ADAP is a possible negative regulator of glucosinolate biosynthesis in Arabidopsis thaliana based on clustering and gene expression analyses.

Glucosinolates (GSLs) are plant secondary metabolites consisting of sulfur and nitrogen, commonly found in Brassicaceae crops, such as Arabidopsis thaliana. These compounds are known for their roles in plant defense mechanisms against pests and pathogens. 'Guilt-by-association' (GBA) approach predicts genes encoding proteins with similar function tend to share gene expression pattern generated from high throughput sequencing data. Recent studies have successfully identified GSL genes using GBA approach, followed by targeted verification of gene expression and metabolite data. Therefore, a GSL co-expression network was constructed using known GSL genes obtained from our in-house database, SuCComBase. DPClusO was used to identify subnetworks of the GSL co-expression network followed by Fisher's exact test leading to the discovery of a potential gene that encodes the ARIA-interacting double AP2-domain protein (ADAP) transcription factor (TF). Further functional analysis was performed using an effective gene silencing system known as CRES-T. By applying CRES-T, ADAP TF gene was fused to a plant-specific EAR-motif repressor domain (SRDX), which suppresses the expression of ADAP target genes. In this study, ADAP was proposed as a negative regulator in aliphatic GSL biosynthesis due to the over-expression of downstream aliphatic GSL genes (UGT74C1 and IPMI1) in ADAP-SRDX line. The significant over-expression of ADAP gene in the ADAP-SRDX line also suggests the behavior of the TF that negatively affects the expression of UGT74C1 and IPMI1 via a feedback mechanism in A. thaliana.

Recent advances in exploitation of nanomaterial for arsenic removal from water: a review.

Recently, increasing research efforts have been made to exploit the enormous potential of nanotechnology and nanomaterial in the application of arsenic removal from water. As a result, there are myriad of types of nanomaterials being developed and studied for their arsenic removal capabilities. Nevertheless, challenges such as having a complete understanding of the material properties and removal mechanism make it difficult for researchers to engineer nanomaterials that are best suited for specific water treatment applications. In this review paper, a comprehensive review will be conducted on several selected categories of nanomaterials that possess promising prospects in arsenic removal application. The synthesis process, material properties, as well as arsenic removal performance and removal mechanisms of each of these nanomaterials will be discussed in detail. Fe-based nanomaterials, particularly iron oxide nanoparticles, have displayed advantages in arsenic removal due to their super-paramagnetic property. On the other hand, TiO2-based nanomaterials are the best candidates as photocatalytic arsenic removal agents, having been reported to have more than 200-fold increase in adsorption capacity under UV light irradiation. Zr-based nanomaterials have among the largest BET active area for adsorption-up to 630 m2 g-1-and it has been reported that amorphous ZrO2 performs better than crystalline ZrO2 nanoparticles, having about 1.77 times higher As(III) adsorption capacity. Although Cu-based nanomaterials are relatively uncommon as nano-adsorbents for arsenic in water, recent studies have demonstrated their potential in arsenic removal. CuO nanoparticles synthesized by Martinson et al were reported to have adsorption capacities up to 22.6 mg g-1 and 26.9 mg g-1 for As(V) and As(III) respectively. Among the nanomaterials that have been reviewed in this study, Mg-based nanomaterials were reported to have the highest maximum adsorption capacities for As(V) and As(III), at 378.79 mg g-1 and 643.84 mg g-1 respectively. By combining desired properties of different nanomaterials, composite nanomaterials can be made that have superior potential as efficient arsenic removal agents. Particularly, magnetic composite nanomaterials are interesting because the super-paramagnetic property, which allows efficient separation of nano-adsorbents in water, and high adsorption capacities, could be achieved simultaneously. For instance, Fe-Mn binary oxide nanowires have shown promising As(III) adsorption capacity at 171 mg g-1. Generally, nanomaterials used for arsenic removal face severe degradation in performance in the presence of competing ions in water, especially phosphate ions. This study will contribute to future research in developing nanomaterials used for arsenic removal that are highly efficient, environmentally friendly and cost-effective by providing a thorough, structured and detailed review on various nanomaterial candidates that have promising potential.

Interspace/interdental brushes for oral hygiene in orthodontic patients with fixed appliances.

BACKGROUND: Accumulation of plaque on tooth surfaces that have fixed orthodontic appliances is increased. Effective removal is essential to maintain oral health but it is unclear whether the use of interdental or interspace brushes is useful. OBJECTIVES: To compare the effectiveness of standard toothbrushes with combined standard toothbrushes and interdental/interspace brushes used by patients during fixed orthodontic appliances therapy in relation to plaque removal, the health of dental and supporting tissues, dependability, cost and adverse effects. SEARCH STRATEGY: We searched the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE, EMBASE and CINAHL. Schools of dental hygiene were contacted for additional data. No language restrictions were applied. Handsearching of the relevant journals was carried out. Most recent search: January 2006. SELECTION CRITERIA: Randomised controlled trials (RCTs) including the following criteria: participants - patients with fixed orthodontic appliances and uncompromised manual dexterity; intervention - unsupervised toothbrushing with standard toothbrush alone versus standard toothbrush and interdental/interspace brush. Primary outcomes were differences in plaque control, gingival health and decalcification. DATA COLLECTION AND ANALYSIS: Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were to be conducted in duplicate and independently. Trials were to be grouped in terms of their interventions and outcome measures. Results were to be expressed as random-effects models using standardised mean differences for continuous outcomes and risk ratios for dichotomous outcomes with 95% confidence intervals. Heterogeneity was to be investigated. MAIN RESULTS: No studies were identified to support or contest the null hypothesis. AUTHORS' CONCLUSIONS: The present practice of recommending the use of interdental/interspace brushes in addition to standard toothbrushes is not supported by clinical investigations. Interdental brushes and normal toothbrushes wear is increased during orthodontic treatment and brushes need to be replaced more frequently. This increases the economic burden of oral hygiene products for the patient. Well designed RCTs are required to provide evidence for determining clinical practice in this area.

Metabolite profiling reveals temperature effects on the VOCs and flavonoids of different plant populations.

Temperature is one of the key factors in limiting the distribution of plants and controlling major metabolic processes. A series of simulated reciprocal transplant experiments were performed to investigate the effect of temperature on plant chemical composition. Polygonum minus of different lowland and highland origin were grown under a controlled environment with different temperature regimes to study the effects on secondary metabolites. We applied gas chromatography-mass spectrometry and liquid chromatography time-of-flight mass spectrometry to identify the chemical compounds. A total of 37 volatile organic compounds and 85 flavonoids were detected, with the largest response observed in the compositional changes of aldehydes and terpenes in highland plants under higher temperature treatment. Significantly less anthocyanidin compounds and larger amounts of flavonols were detected under higher temperature treatment. We also studied natural variation in the different plant populations growing under the same environment and identified compounds unique to each population through metabolite fingerprinting. This study shows that the origin of different plant populations influences the effects of temperature on chemical composition.

Effects of sex steroids on the positive estrogen feedback mechanism in intact women and castrate men.

We studied the effects of prolonged testosterone treatment on ovulatory function and positive estrogen feedback in women and of prolonged estrogen priming on gonadotropin feedback in castrate men. An estrogen provocation test was carried out in 4 groups of transsexual subjects: 12 female transsexuals in their early follicular phase (days 3-5; group 1A), 8 females who had been treated with Depo-testosterone (T) for 3-6 months (group 1B), 11 men who had been castrated 3 months previously (group 2A), and 4 male castrates treated with oral estrogen for 3 months starting 3 months after castration (group 2B). The estrogen provocation test consisted of 3 GnRH tests (100 micrograms) carried out immediately before (0 h) and 44 and 92 h after an im injection of estradiol valerate (10 mg). Responses to the estrogen provocation test in women with normal menstrual cycles (group 1A) were typically female. After initial suppression at 44 h, a LH surge (positive feedback) occurred at 92 h. Pituitary responsiveness, however, was amplified both at 44 and 92 h. Prolonged T priming of women in group 1B did not inhibit the estrogen-induced LH surge, nor was the amplitude of the surge blunted. Removal of androgens and other testicular factors (group 2A) did not result in the appearance of an estrogen-induced LH surge. On the other hand, prolonged estrogen priming in male castrates (group 2B) resulted in activation of the positive feedback mechanism; a LH surge in response to the estrogen provocation occurred. The results of the present study imply that 1) contrary to an earlier suggestion, testosterone does not block or blunt the LH surge, indicating that it is probably not responsible for suppressing the LH surge in normal men; 2) testosterone can cause ovulatory failure without suppressing the LH surge in women; and 3) prolonged estrogen priming may be involved in activation of the positive feedback mechanism in humans.

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.

Quantitative comparison of prolactin production by decidua compacta and spongiosa from the first trimester elective termination of pregnancy.

Prolactin (PRL) producing capacity was studied in explants of decidua compacta and decidua spongiosa obtained from 41 patients undergoing termination of pregnancy at gestation 6 to 12 weeks. In vitro PRL producing capacity, expressed as mIU/g protein, of the decidua compacta was significantly higher (P < 0.05) than those of decidua spongiosa. Production of PRL increased with gestation from 6 to 12 weeks with a more rapid rate at the later gestation. The pattern of increase fitted significantly (P < 0.0001) to the exponential model for both decidua compacta and decidua spongiosa. The exponential regression equations for decidua compacta and decidua spongiosa were (ln y = 4.25 + 0.19x) and (ln y = 2.80 + 0.31x) respectively. Hence, although both decidua compacta and decidua spongiosa had a similar pattern of increase in PRL production, the rate of increment was significantly greater in decidua spongiosa than in decidua compacta. These findings suggest that separating decidua compacta and decidua spongiosa of the first trimester would reduce the heterogeneity of decidual tissue and offer a new approach to the studies of the synthesis, release and regulation of PRL production by human decidua.

Luteinizing hormone surge in adult female rats after androgen priming.

The effects of androgens alone and in combination with oestrogens on luteinizing hormone secretion in adult female rats were studied after 1, 2 and 4 months of priming. Each adult female rat was implanted with a Silastic capsule filled with testosterone or dihydrotestosterone alone or together with another similar capsule of oestradiol. An oestrogen challenge test was carried out in each rat after priming. Blood samples were collected before androgen priming. During the oestrogen challenge test, blood samples were collected before (0 h or day 0) and at 12, 24, 36 and 48 h after the intramuscular injection of 50 µg oestradiol vaierate for rats primed for 1 month, or daily for 5 days (days 1 to 5) for other rats. An oestrogen challenge test was also performed in two groups of untreated male and female rats which served as controls. The results indicated that long-term androgen priming had resulted in the attenuation or total blockade of the luteinizing hormone surge which normally occurs during an oestrogen challenge test in adult female rats. This suggests that androgens may be important modulators of the luteinizing hormone surge mechanism in rats. Furthermore, the fact that the luteinizing hormone surge can be blocked by androgen priming in adult female rats suggests that the sexual dimorphic response to oestrogen feedback is not immutably imprinted in the hypothalamic-pituitary axis as was originally proposed.

Effects of hormone deficiency, androgen therapy and calcium supplementation on bone mineral density in female transsexuals.

A total of 79 healthy female transsexuals, divided into four groups, were involved in this study. Group 1 comprised 15 pre-operated normal cycling females; Group 2, five pre-operated females who were on regular androgen therapy for 1-3 years; Group 3, 27 post-operated females who were on regular androgen therapy for 2-12 years; and Group 4, 32 post-operated females who either had stopped or were on irregular androgen therapy. A bone scan of the lumber spine, at positions L2-L4, was carried out for each subject. A blood sample was taken for measurement of plasma testosterone concentrations. Ten subjects from Group 3 had a repeat bone scan following 10-39 months of calcium supplement (625 mg daily as calcium carbonate); another 10 post-operated females of Group 3 had a repeat bone scan 6-59 months later; and five subjects from Group 4 had a repeat scan following resumption of regular androgen therapy for 17-27 months. The mean +/- SE concentrations of testosterone of Groups 1-4 were, respectively, 0.58 +/- 0.05, 10.1 +/- 2.48, 7.7 +/- 0.98 and 0.99 +/- 0.14 ng/ml. Pre-operated females (Group 2) following 1-3 years of regular androgen therapy had significantly higher BMD and age-matched BMD than corresponding levels in pre-operated normal cycling females in Group 1. While the age-matched BMDs of post-operated females, who were on regular androgen therapy, were not significantly different, the mean BMD was significantly lower than corresponding values in the controls of Group 1. Post-operated females in Group 4 had significantly lower BMDs and age-matched BMDs as compared to corresponding values in controls of Group 1. The BMDs and age-matched BMDs of post-operated females, who were on regular androgen therapy, were significantly raised following daily calcium supplementation for durations ranging from 10-39 months. A repeat bone scan carried out following a lapse of 6-59 months did not reveal any significant change in the BMDs and age-matched BMDs of 10 post-operated females on regular androgen therapy. On the other hand, the BMDs and age-matched BMDs of post-operated females in Group 4 were significantly raised following the resumption of regular androgen therapy for 17-27 months. Results of the present study showed that ovariectomy and remaining in the hormone-deficient state for a sufficiently long duration was associated with a definite loss of bone mass. However, it was shown in this study that the resumption of regular androgen therapy for a sufficient duration could arrest this loss and, additionally, substantially increase the bone mass. Androgen appears to have a potentially greater impact on bone mass than oestrogen. Furthermore, calcium supplementation in a Singaporean population, which is accustomed to a low dietary calcium intake, can assist in the accretion of a higher bone mass in an adult population.

The impact of long-term testosterone replacement therapy on lipid and lipoprotein profiles in women.

The lipid and lipoprotein profiles of 39 female transsexuals, exposed to testosterone esters (250 mg monthly) for an average duration of 33 months after their sex reassignment operation (group 2), were compared to those of 29 normal menstruating female transsexuals prior to starting androgen therapy (group 1). A third group, comprising 17 post-operative female transsexuals were studied while on, and after stopping their androgen therapy for 6-12 months (group 3). The average concentration of testosterone in androgenized women was comparable to those found in normal males and levels of SHBG were significantly lower than those in the control group. No significant difference was noted between all levels of lipids and lipoproteins in pre-operative subjects of group 1 and corresponding levels in subjects of group 3 after they had stopped their androgen therapy for 6-12 months. Significantly higher levels of triglyceride (Trig), total cholesterol (TC), low-density lipoprotein (LDL-C) and apolipoprotein-B (Apo B) and a significantly lower level of high-density lipoprotein-cholesterol (HDL-C) were noted in androgenized women (group 2) when compared to controls (group 1). The two atherogenic indices, LDL-C/HDL-C and Apo-AI/Apo-B were significantly raised and lowered, respectively. Similar results were noted when comparing lipid and lipoprotein profiles in subjects of group 3 while they were on and after stopping their androgen therapy. Results from this study indicate that testosterone, per se, at supraphysiological doses may promote atherogenicity in women. Furthermore, the male predilection for coronary vascular diseases (CVD) may be due to the adverse effects of higher androgen levels on lipid and lipoprotein profiles.

Endocrine effects in Asian postmenopausal women treated with SH D 461 M and Prempak-C.

We reported the results of a randomized cross-over study comparing SH D 461 M (Climen) and Prempak-C in 38 postmenopausal women who were established users of hormone replacement therapy (HRT). Climen contains 11 tablets of 2 mg estradiol valerate (EV), and 10 tablets with 2 mg EV plus 1 mg of cyproterone acetate. Prempak-C, on the other hand, is a regime consisting of 28 tablets of 0.625 mg conjugated equine estrogens (CEE); the last 12 tablets are taken together with 0.15 mg of norgestrel (NG) tablets. Patients in Sequence I started with Climen for 6 months and then crossed-over to Prempak-C, for the next 6 months; patients in Sequence II, followed the reverse order. Following Climen treatment, significantly higher levels (P < 0.05, t-test) of sex hormone binding globulin (SHBG) and estradiol, when compared to Prempak-C treated subjects, were noted. No significant differences in follicle stimulating hormone (FSH), corticosteroid binding globulin (CBG), renin, angiotensinogen, angiotensin-I and aldosterone levels between the two treatment regimes were noted. While both regimes were effective in reducing menopausal symptoms, none of the regimes could eliminate all symptoms completely. Treatment with Climen appeared to result in less frequent occurrences of some symptoms. During periods of no estrogen (only true for Climen) as well as periods of maximum progestagen and estrogen (P and E), subjects on Climen had significantly lower incidence of some of the symptoms (backache, lack of concentration, lethargy and swelling) when compared to those on Prempak-C.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrine effects in Asian postmenopausal women, treated with SH D 461 M and Prempak-C.

We reported the results of a randomized cross-over study comparing SH D 461 M (Climen) and Prempak-C in 38 postmenopausal women who were established users of hormone replacement therapy (HRT). Climen contains 11 tablets of 2 mg estradiol valerate (EV), and 10 tablets with 2 mg EV plus 1 mg of cyproterone acetate. Prempak-C, on the other hand, is a regimen consisting of 28 tablets of 0.625 mg conjugated equine estrogens (CEE); the last 12 tablets are taken together with 0.15 mg of norgestrel (NG) tablets. Patients in Sequence I started with Climen for 6 months and then crossed-over to Prempak-C, for the next 6 months. Patients in Sequence II followed the reverse order. Following Climen treatment, significantly higher levels (P < 0.05, t-test) of sex hormone binding globulin (SHBG) and estradiol, when compared to Prempak-C treated subjects, were noted. No significant differences in follicle stimulating hormone (FSH), corticosteroid binding globulin (CBG), renin angiotensinogen, angiotensin-I and aldosterone levels between the two treatment regimens were noted. While both regimens were effective in reducing menopausal symptoms, none of the regimens could eliminate all symptoms completely. Treatment with Climen appeared to result in less frequent occurrences of some symptoms. During periods of no estrogen (only true for Climen) as well as periods of maximum P and E, subjects on Climen had significantly lower incidence of some of the symptoms (backache, lack of concentration, lethargy and swelling) when compared to those on Prempak-C.(ABSTRACT TRUNCATED AT 250 WORDS)

The gonadotrophin surge in humans: its mechanism and role in ovulatory function--a review.

The presence of the positive feedback by oestrogen resulting in the mid-cycle gonadotrophin surge in women distinguishes the female's feedback control of gonadotrophin secretion from that in males. The gonadotrophin surge is an event crucial for final oocyte maturation, ovulation and subsequently for corpus luteum function. In this article, the roles of oestrogen, progesterone and testosterone in the regulation of the gonadotrophin surge are reviewed. Evidences appear to support the suggestion that an oestradiol pulse of sufficient potency and lasting for an adequately long duration alone is sufficient to trigger off the LH surge. Progesterone has a biphasic effect on LH secretion, and although not required for the initiation of the LH surge, may play a role in maintaining the LH peak. Testosterone, on the other hand, does not modulate the LH surge mechanism in man. Dysfunction of the gonadotrophin surge mechanism may account for some forms of ovulatory disorders: amenorrhoea and in some cases of delayed or precocious puberty. In patients with polycystic ovary syndrome (PCOS), different degrees of dysfunction of the gonadotrophin surge mechanism have been shown.

Steroidogenesis in hydatidiform mole--sources of androgens.

Plasma concentration of testosterone is significantly higher in patients with a molar pregnancy than in those with a normal pregnancy at similar gestation. The source of this raised level of testosterone has been controversial with some suggesting the molar trophoblast while others, the hyperstimulated ovary as the main contributor. We have carried out a series of investigations involving measurements of testosterone levels in plasma before and after evacuation of the uterus and in fluid from molar vesicle and lutein cyst. Furthermore, in vitro study on the conversion of androstenedione and dehydroepiandrosterone (DHEA) to testosterone and in vivo conversion of DHEA to testosterone and oestradiol before and after evacuation of the mole were conducted. Considering all the evidence together, it appears that the hyperstimulated ovary is probably the major source of the raised concentration of testosterone in molar pregnancy. On the other hand, although the molar trophoblast also makes some contribution as in normal pregnancy, the molar trophoblast is essential for the production of oestrogens.

Plasma concentration of steroid hormones after intravenous infusion of testosterone in castrated male transsexuals.

Ten male transsexuals who had surgical operations for sex-reassignment at least three months previously were given intravenous infusion of 2.4 mg (7 subjects) or 12 mg (3 subjects) testosterone over a period of seven hours. In both groups, plasma levels of testosterone and oestradiol measured by radioimmunoassay were significantly elevated one hour after the start of the infusion and remained raised throughout the infusion period. With the lower rate of infusion, plasma levels of testosterone rose from 0.6 ng/ml to 7.4 ng/ml, oestradiol from 16.2 pg/ml to 22.4 pg/ml while levels of androstenedione remained unchanged. When 12 mg testosterone was infused, the level of this hormone was elevated from 0.5 ng/ml to 29.6 ng/ml, while oestradiol increased from 16.5 pg/ml to 45.0 pg/ml. These results indicate that when physiological doses of testosterone are infused, conversion to oestradiol contributes to approximately 13.5% of total circulating oestradiol in men.

Long-term oestrogen priming on basal and oestradiol-induced release of luteinising hormone secretion in male rats.

The response of prolonged oestrogen priming (by silastic implants) of the male rat hypothalamic-pituitary axis (HPA) to an oestrogen challenge test was investigated. Basal LH levels were suppressed to a maximum at two months and remained unchanged by four months. In contrast to response in human, oestrogen priming had failed to stimulate a positive feedback response to an oestrogen challenge test in the male rats. Instead, oestrogen priming might have attenuated the negative LH feedback response. Increasing the dose of oestrogen priming by increasing the duration was not effective in inducing positive feedback in the male rats. The failure of these priming regimes to stimulate positive feedback in male rats may reaffirm our earlier suggestion that oestrogen does not play an important role in activating the cyclic centre in rats. This would also contradict the suggestion that testicular secretions may have acted through conversion to oestradiol in the suppression of the cyclic system in males during the critical period of differentiation of the HPA.

Oogenesis, fertilisation and early embryonic development in rats. I: Dose-dependent effects of pregnant mare serum gonadotrophins.

Five hundred and eight mature female Wistar rats divided into 35 different groups were stimulated with pregnant mare serum gonadotrophins (PMSG) (0, 5, 10, 20 & 40 IU) at the late diestrus stage to induce multiple follicular development. No chorionic gonadotrophin (CG) was used for ovulation induction. The quality of oocytes and their in vitro fertilisability, quality of Day 2-embryos, viability of pregnancy and status of fetuses on Day 14 of gestation and status of embryos retrieved on Day 2, 3, 4 and 5 of pregnancy in different subgroups of rats were examined. Results showed that more oocytes and embryos fertilised in in vivo were retrieved from rats supraphysiologically stimulated with 20 IU of PMSG. However, concurrent with the larger number, higher proportions of abnormal oocytes and embryos were found. High doses of PMSG caused lower in vitro fertilisability of oocytes and greater degrees of embryonic degeneration. Although, the number of oocytes and Day 2-embryos were higher in the 20PMGS dose group, the pregnancy rate was significantly reduced to 27%. In the 40PMSG group no viable pregnancy was noted. Most embryo demise occurred by day 3-5 of pregnancy, probably within the oviducts and before the implantation stage. In rats supraphysiologically stimulated with 20 and 40 IU of PMSG, the number of morphologically normal looking embryos was greatly reduced by Day 3-5 of pregnancy. In the 40PMSG group, there were no embryos retrieved by Day 4 and 5.(ABSTRACT TRUNCATED AT 250 WORDS)

Oogenesis, fertilisation and early embryonic development in rats. II: Dose-dependent effects of human chorionic gonadotrophin.

A total of 950 female Wistar rats in 81 groups were involved in this study. Different groups of rats were stimulated with PMSG (0, 10 & 20 IU) at diestrus followed, 48-52 hr later, by different doses of HCG (0, 10, 20, 30 & 40) for ovulation induction. The dose-dependent effects of HCG, either with or without the use of PMSG for stimulation of multiple follicular development, on the quality of oocytes and their in vitro fertilisability, quality of Day 2-embryos, viability of pregnancy and status of embryos retrieved on Day 2, 3, 4 or 5 of pregnancy in different subgroups of rats were examined. Results showed that more oocytes and embryos fertilised in vivo were retrieved from rats supraphysiologically stimulated with 20 IU of PMSG. The addition of HCG did not increase the number of ovulated oocytes or Day-2 embryos. In other words, the number of oocytes or embryos produced is dependent on the dose of PMSG administered during diestrus rather than on the dose of HCG given for ovulation induction. Hence, no increase in the amount of HCG is required to effectively ovulate bigger cohort of preovulatory follicles in supraphysiologically stimulated rats. As was shown earlier, in vitro and in vivo fertilisation rates were reduced when higher doses of PMSG were used. Similarly, these rates were reduced when increasing doses of HCG were used in rats not previously stimulated with PMSG. When higher doses of HCG were used in rats stimulated earlier with PMSG (10 and 20 IU), the in vitro but not the in vivo fertilisation rates were further reduced.(ABSTRACT TRUNCATED AT 250 WORDS)

Contributions to reproductive medicine through in-vitro fertilization: a review.

In vitro fertilization (IVF) is now an accepted treatment procedure for subfertility. Its use has also contributed greatly to the understanding of our knowledge in reproductive medicine. This review looks at these contributions. In the female, IVF has made it possible to examine more closely ovarian physiology through the follicular micro-environment, follicular dominance and cohorts. In the male, the new sperm preparation technology has assisted the investigation of sperm parameters in-depth. A better understanding of human egg and sperm physiology, the fertilization process and pre-implantation phenomena has also contributed to better management of the infertile couple. Perhaps in the future, the pre-implantation embryo may be considered as a "patient".

Research and development in obstetrics & gynaecology in the Department of Obstetrics & Gynaecology at the National University of Singapore.

This is a review of the research and achievements of the Department of Obstetrics and Gynaecology, National University of Singapore since 1949. The research activities reviewed are Fertility Control, Subfertility, Reproductive Endocrinology, In-Vitro Fertilization, Trophoblastic Disease, Prostaglandins and Perinatal Medicine. The University Department has kept abreast with the Singapore norm of two-child families by providing the most sophisticated technology and expertise. The perinatal mortality and stillbirth rates have been reduced to 11 and 6 per thousand births. Prostaglandin research in the Department includes an investigation of the involvement of these substances in various physiological processes, pharmacological studies with different prostaglandins and development of clinical applications. Between 1974 and 1981 we had studied 12 intrauterine contraceptive devices, both on a departmental basis and in conjunction with international agencies. The newer medicated devices have proved to offer significant advantages over the original inert plastic configuration. Metabolic changes in Singapore women on the oral pill and injection Depoprovera were studied. Impaired glucose tolerance and raised fasting total lipids were found in women on the pill. Marginal changes in carbohydrate metabolism only were found in women on injection Depoprovera. Hypercoagulation changes in the blood occurring in Singapore women varied with the dose of the synthetic or natural oestrogen medication. Initially, the fibrinolytic activity was enough to compensate for these changes; however after two years there were signs of decompensation. Progestogens affect coagulation via their influence on the liver functions. Hypercoagulation changes also occurred in pregnancy and was of a greater magnitude than oestrogen or progestogen medication. In many obstetric disorders, including hydatidiform mole, there was evidence of intravascular coagulation. The introduction of endocrine function tests has greatly improved patient care in our Department, in particular those related to endocrine disorders. Application of the immunoassays to basic research has shown that physiological levels of oestradiol exert a negative feedback effect on both FSH and LH secretions in men. The greater suppression of LH than of FSH secretion by pharmacological doses of estradiol is possibly due to different control mechanisms in the pituitary for the synthesis and release of both gonadotrophins. Physiological level of testosterone per se has a definite negative feedback effect on the secretion of LH but not on FSH. Pharmacological doses of the 5-alpha-reduced metabolites of testosterone have been shown to suppress both LH and FSH indicating that some of the actions of testosterone could be medicated by these metabolites of which the 3 alpha-androstanediol and 3 beta-androstanediol are the more likely candidates.