Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Small G-proteins (SMGs) require isoprenylation for their association with membranes. We have examined protein isoprenylation, subcellular distribution of SMGs, cytosolic Ca2+ changes and insulin secretion in HIT-T15 cells after treatment with lovastatin, which inhibits the production of isoprenoids by blocking mevalonate production by 3-hydroxy-3-methylglutaryl-CoA reductase. Numerous proteins in the 20-70 kDa range were found to be isoprenylated. Most of these proteins co-migrated with SMGs (21-27 kDa). Lovastatin treatment (25 microM, 24 h) decreased protein isoprenylation and affected the distribution of several SMGs, causing a large accumulation in the cytosol and a detectable decrease in membranes. Lovastatin selectively attenuated the potentiating action of bombesin and vasopressin, which activate phospholipase C in these cells, on insulin secretion stimulated by nutrients (glucose + leucine + glutamine). This lovastatin effect was overcome by mevalonate. Insulin secretion stimulated by nutrients alone or insulin release in the presence of the potentiating agents forskolin or phorbol myristate acetate remained unaffected. As the modulation of insulin secretion by isoprenaline and somatostatin were not altered by lovastatin, the drug does not non-selectively affect the binding of ligands to their receptors. Lovastatin did not interfere with the activation of phospholipase C by bombesin and vasopressin, since the rise in cytosolic Ca2+ induced by these agents was not changed. Limonene, proposed to block specifically prenyl-protein transferases of SMGs, did not alter protein isoprenylation patterns, but inhibited the stimulated insulin secretion. In conclusion, lovastatin selectively attenuated the potentiation of nutrient-induced insulin secretion by bombesin and vasopressin without affecting their activation of phospholipase C. The concomitant changes in SMG isoprenylation and their subcellular distribution after lovastatin treatment suggest that SMGs could play an important role in the bombesin and vasopressin action on insulin secretion.
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PMID:Blockade of mevalonate production by lovastatin attenuates bombesin and vasopressin potentiation of nutrient-induced insulin secretion in HIT-T15 cells. Probable involvement of small GTP-binding proteins. 842 83

Several studies have shown that exogenous human growth hormone (HGH) exerts an anabolic effect on protein metabolism in surgical patients with mild or moderate catabolism. However, contradictory results have been demonstrated in polytrauma patients where HGH did not improve protein metabolism. Aim of this study was to evaluate whether the pharmacokinetics of recombinant biosynthetic human GH (r-HGH) are altered in critically ill patients. After an overnight fast, r-HGH was infused at a rate of 460 micrograms/h/kg/bw during 120 min to five intensive care unit (ICU) patients. The patients were catabolic (nitrogen balance -11 +/- 0.5), showed normal liver function, and only one patient had a slightly impaired kidney function (creatinine > 1.5 mg/dl). Endogenous GH secretion was suppressed by continuous infusion of 50 micrograms/m2/h somatostatin. From plasma GH curves, elimination half life (t1/2kle), whole body clearance (Cltot) and steady state distribution space (DS) were calculated in an open two compartment model. Additionally, the effects of r-HGH infusion on plasma insulin, glucagon and amino acid concentrations were evaluated. T1/2kle was 19.6 +/- 2.3 min, Cltot 2.9 +/- 0.4 ml/kg/bw/min and DS 76.4 +/- 3.8 ml/kg/bw for 90 min. The plasma levels of total amino acids including the branched chain amino acids valine, leucine and isoleucine and of glutamine were significantly higher during r-HGH infusion than during the basal and somatostatin periods. In conclusion, the elimination of r-HGH in catabolic ICU patients is not different from that of healthy volunteers.
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PMID:Human growth hormone kinetics in critically ill patients. 876 7

It has been speculated that opiate tolerance and dependence may occur at the level of gene expression. Our previous studies have shown that the binding activity of a nuclear factor (ssCRE-BP) to single-stranded CRE of somatostatin gene is altered by long-term treatment with morphine in the mouse cerebellum. ssCRE-BP was purified from the mouse cerebellum by a combination of chromatography on DNA affinity agarose and Mono Q HR. The native protein exhibited a molecular size of 110-150 kDa by gel filtration, and two polypeptides of about 35-40 kDa were observed on SDS-PAGE. The cloning and sequencing of a cDNA encoding ssCRE-BP showed that the protein possesses a glycine-rich domain and a glutamine-rich domain in the amino terminus and the carboxyl terminus, respectively. To investigate the function of ssCRE-BP in the brain, recombinant glutathione-S-transferase (GST) fusion proteins containing ssCRE-BP were expressed in bacterial systems. Rabbit anti-ssCRE-BP antibodies were raised against a GST-ssCRE-BP fusion protein. Using the antibodies in western blot analysis, a polypeptide of approximately 66 kDa was detected in the brain. These findings indicate that ssCRE-BP is involved in opiate tolerance and dependence.
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PMID:Characterization of single-stranded cAMP response element binding protein (ssCRE-BP) from mouse cerebellum. 895 22

We investigated the mechanism by which a selective increase in arterial insulin can suppress hepatic glucose production in vivo. Isotopic (3-3H-glucose) and arteriovenous difference methods were used in overnight-fasted, conscious dogs. A pancreatic clamp (somatostatin, basal portal insulin, and glucagon infusions) was used to control the endocrine pancreas. Equilibration (100 min) and basal (40 min) periods were followed by a 180-min test period. In control dogs (n = 5), basal insulin delivery was continued throughout the study. In the other two groups, peripheral insulin was selectively increased at the beginning of the test period by stopping the portal insulin infusion and infusing insulin peripherally at twice the basal portal rate. One group (INS + FAT; n = 6) received an infusion of 20% intralipid + heparin (0.5 U x kg(-1) x min(-1)) to clamp the nonesterified fatty acid (NEFA) levels during hyperinsulinemia; the other group (INS; n = 7) received only saline during the experimental period. In the INS group, a selective increase in peripheral insulin of 84 pmol/l was achieved (36 +/- 6 to 120 +/- 24 pmol/l, last 30 min) while portal insulin was unaltered (84 +/- 18 pmol/l). In the INS + FAT group, a similar increase in peripheral insulin was achieved (36 +/- 6 to 114 +/- 6 pmol/l, last 30 min); again, portal insulin was unaltered (96 +/- 12 pmol/l). In the control group, basal insulin did not change. Glucagon and glucose remained near basal values in all protocols. In the INS group, NEFA levels dropped from 700 +/- 90 (basal) to 230 +/- 65 micromol/l (last 30 min; P > 0.05), but in the INS + FAT group changed minimally (723 +/- 115 [basal] to 782 +/- 125 micromol/l [last 30 min]). In the INS group, net hepatic glucose output dropped by 6.7 micromol x kg(-1) x min(-1) (P < 0.05), whereas in the INS + FAT group it dropped by 3.9 micromol x kg(-1) x min(-1) (P < 0.05). When insulin levels were not increased (i.e., in the control group), net hepatic glucose output dropped 1.7 micromol x kg(-1) x min(-1) (P < 0.05). In all groups, the net hepatic glucose output data were confirmed by the tracer-determined glucose production data. In the INS group, net hepatic gluconeogenic substrate uptake (alanine, glutamine, glutamate, glycerol, glycine, lactate, threonine, and serine) fell slightly (10.4 +/- 1.3 [basal] to 7.2 +/- 1.3 micromol x kg(-1) x min(-1) [last 30 min]), whereas in the INS + FAT group it did not change (7.3 +/- 1.5 [basal] to 7.4 +/- 0.6 micromol x kg(-1) x min(-1) [last 30 min]), and in the control group it increased slightly (9.6 +/- 1.3 [basal] to 10.3 +/- 1.4 micromol x kg(-1) x min(-1) [last 30 min). These results indicate that peripheral insulin's ability to regulate hepatic glucose production is partially linked to its inhibition of lipolysis. When plasma NEFA levels were prevented from falling during a selective arterial hyperinsulinemia, approximately 55% of insulin's inhibition of net hepatic glucose output (NHGO) was eliminated. The fall in NEFA levels brings about a redirection of glycogenolytically derived carbon within the hepatocyte such that there is an increase in lactate efflux and a corresponding decrease in NHGO.
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PMID:The role of fatty acids in mediating the effects of peripheral insulin on hepatic glucose production in the conscious dog. 900 Jun 93

Short-bowel syndrome is a rare problem in surgical practice and its prognosis depends on the length of intestinal remnants and/or the presence of a jejunostomy. In adults long-term total parenteral nutrition (TPN) can be avoided if the remaining small bowel is longer than 60-100 cm. In all, 50-60% of patients in the long-term follow-up are expected to be adequately nourished with oral feeding, 25% with enteral and parenteral feeding and less than 20% depend on long-term TPN alone. By using a modified diet (glutamine, growth hormone), intestinal absorption and overall prognosis could even be enhanced. The introduction of home TPN by specialized centres has resulted in a remarkable improvement in quality of life (> 80% good). The main complications of long-term TPN are sepsis, thrombosis and metabolic disorders. Medical therapy of diarrhoea consists of H2-receptor antagonists (hypergastrinaemia), loperamide and secretion inhibitors (somatostatin). Several surgical procedures have been performed, either to decelerate intestinal transit or to increase the area of intestinal absorption with overall unsatisfactory results. However, in the presence of small-bowel dilatation, promising surgical results (tapering, stricturoplasty, intestinal lengthening) have been achieved. There may be advances (immunosuppression) in the future that will make intestinal transplantation a good option for some patients; at present, the 1-year patient and graft survival in around 100 patients was 60% and 40%, respectively.
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PMID:[Pathophysiology, clinical aspects and therapy of short bowel syndrome]. 932 32

Morphological and physiological adaptation in residual small intestine occurs after massive enterectomy and is influenced significantly by different growth factors and hormones. The mechanism of adaptation occurs through hypertrophy and hyperplasia as well as nutrient transporter changes. These transporters are classified into different classes dependent on its biological properties. The adaptation process evolves over time and different nutrient absorption profiles occur at different postoperative stages. There is an initial decrease in amino acid transport after resection followed by a return to approximately normal levels. Glucose also follows a similar pattern of changes but returns to normal later than amino acids. The time course of these changes are different for different animals with rat adaptation being much faster than rabbit. Growth hormone (GH) induces increased amino acid transport during this adaptation period, however, appears not to affect small intestine hypertrophy or hyperplasia. The increase in transport occurs via an increase in transport numbers rather than affinity. Epidermal growth factor (EGF) also increases amino acid transport in postoperative animals. Its advantage is it is orally stable when given with a protease inhibitor. EGF also reverses the down-regulating effects of the somatostatin analogue Octreotide (SMS) post resection. EGF in combination with GH has additive effects. However, the effects of the growth factors are site specific. GH and EGF combination therapy significantly increased alanine and arginine transport in distal small bowel after 70 % enterectomy but not in the proximal small bowel. The same combination increases leucine and glutamine transport in the proximal small intestine only. Understanding the specific changes that occur with these therapies may improve quality of life for patients and also reduce that need for total parenteral nutrition.
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PMID:Intestinal adaptation and amino acid transport following massive enterectomy. 934 74

These studies were conducted to determine the effect of route of gluconeogenic amino acid delivery on the hepatic uptake of the amino acids. After a sampling period with no experimental intervention (basal period), conscious dogs deprived of food for 42 h received somatostatin, intraportal infusions of insulin (3-fold basal) and glucagon (basal), and a peripheral infusion of glucose to increase the hepatic glucose load 1.5-fold basal for 240 min. A mixture of alanine, glutamate, glutamine, glycine, serine and threonine was infused intraportally at 7.6 micromol. kg(-1). min(-1) (PorAA group, n = 6) or peripherally at 8.1 micromol. kg(-1). min(-1) (PerAA, n = 6), to match the hepatic load of gluconeogenic amino acids in PorAA. During the infusion period, there were no differences in PerAA and PorAA, respectively, with regard to arterial plasma insulin (144 +/- 18 and 162 +/- 18 pmol/L), glucagon (51 +/- 8 and 47 +/- 11 ng/L), hepatic glucose load (199.8 +/- 22.2 and 210.9 +/- 16.6 micromol. kg(-1). min(-1)), net hepatic glucose uptake (2.8 +/- 2.2 and 2.2 +/- 1.7 micromol. kg(-1). min(-1)), hepatic load of amino acids (68 +/- 14 and 62 +/- 7 micromol. kg(-1). min(-1)), or net hepatic glycogen synthesis (11.1 +/- 2.2 and 8.9 +/- 2.2 micromol. kg(-1). min(-1)). The net hepatic uptake of glutamine (2.1 +/- 0.4 vs. 0.8 +/- 0.3 micromol. kg(-1). min(-1)) and the net hepatic fractional extractions of glutamine (0.11 +/- 0.02 vs. 0.05 +/- 0.02) and serine (0.41 +/- 0.03 vs. 0.34 +/- 0.02) were greater in PorAA than in PerAA (P < 0.05). We speculate that one or more of the amino acids in the mixture causes enhancement of the net hepatic uptake and fractional extraction of glutamine, and perhaps other gluconeogenic amino acids, during intraportal amino acid delivery.
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PMID:Net hepatic gluconeogenic amino acid uptake in response to peripheral versus portal amino acid infusion in conscious dogs. 1057 53

The aim of this study was to determine the role of glucagon in hepatic glutamine (Gln) metabolism during exercise. Sampling (artery, portal vein, and hepatic vein) and infusion (vena cava) catheters and flow probes (portal vein, hepatic artery) were implanted in anesthetized dogs. At least 16 days after surgery, an experiment, consisting of a 120-min equilibration period, a 30-min basal sampling period, and a 150-min exercise period, was performed in these animals. [5-(15)N]Gln was infused throughout experiments to measure gut and liver Gln kinetics and the incorporation of Gln amide nitrogen into urea. Somatostatin was infused throughout the study. Glucagon was infused at a basal rate until the beginning of exercise, when the rate was either 1) gradually increased to simulate the glucagon response to exercise (n = 5) or 2) unchanged to maintain basal glucagon (n = 5). Insulin was infused during the equilibration and basal periods at rates designed to achieve stable euglycemia. The insulin infusion was reduced in both protocols to simulate the exercise-induced insulin decrement. These studies show that the exercise-induced increase in glucagon is 1) essential for the increase in hepatic Gln uptake and fractional extraction, 2) required for the full increment in ureagenesis, 3) required for the specific transfer of the Gln amide nitrogen to urea, and 4) unrelated to the increase in gut fractional Gln extraction. These data show, by use of the physiological perturbation of exercise, that glucagon is a physiological regulator of hepatic Gln metabolism in vivo.
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PMID:Glucagon response to exercise is critical for accelerated hepatic glutamine metabolism and nitrogen disposal. 1095 Aug 33

Huntington's disease (HD) is a hereditary autosomal dominant neurodegenerative disease characterized by motor, cognitive and psychiatric symptoms. It affects about 1 in 10,000 individuals. The onset of symptoms typically occurs in the third or fourth decade of life, though it may appear at any age. The molecular basis of the disease is the expansion of the trinucleotide CAG in the first exon of a gene on chromosome four (4p 16.3). This gene encodes the protein huntingtin of 3136 amino acids. The mutation of huntingtin produces an expanded stretch of glutamine (Gln) residues. This CAG/polyGln expansion has 6 to 39 units in normal individuals and 36 to 180 units in HD patients. The normal function of huntingtin and the pathogenic mechanisms caused by the expanded polyGln of mutant huntingtin remain incompletely characterized. Huntingtin appears to be associated with synaptic vesicles and/or microtubules and seems to have an important role in vesicular transport and/or the binding to the cytoskeleton. It is thought that this protein is important in embryogenesis and that its mutant form alters the function of the mitochondrial respiratory chain. The toxic gain of function caused by huntingtin could either be an overactivity of the normal function or the introduction of a novel function. Its interactions with other proteins could lead to an impairment of the cellular function or to its own polymerization to form insoluble aggregates. The intraneuronal aggregates could affect gene transcription, protein interactions, protein transport inside the nucleus and cytoplasm, and the vesicular transport. However, since a dissociation between the aggregation of huntingtin and the selective pattern of striatal neuronal loss has been demonstrated, it is believed that other properties of the mutant huntingtin, like proteolysis and the interactions with other proteins that affect vesicular trafficking and nuclear transport, could be responsible for the neurodegeneration. On gross examination, 80% of HD brains show atrophy of the frontal lobes. A bilateral, symmetric atrophy of the striatum is observed in 95% of the HD brains. The mean brain weight in HD patients is approximately 30% lower than in normal individuals. Striatal degeneration has an ordered and topographic distribution. The tail of the caudate nucleus shows more degeneration than the head. The caudate atrophy is associated to a gradual atrophy and neuronal loss in other brain regions as the disease progresses. The striatal and cerebral cortex projection neurons are much more susceptible to the disease than interneurons. In the neostriatum, the levels of GABA, dynorphin and substance P are decreased, but the concentrations of somatostatin and neuropeptide Y increase. An impairment of energy metabolism in HD and a sensitivity to oxidative stress and to the cytotoxic effects of glutamate seem to contribute to the neuronal death in HD. It is proposed that melatonin should be assayed in cell cultures and in transgenic animals due to its potent antioxidant and free radical scavenger properties.
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PMID:[Huntington disease. A review]. 1096 Oct 47

To test the hypothesis that fetal hepatic glutamate output diverts the products of hepatic amino acid metabolism from hepatic gluconeogenesis, ovine fetal hepatic and umbilical uptakes of glucose and glucogenic substrates were measured before and during fetal glucagon-somatostatin (GS) infusion and during the combined infusion of GS, alanine, glutamine, and arginine. Before the infusions, hepatic uptake of lactate, alanine, glutamine, arginine, and other substrates was accompanied by hepatic output of pyruvate, aspartate, serine, glutamate, and ornithine. The GS infusion induced hepatic output of 1.00 +/- 0.07 mol glucose carbon/mol O(2) uptake, an equivalent reduction in hepatic output of pyruvate and glutamate carbon, a decrease in umbilical glucose uptake and placental uptake of fetal glutamate, an increase in hepatic alanine and arginine clearances, and a decrease in umbilical alanine, glutamine, and arginine uptakes. The latter result suggests that glucagon inhibits umbilical amino acid uptake. We conclude that fetal hepatic pyruvate and glutamate output is part of an adaptation to placental function that requires the fetal liver to maintain both a high rate of catabolism of glucogenic substrates and a low rate of gluconeogenesis.
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PMID:Fetal hepatic and umbilical uptakes of glucogenic substrates during a glucagon-somatostatin infusion. 1183 55


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