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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review explains and surveys very recent findings and experimental results concerning molecular pathology and genetics of overweight and obesity and also evaluates their relevance for the actual treatment of obesity at present. Most of these studies were done on inbred obese mice or rats and it is yet unknown to what extent the results do apply to human overweight. Nevertheless these studies led to the discovery of a new hormone--OB-protein or leptin--produced by adipocytes of animals. It does not only increase satiety by influencing feeding centers and decrease body weight but it also interferes with several peripheral metabolic functions. Mutations of leptin expression or expression of leptin receptors as observed in animals are, however, very rare in humans. In obese individuals (and animals) there is a yet unexplained resistance to the effects of leptin which interferes with successful therapeutic use of leptin in human obesity. Various other recently discovered transmitters modifying feeding habits may, however, become targets of future drugs making dietary weight loss and its maintenance more acceptable and successful. At present obese people and patients have to rely, however, on traditional methods of weight loss though these are known to yield poor results over prolonged periods of time. Orlistat, a recently introduced drug results in malabsorption of fat from the gut by inhibiting lipases. Though it is not based on recent insights to regulation of body weight it is promising primarily for educating patients to reduce their nutritional fat intake.
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PMID:[New knowledge about obesity--news for obese patients?]. 987 83

Obesity is a frequent cause of insulin resistance and poses a major risk for diabetes. Abnormal fat deposition within skeletal muscle has been identified as a mechanism of obesity-associated insulin resistance. We tested the hypothesis that dietary lipid deprivation may selectively deplete intramyocellular lipids, thereby reversing insulin resistance. Whole-body insulin sensitivity (by the insulin clamp technique), intramyocellular lipids (by quantitative histochemistry on quadriceps muscle biopsies), muscle insulin action (as the expression of Glut4 glucose transporters), and postprandial lipemia were measured in 20 morbidly obese patients (BMI = 49 +/- 8 [mean +/- SD] kg x m(-2)) and 7 nonobese control subjects. Patients were restudied 6 months later after biliopancreatic diversion (BPD; n = 8), an operation that induces predominant lipid malabsorption, or hypocaloric diet (n = 9). At 6 months, BPD had caused the loss of 33 +/- 10 kg through lipid malabsorption (documented by a flat postprandial triglyceride profile). Despite an attained BMI still in the obese range (39 +/- 8 kg x m(-2)), insulin resistance (23 +/- 3 micromol/min per kg of fat-free mass; P < 0.001 vs. 53 +/- 13 of control subjects) was fully reversed (52 +/- 11 micromol/min per kg of fat-free mass; NS versus control subjects). In parallel with this change, intramyocellular-but not perivascular or interfibrillar-lipid accumulation decreased (1.63 +/- 1.06 to 0.22 +/- 0.44 score units; P < 0.01; NS vs. 0.07 +/- 0.19 of control subjects), Glut4 expression was restored, and circulating leptin concentrations were normalized. In the diet group, a weight loss of 14 +/- 12 kg was accompanied by very modest changes in insulin sensitivity and intramyocellular lipid contents. We conclude that lipid deprivation selectively depletes intramyocellular lipid stores and induces a normal metabolic state (in terms of insulin-mediated whole-body glucose disposal, intracellular insulin signaling, and circulating leptin levels) despite a persistent excess of total body fat mass.
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PMID:Insulin resistance in morbid obesity: reversal with intramyocellular fat depletion. 1175 34

Biliopancreatic diversion (BPD), a gastrectomy with a long ROUX en Y reconstruction, reduces intestinal absorption by delaying the mixing of food and biliopancreatic juices, and induces persistent weight loss in obese patients unresponsive to medical treatments. The levels of leptin (a plasma protein synthesised in human adipose tissue) are increased in obese subjects and significantly decrease after a major weight loss. A possible role of thyroid hormones in regulating adipose tissue metabolism in humans has been proposed, but it is not universally accepted and the relationship between thyroid function and leptin levels has not yet been clearly defined. We studied serum leptin, TSH, fT4 and fT3 levels in 38 obese patients (26 women and 12 men), before and 12 months after BPD. There was a significant post-surgical decrease in BMI and circulating leptin levels in all of the treated subjects, but thyroid function did not seem to be affected (TSH and fT4 levels were unchanged). However, fT3 levels significantly decreased after surgery. Our data suggest that BPD-induced malabsorption has no direct effect on thyroid function, but possibly reduces the peripheral conversion of thyroxine to T3. Further studies seem to be necessary to clarify the clinical relevance of these observations.
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PMID:Evaluation of serum leptin levels and thyroid function in morbidly obese patients treated with bariatric surgery. 1288 Jan 85

Caloric imbalance, particularly in critical periods of growth and development, is often the underlying cause of growth abnormalities. Serum levels of leptin are elevated in obesity and are low in malnutrition and malabsorption. The aim of the present study was to determine whether leptin integrates energy levels and growth in vivo, as shown previously in our ex vivo experiments, even in the presence of caloric restriction. In the first part of the study, mice were divided into three groups. Two groups were fed ad libitum and received leptin or vehicle only, and the third group was pair-fed with the group injected with leptin to dissociate leptin's effect on growth from its effect on food consumption. Mice given leptin had a significantly greater tibial length than untreated pair-fed animals and a similar tibial length as control mice fed ad libitum despite their lower weight. In addition, leptin significantly increased the overall size of the epiphyseal growth plate by 11%. On immunohistochemistry and in situ hybridization studies, leptin stimulated both the proliferation and differentiation of tibial growth plate chondrocytes without affecting the overall organization of the plate. There was also a marked increase in the expression and level of IGF-IR. In the second part of the study, two groups of mice were fed only 60% of their normal chow; one was injected with leptin, and the other was injected with vehicle alone. Caloric deprivation by itself reduced serum levels of IGF-I by 70% and the length of the tibia by 5%. Leptin treatment corrected the fasting-induced growth deficiency, but further reduced the level of serum IGF-I. These results indicate that leptin stimulates growth even in the presence of caloric restriction independently of peripheral IGF-I.
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PMID:Leptin reverses the inhibitory effect of caloric restriction on longitudinal growth. 1452 12

Dietary modification is useful in both type 1 and type 2 diabetes. Glucose levels after a meal are largely determined by carbohydrate intake. Decreased intake of simple carbohydrates and increased fiber consumption lower postprandial glucose. Obesity has become epidemic in the United States and has dramatically increased the incidence of type 2 diabetes by augmenting insulin resistance. Dietary treatment of obesity has been frustrating. Success will require education in using foods with high fiber contents, low glycemic indexes, and low saturated fat levels. The use of natural foods must be supplemented by the use of semisynthetic foods with desirable properties. The educational efforts required are substantial and must be recognized by third-party reimbursement agencies. Operative procedures to decrease intake or reduce the absorption of food are being used with increasing frequency. Bariatric surgery is often successful in inducing a substantial loss of weight; however, this success must be balanced against the complications of surgery, which can be considerable. The pharmacologic approaches to treatment of obesity have focused primarily on anorexigenic agents. Several polypeptides that induce satiety are currently under study, including leptin and glucagon-like peptide-1 (GLP-1). Orlistat has been used to induce the malabsorption of fat to reduce caloric ingestion. Of the currently used oral hypoglycemics, metformin and the disaccharidase inhibitors have the best tendency to promote weight loss. There is active research on the uncoupling proteins that induce thermogenesis and promote the dissipation of calories. The beta-3 agonists act through the uncoupling proteins. The thiazolidinediones tend to promote weight gain through the PPAR gene locus. Agents that antagonize this effect could induce weight loss. The future will undoubtedly bring us drugs that are effective in causing weight loss. The advent of drugs to successfully combat obesity will substantially improve public health.
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PMID:Advances in diabetes for the millennium: nutritional therapy of type 2 diabetes. 1564 15

Plasma leptin and growth hormone (GH) profile and pulsatility have been studied in morbidly obese subjects before and 14 months after bilio-pancreatic diversion (BPD), a bariatric technique producing massive lipid malabsorption. The maximum leptin diurnal variation (acrophase) decreased (10.27+/-1.70 vs. 22.60+/-2.79 ng x ml(-1); P=0.001), while its pulsatility index (PI) increased (1.084+/-0.005 vs. 1.050+/-0.004 ng x ml(-1) x min(-1); P=0.02) after BPD. Plasma GH acrophase increased (P=0.0001) from 0.91+/-0.20 to 4.58+/-0.80 microg x l(-1) x min(-1) after BPD as well as GH PI (1.70+/-0.13 vs. 1.20+/-0.04 microg x l(-1) x min(-1); P=0.024). Whole-body glucose uptake (M), assessed by euglycemic-hyperinsulinemic clamp, almost doubled after BPD (from 0.274+/-0.022 to 0.573+/-0.027 mmol x kgFFM(-1) x min(-1); P<0.0001), while 24 h lipid oxidation was significantly (P<0.0001) reduced (131.94+/-35.58 vs. 44.56+/-15.10 g). However, the average lipid oxidation was 97.2+/-3.1% (P<0.01) of the metabolizable lipid intake after the bariatric operation, while it was 69.2+/-8.5% before. After the operation, skeletal muscle ACC2 mRNA decreased (P<0.0001) from 452.82+/-76.35 to 182.45+/-40.69% of cyclophilin mRNA as did the malonyl-CoA (from 0.28+/-0.02 to 0.16+/-0.01 nmol x g(-1); P<0.0001). Leptin changes negatively correlated with M changes (R2=0.69, P<0.001). In a stepwise regression (R2=0.87, P=0.0055), only changes in 24 h free fatty acids (B=0.105+/-0.018, P=0.002) and glucose/insulin ratio (B=0.247+/-0.081, P=0.029) were the best predictors of leptin variations. In conclusion, the reversion of insulin resistance after BPD might allow reversal of leptin resistance, restoration of leptin pulsatility, and consequent inhibition of ACC2 mRNA expression, translating to a reduced synthesis of malonyl-CoA, which, in turn, results in increased fatty acid oxidation. Finally, since leptin inhibits GH secretion, a reduction of circulating leptin levels might have produced an increase in GH secretion, as observed in our series.
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PMID:Leptin pulsatility in formerly obese women. 1595 44

Gastrointestinal (GI) problems at high altitude are commonplace. The manifestations differ considerably in short-term visitors, long-term residents and native highlanders. Ethnic food habits and social norms also play a role in causing GI dysfuntion. Symptoms like nausea and vomiting are common manifestations of acute mountain sickness and are seen in 81.4% short-term visitors like mountaineers. Anorexia is almost universal and has a mutifactorial causation including effect of hormones like leptin and cholecystokinin and also due to hypoxia itself. Dyspepsia and flatulence are other common symptoms. Diarrhoea, often related to poor hygiene and sanitation is also frequently seen especially among the short-term visitors. Peptic ulceration and upper gastro-intestinal haemorrhage are reported to be common in native highlanders in the' Peruvian Andes (9.6/10000 population per year) and also from Ladakh in India. A hig h incidence o f gastriccarcinoma is also reported, especially from Bolivia (138.2 cases per 10000 population per year). Megacolon and sigmoid volvulus are common lower GI disorders at high altitude. The latter accounted for 79% of all intestinal obstructions at a Bolivian hospital. Thrombosis of the portosystemic vascultature and splenic hematomas has been reported from India. Malnutrition is multifactorial and mainly due to hypoxia. Fat malabsorption is probably significant only at altitudes > 5000m. Neonatal hyperbilirubinemia was found to be four times more common in babies born at high altitude in Colorado than at sea level. Gall stones disease is common in Peruvian highlands. A high seroprevalence of antibodies to H pylori (95%) has been found in Ladakh but its correlation to the prevalence of upper gastro-intestinal disease has not been proven.
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PMID:Gastrointestinal problems at high altitude. 1754 91

Patients with anorexia nervosa (AN) may develop multiple endocrine abnormalities, including amenorrhea, hyperactivity of the hypothalamus-pituitary-adrenal axis, hypothyroidism and particular changes in the activity of the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. Exaggerated GH secretion and reduced IGF-I levels are usually found in AN, as well as in conditions of malnutrition and malabsorption, insulin-dependent diabetes mellitus, liver cirrhosis and catabolic states. In AN, GH hypersecretion at least partially reflects malnutrition-induced peripheral GH resistance, which leads to reduced IGF-I synthesis and release; this implies an impairment of the negative IGF-I feedback action on GH secretion. On the other hand, primary alterations in the neural control of GH secretion cannot be ruled out. The neuroendocrine alterations include enhanced somatotroph responsiveness to growth hormone releasing hormone (GHRH) and impaired GH response to most central nervous system-mediated stimuli. Particular resistance to cholinergic manipulation has also been demonstrated, thus suggesting a somewhat specific alteration in the somatostatin (SS)-mediated cholinergic influence on GH secretion. Moreover, paradoxical GH responses to glucose load, thyrotropin releasing hormone (TRH) and luteinizing hormone releasing hormone (LHRH) have also been reported. The effect of reduced leptin levels on GH hypersecretion in AN is still unclear, but ghrelin (the gastric hormone that is a natural ligand of the GH secretagogue receptor and strongly stimulates somatotroph secretion) is thought to play a major role. Regardless of the supposed central and peripheral alterations, it has to be emphasised that the activity of the GH/IGF-I axis in AN is generally restored by nutritional and stable weight gain. It therefore reflects an impaired nutritional state and cannot be considered a primary hallmark of the disease.
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PMID:GH/IGF-I axis in anorexia nervosa. 1764 63

Celiac disease (CD) is a chronic immune-mediated gluten-dependent enteropathy induced by ingestion of gluten-containing products, characterized by intestinal malabsorption and subtotal or total atrophy of intestinal villi, which improves after gluten-free diet (GFD). Untreated patients affected by the classic form of CD are at high risk of malnutrition, but an impairment of nutritional status is frequently reported also in patients with the subclinical form of the disease. Strict adherence to a GFD greatly improves nutritional status, inducing an increase in fat and bone compartments, but does not completely normalize body composition. A lack of improvement in nutritional status may identify incomplete adherence to GFD treatment. Evidence has shown lower body weights and lower fat mass and fat-free mass contents in CD patients. Untreated CD patients oxidize more carbohydrates as energy substrate compared to treated subjects. In addition, circulating ghrelin concentration was reduced after GFD treatment as a possible consequence of body composition improvement, while leptin did not correlate with the changes in body composition and substrate oxidation in patients with CD. A significant correlation was reported between ghrelin and the degree of severity of intestinal mucosal lesions. CD patients might show an alteration in lipid metabolism, i.e. low serum total and high- density lipoprotein-cholesterol as a consequence of lipid malabsorption and decreased intake. In conclusion, weight loss and nutritional deficiencies are relevant clinical features in CD. Thus, an early and accurate evaluation of nutritional status and energy metabolism represents a fundamental tool in the management of CD patients.
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PMID:Metabolic and nutritional features in adult celiac patients. 1843 Oct 62

Ghrelin and leptin are newly discovered, still very mysterious, hormones. Beside the energy balance, they regulate endocrine and immune system, growth and maturate processes. Fluctuations of both hormones concentration are observed in many gastrointestinal tract diseases. In this publication is presented current knowledge about meaning ghrelin and leptin in choosen diseases, like malabsorption syndromes, inflammatory diseases and tumors of gastrointestinal tract.
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PMID:[Meaning of ghrelin and leptin in gastrointestinal tract diseases]. 2036 31


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