SEARCH · PubMed Health

Results for “GLUCOSE, RADIOACTIVE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources

PubMed1989

[Effects of exogenous insulin on oxidation of glucose and fatty acid in septic rats].

The effects of exogenous insulin on oxidation of glucose and fatty acid were investigated in septic (n = 20) and control rats (n = 20). Sepsis was induced by ligation and puncture of the caecum. The rats received intravenous nutrition with glucose as a non-protein calorie for 27 hours. Ten rats in each group received insulin intravenously at a rate of 0.64U/kg/hr during the last 6 hours of the intravenous nutrition, U-14C-glucose or 1-14C-linoleic acid at a dose of 1.563 microCi each was injected as a bolus at the 21st hour of the intravenous nutrition. Cumulative 14CO2 production was measured for 6 hours after the injection of the radioactive substrates. 14CO2 production from both glucose and linoleic acid was inhibited by the sepsis. 14CO2 production from glucose was accelerated by exogenous insulin in the control rats, while it was not accelerated in the septic rats. Exogenous insulin did not affect 14CO2 production from linoleic acid in both the control and the septic rats. These results indicate that, under the condition of sepsis, lowering blood sugar level with exogenous insulin does not refLect an increase in oxidation of glucose.

Animals↗

PubMed1983

A potential error in modifications of the [14C]2-deoxyglucose technique.

Although the technique developed by Sokoloff et al. employing [14C]2-deoxyglucose as tracer, provides measurements of local cerebral glucose utilization, various modifications of the original technique are presently in widespread use. We have examined the validity of a crucial simplifying assumption which is an integral feature of many of these modifications; namely, that all the radioisotope in the CNS at the moment of sacrifice is present as 2-deoxyglucose-6-phosphate. By employing the kinetic model developed by Sokoloff et al. and arterial plasma [14C]2-deoxyglucose and glucose histories, the proportion of total radioactivity present in the CNS as unphosphorylated 2-deoxyglucose was calculated and found to vary from 5 to 50% of the total amount of isotope present in the CNS under different experimental conditions. It can be shown to be dependent upon (a) the rate of cerebral glucose utilization, (b) the time which elapses from administration of the radioisotope until the sacrifice, (c) the route by which the isotope is administered, and (d) arterial plasma glucose levels. Thus, modifications of the original 2-deoxyglucose technique have introduced a potential source of error which is not a feature of the approach of Sokoloff and his associates.

Animals↗

PubMed1988

The second component of human complement: use of glycosidases and glucosylation to distinguish the two forms.

The two forms of human plasma C2 that were described in the preceding report (1) were investigated for their functional and biochemical differences. Incubation with the neuraminidase (NAN'dase) of Clostridium perfringens at 37 degrees C resulted in a four- to fivefold increase in the hemolytic activity of both forms. The increase in activity was different than the increase caused by treatment with iodine. The mechanism of increased activity of NAN'dase-treated C2 was the generation of increased molecules of activated C3 (C3b), resulting in more molecules of C5 binding to (C4b, 2a, 3b)n. Removal of N-acetyl-neuraminate from C2 did not alter its binding to a cationic exchanger. Nonenzymatic glucosylation was used to distinguish the two forms of C2. Incubation of highly pure C2 with 14C-D-glucose resulted in the gradual accumulation of radioactivity in acid-precipitable material. The two forms of C2 were glucosylated in vitro for seven days with 14C-D-glucose in phosphate-buffered saline at 25 degrees C. Form 2 bound twice as much 14C-D-glucose as form 1. Glucosylated form 2, but not form 1, lost some of its affinity to bind to a cationic exchanger. Since the interaction between glucose and protein occurs at free amino groups, we conclude that form 2 of C2 has approximately twice as many free amino groups as form 1. This explains the reason for the existence of two forms of C2 in plasma independent of the allelic variant.

Complement C2↗

PubMed1993

Hexose metabolism in pancreatic islets: time-course of the oxidative response to D-glucose.

The time-course for the generation of 3HOH from D-[5-3H]glucose and for the production of 14CO2, 14C-labelled acidic metabolites and radioactive amino acids from D-[3,4-14C]glucose, D-[2-14C]glucose and D-[6-14C]glucose was monitored, over 60 to 120 min incubation, in both rat pancreatic islets and parotid cells exposed to a low or high concentration of the hexose. In islets stimulated by D-glucose, a progressive increase in the oxidation rate of glucose-derived acetyl residues was observed. Such a phenomenon was not observed in islets exposed to a low concentration of D-glucose, concerned specifically the oxidation of acetyl residues in the Krebs cycle as distinct from their generation in the reaction catalyzed by pyruvate dehydrogenase, and failed to occur in parotid cells. It is concluded that the increase in the oxidation rate of glucose-derived acetyl residues found in pancreatic islets represents an unusual phenomenon not encountered in other cell types and specifically regulated in terms of its time-course, concentration dependency and relationship to other oxidative events.

Amino Acids↗

PubMed1967

The secretion of newly synthesized insulin in vitro.

1. An immunological method for the purification of small quantities of insulin has been devised. 2. This method has been used to isolate labelled insulin secreted from pancreas slices incubated in vitro. The insulin had previously been labelled by incubation of the slices with [(3)H]leucine in vitro. 3. There is some release of labelled insulin when such slices are further incubated in media of low glucose content. When the glucose content of the medium is raised, little additional radioactive insulin is released in the first hour after labelling. However, there is a marked increase in specific radioactivity of insulin released from slices in response to a high concentration of glucose in the second and third hours. Release of labelled insulin is again diminished in the final phase, 4hr. from the start of the experiment. 4. These results are discussed in relation to possible mechanisms of insulin release from the beta-cell.

Journal Article↗

PubMed1987

In vivo glucose absorption by neomucosa.

Growing neomucosa has been investigated as a means of permanently increasing intestinal absorption in the short-bowel syndrome. The purpose of this study was to quantitate in vivo glucose absorption by neomucosa and correlate this with neomucosal growth. Thirteen New Zealand White rabbits (2.3 to 3.8 kg) had 2 by 5 cm ileal defects patched with colon serosa, and there was 12 control animals. Glucose absorption was determined by measuring the appearance of radioactivity in the portal vein and vena cava after topical application of [14C]-glucose. At 2 weeks the patched defect is partially covered by a thin layer of columnar epithelial cells. Mature villi are present at 8 weeks. The maximum rate of absorption by neomucosa was significantly greater 8 weeks after patching than at 2 or 4 weeks (0.067 +/- 0.103 versus 0.020 +/- 0.004 and 0.012 +/- 0.003 microCi/min) but was significantly less than normal mucosa (0.264 +/- 0.142 microCi/min, p less than 0.05). Similarly, glucose absorption in the first 20 minutes by neomucosa was greater at 8 weeks than at 2 and 4 weeks (13.0% +/- 6.2% versus 4.7% +/- 0.5% and 6.5% +/- 1.33%, p less than 0.05). Colon serosa also absorbed significant glucose. Neomucosa absorbs glucose in vivo. The rate and amount of absorption correlate with neomucosal growth. Significant glucose absorption by colon serosa has implications for the transperitoneal delivery of nutrients.

Animals↗

PubMed1962

OXIDATIVE ASSIMILATION OF GLUCOSE BY PSEUDOMONAS AERUGINOSA.

Duncan, Margaret G. (The University of British Columbia, Vancouver, British Columbia, Canada) and J. J. R. Campbell. Oxidative assimilation of glucose by Pseudomonas aeruginosa. J. Bacteriol. 84:784-792. 1962-Oxidative assimilation of glucose by washed-cell suspensions of Pseudomonas aeruginosa was studied using C(14)-labeled substrate. At the time of glucose disappearance, only small amounts of radioactivity were present in the cells, and alpha-ketoglutaric acid accumulated in the supernatant fluid. Most of the material synthesized by the cells during oxidative assimilation was nitrogenous, the ammonia being supplied by the endogenous respiration. The cold trichloroacetic acid-soluble fraction and the lipid fraction appeared to be important during the early stages of oxidative assimilation, and the largest percentage of the incorporated radioactivity was found in the protein fraction. In the presence of added ammonia, assimilation was greatly increased and no alpha-ketoglutaric acid was found in the supernatant fluid. Sodium azide partially inhibited incorporation into all major cell fractions, and at higher concentrations depressed the rate of glucose oxidation. During oxidative assimilation, chloramphenicol specifically inhibited the synthesis of protein. Oxidative assimilation of glucose by this organism did not appear to involve the synthesis of a primary product such as is found in the majority of bacteria.

Journal Article↗

PubMed1975

Incorporation of exogenous D-glucose-1-(14)C and D-manose-1-(14)C into glycogen and lactate excreted by Angiostrongylus cantonensis in vitro.

The amount of labelled glucose incorporated into glycogen is 6 times as much as that of labelled mannose by the female worms. They excreted lactate of labelled glucose-origin 3-4 times as much as that of labelled mannose-origin. The amount of labelled glucose incorprated in worm bodies is about 3 times as much as that of labelled mannose. Male worms absorbed a half amount of glucose by female worms. Paralelled with radioactivity studies mentioned above, chemical determinations of sugars, lactate, and glycogen were performed on the media prior and posterior to incubation and the worms. The results obtained from chemical determinations fairly agreed with those on lactate production and sugar consumption from radioactivity studies, but not on glycogen content of worms after incubation. Chemical determination shows no glycogen synthesis in worms incubated in mannose media while the radioactivity of labelled mannose was detected, though it is very low in activity, from glycogen of worms in the media. Coupled with previously reported findings, results from the present study show mannose to be far less significant in the carbohydrate metabolism of Angiostrongylus cantonensis as compared with glucose.

Journal Article↗

PubMed2003

The importance of amino acids as carbon sources for Micromonospora echinospora (ATCC 15837).

AIMS: This study set out to investigate the effect of amino acids on the uptake of glucose by Micromonospora eichinospora (ATCC 15837). METHODS AND RESULTS: The specific rate of glucose uptake was found to be reduced when organic nitrogen components were present in the medium. Radioactive uptake studies revealed that the Km for glucose in this organism was 53 mm, indicating a low affinity for uptake compared with other actinomycete sugar transport systems. Individual amino acids negatively influenced the rate of glucose transport, suggesting a relationship between amino acid metabolism and glucose uptake in this organism. The sugar transport system was found to be an active process being inhibited by ionophores and KCN. CONCLUSIONS: The data suggest a direct link between amino acid metabolism and glucose uptake at the level of sugar transport. SIGNIFICANCE AND IMPACT OF THE STUDY: This study shows that the uptake of glucose, a major carbon source for many antibiotic fermentations, is significantly reduced in the presence of amino acids. This fact should inform the medium design and feeding regimes of fermentations involving similar actinomycetes.

Amino Acids↗

PubMed1985

Hepatic oxygen consumption, lactate uptake, and glucose production in neonatal lambs.

Previous studies have evaluated neonatal hepatic metabolism in vitro, and neonatal hepatic oxygen consumption has been measured in vivo, but direct measurements of neonatal hepatic metabolism have not been reported. We studied seven neonatal lambs at age 7-10 days after placing catheters chronically in the hepatic vein, portal vein, descending aorta, left ventricle, and inferior vena cava. Hepatic blood flow was measured by the radioactive microsphere technique. Oxygen consumption and glucose and lactate fluxes were measured using the Fick principle. 14C-lactate was infused intravenously and lactate and glucose specific activities were measured and used to calculate hepatic gluconeogenesis from lactate. Neonatal hepatic blood flow was 254.5 +/- 50.3 ml/min/100 g (mean +/- SD) with 5.4 +/- 4.6% from the hepatic artery and 94.6 +/- 4.6% from the portal vein. Hepatic oxygen consumption was 7.2 +/- 2.4 ml/min/100 g and oxygen extraction was 44.9 +/- 15.4%. Oxygen extraction correlated inversely with oxygen delivery. In the seven lambs, there was net hepatic lactate uptake of 10.2 +/- 5.0 mg/min/100 g (1.13 +/- 0.56 mM) and hepatic glucose production of 30.8 +/- 11.3 mg/min/100 g (1.71 +/- 0.62 mM). In the five lambs in which hepatic gluconeogenesis was measured, 12.4 +/- 5 mg (1.37 +/- 0.56 mM) of lactate was converted to glucose per 100 g liver, accounting for 38.4% of the hepatic glucose production in these lambs. Blood flow and oxygen and substrate delivery to the neonatal liver are lower than those to the fetal liver but the neonatal liver extracts more oxygen and substrates and is able to produce glucose by gluconeogenesis from lactate.

Animals↗

PubMed2005

2-NBDG as a fluorescent indicator for direct glucose uptake measurement.

Evaluation of glucose uptake ability in cells plays a fundamental role in diabetes mellitus research. In this study, we describe a sensitive and non-radioactive assay for direct and rapid measuring glucose uptake in single, living cells. The assay is based on direct incubation of mammalian cells with a fluorescent d-glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose (2-NBDG) followed by flow cytometric detection of fluorescence produced by the cells. A series of experiments were conducted to define optimal conditions for this assay. By this technique, it was found that insulin lost its physiological effects on cells in vitro meanwhile some other anti-diabetic drugs facilitated the cell glucose uptake rates with mechanisms which likely to be different from those of insulin or those that were generally accepted of each drug. Our findings show that this technology has potential for applications in both medicine and research.

4-Chloro-7-nitrobenzofurazan↗

PubMed1988

Effects of moderate ethanol sedation on brain regional 2-deoxyglucose uptake in alcohol-sensitive and alcohol-insensitive rat lines.

Acute intraperitoneal ethanol administration (2 g/kg) decreased the accumulation of radioactivity after [14C]2-deoxy-D-glucose injection into grossly dissected brain regions of alcohol-sensitive (ANT) and alcohol-insensitive (AT) rat lines. In autoradiography, the balance of radioactivity uptake between different functional systems (as judged from relative optical density ratios) was changed after ethanol: especially in the ANT rats, areas associated with sensory input were damped but motor relay nuclei were relatively active, suggesting a tendency to motor overactivity relative to sensory input. The ANT rats furthermore showed slight relative damping of cortical associative areas and differences in limbic structures compared to the AT rats, which, provided that changes in the balance between brain regions with a decreased overall activity are meaningful, suggests that the higher level of ethanol-induced motor impairment of the ANT rats may be related to defects in their integration of sensory and motor processes.

Animals↗

PubMed1981

The regional distribution of d-amphetamine and local glucose utilization in rat brain during continuous amphetamine administration.

The distribution of radioactivity following administration of either [3H]d-ampetamine or [3H]2-deoxy-d-glucose was examined by scintillation counting of 22 microdissected brain regions from rats pretreated with either acute or continuous amphetamine, or continuously administered labeled d-amphetamine. Animals continuously administered drug were sacrificed in behaviorally distinct stages of the continuous amphetamine syndrome, a potential animal model of amphetamine psychosis. Both isotopes were heterogeneously distributed within brain, and their distributions were differentially affected by acute or continuous amphetamine regimens. While the distribution of either isotope in naive rats was characterized by greatest concentrations of counts in rostral rather than caudal regions, and grey-matter rather than white-matter structures, continuous amphetamine administration resulted in progressively increased retention of amphetamine by mesolimbic but not nigrostriatal brain regions; this was accompanied by locally enhanced levels of glucose utilization. This effect was predominantly localized in the nucleus accumbens, which exhibited the greatest retention of amphetamine and greatest relative increase in glucose utilization of any region studied during that stage of the continuous amphetamine syndrome thought to best model amphetamine psychosis. Alterations in amphetamine distribution and local levels of neural activity may reflect a change in the principal locus of control of amphetamine effects within brain as animals progress through the stages of the continuous amphetamine syndrome.

Amphetamine↗

PubMed1995

Glycogen turnover in the isolated working rat heart.

The isolated working rat heart was adapted for simultaneous determination of glycogen synthesis and degradation using a dual isotope technique. After prelabeling of glycogen with [U-14C]glucose, glycogenolysis was determined continuously from the washout of 14CO2 plus [14C]lactate. Glycogen synthesis was determined during the same period from incorporation of [5-3H]glucose. In the absence of added hormones, hearts were predominantly glycogenolytic (1.5 mumol/min/g, dry weight), and there was simultaneous synthesis (11% of the rate of glycogenolysis). The percentage of glucose taken up by the heart that could traverse the glycogen pool as a consequence of glycogen turnover was minor (5%). Insulin (10 milliunits/ml) predictably stimulated glycogen synthesis (3.6-fold) and nearly abolished glycogenolysis. Addition of glucagon (1 microgram/ml) increased contractile performance and initially stimulated glycogenolysis (3.8-fold) until glycogen was largely depleted. Net tritium incorporation was unaffected by glucagon. Both hormones stimulated glycolytic flux from exogenous glucose (3H2O from [5-3H]glucose) as well as total glycolytic flux (3H2O plus glycogenolysis). The initial stimulation in total glycolytic flux with glucagon was largely from glycogen, explaining the lag in stimulation from exogenous glucose. The relationship between the specific radioactivity and amount of glycogen remaining after different degrees of glycogenolysis suggests that the preference of glycogenolysis for newly synthesized glycogen is only partial.

Animals↗

PubMed1993

Transmembrane glucose transport in skeletal muscle of patients with non-insulin-dependent diabetes.

Insulin resistance for glucose metabolism in skeletal muscle is a key feature in non-insulin-dependent diabetes mellitus (NIDDM). Which cellular effectors of glucose metabolism are involved is still unknown. We investigated whether transmembrane glucose transport in vivo is impaired in skeletal muscle in nonobese NIDDM patients. We performed euglycemic insulin clamp studies in combination with the forearm balance technique (brachial artery and deep forearm vein catheterization) in six nonobese NIDDM patients and five age- and weight-matched controls. Unlabeled D-mannitol (a nontransportable molecule) and radioactive 3-O-methyl-D-glucose (the reference molecular probe to assess glucose transport activity) were simultaneously injected into the brachial artery, and the washout curves were measured in the deep venous effluent blood. In vivo transmembrane transport of 3-O-methyl-D-glucose in forearm muscle was determined by computerized analysis of the washout curves. At similar steady-state plasma concentrations of insulin (approximately 500 pmol/liter) and glucose (approximately 5.15 mmol/liter), transmembrane inward transport of 3-O-methyl-D-glucose in skeletal muscle was markedly reduced in the NIDDM patients (6.5 x 10(-2) +/- 0.56 x 10(-2).min-1) compared with controls (12.5 x 10(-2) +/- 1.5 x 10(-2).min-1, P < 0.005). Mean glucose uptake was also reduced in the diabetics both at the whole body level (9.25 +/- 1.84 vs. 28.3 +/- 2.44 mumol/min per kg, P < 0.02) and in the forearm tissues (5.84 +/- 1.51 vs. 37.5 +/- 7.95 mumol/min per kg, P < 0.02). When the latter rates were extrapolated to the whole body level, skeletal muscle accounted for approximately 80% of the defect in insulin action seen in NIDDM patients. We conclude that transmembrane glucose transport, when assessed in vivo in skeletal muscle, is insensitive to insulin in nonobese NIDDM patients, and plays a major role in determining whole body insulin resistance.

Adult↗

PubMed1990

Nickel availability and urease expression in Proteus mirabilis.

Cells of Proteus mirabilis, previously grown in nutrient broth (NB), exhibited an increase in urease activity during subsequent incubation in mineral medium even when protein biosynthesis was inhibited. During growth in NB, degradation of amino acids obviously led to the formation of nickel-complexing metabolites, and nickel ions were therefore unavailable for maximal expression of enzymatically active urease; this inhibition of urease biosynthesis was overcome by the addition of nickel to the growth medium, and also by added glucose. Experiments concerning the incorporation of radioactive nickel into urease finally indicated that the observed increase in urease activity was caused by posttranslational insertion of nickel into performed apo-urease.

Amino Acids↗

PubMed1983

Metabolism of C-labeled photosynthate and distribution of enzymes of glucose metabolism in soybean nodules.

The metabolism of translocated photosynthate by soybean (Glycine max L. Merr.) nodules was investigated by (14)CO(2)-labeling studies and analysis of nodule enzymes. Plants were exposed to (14)CO(2) for 30 minutes, followed by (12)CO(2) for up to 5 hours. The largest amount of radioactivity in nodules was recovered in neutral sugars at all sampling times. The organic acid fraction of the cytosol was labeled rapidly. Although cyclitols and malonate were found in high concentrations in the nodules, they accumulated less than 10% of the radioactivity in the neutral and acidic fractions, respectively. Phosphate esters were found to contain very low levels of total label, which prohibited analysis of the radioactivity in individual compounds. The whole nodule-labeling patterns suggested the utilization of photosynthate for the generation of organic acids (principally malate) and amino acids (principally glutamate).The radioactivity in bacteroids as a percentage of total nodule label increased slightly with time, while the percentage in the cytosol fraction declined. The labeling patterns for the cytosol were essentially the same as whole nodule-labeling patterns, and they suggest a degradation of carbohydrates for the production of organic acids and amino acids. When it was found that most of the radioactivity in bacteroids was in sugars, the enzymes of glucose metabolism were surveyed. Bacteroids from nodules formed by Rhizobium japonicum strain 110 or strain 138 lacked activity for phosphofructokinase and NADP-dependent 6-phosphogluconate dehydrogenase, key enzymes of glycolysis and the oxidative pentose-phosphate pathways. Enzymes of the glycolytic and pentose phosphate pathways were found in the cytosol fraction.In three experiments, bacteroids contained about 10 to 30% of the total radioactivity in nodules 2 to 5 hours after pulse-labeling of plants, and 60 to 65% of the radioactivity in bacteroids was in the neutral sugar fraction at all sampling times. This strongly suggests some absorption and metabolism of sugars by bacteroids in spite of the lack of key enzymes. Bacteroids did possess enzymes for the formation of hexose phosphates from glucose or fructose. Radioactivity in alpha,alpha-trehalose in bacteroids increased until, after 5 hours, trehalose was a major labeled compound in bacteroids. Thus, trehalose synthesis may be a major fate of sugars entering bacteroids.

Journal Article↗

PubMed1977

Identification of UDP-glucose as an intermediate in the biosynthesis of the membrane-derived oligosaccharides of Escherichia coli.

The membrane-derived oligosaccharides of Escherichia coli constitute a closely related family of oligosaccharides containing approximately 9 glucose units variously substituted with sn-glycero-1-phosphate and phosphoethanolamine residues derived from the head groups of membrane phospholipids, and also with succinate in O-ester linkage (Kennedy, E.P., Rumley, M.K., Schulman, H., and van Golder, L.M.G. (1976) J. Biol. Chem. 251, 4208-4213). Studies with mutant strains defective in the synthesis of various nucleoside diphosphate sugars have now revealed that UDP-glucose is an essential intermediate in the biosynthesis of these oligosaccharides. Mutants unable to synthesize UDP-glucose do not contain significant amounts of the membrane-derived oligosaccharides. In contrast, a strain unable to synthesize ADP-glucose, the glucosyl donor for glycogen synthesis in E. coli, contained normal amounts of the membrane-derived oligosaccharides, although with a somewhat different pattern of distribution of the various subspecies. In confirmation of these genetic studies, pulse-label isotope tracer studies have been carried out with glucose of high specific activity, under conditions in which UDP-glucose comprises a large fraction of the total radioactivity in the low molecular weight pool. Subsequent "chase" experiments clearly revealed the conversion of UDP-glucose to the higher molecular weight membrane-derived oligosaccharides.

Cell Membrane↗