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Biomedical subjects

T A Wang

Publications and source records attributed to T A Wang.

5 recordsLinked to original sources
PubMed1997

Cartilage viability with interpolated skin flaps: an experimental study.

Although composite cartilage grafts are often used in conjunction with a midline forehead flap to repair full-thickness nasal defects, the timing of pedicle division, which optimizes cartilage viability, has yet to be determined. A rabbit animal model was designed to investigate this question. The skin flap pedicle was divided at 0 days, 4 days, 3 weeks, 6 weeks, and 10 weeks in each of five groups of five animals. Although early pedicle division led to partial skin flap necrosis, the cartilage grafts tolerated this ischemic period better. Cartilage viability was approximately 70% and did not differ significantly between the five groups. It is concluded that a larger composite graft and better definition of the skin flap's critical period are needed to determine optimum timing for pedicle division in this animal model.

Analysis of Variance↗
PubMed1995

Eukaryotic DNA replication.

Recent discoveries suggest that the initiation of eukaryotic DNA replication involves at least two steps--one occurring near the completion of mitosis and the other at the onset of S phase--that bring about the ordered assembly of initiator proteins at the origin. The identification and characterization of components involved in promoting or antagonizing each of these steps has provided a preliminary understanding of how replication initiation is regulated so precisely during the cell cycle.

Animals↗
PubMed1987

The impact of embryo quality and quantity on implantation and the establishment of viable pregnancies.

The role of cleavage rates, number of embryos transferred, and some other variables in pregnancy outcome in 222 human embryo transfers was studied. Pregnancy rates were significantly higher in a group of 117 patients receiving at least one embryo that had reached the four-cell stage at 40 hr postinsemination (26% total pregnancies/transfer and 18% ongoing pregnancies/transfer) than in the 105 patients receiving embryos developing at a slower rate (7% total pregnancies/transfer and 2% ongoing pregnancies/transfer). Of the 23 ongoing or term pregnancies produced, 21 came from transfers of at least one embryo that had reached four-cell stage by 40 hr postinsemination. Pregnancy rates were unaffected in either the fast-cleaving or the slower-cleaving embryos by culturing in vitro for an additional 24 hr. The presence of anucleate cell fragments also had no effect on pregnancy rates. Pregnancy rates increased progressively with the transfer of more embryos per transfer. These results suggest that procedures to improve ovulation induction and in vitro embryo culture technique may better the success of in vitro fertilization by providing a high number of rapidly cleaving embryos for transfer.

Cleavage Stage, Ovum↗
PubMed1987

The influence of exogenous human chorionic gonadotropin cycles with spontaneous luteinizing hormone surges on the outcome of in vitro fertilization.

Thirty consecutive patients who displayed endogenous luteinizing hormone (LH) surges and reached oocyte recovery for the purpose of in vitro fertilization were reviewed (LH surge group). Another 37 patients receiving human chorionic gonadotropin (hCG) in the absence of an LH surge served as a control group (no surge-hCG group). All patients underwent ovulation induction using clomiphene citrate (CC) plus human menopausal gonadotropin (hMG). The numbers of oocytes recovered and embryos transferred were significantly lower in the LH surge group compared with the no surge-hCG group (P less than 0.05). Nevertheless, the pregnancy rate per oocyte recovery between the two groups appeared similar (20 versus 16%). Among the 30 patients with a LH surge, 9 received hCG after a LH surge was verified, whereas the others did not. Addition of hCG to the LH surge increased the numbers of oocytes recovered, embryos transferred, and the pregnancy rate (3 out of 9 versus 3 out of 21); however, this difference is not statistically significant. Furthermore, the addition of exogenous hCG to a spontaneous LH surge appears to be necessary to maximize the number of oocytes recovered, embryos transferred, and pregnancies obtained.

Adult↗