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Biomedical subjects

H N Ho

Publications and source records attributed to H N Ho.

125 records · Page 7Linked to original sources
PubMed1988

Isolation and characterization of rat trophoblast cells.

Previous immunohistochemical studies of the rat placenta using specific alloantisera and/or monoclonal antibodies showed that the basal zone trophoblasts stained for Pa and Aa class I major histocompatibility complex (MHC) antigens and for the human SP1-related antigen. In an effort to isolate the basal zone trophoblast cells from the rat placenta, we used these markers to assess the degree of purification of the cells separated by density gradient centrifugation using either Ficoll-Hypaque or Percoll as the gradient medium. The cells were put either on the top or at the bottom of discontinuous density gradients in the range of 1.005-1.10 g/ml. The cell separation profiles for the two media were different. With Percoll, most of the trophoblast cells (80-95%) were collected at the density gradients 1.04/1.06 and 1.06/1.08, whereas with Ficoll-Hypaque, these gradients separated only a small fraction (4-23%) of the trophoblast cells, and most of them pelleted at the bottom of the tube. The trophoblast cells separated by Ficoll-Hypaque, however, showed fewer contaminant cells than those separated by the Percoll gradients.

Animals↗
PubMed1987

Differential expression of MHC class I antigens on the placenta of the rat. A mechanism for the survival of the fetal allograft.

In some mating combinations in rats, there is a maternal antibody response to the maternal antigenic components of the placenta without any previous immunization of the mother. The highest response occurs in the WF (u) female mated to the DA (a) male, and it is against a unique MHC-encoded class I antigen, the Pa antigen, and not against the major allele-specific transplantation antigen of the DA strain, RT1.Aa. The development of mAbs to the Pa and Aa antigens allowed us to localize these antigens on the placenta and to explore the reason for the differential antibody response to them using immunohistochemical and biochemical techniques. Both antibodies reacted with the WF X DA placenta and stained the endovascular and interstitial trophoblast of the decidua, the basal trophoblast, Reichert's membrane, and the yolk sac epithelium, but they did not stain the labyrinthine trophoblast. Blocking studies showed that each antibody reacted with a separate molecule in the placenta. Anti-class II mAbs reactive with the a or u haplotype did not stain the WF X DA, DA X DA, or WF X WF placenta; hence, there are no class II antigens in the placenta. Electron microscopic studies of the semiallogeneic WF X DA placenta using the immunogold technique with both single- and double-labeling showed that only the Pa antigen was expressed on the surface of the basal trophoblast, but that both the Pa and Aa antigens were in the cytoplasm of these cells; neither antigen was found in the labyrinthine trophoblast. By contrast, the placenta from the syngeneic DA X DA mating expressed both the Pa and Aa antigens on the surface of the basal trophoblast as well as in the cytoplasm; neither antigen was found in the labyrinthine trophoblast. These observations were quantified morphometrically using electron photomicrographs of single-labeled tissues. Both the Pa and Aa antigens isolated from the plasma membrane of lymphocytes have heavy chains of 46 kD, but those antigens isolated from the plasma membrane of basal trophoblast cells have heavy chains of 43 kD. Based on densitometric measurements of autoradiographs, the Pa/Aa ratio in the basal trophoblast membrane is 23.5, whereas it is 0.46 in lymphocyte membranes. These studies show that there is differential regulation of the expression of class I antigens on basal trophoblast cells in semiallogeneic pregnancies, but not in syngeneic pregnancies, such that the major allele-specific transplantation antigen is scarcely expressed on the surface of the basal trophoblast.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Ontogeny of expression of Pa and RT1.Aa antigens on rat placenta and on fetal tissues.

The unique pregnancy-associated (Pa) antigen, which is a class I antigen encoded by the major histocompatibility complex (MHC), elicits a nondestructive maternal antibody response. By contrast, the class I transplantation antigen RT1.Aa elicits a destructive antibody response in tissue transplantation but not during pregnancy. With the use of the avidin-biotin complex (ABC) immunohistochemical method, the Pa and RT1.Aa antigens were localized on the basophilic and giant cells of the basal zone trophoblast, the endovascular trophoblast and decidual interstitial trophoblast, and the chorioallantoic membrane but not on the labyrinthine zone trophoblast as early as the 12th day of gestation. These two antigens were also expressed on the epidermis, hair follicles, spleen, thymic medulla, bronchial epithelium, intestinal epithelium, the hepatic Kupffer cells, endocardium, endothelium of blood vessels, renal tubular cells and glomeruli, and renal pelvis and ureter of fetal and adult rat tissues. Absorption studies with placental tissue confirmed the presence of these two antigens in the rat placenta, and antibody-blocking studies confirmed their unique specificities.

Animals↗
PubMedDate not supplied

Down-regulation of CD25 expression on the surface of activated tumor-infiltrating lymphocytes in human cervical carcinoma.

To investigate the activation status of tumor-infiltrating lymphocytes (TILs) within the tumor milieu of human cervical carcinoma, we quantitatively measured and compared the activation markers on lymphocyte subpopulations which infiltrating normal and neoplastic cervix. A total of 20 patients with stage IA to IIA cervical cancer (cancer group) and 10 women with normal cervix (control group) were enrolled in this study. Mononuclear cells were isolated from tissue specimens by mechanical dispersal technique and three-color flow cytometry was utilized for the quantification of activation markers on lymphocyte subsets. Compared with control group, lymphocytes isolated from cancer tissue consisted of higher proportions of B cells (7.23% +/- 4.49% vs. 3.67% +/- 3.19%, P = 0.016) and T cells (72.33% +/- 8.70% vs. 53.15% +/- 17.36%, P = 0.004), but an inverted CD4:CD8 ratio (0.74 +/- 0.27 vs. 1.14 +/- 0.28, P = 0.002) and decreased NK cells (7.53% +/- 4.33% vs. 16.00% +/- 11.82%, P = 0.035). Low expression of CD25, but not CD69 and HLA-DR was observed on both CD4+CD3+ and CD8+CD3+ T cells derived from cervical cancer (P < 0.0001). Further dual activation marker analysis demonstrated that the expression of CD25 was dissociated from CD69 and HLA-DR on the same TILs in cancer tissue (P < 0.001). TILs in the tumor microenvironment can be functionally inhibited and lose the ability of clonal proliferation due to depressed expression of CD25.

Antigens, Differentiation, T-Lymphocyte↗
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

Microinjection of human sperm into perivitelline space of hamster eggs: comparison with zona-free hamster egg penetration of human sperm.

Micromanipulation of human sperm and oocyte has been utilized to facilitate fertilization of those patients with male factor due to oligoasthenospermia or those patients with repeated fertilization failure in an in vitro fertilization (IVF) program. Before manipulating human gametes, one needs experience with animal models. Our objective was to perform subzonal insertion of human sperm into hamster eggs and to compare the result with that of sperm penetration assay (SPA) using zona-free hamster eggs. Semen samples were obtained from 15 fertile donors with normal semen analysis and the motile sperm were collected by swim-up procedure. Microinjection was performed by injecting a varied number of sperm into the perivitelline space of 222 hamster eggs pretreated with sucrose solution (0.1 M). The rate of damage of eggs during microinjection was 7.2% (16/222). The rates of penetration in the microinjection group were 5.1% (4/79) for 1-5 sperm injected, 10.9% (11/101) for 6-10 sperm injected, and 11.5% (3/26) for 11-15 sperm injected. The average rate of penetration per egg was 8.7% (18/206), and the polyspermic rate was 11.1% (2/18). Simultaneously SPA was performed in each sample of semen as a positive control, and the average rate of penetration of SPA was 51.4% (108/210). The rate of penetration in the microinjection group was significantly smaller (p < .05) than that in the SPA group. Whether the penetration rate and polyspermic rate in a hamster model reflect similar results in human oocyte requires further investigation. However, the hamster egg provides an ideal model to develop a micromanipulation technique for human beings.

Animals↗
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

Spermatozoa recovered by IxaPrep gradient have improved longevity and better motion characteristics than those by Percoll gradient.

To compare the effectiveness of various sperm preparation methods, we examined sperm concentration, percentage of progressive motility, recovery rate, and various motion characteristics in 32 semen samples after Percoll and IxaPrep preparations. Except for sperm concentration, which was much higher after IxaPrep preparation, no statistical differences existed between these two methods in terms of motile sperm concentration (MSC), recovery rate, mean curvilinear velocity (VCL), mean straight-line velocity (VSL) and mean amplitude of lateral head displacement (ALH). Among 22 samples that were allocated in a 37 degrees C, 5% CO2 incubator, the mean MSC after 3 hours was significantly higher following IxaPrep preparation than following Percoll preparation (63.2 x 10(6)/mL vs. 42.8 x 10(6)/mL, p < .03). VCL and VSL were much higher after IxaPrep preparation than after Percoll preparation, both at 3 hours (p < .01) and at 24 hours (p < .03). ALH was also higher after IxaPrep preparation than after Percoll preparation, and it was statistically significant after 3 hours of incubation (p < .03). We conclude that the IxaPrep gradient may be adopted as the preferred method to the Percoll gradient in preparing spermatozoa for assisted reproduction because of the spermatozoa's persistent and better motion activities after incubation.

Cell Separation↗
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↗