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Biomedical subjects

B H Yuen

Publications and source records attributed to B H Yuen.

105 records · Page 6Linked to original sources
PubMed1977

Cyclic 3',5' -adenosine monophosphate in umbilical cord and maternal plasma before and after the onset of parturition.

Significant arteriovenous differences in cord cyclic 3',5'-adenosine monophosphate (cAMP) levels and between the maternal plasma (MP) and each cord vessel (mean umbilical artery [UA] greater than umbilical vein [UV] greater than MP) was observed. cAMP levels were significantly higher in the umbilical cord vessels and maternal plasma after vaginal delivery than they were following delivery by elective cesarean section before the onset of labor. The higher mean cAMP levels observed after parturition appeared to be more pronounced in the fetoplacental unit than in the maternal compartment. A significant positive correlation in cAMP levels between the UA and UV was also observed.

Cesarean Section↗
PubMed1977

Plasma beta-subunit human chorionic gonadotropin assay in molar pregnancy and choriocarcinoma.

Serum plasma levels of the beta-subunit of human chorionic gonadotropin (HCG-beta) were measured by radioimmunoassay in 24 women with molar pregnancies and five with choriocarcinoma. In the patients with molar pregnancy, plasma HCG-beta concentrations became undetectable within 8 to 173 days. In the patients with choriocarcinoma, plasma HCG-beta levels declined rapidly with appropriate chemotherapy. Serial plasma HCG-beta assay in this series accurately determined remission and detected early recurrences during follow-up. All patients are in remission with a mean follow-up of 22 months for the patients with choriocarcinoma.

Choriocarcinoma↗
PubMed1976

Cyclic adenosine 3',5'-monophosphate (cAMP) in pregnancy body fluids during normal and abnormal pregnancy.

cAMP levels in maternal urine (MU), maternal plasma (MP), and amniotic fluid (AF) were measured by competitive protein-binding assay in medically uncomplicated pregnancies (Group A) and some abnormal pregnancies (Group B). In Group A, MU values increased from 3.43 +/- 0.3 mu/Moles per gram of creatinine (mean +/- S.E.M.) at 12 to 29 weeks to its peak value, 5.72 +/- 1.03 at 33 to 35 weeks (p less than 0.025). Thereafter, the values decreased until term. In AF, cAMP levels increased from 9.4 +/- 1.02 at 10 to 19 weeks to 32.6 +/- 2.7 picomoles per milliliter between 35 and 42 weeks (p less than 0.005). Mean +/- S.E.M. MP levels between 4 to 20 and 21 to 42 weeks showed no significant difference (14.97 +/- 15.89 +/- 0.57 picomoles per milliliter, respectively). Umbilical cord plasma contained higher concentrations than in MP and AF. In Group B, abnormal MU patterns were observed in hypertensive disorders, chronic renal disease, and postmaturity. In a single patient with hyperthyroidism, abnormal MU and AF (but not MP) levels were observed. Abnormalities in MU and AF concentrations of the nucleotide are thus not specific for one disease entity.

Amniotic Fluid↗
PubMed1976

Amenorrhea, hyperprolactinemia and pituitary enlargement secondary to primary hypothyroidism. Successful treatment with thyroid replacement.

A 22-year-old nulliparous woman presented with primary amenorrhea, primary hypothyroidism, hyperprolactinemia, and radiologic evidence of pituitary enlargement. Investigation demonstrated limited reserves of ACTH and growth hormone. Circulating concentrations of TSH and prolactin were elevated; they increased in response to thyrotropin releasing hormone and decreased following L-dopa administration. After treatment with L-tri-iodothyronine, serum TSH and prolactin levels fell markedly, reserves of growth hormone and ACTH returned to normal, menstrual periods began, and the patient conceived. She experienced an uncomplicated prenatal, intrapartum, and postpartum course. It is thought that this patient represents a distinct clinical entity: a syndrome of amenorrhea, hyperprolactinemia, and pituitary enlargement, all secondary to primary thyroid failure. This syndrome should be distinguished from the Forbes-Albright syndrome, as it is reversible with thyroid replacement therapy. Recognition of this syndrome may thus spare the patient unnecessary, and potentially dangerous, pituitary surgery or irradiation.

Adult↗
PubMed1974

An analysis of maternal deaths in British Columbia: 1963 to 1970.

There were 132 maternal deaths in British Columbia in the years 1963 to 1970. The mean maternal mortality rate for these eight years was 0.317. Sixty of these deaths (45.5%) were due to direct obstetrical causes. Indirect and nonrelated deaths accounted for 21.2 and 33.3% of the total, respectively. The most common causes of direct obstetrical deaths were hemorrhage, infection and vascular accidents, in that order; pre-eclampsia ranked a distant fourth. Ninety-five percent of direct obstetrical deaths were probably avoidable. Approximately 27% of all direct obstetrical deaths were abortion-related. Hemorrhage continues to be a major problem, in particular among the native Indian women of the province.If further reduction in maternal mortality is to be achieved, obstetrical hemorrhage must be better managed and deaths due to abortions reduced. Future studies should reveal if the liberalized abortion laws will assist in the realization of the latter goal.

Abortion, Illegal↗
PubMedDate not supplied

Separation of a 170-K delayed-implantation-associated protein with inhibitory activity on trophoblast outgrowth and RNA synthesis by mouse embryo.

PROBLEM: To screen the uterine protein responsible for embryonic dormancy associated with delayed implantation. METHOD: Uterine protein extracts and sera from mice in which delayed implantation had been induced and those from pregnant mice were separated by three steps of chromatography and SDS-PAGE by monitoring an inhibitory activity on trophoblast outgrowth. The presence of the separated protein in the uterine luminal fluid was assessed. Effect of the protein on cell proliferation and RNA synthesis by blastocysts were assessed. RESULTS: A 170-K protein was found in the uterine tissue as well as uterine luminal fluid associated with delayed implantation. The 170-K protein suppressed RNA synthesis by approximately 50% and cell proliferation in blastocysts. CONCLUSION: A 170-K protein is secreted into the uterine lumen during delayed implantation period. The ability of 170-K protein to suppress RNA synthesis and cell proliferation may play a role in regulation of embryonic dormancy associated with delayed implantation.

Animals↗
PubMedDate not supplied

Interaction of prostaglandin F(2alpha) and prostaglandin E(2) on progesterone production in human granulosa-luteal cells.

This study examined the effects of prostaglandin-F(2alpha) (PGF(2alpha)), prostaglandin-E(2) (PGE(2)) and their interactions on progesterone production in human granulosa-luteal cells (GLCs). Human GLCs collected from in vitro fertilization patients were cultured for 1 (D(1)) or 8 days (D(8)), followed by a 24-hour treatment period, after which media were collected and radioimmunoassayed for progesterone. Seven-point PGF(2alpha) and PGE(2) concentration-response curves were crossed into a matrix of 49 separate treatments. Responses were plotted in three dimensions and as two-dimensional "slices". In D(1) cultured human GLCs neither PGF(2alpha) nor PGE(2) alone had any effect on progesterone production, however two different combinations of these hormones led to at least a 3-fold increase in progesterone production. This stimulation was seen when cells were treated with 10(-6) M PGF(2alpha) plus 10(-9) M PGE(2), and when they were treated with 10(-10) M PGF(2alpha) plus 10(-9) M PGE(2). In D(8) GLCs, PGF(2alpha) stimulated progesterone production maximally at 10(-9) M, while the lowest (10(-11) M) and highest concentrations (10(-6) M) tested were ineffectual. On the contrary, in the presence of high concentrations of PGE(2) (10(-6) to 10(-7) M), PGF(2alpha)-mediated stimulation of progesterone production was attenuated. In a similar fashion to PGF(2alpha), PGE(2) also acted in a luteotrophic manner, although the maximal stimulation of progesterone production was seen at a higher concentration (10(-8) to 10(-7) M). Likewise, PGE(2)-mediated progesterone production was attenuated by the presence of high concentrations of PGF(2alpha) (10(-6) to 10(-7) M). In conclusion, in D(1) human GLCs neither PGF(2alpha) nor PGE(2) alone were luteotrophic, although specific combinations of these hormones were. Conversely, in D(8) GLCs both PGF(2alpha) and PGE(2) stimulated progesterone production in a biphasic manner, while the presence of a high concentration of either of these prostaglandins attenuated the luteotrophic effects of the other. Therefore, PGF(2alpha) and PGE(2) interacted in a concentration-dependent manner, resulting in a multimodal progesterone response, which was easily visualized using three-dimensional plots.

Cells, Cultured↗
PubMedDate not supplied

Characterization of cell types within a chorionic gonadotropin-secreting, mechanically dissociated human placental cell population in perifusion.

A cell perifusion system was established to examine human placental endocrine regulation by locally synthesized peptides. First-trimester and term trophoblast cells were mechanically dissociated. Cells were plated on microcarrier beads and cultured for 7-14 days. Cells on beads were loaded in chambers, perifused with culture media and effluent was assayed for chorionic gonadotropin (hCG). Mechanical dissociation of placental tissue produced cell preparations with 85-95% viability. Staining with Masson trichrome, cytokeratin and beta-hCG antibodies suggested that greater than 50% of the cells were trophoblast. Perifused trophoblast cells secreted hCG in a continuous non-pulsatile fashion, independent of exogenous hormonal stimuli. hCG secretion from first-trimester trophoblast cells remained stable in static culture for 14 days. GnRH perifusion (10(-8) M) for 15-120 s transiently increased hCG secretion from first-trimester trophoblast cells. Longer GnRH exposure stimulated greater hCG secretion. Each of 3 consecutive pulses of 8-bromo-cyclic adenosine-3',5'-monophosphate (cAMP, 10(-9) M) administered at 2-hour intervals stimulated transient hCG secretion from first-trimester and term placental cells. cAMP stimulated hCG secretion more potently from first-trimester than from term placental cells.

Cells, Cultured↗
PubMedDate not supplied

Immunoreactive prolactin in breast milk and plasma of women with hyperprolactinemia, galactorrhea and menstrual dysfunction.

Prolactin levels were measured by radioimmunoassay in paired breast milk and plasma samples of 11 hyperprolactinemic women with galactorrhea and various menstrual disorders (amenorrhea, n = 8; oligomenorrhea, n = 2; luteal phase defect, n = 1) before and during treatment with bromocriptine (Parlodel, Sandoz). Pretreatment levels of prolactin in the milk and plasma were 80 +/- 13 ng/mL (mean +/- SEM) and 47 +/- 7 ng/mL (P less than 0.05), respectively. While on treatment, the concentration gradient for prolactin remained in favour of the milk, with values for milk and plasma 59 +/- 11 and 29 +/- 3 ng/mL (P less than 0.01), respectively. Thus, bromocriptine lowered the prolactin concentrations in both breast milk and plasma. Since prolactin in milk is biologically active, these findings may be relevant to the initiation and maintenance of lactation in women with abnormal lactogenesis.

Adenoma↗
PubMedDate not supplied

Exogenous gonadotropin therapy in combined anovulatory and male factor infertility.

This retrospective study evaluated conception rates in 18 women with refractory anovulatory infertility undergoing hMG ovulation induction in the presence of persistent mild to moderate semen abnormalities. Logistic regression analysis showed no relationship between conception (9.6% cycle) and the age of either partner, primary versus secondary infertility, or lowest sperm count, motility or morphology. In summary, this study demonstrates that a coexisting mild to moderate male factor does not preclude pregnancy during hMG therapy for anovulation. While semen abnormalities should not be ignored, aggressive treatment of concomitant ovulatory disorders and the resulting timed ovulation of several oocytes may minimize the effects of semen abnormalities.

Adult↗