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Biomedical subjects

N Grunnet

Publications and source records attributed to N Grunnet.

At least 127 records · Page 7Linked to original sources
PubMed1987

Dual-digitonin-pulse perfusion. Concurrent sampling of periportal and perivenous cytosol of rat liver for determination of metabolites and enzyme activities.

A previously described digitonin-perfusion technique [Quistorff, Grunnet & Cornell (1985) Biochem. J. 226, 289-297], by which intracellular material of rat liver could be liberated, has been refined, now allowing release of cytosol of high purity from both periportal and perivenous parts of the same liver. The cytosolic fractions are obtained by perfusing the liver for short intervals (10-20 s) with digitonin (4-5 mg/ml), first in the normal perfusion direction and then, after an interval of 1-2 min, in the retrograde direction, the eluate being collected during and after both intervals. The technique is termed 'dual-digitonin-pulse perfusion'. The eluate fractions showed a peak specific activity of the cytosolic enzymes alanine aminotransferase (ALAT), lactate dehydrogenase (LDH) and pyruvate kinase (PK) of 3-5-fold higher than obtained in a biopsy from the same liver. For glutamine synthetase (GS) a 10-fold higher specific activity was obtained. Zonation, defined as the ratio of the specific activities in periportal and perivenous eluates, of ALAT, LDH and PK was 10, 1.7 and 0.70 respectively. Zonation of GS was less than 0.01. These factors may be modified by a slight zonation of cytosolic protein of 1.2-1.3. Peak concentrations in the eluate of ATP, ADP, Pi, NAD+ and glycerol 3-phosphate were 32.5 +/- 11.4, 19.9 +/- 4.3, 71.9 +/- 25.4, 2.41 +/- 0.83 and 6.84 +/- 2.74 nmol/mg of protein for periportal eluates. There was no difference between periportal and perivenous eluates except for glycerol 3-phosphate, which was significantly higher in perivenous eluates, 12.8 +/- 4.5 nmol/mg of protein.

Alanine Transaminase↗
PubMed1987

Genetic investigations in atopic dermatitis.

In a population based study of 68 individuals with atopic dermatitis and 94 control individuals it was not possible to demonstrate any significant associations between the disease and gene frequencies of HLA-ABC, ABO, MN, Rhesus, Kell, Duffy, Hp, Gc, Gm, Km/Inv, PGM, AcP, GPT, EsD, GLO, AK, PGD, ADA, and GALT/Gt.

Blood Group Antigens↗
PubMed1987

The ability of uremic serum to induce neutrophil chemotaxis in relation to hemodialysis.

The ability of serum to attract normal neutrophil granulocytes was investigated in 11 uremic patients before and after hemodialysis using a modified assay system for granulocyte migration under agarose. The chemotactic responses towards serum from the uremic patients were significantly decreased (p less than 0.01) prior to hemodialysis compared to control serum from a healthy individual. Hemodialysis acutely normalized the depressed chemotactic responses. It is concluded that hemodialysis improves the ability of uremic serum to attract neutrophils, and it is suggested that this improvement might be due to removal of granulocyte inhibitory factors from the sera.

Chemotaxis, Leukocyte↗
PubMed1987

Long-term culture of hepatocytes: ethanol oxidation and effect of ethanol on enzyme activities and albumin secretion.

Rat hepatocytes were cultured in a modified HI-WO/BA medium for 13 days, and the combined effect of dexamethasone, 10(-7) M, insulin, 10(-8) M, and glucagon, 10(-9) M on the DNA-content, and on the activity of several enzymes, the secretion of albumin and the rate of ethanol oxidation was investigated. The effect of ethanol on these parameters was also studied. All parameters measured declined with time in the hormone-free cultures. In hormone-supplemented cultures, the DNA-content, the activity of glucokinase, pyruvate kinase, hexokinase and lactate dehydrogenase and the secretion of albumin was maintained at reasonable levels throughout the 13 days, whereas both the activity of alcohol dehydrogenase and the rate of ethanol oxidation fell significantly, although less than in hormone-free cultures. Addition of 50 mM ethanol to the hormone-supplemented culture medium caused a ca. 20% fall in the activity of glucokinase and pyruvate kinase and a 20% increase in alcohol dehydrogenase activity. No effect of ethanol was observed on the activity of hexokinase and lactate dehydrogenase or on the secretion of albumin.

Albumins↗
PubMed1987

Ethanol-induced accumulation of triacylglycerol in cultured hepatocytes: dependency on ethanol metabolism.

Calculations based on net changes and [1-14C]oleate incorporation data suggest that fatty acids are the only precursor of acetylCoA and that extensive lipolysis takes place in hepatocyte cultures incubated with 1 mM oleate in the absence or presence of ethanol. The effect of 4-methylpyrazole on fatty acid metabolism as affected by ethanol has been studied. The ethanol-induced increase in fatty acid uptake was found to be an effect of ethanol per se, whereas the decreased oxidation of fatty acids and secretion of VLDL-triacylglycerol was found to be due to ethanol metabolism.

Animals↗
PubMed1987

Rate determining factors of ethanol oxidation in hepatocytes from starved and fed rats: effect of acetaldehyde concentration on the rate of NADH oxidation catalyzed by alcohol dehydrogenase.

Rates of reduction of acetaldehyde and pyruvate catalyzed by alcohol dehydrogenase and lactate dehydrogenase have been estimated in isolated hepatocytes from rats metabolizing ethanol and [2-3H]lactate. The concentration of the substrates of the two dehydrogenases were varied by addition of fructose and cyanamide. Calculation of the rates are based on the detritiation pattern of lactate and the labelling pattern of ethanol and glucose. The rate of acetaldehyde reduction increased with the concentration of acetaldehyde and ranged from 1-20 mumol/min ml cells. Net ethanol oxidation was decreased only under conditions with a high rate of reduction of acetaldehyde. The results suggest that the rate of net ethanol oxidation is determined by the activity of acetaldehyde dehydrogenase relative to that of alcohol dehydrogenase.

Acetaldehyde↗
PubMed1986

Periportal and perivenous hepatocytes retain their zonal characteristics in primary culture.

Periportal and perivenous hepatocytes from rat liver were isolated by combined digitonin-collagenase perfusion, and gluconeogenesis, urea synthesis and fatty acid synthesis was measured both in freshly isolated cells and in primary culture. A periportal zonation of gluconeogenesis and urea synthesis of about 3 and 1.5 fold, respectively, was observed. This zonation persisted unchanged for 23 hours in culture under identical conditions of incubation for periportal and perivenous cells. Fatty acid synthesis was not zonated.

Alanine Transaminase↗
PubMed1986

HLA antigens in a family with Behçet's syndrome.

A family is described in which 3 of 12 members suffered from Behçet's syndrome. Four members, including the three patients with Behçet's syndrome suffered from recurrent aphthous stomatitis. These four family members possessed the HLA-haplotype HLA A2, B15, Cw3, DR4. However, one relative had inherited the same HLA-haplotype without showing any symptoms of the disease. Genetic influence from the actual HLA-haplotype may interact in manifestation of the syndrome.

Adolescent↗
PubMed1986

HTLV-III antibody testing in three Danish blood banks.

The Organon Teknika Vironostika anti-HTLV-III/LAV test was evaluated in three Danish blood banks. The evaluation comprised in total 3,940 consecutive donors. In all three blood banks the tests were carried out exactly according to the manufacturer's instructions, using a low cut-off value defined as (4N + P)/5, where N and P are means of optical densities of known negative and positive samples. By this method the overall frequency of repeatably positive samples was 0.30%. When tested by Western blot, however, none of these samples were shown to contain specific antibodies against HTLV-III/LAV proteins. When testing different categories of patients, only sera containing HLA antibodies gave rise to false-positive reactions. Finally, important differences in the results were observed regarding sample preparation, single or dual wavelength optical density readings, and the experience of the technical staff.

Antibodies, Viral↗
PubMed1986

The effect of ethanol on the beta-oxidation of fatty acids.

The application of radiolabeled fatty acids to measurements of fatty acid oxidation is discussed and a method for measuring the rate of beta-oxidation and of acetyl-CoA oxidation to CO2 is described. In hepatocytes from starved or fed rats, ethanol inhibited total beta-oxidation in the presence of 1.3 mM palmitate by 22% and 25%, respectively. If changes in the specific radioactivity of acetyl-CoA were not corrected for, the effect of ethanol would have been overestimated by 15% and underestimated by 15% in hepatocytes from fed and starved rats, respectively. In perfused liver from fed rats, inhibition by ethanol of total beta-oxidation in the presence of 1 mM palmitate was 35%. The rate of beta-oxidation in the absence of ethanol was underestimated by 65% if proper corrections were not applied. Inhibition of the tricarboxylic acid cycle by ethanol was 57% and 72% in hepatocytes from starved and fed rats, respectively. Pyrazole titration experiments demonstrated a correlation between changes in the mitochondrial NADH/NAD+ ratio and both inhibition of the tricarboxylic acid cycle and inhibition of the beta-oxidation pathway. The concentration of acetoacetyl-CoA is suggested as an additional regulatory factor of the beta-oxidation pathway. The ethanol-induced accumulation of triacylglycerol as a consequence of the inhibition of the beta-oxidation pathway is estimated to represent a 10% increase in the cellular triacylglycerol pool/hr/g of wet weight. Hence its chemical determination requires experiments of several hours duration. Primary cultures of hepatocytes have been shown to be a useful experimental system for studies of the ethanol-induced triacylglycerol accumulation.

Acetyl Coenzyme A↗
PubMed1986

Biocompatibility of a new polycarbonate dialysis membrane.

The present report summarizes our experience with a new polycarbonate (PC)-based dialysis membrane (Gambro Lundia PRO-5) compared with a cuprophan (CP)-based membrane (Gambro Lundia 10-5N). Platelet count decreased during dialysis with CP, but was unchanged with PC membranes. Platelet injury, reflected by decreased platelet aggregation and increase in plasma beta-thromboglobulin, occurred equally with both membranes. Complement activation (C3d and C5a), leukopenia and release of granulocyte-derived elastase was more extensive with CP than with PC membranes. The new membrane represents an improvement of biocompatibility with respect to the complement-leukocyte system, whereas the effect on platelets resembles the injury caused by CP membranes.

Adenosine Diphosphate↗
PubMed1985

Effect of ethanol on lipid metabolism in cultured hepatocytes.

Isolated rat hepatocytes were cultured in a modified HI-WO/BA medium for 16 h. In the following 24 h oleate or oleate plus ethanol was added to the medium. After this period the medium was changed again and the cultures were further incubated with [1-14C]oleate alone or with [1-14C]oleate plus ethanol for 6 h. This allowed a comparison of effects of short-term (6 h) and long-term (24 + 6 h) exposure to ethanol on fatty acid metabolism. The increased intracellular accumulation of triacylglycerol in the presence of ethanol was quantitatively accounted for by increased fatty acid uptake, by decreased fatty acid oxidation in the tricarboxylic acid cycle and by decreased VLDL (very-low-density lipoprotein)-triacylglycerol secretion. Ketone-body production was not affected. After short-term exposure the rate of accumulation of triacylglycerol was increased by 50%. This increase was accounted for by increased fatty acid uptake (44%), decreased tricarboxylic acid-cycle activity (49%) and decreased VLDL-triacylglycerol secretion (7%). After long-term exposure, the rate of accumulation of triacylglycerol was increased by 74%. This increase was accounted for by increased fatty acid uptake (34%), decreased tricarboxylic acid-cycle activity (34%) and decreased VLDL-triacylglycerol secretion (32%). The larger increase in accumulation of triacylglycerol after long-term exposure to ethanol was entirely accounted for by increased inhibition of secretion of VLDL-triacylglycerol. The biochemical mechanisms underlying the observations are discussed.

Animals↗
PubMed1985

Contribution of non-ADH pathways to ethanol oxidation in hepatocytes from fed and hyperthyroid rats. Effect of fructose and xylitol.

The metabolism of (1R)[1-3H]ethanol, [2-3H]lactate or [2-3H]xylitol was studied in hepatocytes from fed or T3-treated rats in the presence or absence of fructose or xylitol. The yields of tritium in ethanol, lactate, water, glycerol and glucose were determined. A simple model, describing the metabolic fate of tritium from these substrates is presented. The model allows estimation of the ethanol oxidation rate by the non-alcohol dehydrogenase pathways from the relative yield of tritium in water and glucose. The calculations are based on a comparison of the fate of the 1-proR-hydrogen of ethanol and the hydrogen bound to carbon 2 of lactate (or xylitol) under identical condition. In our calculations we have taken into account that the reactions catalyzed by lactate dehydrogenase and alcohol dehydrogenase are reversible and that lactate or ethanol labelled during the metabolism of the other tritiated substrates will contribute to the tritium found in water. The contribution of non-ADH pathways to ethanol oxidation varied from 10 to 50% and was correlated to changes in the lactate/pyruvate ratio from 80 to 500. In T3-treated rats the activity of non-ADH pathways were greater than in fed rats for the same lactate/pyruvate ratio.

Alcohol Dehydrogenase↗
PubMed1985

Digitonin perfusion of rat liver. A new approach in the study of intra-acinar and intracellular compartmentation in the liver.

Perfusing a rat liver with digitonin in the concentration range 2-20 mg/ml results in complete decolorization of the organ within 45-250 s. Decolorization progresses with time in the direction of flow, and it is therefore possible, by collecting the eluate, to obtain material from specific intracellular compartments of hepatocytes in different zones in the microcirculatory unit of the liver. The results demonstrate that cytoplasmic marker enzymes from periportal or perivenous hepatocytes can be collected with as little contamination from the other compartment as is obtained in micro-dissection studies. Furthermore, a fraction enriched in mitochondrial marker enzymes can be achieved with only 10-20% contamination by cytoplasmic material.

Animals↗