Search PubMed⌕ Search

Biomedical subjects

G W Tang

Publications and source records attributed to G W Tang.

49 records · Page 3Linked to original sources
PubMed1984

Comparative study of total urinary oestrogen and first morning urinary oestrogen in monitoring gonadotrophin therapy.

Total 24-hour urinary oestrogen has been used extensively and proven to be reliable in monitoring gonadotrophin therapy for induction of ovulation. However, the method is time consuming for the patient and incomplete collection, as expected, is not uncommon, hence interfering with the treatment result. Oestrone-3-glucuronide in first morning urine samples has been shown to correlate well with plasma oestradiol-17 beta levels during normal menstrual cycles. A comparative study was made to examine the correlation between the levels of 24-hour urinary oestrogen and first morning urinary oestrogen in patients on gonadotrophin therapy. Creatinine levels were also determined to exclude the factor of variable excretion of oestrogen. The correlation thus found is highly significant (p less than 0.001). Hence first morning urinary oestrogen to creatinine ratios may be used to replace 24-hour urinary oestrogen in biochemical monitoring of gonadotrophin therapy.

Creatinine↗
PubMed1984

Relationships of seminal plasma prolactin with spermatozoal characteristics and fertilizing capacity in vitro.

Seminal plasma prolactin (PRL) levels were determined in 224 semen samples collected from fertile and suspected infertile men, and their relationships with spermatozoal characteristics and fertilizing capacity in vitro were evaluated. PRL concentrations were similar in normospermic and oligospermic samples, but were significantly lower in azoospermic samples. PRL concentrations were significantly higher in samples with high spermatozoal motility than in those with low spermatozoal motility. There were no significant differences in PRL concentrations between normal-morphology and abnormal-morphology samples, and between high-fertilizing capacity and low-fertilizing capacity samples. A low degree of positive correlation was observed between the PRL concentration and the spermatozoal motility. There were no significant correlations between the PRL levels, the other spermatozoal characteristics, and the spermatozoal fertilizing capacity in vitro. These findings indicate that the seminal plasma PRL levels are significantly depressed in azoospermic subjects and suggest that the seminal plasma PRL may play a role in the maintenance of spermatozoal motility. Whether there is a potential function of prolactin in semen on spermatozoal fertilizing capacity, however, cannot be inferred from the present study.

Animals↗
PubMed1984

Lack of effect of exogenous prolactin on the fertilizing capacity of human spermatozoa in vitro.

The effect of exogenous prolactin (PRL) on the fertilizing capacity of human spermatozoa in vitro was evaluated by the zona-free hamster ova penetration assay. Bovine and ovine PRL, in both physiological and pharmacological concentrations, failed to increase the penetration after 5 hr of incubation in vitro. The percent motility of spermatozoa was not influenced by PRL during the incubation period. Exogenous PRL does not affect the fertilizing capacity of human spermatozoa in vitro. The role of prolactin, normally present in seminal plasma and female reproductive tract fluid, in the human spermatozoal capacitation process merits further investigation.

Animals↗
PubMed1984

Transient hyperprolactinaemia in human menopausal gonadotropin induction of ovulation.

In 20 anovulatory patients who were normoprolactinaemic, 12 developed transient hyperprolactinaemia when they were treated with human menopausal gonadotropin (hMG) for induction of ovulation. The hyperprolactinaemia was probably due to the increased oestrogen production effect on some susceptible patients. The pregnancy rate was found to be lower in those who developed this condition. The dosage of hMG required was found to be significantly higher in this group. The importance of recognizing this transient hyperprolactinaemia and the probably role of Bromocriptine are discussed. Further study is suggested.

Adult↗
PubMed1983

Effects of androgens on fertilizing capacity of human spermatozoa.

The potential functions of testosterone and 5 alpha-dihydrotestosterone, the androgens normally present in human seminal plasma, on human spermatozoal physiology were evaluated by studying the effects of these two steroid hormones on the in vitro fertilizing capacity of human spermatozoa. Spermatozoa collected from presumably fertile men were washed in BWW medium and incubated with different concentrations (0, 100, 250, 500, 1000 pg/ml) of testosterone or 5 alpha-dihydrotestosterone for 5 hr before insemination of the zona-free hamster ova. Penetration of the zona-free hamster ova was scored 6 hr later and the results were analyzed statistically. Both testosterone and 5 alpha-dihydrotestosterone, at the concentrations tested, significantly decreased the in vitro penetration of the denuded hamster ova in comparison to the controls (p less than 0.05). A dose-dependent response was also observed for the 5 alpha-dihydrotestosterone tested. These findings indicate that exogenous testosterone and 5 alpha-dihydrotestosterone can inhibit the fertilizing capacity of human spermatozoa in vitro, and suggest that the androgens normally present in human seminal plasma may serve, in part, to prevent premature spermatozoal capacitation before the spermatozoa reach the site of fertilization in vivo.

Animals↗
PubMed1983

Pre-operative cervical dilatation in termination of first trimester pregnancies using 16, 16-dimethyl-trans-delta 2 PGE1 methyl ester vaginal pessaries.

The effect of a prostaglandin E1 analogue on the cervix prior to termination of first trimester pregnancy was studied in a double-blind placebo-controlled trial with 70 primigravid and 125 multigravid patients in the Hong Kong University Gynaecological Unit. One mg of 16, 16-dimethyl-trans-delta 2-prostaglandin E1 methyl ester (ONO 802) in the form of vaginal pessary was inserted 3 hours before vacuum aspiration. The cervical dilatation in patients receiving ONO 802 pessaries was significantly greater than that in patients who received no treatment or placebo pessaries but the difference in dilatation between patients who received no treatment or placebo was not significant. The blood loss during operation in patients receiving ONO 802 pessaries was also significantly less than that in patients receiving placebo pessaries. The side effects due to ONO 802 pessaries were mild and infrequent.

Abortifacient Agents↗
PubMed1982

Abortion in single girls in Hong Kong.

Abortion in single girls in an increasing problem in Hong Kong. This paper is an attempt to look at the psychosocial factors in sexual behavior in a selected sample of girls. Of 100 girls requesting an abortion, 70% were educated to Form III level (grade 10 U.S. equivalent) and these did not come from broken or disturbed homes. The adequacy of their prepregnancy use of contraception was significantly and positively related to their level of formal education. These girls were all made pregnant by their boy-friends. Some aspects of their sexual behavior are described.

Abortion Applicants↗
PubMedDate not supplied

Seminal plasma beta-human chorionic gonadotropin (beta-HCG): relationships with seminal characteristics and spermatozoal fertilizing capacity.

Seminal plasma beta-human chorionic gonadotropin (beta-HCG) levels were determined in 254 semen samples collected from fertile and suspected subfertile men, and their relationships with seminal characteristics and spermatozoal fertilizing capacity were evaluated. Radioimmunoassayable beta-HCG, as defined by greater than 5 mIU/ml concentration, was demonstrated in only 44.5% of all the samples studied. beta-HCG concentrations were similar in normospermic, oligospermic and azoospermic samples. There were no significant differences in beta-HCG concentration between high-motility and low-motility samples, between normal-morphology and abnormal-morphology samples, and between high-fertilizing capacity and low-fertilizing capacity samples. No significant correlations between the concentrations of beta-HCG and individual parameters of semen analysis and spermatozoal fertilizing capacity among the various groups of samples were observed. The physiological role of seminal plasma beta-HCG is presently uncertain and the relationship of its determination to male fertility requires further investigation.

Chorionic Gonadotropin↗
PubMedDate not supplied

Spermatozoal fertilizing capacity in polyzoospermia: a preliminary study.

Men with the spermatological symptom of polyzoospermia (greater than 250 X 10(6) sperm/ml) have been reported to seldom impregnate their wives. It was the aim of this study to investigate the spermatozoal fertilizing capacity in polyzoospermia by the human sperm and zona-free hamster ova penetration bioassay. General semen characteristics and in vitro spermatozoal fertilizing capacity were studied in 12 polyzoospermic male partners of couples of infertile marriages. The results were compared with those from a control group of normospermic fertile men (n = 22). No significant differences in sperm motility, normal morphology and in vitro spermatozoal fertilizing capacity were found between the two groups. The polyzoospermic men we studied did not appear to have any defect with the spermatozoal fertilizing capacity, as assessed by the heterologous sperm--ova penetration bioassay. The apparent impairment of fertility and higher abortion rate in couples with polyzoospermic male partners, as described in the literature, may be related to chromosomal aberrations and/or other unknown functional defect of the spermatozoa.

Animals↗
PubMedDate not supplied

Prolactin in human cervical mucus.

The pattern of change in the levels of prolactin (PRL) in cervical mucus was studied in 19 normal ovulatory women. The concentration of PRL in cervical mucus was generally higher than that in plasma except at midcycle, when a reverse relationship was observed. The concentration of PRL in mucus obtained at midcycle was lower than mucus obtained during follicular phase or luteal phase. There were no significant differences in the total PRL content among preovulatory, midcycle and postovulatory cervical mucus samples. The amount of cervical mucus markedly increased during the periovulatory period (two days from the peak of plasma luteinizing hormone). The cervical mucus PRL level undergoes cyclic changes during the normal menstrual cycle, and the decrease in PRL concentration in mucus at midcycle is most likely a result of the dilutional effect of increased mucus volume. The physiological implication of the presence of PRL in human cervical mucus is also discussed.

Cervix Mucus↗
PubMedDate not supplied

Serum immunoreactive beta-endorphin in the human ovulatory cycle.

Daily serum immunoreactive beta-endorphin (IR-beta-EP) levels, in conjunction with luteinizing hormone, follicle-stimulating hormone, 17 beta-oestradiol, progesterone, and prolactin, were measured during the ovulatory cycle in five healthy Chinese women. Standardization of raw data by conversion to the statistical "Z scores" and composite plot of the five cycles showed that serum IR-beta-EP levels fluctuated during the follicular, late luteal, and menstrual phases. A preovulatory rise occurred two to three days prior to the luteinizing hormone surge, followed by a postovulatory dip for two to three days. The concentrations of IR-beta-EP were (mean +/- S.E.M.): 85.5 +/- 10.5 pg/mL (n = 36) in the follicular phase; 92.4 +/- 36.5 pg/mL (n = 5) in the ovulatory phase; 72.3 +/- 16.6 pg/mL (n = 7) in the early luteal phase; 100.0 +/- 10.7 pg/mL (n = 38) in the late luteal phase. The values in the luteal phase were the highest of any in the ovulatory cycle. The findings suggest that the fluctuation of endogenous beta-EP is under the influence of, among other factors, ovarian sex steroids. The significance of beta-EP in the regulation of gonadotropin release during normal menstrual cycles is discussed.

Adult↗