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Biomedical subjects

H F Chen

Publications and source records attributed to H F Chen.

At least 91 records · Page 5Linked to original sources
PubMed1995

In vivo CD3+CD25+ lymphocyte subpopulation is down-regulated without increased serum-soluble interleukin-2 receptor (sIL-2R) by gonadotropin releasing hormone agonist (GnRH-a).

PROBLEM: To test further whether the suppression of the CD3+CD25+ lymphocyte subpopulation by gonadotropin-releasing hormone agonist (GnRH-a) is related to the change in levels of cytokines and soluble interleukin-2 receptor (sIL-2R). METHOD: Twenty-seven infertile patients were enrolled under the long protocol of GnRH-a agonist (buserelin acetate) and superovulation with gonadotropin from our IVF-ET program. Peripheral B cells, NK cells, CD4+ and CD8+ T cells and the expression of CD69, CD25, HLA-DR, and CD71 antigens on the T cells were serially examined by dual-color flow cytometry. Serum levels of cytokines and sIL-2R were measured. RESULTS: The B cells, NK cells, T cells, CD4+, CD8+ T cells, CD3+DR+, and CD3+CD71+ lymphocyte subpopulations were not changed after the use of GnRH-a. The CD25+ T cell subpopulation was significantly down-regulated, but the CD69+ T cell subpopulation was increased when the GnRH-a was used for approximately 2 wk. The serum levels of interleukin-1 beta (IL-1 beta), interleukin-2 (IL-2), interleukin-4 (IL-4), interferon-gamma (IFN-gamma), and sIL-2R were not changed. CONCLUSION: The GnRH-a had a transiently suppressive effect on CD25+ T cells, but a stimulatory effect on CD69+ T cells. However, the serum level of cytokines or sIL-2R did not change. These immunological modulations seems to be the result of interaction between GnRH-a and estrogen.

Antigens, CD↗
PubMed1995

Biliary excretion of furosemide glucuronide in rabbits.

Furosemide (F) was administered to rabbits intravenously and intraduodenaly and the biliary excretion was studied. The major metabolite excreted in bile was furosemide glucuronide (FG). F and acyl migration isomers of FG (FG-iso) were also excreted in bile. The biliary excretion rates of total F (F+FG+FG-iso) following intraduodenal administration of F were much smaller than those following intravenous administration. The fraction of (F+FG-iso) in bile following intraduodenal administration of F were larger than those following intravenous administration. Stability of FG or FG-iso in bile and supernatant solution of the duodenum homogenate of rabbits was studied. FG was unstable in both media and its degradation followed apparent first-order kinetics in both media. In bile, FG degraded to produce several FG-iso and F, while in the supernatant solution of the duodenum homogenate, it hydrolyzed immediately to F. FG-iso were hardly detected in the supernatant solution. These results indicated that FG excreted in bile degraded easily to FG-iso and F. FG might easily hydrolyze to F enzymatically in the duodenum, and the resultant F might be reabsorbed from the intestinal tract. Unabsorbed FG-iso and F might be excreted in the feces.

Adult↗
PubMed1995

Effect of assisted hatching by partial zona pellucida dissection on mouse embryos in vitro.

The zonae pellucida of mouse embryos were dissected to examine the effect of partial zona dissection (PZD) at the four-cell stage on embryonic development and the hatching process in vitro. Micropipettes were used to create a gap of one-sixth the zona circumference, to avoid damage to the blastomere. A total of 484 embryos at the four-cell stage (defined as day 2 embryos) were randomly divided into two groups, the PZD group (n = 238) and the control group (n = 246). Embryos of both groups were cultured in vitro under identical conditions and examined on the following day. The hatching rates were as follows: day 3, 11/238 (4.6%) in the PZD group and 0/246 (0%) in the control group; day 4, 105/238 (44.1%) in the PZD group and 54/246 (22.0%) in the control group; day 5, 71/238 (29.8%) in the PZD group and 36/245 (14.5%) in the control group. On day 4 the rates of complete hatching were 7/238 (2.9%) in the PZD group and 2/246 (0.8%) in the control group. On day 6 they were 88/238 (37.0%) in the PZD group and 66/246 (26.8%) in the control group. A significantly higher percentage of PZD embryos than controls initiated and completed hatching in similar culture conditions. The present study indicates that the creation of an opening in the zona pellucida is not harmful to embryonic development and may facilitate hatching. Whether the enhanced hatching ability of embryos in vitro caused by PZD can improve the implantation rate requires further study.

Animals↗
PubMed1995

Heterotopic pregnancies after controlled ovarian hyperstimulation and assisted reproductive techniques.

Eight cases of heterotopic pregnancy following assisted reproductive techniques (ART) were reviewed. One cervical, three cornual and four tubal pregnancies were combined with intrauterine pregnancies. The cervical ectopy was successfully treated with a local injection of potassium chloride (KCl) into the gestational sac. A viable baby was produced from the intrauterine gestation. Cornual metroplasties were performed on two ruptured and one unruptured cornual heterotopic pregnancies. One of these three cases was maintained till term. All four tubal heterotopic pregnancies were aborted. Widespread application of ART in recent years has meant that heterotopic pregnancies are no longer a rarity. Both physicians and patients should be made aware that the existence of an intrauterine gestation does not preclude the risk of nidation of other fetuses in ectopic sites. The authors recommend that detailed ultrasound studies, preferably via the vaginal route, should be performed on patients in ART programs. During the examination, the adnexae should be carefully evaluated, even if an intrauterine gestational sac is already present. If a heterotopic pregnancy is diagnosed, the appropriate treatment depends on the location of ectopic pregnancy. Local injection with KCl or methotrexate is effective in certain types of cervical or cornual ectopic pregnancy, as it may allow the conservation of the intrauterine pregnancy.

Adult↗
PubMed1994

Peptides extracted from Vero cell cultures overcome the blastocyst block of mouse embryos in a serum-free medium.

PURPOSE: The aim of this work was to evaluate the effect of a Vero cell coculture system on the development of mouse embryos. METHODS: Mouse embryos were randomly divided and cultured in human tubal fluid (HTF) medium with/without Vero cell monolayers, conditioned medium (CM) obtained from Vero cell cultures, and HTF medium supplemented with peptides extracted from CM. The concentrated CM was examined by SDS/PAGE. RESULTS: The development of mouse embryos was blocked at the blastocyst stage in pure HTF medium (1.4% hatching at day 5). This "blastocyst block" was overcome by coculture with Vero cell monolayers (48.1% hatching at day 5; 1.4 vs 48.1%; P < 0.001). CM and the addition of 5% fetal bovine serum (24.1 and 34.9% hatching, respectively, at day 5) were also able to enhance the process of hatching. In the other experiment, the addition of peptides extracted from Vero cell cultures also overcame the blastocyst block (12.5%) compared with pure HTF medium (2.1%) (P < 0.05). Electrophoretic separation revealed several classes of polypeptides consistently secreted into CM obtained from Vero cell cultures. Most peptides occurred in the M(r) range between 6.5 kd and 35.9 kd. CONCLUSION: A developmental block (blastocyst block) of mouse embryos in a serum- and protein-free medium (HTF) was discovered in this study. This block was effectively overcome by HTF plus serum and coculture with Vero cell monolayers and also by the peptides extracted from Vero cell-conditioned medium. We speculate that certain factors secreted or converted by Vero cells may be critical in hatching of mouse embryos. Further study of these factors may be helpful in delineating its mechanism.

Animals↗
PubMed1994

Sharing of human leukocyte antigens in couples with unexplained infertility affects the success of in vitro fertilization and tubal embryo transfer.

OBJECTIVE: The purpose was to test further our hypothesis that genes, or genetic defects, linked to the major histocompatibility complex affect reproduction by correlating human leukocyte antigen sharing with the success or failure of in vitro fertilization and tubal embryo transfer in couples having unexplained infertility. STUDY DESIGN: Seventy-six couples with unexplained infertility who failed superovulation and intrauterine insemination at least three times were typed for human leukocyte antigens and treated by in vitro fertilization and tubal embryo transfer. The results were correlated with the sharing of human leukocyte antigens in the couples. RESULTS: Thirty-four of the women had successful pregnancies, 36 did not become pregnant, and six became pregnant but aborted shortly thereafter. There was a highly significant excess of human leukocyte antigen sharing in the couples who failed treatment: three of the A, B, DR, and DQ antigens (p = 0.015) or two of the B, DR, and DQ antigens (p = 0.015). No specific human leukocyte antigen alleles were present in excess. CONCLUSIONS: Genes, or genetic defects, linked to the major histocompatibility complex significantly affect the success of in vitro fertilization and tubal embryo transfer just as they affect the prevalence of recurrent spontaneous abortion, cancer, and congenital anomalies. It appears as if the critical genes, or genetic defects, are located in the B-DR-DQ region of the major histocompatibility complex.

Abortion, Spontaneous↗
PubMed1994

Co-culture with Vero cell monolayer maintains the motility of asthenozoospermic semen samples.

The clinical effectiveness of co-culture with Vero (Green monkey kidney) cell monolayer in maintaining the motility and viability of fresh asthenozoospermic semen (18 samples) and frozen-thawed semen with poor motility (motility fraction < 50%) (15 samples) in a 24-h period was evaluated. Co-culture with Vero cell monolayer in human tubal fluid (HTF) medium for 24 h resulted in a statistically better maintenance of motility percentage (P < 0.005), mean amplitude of lateral head displacement (ALH) (P < 0.005), and mean track speed (VCL) (P < 0.05) than culture in HTF medium alone. However, these motility parameters (motility percentage, ALH, VCL) declined soon after removal of spermatozoa from the monolayer. Co-culture with Vero cell monolayer also maintained the viability percentage of these sperm samples (52% of the original value) after the 24-h period compared with culture in HTF medium alone (22% of the original) (52% versus 22%, P < 0.05). It is concluded that Vero cell monolayer is effective in the maintenance of motility and viability of asthenozoospermic semen or frozen-thawed semen with poor motility. This co-culture system may be beneficial in enhancing the in-vitro performance of asthenozoospermic semen samples in the practice of assisted reproductive technology. However, its safety needs further evaluation.

Animals↗
PubMed1994

Effects of pulmonary air embolism on discharge of slowly adapting pulmonary stretch receptors.

Pulmonary air embolism (PAE) usually causes small-airway collapse. Local transpulmonary pressure (Ptr) is thought to be closely associated with the activity of slowly adapting pulmonary stretch receptors (SAPSRs). To test whether discharge of SAPSRs located distal to collapsed airways is closely related to the overall Ptr, we studied 65 SAPSRs in anesthetized paralyzed open-chest dogs that were ventilated at constant tidal volume and frequency. PAE increased both Ptr and total pulmonary resistance but decreased dynamic lung compliance. Three groups of SAPSRs were identified on the basis of their locations in intrapulmonary airways. Group I had 29 SAPSRs located in airways < 1 mm in diameter. Group II had 10 SAPSRs that were found in intrapulmonary airways between 1 and 2 mm in diameter. PAE decreased the activity of 31 of the 39 SAPSRs in these two groups. Their activity during PAE was not related to Ptr. The 26 SAPSRs in group III were in airways > 2 mm in diameter. PAE increased the peak firing rate of 18 of these receptors, and there was a close relationship between the discharge frequency of these SAPSRs and the Ptr during PAE. In groups I and II, the dissociation between Ptr and SAPSR activity during PAE may have been caused by peripheral airway collapse. Activity of central fibers was blocked at higher temperatures than activity of peripheral fibers. We suggest that the response of a SAPSR to PAE depends on the location of the receptor within the lungs, and we speculate that threshold and fiber type are also related to location.

Airway Resistance↗
PubMed1994

Delayed maternal death after perimortem cesarean section.

We report a case of perimortem cesarean section performed on a multigravida with congestive heart failure. This patient had a past history of repeated episodes of acute myocarditis and this time, congestive heart failure attacked her at the 36th week of gestation. The maternal condition deteriorated rapidly with frequent attacks of ventricular fibrillation and cardiac arrest, which gradually became unresponsive to active cardio-pulmonary resuscitation (CPR). The fetal condition also worsened accordingly. Cesarean section was therefore performed and a 2590 gm depressed female baby was delivered in less than one minute after skin incision and about twenty-seven minutes after the maternal condition became extremely unstable. The Apgar scores were 1 at one min, 4 at five min and 6 at ten min. The mother improved soon after delivery of the fetus and her consciousness returned. However, her condition deteriorated again and she died four hours after operation. The fetus survived and follow-up 21 months after delivery was normal.

Adult↗
PubMed1993

Antihypertensive principles from the leaves of Melastoma candidum.

Three active principles were isolated from the leaf of Melastoma candidum using the screening of hypotensive effects on spontaneously hypertensive rats (SHR). Intravenous injection of castalagin, procyanidin B-2, or helichrysoside into SHR lowered the mean blood pressure in a dose-dependent manner, with helichrysoside being the most potent compound. Plasma noradrenaline (NA) levels, both basal in SHR and elevated in normal rats through cold-stress stimulation, were attenuated by these compounds in a way which was not influenced by adrenalectomy. Decrease of NA release from sympathetic nerves was assumed to be responsible. Moreover, the hypertensive effect of various vasoconstrictors in anesthetized rats was reduced by helichrysoside. The same results were also observed in castalagin or procyanidin B-2 treated animals. The results indicate that the three principles possess the ability to lower blood pressure through a decrease of sympathetic tone as well as due to direct vasodilatation in SHRs.

Animals↗
PubMed1992

Expression of the Epstein-Barr virus latent membrane protein (LMP) in insect cells and detection of antibodies in human sera against this protein.

Recombinant baculoviruses containing the complete LMP and truncated LMP genes were generated and high levels of the LMP proteins were expressed in Spadoptera Frugiperda insect cells. A specific rabbit antiserum directed against the N-terminal part of LMP was obtained by immunizing the rabbits with Escherichia coli-expressed trpE-N-terminal part of LMP fusion protein. A total of 127 human sera were studied for their immune response to the recombinant full-length LMP. In immunofluorescence analysis, all sera tested showed no detectable reaction with the recombinant full-length LMP. In immunoprecipitation-immunoblotting analysis, however, sera from patients with nasopharyngeal carcinoma (5/22), patients with Hodgkin's disease (16/27), patients with other diseases exhibiting high EA-IgG titers (3/52), and VCA-IgG-positive healthy individuals (2/26) were shown to contain antibodies against this recombinant LMP. The expressed LMP proteins provided a sufficient and economic source of the proteins for further serological and biological studies.

Animals↗
PubMed1992

Inhibition of host-versus-graft and graft-versus-host responses after small bowel transplantation in rats by rapamycin.

The effect of rapamycin (RAPA) on both host-versus-graft (HVG) and graft-versus-host (GVH) immune responses was examined in small bowel transplant models using strongly histoincompatible donor-recipient combinations. Normal Wistar Furth (WFu; RT-1u) recipients rejected Buffalo (BUF; RT-1b) small bowel allografts within a mean survival time (MST) of 10.5 +/- 0.5 days. Administration of RAPA (0.8 mg/kg) by continuous intravenous infusion for 14 days via an osmotic pump prolonged graft survival to 25.0 +/- 4.6 days (P = 0.01). In a second strain combination, the 12.5 +/- 2.2 day survival of Brown Norway (BN; RT-1n) small bowel allografts in Lewis (RT-1l) recipients was prolonged to 21.6 +/- 2.0 and 28.5 +/- 2.8 days by 14 days of i.v. RAPA at doses of 0.8 and 1.6 mg/kg, respectively. In this model RAPA is five times more effective than cyclosporine, which at 4.0 mg/kg prolongs BN small bowel allografts in Lewis recipients to 21.6 +/- 6.3. To isolate HVG and GVH immune responses, (BN x Lewis)F1 hybrid rats served as the graft donor or host, respectively. In the HVG model, (BN x Lewis)F1 small bowel allografts, which were rejected by normal Lewis recipients at 12.2 +/- 3.6 days, were prolonged to 40.8 +/- 5.8 days (P = 0.001) by RAPA (0.8 mg/kg x 14 days). In the GVH model, the ability of Lewis small bowel allografts to produce severe GVH disease in untreated (BN x Lewis)F1 recipients at 12.3 +/- 2.8 days was delayed to 21.3 +/- 5.2 days by 0.8 mg/kg RAPA (P = 0.025). Thus, RAPA protects small bowel allografts more effectively against HVG than GVH immune responses.

Animals↗
PubMed1992

Pregnancy after transfer of frozen-thawed human embryos.

Cryopreservation of human embryos has been successfully applied in in vitro fertilization (IVF) and embryo transfer (ET) programs at the National Taiwan University Hospital since 1988. Our preliminary results with 120 frozen-thawed embryos in 31 transfer cycles showed that the survival rate of frozen embryos was 66%. Following transfer, the implantation rate and clinical pregnancy rate were 6.5% and 13%, respectively. Four clinical pregnancies and one preclinical pregnancy following a frozen-thawed embryo transfer were achieved. Two normal male babies have been delivered and another pregnancy is progressing without any problem.* Unfortunately, one pregnancy was terminated due to intrauterine fetal death discovered at the 10th week of gestation; chromosome abnormality (47, XX, +5) of the fetus was found. The single preclinical pregnancy showed an elevation of serum beta-human chorionic gonadotropin levels for three consecutive weeks following ET, but no definite gestational sac was visualized by transvaginal ultrasound.

Adult↗
PubMed1991

Immunological characterization of the Epstein-Barr virus phosphoprotein PP58 and deoxyribonuclease expressed in the baculovirus expression system.

The open reading frames of the phosphoprotein pp58 (BMRFI) and the deoxyribonuclease (BGLF5) of the Epstein-Barr-virus (EBV) strain M-ABA were cloned in the baculovirus expression vectors pAc373 and pAc360 and expressed in the Spodoptera frugiperda (SF158) insect cells. The recombinant phosphoprotein pp58 expressed in SF158 cells was recognized by the anti-pp58 rabbit anti-sera which were generated by immunizing rabbits with a TrpE-BMRFI fusion protein expressed in E. coli. DNA-cellulose chromatography showed that the recombinant pp58 exhibited DNA-binding activities. Immunofluorescence, immunoblot and ELISA analysis indicated that sera from patients with nasopharyngeal carcinoma (NPC) contained antibodies against pp58. The recombinant EBV DNase expressed in SF158 cells was recognized by the anti-EBV DNase rabbit anti-sera which were generated by immunizing rabbits with a TrpE-C-terminal part of BGLF5 fusion protein expressed in E. coli. The anti-EBV DNase rabbit anti-sera recognized also a protein of about 52 kDa in the EBV-harboring human B-cell lines Raji, Jijoye, B95-8, M-ABA and BL74 induced by TPA and n-butyrate. The recombinant EBV DNase exhibited exonuclease and endonuclease activities, a requirement for magnesium, and a high pH optimum (8.0). Its enzyme activities could be inhibited by sera from NPC patients and anti-EBV DNase rabbit anti-sera. Comparable studies of Raji EBV-DNase and recombinant EBV-DNase implied that recombinant EBV-DNase could also be used in the enzyme activity assay for the detection of NPC. In contrast to the enzyme inhibition test, immunofluorescence and immunoblot analysis demonstrated that the recombinant EBV DNase exhibited only a weak immunological reaction with NPC sera.

Animals↗
PubMed1991

Refined technique for intestinal transplantation in the rat.

Unlike other solid organ transplants, intestinal transplantation (IT) remains a highly experimental procedure. Rejection, sepsis, and graft-versus-host disease have been the major barriers to successful IT in humans. These problems can be studied in the rat model, but this requires a reliable surgical technique that will produce high survival rates and excellent graft function. Herein, we review 400 consecutive IT in rats and describe important technical aspects of surgery. Technical modifications that have helped to reduce the morbidity after IT in rats include 1) minimizing mechanical and ischemic injuries to grafts during the donor procedure, 2) marking the portal vein and aortic conduit with sutures to ensure correct orientation of the graft, 3) using a macaroni noodle to stent the intestinal anastomosis, and 4) administering large volumes of crystalloid to maintain a normal blood pressure during the donor and recipient surgeries. The survival rate in 298 rats with accessory, heterotopic grafts was 90%. The survival rate in 102 rats with orthotopic (in continuity) graft (OIT) was 86%. Rats have survived more than 500 days after OIT, maintaining normal weights, intestinal function, and intestinal histology.

Anastomosis, Surgical↗
PubMed1991

In vitro IgE production by interleukin 4-stimulated human peripheral blood mononuclear cells is suppressed by rapamycin.

Rapamycin (RAPA) is a new immunosuppressant which is 50-fold to 100-fold more potent than cyclosporin A (CyA) in inhibiting cellular immune responses and allograft rejection in animal models of organ transplantation. The drug's effect on in vitro IgE synthesis by interleukin (IL)4-stimulated human peripheral blood mononuclear cells was examined and compared with CyA's effect in this study. RAPA was found to be about 100-fold more potent than CyA in inhibiting IgE synthesis. Its inhibitory effect on IgE production was significant if it was added to the culture before Day 6 of a 14-day culture. The suppression was accompanied by the inhibitory effect on cell proliferation and on IgE-binding factor (IgE-BF) production. IL2 was able to partially reverse CyA- but not RAPA-induced inhibition of IgE production. Commercial B cell growth factor (cBCGF) was not able to reverse either RAPA- or CyA-induced suppression of IgE synthesis. The strong inhibitory effect of RAPA in IgE synthesis may be useful in certain clinical applications where overproduction of pathogenic IgE is a key issue. RAPA can also be used as a tool to dissect the regulation of IgE production.

Cell Division↗
PubMed1991

A comparison of heterotopic and orthotopic intestinal transplantation in rats.

Two surgical techniques are commonly used for small intestinal transplantation: heterotopic (accessory) intestinal grafting (HIT), where the small bowel is initially defunctioned with restoration of intestinal continuity at a later date, and orthotopic (in continuity) intestinal grafting (OIT), where the small bowel is immediately anastomosed to the native intestine. The present experiments were undertaken to compare the advantages and disadvantages of these two surgical models. Graft barrier function (intestinal permeability), intestinal histology, and graft survival were evaluated after heterotopic and orthotopic intestinal transplantation in the following groups of rats: group 1: isografts, group 2: untreated allografts, group 3: low-dose cyclosporine-treated allografts (subcutaneous CsA 2 mg/kg/day), and group 4: high-dose CsA-treated allografts (subcutaneous CsA 4 mg/kg/day). Intestinal permeability was consistently higher after HIT than OIT in all of the groups (ANOVA; P less than 0.01). Histological evidence of rejection appeared earlier after HIT than OIT (HIT 5th postoperative day (POD); OIT 7th POD; P less than 0.05). The mean survival of untreated allografts was longer after HIT than OIT (HIT 15.7 +/- 6 days, OIT 9.2 +/- 1 days, P less than 0.05). The rats treated with low-dose CsA after OIT lost weight and died of rejection after a mean survival time of 17.7 +/- 2 days, while the rats treated with low-dose CsA after HIT remained well until sacrifice on POD 28 (P less than 0.01). The rats with isografts and rats with allografts treated with high-dose CsA remained well after HIT and OIT until sacrifice on the 28th POD. These data suggest that nutrients and other factors in the succus entericus may improve gut barrier function and delay the onset of rejection after OIT. However, rejection of the orthotopic intestinal graft is usually fatal, while rejection of the heterotopic graft is often surprisingly well tolerated. These factors must be taken into consideration when choosing a surgical technique for intestinal transplantation in humans.

Animals↗