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PubMedDate not supplied

A rapid Candida albicans hyphal-form growth inhibition assay: determination of myelomonocytic-mediated antifungal activity.

An in vitro microassay for the measurement of Candida albicans hyphal-form growth inhibition by myelomonocytic cells is described. The assay is rapid, easy-to-perform and objective. A Candida strain capable of in vitro dimorphic transition from yeast to hyphal form has been employed. The assay is based on the incorporation of 3H-glucose by the fungus, the effect being dependent upon the time of pulse, size of the inoculum and concentration of radiolabelled metabolite. In particular, C. albicans hyphal form, obtained by a 3 h incubation in vitro in the presence of 10% fetal calf serum, is co-incubated with the effector cells. A pulse with 3H-glucose in water is then performed and the radioactivity incorporated by the residual Candida is taken as an indication of hyphal growth. We found that polymorphonuclear cells, peritoneal macrophages and the cloned GG2EE macrophage cell line significantly inhibited hyphal growth, the effects being time and effector-to-target cell ratio dependent.

Animals↗
PubMed2004

Applications of positron emission tomography (PET) in neurology.

Positron emission tomography (PET) is a powerful imaging technique which enables in vivo examination of brain functions. It allows non-invasive quantification of cerebral blood flow, metabolism, and receptor binding. In the past PET has been employed mainly in the research setting due to the relatively high costs and complexity of the support infrastructure, such as cyclotrons, PET scanners, and radiochemistry laboratories. In recent years, because of advancements in technology and proliferation of PET scanners, PET is being increasingly used in clinical neurology to improve our understanding of disease pathogenesis, to aid with diagnosis, and to monitor disease progression and response to treatment. This article aims to provide an overview of the principles of PET and its applications to clinical neurology.

Brain↗
PubMed1969

Effect of diet and triiodothyronine on the activity of sn-glycerol-3-phosphate dehydrogenase and on the metabolism of glucose and pyruvate by adipose tissue of obese patients.

Lipogenesis and the metabolism of sn-glycerol-3-phosphate were studied in 23 fat biopsies from eight grossly obese patients. The first biopsy was obtained after a minimum of 12 days on a 3500 cal diet, the second biopsy after 2 wk on a 900 cal diet, and the third biopsy after an additional 2 wk on 900 cal supplemented with thiiodothyronine, 250 mug/day.Oxygen consumption and respiratory quotient declined during caloric restriction. Oxygen consumption was restored to the initial level during treatment with triiodothyronine, and the respiratory quotient rose somewhat.Lipogenesis from glucose and pyruvate was demonstrated in fat obtained from the first biopsy but could not be detected in the other biopsies. The incorporation of radioactivity from pyruvate into fatty acids was stimulated by the addition of glucose. Insulin stimulated lipogenesis in pieces of fat from the first biopsy, but isolated fat cells were unaffected by insulin. After caloric restriction no effects of insulin could be detected. The activity of both the cytoplasmic and mitochondrial sn-glycerol-3-phosphate dehydrogenase in homogenates of adipose tissue declined with caloric restriction. Treatment with triiodothyronine enhanced the activity of the mitochondrial sn-glycerol-3-phosphate dehydrogenase but did not affect the cytoplasmic enzyme.

Adipose Tissue↗
PubMed1976

Enzymatic radioiodination of succinyl cyclic AMP tyrosine methyl ester by lactoperoxidase and radioimmunoassay for cyclic AMP.

A highly specific and simple radioimmunoassay for cyclic AMP with a sensitivity of 0.04 picomoles/tube has been developed according to the method of Steiner et al., using 125I-succinyl cyclic AMP tyrosine methyl ester as a tracer. The tracer with higher immunoactivities could be simply and constantly prepared by an enzymatic iodination procedure utilizing lactoperoxidase, radioactive iodide and hydrogen peroxide generated by glucose-glucose oxidase system, rather than by chloramine-T procedure.

Adipose Tissue↗
PubMed1988

Cerebral energy metabolism following fluid-percussion brain injury in cats.

Clinical and experimental evidence suggests that head injury can cause alterations of cerebral energy metabolism. However, the etiology of this metabolic perturbation is not known. The objective of this study was to determine the effect of fluid-percussion trauma on cerebral energy metabolism. Seven ventilated, chloralose-anesthetized cats were subjected to a 3.2-atm fluid-percussion brain injury. Before and for 8 hours after trauma, continuous phosphorus-3 1 magnetic resonance spectrography was obtained to noninvasively monitor tissue pH, phosphocreatine (PCr), and inorganic phosphate (Pi) levels. Measurement of cerebral blood flow (CBF) by the radioactive microsphere technique and calculation of oxygen and glucose consumption (CMRO2 and CMRG1) were also performed before trauma as well as 30 minutes and 1, 2, 4, and 8 hours after trauma. The data showed a moderate decrease in tissue pH from 7.04 to 6.89 at 30 minutes following trauma with return to control levels by 3 hours posttrauma. During the 8-hour observation period, CBF, CMRO2, and CMRG1 remained at control levels. Tissue PCr and Pi levels were also unchanged. Fluid-percussion trauma at the 3.2-atm level in ventilated cats causes a moderate and transient decrease in tissue pH that returns to control levels after trauma. No other metabolic changes are seen later than 30 minutes posttrauma. This indicates that a mild metabolic disturbance occurs after trauma in the ventilated animal and quickly returns to normal.

Animals↗
PubMed1992

Evaluation of liver tumors using fluorine-18-fluorodeoxyglucose PET: characterization of tumor and assessment of effect of treatment.

To evaluate glucose metabolism in patients with tumors involving the liver, 35 patients with liver lesions had PET using 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG (148 MBq) was injected and radioactivity of the tumor was scanned dynamically by PET. The rate constants (k1, k2, k3, k4) of FDG in a metabolic model were calculated. The results were compared to hexokinase activity in the excised tumor specimens. k3 was found to reflect tumor hexokinase activity. When k3 was used as an index (cut-off value: 0.025), it was possible to distinguish benign and malignant tumors. k4 was significantly higher in hepatocellular carcinoma. By using k3 and k4 as indices, one could assess the degree of differentiation of hepatocellular carcinoma. After treatment, k3 decreased according to the effectiveness of therapy and thus may be a useful index for quantitatively assessing tumor viability.

Adenoma, Bile Duct↗
PubMed1989

[Effect of cadmium on C-14-glucose uptake by Staphylococcus aureus].

The aim of the study was to evaluate an influence of Cd++ on 14C-glucose uptake by two strains of S. aureus resistant and sensitive to cadmium in 0.1 M phosphate buffer, pH 7.0. Uptake of this sugar in both strains is an active process in which energy comes from oxidation of endogenous substrates, what was shown in aerobic condition, anaerobic condition at temperatures of 37 degrees C and 4 degrees C, and with p-CMB and CCCP. In the resistant strains Cd++ at 10 microM concentration did not inhibit endogenous respiration, 14C-glucose uptake and its oxidation. This is due to presence of energy-dependent system of 2H+/Cd++ antiport coded by cadA genes located on penicillinase pII17810 plasmid, which eliminated Cd++ from bacterial cell. In the case of plasmid free variant deprived of this system, Cd++ is retained in cytoplasm and blocks endogenous respiration uptake, and oxidation of glucose.

Cadmium↗
PubMed1998

[A new method of evaluating the utilization of nutrients (carbohydrates, amino acids and fatty acids) on the plastic and energy goals in the animal body].

With use of a new method, based on detection in blood serum of radioactivity of water, formed from tritium marked precursors--glucose, amino acids (valine, serine, histidine) and palmitine acid--their distribution on oxidizing and anabolic ways of metabolism was determined. The work was carried out on laboratory rats. In young pubertal rats the ratio of flows on these ways for glucose was found equal 2.83, i.e. it in a greater degree was used as energy substratum. On the contrary, for palmitine acid this ratio was equal 0.10--it was comprised in a plastic material of organism in a greater degree. For serine, histidine and valine it is equal 0.34, 0.71 and 0.46, accordingly. In growing rats the distribution of flows was shifted aside of anabolic way: the ratio of flows is equal 0.19; in old rats--aside of oxidizing: a ratio of flows is equal 0.71.

Amino Acids↗
PubMed1980

Rat brain antigen concentration measured by 14C-labeled immunoprecipitates.

Newborn rats were labeled with [14C]glucose during the first 35 days of life. Specific radioactivity was the same in fibrin, hemoglobin and brain proteins. The radioactivity precipitated in specific immunoprecipitates obtained on crossed immunoelectrophoresis with polyspecific antisera was used to calculate the amounts of synaptosomal antigens. Immunoprecipitable D1, D2, and D3 amounted to approximately 3.0%, 2.2% and 2.4% of rat forebrain proteins respectively.

Animals↗
PubMed1995

A new pathway for the synthesis of the plant sulpholipid, sulphoquinovosyldiacylglycerol.

A new pathway is proposed for the biosynthesis of the plant sulpholipid, sulphoquinovosyldiacylglycerol. The pathway begins at UDP-glucose and involves the formation therefrom of UDP-4-ketoglucose-5-ene to which is subsequently added sulphite (or its metabolic equivalent). Evidence consistent with this pathway, rather than with the previously proposed 'sulphoglycolytic' route, was obtained from experiments with pea chloroplast preparations. The evidence included the failure of potential inhibitors of the sulphoglycolytic pathway to alter the rate of synthesis of sulpholipid and the stimulation of the incorporation of 35SO4(2-) into the latter by UTP. Radioactivity was effectively incorporated into sulpholipid from UDP-[14C]glucose and this radiolabelling was stimulated by the addition of methyl alpha-glucose-enide or of an enzyme system known to be forming (although not accumulating) UDP-4-ketoglucose-5-ene. This new pathway is also consistent with other data in the literature.

Chloroplasts↗
PubMed1972

Sugar transport in immature internodal tissue of sugarcane: I. Mechanism and kinetics of accumulation.

Transmembrane sugar transport into immature internodal parenchyma tissue of sugarcane (Saccharum officinarum L.) is a metabolically regulated process as evidenced by its sensitivity to pH, temperature, anaerobiosis, and metabolic inhibitors. All sugars studied-glucose, fructose, galactose, sorbose, glucose 6-phosphate, 3-O-methylglucose, and 2-deoxy-d-glucose-were apparently transported via the same carrier sites since they competed with each other for uptake. External concentrations of these sugars at one-half V(max) were in the range of 3.9 to 8.4 nm. Preliminary data indicated that phosphorylation may be closely associated with glucose transport. The dominant intracellular sugar after 4-hours incubation was sucrose when glucose, glucose-6-P, or fructose was the exogenously supplied sugar; but when galactose was supplied, only 28% of intracellular radioactivity was in sucrose. Sorbose, 3-O-methylglucose, and 2-deoxy-d-glucose were not metabolized. Thus, by using these analogs, transport could be studied independently of subsequent metabolism, effectively eliminating a complicating factor in previous studies.

Journal Article↗
PubMed1993

Analysis of inositol metabolites produced by Saccharomyces cerevisiae in response to glucose stimulation.

When cultures of Saccharomyces cerevisiae are grown to stationary phase in medium containing [3H] inositol, significant amounts of radioactivity can be detected in phosphatidylinositol, phosphatidylinositol 3-phosphate, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate. Addition of glucose to such cultures results in the generation of [3H]glycerophosphoinositol, [3H]glycerophosphoinositol 4-phosphate, and [3H]glycerophosphoinositol 4,5-bisphosphate in the extracellular medium. We found no evidence, however, for the stimulated formation of other inositol polyphosphates. This result suggests that glucose does not stimulate the "phospholipase C" signalling pathway established in higher eukaryotic cells but, in contrast, stimulates specific phospholipases A or B. A variety of cell division cycle (cdc) mutants have been studied to investigate the relationship between cell cycle progression and inositol metabolism in S. cerevisiae. Mutants which are defective for completion of cell cycle "START" (i.e. commitment to mitosis) show reduced formation of glycerophosphoinositol 4-phosphate and glycerophosphoinositol 4,5-bisphosphate in response to glucose. In contrast, cdc mutants which are defective in post-"START" processes show a larger glucose response than wild type cells. These results suggest that deacylation of phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate may be coordinated with cell cycle control in S. cerevisiae.

Carbon Radioisotopes↗
PubMed1989

Phosphoglucoisomerase-catalyzed interconversion of hexose phosphates; diastereotopic specificity, isotopic discrimination and intramolecular hydrogen transfer.

When D-[1-3H]fructose 6-phosphate generated from D-[2-3H]glucose 6-phosphate is converted, in a monodirectional manner to D-glucose 6-phosphate and then 6-phospho-D-gluconate, about 42% of the radioactivity is transferred from the C1 of the ketohexose ester to the C2 of the aldohexose phosphate, whereas the remaining 58% are produced as 3H2O. The velocity of the reaction catalyzed by phosphoglucoisomerase represents, in the case of the tritiated substrate, only 43% of that recorded with D-[U-14C]fructose 6-phosphate, such an isotopic discrimination being attributable mainly to a difference in maximal velocity rather than affinity. The phenomena of both intramolecular hydrogen transfer and isotopic discrimination were less pronounced than when D-[2-3H]glucose 6-phosphate is converted, in a monodirectional manner, to D-fructose 6-phosphate and then D-fructose 1,6-bisphosphate. In contrast, when either D-[1-3H]glucose 6-phosphate or D-[1-3H]fructose 6-phosphate prepared from D-[1-3H]glucose were tested, no 3H2O was formed, all radioactivity being recovered, respectively, in tritiated D-fructose 1,6-bisphosphate or NADP3H. Nevertheless, phosphoglucoisomerase was also found to discriminate between D-[U-14C]glucose 6-phosphate and D-[1-3H]glucose 6-phosphate or between D-[U-14C]fructose 6-phosphate and D-[1-3H]fructose 6-phosphate prepared from D-[1-3H]glucose. The reaction velocity with the tritiated esters averaged 78-83% of those recorded with the 14C-labelled esters. Such an isotopic discrimination was again attributable mainly to a difference in maximal velocity rather than affinity. These findings indicate that the mode of preparation of D-[1-3H]fructose cannot be ignored in considering the fate of this tritiated hexose, as ruled by the intrinsic properties, and especially the diastereotopic specificity of phosphoglucoisomerase.

Carbon Radioisotopes↗
PubMed1980

Cold exposure and mammary glucose metabolism in the lactating goat.

1. [U-14C]glucose was infused intravenously into conscious lactating goats exposed to thermoneutral or cold environments for a total of 24 h. The irreversible loss of glucose from the whole body and uptake of glucose by the mammary gland was measured and glucose utilization in the udder was studied by measuring the incorporation of radioactivity into carbon dioxide in mammary venous blood, into milk lactose and milk triglyceride-glycerol. 2. Exposure to cold increased the circulating level of glucose and slightly though not significantly, increased the non-mammary irreversible loss of glucose. 3. The extraction of glucose from the circulation by the udder fell, the secretion of lactose by the udder also fell and this correlated closely with the reduced secretion of milk in the cold. 4. Simultaneous measurements of the concentrations of insulin, growth hormone and corticosteroids in the arterial plasma were made. 5. The plasma concentration of corticosteroids increased significantly in the cold. 6. It is concluded that reduced glucose uptake and lactose synthesis by the udder are important factors which reduce milk secretion during cold exposure.

Animals↗
PubMed1984

Glucose requirement for induction by sodium butyrate of the glycoprotein hormone alpha subunit in HeLa cells.

Butyric acid produces multiple effects on mammalian cells in culture, including alterations in morphology, depression of growth rate, increased histone acetylation, and modified production of various proteins and enzymes. The latter effect is exemplified by the induction in HeLa cells of the glycoprotein hormone alpha subunit by millimolar concentrations of the fatty acid. This report demonstrates that increased subunit accumulation in response to sodium butyrate is strikingly dependent on the presence of glucose (or mannose) in the growth medium. In contrast, basal levels of subunit synthesis are only marginally affected when the culture medium is supplemented with one of a variety of hexoses. An increase in the accumulation of HeLa alpha does not occur in medium containing pyruvate as the energy source, and sustained induction requires the simultaneous and continued presence of both glucose and butyrate. The effects of butyrate on HeLa cell morphology and subunit induction can be separated, since the latter is glucose-dependent while the former is not. Failure of butyrate to induce alpha in medium containing pyruvate does not result from restricted subunit secretion, since the levels of intracellular alpha are not increased disproportionately relative to those in the medium. The hexoses which support induction of HeLa alpha (glucose greater than or equal to mannose greater than galactose greater than fructose) are identical to those which have been shown previously to stimulate the glucosylation of lipid-linked oligosaccharides and enhance the synthesis of certain glycoproteins. Labeling of various glycosylation intermediates with [3H]mannose indicates that in glucose medium there is a decrease in the level of radioactivity associated with both dolicholpyrophosphoryl oligosaccharide and cellular glycoproteins and a concomitant increase in the fraction of label recovered in secreted glycoproteins. Butyrate also causes a decrease in [3H]mannose-labeled cellular glycoproteins and an increase in tritiated extracellular glycoproteins, particularly in glucose medium. Likewise, glucose stimulates the incorporation of [3H]glucosamine into immunoprecipitable alpha subunit relative to the bulk of HeLa-secreted glycoproteins, and this is further enhanced by butyrate. However, as demonstrated by lectin chromatography of conditioned media, a nonglycosylated subunit does not accumulate in pyruvate medium, either in the absence or presence of butyrate.(ABSTRACT TRUNCATED AT 400 WORDS)

Butyrates↗