Biomedical subjects

M G Subramanian

Publications and source records attributed to M G Subramanian.

At least 37 records · Page 2Linked to original sources

PubMed1990

Effects of low doses of alcohol on delta-9-tetrahydrocannabinol's effects in pregnant rats.

Pregnant rats were intubated with 50 mg/kg of delta-9-tetrahydrocannabinol (THC) or with THC plus alcohol to determine if a low dose of alcohol (1 g/kg) would significantly increase blood levels of THC. On the basis of this study, a second study was conducted in which pregnant rats were intubated with THC (50, 25 or 0 mg/kg) plus alcohol (2, 1 or 0 g/kg) from gestation day six to parturition. THC reduced birth weights but did not significantly affect litter size or passive avoidance learning. Alcohol did not have a significant effect on offspring birth weight nor did it interact with THC to affect offspring.

Animals↗

PubMed1990

Vinblastine reduces progesterone and prostaglandin E production by rat granulosa cells in vitro.

To elucidate the possible mechanism(s) of vinblastine-induced premature ovarian failure, we studied the effect of vinblastine (VLB) on progesterone (P) and prostaglandin E (PGE) production by rat granulosa cells in vitro. Granulosa cells obtained from immature, pregnant mares' serum gonadotrophin-primed rats were incubated for 5 h in modified Medium 199 +/- LH (10 ng/mL) with varying concentrations of VLB (0.001 to 10.0 micrograms/mL) and cells plus media were assayed for total P and PGE. VLB reduced production of both basal and LH-stimulated P in granulosa cells, with VLB at a concentration of 0.1 micrograms/mL showing the first significant difference from control. This dose also suppressed basal and LH-stimulated PGE. Granulosa cell survival was similar for all groups. Thus VLB, an agent known to disrupt microtubular function, reduced granulosa cell production of both P and PGE. Our results suggest that at a concentration (0.1 micrograms/mL) lower than that routinely achieved during chemotherapy (0.3 micrograms/mL), VLB depresses rat granulosa cell function in vitro. This system appears to be a valid model for preliminary assessment of the cytotoxic effects of chemotherapy on an ovarian component.

Animals↗

PubMed1990

Acute alcohol infusion does not alter plasma gonadotropins or prolactin in ovariectomized rats.

We examined the effects of acute alcohol on basal plasma FSH, LH, and prolactin in ovariectomized rats. Alcohol infusion and blood sampling were done via an indwelling atrial catheter. Blood samples for alcohol and hormone determinations were collected before, and 5 to 120 min after completion of saline (control) or alcohol in saline (experimental) infusion. Plasma follicle-stimulating hormone, luteinizing hormone, and prolactin were not altered during the 2-hr period. Peak blood alcohol concentrations achieved following 1.0- and 2.0-g/kg body weight of alcohol doses were approximately equal to, and twice, the legal human intoxication levels, respectively. Alcohol clearance rates from blood for the two groups were: 130 +/- 3 mg/kg/hr for the 1.0-g/kg body weight group and 151 +/- 3 mg/kg/hr for the 2.0-g/kg body weight group. These results show that acute alcohol does not affect basal gonadotropins and prolactin secretion in ovariectomized rats.

Alcoholic Intoxication↗

PubMed1990

Pattern and duration of the inhibitory effect of alcohol administered acutely on suckling-induced prolactin in lactating rats.

We have characterized the pattern and duration of the inhibitory effect of acute alcohol administration on suckling-induced prolactin (PRL) release in the lactating rat. On day 2 of lactation, litters were adjusted to eight pups. On day 6, dams were implanted with an atrial catheter and experiments were conducted on day 10 of lactation. Pups were removed from the dams at 0800 hr. An extension tube filled with heparinized saline was attached to the catheter at 1300 hr. At 1400 hr, a preinfusion (PRE 0) blood sample was removed and was followed by infusion of saline (control) or alcohol in saline (0.5, 1.0, 2.0, 2.5 g/kg body weight doses) solutions. Following the removal of a postinfusion (POST 0) blood sample, pups were returned to the mother. Subsequent blood samples were obtained 10, 30, 60, 120, and 180 min after initiation of suckling. In separate groups, the effects of alcohol on basal PRL were studied by collecting blood samples PRE 0, POST 0 and 20, 40, 60, 80, 100, and 120 min following infusion of saline or alcohol in saline to lactating rats also separated from their pups for 6 hr. Alcohol infusion did not alter basal PRL. However, suckling-induced PRL was inhibited at 10, 30, 60, and 120 min of suckling by alcohol administered at doses greater than or equal to 1.0 g/kg body weight. After 180 min of suckling, plasma PRL levels were comparable among groups. The suckling latency for the 2.5 g/kg body weight alcohol group was greater than for other groups, but the quantities of milk consumed during the 3-hr suckling period were comparable.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

The effect of cocaine on oocyte development and the follicular microenvironment in the rabbit.

We examined the effects of cocaine exposure in the rabbit on in vitro oocyte development and on steroidal content of follicular fluid (FF) and serum progesterone (P). Cocaine hydrochloride (0, 10, 20, 40, or 80 mg/kg) was administered daily subcutaneously for 5 days to New Zealand White female rabbits before superovulation. On the last day of cocaine administration, animals were given human chorionic gonadotropin intravenously, and laparotomy was performed 6 to 8 hours later. During laparotomy, ovaries were removed, the number of follicles recorded, oocytes retrieved, and FF was obtained. In vitro fertilization (IVF) was then performed on the oocytes and the rate of cleavage observed. For all cocaine dosage groups, no differences were observed in the number of follicles present, number of oocytes retrieved, or IVF and cleavage rates. Cocaine did, however, decrease periovulatory serum P, and FF P, whereas FF estradiol concentrations increased. This suggests that short-term cocaine exposure affects the follicular steroid milieu, possibly by delaying granulosa cell luteinization.

Animals↗

PubMed1989

Porcine zona pellucida: association of sperm receptor activity with the alpha-glycoprotein component of the Mr = 55,000 family.

The immunogenicity and sperm receptor activity of five preparations of the major porcine zona pellucida glycoprotein family ZP3 (Mr = 55,000) were investigated. These included (1) ZP3, a chromatographically purified preparation of the 55,000 family; (2) ZP3 alpha, and (3) ZP3 beta, the two-component glycoproteins of the ZP3 family; (4) ZP3-EBGD, a partially deglycosylated preparation of ZP3 obtained by enzymatic treatment; and (5) ZP3-DG, a chemically deglycosylated preparation of ZP3. Titer studies using mouse and rabbit antisera prepared against each preparation yielded the following order of immunogenicity: ZP3 and ZP3 beta greater than ZP3-EBGD and ZP3 alpha greater than ZP3-DG, indicating that ZP3 becomes less immunogenic as more carbohydrate is removed. Pretreatment of intact zona with the various antisera prior to zona exposure to sperm resulted in an inhibition of sperm attachment to those zona treated with antibodies to ZP3, ZP3-EBGD, and ZP3 alpha. Pretreatment of zona with antibodies to ZP3 beta and ZP3-DG had no effect on sperm attachment. Studies involving pretreatment of boar sperm with the various ZP3 preparations prior to their use in a sperm-zona attachment assay and investigations involving displacement of the radiolabeled ZP3 preparations from sperm by unlabeled ZP3 preparations also yielded findings similar to the antibody studies. Collectively, these data indicate that ZP3 alpha probably functions as a zona receptor for boar sperm and that carbohydrate has an important role in maintaining the functional integrity of the ZP3 alpha glycoprotein.

Animals↗

PubMed1989

Effect of varying dosages and adjuvants on antibody response in squirrel monkeys (Saimiri sciureus) immunized with the porcine zona pellucida Mr = 55,000 glycoprotein (ZP3).

Using the porcine zona pellucida Mr = 55,000 (ZP3) glycoprotein as immunogen, the effect of varying ZP3 dosages (50 micrograms, 25 micrograms, 5 micrograms) or adjuvants (200 micrograms ZP3 with either Freund's, A1[OH]3, or a muramyl dipeptide analog [MDP] on antibody response was evaluated in female squirrel monkeys. Although the dosage range investigated did result in dose-dependent titration profiles, antisera from all dosage groups demonstrated in vitro contraceptive potential. MDP was as effective an adjuvant as Freund's in eliciting high titers of antibodies demonstrating contraceptive potential. A1(OH)3 was not an effective adjuvant in this system. Fertility data, utilizing those monkeys in the dosage study, suggested that an RIA titer greater than 40% binding was necessary to prevent pregnancy. We conclude that in the squirrel monkey system, a 50 micrograms dosage of ZP3 should be adequate for inhibiting fertility and that MDP would serve as a satisfactory alternative adjuvant for Freund's.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1988

Human follicular fluid: prolactin is biologically active and ovum fertilization correlates with estradiol concentration.

The bioactivity of prolactin (PRL) in follicular fluid (FF) obtained from mature preovulatory follicles was measured by the Nb2 lymphoma-cell bioassay and compared with the immunoreactivity as measured by radioimmunoassay (RIA-PRL). There was a good correlation between the two assay systems (P less than 0.01), and when RIA-PRL was more than 25 ng/ml, both assay systems yielded comparable values, with a mean bioassay/RIA ratio of 1.06 +/- 0.03; however, when RIA-PRL was 25 ng/ml or less, a discrepancy between the two assay systems was evident, with a bioassay/RIA ratio of 1.55 +/- 0.15. The estradiol (E2) concentration of FF obtained from follicles that contained oocytes which were subsequently fertilized was greater than that in follicles containing oocytes which were not fertilized: 588 +/- 62 vs 376 +/- 37 ng/ml (P less than 0.01), respectively. No differences were found in bioassay-PRL, RIA-PRL, progesterone (P), and FF volumes between fertilized and unfertilized groups of follicles. FF from mature preovulatory follicles contained greater concentrations of RIA-PRL compared to immature follicles (34.6 +/- 3.1 vs 8.5 +/- 1.6 ng/ml; P less than 0.001).

Biological Assay↗

PubMed1988

The effect of "activated" cyclophosphamide on rat granulosa cells in vitro.

We investigated the mechanism of cyclophosphamide (CTX)-induced ovarian toxicity by studying the effect of an activated form, 4-hydroperoxycyclophosphamide (PCTX), on rat granulosa cells in vitro. Cells were obtained from PMSG-primed immature rats and incubated with PCTX at concentrations of 1, 10, 100, and 500 micrograms/mL. Ovine LH (10 ng/mL) was added in selected tubes. Cell viability before and after seven hours incubation was determined. Progesterone and prostaglandin E accumulation were measured by radioimmunoassay. Granulosa cell viability was significantly decreased at PCTX concentrations of 10 micrograms/mL or higher in a dose-related manner. PCTX at concentrations of 100 micrograms/mL and 500 micrograms/mL significantly decreased basal and LH-induced progesterone and prostaglandin E accumulation. The above findings demonstrate that cyclophosphamide metabolites decrease granulosa cell survival and function in vitro. These direct effects suggest a possible mechanism for CTX-induced premature ovarian failure.

Animals↗

PubMed1988

Clinical value of prolactin bioassay in euprolactinemic reproductive disorders.

To examine the disparity between clinical presentation and prolactin (PRL) measured by radioimmunoassay (RIA), serum samples from 128 patients with galactorrhea and/or reproductive disorders were evaluated by RIA for immunoassayable PRL (RIA-PRL) and by Nb2 lymphoma cell proliferation assay for bioassayable PRL (bioassay-PRL). One hundred fifteen patients had normal RIA-PRL and 13 patients had high RIA-PRL (greater than 25 ng/ml). Twenty patients had galactorrhea, two of whom had hyperprolactinemia. The reproductive disorders in female patients included infertility, amenorrhea, oligomenorrhea, irregular menstrual cycles, and luteal phase defects. Six oligospermic males also were studied. Twenty-three male and female volunteers with no evidence of reproductive disorders served as controls. Appropriate comparisons showed that PRL bioassay/RIA ratio, an index of agreement between the two assay systems, did not differ for the various patient groups compared with controls. It is concluded that Nb2 lymphoma bioassay does not provide additional diagnostic value to RIA in defining the cause of euprolactinemic galactorrhea and/or reproductive disorders.

Biological Assay↗

PubMed1988

Amniotic fluid cortisol and alpha-fetoprotein in normal and aneuploid pregnancies.

Cortisol and alpha-fetoprotein (AFP) levels were measured in amniotic fluid (AF) samples at 15-20 weeks of gestation from 125 normal pregnancies and 29 pregnancies affected by aneuploidy. The normal pregnancy group was further subdivided into 'low' AF-AFP (less than 0.6 MOM, n = 60) and 'normal' AF-AFP (0.6 less than AFP less than 1.4 MOM, n = 65). A significant, inverse, linear correlation was found between cortisol and AF-AFP for both normal AFP and low AFP groups (r = -0.26, and r = -0.4, respectively, p less than 0.05). Gestational age was significantly correlated with both cortisol and AFP levels in the normal pregnancy groups. No difference was found when cortisol levels were compared between the low and normal AFP groups. The correlation between cortisol and AFP in aneuploid pregnancies was not significant (p = 0.37). The strong association between cortisol or AFP and gestational age in normal pregnancy (p less than 0.00001) was lost in trisomic gestation. We conclude that higher cortisol levels do not seem to be the cause of low AFP in normal or aneuploid pregnancies.

Amniotic Fluid↗

PubMed1987

Ectopic prolactin secretion from a gonadoblastoma.

A 6.5-year-old girl developed isosexual, pseudoprecocious puberty secondary to a gonadoblastoma. The tumor was found to produce and secrete both immunoassayable and bioassayable prolactin based on immunohistochemical techniques and the presence of a prolactin gradient between the tumor vein and peripheral vein. The source of the prolactin was a Sertoli-like cell. Neither growth hormone nor growth hormone-releasing hormone was detected within the tumor. This case confirms the ectopic production of prolactin by neoplastic tissue.

Child↗

PubMed1987

Structural characterization of the Mr = 55,000 antigen (ZP3) of porcine oocyte zona pellucida. Purification and characterization of alpha- and beta-glycoproteins following digestion of lactosaminoglycan with endo-beta-galactosidase.

The major macromolecular component of the porcine oocyte zona pellucida is a Mr = 55,000 antigen, termed ZP3, comprised of greater than 25 charge isomers. ZP3 was purified to apparent electrophoretic homogeneity from nonreduced, sodium dodecyl sulfate-treated porcine zonae pellucidae by chromatography on Sephacryl S-400 and hydroxylapatite resins. The carbohydrate moiety of purified ZP3 was comprised of a heterogeneous population of acidic lactosaminoglycans as evidenced by the saccharide composition and size distribution of glycopeptides produced by Pronase digestion of ZP3, as well as by the sensitivity of ZP3 to digestion with Escherichia freundii endo-beta-galactosidase. Endo-beta-galactosidase-digested ZP3 was resolved by gel electrophoresis into two components, termed alpha-glycoprotein and beta-glycoprotein, with Mr values (nonreduced) of 46,000 and 42,000, respectively. Each was comprised of fewer and more neutral charge isomers than ZP3. Following purification by reverse phase high performance liquid chromatography, the alpha- and beta-glycoproteins of endo-beta-galactosidase-digested ZP3 were distinguished on the basis of amino acid and carbohydrate compositions, amino-terminal sequence analyses and peptide mapping experiments, thus suggesting differences in the primary structures of their respective polypeptide moieties. Corresponding dissimilarities in the immunoreactivities of the alpha- and beta-glycoproteins toward polyclonal antisera raised against ZP3, alpha-glycoprotein, and beta-glycoprotein were revealed by competitive binding radioimmunoassays as well as by immunoblotting experiments. Collectively, the data were interpreted to indicate that the Mr = 55,000 antigen of porcine oocyte zona pellucida is in fact comprised of overlapping families of charge isomers corresponding to two structurally and immunologically distinct lactosaminoglycan-containing glycoproteins.

Amino Sugars↗

PubMed1987

Ovaries remain functional in squirrel monkeys (Saimiri sciureus) immunized with porcine zona pellucida 55,000 macromolecule.

Fifty female squirrel monkeys were each immunized with 200 micrograms of a purified preparation of the 55,000 macromolecule (ZP3) from porcine zona pellucida. The fertility status of these immunized monkeys, as well as the effect of ZP3 antibodies on ovarian function, was monitored. High anti-ZP3 titers were achieved (greater than 75% binding levels as determined by radioimmunoassay) and remained high (approximately 67% binding level) for the duration of this study. Hormonal evaluations indicated initial disturbances in normal ovarian steroid secretion and function that were confirmed by laparoscopic observation and oocyte production data. Histological examination of ovaries at 6-7 mo post-injection suggested an interference in folliculogenesis. No pregnancies were observed in the immunized monkeys during this period. By 10-15 mo post-immunization, hormonal and laparoscopic data indicated that ovarian function was recovering in injected monkeys despite the continued presence of high titers to ZP3. Collectively, these results demonstrate that although immunization with ZP3 initially produces disturbances in normal ovarian function that inhibit fertility, these effects are reversible. Such findings encourage the continued intensive investigation of purified porcine zona macromolecules for immunocontraceptive purposes.

Animals↗

PubMed1987

Olfactory bulbs influence testosterone feedback on gonadotropin secretion in male hamsters on long or short photoperiod.

Previous studies have shown that prepubertal olfactory bulbectomy will prevent the testicular regression associated with short photoperiod in golden hamsters. The gonadal regression which normally occurs in hamsters on short photoperiod is known to be due in part to an increased responsiveness of the reproductive neuroendocrine system to the negative feedback actions of testosterone on LH and FSH secretion. The present study tested whether the olfactory bulbs influence the feedback effects of testosterone on gonadotropin secretion. Twenty-four- to 26-day-old male golden hamsters were either olfactory-bulbectomized (BX) or sham-olfactory-bulbectomized. Eight weeks later, all hamsters were castrated, and one half of each group was placed in LD 10:14 (this was called week-8 of the study), while the other half was returned to long photoperiod (LD 14:10). Eight weeks following castration (week 0 of the study), all animals were implanted with silastic capsules containing 0, 4, 8 or 16 mm of testosterone. All hamsters were bled by cardiac puncture at -8, -4, 0, +2, +4, +6 and +8 weeks. The concentration of LH and FSH in these samples was then determined by RIA. BX completely prevented the negative feedback of testosterone on gonadotropin secretion in hamsters on either long or short photoperiod at all levels of testosterone tested in this study. In addition, there were seemingly steroid-independent effects of BX on gonadotropin levels in the castrated hamsters prior to testosterone replacement at weeks -4 and 0.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1987

Testosterone levels in adult male epileptic patients.

Total and free testosterone levels were assayed in 80 epileptic outpatients. The levels were in the low-normal range, and there was no dissociation between free and total levels observable in this sample. No relationships to clinical epilepsy parameters or anticonvulsant levels were found, but significant inverse relationships existed with age and the number of different anticonvulsant medications a patient was taking. The age effect was independent of the medication contribution and raises the question of premature aging of the sexual system in patients with epilepsy. Whether or not this is part of a more general premature decrease in the functions of the pituitary hypothalamic axis needs to be investigated.

Adult↗

PubMed1986

Pituitary gonadotropin releasing hormone (GnRH) receptor levels in intact and ovariectomized-adrenalectomized female golden hamsters on a short photoperiod.

Both intact and ovariectomized + adrenalectomized hamsters on a short photoperiod, had a daily surge in plasma LH at approximately 16.00-18.00 h. The number of pituitary GnRH receptors was generally lower in ovariectomized + adrenalectomized hamsters than in intact animals, but both intact and ovariectomized + adrenalectomized hamsters had a decrease in the number of receptors just prior to the LH surge. These results show that gonadal steroids are not involved in regulating the pre-LH surge fall in the number of GnRH receptors.

Adrenalectomy↗

PubMed1986

Pathways to immunocontraception: biochemical and immunological properties of glycoprotein antigens of the porcine zona pellucida.

The zona pellucida (ZP) is an extracellular coat which surrounds the mammalian oocyte and whose macromolecular composition is unique for each species. Two-dimensional gel electrophoresis of porcine ZP under reducing conditions resolves four major acidic, charge-heterogeneous glycoproteins with apparent molecular weights of 82,000 (ZP1), 61,000 (ZP2), 55,000 (ZP3) and 21,000 (ZP4). Fractionation of heat-solubilized porcine ZP under nondissociative, nonreducing conditions resulted in a preparation, termed purified pig zona antigen (PPZA), substantially enriched in ZP3 and lacking ZP1 and ZP2. PPZA was highly immunogenic in both rabbit and squirrel monkey. Anti-PPZA sera exhibited contraceptive potential as assessed by in vitro inhibition of homologous sperm-zona binding following antibody treatment of human, pig and squirrel monkey oocytes. Alternatively, fractionation of sodium dodecyl sulfate (SDS)-dissociated porcine ZP under nonreducing conditions resulted in isolation of two electrophoretically homogeneous antigens with apparent molecular weights of 82,000 (82K antigen) and 55,000 (55K antigen) as judged by nonreducing SDS-polyacrylamide gel electrophoresis. The 82K antigen exhibited an estimated molecular weight of 345,000 by gel filtration chromatography in nondissociative solvent and was comprised of ZP1 and disulfide-linked heterodimers of ZP2+ZP4 and ZP3+ZP4. The 55K antigen was comprised of ZP3 which was highly aggregated in nondissociative solvent. Each antigen had a characteristic carbohydrate composition and proved to be immunogenic in the rabbit. The effects of active heteroimmunization of squirrel monkeys with 55K antigen on fertility are under investigation.

Animals↗