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Query: UMLS:C0021843 (bowel obstruction)
 9,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although once considered completely devoid of complications, it is now recognised that the misuse or inappropriate use of nitrous oxide (N2O) often results in adverse side effects. Hypoxia, particularly the entity 'diffusion hypoxia', can occur with the administration of inadequate amounts of oxygen during or immediately after a N2O anaesthetic. N2O will diffuse into air-containing cavities within the body faster than nitrogen diffuses out. This results in a temporary increase in either the pressure and/or volume of the cavity depending upon the distensibility of its walls. The magnitude of the effect is proportional to the blood supply of the cavity, the concentration of N2O inhaled and the length of time the patient is exposed to N2O. Significant morbidity or even death can result from this phenomenon. A property unique to N2O is its ability to oxidise and inactivate the vitamin B12 components of certain enzymes in both animals and man. One such enzyme, methionine synthetase is essential for normal DNA production. Animal and human studies have demonstrated that the haematological, immune, neurological and reproductive systems are each affected. These adverse effects of N2O can occur after both acute (surgical) or long term (occupational) exposure to the gas. Because of its effects on the pressure and volume characteristics of air-containing spaces, N2O should not be used for patients with bowel obstruction, pneumothorax, middle ear and sinus disease, and following cerebral air-contrast studies. Many anaesthesiologists feel that use of N2O should be restricted during the first two trimesters of pregnancy because of its effects on DNA production and the experimental and epidemiological evidence that N2O causes undesirable reproductive outcomes. Since N2O affects white blood cell production and function, it has been recommended that N2O not be administered to immunosuppressed patients or to patients requiring multiple general anaesthetics. Many anaesthesiologists believe that the potential dangers of N2O are so great that it should no longer be used at all for routine clinical anaesthesia. However, the continued use of N2O remains a controversial topic since, at present, a suitable substitute gas is not available.
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PMID:Adverse effects of nitrous oxide. 353 24

The effects of elevated intraluminal hydrostatic pressure on the active absorption of the amino acid selenium 75 L-methionine has been analyzed in the normal and obstructed small intestine. An intestinal loop of defined position and length was included in a recircling perfusion system from which the elimination rate of the radiolabeled amino acid was measured. Preset pressure levels within the system were maintained by a servo-controlled unit, which added or subtracted volume to keep the pressure constant. The rate of amino acid elimination increased when the nonobstructed loop was subjected to a pressure of 10 cm H2O but decreased when exposed to 20cm H2O. Using a loop of intestine subjected to 48 hours of obstruction, amino acid elimination was greatly retarded compared with that of the nonobstructed loop. By increasing the intraluminal pressure to 10 and 20 cm H2O, the elimination rate increased, equalling that of the nonobstructed gut. The results suggest that intestinal obstruction per se decreases active absorption secondary to impaired intestinal viability. Moderately increased intraluminal pressure adds a driving force to L-methionine absorption, the mechanism of which is obscure.
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PMID:Effects of intraluminal hydrostatic pressure on L-methionine absorption in the obstructed small intestine of the rat. 395 59

Technological advances in genetics have made feasible and affordable large studies to identify genetic variants that cause or modify a trait. Genetic studies have been carried out to assess variants in candidate genes, as well as polymorphisms throughout the genome, for their associations with heritable clinical outcomes of cystic fibrosis (CF), such as lung disease, meconium ileus, and CF-related diabetes. The candidate gene approach has identified some predicted relationships, while genome-wide surveys have identified several genes that would not have been obvious disease-modifying candidates, such as a methionine sulfoxide transferase gene that influences intestinal obstruction, or a region on chromosome 11 proximate to genes encoding a transcription factor and an apoptosis controller that associates with lung function. These unforeseen associations thus provide novel insight into disease pathophysiology, as well as suggesting new therapeutic strategies for CF.
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PMID:The influence of genetics on cystic fibrosis phenotypes. 2320 80