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At least 1,639 records · Page 91Linked to original sources
PubMed1998

Intestinal absorption and enterohepatic circulation of folic acid: effect of ethanol.

This study sought to determine the intestinal in vivo absorption of folic acid by the whole intestine, and the appearance of this compound in bile in control and ethanol-fed rats. Intestinal folic acid absorption in rats with the bile duct cannulated decreased in ethanol-fed rats with respect to control rats. This difference was significant at 1 and 2.5 microM concentrations of folic acid. This result is in contrast with previous work in our laboratory on rats with intact bile ducts, where ethanol-fed rats had an increase in folic acid absorption. The results obtained in the present work suggest an impaired enterohepatic recycling of folic acid in ethanol-fed rats.

Animal Feed↗
PubMed2005

Stable isotopes in studies of intestinal absorption, exchangeable pools and mineral status: the example of magnesium.

Magnesium (Mg) is a biologically essential mineral and Mg deficiency is known to lead to severe biochemical and symptomatic disorders. Radioactive isotopes and, more recently, stable isotopes have been used as research tools to determine intestinal Mg absorption in humans and animals under different nutritional and physiological conditions. Mg isotopes are given orally or orally plus intravenously and analysed in faeces and/or in plasma and urine in order to calculate intestinal Mg absorption and possibly endogenous Mg excretion. Mg isotopes have been used to assess exchangeable pools of Mg under nutritional and physiopathological conditions. Mg isotopes are given intravenously and are analysed in plasma and urine to calculate the size and half-life of the various Mg exchangeable pools. More recently, in vitro isotopic tests have been developed to study the need of cells for Mg in different nutritional and genetic conditions. Whole blood is incubated with Mg isotopes and isotopic blood cell enrichment is measured, which reflects the avidity of cells for Mg and thus its initial status. This paper is a report on the use of stable Mg isotopes and their advantages in these different fields of Mg absorption and metabolism. The studies available have clearly demonstrated that stable isotopes provide a useful research tool for determining intestinal Mg absorption, and represent a precious research tool for the study of Mg metabolism and the assessment of Mg status.

Animals↗
PubMed1996

Ion microscopic imaging of calcium during 1,25-dihydroxyvitamin D-mediated intestinal absorption.

A combination of ion microscopic and conventional radionuclide techniques was employed to investigate the temporal-spatial dynamics of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]-stimulated intestinal calcium (Ca) absorption. At varying times following the administration of a single intravenous dose of 1,25(OH)2D3 to vitamin D-deficient chicks, transepithelial transport and tissue retention of Ca were quantitated in vivo, using the ligated duodenal loop technique and 47Ca as the tracer. The localization of Ca in the intestinal tissue during absorption was monitored by ion microscopy, using the stable Ca isotope, 44Ca, as the absorbed species. There was little transepithelial absorption of Ca in the vitamin D-deficient animals despite a substantial tissue accumulation of luminally derived Ca, the latter localizing predominantly in the brush border region of the enterocyte, as shown by the 44Ca-ion microscopic images. The early (30 min-1 h) response to 1,25(OH)2D3 was an increased tissue uptake of luminal 47Ca, which also primarily associated with the brush border region, again as shown by ion microscopy. At 2-4 h after the 1,25(OH)2D3 dose, there was a progressive redistribution of Ca from the brush border region throughout the cytoplasm and into the lamina propria. At 8-16 h, 47Ca absorption was maximal and 44Ca was sparsely distributed in the intestinal tissue. 47Ca absorption gradually declined and reached pre-dose levels by 72 h. At this time, tissue 44Ca was again largely limited to the brush border region. These results provide support for the multiple actions of 1,25(OH)2D3 on the intestinal Ca absorption process. The ion microscopic images provided unique information on the specific time-dependent changes in the tissue localization of Ca during the process of its intestinal absorption as affected by 1,25(OH)2D3.

Animals↗
PubMed1992

Tissues and organs as indicators of intestinal absorption of minerals and trace elements, evaluated in rats.

Tissue and organ deposition and blood parameters were evaluated as indices of mineral and trace element absorption in rats. The absorption of elements was quantified in relation to nitrogen retention, i.e., considering the weight gain and new tissue synthesis. A rapeseed meal diet was supplied with three levels of calcium, two levels of zinc, and two levels of copper in a factorial design. In general, an increase in dietary mineral content increased the relative absorption, which in turn, increased the tissue deposition progressively. Striated muscle, however, did not respond to either an increased calcium or zinc supply. Furthermore, an increased calcium absorption caused a depression of the fractional phosphorus and magnesium content of femur bones. The copper content of the kidneys and the heart muscle was directly proportional to the amount of absorbed zinc and iron, respectively. The iron content of tissue was, in general, inversely proportional to zinc absorption and showed a tendency to be directly proportional to copper absorption. The zinc level in tissues was, in a similar way, inversely correlated to measured calcium absorption. In conclusion, interactions between elements do not only affect the intestinal element absorption, but also the distribution of already absorbed elements in tissues and organs.

Animals↗
PubMed1989

Ultrastructural features of the intestinal absorption of mouse mammary tumor virus in newborn BALB/cfRIII mice.

The retrovirus mouse mammary tumor virus is present in mouse strains with a high incidence of mammary tumors as a causative agent. It is produced mainly in the mammary glands of sexually mature females and is milk-transmitted to newborns. The fate of the mouse mammary tumor virus is almost unknown. Where it enters, how it is distributed, and where it remains latent, remain unresolved problems. This study tries to answer the first of these questions. Viruses are for the most part digested in the stomach. Very few well-preserved B particles, i.e., the infective particles, are allowed to enter through a process of endocytosis, mainly in the newborn-type epithelial cells. These are epithelial cells with a very rich absorptive apparatus, characteristic of newborn rodents. The adult-type absorptive cells and the M cells of the Peyer's patches might be partly involved.

Animals↗