Search PubMed⌕ Search

Biomedical subjects

J H Check

Publications and source records attributed to J H Check.

At least 19 recordsLinked to original sources
PubMed1992

A guanine nucleotide-binding regulatory protein in human sperm mediates acrosomal exocytosis induced by the human zona pellucida.

Guanine nucleotide-binding regulatory proteins play key intermediary roles in regulating zona pellucida-mediated acrosomal exocytosis in mouse and bull sperm. Since human sperm possess a Gi-like protein and undergo the acrosome reaction in response to the human zona pellucida, we investigated whether this G protein plays a regulatory role in this exocytotic process. Zonae pellucidae isolated from eggs that had been inseminated but had shown no signs of fertilization after retrieval for in vitro fertilization and embryo transfer were pooled into groups of greater than or equal to 50 in order to reduce variability in biological responses due to the possible presence of ZP that had undergone modifications associated with the polyspermy block. Acid-solubilized zonae pellucidae were incubated with capacitated sperm, and the sperm then assessed for the acrosome reaction using both the P. sativum agglutinin and chlortetracycline fluorescence assays; both assays gave similar results. Sperm incubated with solubilized zonae pellucidae at a final concentration of 2, 4, or 6 ZP/microliter underwent acrosomal exocytosis to a similar extent as compared with A-23187. Sperm were incubated with 1 microgram/ml pertussis toxin during capacitation to functionally inactivate the Gi-like protein. Pertussis toxin treatment of sperm did not affect sperm motility and the ability of the cells to bind to structurally intact zonae pellucidae. Pertussis toxin, however, completely inhibited the percentage acrosome reactions induced by solubilized zonae pellucidae. By contrast, the A-23187-induced acrosome reaction was insensitive to PT treatment. Pertussis toxin inhibition of the zona pellucida-induced acrosome reaction occurred in a concentration-dependent manner with maximal effects observed at 100 ng/ml PT.(ABSTRACT TRUNCATED AT 250 WORDS)

Acrosome↗
PubMed1992

Comparison of pregnancy rates following in vitro fertilization-embryo transfer between the donors and the recipients in a donor oocyte program.

Our in vitro fertilization (IVF) program provides a unique opportunity to evaluate influences of hormonal milieu on pregnancy outcome, by using a shared pool of oocytes obtained by donors (in exchange for financial assistance). The study presented herein evaluated 38 retrieval cycles (28 oocyte donors/22 recipients). No difference in mean number of embryos transferred was seen (2.7 in the donors vs 2.8 in the recipients). However, a statistically significant difference was seen in the pregnancy rates per retrieval (10.5% donors vs 29% recipients) and per transfer (4/35, 11.1%, vs 11/34, 32.3%). Abortion rates were similar (25% donor, 27.2% recipients). These data suggest that other reports of higher pregnancy rates from donor oocyte programs may not be due exclusively to better-quality oocytes. Possibly a negative effect of hyperstimulation or adverse endometrial environment of the donor (possible chronic endometritis) may explain these data.

Abortion, Spontaneous↗
PubMed1992

Effect of swim-up, Percoll and Sephadex sperm separation methods on the hypo-osmotic swelling test.

The separation of spermatozoa from the seminal plasma is required to prepare the spermatozoa for intrauterine insemination, in-vitro fertilization and sex selection. This study evaluated the effects of sperm preparation techniques on the functional integrity of the sperm membrane, as measured by the hypo-osmotic swelling test (HOS). Thirty-four semen specimens obtained from the male partner of infertile couples were evaluated. A semen analysis and HOS test were performed on each specimen. The remainder of the specimen was divided into three equal aliquots, the first prepared using Percoll, the second using a swim-up method and the third using a Sephadex column. After the preparation, a semen analysis and HOS test was performed on each aliquot. The mean and standard deviation for the HOS test was 72.9 +/- 8.5% initially, 71.2 +/- 13.1 after Percoll, 75.2 +/- 15.1 after swim-up and 62.4 +/- 14.5 after Sephadex. Analysis of variance showed that the mean HOS score was the same after Percoll and swim-up as it was initially but significantly lower after preparation with Sephadex. There was also a higher proportion of abnormal semen specimens (HOS less than 50%) after preparation with Sephadex than after the other preparation methods. We recommend the use of the HOS test as part of a screening panel for sperm separation.

Cell Membrane↗
PubMed1992

Comparison of short versus long-term leuprolide acetate--human menopausal gonadotrophin hyperstimulation in in-vitro fertilization patients.

The use of leuprolide acetate for at least 10 days beginning in the mid-luteal phase prior to initiating human menopausal gonadotrophin (HMG) stimulation has been fairly successful in preventing cancellations for premature luteinization and allowing retrieval of more oocytes, which in turn provide more embryos for cryopreservation. However, it is theoretically possible that the long-term use of leuprolide may have some adverse effect on either pregnancy rates or on mean survival after cryopreservation and thawing. Recently, a short 3 day regimen of a gonadotrophin-releasing hormone agonist, buserelin effectively prevented premature luteinization during HMG stimulation. The present study indicated that substitution of a 3 day course of leuprolide acetate also effectively prevented premature luteinization but was less expensive, required statistically fewer ampoules of HMG and much less leuprolide.

Adult↗
PubMed1992

The effect of follicle maturing drugs on side of ovulation in successive cycles.

Our previous study has demonstrated that ovulation in unstimulated cycles is random with an equal likelihood of ipsilateral or contralateral ovulation occurring in the following cycle. This study evaluated women taking ovulation-inducing drugs to see if the side of ovulation in the preceding cycle has an influence on the side of ovulation in the succeeding cycle. Ovulatory patterns in consecutive pairs of cycles in anovulatory women treated with ovulation-inducing drugs were evaluated through sonographic studies of follicular maturation. The results demonstrated that when unilateral ovulation occurred, there was an equal likelihood of ipsilateral or contralateral ovulation in the succeeding cycle. However, ovulation-inducing drugs increase the incidence of bilateral or multiple ovulation.

Clomiphene↗
PubMed1992

A randomized prospective study comparing pregnancy rates following clomiphene citrate and human menopausal gonadotrophin therapy.

The anti-oestrogenic effect of clomiphene citrate causes an increased rate of associated cervical factor problems. Theoretically, it may also cause an adverse effect on the endometrium. The hostile mucus may be completely or partially corrected by the use of additional oestrogen after stopping clomiphene, or by intrauterine insemination (IUI). The prospective randomized study presented here was designed to determine whether a higher pregnancy rate might be achieved using human menopausal gonadotrophin (HMG) compared to clomiphene citrate. Thirty-seven women treated with clomiphene citrate for 165 cycles were compared to 33 treated with HMG for 179 cycles. A pregnancy was achieved in 81.1% of clomiphene-treated women (18.2%/cycle) versus 72.7% (13.3% per cycle) of HMG-treated women. The abortion rates of 13.3 and 12.5% respectively, were similar. The data suggest no adverse effect of clomiphene compared to HMG as far as pregnancy rates are concerned. IUI seems to be an effective means of treating cervical factor problems induced by clomiphene.

Clomiphene↗
PubMed1992

An evaluation of couples with failure of fertilization in vitro.

Attempts at in-vitro fertilization (IVF) may be used as a method of evaluating whether in a given couple, the inability of the sperm to fertilize the oocyte may be the cause of infertility. We evaluated all IVF patients in our practice who had at least one cycle with no fertilization to determine how often this was an isolated event or was repeated in multiple cycles; would poor semen quality be found as a frequent cause; and how well can a donor sperm or oocyte 'probe' uncover which of the two is the problem? Of 35 couples who used their own gametes exclusively, 30 (85.7%) had at least one cycle with zero fertilization; 42.5% of those failing to fertilize in cycle 1 and 35% of those failing in cycle 2 had a subnormal concentration of motile spermatozoa, morphology or hypo-osmotic swelling test scores. The pregnancy rate per cycle with both husband's and wife's gametes was only 2.3% (3/130), but was 8.3% for those using donor spermatozoa (3/36) and 18.2% (2/11) for donor oocytes. Thus, failing to fertilize in a given cycle does not necessarily predict failure to fertilize in a subsequent cycle, but does predict a poor fertility outcome unless donor gametes are used.

Adult↗
PubMed1992

Analysis of serum human chorionic gonadotrophin levels in normal singleton, multiple and abnormal pregnancies.

Some researchers claim that first trimester beta-human chorionic gonadotrophin (beta HCG) levels have a constant doubling time; others suggest doubling time increases as pregnancy progresses. This study was designed to settle the debate by analysing a large series of serial serum beta HCG determinations from 143 pregnant women whose day of ovulation was precisely determined. Regression analysis was used to evaluate linear and quadratic models for the relationship of HCG with time in normal pregnancies. Doubling times were calculated for three time periods: 10-20 days post-ovulation (period 1); 21-30 days post-ovulation (period 2); greater than 30 days post-ovulation (period 3). Analysis of variance was used to compare the mean doubling time by time period and type of pregnancy (single, multiple, spontaneous abortion and ectopic). The analysis showed that a quadratic model best described the pattern of HCG rise in early normal pregnancy. Furthermore, for normal pregnancies, the mean doubling time increased significantly with advancing gestational age between time periods 1 and 2 and between periods 2 and 3. The mean doubling time was the same for single and multiple pregnancies. The doubling time was prolonged with ectopic pregnancy in period 1; and for aborters reaching ultrasound at 8 weeks, the doubling time was normal in period 1 but prolonged in period 2. Careful observation of the doubling time may aid clinicians in the detection of abnormal pregnancies.

Abortion, Spontaneous↗
PubMed1992

Successful delivery of twins in a woman with a unicornuate uterus.

The presence of a unicornuate uterus is a rare congenital condition which represents only 1-2% of uterovaginal anomalies. Previous reports have demonstrated an increase in the number of cases of primary infertility, pregnancy loss and preterm labor associated with the unicornuate uterus. Herein, we present a case in which a patient conceived following a thawed frozen embryo transfer. She had been given the option of selective reduction, because of the high risk associated with this pregnancy, but refused and her pregnancy successfully continued to 35 weeks and delivery of twins.

Adult↗
PubMed1992

Serum progesterone and 17-hydroxyprogesterone in the diagnosis of ectopic pregnancies and the value of progesterone replacement in intrauterine pregnancies when serum progesterone levels are low.

The corpus luteum function was evaluated in patients with surgically confirmed ectopic pregnancy (EP) in a multicenter study. In addition, the minimal threshold of serum progesterone (P) concentration required for salvaging intrauterine pregnancies (IUP) was also examined. Results show that single P or 17-OHP measurements are not diagnostic for EP, since mean P levels in EP were similar to those with spontaneous abortion though significantly lower than those in controls. 17-OHP levels in EP overlapped in 50% with IUP, and the mean levels were significantly lower only at 6-7 weeks. The 17-OHP levels when compared to hCG supports the view that corpus luteum defect is primary. In IUP, P levels < 8 ng/ml still were associated with viable (60%) pregnancy; thus no minimal threshold could be established.

17-alpha-Hydroxyprogesterone↗
PubMed1992

Effect of the short follicular phase on subsequent conception.

The present study was designed to evaluate whether there is a lower pregnancy rate in women with short follicular phases, as defined by attaining the peak estradiol level before day 11 of the cycle. Thirty-two early ovulators with mature follicles were matched with 32 women being treated for similar infertility problems, who ovulated between days 12-20. Pregnancies were achieved by 9 (28.1%) of the early ovulators compared to 19 (59.4%) of the controls. The mean number of cycles required to achieve a pregnancy was 8.6 in the early ovulators compared to 6.4 in the controls. Using the clinical life table method, the 12-month pregnancy rate was estimated to be 31.4% for early ovulators as compared to 66.3% for controls. Whether lengthening the follicular phase by drug treatment will improve pregnancy rates remains to be seen.

Adult↗
PubMed1992

Comparison of first trimester serum estradiol levels in aborters versus nonaborters during maintenance of normal progesterone levels.

This study was designed to measure the average serum estradiol (E2) levels in the first trimester for women whose serum progesterone (P) levels were carefully maintained at normal levels by the use of exogenous P, and to compare the mean serum E2 levels in women who aborted with those in women who did not. The study group consisted of 94 pregnant women supported with exogenous natural P therapy from the luteal phase through the first trimester. Beginning at week 5, and continuing through the first trimester, the mean serum E2 levels for nonaborters were significantly higher than those for aborters.

Abortion, Habitual↗
PubMed1992

Multiple follicles in an unstimulated cycle despite elevated gonadotropins in a perimenopausal female.

The presence of estrogen deficiency associated with elevated gonadotropins usually signifies menopause. However, there have been a few case reports of ovulation and pregnancy despite hypergonadotropic hypogonadism. Described herein is a case of a perimenopausal woman who not only failed to ovulate in response to clomiphene citrate therapy but also failed to generate a level of serum estradiol (E2) over 30 pg/ml. Following pharmacologic suppression of her elevated gonadotropins with ethinyl estradiol, she spontaneously formed 3 mature follicles, and her serum E2 climbed to 868 pg/ml. This case suggests that some perimenopausal women may respond to their own endogenous elevated gonadotropins as if they are taking ovulation-inducing drugs and may, as a consequence, form multiple follicles.

Adult↗
PubMed1992

The effect of follicle-maturing drugs on mid-cycle androgen levels in women with normal baseline levels.

Theoretically, clomiphene citrate or human menopausal gonadotropins might have a higher chance of inducing pregnancy per cycle were it not for the concomitant rise in androgens induced by these follicle-maturing drugs. In the present study, mid-cycle androgen levels were evaluated in anovulatory women with normal baseline early follicular levels who were treated with either clomiphene citrate or human menopausal gonadotropins. The only mid-cycle androgen to rise above the normal range was androstenedione. However, no negative effects of elevated androstenedione levels on pregnancy rates were apparent. Thus, at least in women with normal baseline androgen levels, the use of follicle-maturing drugs does not appear to cause a rise in androgen levels except for androstenedione, and the rise in androstenedione at mid-cycle appears to have no adverse effect on conception.

Androgens↗