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

A gas-solid chromatographic system using tandem silica gel and molecular sieve columns is described for the measurement of hydrogen, carbon dioxide, oxygen, and nitrogen in samples of respiratory gases. This system has a detection limit of 2 ppm of hydrogen in a 1 ml sample and can measure 120 ppm H2 and 5% CO2 with relative standard deviations of 1.3% and 1.7%, respectively. Improved sample storage and withdrawal techniques are described that give reproducible values for up to 6 weeks after collection. Finally we show that normalization of breath hydrogen values to an alveolar concentration, using the observed carbon dioxide concentrations, substantially reduces the range and variance of apparent H2 concentrations in human subjects. Normalization eliminates the need for rebreathing or end-expiratory collection techniques and substantially increases the reliability and clinical utility of hydrogen breath measurements in noninvasive tests of carbohydrate malabsorption.
 ...
PMID:Improved gas chromatographic quantitation of breath hydrogen by normalization to respiratory carbon dioxide. 50 Dec 2

The quantity of lactose not absorbed by 4 normal and 6 lactase-deficient subjects was determined by three indirect methods which involved: (1) measurement of pulmonary hydrogen (H2) excretion, (2) pulmonary (14)CO2 excretion, and (3) stool (14)C excretion, after ingestion of 12.5 g of 1-(14)C-lactose and 4 g of polyethylene glycol (PEG). Results were compared with absorption determined directly from the (14)C:PEG ratio of multiple terminal ileal aspirates. The fraction of lactose not absorbed determined by ileal aspiration ranged from 0 to 8% in normals and 42 to 75% in mild-intolerant subjects. Whereas all three indirect methods were useful in qualitatively separating normal from deficient subjects, the quantity of lactose absorbed as determined by H2 excretion correlated most closely with ileal measurements (r = 0.94). Pulmonary (14)CO2 excretion for 24 hr after (14)C-lactose ingestion did not distinguish normal (17 +/- 4% (SEM) of ingested (14)C per 24 hr) from lactase-deficient subjects (21.1 +/- 3%). Likewise, stool (14)C:PEG ratios grossly underestimated malabsorption with less than one-quarter of the nonabsorbed (14)C appearing in the stool. This study suggests that individual differences in susceptibility to diarrhea after milk ingestion by lactase-deficient subjects may be due to differences in the quantity of lactose not absorbed and/or differences in the rate of bacterial metabolism of lactose in the colon. Analysis of ileal fluid collected during passage of the lactose meal indicated that about two-thirds of the osmotic load delivered to the colon consists of endogenous electrolytes. Thus the water load delivered to the colon is about 3 times that calculated to be osmotically held by the nonabsorbed sugar.
 ...
PMID:Quantitative measurement of lactose absorption. 126 65

An automatic electronically operated end-expiratory air sampler has been developed for use in small infants. Upon expiration, which is detected by a hot-wire sensor, a small portion of the end-expiratory air is automatically collected into a syringe mounted on a syringe driver. The sampler obtained 87% of the end-expiratory air sample. Additionally, highly reproducible and consistent results were obtained for the respiratory gases (O2, N2, CO2). The sampler has been applied for studying breath hydrogen excretion to detect lactose malabsorption. It may also be applicable to study other expiratory gases in infants.
 ...
PMID:Automatic end-expiratory air sampling device for breath hydrogen test in infants. 167 Jul 35

We measured breath hydrogen excretion in 103 neonates from birth to as late as 2 months of age. The patients weighed less than 2000 g at birth and were part of a study of hydrogen excretion as a screening test for necrotizing enterocolitis. Hydrogen excretion in parts per million was normalized for the quality of the expired air by dividing by the Pco2 of the gas sample The rise in the H2/CO2 ratio was influenced by gestational age, energy intake, and antibiotic usage but not by the daily frequency of feeding. The mean +/- SD peak H2/CO2 ratio was 5.1 +/- 3.6 ppm per millimeter of mercury and occurred at 16.0 +/- 11.0 days of age. The age at which the peak H2/CO2 occurred varied with gestational age. Patients born between 23 and 28 weeks gestational age (n = 34) were 22.9 +/- 13.1 days of age when they experienced their peak H2/CO2 ratio, whereas those born between 29 and 34 weeks gestational age (n = 62) were 12.2 +/- 7.5 days of age. The age at which the peak H2/CO2 ratio occurred did not differ between these two groups when corrected for the age at which oral intake exceeded 420 kJ/kg per day. These results suggest that premature neonates require experience with ingesting more than 420 kJ/kg per day before bacteria and carbohydrates are present in large enough quantities to permit measurable hydrogen production. This information will be useful in future studies of premature gut development and physiology and in studying pathologic processes in which malabsorption may play a role.
 ...
PMID:Breath hydrogen excretion in the premature neonate. 210 30

Total parenteral nutrition (TPN), specifically amino acid infusions, has been shown to increase the ventilatory response to inhaled CO2. The hypothesis tested was that morphine sulfate (known to depress ventilatory CO2 responsiveness) would diminish the augmented ventilatory CO2 response in patients receiving TPN. The influence of morphine on hyperoxic hypercapnic ventilatory response (assessed by the Read rebreathing technique) was therefore examined in four otherwise healthy subjects who were receiving TPN at home for long-standing nutritional support secondary to malabsorption syndrome (short-bowel syndrome), and in a control group of four healthy subjects who were not receiving TPN. The slope and intercept of the CO2 response was estimated by linear regression on the relationship between ventilation (VE) and end-tidal PCO2 (PETCO2). Administration of morphine in the non-TPN group elicited the expected decrease in the VE-PETCO2 slope. In contrast, morphine administration was associated with an increase in the VE-PETCO2 slope in the TPN group. While this investigation does not provide a direct indication of the mechanisms underlying the augmenting action of morphine on the ventilatory response to CO2 in subjects receiving TPN, it does suggest that patients on TPN who demonstrate no impairment of ventilatory control may be given normal doses of morphine sulphate (ie, as for pain control or preoperative medication) with no increased concern for an adverse ventilatory outcome.
 ...
PMID:The effect of total parenteral nutrition and morphine on ventilation. 212 45

The use of medium-chain triglycerides (MCT) in lipid malabsorption and lipoproteinlipase deficiency is well established. It is known from experiments in animals and humans that after parenteral administration MCT are rapidly hydrolyzed by lipoprotein lipase in plasma. The liberated medium-chain fatty acids are taken up independently of carnitine by mitochondria and oxidized to CO2 in extrahepatic tissues more rapidly than long-chain fatty acids. Medium-chain fatty acids are ketogenic, and consequently both medium-chain fatty acids and ketones are carnitine-independent energy carriers for different tissues. By simultaneously infusing glucose the risk of ketoacidosis can be minimizes. MCT in parenteral nutrition is a substrate which provides high-density energy without problems regarding osmolality or renal losses and with less interference to the reticulohistiocytes of the immune system. On the basis of these metabolic and functional properties MCT represent a valuable additional energy source in total parenteral nutrition.
 ...
PMID:[Medium-chain triglycerides--useful energy carriers in parenteral nutrition]. 249 24

Previous studies have provided evidence that an anaerobic bacterium, which degrades dietary oxalate to CO2 and formate, is present in colonic contents of a number of herbivorous species, laboratory rodents and humans. The present study examines the possibility that these bacteria degrade significant amounts of oxalate and can influence colonic oxalate absorption. Guinea pigs adapted to a diet containing 2% sodium oxalate or fed a normal diet were challenged with 67, 135, 170 or 200 mg of sodium oxalate containing 0.5 microCi of [14C]oxalate, which was injected into the cecum. Adapted animals excreted approximately 2% of the 14C in the urine, regardless of the dose, whereas unadapted animals excreted significantly higher amounts in the urine at the two lower doses and died at the two higher doses. Conversely, antibiotic treatment of adapted guinea pigs reduced the ability of their cecal flora to degrade oxalate, and a correspondingly greater percentage of an injected oxalate load was excreted in the urine. Oxalate degradation rates in cecal fluid were depressed by the secondary bile salt deoxycholate, and in vitro studies with pure isolates of guinea pig and human strains of oxalate degraders confirmed that these bacteria were highly sensitive to low concentrations of deoxycholate. Results indicate that these bacteria may be important in preventing excess absorption of oxalate and raise the possibility that the hyperoxaluria associated with bile salt malabsorption of ileal disease in part may be due to suppression of these bacteria by the bile salts.
 ...
PMID:Intestinal oxalate-degrading bacteria reduce oxalate absorption and toxicity in guinea pigs. 337 43

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.
 ...
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.
 ...
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.
 ...
PMID:Effect of ventilation on breath hydrogen measurements. 392 Mar 35


1 2 3 Next >>