[The vitamin D endocrine system and bone tissue mineral metabolism in rats with adjuvant arthritis: the effect of 1,25-dihydroxyvitamin D3].

Adjuvant arthritis was induced in male rats by injecting bacillus Calmette-Guèrin in mineral oil in a hindpaw. A decrease in bone density, calcium and phosphorus content due to polyarthritis was found in the tibia of the noninjected hind leg. Arthritic rats demonstrated serum 1,25-dihydroxyvitamin D deficiency along with constant level of 25-hydroxyvitamin D.

[Effect of 1,25-dihydroxycholecalciferol and 24,25-dihydroxycholecalciferol on calcium homeostasis in rats treated with hydrocortisone].

Physiological dose of 1,25(OH)2D3 (0.03 microgram) normalized the phosphorus-calcium metabolism and improved the state of bone tissue in rats treated with hydrocortisone. An increased dose of 1,25(OH)2D3 (0.

[Effect of 1,25-dioxycholecalciferol and 24,25-dioxycholecalciferol on calcium homeostasis in rats given hydrocortisone in the diet with various phosphorus contents].

High content of phosphorus in the diet (1.8% of phosphorus in the diet, Ca:P ratio 1:3) accelerated the development of hypocalcemia and osteoporosis and increased their degree in rats which received hydrocortisone (3.5 mg/10 g bw a day for 4 weeks).

[Comparative study of the effects of alpha-25-dihydroxycholecalciferol and 24, 25-dihydroxycholecalciferol on calcium-phosphorus metabolism and on bone tissue in experimental kidney insufficiency in rats].

Experimental chronic kidney insufficiency (CKI; within 2-6 months) in rats, kept on a diet containing 0.6% Ca2+ and 0.6% P was accompanied by distinct azotemia, hyperphosphatemia, by a decrease in specific weight, in content of Ca2+, P and hydroxyproline in diaphyses as well as by a decrease in epiphyseal Ca2+.

[Role of sterols in the interaction of polyene antibiotics with lipid membranes].

The problem whether the membrane sterols are indirect acceptors of polyenic antibiotics or they play the role of substances providing conditions (at the expense of putting in order the membrane phospholipids) for formation of conductive complexes (ionic canals) from the antibiotic molecules is discussed. The comparative study on the ability of sterols of various structure (ergosterol, 7-dehydrocholesterol, cholesterol, 5 alpha-cholestan-3 beta-ol) to interact with the membrane phospholipids and to increase the sensitivity of such membranes to amphotericin B showed no correlation between the levels of these properties. The value of the changes in the cross elasticity module (E) of artificial bilayer lipid membranes from egg lecithin on introduction of the above sterols into their composition was used as the criterion for the interaction level.

[Comparative study of the biological activity and toxic effect of 1alpha-hydroxycholecalciferol and ergocalciferol in rats].

Single administration of 0.25 microgram of sunthetic Ialpha-hydroxycholecalciferol (IalphaOHD3) into nephrectomized rats, maintained at D-avitaminous diet, improved the active transport of calcium ions against the concentration gradient in small intestine of these animals, whereas ergocalciferol was biologically inactive under the same conditions. Administration of IalphaOHD3 during 5 days at a dose 0.

[1 alpha-hydroxyvitamin D3: chemical synthesis and biological effect].

A method for the synthesis of an analog of vitamin D3--1alpha-hydroxy vitamin D3 (1alpha-OH D3) from cholesta-4,6-dien-3beta-ol was developed. Biological activity of this compound in the chick organism was measured. The growth stimulating effect of 1alpha-OH D3 and its effect on bone tissue mineralization and serum biochemical parameters (content of calcium, inorganic phosphorus and activity of alkaline phosphatase) were 4--5 times higher than those of vitamin D3 in low doses (19.