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Biomedical subjects

C H Tseng

Publications and source records attributed to C H Tseng.

At least 19 recordsLinked to original sources
PubMed2002

The prevalence of TT virus and GB virus C/hepatitis G virus infection in individuals with raised liver enzymes but without HBV or HCV infection in Taiwan.

The prevalence of TT virus (TTV) and GB virus-C/hepatitis G virus (GBV-C/HGV) infection and the association with raised liver function tests in 546 Taiwanese with negative HBsAg, anti-HCV and HCV RNA was elucidated. They were tested for serum alanine aminotransferase (ALT), GBV-C/HGV RNA, anti-envelope protein 2 antibody (anti-E2) and TTV DNA. Direct sequencing and phylogenetic analyses were performed on 58 isolates for TTV genotype determination. The prevalence of TTV DNA, GBV-C/HGV RNA, anti-E2 and over all GBV-C/HGV exposure was 24.9, 3.4, 8.2 and 11.1%, respectively. Using uni- and multi-variate analyses, male gender and TTV viremia were associated significantly with raised ALT values. Sixty-nine percent of TTV isolates were deduced to be TTV genotype 1 and they had significantly lower mean age than genotype non-1 isolates. In the population, raised ALT may be related to male gender and be attributable to TTV infection but not to GBV-C/HGV among individuals with no evidence of current HBV and HCV infection. TTV genotype 1 is the most prevalent genotype and associated with younger age.

Adult↗
PubMed2001

Enhanced effect of in-situ generated ammonium salts aerosols on the removal of NOx from simulated flue gas.

The combined removal of sulfur dioxide (SO2, up to 3,000 ppm) and nitrogen oxides (NO and NO2, up to 1,200 ppm) has been investigated in a bench-scale pulsed-corona enhanced wet electrostatic precipitator (wESP) with the optional injection of ammonia and/or ozone. The reaction of ammonia with SO2 produces submicron aerosols under certain conditions. Experiments have shown the feasibility of combined SO2 and NOx removal from simulated flue gases by the action of these in-situ generated aerosols. The mechanisms for NOx removal include oxidation of NO to NO2 and subsequent absorption of NO2 into the water wall of the wESP. The results have shown that injecting NH3 (NH3/NOx molar ratio 1) resulted in NOx removal of approximately 13% in a simulated combustion flue gas. Injecting 200 ppm ozone (no ammonia) increased NO conversion to 35% by oxidation, but total NOx removal increased to only 17%. Without the formation of ammonium salts aerosols (e.g., without SO2 in the gas), co-injection of ammonia and ozone increased NO conversion to 60% and NOx removal to 40%. However, high NOx removals were measured in simulated flue gas that contained NH3, SO2, and ozone. The total NOx removal efficiency was 79% when the ammonium salts aerosols were formed in the presence of 2400 ppm SO2, 312 ppm O3, and 2,900 ppm NH3. The energy efficiency of collection improved by approximately 250% for SO2 removal and more than 4700% for NOx removal under these conditions. It was determined that the ammonium salts aerosols produced from the reaction of ammonia and sulfur dioxide substantially enhanced total NOx removal.

Absorption↗
PubMed2001

Induction of disabled-2 gene during megakaryocyte differentiation of k562 cells.

Megakaryocyte differentiation is often accompanied by the changes of gene expression pattern. Here we reported that the expression of DAB2, a putative adaptor protein in cell signaling, was induced at the protein and mRNA levels upon 12-O-tetradecanoylphorbol-13-acetate-mediated megakaryocyte differentiation of human chronic myeloid leukemic K562 cells. On the other hand, the differentiation agents DMSO and retinoic acid had no effect on DAB2 expression. Analysis of promoter activity with the human DAB2 luciferase reporter constructs suggested that the regulation is partially at the transcriptional level. The responsive sequences located within an 80-bp DAB2 promoter region. To determine the involvement of MEK1-p42/p44 MAPK pathway in mediating DAB2 gene expression, we have performed the following experiments and found that (i) there was sustained activation of p42/p44 MAPK, but not p38 MAPK, upon K562 cells differentiation; (ii) application of MEK1 inhibitor U0126 reduced the expression of DAB2 protein, mRNA and promoter activity, as well as cell differentiation; (iii) constitutively active MEK1 increased DAB2 promoter activity; and (iv) dominant negative ERK2 abolished constitutively active MEK1-induced DAB2 promoter activity. Taken together, our results indicate that DAB2 gene is induced upon megakaryocyte differentiation by the MEK1-p42/p44 MAPK pathway and may define a new role of DAB2 in hematopoietic cell differentiation.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Incidence of transitional cell carcinoma and arsenic in drinking water: a follow-up study of 8,102 residents in an arseniasis-endemic area in northeastern Taiwan.

A significant association between ingested arsenic and bladder cancer has been reported in an arseniasis-endemic area in southwestern Taiwan, where many households share only a few wells in their villages. In another arseniasis-endemic area in northeastern Taiwan, each household has its own well for obtaining drinking water. In 1991-1994, the authors examined risk of transitional cell carcinoma (TCC) in relation to ingested arsenic in a cohort of 8,102 residents in northeastern Taiwan. Estimation of each study subject's individual exposure to inorganic arsenic was based on the arsenic concentration in his or her own well water, which was determined by hydride generation combined with atomic absorption spectrometry. Information on duration of consumption of the well water was obtained through standardized questionnaire interviews. The occurrence of urinary tract cancers was ascertained by follow-up interview and by data linkage with community hospital records, the national death certification profile, and the cancer registry profile. Cox proportional hazards regression analysis was used to estimate multivariate-adjusted relative risks and 95% confidence intervals. There was a significantly increased incidence of urinary cancers for the study cohort compared with the general population in Taiwan (standardized incidence ratio = 2.05; 95% confidence interval (CI): 1.22, 3.24). A significant dose-response relation between risk of cancers of the urinary organs, especially TCC, and indices of arsenic exposure was observed after adjustment for age, sex, and cigarette smoking. The multivariate-adjusted relative risks of developing TCC were 1.9, 8.2, and 15.3 for arsenic concentrations of 10.1-50.0, 50.1-100, and >100 microg/liter, respectively, compared with the referent level of < or =10.0 microg/liter.

Adult↗
PubMed2001

Real-time PCR for rapid genotyping of angiotensin-converting enzyme insertion/deletion polymorphism.

OBJECTIVE: To develop a real-time PCR technique for detection of the insertion/deletion (I/D) polymorphism of angiotensin-converting enzyme (ACE) gene. DESIGN AND METHODS: Three primers were designed for performing real-time PCR in the presence of SYBR Green I as flurochrome followed by melting curve analysis. Forty human genomic DNA that have been genotyped by two-rounds of conventional PCR were used for evaluation of this technique. RESULTS: Melting curve analysis indicated the melting peak at 73.9 degrees C and 76.2 degrees C corresponding to the presence of I and D alleles, respectively. Comparable genotyping results were obtained by both conventional and real-time PCR. Besides, the mistyping of ID allele individuals by the first run of conventional PCR were accurately genotyped by single-tube real time PCR. CONCLUSIONS: The real-time PCR method presented in this study provides a rapid and sensitive way for genotyping of ACE gene that may be suitable for large-scale clinical and epidemiologic study.

Alleles↗
PubMed2000

The incidence of type 2 diabetes mellitus in Taiwan.

Currently, diabetes mellitus is the fifth leading cause of death in Taiwan. The trends of diabetes mortality is increasing steadily. Epidemiologic studies also showed increasing prevalence of diabetes mellitus over the past few decades. The incidence of diabetes mellitus in Taiwan has only been studied in recent 10 years. The areas that have been included as study areas for diabetes incidence are Kin-Chen (Kinmen), Chu-Dung, Pu-Tzu, Pu-Li and Pu-Tai. The reported incidence rates ranged from 1.0 to 4.0% per year for people with varying degrees of baseline plasma glucose levels not reaching the diagnosis of diabetes mellitus according to the criteria of the World Health Organization. Age, baseline glucose level, and obesity are important predictors for the development of diabetes mellitus. In the Pu-Tai study, which was aimed at following a group of people who had been living in the hyperendemic villages of blackfoot disease and had been exposed to arsenic from drinking artesian well water, the incidence of diabetes mellitus was calculated to be 27.4 per 1000 person years. The incidence of diabetes mellitus in these arseniasis-hyperendemic villages correlated with age, body mass index and cumulative arsenic exposure.

Adult↗
PubMed2000

Magnetic resonance imaging of convection in laser-polarized xenon.

We demonstrate nuclear magnetic resonance (NMR) imaging of the flow and diffusion of laser-polarized xenon (129Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid imaging than one can achieve with thermally polarized gas-liquid systems, permitting shorter time-scale events such as rapid gas flow and gas-liquid dynamics to be observed. Two-dimensional velocity-encoded imaging shows convective gas flow above the evaporating liquid xenon, and also permits the measurement of enhanced gas diffusion near regions of large velocity variation.

Convection↗
PubMed2000

Long-term arsenic exposure and incidence of non-insulin-dependent diabetes mellitus: a cohort study in arseniasis-hyperendemic villages in Taiwan.

Diabetes prevalence in arseniasis-hyperendemic villages in Taiwan has been reported to be significantly higher than in the general population. The aim of this cohort study was to further evaluate the association between ingested inorganic arsenic and the incidence of non-insulin-dependent diabetes mellitus in these villages. A total of 446 nondiabetic residents in these villages were followed biannually by oral glucose tolerance test. Diabetes is defined as a fasting plasma glucose level > or = 7.8 mmol/L and/or a 2-hr post-load glucose level > or = 11.1 mmol/L. During the follow-up period of 1499.5 person-years, 41 cases developed diabetes, showing an overall incidence of 27.4/1,000 person-years. The incidence of diabetes correlated with age, body mass index, and cumulative arsenic exposure. The multivariate-adjusted relative risks were 1.6, 2.3, and 2.1 for age > or = 55 versus < 55 years, a body mass index ¿Greater/Equal to] 25 versus < 25 kg/m(2), and a cumulative arsenic exposure > or = 17 versus < 17 mg/L-years, respectively. The incidence density ratios (95% confidence intervals) between the hyperendemic villages and the two nonendemic control townships were 3.6 (3.5-3.6), 2.3 (1.1-4.9), 4.3 (2.4-7.7), and 5.5 (2.2-13.5), respectively, for the age groups of 35-44, 45-54, 55-64, and 65-74 years. The findings are consistent with our previous cross-sectional observation that ingested inorganic arsenic is diabetogenic in human beings.

Adult↗
PubMed2000

Unexpected cytokines in serum of malignant melanoma patients during sequential biochemotherapy.

Biochemotherapy, which combines traditional chemotherapy with immune modulating biologicals, produces an unexpectedly high response rate (>50%) in advanced melanoma patients. We hypothesize that immunological mechanism(s) are responsible for the increased response rate, and particularly that macrophage activation is involved in tumor reduction. Patients were randomized to receive chemotherapy, composed of cisplatin, vinblastine, and dacarbazine (CVD), or biochemotherapy, which is CVD followed by interleukin (IL)-2 and IFN-alpha2b (CVD-BIO). Laboratory analysis was performed on sera from 41 patients from each arm. Measurements of macrophage activation (neopterin), nitric oxide production (nitrite), and tumor necrosis factor-alpha (TNF-alpha), IL-1alpha, IL-1beta, IFN-gamma, IL-6, IL-10, and soluble IL-2 receptor (sIL-2R) were performed. Six of the nine biological responses (nitrite, neopterin, IFN-gamma, IL-6, soluble IL-2R, and IL-10) significantly (P < 0.0002) increased in the CVD-BIO patients but not in the CVD patients. The increased IL-6 (P = 0.04) and IL-10 (P = 0.05) correlated with patient response, but only when the minor responders were included in the analysis. Evidence of macrophage activation was found in CVD-BIO patients and not in those receiving CVD alone. In addition, an unusual cytokine elaboration composed of IL-6, IFN-gamma, IL-10, nitrite, neopterin, and sIL-2R, but not the expected TNF-alpha and IL-1, was detected. A trend of higher increase in IL-6 and IL-10 in patients having clinical response was found, suggesting an incomplete Th2 pattern of cytokine elaboration. These data show that macrophage activation does not appear to be critical in the response to CVD-BIO, but that IL-10 and IL-6 induced by the BIO component of the CVD-BIO were associated with tumor regression, and that their biology should be pursued further in the analysis of mechanism(s) of response.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1999

Accrual strategies for phase I trials with delayed patient outcome.

Phase I dose-finding trials typically are conducted using adaptive rules that select dose levels for successive patient cohorts based on the outcomes of patients treated previously in the trial. When patient outcome cannot be observed immediately after treatment, the problem arises of how to deal with new patients while waiting to observe the current patient cohort's outcomes. We consider two alternative approaches to this problem in the context of a phase I trial conducted using the continual reassessment method. With the first approach, a patient requiring treatment before the next cohort opens is treated off protocol with standard therapy, and otherwise waits until the next cohort opens. The second approach treats each patient immediately upon arrival at the dose recommended based on currently available data. We compare these two approaches by simulation under varying dose--toxicity curves, accrual rates, cohort sizes and early stopping rules. We evaluate patient waiting time, trial duration, number of patients treated off protocol and the probabilities of toxicity and of selecting the correct dose. We also study three strategies for assigning patients to trials when two or more phase I trials may be ongoing simultaneously. Based on our results, we provide practical guidelines for deciding among these approaches and strategies in a given clinical setting.

Antineoplastic Agents↗
PubMed1999

Single-shot diffusion measurement in laser-polarized Gas.

A single-shot pulsed gradient stimulated echo sequence is introduced to address the challenges of diffusion measurements of laser polarized 3He and 129Xe gas. Laser polarization enhances the NMR sensitivity of these noble gases by >10(3), but creates an unstable, nonthermal polarization that is not readily renewable. A new method is presented which permits parallel acquisition of the several measurements required to determine a diffusive attenuation curve. The NMR characterization of a sample's diffusion behavior can be accomplished in a single measurement, using only a single polarization step. As a demonstration, the diffusion coefficient of a sample of laser-polarized 129Xe gas is measured via this method.

Algorithms↗
PubMed1999

Construction and implementation of NMR quantum logic gates for two spin systems.

The implementation of small prototype quantum computers has been studied through ensemble quantum computing via NMR measurements. In such laboratory studies it is convenient to have access to a wide array of logic gates. Here a systematic approach to reduce the logic gate to an NMR pulse sequence is introduced. This approach views the truth table for a quantum logic operation as a permutation matrix that corresponds to a propagator for an NMR transition. This propagator is then used as the starting point for the derivation of a pulse sequence. Pulse sequences for all the permutations of a four level system are reported along with implementations of representative examples on a two spin-1/2 system, 13C-labeled chloroform.

Magnetic Resonance Spectroscopy↗
PubMed1999

A system for low field imaging of laser-polarized noble gas.

We describe a device for performing MRI with laser-polarized noble gas at low magnetic fields (<50 G). The system is robust, portable, inexpensive, and provides gas-phase imaging resolution comparable to that of high field clinical instruments. At 20.6 G, we have imaged laser-polarized (3)He (Larmor frequency of 67 kHz) in both sealed glass cells and excised rat lungs, using approximately 0.1 G/cm gradients to achieve approximately 1 mm(2) resolution. In addition, we measured (3)He T(2)(*) times greater than 100 ms in excised rat lungs, which is roughly 20 times longer than typical values observed at high ( approximately 2 T) fields. We include a discussion of the practical considerations for working at low magnetic fields and conclude with evidence of radiation damping in this system.

Animals↗
PubMed1999

Multi-institutional melanoma lymphatic mapping experience: the prognostic value of sentinel lymph node status in 612 stage I or II melanoma patients.

PURPOSE: To compare the effect of pathologic sentinel lymph node (SLN) status with that of other known prognostic factors on recurrence and survival in patients with stage I or II cutaneous melanoma. PATIENTS AND METHODS: We reviewed the records of 612 patients with primary cutaneous melanoma who underwent lymphatic mapping and SLN biopsy between January 1991 and May 1995 to determine the effects of tumor thickness, ulceration, Clark level, location, sex, and SLN pathologic status on disease-free and disease-specific survival. RESULTS: In the 580 patients in whom lymphatic mapping and SLN biopsy were successful, the SLN was positive by conventional histology in 85 patients (15%) but negative in 495 patients (85%). SLN status was the most significant prognostic factor with respect to disease-free and disease-specific survival by univariate and multiple covariate analyses. Although tumor thickness and ulceration influenced survival in SLN-negative patients, they provided no additional prognostic information in SLN-positive patients. CONCLUSION: Lymphatic mapping and SLN biopsy is highly accurate in staging nodal basins at risk for regional metastases in primary melanoma patients and identifies those who may benefit from earlier lymphadenectomy. Furthermore, pathologic status of the SLN in these patients with clinically negative nodes is the most important prognostic factor for recurrence. The information from SLN biopsy is particularly helpful in establishing stratification criteria for future adjuvant trials.

Biopsy↗
PubMed1998

Low-field MRI of laser polarized noble gas.

NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

Diffusion↗
PubMed1998

Pulsed-field-gradient measurements of time-dependent gas diffusion.

Pulsed-field-gradient NMR techniques are demonstrated for measurements of time-dependent gas diffusion. The standard PGSE technique and variants, applied to a free gas mixture of thermally polarized xenon and O2, are found to provide a reproducible measure of the xenon diffusion coefficient (5.71 x 10(-6) m2 s-1 for 1 atm of pure xenon), in excellent agreement with previous, non-NMR measurements. The utility of pulsed-field-gradient NMR techniques is demonstrated by the first measurement of time-dependent (i.e., restricted) gas diffusion inside a porous medium (a random pack of glass beads), with results that agree well with theory. Two modified NMR pulse sequences derived from the PGSE technique (named the Pulsed Gradient Echo, or PGE, and the Pulsed Gradient Multiple Spin Echo, or PGMSE) are also applied to measurements of time dependent diffusion of laser polarized xenon gas, with results in good agreement with previous measurements on thermally polarized gas. The PGMSE technique is found to be superior to the PGE method, and to standard PGSE techniques and variants, for efficiently measuring laser polarized noble gas diffusion over a wide range of diffusion times.

Magnetic Resonance Spectroscopy↗
PubMed1998

Low serum carotene level and increased risk of ischemic heart disease related to long-term arsenic exposure.

To elucidate the association between arsenic-related ischemic heart disease (ISHD) and serum antioxidant micronutrient level, residents aged 30 or older living in arseniasis-hyperendemic villages in Taiwan were recruited in a community-based health survey. A structured questionnaire was used to obtain a history of long-term exposure to arsenic through consuming artesian well water and fasting serum samples were also collected at the recruitment. A total of 74 patients affected with ISHD, who were diagnosed through both electrocardiography and Rose questionnaire interview, and 193 age-sex-matched healthy controls were selected for the examination of serum levels of micronutrients by high performance liquid chromatography (HPLC). There was a significant biological gradient between the risk of ISHD and the duration of consuming high-arsenic artesian well water. A significant reverse dose-response relationship with arsenic-related ISHD was observed for serum level of alpha- and beta-carotene, but not for serum levels of retinol, lycopene and alpha-tocopherol. Multivariate analysis showed a synergistic interaction on arsenic-related ISHD between duration of consuming artesian well water and low serum carotene level. An increased risk of arsenic-related ISHD was also associated with hypertension and elevated body mass index, but not with serum lipid profile, cigarette smoking and alcohol drinking. The findings seem to suggest that arsenic-related ISHD has a pathogenic mechanism which is at least partially different from that of ISHD unrelated to long-term exposure to arsenic.

Adult↗