Effects of amino acids and derivatives of cyclic adenosine 3', 5'-monophosphate on the production of three exoenzymes by Staphylococcus simulans biovar staphylolyticus.
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Amino Acids↗
Biomedical subjects
J M Robinson
Publications and source records attributed to J M Robinson.
Effects of urea treatment on the divalent cation-independent cell aggregation of 3T3MIT fibroblasts.
Growth of nontransformed 3T3MIT fibroblasts in media containing 200 mM urea leads to the rapid acquisition of the transformed adhesive phenotype as evidenced by an increased rate of divalent cation-independent cell aggregation. The increased rate of divalent cation-independent cell aggregation of urea treated 3T3MIT cells shares many properties with the high rate of aggregation of transformed cells including a sensitivity to treatment with trypsin or hyaluronidase and a reduction in the presence of exogenously added hyaluronic acid. Reversal of the urea-induced increase in aggregation occurs within 24 hours in the absence of urea and can be blocked by 0.2 micrograms/ml cycloheximide. In the presence of cycloheximide, low rates of aggregation can be restored by the addition of urea-conditioned supernatents. The results of these experiments suggest that the loss of an aggregation-inhibitory activity during growth in media containing 200 mM urea is responsible for the increased rate of divalent cation-independent cell aggregation. After removal of this aggregation-inhibitory activity, the normally lowly adhesive 3T3MIT cells become phenotypically transformed with regards to the rate of divalent cation-independent cell aggregation.
Animals↗
Glycogen accumulation in polymorphonuclear leukocytes, and other intracellular alterations that occur during inflammation.
Neutrophils isolated from the blood were compared to those from inflammatory exudates in the peritoneal cavity of guinea pigs. Inflammatory neutrophils were shown to have 10-fold more glycogen than blood neutrophils. This was also reflected in the morphology of these cells. The large accumulations of glycogen in inflammatory neutrophils exists in ordered arrays of beta-granules. Other morphological changes including accumulations of lipid droplets and a decrease in the number of lysosomal granules also accompany the change from blood neutrophils to inflammatory neutrophils. These results show that there are major metabolic differences in the two types of neutrophils.
Animals↗
Coordinate production of three exoenzymes of Staphylococcus staphylolyticus.
Staphylococcus staphylolyticus produced three exoenzymes (a staphylolytic endopeptidase, a hexosaminidase and a protease) coordinately under a range of conditions of induction and repression by various peptides and carbohydrates. Mutants of S. staphylolyticus were isolated and shown to have pleiotropic variations in the production of the three enzymes. Hypo- or hyperproducing mutants of one enzyme were invariably hypo- or hyperproducers for the other two enzymes. Mutants that had lost the ability to produce one of the exoenzymes invariably failed to produce the other two enzymes. Revertants isolated from non-producers that regained the ability to produce one of the exoenzymes always regained the ability to produce the other two as well. These results suggest that the three exoenzymes share a common regulatory or processing mechanism.
Endopeptidases↗
Hydrogen peroxide synthesis in isolated spinach chloroplast lamellae : an analysis of the mehler reaction in the presence of NADP reduction and ATP formation.
Light-dependent O(2) reduction concomitant with O(2) evolution, ATP formation, and NADP reduction were determined in isolated spinach (Spinacia oleracea L. var. America) chloroplast lamellae fortified with NADP and ferredoxin. These reactions were investigated in the presence or absence of catalase, providing a tool to estimate the reduction of O(2) to H(2)O(2) (Mehler reaction) concomitant with NADP reduction. In the presence of 250 micromolar O(2), O(2) photoreduction, simultaneous with NADP photoreduction, was dependent upon light intensity, ferredoxin, Mn(2+), NADP, and the extent of coupling of phosphorylation to electron flow.In the presence of an uncoupling concentration of NH(4) (+), saturating light intensity (>500 watts/square meter), saturating ferredoxin (10 micromolarity) rate-limiting to saturating NADP (0.2-0.9 millimolarity), and Mn(2+) (50-1000 micromolarity), the maxium rates of O(2) reduction were 13-25 micromoles/milligram chlorophyll per hour, while concomitant rates of O(2) evolution and NADP reduction were 69 to 96 and 134 to 192 micromoles/milligram chlorophyll per hour, respectively. Catalase did not affect the rate of NADPH or ATP formation but decreased the NADPH:O(2) ratios from 2.3-2.8 to 1.9-2.1 in the presence of rate-limiting as well as saturating concentrations of NADP.Photosynthetic electron flow at a rate of 31 micromoles O(2) evolved/milligram chlorophyll per hour was coupled to the synthesis of 91 micromoles ATP/milligram chlorophyll per hour, while the concomitant rate of O(2) reduction was 0.6 micromoles/milligram chlorophyll per hour and was calculated to be associated with an apparent ATP formation of only 2 micromoles/milligram chlorophyll per hour. Thus, electron flow from H(2)O to O(2) did not result in ATP formation significantly above that produced during NADP reduction.
Journal Article↗
Hypotensive anaesthesia for microsurgery of the middle ear. A comparison between enflurane and halothane.
One hundred patients undergoing microsurgery of the ear were anaesthetised using thiopentone, nitrous oxide, oxygen and either halothane or enflurane with spontaneous respiration. Blood pressure was reduced to approximately 70 mmHg by the use of hypotensive agents. The efficacy of halothane and enflurane in producing good operating conditions was compared during this technique. Haemostasis was assessed by the surgeon who was unaware which volatile agent was being used. Both agents were found to be satisfactory and enflurane was shown to be a safe and reliable agent with this technique should an alternative to halothane be required. No impairment of renal function was seen with either agent in combination with hypotension.
Adolescent↗
Removal of Sulfur Compounds from Coal by the Thermophilic Organism Sulfolobus acidocaldarius.
The thermophilic, reduced-sulfur, iron-oxidizing bacterium Sulfolobus acidocaldarius was used for the removal of sulfur compounds from coal. The inclusion of complex nutrients such as yeast extract and peptone, and chemical oxidizing agents, 0.01 M FeCl(3) into leaching medium, reduced the rate and the extent of sulfur removal from coal. The rate of sulfur removal by S. acidocaldarius was strongly dependent on the sulfur content of the coal and on the total external surface area of coal particles. Approximately 96% of inorganic sulfur was removed from a 5% slurry of coal which had an initial total sulfur content of 4% and an inorganic (pyritic S and sulfate) sulfur content of 2.1%. This resulted in removal of 50% of initial total sulfur present in coal.
Journal Article↗
A controlled comparison of relaxation and diazepam in panic disorder.
Subjects with panic disorder (N = 23) were randomized into a crossover design involving diazepam, placebo, relaxation therapy, or control. Anxiety was measured by a 3-day hourly diary, psychological tests, and assessment of heart rate and skin conductance level during baseline, stress test, and interview. The greatest and only significant physiologic changes occurred with diazepam. The largest pre/posttreatment changes on the psychological tests and self-reported anxiety and depression occurred with relaxation, although the differences were not statistically significant. Relaxation therapy may be useful for treating the general anxiety associated with panic disorder.
Adolescent↗
Bacteriuria and survival in old age.
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Adolescent↗
Superoxide production by an unusual aldehyde oxidase in guinea pig granulocytes. Characterization and cytochemical localization.
An aldehyde oxidase extracted from guinea pig granulocytes with isotonic KCl catalyzes the oxidation of a variety of aliphatic aldehydes and 2-OH-pyrimidine. The stoichiometry of the oxidation of 2-OH-pyrimidine is consistent with the reaction 2-OH-pyrimidine + OH- + O2 leads to uracil + H2O2. Between 75 and 90% of the peroxide produced results from dismutation of superoxide formed as an intermediate. The Km for 2-OH-pyrimidine is approximately 1.65 mM and the maximum velocity is 22.9 +/- 5.5 S.D. nmol of superoxide/min/10(7) cells. This same maximum velocity is observed for the substrates isobutyraldehyde, propionaldehyde, and acetaldehyde. Unlike other aldehyde oxidases, this enzyme is inactive with purines as substrates and is insensitive to antimycin A, menadione, and Triton X-100. The enzyme is inhibited by cyanide, methanol, and arsenite. The apparent molecular weight is approximately 340,000 +/- 25,000 and the pH optimum is in the range of 7.5 to 9.0. Electron cytochemistry reveals an association of this oxidase with the phagosome membrane. The potential significance of this oxidase is discussed in relation to microbicidal mechanisms.
Aldehyde Oxidase↗
Oxidative cytochemistry in phagocytosis: the interface between structure and function.
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Aldehyde Oxidoreductases↗
Comparative aspects of oxidative metabolism of neutrophils from human blood and guinea pig peritonea: magnitude of the respiratory burst, dependence upon stimulating agents, and localization of the oxidases.
We have compared the subcellular sites of H2O2 and presumably also superoxide-(O2-) production, and certain aspects of metabolic responses (O2 consumption, O2- production) of stimulated neutrophils from human blood and those elicited into guinea pig peritonea. Stimulation was accomplished with either opsonized zymosan or phorbol-12-myristate-13-acetate (PMA). Striking quantitative differences were observed between these cell types with regard to the increased respiration and O2- production observed during stimulation. These differences were most apparent when opsonized zymosan served as the stimulating agent. They were minimized when the soluble stimulating agent, PMA, was used. With either stimulus, the subcellular sites of H2O2 production were the same for both types of neutrophils, i.e., the plasmalemma and phagosomal membranes. No H2O2 production could be detected cytochemically in the absence of stimulation. Treatment of both unstimulated human blood and elicited guinea pig peritoneal neutrophils with the nonpenetrating, covalently linking reagent, p-diazobenzenesulfonic acid, failed to diminish O2- production upon subsequent stimulation, in contrast to a previous report. These data are discussed in terms of the possible cytological arrangements of the respiratory enzyme(s), and the different modes of stimulation of neutrophil metabolism by various agents. Ancillary data on elicited mouse peritoneal neutrophils are presented.
Animals↗
Configurational assignments to spirostan-3-ols by mass spectrometry.
A study of the degree of water elimination from ions derived from spirostan-3-ols by electron bombardment has shown that the loss is greatest from those ions produced by the 5 beta-spirostan-3 alpha-ols, less from the 5 beta-spirostan-3 beta-ols and the 5 alpha-spirostan-3 alpha-ols, which give losses of the same order of magnitude; and least from the 5 alpha-spirostan-3 beta-ols. The extent of water elimination can be used to help characterise spirostan-3-ols isolated from plant materials.
Chemical Phenomena↗
Specializations in filopodial membranes at points of attachment to the substrate.
A mouse cell line (LM), which grows predominantly as spindle-shaped cells with numerous filopodia, was employed in this study. These filopodial projections appear to be important as sites of attachment to the substratum in LM cells. Morphologically the filopodia are slender projections from the cell body which usually attach to the substrate at their distal ends (filopodial footpads). Freeze-fracture of monolayer cultures in situ preserves the spatial relationship of filopodial processes to that of the cell body. Examination of these freeze-fracture preparations reveals a striking difference in the density of intramembrane particles (IMP) in the filopodial-footpad plasmalemma compared with the plasmalemma of the cell body (number of IMP in footpad > cell body). Additionally, there is a marked difference in the number of filipin-sterol complexes on the cell body, compared with the filopodial footpad, implying a difference in the cholesterol content in these regions (filipin-sterol complexes in footpad < cell body). These data suggest a structural and functional specialization of the filopodial-footpad plasma membrane which may be related to cell adhesion.
Animals↗
The characteristics of extracellular protein secretion by Staphylococcus staphylolyticus.
The differential rate of extracellular protein formation by Staphylococcus staphylolyticus, the lysostaphin-producing organism, was biphasic with a low rate of exoprotein secretion during exponential growth and an increased rate during the post-exponential phase of growth. After 20 h, when no further exoprotein was secreted, exoprotein accounted for 5% of the total protein in the culture. The secretion of three extracellular enzymes was monitored and found to represent a constant proportion of total exoprotein at exoprotein concentrations greater than 0.1 mg ml-1.
Bacterial Proteins↗
Influence of Hydrogen Peroxide upon Carbon Dioxide Photoassimilation in the Spinach Chloroplast: I. HYDROGEN PEROXIDE GENERATED BY BROKEN CHLOROPLASTS IN AN "INTACT" CHLOROPLAST PREPARATION IS A CAUSAL AGENT OF THE WARBURG EFFECT.
Photosynthesis and the Warburg effect (O(2) inhibition of photosynthesis) were evaluated in preparations of intact spinach chloroplasts enriched with varying amounts of lysed chloroplasts. Increasing the ratio of broken to intact plastids resulted in decreased rates of CO(2) assimilation.Hydrogen peroxide when added at 10 or more micromolar also inhibited photosynthesis in these preparations. Inhibition of the photosynthetic rate by both factors was eliminated by addition of catalase. These findings indicate that H(2)O(2) presumably generated by the broken chloroplasts was the causal agent of this inhibition.The Warburg effect also became more pronounced by increasing the level of broken to intact chloroplasts. This effect was examined as a function of added catalase, pH, and O(2) concentration. At 21% O(2) and 0.44 to 0.68 millimolar CO(2), catalase relieved the effect almost completely at pH 7.5, but at pH 8.3, the rate was restored only to about half or less of the control. At pH 7.6, 0.44 millimolar CO(2), and 100% O(2), the effect was only slightly overcome by catalase.A rise in glycolate synthesis by the isolated spinach chloroplast has been shown previously to be coupled to an increase in pH and O(2) (Kow, Robinson, Gibbs 1977 Plant Physiol 60: 492-495; Robinson, Gibbs, Cotler 1977 Plant Physiol 59: 530-534). At 21% O(2), glycolate synthesis was not affected by the addition of catalase at pH 7.5 or 8.3. It is proposed that at 21% O(2) and without some means of removing H(2)O(2), that portion of the Warburg effect attributed to glycolate synthesis has been overestimated at pH values in the order of 7.5. In contrast, that portion of the Warburg effect which was, at alkaline pH, insensitive to catalase represented the stress placed upon the photosynthetic carbon reduction cycle which resulted from an enhanced synthesis of glycolate. At 100% O(2) aeration and pH 7.5 to 8.5, the Warburg effect may also represent O(2)-mediated inhibition of a Calvin cycle enzyme within the intact plastid.
Journal Article↗
Evaluation of the polyene antibiotic filipin as a cytochemical probe for membrane cholesterol.
Distribution of the filipin-cholesterol complexes has been studied by freeze-fractures techniques. While filipin-cholesterol complexes are formed in fixed as well as unfixed cells, the distribution of the complexes varies with fixation. Furthermore, filipin induces dramatic rearrangement of intramembrane particles in unfixed, but not in fixed, cells. Examination of thin sections of filipin-treated cells shows that filipin alone induces substantial cellular damage, while filipin treatment simultaneous to fixation or following fixation does not cause noticeable damage. For filipin to be an effective cytochemical probe of membrane structure, cellular damage must be minimized; this is best achieved by treating cells with filipin following glutaraldehyde fixation.
Animals↗