Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0024523 (malabsorption)
 7,319 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Juvenile rats fed a diet containing 1% lead acetate for 7 weeks, in addition to an impaired growth rate and renal function derangements, suffered malabsorption of glucose and certain amino acids, as assessed by an in vivo perfusion technique. The reduction in glucose absorption ranged between 10% and 31% when the carbohydrate was pumped in concentrations of 2-80 mM. This alteration was compatible with a noncompetitive type of transport inhibition. The intestinal absorption of glycine, lysine, and phenylalanine were, respectively, decreased 22, 18, and 15% when these amino acids were present at 1 mM levels. Sodium transport was severely reduced (57.6 +/- 17.9 (SEM) vs. 124.2 +/- 17.4 muEq/min-cm) and intestinal mucosa (Na+-K+)-ATPase was concomitantly lower in the lead-intoxicated rats (186.4 +/- 19.0 vs 268.4 +/- 29.8 nmol P/min-mg protein). However, this enzyme was not altered in liver and kidney. Furthermore, intestinal mucosa fructose-1,6-diphosphatase, succinic dehydrogenase, pyruvate kinase, and tryptophan hydroxylase were not different in experimental and control animals. These studies substantiate the presence of functional and biochemical abnormalities in the intestinal mucosa of young rats when fed substantial amounts of a soluble lead salt. It is, therefore, reasonable to accept the possibility that physiologic damage occurs in tissues directly subjected to high and persistent levels of a toxic agents, as it occurs in other organs, underscoring the parallelism between transport mechanisms at the renal and intestinal levels.
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PMID:Experimental lead poisoning and intestinal transport of glucose, amino acids, and sodium. 13 38

Involuntary weight loss or wasting indicative of severe protein energy malnutrition is a frequent complication of acquired immune deficiency syndrome (AIDS). Malnutrition, with its associated adverse effects on immunocompetence, may contribute to the progression of AIDS itself. Since death from wasting is ultimately related to the magnitude of tissue depletion, restoration of body cell mass may enhance survival. The mechanism of weight loss in AIDS has not been clearly elucidated. The etiology is likely to be multifactorial, the result of interactions between decreased caloric intake, malabsorption, and alterations in energy expenditure secondary to hormonal and/or metabolic abnormalities. Although weight loss is occasionally reversible with treatment of underlying infections and/or easily identifiable and reversible causes, the majority of patients are not this fortunate. Enteral and parenteral nutrition, which are expensive, cumbersome, and potentially morbid, have been suggested by some as therapeutic options. Megestrol acetate, a synthetic, orally active progestational agent, has been reported to stimulate appetite and weight gain. Data regarding the use of megestrol acetate for the treatment of cachexia related to human immunodeficiency virus (HIV) infection demonstrate convincingly its effectiveness in treating many patients with HIV-related anorexia and cachexia.
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PMID:HIV-related cachexia: potential mechanisms and treatment. 146 29

Two appetite stimulants, megestrol acetate and cyproheptadine were administered in a randomized trial to 14 patients who had no evidence of opportunistic infection or malabsorption but were wasted (had lost more than 5 kg body weight) as a result of human immunodeficiency virus (HIV) infection. Energy intakes were calculated from a 7 day weighed dietary record. Mean energy intakes per kilogramme body weight were similar in both treatment groups (greater than 34 kcal/kg) and were higher than that in well British males. Energy intakes increased by just over 500 kcal during both treatments, but fell to pretreatment levels after therapy. Patients in both treatment groups gained a moderate amount of weight. Megestrol acetate was associated with impotence in 4 patients. Insufficient calorie intake alone is not a common cause of wasting associated with HIV and the role of appetite stimulants is likely to be limited.
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PMID:Megestrol acetate vs cyproheptadine in the treatment of weight loss associated with HIV infection. 150 60

The purpose of this study was to determine whether energy from malabsorbed carbohydrate could be conserved through colonic fermentation in short bowel syndrome. Seven patients with short bowel anastomosed to the remaining colon and five patients with short bowel without a colon were selected from the home total parenteral nutrition (TPN) program. Six normal volunteers also were studied. After an overnight fast, subjects consumed a 50-g carbohydrate bread meal and were studied hourly over the next 6 h. Carbohydrate malabsorption, estimated by lactulose breath hydrogen testing, was 48 +/- 13% in short bowel patients. After the bread meal, breath hydrogen was higher in short bowels with colons (69 +/- 20 ppm) than in either short bowels without colons (11 +/- 7 ppm) or normal subjects (10 +/- 3 ppm) (p less than 0.01). Blood acetate levels also were higher in short bowels with colons than in those without colons, reaching a peak of 167 +/- 27 mumol/L at 4 h (p less than 0.05). We conclude that in patients with a short bowel and a colon, malabsorbed carbohydrate is fermented and there is a rise in blood acetate, suggesting that the colon has a role in salvaging malabsorbed carbohydrate as a source of energy through carbohydrate fermentation.
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PMID:Evidence for colonic conservation of malabsorbed carbohydrate in short bowel syndrome. 159 Mar 14

The effect of acarbose on hydrolysis of a pure starch meal was investigated in normal subjects and ileostomy patients by means of 13CO2 breath tests and blood glucose levels as parameters of absorption, and of H2 breath tests, serum acetate levels, and ileal loss of carbohydrate as parameters of malabsorption. Additional information on the effect of acarbose on alpha-amylase activity was obtained by in vitro experiments. Acarbose (200 and 400 mg) significantly delayed starch absorption. Serum acetate was found to be a less sensitive marker of malabsorption than breath H2 excretion. After intake of 50 g starch plus 400 mg acarbose, 23-71% of the starch load was lost in the ileostomy effluent, for a large part as starch. This suggests that acarbose considerably inhibits alpha-amylase, and not only brush-border enzymes. In vitro experiments confirm that an inhibition of two thirds of alpha-amylase activity can be expected from pharmacologically used doses of acarbose.
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PMID:Effects of acarbose on starch hydrolysis. Study in healthy subjects, ileostomy patients, and in vitro. 161 53

Carbohydrate malabsorption frequently results in an increased net production of organic acids by colonic microorganisms and an acidification of colonic contents. Colonic structure and function during and following mucosal exposure to acetate at various H ion concentrations was examined under both in vivo and in vitro conditions. An acetic acid dose and time-dependent injury of the surface epithelium sequentially resulted in (1) degeneration and extrusion of enterocytes and increased ion permeability (pH 5.0); (2) formation of subepithelial blisters and increased mucosal permeability to mannitol (pH 4.0), and (3) sloughing of surface epithelium and the abolition of active NaCl absorption (pH 3.0). Both acetate and lactate at pH 4.0 produced significantly greater injury than similarly acidified NaCl. Crypt cell structure and Cl secretory function were preserved, however, and migration of viable cells from adjacent crypts rapidly covered the denuded surface within 30-60 min of recovery. Normal structure and function were nearly restored in 2 hr. These results suggest that colonic mucosal injury is possible under conditions that may be present during carbohydrate malabsorption syndromes. They also provide evidence that the process of surface reepithelialization may be of central importance in the defense and repair of the colonic mucosa during such acid-induced injury.
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PMID:Short-chain fatty acids induce reversible injury of porcine colon. 191 71

Chronic consumption of substantial amounts of alcohol is not associated with the expected effect on body weight. Isocaloric substitution of carbohydrates by ethanol results in weight loss, and addition of ethanol to an otherwise normal diet does not produce the expected weight gain. This energy deficit cannot be explained by maldigestion or malabsorption but has been attributed to induction of the microsomal ethanol oxidizing system (a metabolic pathway that oxidizes ethanol without associated chemical energy production), increased sympathetic tone and associated thermogenesis, and/or enhanced ATP breakdown (with increased purine catabolism) secondary to the acetate produced from ethanol. All these hypotheses do not fully explain the lack of weight deficit when alcohol is consumed with a very-low-fat diet, which suggests that an alteration in the energy utilization derived from fat plays a major role, possibly through uncoupling of oxidation with phosphorylation in mitochondria damaged by chronic ethanol consumption.
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PMID:Perspectives: do alcohol calories count? 195 30

Home parenteral nutrition has prevented malnutrition in patients who cannot maintain adequate nutrition by enteral feedings alone. The risk of bone and mineral abnormalities in these patients is significant for several reasons. Pre-existing skeletal disease can occur from factors known to affect the population at large as well as from malnutrition, malabsorption, and corticosteroid use related to the underlying disease process. Long-term use of infused nutrients and potential toxins can further alter bone turnover. Hypercalciuria is frequently present during HPN, yet its etiology is poorly defined. Parenteral nutrition admixture concentrations of calcium, phosphorus, protein, sodium, and dextrose may all play a role. Any development of acidosis can certainly aggravate hypercalciuria, which may be an indirect marker of abnormal bone turnover. Although increased protein intake can promote the development of acidosis-induced calciuresis, infused phosphorus and acetate can help reduce calcium excretion. Parenteral nutrition contamination by aluminum can cause a spectrum of osteomalacic bone disease similar to aluminum-associated changes seen in renal failure patients. Even with recent attempts to remove aluminum from the parenteral admixture, low-turnover bone disease can still occur. At present, HPN-related bone disease is a poorly understood entity because of its multifaceted nature. Patients receiving long-term parenteral nutrition should be considered to have an increased risk for the development of metabolic bone disease. Early monitoring for and treatment of bone disease should be considered in all patients receiving HPN.
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PMID:Long-term parenteral nutrition and metabolic bone disease. 211 69

The endocrine abnormalities associated with acquired immunodeficiency syndrome (AIDS) are reviewed. These include adrenal insufficiency, hyporeninemic hypoaldosteronism, panhypopituitarism, hypogonadism, and alterations in thyroid function tests. AIDS-related infections or neoplasms may lead to hypercalcemia, whereas malabsorption may cause hypocalcemia. The possibility that AIDS-associated cachexia and hypertriglyceridemia may be caused by cachectin (tumor necrosis factor) is discussed, along with possible therapy for cachexia with megestrol acetate. Ketoconazole, sulfonamides, and pentamidine have specific, potentially deleterious metabolic effects when used in AIDS patients. Because treatment of endocrinological abnormalities of AIDS is often effective, improved diagnosis and appropriate therapy of these abnormalities will result in improved quality of life and, possibly, longer survival of patients with AIDS.
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PMID:Endocrinologic and metabolic manifestations of the acquired immunodeficiency syndrome. 224 1

Relationships between nutrition and infection are generally complex, bidirectional, and not perfectly worked out. Healthy people can adapt to simple decreases in intake or increases in expenditure. However, the imposition of infection with associated cytokines may impair such adaptations, resulting in wasting of lean tissue. In human immunodeficiency virus (HIV) infection, nutritional abnormalities are common. Lean body mass depletion is associated temporally with death in a subset of acquired immune deficiency syndrome (AIDS) patients. Weakness, fatigue, and anorexia are important symptomatic complaints affecting quality of life. Pathophysiologic mechanisms remain speculative, although there is reason to suspect four theoretic factors: decreased intake, malabsorption, hypermetabolism, and altered metabolism. More than one disturbance may be necessary for clinical wasting to develop; ie, a primary abnormality plus a failure of homeostatic adaptation. Excess cytokine production also may be involved, but this is uncertain. Therapeutics remain empiric in the absence of known mechanisms. Current options are restricted to diet adjustments or supplements, treatment of underlying diseases (where possible), and rarely, parenteral alimentation. Promising investigational possibilities include an appetite stimulant (megestrol acetate) and therapies to oppose cytokine production or actions, but definitive beneficial effects on nutritional status, subjective performance, disease activity, or survival have not yet been demonstrated. Advances in clinical therapeutics await an improved understanding of pathophysiologic mechanisms and carefully designed clinical trials testing proposed interventions.
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PMID:Current approach to the treatment of human immunodeficiency virus-associated weight loss: pathophysiologic considerations and emerging management strategies. 225 24


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