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

We have determined the effect of unlabeled glucose infusions, with and without added insulin, on glucose metabolism in normal male volunteers by means of the simultaneous primed-constant infusion of 6-3H and U-13C-glucose. Glucose kinetics were measured after 90 min of infusion. When steady state had been reached, endogenous glucose production (2.53 +/- .058 mg/kg . min, X +/- SEM) was suppressed at all rates of exogenous glucose tested (1, 2, and 4 mg/kg . min). The absolute degree of suppression was most marked (75%) at the highest rate of infusion, but the greatest degree of suppression, relative to infusion rate, was at the lowest infusion rate. The control of plasma glucose concentration during the glucose infusion was achieved primarily through regulation of endogenous Ra. The rate of uptake of glucose only increased during the 4 mg/kg . min infusion, even though there were significant elevations in the plasma glucose and insulin concentrations during the 2 mg/kg . min infusion as well. The glucose clearance rate increased only when sufficient insulin was infused with the 4 mg/kg . min glucose infusion to control the hyperglycemia that developed if no insulin was administered. Approximately 43% of the infused glucose was directly oxidized when the infusion rate was 1 or 2 mg/kg . min. That value fell to 32% when the infusion rate was increased to 4 mg/kg . min, regardless of whether insulin was infused or not.
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PMID:Glucose metabolism in man: responses to intravenous glucose infusion. 76 55

Glucose was given as a rapid intravenous injection to fasted anaesthetized rhesus monkeys, and the concentrations of blood glucose and plasma insulin were measured. Glucose caused a biphasic insulin response. The first phase (which was short) occurred 1 min after the injection; the second was longer, and occurred 17 to 30 min after the injection. Following the control glucose injection, each animal was given atropine, and the insulin response to an identical glucose stimulus was measured. This produced a mean reduction of 45% in the area under the curve of insulin release. Both phases of insulin release were inhibited by atropine. When glucose was given alone, its mean half-time of disappearance from the circulation (t1/2) was 25.4 ( plus or minus 1.9 SEM) min. After atropine the mean t1/2 was 36.6 (plus or minus 3.1 SEM) min, a significant difference. It is suggested that the delayed rate of disappearance of glucose from the circulation is the result of inhibition of insulin release by atropine.
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PMID:The effect of atropine on insulin release caused by intravenous glucose in the rhesus monkey. 80 62

Glycogen metabolism was studied in the isolated perfused liver of the monkey conceptus at 90% of gestation using an in situ recirculating perfusion system. Net uptake of glucose and galactose and the activities of the enzymes, glycogen synthetase and phosphorylase, were studied in response to varied perfusate composition. Synthetase activity was expressed as %I. the percentage of total synthetase activity in the active form. Perfusate glucose concentrations as high as 700 mg/100 ml did not lead to net glucose uptake of to an increase in the baseline %I synthetase (4 +/- 1, mean +/- SEM). In the presence of 300 mg/100 ml glucose, insulin at 10(-7) M in creased %I to 8 +/- 2, and galactose greater than 75 mg/100 ml increased %I to 8 +/- 1. The combination of galactose, glucose, and insulin increased %I to 40 +/- 5. With this latter combination, synthetase activity was proportional to perfusate glucose concentration above 100 mg/100 ml. Phosphorylase activity was diminished by either galactose or insulin, and phosphorylase activity was lowest in the group receiving galactose, glucose, and insulin. Galactose was taken up by all livers, but net glucose uptake was not observed under any condition; net hexose uptake was observed in perfusions with galactose. Glycogen levels did not vary significantly with varied perfusate composition during the 30-min perfusion periods.
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PMID:Glycogen regulation in isolated perfused near term monkey liver. 81 75

To study the influence of luminal nutrition on the structural and functional adaptive changes which are seen in the residual intestine after partial small bowel resection, quantitative histology, in vitro uptake of 14C l-leucine, mucosal enzyme activities, and in vivo absorption of glucose were studied before and 6 weeks after 50% proximal small bowel resection in 10 greyhound dogs, 5 of which were nourished exclusively by the intravenous route while 5 were pair-fed by mouth. In the orally fed jejunectomized dogs, the ileum became dialed with mucosal hyperplasia, the villus height increased from 796 +/- SEM 26 mum to 1102 +/- 28 mum (P less than 0.001), and there was a corresponding increase in glucose absorption in vivo (milligrams -centimeter of intestine -1min-1) from 5.3 +/- 1.2 to 10.1 +/-1.6. The increased absorption seems mainly caused by the dilation and villus hyperplasia, since there was no significant change in in vitro absorption and mucosal enzyme activity when expressed per unit weight of intestine. In the absence of exogenous luminal nutrition, the well nourished intravenously fed dogs showed no evidence of functional adaptation and a significant fall in mean ileal villus height from 823 +/-48 mum at the initial operation to 732 +/-57 mum 6 weeks after jejunectomy. These results provide the most direct evidence to date that luminal nutrition is essential for the development of intestinal adaptation after resection. They also suggest that luminal contents are necessary to maintain the structural and functional integrity of the normal small bowel.
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PMID:Effects of oral versus intravenous nutrition on intestinal adaptation after small bowel resection in the dog. 81 99

The cholesterol-lowering effect of portacaval anastomosis in homozygous familial hypercholesterolemia suggested a study of lipid metabolism in cirrhotic patients after portasystemic anastomoses. Fasting serum cholesterol, triglycerides, insulin, and glucagon levels were obtained in 20 patients with alcoholic cirrhosis and portacaval anastomosis, and in 21 nonshunted subjects with cirrhosis. After 100 g of glucose, given orally, insulin and glucagon levels were measured. In the shunted patients serum cholesterol was higher than in the nonshunted subjects, 240 +/- 15 mg per 100 ml (mean +/- 1 SEM) versus 180 +/- 13 mg per 100 ml, P less than 0.01. Triglycerides were normal in both groups. Fasting insulin was elevated to a greater extent in the shunted patients with cirrhosis (36 +/- 5 muU per ml) than in the nonshunted patients (22 +/- 4 muU per ml), P less than 0.05. Two hours after glucose, insulin levels were also elevated to a greater extent in the shunted subjects (304 +/- 50 muU per ml) than in the nonshunted subjects (167 +/- 29 muU per ml), P less than 0.03. Fasting glucagon (corrected for interference factor) was elevated to a greater extent in the shunted subjects (204 +/- 35 pg per ml) than in the nonshunted subjects (80 +/- 19 pg per ml), P less than 0.01. The explanation for serum cholesterol elevation after surgical shunting in cirrhotics is unknown. Two possible hypotheses--the differential action of insulin and glucagon on cholesterol metabolism and the effects of shunting on the cirrhotic liver--are discussed.
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PMID:Serum lipids, insulin, and glucagon after portacaval shunt in cirrhosis. 83 May 79

Postprandila glycaemia and rise in serum insulin after carbohydrate-containing meals were reduced by the addition of guar flour or pectin, or both. After a liquid test meal (four subjects) the 30-min blood glucose was reduced from 6.33 +/- 0.19 mmol/litre (114 +/- mg/dl), mean +/- SEM, in the control subjects of 4.77 +/- 0.17 mmol/litre (86 +/- 3 mg/dl) by addition of guar gum (P less than 0.05). The mean insulin level was also significantly lower at 15 min. A breakfast test meal (bread, butter, marmalade, and tea) resulted in a mean 15-min blood glucose of 6.18 +/- 0.21 mmol/litre (111 +/- 4 mg/dl) in eight subjects; 10 g of pectin added to the marmalade reduced this level to 5.64 +/- 0.17 mmol/litre (102 +/- 3 mg/dl) (P less than 0.01). The insulin levels were significantly lower at 15, 30, and 45 min. A similar meal in which guar was added to the bread and pectin to the marmalade resulted in significant reductions of blood glucose at 15 min (P less than 0.002) and 30 min (P less than 0.01). The insulin values were also significantly lower throughout the first 90 min of the test. This action of unavailable carbohydrate may prove useful in the dietary control of diabetes.
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PMID:Decrease in postprandial insulin and glucose concentrations by guar and pectin. 83 24

Oxidative phosphorylation and respiratory enzyme concentrations of liver mitochondria and glucose tolerance were studied in 12 cirrhotic patients and CCl4-induced cirrhotic rats. The cirrhotic patients with normal or higher concentrations of cytochrome a(+a3) showed parabolic glucose tolerance test (GTT) patterns having return of blood glucose level somewhat toward normal within two hours and tolerated major operations well, while three patients with cytochrome a(+a3) concentrations less than 60 per cent of normal (0.81 +/- 0.02 (mean +/- SEM) X 10(-10) moles/mg protein) could not tolerate even minor operations. In CCl4-induced cirrhotic rats, cytochrome a(+a3) concentrations varied from 1.5 to 3.0 X 10(-10) moles/mg protein as compared with 1.8 +/- 0.1 of controls. In mitochondria with normal or higher concentrations of cytochrome a(+a3), the oxidative and phosphorylative activities per unit of cytochrome a(+a3) were negatively correlated with cytochrome a(+a3) concentrations. These rats tolerated partial hepatectomy well. However, in cirrhotic rats with subnormal cytochrome a(+a3) concentrations there was a high mortality following hepatectomy. The former showed parabolic GTT patterns, while the latter showed nonparabolic GTT patterns.
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PMID:Adaptive increase of respiratory enzymes in the mitochondria from cirrhotic livers of patients and rats, and its relationship to glucose tolerance. 84 6

The intestinal absorption of sodium taurocholate was studied in the near-term fetal and neonatal dog. Absorption rates were measured in vivo in isolated loops of fetal jejunum and ileum. Absorption was also measured in vitro in everted sacs and rings of fetal and neonatal jejunum and ileum. The maximal rates of taurocholate absorption observed after instillation of 1 micronmol taurocholate into closed segments of fetal jejunum and ileum with intact blood supply were not significantly different (P less than 0.2), and equalled 0.282+/-0.026 (mean+/-SEM) and 0.347+/-0.051 micronmol/h per 10-cm segment length jejunum and ileum, respectively. Similarly, the rates of absorption from open segments of jejunum and ileum perfused with 0.4 and 1.0 mM taurocholate were nearly identical (0.232+/-0.040 and 0.255+/-0.039, respectively at 0.4 mM, and 0.470+/-0.065 and 0.431+/-0.013, respectively at 1.0 mm) (P greater than 0.2). At perfusate concentrations of 4.0 mM, moreoever, jejunal absorption exceeded ileal absorption (1.490+/-0.140 and 0.922+/-0.200, respectively (P less than 0.05). As expected, concentration of taurocholate by the mucosa was readily demonstrated in adult ileal, but not in adult jejunal everted rings. In contrast, there were no significant differences in mucosal uptake of taurocholate by fetal jejunal and ileal rings. Fetal ileal mucosal concentrations were not significantly above those in the incubation medium after 1-h exposure of the mucosa to 0.003, 0.03, and 0.3 mM taurocholate. Uptake was proportional to incubation medium concentration over the full range of values. This was also true of tissues from 1-wk-old neonates. However, by 2 wk of age, ileal mucosal concentration of taurocholate was evident and adult levels were attained by 5 wk of age. It is concluded that taurocholate is absorbed by the fetal gut and that ileal absorption is no more efficient than jejunal absorption. Although active glucose transport was demonstrable in both jejunum and ileum, it was not possible to demonstrate an ileal mechanism for active transport of taurocholate in the fetus. Active ileal transport was not demonstrable in the newborn until at least 2 wk after birth.
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PMID:Fetal bile salt metabolism. The intestinal absorption of bile salt. 86 98

The effects of two levels of morphine-nitrous oxide anesthesia on cerebral blood flow (CBF) and cerebral metabolism (CMRO2) were measured in healthy male volunteers. CBF and metabolic measurements were made in the awake control state, after morphine, 1 mg/kg, with 70 per cent nitrous oxide and 30 per cent oxygen, and at a total dose of 3 mg/kg morphine with the same concentrations of nitrous oxide and oxygen. Ventilation was controlled and carbon dioxide added to inspired gas to maintain PaCO2 constant at 40 torr. CBF was 48.2 +/- 4.4 (SEM) ml/100 g/min during the control phase; 45.7 +/- 6.4 ml/100 g/min after 1 mg/kg morphine, and 44.3 +/- 4.9 ml/100 g/min after 3 mg/kg morphine. The latter values are not significantly different from control. Cerebral metabolic rates for oxygen, glucose, and lactate were normal in the control phase and did not change significantly when morphine was present at either level. It is concluded that morphine-nitrous oxide anesthesia produces no alteration of cerebral blood flow or metabolism in normal man at the two dose levels studies.
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PMID:Cerebral blood flow and metabolism during morphine--nitrous oxide anesthesia in man. 86 45

Glucose and fructose were studied in eight healthy volunteers who fasted twice for 4 days. Before and after the fasts each subject received a 4-hr glucose or fructose infusion providing 0.5 g/kg/hr. Glucose infusion during starvation resulted in a mean maximal plasma glucose rise of 401 +/- 21 mg/100 ml (+/- SEM) as compared to 119 +/- 10 mg/100 ml before starvation. Insulin/glucose ratios were lower than normal in fasted subjects. Fructose infusion during fasting produced a maximal plasma glucose rise of 91 +/- 9 mg/100 ml as opposed to 5+/-1 mg/100 ml before starvation. During fructose infusion in the fasted state, plasma fructose levels were higher than control and the rise in blood lactate and pyruvate was delayed, but finally lactate concentrations were above control values. The antiketotic effects of intravenous glucose and fructose were similar during fasting but fructose was significantly less potent in reducing free fatty acid levels. After starvation, urinary carbohydrate losses during glucose infusion were 5 times higher than those observed during fructose infusion. Thus, fructose utillization was less impaired during fasting than was glucose utilization, although fasting induced abnormalities in both glucose and fructose metabolism.
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PMID:Comparison of glucose and fructose tolerance before and after starvation. 90 56


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