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Biomedical subjects

N E Craft

Publications and source records attributed to N E Craft.

20 records · Page 2Linked to original sources
PubMed1983

Zinc, iron, and copper absorption in the streptozotocin-diabetic rat.

Altered tissue levels of trace metals have been reported in streptozotocin-diabetic (STZ) rats. To determine whether increased hepatic and renal levels of Cu and Zn were associated with enhanced intestinal absorption, trace metal absorption was studied in control (C) and STZ rats using dietary balance and in situ ligated-loop techniques. The apparent daily absorption of dietary Zn and Cu per 100 g body wt was threefold higher in STZ than C rats. In comparison, dietary Fe absorption per day was not altered. Increased Zn absorption was closely correlated with diabetes-associated polyphagia. The initial rate of injected 65Zn excretion was more rapid in STZ rats, although the rate of excretion beyond day 7 was similar from C and STZ animals. The quantity of Zn, Fe, and Cu absorbed per 20 cm duodenal loop was similar for C and STZ rats. Zn, Fe, and Cu absorption per gram dry mucosa were reduced 45-53% in STZ rats due to the 50% increase in mucosal mass. Moreover, the quantity of radioisotopes accumulated per gram dry mucosa and the concentration of metallothionein per gram mucosal cytosol protein were similar in C and STZ animals. Together, these data demonstrate that increased absorption of dietary Zn and Cu is in part responsible for accumulation of these elements in STZ tissues and suggest altered metal transport at the luminal (brush border) surface of the intestinal epithelium.

Animals↗
PubMed1983

Depressed response of plasma iron and zinc to endotoxin and LEM in STZ-diabetic rat.

Laboratory and epidemiological evidence indicate that the enhanced flux of iron and zinc from the plasma to the storage compartments, such as liver, serves as a protective host response to combat infection. Studies were performed to determine the status of this nonspecific immune response in the diabetic animal, since it is commonly held that the diabetic has an increased incidence and susceptibility to infection. Normal rats and rats previously rendered diabetic by streptozotocin (STZ) were injected with either saline or Escherichia coli endotoxin, and plasma levels of zinc, iron, and copper were monitored 8 hr thereafter. Diabetic rats reduced their plasma zinc and iron levels by 35 and 25%, respectively, in response to endotoxin injection whereas control rats had a 70% decrease in zinc and a 46% depression in iron. Insulin administration to the diabetic rats restored the ability to decrease plasma zinc and iron to the same degree as control rats. Plasma copper did not change in any group. Further investigation suggested that the defect in trace metal response occurred after the secretion of leukocytic endogenous mediator (LEM) in the inflammatory response pathway. It is concluded that STZ-diabetic rats have a diminished ability to decrease plasma zinc and iron in response to endotoxin, and that this defect is due to an ineffective response of target tissues to the effects of leukocytic endogenous mediator. Furthermore, it is postulated that the hyperinsulinemia associated with the stress of infection functions to lower plasma zinc and, possibly, iron, thereby allowing the host to better combat infection.

Animals↗