Biomedical subjects

A Loganath

Publications and source records attributed to A Loganath.

47 records · Page 3Linked to original sources

PubMed1985

Inappropriate luteinizing hormone concentration in human breast cancer.

As part of a programme to assess the para-endocrine behaviour of human infiltrating ductal breast carcinoma among Chinese women, this study was designed to compare (Mann-Whitney U test) the immunoreactive mammary tumour tissue concentrations of follicle stimulating hormone (FSH), luteinizing hormone (LH), human chorionic gonadotrophin (beta-hCG) and prolaction (PRL) at stages I (n = 9), II (n = 12) and III (n = 7) with that of normal breast tissue (n = 8). It was found that with the exception of FSH and beta-hCG in stages I and III significantly elevated concentrations of protein hormones were noted at all stages of malignancy. The possible importance of these findings in multi-stage mammary carcinogenesis is discussed. It is suggested that measurement of LH concentration may provide an endocrine basis to facilitate the diagnosis of tumours to serve as a guide to the biological behaviour of mammary neoplasms.

Adult↗

PubMed1985

Cholesterol synthesizing enzymes in term human fetal amnion.

Based on the observations that human fetal membranes possess the ability to synthesize steroid hormones, we sought to investigate the precursor role of 2 - 14C acetate in cholesterol formation by term human fetal amnion. Concentrations of derivatized 14C cholesterol was measured by reverse-isotope dilution technique in incubations of 2 - 14C acetate with homogenates of term fetal amnion dissected from 5 human placentae (37-40 weeks gestation) delivered vaginally from uncomplicated pregnancies (age 22-29 years). Controls consisted of homogenates heated in a boiling water bath for 10 min. The data presented demonstrate incorporation of 2-14C acetate into 14C cholesterol by the viable tissue. The extent of enzymic conversion varied from 0.002% to 0.076%. The small but definite conversion indicates that the homogenates of term human fetal amnion contain the full complement of enzymes necessary to catalyse the transformation of acetate to cholesterol. The metabolic need for cholesterol supply during labor is discussed.

Adult↗

PubMed1984

Altered hypothalamic-pituitary-testicular function in incomplete testicular feminization syndrome.

An 18-year-old 46 XY patient with the syndrome of incomplete testicular feminization was investigated. The clinical phenotypic features were distinctive and typical of the 4 46 XY cases previously reported. The findings of elevated plasma T4 with evidence of incomplete development of female secondary sex characteristics suggest partial end organ insensitivity to the androgen at the target tissues. This possibility is substantiated by the high plasma LH level, presumably the consequence of the relative inability of the hypothalamic-pituitary unit to respond to testosterone in the feedback regulation of LH secretion. It is therefore suggested that, compared to normal males, the patient had an altered hypothalamic-pituitary-testicular function.

Adolescent↗

PubMed1984

Cord plasma alpha-fetoprotein values and neonatal jaundice.

Umbilical cord plasma alpha-fetoprotein (AFP) values were determined in 127 infants with hyperbilirubinemia (56 glucose-6-phosphate dehydrogenase (G-6-PD) deficient and 71 G-6-PD normal) and 136 control subjects (73 G-6-PD deficient and 63 G-6-PD normal). The mean alpha-fetoprotein value of 173 +/- 35.2 (SD) mg/L for the group of infants with hyperbilirubinemia was significantly greater than that (122 +/- 21.7 mg/L) for the control infants (P less than .001). G-6-PD status and sex did not significantly affect the alpha-fetoprotein values. Using an alpha-fetoprotein level of 130 mg/L as a "cut-off" value, the incidence of false-positive results was 25.5% and the incidence of false-negative results was 11.8%. This test can be used as a screening procedure to detect infants at high risk for hyperbilirubinemia.

China↗

PubMed1983

Evidence for cleavage of [26-14C]cholesterol side-chain by human foetal membranes in vitro.

With a view to establish the hitherto undescribed role of cholesterol in foetal-membranous steroidogenesis, homogenates of term chorion pars reflexa and amnion pars reflexa and pars placentaris collected from 6 women after spontaneous labour at term (38 to 41 weeks gestation) were incubated with [26-14C]cholesterol. Using reverse-isotope dilution analysis, [14C]isocaproic acid was isolated and characterized. This conversion constitutes strong evidence that C-20, 22-desmolase activity, normally present in the adrenal, gonadal and placental tissues, is present in the homogenates of both membranes. The efficiency of the enzymic conversion suggests that the chorion possesses a more active desmolase system compared to that of the amnion.

Adult↗

PubMed1982

Elevated intravesicular fluid luteinizing hormone concentration in hydatidiform mole.

Concentrations of human chorionic gonadotrophin (beta-hCG), follicle-stimulating hormone (FSH), luteinizing hormone (LH) and prolactin (PRL) were measured by radioimmunoassay in the serious fluid of hydatid vesicles obtained from 27 patients with hydatidiform mole. High amounts of all four hormones were found in every case. The mean concentrations +/- SEM were 710.8 +/- 100.8 i.u./1 X 10(-3) for beta-hCG, 13.8 +/- 0.3 i.u./1 for FSH, 302.2 +/- 34.5 i.u./1 X 10(-3) for LH and 2610.8 +/- 562.1 m-i.u./1 for PRL. It is suggested that aberrations in the mechanisms controlling the synthesis and release of luteinizing hormone-releasing factor (LH-RF) could result in chronically elevated LH levels leading to changes characteristic of the disease.

Adolescent↗

PubMed1982

Cigarette smoke-induced cholesterol C-20, 22-desmolase inhibition in pregnancy.

In an attempt to demonstrate the physiological importance of cholesterol C-20, 22-desmolase regulation of pregnenolone formation in maternal cigarette smoking during pregnancy, the in vitro effect of cigarette smoke extract on corpus luteal and placental desmolase ability to cleave (26-14C) cholesterol to (14C) isocaproic acid, was studied. Using the reverse-isotope dilution technique, (14C) isocaproic acid was isolated and characterized. With the homogenates of corpora lutea of pregnancy (4 to 9 weeks gestation) the maximal inhibitory effect (98.3%) on desmolase efficiency became evident at equivalent of 4 cigarettes. In response to concentrations of the extract at 1/2, 1, 2 and 4 cigarette equivalents on the preparations of placentae (18 to 20 weeks gestation), a dose-dependent pattern of inhibitory effect was observed (29.1 to greater than 95.1%). These results are consistent with the interpretation that decreased supply of pregnenolone for the biosynthesis of progestational and oestrogenic hormones may be causally related to changes characteristic of cigarette-smoke induced pathologic state. It is suggested that similar studies directed towards alteration in biosynthetic capacity of steroidogenic enzymes may provide the basis for our understanding of molecular events initiated in response to the common insult.

Adult↗

PubMedDate not supplied

Concentrations of intracellular sex steroids in human spermatozoa.

In an attempt to determine whether human spermatozoa contain steroid hormones, the immunoreactive levels of progesterone, testosterone, and estradiol-17 beta were measured in the extracts of sonicated specimens of sperm obtained as ejaculates from husbands of infertile couples (n = 67, age 26-44 years). In the range of sperm concentration between 3.0 and 869.6 million per ejaculate (143.2 +/- 13.6 mean +/- SEM), the concentrations were as follows: progesterone 127.3-6685.4 fmol/ml (1434.5 +/- 178.6), testosterone 98.3-2219.1 fmol/ml (611.6 +/- 49.0), and estradiol-17 beta 33.0-678.1 fmol/ml (206.9 +/- 19.7). Using Pearson's correlation coefficient, the steroid hormone levels correlated significantly with the total sperm number (p < .02). The spermatozoa contained small but measurable amounts of the sex steroids.

Adult↗

PubMedDate not supplied

Aromatization of [4-14C]testosterone to [14C]estradiol-17 beta by testicular tissue from male-to-female transsexuals on estrogen therapy.

Abnormality in testicular biosynthesis of sex hormones may accompany or cause transsexualism. With a view to determine whether the cells of male transsexual testicular tissue possess aromatic cytochrome P-450 activity, homogenates of the tissue from 4 phenotypic male-to-female transsexuals (2 Chinese and 2 Malays, aged 23-34 years) with XY karyotype who had been on estrogen therapy for 9-17 years until orchidectomy were incubated with [4-14C]testosterone as substrate. Using reverse-isotope dilution analysis, identity was established for [14C]estradiol-17 beta. No such metabolite was found in parallel incubations of heat-denatured enzymes. The extent of enzyme-catalyzed conversion was 9.3 x 10(-3) to 3.4 x 10(-2)%. The specific biosynthetic aromatase cytochrome P-450 activity contained in the tissue system can synthesize [14C]estradiol-17 beta from [4-14C]testosterone. Elevated aromatic expression in situ may have important effects on target tissues.

Adult↗

PubMedDate not supplied

Characterization of a delta 5-3 beta-hydroxy pathway of testosterone synthesis in the human spermatozoa.

Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32-38 years; n = 7, age 27-38 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5; 131.1 and 256.7 millions per ejaculate were separately incubated with [7n-3H]pregnenolone and [1,2,6,7(-3)H]dehydroepiandrosterone. Using the reverse-isotope dilution technique [3H]dehydroepiandrosterone and [3H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.2 x 10(-2) to 4.6 x 10(-20/0) and 7.1 x 10(-2) to 2.5 x 10(-10/0)/ Such metabolites were not evident in the controls. These results provide evidence for metabolic transformation of pregnenolone to testosterone via the delta 5-3 beta-hydroxy route.

Adult↗

PubMedDate not supplied

A delta 4-3-keto pathway for testosterone synthesis in the human spermatozoa.

The ability of human spermatozoa to metabolize pregnenolone to progesterone and progesterone to testosterone was assessed. Sonicated specimens of freshly ejaculated sperm from two groups of husbands (n = 6, age 32-38 years; n = 6, age 30-51 years) of infertile couples in the range of sperm concentration between 237.5 and 568.5, 100.1 and 248.8 millions per ejaculate, were separately incubated with [7n-3H]pregnenolone and [1,2,6,7,16,17-3H]progesterone. Using the classical reverse-isotope dilution technique the desired products [3H]progesterone and [3H]testosterone formed from the respective substrates were isolated and characterized, yielding 1.4 to 12.2% and 3.1 x 10(-2) to 2.0 x 10(-1)%. Such metabolites were not evident in the controls. The results indicate that the human spermatozoa contain the enzymes necessary for the transformation of pregnenolone to testosterone via the delta 4-3-keto route.

Adult↗