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Biomedical subjects

C Berne

Publications and source records attributed to C Berne.

At least 163 records · Page 9Linked to original sources
PubMed1983

Development of phosphatidyl glycerol biosynthesis in the lungs of fetuses of diabetic rats.

The lungs of fetuses of streptozotocin-diabetic rats were examined for their ability to incorporate U-14C-glucose into phosphatidyl choline, phosphatidyl glycerol, phosphatidyl inositol and lysophosphatidyl choline. In the lungs of control rats an increased biosynthesis of phosphatidyl glycerol in late pregnancy suggested a close association between the production of this phospholipid and the terminal maturation of the fetal lung. In the offspring of diabetic rats the incorporation of 14C-glucose into phosphatidyl choline, lysophosphatidyl choline and phosphatidyl glycerol was markedly decreased compared with the control rats on gestational day 20, whereas no difference was seen at day 22. Insulin treatment of the pregnant rats restored the biosynthesis of phosphatidyl choline and lysophosphatidyl choline towards normal on gestational day 20, while the ratio of phosphatidyl glycerol to phosphatidyl inositol incorporation of 14C-glucose was decreased, suggesting that the biosynthesis of phosphatidyl glycerol is more sensitive than that of phosphatidyl choline and lysophosphatidyl choline to the metabolic disturbances inherent in maternal diabetes. The delayed fetal pulmonary maturation occurred without fetal hyperinsulinism which suggests that this latter feature may not be of crucial significance in the aetiology of the respiratory distress syndrome.

Animals↗
PubMed1983

Glucose intolerance in patients with chronic inflammatory diseases is normalized by glucocorticoids.

Nine of 16 patients with inflammatory connective tissue diseases (rheumatoid arthritis, polymyalgia rheumatica, scleroderma and mixed connective tissue disease) had glucose intolerance defined a a K-rate less than one but a normal early insulin response to intravenous glucose loading. The degree of the impaired glucose handling was related to the degree of inflammatory activity as defined by acute phase reactants. Glucocorticoid therapy induced within three days an improved and normalized glucose tolerance and an augmented early insulin response (p less than 0.001). The glucocorticoid effect was still present up to six months of ongoing therapy. It is suggested that glucose intolerance in chronic inflammation is a consequence of a peripheral insulin antagonism and an inhibition of insulin secretion. This inhibition may be mediated directly or indirectly by inflammatory cell products and may be sensitive to glucocorticoids.

Adolescent↗
PubMed1983

Estimation of fetal maturity by amniotic fluid cytology, creatinine, lecithin/sphingomyelin ratio and phosphatidylglycerol.

The value of four amniotic fluid tests--the lecithin/sphingomyelin ratio, the presence of phosphatidylglycerol, amniotic fluid cytology and the creatinine concentration--in the prediction of fetal lung maturity was investigated. The sensitivity was high for all tests except for amniotic fluid cytology, which had a higher specificity. The overall outcome, particularly the value for predicting immaturity, was improved by various combinations of tests. The combination of amniotic fluid cytology and creatinine proved useful in predicting the gestational age. A diagram for estimation of gestational age is presented.

Amniotic Fluid↗
PubMed1983

Glycogen content and lipid biosynthesis in the lungs of fetuses of diabetic rats.

The fetal pulmonary glycogen content and the pulmonary biosynthesis of neutral lipids and phospholipids were estimated at gestational days 18, 20, and 22 in the offspring of normal, manifest diabetic, and insulin-treated diabetic rats. In all groups the fetal pulmonary glycogen concentration was highest on gestational day 20 and decreased during the subsequent 2 days. At the same time the biosynthesis of neutral lipids and phospholipids increased in the fetal lungs. The fetuses of the manifest diabetic rats showed an increased glycogen concentration and decreased total lipid biosynthesis compared with the other two groups. Insulin treatment of the rat mothers largely normalized the pulmonary lipid biosynthesis and glycogen accumulation in their fetuses. These data suggest that the diabetic maternal environment induces a transient block in the fetal utilization of pulmonary glycogen for the biosynthesis of lipids, in particular for the production of surfactant phospholipids.

Animals↗
PubMed1982

Short-term influence of a post-synaptic alpha-adrenoceptor blocking drug (prazosin) on carbohydrate metabolism.

Since sympathetic nervous activity is intimately involved in the regulation of hormonal and metabolic responses, it may be assumed tht antihypertensive drugs acting on adrenergic receptors will interfere with metabolic control mechanisms. We have therefore evaluated the effect of the selective alpha 1-adrenoceptor blocker prazosin on intravenous glucose tolerance and insulin response in a group of 6 healthy subjects. Ninety minutes after a single oral dose of 2 mg prazosin we observed a significant (p less than 0.05) fall in K-value (mean decrease from 1.7 to 1.0), which was accompanied by a blunting of the early insulin response. The acute effects of prazosin closely resemble those observed after 6-8 weeks of treatment with therapeutic doses of prazosin in hypertensive women. It is postulated that the effect of prazosin is mediated by an increase in circulating catecholamines acting on the pancreatic beta-cell alpha 2-adrenoceptors, which are responsible for the well-known inhibitory action of alpha-adrenergic agents upon the release of insulin.

Adrenergic alpha-Antagonists↗
PubMed1982

Skin content and plasma transport of vitamin A and beta-carotene in chronic renal failure.

The serum and cutaneous concentrations of beta-carotene and vitamin A and the serum concentrations of retinal-binding protein (RBP) and prealbumin were investigated in ten patients with chronic renal failure. The serum beta-carotene concentration was lower in the patients 1.3 +/- 0.7 mumol/l) than in the twenty-two healthy controls (2.4 +/- 0.9; P less than 0.01). The skin carotene concentration was also lower in patients than in controls (18.7 +/- 5.5 v. 24.6 +/- 9.9 nmol/g protein; P less than 0.05). By contrast, the patients' mean concentration of vitamin A in the skin was twice that of the healthy controls (11.0 +/- 4.8 v. 5.9 +/- 1.4 nmol/g protein; P less than 0.005) and in serum 3 times that of the controls (4.8 +/- 1.7 v. 1.8 +/- 0.3 mumol/l; P less than 0.001). The increase of serum vitamin A was accompanied by a rise in the RBP concentration, but the concentrations of vitamin A-esters and prealbumin remained in the normal range. It is suggested that vitamin A may accumulate in the skin as a result of an increased transfer of the vitamin by RBP. A possible relationship between high skin levels of vitamin A and uraemic skin symptoms is discussed.

Adult↗
PubMed1981

Lipid metabolism of isolated mouse pancreatic islets maintained in culture at different glucose concentrations.

The lipid metabolism of isolated mouse pancreatic islets, which had been cultured for one week at 3.3 or 16.7 mM glucose, was examined in short-term experiments performed at the end of the culture period. It was found that: a) high-glucose cultured islets oxidized palmitate at a higher rate: and b) both groups of cultured islets increased the rate of incorporation of (U-14C)-glucose into triacylglycerols and phospholipids in response to an acute glucose challenge. This latter effect was, however, more pronounced after culture at a high glucose concentration. The present data suggest that long-term exposure to high concentrations of glucose leads to a general increase of islet oxidative metabolism. Moreover, high glucose culture seems to induce an increased conversion of carbohydrates into triacylglycerols and membrane phospholipids.

Animals↗
PubMed1980

Lung maturation in fetuses of diabetic rats.

Pulmonary maturation in diabetic pregnancy has been studied in the 20-day-old fetuses of manifest diabetic rats. The animals were either untreated or treated with insulin. The diabetic state was induced by a single IV injection of streptozotocin given about 2 wk before the onset of pregnancy. The biosynthesis of lung surfactant was estimated by monitoring the rate of incorporation of [methyl-3H]choline into phosphatidylcholine and lysophosphatidylcholine in fetal lung slices. In the untreated group, the biosynthesis of both phosphatidylcholine and lysophosphatidylcholine were decreased in the fetal lung. Insulin treatment abolished the decrease in the phosphatidylcholine biosynthesis, whereas the lysophosphatidylcholine biosynthesis reamined depressed. Light and transmission electron microscopical studies indicated a delayed pulmonary maturation in the untreated offspring accompanied by a decreased cytoplasmic content of glycogen in the alveolar epithelial cells.

Animals↗
PubMed1978

Enzymatic studies of liver cells obtained by fine needle biopsy from mice with the obese-hyperglycemic syndrome (genesymbol ob).

In an enzymatic study of livers from obese hyperglycemic mice (obob) and their lean litter mates, microdissected freeze-dried fine needle biopsies were used. Carbohydrate, fatty acid and ketone body metabolism was examined through assays of phosphofructokinase (PFK), 3-hydroxyacyl-CoA dehydrogenase (HOADH) and D-3-hydroxybutyrate dehydrogenase (HBDH). At 2 months of age the obob-mice showed a significant increase in PFK activity as compared to their lean litter mates. No such difference was found for the activity of HOADH and HBDH. An early increase in the initial glycolysis in the livers of obob-mice might thus be one of the factors responsible for the accelerated synthesis of lipids resulting in the fatty livers of the adult obob-mice. The present results corroborate previous studies indicating no major derangement in the fatty acid and ketone body metabolism in the livers of obob-mice. In a methodological evaluation of the technique for tissue sampling and preparation, freeze-dried fine-needle punctates showed significantly higher enzyme activities of PFK and HOADH than freeze-dried liver sections or crude homogenates. Freeze-drying of fine needle biopsies appears to be a technique with good preservation of the enzyme activity. This is of significance for future metabolic studies also in humans.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1976

Long-term effects of a high glucose concentration on cyclic nucleotide phosphodiesterase activity in mouse pancreatic islets maintained in tissue culture.

It has been suggested that the stimulatory effect of glucose on insulin release may be mediated by the adenylate cyclase-cyclic AMP phosphodiesterase system. In this study it was found that exposure of isolated pancreatic islets to an elevated extracellular glucose concentration for 1 week in vitro caused an increase of the cyclic AMP phosphodiesterase activity in the islet cells. These and previous data indicate that there is an increased turnover of cyclic AMP in B-cells exposed for a prolonged time to a high extracellular glucose concentration, which also causes an increased turnover rate of insulin.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1976

Determination of D-3-hydroxybutyrate dehydrogenase in mouse pancreatic islets with a photokinetic technique using bacterial luciferase.

A sensitive assay for d-3hydroxybutrate dehydrogenase (EC 1.1.1.30) was developed for use with the minute amounts of material obtained from islets of Langerhans microdissected from freeze-dried pancreatic sections. NADH formed in the enzyme reaction was determined by photokinetic analysis of the luminescence obtained with bacterial luciferase from Achromobacter fishcherii. In this way, accurate determination was obtained with less than 0.1 mug dry weight of islet material. In obese hyperglycemic mice, the islet enzyme had an activity of 4.7 mumoles/min and g dry weight. Optimal enzyme activity was found at pH 8 for the islet enzyme. The enzyme activity was similar in pancreatic islets and acini, while considerably higher activity was found in cardiac muscle, liver and renal cortex. Normal mouse islets showed about equal enzyme activity as the islets from obese hyperglycemic mice.

Alcaligenes↗
PubMed1975

Glucose dependent alterations of mitochondrial ultrastructure and enzyme content in mouse pancreatic islets maintained in tissue culture: a morphometrical and biochemical study.

Isolated islets of Langerhans from mice were maintained in tissue culture for one week at either a high (28 mM) or a low (3.3 mM) extracellular glucose concentration. Electron microscopic morphometry by means of stereological methods revealed a much greater volume of mitochondria in islet cells cultured at low glucose than in those cultured at high glucose. The former islets also showed a higher activity of the mitochondrial marker enzyme, L-3-hydroxyacyl-CoA-dehyrogenase (E.C.1.1.1.35). These results indicate a true mitochondrial hypertrophy at the low glucose concentration. Although it is known from previous studies that the islet cell metabolism is diminished after low-glucose culture, the present observations of an increased mitochondrial volume probably do not reflect a degenerative process, but rather adaptive changes towards oxidation of energy yielding substrates other than glucose.

Alcohol Oxidoreductases↗