Ferritin intestinal absorption.

Ferritin as a source of iron was consiered. A good iron absorption rate appears in normal rats with an in vivo absorption technique. The same absorption appears in iron-deficient animals. The iron stored in intestinal wall is lower in anemic rats than in normal ones, suggesting a higher draw of iron from lumen to blood.     

Studies on mammalian intestinal peroxidase.

A peroxidase, purified from rat small intestine to apparent homogeneity as judged by polyacrylamide-gel electrophoresis, exhibited an absorbance ratio (A412/A280) of 0.783. Its Mr (44000 +/- 1000) and spectral properties were similar to those of the pig intestinal enzyme. The velocity constant for the reaction between rat intestinal peroxidase and hydrogen peroxide was found to be 1.8 x 10(7) M-1 . s-1. Benzhydroxamic acid inhibited the peroxidative oxidation of guaiacol by intestinal peroxidase from both species but the concentration required to cause half-inhibition of the enzyme from the rat was higher by one order of magnitude than for the pig enzyme. The amino acid composition of highly-purified pig intestinal peroxidase showed a relative abundance of basic amino acids (lysine and arginine) and was similar to that of lactoperoxidase, but not that of myeloperoxidase. The initial ten amino acid residues of this enzyme (the first reported partial sequence for a mammalian peroxidase) were also determined.     

Blastocystis hominis--a potential intestinal pathogen.

The parasite Blastocystis hominis has been found in 10% to 18% of stool specimens submitted to microbiology laboratories. Controversy exists as to whether this organism can cause illness in humans. We have reviewed the records of 65 symptomatic patients with B hominis in their stool. We conclude that B hominis is a potential pathogen that may or may not require drug therapy depending on the overall clinical circumstances, the severity of symptoms, and the presence of other pathogenic organisms.     

Small intestinal transit in diabetics.

Small intestinal transit was assessed in diabetic patients and healthy controls by measuring the breath hydrogen appearance time after the ingestion of lactulose. Transit in diabetics with autonomic neuropathy was significantly slower than in diabetics without neuropathy and controls. Delayed transit is probably due to vagal denervation. These slower transit times would allow bacteria to proliferate, which might explain why some diabetics have diarrhoea. The test cannot be used in patients with bacteria in the small bowel because these may metabolise lactulose and release hydrogen prematurely.     

The intestinal epithelial stem cell.

This article considers the role of the adult epithelial stem cell, with particular reference to the intestinal epithelial stem cell. Although the potential of adult stem cells has been revealed in a number of recent publications, the organization and control of the stem cell hierarchy in epithelial tissues is still not fully understood. The intestinal epithelium is an excellent model in which to study such hierarchies, having a distinctive polarity and high rate of cell proliferation and migration. Studies on the small intestinal crypt provide insight into the characteristics of the stem cells in normal and regenerating circumstances and demonstrate why a thorough understanding of these cells is an essential pre-requisite for stem cell based therapeutic approaches.     

Morphological adaptations of intestinal helminths.

Nematodes, trematodes, cestodes, and acanthocephalans each have become adapted in different ways to the microenvironment of the vertebrate intestine. Life in this specialized habitat affords parasites a reliable source of nutrients, a relatively homeostatic environment, and protection from predators but, in exchange for these advantages, presents the special challenges of exposure to digestive enzymes, normal peristalsis, and host immune response to infection. Logically, the surface of the parasite should be the first part of the organism to encounter such challenges, and, for this reason, any response or reaction by the parasite is expected to be manifested at the parasite-host interface. Morphological adaptations of intestinal helminths to their microenvironment include modification of the tegumental surface that affords protection and increases absorptive surface area, development of specialized attachment organs, and, in some cases, complete loss of their own internal digestive system. Representative examples of such adaptations by helminths are described and discussed in terms of the parasite's nutritional requirements, site selection, and host specificity, and the possibility is suggested that some helminths may have adapted in ways that exploit host defensive mechanisms for their own benefit.     

Regulation of intestinal glucose transport.

The small intestine is capable of adapting nutrient transport in response to numerous stimuli. This review examines several possible mechanisms involved in intestinal adaptation. In some cases, the enhancement of transport is nonspecific, that is, the absorption of many nutrients is affected. Usually, increased transport capacity in these instances can be attributed to an increase in intestinal surface area. Alternatively, some conditions induce specific regulation at the level of the enterocyte that affects the transport of a particular nutrient. Since the absorption of glucose from the intestine is so well characterized, it serves as a useful model for this type of intestinal adaptation. Four potential sites for the specific regulation of glucose transport have been described, and each is implicated in different situations. First, mechanisms at the brush-border membrane of the enterocyte are believed to be involved in the upregulation of glucose transport that occurs in streptozotocin-induced diabetes mellitus and alterations in dietary carbohydrate levels. Also, factors that increase the sodium gradient across the enterocyte may increase the rate of glucose transport. It has been suggested that an increase in activity of the basolaterally located Na(+)-K+ ATPase could be responsible for this phenomena. The rapid increase in glucose uptake seen in hyperglycemia seems to be mediated by an increase in both the number and activity of glucose carriers located at the basolateral membrane. More recently, it was demonstrated that mechanisms at the basolateral membrane also play a role in the chronic increase in glucose transport observed when dietary carbohydrate levels are increased. Finally, alterations in tight-junction permeability enhance glucose absorption from the small intestine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies on intestinal adenosine triphosphatases. I. Application of a semiautomated method to the rat intestinal brush borders.

Elaboration of a semiautomated kinetic test on LKB 8600 apparatus for ATPase is described, using the PK-LDH system. As optimal ionic conditions 3 mmol-1 - minus 1 potassium chloride and 100 mmol-1 - minus 1 sodium chloride are proposed for measurement of (Na+-K+)-ATPase activities of rat intestinal brush borders. NH+4 can substitute for K+. The coefficients of variation of the method are 2.4% for Mg2+-ATPase and 4.9% for (Na+-K+)-ATPase determinations.