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Biomedical subjects

Anthony P Cheung

Publications and source records attributed to Anthony P Cheung.

5 recordsLinked to original sources

Male infertility.

With infertile couples, one third of cases can be due to a male factor. It is important to have a comprehensive yet efficient approach to identifying potential causes for appropriate counseling and treatment. We combined the experience of a urologist and a gynecologist, both fertility subspecialists, and reviewed current literature on the investigation of male infertility. A history and physical examination supplemented by relevant investigations will help unravel any significant diseases that can be associated with male subfertility or any conditions that may be transmitted to future offspring. Semen analysis is a common, convenient measure of assessing the male. It should precede any invasive tests of the female. While reference values are important in standardization, the current trend in using sperm morphology alone in predicting male fertility remains problematic. Overreliance on this reference can lead to misdiagnosis and unnecessary invasive treatment with intracytoplasmic sperm injection (ICSI). In those who have no identifiable or correctable causes, ICSI provides new hope for couples with male infertility who, in the past, could only choose among therapeutic donor insemination, adoption or voluntary childlessness. With increasing application of these assisted reproductive technologies, it is important to rule out genetic causes, such as cystic fibrosis, and to provide appropriate genetic counseling before embarking on these invasive and costly procedures.

Adult↗

Assisted reproductive technology: both sides now.

Over the last 2 decades, increased pregnancy success has been achieved by assisted reproductive technology (ART) at the expense of perinatal well-being from a corresponding rise in multiple births. Multiple pregnancies increase the risk of prematurity, low birth weight, and perinatal morbidity and mortality. Together with recent concerns about possible birth defects and long-term developmental sequelae, modern ART practice is increasingly scrutinized for such adverse perinatal outcomes. Hence, it is mandatory for infertility specialists to look at ART from both sides now--its success and its complications. This article summarizes the prevalence of multiple pregnancies, the risk of low birth weight and possible birth defects, and long-term developmental sequelae associated with ART and discusses some potential approaches to minimizing these perinatal complications. Reducing the number of embryos transferred is an immediate action that can minimize adverse perinatal outcomes associated with multiple births. Continuous refinements in ART techniques will allow the transfer of a single embryo with equivalent rates of pregnancy success leading to a healthy, singleton live birth.

Chromosome Aberrations↗

A randomized, double-blind, multicenter study comparing a starting dose of 100 IU or 200 IU of recombinant follicle stimulating hormone (Puregon) in women undergoing controlled ovarian hyperstimulation for IVF treatment.

PURPOSE: To compare the efficiency and efficacy of two starting doses of recombinant FSH (follitropin-beta, Puregon) in women undergoing IVF treatment. METHODS: This prospective, randomized, double-blind, multicentric (N = 6) study included 192 women undergoing IVF using the long protocol of GnRH agonist who received either 100 IU or 200 IU of r-FSH per day. Gonadotropin dose adjustment was allowed after day 4 of stimulation. RESULTS: The average (SD) number of oocytes retrieved was 10.9 (5.4) and 12.2 (5.6) in the 100 IU and 200 IU group respectively (p = 0.067). The total doses of Puregon administered were 1887 IU and 2559 IU in the 100 IU and 200 IU group respectively. The number of transferable embryos, and the rates of pregnancies, cancelled cycles, miscarriages and adverse events including OHSS were comparable between the two groups. CONCLUSIONS: Women undergoing IVF have similar outcomes whether recombinant FSH is commenced in a dose of 100 IU or 200 IU for the first 4 days of stimulation.

Adult↗

Metformin and polycystic ovary syndrome: a literature review.

Polycystic ovary syndrome (PCOS) is a common endocrine condition that affects women of reproductive age. Anovulation, menstrual irregularities, hirsutism, and infertility are common clinical presentations. Long-term health concerns such as type II diabetes mellitus and, possibly, cardiovascular disease, have been linked to PCOS. Metformin, an oral hypoglycemic agent, has been recently advocated as treatment for some women with PCOS due to the association of PCOS with hyperinsulinemia. Metformin is utilized as sole therapy for ovulation induction as well as in combination with traditional ovulation-induction therapies. This review identified 23 prospective studies addressing the effects of metformin on PCOS. Because of the heterogeneity of the published reports, only a qualitative assessment of the data was possible. Review of this literature confirms a beneficial role of metformin in reducing insulin resistance in some women with PCOS. Other favourable biochemical effects include reduced free testosterone levels and increased sex hormone-binding globulin (SHBG). Metformin may improve menstrual regularity, leading to spontaneous ovulation, and improve ovarian response to conventional ovulation-induction therapies. There is, however, little evidence supporting the use of metformin to facilitate weight reduction, or improve serum lipids or hirsutism. Further evaluation is required to define the long-term effectiveness of metformin, who will benefit from metformin treatment, and the optimal duration of metformin therapy.

Androgens↗

In-vivo ovarian androgen responses to recombinant FSH with and without recombinant LH in polycystic ovarian syndrome.

BACKGROUND: Effects of exogenous LH on ovarian androgen secretion during ovulation induction have not been clearly characterized in polycystic ovarian syndrome (PCOS). The purpose of this study was to compare androgen secretion in PCOS women during ovarian stimulation with either recombinant FSH (rFSH) alone or combined with recombinant LH (rLH). METHODS: Clomiphene-resistant women with PCOS were allocated, in a factorial study design, to receive either daily injections of rFSH (n = 24) or rFSH + rLH (n = 24) in a 1:1 ratio starting: (i) on day 2-3 of progestogen-induced menses (n = 8); (ii) after 6 weeks of GnRH agonist treatment (nafarelin, 400 micro g twice daily; n = 8); or (iii) after nafarelin treatment as in (ii) plus dexamethasone (n = 8). The effects of rFSH with rFSH + rLH under these three hormone conditions on serum LH, 17alpha-hydroxyprogesterone (17-OHP), androstenedione (DeltaDelta(4)) and testosterone were contrasted by analysis of variance with specific treatment days as a repeated measures factor. RESULTS: Pre-study hormone levels were similar for all groupings. Nafarelin significantly suppressed LH levels, which remained at the lower limit of assay sensitivity (0.5 IU/l) during stimulation with rFSH but increased significantly to >1 but <2 IU/l when rLH was added. As expected, 17-OHP, DeltaDelta(4) and testosterone levels fell following nafarelin treatment. Dexamethasone further suppressed 17-OHP, DeltaDelta(4) and testosterone levels and unmasked a small but significant rise in these ovarian steroids 24 h following the first dose of rFSH + rLH, a rise that was absent with rFSH alone. Secretion of these steroids then appeared to 'catch-up' after 5 days of rFSH stimulation. CONCLUSIONS: Despite profound LH, 17-OHP, DeltaDelta(4) and testosterone suppression, comparable E(2) response, follicle development and successful pregnancies in PCOS subjects receiving rFSH alone to those receiving rFSH + rLH would argue that circulating LH at levels as low as 0.5 IU/l are sufficient to sustain adequate follicle development and function when FSH is present in abundance. Whether the observed dichotomy between rFSH and rFSH + rLH treatment in temporal secretion patterns reflects a greater reliance on evolving paracrine mechanisms as the follicles mature under profound LH suppression remains to be explored but may influence the optimal LH threshold for ovulation induction in PCOS.

17-alpha-Hydroxyprogesterone↗