Biomedical subjects
Publications and source records attributed to M J Rubinoff.
This review singles out several bacterial and parasitic causes of infectious diarrhea about which there have been interesting recent developments in pathogenesis, diagnosis, or treatment. Diarrheagenic mechanisms and infections by Escherichia coli, Salmonella, Giardia lamblia, Entamoeba histolytica, Cryptosporidia, and Isopora are discussed.
Clonidine, an alpha 2-adrenergic agonist, has been shown to be useful in the treatment of some patients with chronic diarrhea. Previous animal and human studies have suggested that clonidine alters both small bowel fluid absorption and total gut motility. We measured the effect of clonidine 0.3 mg on oro-cecal transit time, using the lactulose-breath hydrogen test. Intestinal transit time in six normal healthy male volunteers after administration of clonidine was 148 +/- 20 min, and was 90 +/- 7 min with a placebo (p less than 0.05). The average prolongation in transit time was 69.5%. We conclude that clonidine may markedly alter human small intestine transit time which explains, at least in part, the mechanism for this agent's antidiarrheal effect.
Calcium uptake by an endoplasmic reticulum-enriched membrane fraction isolated from rat small intestine was investigated using a rapid filtration technique. Calcium sequestration was stimulated by the presence of ATP and released by the calcium ionophore A23187. ATP stimulation of calcium uptake was dependent on the presence of magnesium, inhibited by vanadate, and refractory to calmodulin. Kinetic studies revealed a K0.5 for the ATP-stimulated uptake of 62.5 nM Ca and a Jmax of 1.4 nmol of Ca/mg protein X min. A high dietary calcium load stimulated maximal uptake by 80% with no change in affinity. The magnitude of maximal uptake and the high affinity of this transport system suggest that the endoplasmic reticulum may play a significant role in cytosolic calcium sequestration and that extracellular calcium leads to modulation of intracellular endoplasmic reticulum calcium buffering.