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J Hawrylko

Publications and source records attributed to J Hawrylko.

7 recordsLinked to original sources
PubMed1985

GSH-dependent inhibition of lipid peroxidation: properties of a potent cytosolic system which protects cell membranes.

Properties of a heat labile, nondialyzable cytosolic factor which prevents lipid peroxidation in membranous organelles are described. The factor is present in liver and other animal tissues, and its capacity to inhibit lipid peroxidation in membranes subjected to oxidative stress is greatly potentiated by glutathione (GSH), although GSH by itself has no inhibitory effect on lipid peroxidation. The data obtained thus far indicate that one or more sulfhydryl groups associated with the factor is required for the inhibition. The mechanism by which lipid peroxidation is inhibited must involve prevention of initiation of peroxidation in the membranes, presumably by a process requiring one or more sulfhydryl groups associated with the heat labile factor. The latter appears to be protected by GSH while the factor is exerting its inhibitory effect on lipid peroxidation. The factor is not one of the known GSH-dependent enzymes, and appears to be a potent and ubiquitous system for stabilizing cell membranes against oxidative damage.

Animals↗
PubMed1979

Hypercalcemic effect of insulin in the chick.

There are conflicting reports on the effect of insulin on plasma Ca concentration in rats. Low doses appear to decrease and higher doses to increase plasma Ca. Since birds are known to be very sensitive to parathyroid hormone and have resistance to the hypoglycemic effects of insulin, the effect of commercial and highly purified insulin on plasma Ca concentration was studied in 10-day-old chicks 60 min after the administration of the hormone. Both commerical bovine and purified porcine insulin provoked a dose-related elevation of plasma Ca. Although hypophosphatemia was observed with the highest dose of insulin used (0.4U), hypercalcemia was observed with 0.05 U insulin, a dose that did not modify plasma phosphate concentration. The slopes of the dose-response curves of insulin and parathyroid hormone were indistinguishable and different from that of 1 alpha-hydroxyvitamin D3. Neither propranolol nor deprivation of vitamin D altered the hypercalcemic response to insulin. Unexpectedly, propranolol (40 microgram/chick) provoked elevation of plasma Ca. It is concluded that insulin raises plasma Ca concentration in the chick by a mechanism(s) not yet elucidated.

Animals↗
PubMed1977

Effects of aldosterone on the urinary excretion of total and non-dialyzable hydroxyproline.

In order to explore the role of mineralocorticoids on collagen metabolism, the effects of aldosterone on the urinary excretion of total and non dialyzable hydroxyproline (HYPRO) was studied in rats. The administration of aldosterone in sesame oil, 75 microgram/100 g body weight to adrenalectomized rats maintained on 1% NaCl solution as drinking fluid and 1 mg of cortisone subcutaneously daily, provoked elevation of total and non dialyzable HYPRO in urine (P less than 0.001), when compared to similarly treated adrenalectomized rats receiving sesame oil but no aldosterone. Both groups showed a normal growth curve and had similar urinary excretion of creatinine. The effects of aldosterone are opposed to the known lowering effects of glucocorticoids on HYPRO excretion and may suggest an effect of aldosterone on collagen turnover. Alternatively, aldosterone may modify the metabolism or excretion of HYPRO in an opposite manner to that of glucocorticoids.

Adrenalectomy↗