Biomedical subjects
C H Chen
Publications and source records attributed to C H Chen.
Effect of K+ channel openers on K+ channel in cultured human dermal papilla cells.
Minoxidil sulfate and pinacidil, well-known activators of the ATP-sensitive K+ (KATP) channel, induce hair growth in clinical studies. The opening of K+ channels is thought to be an important mechanism in the regulation of hair follicles. In the present study, we used the patch clamp technique to characterize the K+ channels and tested the effect of K+ channel openers on K+ channels in cultured human dermal papilla cells. In dermal papilla cells, the Ca(2+)-activated K+ (KCa) channel with large conductance (179.3 +/- 13.1 pS in symmetrical 150 mM K+ solutions, n = 9) was dominant and we could not observe KATP channels in cell-attached and inside-out patches. In addition, minoxidil and pinacidil failed to activate KATP or KCa channels. In inside-out membrane patches, the channel was blocked by 10 mM tetraethylammonium ion, 2 mM 4-aminopyridine to the cytosolic face of the membrane or by lowering Ca2+ using 10 mM EGTA, but not by glibenclamide. In the cell-attached patch configurations, extracellular application of 1 mM sodium nitroprusside, a nitrovasodilator, activated the KCa channel. Methylene blue (2 mM) inhibited channel activation by sodium nitroprusside. Extracellular application of 20 mM dibutyryl cGMP activated the KCa channel, suggesting that channel activation is mediated by cGMP. Nitrovasodilators, which have no effect on hair growth, now appear to activate KCa channels in dermal papilla cells. These results suggest that increased K+ permeability itself in dermal papilla cells may not be sufficient for promotion of hair growth.
Extensive thrombophlebitis with reactive thrombocytosis in a high risk Chinese parturient associated with retained placenta increta: a case report.
Postpartum thrombophlebitis is an infrequent disorder in Chinese women. A case is reported of extensive postpartum thrombophlebitis involving 23 cm of the femoral and pelvic veins. This 25-year-old splenectomized victim of beta-thalassemia was bedridden for 12 weeks because of threatened premature labor before Cesarean delivery. During the operation, placenta increta with massive bleeding was encountered. To save the uterus, ten percent of the placenta was retained. Duplex color Doppler imaging was performed for the diagnosis and follow-up of the thrombosis and vigorous anticoagulation therapy successfully cured this patient.
Low-flow anesthesia in adult orthotopic liver transplantation: a preliminary clinical experience.
BACKGROUND: Anesthesia in orthotopic liver transplantation (OLT) may carry with complex hemodynamic, body temperature, and metabolic alterations. Although OLT cases increased in recent years in Taiwan, experiences remained limited. Notable advantage of low flow anesthesia may include reduced consumption of anesthetic gases and vapors, reduced environmental pollution and cost-saving. This study investigated patient profiles and the feasibility of low-flow rebreathing technique for adult orthotopic liver transplantation. METHODS: Since June 1996, there were six OLT patients who received low flow anesthesia with isoflurane. All patients received hepatic veno-venal anastmosis (so-called piggy back procedure). Two patients were excluded from this study because of different surgical procedure (total occlusion of inferior vena cava and inferior vena cava veno-venal anastmosis). During maintenance of anesthesia, isoflurane was carried by a mixture of oxygen and air at a total fresh gas flow of 0.6 L/min. Alongside with the standard anesthesia machine and physiologic monitors, a newly designed Swan-Ganz catheter was introduced to measure and record cardiac output, systemic vascular resistance, pulmonary artery pressure, central venous pressure, and core temperature in a real-time manner. Blood samples were collected at 6 predetermined time-points in each patient for analysis of arterial blood gases, electrolytes, lactate and glucose concentrations. RESULTS: The anesthetic time was 916 +/- 26 min (900 to 930 min). All patients regained their consciousness within 30 min after completion of surgery. The hemodynamics were relatively stable except after reperfusion of the liver. There was a significant decrease in mean arterial blood pressure, which occurred with accompaniment of a reduction of systemic vascular resistance and increased cardiac output. Arterial blood gas, electrolyte, and glucose were, however, maintained within acceptable limits. Blood lactate was progressively increased and reached its peak after reperfusion of the liver until the end of surgery. The core temperature was well maintained above 34 degrees C. No patient developed hypoxia or hypercapnia. CONCLUSIONS: Low-flow rebreathing anesthetic technique maintained acceptable patient profiles and good body temperature preservation in orthotopic liver transplantation. These characteristics make it a promising method in maintenance of anesthesia for OLT.
Propofol anesthesia in a patient with Isaacs syndrome--report of a case and literature review.
Isaacs syndrome is an unusual lower motor neuron disease characterized by myokymia (muscle twitching), muscular stiffness, and decreased tendon reflexes. We reported a patient who was affected with this rare disease, with manifestation of involuntary muscular contractions and required general anesthesia for bilateral tonsillectomies. Understanding the presentation and characterization of this unusual disease may be helpful in making choice of anesthetics or anesthetic techniques. Its possible mechanisms of action and its specific considerations in anesthesia in the literature are reviewed and discussed.
Complete eradication of hepatitis C virus after interferon treatment for chronic hepatitis C.
BACKGROUND: Alpha-interferon therapy can lead to a persistent biochemical response, but discordant opinions have been expressed on the definition of sustained response and on the real possibility of complete eradication of hepatitis C virus (HCV). AIMS: To define the clinical, virological and histologic profiles of the patients with sustained response. PATIENTS: Twenty-eight patients with three different biochemical and virological patterns of response to interferon therapy (16 sustained responders, 6 responders with relapse and 6 non responders) were studied for a follow-up period of 36 months. METHODS: HCV-RNA sequences were investigated in serum, peripheral blood mononuclear cells and in liver tissue by means of reverse transcriptase-polymerase chain reaction, targeted to the 5' non coding region. Viral load in serum was quantified by branched-DNA signal amplification. HCV genotypes were evaluated using a line probe assay. RESULTS: All sustained responders showed persistent normal ALT values and loss of serum HCV-RNA during the treatment and in the entire follow-up period. The HCV clearance was also demonstrated in peripheral blood mononuclear cells and in liver tissue. Pre-treatment HCV-RNA quantitation showed that sustained responders had a significantly lower viral load compared to relapsers and non responders (p = 0.005). HCV genotyping showed that patients infected by genotypes 2a, 3a were more likely to achieve a sustained response. Interestingly, a prolonged response was also observed in the only three patients with pre-treatment detectable viral load infected by genotype 3a and in patients with genotype 1b and low viraemia levels. To assess the histologic outcome following HCV eradication, all sustained responders underwent a second liver biopsy in the follow-up period (6-18 months). Periportal necrosis and portal inflammation were significantly improved. CONCLUSIONS: Our results suggest that persistent loss of HCV-RNA in serum, peripheral blood mononuclear cells and liver as well as histologic improvement are consistent with the complete HCV eradication even from intracellular compartments and from potential extra-hepatic sites of viral persistence. Moreover, pre-treatment viral load, HCV infecting genotypes and histologic features may influence the clinical outcome of hepatitis C and the response to interferon therapy.
Characterization of avian T-cell receptor gamma genes.
In birds and mammals T cells develop along two discrete pathways characterized by expression of either the alpha beta or the gamma delta T-cell antigen receptors (TCRs). To gain further insight into the evolutionary significance of the gamma delta T-cell lineage, the present studies sought to define the chicken TCR gamma locus. A splenic cDNA library was screened with two polymerase chain reaction products obtained from genomic DNA using primers for highly conserved regions of TCR and immunoglobulin genes. This strategy yielded cDNA clones with characteristics of mammalian TCR gamma chains, including canonical residues considered important for proper folding and stability. Northern blot analysis with the TCR gamma cDNA probe revealed 1.9-kb transcripts in the thymus, spleen, and a gamma delta T-cell line, but not in B or alpha beta T-cell lines. Three multimember V gamma subfamilies, three J gamma gene segments, and a single constant region C gamma gene were identified in the avian TCR gamma locus. Members of each of the three V gamma subfamilies were found to undergo rearrangement in parallel during the first wave of thymocyte development. TCR gamma repertoire diversification was initiated on embryonic day 10 by an apparently random pattern of V-J gamma recombination, nuclease activity, and P-and N-nucleotide additions to generate a diverse repertoire of avian TCR gamma genes early in ontogeny.
Identification of a BglI polymorphism of catechol-O-methyltransferase (COMT) gene, and association study with schizophrenia.
Several linkage studies suggested chromosome 22q11-13 may harbor susceptible genes for schizophrenia. Catechol-O-methyl-transferase (COMT), which is involved in the metabolism of catecholamines, was mapped to 22q11 and is considered a possible candidate gene for schizophrenia. Recently, we identified a polymorphic marker, a single nucleotide C insertion at the 3' untranslated region of the COMT gene, which obliterates a BglI site. Using this BglI polymorphism, we conducted a case-control association study in Chinese patients with schizophrenia. No significant differences of allele and genotype frequencies were noted between patients (N = 177) and controls (N = 99). When patients were subgrouped according to sex, no significant differences of genotype and allele frequencies were noted in either male or female patients compared to normal controls. Our results do not support an association between the BglI polymorphism of COMT gene and schizophrenia.
Single-beat estimation of end-systolic pressure-volume relation in humans. A new method with the potential for noninvasive application.
BACKGROUND: The end-systolic pressure-volume relation (ESPVR) provides a useful measure of contractile function. However, the need to acquire multiple cardiac cycles at varying loads limits its applicability. We therefore developed and tested a novel single-beat estimation method that is based on normalized human time-varying elastance curves [EN(tN)]. METHODS AND RESULTS: Pressure-volume (PV) data were measured by conductance catheter in 87 patients with normal or myopathic hearts. Time-varying elastance curves were generated from 72 PV loops (52 patients) and normalized both by amplitude and time to peak amplitude. The resulting EN(tN) curves were remarkably consistent despite variations in underlying cardiac disease, contractility, loading, and heart rate, with minimal interloop variance during the first 25% to 35% of contraction. On the basis of this finding and assuming ESPVR linearity and constant volume-intercept, ESPVRs were estimated from one beat with the use of PV data measured at normalized time (tN) and end systole (tmax) to predict intercept: Vo(SB) = [EN(tN) x P(tmax) x V(tN)-P(tN)x V(tmax)]/[EN(tN) x P(tmax)-P(tN)] and slope Emax(SB) = Pes/[Ves-Vo(SB)]. Single-beat estimates were highly correlated with measured ESPVR values obtained by standard multiple-beat analysis (including data from 35 additional patients). Emax(SB) accurately reflected acute inotropic change and was influenced little by loading. The new estimation method also predicted measured ESPVRs better than prior techniques and was applicable to noninvasive analysis. CONCLUSIONS: ESPVRs can be reliably estimated in humans from single cardiac cycles by a new method that has a potential for noninvasive application.
ABO genotyping by mutagenically separated polymerase chain reaction.
ABO blood groups were determined by the mutagenically separated polymerase chain reaction (MS-PCR). The products from two sets of PCR reactions using the same program for the nucleotides at positions 261 and 703 from cDNA at the ABO locus were used to distinguish A, B and O alleles. Two forward mutagenic allele-specific primers of different lengths for the ABO polymorphic site were paired with the same reverse primer in each PCR reaction. The 216 bp fragment of the PCR products for the 261th nucleotide was A or B allele-specific and the 195 bp fragment was O allele-specific. The 126 bp fragment of the PCR products for the 703th nucleotide was B allele-specific and the 106 bp fragment was A or O allele-specific. The ABO genotypes were determined by the intersection of the predicted alleles from these two PCR reactions. The PCR products were obtained using 10 ng of DNA in 50 microL of PCR reaction mixture, and electrophoresed in 4% agarose gel. In this study, 265 ABO-phenotype known samples (A: 31, B: 48, AB: 6 and O: 180) in Chinese were used. The results of ABO genotypes were AA: 1, AO: 30, BB: 2, BO: 46, AB: 6 and OO: 180. These results were confirmed by the PCR-RFLP ABO genotyping method. This technique is a simple, rapid, and reliable method for ABO genotyping.
A protein kinase C translocation inhibitor as an isozyme-selective antagonist of cardiac function.
Protein kinase C (PKC) isozymes translocate to unique subcellular sites following activation. We previously suggested that translocation of activated isozymes is required for their function and that in addition to binding to lipids, translocation involves binding of the activated isozymes to specific anchoring proteins (receptors for activated protein kinase C. Using cultured cardiomyocytes we identified inhibitors, the V1 fragment of epsilonPKC (epsilonV1), and an 8-amino acid peptide derived from it that selectively inhibited the translocation of epsilonPKC. Inhibition of epsilonPKC translocation but not inhibition of delta or betaPKC translocation specifically blocked phorbol ester- or norepinephrine-mediated regulation of contraction. These isozyme-selective translocation inhibitors provide novel tools to determine the function of individual PKC isozymes in intact cells.
Lack of association between TaqI A1 allele of dopamine D2 receptor gene and alcohol-use disorders in atayal natives of Taiwan.
Association studies between the A1 allele of the dopamine D2 receptor (DRD2) gene TaqI A polymorphism and alcoholism remain controversial. A recent study from Japan demonstrated that the A1 allele is associated with severe alcoholism in the Japanese population. We were interested in knowing if this association also exists in the Atayals of Taiwan, who were found to have a higher prevalence of alcohol-use disorders than the Han Chinese in Taiwan. Genotype and allele frequencies were determined in alcohol-abusing, alcohol-dependent, and nonalcoholic control Atayal natives in Taiwan. A1 allele frequencies in alcohol-dependent, alcohol-abusing, and normal control Atayals were 0.39, 0.42, and 0.39, respectively. No difference in A1 allele frequency was found among these three groups. Our data do not support the hypothesis that the A1 allele of the TaqI A polymorphism of the DRD2 gene increases susceptibility to alcohol-use disorders in the Atayals of Taiwan.
Thermodynamic and fluorescence studies of the underlying factors in benzyl alcohol-induced lipid interdigitated phase.
To further investigate factors contributing to the action of alcohol in the solute-induced lipid interdigitation phase, thermodynamic and fluorescence polarization measurements were carried out to study the interaction of benzyl alcohol with dipalmitoyl phosphatidylcholine bilayer vesicles. The obtained results were compared with those previously reported for ethanol and cyclohexanol (L. G. Roth and C-H. Chen, Arch. Biochem. Biophys. 296, 207, 1992). Similar to ethanol, benzyl alcohol was found to exhibit a biphasic effect on the enthalpy (delta Hm) and the temperature (tm) of the lipid-phase transition and the steady-state fluorescence polarization (P) monitored by 1,6-diphenyl-1,3,5-hexatriene. At a total concentration of benzyl alcohol < 30 mg/ml (the alcohol concentration in lipid phase < 21 mg/ml), benzyl alcohol was found to exhibit large increases in delta Hm and P, which were correlated with the formation of a lipid interdigitated phase, as evidenced by reported X-ray diffraction data. Combining the results with benzyl alcohol and ethanol suggested that simultaneously large changes in delta Hm and P can be used as an indication of the occurrence of a solute-induced lipid interdigitated phase. The overall interacting force in the formation of this lipid phase, as derived from the interactions of the hydroxyl portion of an alcohol with the lipid phosphate head group and the hydrophobic portion of an alcohol with the lipid hydrocarbon chains, may or may not be dominated by hydrophobic interaction. Although lipid/water partition coefficients and the contribution of hydrophobic interaction to the overall interacting force were comparable between benzyl alcohol and cyclohexanol, benzyl alcohol induced lipid interdigitated phase, but not for cyclohexanol. This was due to the ability of benzyl alcohol to be more effective than cyclohexanol in simultaneously interacting with the phosphate head group and the hydrocarbon chains of lipid.
Apoptosis induced by X-irradiation of rec-myc cells is postmitotic and not predicted by the time after irradiation or behavior of sister cells.
Rat embryo cells expressing the c-myc oncogene (rec-myc) were studied by time-lapse microscopy to determine whether radiation-induced apoptosis occurred before or after mitosis. Following X-irradiation with 9.5 Gy, cells were imaged every 3 min for 6 days. Episodes of apoptotic blebbing were very consistent from cell to cell, lasting 30-60 min, followed by cessation of movement and cell death. In contrast, the time of initiation of apoptotic blebbing was unpredictable. At least 96% of the apoptotic episodes were postmitotic, after one to four cell divisions and 2-97 h after a given division. Sister cells often behaved differently from one another, with apoptosis in one sister occurring many h or several divisions after apoptosis in the other. Thus, the onset of radiation-induced apoptosis in rec-myc cells is not strictly programmed but may result from the segregation of chromosome aberrations in the postirradiation generations.
No association of dopamine D2 receptor molecular variant Cys311 and schizophrenia in Chinese patients.
A serine-to-cysteine mutation of dopamine D2 receptor at codon 311 (Cys311) was found to have higher frequency in schizophrenic patients than in normal controls in Japanese by Arinami et al. [1994: Lancet 343: 703-704]. The Cys311 allele was found to be associated with patients with younger age-of-onset, positive family history, and more positive symptoms. To investigate the possible involvement of Cys311 in schizophrenia in the Chinese population, 114 unrelated Taiwanese Chinese schizophrenic patients with positive family history and 88 normal controls were genotyped for Cys311. Four patients and 5 normal controls were heterozygotes of Ser311/Cys311; no homozygotes of Cys311 were identified in either group. The allele frequencies of Cys311 in Chinese schizophrenic patients and normal controls were 2% and 3%, respectively. No significant difference was detected between the two groups. Our results do not support the argument that the Cys311 allele of DRD2 poses a genetic risk for certain types of schizophrenia in Chinese populations.
Hedgehog patterning activity: role of a lipophilic modification mediated by the carboxy-terminal autoprocessing domain.
Autocatalytic processing mediated by the carboxyterminal domain of the hedgehog (hh) protein precursor (Hh) generates an amino-terminal product that accounts for all known signaling activity. The role of autoprocessing biogenesis of the hh signal has been unclear, since a truncated unprocessed protein lacking all carboxy-terminal domain sequences retains signaling activity. Here, we present evidence that the autoprocessing reaction proceeds via an internal thioester intermediate and results in a covalent modification that increases the hydrophobic character of the signaling domain and influences its spatial and subcellular distribution. We demonstrate that truncated unprocessed amino-terminal protein causes embryonic mispatterning, even when expression is localized to cells that normally express Hh, thus suggesting a role for autoprocessing in spatial regulation of hh signaling. This type of processing also appears to operate in the biogenesis of other novel secreted proteins.
Prevalence of coronary heart disease in Kin-Chen, Kinmen.
We estimated the prevalence of coronary heart disease (CHD) by the Minnesota code of a 12-lead resting electrocardiogram, Rose chest pain questionnaire and self-reported previous medical history in Kin-Chen, Kinmen (Quemoy), an island under military control for 40 years and the focal point of confrontation between mainland China and Taiwan. Among the target population of 6346 who accounted for all residents aged over 30, 3826 (60.3%) responded with complete data. The prevalence of probable CHD (Minnesota code 1.1-1.2) was 4.1% (71/1732) in men and 4.0% (84/2094) in women, whereas the prevalence of possible CHD (Minnesota code 1.3, 4.1-4.4, 5.1-5.3 and 7.1.1) was significantly higher in women (21.4%) than in men (11.6%). When compared to Chinese populations elsewhere, the increased overall prevalence may suggest a link to long-term stress conditions under military control. We also found the abnormal ECG was associated with many risk factors of CHD, particularly win women. The prevalence of Rose angina and self-reported angina or myocardial infarction was, however, low and associated poorly with any cardiovascular risk factors. Long-term follow-up studies are needed to determine the predictive value of these electrocardiographic abnormalities for cardiovascular disease morbidity and mortality in this population.
Thermodynamic stabilization of nucleotide binding to thymidylate synthase by a potent benzoquinazoline folate analogue inhibitor.
The stabilization of dUMP, FdUMP, and dGMP binding to Escherichia coli thymidylate synthase (TS) in the presence and absence of a folate analogue inhibitor of TS, 1843U, was determined by differential scanning calorimetry. When the enzyme is thermally unfolded in the presence of dUMP, two separate temperature transitions are evident, although only one binding site/dimer was detected in equilibrium dialysis experiments. In the absence of dUMP, TS shows a major peak of unfolding at 45 degrees C with a shoulder at 47 degrees C. In the presence of increasing amounts of dUMP progressive changes in the size of each peak occur, each associated with a higher temperature of unfolding. At a ratio of dUMP/TS of 100, a major peak predominates with an unfolding temperature (Td) of 60 degrees C. FdUMP shows a similar profile, while dGMP does not alter the Td of the enzyme since dGMP alone does not bind to TS. Despite the fact that 1843U binds tightly to TS in the absence of nucleotide ligands [Dev, I. K., Dallas, W.S., Ferone, R., Hanlon, H., McKee, D.D., & Yates, B. B. (1994) J.Biol. Chem. 269, 1873-1882], it exhibits only a small effect on the Td profile of TS. However, when 1843U is present, in addition to the nucleotides (dUMP, FdUMP, or dGMP), a Td of 72 degrees C is achieved and the enthalpy of unfolding is increased by one-third. The stabilizing effect of substrate binding to TS by 1843U examined by thermodynamic parameters can be attributed to the considerable extra amount of free energy released on formation of the ternary complex of TS-1843U-nucleotide. The tightness of this complex is due to the stacking energy that results from Van der Waals contacts between the nucleotide purine or pyrimidine ring and the benzoquinazoline ring of 1843U [Weichsel, A., Montfort, W. R., Cieśla, J., & Maley, F. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 3493-3497], which induces a local conformational change in the protein. This conformational change is associated with a significant positive entropy change, which suggests that water is expelled from the active site region.