Biomedical subjects

C H Chen

Publications and source records attributed to C H Chen.

At least 91 records · Page 5Linked to original sources

PubMed2001

Two-trait-locus linkage analyses of asthma susceptibility.

A genome-wide search was conducted to identify chromosomal regions likely to harbor genes for asthma susceptibility. One hundred and twelve Caucasian families ascertained through a proband with a diagnosis of asthma by the Collaborative Study on the Genetics of Asthma (CSGA) were used for this search. Genotype data on 323 polymorphic markers were analyzed via parametric and nonparametric linkage analysis in an initial genome scan to identify potential asthma susceptibility region(s). The regions where hold or nonparametric linkage scores were greater than 2.0 were selected for further investigation using two-trait-locus linkage analysis models.

Adult↗

PubMed2001

Transmission/disequilibrium test analysis of total serum IgE levels in the Hutterite and Collaborative Study on the Genetics of Asthma data sets.

The Hutterite and Collaborative Study on the Genetics of Asthma data sets provided by Genetic Analysis Workshop 12 were analyzed using a regression-based transmission/disequilibrium test that assesses linkage between a marker locus and quantitative trait locus when allelic association is present, as proposed by George et al. [Am J Hum Genet 65:236-45, 1999]. Because the same marker set and analytical technique was used, the results from these data sets are amenable for comparison. Statistically significant results common to both data sets were found on chromosomes 1 and 3. A noteworthy result, significant at p < 10(-4), was detected on chromosome 18 in the Hutterites.

Adult↗

PubMed2001

A regulatory region rearranged BK virus is associated with tubulointerstitial nephritis in a rejected renal allograft.

A renal allograft transplant patient with high serum creatinine presented clinical symptoms of rejection. Sections of renal biopsy tissue showed mononuclear leukocyte infiltration in the tubulointerstitium and nuclear enlargement with inclusions in the tubular epithelium. The morphological characteristics resembled polyomavirus-induced interstitial nephritis. Electron microscopy of the nuclear inclusions showed paracrystalline arrays of naked viral particles with a diameter of 45 nm. Molecular studies revealed that a new variant of BK virus (BKV) with rearrangement at the regulatory region was involved in the nephritis. The BKV regulatory region contained a tandem repeat from the P-block to the Q-block causing duplication of several important transcriptional elements or transcriptional factor binding motifs. This is the first report to show a naturally occurring BKV variant with regulatory region rearrangement associated with tubulointerstitial nephritis.

Adult↗

PubMed2001

Probing reactive sites for ion-molecule reactions of anthraquinones with dimethyl ether using an external source ion trap tandem mass spectrometer and computational chemistry.

Gas-phase ion-molecule reactions of anthraquinone derivatives with dimethyl ether (DME) were investigated using an external source ion trap mass spectrometer. Semi-empirical calculations were executed to determine possible reactive sites for the product ions. Collision activated dissociation (CAD) was successfully performed for very low abundance of ion-molecule products. Even for product ions with a relative intensity below 1%, CAD experiments can be successfully performed. Significantly more structural information could be elucidated based on this special feature. Importantly, the CAD spectra of very minor ions could be measured by this ion trap instrument, which significantly enhances the future role of the ion trap as a powerful analytical instrument. CAD of all product ions on anthraquinone compounds typically eliminates neutral molecules such as CO or H(2)O. A hydration phenomenon in the CAD processes resulting from the precursor ions incorporating one molecule of H(2)O and then eliminating one molecule of CO was observed in this study.

Anthraquinones↗

PubMed2001

The influence of pH and cadmium sulfide on the photocatalytic degradation of 2-chlorophenol in titanium dioxide suspensions.

The influence of pH and cadmium sulfide on the photocatalytic degradation of 2-chlorophenol (2-CP) in titanium dioxide suspensions was investigated to evaluate the feasibility of mixed semiconductors on the photodegradation of chlorinated organics in aqueous solution. Apparent first-order rate constants (k(obs)) and initial rate constants were used to evaluate the degradation efficiency of 2-CP. Higher degradation efficiency of 2-CP was observed at higher pH values. The apparent pseudo-first-order rate constant was 0.036 min(-1) at pH 12.5 in TiO2/UV system, while a 2- to 9-fold decrease in k(obs) was observed over the pH range of 2.5-9.5. The addition of phosphate buffer solutions at different pH values have different effects on the degradation of 2-CP. H2PO4- has little effect on the photodegradation of 2-CP, while HPO4(2-) could inhibit the photodegradation efficiency of 2-CP. Chlorocatechol, hydroquinone, benzoquinone and phenol were identified as the predominant aromatic intermediates for the photocatalytic degradation of 2-CP. Moreover, less aromatic intermediates at higher pH were observed. Direct oxidation contributed significantly to the photodegradation of 2-CP. An addition of a semiconductor decreased the initial and apparent first-order rate constants of 2-CP. The cutoff of wavelength of 320nm could diminish the contribution of direct photolysis of 2-CP. The combination of cadmium sulfide and titanium dioxide can lead to an enhanced rate of disappearance of 2-CP compared to those in single semiconductor system. A 1.2 to 2.5-fold increase in rate constant in coupled semiconductor system relative to the single semiconductor system was obtained.

Biodegradation, Environmental↗

PubMed2001

Noninvasive single-beat determination of left ventricular end-systolic elastance in humans.

OBJECTIVES: The goal of this study was to develop and validate a method to estimate left ventricular end-systolic elastance (E(es)) in humans from noninvasive single-beat parameters. BACKGROUND: Left ventricular end-systolic elastance is a major determinant of cardiac systolic function and ventricular-arterial interaction. However, its use in heart failure assessment and management is limited by lack of a simple means to measure it noninvasively. This study presents a new noninvasive method and validates it against invasively measured E(es). METHODS: Left ventricular end-systolic elastance was calculated by a modified single-beat method employing systolic (P(s)) and diastolic (P(d)) arm-cuff pressures, echo-Doppler stroke volume (SV), echo-derived ejection fraction (EF) and an estimated normalized ventricular elastance at arterial end-diastole (E(Nd)): E(es(sb)) = [P(d) - (E(Nd(est)) x P(s) x 0.9)[/(E(Nd(est)) x SV). The E(Nd) was estimated from a group-averaged value adjusted for individual contractile/loading effects; E(es(sb)) estimates were compared with invasively measured values in 43 patients with varying cardiovascular disorders, with additional data recorded after inotropic stimulation (n = 18, dobutamine 5 to 10 microg/kg per min). Investigators performing noninvasive analysis were blinded to the invasive results. RESULTS: Combined baseline and dobutamine-stimulated E(es) ranged 0.4 to 8.4 mm Hg/ml and was well predicted by E(es(sb)) over the full range: E(es) = 0.86 x E(es(sb)) + 0.40 (r = 0.91, SEE = 0.64, p < 0.00001, n = 72). Absolute change in E(es(sb)) before and after dobutamine also correlated well with invasive measures: E(es(sb)): DeltaE(es) = 0.86 x DeltaE(es(sb)) + 0.67 (r = 0.88, p < 0.00001). Repeated measures of E(es(sb)) over two months in a separate group of patients (n = 7) yielded a coefficient of variation of 20.3 +/- 6%. CONCLUSIONS: The E(es) can be reliably estimated from simple noninvasive measurements. This approach should broaden the clinical applicability of this useful parameter for assessing systolic function, therapeutic response and ventricular-arterial interaction.

Adult↗

PubMed2001

Molecular transporters for peptides: delivery of a cardioprotective epsilonPKC agonist peptide into cells and intact ischemic heart using a transport system, R(7).

BACKGROUND: Recently, we reported a novel oligoguanidine transporter system, polyarginine (R(7)), which, when conjugated to spectroscopic probes (e.g., fluorescein) and drugs (e.g., cyclosporin A), results in highly water-soluble conjugates that rapidly enter cells and tissues. We report herein the preparation of the first R(7) peptide conjugates and a study of their cellular and organ uptake and functional activity. The octapeptide (psi)(epsilon)RACK was selected for this study as it is known to exhibit selective epsilon protein kinase C isozyme agonist activity and to reduce ischemia-induced damage in cardiomyocytes. However, (psi)(epsilon)RACK is not cell-permeable. RESULTS: Here we show that an R(7)-(psi)(epsilon)RACK conjugate readily enters cardiomyocytes, significantly outperforming (psi)(epsilon)RACK conjugates of the transporters derived from HIV Tat and from Antennapedia. Moreover, R(7)-(psi)(epsilon)RACK conjugate reduced ischemic damage when delivered into intact hearts either prior to or after the ischemic insult. CONCLUSIONS: Our data suggest that R(7) converts a peptide lead into a potential therapeutic agent for the ischemic heart.

Animals↗

PubMed2001

Detection and typing of vancomycin-resistance genes of enterococci from clinical and nosocomial surveillance specimens by multiplex PCR.

Ninety-three clinical isolates of vancomycin-resistant enterococci (VRE) collected from nine hospitals in Taiwan were examined for the presence of vanA, vanB, vanC1, or vanC2/vanC3 genes by a multiplex PCR. Forty-seven of these VRE isolates were vanA positive, 1 contained both vanC1 and vanA, 40 harboured vanB, 2 were vanC1, and 3 were identified to be vanC2/vanC3. Twenty-four vanA isolates were sensitive to teicoplanin and thus did not have a typical VanA phenotype. Five isolates with the VanC phenotype harboured vanB. None of the 40 clinically isolated vancomycin-susceptible E. faecium or E. faecalis and the vancomycin-resistant Leuconostoc and Pediococcus isolates were positive for any of the van genes. While performing nosocomial surveillance, VRE were isolated from 47 of 467 rectal swabs by culture. Compared with the conventional culture method, the sensitivity and specificity of the multiplex PCR for detecting and identifying vancomycin-resistance genes in enterococci directly from culture-positive broth were 97.9% and 100%, respectively. The results suggest that genotypic characterization of vancomycin-resistance is necessary for all clinical VRE isolates and that the multiplex PCR assay can be an alternative method for this purpose.

Bacterial Proteins↗

PubMed2001

Molecular epidemiologic analysis of Vibrio cholerae O1 isolated during the 1997-8 cholera epidemic in southern Thailand.

An unusually high incidence of Vibrio cholerae O1 infection was observed in southern Thailand between late December 1997 and March 1998. Fifty-seven V. cholerae O1 strains were isolated in five provinces during this epidemic and were examined. They were El Tor Ogawa strains exhibiting similar antibiograms. All strains were resistant to tetracycline, which had not been reported in Thailand since 1993. The ribotypes. hybridization patterns with ctx and zot gene probes, arbitrarily primed PCR profiles, and pulsed-field gel electrophoresis profiles of the representative strains were compared with the clinical strains isolated from patients in India and Bangladesh in 1997 and 1998 and from international travellers originating from various Asian countries during the 1992-8 period. All southern Thailand strains and the 1998 international traveller strain of Thai origin showed indistinguishable genetic fingerprinting patterns that were distinct from those of other test strains. The results suggest that a tetracycline-resistant clone newly emerged in late December 1997 caused the large epidemic in southern Thailand and that the variants with a slightly different antibiogram appeared during the course of the spreading epidemic.

Cholera↗

PubMed2001

Chemical constituents from Alseodaphne andersonii.

Five new compounds, including four C(17) gamma-lactones, dihydroisoobtusilactone (1), dihydroobtusilactone (2), 3-epilitsenolide D(2) (3), and 3-epilitsenolide D(1) (4), and one furanone alseodafuranone (5), were isolated from the root and stem of Alseodaphne andersonii. Their structures were elucidated mainly by spectral analysis (NMR and MS) and partially by chemical correlation.

Drugs, Chinese Herbal↗

PubMed2001

A critical role for NF-kappa B in GATA3 expression and TH2 differentiation in allergic airway inflammation.

The transcription factor GATA-3 is expressed in T helper 2 (TH2) but not TH1 cells and plays a critical role in TH2 differentiation and allergic airway inflammation in vivo. Mice that lack the p50 subunit of nuclear factor kappa B (NF-kappa B) are unable to mount airway eosinophilic inflammation. We show here that this is not due to defects in TH2 cell recruitment but due to the inability of the p50-/- mice to produce interleukin 4 (IL-4), IL-5 and IL-13: cytokines that play distinct roles in asthma pathogenesis. CD4+ T cells from p50-/- mice failed to induce Gata3 expression under TH2-differentiating conditions but showed unimpaired T-bet expression and interferon gamma (IFN-gamma) production under TH1-differentiating conditions. Inhibition of NF-kappa B activity prevented GATA-3 expression and TH2 cytokine production in developing, but not committed, TH2 cells. Our studies provide a molecular basis for the need for both T cell receptor and cytokine signaling for GATA-3 expression and, in turn, TH2 differentiation.

Animals↗

PubMed2001

Recombinant DNA vaccines protect against tumors that are resistant to recombinant vaccinia vaccines containing the same gene.

Antigen-specific cancer immunotherapy involves the delivery of tumor-associated antigen to the host for the generation of tumor-specific immune responses and antitumor effects. We hypothesized that different delivery systems may influence the pattern of antigen-specific immune response and the outcome of antitumor effect. We therefore evaluated recombinant vaccinia virus and naked DNA for the generation of antigen-specific immune responses and antitumor effects. We previously found that recombinant vaccinia and naked DNA vaccines containing the chimeric Sig/E7/LAMP-1 gene were capable of controlling the growth of HPV-16 E7-expressing tumor cells (TC-1). In this study, we performed a head-to-head comparison of optimized delivery of Sig/E7/LAMP-1 vaccinia and DNA vaccines using dose-escalating tumor challenge. At a dose of 1 x 10(6) TC-1 cells per mouse, Sig/E7/LAMP-1 DNA provided 100% protection against subcutaneous growth of tumors, while Vac-Sig/E7/LAMP-1 protected only 40% of the mice. Furthermore, Sig/E7/LAMP-1 DNA vaccines are capable of protecting against challenge with a more stringent subclone of TC-1 (TC-1 P2) established from TC-1 tumors that survived initial Sig/E7/LAMP-1 vaccinia vaccination. Immunological assays revealed that both vaccines induced comparable levels of CD8(+) T cell precursors and anti-E7 antibody titers. Interestingly, Sig/E7/LAMP-1 vaccinia induced both E7-specific IFN-gamma- and IL4-secreting CD4(+) T cell precursors while Sig/E7/LAMP-1 DNA induced only E7-specific IFN-gamma-secreting CD4(+) T cell precursors. We also found that IL-4 knockout C57BL/6 mice vaccinated with Sig/E7/LAMP-1 vaccinia exhibited a more potent antitumor effect than vaccinated wild-type C57BL/6 mice in our tumor protection experiments. These results suggest that IL-4 may play a detrimental role in the antitumor effect mediated by vaccinia vaccines. Our findings suggested that DNA vaccines may provide better tumor protection than vaccinia vaccines employing the same gene, which may have implications in the future design of antigen-specific cancer immunotherapy.

Animals↗

PubMed2001

Lack of evidence to support the association of the human prion gene with schizophrenia.

Recently a new variant of Creutzfeldt-Jakob disease, a human prion disease, with prominent psychiatric manifestations in the early stage was identified, suggesting that human prion disease may be associated with mental disorders. Furthermore, a novel missense mutation with asparagine-to-serine substitution at codon 171 of the human prion gene (N171S) was identified in a family with severe psychiatric symptoms. This finding provides further clue that the prion gene may be a susceptibility gene for certain psychiatric disorders. We systematically sequenced the protein-coding and untranslated exons of prion gene in 62 Han Chinese schizophrenic patients with positive family history from Taiwan. We identified two polymorphisms that alter amino acid sequences, a methionine/valine at codon 129 (M129V) and a glutamate/lysine at codon 219 (E219K), respectively. Further comparison of the genotype, allele and haplotype frequency distributions of these two polymorphisms between 234 schizophrenic patients and 100 non-psychotic controls, however, did not reveal significant differences between two groups. Besides, no other mutations in the prion gene were identified in these 62 patients. Hence, our results suggest that the prion gene may not play a major role in conferring susceptibility to schizophrenia.

Creutzfeldt-Jakob Syndrome↗

PubMed2001

Empirical validation of a teaching course on spiritual care in Taiwan.

UNLABELLED: AIM(S) OF STUDY: The aims of this study were threefold: (a) to develop the first spiritual care program for master of science in nursing degree students (MSNDS) in Taiwan, since most of these students are or will be nursing leaders in clinical practice, education, administration, or research; (b) to facilitate the MSNDS in applying the contents of this program to care of their clients; and (c) to understand the MSNDS' appraisals of the usefulness of the program in helping them provide spiritual care in clinical settings. BACKGROUND: The World Health Organization (WHO) (1998) proclaimed that health needs should include spiritual well-being in addition to physical, mental, and social domains. Nevertheless, many dominant medical educational systems have not yet encompassed spiritual care as part of their comprehensive or core curricula. DESIGN/METHODS: The methodological triangulation research design used in this project included various strategies of developing a novice course entitled 'Spirituality in Nursing Practice' which was given to the subjects over 18 weeks from September 1998 to February 1999. The course included classroom lectures, field trips, clinical implications, and presentation-appraisal. A convenience sample of 22 female MSNDS who were or had the potential to be nursing leaders from two schools of nursing in northern Taiwan was obtained. RESULTS: Four types of help were identified: (a) help in clarifying the theoretical concepts of spiritual care (100%); (b) help in providing a culturally bonded spiritual care plan (100%); (c) help in self-disclosure of the nurse's personal value systems and spiritual needs (91%); and (d) help in clarifying the symbolic meaning and the impact of religious rituals (86%). The explicit spiritual care plans and an empirical example of spiritual care were provided. CONCLUSIONS: This study presented the first spiritual care program for MSNDS in Taiwan. All subjects considered the course helpful in providing spiritual care for their clients in various clinical settings. The concept of spirituality is arousing great interest in the world, and this is evident in the spiritual care courses appearing in nursing curricula for nursing leaders in Taiwan.

Adult↗

PubMed2001

The Chinese version of the Davidson Trauma Scale: a practice test for validation.

The Chinese version of the Davidson Trauma Scale (DTS-C) was developed to respond to the need of Chinese-speaking individuals. The DTS is a validated self-rating scale used in the diagnosis of posttraumatic stress disorder (PTSD). The DTS-C is translated from DTS through a two-stage translation. Subjects were drawn from a sample of 210 survivors of the 21 September 1999, Chi-Chi Earthquake. The scale showed good internal consistency (Cronbach's alpha = 0.97) and test-retest reliability (r = 0.88). Concurrent validity was obtained against the clinical diagnostic interview, with a diagnostic accuracy of 0.85 at DTS-C score of 44. It showed that the sensitivity was 0.9, specificity 0.81, positive likelihood ratio 4.74, and negative likelihood ratio 0.12. The recommended stratum-specific likelihood ratios were 0.10 (95% CI: 0.05-0.20) for the score range 0-39, 4 (2.22-7.23) for the score range of 40-59, and 6.14 (3.42-11.02) for the scores above 60. In PTSD diagnosed subjects, the factor structures closely resembled the DSM-IV grouping of PTSD symptoms. The psychometric strength of DTS-C is reliable for its future use, particularly for screening for subjects with possible diagnosis of PTSD.

Adolescent↗

PubMed2001

Characteristics of postictal psychosis in a psychiatric center.

The clinical characteristics of 12 cases of postictal psychosis treated at Taipei City Psychiatric Center, Taipei, Taiwan, were retrospectively reviewed. Increased seizure frequency, especially with generalized tonic-clonic seizures, was the major risk factor predisposing to postictal psychosis. The psychotic symptoms were variable with delusions and/or hallucinations. These patients showed a much longer history of epilepsy (21.9 +/- 10.7 years) prior to the development of postictal psychosis than has been previously reported. The possible mechanisms in the pathophysiology of psychosis in epileptics were discussed.

Adolescent↗

PubMed2001

Women's perceptions of helpful and unhelpful nursing behaviors during labor: a study in Taiwan.

BACKGROUND: The job of the nurse in labor and delivery is not only to ensure a safe delivery but also to create a positive and satisfying childbirth experience. Few studies have been conducted of women's perceptions about the ideal image of the obstetric nurse during labor, and most previous studies involved only North American or European women. The purpose of this study was to assess Taiwanese women's perspectives about their encounters with obstetric nurses during labor. METHODS: Interviews of a convenience sample of 50 mothers experiencing normal childbirth in Taiwan were conducted. The interviews were tape recorded and transcribed, and the transcriptions were analyzed to develop coding categories and identify themes. RESULTS: Sixty percent of the participants reported having received helpful nursing behaviors only; 38 percent reported having received both helpful and unhelpful nursing behaviors. Helpful labor-coping measures that were valued by participants included performing roles of emotional support providers, comforters, information/advice providers, professional technical skills providers, and advocates. Forty percent of the participants reported that some nurses had hindered their labor-coping ability by failing to provide emotional support, comfort measures, adequate or correct information/advice, or to perform technical duties. CONCLUSIONS: The ideal nursing image encompasses the roles of emotional supporter, comforter, information/advice provider, professional/technical skill provider, and advocate. The findings may help obstetric team members better understand patients' needs, and enable them to provide better support during labor and to prevent unhelpful nursing behaviors.

Adult↗

PubMed2001

Lateral approach without ligament release in total knee arthroplasty: new concepts in the surgical technique.

A lateral approach without ligament release was performed in 475 primary total knee arthroplasties (TKAs) in 344 patients and 50 revision TKAs in 39 patients. Deformities of the genu varum or valgum were corrected by accurate bone cut; no ligament releases were required other than to achieve adequate exposure. A lateral approach allowed both self-centering of the extensor mechanism and knee closure in complete flexion. Better range of motion was achieved. More than 90 degree active flexion usually occurred 3 days postoperatively. Postoperative roentgenograms showed all knees had good varus and valgus stability, which was sustained with time, except 1 with late genu recurvatum due to inadequate polyethylene thickness and the other with a broken tibial base plate. Complications such as disruption of patellar blood supply and knee instability, more frequently observed in the medial approach with ligament release, did not occur. The results suggest that this new technique is safe and may give better outcomes.

Arthroplasty, Replacement, Knee↗