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 145 records · Page 8Linked to original sources

PubMed1975

Effect of halofenate and clofibrate on lipid synthesis in rat adipocytes.

The free acids of the plasma lipid-lowering agents, halofenate and clofibrate inhibited the incorporation of radioactive glucose and pyruvate into fatty acids of isolated adipocytes prepared from rat epididymal fat pads. The concentration which inhibited fatty acid synthesis was dependent on the bovine serum albumin concentration in the incubation. The 50 per cent inhibitory concentration of the free acid of halofenate in 1 per cent, 2 percent and 4 per cent albumin was 0.9 mM, 2.3 MM and 4.4 mM, respectively. The potency of clofibrate was also lowered by increasing the albumin concentration. These compounds inhibited the uptake of both [14C]glucose and [14C]pyruvate to the same degree as the incorporation of these substrates into fatty acids. However, the drugs either had no effect on , or stimulated the uptake of palmitate by the cells. Leucine accumulation by the adipocytes was unaffected by halofenate (free acid) and inhibited by clofibrate (free acid). A comparison of these agents with (minus)-hydroxycitrate, kynurenate and cerulenin (inhibitors of ATP-citrate lyase, acetyl CoA carboxylase and fatty acid synthetase, respectively) on the oxidation of pyruvate suggested that they inhibited pyruvate metabolism at or near the enzyme, pyruvate dehydrogenase.

Adipose Tissue↗

PubMed1994

Differing patterns of carbohydrate metabolism in liver and muscle.

The effect of a period of starvation followed by refeeding on skeletal muscle glycogen was investigated by the use of double-labelled radioactive glucose precursors in rats. Skeletal muscle glycogen, which is not depleted to anything like the extent of liver glycogen, shows a remarkable stability with respect to its overall molecular size distribution during starvation and subsequent refeeding. The experiments also indicate that there is a control mechanism in muscle tissue enabling the synthesis of lysosomal glycogen to be switched off during the initial part of the refeeding process. The results emphasise the inadequacy of the Cori cycle and a modified version is proposed.

Animals↗

PubMed1975

The sialic acid and carbohydrate content and the synthesis of glycoprotein from radioactive precursors by tissues of the normal and diseases upper intestinal tract.

The sialic acid and total hexose content of perorally obtained mucosal biopsies have been determined. Gastric mucosa has a higher content of sialic acid/mg protein and a lower content of total hexoses/mg protein than does jejunal mucosa. There were no differences chemically between gastric biopsies from subjects with or without peptic ulcers. Neither were there any differences between normal jejunal mucosa and jejunal mucosa from patients with untreated or treated coeliac disease. The studies of the incorporation of radioactive glucose into glycoprotein using all these tissues indicate that bacteria make a major in vitro contribution. This method is not suitable for study of de novo synthesis in either gastric or jejunal mucosa. Results are presented which suggest that bacteria may normally be present within the mucous layer of the stomach.

Adult↗

PubMed1986

Changes of the main isoform of human apolipoprotein A-I following incubation of plasma.

This study was aimed to ascertain whether the more acidic isoforms of plasma apo A-I (A-I-1 and A-I-2) could originate in vitro from the main plasma isoform (A-I0). Apo A-I isoforms were separated by two-dimensional gel electrophoresis before and after a prolonged incubation of serum or EDTA-plasma at 37 degrees C. Incubated plasma there was a marked decrease of apo A-I0 and a concomitant linear increase of apo A-I-1 + and A-I-2. The relative content of the latter raised from 22 +/- 7% before the incubation to 60 +/- 7% after 48 h of incubation. This conversion of A-I0 was not inhibited by either pre-heating of plasma at 60 degrees C for 1 h or the addition of protease inhibitors, EDTA and p-chloromercuriphenylsulfonic acid. The conversion of apo A-I0 was not observed in isolated HDL, incubated either in the absence or in the presence of d less than 1.063 g/ml lipoproteins and lipoprotein deficient plasma, nor in plasma which had been dialyzed before being incubated at 37 degrees C. This suggests that plasma contains a low molecular weight factor capable of promoting the conversion of A-I0. The increase of the relative content of apo A-I-1 and apo A-I-2 in incubated plasma was not due to glucosylation or carbamylation of A-I0 as no radioactive glucose and urea were found to be bound to A-I. Since the conversion of apo A-I0 was prevented by the addition of an antioxidant (butylated hydroxytoluene, BHT) to the incubated plasma it is conceivable that some product of lipid peroxidation renders apo A-I0 more electronegative by reacting with some free amino groups of this peptide.

Adult↗

PubMed1976

Antibacterial activity of 15-azasteroids alone and in combination with antibiotics.

A new class of 15-azasteroid analogues has been synthesized and tested for antimicrobial activity. The compounds 1, 10, 11, 11a-tetrahydro-7-methoxy-11a-methyl-2H-naphth (1,2-g) indol (methoxyimine) and 1,10,11,11a-tetrahydro-11a-methyl-2H-naphth (1,2-g) indol-7-ol (hydroxyimine) inhibit the growth of Bacillus subtillis and Escherichia coli at concentrations as low as 10-5 M. Addition of either compound to the growth medium casued a rapid inhibition in the transport of radioactive glucose, uracil and several amino acids. The inhibition of growth and substrate transport was reversed following removl of the steroid from the medium. The evidence is consistent with a site of steroid action at the cell periphery. Combining the methoxyimine with polyor circulin at subinhibitory concentrations produced greatly enhanced antimicrobial activity against Pseudomonas fluorescens. Similar action was observed against B. subtilis when the azasteroid was combined with vancomycin or chloramphenicol. The inhibitory action of other antibiotics such as penicillin or erythromycin was not affected by addition of the test compound. The results suggest formation of a molecular complex between the azasteroid and antibiotic which is responsible for the enhanced biological activity.

Aminoisobutyric Acids↗

PubMed1983

A simplified method for the estimation of individual amino acid radioactivity in plasma samples.

A method is presented for the quantitative estimation of the individual amino acid radioactivity in biological samples. The material is deproteinized with cold acetone, and, after acetone evaporation, is passed through a column containing 1 g of Amberlite XAD-2, then eluted with 10% ethanol. The samples are derivatized with Sanger's reagent (alkaline 1-fluoro-2,4-dinitrobenzene) and passed again through the Amberlite XAD-2 column; the 10% ethanol eluate is now discarded and the DNP-amino acids eluted with acetone. Aliquots are used for TLC chromatography on Silicagel plates; the spots are identified, cut away and their radioactivity estimated. The actual recovery of radioactivity in the spots is about 86-92% of the initial radioactivity. No contamination with radioactive glucose, lactate, pyruvate or glycerol has been observed.

Amino Acids↗

PubMed1983

A stomach hormone that inhibits food intake.

To determine whether extrinsic nerves of the stomach play a role in the short-term inhibition of food intake, 4 inbred Lewis rats received a supernumerary transplant of the stomach, duodenum, proximal jejunum and pancreas. When 4 or 8 cc of liquid diet was infused into the transplanted stomach, the rats showed a compensatory reduction of food intake whether food was allowed to empty into the intestines or whether it was retained in the stomach by a pyloric clamp. Since absorption of nutrients from the stomach is small, these results suggest that a hormone released by the stomach into the general circulation inhibits food intake. The transplanted upper digestive tract showed normal absorption of radioactive glucose from a mixed meal. A sensitive conditioned aversion test repeated 6 times did not reveal any aversion to the infusion of food into the transplanted stomach. Thus, the transplant appeared to function normally and did not cause discomfort to the rat. The release of the stomach hormone depends upon both distension of the stomach wall and chemical stimulation of the gastric mucosa. Two separate models for release of the hormone are proposed.

Absorption↗

PubMed2006

[FDG PET and its impact on patient's management in oncology].

FDG, a radioactive glucose analog for PET imaging, requires some precautions: it should be used only in patients with glycemia < 7mmol/L, fasting for at least 6 h but well hydrated, and after pregnancy is ruled out. FDG-PET has many indications in oncology. Its clinical utility has been documented in some circumstances, listed as routine indications in the European Principal Characteristics Summary and the French Standards, Options, and Recommendations. The European "Points to Consider" define as a principal criterion of clinical utility the impact of the imaging results on patient management. The original results presented here evaluate the clinical impact of FDG-PET among patients at Tenon Hospital by the rate of modifications in patient' management, determined with the same questionnaire as that used in two California studies of 2044 patients. Our response rate was lower than in our previous retrospective study in 2000 (34% versus 73%), probably because a prospective evaluation requires more work by the referring physician (who had to respond to two separate letters). On the other hand, the modification rate rose significantly (54% versus 46%, p<0.001), especially for colorectal cancer (58% versus 44%, p<0.02). The California studies had similar response rates (31%-48%, depending on the indication). Their modification rates were also similar, although higher for lymphoma (68%), colorectal (65%) and breast (58%) cancers.

Decision Making↗

PubMed1993

Hypoglycaemia: principles of diagnosis and treatment in children.

The diagnostic approach to children with suspected hypoglycaemia is facilitated by the fact that two clinically distinct groups exist with little overlap: 1. Hypoglycaemias characterized by a fuel deficit only. 2. Hypoglycaemias in which the fuel deficit is overshadowed by symptoms of intoxication. This differentiation is used when taking the medical history, performing the physical examination, and planning the laboratory investigations. The latter may encompass tolerance tests, a fasting test or the use of a non-radioactive glucose isotope. Protocols for such tests are given.

Child↗

PubMed2001

Characterization of adenosine A1 receptor in cultured myoblast C2C12 cells of mice.

In an attempt to investigate the presence of adenosine A1 receptor in cell line, we used N6-cyclopentyladenosine (CPA), an agonist of adenosine A1 receptor, to incubate with C2C12 cells in vitro. CPA increased the uptake of radioactive glucose into C2C12 cells in a concentration-dependent manner and this action was abolished by the antagonists, both 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) (1,3-dipropy1-8-cyclopentylxanthine) and 8-(p-sulfophenyl)theophylline (8-SPT), at concentrations sufficient to block adenosine A1 receptor. Northern blot analysis showed the expression of adenosine A1 receptor mRNA by C2C12 cells. Western blotting also indicated a positive correlation (r = 0.99) of antibody recognized adenosine A1 receptor with membrane protein. The presence of adenosine A1 receptor in C2C12 cells can thus be considered. In the presence of U73312 (1-[6[[(17 beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-1H- pyrrole-2,5-dione), the specific inhibitor of phospholipase C, glucose uptake stimulated by CPA into C2C12 cells was reduced concentration-dependently while it was not modified by U73343 (1-[6[[(17 beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino]hexyl]-2,5- pyrrolidinedione), the negative control of U73312. Moreover, chelerythrine and GF 109203X (3-[1-[3-(dimethylamino)propyl]-1H-indol-3-yl]-4-(1H-indol-3- yl)-1H-pyrrole-2,5-dione) also diminished the CPA-stimulated glucose uptake at concentrations sufficient to inhibit protein kinase C. The obtained data suggest that activation of adenosine A1 receptor in C2C12 cells may increase the glucose uptake via phospholipase C-protein kinase C pathway.

Adenosine↗

PubMed1972

Effects of carbohydrate availability on lipogenesis in sheep.

1. Lipogenesis in sheep liver and adipose tissue was investigated by incorporation studies in vitro with radioactive glucose and acetate and by assays of key enzymes. 2. Carbohydrate availability to sheep was increased by feeding on a diet containing 70% soluble carbohydrate, by infusing glucose into the abomasum or by direct intravenous infusion of glucose. 3. Under these conditions lipogenesis from glucose and acetate was increased from very low values in lìver and adipose tissue, especially in those animals where rumen fermentation was by-passed by glucose infusion. 4. Large increases in the activities of ATP citrate lyase (EC 4.1.3.8) and NADP-malate dehydrogenase (EC 1.1.1.40) occurred in both tissues when lipogenesis was increased. 5. No adaptations were found in the activities of pyruvate carboxylase (EC 6.4.1.1) in adipose tissue, glucokinase (EC 2.7.1.2) in liver or 3-hydroxybutyrate dehydrogenase (EC 1.1.1.30) in liver. It is proposed that the absence of these enzymes is not related to glucose availability. 6. The effect of glucose on liver lipogenesis was to increase conversion of acetate into lipid. 7. This effect also occurred in adipose tissue, but in this tissue glucose also became a quantitatively important precursor of triglyceride fatty acid.

Abomasum↗

PubMed1983

Disturbance of lysosomal glycogen metabolism by liposomal anti-alpha-glucosidase and some anti-inflammatory drugs.

The size-distribution of liver glycogen was shown to be distinctly affected by the anti-inflammatory drugs salicylate and indomethacin. By measurement of the incorporation of radioactive glucose into glycogen, salicylate was shown to have a depressing effect on overall liver glycogen metabolism. These effects appear to arise from the stabilizing of the lysosome by the drugs. The incorporation, via liposomes, of purified anti-1,4-alpha-glucosidase activity and in the content of high-molecular-weight glycogen. These changes are increased by prolonged liposomal antibody treatment and suggest that a possible feedback control mechanism operates in the incorporation of glycogen into lysosomes. These experiments may be useful as a model of glycogen turnover and its failure in glycogenosis type II (Pompe's disease).

Acarbose↗

PubMed1998

Role of acetyl-L-carnitine in rat brain lipogenesis: implications for polyunsaturated fatty acid biosynthesis.

This study was undertaken to explore the metabolic fate of acetyl-L-carnitine in rat brain. To measure the flux of carbon atoms into anabolic processes occurring at regional levels, we have injected [1-(14)C]acetyl-L-carnitine into the lateral brain ventricle of conscious rats. After injection of [1-(14)C]acetyl-L-carnitine, the majority of radioactivity was recovered as 14CO2 expired (60% of that injected). The percentage of radioactivity recovered in brain was 1.95, 1.60, 1.30, and 0.93% at 1, 3, 6, and 22 h, respectively. Radioactivity distribution in various lipid components indicated that the fatty acid moiety of phospholipid contained the majority of radioactivity. The radioactive profile of these fatty acids showed that the acetyl moiety of acetyl-L-carnitine was incorporated into saturated (60%), monounsaturated (15%), and polyunsaturated (25%) fatty acids [mainly present in 20:4 (5.2%) and 22:6 (7.8%)]. Injection in the brain ventricle of radioactive glucose, the major source of acetyl-CoA in the CNS, revealed that glucose was a precursor of saturated (85%) and monounsaturated (15%) but not of polyunsaturated fatty acids. Thus, this study demonstrated distinct fates of glucose and acetyl-L-carnitine following intracerebroventricular injection. In summary, these data implicate acetyl-L-carnitine as an important member of a complex acetate trafficking system in brain lipid metabolism.

Acetylcarnitine↗

PubMed1976

The carbon pathway for lipogenesis in isolated adipocytes from rat, guinea pig, and human adipose tissue.

The synthesis of fatty acids from a variety of labeled substrates by isolated adipocytes of the rat, guinea pig, and human was investigated. The incorporation of radioactive glucose and pyruvate into triglyceride fatty acids was considerably lower in human than either rat or guinea pig adipose tissue. By contrast, the incorporation of palmitate into adipose tissue triglycerides was approximately the same in all three species. End carbon analysis of fatty acids isolated from adipocytes incubated with pyruvate-U-14C indicated that although the synthesis of fatty acids in human adipose tissue was extremely low compared to that of the rat and guinea pig, it represented de novo biosynthesis rather than chain elongation of existing fatty acids. It is suggested that in the human, fatty acids are synthetised de novo primarily in the liver. In adipose tissue, lipogenesis consists essentially of the esterification of fatty acids, obtained from plasma, into triglycerides.

Adipose Tissue↗

PubMed1987

Cephalic reflexes: their role in digestion and possible roles in absorption and metabolism.

Stimulation of the oral cavity immediately elicits salivation, gastric acid secretion and pancreatic exocrine and endocrine secretions that serve to prepare the alimentary canal for digestion, transport and utilization of ingested nutrients. Oropharyngeal-stimulated responses are reliably initiated by the taste and smell of food. These gastrointestinal reflexes, often referred to as anticipatory or cephalic phase responses, are mediated by the autonomic nervous system and are believed to be independent of the postabsorptive effects of ingested nutrients. A common pathway used by cephalic phase responses to trigger gastrointestinal secretions is the vagus. Several studies have also demonstrated that cephalic stimulation activates both the sympathetic and parasympathetic nervous systems and thus, many cephalic-metabolic reflexes may arise indirectly from more general physiological changes that accompany oropharyngeal stimulation. The present studies suggest that oral stimulation results in alterations in intestinal function. Specifically, oropharyngeal stimulation of conscious, unrestrained rats with sucrose increases the uptake of radioactive glucose from the small intestine into the hepatic portal blood.

Animals↗

PubMed1985

Red cell metabolism in renal failure--the effect of dialysis.

The mechanism of the increased haemoglobin (Hb) and erythrocyte survival in continuous ambulatory peritoneal dialysis (CAPD) compared to haemodialysis (HD) was investigated by measuring hexose monophosphate shunt (HMP) activity and reduced glutathione concentration (GSH) in 12 patients--six patients who were stable on CAPD, and six patients who were stable on HD, and also six normal controls. We confirmed the rise in haemoglobin in the CAPD group. The HMP activity, measured by the liberation of 14CO2 from radioactive glucose labelled at the C1 position shows that both HD and CAPD groups fall into the normal range (normal 3-11%) although the HMP activity is higher in the HD group. The reduced glutathione concentration in the three groups was: normal controls 2.41 +/- 0.19 mmol/l; HD 3.31 +/- 0.43 mmol/l; CAPD 2.68 +/- 0.24 mmol/l. The HD group is significantly higher (P less than 0.01) than both normal and CAPD. We conclude that the rise in haemoglobin in CAPD patients is not related to a more effective HMP. This suggests other mechanisms i.e. marrow function or red-cell loss in HD may be the reason for the lower haemoglobin in this group.

Cell Count↗

PubMed1982

Effect of kainic acid, glutamate, and aspartate on CO2 production by goldfish tectal slices.

For a study of the excitatory effect of kainate, glutamate, and aspartate in the goldfish optic tectum, these substances were tested on the production of CO2 from radioactive glucose in tectal slices incubated in Krebs-Ringer medium for fish. Kainate increased the rate of CO2 production for up to 30 min in a dose-related manner, the effect being maximum at 0.1 mM concentration and decreasing at higher doses. The effect was blocked by ouabain (1 mM) as well as by the substitution of choline for Na+ in the incubation medium. Glutamate and aspartate exerted a less pronounced excitatory effect on CO2 production at higher concentration than kainate. This effect was also abolished by ouabain. Glutamate, added to the medium at a concentration at least 100-fold higher than kainate, partially reversed the increase in CO2 production induced by kainic acid. No similar effect was noticed for aspartate. The supposed glutamate antagonists glutamic acid diethylester (1 mM) and proline (5 mM) did not affect the excitatory action of kainic acid or exert an antagonistic effect towards glutamate. At higher concentration (10 mM) glutamic acid diethylester increased CO2 production, an effect that was, however, ouabain insensitive. Methyltetrahydrofolic acid (1 mM), a substance reported to compete for the kainate receptor, did not inhibit the effect of kainic acid or increase CO2 production.

Animals↗

PubMed1982

The functional significance of the pentose phosphate pathway in synaptosomes: protection against peroxidative damage by catecholamines and oxidants.

Catecholamines added in vitro in rat brain synaptosomes activate the decarboxylation of glucose radioactively labelled on carbon 1, suggesting an effective activation of the pentose phosphate pathway. Stimulation also occurred with phenazine methosulphate, reduced glutathione and hydrogen peroxide. The activation of the pentose phosphate pathway by 5-hydroxytryptamine, noradrenaline and dopamine is ascribed to the activation of monoamine oxidase, producing both the respective biogenic aldehyde and hydrogen peroxide. Evidence is presented that the further metabolism of the aldehyde by aldehyde reductase and the removal of hydrogen peroxide by glutathione peroxidase both release the limitation of NADP+ availability for the pentose phosphate pathway by leading to the oxidation of NADPH. The relevance of the maintenance of reduced NADP+ on brain is discussed in relation to the metabolism of glutathione and to lipid peroxidation.

Aldehyde Oxidoreductases↗