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Biomedical subjects

A R Sheth

Publications and source records attributed to A R Sheth.

At least 163 records · Page 9Linked to original sources
PubMed1980

Long-term effects of vasectomy on prostatic function in men.

The seminal plasma constituents of acid phosphatase, maltase, citric acid, prolactin, zinc and magnesium were measured in men vasectomized for 1-8 years. Compared with values obtained for a group of normal fertile men, all the constituents, except acid phosphatase which was unchanged, decreased significantly after vasectomy, but not progressively so. Since the constituents measured are believed to be of prostatic origin, the results suggest that vasectomy in men decreases the secretory function of the prostate gland.

Acid Phosphatase↗
PubMed1980

Negative feedback of secretion of follicle-stimulating hormone by the pituitary gland of developing male rats.

Rabbit antiserum to human seminal plasma inhibin (hSPI) was administered subcutaneously to developing male rats of 5, 10, 14, 17 and 24 days of age and the size of the endogenous FSH rise in serum was measured. The FSH levels were threefold higher on day 9 and 1.5-fold higher on days 14 and 18 when compared with levels in control rats treated with normal rabbit serum. Furthermore, the in-vitro binding capacity of pituitary plasma membrane to 125I-labelled hSPI declined with increase in age of the rats. Thus, the results of the present study suggest that the sensitivity of the testicular inhibin-FSH feedback relationship is related to age-dependent changes in pituitary binding of inhibin.

Animals↗
PubMed1980

Isolation and characterization of ovine testicular and ovarian inhibin.

Low-molecular-weight (< 1500 daltons) peptides with inhibin activity have been isolated from sheep testes and ovaries by simple gel filtration. These peptides were capable of inhibiting the ovarian weight increase in hCG-primed immature female mice and also of suppressing the post-castration rise of serum FSH levels in adult male rats, suggesting similarities in their biological properties. Both testicular and ovarian inhibin were typsin sensitive and heat stable at 100 degrees C for 30 min and were shown to act by interfering with the production of a hypothetical FSH-RH.

Animals↗
PubMed1980

Effect of spermine on divalent cations of human spermatozoa.

The present report deals with the effect of spermine (0.4--2.0 mg) on the intracellular levels of calcium, magnesium, sodium, and potassium in human spermatozoa. Spermine decreased the calcium and magnesium levels in a dose-related manner; however, changes in the sodium and potassium levels could not be correlated with spermine concentration.

Calcium↗
PubMed1980

Lack of seasonal changes in biochemical constituents of bonnet monkey semen.

The seasonal changes in the production of semen were investigated in four proven-fertile bonnet males (Macaca radiata), maintained under ordinary laboratory conditions. The various physical and biochemical characteristics of 190 ejaculates collected at different seasons of the year were analyzed. There were no significant changes in the responses to penile stimulation, in semen volume, sperm density, and in the concentrations of fructose, citric acid, sialic acid, maltase, amylase, and protein of seminal plasma, attributable to season.

Animals↗
PubMed1980

Modulation of FSH action by inhibin.

Both testicular and ovarian inhibin preparations caused a dose-related inhibition of binding of 125I-hFSH to rat testicular receptors. Testicular inhibin also suppressed the FSH-induced production of cAMP by rats testis in vitro. These data demonstrate a direct action of inhibin at the testicular level by interfering with FSH action.

Animals↗
PubMed1980

Measurement of inhibin.

The bioassays developed so far, although good for detecting inhibin from different sources and for monitoring their purification, are not really practical for physiological studies. Moreover, they are influenced by steroidal hormones. In this regard radioimmunoassays, with their high capacity and greater sensitivity, are of immense value in studies involving the physiology of inhibin. More information on this aspect will probably lead to the development of more rational methods of assay. However, the need for an international reference preparation that will provide a common basis for comparing data from different laboratories cannot but be emphasized.

Animals↗
PubMed1980

Role of adrenals on the 24-hour periodicity in hypothalamo-pituitary axis in male rat.

Studies were carried out to investigate the influence of adrenalectomy on the 24 hour periodicity in the hypothalamo-pituitary axis in adult male rat. Adrenal gland ablation resulted in the shift in the occurrence of peak content of hypothalamic LHRH and attenuation in the responsiveness of the pituitary to synthetic LHRH. Following adrenalectomy, the circadian serum LH peak was attenuated and serum FSH showed a 24 hour periodicity. In conclusion, the results suggest the possible role of adrenal gland in the maintenance of 24 hour periodicity of hormones in the hypothalamo-hypophyseal axis in male rat.

Adrenalectomy↗
PubMed1980

Effects of castration on 24-hour periodicity of hypothalamo-pituitary gonadotropic function.

Groups of 6 castrated or sham-castrated (controls) adult male rats were decapitated 7 days after the operation at 4 h intervals within a 24 h period. Serum LH, FSH and PRL were measured by radioimmunoassay and GnRH activity in medial basal hypothalamus was estimated by bioassay using donor pituitaries from normal adult rats. Finally, the responsiveness of pooled pituitaries from each experimental group to 5 ng synthetic GnRH was tested in vitro immunoreactive LH in medium being used as the end point. It was found that the castration of male rats results in the abolition of 24 h periodicity of hypothalamic GnRH content. Furthermore, a shift in the occurrence of peak levels (acrophase) and about 100 percent increase of the pituitary sensitivity to GnRH was observed. The castration also resulted in a shift in the acrophase of serum gonadotropins levels. In conclusion, the presented data suggest that the gonadal secretion possibly maintains the circadian periodicity of hypothalamo-pituitary gonadotropic function.

Animals↗
PubMed1979

Presence of elevated circulating levels of LH during the pre-menstrual period in some copper IUD users and the possibility of their confusion with hCG.

A heterologous radioimmunoassay (RIA) capable of discriminating between LH and hCG was used to measure LH levels in sera obtained during the pre- and post-menstrual periods from 80 women bearing copper intrauterine contraceptive devices (IUD). hCG levels in these samples were also estimated by use of a homologous beta-hCG radioimmunoassay and a radioligand-receptor assay. Only two IUD users during the pre-menstrual period had detectable, but low hCG levels. However, LH levels, as estimated by specific RIA, in the serum of these two women were elevated to a level that would cause detection at low levels in the hCG assays. The data thus provide direct evidence to indicate that the positive hCG levels observed by others during the pre-menstrual period in some copper IUD users could be due to the interference in hCG assays by elevated LH.

Adult↗