Biomedical subjects

H F Chen

Publications and source records attributed to H F Chen.

117 records · Page 7Linked to original sources

PubMedDate not supplied

Comparative study of QSAR/QSPR correlations using support vector machines, radial basis function neural networks, and multiple linear regression.

Support vector machines (SVMs) were used to develop QSAR models that correlate molecular structures to their toxicity and bioactivities. The performance and predictive ability of SVM are investigated and compared with other methods such as multiple linear regression and radial basis function neural network methods. In the present study, two different data sets were evaluated. The first one involves an application of SVM to the development of a QSAR model for the prediction of toxicities of 153 phenols, and the second investigation deals with the QSAR model between the structures and the activities of a set of 85 cyclooxygenase 2 (COX-2) inhibitors. For each application, the molecular structures were described using either the physicochemical parameters or molecular descriptors. In both studied cases, the predictive ability of the SVM model is comparable or superior to those obtained by MLR and RBFNN. The results indicate that SVM can be used as an alternative powerful modeling tool for QSAR studies.

Animals↗

PubMedDate not supplied

Schedule to inject in vitro matured oocytes may increase pregnancy after intracytoplasmic sperm injection.

To ascertain the value of using immature oocytes in an intracytoplasmic sperm injection (ICSI) program, the authors designed a schedule, at 5 p.m. on day 1 (the day of oocyte retrieval) and at 8 a.m. and 2 p.m. on day 2, to recognize and inject the in vitro matured (IVM) oocytes. For the 1,166 oocytes retrieved in 107 ICSI cycles, 128 (11.0%) were at the stage of metaphase I (MI) and 113 (9.7%) at germinal vesicle. Routine ICSI for metaphase 11 oocytes was performed at 2 p.m. on day 1 (initial ICSI). In culture medium of human tubal fluid with 15% maternal serum, 85.1% (205/241) immature oocytes progressed to maturation in which 16.4% (21/128) of MI oocytes matured at 5 p.m. of day 1. The rate of normal fertilization for IVM oocytes (58.5%) was not significantly different from that of initial ICSI (64.0%). One patient received a transfer of two fertilized IVM oocytes alone that were injected at 5 p.m. of day 1, maturing from the MI stage, and achieved a normal pregnancy. The fertilized IVM oocytes were replaced along with the embryos from initial ICSI for 40 cycles that led to 14 (35%) clinical pregnancies. In 43 fertilized IVM oocytes donated for research, we observed that cleavage (95.3%) to the 2- to 4-cell stage was not distinct from that of initial ICSI (94.6%); however, the percentage of embryos of grade I and II morphology was significantly smaller (24.4% vs. 62.5%). Only five (11.6%) developed to blastocysts in vitro. Twenty-one fertilized IVM oocytes were frozen for future transfer. A schedule to inject IVM oocytes in ICSI cycles may generate more accessible embryos for fresh transfer or cryopreservation to increase the chance of pregnancy, although the embryo quality was relatively poor.

Adult↗

PubMedDate not supplied

Comparative study of non nucleoside inhibitors with HIV-1 reverse transcriptase based on 3D-QSAR and docking.

The intermolecular interaction between two types of non nucleoside reverse transcriptase inhibitors (NNRTIs), HEPT and TIBO, and HIV reverse transcriptase receptor (HIVRT) was investigated. The result of docking study showed that two types of NNRTIs presented similar interaction mechanism with HIVRT. The most active compound of every type of inhibitors could form one hydrogen bond with the residue Lys101 and has hydrophobic interaction with residues Tyr181, Tyr188 and Tyr318, etc. Three 3D-QSAR models including two partial correlation models (one for each family of HEPT and TIBO) and a mixed model gathering two families were constructed. Comparative study of these models indicated that the mixed model offered the strongest prediction ability. For this model, the cross-validated q2 values were 0.720 and 0.675, non-cross-validated r2 values were 0.940 and 0.920 for CoMFA and CoMSIA, respectively. It has been validated by using a test set of 27 inhibitors. Compared with previously reported works, our model showed better prediction ability. It could help us to insight the interaction between NNRTIs and HIVRT, and to design new anti-HIV NNRTIs inhibitors.

Drug Interactions↗

PubMedDate not supplied

Acrosin activity of human sperm did not correlate with IVF.

To evaluate the predicting value of sperm acrosin activity in human, the acrosin activity index (AAI) was measured in 95 semen samples from patients participating in an IVF program. All patients had at least two mature oocytes. Of 95 patients, 84 had successful fertilization and 11 failed to fertilize all oocytes in vitro. The numbers of mature oocytes were similar between fertilization and nonfertilization groups. The mean AAI, measured using a commercially available (Accu-Sperm) acrosin activity assay, was greater in the fertilization group than in the nonfertilization group, but the difference was not significant. There was no correlation between AAI and the in vitro fertilization rate of mature oocytes. The relation between AAI and semen parameters also showed no significant difference. It would appear that measurement of AAI inaccurately reflects in vitro fertilizability of human sperm.

Acrosin↗

PubMedDate not supplied

Correlation between sperm morphology using strict criteria in original semen and swim-up inseminate and human in vitro fertilization.

To study the value of sperm morphology using strict criteria in raw semen and in swim-up inseminate of human in vitro fertilization (IVF), 135 cycles of IVF with normal sperm concentration and motility were recruited. At least two mature oocytes were recovered in each cycle. The correlation between the percentages of normal forms and fertilization rates of mature oocytes was analyzed. The results demonstrate that the percentage of normal forms in both the raw semen and swim-up sample of patients with poor fertilization was significantly lower than in those with acceptable fertilization. The percentages of normal forms both in raw semen and in swim-up sample were significantly correlated with fertilization rates in vitro, however, the former seemed to have a better correlation (r = .51 and .19, respectively). Regarding the percentages of normal forms in raw semen, the fertilization rate in patients with normal forms < 4% was 6 +/- 11%, for 4-14% it was 58 +/- 36%, and for > 14% it was 88 +/- 20%. The fertilization rates were significantly different among these three groups of patients. The evaluation of sperm morphology using strict criteria in raw semen before IVF is predictive of fertilization outcome and may also help doctors to choose an optimal method of treatment for patients.

Female↗

PubMedDate not supplied

Combination of direct swim-up technique and discontinuous Percoll gradient centrifugation for sperm preparation of oligoasthenozoospermic samples.

Sperm recovery for assisted reproduction in oligoasthenozoospermic patients is not satisfying either by the swim-up technique or by Percoll gradient centrifugation, and no single technique is constantly preferred. The design of this study was to evaluate the effects of combining the two methods on improving the efficacy of sperm preparation in these poor samples. For each semen sample, 1 mL was treated with a combination method, which used direct swim-up technique to recover motile sperm swimming to the supernatant, and then the residual semen was subjected to two-layer discontinuous Percoll gradient procedure for further recovery of motile sperm. Another 1 mL was prepared with two-layer discontinuous Percoll gradient centrifugation alone for comparison. Parameters measured included sperm concentration, number of progressively motile sperm, percentage of progressive motility, percentage of motile sperm recovery, amount of debris, percentage of normal forms according to Kruger's strict criteria, and motion characteristics of sperm using computer-aided motility analysis. The results of 30 oligoasthenozoospermic samples demonstrated that the combination method achieved a significantly greater recovery of motile sperm than the two-layer discontinuous Percoll gradient centrifugation did (43.2 +/- 19.7% vs. 32.2 +/- 14.3%, p < .05). The percentage of progressive motility was higher in the samples of the combination method than in those of Percoll gradient centrifugation alone, but the difference was not significant (63.7 +/- 21.8% vs. 58.7 +/- 20.1%). The debris of semen was removed equally well by both methods. The percentage of normal forms as well as motion characteristics, including curvilinear velocity, straight-line velocity, mean amplitude of lateral head displacement, and linearity, were similar in the samples treated by these two procedures. The combination of the direct swim-up technique and discontinuous Percoll gradient centrifugation combines the advantages of each procedure and results in greater recovery of motile sperm in oligoasthenozoospermic samples.

Cell Separation↗

PubMedDate not supplied

Effect of peritoneal fluid on sperm motility parameters in women with endometriosis.

To clarify the effect of peritoneal fluids (PF) of women with various stages of endometriosis on sperm motility, we utilized computer-aides sperm analysis (CASA) to analyze sperm movement characteristics. PF was collected in the early follicular phase (days 4-8) of the menstrual cycle from 48 women undergoing diagnostic laparoscopy. Only sperm samples having normal sperm parameters were chosen for study. Swim-up separation was performed for 1 h at 37 degrees C. Sperm suspension was mixed at a ratio of 1:1 with each of the following four groups: group 1, human tubal fluid (HTF) with 10% fetal bovine serum (control), group 2, normal PF (n = 16); group 3, minimal or mild endometriosis PF (n = 16); and group 4, moderate or severe endometriosis PF (n = 16). The mixtures were analyzed at 0, 1, 3, 6, and 24 h of co-incubation using the CASA system. At the end of the 24 h incubation, Supravital staining of sperm was done to check the viability of sperm in each group. Only time (F = 126.6, p < .001) has a significant effect on sperm motion parameters. At 6 h, sperm velocity (mean curvilinear velocity and mean straight line velocity) of the PF groups was significantly greater than that of the control, but there was no significant difference between each PF group. At 24 h, the PF groups maintained 50% of initial sperm viability, compared with 13% of initial viability in the control group (p < .001). There was no adverse effect of PF in patients with endometriosis on sperm motion parameters.

Ascitic Fluid↗

PubMedDate not supplied

Enzyme inhibitory assay using monoclonal antibody against acid alpha-D-glucosidase in prenatal diagnosis to identify homozygotes of Pompe's disease.

From January 1985 to January 1990, measurements of acid alpha-D-glucosidase activity in amniocytes or chorionic villus samplings were done for 24 pregnant mothers who were carriers of Pompe's disease. 6 women had two subsequent pregnancies. Amniotic fluid was obtained by transabdominal amniocentesis performed on 10 of them, while chorionic villus samplings were obtained in the other 20. The results showed that 7 (23.3%) cases were homozygotes, 16 (53.4%) cases were heterozygotes, and 7 (23.3%) cases were normal. Pregnancies were terminated in the homozygotic group. Final diagnosis was confirmed by either skin fibroblast culture or clinical course. However, we found that there was overlap in the acid alpha-D-glucosidase activity of amniocytes between homozygotes and heterozygotes due to residual activity of neutral alpha-D-glucosidase. In an attempt to identify heterozygotes for Pompe's disease, we established an enzyme inhibitory assay using monoclonal antibody (mAb) against acid alpha-D-glucosidase. Comparing the differences in alpha-D-glucosidase activity before and after mAb treatment the homozygotes were significantly lower than heterozygotes (P less than 0.001). There was no more overlap in the difference of acid alpha-D-glucosidase activity before and after mAb treatment between heterozygotes and homozygotes in amniocytes. This modified enzyme inhibitory assay should facilitate homozygote detection. Comparing acid alpha-D-glucosidase activity between CVS and amniocytes, the enzyme activity in CVS is about 5 times higher than in amniocytes. There was no overlap in the acid alpha-D-glucosidase activity between homozygotes and heterozygotes. Therefore, CVS is better than amniocentesis in the prenatal diagnosis of Pompe's disease.

Animals↗

PubMedDate not supplied

Hormonal studies and Doppler flow imaging of ovarian lipoid cell tumors: report of two cases.

Ovarian lipoid cell tumors are very rare. We report two cases with abnormal menstruation, hirsutism, clitoromegaly and marked elevations of serum testosterone. Sonography revealed unilateral adnexal solid tumors. Flow velocity wave form study showed apparent flow within the tumor with the resistance index ranging from 0.42 to 0.49 in both cases. Unilateral oophorectomy and contralateral ovarian biopsy were performed. Frozen sections showed lipoid cell tumors without malignant change. During surgery, direct ovarian venipuncture showed a discrepancy in testosterone level in the bilateral ovaries of both patients and large ovarian-peripheral venous gradients in case 2. The testosterone concentration returned to normal postoperatively in both cases. Flow velocity wave form study and direct ovarian venipuncture are useful tools for evaluation of androgen-secreting tumors preoperatively and intraoperatively.

Adult↗