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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To characterize its insulin-antagonistic effect, growth hormone (GH) was infused at variable rates (24, 12 or 6 mU kg-1 min-1) for 1 h in 7 IDDM patients. Saline infusion was used as control (C) and all patients participated in all studies. The effect of insulin was measured with the euglycaemic clamp technique for 6 h combined with d-(3-3H)-glucose to evaluate glucose turnover. The insulin levels during the clamps were similar in all studies (23 +/- 3 mU l-1). The infusions produced peak GH levels of (24 rate = 24) 157 +/- 11, (12 rate = 12) 76 +/- 7, and (6 rate = 6) 45 +/- 8 mU l-1 (mean +/- SEM). The insulin-antagonistic effect of GH on glucose uptake was seen after 2 h and was at a maximum 4 to 5 h after the start of the GH infusion (difference in glucose infusion rate between C and 24 was 1.7 +/- 0.4 mg kg-1 min-1, p < 0.01). The resistance was due to a less pronounced effect of insulin to both inhibit rate of appearance and to stimulate rate of disappearance. Infusion of GH at 12 mU kg-1 min-1 induced a less pronounced insulin resistance both with regards to maximal effect (glucose infusion rate C - GH 1.4 +/- 0.5 mg kg-1 min-1, p < 0.05) and duration (3 h). At 6 mU kg-1 min-1, a clear GH-induced insulin-antagonistic effect was only seen during the third hour of the clamp (glucose infusion rate C-GH 1.3 +/- 0.5 mg kg-1 min-1, p < 0.05). GH infusion impaired the effect of insulin to lower both the levels of free fatty acids (NEFA) and glycerol between 2 and 5 h after the start of the infusion (NEFA, C:110 +/- 29, 24:303 +/- 95, p < 0.05: glycerol, C:32 +/- 4, 24:50 +/- 7 mumol l-1, p < 0.05). The present study therefore demonstrates that the insulin-antagonistic effect of GH in IDDM is related to the plasma levels both with regard to duration and response. The results also indicate that GH impairs the effect of insulin on lipolysis in IDDM after physiological peaks.
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PMID:Characterization of the insulin-antagonistic effect of growth hormone in insulin-dependent diabetes mellitus. 858 32

To evaluate the effects of the short-term, high-dose sodium heparin therapy on biochemical markers of bone metabolism, we studied 20 patients (11 males and 9 females) with pulmonary embolism, treated with sodium heparin (daily dose range: 40,000-45,000 I.U. by continuous i.v. infusion). Heparin therapy lasted 5-7 days, after which patients received warfarin over 12 months. Eleven patients (6 males and 5 females) with ischaemic stroke, treated with i.v. glycerol and pentoxifilline, were used as controls. Before and after therapy serum and urinary markers of bone metabolism were evaluated; in 12 heparin-treated pts., the parameters were also evaluated 4 months after discontinuation of warfarin therapy. After heparin therapy a significant reduction vs. basal value was observed in levels of serum osteocalcin (ng/ml;mean + SEM): 3.32 & 0.19 vs. 2.05 + 0.21; p < 0.001. In the 12 patients evaluated 4 months after discontinuation of warfarin therapy, serum osteocalcin levels returned to basal value: 3.41 + 0.12 ng/ml (p:n.s.). No significant changes of the examined parameters were observed in controls. In conclusion, our data seem to indicate an effect of i.v. short-term heparin therapy on bone metabolism. This effect seems to be characterized by an inhibition of osteoblast function as suggested by the reduction of serum osteocalcin levels.
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PMID:Effects of short-term, high dose, heparin therapy on biochemical markers of bone metabolism. 860 85

The mechanism of triglyceride lowering by Acipimox, a nicotine acid analogue, was examined in a group of five moderately hypertriglyceridemic male rhesus monkeys. Two experiments were designed to examine the effect of the drug on lipid and glucose metabolism in nondiabetic, insulin-resistant animals. A single dose of Acipimox (8 mg/kg) given with a meal lowered the plasma free fatty acids (FFA) significantly at 4 h (0.102 +/- 0.008 vs 0.154 +/- 0.020 g/l; mean +/- SEM; P < 0.03); however, FFA concentrations returned to control levels at 6 h. Chronic administration of Acipimox (16 mg/kg q. i. d.) for 2 months produced a 31% reduction in triglyceride concentration (P < 0.05) and a significant decrease in low density lipoprotein (LDL)-cholesterol (P < 0.04), without changes in insulin action as measured by the hyperinsulinemic euglycemic clamp. Fasting FFA concentrations were not significantly altered by chronic treatment (0.163 +/- 0.013 versus 0.140 +/- 0.034 g/l). Fatty acid metabolic studies indicated increases in FFA transport (203.7 +/- 59.1 versus 136.1 +/- 26.6 microEq/min; P < 0.05), while FFA fractional clearance rate (FCR) was unchanged. Very low density lipoprotein triglyceride (VLDL-Tg) metabolic experiments, using [3H]glycerol, showed increases in production and FCR with the drug. Increased VLDL-Tg clearance, in spite of increased production of VLDL, appears to be the mechanism by which triglycerides are lowered upon chronic Acipimox administration.
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PMID:Effects of Acipimox on the metabolism of free fatty acids and very low lipoprotein triglyceride. 875 Jul 69

In order to investigate microsomal diacylglycerol acyltransferase activity, ethanol or several detergents have been used as a dispersing agent for water-insoluble substrates. However, ethanol acyltransferase interferes with the activity of this enzyme, and detergents inhibit it. We examined the properties of microsomal diacylglycerol acyltransferase in rat salivary glands without detergents or organic solvents. 1,2-Dioleoyl-sn-glycerol (1,2-diolein) was dispersed by sonication. The activity was measured as the formation rate of [14C]triglyceride using [1-14C]palmitoyl-CoA as an acyl-donor. The reaction was dependent on the microsomal protein and 1,2-diolein at least up to 145 micrograms/ml and 3.6 mM, respectively. The specific activities were 3.91 +/- 0.57 and 3.80 +/- 0.77 nmol/min per mg protein (SEM, n = 4) in the parotid and submandibular glands, respectively. They were 12- to 20-fold higher than the activities in liver, brain and spleen, and two orders of magnitude higher than that assayed with microsomal endogenous diacylglycerol. Adding tissue phospholipids to 1,2-diolein suspension reduced the concentration of 1,2-diolein required for the maximal velocity. A similar, but reduced, effect was induced by egg yolk phosphatidylcholine in place of the tissue phospholipids. The level of activity was recovered by adding another phospholipid class to the phosphatidylcholine. The results suggested that the physical condition of the substrate diacylglycerol affects diacylglycerol acyltransferase activity in rat salivary gland microsomes.
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PMID:Microsomal diacylglycerol acyltransferase in rat parotid and submandibular glands: acylation of 1,2-dioleoyl-sn-glycerol dispersed with phospholipids. 881 37

Studies were conducted to assess the efficacy and safety of a synthetic peptide-containing surfactant in the treatment of respiratory distress syndrome (RDS) in preterm (approximately 80% of normal gestation) infant rhesus monkeys. Surfactant was prepared consisting of the phospholipids dipalmitoylphosphatidyl choline and palmitoyl-oleoyl phosphatidyl glycerol and a synthetic peptide modeled after surfactant protein B (SP-B), "KL4-Surfactant" contained a peptide having the sequence KLLLLKLLLLKLLLLKLLLLK, where "K" is lysine and "L" is leucine. The peptide was selected because it mimics the repeating stretches of hydrophobic residues with intermittent basic hydrophilic residues seen in SP-B. KL4-Surfactant was shown to have biophysical activity assessed as the ability to lower surface tension at an air-liquid interface in a pulsating bubble surfactometer. Thirty premature rhesus monkeys were treated shortly after birth with one dose of KL4-Surfactant. The arterial to alveolar oxygen partial pressure ratio (a/A) was found to rise from a pretreatment level of 0.11 +/- 0.01 (mean +/- SEM), indicative of severe RDS, to 0.40 +/- 0.02 at 12-13 h post-treatment. The improvement in oxygenation persisted throughout the study period, with a mean a/A at 22-23 h of 0.45 +/- 0.07. Chest radiographs and gross and microscopic examination of the lungs all confirmed the reversal of the atelectasis seen before treatment. Animals treated with a dose of 200 mg/kg showed a faster, more consistent, and greater response than did a group treated with an average dose of 127 mg/kg. There was no evidence of toxicity after treatment with the higher dose as demonstrated by physiologic, hematologic, biochemical, and pathologic data. The importance of the peptide in the synthetic surfactant was apparent from the results obtained with a control group of nine premature monkeys treated with a non-peptide-containing surfactant; the a/A of this group was 0.15 +/- 0.03 at nine hours of age as compared with a value of 0.38 +/- 0.02 for 30 comparable animals receiving KL4-Surfactant.
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PMID:Efficacy of synthetic peptide-containing surfactant in the treatment of respiratory distress syndrome in preterm infant rhesus monkeys. 884 50

To examine the effects of alkalosis on the metabolic response to prolonged exercise, seven healthy males cycled for 1 h at approximately 70% of maximum oxygen uptake on two occasions, 1-week apart. Starting 3 h prior to exercise, subjects consumed either CaCO3 (placebo) or NaHCO3 (0.3 g.kg-1 body mass) over a 2-h period. Arterialised-venous blood samples were drawn before and during exercise for the determination of acid-base status and blood metabolites (lactate, glucose, glycerol and plasma free fatty acids). Expired gas was collected during exercise for determination of oxygen uptake (VO2) and respiratory exchange ratio to estimate fuel oxidation rates. Ratings of perceived exertion (RPE) and heart rates were also recorded. A significant (P < 0.01) alkalosis was observed at all times following bicarbonate ingestion. Blood lactate was significantly (P < 0.05) higher at all sample times throughout exercise following bicarbonate ingestion. Blood lactate concentration [mean (SEM)] reached peak values of 2.90 (0.16) and 4.24 (0.45) mmol.l-1 following 20 min of exercise following placebo and bicarbonate, respectively. No differences between treatments were noted at any time for the other metabolites. VO2 and RPE were significantly higher (P < 0.01) with the bicarbonate trial. At a constant power output increases in VO2 are generally associated with increases in fat oxidation, however, no evidence for an altered fuel oxidation was obtained in the present study. The differences in blood lactate indicate that induced alkalosis increased lactate efflux from muscle, but it cannot be confirmed whether this represents an increased rate of glycolysis within the muscle.
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PMID:The effects of induced alkalosis on the metabolic response to prolonged exercise in humans. 891 32

To our knowledge postoperative hepatic hemodynamics and hepatic metabolism have not been fully studied on a long-term basis. Our goal was to develop a large animal model that would permit the measurement of hepatic blood flow (BF), perihepatic pressures (P), and hepatic metabolism in a long-term setting. Catheters were inserted into the jugular vein, carotid artery, pulmonary artery, hepatic vein, and portal vein (PV) of 27 commercially bred pigs; ultrasonic transit time flowmeter probes were placed around the hepatic artery and PV. Daily postoperative measurements of jugular vein P, carotid artery P, pulmonary artery P, hepatic vein P, and PVP, as well as hepatic artery BF and PVBF, were recorded for 20 days. Hepatic carbohydrate metabolism was assessed by arteriovenous difference techniques. Jugular vein P, pulmonary artery P, hepatic vein P, PVP, and heart rate reached steady-state values during the first week, with a mean +/- SEM of 1.0 +/- 0.3 mm Hg for jugular vein P, 21.4 +/- 2.1 mm Hg for pulmonary artery P, 4.3 +/- 0.4 mm Hg for HVP, 7.8 +/- 0.5 mm Hg for PVP, and 116 +/- 4 beats per minute for heart rate. Mean carotid artery P increased from 65 +/- 3 mm Hg during surgery to 94 +/- 2 mm Hg on postoperative day 1 (P < 0.001) and to a mean 101 +/- 2 mm Hg thereafter. Total hepatic BF reached a steady-state value of 1,132 +/- 187 ml/min by postoperative day 7 (P = 0.19). Over week 1 hepatic artery BF measured as a percentage of total hepatic BF decreased from 35.0 +/- 3.0% to 15.5 +/- 2.7%, and PVBF increased from 65.0 +/- 3.0% to 84.5 +/- 2.7% (P < 0.005); both variables were steady thereafter. In the hemodynamic steady state the net hepatic balances of glucose, lactate, glycerol, and alanine in 5 pigs were 9.9 +/- 4.0, -4.2 +/- 0.4, -2.3 +/- 1.1, and -0.68 +/- 0.22 micromol/kg per min respectively. The net gut (portal-drained viscera) balances of glucose, lactate, alanine, and glycerol were -2.0 +/- 2.5, 1.1 +/- 0.5, 0.73 +/- 0.18, and -0.69 +/- 0.19 micromol/kg per min respectively. Thus, a reliable large animal model was developed to study acute and chronic hepatic hemodynamics and metabolism.
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PMID:A model for the extended studies of hepatic hemodynamics and metabolism in swine. 900 Nov 78

A primary culture system of chicken hepatocytes was developed to study the effects of genetic, hormonal and nutritional factors on hepatic triglyceride (TG) secretion in the chicken, and the effect of insulin on TG synthesis and secretion examined. TG synthesis and secretion was measured using [3H]-glycerol incorporation into cellular and secreted TG. An additional step consisting of brief incubation of the monolayer with trypsin solution to improve harvesting the medium immediately adjacent to the cell monolayer, is also proposed. In our culture system, TG secretion occurred at least up to 75 hr of culture, showing a maximum between 40 and 60 hr of culture. No significant effect of insulin could be observed after 24 hr of culture. A clear stimulatory effect was observed with 10(-9) M insulin concentration after 48 hr. The mean ratio of the secretion rates in the presence or absence of insulin was 2.20 +/- 0.30 (SEM, n = 4). In contrast, the 10(-6) M concentration of insulin had no effect on TG secretion. The use of an additional trypsinization step enhanced the findings obtained by simple removal of the culture medium: a clear stimulatory effect of insulin on TG synthesis was observed after both 24 and 48 hr of culture. Analysis of TG fatty acid composition showed an imbalance of monoene versus saturated fatty acids between cellular and secreted TG, secreted TG being more monounsaturated than cellular TG. These results were obtained in the absence of exogenous fatty acid. An oleic acid supplement in the culture medium did not significantly influence TG secretion. In summary, a primary culture system for chicken hepatocyte was developed. A high level of TG secretion was seen in these cells with or without exogenous fatty acid and this secretion was stimulated by insulin. It was concluded that chicken hepatocytes in primary culture provide a useful model for studying regulation of TG secretion.
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PMID:Effect of insulin on triacylglycerol synthesis and secretion by chicken hepatocytes in primary culture. 902 54

To determine the effect of acute plasma volume (PV) expansion on substrate utilization, blood metabolites and catecholamines to prolonged, moderate intensity cycle exercise, eight untrained men mean maximal oxygen uptake VO2max 4.10 (SEM 0.32) 1.min-1 were infused (10 ml.kg-1) with a 6% dextran (DEX) solution. These responses were also compared to those elicited using a short-term training (TR) protocol involving cycling for 90 to 120 min.day-1 at 60% VO2max for 3 consecutive days. In general DEX, which resulted in a calculated expansion of PV by 23.9% was without effect in modifying exercise oxygen uptake or the reduction in the respiratory exchange ratio (R) observed during prolonged exercise. In addition, the concentrations of blood glucose, glycerol, alanine and serum free fatty acids, although altered (P < 0.05) by exercise, were not altered by DEX. Blood lactate concentration was only higher (P < 0.05) at 30 min of exercise during DEX compared to the control. With the exception of blood lactate concentration, which was reduced (P < 0.05), TR did not change R or the concentrations of other blood metabolites. The concentrations of nonadrenaline and adrenaline, were depressed (P < 0.05) by DEX and TR at 60 and 90 min of exercise. These results would suggest that mechanisms as yet undefined can compensate for the estimated 10% reduction in arterial oxygen content mediated by acute PV expansion and enable prolonged exercise to be performed without adjustments in substrate selection and substrate mobilization.
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PMID:Blood metabolite and catecholamine responses to prolonged exercise following either acute plasma volume expansion or short-term training. 908 48

The osmotic tolerance limits for boar spermatozoa were determined at 22 degrees C. These cells can swell to within 1.02 times and shrink to within 0.97 times their isosmotic volume and maintain > 70% motility. In the presence of an extender, cells can swell to within 1.1 times and shrink to within 0.97 times their isosmotic volume and maintain > 70% motility. Plasma membrane permeability coefficients were determined in the presence of 1 M dimethyl sulfoxide (DMSO), 1 M glycerol, and 2 M ethylene glycol (EG) at 22 degrees C. Hydraulic conductivity (Lp) was estimated to be 0.120+/-0.016 (mean+/-SEM), 0.138+/-0.006, and 0.204 +/-0.021 microm/min/atm in the presence of DMSO, glycerol, and EG, respectively, at 22 degrees C. Solute permeability (P[CPA]) was determined to be 0.930+/-0.118, 0.481+/-0.045, and 1.98+/-0.106 x 10(-3) cm/min, for DMSO, glycerol, and EG, respectively. Subsequent experiments were performed at 8 degrees C and 0 degrees C. Activation energies were calculated for Lp in the presence of glycerol and EG to be 7.20 and 11.51 Kcal/mol, respectively. The activation energies for P(CPA) were 4.06 and 7.48 Kcal/mol for glycerol and EG permeability, respectively. These membrane characteristics were used to calculate volume flux during addition and removal of cryoprotectant agents as well as during cooling and warming. In addition, the potential for intracellular ice formation during cooling and warming was calculated.
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PMID:Determination of plasma membrane characteristics of boar spermatozoa and their relevance to cryopreservation. 947 19


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