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

With the development of sophisticated physiological and biochemical analytical techniques and intestinal gas analysis, both direct, e.g. Argon washout and indirect, e.g. breath measurements of H2 and labelled CO2 derived from intestinal metabolism, greater understanding of the influence of diet on intestinal gas production and the development of diagnostic procedures for identifying causes of malabsorption have evolved. The use of stable isotopes and different probe molecules will see even greater developments in this field in the years ahead.
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PMID:Intestinal gas formation and the use of breath measurements to monitor the influence of diet and disease. 354 58

The regulatory functions of anions in colonic absorption of sodium are unknown. Absorption of sodium ions was assessed with chloride, butyrate, nitrite, sulphate and oxalate anions in segments of proximal/distal colon and in defunctioned colon. Efficiency of sodium absorption was related to availability of CO2 in mucosal cells: CO2 availability was enhanced (P less than 0.01) by sodium nitrite or diminished (P less than 0.01) in defunctioned colon. Sodium nitrite stimulated absorption of sodium in the distal colon where bicarbonate secretion predominated and n-butyrate stimulated absorption of sodium in the proximal colon where hydrogen ion secretion predominated. Sodium absorption was very significantly diminished (P less than 0.01) in defunctioned colon. Results indicate that sodium absorption in the colon is both a double anion exchange system as well as cation/anion co-transport. Anions act differently on sodium absorption along the length of the colon and prolonged lack of anions plays a part in sodium malabsorption of the defunctioned colon.
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PMID:Anion control of sodium absorption in the colon. 371 59

Measurement of hydrogen (H2) in expired air by interval sampling after oral administration of carbohydrate detects sugar malabsorption. Standard breath H2 tests require comparison of H2 concentrations in expired air samples obtained immediately before and after delivery of a test substrate. Comparison of interval samples assumes that minute ventilation (VE) remains constant unless H2 is independent of VE. Because healthy individuals have variable VE, we determined how H2 is influenced by changes in VE. H2 concentration was studied at different ventilatory rates in eight healthy adults. It varied inversely with VE in all subjects. We also compared the effect of changes in VE on the relationship between H2 and carbon dioxide (CO2) concentrations in expired air samples. At constant VE, the relationship between H2 and CO2 was linear (r = 0.95, P less than 0.001). As VE changed, the relationship between H2 and CO2 became nonlinear. Changes in VE altered methane concentrations in expired air samples from two subjects in a manner comparable to the effect on H2. These results demonstrate that breath H2 concentrations vary with ventilatory rate. Under conditions where frequent changes in VE are likely, independent measures for ensuring constant VE over sampling times are necessary. Use of CO2 as an internal standard to normalize H2 values to an alveolar concentration is appropriate only under conditions of constant VE.
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PMID:Effect of ventilation on breath hydrogen measurements. 392 Mar 35

There is evidence for both humans and rats that malnutrition frequently occurs when ethanol is chronically ingested. Small bowel 14C-labelled glucose absorption was measured with an ex vivo system in which the small bowel of the rat was surgically removed and then arterially perfused with an artificial medium. Glucose absorption for a control group of seven rats was 248 +/- 8 microM/min/gm dry weight of small bowel (mean +/- SEM). This was significantly greater than the value 112 +/- 12 microM/min/gm dry weight (P less than 0.005) for a group of five rats in which a competitive inhibitor of glucose absorption, phlorizin (0.2 mM), was added to the bowel lumen. In the presence of 3% ethanol within the gut lumen of five rats, glucose absorption was also reduced (to 131 +/- 12 microM/min/gm dry weight) compared to absorption in the control group (P less than 0.005). The calculated amount of glucose absorbed was corrected for metabolism to lactate and carbon dioxide. We conclude that both phlorizin and ethanol inhibit glucose absorption in the isolated and perfused small bowel of rats and that probably at least part of the malnutrition in ethanol-fed rats is due to glucose malabsorption.
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PMID:Ethanol inhibition of glucose absorption in isolated, perfused small bowel of rats. 641 May 24

The 14C-triolein breath test was evaluated as a screening test for fat malabsorption in 50 consecutive patients. After the ingestion of a 30-g fat meal containing 5 microCi 14C-triolein, the breath excretion of 14CO2 was measured at hourly intervals for 6 h and compared with a 3-day faecal excretion of fat. Nineteen patients had steatorrhoea and 31 patients normal fat excretion. The maximum specific activity of CO2 in the breath provided the best means of distinguishing between the two groups, with no false-negative values and nine false-positive values (29%). Our findings confirm that the 14C-triolein breath test is sensitive and has sufficient specificity for screening fat malabsorption, especially among outpatients. If a normal 14C-triolein breath test is obtained, it seems unnecessary to perform measurements of excretion of faecal fat.
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PMID:14C-triolein breath test as a rapid and convenient screening test for fat malabsorption. 667 78

Short-chain fatty acids (SCFAs) constitute the major solute fraction of normal stool water and are responsible for the diarrhea associated with carbohydrate (CHO) malabsorption. Although SCFA absorption from the human small bowel has been reported previously, the fate of SCFAs in the colon--their major site of production--was investigated in the present study. The colon of normal volunteers was perfused with neutral, isotonic solutions containing SCFA, 0-90 mM. Propionate was studied in detail with limited observations on acetate and n-butyrate. SCFA absorption was concentration-dependent; back diffusion of metabolic products, ketone bodies, was quantitatively insignificant. The transport process was accompanied by increased Na, K, and water absorption, by luminal alkalinization due to bicarbonate accumulation, and by a fall in lumen PCO2. The results are consistent with the existence of two mechanisms for colonic SCFA absorption: first, nonionic diffusion of protonated SCFA involving consumption of luminal CO2; this process accounts for about 60% of total SCFA absorption; and second, cellular uptake by ionic diffusion of the Na or K salt of the SCFA.
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PMID:Absorption of short-chain fatty acids by the colon. 676 37

The use of a few microcuries of 14C labelled molecules with very short biological half-life for breath-tests gives no more body irradiation than 10 minutes' exposure to the sun. Yet it provides the gastroenterologist with accurate information. Detection and identification of fat malabsorption are easy when 3 labelled lipids are used. Glycine 1 14C cholate administered orally offers a simple, rapid and effective screening technique for the detection of increased bile salt deconjugation and may provide a valuable diagnostic supplement in the study of steatorrhea after ileal resection, bypass or bacterial overgrowth. The clearance of labelled aminopyrine can be decreased in hepatocellular dysfunction or increased in some alcoholic patients or in patients receiving phenobarbitone. Tracer doses of labelled ethanol were used to study the metabolism of ethanol by the liver in alcoholic patients. Chronic ingestion of alcohol stimulates the activity of microsomal drug-metabolising enzymes in both non-cirrhotic and cirrhotic patients; this response is lost in acute liver damage and in chronic alcoholic disease with severe hepatic dysfunction. The CO2-labelled breath-tests are non-invasive, effective and inexpensive. The forthcoming replacement of 14C by non-radioactive 13C or briefly radioactive 11C will render these tests even more attractive.
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PMID:[Labelled CO2 breath-tests in gastroenterology (author's transl)]. 679

Carbon isotope breath tests are often interpreted assuming a constant endogenous production of CO2 (some including calculations assuming a specific production of 9 mmol CO2/body weight per hour). We have evaluated the endogenous-CO2 production following ingestion of caloric meals varying with the range of most currently available carbon isotope breath tests. On three separate test days, fasting basal CO2 production was 8.08 +/- 0.55, 8.00 +/- 0.47, and 8.23 +/- 0.48 mmol/kg-hr (mean +/- s.e.m.), with a range 6-11 mmol/kg-hr. Administration of zero and 100 kcal led to no significant change from the basal CO2 production. In contrast, administration of 200 kcal or more led to significant elevation of endogenous CO2 production both by normal subjects and by subjects with nutrient malabsorption. This phenomenon could influence interpretation of some nonfasting isotopic CO2 breath tests; it deserves further evaluation.
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PMID:Alteration of CO2 production during nonfasting isotopic CO2 breath tests: concise communication. 679 20

Breath tests rely on the measurement of gases produced in the intestine, absorbed, and expired in the breath. Carbohydrates, such as lactose and sucrose, can be administered in physiologic doses; if malabsorbed, they will be metabolized to hydrogen by colonic bacteria. Since hydrogen is not produced by human metabolic reactions, a rise in breath hydrogen, as measured by gas chromatography, is evidence of carbohydrate malabsorption. Likewise, a rise in breath hydrogen marks the transit time of nonabsorbable carbohydrates such as lactulose through the small intestine into the colon. Simple end-expiratory interval collection into nonsiliconized vacutainer tubes has made these noninvasive tests quite convenient to perform, but various problems, including changes in stool pH, intestinal motility, or metabolic rate, may influence results. Another group of breath tests uses substrates labeled with radioactive or stable isotopes of carbon. Labeled fat substrates such as trioctanoin, tripalmitin, and triolein do not produce the expected rise in labeled breath CO2 if there is fat malabsorption. Bile acid malabsorption and small intestinal bacterial overgrowth can be measured with labeled cholylglycine or cholyltaurine. Labeled drugs such as aminopyrine, methacetin, and phenacetin can be used as an indication of drug metabolism and liver function. Radioactive substrates have been used to trace metabolic pathways and can be measured by scintillation counters. The availability of nonradioactive stable isotopes has made these ideal for use in children and pregnant women, but the cost of substrates and the mass spectrometers to measure them has so far limited their use to research centers. It is hoped that new techniques of processing and measurement will allow further realization of the exciting potential breath analysis has in a growing list of clinical applications.
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PMID:Breath tests: principles, problems, and promise. 718 Jun 96

The use of 14CO2 breath tests and fecal analyses for the detection and quantitation of intestinal malabsorption has been extensively documented in adult subjects. The use of stable isotopes has extended the range of breath test applications to include pediatric and obstetric subjects. Here we report a fecal 13C analysis that can be used in conjunction with 13CO2 breath tests. Twenty-four-hour fecal samples were collected before and after the administration of a labeled substrate. The samples were homogenized and combusted to CO2, and the 13C abundance was determined by high-precision, differential isotope ratio mass spectrometry. The isotopic variation between successive 24 hr fecal samples was 0.6 0/00 (0.0006 atom percent). This variation limited the sensitivity of the fecal analysis to 13 mumol of 13C label per mold of fecal carbon. Simultaneous cholyglycine 13CO2 breath tests and fecal assays were performed in five children. One child with bacterial overgrowth had an abnormal breath test and a normal fecal test. Of three children with ileal dysfunction, only one had an abnormal breath test, whereas the fecal test was abnormal in all three, Both the breath test and fecal test were abnormal for a child who had undergone an ileal resection. Both tests were normal for a child with ulcerative colitis.
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PMID:Fecal 13C analysis for the detection and quantitation of intestinal malabsorption. Limits of detection and application to disorders of intestinal cholylglycine metabolism. 746 74


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