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

Children with human immunodeficiency virus (HIV) infection have a higher prevalence of intestinal malabsorption. Anemia is also a common feature in these children. The aims of this work were (a) to establish the prevalence of iron deficiency in HIV-infected children, (b) to test the hypothesis that iron deficiency is related to intestinal malabsorption, (c) to see whether it may contribute to anemia, and (d) to evaluate the sensitivity of oral iron load in the investigation of intestinal function. To accomplish these goals, 71 HIV-infected symptomatic children were enrolled. Iron serum values were determined before and after oral load with ferrous sulfate. The correlation between basal and post-load iron levels was evaluated by linear regression. Xylose level after oral load, fecal fat, and fecal alpha 1-antitrypsin concentration were also determined. Iron deficiency was detected in 48% of patients, and it was significantly associated with intestinal iron malabsorption. Sugar malabsorption, steatorrhea, and fecal protein loss were detected in 26, 36, and 17% of patients, respectively. Low hemoglobin levels were detected in 66% of patients. The majority of children with iron deficiency also had anemia. Preliminary data showed that oral iron administration was sufficient for raising hemoglobin in children with normal iron absorption, whereas parenteral administration was required in those with iron malabsorption. We conclude that (a) iron deficiency is a major feature of pediatric HIV infection, (b) it is related to intestinal malabsorption, and (c) it contributes to anemia. Finally, oral iron load is a sensitive test for investigating intestinal function.
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PMID:Iron deficiency and intestinal malabsorption in HIV disease. 873 98

Sugar reaching the colon because of intestinal maldigestion or malabsorption may be fermented to acetate and other short-chain fatty acids, resulting in stimulation of colonic water absorption and cell proliferation. To explore this phenomenon in more detail, we have developed a stable isotope model for estimating the fraction of colon-derived glucose or lactose that is fermented to acetate, propionate and butyrate. In an initial application of the model, [d3]-acetate and either [1-(13)C]-glucose or [D-1-(13)C]-lactose were infused into the cecum or colon of piglets, and plateau plasma acetate enrichment was monitored in the carotid artery. In acutely anesthetized piglets, the fractions of glucose and lactose fermented to acetate were 17.0 and 20.0%, respectively. In a chronically catheterized piglet, fermentation was higher (34.2%). When conducted in chronically catheterized animals or via a colostomy or ileostomy in infants, this model may be used to determine how age, previous surgery or antibiotic therapy affects the efficiency of colonic assimilation of carbohydrate.
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PMID:Stable isotope model for assessing production of short chain fatty acids from colon-derived sugar: application in pigs. 900 76

The incidence of intestinal nutrient malabsorption increases with age. Therefore, an important question is whether there are age-related changes in intestinal nutrient absorption which may contribute to a decline in absorptive capacity. Sugar and amino acid transport per mg intestine generally decreases with age. The proximate mechanism underlying this age-related decrease in transport activity is a decrease in number of transporters per mg. This reduction in transporter number can be caused by age-related changes in cell proliferation rates which, in turn, can alter the ratio of absorptive to nonabsorptive cells. The age-related change in proliferation rates typically increases intestinal mass. There seems to be no age-related changes in the steady state levels of transporter mRNA. Aging also modestly impairs the ability of intestinal nutrient transport systems to adapt to changes in dietary conditions. Caloric restriction is the only procedure known to consistently increase the lifespan of mammals. Chronic caloric restriction markedly enhances intestinal nutrient transport per mg without affecting intestinal mass. Since body weight decreases with caloric restriction, there is a dramatic increase in intestinal absorptive capacity normalized to body weight. This suggests that an increase in intestinal nutrient absorption may be a critical adaptation to caloric restriction. There is a need to perform in vivo transport studies during senescence, to distinguish between acute and chronic effects of caloric restriction, and to identify hormones that may mediate aging and caloric restriction effects on intestinal nutrient transport.
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PMID:Effect of aging and caloric restriction on intestinal sugar and amino acid transport. 934 90

In South African blacks colorectal cancers are uncommon and adenomatous polyps are rare, despite major changes in diet and lifestyle in the large urbanized community of Soweto (population over 3 million). Factors favouring adenomas formation are changes in bowel function. Thus, stool weights, defaecation frequencies, oro-caecal transit times and whole-gut transit times in Sowetans approximate those of western populations. Moreover a measure of westernization of diet has occurred, the salient feature being a greatly reduced fibre intake (14 g daily). Factors thought to inhibit adenoma formation are physiological malabsorption of maize, lactose and fructose. Sucrose activity is significantly lowered compared with whites. With regard to diet, fat consumption is well below that of western societies. There are differences in colon cell proliferation, faecal short chain fatty acids, faecal pH and colonic microflora compared with white groups. Equivocal factors that may be involved in adenoma formation are time trends and genetic background. In the context of the above it is apparent that in South African blacks inhibiting factors outweigh promotive factors in adenoma formation.
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PMID:Rarity of colorectal adenomas in the African black population. 988 82

Sugars normally are absorbed in the small intestine. When carbohydrates are malabsorbed, the osmotic load produced by the high amount of low molecular weight sugars and partially digested starches in the small intestine can cause symptoms of intestinal distention, rapid peristalsis, and diarrhea. Colonic bacteria normally metabolize proximally malabsorbed dietary carbohydrate through fermentation to small fatty acids and gases (ie, hydrogen, methane, and carbon dioxide). When present in large amounts, the malabsorbed sugars and starches can be excreted in the stool. Sugar intolerance is the presence of abdominal symptoms related to the proximal or distal malabsorption of dietary carbohydrates. The symptoms consist of meal-related abdominal cramps and distention, increased flatulence, borborygmus, and diarrhea. Infants and young children with carbohydrate malabsorption show more intense symptoms than adults; the passage of undigested carbohydrates through the colon is more rapid and is associated with detectable carbohydrates in copious watery acid stools. Dehydration often follows feeding of the offending sugar. In this review we present the clinical and current molecular aspects of disaccharidase digestion.
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PMID:Disaccharide digestion: clinical and molecular aspects. 1652 88

Sugar malabsorption in the bowel can lead to bloating, cramps, diarrhea and other symptoms of irritable bowel syndrome as well as affecting absorption of other nutrients. The hydrogen breath test is now a well established noninvasive test for assessing malabsorption of sugars in the small intestine. However, there are patients who can suffer from the same spectrum of malabsorption issues but who produce little or no hydrogen, instead producing relatively large amounts of methane. These patients will avoid detection with the traditional breath test for malabsorption based on hydrogen detection. Likewise the hydrogen breath test is an established method for small intestinal bacterial overgrowth (SIBO) diagnoses. Therefore, a number of false negatives would be expected for patients who solely produce methane. Usually patients produce either hydrogen or methane, and only rarely there are significant co-producers, as typically the methane is produced at the expense of hydrogen by microbial conversion of carbon dioxide. Various studies show that methanogens occur in about a third of all adult humans; therefore, there is significant potential for malabsorbers to remain undiagnosed if a simple hydrogen breath test is used. As an example, the hydrogen-based lactose malabsorption test is considered to result in about 5-15% false negatives mainly due to methane production. Until recently methane measurements were more in the domain of research laboratories, unlike hydrogen analyses which can now be undertaken at a relatively low cost mainly due to the invention of reliable electrochemical hydrogen sensors. More recently, simpler lower cost instrumentation has become commercially available which can directly measure both hydrogen and methane simultaneously on human breath. This makes more widespread clinical testing a realistic possibility. The production of small amounts of hydrogen and/or methane does not normally produce symptoms, whereas the production of higher levels can lead to a wide range of symptoms ranging from functional disorders of the bowel to low level depression. It is possible that excess methane levels may have more health consequences than excess hydrogen levels. This review describes the health consequences of methane production in humans and animals including a summary of the state of the art in detection methods. In conclusion, the combined measurement of hydrogen and methane should offer considerable improvement in the diagnosis of malabsorption syndromes and SIBO when compared with a single hydrogen breath test.
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PMID:The importance of methane breath testing: a review. 2347 Aug 80


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