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Biomedical subjects

Y Weisman

Publications and source records attributed to Y Weisman.

At least 127 records · Page 7Linked to original sources
PubMed1983

The effect of 1,25-dihydroxyvitamin D3 on cartilage growth in neonatal mice.

The in vivo effects of 1,25(OH)2D3 on cell proliferation, tissue organization and matrix mineralization have been studied in condylar cartilage of neonatal mice. A relatively low dose of the metabolite, 50 ng/kg body weight, significantly reduced the incorporation of [3H]thymidine as well as the number of chondroblasts. The cartilage as a whole underwent a marked derangement in its organization, as many fibroblastlike cells appeared to occupy the zone of progenitor cells. There was a high degree of correlation observed between the effects of 1,25(OH)2D3 upon [3H]thymidine incorporation and the size of the condylar zone of chondroblasts. With increasing doses, enhanced mineralization was noted in the cartilaginous matrix, along with cartilage cell degeneration. These findings indicate that 1,25(OH)2D3 possesses an inhibitory effect upon both the proliferative activity of prechondroblasts and upon the capacity of those cells to differentiate into chondroblasts.

Animals↗
PubMed1982

Evidence for 24,25-dihydroxycholecalciferol receptors in long bones of newborn rats.

Several reports have appeared that suggest that 24,25-dihydroxycholecalciferol has a possible biological role in bone formation. We have utilized competition studies, saturation analysis, sucrose-density-gradient sedimentation and DEAE-cellulose chromatography to demonstrate that long bones of vitamin D-depleted newborn rats contain cytoplasmic and possibly nuclear receptors that bind 24,25-dihydroxycholecalciferol with specificity and high affinity (Kd = 1.79 nM). Sucrose-density-gradient analysis of the cytoplasmic 24,25-dihydroxycholecalciferol-binding component showed a single binding macromolecule for 24,25-dihydroxycholecalciferol with a sedimentation coefficient of 3.1 S. DEAE-cellulose chromatography showed a [3H]24,25, dihydroxycholecalciferol-macromolecular complex that binds to DEAE-cellulose and elutes between 0.15 and 0.21 M-KCl. The finding of 24,25-dihydroxycholecalciferol receptors in long bones of newborn rats suggests a possible involvement of 24,25-dihydroxycholecalciferol in the metabolism of developing skeletal tissues.

24,25-Dihydroxyvitamin D 3↗
PubMed1982

Hepatic cirrhosis suggesting aflatoxicosis in a flock of geese.

An outbreak of hepatic cirrhosis in a flock of young geese was investigated. The affected geese were cyanotic with purple beaks, shanks and footwebs. On post mortem examination severe atrophy of the liver was seen and, histologically, extensive areas of necrosis, cirrhosis and bile duct proliferation were prominent. Liver function tests and serum enzyme levels confirmed that the liver damage was extensive. The findings are compared with those found in aflatoxicosis of other avian species.

Animals↗
PubMed1982

Vitamin D metabolites in human milk.

The concentrations of unconjugated 25-OHD, 24, 25(OH)2D, and 1,25(OH)2D were measured in human milk by competitive protein-binding radioassays following successive preparative Sephadex LH-20 chromatography and HPLC. The mean (+/- SE) concentration of 25-OHD was 0.37 +/- 0.03 ng/ml, of 24,25(OH)2D was 24.8 +/- 1.9 pg/ml, and of 1,25(OH)2D was 2.2 +/-0.1 pg/ml. The concentration of 25-OHD3 in milk as determined by HPLC and UV detection at 254 nm was 0.27 +/- 0.08 ng/ml. The milk concentrations of vitamin D metabolites did not correlate with the maternal serum 25-OHD levels. The total amounts of unconjugated vitamin D metabolites correspond to the known low bioassayable vitamin D antirachitic activity in human milk.

Chromatography, High Pressure Liquid↗
PubMed1982

Isolation of Yucaipa-like avian paramyxoviruses from migrating coots (Fulica atra) wintering in Israel.

Two hemagglutinating (HA) agents were isolated from coots (Fulica atra). One of them was isolated from a brain specimen, the specimens being taken from 8 dead birds. The other one was isolated from a tracheal swab, the tracheal and cloacal swabs being taken from 47 apparently healthy birds. Both the agents were identified as Yucaipa-like avian paramyxoviruses (PMV-2) by means of HA inhibition (HI) and neuraminidase (Nase) inhibition (NI) tests. This is the third species of feral birds and the second species of migrating waterfowl in Israel from which Yucaipa-like viruses were isolated.

Animals↗
PubMed1981

Decreased 1,25-dihydroxycholecalciferol and increased 25-hydroxy- and 24,25-dihydroxycholecalciferol in tissues of rats treated with thyroxine.

The effect of thyroxine on the metabolism of vitamin D was investigated in rats. Vitamin D depleted rats were repleted by injections of radiolabelled cholecalciferol or 25-hydroxycholecalciferol (25OHD3). After 3 weeks, a state of hyperthyroidism was induced by daily injections of L-thyroxine for 21 days. The lipid extracts of the Plasma and tissues were analyzed by successive Sephadex LH-20 and high pressure liquid chromatography. The concentrations of 25OHD3 and of 24,25-dihydroxycholecalciferol (24,25 (OH)2D3) were significantly higher and those of cholecalciferol and of 1,25-dihydroxycholecalciferol (1,25(OH)2D3) were significantly lower in the plasma and tissues of animals treated with thyroxine than in controls. The present study suggests that alterations in the metabolism of vitamin D may be involved in the disturbances of calcium metabolism observed in hyperthyroidism.

24,25-Dihydroxyvitamin D 3↗
PubMed1981

Inadequate status and impaired metabolism of vitamin D in the elderly.

The mean serum concentrations of 25-hydroxyvitamin D and of 24,25-dihydroxyvitamin D were significantly lower (P less than 0.01) in 82 elderly people than in 30 young control subjects. The levels in 30 elderly people confined to their rooms were 8.0 +/- 0.7 (SE) and 0.54 +/- 0.04 ng/ml, respectively; in 31 active old-age-home residents who spent part of their time outdoors, they were 11.4 +/- 0.8 and 0.82 +/- 0.08 ng/ml, respectively; and in 21 elderly farm workers, 14.6 +/- 1.4 and 0.98 +/- 0.10 ng/ml, respectively. In the young control subjects, the levels were 21.5 +/- 1.4 and 1.91 +/- 0.12 ng/ml, respectively. In addition, an intestinal absorption test with a standard oral dose of 25-hydroxyvitamin D3 showed that the serum 25-hydroxyvitamin D3 responses at 4 and 6 h were considerably depressed in 10 of the 20 elderly subjects in whom the test was performed.

Aged↗
PubMed1980

End-organ resistance to 1,25-dihydroxycholecalciferol.

A 13-year-old girl with total alopecia who in infancy had rickets unresponsive to large doses of vitamin D2 is described. She had profound hypocalcaemia which was resistant to treatment with high doses of dihydrotachysterol, 1 alpha-hydroxycholecalciferol, and 1,25-dihydroxycholecalciferol. Serum concentrations of 25-hydroxyvitamin D were normal but those of 1,25-dihydroxycholecalciferol were markedly raised (674 and 745 pg/ml). In addition, 24,25-dihydroxyvitamin D was undetectable in serum. Administration of synthetic 24,25-dihydroxycholecalciferol was followed by normocalcaemia which persisted long after treatment was stopped. Her sister, who died at the age of 10 months, also had had total alopecia, rickets, and hypocalcaemia resistant to vitamin-D2 therapy. In this familial syndrome there seems to be end-organ resistance to the action of 1,25-dihydroxycholecalciferol, possibly as a result of changes at the receptor sites.

Adolescent↗
PubMed1980

Decreased serum tuftsin concentrations in sickle cell disease.

The serum concentrations of the phagocytosis-stimulating peptide, tuftsin, were determined by radioimmunoassay in 21 patients with sickle cell disease and in 12 healthy controls. The mean serum tuftsin concentration was significantly lower in patient with haemoglobin SS disease (154.3 +/- 35.1 ng/ml; 308.6 +/- 70.2 nmol/l, P < 0.01) and in patients with haemoglobin SC and CC disease (180.9 +/- 42.7 ng/ml; 361.8 +/- 85.4 nmol/l, P < 0.05) than in healthy controls (228.7 +/- 46.7 ng/ml; 457.4 +/- 93.4 nmol/1). Tuftsin deficiency is an indicator of splenic hypofunction and may contribute to the increased susceptibility of patients with sickle cell disease to severe infection.

Adolescent↗
PubMed1979

Metabolism of cholecalciferol in land snails.

1. Radioactively labelled cholecalciferol was injected into the land snails Levantina hiersolyma and Theba pisana. Three metabolites (C, D and E), more polar than cholecalciferol, were found. 2. Metabolite C was found to be identical with 25-hydroxycholecalciferol. On injection of 25-hydroxy[26,27-3H]cholecalciferol, metabolite E was predominantly formed. Metabolite D was predominantly formed from cholecalciferol. Metabolites D and E differ from any known cholecalciferol metabolites. 3. The intestine was found to be the tissue capable of carrying out the transformation of 25-hydroxycholecalciferol into metabolite E. 4. 25-Hydroxycholecalciferol and metabolite E were localized in the digestive gland of the snail, the tissue responsible for the absorption of Ca2+ and its storage. Metabolite D was not localized in any specific tissue.

Animals↗