 10 mg propranolol and 20 mg practolol on the stimulating effect of 40 mg furosemide on the PRA can be interpreted as a dosage problem.
| 12,404
|
[The effect of surgery, performed under ischemia, on the fine structure of the hand muscles].
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The ultrastructural picture of the intact and injured hand muscles has been examined by the authors during and after operations in tourniquet ischaemia of 12 patients, in connection with tendon and nerve reconstruction. Muscle specimina were taken partly in the beginning of the ischaemization, and partly at the end ot it, every 15--20 minutes, and the muscle specimina have been examined by means of electron microscope. It has been found that in the first 2 hours of ischaemia neither the intact muscles, nor those previously injured suffer demonstrable damage.
| 12,410
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Immunohistochemical studies on the localization and distribution of monoamine neuron systems in the rat brain. I. Tyrosine hydroxylase in the mes- and diencephalon.
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The localization and distribution of tyrosine hydroxylase (TH), the first enzyme in the catecholamine synthesis, in the mes- and diencephalon has been studied with the indirect immunofluorescence technique of Coons and collaborators. Principally, TH was present in neuron systems with a distribution similar to known dopamine, noradrenaline and adrenaline systems. The present data, taken together with published and some unpublished results, indicate that all parts of most central dopamine neurons, i.e. cell body, dendrites, axon and nerve terminals, appear strongly fluorescent. The adrenaline neurons also appeared strongly fluorescent, except for their axons, which only exhibited a weak fluorescence. Only cell bodies of noradrenaline neurons were strongly fluorescent, whereas the nerve terminals and axons showed a weak or moderate fluorescence intensity. The fine noradrenaline nerve terminals in some areas, such as the thalamus, were invisible or, under favourable conditions, weakly fluorescent. Therefore, in the present study we are mainly dealing with the dopamine neurons of the upper brain stem. Our results demonstrate a widespread occurrence of TH-positive neuron systems in the mes- and diencephalon. The different mesencephalic dopamine systems and their ascending projections were visualized. Numerous TH-positive cell bodies were present along the ventricle system extending from the aqueductus cerebri to the most cranial periventricular parts of the third ventricle. The caudal part of these neurons, consisting of very small cell bodies, belong to the dorsal periventricular system described by Lindvall and Björklund. Several TH-positive cell bodies were also observed in the inferior collicle of young animals. In the superficial layers of the inferior collicles TH positive nerve terminals were seen. At the hypothalamic level the A11 to A14 cell groups as well as some additonal cell bodies and extensive nerve terminal plexuses appeared strongly fluorescent. The differences in the intensity of the TH-related immunofluorescence between various brain regions and between various neuron systems may well reflect differences in enzyme levels between the various catacholamine systems rather than be due to the existence of different types of TH.
| 12,423
|
Adding a Medex to the medical mix: an evaluation.
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Three classes of Medex were followed during their preceptorship training and subsequent employment to assess the impact of adding such physician assistants on 13 private practices. The data suggest that the Medex are readily incorporated into the practice, seeing a similar spectrum of patients and generally functioning as a semicolleague. Although the Medex was almost universally a contributing addition to the practice, increasing patient volume, the specific effects varied with the setting.
| 12,425
|
[Biosynthesis of chitinase by Achromobacter liquefaciens].
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Bacterial cultures under study synthesize exocellular chitinase on a medium containing chitin or demineralized crab shells as a source of carbon and nitrogen. Conditions for biosynthesis of chitinase by the cells of Achromobacter liquefaciens 301a were investigated under periodic and continuous conditions of cultivation. The preparation of chitinase isolated from the cultural broth of A. liquefaciens 301a hydrolysed colloid and native chitin at the optimum pH 6.5 and temperature 40degreesC. The terminal products of the reaction are chitobiose and N-acetylglucosamine.
| 12,452
|
New approaches to the causation and prevention of cancers of epithelial surfaces.
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Environmental rather than genetic factors appear to be responsible for the causation of cancers involving epithelial surfaces, especially oropharyngeal cancers, cancers of the gastro-intestinal tract, cancers of the liver and gall-bladder, cancers of the cervix uteri and lung cancers. Epithelial surfaces which have mucus-bearing cells are particularly prone, because if these mucus cells are surrounded by an alkaline milieu over a prolonged period, the mucous of the epithelial cells is rendered fluid and is removed from the cells, of which it forms an integral part. This leads to proliferative changes with metaplasia, cell-atypia and a very significant increase in mitotic activity. Such changes are a prelude to carcinogenesis. In the case of many oropharyngeal cancers in Asia and Africa it is the alkaline slaked lime in the betel quid which is responsible; in the case of gastric cancers it is the reflux of the alkaline duodenal contents into the stomach; in the case of colon it is the absence of roughage, cellulose and vegetable fibres from the diet; in the case of the cervix uteri it is the frequency of coitus which gives rise to a highly alkaline seminal fluid; and in the case of cancer lung it is the alkaline cigarette smoke.
| 12,456
|
Phenylalanine hydroxylase and tyrosine aminotransferase in human fetal and adult liver.
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The mean value of phenylalanine hydroxylase activity in adult human liver was almost twice as high as that in the fetal ones; no consistent variations were seen with sex, fetal age (between the 11th and 22nd week of gestation), or with hours between delivery and death. The tyrosine aminotransferase levels did not correlate with sex, age, or method of abortion; however, they were 5 times higher in the two fetuses which survived for more than 1.5 hr after delivery. The mean concentration of tyrosine aminotransferase (excluding these two fetuses) was about 15 times lower than in the adult liver. Phenylalanine hydroxylase is known to appear in rat liver on the 20th to 21st day of gestation. Tyrosine aminotransferase, on the other hand, emerges on the first postnatal day and, as shown here, can be evoked by premature delivery. Thus, in man as in the rat, (1) phenylalanine hydroxylase approaches physiologically significant levels at an earlier development stage than does tyrosine aminotransferase and (2) extrauterinization stimulates the synthesis of tyrosine aminotransferase but not of phenylalanine hydroxylase. Speculation There is a greater analogy than is usually assumed between human and rat liver with respect to the time schedule of enzymic differentiation and the factors which regulate it.
| 12,495
|
Failure of parathyroid hormone and cyclic AMP to inhibit renal carbonic anhydrase.
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It has been suggested that the parathyroid hormone and cyclic AMP produce their bicarbonaturic effects through inhibition of renal carbonic anhydrase. In the present study, the incubation of renal carbonic anhydrase with parathyroid hormone or cyclic AMP in presence of ATP, Mg++ and K+ ions, did not produce any inhibition of the enzyme when the pH of the solution was maintained above 7. It is concluded, that parathyroid hormone and cyclic AMP produce urinary bicarbonate excretion by a mechanism independent of carbonic anhydrase inhibition.
| 12,496
|
Implications of electrostatic potentials on ribosomal proteins.
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Potentiometric studies of ribosomal particles 30S, 50S, and 70S, were designed to investigate possible implications of the electrostatic potentials developed by the 16S and 23S rRNA fractions. Release of protons and proton titrations of these ribosomal fractions were examined as a function of Mg2+ and K+ concentrations. The effects of these cations fit the polyelectrolyte theory remarkably well and are discussed accordingly.
| 12,498
|
Effects of pyrroxan and chlordiazepoxide on biogenic amine metabolism in the rat brain.
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Pyrroxan (20 mg/kg, i.p.), a new potential antianxiety agent, increased brain norepinephrine (NE) turnover in rats, reflecting a possible central alpha-adrenergic receptor blocking activity. In contrast, chlordiazepoxide (20 mg/kg, i.p.), a widely used antianxiety agent, did not alter the NE turnover. Pyrroxan did not affect overall DA turnover although it did appear to accelerate DA turnover initially. The initial potentiation of DA turnover may indicate a short-lasting blocking action on DA receptors. In comparison, chlordiazepoxide (20 mg/kg, i.p.) decreased the turnover rate of DA. Effects of both drugs on 5-HT indicate a decrease in turnover with no significant monoamine oxidase activity or blockade of the 5-HT reuptake mechanism. Both drugs antagonized the decline in intraventicularly-injected 14C-5-HT. Neither drug caused consistent changes in endogenous 5-HT, 5-hydroxyindoleacetic acid, or tryptophan levels. Neither drug potentiated the behavioral effects of L-Dopa nor increased the 5-HTP behavoiral syndrome in the mouse. Pyrroxan may be expected to exhibit a spectrum of activity between that of minor and major tranquilizers, characterized by antianxiety action together with sedative or tranquilizing activity.
| 12,528
|
Stages of bone marrow transplantation: a psychiatric perspective.
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Patients undergoing bone marrow transplantation were closely followed by a psychiatric service functioning as part of a multidisciplinary team. A somewhat predictable pattern of psychological reactions to the stress of various stages of the procedure appeared to emerge. Approaches to patient evaluation, typical patient responses, and suggestions for working with these patients and their families are described.
| 12,531
|
Participation of leukemia cells in immune responses.
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Cells of a transplantable lymphoid leukemia of mice were tested in vivo and in vitro to see which features of normal lymphoid cells were retained in spite of malignant transformation and lack of growth control. Leukemia cells phagocytosed, adhered to glass, possessed receptors for immunoglobulin, participated in the immune response against SRBC (probably by amplifying a normal response through attachement of antibodies on their surfaces), became recruited into inflammatory reactions elicited by grafting allogeneic of syngeneic skin, and apparently joined graft-versus-host and host-versus-graft reactions, contributing toward damage of hemopoietic target tissues.
| 12,544
|
Microcalorimetric measurements of heat production in human erythrocytes. III. Influence of pH, temperature, glucose concentration, and storage conditions.
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Heat production in human erythrocytes has been measured under different conditions of pH, glucose concentration, and temperature. Storage conditions have also been varied. The erythrocytes, which were from healthy subjects, were suspended either in autologous plasma or in phosphate buffer. The heat effect, P, was shown to increase linearly in the physiological pH range: 1.2% per 0.01 pH unit. Variation of the glucose concentration within a wide range, 3-32 mmol/1, did not affect the P value. The temperature coefficient for P was determined to be Q10 = 2.8 for the temperature range 32-42 degrees C. A constant energy of activation was found, 82.6 kJ/mol, for the temperature range 25-42 degrees C. When the erythrocytes were stored at 4 degrees C, P values (measured at 37 degrees C) increased initially by 6%/h. After 24 h of storage P was about 50% higher than the initial value. Determinations of glucose consumption were made in parallel with most of the calorimetric experiments.
| 12,557
|
Acid-base determinations in normal and asphyxiated term infants during the first 24 hours of life.
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Vigorous term infants who are born normally initially have a moderate metabolic and respiratory acidosis which is corrected by the time the infant is 6 hours old. Asphyxiated infants consistently show a greater degree of acidosis, both metabolic and respiratory. Caesarean section results in higher pCO2 values, especially when 'diffusion apnoea' occurs. Indications for the correction of acidosis in asphyxia are proposed.
| 12,578
|
Chemical studies of marine invertebrates. XXIII. A novel polyhydroxylated sterol from the soft coral Litophyton viridis (Coelenterata, Octocorallia, Alcyonacea).
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The structure of 24-methylenecholest-5-en-3beta,7beta,19-triol (II) isolated from the soft coral Litophyton viridis, has been established by X-ray diffraction analysis. The compound is accompanied by its 7-monoacetate derivative.
| 12,598
|
Induction of increased graft-versus-host disease by mouse spleen cells sensitized in vitro to allogeneic tumor.
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The aim of our study was to sensitize cells in vitro, follow their proliferative and cytotoxic responses, and determine their ability to cause lethal graft-versus-host disease (GVHD). C57BL/6 (H2b) spleen cells were incubated with irradiated BALB/C (H2d) Moloney lymphoma cells (LSTRA) in mixed leukocyte culture conditions for 2, 4, or 6 days and then tested. The maximal proliferative response occurred after 4 days. In vitro cytotoxic reactivity against 51Cr-labeled LSTRA was generated by 4 days (76.3+/-3.1% 51Cr released) and 6 days (133.0+/-4.8%) of sensitization but not by 2 days (-0.2+/-1.1%). Induction of fatal GVHD was assayed by injecting graded doses of the C57BL/6 spleen cells i.v. into adult BALB/c mice pretreated with cyclophosphamide, 180 mg/kg. Cells sensitized for 2 days were effective but no more so than were (control) cells cultured with irradiated C57BL/6 spleen cells. However, cells sensitized longer were far more active than the control cells. Cells sensitized for 4 days killed 70 of 88 mice (80%), and those sensitized for 6 days killed 37 of 48 mice (77%), whereas control cells killed only 42 of 90 mice (47%) (P less than 0.005). Thus, cells sensitized in vitro exhibited an increased ability to induce GVHD in vivo, which was temporally associated with the development of cytotoxicity in vitro.
| 12,600
|
Hyperlactatemia and hemolysis in G6PD deficiency after nitrofurantoin ingestion.
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A 69-year-old man with glucose-6-phosphate dehydrogenase deficiency was treated with nitrofurantoin for pyuria. Four days later he presented with metabolic acidosis due to excess lactic acid, a decline in curculating hemoglobin, reticulocytosis, elevated serum transaminase levels, and hyperbilirubinemia. The drug was withdrawn and the hyperlactatemia subsided in three days without specific treatment. In vitro, nitrofurantoin is capable of stimulating erythrocyte glucose utilization aand lactate production, and inhibiting the generation of reduced glutathione. In vivo, this drug is capable of producing hemolysis in susceptible subjects and hepatocellular injury. The temporal proximity of drug ingestion and hemolysis, increased glucose utilization, lactate excess, and hepatic insufficiency suggests that nitrofurantoin may have been responisble for precipitating the clinical and chemical abnormalities observed.
| 12,659
|
[Salvage of a patient with respiratory distress caused by tracheal obstruction, by use of a Fogarty catheter].
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The author observed a state of acute asphyxia due to a mucosal plug in a patient undergoing total laryngectomy. After failure of classical methods of removal and the plug and in view of the critical state of the patient, a heroic procedure was used: extraction of the mucosal plug using a Fogarty catheter, as used in arterial surgery.
| 12,693
|
[Difficult intubations and proposed solutions. Intubation by fiberscopy].
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After a review of the various techniques used in difficult intubations, the authors emphasize recent progress in the field of fiber endoscopy. The advantages of this technique, e.g. absence of trauma, increased field of exploration and reduction in dose of anaesthetic drugs, exceed the present disadvantages, e.g. high price of this material, relatively fragile apparatus, too long and diameter too great for use in children.
| 12,701
|
[Sterilization of intratracheal tubes].
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After a brief review of classical and modern methods of sterilisation of endo-tracheal catheters, where they emphasize the dangers of the use of ethylene oxide, the authors recall the common procedure which they used: washing with water and soap, and soaking for 6 to 7 hours in formaldehyde or in a solution of quaternary ammonium salts, and all manipulations should be made using gloves.
| 12,705
|
[Glycosyltranferases. Biological and pathological importance].
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Catalysing the transfer of oses and ose derivatives on various accepters, glucosyltransferases are of increasing importance in biology and pathology. Their sub-cellular localisation is now known together with the physico-chemical parameters of their activity and the importance of polyprenic intermediates. The first phenomenological studies concerning them are in favour of a mechanism of Bi-Bi type. For example, they may play a role in mucoviscidosis, virus diseases, vaccination and arthrosis.
| 12,708
|
Diffusion coefficients for protein molecules in blood serum.
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A new technique is described for the measurement of the self-diffusion coefficients of protein macromolecules in solution. The method makes use of the phenomenon of Taylor dispersion of a solute introduced into a solvent flowing in the laminar regime through a tube of circular section. Results are reported for the self-diffusion coefficient of cholesterol associated with lipoprotein molecules in dogs' serum at pH 7.4 in the temperature range 18-37 degrees C. The diffusivity of bovine serum albumin in serum has also been studied as a function of temperature at pH 7.4 and 4.7. In the more basic solution, measurements of the diffusivity as a function of protein concentration substantially agree with earlier work. For all the systems studied the diffusivity varies rapidly with temperature. The pH of the solution, in the case of bovine serum albumin, also has a significant effect on the diffusivity of the macromolecule. The latter observation is related to the amount of water bound to the protein molecule in solution.
| 12,775
|
Characterization of the acetyl-CoA synthetase of Acetobacter aceti.
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The acetate activating system of Acetobacter aceti has been studied. The enzyme responsible, acetyl-CoA synthetase, has been purified about 500-fold from crude cell extracts and was approximately 85% pure as judged by polyacrylamide gel electrophoresis in sodium dodecyl sulphate. The purified enzyme showed optimal activity at pH 7.6 in both Tris-HCL and potassium phosphate buffers. In its purest form, the enzyme was stable at 4 degrees-C but denatured upon freezing. The Km values for CoA, ATP and acetate were found to be 0.104 mM, 0.36 mM and 0.25 mM respectively; propionate and acrylate were also activated by the enzyme but not butyrate, isobutyrate or valerate. GTP, UTP, CTP and ADP could not replace ATP in the reaction, and cysteine or pantetheine failed to replace CoA. The cationic requirements were studied and of the divalent cations tested, only Mn2+ could significantly replace Mg2+ in the reaction; K+ and NH4+ stimulated enzyme activity but inhibited at high concentrations; Na+ was a poor activator, but did not inhibit at higher concentrations. The effect of a number of glucose and other metabolites on enzyme activity has been tested.
| 12,800
|
Thermoplasma acidophilum: intracellular pH and potassium concentration.
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Thermoplasma acidophilum is a free-living thermophilic mycoplasma. Although the organism lacks a cell wall, it can grow in medium as dilute as 66 mosM. The intracellular K+ concentration can be as low as 17 mM, but varies according to the osmolality of the culture medium. The internal pH can be measured by taking advantage of the fact that T. acidophilum undergoes lysis when the pH is adjusted to neutrality. Thus, by appropriate analysis of titration curves, it is possible to conclude that the internal pH is near 5.5. This result was confirmed by a second type of experiment in which the internal pH was analyzed by rupturing the cells in a French Pressure Cell.
| 12,804
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Influence of 8-substitutes on the oxidation of hypoxanthine and 6-thioxopurine by bovine milk xanthine oxidase.
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1. The influence of 8-substituents was studied on the rate of oxidation of hypoxanthine and 6-thioxopurine by bovine milk xanthine oxidase (EC 1.2.3.2). 2. An 8-methyl group does not alter the rate of oxidation of hypoxanthine materially, but an 8-phenyl substituent reduces it markedly. This is ascribed to inhibition of the tautomerisation process, responsible for substrate activation, prior to oxidation. 3. In contrast, the 8-phenyl group in 3-methyl-8-phenylhypoxanthine enhances the rate, presumably by binding to a hydrophobic site near the enzymaic center. 4. An 8-phenyl group in 6-thioxopurine markedly increases the rate of enzymaic oxidation. Probably the aromatic substituent diverts anion formation to the imidazole ring. In contrast, ionisation of 8-methyl-6-thioxopurine involves the pyrimidine moiety, thus rendering enzymic attack at position 2 more difficult.
| 12,828
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Purification and properties of acid phosphatases isolated from Owenia fusiformis.
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Acid phosphatase (EC. 3.1.3.2) has been separated by molecular sieving into two fractions and these fractions were purified by Sephadex ion-exchange chromatography. One of the purified enzymes (fraction II) was purified 830 fold and had a specific activity of 34 international units per mg protein at 37 degrees C and at a pH of 4.9. The Km value with p-nitrophenylphosphate as substrate was 9.10(-4) M and the kinetic studies showed no possibilities of control by allosteric transitions, and no effect of metabolites (amino acids) on the reaction velocity.
| 12,839
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Looking both ways. Presidential address delivered at British Institute of Radiology Annual Congress-9th April 1976.
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The address looks backward over the progress made in the techniques of radiology--both diagnosis and therapy--over the past 30 years and forward to the possibilities which lie ahead. It draws attention to the continuing need for basic research as the source from which practical advances spring, illustrating this from the development of radiosensitizing drugs. Finally, it emphasized the importance of the Institute as an interdisciplinary forum in the present era of rapid technological advance.
| 12,849
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New sugars from antigenic lipopolysaccharides of bacteria: identification and synthesis of 3-O-[(R)-1-carboxyethyl]-L-rhamnose, an acidic component of Shigella dysenteriae type 5 lipopolysaccharide.
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A new acidic sugar, 3-O-[(R)-1-carboxyethyl]-L-rhamnose (1), has been identified as a constituent of the O-antigenic lipopolysaccharide of Sh. dysenteriae type 5. The structure of 1 has been established by physico-chemical methods and by synthesis. Alkylation of methyl 2,5-di-O-benzyl-alpha-L-rhamnofuranoside (6) with (S)- or (R)-2-chloropropionic acids, followed by removal of the protecting groups, afforded 3-O-[(R)-1-carboxyethyl]-L-rhamnose (9) and 3-O-[(S)-1-carboxyethyl]-L-rhamnose (10), respectively. The properties of 1 coincide with those of 9.
| 12,866
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Enzymatic assay of total cholesterol in serum or plasma by amperometric measurement of rate of oxygen depletion following saponification.
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A method for serum or plasma cholesterol assay involving amperometric measurement of the rate of oxygen depletion in the cholesterol oxidase-catalyzed oxidation of cholesterol is described. The hydrolysis of the serum cholesterol esters is accomplished by saponification of 50 mul of sample with 0.2 ml of ethanolic KOH (1.0 mol/1) containing 0.5% Triton X-100 for 5 min at 75 degrees C. The rate of oxygen consumption in a 25-mul aliquot of this is measured with a Clark electrode in a Beckman Glucose Analyzer and the assay takes about one minute after incubation; results are read digitally on the instrument. The analyzer cell contains 1 ml of 1 M phosphate buffer, pH 7.4, with 100 mg sodium cholate/100 ml and 0.1-0.2 U cholesterol oxidase.
| 12,891
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Translation of mRNA from rat-liver polysomes into tyrosine aminotransferase and tryptophan oxygenase in a protein-synthesizing system from wheat germ. Effects of cortisol on the translatable levels of mRNA for these two enzymes.
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Messenger RNA was isolated from rat liver polysomes by phenol/chloroform extraction and subsequent oligo(dT)-cellulose chromatography. The mRNA was translated in a protein-synthesizing system in vitro derived from wheat germ. The system was optimized in respect to Mg2+ and K+. The presence of spermidine or spermine is necessary for the synthesis of polypeptides having molecular weights of over 20 000. In the absence of the bases only small molecular weight products are formed. The amount of protein synthesized is linearly dependent on the amount of mRNA added up to concentrations of 80 mug mRNA/ml. The synthesis of tyrosine aminotransferase and tryptophan oxygenase in the system in vitro has been demonstrated by specific immunoprecipitation and sodium-dodecylsulfate polyacrylamide gel electrophoresis of the precipitate with enzyme proteins as marker. The amount of specific product formed is linearly dependent on the amount of mRNA present. The amount of translatable tyrosine aminotransferase mRNA and tryptophan oxygenase mRNA increases after administration of hydrocortisone to adrenalectomized rats. At low doses of hormone (2 mg/100 g body weight) maximal values are observed at 4 h, control levels being reached at 6-8 h after hormone application. With higher doses of hydrocortisone (20 mg/100 g body weight) maximal values are attained at 6 h, tending to control levels 14 h after treatment. The enzyme activity curves are parallel to the mRNA curves, the peak of enzyme activity occurring 2 h after the peak of mRNA activity.
| 12,944
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Biosynthesis of peptidoglycan in Gaffkya homari. The incorporation of peptidoglycan into the cell wall and the direction of transpeptidation.
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Wall membrane enzyme preparations from Gaffkya homari catalyze the formation of peptidoglycan from the precursor pairs: UDP-N-acetylglucosamine + UDP-N-acetylmuramyl-pentapeptide (UDP-MurNAc-Ala-DGlu-Lys-DAla-DAla) and also from UDP-N-acetylglucosamine + UDP-N-acetylmuramyl-tetrapeptide (UDP-MurNAc-Ala-DGlu-Lys-DAla). Part of the reaction products is soluble in 2% sodium dodecylsfulfate whereas the other part is bound to pre-existing cell wall peptidoglycan. The incorporation into cell wall takes place by a transpeptidation reaction in which the D-alanyl-D-alanine sequences in the pre-existing cell wall function as donors and the epsilon-amino groups of the lysine residues in the newly synthesized peptidoglycan strands function as acceptors. Nepsilon-D-Alanyl-lysine linkages are formed. At saturating concentration of UDP-N-acetylglucosamine, the enzyme system exhibits similar apparent Km values (30--80 muM) for UDP-MurNAc-pentapeptide and UDP-MurNAc-tetrapeptide both for the formation of cell-wall bound peptidoglycan and total (i.e. soluble + cell-wall-bound) peptidoglycan. The V values are also in the same order of magnitude (270-650 pmol x min-1 x mg of protein -1). However, UDP-MurNAc-tetrapeptide was a slightly better substrate than UDP-MurNAc-pentapeptide for the formation of cell-wall-bound peptidoglucan. The synthesis of total and cell-wall-bound peptidoglycan from UDP-MurNAc-pentapeptide was competitively inhibited by UDP-MurNAc-tetrapeptide and vice versa. UDP-MurNAc-tripeptide and both UDP-Mur-NAc-pentapeptide and UDP-Mur-NAc-tetrapeptide in which the epsilon-amino group of the lysine residue was substituted by an acetyl group were utilized less efficiently than UDP-MurNAc-pentapeptide and UDP-MurNAc-tetrapeptide for the formation of soluble peptidoglycan; they were exceedingly poor substrates for the formation of cell-wall-bound peptidoglycan.
| 12,946
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Efficient purification and molecular properties of spinach chloroplast fructose 1,6-bisphosphatase.
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A relatively straightforward procedure has been developed for the purification of chloroplast fructose bisphosphatase from spinach leaves to apparent homogeneity and with 80% yield. The molecular weight of the enzyme was about 160 000. Chloroplast fructosebisphosphatase consists of four possibly identical subunits and, at pH 8.8, EASILY DISSOCIATES INTO EQUAL HALVES WITH LOWered activity. Sigmoid saturation curves with Hill coefficients between 3.0 and 3.7 were obtained for fructose 1,6-bisphosphate and Mg2+. Incubation of the enzyme with 20 mM dithiothreitol slowly altered the response to pH from no activity measured at pH 7.5 and full activity at pH 8.8 to equal activity at each of these pH values; at the same time the number of freely available sulphydryl groups increased from four to twelve per molecule. These properties are considered in the context of the observed activation of this enzyme following illumination of chloroplasts.
| 12,949
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Studies on 3-deoxy-d-arabinoheptulosonate-7-phosphate synthetase(phe) from escherichia coli k12. 3. Structural studies.
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1. Investigations with structural analogues of phenylalanine indicated an absolute requirement for the aromatic ring and both the alpha-carboxyl and alpha-amino groups of phenylalanine for inhibition of 3-deoxy-D-arabinoheptulosonate-7-phosphate synthetase(phe) activity. Replacement of the alpha-H atom with a methyl group does not decrease the inhibition greatly. Varying degrees of inhibition were observed with o, m and p mono-substituted fluoro, chloro and hydroxy phenylalanines. D-Phenylalanine and several metabolites of the aromatic biosynthetic pathways do not inhibit enzymic activity. 2. Circular dichroism studies indicated that the native enzyme possesses approximately 26% alpha-helix. Both circular dichroic and ultraviolet difference spectra indicated that the addition of phenylalanine to the synthetase induces a conformational change involving a small alteration of the secondary structure and large alterations in th interactions of some of the aromatic residues of the enzyme. In particular, a tryptophan residue moves from an extremly hydrophobic environment to one less hydrophobic. 3. Kd for the binding of phenylalanine to the enzyme was determined spectrophotometrically to be 75 muM. 4. Chemical modification studies suggested that a sulphydryl group and possibly a lysine residue may be implicated in the catalytic activity of the enzyme.
| 12,953
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Electron spin resonance investigations of mitochondrial electron transport in Neurospora crassa. Characterization of paramagnetic intermediates in a standard strain.
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1. Submitochondrial particles from Neurospora strain inl-89601 have been analyzed by electron spin resonance spectroscopy (ESR). Numerous signals due to iron-sulfur proteins are observed at low temperatures. Analysis of these ESR signals at various temperatures allows the assignment of resonances to iron-sulfur centers 1-5 that have been described in other organisms. There are no discrepancies between the signals seen in Neurospora and those described in other organisms and it is likely that Neurospora mitochondria contain the same iron-sulfur centers that are observed elsewhere. 2. NADPH and NADH act to reduce the iron-sulfur centers of respiratory complex I. 3. The drug pyrrolnitrin [3-chloro-4-(2'-nitro-3'-chlorphenyl)pyrrole] is an effective inhibitor of both NADH-supported and succinate-supported electron transport in Neurospora. 4. Analysis of pyrrolnitrin inhibition curves, respiration studies, ESR spectra, and the steady-state level of reduction of cytochrome b in the presence and absence of the drug shows that pyrrolnitrin acts to inhibit electron transport in Neurospora mitochondria at multiple sites in the region between ubiquinone and cytochrome b.
| 12,965
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Cyclic nucleotide hydrolysis in the thyroid gland. General properties and key role in the interrelations between concentrations of adenosine 3':5'-monophosphate and guanosine 3':5'-monophosphate.
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Phosphodiesterase activities of horse (and dog) thyroid soluble fraction were compared with either cyclic AMP (adenosine 3':3'-monophosphate) or cyclic GMP (guanosine 3':5'-monophosphate) as substrate. Optimal activity for cyclic AMP hydrolysis was observed at pH 8, and at pH 7.6 for cyclic GMP. Increasing concentrations of ethyleneglycol bis(2-aminoethyl)-N,N'-tetraacetic acid inhibited both phosphodiesterase activities; in the presence of exogenous Ca2+, this effect was shifted to higher concentrations of the chelator. In a dialysed supernatant preparation, Ca2+ had no significant stimulatory effect, but both Mg2+ and Mn2+ increased cyclic nucleotides breakdown. Mn2+ promoted the hydrolysis of cyclic AMP more effectively than that of cyclic GMP. For both substrates, substrate velocity curves exhibited a two-slope pattern in a Hofstee plot. Cyclic GMP stimulated cyclic AMP hydrolysis, both nucleotides being at micromolar concentrations. Conversely, at no concentration had cyclic AMP any stimulatory effect on cyclic GMP hydrolysis. 1-Methyl-3-isobutylxanthine and theophylline blocked the activation by cyclic GMP of cyclic GMP of cyclic AMP hydrolysis, whereas Ro 20-1724 (4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone), a non-methylxanthine inhibitor of phosphodiesterases, did not alter this effect. In dog thyroid slices, carbamoylcholine, which promotes an accumulation of cyclic GMP, inhibits the thyrotropin-induced increase in cyclic AMP. This inhibitory effect of carbamoylcholine was blocked by theophylline and 1-methyl-3-isobutylxanthine, but not by Ro 20-1724. It is suggested that the cholinergic inhibitory effect on cyclic AMP accumulation is mediated by cyclic GMP, through a direct activation of phosphodiesterase activity.
| 12,974
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Comparison of adiphenine and TRH effects on TSH release by rat pituitary in vitro.
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The mechanism of action of adiphenine on in vitro rat anterior pituitary TSH release was compared to that of the physiological stimulator TRH. The comparative study showed that adiphenine and TRH were able to increase TSH release in a dose-dependent manner, had similar time courses of action for equipotent stimulating concentrations and produced similar aspects of stimulated TSH cells. However, there were several differences between the effects of adiphenine and TRH. Adiphenine action was inhibited by 20 mM K+; was not calcium dependent; was inhibited by neither thyroid hormones nor somatostatin; was little affected by energy depression. It is concluded that adiphenine probably acts near the ultimate steps of the TSH release pathway and could be a useful pharmacological tool for studying the mechanism of TSH release.
| 12,985
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A comparison of laparoscopy and culdoscopy for internal sterilization.
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In recent years, the increased demand for sterilization by women who have achieved their desired family size has emphasized the need to improve both existing methods of tubal occlusion and the means of access to the Fallopian tubes. Utilization of diagnostic instruments such as the laparoscope and culdoscope to perform sterilization minimizes the trauma associated with standard laparotomy and colpotomy and promises to reduce morbidity occurring as a result of sterilization. In order to evaluate and compare the improved techniques of laparoscopy and culdoscopy for elective interval sterilization, 722 women were studied between January and August of 1973 at the Siriraj Hospital in Bangkok. For 279 patients (Group I), sterilization was performed by culdoscopic tubal ligation using a modified Pomeroy technique; for 443 patients (Group II), the procedure used was laparoscopic tubal cauterization and cutting. All procedures were performed using local anesthesia on an outpatient basis. Complication rates and required surgical time were similar for both procedures and compared favorably with rates reported by other investigators. Because of a low incidence of complications and the elimination of the need for general anesthesia and hospitalization, both endoscopic procedures appear to be of particular value in developing countries where hospital facilities and physician time are in short supply.
| 13,007
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Ritodrine hydrochloride induced cardiopulmonary and placental hemodynamic changes in normal and hypertensive late pregnancy.
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Cardiopulmonary parameters (minute volume, heart rate, stroke volume, right heart, pulmonary and left heart blood volumes), blood pressure and placental blood flow were evaluated in 20 normal patients, nine patients with preeclamptic disease and 12 with essential hypertension in late pregnancy before and 60 minutes after a single i.m. dose of 10 mg of ritodrine hydrochloride. The drug caused a statistically significant increase in heart rate in all the patient groups, while the systolic and diastolic blood pressures were only slightly affected. Minute volume was unchanged in the group of normal patients, but in both hypertensive groups there was a significant increase. The placental perfusion index was statistically nearly significantly decreased in the group of uncomplicated pregnancies, statistically significantly increased in preeclamptic patients, and not affected in the group with essential hypertension. Ritodrine hydrochloride medication can be expected to have a positive effect on placental blood flow only in preeclamptic disease, and then probably in the milder forms of the disease.
| 13,017
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Terminal deoxynucleotidyl transferase as a biological marker for human leukemia.
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High levels of terminal deoxynucleotidyl transferase have been observed in leukocytes of 7 out of 20 patients with chronic myelogenous leukemia in acute blast phase of the disease. These levels are comparable to the levels observed in human and calf thymus gland and cell lines with some T cell characteristics (Molt 4 and 8402). Negligible levels of this activity were observed in chronic myelogenous leukemia not in an acute blast phase of the disease, chronic lymphocytic leukemia, human B cells, mature T cells, and the mixed population of lymphocytes present in normal human blood. The detection of this enzyme in some patients with chronic myelogenous leukemia in acute blast phase of the disease suggests that the blast proliferation may involve primitive stem cells which have more lymphoid than myelogenous characteristics. This enzyme assay may be of use as a biological marker for following patients during treatment and in remission.
| 13,027
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Role of urinary solutes in natural immunity to gonorrhea.
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Natural resistance of the male urethra to gonococci has not been explained by classical immune mechanisms but could result from antibacterial properties of urine. Accordingly, we measured survival in midmorning urine of 10(7) F-62 T2 gonococci per ml by serial dilutions and plate counts. Fifteen killer urines from eight people all killed greater than 3 logs (average, 5.3), and 13 of 15 were sterilized. Fourteen nonkiller (inhibitor) urines from seven subjects allowed no growth. Killer urines were more acidic (pH 5.4 versus 6.4) and more concentrated (861 versus 717 mosmol/kg) than nonkillers. Upon addition of hydrogen ion, urea, and sodium chloride to urines and broth, pH proved to be the major killing factor, but urea and NaCl were also bactericidal. Susceptibility to urine bactericidal power did not vary with colony type (T2 versus T4) or strain (F-62 versus two fresh isolates). Killing was rapid (0.5 to 3 h) and not bacteriolytic. Escherichia coli multiplied 10-fold in urines that inhibited growth of gonococci. Thus, the bacteriostatic effect of urine may explain why gonococci do not infect the bladder and kidney during gonorrhea. The bactericidal properties of urine may contribute to resistance against gonococcal urethritis.
| 13,038
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Adenosine triphosphate catabolism in homogenates of rat secretory enamel organs incubated in histochemical lead media.
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To investigate how lead, when used as trapping agent, influences the ATP hydrolysis and to study how ATP is catalyzed in histochemical systems, homogenized secretory enamel organs were incubated in histochemical [3H]-ATP media. Aliquots from the media were taken after 3, 10, 20 and 30 min, the ATP and formed metabolites were separated by electrophoresis and radiometrically quantitated. In media lacking both lead and homogenate 2% of the ATP was spontaneously hydrolyzed during 30 min incubation at room temperature. The presence of lead caused an additional 8% hydrolysis at pH 7.2 and an additional 20% hydrolysis at pH 9.4. In the presence of homogenate, however, lead caused a net decrease of the hydrolysis of ATP as well as of ADP and AMP. This enzyme inhibition varied from around zero to some 80%, depending on pH and substrated involved. In homogenate-containing lead media, at both pH 7.2 AND 9.4, ATP was rapidly hydrolyzed primarily to ADP and subsequently to AMP and adenosine and/or inosine. After 5--10 min ADP constituted the predominant substrate at both pH:s. At pH 7.2 ADP remained so for the rest of the incubation, whereas at pH 9.4 AMP was predominant substrate at the end of the incubation. AMP was the finan catabolic product in experiments at pH 7.2, and adenosine and/or inosine at pH 9.4. Inorganic phosphate was liberated almost linearly during the whole incubation period. The results indicate that histochemical studies of substrate specific ATP-ases should be performed with short incubation times and, when high specific activities are present, in large quantities of incubation media to reduce interference by ADP and AMP hydrolyzing enzymes.
| 13,054
|
Rhodanese from Thiobacillus A2: catalysis of reactions of thiosulphate with dihydrolipoate and dihydrolipoamide.
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Rhodanese (thiosulphate:cyanide sulphurtransferase EC.2.8.1.1) was purified 25- to 30-fold from thiosulphate-grown Thiobacillus A2. It exhibited a pH optimum between pH 10-2 and 10-4 and apparent Km values of 0-36 mM-Na2S2O3 and 17 mM-KCN. Ultraviolet spectrophotometry and thin-layer chromatography showed that the enzyme catalysed the reaction of S2O3(2-) with dihydrolipoic acid or dihydrolipoamide, producing alpha-lipoate or lipoamide, with the intermediate production of the persulphides of dihydrolipoate and dihydrolipoamide, which were demonstrated chromatographically. This is the first demonstration of catalysis by a thiobacillus rhodanese of reactions which are likely to be physiologically important in the oxidative dissimilation of thiosulphate by a central energy-conserving pathway.
| 13,142
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Regulation of the tricarboxylic acid cycle and poly-beta-hydroxybutyrate metabolism in Azotobacter beijerinckii grown under nitrogen or oxygen limitation.
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Azotobacter beijerinckii was grown in ammonia-free glucose/mineral salts media in chemostat culture under oxygen or nitrogen limitation. Selected enzymes of the tricarboxylic acid cycle and poly-beta-hydroxybutyrate metabolism were monitored in relation to oxygen supply for both steady and transition states. Two dissolved oxygen concentrations were used for the nitrogen-limited steady state to investigate the possible effects of respiratory protection of nitrogenase on these enzymes. The levels of NADH oxidase, isocitrate dehydrogenase and 2-oxoglutarate dehydrogenase increased markedly on relaxation of oxygen limitation while pyruvate dehydrogenase and citrate synthase were relatively unaffected. beta-Ketothiolase and acetoacetyl-CoA reductase levels decreased as oxygen limitation was relaxed. Respiratory activity, as measured by the QO2 value, increased with oxygen supply rate. Imposition of oxygen limitation on a nitrogen-limited culture caused an immediate increase in the NADH/NAD ratio but this rapidly readjusted to its previous steady-state value. These changes are discussed in relation to respiratory protection of nitrogenase and poly-beta-hydroxybutyrate metabolism in A. beijerinckii.
| 13,143
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The effect of C.P.A.P. upon pulmonary reserve and cardiac output under increased abdominal pressure.
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The cardiopulmonary effects of CPAP under conditions of increased intra-abdominal pressure were studied using the rabbit as an experimental model. Central venous pressure and cardiac output were reduced when the intra-abdominal pressure was increased. Addition of CPAP caused a further reduction in C.V.P. and C.O. Despite these reductions CPAP significantly improved arterial PaO2 without significant effects on pH and PaCO2. The use of CPAP in conditions associated with pulmonary dysfunction secondary to increased intraabdominal pressure may be a definite therapeutic modality.
| 13,172
|
[Treatment of ischemic heart disease with "coronary drugs" (author's transl)].
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The standard treatment of ischemic heart disease consists in the administration of nitrates and beta-sympathicolytic agents. Calcium antagonists are likewise promising. They should be used particularly if beta-sympathicolytic agents are contraindicated. In the beginning special caution should be exercised on combining a beta-sympathicolytic agent with a calcium antagonist. This is best done under clinical supervision since sudden cardiac decompensation, extreme bradycardia and/or disturbed atrioventricular conduction is to be expected. Today the administration of "coronary dilators" is no longer a part of the standard treatment but can at best be regarded as supplementary therapy.
| 13,298
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Preponderance of beta adrenergic receptors in the gastric fundus of the rat.
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There are two kinds of adrenergic receptors in rat fundus (stomach), the alpha receptors are stimulated with adrenaline and noradrenaline and can be blocked effectively with azapetine and the beta receptors are stimulated with isoprenaline and adrenaline and can be blocked effectively with propranolol. Adrenaline, noradrenaline and isoprenaline all produce inhibition of acetylcholine induced contractions in both untreated and reserpinized tissues that can be antagonized with azapetine and propranolol on its specific receptors but propranolol has a greater capacity to decrease the sensitivity of both untreated and reserpinized tissues to isoprenaline and adrenaline than azapetine can in case of noradrenaline and adrenaline.
| 13,339
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Recommending coronary artery surgery: refining judgement through application of new knowledge.
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An analysis is made to help decide on the best form of treatment for atherosclerotic coronary disease. Available data on surgical treatment are reviewed with emphasis on prognosis and management of the patient with stable angina.
| 13,356
|
Rhodopsin in model membranes: charge displacements in interfacial layers.
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A model membrane was developed in which interfacial layers of rhodopsin were reoriented onto one side of a thin Teflon film separating two aqueous compartments. Flashes evoked fast photoelectric signals (1 ms) that originated from capacitative charge displacements of oriented rhodopsin upon bleaching. The photoelectric responses of rhodopsin in the model membrane are compared with the early receptor potential of photoreceptor cells; it is concluded that the signals in both systems originate from the same mechanism.
| 13,363
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Intramolecular general base-catalyzed ester hydrolyses by the imidazolyl group.
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Intramolecular general base catalysis by the imidazolyl group was found in the hydrolyses of endo-5-[4;(5')-imidazolyl]-bicyclo[2.2.1]hept-endo-2-yl trans-cinnamate and endo-5-[4'(5')-imidazolyl]bicyclo[2.2.2]oct-endo-2-yl trans-cinnamate in which the imidazolyl and trans-cinnamoyl groups are bound in close proximity to each other by rigid bicyclic rings. The rate constants for the intramolecular general base-catalyzed hydrolyses at 60 degrees are 6.4 X 10(-7) sec-1 for the former and 1.8 X 10(-7) sec-1 for the latter and the deuterium oxide solvent isotope effects are 3.0 for both. On the other hand, no intramolecular catalytic participation of the imidazolyl group was observed in the hydrolyses of the endo-exo isomers, exo- 5-[4'(5')-imidazolyl]bicyclo[2.2.1]hept-endo-2-yl trans-cinnamate and endo-5[4'(5')-imidazolyl]bicyclo[2.2.2]oct-exo-2-yl trans-cinnamate, in which the imidazolyl groups are located far from the trans-cinnamoyl groups. Intramolecular general base-catalyzed hydrolyses by the imidazolyl groups in endo-5[4'(5')-imidazolyl]bicyclo[2.2.1]hept-endo-2-yl trans-cinnamate and endo-5-[4'(5')-imidazolyl]bicyclo[2.2.2]oct-endo-2-yl trans-cinnamate can serve as models of serine esterase-catalyzed hydrolyses.
| 13,364
|
Inhibitors of genetic recombination in pneumococci.
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Treatment of transformable pneumococci with DNA-intercalating agents shortly after the uptake of DNA molecules inhibited the appearance of genetic transformants. The same drug treatments applied 20 min after DNA uptake were ineffective. Ethidium bromide, proflavin, daunomycin, actinomycin D, and platinum red were found to be effective inhibitors. Donor DNA molecules reisolated from the drug-treated bacteria appeared to be associated with the resident DNA in an abnormal manner, and they had only poor transforming activity.
| 13,367
|
Effects of L-prolyl-L-leucyl-glycine amide (MIF-I) on dopaminergic neurons.
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In an attempt to determine the mechanism of action of L-proly-L-leucyl-glycine amide (MIF-I) in the treatment of Parkinson's disease, various parameters of dopaminergic neuronal function were studied in rats. It was found that the active uptake of 3H-dopamine (3H-DA) by synaptosome-rich homogenates of the striatum of rats treated with MIF-I (1 mg/kg IP X 3, 24 hr intervals) was unaltered 1 hr after final treatment with MIF-I. Also, neither tyrosine hydroxylase nor dopa decarboxylase activity was altered in the striatum and substantia nigra of rats treated with MIF-I (20 mg/kg IP X 3, 24 hr intervals). Thus, vital functional processes associated with dopaminergic neurons apparently are not altered by MIF-I under the conditions studied. These findings illustrate the importance of concurrent DOPA administration in observing an effect of MIF-I on dopaminergic neuronal function.
| 13,412
|
Hypothalamic releasing factors: physiological evidence for a regulatory action on central neurons and pathways for their distribution in brain.
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Recent observations based on single cell recordings obtained in various areas of the brain indicate that TRH, LH-RH and somatostatin have potent effects on the activity of central neurons. There is also electrophysiological evidence for the existence of a system of hypothalamic tuberoinfundibular neurons with widespread extrahypothalamic connections. These connections may indicate possible pathways for the observed widespread distribution of these peptides in the brain. These findings, coupled with behavioral studies and subcellular localization data support the postulate that hypothalamic peptides may have an important role inthe modulation of central neuronal activity.
| 13,416
|
Assembly of a spherical plant virus.
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The conditions previously reported as necessary for the reassembly of spherical viruses have been distinctly unphysiological and such reassembly cannot be related directly to the in vivo reaction. Mild conditions for the in vitro reassembly of cowpea chlorotic mottle virus (CCMV) from its isolated components have now been described (Adolph & Butler 1975) and the reassembled virus characterized. This reassembly involved the co-aggregation of the RNA and protein around neutrality and at ionic strength 0.2, giving yields of 70% encapsidation at pH 6.0. The reaction was independent of temperature over the range 5-25 degrees C and did not require the presence of Mg2+ ions. The reassembled virus shows a stability similar to that of native CCMV, with the same change in sedimentation coefficient around pH 6.5. The molecular mass and buoyant density in CsCl are also the same as those of native CCMV, while the electron microscope reveals a surface morphology on the reassembled particles like that on native CCMV. Analysis of the number-average, mass-average, and Z-average molecular masses of the purified protein at both pH 6.0 and pH 7.5 suggests that the active unit for reassembly is a dimer of the protein subunit.
| 13,422
|
Physiological viewpoints on clinical acid-base diagnostics.
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Acid-base physiology is concerned with sources, extent, and control of hydrogen ion donation in the body, at the organ-physiological as well as the molecular level of study. With the introduction of Van Slyke's methods for quantitative carbon dioxide measurements in biological fluids, one important source of hydrogen ion donation became identifiable; and these and derived methods have permitted of fairly precise quantitative descriptions of transport and pulmonary elimination of carbon dioxide. However, the inevitable operational concept of non-carbonic (non-volatile) contributions to the titratable acidity of the body fluids has been a cause of considerable methodological and conceptual difficulties; and whereas it is now possible by means of the micro-equilibration technique to make accurate assessments of the concentration of non-volatile titratable acid (base) in blood, the question of the physiological relevance of the concept of 'base excess' remains open. In particular, the concept of non-carbonic acid does not possess a specific relevance with respect to the acid-base physiology of kidney, bone, and gastro-intestinal tract comparable to the 'substrate-specificity of carbon dioxide with respect to the lung. Our studies indicate that a subdivision of the titratable non-carbonic acid of any biological medium in two subcomponents will provide an improvement of specificity, adequate for a system physiological approach at the organ level. Thus, a distinction should be made between (1) processes of hydrogen ion donation, reversible by endogenous metabolic means (quantitated in terms of the component MA = metabolizable non-carbonic acid) and (2) processes of hydrogen ion donation associated with gastro-intestinal, skeletal, and renal transport, storage, and control of non-metabolizable non-carbonic acid (NA). Some implications of this distinction for acid-base physiology and acid-base diagnostics are discussed.
| 13,479
|
A review of recent advances in vascular smooth muscle pharmacology.
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An understanding of the physiology of vascular smooth muscle and knowledge of the reaction of such muscle to certain drugs are essential for the development of a means of treating cerebral arterial spasm. The role of cyclic nucleotides in vascular smooth muscle activity is reviewed and possible therapeutic approaches are listed. Probably the safest and most effective treatment would be 1) stimulation of the adenyl cyclase-cyclic adenosine monophosphate system by a beta(2)-adrenergic drug combined with 2) inhibition of the phosphodiesterase system.
| 13,504
|
Arterial blood gas tensions, hydrogen ion, and electroencephalogram during sleep in patients with chronic ventilatory failure.
|
We have studied arterial PO2, PCO2, and hydrogen ion and electroencephalogram during sleep in 10 patients with stable severe chronic respiratory failure. As a group the patients slept badly. Sleep was associated with a worsening of hypoxia and no significant change in PCO2 and H+. Two patients were restudied, receiving oxygen therapy overnight. Both had improved sleep but one, who had an intact hypoxic drive to breathing, developed marked hypercapnia and acidosis when his PO2 was restored to normal during sleep; the other, who had no hypoxic drive to breathing, developed no more hypercapnia or acidosis during sleep when breathing oxygen than when breathing air. Oxygen therapy may improve sleep disturbance in these patients, but its effect on the drive to breathing during sleep should be considered if severe hypercapnia and acidosis are to be avoided.
| 13,511
|
[Histopathological study of the mosquito-bite infiltrate in patients with various underlying diseases and different medications].
|
A histologic study was carried out on tissue-reactions after insect bits in 9 patients with various primary diseases. The clinical and cellular reactions to the bite in the epidermis varied, according to the length, intensity of toxity of the insect bit. The dermal infiltrate was similar in almost all cases and corresponded to a cellular immunologic reaction of the early or late type, as is also to be seen in trichophytin and tuberculin-reactions. Tere was clearly no relationship between the character of the dermal infiltrate and the basic disease. We also found no change in the dermal infiltrate due to special medicaments. Even corticosteroids did not suppress the dermal cellular reactions. There was also a striking absence of eosinophil leucocytes in the dermal infiltrate.
| 13,547
|
[Comparison in vitro between farm-yard manure and liquid manure (author's transl)].
|
Spreading of liquid manure in a grassland ecosystem, stable since a long time when treated with farm-yard manure, brings out a great unbalance in the soil. In comparison of farm-yard manure, the liquid manure involves -- a decrease of C and N in the soil, -- a deterioration of the soil structure, -- a dangerous change in the CEC for K+ and Na+, -- an excessive stimulation of the microflora. In brief, through its composition the liquid manure involves a hyperactivity of the microglora. This heterotropic microflora is particularly mineralizing and breaks down the organic matter. The result is a temporary increase in fertility. But this stimulation of the soil life disbalances the eco-system in which -- the pool of organic matter decreases without replacement, -- the content in Ca++ and Mg++ decreases to the benefit of K+ and Na+.
| 13,589
|
Histochemical studies on the mucins of the vertebrate tongues. VII. Histochemical analysis of mucosubstances in the tongues of some fishes.
|
The tongues of three fishes were investigated histochemically to determine the distribution and nature of mucosubstances by employing recent techniques and the results were considered comparatively with the lingual mucosubstances of other vertebrates. A heterogenous distribution of neutral mucosubstances, sulfomucins and sialomucins in various lingual sites was noted. The taste buds and/or free nerve endings were found to be restricted in the areas containing abundance of goblet cells. In non-gustatory areas of tongue, the goblet cells were very few or absent. Importance of lingual histology in establishing phylogenetic relationships and the possible functional significance of the mucosubstances in the physiology of gustation is discussed in detail.
| 13,596
|
Comparative evaluation of neuromuscular blockade and reversibility of AH 8165 and pancuronium bromide in man.
|
The neuromuscular properties of AH 8165 were compared to those of pancuronium bromide in 66 patients during analgesic anesthesia procedures. Administration of 0.5 mg/kg AH 8165 and 0.04 mg/kg pancuronium bromide produced very similar degrees of non-depolarizing block. AH 8165 acted quicker and therefore gave better conditions for intubation. Spontaneous recovery of muscle twitch tension was slightly shorter for AH 8165 than for pancuronium bromide, whether small or larger amounts of drugs were used. Administration of neostigmine caused rapid and complete return of muscle twitch tension, well-maintained tetanus and insignificant posttetanic potentiation within 20 minutes, with a similar efficiency of competitive neuromuscular block reversal for both drugs.
| 13,601
|
Reduced inactivation of tyrosine aminotransferase in the prefused rat liver in the presence of ethanol.
|
The mode of action whereby alpha-methyltyrosine (alpha-MT) potentiates the behavioural effects induced by catecholamine receptor blocking antipsychotic drugs was investigated in rats trained to lever-press for food on a fixed-ratio 40 schedule of reinforcement. It was found that alpha-MT (20 mg/kg intraperitoneally -- 4 hrs potentiates the effects induced by pimozide (0.04 mg/kg intraperitoneally -- 6 hrs) which preferentially blocks central dopamine (DA) receptors, but not the effects induced by phenoxybenzamine (0.5 mg/kg intraperitoneally -- 30 min.) which blocks central noradrenaline (NA) receptors. Furthermore, the behavioural suppression induced by chlorpromazine (0.5 mg/kg intraperitoneally -- 15 min.), thioridazine (1.5 mg/kg intraperitoneally -- 15 min.), or haloperidol (0.02 mg/kg intraperitoneally -- 15 min.) were not potentiated by the administration of the inhibitor of DA-beta-hydroxylase, bis-(4-methyl-1-homopiperazinylthiocarbonyl) disulfide (FLA-63) 4 mg/kg subcutaneously -- 1 hr). The potentiation by alpha-MT of the clinical effects of antipsychotic drugs and of their behavioural effects in animal experiments is in all probability due to a blockade by alpha-MT of a feed-back mediated compensatory increase in the catecholamine synthesis as a result of a blockade of central NA and/or DA receptors by the antipsychotic drugs. Since, in the present experiments, the behavioural effects induced by drugs which block central DA but not NA receptors were potentiated by the simultaneous administration of alpha-MT, it seemed probable that the disruption of conditioned behaviours by antipsychotic drugs is due to a blockade of central DA receptors. In view of the fact that the ability to selectively disrupt conditioned behaviours is shared by a wide range of antipsychotic drugs differing in chemical structure and also in their mode of action, it is possible that a blockade of DA neurotransmission is also of primary importance for the clinical effects induced by antipsychotic drugs.
| 13,604
|
Cholinergic mechanisms in the learning and memory facilitating effect of caffeine.
|
Experiments are made to train rats in a maze involving memory tests 24 hours and 14 days after training. As it was established in previous studies of the authors, caffeine introduced in low doses (5 mg/kg) 5 min before training facilitates learning and memory. Applied immediately after training, caffeine even in higher doses (20 mg/kg) also improves the memory indices 24 hours and 14 days after the experiment. The anticholinergic agents spasmolytine and scopolamine in higher doses (20 and 2 mg/kg respectively) have a markedly deteriorating effect on learning, while scopolamine deteriorates retention as well. Introduced after training, both drugs deteriorate memory even in smaller doses - 2 and 0,25 mg/kg, respectively. On the background of the anticholinergic agents (especially in the higher doses), the learning and memory facilitating effects of caffeine are not manifested in any of the experimental setups (administration before and after train. The results obtained show that cholinergic mechanisms play an important role in the learning and memory facilitating effect of caffeine. A necessary condition for the manifestation of this effect is the optimum functional level of these cholinergic mechanisms in the central nervous system.
| 13,607
|
Phenothiazine-induced alterations of immune response in experimental tick-borne encephalitis: morphological model analysis of events.
|
The depressive effect of trifluoperazine (TFP), a phenothiazine derivative, on the morphology of the development of immune response (IR) (humoral and cell-mediated component) was studied in mice given tick-borne encephalitis (TBE) virus, sheep red blood cells (SRBC) or the BCG vaccine. This effect was manifested by a decrease in the mitotic activity of lymphocytes and in the number of blastic transformations after antigenic stimulation. In virus-infected and TFP-given mice, lowered levels of specific virus neutralizing antibody (VNA), together with a pronounced reduction of the inflammatory response in the brain were found. No signs of cytotoxicity following administration of the drug were observed. The mechanism of the immunodepressive action of TFP are discussed.
| 13,643
|
Effect of methylated PGE2 analogs given orally on pancreatic response to secretin in man.
|
The effect of two methylated PGE2 analogs given orally on the pancreatic response to intravenous secretin has been studied in 8 healthy subjects. The secretion of bicarbonate was not changed by these PGE2 analogs. The secretion of enzymes during infusion of PGE2 analogs was significantly greater than in the control.
| 13,652
|
Physiologic effects of normal-or low-oxygen-affinity red cells in hypoxic baboons.
|
Baboons were bled one-third their red cell mass and were given homologous transfusions of red blood cells to restore the red cell volume. One group of baboons received red blood cells with a normal 2,3-diphosphoglycerate 2,3-DPG) level and normal affinity for oxygen, and in this group the 2,3-DPG level after transfusion was normal. The other group received red blood cells with a 160% of normal 2,3-DPG level and decreased affinity for oxygen, and in this group the 2,3-DPG level after transfusion was 125% of normal. In both groups of baboons, the inspired oxygen concentration was lowered and arterial PO2 tension was maintained at 55-60 mmHg for 2 h after transfusion. During the hypoxic state, systemic oxygen extraction was similar in the two groups, whereas oxygen saturation was lower in the high 2,3-DPG group than in the control animals. Cardiac output was significantly reduced 30 min after the arterial PO2 was restored to normal. These data indicate that red blood cells with decreased affinity for oxygen maintained satisfactory oxygen delivery to tissue during hypoxia.
| 13,664
|
The effect of adrenergic receptor blocking agents on arrhythmia caused by trauma.
|
Experiments on animals have shown that blunt trauma to the anterior chest wall causes arrhythmia and conduction disturbances. In most cases nodal rhythm and ST segment elevation were observed. Microscopic examination disclosed myocardial damage in the vicinity of the atrioventricular node. Administration of alpha or beta adrenergic receptor blocking agents immediately before trauma failed to prevent arrhythmia and conduction disturbances, on the contrary, they became even more pronounced.
| 13,678
|
Control of breathing using an extracorporeal membrane lung.
|
Various amounts of carbon dioxide were removed through an extracorporeal membrane lung in spontaneously breathing lambs. The decrease in alveolar ventilation was proportional to the fraction of total carbon dioxide removed by the membrane lung. When extracorporeal CO2 removal approximated CO2 production (VCO2), alveolar ventilation almost ceased. Pulmonary ventilation can be controlled by extracorporeal carbon dioxide removal.
| 13,683
|
[Endocrine effects of neuroleptics].
|
The neuroleptic drugs used in anesthetics belong to the group of phenothiazines or butyrophenones. The endocrine response to their intravenous administration is still ill-known and usually only concerns the association of anesthetics and neuroleptics. However, as far as the catecholamines are concerned, it is known that neuroleptic drugs do not prevent either their secretion nor their liberation but, depending on their dosage, they block the dopaminergic receptors and the alpha-receptors and induce disturbances in the metabolism of the mono-amines. The injection of neuroleptics associated with analgesics, raises the blood levels of catecholamines, does not induce a rise in ACTH and cortisol levels in the absence of stress, but does not totally prevent their rise in cases of aggression. As far as growth hormone is concerned, the effects are variable depending on the association studied. There is a rise with droperidol + pethidine or pentazocine, no change with chloroprotixene-dextromoramide. In both cases, the blood sugar rises. As far as STH, or growth hormone, free fatty acids and insulin are concerned, one may note a rise with associations containing droperidol even in the absence of any stress and stability with a mixture of chlorprotixene and dextromoramide. With none of these well known associations was there any variation either in levels of pituitary thyreo-stimulin, nor in thyroxine levels. Testosterone becomes reduced with the association of droperidol + analgesics but this effect does not seem to be specific to droperidol. These responses are frequently disturbed in case of additional stress.
| 13,691
|
Some aspects of the persistence and fate of acrolein herbicide in water.
|
Experimental data for the decay of acrolein approximated first order kinetics. The reaction continued to completion in local waters but in buffered solution (pH 5.1-8.6) an equilibrium was reached after reaction of about 92% of the acrolein. It is proposed that data presented on the effects of pH on decay of acrolein may be used as a conservative estimate of dissipation rates in water where non-target organisms are at risk. In flowing water in two channels the 8 to 10 fold discrepancy between observed and predicted rates of dissipation was attributed to major losses in volatilization and adsorption. A relatively non-volatile reaction product (which gave a positive reaction with dinitrophenylhydrazine) accumulated initially but dissipated rapidly, probably by microbiological processes, when acrolein concentrations fell below about 2 to 3 ppm.
| 13,740
|
Energetic aspects of anaerobic growth of Aerobacter aerogenes in complex medium.
|
Molar growth yields for anaerobic growth of Aerobacter aerogenes in complex medium were much higher than for growth in minimal medium. In batch cultures the molar growth yield for glucose varied from 44 to 50 and YATP from 17.1 to 18.8. For glucose-limited chemostat cultures a value of 17.5 g/mole was found for Y max ATP and a value of 2.3 mmoles ATP/g dry weight h for the maintenance coeficient. Growth-dependent pH changes were used to control the addition of fresh medium, containing excess of glucose to a continuous culture. The specific growth rate and the population density were dependent on the pH difference between the inflowing medium and the culture. At a mu value of 1.44 h-1 the molar growth yield for glucose was about 70 and Y ATP about 28.5. An equation is presented, which gives the relation between theoretical and experimental Y max ATP values.
| 13,757
|
Ammonium uptake and metabolism by mitrogen fixing bacteria. II. Klebsiella pneumoniae.
|
The primary steps of N2, ammonia and nitrate metabolism in Klebsiella pneumoniae grown in a continuous culture are regulated by the kind and supply of the nitrogenous compound. Cultures growing on N2 as the only nitrogen source have high activities of nitrogenase, unadenylated glutamine synthetase and glutamate synthase and low levels of glutamate dehydrogenase. If small amounts of ammonium salts are added continuously, initially only part of it is absorbed by the organisms. After 2-3 h complete absorption of ammonia against an ammonium gradient coinciding with an increased growth rate of the bacteria is observed. The change in the extracellular ammonium level is paralleled by the intracellular glutamine concentration which in turn regulates the glutamine synthesis and an induction of glutamate dehydrogenase synthesis. Upon deadenylation these events are reversed.--Addition of dinitrophenol causes transient leakage of intracellular ammonium into the medium.
| 13,759
|
Monoamine metabolism in human brain.
|
Norepinephrine (NE), dopamine (DA), tyrosine hydroxylase (TH), catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) levels were measured in human brain tissue obtained at autopsy from a series of 39 patients dying of various medical and accidental causes. The nine following brain areas were studied: globus pallidus, thalamus, hypothalamus, hippocampus, substantia nigra, floor of the fourth ventricle, orbital cortex, caudate nucleus, and mammillary bodies. Enzyme activity correlated positively with age in all brain areas for MAO (with both benzylamine and tryptamine substrates) but no consistent pattern of correlation was found for COMT and TH. Mean MAO activity was significantly higher in women than men. There is increased brain MAO activity during late childhood and adolescence. These data are consistent with previous evidence suggesting that age and sex are important determinants of amine metabolism in the human central nervous system.
| 13,761
|
Validation of a simple radiochemical assay measuring hydrolysis of choline-labelled microsomal phosphatidylcholine by phospholipase C. pH-dependence.
|
Selective hydrolysis of phosphatidylcholine species, which are selectively radioactively labelled in vivo, does not appear to interfere with a radiochemical assay for hydrolysis of microsomal phosphatidylcholine by C-type phospholipases from Bacillus cereus or Clostridium perfringens. Both phospholipases substantially hydrolysed phosphatidylcholine over the pH range 4.0-10.0.
| 13,785
|
Purification and properties of debranching enzyme from dogfish muscle.
|
Glycogen debranching enzyme (4-alpha-glucanotransferase amylo-1,6-glucosidase, EC 2.4.1.25 + 3.2.1.33) was purified 140-fold from dogfish muscle in a rapid, high-yield procedure that takes advantage of a strong binding of the enzyme to glycogen, and its quantitative adsorption to concanavalin A-Sepharose only when the polysaccharide is present. The final product was hrophoresis in the presence and absence of dodecyl sulfate. A molecular weight of 162,000 +/- 5000 was determined by sedimentation equilibrium analysis in good agreement with the value of 160,000 estimated by gel electrophoresis, but a low-sedimentation constant of 6.5 S suggests that the enzyme is asymmetric. The molecule appears to be made up of a single polypeptide chain with no evidence for multiple repeating sequences: it could not be dissociated into smaller fragments by dodecyl sulfate even after complete carboxymethylation; tryptic cleavage of the native protein yielded only two fragments of molecular weight 20,000 and 140,000 without loss of enzymatic activity. The amino acid composition of the enzyme is reported; no covalently bound phosphate or carbohydrate could be detected. All 32 sulfhydryl groups present were titrated with 5,5'-dithiobis(2-nitrobenzoic acid) under denaturing conditions; eight reacted readily in the native enzyme without loss of catalytic activity, while substitution of eight additional ones lowered the activity by 50%. Inactivation was greatly reduced by glycogen; the polysaccharide also influenced markedly the electrophoretic behavior of the enzyme and large filamentous aggregates were formed when solutions of both were mixed. Purified debranching enzyme releases 3 mumol of glucose min-1 mg-1 at 19 degrees C, pH 6.0, from a glycogen limit dextrin and one-tenth this amount when the native polysaccharide is used as substrate; glycogen is quantitatively degraded in the presence of phosphorylase. None of the usual sugar phosphates or nucleotide effectors of glycolysis affected enzymatic activity. No phosphorylation by either dogfish or rabbit skeletal muscle protein kinase or phosphorylase kinase could be demonstrated, nor any direct interaction with phosphorylase as measured by SH-group reactivity, enzymatic activity, or rate of phosphorylase b to a conversion. Purification of the 160,000 molecular weight M-line protein of skeletal muscle resulted in the quantitative removal of debranching enzyme, indicating that the two proteins are different.
| 13,809
|
Cation transport in cytochrome oxidase reconstituted vesicles.
|
Cation translocation across the membrane of cytochrome oxidase reconstituted vesicles may be followed with a simple spectrophotometric method. Cytochrome oxidase reconstituted vesicles, supplemented with ascorbate and cytochrome c. induce large spectral changes of the positive dye safranine, reversed by uncouplers and inhibitors of respiration. The dye is probably accumulated in the inner space of the vesicles, where it reaches high concentrations and aggregates. The spectral shifts and the absorbance changes, due to aggregation, are proportional to the amount of the dye taken up and depend on the respiratory control. In the presence of potassium, valinomycin causes an inhibition, whereas nigericin stimulates the dye uptake. The data are discussed in terms of electrical potential dependent fluxes.
| 13,827
|
Bis-(4-methylumbelliferyl) phosphate as a substrate for the surface membrane-associated phosphodiesterase activity of pig platelets.
|
It was found that the newly-available compound, bis-(4-methylumbelliferyl) phosphate, could be used as a substrate for the pig platelet surface membrane-associated phosphodiesterase activity, usually assayed with bis-(p-nitrophenyl) phosphate. This enzyme activity is distinct from the phosphodiesterase activity towards 5'-dTMP-P-nitrophenyl ester, which is probably associated with intracellular membrane structures in platelets. Consequently, the use of the 4-methylumbelliferyl derivative as substrate for the phosphodiesterase activity provides a sensitive, fluorimetric assay for this marker enzyme of the platelet surface membrane.
| 13,836
|
A specific polyadenylase from Escherichia coli K12.
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A polyadenylase, degrading specifically poly(A) sequences was isolated from Escherichia coli K12. The enzyme was purified about 850 times to practically electrophoretic homogeneity. It was free of poly(A) polymerase activity, as well as of the well known E. coli RNAases I and II. It is stimulated by bivalent cations like Mg2+ and Mn2+ and splits poly(A) to 3'-AMP and therefore it can be considered as an exonuclease. The enzyme does not degrade any other ribohomopolymer or RNA.
| 13,837
|
Purification and properties of aldehyde dehydrogenase from Proteus vulgaris.
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NADP-linked aldehyde dehydrogenase (aldehyde : NADP+ oxidoreductase, EC 1.2.1.4) was purified from Proteus vulgaris to the stage of homogeneity as judged by ultracentrifugation and polyacrylamide gel electrophoresis. The molecular weight of the purified enzyme was estimated to be 130000 by gel filtration. The enzyme which was crystallized from ammonium sulfate solution, lost its activity. The enzyme did not require coenzyme A, and the reaction was completely dependent on ammonium ions which could be partially replaced by Rb+ or K+. The optimum pH was about 9. Broad substrate specificity was observed and Km values for propionaldehyde, acetaldehyde and isovaleraldehyde were 1.7 - 10(-5), 4 - 10(-5) and 3 - 10(-5) M, respectively. The physiological role of the enzyme in living cells is obscure, but might account for another degradative pathway of L-leucine in P. vulgaris differing from the established pathway.
| 13,839
|
Purification and properties of one component of acid phosphatase produced by Aspergillus niger.
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One component, the i form, of acid phosphatase (orthophosphoric-monoester phosphohydrolase (acid optimum), EC 3.1.3.2) produced by Aspergillus niger was purified from the mycelial extract. The purified enzyme was homogenous on Sephadex G-200 gel filtration, disc electrophoresis and heat inactivation. The purified enzyme was studied and the following results were obtained: 1. The enzyme catalyzed the hydrolysis of a wide variety of phosphomonoesters, but not that of bis(p-nitrophenyl)phosphate, adenosine 3',5'-cyclic monophosphate, fructose 1,6-diphosphate, adenosine 5'-diphosphate or adenosine 5'-triphosphate. 2. Fluoride, orthophosphate, arsenate, borate, molybdate and (+)-tartrate acted as inhibitors. This enzyme was inactivated by N-bromosuccinimide and 2-hydroxy-5-nitrobenzyl bromide, and was not affected by p-chloromercuribenzoate, N-acetylimidazole, p-diazobenzenesulfonic acid and tetranitromethane. From these results, tryptophan was estimated to play an important role in the enzyme activity. 3. The apparent molecular weight was 310000 by Sephadex G-200 gel filtration. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate suggested that the molecular weight of the subunit was approximately 89000. 4. The purified enzyme contained 29% carbohydrate consisting of glucosamine, mannose and galactose. The amino acid composition of this enzyme was not specific compared with other known acid phosphatases.
| 13,843
|
The transsulfuration pathway in Tetrahymena pyriformis.
|
Four enzymes necessary for the metabolism of methionine by the trans-sulfuration pathway, methionine adenosyltransferase (EC 2.5.1.6), adenosylhomocysteinase (EC 3.3.1.1), cystathionine beta-synthase (EC 4.2.1.22) and cystathionine gamma-lyase (EC 4.4.1.1) were identified in Tetrahymean pyriformis. The ability of these cells to transfer 35S from E135S]methionine to form [35S] cysteine was also observed and taken as direct evidence for the functional existence of this pathway in Tetrahymena. An intermediate in the pathway and an active methyl donor, S-adenosylmethionine, was qualitatively identified in Tetrahymena and its concentration was found to be greater in late stationary phase cells than in early stationary phase cells.
| 13,863
|
Inactivation of mitochondrial 2-oxoglutarate dehydrogenase complex as a result of phospholipid degradation induced by freeze-thawing.
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The inactivation of 2-oxoglutarate dehydrogenase complex by freeze-thawing was examined along with alterations of membrane phospholipids, in order to elucidate the mechanism of freezing injury in mitochondria. The dehydrogenase complex activity in slowly frozen and thawed mitochondria decreased to 70% as compared to intact mitochondria and further decreased during incubation. This inactivation during incubation was temperature dependent, i.e., at temperatures up to 25 degrees C there was a slight decrease, while at higher temperatures there was a marked decrease in the dehydrogenase complex activity. Simultaneously, there was a significant accumulation of free fatty acids, generated from mitochondrial phospholipids, which inhibited 2-oxoglutarate dehydrogenase and subsequently enzyme complex activity. Oxoglutarate dehydrogenase activity in mitochondria was markedly inhibited by exogenous phospholipase A, and this inhibition was partially prevented with bovine serum albumin. Furthermore, when intrinsic phospholipase A was either inhibited or stimulated, there was a respective decrease or increase in the enzyme complex inactivation. The activity of the purified enzyme complex decreased slightly after slow freezing, but remained constant even when incubated at temperatures up to 32 degrees C. However, the activity of this enzyme complex was markedly reduced when incubated either in the presence of venom phospholipase A or with exogenous fatty acid. The relationship between inactivation of the 2-oxoglutarate dehydrogenase complex, phospholipase A activation and production of free fatty acids in frozen and thawed mitochondria is discussed.
| 13,867
|
The molecular dynamics of hyaluronates in solution.
|
The dynamic properties of hyaluronate solutions are discussed with relevance to some problems in sensory physiology (mechanoelectrical transduction), renal physiology, interstitial fluid regulation, and especially to the causes of open-angle glaucoma. With respect to the last problem: as recent biochemical evidence indicates that the hyaloid membrane does not exist, it now seems worthwhile to consider the increase in intraocular pressure present in the eye with glaucoma to be due--at least in the open-angle case--to a change in the specific gravity and hydrophilic nature of the hyaluronic acid in the vitreous body in particular, as well as in the trabecular meshwork. Densimetric experimental evidence indicates that the hyaluronate system could, indeed, produce the pressure changes seen in glaucoma, if intraocular pH changed but slightly. A hypothesis concerning the effect of acetazol amide on intraocular pressure is also presented.
| 13,876
|
[Effect of hypoxia on the concentration of nicotinamide coenzymes in the tissues of newborn rats].
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The content of nicotinamide coenzymes (NAD, NAD-H, NADP, NADP-H) was studied in the brain, heart and liver tissue of the newborn rats kept in hypoxic gaseous medium with a 4% oxygen content for 2 1/2 hours. There was a marked reduction of NAD content, an accumulation of NAD-H and a more than two-fold fall of the NAD/NAD-H ratio particularly marked in the brain and heart. A reduction of the NADP-H values chiefly in the liver and of the general pool of NAD-phosphates in the tissues of the newborn rats under study occurred under the same conditions. The data obtained led to the conclusion that oxygen deficiency had a significant influence on the concentration and the ratio of the nicotinamide coenzymes in the tissues of newborn rats, that in its turn led to the changes in the level and the direction of the redox processes under the conditions of hypoxia.
| 13,878
|
Influence of oxygen and carbon dioxide on the plasma-erythrocyte pH relationship in normal human whole blood.
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The influence of oxygenation level (oxyhaemoglobin saturation 0 or 100%) on the relationship between plasma pH and erythrocyte pH was studied, in vitro, in normal human blood submitted to changes in carbon dioxide tension. Firstly, the pH of both true and separated erythrolysates were compared: for the former, tonometry was carried out on whole blood, before red cells lysis; for the latter, equilibration was performed on erythrolysate, pH values appeared different: at PCO2 congruent to 21 and 38 Torr, separated erythrolysate was more alkaline than true one, and at PCO2 congruent to 0 it was more acid. Therefore, to estimate pHe-pHi relationship, pHi was evaluated on true erythrolysate. When haemoglobin passed from the reduced to the completely oxygenated state, a significant decrease of both pHe and pHi was observed for a given PCO2 (respectively about 0.05 and 0.08 pH unit), and of pHi for a given pHe (about 0.04 pH unit). In either extra or intraerythrocyte fluid, the oxygen-linked pH difference was negatively correlated to PCO2.
| 13,893
|
The normal occurrence of octopamine in the central nervous system of the rat.
|
An enzymatic assay for octopamine capable of detecting 50 pg of amine was developed and used to study the distribution of octopamine in regions of the rat central nervous system. The presence of octopamine in the rat pineal organ was confirmed by mass spectrometry; Administration of a monoamine oxidase inhibitor and of tyramine led to increases in CNS octopamine levels while the administration of reserpine intraperitoneally or 6-hydroxydopamine intraventricularly led to decreases in octopamine levels. The results suggest that in the mammalian CNS octopamine is present in neural structures where it may be involved in synaptic function.
| 13,909
|
Ganglioside GM2 N-acetyl-beta-D-galactosaminidase and asialo GM2 (GA2) N-acetyl-beta-D-galactosaminidase; studies in human skin fibroblasts.
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Ganglioside GM2 and its asialo-derivative, GA2 were radiolabeled in their N-acetyl-D-galactosaminyl moieties by oxidation with galactose oxidase and reduction with tritiated sodium borohydride. Specific activities of 6 X 10(4) dpm/nmol (GM2) and 1.8 X 10(6) dpm/nmol (GA2) were achieved. About 98% of the label was in N-acetyl-D-galactosamine. Using these substrates, an assay was developed for GM2-N-acetyl-beta-D-galactosaminidase (E.C.3.2.1.30) and GA2-N-acetyl-beta-D-galactosaminidase (E.C.3.2.1.30) activities in human cultured skin fibroblasts. The products of the GM2 cleaving reaction were identified as N-acetylgalactosamine and ganglioside GM3. Both GM2 and GA2 cleaving activities were stimulated about 5-fold by purified sodium taurocholate, and this stimulation was inhibited by neutral detergents, lipids and albumin at low concentrations. Addition of various salts, reducing agents and a protein activator factor from human liver of Li et al. (1973) did not stimulate GM2-N-acetyl-beta-D-galactosaminidase activity beyond that found with sodium taurocholate. Under optimal conditions, control fibroblast supernates cleaved ganglioside GM2 at a rate of 3.7 nmol/mg protein/h compared to 1100 for GA2-N-acetyl-beta-D-galactosaminidase and 4700 for 4-methylumbelliferyl-N-acetyl-beta-D-glucosaminidase. Supernates from two patients with Tay-Sachs disease had markedly reduced activity levels for GM2-N-acetyl-beta-D-galactosaminidase but not for the other two substrates. Supernates from two patients with Sandhoff's disease had reduced activities for all three substrates. A supernate from one patient with juvenile GM2 gangliosidosis cleaved GM2 at a somewhat faster rate than those from Tay-Sachs or Sandhoff's patients. Two healthy adult women with markedly reduced hexosaminidase A activities using 4MU-N-acetyl-beta-D-glucosaminide as substrate had approximately half-normal activities using GM2 as substrate. A patient with the Tay-Sachs phenotype but with a partial deficiency of hexosaminidase A using the 4-MU substrate had a profound deficiency using GM2 as substrate. In such unusual hexosaminidase mutants, assays using GM2 as substrate are better indicators of phenotype than those using synthetic substrates.
| 13,950
|
Altered hepatic blood flow and drug disposition.
|
For some drugs, delivery to the liver by the hepatic circulation is an important determinant of removal by this organ. Classical pharmacokinetic analyses cannot predict the changes produced by altering any of the biological determinants of drug elimination by the liver; hepatic blood flow, metabolic enzyme activity, drug binding and route of administration. However, with the use of a physiological model of hepatic drug elimination, such predictions can be made. This model has been tested experimentally and appears to be valid. Hepatic blood flow can vary over about a 4-fold range from half normal flow to twice logical changes affecting the circulation. For drug clearance to be affected significantly by these changes in flow, the drug must be avidly removed by the liver as reflected in a high hepatic extraction ratio and intrinsic hepatic clearance. This latter term is a useful way to characterise the ability of the liver to irreversibly remove drug from the circulation in the absence of any flow limitation. The clearance of drugs with low intrinsic clearance will not be affected significantly by changes in liver blood flow.
| 13,954
|
Monoamine metabolites in cerebrospinal fluid and serotonin uptake inhibition during treatment with chlorimipramine.
|
The effects of chlorimipramine on the concentrations of the main metabolites of serotonin (5-HT) norepinephrine (NE), and dopamine, i.e. 5-hydroxyindoleacetic acid (5-HIAA), 4-hydroxy-3-methoxyphenyl glycol (HMPG) and homovanillic acid (HVA), respectively, were studied in cerebrospinal fluid from 14 depressed patients, and related to the serotonin- and NE uptake inhibiting activity in vitro of plasma drawn from the patients. Chlorimipramine inhibited the uptake of both transmitter amines in all patients. During treatment, the levels of 5-HIAA and HMPG in cerebrospinal fluid (CSF) were significantly reduced. HVA levels were reduced in 6 patients and increased in 8 patients; there was no mean change. The decrease in 5-HIAA level in CSF was correlated to the uptake inhibition of 5-HT but there was no corresponding relationship between NE uptake and HMPG levels. The changes in HVA levels were also correlated to the uptake of 5-HT despite the absence of a unidirectional change of this metabolite.
| 13,959
|
Effect of ultrasonic nebulization on arterial oxygen saturation in chronic obstructive pulmonary disease.
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Twenty patients with mild to severe chronic obstructive pulmonary disease received ultrasonic nebulization to assess the danger of short-term changes in blood gas levels during this therapy. The status of arterial oxygenation was monitored during 20 minutes of therapy and for 20 minutes following therapy. In nine patients with periodic studies of arterial blood, the mean change in arterial oxygen pressure from base line was a decrease of 0.8 mm Hg at ten minutes into therapy, 2.8 mm Hg at the conclusion of therapy, and 2.9 mm Hg 20 minutes after therapy. In all 20 patients, ear oximetric studies showed only a small mean change at ten minutes into therapy, at the end of therapy, and at 20 minutes after therapy. Changes in the status of arterial oxygenation during and after therapy with ultrasonic nebulization in a group of patients with chronic obstructive pulmonary disease are generally small and of no statistical and limited clinical significance; however, alarming falls in arterial oxygenation can occur and cannot be predicted by base-line testing of pulmonary function or studies of arterial blood. It would be prudent to monitor patients with chronic obstructive pulmonary disease during therapy with ultrasonic nebulization or to withhold therapy altogether.
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Controlled comparison of bromazepam, amitriptyline, and placebo in anxiety-depressive neurosis.
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Seventy-two private practice patients with moderate or severe anxiety-depressive neurosis received mean daily oral doses of 23.8 mg bromazepam, 94 mg amitriptyline, or 4.6 capsules of placebo in a double-blind four-week study. The patient's condition was assessed initially and at weekly intervals by using the Brief Psychiatric Rating Scale and the Hamilton Psychiatric Rating Scale for Depression. From the first through the fourth week evaluations, a larger proportion of patients improved on bromazepam than on amitriptyline. Bromazepam was also superior to amitriptyline and placebo in the degree of improvement made Statistical significance (p less than 0.05) of the changes noted after one week was even greater after four weeks, particularly in BPRS items of somatic concern, depressive mood, anxiety and tension and in nearly all representative psychic and somatic symptoms on the depression scale, confirmed by global evaluation. Compared to bromazepam patients, amitriptyline patients had significantly severer adverse reactions which were the major cause of the group's higher dropout rate (66% vs 33%). The prompt clinical response to bromazepam contributed to its superior safety and patient progress in that it was possible to carefully titrate dosage and thus help to control adverse reactions and allow patients to maintain alertness and productivity under therapy.
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