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Biomedical subjects

A R Sheth

Publications and source records attributed to A R Sheth.

At least 37 records · Page 2Linked to original sources
PubMed1992

Hormonal modulation of biosynthesis of prostatic specific antigen, prostate specific acid phosphatase and prostatic inhibin peptide.

Hormonal modulation of in vitro biosynthesis of three prostatic secretory proteins, prostate specific acid phosphatase (PSAP), prostate specific antigen (PSA) and prostatic inhibin peptide (PIP) by human benign hyperplasia (BPH) tissue was studied. LH and inhibins caused increase in the synthesis of all three proteins whereas FSH enhanced the synthesis of PIP and PSA only but decreased PSAP synthesis. Prolactin and thyroid releasing hormone decreased synthesis of PIP and PSAP. However, PSA synthesis was enhanced by TRH and was decreased by prolactin. Estradiol caused significant increase in PSA and PSAP but no discernible changes in PIP synthesis were noticed. Testosterone caused an increase in PIP, PSA and PSAP. These data indicate that biosynthesis of PIP, PSA and PSAP by BPH tissue is under multihormonal regulation.

Acid Phosphatase↗
PubMed1991

Cellular distribution of inhibin in marmoset testes during development.

Using polyclonal antibodies against a 13 KD human testicular inhibin, immunocytochemical localization studies were carried out in marmoset monkey testes. The pattern as well as the intensity of immunocytochemical staining for inhibin vary substantially during development. In early development (day 1 to 2 months) Leydig cells are the predominant cell types showing intense staining which reaches its nadir at 3 months. Subsequently both Sertoli cells as well as Leydig cells show equal intensity of inhibin staining. Testicular inhibin is likely to play a vital role in cell to cell communication.

Animals↗
PubMed1991

Occurrence of bioactive and immunoreactive inhibin (13 KD) in human epididymis.

Using specific polyclonal antibodies generated against a 13 KD human testicular inhibin, immunocytochemical localization of inhibin was carried out in different regions of human epididymis. The concentrations of inhibin were greater in caput and corpus regions as compared to the caudal region. The epididymal inhibin was found to be bioactive, since it suppressed specifically the FSH levels of rat pituitaries in vitro. Spermiophage/macrophage cells exhibited strong staining for inhibin which were suggestive of a possible role of inhibin in modulation of immune function. In view of the known activities of inhibin in cellular growth, differentiation, and steroidogenesis, epididymal inhibin could have a role in acquisition of sperm fertilizing capabilities.

Antibodies↗
PubMed1991

FSH in testes of marmosets during development: immunocytochemical localization and de novo biosynthesis.

Immunocytochemical localization of FSH was carried out in various cell types of marmoset testes during development using antisera generated against intact as well as beta-subunit of human FSH. Significant differences in the intensity as well as distribution of FSH in various cell types were observed in neonatal, pubertal, and adult marmosets. Intensity of staining in Leydig cells was maximum at day 1 and in adults (1-3 years), whereas it was minimum at 3 months. In seminiferous tubules (Sertoli cells), FSH was present in trace amount until puberty and subsequently increased at maturity. Further studies demonstrate de novo biosynthesis of FSH-like moiety in vitro by testicular tissue, which was age dependent.

Animals↗
PubMed1991

Similarities in the modulation of pituitary and prostatic FSH by inhibin and related peptides.

Prostatic inhibin peptide (PIP) suppresses the synthesis as well as release of FSH from the rat pituitary whereas the carboxy terminal nonapeptide (86-94) of PIP elevated the release of pituitary FSH. Addition of a tyrosine residue at the NH2-terminal end of nonapeptide and blocking the sulfhydryl group of the cysteine residue at position 87 resulted in a decapeptide having the property of suppressing FSH release from rat pituitary. Human prostate has been shown to synthesize FSH in vitro. PIP, nonapeptide, and decapeptide modulate the prostatic FSH biosynthesis, the pattern of which was similar to that observed for pituitary.

Animals↗
PubMed1991

Prostate--an extrapituitary source of follicle-stimulating hormone (FSH): occurrence, localization, and de novo biosynthesis and its hormonal modulation in primates and rodents.

A comparative study on the immunocytochemical localization, de novo biosynthesis, and hormonal modulation of follicle-stimulating hormone (FSH) was carried out in the prostates of man, monkey, dog, guinea pig, hamster, rat, and mouse. FSH was localized in the cytoplasm of the prostatic epithelial cells. In some specimens, staining was also observed in the nucleus. Both pituitary as well as prostatic FSH were coeluted on a Sephadex G-100 column and high-performance liquid chromatography (HPLC) indicating physicochemical similarities of FSH in both the tissues. Surprisingly, the modulation of pituitary and prostatic FSH by inhibin and its related peptides were comparable. The intensity and grandularity of FSH staining was stronger in the case of benign prostatic hyperplasia as compared with normal prostatic specimens. In view of the well-known effects of FSH on the cellular growth, differentiation, and function of gonadal tissues, a similar role for FSH in pathophysiology of prostate is postulated.

Adult↗
PubMed1991

Antifertility effects of human sperm antigen in female rats.

The sperm antigens responsible for inducing infertility were identified by Western blot technique using sera from an infertile woman with circulating antisperm antibodies. The 80 Kda was prepared from human sperm by extraction with 0.05% sodium deoxycholate in 0.01 M Tris-HCl buffer, pH 8.4 and fractionation with ammonium sulphate. The supernatant after 40% saturation ammonium sulphate extraction was separated by gelpermeation chromatography, using HPLC (Protein PAK 125 column) and FPLC (superose 12 column) systems. The homogeneity of the protein was established by SDS-PAGE and its molecular size was estimated to be 80 Kda and its isoelectric point was 4.5. The purified protein upon active immunization in female rats caused infertility in 100 percent animals. The data suggest that 80 Kda human sperm antigen has the potential for use as a contraceptive vaccine.

Animals↗
PubMed1991

De novo biosynthesis and localization of inhibin in marmoset (Callithrix jacchus) and rat epididymis.

Using specific polyclonal antibodies generated against a 13 Kd human testicular inhibin, immunocytochemical localization was carried out in epididymis of intact and castrated marmoset monkey and rat epididymis. Inhibin was found to be present in the cytoplasm of epithelial cells of caput, corpus and cauda epididymis. The intensity of staining and pattern of distribution did not change following castration. Further, the in vitro biosynthesis of inhibin studied by incorporating 3H-leucine and precipitating it with specific antibody indicated maximum biosynthesis in the corpus epididymis in case of marmosets and cauda in case of rats. Following castration in rats, the epididymal tissue still retained the capacity to biosynthesize inhibin. These studies indicate that marmoset and rat epididymis are capable of biosynthesizing/absorbing inhibin and whose synthesis does not depend on androgens.

Animals↗
PubMed1991

Endometrium--an extragonadal source of inhibin.

Using polyclonal antibodies generated against human seminal plasma inhibin (10.5 KDa), immunocytochemical localization was carried out in paraffin embedded tissue sections of human endometrial biopsies obtained at various phases of the menstrual cycle. A positive reaction which indicated the presence of inhibin was characterized by the presence of golden yellow or brown colour in the cytoplasm of epithelial cells that formed the glands as well as the luminal lining. The stromal cells however, showed negative staining. In early proliferative phase, the endometrial glands exhibited weak positive staining for inhibin which gradually increased and was intense in late follicular and early secretory phases. The intensity of the staining although was not diminished in the glandular epithelium in the mid as well as late secretory phases, the number of cells showing positive staining appeared to be reduced. Incubation of endometrial biopsies in vitro with labelled amino acid and immunoprecipitation of newly synthesized protein with specific antibodies to inhibin indicated that endometrium is capable of de novo synthesizing inhibin. The above results suggest that endometrium is an extra ovarian source of inhibin and the possible role of endometrial peptide in sperm fertilizing capabilities as well as in pre and post implantation events is suggested.

Adolescent↗
PubMed1991

Suppression of steroidogenesis in mice granulosa cells by a synthetic nonapeptide fragment of human seminal plasma inhibin.

A synthetic nonapeptide, which is C-terminal sequence of 94-amino acid of prostatic inhibin peptide was tested for progesterone and estrogen secretion by mouse granulosa cell cultures. Nonapeptide suppressed the progesterone and estrogen synthesis, the magnitude of suppression was highest at 5 ng dose level for progesterone and 50 ng dose level for estradiol. The study suggests that, nonapeptide exerts its effect by impairing the binding of FSH to granulosa cell receptors.

Animals↗
PubMed1991

Interaction between inhibin and melatonin on secretion of rat pituitary gonadotrophins.

In presence of melatonin, the suppression of FSH levels by inhibin is reduced (31%) as compared to inhibin given alone (51%) to adult male rats. Likewise, inhibin decreases the prolactin enhancement following melatonin administration. These experiments demonstrate interaction of inhibin and melatonin on the secretion of pituitary gonadotrophins.

Animals↗
PubMed1991

Prostate--a novel target for evaluation of FSH modulating peptides.

Effects of prostatic inhibin peptide and its synthetic fragments on FSH biosynthesis by the human pituitary and prostate, were examined in vitro. The results showed that FSH biosynthesis by prostatic tissue is modulated by these peptides in a similar fashion to that observed at the pituitary level.

Amino Acid Sequence↗
PubMed1990

Immunocytochemical localization of follicle stimulating hormone in normal human stomach.

Immunoreactive follicle-stimulating hormone (IR-FSH) is detected in sections of formalin-fixed and paraffin-embedded gastric mucosal tissue of normal men, using the immunoperoxidase staining technique and specific antisera to hFSH (NIDDK, NIH). Positive staining for IR-FSH was detected in the parietal cells lining the gastric glands of the intermediate zone. The staining was intracytoplasmic and distributed throughout the cytoplasm. IR-FSH was also found to be present in the basal part of the foveolar epithelium. Stromal tissue and nuclei were devoid of the stain. The zymogen cells in the deeper region of the mucosa did not show any detectable staining for IR-FSH. The presence of IR-FSH in gastric mucosa was also detected by radioimmunoassay. Gel chromatography of the gastric tissue extract showed a single peak of FSH immunoreactivity that coeluted with the 125I-labeled highly purified FSH preparation (NIDDK, NIH). Furthermore, the FSH in the pituitary tissue extract had a chromatographic profile similar to that of IR-FSH from gastric tissue, and 125I-FSH labeled highly purified FSH, indicating a close resemblance in their molecular sizes. These results demonstrate that IR-FSH is present in the normal human gastric mucosa. The role of this regulatory petpide in gastric tissue, if any, needs to be investigated.

Chromatography↗
PubMed1990

Effect of antibodies to human seminal plasma inhibin on spermatogenesis and sperm agglutination in adult male rats.

In vitro incubation of rat epididymal sperm with antiserum to human seminal plasma inhibin (As hSPI) caused agglutination of the sperm. In vivo administration of As hSPI to adult male rats resulted in a significant decrease in testicular as well as epididymal sperm counts. Furthermore, the majority (almost 90%) of the epididymal sperm were agglutinated. When these animals were mated with normal cycling females, significant reduction in fertility was observed.

Animals↗
PubMed1990

De novo biosynthesis of FSH like peptide by the human prostate.

Human benign prostatic hyperplasia tissue is able to synthesize immunoreactive FSH (IR FSH) in vitro. The prostatic FSH is similar to pituitary FSH as evident by co-elution on Sephadex G-100. High performance gel filtration chromatography and Western blot analysis. Immunocytochemical localization studies indicate positive staining in the cytoplasm of prostatic epithelial cells. There is a two fold increase in the concentration of immunoreactive FSH in benign hyperplastic tissue as compared to normal prostate.

Blotting, Western↗
PubMed1990

Immunocytochemical localisation of follicle stimulating hormone (FSH) in normal, benign and malignant human prostates.

Immunocytochemical localisation of follicle stimulating hormone (FSH) was carried out in normal, benign and malignant human prostates by indirect immunoperoxidase technique. Positive staining was observed in the epithelial cells of all the three categories, while the stromal cells showed a weakly positive reaction in a few specimens. The brown reaction product was dispersed in the cytoplasm of the epithelial cells. These observations demonstrate the presence of immunoreactive FSH-like peptide in human prostate. The significance of FSH in the aetiopathology of prostatic disorders is discussed.

Adolescent↗
PubMed1990

Modulation of lipid peroxidation in human spermatozoa and human prostate by prostatic inhibin.

Loss of sperm motility as a result of the production of hydrogen peroxide by lipid peroxidation is regulated by as yet unidentified prostatic factor(s). Inhibinlike peptide of prostatic origin isolated from human seminal plasma, with a molecular size of about 10,400 daltons, was studied for its effect on ascorbate-induced lipid peroxidation in human spermatozoa. Dose-related suppression of lipid peroxidation was observed at dose levels of 0.25, 0.5, and 1.0 micrograms. The data suggest that inhibinlike peptide could be one of the factors involved in the regulation of lipid peroxidation and thereby of sperm motility. Inhibinlike peptide also exhibited local action in both normal and benign hyperplastic human prostate tissue by enhancing the rate of lipid peroxidation. These findings have implications in the pathophysiology of the prostate.

Dose-Response Relationship, Drug↗