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Biomedical subjects

D Gupta

Publications and source records attributed to D Gupta.

At least 271 records · Page 15Linked to original sources
PubMed1983

Effect of tetrahydrocannabinols on pubertal body weight spurt and sex hormones in developing male rats.

Chronic administration of delta 8- and delta 9-tetrahydrocannabinols (4 mg/kg b.wt. i.p.) to sexually developing male rats every alternate day from age day 16 to age day 87 resulted in a significant decrease in pubertal growth spurts, especially the second peak. Endogenous testosterone, dihydrotestosterone, LH and FSH concentration in blood declined significantly from those of the control animals. When the drugs were withdrawn at mid-puberty (age day 40) the "catch-up" phenomenon in body growth weas evident although testosterone level continued to be suppressed but dihydrotestosterone level recovered. Withdrawal of the drugs resulted in better recovery in LH level compared to that of FSH. Administration of LH-RH to the animals receiving drugs until day 87 resulted in significantly (P less than 0.001) lower levels of gonadotropins than those in the control animals. The inhibition in delta 9-THC-treated animals was more severe than in delta 8-THC-treated ones. When the drug was withdrawn, delta 8-THC-treated animals responded to LH-RH stimulation better than did those treated with delta 9-THC. These findings suggest that the tetrahydrocannabinols perhaps mainly affect pituitary function.

Animals↗
PubMed1983

Role of the pineal gland in the regulation of prostatic androgen receptors in pubertal and mature rats.

The effects of exposure to continuous light, continuous darkness, and administration of melatonin on prostatic androgen receptors in relation to pubertal development in rats were examined. Darkness produced dissimilar results between the pubertal and adult groups. Whereas the prostate weight in the pubertal group remained unaltered, it increased in the adult group. In the pubertal group exposed to darkness, plasma melatonin increased significantly, and androgen receptors declined, whereas in the adult group these receptors rose significantly with a simultaneous increment of melatonin concentration in plasma. Exposure to continuous light did not produce any effective alterations in the parameters examined. The afternoon melatonin administration showed trends similar to those seen in animals exposed to darkness. The results indicate that exposure to darkness or administration of melatonin both have age-dependent effects on prostatic androgen receptors. Exposure to darkness may interfere with the process of sexual maturation in the pubertal animal as a result of increased melatonin production.

Animals↗
PubMed1983

Hormones and human milk.

The presence of several hormones in milk occurring either by passive diffusion or by active concentrating mechanism from blood can be of great concern to the neonate. According to Fulkerson [1979] when the clearance rates of the hormones out of blood is considered, this worry is unwarranted. Concerning the steroids, when their levels have been monitored in milk after lactogenesis, the worry for the baby seems to be unfounded. But with the new finding of high level of LH-RH in milk whose concentration far exceeds that of blood, care should be taken to examine in the neonates whether the levels of LH and FSH become disproportionately high and induce the secretion of gonadal steroids at a higher level.

Adrenal Cortex Hormones↗
PubMed1982

Bridging large bone defects with a xenograft composited with autologous bone marrow. An experimental study.

We have investigated the role of defatted, decalcified xenogenic bone implants composited by impregnation with fresh autologous marrow in bridging large cortical defects. Diaphyseal cortical implants were obtained from orthopaedic operations on humans and from guinea pigs and prepared by treatment with acetone, 0.6 M HCl and ethanol. The composited graft was used to bridge a 3 cm defect in the diaphysis of the ulna of rabbits. Periodic investigations were made clinically, radiographically and histologically and by tetracycline, fluorescence studies up to 20 weeks. Abundant new bone formation was observed in 85.7% of composited human xeno-autografts and in 83.3% of composited guinea pig xeno-autografts. New bone formation was seen in 13.3% of noncomposited xeno-implants. No appreciable antigenicity was observed either clinically or histologically in the grafts. The high degree of success obtained justifies further studies on implants composited by fresh autologous marrow and offers hope for the enhancement of new bone formation clinically, particularly in reconstructive operations for significant skeletal defects. We feel that the osteo-inductive potential of autologous marrow was responsible for the healing of the defects aided by the better internal milieu provided by defatted decalcified xeno implant.

Animals↗
PubMed1982

Responsiveness of cortisol and dehydroepiandrosterone to ACTH in children.

In a total of 101 children, the dehydroepiandrosterone (DHA) and cortisol (F) levels were measured before and after ACTH (Synacten) administration. F responsiveness was unchanged during development, while DHA responsiveness in healthy children was highest during adrenarche. In hypopituitary patients DHA levels were lower than in the controls, but responsiveness to ACTH showed similar changes during development. Children with Turner's syndrome and hypergonadotrophic males had the response in elevated DHA levels while ACTH-induced DHA response related to bone-age matched controls. We conclude that regulation of adrenal androgens is mediated by both ACTH and another hypothalamo-pituitary hormone, perhaps independent of gonadal activation, but requiring gonadal integrity.

Adolescent↗
PubMed1982

Osteoinductivity of partially decalcified alloimplants in healing of large osteoperiosteal defects.

About 3.5 cm osteoperiosteal circumferential gaps in rabbit ulnae were bridged by partially decalcified (by 0.6 M HCl) allogenic implants, 8-12 weeks after implantation complete bridging of the gap by new bone formation and union at host-graft junctions was observed in 97.2 per cent of the experiments. Instant permeability and the powerful osteo-inductive potential of the implant coupled with some degree of mechanical stability provided by partial decalcification ensured successful bone formation in almost all the experiments. It is suggested that partially decalcified allogenic bone matrix preserved in 70 per cent ethanol may be a reasonably good substitute for autologous bone graft.

Animals↗
PubMed1982

Effect of human chorionic gonadotropin on the plasma levels of testosterone, estradiol, sex hormone binding globuline and free testosterone in Klinefelter syndrome.

Preliminary experiments showed that a course of 3 X 5000 IU Human Chorionic Gonadotropin (HCG) every alternate day in 5 patients with Klinefelter Syndrome caused increment in the circulating levels of testosterone, estradiol, and Sex Hormone Binding Globuline (SHBG). The levels of free testosterone, however, declined in 3 subjects and recorded no change in the remaining two. Estradiol/testosterone ratio on day 0 showed high correlation (r = 0.853) with augmented SHBG. It has been postulated that higher amount of SHBG is perhaps potentiating a reduction in the bioavailability of testosterone.

Adult↗
PubMed1982

Amniotic fluid levels of 17 alpha-hydroxyprogesterone during human pregnancy: pre-natal diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency.

Levels of 17 alpha-hydroxyprogesterone were estimated by radioimmunoassay in 174 amniotic fluid specimens obtained from 162 normal pregnancies of 16-20 weeks gestation. Another 18 specimens from 11 normal pregnancies between 25-42 weeks gestation and 7 specimens from 7 women who each previously had given birth to a child affected with CAH were also studied. There was no sex difference in AF 17 alpha-OH-progesterone levels, nor any significant downward trend in concentrations throughout the observed gestation period. Among the 7 subjects with previous history of CAH offsprings, 4 demonstrated normal levels of AF 17 alpha-OH-progesterone and 3 significantly higher values. HLA-typing of the cultivated amniotic cells confirmed these 4 cases to be heterozygous for 21-hydroxylase deficiency. The three subjects with high AF 17 alpha-OH-progesterone levels delivered babies affected with CAH, although HLA-typing in one case was non-conclusive. The failure of HLA-typing in 1 case for a confirmatory diagnosis indicates that the prenatal diagnosis of CAH must continue to rest on joint endocrinological and genetical investigations.

17-alpha-Hydroxyprogesterone↗
PubMed1981

Effect of morphogenesis on the infectivity of tissue.

A technique was standardised to develop callus cultures from leaf tissues of tobacco plants infected with CPO strain of tobacco mosaic virus. These leaf callus cultures had a higher virus titre than the callus cultures developed from other explants such as stem, as evidenced by bioassay on local lesion hosts. Morphogenetic dedifferentiation of callus culture influenced the virus titre of the cultured tissues. Caulogenic dedifferentiation of the callus culture induced higher virus titre than rhizogenic dedifferentiation. In the non-differentiated callus cultures, however, the introduction of histogenesis, as evidenced by the compact growth, did not affect the virus titre. The formation of chlorophyll in the callus culture cells also did not change the infectivity of the tissue and thereby the virus titre.

Cell Differentiation↗
PubMed1980

Data on linkage relations between GLO and 21-hydroxylase.

Linkage between GLO and 21-hydroxylase was investigated in 11 families with 24 children. Positive lod score values with a maximum of +1.618 at theta = 0.05 indicate close linkage between these marker loci.

Adrenal Hyperplasia, Congenital↗
PubMed1978

Augmentation of in vitro pituitary biotransformation of testosterone due to orchidectomy and its relation to serum gonadotropins in the rat.

The biotransformation of testosterone to its metabolites by the anterior pituitary gland and the relation between the products formed and the circulating levels of LH and FSH were examined in male rats at various stages of sexual maturation. The animals were either intact controls or castrated 4 and 7 days prior to the investigation. Castration greatly increased testosterone biotransformation to its 5alpha-reduced products, but did not affect the formation of androstendione. It was concluded that castration and the eventual rise of LH-RH stimulated the 5alpha-reductase activity but not the 17beta-ol-dehydrogenase system. This is reflected in the significant relationship between the circulating gonadotropins and 5alpha-metabolites of testosterone but not androstendione.

Androstenedione↗
PubMed1977

Age related changes in pituitary responsiveness to luteinizing hormone-releasing hormone in the male rat.

Changes in pituitary and serum concentrations of LH and FSH, determined by radioimmunoassay, were studied after administration of LH-RH to intact male rats of various ages. Although injection of LH-RH resulted in a depletion of pituitary LH and FSH in almost all age groups, thereby increasing the serum levels of these hormones, the magnitude and time course of the effects varied. Serum LH in the prepubertal and pubertal rats was maximal at 10 min after LH-RH injection, whereas the mature animals showed maximal increase only after 30 min. Peak serum concentrations of FSH found at 10 min in the prepubertal animals, but between 30 and 60 min in the pubertal and adult animals. At 35 days of age, significant pituitary depletion of LH and FSH occurred.

Age Factors↗
PubMed1977

Hypothalamic control of the mammalian sexual maturation.

The attainment of sexual maturity is a complex process which requires maturation and interaction not only of gonads and reproductive tract but also of the pituitary and essentially of the neuroendocrine mechanisms which ultimately control gonadotropin secretion. One of the more attractive hypotheses of the sexual maturation presumes the existence of the sensitivity threshold of the regulating system to the negative feedback signal, which differentiates immaturity from maturity. As the subject matures this declines. In an attempt to examine further the maturational alterations of the male hypothalamo-pituitary-gonadal axis, investigations were carried out with regard to simultaneous changes of blood LH, FSH, testosterone and dihydrotestosterone levels during the course of 24 hr; augmentation of pituitary and blood LH and FSH concentrations under the stimulus of LH-RH as a function of time and age; synthesis and release of LH and FSH in the testosterone-blocked animals at various stages of sexual maturation; and in vitro biotransformation of testosterone to its 5 alpha-reduced metabolites by the pituitaries as a function of age. Evidence from the experimental data could be interpreted as a decrement of the feedback set-points during sexual maturatio as reflected by the transition of the responses obtained under various experimental signals. In parallel to these observations, new evidence was presented regarding not only quantitative but qualitative changes in the pituitary gonadotropins as response to the negative and positive feedback signals. This leads to new thinking with regard to the hypothesis of differential sensitivity.

Animals↗