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Biomedical subjects

R S Mathur

Publications and source records attributed to R S Mathur.

At least 55 records · Page 3Linked to original sources
PubMed1993

Androgen regulation of thromboxane A2/prostaglandin H2 receptor expression in human erythroleukemia cells.

Thromboxane A2 (TxA2), a platelet aggregator and vasoconstrictor, has been implicated as a potential mediator of cardiovascular diseases. Abuse of androgenic steroids has been associated with thrombotic cardiovascular diseases. Human erythroleukemia (HEL) cells, a megakaryocyte-like cell line, express functional TxA2/prostaglandin H2 (PGH2) receptors with characteristics similar to those seen in platelets. This study characterized testosterone regulation of HEL cell TxA2/PGH2 receptors. TxA2/PGH2 receptor affinity (Kd) and density (Bmax) were determined via equilibrium binding experiments using the radiolabeled TxA2 mimetic (1S-[1 alpha,2 beta(5Z),3 alpha(1E,3R*),4 alpha])-7-(3-[3-hydroxy-4-(4'- iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]heptan-2-yl)-5-he ptenoic acid (125I-labeled BOP). Testosterone (200 nM) but not estradiol increased Bmax from 108 +/- 9 fmol/mg protein to 157 +/- 9 fmol/mg protein (n = 7 experiments; P < 0.01) without any significant change in Kd. Testosterone had no significant effect on alpha 2-adrenergic receptor density. The maximum increase in intracellular free calcium induced by the TxA2 agonists I-BOP or U-46619 was significantly (P < 0.005) greater in testosterone-treated cells compared with controls. Hydroxyflutamide (1 microM), an androgen-receptor antagonist, completely blocked the effect of testosterone (P < 0.01). Dihydrotestosterone, the active metabolite of testosterone, also increased Bmax in a concentration-dependent manner and was more potent than testosterone. The effect of testosterone to increase Bmax was significantly (P < 0.01) inhibited by coincubation with cycloheximide (0.1 microgram/ml) or actinomycin D (10 ng/ml). These results indicate that androgenic steroids regulate the expression of functional TxA2/PGH2 receptors in HEL cells. These findings may have relevance to cardiovascular disease.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1992

3 alpha-Androstanediol and 3 alpha-androstanediol glucuronide. Maternal and umbilical cord plasma concentrations in normal pregnancy.

Concentrations of 3 alpha-androstanediol (A) and 3 alpha-androstanediol glucuronide (AG) were measured with a radioimmunoassay in pregnancy plasma samples collected from the mother in the first trimester (first, n = 18) and second trimester (second, n = 20) and at term (n = 14). At term, along with the maternal samples, matching cord plasma samples were also obtained (n = 14). Throughout pregnancy the levels of A and AG were significantly higher than in normally menstruating women. Although the total concentration of A and AG did not change significantly throughout pregnancy, the levels of A in the second and at term were significantly higher than in the first. In contrast, AG concentrations in the second were significantly lower than in the first and at term. As compared to the maternal concentrations at term, the cord levels of AG and A plus AG were not significantly different. However, the levels of A in the cord were significantly lower than those in the maternal circulation at term. Significant correlations were observed between the term maternal and cord levels of AG and A plus AG. No sex-related differences in the plasma levels of A and AG were noted. The results show that levels of A and AG increase significantly in the first trimester and remain elevated throughout pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Androstane-3,17-diol↗
PubMed1992

Plasma 3 alpha, 17 beta-androstanediol glucuronide concentrations in normally menstruating Chinese women.

Hirsutism is rare in oriental women. In order to define the androgen metabolism in these women, plasma levels of androstanediol glucuronide (AG) along with testosterone (T), androstenedione (delta 4A), dehydroepiandrosterone sulfate (DHAS) and sex hormone binding globulin (SHBG) were determined in samples collected from 22 normally menstruating Chinese women. Their ages were 37.7 +/- 7.2 years (mean +/- S. D.) with a range of 27 to 46 years. All were born of Chinese parents. None were on any hormonal medication for at least one year. Compared to our local controls, no significant differences were observed in plasma androgens and SHBG concentrations. Comparable levels of AG, delta 4A and T in these two groups suggest that in Chinese women, under basal conditions, the androgen metabolism is comparable to their north american counterparts.

Adult↗
PubMed1991

Anaerobic threshold as a measure of physical work capacity.

Fifty healthy subjects underwent incremental exercise on a treadmill. Anaerobic threshold (AT) and maximum oxygen consumed in litres per minute (VO2 max) were measured. VO2 max (mean +/- SD) in males and females was 2.71 +/- 0.5 and 2.014 +/- 0.4 L/min respectively. AT as a percentage of VO2 max predicted was 58 in males and 56 in females. These values were comparable to Western studies. Anaerobic threshold is the most sensitive indicator of exercise performance.

Adult↗
PubMed1990

Serum angiotensin converting enzyme in the diagnosis of pulmonary sarcoidosis.

Serum angiotensin converting enzyme (SACE) was estimated in 25 normal healthy subjects mean (15.62 +/- 6.5 mU/mL/37 degrees C), 26 patients with sarcoidosis (32.06 +/- 9.7) 15 with pulmonary tuberculosis (16.31 +/- 4.6) and 19 with diffuse interstitial lung disease (11.72 +/- 4.555). Significantly (P less than 0.05) elevated SACE values were seen in active sarcoidosis, and serial SACE levels correlated well with the course of the disease.

Humans↗
PubMed1990

Effect of steroidal fraction of seeds of Abrus precatorius Linn. on rat testis.

Dose-dependent degenerative changes in the testicular weights, sperm count, later stages of spermatogenesis and Leydig cells are observed in testis of rats treated with steroidal fraction of seeds of A. precatorius. These are correlated with the dose-dependent decrease in the enzyme activity of 3 alpha, 3 beta, 17 beta-hydroxysteroid dehydrogenases, glucose-6-phosphate dehydrogenase, sorbitol dehydrogenase and leucine aminopeptidase. The steroidal fraction may also exert its influence indirectly at the pituitary level by a feedback mechanism, leading to decrease in production and release of testosterone which results in significant alterations in the testis.

Animals↗
PubMed1989

Sex steroid hormones are altered in essential hypertension.

Little is known about the relationship between blood pressure and endogenous sex steroid hormones in patients with essential hypertension. Studies in hypertensive men have described decreased androgens. Men with cardiovascular disease may have estrogen levels which are increased or similar to healthy controls. We measured selected sex steroid hormones in 24 medication-free patients with uncomplicated essential hypertension (diastolic blood pressure less than or equal to 90 mmHg) and 24 normotensive subjects. The groups were equally divided by race, gender, age and weight. Hypertensive men had lower levels of both free and total testosterone and androstenedione than controls. The converse was true for hypertensive women. Androgen levels were similar in blacks and whites regardless of gender or blood pressure. Estradiol levels were higher in hypertensive men and women than controls and in blacks than whites. Levels of luteinizing hormone and sex hormone binding globulin were similar in all subjects. The clinical and pathophysiological significance of our findings merits further investigation.

Adult↗
PubMed1987

Cytotoxic sperm antibodies and in vitro fertilization of mature oocytes: a preliminary report.

The fertilization rates of mature oocytes during in vitro fertilization and embryo transfer (IVF-ET) using fetal cord serum-supplemented insemination media were greater than or equal to 57% for five infertile couples without sperm antibodies (group 1). But they were less than or equal to 50% for four of nine infertile couples (group 2) with cytotoxic sperm antibodies in both partners (n = 6) or the husband alone (n = 3). Two women in group 1 were successful in achieving normal, full-term pregnancies with the delivery of normal infants (chi2 = 4.2, P less than 0.05, by chi-square analysis). One of them consistently tested negative for sperm antibodies, while her husband was previously treated with antibiotics for infection and transient sperm antibodies in the seminal plasma. Subsequently, antibody titers in the husband were in the normal range when the successful IVF-ET was performed. One woman in group 2, with antibodies to her autoimmune husband's sperm but not control sperm and with a long-standing poor postcoital test sperm motility, conceived through artificial insemination with donor sperm (AID) after failing to conceive with her husband through IVF-ET. These data suggest that the presence of cytotoxic sperm antibodies in the serum and/or secretions of both partners reduces the rates of fertilization of mature oocytes in spite of using fetal cord serum in the IVF media. Pregnancy achievement is impaired in this group.

Antibodies↗
PubMed1986

Time-related changes in the plasma concentrations of prolactin, gonadotropins, sex hormone-binding globulin, and certain steroid hormones in female runners after a long-distance race.

Running is associated with an increase in plasma concentrations of certain anterior pituitary hormones and adrenal steroids. This study reports such increases after a marathon race. Six trained female runners, 26 to 42 years old, participated in a marathon race. Fasting (resting) blood samples were collected a few weeks before the race (baseline) and immediately (0 hour), 1 hour, and 4 hours after the run. The data were analyzed with the use of two-way analyses of variance (F-test), paired t-test, and Page's test. At 0 hour, compared with baseline, significant increases were observed in the plasma concentrations of testosterone (T), dehydroepiandrosterone sulfate (DHEA-S), cortisol (F), free T index (T/SHBG), and prolactin (PRL). At 1 hour, levels of these steroid hormones and PRL declined, some significantly. At 4 hours, levels of all hormones except DHEA-S returned to baseline. No significant changes were observed in concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and sex hormone-binding globulin (SHBG), as evaluated by F-test. Running-associated changes in plasma hormonal concentrations revert to baseline in four hours, although DHEA-S may take a little longer.

Adult↗
PubMed1985

The effect of estrogen treatment on plasma concentrations of steroid hormones, gonadotropins, prolactin and sex hormone-binding globulin in post-menopausal women.

Twenty-one post-menopausal women on no other medication were treated with a low dose (0.625 mg/day) of conjugated equine estrogen (CEE) for a mean (+/- SEM) period of 2.6 +/- 0.2 mth (range 1.75-4.75). Blood samples were collected before and at the completion of therapy, and alterations in the levels of prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), sex hormone-binding globulin (SHBG) and certain steroid hormones, including the free testosterone (T) index (T/SHBG) were studied. Following treatment, a significant increase in SHBG levels produced a significant decrease in the free T index (P less than 0.005). As expected, no changes were observed in the levels of PRL and steroid hormones other than estrone (E1) and estradiol-17-beta (E2). Our observations indicate that treatment of post-menopausal women with low-dose estrogen lowers the unbound T.

Adult↗