PubMed Health⌕ Search

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 577 records · Page 32Linked to original sources
PubMed1987

In vitro synthesis of cellulose II from a cytoplasmic membrane fraction of Acetobacter xylinum.

The cytoplasmic and outer membranes of Acetobacter xylinum (ATCC 53582) were isolated by discontinuous sucrose density ultracentrifugation. Both lysozyme (EC 3.2.1.17) and trypsin (EC 3.4.21.4) were required for efficient crude membrane separation. Primary dehydrogenases and NADH oxidase were used as cytoplasmic membrane markers, and 2-keto-3-deoxyoctulosonic acid was used to identify the outer membranes. Cellulose synthetase (UDP-glucose:1,4-beta-D-glucan 4-beta-D-glucosyltransferase; EC 2.4.1.12) activity was assayed as the conversion of radioactivity from UDP-[(14)C]glucose into an alkali-insoluble beta-1,4-D-[(14)C]glucan. This activity was predominantly found in the cytoplasmic membrane. The cellulose nature of the product was demonstrated by (i) enzymatic hydrolysis followed by TLC, (ii) methylation analysis followed by TLC, and (iii) GC/MS. Further, the weight-average and number-average degree of polymerization of the in vitro product, determined by high-performance gel permeation chromatography, were 4820 and 5270, respectively. In addition, x-ray diffraction analysis indicated that the in vitro product is cellulose II, which is in contrast to the in vivo product-namely, cellulose I.

Journal Article↗
PubMed1990

Glucose phosphorylation rate in rat parietal cortex during normoglycemia, hypoglycemia, acute hyperglycemia, and in diabetes-prone rats.

Cerebral metabolic rate for glucose (CMRglc) was studied in rats using [6-14C]glucose. After intravenous injection, the radioactivity of the parietal cortex was corrected for loss of labeled CO2 and divided by the integral of the arterial plasma glucose concentration, determined during tracer circulation. Treatment with insulin, resulting in plasma glucose concentrations less than 2.6 mmol/l, reduced CMRglc to 64% of the values found in control animals. CMRglc did not change in animals with acute hyperglycemia produced by intraperitoneal injection of a glucose solution or in diabetes-prone rats with or without insulin treatment.

Animals↗
PubMed1994

Dual effects of forskolin on glucose utilization in cultured fibroblasts, as observed with the use of glucose analogs.

It is well known that forskolin suppresses glucose transport in cell membranes. In the present study, however, we indicated a different effect of forskolin on the uptake of radioactive 2-deoxy-D-glucose (2-DG) by cultured fibroblasts between the values measured in the presence of unlabeled 2-DG and those measured in the presence of unlabeled glucose. In the former case, the uptake was inhibited by forskolin. On the contrary, [3H] 2-DG uptake in the presence of unlabeled glucose was increased by forskolin. These results suggest that the metabolic difference between the two sugars is involved in the above-mentioned difference in the effect of forskolin. This paper presents that forskolin has stimulatory effect on glycolysis in addition to an inhibitory effect on glucose transporter. The findings seem to be of another interest to indicate the relationship between membrane transport and subsequent intracellular metabolism of glucose.

Cell Line↗
PubMed1977

Comparison of the effect of glucose and fructose on the recovery of the heart preparation.

Reactions of the cardiac muscle of the rat in vitro were investigated in the present study. Cardiac muscle was perfused by Langendorf's method; perfusion pressure was 80 cm H2O and the temperature of the perfusion solution 37 degrees C. The perfusion solution was aerated with a gas mixture of oxygen (95%) and carbon dioxide (5%). Potassium citrate solution was used for heart arrest, and heart function was recovered by infusion of Locke's solution, plus glucose, fructose or sucrose. During recovery the amplitude and frequenty of heart beats, the lactic acid in the drained perfusion solution, pH and potassium concentration were measured. The use of glucose, fructose or sucrose made no significant difference to any of these parameters. Next, the metabolism of glucose and fructose in the heart was investigated by means of D(U-14C)-glucose nad D(U-14C)-fructose. Radioactive lactic acid was detected in the drained perfusion solution with D(U-14C)-glucose, but not when D(U-14C)-fructose was used. The radioactivity incorporated into glycogen by the heart was also larger with D(U-14C)-glucose than with D(U-14C)-fructose. On a metabolic basis the use of glucose for resuscitation would seem to be more appropriate than fructose.

Animals↗
PubMed1965

Correlation of Carbohydrate Catabolism and Synthesis of Macromolecules During Enzyme Synthesis in Pseudomonas fluorescens.

Kirkland, Jerry J. (Oklahoma State University, Stillwater), and Norman N. Durham. Correlation of carbohydrate catabolism and synthesis of macromolecules during enzyme synthesis in Pseudomonas fluorescens. J. Bacteriol. 90: 23-28. 1965.-Glucose, ribose, and fructose shorten the lag period required for synthesis of protocatechuate oxygenase. Radioactivity from uracil-2-C(14) is incorporated into the hot trichloroacetic acid-soluble fraction after a lag period of approximately 20 min after addition of protocatechuic acid. Addition of glucose or ribose simultaneously with the inducer shortens the lag period to approximately 5 min and increases the rate of uracil incorporation. The inducer must be present to initiate incorporation of radioactivity, and the exogenous carbon source accelerates incorporation but is not sufficient to initiate synthesis by itself. The addition of protocatechuic acid increases the rate and total incorporation of radioactivity from uniformly labeled glucose or ribose-1-C(14) into the hot trichloroacetic acid-soluble fraction. Ribose decreases the incorporation of radioactivity from uniformly labeled glucose into the hot trichloroacetic acid-soluble fraction, and glucose shows a similar effect on incorporation of radioactivity from ribose-1-C(14), indicating the two sugars are serving in the same capacity to enhance enzyme synthesis. Radioactivity from glucose-1-C(14) is not incorporated into the hot trichloroacetic acid-soluble fraction. The results suggest that glucose and ribose shorten the lag period for inducible enzyme formation by serving as a "specific" carbon source for synthesis of macromolecules such as ribonucleic acid.

Journal Article↗
PubMed1994

The metabolism of 2-fluoro-2-deoxy-D-glucose in human chondrocytes and its incorporation into keratan sulfate proteoglycans.

The incorporation of 2-fluoro-2-deoxy-D-[14C]glucose in proteoglycans was investigated in a cell culture system, where human articular chondrocytes were cultured in high-cell-density thin-layer soft agarose. The proteoglycans were solubilized from the culture medium and the cell layer fraction by extracting with a guanidine hydrochloride buffer and purified by an ion-exchange-chromatography (DEAE-Sepharose CL-6B). With enzymic decomposition experiments concerning the glycosaminoglycan side-chains it could be shown that 65-69% were digestible by keratanase, whereas 21-29% of the 14C-labeled proteoglycans were digested with chondroitinase AC/ABC. The main constituent of the 2-fluoro-2-deoxy-D-[14C]glucose-metabolites present in the glycosaminoglycan side chains of the proteoglycans was 2-fluoro-2-deoxy-D-[14C]galactose. Therefore, 2-fluoro-2-deoxy-D-glucose was preferentially incorporated into keratan sulfate. We investigated the effect of non-radioactive 2-fluoro-2-deoxy-D-glucose on UDP-sugar and proteoglycan biosynthesis after incubation periods of 1-30 h. A high 2-fluoro-2-deoxy-D-glucose concentration in the culture medium did not influence the pool size of UDP-N-acetylhexosamines, but UDP-D-glucose, UDP-D-galactose, UDP-D-glucuronic acid, UDP-2-fluoro-2-deoxy-D-glucose, UDP-2-fluoro-2-deoxy-D-galactose and UDP-2-fluoro-2-deoxy-D-glucuronic acid accumulated in the chondrocytes time dependently. In a pulse/chase experiment the retarded synthesis of fluorinated UDP-sugars was proved. The half-lives (t1/2) for UDP-2-fluoro-2-deoxy-D-glucose and UDP-2-fluoro-2-deoxy-D-galactose were about 7.7 h and 13.3 h, respectively. UDP-2-fluoro-2-deoxy-D-glucuronic acid could be found with delay. The incubation with 2-fluoro-2-deoxy-D-glucose and [14C]glucosamine resulted in a decreased radioactive labelling of chondroitin sulfate and keratan sulfate.

Cartilage, Articular↗
PubMed1979

Interference with glycosylation of glycoproteins. Inhibition of formation of lipid-linked oligosaccharides in vivo.

Influenza-virus-infected cells were labelled with radioactive sugars and extracted to give fractions containing lipid-linked oligosaccharides and glycoproteins. The oligosaccharides linked to lipid were of the 'high-mannose' type and contained glucose. In the glycoprotein fraction, radioactivity was associated with virus proteins and found to occur predominantly in the 'high-mannose' type of glycopeptides. In the presence of the inhibitors 2-deoxy-D-glucose, 2-deoxy-2-amino-D-glucose (glucosamine), 2-deoxy-2-fluoro-D-glucose and 2-deoxy-2-fluoro-D-mannose incorporation of radiolabelled sugars into lipid- and protein-linked oligosaccharides was decreased. Kinetic analysis showed that the inhibitors affected first the assembly of lipid-linked oligosaccharides and then protein glycosylation after a lag period. During inhibition by deoxyglucose and the fluoro sugars lipid-linked oligosaccharides were formed that contained oligosaccharides of decreased molecular weight. No such aberrant forms were found during inhibition by glucosamine. In the case of inhibition by deoxyglucose it was shown that the aberrant oligosaccharides were not transferred to protein. Inhibition of formation of lipid-linked oligosaccharides by deoxyglucose and fluoro sugars was antagonized by mannose, in which case oligosaccharides of normal molecular weight were formed. The inhibition by glucosamine was reversed by its removal from the medium. The reversible effects of these inhibitors exemplify their usefulness as tools in the study of glycosylation processes.

Animals↗
PubMed1978

The realiability of rates of glucose appearance in vivo calculated from constant tracer infusions.

The rate of appearance of unlabelled glucose was calculated from tracer data and compared with the actual rate of infusion of unlabelled glucose into a anaesthetized dog with all sources of endogenous glucose production surgically removed. The mean steady-state rate of appearance of unlabelled glucose calculated from the equilibrium specific radioactivity was insignificantly higher (0.3%) than the actual rate of infusion of unlabelled glucose (n = 6). During non-steady states, a time-variable volume of distribution of glucose (V) was necessary to predict the rate of appearance of unlabelled glucose correctly from the pool-dependent equation described by Steele [(1959) Ann. N.Y. Acad. Sci. 82, 420--430]. Rapid fluctuations in the rate of appearance of glucose could be predicted reasonably well by using a fixed value of V for 40ml/kg, but by using larger fixed values for V (100--160ml/kg) the rates were inaccurate. The pool-dependent two-radiactive-isotope technique described by Issekutz, Issekutz & Elahi [(1974) Can. J. Physiol. Pharmacol. 52, 215--224] predicted single-step increases in the rate of infusion of glucose reasonably accurately, but the Steele (1959) equation was better at predicting sequential changes in the rate of infusion of unlabelled glucose.

Animals↗
PubMed1970

Structure-function relationships in the adipose cell. II. Pinocytosis and factors influencing its activity in the isolated adipose cell.

Pinocytic activity in the adipose cell has been examined by measuring the uptake of colloidal gold. Pinocytic activity occurs in the isolated adipose cell under all experimental conditions; a portion of the vesicular elements of the cell can be identified by electron microscopy as pinocytic in origin. The isolated adipose cell appears to take up serum albumin by pinocytosis. Pinocytic activity in the isolated adipose cell is enhanced by epinephrine, but not by insulin. The relationship between pinocytosis and the metabolic activity of the adipose cell has been studied by measuring simultaneously the uptake of radioactive colloidal gold, the incorporation of (14)C-counts from U-glucose-(14)C into CO(2), total lipid, triglyceride glycerol and triglyceride fatty acids, and the release of nonesterified fatty acids in the absence of hormones and in the presence of insulin or epinephrine. Correlations between hormone-produced alterations in lipid metabolism and in pinocytic activity suggest that intracellular nonesterified fatty acid levels are a factor in the regulation of both the cell's pinocytic activity and its metabolism and that pinocytosis in the adipose cell functions in the extracellular-intracellular transport of nonesterified fatty acids.

Adipose Tissue↗
PubMed1976

Incorporation of [14C]glucose from UDP[14C]glucose into a phosphoglycolipid by cell-free particulate systems of a moderately halophilic gram-negative bacterium, Pseudomonas halosaccharolytica ATCC 29423.

A glucosyl group from uridine diphosphate [U-14C]glucose is incorporated into a phosphoglycolipid, probably a glucosylphosphatidylglycerol, by a disrupted membrane enzyme preparation from a gram-negative, moderately halophilic bacterium, Pseudomonas halosaccharolytica ATCC 29423. The conversion of [14C]phosphatidylglycerol into phosphoglycolipid by the particulate preparation was also enhanced in the presence of non-labelled UDP-glucose. A chemical degradation study of labelled phosphoglycolipid showed the bulk of the radioactivity from UDP[U-14C]glucose to be associated with the glucose moiety, which also appeared to be attached to the hydroxyl group of a second glycerol.

Acetates↗
PubMed1969

Lipid synthesis by isolated Chlamydia psittaci.

The isolated cells of the host-dependent meningopneumonitis agent, Chlamydia psittaci, were shown to incorporate radioactive carbon from aspartate, isoleucine, and glucose-6-phosphate into cell lipids. The nature of this incorporation was investigated. Radioactivity was found only in the fatty acids and primarily in the phosphatidyl ethanolamine, and, to a lesser extent, in the phosphatidyl choline fractions. Branched-chain fatty acids, not found in host lipid, were shown to constitute a large proportion of the fatty acid content of phosphatidyl ethanolamine. The reasons why only fatty acid synthesis took place under the conditions of our experiments with isolated meningopneumonitis agent cells remain obscure.

Aspartic Acid↗
PubMed1998

1-[Carbon-11]-glucose radiation dosimetry and distribution in human imaging studies.

UNLABELLED: 1-[Carbon-11]-D-glucose ([11C]-glucose) is an important imaging agent for PET studies that have been used to study the normal brain, encephalitis, epilepsy, manic-depressive disorder, schizophrenia and brain tumors. METHODS: Dosimetry estimates were calculated in subjects undergoing imaging studies to help define the radiation risk of [11C]-glucose PET imaging. Time-dependent radioactivity concentrations in normal tissues in 33 subjects after intravenous injection of [11C]-glucose were obtained by PET imaging. Radiation absorbed doses were calculated according to the procedures of the Medical Internal Radiation Dose (MIRD) committee along with the variation in dose based on the calculated standard deviation of activity distribution seen in the individual patients. RESULTS: Total body exposure was a median of 3.0 microGy/MBq in men and 3.8 microGy/MBq in women. The effective dose equivalent was 3.8 microGy/ MBq in men and 4.8 microGy/MBq in women. The critical organs were those that typically take up the most glucose (brain, heart wall and liver). CONCLUSION: The organ doses reported here are small and comparable to those associated with other commonly performed nuclear medicine tests and indicate that potential radiation risks associated with this radiotracer are within generally accepted limits.

Carbon Radioisotopes↗
PubMed1996

No effect of beta-adrenergic blockade on hypoglycaemic effect of glucagon-like peptide-1 (GLP-1) in normal subjects.

GLP-1 administration decreases blood glucose levels in normal subjects and non-insulin-dependent diabetes mellitus patients and is therefore proposed as a treatment for diabetic hyperglycaemia. The glucose lowering effect of GLP-1 is glucose dependent and therefore self-limiting, but it is not known to which extent counterregulatory mechanisms participate in this. GLP-1 was infused i.v. into 8 healthy subjects after an overnight fast at a rate of 100 pmol kg-1 h-1 for 1 h with and without beta-adrenoceptor blockade (i.v. bolus of 5 mg propranolol followed by a continuous infusion of 0.08 mg min-1). In a control experiment, saline and propranolol were infused. Hepatic glucose production was measured and blood was analysed for plasma glucose, insulin, glucagon, catecholamines, and radioactivity. Plasma GLP-1 levels were similar on the two GLP-1 infusion days and resulted in: (1) a significant decrease in plasma glucose from 5.2 +/- 0.2 to 4.1 +/- 0.1 mmol l-1 with GLP-1/propranolol infusion, and from 5.2 +/- 0.1 to 4.0 +/- 0.1 mmol l-1 with GLP-1/saline infusion (NS); (2) a corresponding significant increase in plasma insulin from 58.0 +/- 6.3 to 144.5 +/- 22.3 pmol l-1 and from 61.7 +/- 6.4 to 148.2 +/- 34.0 pmol l-1, respectively (NS); (3) a significant decrease in plasma glucagon from 11.7 +/- 1.6 to 6.5 +/- 1.5 pmol l-1 and from 10.4 +/- 1.6 to 4.6 +/- 1.0 pmol l-1, respectively; (4) a significant decrease in the rate of glucose appearance which was not significantly different on the two GLP-1 infusion days; and (5) an increase in catecholamine levels in the GLP-1/saline experiment and also in the beta-blockade experiments. We conclude that adrenergic counterregulation plays an insignificant role in curtailing GLP-1's glucose lowering effect.

Adrenergic beta-Antagonists↗
PubMed2001

Glycogen accumulation in rat pancreatic islets: in vitro experiments.

Under conditions of sustained hyperglycemia, glycogen accumulates in pancreatic islets, but not so in acinar pancreatic cells. Advantage conceivably could be taken from such a situation in the perspective of the noninvasive imaging of the endocrine pancreas. The present experiments aim, therefore, at characterizing the time course for glycogen accumulation in pancreatic islets cultured at a high concentration (30 mM) of D-glucose in the presence of tracer amounts of either D-[U-14C]glucose or 2-deoxy-2-[18F]fluoro-D-glucose. The 14C-labeled glycogen content of the cultured islets increased with time (150 min to 72 h), exceeded that found in acinar tumoral cells, and did not decrease over 60 min of incubation at 30 mM D-glucose in the absence of D-[U-14C]glucose. Glycogenolysis was observed, however, when the concentration of D-glucose was decreased to 2.8 mM and, in such a case, was further enhanced by forskolin and theophylline. Such a glycogenolysis coincided with the generation of 14CO2 from radioactive intracellular precursors and alteration of the B-cell secretory response to D-glucose. The radioactive glycogen content was higher in islets exposed to 2-deoxy-2-[18F]fluoro-D-glucose than D-[U-14C]glucose. Prior exposure of the islets to streptozotocin suppressed the accumulation of glycogen during their subsequent culture at high D-glucose concentration. These findings may help to define the experimental conditions optimal for the labeling and accumulation of islet glycogen in vivo.

Amino Acids↗
PubMed1993

Incorporation of carbon atoms from glucose into the food mutagens MeIQx and 4,8-DiMeIQx using 14C-labelled glucose in a model system.

Mixtures of creatinine, glucose and threonine with the addition of a small amount, 250 microCi, of [U-14C]glucose, [1-14C]glucose or [6-14C]glucose were heated at 180 degrees C for 30 min in an aqueous model system. The mixtures were purified and analysed using HPLC, scintillation and Ames tests. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx) were detected as the main radioactive mutagens. The amount of MeIQx and 4,8-DiMeIQx produced from threonine was estimated at 18 and 60 nmol/mmol glucose respectively. Radioactive carbon atoms originating from glucose were also shown to be incorporated into 2-amino-3-methylimidazo[4,5-f]quinoxaline (IQx). The specific activity was calculated to be 0.6, 0.3 and 0.1-0.3 mCi/mmol for MeIQx, 4,8-DiMeIQx and IQx respectively for all three labelled forms of glucose. By the incorporation of carbon atoms originating from glucose into the imidazoquinoxaline mutagens it was clearly demonstrated that glucose is a precursor in the formation of these food mutagens.

Carbon↗
PubMedDate not supplied

In the rat, intestinal lymph carries a significant amount of ingested glucose into the bloodstream.

Intestinal lymph flow in rats receiving an oral load of 3 mmoles of glucose was determined by measuring the amount of tritiated gavage water entering via the portal route [computed differential arterio-venous tritium water concentrations multiplied by portal blood flow) and measuring the total amount of tritium transferred from the intestinal lumen to the rest of the rat in a given time [from the blood tritium specific activity and the water space (795 ml.kg-1) of the rat]. The approximate figure obtained (79.8 ml.kg-1.h) was used for the evaluation of the amount of glucose (from 14C-labelled glucose in the gavage) transfer via intestinal lymph from the label present in the lymph and its flow. Lymph glucose concentration (c. 11 mM) and specific radioactivity were higher than those of blood. The amount of glucose actually taken up from the intestinal lumen was determined measuring the remaining label in the alimentary canal. The portal contribution to label distribution was measured as for tritium water transfer. Most glucose label passed through in the form of glucose, with much smaller proportions as CO2 and even smaller as lactate and other labelled compounds. The results suggest that the contribution of lymph circulation to dietary glucose incorporation into the bloodstream may be significant, amounting to values higher than 10% of the glucose actually incorporated.

Animals↗
PubMed1986

Biochemical and functional heterogeneity of rat adipocyte glucose transporters.

We have studied the biochemical mechanism of insulin action on glucose transport in the rat adipocyte. Plasma membranes and low-density microsomes were prepared by differential ultracentrifugation of basal and insulin-stimulated cells. The photochemical cross-linking agent hydroxysuccinimidyl-4-azidobenzoate was used to covalently bind [3H]cytochalasin B to the glucose transporter which migrated as a 45-50-kDa protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing of the eluted 40-55-kDa proteins revealed two peaks of D-glucose-inhibitable [3H]cytochalasin B radioactivity focusing at pH 6.4 and 5.6 when low-density microsomes were used as the starting material. In contrast, only one D-glucose inhibitable peak, focusing at pH 5.6, was found in plasma membranes. Pretreatment of the cells with insulin led to a marked redistribution of the pH 5.6 form of the glucose transporter from low-density microsomes to plasma membranes with no effect on the pH 6.4 form of the glucose transporter. Following isolation from the isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gels, both glucose transporter isoforms were shown to cross-react with an antiserum raised against the purified human erythrocyte glucose transporter. Following incubation of [3H]cytochalasin B-labeled low-density microsomal and plasma membranes with neuraminidase, the pH 5.6 transporter isoform was shifted on isoelectric focusing to a more basic pH, while the pH 6.4 isoform was not affected. These data demonstrate that: there is a heterogeneity of glucose transporter species in the intracellular pool while the plasma membrane transporters are more uniform in structure. The pH 5.6 glucose transporter isoform is translocated by insulin from the low-density microsomes to the plasma membrane but the pH 6.4 isoform is not sensitive to insulin. Differential sensitivity of the glucose transporter isoforms to neuraminidase suggests that the heterogeneity is at least partially due to differences in glycosylation state.

Adipose Tissue↗