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Biomedical subjects

R Perlman

Publications and source records attributed to R Perlman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Use of 1 alpha-hydroxyvitamin D3 in the prevention of bovine parturient paresis. IX. Early and late effects of a single injection.

Israeli Friesian cows in the third or later lactation were injected intramuscularly (serratus muscle of the neck) with 1 alpha-hydroxyvitamin D3 in propylene glycol in order to compare the short-term and long-term effects of the drug. Following injection of 700 micrograms 1 alpha-hydroxyvitamin D3, the D-derivative appeared in the plasma after 12 h and reached a peak 24 h after injection. Plasma 1,25-dihydroxyvitamin D increased as early as 6 h and peaked at 24 h. Plasma calcium increased after 6 h and peaked 4 to 5 d after the injection. The administration of a single dose of 350 micrograms 1 alpha-hydroxyvitamin D3 at 7 to 8 d before calving did not prevent periparturient hypocalcaemia observed in the uninjected control cows. A single injection of 700 micrograms 1 alpha-hydroxyvitamin D3 7 to 8 d before parturition prevented hypocalcemia at calving. There were no significant differences in plasma calcium 4 to 21 d after calving between the injected and control cows nor were there any cases of delayed postparturient hypocalcemia or milk fever. Results suggest that 700 micrograms 1 alpha-hydroxyvitamin D3 prolonged the calcemic effect of the drug and prevented hypocalcemia at parturition, even if administered 6 to 8 d before calving.

Animals↗
PubMed1987

Field rickets in turkeys: relationship to vitamin D.

Thirty-two outbreaks of leg disorders in turkeys were investigated during 1981-1985. Among them, 22 were characterized by a low percentage of bone ash and were considered as field rickets. Most of the field rickets cases exhibited reduced plasma calcium and inorganic phosphorus. Plasma 25-hydroxyvitamin D3 and intestinal calcium-binding protein were lower in the rachitic than in normal turkeys. These symptoms are typical of rickets resulting from vitamin D deficiency. The vitamin D3 equivalence of a diet that had been fed during field rickets outbreaks was assayed biologically and found to be 111 micrograms/kg diet, about eight times the minimal requirement. In two other cases no symptoms of rickets were observed in turkeys fed diets that had been previously consumed during field rickets outbreaks. The results indicate that in some cases of field rickets there was no involvement of dietary factors and confirm a previous suggestion that field rickets may result from defects in metabolism of vitamin D3, or in its expression.

Animals↗
PubMed1986

The dual effect of calcium on aromatization by cultured human trophoblast.

To study the effect of calcium ion on aromatization of an androgenic precursor to estradiol by the placenta, cultured term trophoblasts were used as a model system. Secretion of estradiol into the culture medium was regarded as indicating aromatization, since cells cultured with no androgenic precursors produced only insignificant amounts of estradiol. EGTA, verapamil and ionophore A23187 inhibited aromatization, while trifluoperazine, an inhibitor of the calcium-calmodulin complex, interfered with the stimulatory effect of cyclic AMP on aromatization. We conclude that calcium ion has an essential role in the aromatization of 4-androstene-3,17-dione to estradiol. The calcium-calmodulin complex is required for activation of aromatase by cyclic AMP. However, when flooded with calcium by ionophore A23187, the trophoblast is unable to effectively buffer calcium, and aromatization is inhibited.

Androstenedione↗
PubMed1986

Use of 1 alpha-hydroxyvitamin D3 to prevent bovine parturient paresis. VI. Concentrations of vitamin D metabolites and vitamin D3 equivalence in milk.

Concentration of vitamin D metabolites was determined in the milk of control and 1 alpha-hydroxyvitamin D3-injected (700 micrograms) cows that calved 36 to 43 h after treatment. Milk samples were taken 60 h after calving. Concentrations of vitamin D, 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D in milk of the control cows were 372 +/- 24, 264 +/- 68, 68 +/- 26, and 21 +/- 3 ng/L, respectively. Concentrations of vitamin D metabolites in the milk of the treated cows did not differ significantly from those of controls. Concentration of 1 alpha-hydroxyvitamin D3 in milk of treated cows was less than 20 ng/L. In a second experiment, cows were injected twice, at 72-h intervals, with 350 micrograms 1 alpha-hydroxyvitamin D3. Milk was taken 60 h after parturition from cows that calved 37 to 60 h after the second injection. The vitamin D3 equivalence of the milk was 40 +/- 3 IU/L. Results indicate that injection of 700 micrograms 1 alpha-hydroxyvitamin D3 did not affect the concentration of vitamin D metabolites or the vitamin D3 equivalence of milk taken 60 h after calving.

Animals↗
PubMed1985

The effect of inhibitors on insulin regulation of hormone secretion by cultured human trophoblast.

The effect of insulin in physiological concentrations on hormone secretion by human term trophoblast cell culture was studied in relation to insulin control of glucose transport and utilization. Specific inhibitors to these 2 functions were added to the culture, either alone to test for a dose response or with insulin. 2-Deoxy-D-glucose, which inhibits glycolysis, did not change the pattern of response of estradiol and placental lactogen (hPL) secretion to insulin. Phloridzin, an inhibitor of glucose transport, interfered with the stimulatory effect of insulin on hPL secretion, but stimulated insulin inhibition of estradiol secretion when added by itself. The results indicate that hPL response to insulin is dependent on glucose transport, but is independent of glycolysis. Estradiol response is dependent on glucose transport, but is independent of glycolysis.

Cells, Cultured↗
PubMed1985

Observation on the use of 1 alpha-hydroxyvitamin D3 in the prevention of bovine parturient paresis: the effect of a single injection on plasma 1 alpha-hydroxyvitamin D3, 1,25-dihydroxyvitamin D3, calcium, and hydroxyproline.

Israeli Friesian cows in the third or later lactation, were injected intramuscularly with 1 alpha-hydroxyvitamin D3 in propylene glycol. Plasma 1 alpha-hydroxyvitamin D3 peaked 24 to 48 h after 700 micrograms of the drug was injected and decreased to the initial concentration 4 d later. The disappearance rate of 1 alpha-hydroxyvitamin D3 from the blood was .330 d-1 (biological half-life of 2.1 d). Plasma 1,25-dihydroxyvitamin D3 peaked 24 to 48 h after the injection and approached the initial concentration 5 to 7 d later. Plasma calcium increased within 24 h, reached a plateau at 4 to 6 d, and then decreased. Administration of 700 micrograms 1 alpha-hydroxyvitamin D3 resulted in higher plasma 1,25-dihydroxyvitamin D3 and calcium concentrations than when 350 micrograms of the drug was injected. 1 alpha-Hydroxyvitamin D3 did not affect plasma hydroxyproline. The injection of 700 micrograms 1 alpha-hydroxyvitamin D3 52 to 36 h before parturition resulted in a greater increase in plasma 1,25-dihydroxyvitamin D3 than that obtained with 350 micrograms. In both groups 1,25-dihydroxyvitamin D3 peaked 24 h after injection, as opposed to the controls, which peaked 72 h postpartum. At parturition, the 700-micrograms dose resulted in a slight hypercalcemia; the 350-micrograms dose moderated the hypocalcemia prevalent during this period, whereas in controls hypocalcemia was more pronounced. In cows injected with 700 micrograms, hypercalcemia was observed until the 15th d postpartum. Plasma hydroxyproline was elevated in all cows 48 to 72 h after parturition, but the increase was smaller in animals injected with 1 alpha-hydroxyvitamin D3.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The modulation of placental lactogen secretion by calcium: studies with cultured human term trophoblast.

Previous reports have documented the negative regulatory effect of calcium ion on the secretion of human placental lactogen by the placenta. Human term trophoblasts were dispersed from term placenta and maintained in monolayer cell culture. Incubation of the cultured trophoblast with EGTA produced a dose-dependent stimulation of placental lactogen secretion. The calcium ionophore A23187 inhibited hormone secretion. This inhibitory effect was eliminated by the addition of the calcium-calmodulin complex inhibitor trifluoperazine. It is concluded that calcium exerts a negative regulatory effect on the secretion of placental lactogen by a mechanism which requires the action of the calcium-calmodulin complex.

Calcimycin↗
PubMed1984

Cardiovascular changes produced by the injection of aconitine at the area of the locus coeruleus in unanesthetized rats.

Blood pressure, heart rate and electrocardiogram were monitored in unanesthetized, unrestrained rats while the area of the locus coeruleus was stimulated by the injection of 0.03 to 10 micrograms of aconitine to pharmacologically evaluate its cardiovascular action. Aconitine elicited a dose-dependent elevation of mean blood pressure to 200 mmHg; at doses of 1-10 micrograms, it increased heart rate by more than 100 beats/min and produced arrhythmias. Phentolamine and the serotonergic antagonist, 2-bromo-lysergic acid diethylamide, prevented aconitine-induced cardiovascular changes. Diminution of aconitine-induced tachycardia by propranolol was attributed to the antagonist's direct peripheral effects. Atropine (5 mg/kg, subcutaneously) did not alter aconitine's cardiovascular actions. It is suggested that stimulation of the area of the locus coeruleus with aconitine elicits specific cardiovascular effects, which may involve adrenergic as well as serotonergic pathways.

Aconitine↗
PubMed1983

Surgery for gynecomastia.

The surgical treatment for gynecomastia has had variations since 1538, when the first description of the surgical treatment was attributed to Paulus Aegineta. Since then, various incisions on and under the breast have been used. It has also been thought that when gynecomastia is severe, the excess skin should be removed along with the gland and fat. The technique for the correction of gynecomastia presented leaves minimal scar, allows access to the tumoral mass, and requires no skin excision.

Adolescent↗
PubMed1983

Insulin regulates placental lactogen and estradiol secretion by cultured human term trophoblast.

We have described a human term trophoblast cell culture system which synthesizes hormones de novo from their precursors. In the present report we utilized this monolayer system to show that insulin produced a dose-dependent stimulation of hPL secretion, with a significant effect at 10(-10) M insulin. At 10(-9) M concentration, insulin also inhibited estradiol secretion by the cultured trophoblast. We conclude that insulin regulates secretion of estradiol and placental lactogen by cultured human term trophoblast.

Cells, Cultured↗
PubMed1981

Platelet monoamine oxidase values and genetic heterogeneity in schizophrenia research.

Platelet monoamine oxidase (MAO) activity is significantly reduced in chronic schizophrenics with family history of schizophrenia. The degree of reduction is related to the extent of genetic load. Schizophrenics with no affected relatives do not differ from control subjects. These findings are consistent with the hypothesis of genetic heterogeneity in schizophrenia. Discrepancies among previously reported data sets can thus be explained by overrepresentation of nongenetic phenocopies with normal MAO levels. The implications for biologic and genetic research in schizophrenia are discussed.

Blood Platelets↗
PubMed1980

Human platelet monoamine oxidase and the menstrual cycle.

Endocrine factors are known to affect platelet monoamine oxidase (MAO) activity. To assess the role of sex steroid hormones in regulating MAO, blood samples for platelet MAO assay were obtained twice weekly from 12 women. Peak MAO activity occurred during the ovulatory interval and a nadir occurred in the postovulatory phase, 5 to 6 days later. A 17% mean effect of menstrual variation from peak to nadir was noted. The implications for MAO studies in psychiatric research are discussed.

Adolescent↗
PubMed1980

Low platelet monoamine oxidase activity: a possible biochemical correlate of borderline schizophrenia.

Platelet monoamine oxidase (MAO) activity, psychiatric disorders, and family history of psychopathology were studied in 115 nonhospitalized, previously undiagnosed college student volunteers. Subjects were classified into two extreme groups: those with platelet MAO activity two standard deviations below the mean ("low-MAO" probands) and those with platelet MAO activity two standard deviations above the mean ("high"-MAO probands). Low-MAO probands were found to have a significant increase in the incidence of borderline schizophrenia and other psychiatric disorders compared to high-MAO probands. First-degree relatives of low-MAO probands were more often affected with psychiatric disorders and borderline schizophrenia than relatives of high-MAO probands. The data suggest that reduced platelet MAO activity is associated with psychiatric vulnerability and that the spectrum of schizophrenia may be more closely related to this vulnerability than other psychiatric disorders.

Adult↗