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Biomedical subjects

G W Tang

Publications and source records attributed to G W Tang.

At least 37 records · Page 2Linked to original sources
PubMed1991

Lymphocyte subsets in patients with oestrogen deficiency.

We have previously shown that in patients with idiopathic premature ovarian failure there were significant changes in lymphocyte subsets. To test our hypothesis that these changes were due to oestrogen deficiency we studied lymphocyte subsets in patients with oestrogen deficiency due to other causes. Blood was taken for serum oestradiol, lymphocyte counts and lymphocyte subset counts (CD2+, CD4+, CD8+ and B cells) before oestrogen replacement in 19 patients with gonadal dysgenesis, 22 patients with hypothalamic-pituitary failure and 24 healthy female control subjects. The CD4:CD8 ratio in both groups of patients was significantly lower than that in the normal control subjects while the percentages and counts of lymphocytes and CD8+ cells were significantly higher. There was a significant positive correlation between the serum oestradiol level and the CD4:CD8 ratio. These findings support the hypothesis that the changes in lymphocyte subsets are due to oestrogen deficiency.

Antigens, CD↗
PubMed1990

13-cis-retinoic acid is an endogenous compound in human serum.

The occurrence of 13-cis-retinoic acid as an endogenous component in human serum has been confirmed by cochromatography with standards in both normal-phase and reverse-phase high-performance liquid chromatographic (HPLC) system, by the lambda max of its UV spectrum recorded simultaneously with the HPLC run, and by chromatography of its methyl derivative. The method using solid-phase extraction followed by a gradient reverse-phase HPLC procedure with an internal standard and sensitive UV detector, provides an efficient and sensitive technique for the separation and quantification of serum 13-cis- and all-trans-retinoic acid. Serum levels of 13-cis- and all-trans-retinoic acid in 26 fasting volunteers ranged from 1.0 to 2.2 ng/ml (mean +/- SEM = 1.4 +/- 0.3 ng/ml) and from 1.1 to 1.9 ng/ml (mean +/- SEM = 1.4 +/- 0.2 ng/ml), respectively. The levels determined by a liquid-liquid double-phase extraction method were 90% higher in both 13-cis- and all- trans-retinoic acid than those from a solid-phase extraction. Human small intestine can isomerize all-trans-retinoic acid. 13-cis-Retinoic acid is the predominant cis isomer after incubation of intestinal mucosa homogenates with all-trans-retinoic acid. Moreover, the concentration of retinoic acid in serum is related to diet in that the level of total retinoic acid was 36% higher (n = 10) 2 h after a nonstandard breakfast than in fasting subjects.

Adult↗
PubMed1989

Rabbits fed on beta-carotene have higher serum levels of all-trans retinoic acid than those receiving no beta-carotene.

The aim of the present work was to determine the effect of giving increasing doses of supplements of beta-carotene on serum retinoic acid levels in rabbits. Four groups of 7-week-old female rabbits were fed for 9 weeks on a pelleted diet containing 1.72 mg vitamin A as retinyl acetate/kg and including control gelatin beadlets devoid of beta-carotene or 1, 2 or 4 mg beta-carotene/kg body-weight per d. Serum was collected at 3, 6 and 9 weeks after the beginning of the experiment and the concentration of all-trans retinoic acid was determined by a gradient reverse-phase high-performance liquid chromatography system following a double-phase extraction. The average concentration of retinoic acid in serum of the combined control and 1 mg beta-carotene/kg groups was 3.80, 3.06 and 2.40 nM at 3, 6 and 9 weeks respectively. The concentrations of retinoic acid in serum of the combined 2 and 4 mg beta-carotene/kg groups were 4.80 nM (P less than 0.05), 3.76 nM (not significant) and 4.90 nM (P less than 0.005) at 3, 6 and 9 weeks respectively. A SAS (SAS Institute Inc., 1985) general linear model repeated-measures analysis of variance revealed that the effects of treatment (P less than 0.01), time (P less than 0.05) and treatment x time interaction (P less than 0.05) were statistically significant. It is concluded that giving beta-carotene is associated with higher concentrations of all-trans retinoic acid in the serum of rabbits than in those receiving no beta-carotene.

Animals↗
PubMed1989

Gonadal dysgenesis: a review of 15 years' management.

Fifteen years' experience in a Menstrual Disorder Clinic revealed that gonadal dysgenesis was the commonest cause of primary amenorrhoea. Investigations using Barr Body study and laparoscopic examination were unsatisfactory and inaccurate. The invasive nature of laparoscopy was the likely principal cause for the high default rate in the early years of the Clinic. The availability of hormone radioimmunoassay and cytogenetic study has improved the diagnostic acuity. Gonadal malignancy associated with the "Y" chromosome could also be identified at its early stage. Oestrogen replacement therapy has been found to be beneficial and is associated with little side effects and no endometrial pathology has been identified.

Adolescent↗
PubMed1988

Non-surgical sterilization using phenol-mucilage: acceptability versus efficacy.

Sterilization has become a popular means of birth control and many methods have been developed to meet the needs of different groups of women. In a pilot study, non-surgical sterilization using phenol-mucilage was found to be extremely acceptable to a group of Chinese women despite its failure rate. The method is simple, safe and inexpensive. It is suggested that this method would be suitable for women who are afraid of surgical sterilization.

Adhesives↗
PubMed1988

Diagnosis of early pregnancy by enzyme immunoassay of Schwangerschafts-protein 1.

Serum Schwangerschafts-protein 1 (SP1) and beta subunit of human chorionic gonadotropin (beta-hCG) were measured by enzyme immunoassay and radioimmunoassay, respectively, in the follicular phase and luteal phase of 50 human menopausal gonadotropin treatment cycles. SP1 could be detected in 63% of blood samples taken in the follicular phase up to the level of 1.56 micrograms/l. Using a cutoff level of 2 micrograms/l, SP1 could be used to diagnose pregnancy 16 to 25 days after the ovulating dose of hCG. The serum SP1 level is not affected by hCG injections and it can be used for diagnosis of pregnancy even when hCG has been given recently. SP1 also may be used as a prognostic indicator of the outcome of the pregnancy.

Abortion, Spontaneous↗
PubMed1988

Further evaluation of first morning urinary oestrogen in monitoring gonadotrophin therapy.

Efficient gonadotrophin therapy requires both biochemical and ultrasonic measurements of ovarian response. Biochemical monitoring can take the form of measurement of plasma oestradiol levels or urinary oestrogen excretion. Levels of first morning urinary oestrogen to creatinine ratio have been shown to correlate well with 24-hour total urinary oestrogen excretion. Such urine collection is not cumbersome and is less invasive than daily venepuncture. Eighty gonadotrophin treatment cycles were evaluated by first morning urinary oestrogen to creatinine ratio and ultrasound scanning of follicles. Analysis confirmed that the ratio correlated significantly both with plasma oestradiol and 24-hour urinary oestrogen levels. The administration of the ovulating dose of human chorionic gonadotrophin depended primarily on ultrasonic demonstration of the presence of mature follicles in the ovaries. There was no increased incidence of multiple gestation or hyperstimulation syndrome in 135 treatment cycles. It is concluded that first morning urinary oestrogen to creatinine ratio is a convenient and cheap method of efficient biochemical monitoring of ovarian response to gonadotrophin therapy.

Chorionic Gonadotropin↗
PubMed1988

Immunologic studies in patients with premature ovarian failure.

Tests for a range of autoantibodies, and counts of lymphocytes, B cells, T cells, and T cell subsets were performed in 45 Chinese patients with premature ovarian failure and 45 age-matched normal control subjects. Eight patients (18%) were positive for at least one autoantibody. Only one patient was positive for antiovarian antibody. Patients with autoantibodies had a significantly higher percentage of circulating B cells. The lymphocyte, T cell, CD4+, and CD8+ counts in patients with premature ovarian failure were significantly higher than those in the control group, but the CD4:CD8 ratio was significantly lower in women with premature ovarian failure. There was a significant negative correlation between plasma estradiol levels and CD8+ counts, and a significant positive correlation between plasma estradiol levels and CD4:CD8 ratios. The changes in lymphocytes and lymphocyte subpopulations in premature ovarian failure may be due to estrogen deficiency.

Adult↗
PubMed1987

Plasma levels of immunoreactive melatonin, estradiol, progesterone, follicle stimulating hormone, and beta-human chorionic gonadotropin during pregnancy and shortly after parturition in humans.

Plasma concentrations of immunoreactive melatonin, estradiol, progesterone, follicle stimulating hormone (FSH), and beta-human chorionic gonadotropin (beta hCG) were studied between 1000 and 1230 h in 105 Chinese females during six periods of normal pregnancy and 1-5 min after normal delivery. We have also examined the midday levels of immunoreactive melatonin in the cord blood of fetuses and plasma collected 1-5 min after and 24 h after delivery from their mothers. Concentrations of hormone immunoreactivities were determined by radioimmunoassay, and distinct fluctuations of all hormones were recorded during pregnancy. In the pregnant females, there were significant negative correlations between melatonin and estradiol, melatonin and progesterone, beta hCG and progesterone, and beta hCG and estradiol, and positive correlations between melatonin and FSH and progesterone and estradiol. Furthermore, plasma melatonin levels in the cord blood demonstrated no sex difference and were significantly lower than and correlated positively with the levels in their mothers. Our results suggest that sex steroids may inhibit and FSH may potentiate circulating melatonin levels in gravid women; changes in the levels of melatonin during pregnancy may affect the in utero development of the human embryo; and circulating melatonin in the mother may be the major source of blood melatonin in the fetus before parturition.

Chorionic Gonadotropin↗
PubMed1986

Vacuum extractor: a safe instrument?

One thousand five hundred and twenty-six records of deliveries with vacuum extractor in 1982 and 1983 in the Hong Kong University Department of Obstetrics and Gynaecology were reviewed. Vacuum extractor was found to be easy and safe to use even by inexperienced house-staff. Vacuum extractor was especially useful in the delivery of malpositioned fetal heads because of its mechanism of allowing autorotation. Its advantage of not occupying extra space in the pelvis was most beneficial to the relatively smaller Chinese pelvis. Maternal injury was uncommon. Fetal scalp injury like cephalhaematoma was not uncommon but serious scalp injury was infrequent. Perinatal mortality rate attributed to the instrument was low (0.6/1,000). However, in order to achieve safety to the mother and fetus, strict rules in application of the vacuum extractor must be observed.

Apgar Score↗
PubMed1986

Psychosocial aspects of gestational trophoblastic disease in Chinese residents of Hong Kong.

Gestational trophoblastic disease has several special aspects as compared with others tumors of the female genital tract. It occurs in young women who want to start a family and expect to have a normal pregnancy. It can be very effectively treated with chemotherapeutic agents, and the subsequent reproductive potential of these young women is not affected. In a survey of 105 Chinese residents of Hong Kong who had had the disease, it was found that their emotional reactions to the disease and treatment, the effects of such on their self-esteem, martial and sexual life, and their attitudes towards their physicians and future pregnancy were different from those of their Western counterparts.

Adolescent↗
PubMed1985

The relationship between the human sperm hypoosmotic swelling test, routine semen analysis, and the human sperm zona-free hamster ovum penetration assay.

The functional integrity of sperm membranes of 270 semen samples collected from fertile men and the male partners in couples with infertile marriages was assessed by the hypoosmotic swelling test and the results correlated with routine semen analysis and the human sperm zona-free hamster ovum penetration assay. Semen samples with abnormal semen parameters had lower values of percentage of swollen sperm after hypoosmotic treatment in comparison with those with normal semen parameters. A weak positive correlation was observed between sperm swelling and sperm morphologic features (r = 0.32, P less than 0.05) and between sperm swelling and sperm motility (r = 0.22, P less than 0.05). Insignificant correlation was observed between sperm swelling and in vitro sperm fertilizing capacity, as assessed by the zona-free hamster ovum penetration assay. The results indicate that the sperm swelling test and the zona-free hamster ovum penetration assay are evaluating different functional qualities of sperm that are apparently not associated with each other.

Animals↗
PubMed1985

Reactions to emergency hysterectomy.

The recovery from emergency hysterectomy of 18 Chinese patients is described. During the recovery period, patients experienced fear, depression, anger, doubt, selfreproach, and multiple somatic complaints without physical origins. Sexual activity was reduced. The recovery course was particularly difficult for those patients who were nonsymptomatic before operation, those who still wanted to bear more children, and those who lacked family support. These women needed continuous reassurance and ample opportunities to ventilate their feelings. None of the patients had psychiatric sequelae requiring expert consultation after the operation. It is emphasized that the reactions and needs of these patients deserve recognition, attention, and follow-up.

Adult↗