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Biomedical subjects

L L Veeck

Publications and source records attributed to L L Veeck.

13 recordsLinked to original sources
PubMed1992

The YAG laser used in micromanipulation to transect the zona pellucida of hamster oocytes.

PROBLEM: Since there has been no reported use of the YAG laser to micromanipulate oocytes, our purpose was to study whether (1) a YAG laser could be used to open the zona pellucida of hamster oocytes; (2) human sperm could reach the ooplasm and (3) under sperm penetration assay conditions, sperm would bind and penetrate the ooplasm. RESULTS: A YAG 100 laser was used at 10 W and 0.4-sec pulse width to open eight of eight ooplasm oocytes. The opening in the zonae was 0.25 to 1.0 rad (10 to 40 microns). For the initial eight oocytes and two parallel controls, the coarse appearance of the ooplasm was unchanged after 3 days. Next, in 11 of 12 manipulated oocytes, the sperm clustered at the opening of the zona. When 16 more oocytes were opened and exposed to sperm in sperm penetration assay conditions, each ooplasm bound sperm. There was no penetration noted. Each manipulation time was < 1 min. To clarify the laser effect, oocytes were exposed to laser energy then utilized as the interactive surface in the sperm penetration assay. It was found that only 20% bound sperm with no penetration. CONCLUSION: While the time factor compares favourably with other methods of zona opening, further study needs to be performed to minimize effect to the exposed oocyte.

Animals↗
PubMed1992

Performance of cryopreserved pre-embryos obtained in in vitro fertilization cycles with or without a gonadotropin-releasing hormone agonist.

OBJECTIVE: To evaluate the viability and potential for pregnancy of cryopreserved/thawed pre-embryos obtained after ovarian stimulation using gonadotropin-releasing hormone agonist (GnRH-a) adjunct therapy. DESIGN: Retrospective clinical evaluation of all patients receiving a gonadotropin ovarian stimulation protocol (follicle-stimulating hormone/human menopausal gonadotropin [FSH/hMG]) with/without GnRH-a. SETTING: Academic tertiary clinical care unit. PATIENTS: Patients receiving leuprolide acetate (LA)/FSH/hMG (n = 136: LA in the luteal phase; long protocol) were compared with patients receiving FSH/hMG alone (n = 130) within the same time-frame in our program (April 1987 through October 1989). INTERVENTIONS: All patients had both a cycle in which pre-embryos were transferred fresh and a cycle of thaw of cryopreserved pre-embryos (frozen at the pronuclear stage in a slow freeze-thaw protocol using 1,2 propanediol) transferred in monitored natural cycles. MAIN OUTCOME MEASURES: Groups were similar in age, etiology of infertility, and cycle day 3 serum FSH levels; a significantly higher (P less than 0.001) number of preovulatory oocytes was recovered in the GnRH-a group. Both groups of patients were transferred an equal number of pre-embryos at the time of IVF. Cycles with frozen/thawed pre-embryos were evaluated based on the analysis of the three main variables that demonstrate cryopreservation efficiency: survival rate, implantation rate, and term pregnancy rate (PR). RESULTS: Non-GnRH-a group (113 transfers): pre-embryo survival, 71.5%; PR/transfer, 24.7%; implantation rate, 16.0%; GnRH-a group (125 transfers): pre-embryo survival 71.6%; PR/transfer, 32.8%; implantation rate, 12.0% (no significant differences). CONCLUSIONS: The use of GnRH-a produced pre-embryos of equal aptitude for development after cryopreservation at the pronuclear stage when compared with a similar gonadotropin stimulation treatment without GnRH-a.

Adult↗
PubMed1992

Influence of number of pre-embryos transferred, progesterone level and oestradiol/progesterone ratio at thaw on pregnancy results during replacement of cryopreserved pre-embryos in natural cycles.

When frozen-thawed pre-embryos were transferred in a natural menstrual cycle, a clinical pregnancy rate of 22% per transfer cycle was obtained. The pregnancy rates were higher when serum progesterone levels at thaw were less than or equal to 3.4 ng/ml than when they were greater than or equal to 3.5 ng/ml. This was reflected in a significantly higher oestradiol/progesterone ratio at thaw in the conception cycles than in the non-conception cycles.

Adult↗
PubMed1992

Fertilization and early embryonic development.

Whether one carefully and meticulously records detailed observations in the laboratory, or jumps feet first into new and exciting areas of investigation, each scientist contributes to the advances being made in the control of human reproduction. The study of spermatozoa, oocytes, sperm-oocyte interaction, preembryo growth and development, and early pregnancy rewards us with breakthroughs in innovative technology and promotes paths of better understanding. One cannot search through the massive amounts of currently available literature without desiring to try "this" technique, expound on "that" one, take someone else's work a little further, or look at one's own results from a different angle. Presented here are some informative data, most published within the past year. Oocyte maturational competence and integrity, sperm function and quality, preembryo culture conditions, preembryo morphology, and ovarian age all emerge as factors important for interpreting a patient's chance of achieving pregnancy.

Embryonic and Fetal Development↗
PubMed1991

Recurrent failure of in vitro fertilization: role of the hemizona assay in the sequential diagnosis of specific sperm-oocyte defects.

The results of predictive fertilization bioassays (hemizona assay, hamster ova-human sperm penetration assay), in vitro fertilization treatment, fertile donor cross-match tests with either sperm or oocytes, and oocyte micromanipulation for assisted fertilization were used to establish a pathophysiologic diagnosis in cases of recurrent failed fertilization in vitro. Disorders of sperm function manifested at the level of zona binding, zona penetration, oolemma fusion, and pronuclear decondensation as well as oocyte anomalies were considered to represent the specific gamete defects that led to abnormal sperm-oocyte interactions (i.e., failed fertilization). Our findings show that the sequential application of bioassays can elucidate specific sperm or oocyte defects that characterize functional abnormalities among sperm populations.

Acrosome↗
PubMed1991

The window of embryo transfer and the efficiency of human conception in vitro.

Women with ovarian failure transferred with donated oocytes provide a unique in vivo model for the elucidation of the window of implantation and efficiency of reproduction in the human. Throughout 52 ovum donation cycles, the temporal window of endometrial receptivity was tested by replacing 2- to 12-cell embryos between days 16 and 24 of hormonally and histologically defined cycles. Of 37 transfers within days 17 to 19, 15 (40.5%) conceptions occurred. Twelve (32.4%) have reached viability. Of 11 patients transferred on days greater than or equal to 20, none conceived. Likewise, no pregnancies were achieved with 4 transfers on cycle day 16. Analysis of multiple embryo transfers within the suggested window of endometrial receptivity (days 17 to 19) revealed 14 of 24 (58.3%) to be conception cycles. considering only transfers with two or more embryos, at least one of which is of high quality (grades 1 to 2), yielded a 63.2% pregnancy rate. The results indicate a very high efficiency for in vitro fecundity provided optimal conditions are attained. The concepts leading to success in the ovum donation model should set the course for continued research toward improving results in other forms of assisted reproduction.

Abortion, Spontaneous↗
PubMed1991

Predictive value of pregnancy during original in vitro fertilization cycle on implantation and pregnancy in subsequent cryothaw cycles.

OBJECTIVE: To understand the homogeneity of oocyte quality within a cohort. DESIGN: All women (n = 367) that had cryopreserved pre-embryos subsequently thawed were studied. Pregnancy and implantation rates in the in vitro fertilization (IVF) and cryothaw transfers were examined. SETTING: Tertiary care academic center. RESULTS: Pregnancy in original IVF cycle predicted higher implantation rates at subsequent cryothaw transfers. Similarly, pregnancy in cryothaw cycles was associated with higher implantation and ongoing pregnancy rates at the initial IVF cycle. CONCLUSIONS: Within a cohort of oocytes, pregnancy with some of the pre-embryos in a cohort predicts pregnancy with the remaining oocytes in the cohort. Thus, oocytes within a cohort have similar pregnancy potential.

Cryopreservation↗
PubMed1991

Combined impact of the number of pre-ovulatory oocytes and cryopreservation on IVF outcome.

Three hundred and twenty-seven consecutive in-vitro fertilization (IVF) cycles in which luteal-phase leuprolide had been given were ranked according to the number of pre-ovulatory oocytes obtained (1-5, 6-10, greater than 10). Excess pre-embryos were cryopreserved at the pronuclear stage and later transferred into monitored natural cycles on the day after ovulation. The results indicate that the retrieval of large numbers of pre-ovulatory oocytes (greater than 10) has a small negative impact on oocyte quality as judged by fertilization rates (4% lower). However, implantation was not impaired compared to lower levels of retrieval in either the original IVF or subsequent cryo-thaw cycles. Overall, despite the small reduction in fertilization rate, the retrieval of many pre-ovulatory oocytes has produced a 'take-home baby rate' per stimulation cycle of 28.3% when 6-10 pre-ovulatory oocytes were retrieved and 41.5% when greater than 10 were retrieved: even higher rates are anticipated when the remaining cryopreserved pre-embryos are ultimately thawed.

Adult↗
PubMed1991

In vitro fertilization: effective alternative to surgery for distal tubal occlusion.

A total of 512 consecutive patients with tubal infertility underwent ovarian hyperstimulation for the purpose of IVF-ET, resulting in a total of 829 attempts and 890 transfers (fresh and cryo). Overall, 218 clinical pregnancies were achieved, of which 114 (52.3%) resulted in live births, and 38 (17.4%) were ongoing (greater than or equal to 20 weeks of gestation) at the conclusion of the study. The total live birth and ongoing pregnancy rate per patient was 29.7% (three patients conceived twice). The probability for a patient to achieve a live or ongoing pregnancy was 42.7% after three attempts and 85.3% after six attempts. We conclude that IVF-ET using contemporary technology offers an effective alternative to surgery for tubal obstruction.

Adult↗
PubMed1990

High-dose follicle-stimulating hormone stimulation at the onset of the menstrual cycle does not improve the in vitro fertilization outcome in low-responder patients.

In an attempt to improve their outcome with in vitro fertilization (IVF), 34 low-responder patients were stimulated with six ampules of follicle-stimulating hormone (FSH) daily starting on day 1 (n = 17) or day 2 (n = 17) of their menstrual cycles. The stimulated cycles showed a mean peak estradiol of 443 +/- 173 pg/mL, mean days of human chorionic gonadotropin of 7.6 +/- 1.4, 2.67 +/- 1.5 preovulatory oocytes per retrieval, and 2.56 +/- 1.3 oocytes per transfer. Three clinical pregnancies resulted after 25 embryo transfer cycles (12%). With paired analysis, we compared 8 patient cycles with prior six ampules of FSH stimulation starting on day 3; all parameters examined showed no significant differences. In a comparison of 22 patient cycles with prior 4 ampules of FSH stimulation on cycle day 3, no significant differences in any parameters were observed except in the higher number of ampules used in the present study. We conclude that high-dose FSH stimulation at the onset of the menstrual cycle does not improve the IVF outcome in low-responder patients.

Adult↗