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 829 records · Page 46Linked to original sources
PubMed1983

Properties of freshly isolated type II alveolar epithelial cells.

The biochemical characteristics of type II alveolar epithelial cells dissociated from adult rabbit lung by instillation of low concentrations of an elastase trypsin mixture are reported. Cells studied immediately (within 4 h) after isolation were found to incorporate the radioactively labelled precursors [U-14C]glucose, [methyl-3H]choline and [3H]palmitate into cellular phosphatidylcholine at rates 2-10-fold higher than previously reported for cells not subject to short-term cell culture. Secretion of phosphatidylcholine was stimulated by beta-adrenergic agonists. Measurement of specific activities of enzymes of phospholipid biosynthesis in subcellular fractions of isolated lung cells showed a significant enrichment of acyl coenzyme A-lysophosphatidylcholine acyltransferase, an enzyme believed to be involved in pulmonary surfactant phosphatidylcholine remodeling, in the endoplasmic reticulum of type II cells. These observations support the utility of freshly isolated type II cells as a model system for the study of the functions of the alveolar epithelium.

Animals↗
PubMed1985

The short-term regulation of fatty acid synthesis in the rat epididymal adipocytes.

Lipogenesis and fatty acid synthetase (FAS) activity of isolated rat adipocytes that were treated with insulin or epinephrine were studied. Insulin stimulated incorporation of radioactivity from D-[U-14C]glucose into CO2, saponifiable and non-saponifiable fractions, whereas epinephrine promoted lipolysis and oxidation of glucose into CO2. Whereas insulin stimulated fatty acid synthesis, epinephrine had no effect. Changes in FAS specific activity of insulin- or epinephrine-treated adipocytes were insignificant and could not account for insulin-stimulated lipogenesis. Rat adipocyte FAS, unlike hepatic FAS, was not subject to short-term regulation by insulin, although fatty acid synthesis showed such a response.

Adipose Tissue↗
PubMed1981

Preparation from keratin sulfate of substrates for the measurement of 2-acetamido-2-deoxy-D-glucose 6-sulfate sulfatase and (1 goes to 3)-N-acetyl-beta-D-glucosaminidase.

An extract of bacterial cells Pseudomonas sp. IFO-13309 grown on medium containing 0.1% bovine cornea keratan sulfate of low sulfate content degraded exhaustively bovine cornea keratan sulfate to give 2-acetamido-2-deoxy-beta-D-gluco-pyranosyl 6-sulfate-(1 goes to 3)-D-galactose, isolated by gel filtration on Sephadex G-25 and purified by preparative paper chromatography. This was reduced with sodium borotritide to give 2-acetamido-2-deoxy-beta-D-glucopyranosyl 6-sulfate-(1 goes to 3)-D-[1-3H]galactitol, purified by gel filtration on Sephadex G-15, which was an excellent substrate for the measurement of 2-acetamido-2-deoxy-D-glucose 6-sulfate sulfatase. The reduced, radioactive monosulfated disaccharide was desulfated with methanolic 70mM hydrogen chloride and purified by gel filtration on Sephadex G-15 to give O-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 goes to 3)-D-[1-3H]galactitol, which allowed the measurement of (1 goes to 3)-N-acetyl-beta-D-glucosaminidase. This enzyme may participate in the normal degradation of keratan sulfate.

Acetylglucosaminidase↗
PubMed1999

A useful radiolabeling method for detection of T cell receptor glycoproteins bearing immature and mature N-linked glycans.

The antigen receptor expressed on most T lymphocytes, the T cell receptor (TCR), is a multisubunit complex containing TCR alpha,beta and CD3-gamma,delta, epsilon and zeta chains, in the form alphabetadeltaepsilongammaepsilonzetazeta. The intracellular transport of TCR proteins is routinely measured by the extent of processing of N-linked glycan chains present on TCR alpha,beta and CD3 gamma,delta subunits, which are converted from immature (high mannose) oligosaccharides in the endoplasmic reticulum (ER) to mature (complex type) species within the Golgi complex. In the current study, a radiolabeling method is described that is useful for the study of TCR glycoproteins bearing immature and mature N-linked oligosaccharide chains. Specifically, we report the use of [3H] galactose as a radioactive tracer of TCR proteins containing glucose and galactose residues, present in immature and mature N-linked oligosaccharides, respectively. This technique is rapid, simple, and sensitive, and provides a unique approach for studying the processing and subcellular localization of T cell receptor proteins.

Galactose↗
PubMed1975

Structure and metabolism of glycoproteins and glycosaminoglycans secreted by organ cultures of rabbit trachea.

1. When cultured in medium 199 in an atmosphere of O2+CO2 (95:5) rabbit tracheal explants retained their viability for up to 21 days. 2. The explants secreted into the culture medium three electrophoretically separable components which were eluted in the non-retarded fraction from Sephadex G-200. 3. Digestion with papain and fractionation with a LiCl gradient on DEAE-cellulose resulted in the separation of these components, which were identified as a sialic acid-rich glycoprotein of epithelial origin, and chondroitin sulphate and hyaluronic acid from sub-epithelial cartilage and connective tissue. 4. Incorporation of radioactive precursors ( D-[U-14-C]glucose, D-[1-14-C]glucosamine, D-[1-14-C]galactose and Na2-35SO4) into these secreted macromolecules was indicative of their active biosynthesis by the tracheal tissue.

Animals↗
PubMed1976

Lipids associated with bovine kidney glomerular basement membranes.

1. After incubation of bovine glomeruli with D-[U-14C]glucose, about 21% of the total radioactivity is found in lipid extracts of glomerular basement membranes. 2. The concentration of lipids in glomerular basement membranes (4.3% of dry wt.) is lower than in the residual glomerular particles (10.8% of dry wt.). The concentrations of neutral lipids (13.9%), phospholipids (46.7%) and cholesterol (37.9%) in the total lipid extract of the glomerular basement membranes, however, differ from those in the residual glomerular particles (15.6, 54.0 and 30.9% respectively). Though residual glomerular particles show a higher lipid content, the radioactivity in this fraction only amounts to 38% of that found in the glomerular basement membranes. 3. The specific radioactivity of total glomerular basement-membrane lipids (12 600 d.p.m./mg) is about 4 times as high as that of the glomerular basement membranes. The specific radioactivities of the individual lipid components, however, differ. The highest values are found for phosphatidylcholine and triacylglycerols. The largest proportion of the radioactivity is found in the glycerol of the glycerides. The radioactivity in the fatty acids is much less and does not differ significantly in the various classes of lipids. 4. G.1.c. of methyl esters of the fatty acids does not reveal a clear difference between the fatty acid compositions of glomerular basement membranes and residual glomerular particles. 5. Treatment of glomerular basement-membrane preparations with ultrasound, the generally used procedure for glomerular basement-membrane preparations, drastically decreases the lipid content of glomerular basement membranes. 6. It is concluded that lipids are associated with the basement membranes. Further, the comparatively high radioactive labelling suggests that glomerular basement-membrane lipids may be an interesting class of substances for further pathological studies.

Animals↗
PubMed1983

Water- and solute-accessible spaces of purified peroxisomes. Evidence that peroxisomes are permeable to NAD+.

Peroxisomes were purified from liver homogenates from rats, treated with the peroxisome proliferator clofibrate, by a combination of differential centrifugation and isopycnic centrifugation in iso-osmotic self-generating Percoll gradients. Structural integrity of the peroxisomes appeared to be preserved as evidenced by a high degree of catalase latency, the absence of catalase release during purification and the exclusion of inulin (mol.wt. +/- 5000). Spaces for water and solutes were measured after incubation of the peroxisomes in iso-osmotic sucrose with radioactive water or solutes and separation of the organelles from their media by centrifugation through an organic layer. Extraperoxisomal water was corrected for by the use of radioactive dextran or inulin. The sucrose, glucose, urea, methanol and acetate-accessible spaces were identical, suggesting that these spaces represent the volume in which molecules that can cross the membrane distribute. This volume equalled 50-65% of the water space. Urate and NAD+, a cofactor of peroxisomal beta-oxidation of fatty acids, also distributed in this volume, but were also partly bound. Urate and NAD+ binding was not abolished by sonication, which released the bulk of matrix catalase activity, but NAD+ binding was seriously diminished. The peroxisomal water and sucrose spaces were estimated to be 107 microliters and 55 microliters per g of liver tissue from a clofibrate-treated rat. From quantitative morphometric data [Anthony, Schmucker, Mooney & Jones (1978) J. Lipid Res. 19, 154-165] and our marker enzyme analyses, as well as from our experimentally determined water spaces of mitochondrial and microsomal fractions, it could be calculated that the volume contamination by lysosomes, mitochondria and microsomes did not exceed 1, 8 and 6% respectively. Our data indicate that apparently intact peroxisomes are permeable to a number of small molecules, including NAD+. Whether the NAD+-binding sites in sonicated peroxisomes mirror the likely existence of a membrane carrier requires further investigation.

Animals↗
PubMed1972

Pinocytosis in Acanthamoeba castellanii. Kinetics and morphology.

The uptake of radioactively labeled albumin, inulin, leucine, and glucose by Acanthamoeba castellanii (Neff strain) was measured. The uptake is linear with time and appears to be continuous under the conditions of these experiments. Uptake is abolished at 0 degrees C. No evidence for saturation of the uptake mechanism was obtained with either albumin or leucine. Each of the four tracer molecules enters the ameba at a similar rate when the uptake is calculated as volume of fluid ingested per unit time. The data suggest that each of these molecules enters the cell by pinocytosis. The highest rate of uptake was obtained with cells in their usual culture medium containing proteose peptone, glucose, and salts but pinocytosis also continued at a reduced rate in a simple salt solution. The calculated volume of fluid taken in during pinocytosis in culture medium was about 2 microl/hr per 10(6) cells. The route of uptake was examined in the electron microscope using horseradish peroxidase (HRP) as a tracer. HRP activity was found exclusively within membrane profiles within the cytoplasm, confirming the pinocytotic mode of uptake. An estimate of the rate of surface membrane turnover due to pinocytosis was made using the biochemical and morphological data obtained. This estimate suggests that the plasma membrane turnover of one cell is on the order of several times an hour.

Amoeba↗
PubMed1988

Insulin antibodies do not influence the absorption rate of subcutaneously injected insulin.

The influence of insulin antibodies on absorption rate and plasma free insulin concentrations after subcutaneous injection of insulin, was studied in two groups of insulin-treated diabetic patients, one without insulin antibodies (n = 9) and a second with high plasma concentrations of antibodies (n = 14). Except for antibody concentration there were no differences in clinical variables. During 8 h after the injection of 12 U of iodinated neutral human insulin, residual radioactivity at the injection site, plasma glucose, and free and total insulin were measured. Significant differences in absorption rate of insulin were not found between the groups. Plasma glucose (basal value 16.8 +/- 4.4 SD vs 16.1 +/- 4.2 mmol l-1) and free insulin (basal value 8.3 +/- 1.4 vs 11.4 +/- 2.3 mU l-1, maximum after 90 min 36.9 +/- 19.5 vs 30.5 +/- 18.7 mU l-1) were never significantly different between the groups, nor were areas under the curve for free insulin (191.4 +/- 69.2 vs 170.8 +/- 98.6 mU l-1 h). In the high antibody group a small increase in bound insulin was found.

Adult↗
PubMed1980

Microbiology of methanogenesis in thermal, volcanic environments.

Microbial methanogenesis was examined in thermal waters, muds, and decomposing algal-bacterial mats associated with volcanic activity in Yellowstone National Park. Radioactive tracer studies with [(14)C]glucose, acetate, or carbonate and enrichment culture techniques demonstrated that methanogenesis occurred at temperatures near 70 degrees C but below 80 degrees C and correlated with hydrogen production from either geothermal processes or microbial fermentation. Three Methanobacterium thermoautotrophicum strains (YT1, YTA, and YTC) isolated from diverse volcanic habitats differed from the neotype sewage strain DeltaH in deoxyribonucleic acid guanosine-plus-cytosine content and immunological properties. Microbial methanogenesis was characterized in more detail at a 65 degrees C site in the Octopus Spring algal-bacterial mat ecosystem. Here methanogenesis was active, was associated with anaerobic microbial decomposition of biomass, occurred concomitantly with detectable microbial hydrogen formation, and displayed a temperature activity optimum near 65 degrees C. Enumeration studies estimated more than 10(9) chemoorganotrophic hydrolytic bacteria and 10(6) chemolithotrophic methanogenic bacteria per g (dry weight) of algal-bacterial mat. Enumeration, enrichment, and isolation studies revealed that the microbial population was predominantly rod shaped and asporogenous. A prevalent chemoorganotrophic organism in the mat that was isolated from an end dilution tube was a taxonomically undescribed gram-negative obligate anaerobe (strain HTB2), whereas a prevalent chemolithotrophic methanogen isolated from an end dilution tube was identified as M. thermoautotrophicum (strain YTB). Taxonomically recognizable obligate anaerobes that were isolated from glucose and xylose enrichment cultures included Thermoanaerobium brockii strain HTB and Clostridium thermohydrosulfuricum strain 39E. The nutritional properties, growth temperature optima, growth rates, and fermentation products of thermophilic bacterial strains 39E, HTB2, and YTB were determined.

Anaerobiosis↗
PubMed2001

High resolution SPECT in small animal research.

Single Photon Emission Computed Tomography (SPECT) is a technique used to assess physiological and biochemical processes under in vivo conditions. SPECT generates tomographic images from blood flow, glucose metabolism and receptor characteristics using radioactively labelled substances. This paper reviews the state of the art of in vivo imaging of laboratory animals in modified human and dedicated animal SPECT scanners. SPECT cameras with special collimators currently reach spatial resolutions up to 1 mm and sensitivities of about 1000 cps/MBq, allowing observation of receptor activity concentration changes in the pico-mole range. The time resolution of such cameras strongly depends on the pharmacological behaviour of the tracer and can range from several minutes to hours. Within these limits the functional characterization of many processes is possible. SPECT also offers the possibility to set up dynamic study protocols and repeated measurements of the same animal. This technique reduces the need for sacrificing animals, as was commonly practiced before the development of animal cameras. Animal SPECT gives the opportunity to monitor physiological and biochemical processes in animals in vivo, without interfering with the system under observation, and may become a valuable adjunct to the instrumentation (autoradiography, in vitro methods) of animal research.

Animals↗
PubMed1993

Upregulation of myo-inositol transport compensates for competitive inhibition by glucose. An explanation for the inositol paradox?

High glucose concentrations inhibit the uptake of myo-inositol into cells. However, whether this leads to a depletion of intracellular myo-inositol levels has been debated, because unchanged, decreased, and increased cellular myo-inositol levels all have been reported for diabetic tissues. To evaluate whether cells are capable of counterregulating impaired uptake, we have investigated myo-inositol uptake in porcine aortic endothelial cells under short- and long-term hyperglycemic conditions. Although increasing glucose concentrations inhibited acute myo-inositol uptake competitively, the uptake was increased markedly, when cells were already preincubated in a high glucose medium for > 6 h. The stimulation was maximal at 20 mM of glucose with no further increase at 40 mM glucose. The same stimulation of uptake could be induced by 5 mM of glucose plus 35 mM of raffinose, whereas 35 mM of sorbitol or mannitol, which do not compete for myo-inositol uptake, were ineffective. Lineweaver-Burk analysis revealed an increased Vmax for the induced myo-inositol transport activity, whereas the Km for myo-inositol remained constant (18 microM). The upregulated inositol transporter was still Na+ and ATP dependent, indicating that the same carrier system was operating. Uptake returned to control values when cells were again exposed to normoglycemic medium conditions for an additional 24 h. When endothelial cells were incubated with D-[U-14C]glucose and 10 microM myo-[2-3H]inositol of equal specific radioactivity for 24 h, no 14C radioactivity was found in intracellular myo-inositol, indicating that conversion of glucose to myo-inositol was rather low.

Animals↗
PubMed1986

Regulation of synthesis of lactosylceramide and long chain bases in normal and familial hypercholesterolemic cultured proximal tubular cells.

We have investigated the effects of lipoproteins on sphingolipid metabolism in proximal renal tubular cells from normal subjects and low density lipoprotein (LDL) receptor-negative homozygous familial hypercholesterolemic subjects employing radioactive precursors, e.g. [3H]serine, [3H]glucose, and [14C]galactose. Compared to cells incubated with lipoprotein-deficient serum, maximum suppression (70-80%) of incorporation of [3H]glucose and [3H]serine into ceramide and LacCer occurred when the LDL concentration in the medium was 25 micrograms/ml medium, and addition of higher amounts of LDL (up to 500 micrograms/ml medium) to normal cells did not produce further suppression. In contrast, high density lipoproteins did not suppress the incorporation of [3H]glucose into lactosylceramide (LacCer) in normal cells. The incorporation of [14C] galactose into LacCer was also suppressed by LDL (50% suppression at a concentration of 100 micrograms/ml medium). In contrast, LDL modified by reductive methylation of lysine residues did not suppress the incorporation of [3H]glucose into LacCer and the incorporation of [3H]serine into ceramide, whereas, native LDL exerted a concentration-dependent suppression of [3H]serine incorporation into ceramide and sphingomyelin in normal cells. At high concentrations of LDL (50-500 micrograms/ml medium), the incorporation of [3H]glucose and [14C]galactose into LacCer in homozygous FH cells was stimulated approximately 2-fold. Maximum stimulation of [3H]serine incorporation into ceramides, LacCer, and sphingomyelin occurred at 100 micrograms LDL/ml medium. Our studies indicate that the endogenous synthesis of sphingolipids in normal renal cells is regulated by the LDL receptor. Modification of the lysine residues in LDL by reductive methylation results in the inability to suppress sphingolipid synthesis in normal cells. Lack of LDL receptors, as in the case of homozygous FH cells, results in the lack of suppression of endogenous sphingolipid synthesis.

Carbon Radioisotopes↗