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Query: UMLS:C0023890 (cirrhosis)
 42,195 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Insulin has been shown to be vasodilatory and antinatriuretic and to stimulate sympathetic nervous activity independent of hypoglycemia in healthy normal subjects. It is hypothesized that hyperinsulinemia, which is commonly observed in cirrhosis, may in part be responsible for the systemic vasodilatation, sympathetic activation, and sodium retention in these patients. The aims of this study, in preascitic cirrhotics, were as follows: (1) to document baseline hyperinsulinemia and its effects on sodium handling, forearm and renal circulations, and sympathetic nervous activity; (2) to determine if pharmacological increases in plasma insulin levels would result in an exaggeration of these physiological effects. Seven male, nonobese, well-compensated, preascitic cirrhotic patients were studied, after being maintained on a 150 mmol sodium per day diet for 7 days, firstly at baseline level, followed by increasing doses of insulin from 10 to 1,200 mU/m2/min using the euglycemic clamp technique. Systemic and renal hemodynamics, urinary sodium excretion, plasma norepinephrine, and forearm blood flow (FBF) were measured at the end of baseline and each hyperinsulinemic period. Baseline measurements in the cirrhotics, when compared with our laboratory standards obtained from a comparable group of male healthy normals, showed significant hyperinsulinemia (P=.01), associated with significantly higher FBF (P=.02), and glomerular filtration rate (GFR) (P=.02), as well as significantly reduced urinary volume (P=.04) and fractional excretion of sodium (P=.04). Insulin infusions in the cirrhotics produced no further sodium retention, but further forearm vasodilatation occurred at doses > or = 10 mU/m2/min. In contrast, there was no further renal vasodilatation except at very high pharmacological levels of insulin together with an unchanged GFR, natriuresis, and diuresis. Hyperinsulinemia produced no significant effects on the sympathetic nervous activity. In conclusion, these results suggest that hyperinsulinemia may be implicated in the glomerular hyperfiltration and sodium retaining tendency of preascitic cirrhotic patients with glucose intolerance. The ability of the kidneys to escape from the sodium retaining effects may serve as an in-built physiological regulatory mechanism on sodium homeostasis.
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PMID:Hyperinsulinemia in preascitic cirrhosis: effects on systemic and renal hemodynamics, sodium homeostasis, forearm blood flow, and sympathetic nervous activity. 861 19

Liver cirrhosis in man is often associated with hyperinsulinemia but its pathogenesis is still unexplained. To investigate whether insulin degradation is impaired in cirrhotic liver, the specific insulin-degrading enzyme activity (EC 3.4.22.11) was assayed in liver cytosol of rats with CCl4-induced liver cirrhosis. No difference was found between liver cytosol of cirrhotic and control rats. The results show that experimental CCl4-induced liver cirrhosis does not damage the specific insulin-degrading activity and support the hypothesis that impaired hepatic insulin handling is not an important cause of hyperinsulinemia in liver cirrhosis.
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PMID:Insulin-degrading activity in experimental liver cirrhosis of the rat. 882 7

Impaired glucose tolerance(IGT) frequently occurs in patients with liver diseases. Because of the central role of the liver in carbohydrate metabolism, it is generally assumed that impaired hepatic metabolism plays a major role in the pathogenesis of IGT in liver disease. However, recent observation using glucose clamp techniques has demonstrated that the majority of patients with cirrhosis are characterized by peripheral hyperinsulinemia and insulin resistance of muscle tissues. Glucose intolerance in patients with chronic pancreatitis in related to impaired glucose-mediated insulin secretion, which is induced by the loss of B-cell mass in the pancreas. Patients with hemochromatosis have insulin resistance in the precirrhotic stage. The mechanism of insulin resistance, produced by iron overload, remains unknown.
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PMID:[Impaired glucose tolerance in liver and pancreas disease]. 891 34

We examined whether a single bout of moderate exercise has a beneficial effect on insulin sensitivity and fuel homeostasis in cirrhosis. Clinically stable cirrhotic patients and age-, sex-, and weight-matched controls participated in insulin clamp studies (either euglycemic hyperinsulinemic or hyperglycemic hyperinsulinemic) in combination with indirect calorimetry and [6,6-2H2]glucose. Three to seven days later, studies were repeated following a single bout of exercise (30 minutes of treadmill exercise at 60% of maximal aerobic capacity). After an overnight fast, following exercise, both cirrhotic and control individuals showed a shift in fuel utilization to enhanced lipid oxidation, decreased glucose oxidation, and increased nonoxidative glucose disposal rates (i.e., glycogen synthesis in muscle) when compared with pre-exercise rates but differences were statistically significant only in the patient group. During euglycemic hyperinsulinemia, insulin-mediated glucose disposal was significantly reduced in cirrhotic patients (3.43 +/- 0.26 vs. 7.36 +/- 0.48 mg/kg/min, P < .01). Following exercise, glucose uptake increased significantly in cirrhotic patients when compared with pre-exercise levels (P < .05) but remained unchanged in the control group. The increase in total body glucose disposal in cirrhotic patients was entirely accounted for by an increase in nonoxidative glucose disposal (0.81 +/- 0.20 vs. 0.51 +/- 0.15 mg/kg/min, P < .05). During combined hyperglycemia/hyperinsulinemia, however, insulin sensitivity was unaffected by exercise in both patients and control individuals. In summary, in cirrhotic patients, a single bout of moderate exercise 1) causes a shift in substrate utilization with an increase in lipid oxidation in the postexercise period that is significantly more pronounced than in controls, and 2) increases insulin sensitivity only during euglycemia but not during the more physiological condition of hyperglycemia. Single bouts of moderate exercise therefore may not have a beneficial effect on the metabolic status of patients with chronic liver disease.
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PMID:Effect of moderate exercise on insulin sensitivity and substrate metabolism during post-exercise recovery in cirrhosis. 932 22

Insulin resistance is present in nearly all patients with cirrhosis, but its etiology remains unknown. Chronic hyperinsulinemia has been suspected as a potential candidate, and we therefore tested the hypothesis that, in cirrhosis, prolonged reduction of the hyperinsulinemia restores insulin sensitivity. Whole-body insulin sensitivity (euglycemic insulin-clamp technique), glucose turnover (6,6-2H2-glucose isotope dilution), glucose oxidation (indirect calorimetry), non-oxidative glucose disposal, and fractional glycogen synthase activity in muscle (biopsies) were measured in eight clinically stable patients with cirrhosis before and at the end of a 4-day continuous subcutaneous infusion of the somatostatin-analogue octreotide (200 microg/24 h) designed to continuously reduce plasma insulin levels. Baseline data were compared with results obtained in healthy individuals matched for sex, age, and weight (n = 8). During the baseline (pre-octreotide) study, patients demonstrated a significant decrease in insulin-mediated glucose uptake compared with controls (5.75 +/- 0.21 vs. 7.98 +/- 0.84 mg/kg/min; P < .03), which was entirely accounted for by an impairment in non-oxidative glucose disposal (P < .04). Four-day infusion of octreotide to cirrhotic patients: 1) reduced postabsorptive and meal-stimulated plasma insulin levels by approximately 35% to 45% without significantly affecting glucose tolerance; 2) did not significantly alter plasma free fatty acids (FFA), growth hormone, and glucagon levels in the postabsorptive state and during the meal test; 3) normalized insulin-mediated whole-body glucose disposal (7.63 +/- 0.72 mg/kg/min post-octreotide; P = not significant vs. control). Restoration of insulin-mediated glucose utilization was entirely caused by normalization of non-oxidative glucose disposal; 4) was associated with a considerably more pronounced stimulation by insulin of the fractional glycogen synthase in muscle compared with pre-octreotide results (increment above baseline pre: 0.035 +/- 0.010 vs. post: 0.060 +/- 0.023 nmol/min/mg protein; P < .04). Fractional glycogen activity significantly correlated with non-oxidative glucose disposal during insulin infusion (r = .69; P < .03). Prolonged reduction of hyperinsulinemia for 96 hours in cirrhotic patients normalizes insulin-mediated glucose uptake and glycogen synthesis in muscle. We conclude that chronic hyperinsulinemia causes insulin resistance in cirrhosis.
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PMID:Insulin resistance in cirrhosis: prolonged reduction of hyperinsulinemia normalizes insulin sensitivity. 965 6

Although the underlying mechanisms no doubt differ, activation of the sympathetic nervous system is an important pathophysiological feature in primary arterial hypertension, in portal hypertension accompanying hepatic cirrhosis, and in heart failure, and is a logical therapeutic target for centrally acting sympathetic nervous system suppressant drugs. Portal hypertension: The sympathetic outflows to skeletal muscle vasculature, the heart, the kidneys and to the hepatomesenteric circulation are stimulated in patients with alcoholic cirrhosis of the liver, perhaps as a reflex response to the vasodilatation and vascular shunting present. Acute dosing with clonidine produces dose dependent reduction in noradrenaline spillover from visceral organs and reduction in hepatic vein wedge pressure, with preservation of hepatic blood flow and negligible fall in arterial pressure. These findings indicate the clinical potential of drugs such as clonidine, moxonidine and rilmenidine for chronically lowering portal venous pressure in cirrhosis. Arterial hypertension: Activation of the sympathetic outflow to the heart, kidneys and skeletal muscle vasculature is commonly present in younger (< 45 years) patients with essential hypertension. The sympathetic stimulation appears to have adverse consequences in hypertensive patients beyond blood pressure elevation. Neural vasoconstriction in skeletal muscle has metabolic effects by impairing glucose delivery, which is a basis for insulin resistance and hyperinsulinemia. Within the heart a trophic effect of sympathetic activation on cardiac growth, contributing to the development of left ventricular hypertrophy, and an arrhythmogenic effect are also likely. Cardiac failure: The cardiac sympathetic nerves are preferentially stimulated in severe heart failure, with norepinephrine release from the failing heart at rest being increased as much as 50-fold, similar to the level seen in healthy people during near maximum exercise. This preferential activation of the cardiac sympathetic outflow contributes to arrhythmogenesis and possibly to progression of the heart failure, and has been directly linked to mortality; a high rate of spillover of noradrenaline from the heart is a strong, independent predictor of poor prognosis in severe cardiac failure. The mechanisms underlying sympathetic nervous stimulation are not entirely clear. Increased intracardiac diastolic pressure seems to be one peripheral signal, and increased forebrain norepinephrine turnover an important central mechanism. Following the demonstration of the beneficial effect of the beta-adrenergic blocker, carvedilol, and with second generation centrally acting sympathetic suppressants now under clinical investigation, elucidation of the abnormalities in central nervous control of sympathetic outflow in heart failure has become clinically relevant.
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PMID:Increased sympathetic nervous system activity and its therapeutic reduction in arterial hypertension, portal hypertension and heart failure. 985 71

About 80% of patients with chronic liver diseases such as cirrhosis are glucose intolerant and some 20-30% eventually develop frank diabetes mellitus. In a given individual it seems impossible to determine whether or not acquired liver diabetes or inherited non-insulin-dependent diabetes mellitus is present. The high prevalence, however, of impaired glucose tolerance and the finding that insulin sensitivity is reduced in nearly all cirrhotic patients before any impairment in glucose tolerance becomes manifest, make it likely that in the majority of patients the hepatic disease is the cause of the development of the hepatogenous diabetes. The insulin resistance resides in muscle and largely results from a defect in glycogen synthesis. Glucose intolerance ensues as a result of two abnormalities that occur simultaneously: insulin resistance of muscle and an inadequate response of the B-cell to appropriately secrete insulin to overcome the defect in insulin action. Diabetes mellitus in insulin-resistant cirrhotic patients develops as a result of a progressive impairment in insulin secretion together with the development of hepatic insulin resistance, leading to fasting hyperglycemia. Until recently, only little was known about the etiology of insulin resistance and impaired insulin secretion. However, most recent studies have shown that prolonged reduction of hyperinsulinemia in cirrhosis normalize insulin-mediated glucose uptake and glycogen synthesis in muscle. These results indicate that chronic hyperinsulinemia causes insulin resistance in cirrhosis and therefore plays a central role in the etiology of the hepatogenous diabetes.
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PMID:[Hepatogenic diabetes: pathophysiology, therapeutic options and prognosis]. 1044 11

Plasma branched-chain amino acid (BCAA) levels are decreased in patients with liver cirrhosis, owing to an increase in BCAA tissue uptake and/or catabolism and a decrease in BCAA production from proteins. Non-specific factors such as malnutrition worsen this picture. Studies of BCAA fluxes and protein turnover in cirrhotic patients have given conflicting results due to patient heterogeneity, differences in method and bias in the expression of results. In well compensated cirrhosis, muscle wasting is moderate and probably due more to decreased protein synthesis than to increased protein catabolism. Hyperinsulinemia has been suggested as the main cause of decreased BCAA levels, by increasing BCAA uptake in muscle and additionally in adipose tissue. However, as depletion of fat stores is frequent in cirrhosis, this effect is certainly quantitatively weak. Also, there is no correlation between state of hyperinsulinemia and decrease in BCAA levels. An effect of cytokines (IL1 and TNF) on muscle BCAA catabolism is a possibility. Until recently, the contribution of the liver to abnormal BCAA metabolism has been underestimated. In cirrhotic liver an increase in liver transamination of branched-chain keto acids (BCKAs) has been suggested and may result from inhibition of liver BCKA dehydrogenase. A modification of protein turnover in cirrhotic liver must be also considered. Lastly, the contribution of non-hepatocyte liver cells, which are activated in cirrhosis, remains to be assessed.
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PMID:Abnormalities in branched-chain amino acid metabolism in cirrhosis: influence of hormonal and nutritional factors and directions for future research. 1045 77

Cirrhosis is often associated with insulin resistance and glucose intolerance. We evaluated if these alterations are restored by liver transplantation (LT). Glucose tolerance (oral glucose tolerance test [OGTT]), peripheral insulin sensitivity (euglycemic insulin clamp technique), glucose oxidation (indirect calorimetry), nonoxidative glucose disposal, and insulin secretion (hyperglycemic clamp technique) were measured in 6 patients (Group 1) before and 6 months after LT, in 12 patients (Group 2) who underwent LT 6 to 30 months previously, and in 6 healthy individuals (controls). In Group 1, glucose tolerance and insulin sensitivity (3.24 +/- 0.37 mg/kg/min) were normalized after LT (8.6 +/- 0.77 mg/kg/min; P <.0001; P = not significant vs. controls). The improved insulin-mediated glucose uptake was the result of a normalization of nonoxidative glucose disposal. Fasting insulin and C-peptide decreased from 24.6 +/- 3.3 microU/mL and 4.37 +/- 0.46 ng/dL, respectively, to 12.7 +/- 1.9 microU/mL and 2.46 +/- 0.5 ng/dL (controls: 10.0 +/- 3 microU/mL and 1.45 +/- 0.34 ng/dL). The glucose-induced increase of insulin concentration, which was higher before LT, showed a significant reduction, although the first phase of beta-cell secretion remained significantly higher compared with that of controls. All these findings were also confirmed in Group 2. The present data indicate that LT normalizes glucose tolerance and insulin sensitivity in cirrhotic patients through an improvement of both hepatic glucose clearance and the peripheral glucose disposal. The latter effect may be the result of the correction of chronic hyperinsulinemia. An increased first-phase beta-cell insulin secretion in response to high glucose levels persists, suggesting that a memory of previous insulin resistance is maintained.
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PMID:Glucose intolerance and insulin resistance in cirrhosis are normalized after liver transplantation. 1046 70

Hepatic steatosis is common in non-insulin-dependent diabetes and can be associated with fibrosis and cirrhosis in a subset of individuals. Increased rates of fatty acid synthesis have been reported in livers from rodent models of diabetes and may contribute to the development of steatosis. Sterol regulatory element-binding proteins (SREBPs) are a family of regulated transcription factors that stimulate lipid synthesis in liver. In the current studies, we measured the content of SREBPs in livers from two mouse models of diabetes, obese ob/ob mice and transgenic aP2-SREBP-1c436 (aP2-SREBP-1c) mice that overexpress nuclear SREBP-1c only in adipose tissue. The aP2-SREBP-1c mice exhibit a syndrome that resembles congenital generalized lipodystrophy in humans. Both lines of mice develop hyperinsulinemia, hyperglycemia, and hepatic steatosis. Nuclear SREBP-1c protein levels were significantly elevated in livers from ob/ob and aP2-SREBP-1c mice compared with wild-type mice. Increased nuclear SREBP-1c protein was associated with elevated mRNA levels for known SREBP target genes involved in fatty acid biosynthesis, which led to significantly higher rates of hepatic fatty acid synthesis in vivo. These studies suggest that increased levels of nuclear SREBP-1c contribute to the elevated rates of hepatic fatty acid synthesis that leads to steatosis in diabetic mice.
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PMID:Increased levels of nuclear SREBP-1c associated with fatty livers in two mouse models of diabetes mellitus. 1051 88


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