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

The analysis of respiratory hydrogen and methane was estimated as a useful index of intestinal fermentation of undigestible carbohydrate. A simultaneous and precious analysis of these gases as well as carbon dioxide was studied. A gas-impermeable multi-laminated film bag metalized by aluminum vapor was fitted to use as a storage bag; its impermeability was verified by measuring the residual rate of hydrogen after 3 months' storage. Hydrogen, methane and carbon dioxide of the breath gas even at 1 ppm could be determined simultaneously by using a gas-solid chromatography installed with a photoionization detector and active carbon column. To observe the genesis of hydrogen and methane after carbohydrate ingestion, pectin, a typical water-soluble dietary fiber, was fed to healthy volunteers. Increasing excretion of pulmonary hydrogen or methane showed the sign of intestinal fermentation as the results of carbohydrate malabsorption.
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PMID:Simultaneous determination of hydrogen, methane and carbon dioxide of breath using gas-solid chromatography. 162 82

The influence of pasta cooking time on starch digestion and plasma glucose and insulin responses was studied in 12 healthy subjects. During 3 consecutive days, one of three pasta test meals (50 g starch) cooked for 11, 16.5, and 22 min was served to each volunteer in a random order. Hydrogen and methane breath excretion was measured after pasta ingestion; plasma responses were compared with those of an equivalent oral glucose-tolerance test. No significant differences were found between cooking times and plasma indices, orocecal transit time, or incremental hydrogen excretion (delta peak hydrogen). With one exception, pasta meals that were completely absorbed were ingested by methane producers. Postprandial delta peak hydrogen was significantly lower in methane than in nonmethane producers (p less than 0.02). These results point to a lack of influence of cooking time on nutritional characteristics of pasta and suggest that starch malabsorption determined by breath-hydrogen-test criteria may be underestimated in methane producers.
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PMID:Pasta cooking time: influence on starch digestion and plasma glucose and insulin responses in healthy subjects. 217 90

Adult (primary) lactose malabsorption is practically universal in Africans of Bantu and San ('Bushmen') stock. Recent environmental changes, especially in rural areas, have exacerbated rates of malnutrition in hospital patients belonging to these groups. In order to assess the advisability of using milk as a nutritional supplement for such patients, the tolerance and absorption of 350 ml boluses of whole milk (containing 17 g lactose) was measured in 110 malnourished hospitalized patients in Namibia and South Africa belonging to Bantu (ie, Zulus, Hereros, and Kavangos) and San (ie, Bushmen) populations and compared with 22 healthy Westernized controls. Mild symptoms of intolerance were noted in about 10 per cent of Bantus and 20 per cent of Bushmen in comparison to 33 per cent of lactose-malabsorbing controls consuming Westernized diets and reported rates of 48 and 80 per cent in American population studies. The average increase in breath hydrogen excretion of 20 parts per million was also lower than the value of 34 parts per million in controls. Fasting breath methane concentrations were high in between 60-84 per cent of the groups of patients, but the level was not significantly affected by milk ingestion. Despite the combination of hypolactasia and malnutrition, 350 ml drinks of milk were well tolerated by African patients. Thus, milk should form an appropriate nutritional supplement for Africans hospitalized in rural areas.
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PMID:Milk tolerance and the malnourished African. 240 Dec 80

Dietary starch delivery to the colon and excretion in stools and the ability of unabsorbed carbohydrates to promote hydrogen and methane release in breath were evaluated in 6 volunteers during two 8-day periods on starch diets of 100 and 300 g, respectively. Significantly less starch was recovered from the terminal ileum by aspiration per 24 h during the low-starch period (4.1 +/- 0.3 vs. 9.5 +/- 1.1 g, mean +/- SEM, p less than 0.01). Unabsorbed glucose tended to rise during the high-starch period (2.7 +/- 0.8 vs. 1.1 +/- 0.3 g). Fecal outputs of starch, glucose, volatile fatty acids, and lactic acid were not significantly different during the two periods. Daily breath hydrogen excretion was unchanged (181.2 +/- 22.7 vs. 193.7 +/- 19.8 ml for the low- and high-starch periods, respectively), whereas breath methane excretion increased markedly in the three methane producers during the high-starch period (217.2 +/- 80.9 vs. 32.4 +/- 7.3 ml). Starch malabsorption in the healthy small intestine was moderate even with a high-starch diet and less than that previously estimated by indirect methods. Unabsorbed starch catabolism by the colonic flora does not seem to explain most of the breath hydrogen excretion.
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PMID:Starch malabsorption and breath gas excretion in healthy humans consuming low- and high-starch diets. 339 66

Methane production was studied in 28 cystic fibrosis patients aged 3-16 years and in 290 healthy children. The percentages of methane producers in the cystic fibrosis and control groups were 60.7 and 20.6%, respectively. In the patient group there was no difference between methane producers and nonproducers with respect to the degree of malabsorption or the administration of pancreatic supplements or antibiotics. We hypothesize that the high proportion of methane producers in cystic fibrosis patients may be associated with the presence of specific substrate(s) (glycoprotein?) in their intestinal contents. Changes of the intestinal microenvironment may favor the development of a methanogenic flora.
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PMID:Methane production in patients with cystic fibrosis. 343 Feb 46

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

Lactose malabsorption, by the breath hydrogen test, and lactose intolerance (presence of symptoms) were studied in twenty healthy Italian subjects after intake of 12.5, 25 and 50 g lactose, whole milk and low-lactose milk. A rise in respiratory concentration of hydrogen (greater than 20 ppm) (malabsorption) was found in fifteen subjects after 50 g lactose, in thirteen after 25 g and in seven after 12.5 g. Symptoms generally occurred in subjects presenting a rise in respiratory hydrogen excretion, but such a rise was often observed without symptoms. Thirteen subjects presented symptoms after 50 g lactose, but only three after 25 g and one after 12.5 g. Whole milk (500 ml) gave a lower incidence of lactose malabsorption than 25 g lactose (7/20 versus 13/20, P less than 0.05) and more subjects developed symptoms (7/20 versus 3/20, NS). Low-lactose milk produced no malabsorbers and one intolerant. Breath methane was detected constantly in seven subjects and in three on some of the days of observation. Respiratory methane excretion generally appeared to be unrelated to lactose ingestion.
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PMID:Respiratory excretion of hydrogen and methane in Italian subjects after ingestion of lactose and milk. 640 50

Hydrogen and methane in human breath derive entirely from bacterial fermentation in the intestinal lumen. The sources of substrates utilized for these reactions have not been completely determined. Basal excretion of both gases occurs in the fasted state, while malabsorbed carbohydrate commonly results in increased hydrogen but not methane production. Using an in vitro fecal incubation system, we have studied hydrogen and methane production from glycoproteins of endogenous as well as dietary origin. All glycoproteins tested yielded hydrogen when incubated with fecal homogenates. Mean hydrogen production from substrates containing less than 3% sugar (human serum albumin, bovine serum albumin, and alpha-casein) averaged 2.2 +/- 0.9% of hydrogen production from equivalent amounts of glucose, while carbohydrate-rich mucin yielded 46.0 +/- 6.7% of hydrogen production from glucose. Glycoproteins of intermediate carbohydrate content, including transferrin and egg white, yielded intermediate values. Methane production from glycoproteins was optimal from carbohydrate-poor protein substrates in fecal homogenates which accumulated hydrogen and became rapidly acidic when incubated with pure carbohydrate. In contrast, methane production was comparable for essentially sugar-free proteins, glycoproteins, and glucose when hydrogen did not accumulate and neutral pH was maintained. We conclude that glycoproteins are substrates for hydrogen and methane production by colonic bacteria from healthy adults. In individuals with bacterial overgrowth syndromes and in protein-losing enteropathy, bacterial catabolism of endogenous glycoproteins may cause increased basal hydrogen and methane excretion. These findings also raise the possibility that measurement of hydrogen or methane after oral administration of dietary glycoproteins may be useful in detection of protein malabsorption.
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PMID:Glycoproteins as substrates for production of hydrogen and methane by colonic bacterial flora. 708 16

To evaluate the possibility that measurement of breath methane (CH4) enhances the accuracy of breath hydrogen (H2) testing to diagnose carbohydrate malabsorption, breath CH4 concentration of healthy subjects was studied. Fasting breath CH4 concentration measured three times over a 30-minute period in 44 CH4-producing volunteers ranged from 5 to 120 ppm. Fluctuation of breath CH4 excretion exceeded 100% increase over fasting in 1 of 9 subjects who ingested a nonabsorbable, carbohydrate-free solution. Out of 13 subjects who had a false negative breath H2 response to lactulose, 11 had a CH4 percentage increase greater than 100%. In 11 of 32 lactose-intolerant patients with a negative breath H2 test, CH4 percentage increase after lactose challenge was greater than 100%. These data suggested that in methanogenic individuals, breath CH4 measurement might enhance the accuracy of H2 breath testing in detecting carbohydrate malabsorption.
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PMID:The possible role of breath methane measurement in detecting carbohydrate malabsorption. 796 27

To evaluate the relationship between colonic methane production and carbohydrate malabsorption, we measured end-expiratory methane levels in 70 normal and 40 lactose-intolerant children. Time-dependent excretion of hydrogen and methane was determined every 30 min for 120 min following a fasting oral lactose challenge (2 g/kg). Mean breath hydrogen levels in normals (lactose-tolerant) equaled 3.7 parts per million (ppm) throughout the study, but increased to > 10 ppm by 60 min and remained elevated in lactose-intolerant subjects. Breath methane in normal children averaged 1.6 ppm from 0 to 120 min. In contrast, CH4 excretion by lactose-intolerant children averaged 5.1 ppm at 90 min; and, by 120 min levels increased significantly compared with control. Breath methane levels in lactose-intolerant subjects following a lactose load continued to increase, however, despite the coingestion of exogenous lactase in amounts calculated to result in complete hydrolysis of the disaccharide. These data demonstrate that lactase-deficient children manifest significant increases in breath methane excretion following lactose ingestion and that enhanced methane production may be a consequence of several factors, including altered fecal pH and increased methanogenic substrates provided by colonic lactose fermentation. Further studies are required to determine the clinical significance of elevated methane production in lactose intolerance.
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PMID:Respiratory methane excretion in children with lactose intolerance. 842 45


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