Biomedical subjects

H F Chen

Publications and source records attributed to H F Chen.

At least 19 recordsLinked to original sources

PubMed1999

Human peripheral blood mononuclear cells express gonadotropin-releasing hormone (GnRH), GnRH receptor, and interleukin-2 receptor gamma-chain messenger ribonucleic acids that are regulated by GnRH in vitro.

The hypothalamic decapeptide, GnRH, plays a critical role in human reproduction. In addition to the well known effects of GnRH on pituitary cells, there is evidence supporting the presence of GnRH-binding sites in tissues other than pituitary cells, including lymphocytes. In addition, a GnRH-like substance has been found to be secreted from lymphoid cells. However, the precise nature of GnRH secretion and binding in immune cells has not been fully established. In this study, we used the RT-PCR method to examine the expression and regulation of GnRH, GnRH receptor (GnRHR), and interleukin-2 receptor gamma-chain messenger ribonucleic acids (mRNAs) in human peripheral blood mononuclear cells. It was found that human mononuclear cells expressed GnRH and GnRHR mRNAs. Nucleotide sequences of these mRNAs are identical to their hypothalamic and pituitary counterparts, respectively. In addition, GnRH and GnRHR mRNA expressions in peripheral blood mononuclear cells are regulated by GnRH and its synthetic analogs in vitro. Treatment with various concentrations of GnRH (10(-5)-10(-11) mol/L) increased GnRHR mRNA expression in a dose-dependent manner (maximal level is 158% of the untreated control value at 10(-8) mol/L GnRH; P < 0.05), but reduced GnRH mRNA levels to 69% of the untreated control value at 10(-9) mol/L GnRH (P < 0.05). Cotreatment of GnRH with a GnRH antagonist blocked these regulatory effects, indicating the receptor-mediated nature of the GnRH action. Both GnRH and GnRH agonist stimulated interleukin-2 receptor gamma-chain mRNA in a dose-dependent manner, indicating that GnRH may be involved in lymphocyte activation. In summary, these observations suggest that mRNAs encoding the pituitary form of GnRHR and the hypothalamic form of GnRH are also expressed in human peripheral blood mononuclear cells. The endogenous production of GnRH by lymphocytes may act as an autocrine or paracrine factor to regulate immune functions. Because of the presence of GnRHR on lymphocytes, exogenous GnRH analog therapy may have an impact on the immune system through these receptors.

Adult↗

PubMed1998

Determination of metformin in plasma by capillary electrophoresis using field-amplified sample stacking technique.

A capillary electrophoresis method was described for the determination of metformin in human plasma based on the extraction of the ion-pair with bromothymol blue into chloroform. Phenformin was used as internal standard. Field-amplified sample stacking injection was employed with an electrokinetic injection voltage of 10 kV for 10 s. The running buffer was 0.1 M phosphate buffer (pH 2.5), running voltage was 20 kV and the UV absorbance detection was set at 195 nm. The limit of quantitation was 0.25 microg/ml. Linearity range of calibration curve was 0.25 to 3.5 microg/ml. Recoveries for three levels (0.25, 1 and 2 microg/ml) were 80.24%, 67.44% and 58.97% (n = 5 for each level), respectively. The intra-day precisions for the three levels were 11.9%, 3.09% and 4.33% and the inter-day precisions were 12.4%, 4.57% and 4.94%, respectively. The concentrations of metformin hydrochloride in human plasma of eight volunteers were measured after orally administrating metformin enteric-capsule and tablet.

Drug Stability↗

PubMed1997

A simplified technique for embryo biopsy: use of the same micropipette for zona drilling and blastomere aspiration.

PURPOSE: Using different micropipettes for zona drilling and blastomere aspiration for embryo biopsy is prevalent at centers of preimplantation genetic diagnosis. The purpose of our study was to simplify the technique by using only one micropipette. METHODS: In this animal model, ICR mouse embryos at the four-cell stage (n = 446) were randomly allocated into two groups; a biopsied group (n = 224) for blastomere aspiration and a control group (n = 222) without micromanipulation. We used a drilling/biopsy micropipette to drill a hole in the zona by expulsion of acidified Tyrode's solution and to aspirate the blastomere by gentle suction with the same micropipette and pull it out of the zona. One blastomere was biopsied from each embryo. RESULTS: In all, 222 (99.1%) intact blastomeres were successfully biopsied from 224 embryos. Only two blastomeres were damaged during aspiration. The capacity for blastocyst development (92.4 vs 93.7%) was not different between the two groups, but the percentages of embryos hatching (51.8 vs 18.0%) and hatched (29.9 vs 8.1%) were significantly higher in the biopsied group than in the control group. CONCLUSIONS: This simplified technique of embryo biopsy is safe and highly efficient for obtaining blastomeres for preimplantation genetic diagnosis and may also facilitate hatching of the blastocysts.

Animals↗

PubMed1997

Assisted hatching increases the implantation and pregnancy rate of in vitro fertilization (IVF)-embryo transfer (ET), but not that of IVF-tubal ET in patients with repeated IVF failures.

OBJECTIVE: To assess the effect of augmenting IVF with assisted hatching in the treatment of patients with repeated IVF failures. DESIGN: Prospective randomized study. SETTING: Division of Reproductive Endocrinology and Infertility of National Taiwan University Hospital. PATIENT(S): From July 1993 to February 1996, 49 patients with repeatedly failed IVF were treated with assisted hatching and were compared with 51 control subjects without assisted hatching. INTERVENTION(S): Assisted hatching. MAIN OUTCOME MEASURE(S): Pregnancy rate and implantation rate per embryo after IVF-ET or IVF-tubal ET (TET) were measured. RESULT(S): The pregnancy rate (PR) in the assisted hatching group was found to be 36.7% compared with 19.6% in the control group, but the difference was not significant. When only patients receiving IVF-ET were considered, it was observed that the PR was significantly higher in the assisted hatching group than the control group (42.4% versus 16.1%). With IVF-TET however, the PR was found to be similar in both assisted hatching and control groups (25.0% and 25.0%, respectively). The rate of embryonic implantation in the IVF-ET patients was 11.0%, which was significantly higher than that of control embryos (3.7%). CONCLUSION(S): These results implied that IVF-ET, combined with assisted hatching, may improve the PR and implantation rate in patients with repeated IVF failures, but the same was not true in the case of IVF-TET.

Embryo Implantation↗

PubMed1997

Mechanisms underlying stimulation of rapidly adapting receptors during pulmonary air embolism in dogs.

We investigated the mechanisms underlying stimulation of rapidly adapting receptors (RARs) during pulmonary air embolism (PAE). Impulses were recorded from RARs in 43 anesthetized, open-chest and artificially ventilated dogs. Forty one out of 56 RARs were stimulated by infusion of air into the right atrium (0.2 ml/kg per min for 10 min). As a group (n = 56), RAR activity increased from a baseline of 1.2 +/- 0.2 to a peak of 4.3 +/- 0.3 impulses/breath at 8-10 min after the onset of PAE induction. PAE also caused an increase in total lung resistance and a decrease in dynamic lung compliance. Studies were repeated in 33 RARs initially stimulated by PAE. In nine receptors, hyperinflation of the lungs performed at the termination of the second PAE induction largely reversed both the afferent and bronchomotor responses. Furthermore, the residual PAE-evoked activity subsequent to hyperinflation was almost eliminated by elevation in the heart position. In another 24 receptors, the responses of RARs to PAE were unaltered by pretreatment with saline (n = 8) or dimethylthiourea (a hydroxyl radical scavenger; n = 8), but was significantly attenuated by pretreatment with ibuprofen (a cyclooxygenase inhibitor: n = 8). These results suggest that: (1) the increased RAR activity following PAE is associated primarily with an increase in bronchomotor tone and secondarily with the mechanical action of the beating heart impacting on lung tissues; and (2) cyclooxygenase products may be involved in this sensory stimulation.

Afferent Pathways↗

PubMed1997

Mechanisms of stimulation of vagal pulmonary C fibers by pulmonary air embolism in dogs.

We investigated the involvement of the cyclooxygenase metabolites and hydroxyl radical (.OH) in the stimulation of vagal pulmonary C fibers (PCs) by pulmonary air embolism (PAE). Impulses were recorded from PCs in 51 anesthetized, open-chest, and artificially ventilated dogs. Fifty of 59 PCs were stimulated by infusion of air into the right atrium (0.2 ml.kg-1.min-1 for 10 min). As a group (n = 59), PC activity increased from a baseline of 0.4 +/- 0.1 to a peak of 1.7 +/- 0.2 impulses/s during the period from 1 min before to 2 min after the termination of PAE induction. In PCs initially stimulated by PAE induction, PAE was repeated after the intervening treatment (iv) with saline (n = 9), ibuprofen (a cyclooxygenase inhibitor; n = 11), or dimethylthiourea (a .OH scavenger; n = 12). The responses of PCs to PAE were not altered by saline vehicle but were abolished by ibuprofen and significantly attenuated by dimethylthiourea. Although hyperinflation of the lungs reversed the PAE-induced bronchomotor responses, it did not reverse the stimulation of PCs (n = 8). These results suggest that 1) cyclooxygenase products are necessary for the stimulation of PCs by PAE, whereas changes in lung mechanics are not, and 2) the functional importance of cyclooxygenase products may be mediated in part through the formation of .OH.

Animals↗

PubMed1997

[Effect of puerarin on plasma endothelin, renin activity and angiotensin II in patients with acute myocardial infarction].

OBJECTIVE: To study the changes of endothelin (ET), renin activity (RA) and angiotensin II (AT-II) before and after puerarin treatment in patients with acute myocardial infarction (AMI). METHODS: Forty-three patients with AMI were divided into two groups, and were given puerarin and glucose-insulin-kalium (GIK) treatment respectively. Plasma ET, RA and AT-II were measured by radioimmunoassay (RIA) before and after treatment in different phases. RESULTS: It showed that plasma ET and RA, AT-II levels in AMI were higher than those in control group (P < 0.01). ET level was conversely correlated with RA and AT-II (P < 0.01). After treatment with puerarin, plasma levels of ET, RA and AT-II were recovered to normal in 3 days, but these data recovered to nearly normal until 7-14 days in group with GIK treatment. CONCLUSION: Puerarin might play an important role in regulating the imbalance of ET, RA and AT-II of patients with AMI.

Aged↗

PubMed1996

Positive charge at position 549 is essential for phosphatidylinositol 4,5-bisphosphate-hydrolyzing but not phosphatidylinositol-hydrolyzing activities of human phospholipase C delta1.

Point mutagenesis, phosphatidylinositol (PI), and phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis assays and equilibrium centrifugation PIP2 assays were used to study the functional roles of four highly conserved arginine residues in the Y region of human phospholipase C delta1 (PLCdelta1) (Arg-527, -549, -556, -701). Most of the mutant enzymes were either partially defective or fully active in their abilities to catalyze the hydrolysis of PI or PIP2. However, upon substitution of Arg-549 by glycine or histidine, the mutant enzyme was defective in its ability to catalyze the hydrolysis of PIP2, but it is still able to hydrolyze PI. Replacing Arg-549 with lysine had little effect on the level of PI and PIP2 hydrolytic activities of the mutant enzyme. The residual PIP2 hydrolyzing activity of R549H is highly dependent on pH. R549H showed 5-10% of the PIP2-hydrolyzing activity of the native enzyme between pH 5 and 7 and nondetectable PIP2-hydrolyzing activity at pH 8. The PIP2-hydrolyzing activity of R549G was not detectable at all pH values. Kinetic analysis of PLCdelta1-catalyzed PIP2 hydrolysis revealed that the micellar dissociation constant Ks and interfacial Michaelis constant Km were similar in the native, R549K, and R549H enzymes; but the specific activity at the saturated substrate mole fraction and infinite level of substrate (Vmax) of the R549H mutant were reduced by a factor of 15. PIP2 competitively inhibits the native enzyme to hydrolyze PI at both pH 7 and 8. However, PIP2 inhibits R549H only at pH 7.0 and does not inhibit R549G at either pH. Taken together, these results suggest that positive charge at position 549 of PLCdelta1 protein is essential for the enzyme to recognize and catalyze the hydrolysis of PIP2 but not PI.

Calcium↗

PubMed1996

Decrease in interferon gamma production and impairment of T-lymphocyte proliferation in peritoneal fluid of women with endometriosis.

OBJECTIVE: Our purpose was to verify regional immune modulations and to test the effect of gonadotropin-releasing hormone agonist in women with endometriosis. STUDY DESIGN: Concentrations of peritoneal cytokines, including interleukin-1 beta, interleukin-2, soluble interleukin-2 receptor, interleukin-6, granulocyte-monocyte colony-stimulating factor, interferon gamma, and tumor necrosis factor-alpha were compared in women with and without endometriosis. Peritoneal cytokine and interleukin-2 production were examined by adding various mitogens to peritoneal fluid mononuclear cells of women with advanced endometriosis before and after gonadotropin-releasing hormone agonist treatment. RESULTS: A significant increase in peritoneal interleukin-1 beta, interleukin-6, and tumor necrosis factor-alpha and a decrease in interferon gamma were noted in women with endometriosis. After gonadotropin-releasing hormone agonist treatment interleukin-6 decreased and interferon gamma increased. A significant impairment of interleukin-2 production of peritoneal fluid mononuclear cells by phytohemagglutinin and pokeweed mitogen stimulation was demonstrated in endometriosis, and production could be restored after gonadotropin-releasing hormone agonist treatment. CONCLUSION: These results indicate that regional immunologic dysfunction might be invoked in the disease process of endometriosis.

Ascitic Fluid↗

PubMed1996

Fertilization and embryo cleavage after intracytoplasmic spermatid injection in an obstructive azoospermic patient with defective spermiogenesis.

OBJECTIVE: To achieve fertilization and cleavage by spermatids without tails from testicular biopsy. DESIGN: Clinical trial. SETTING: Reproductive unit of a university teaching hospital. PATIENT: A patient of obstructive azoospermia with defective spermiogenesis. INTERVENTION: Testicular biopsy after scrotal exploration and spermatid injection into the cytoplasm of oocyte. MAIN OUTCOME MEASURES: Fertilization and cleavage. RESULTS: Four of 13 spermatid injections achieved normal fertilization and 2 of them cleaved. CONCLUSION: Intracytoplasmic spermatid injection may be a possible treatment for patients of defective spermiogenesis who have no viable spermatozoa available.

Adult↗

PubMed1996

Intracytoplasmic sperm injection (ICSI) for severe semen abnormalities: dissecting the tail of spermatozoa at the tip.

Recently, several investigators have emphasized that damaging the membrane of spermatozoa by compressing the mid-piece or cutting the mid-portion of the tail prior to injection yields better results than using motile spermatozoa in intracytoplasmic sperm injection (ICSI). Here we report our experience using a modified immobilization technique of dissecting the tail of the spermatozoon at the tip in 78 cycles on 60 patients. In 55 treatment cycles purely using this modified technique, 468 mature oocytes were injected. A total of 35 oocytes (7.5%) were injured. Of the intact oocytes, 282 (65.1%) were normally fertilized and 266 (94.3%) subsequently cleaved. A single pronucleus was observed in 16 (3.7%) oocytes, and three pronuclei were noted in 11 (2.5%) oocytes. Embryo transfers were performed in 54 cycles, and 18 women (32.7%) achieved clinical pregnancies. In 23 cycles, we compared the effects of these three immobilization techniques on the sibling oocytes obtained from the same patient regarding normal fertilization, abnormal fertilization, and embryo cleavage and quality. The results were comparable among them. Seven pregnancies (30.4%) were achieved in this series. Dissecting a sperm tail at the tip is easily and quickly performed and achieves permanent immobilization. Compression of the mid-piece is also easy, but usually takes several actions to achieve immobilization. Cutting the tail at the mid-portion requires more skill. Therefore, dissecting the tail of the spermatozoon at the tip may provide an alternative method to immobilize the spermatozoon permanently prior to ICSI.

Adult↗

PubMed1996

Pregnancy achieved by intracytoplasmic sperm injection using cryopreserved semen from a man with testicular cancer.

A successful pregnancy was achieved by intracytoplasmic sperm injection (ICSI) using cryopreserved semen from a man with testicular cancer. He was a victim of right testicular seminoma, and was azoospermic after right orchidectomy and radiotherapy. The wife had had three successive failures of intrauterine insemination (IUI) using semen that was cryopreserved before radiotherapy. The couple then underwent in-vitro fertilization (IVF) treatment. ICSI was performed because the sperm motility was extremely poor after thawing. Eight of 12 injected oocytes had normal fertilization and embryo cleavage. After replacement of four embryos, a singleton pregnancy developed. She delivered a healthy male baby at 39 weeks gestation. In addition to IUI and IVF, ICSI further provides male patients with cancer an improved chance of fathering a child. Any men diagnosed with cancer who have not yet finished their families should have their spermatozoa frozen before treatment, regardless of its quality.

Cryopreservation↗

PubMed1996

The value of human growth hormone as an adjuvant for ovarian stimulation in a human in vitro fertilization program.

The purpose of this study was to evaluate whether the combined treatment of growth hormone (GH) and gonadotropins can improve ovulation stimulation in previously poor responders. Twelve patients who, had suboptimal responses in previous in vitro fertilization cycle were enrolled. They underwent 1 cycle with gonadotropin-releasing hormone analogue (GnRH-a) and gonadotropins and another cycle with GnRH-a, gonadotropins, and GH. Serum gonadotropins, insulin-like growth factor-1 (IGF-1), and sex steroids, including estradiol (E2), progesterone (P4), testosterone, and androstenedione were measured on Day 2 and during ovulation induction. The serum IGF-1 level was higher in the GH cycle. There were no significant differences in the levels of the serum luteinizing hormone, E2, P4, testosterone, and androstenedione between the 2 cycles, so was IGF-1, E2 and P4 in follicular fluid. Co-treatment with GH did not improve the ovarian response. However, the GH cycles had better performance in terms of the number of oocytes fertilized and the pregnancy rate.

Androstenedione↗

PubMed1996

The suppression of peritoneal cellular immunity in women with endometriosis could be restored after gonadotropin releasing hormone agonist treatment.

PROBLEM: Our previous study reported that peritoneal natural killer (NK) cytotoxicity and CD3+CD25+ lymphocyte subpopulation were suppressed in women with advanced endometriosis. Whether these phenomena are general for all stages of endometriosis and whether these alterations could be restored by long-term use of gonadotropin releasing hormone agonist (GnRHa) are further tested in this study. METHOD: Lymphocyte subpopulations (B cells, NK cells, T cells, and T-cell activation markers such as CD69, HLA-DR, and CD25) and NK cell cytotoxicity of peripheral blood and peritoneal fluid by dual-color flow cytometry and 51Cr release assay in 30 cases of endometriosis were compared with those in 26 controls. We also compared these changes before and after 6-month treatment with GnRHa for advanced endometriosis. RESULTS: Compared with the controls, only those women with advanced endometriosis showed lower NK cytotoxicity in peritoneal fluid mononuclear cells (PFMC). The CD3+CD69+ lymphocyte subpopulation decreased in peripheral blood mononuclear cells (PBMC) of advanced endometriosis, while the CD3+CD25+ lymphocyte subpopulation decreased in both PBMC and PFMC of mild and advanced endometriosis. After GnRHa treatment, the CD3+CD69+ lymphocyte subpopulation increased in both PBMC and PFMC and the CD3+CD25+ lymphocyte subpopulation increased in PFMC, but not in PBMC. CONCLUSION: Impaired local immunological function in the PF of endometriosis was confirmed by this study and the impairments could be restored after long-term GnRHa therapy.

Ascitic Fluid↗

PubMed1996

How many embryos should be transferred in in vitro fertilization and tubal embryo transfer?

In order to achieve higher pregnancy rates, more than one embryo is usually transferred in in vitro fertilization (IVF) programs. Tubal embryo transfer (TET) produces an even higher pregnancy rate. However, the number of embryos that should be transferred in TET programs remains to be clarified. We studied a series of 241 consecutive TET cycles and analyzed their clinical characteristics, embryo numbers, cumulative embryo score (CES), and pregnancy outcomes. The results demonstrated that 1) four embryos was an adequate number to obtain a satisfactory pregnancy rate and fewer multiple pregnancies, 2) older patients and cases with male factor had less chance of pregnancy and more than four embryos could be transferred, and 3) CES values > 40 were preferred, but for young patients with unusually high anxiety about multiple pregnancies, a CES of 21 to 40 was optimal. A policy of transfer that limits transfer to a maximum of two, three or four embryos is not suitable in all cases and other factors (eg, repeated IVF failure or older age) should be individually considered. Therefore, two equations utilizing CES, age and failure of previous TET as the factors were developed to help practitioners to evaluate how many embryos should be transferred on an individual basis.

Adult↗

PubMed1995

Cytomegalovirus infection and viral shedding in the genital tract of infertile couples.

The prevalence of cytomegalovirus (CMV) infection and viral shedding in infertile couples in Taiwan and its role in infertility were studied. Two hundred fifty couples were enrolled in this study. Anti-CMV IgG was measured in serum samples from these infertile couples. Viral shedding examined by DNA hybridization was detected in semen from the husband and cervical mucus from the wife. Anti-CMV IgG was detected in 249 (99.6%) of the 250 male serum samples and in 247 (98.9%) of the 250 female serum samples. Viral shedding was detectable in 83 (33.5%) of 248 semen samples and 83 (33.7%) of 246 cervical mucus samples by dot-blot DNA hybridization assay. Semen quality was not apparently affected by the existence of viral shedding. The co-shedding rate in semen and cervical mucus was high (15.9%). It is concluded that the seroprevalence and genital tract viral shedding were relatively high in infertile couples in Taiwan. Viral shedding did not affect the semen quality. Nevertheless, screening of donor semen is recommended.

Adolescent↗

PubMed1995

Ketone EC50 values in the Microtox test.

The Microtox EC50 values for the following ketones are reported in the following homologous series: straight chain methyl ketones (acetone, 2-butanone, 2-pentanone, 2-hepatonone, 2-octanone, 2-decanone, and 2-tridecanone); methyl ketones substituted at one alpha carbon (3-methyl-2-butanone; 3,3-dimethyl-2-butanone); methyl substituted at two alpha carbons (2,4-dimethyl-3-pentanone; 2,2,4,4-tetramethyl-3-pentanone); phenyl groups replacing methyl in acetone (acetophenone; benzophenone); methyl groups substituted at the alpha carbons of cyclohexanone; and 2,3- 2,4-, and 2,5-hexanediones, most for the first time. While there were linear relationships between log EC50 and MW for the straight chain methyl ketones, and for methyl substitution at the alpha carbon for methyl ketones, there were no other linear relationships. As molecular weight increased, the EC50 values of soluble ketones decreased; as distance between two carbonyl groups decreased so too did EC50 values. Thus, for the ketones the geometry around the carbonyl group is an important determinant of toxicity as well as MW, water solubility, and octanol/water coefficient.

Ketones↗

PubMed1995

Comparison between a two-layer discontinuous Percoll gradient and swim-up for sperm preparation on normal and abnormal semen samples.

PURPOSE: This work was to compare the effects of Percoll gradient and swim-up treatments for sperm preparation on the percentage of progressive motility, recovery of motile sperm, removal of debris, percentage of normal forms according to strict criteria, and movement characteristics of sperm using computer-assisted velocity analysis. RESULTS: In total, 50 semen samples from 50 patients were tested and divided into two groups: a normal group (n = 27) with normal parameters and an abnormal group (n = 23) with abnormal parameters. The results in both the normal and abnormal groups revealed that the sperm concentration in the Percoll samples was significantly greater than that in the swim-up samples. Although the percentage of progressive motility was greater in the swim-up samples than in the Percoll samples, the number of motile sperm, reflecting the percentage of motile sperm recovery, was till greater in the Percoll samples. The debris of semen was equally removed by both methods and the percentage of normal forms was also similar in the samples treated according to these two procedures. Both curvilinear velocity (VCL) and straight-line velocity (VSL) of sperm were significantly greater in the swim-up samples than in the Percoll samples. Sperm from the swim-up procedure also showed a greater mean amplitude of lateral head displacement than that from the Percoll gradient procedure, but the distinction was insignificant. CONCLUSION: The Percoll gradient technique, by recovering more motile sperm, may be applied to prepare oligospermic samples. The swim-up method may become the standard choice to prepare normal semen which could obtain sufficiently motile sperm, due to its simplicity and recovered sperm with superior motility.

Centrifugation, Density Gradient↗