Search PubMed⌕ Search

Biomedical subjects

C J Chang

Publications and source records attributed to C J Chang.

At least 19 recordsLinked to original sources
PubMed2001

The C677T mutation of the methylenetetrahydrofolate reductase gene is not associated with the risk of coronary artery disease or venous thrombosis among Chinese in Taiwan.

OBJECTIVES: We sought to investigate the association between the methylenetetrahydrofolate reductase (MTHFR) gene C677T mutation and the risk of coronary artery disease (CAD), myocardial infarction (MI) and venous thrombosis (VT) in a Chinese population in Taiwan. METHODS: The subjects included 218 CAD patients, 107 VT patients, and their age- and sex-matched controls. DNA was extracted from the blood and genotypes were determined by polymerase chain reaction, restriction mapping with HinfI and gel electrophoresis. RESULTS: The distribution of MTHFR genotypes was similar in the CAD cases and controls; the genotype TT was present in 6.0% of CAD patients, as compared to 6.9% of CAD control subjects (p = 0.165; odds ratio = 0. 86; 95% confidence interval = 0.40-1.85). The frequency of the T allele was also similar in CAD cases and controls (25.5% vs. 24.8%; p = 0.788). There was no significant association between TT homozygosity and the risk of MI. The genotype distributions and the frequency of the T allele were also similar in VT cases and controls. CONCLUSIONS: Our data suggest that there is no association between the C677T mutation of the human MTHFR gene and the risk of CAD or VT among Chinese in Taiwan.

Alleles↗
PubMed2000

Use of 16S rDNA sequences as signature characters to identify Xylella fastidiosa.

The nucleotide sequences of 16S rDNAs (coding for the small subunit ribosomal RNAs) were used to identify Xylella fastidiosa, a nutritionally fastidious plant pathogenic bacterium. The near-complete 16S rDNAs from nine strains of Xyl. fastidiosa, including seven pathotypes and one strain of Xanthomonas campestris pv. campestris, were amplified through PCR with two conserved primers (forward primer 5'-AGA GTT TGA TCC TGG CTC AG-3' and reverse primer 5'-AAG GAG GTG ATC CAG CC-3') and sequenced. The 16S sequences were compared with all eukaryote and prokaryote DNA entries in GenBank database. A Xyl. fastidiosa 16S rDNA sequence, M26601, was determined to be the most similar to all the near-complete (1537 bp) and partial 5' end sequences from Xyl. fastidiosa, but not those from the Xanthomonas strain. A 20-bp oligonucleotide (5'-TTG GTA GTA ATA CCA TGG GT-3') was found to be highly characteristic of Xyl. fastidiosa. Since the 16S rDNA of Xyl. fastidiosa strains are highly homologous and characteristically different from other bacteria, including the most closely related Xanthomonas, 16S rDNA sequences can be used as signature characters to identify this bacterium.

Base Sequence↗
PubMed2000

Cytotoxicity of extractives from Taiwania cryptomerioides heartwood.

The cytotoxicity of the dominant lignans and sesquiterpenoids from Taiwania (Taiwania cryptomerioides Hayata) was investigated. Three human tumor cells including A-549 lung carcinoma. MCF-7 breast adenocarcinoma and HT-29 colon adenocarcinoma were selected to illustrate the structure-cytotoxicity relationships of Taiwania's dominant compounds. Taiwanin A, taiwanin E and dimethylmatairesinol exhibited significant cytotoxicity against three human tumor cells. Among them, taiwanin A possesses the strongest cytotoxic activity. In addition, the morphology-based evaluation, flow cytometric analysis, and DNA fragmentation assays demonstrated that the tumor cell death induced by taiwanin A was due to apoptosis.

Antineoplastic Agents, Phytogenic↗
PubMed2000

16S rDNA sequence analysis of Xylella fastidiosa strains.

The 16S rDNA encoding the small subunit ribosomal RNA were amplified by PCR, cloned, and sequenced from 16 strains of Xylella fastidiosa originating from nine different hosts. In pair-wise comparisons, X. fastidiosa strains showed a maximum variation of 1.0% or 14 nucleotide positions. When all 16 sequences were considered as a set, 54 variable positions were found. Analysis of the sequence data indicated that the X. fastdiosa strains formed three rDNA groups. Group one includes Pierce's disease and mulberry leaf scorch strains; Group two, periwinkle wilt, plum leaf scald, phony peach, oak leaf scorch, and elm leaf scorch strains; and Group three, citrus variegated chlorosis and coffee leaf scorch strains. All X. fastidiosa strains exhibited significantly higher levels of sequence heterogeneity (63 to 83 nucleotide positions) when compared to species from Xanthomonas and Stenotrophomonas. Our data demonstrate that 16S rDNA sequence data could provide valuable information for future classification of X. fastidiosa at the sub-species level.

DNA, Ribosomal↗
PubMed2000

Effects of atypical neuroleptics on sustained attention deficits in schizophrenia: a trial of risperidone versus haloperidol.

To help determine whether sustained attention deficits as measured with the Continuous Performance Test (CPT) are stable vulnerability indicators of schizophrenia, we compared the CPT performance of schizophrenic patients before and after treatment with risperidone or haloperidol. In this double blind trial, 56 schizophrenic patients were randomly assigned to a 12-week regimen of either risperidone or haloperidol, after a 1-week washout period. The patients undertook two sessions of the CPT (undegraded and 25% degraded) twice, one at the end of the washout period and the other at the end of the study. Thirty-eight patients completed the study, 19 in each group. Both groups experienced significant improvements in clinical symptoms, and the risperidone group showed no change in the severity of extrapyramidal symptoms. Despite those improvements, the CPT performance indexes did not change significantly from the beginning to the end of the study. These findings indicate that sustained attention deficits might be stable vulnerability indicators of schizophrenia.

Adult↗
PubMed2000

Bioactive compounds from Psorothamnus junceus.

During a search for bioactive compounds from Psorothamnus junceus, four heterocyclic compounds, psorothamnone A (1), psorothamnone B (2), dalrubone (3), and emorydone (4) were isolated from the ethanol extract of the stem bark. Psorothamnones A (1) and B (2) demonstrated inhibitory activity against protein kinase C (PKC), a key enzyme involved in the signal transduction of cell proliferation and differentiation. Dalrubone (3) and emorydone (4) showed cytotoxicity against several human tumor cell lines.

Drug Screening Assays, Antitumor↗
PubMed2000

Serum alanine aminotransferase levels in relation to hepatitis B and C virus infections among drug abusers in an area hyperendemic for hepatitis B.

Hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are the major agents responsible for hepatitis in Taiwan. The purpose of this study was to assess the serum alanine aminotransferase (ALT) activity in relation to HBV and HCV infection among drug abusers. This survey included 769 male drug abusers aged 14-59 years, from the Kaohsiung Narcotic Abstention Institute and Kaohsiung Prision. The prevalence of HBsAg seropositivity was 21.5%, and anti-HCV seropositivity was 27.2%, respectively. Drug abusers with HBsAg or anti-HCV had higher serum AST and ALT levels than those without HBsAg and anti-HCV. The prevalence of raised ALT and AST (> or =45 IU/liter) in the HCV-positive group was more significant than in the negative group, while that of the HBsAg-positive group did not reach statistical significance. Among the HCV-positive group, ALT levels are more closely associated with HCV infection than AST levels. Our results indicated that HCV infection plays an important role in the etiology of raised ALT activity among drug abusers, while HBV infection plays a minor role. ALT screening still remains a simple and valuable method in the early recognition of HCV infection.

Adolescent↗
PubMed2000

Effect of glycoprotein IIb/IIIa inhibitors on the individual components of composite endpoints used in clinical trials of unstable angina and non-Q-wave myocardial infarction.

Inhibitors of the platelet glycoprotein (GP) IIb/IIIa receptor complex have recently been approved for the treatment of patients with unstable angina and non-Q-wave myocardial infarction (MI). We performed a meta-analysis to ascertain the effect of these agents on the individual endpoints of death, myocardial infarction, refractory ischemia, and major bleeding after 30 days of follow-up. Five randomized, placebo-controlled trials involving 17,255 patients were identified. The odds ratios for each of the endpoints in each trial were calculated and combined using a fixed-effects model. There was no significant reduction in death (OR, 0.87; 95% CI, 0.73-1.03; P = 0.1), myocardial infarction (OR, 0.91; 95% CI, 0.82-1.004; P = 0.06), or refractory ischemia (OR, 0.92; 95% CI, 0.78-1.1; P = 0.36) in patients treated with GP IIb/IIIa inhibitors. There was a significant increase in major bleeding following treatment with GP IIb/IIIa inhibitors (OR, 1.2; 95% CI, 1.06-1.4; P = 0.005). When used to treat unstable angina and non-Q-wave MI, this new class of agents appears to be associated with minimal clinical benefit and an increase in major bleeding complications.

Angina, Unstable↗
PubMed2000

Relationships of age, menopause and central obesity on cardiovascular disease risk factors in Chinese women.

OBJECTIVE: To evaluate the inter-relationships of age- and menopause- related changes of general obesity and body fat distribution and their independent effects on cardiovascular risk factors. DESIGN: Cross-sectional study. SUBJECTS: One-hundred and thirty-six premenopausal and 193 postmenopausal Chinese women with body mass index (BMI) < 30 kg/m2. MEASUREMENTS: Anthropometric surrogates of general obesity (BMI, total body fat percentage) and central obesity (waist-to-hip ratio, centrality index) were measured. Blood pressure, 75 g oral glucose tolerance test, glycosylated hemoglobin A1c and lipid profiles were also measured. RESULTS: Significant correlation coefficients between age, general obesity, central obesity and cardiovascular disease risk factors were noted. Through the menopausal transition, the BMI and total body fat percentage were increased significantly. After adjustments for age and BMI, the postmenopausal women showed higher android fat percentage, centrality index, glycosylated hemoglobin A1c, serum concentrations of total cholesterol, low-density lipoprotein (LDL) cholesterol and atherogenic indices than the premenopausal women. In multiple stepwise regression models, age exerted independent effects on oral glucose tolerance test 2 h plasma glucose level, systolic and diastolic blood pressure, total cholesterol level, and LDL cholesterol. Menopause was an independent variable in relation to the changes of glycosylated hemoglobin A1c, total and LDL cholesterol levels, triglyceride levels and atherogenic indices. The centrality index was the major independent variable of all the cardiovascular disease risk factors, except total and LDL cholesterol level. However, the variation of total body fat percentage had no independent effect on any cardiovascular disease risk factors. CONCLUSION: Through the aging and menopausal effects, women will increase total body fat content, favoring the central body fat distribution. Age, menopause and central obesity were all independent and significant factors to the cardiovascular disease risk factors in Chinese women.

Adipose Tissue↗
PubMed2000

The application of water drinking test on the evaluation of trabeculectomy patency.

The water drinking test (WDT) was once frequently used as a diagnostic tool for glaucoma, but not so often nowadays. In this study, we investigated the potential use of the WDT on the evaluation of trabeculectomy patency. Twenty age-matched volunteers and thirty-six glaucoma patients who were to receive trabeculectomy procedure were enrolled in this study. The WDT was given to the volunteers once and to all glaucoma patients before undergoing trabeculectomy and at certain intervals after the procedure. The WDT was performed in a standard manner. We defined four parameters after performing the WDT: Initial Pressure [IP, intraocular pressure (IOP) level before the WDT]; Slope of Ascending Trend (SOAT, the slope between baseline IOP and the highest IOP level); Peak Pressure (PP, the highest IOP level during the WDT); and End Pressure (EP, the IOP level after the WDT). It was found that the results of the WDT and trabeculectomy patency were strongly correlated. The four parameters in success and failure cases were significantly different at the last follow up: IP: (15.2 +/- 3.6 vs. 25.3 +/- 6.4, p<0.01); SOAT: (0.9 +/- 0.3 vs. 1.8 +/- 1.2, p<0.01); PP: (19.2 +/- 6.4 vs. 39.5 +/- 12.2, p<0.01); EP: (15.5 +/- 4.8 vs. 29.4 +/- 8.2, p<0.01). Thus, it was observed in this study that WDT was not only easy and safe to perform, but also valuable in evaluating the patency of trabeculectomy.

Adult↗
PubMed2000

Aqueous humor nitric oxide levels differ in patients with different types of glaucoma.

Nitric oxide (NO) has effects on the regulation of aqueous humor dynamics, but the exact mechanism is not yet established. To investigate the possible roles of NO in glaucoma, we determined NO levels in aqueous humor and plasma in glaucoma patients and a control group, cataract patients. The study is an open trial with purposed sampling. One hundred fifty-two patients, including 87 glaucoma patients and 65 cataract patients from two medical centers, were recruited. NO levels in the samples were measured by a chemiluminescence assay. We found that, although the mean aqueous humor NO level (mean +/- SEM) was higher in the glaucoma patients than in the cataract patients (39.7 +/- 1.5 microM vs. 35.5 +/- 1.3 microM, p < 0.05), NO levels varied significantly in different types of glaucoma. The juvenile glaucoma patients had the lowest mean NO level (8.4 +/- 0.9 microM), while the acute angle-closure glaucoma and neovascular glaucoma patients had the highest mean NO levels (64.8 +/- 7.6 microM, 67.3 +/- 8.2 microM). In comparison, the mean plasma NO level in the glaucoma patients was not statistically different from that in the cataract patients (14.1 +/- 1.2 microM vs. 13.9 +/- 1.1 microM, p = 0.91). Our data may provide information for applying NO-mimicking nitrovasodilators in the treatment of glaucoma.

Aged↗
PubMed2000

Wound modulation after trabeculectomy by different formulations of antimetabolites in rabbits.

A prospective, randomized study was performed to examine the effects of subconjunctival retention of 5-fluorouracil (5-FU) microparticles or 5-FU microparticles combined with mitomycin-C (MMC) on the success of trabeculectomy procedure in 32 New Zealand white rabbits. Drug-loaded microparticles were prepared using a biodegradable polymer, 50:50 ploy (D,L-lactide-co-glycolide) (50:50, PLG, MW 9000), by an oil-in-oil emulsification/solvent extraction technique. Each rabbit underwent trabeculectomy on both eyes, then one of the 5-FU and/or MMC preparations was placed at the site of the filtering surgery intraoperatively in the right eye, while the left eye was used as a control. The rabbits were randomly allocated to one of four treatment groups: group 1 rabbits received 5% 5-FU microparticles 10 mg; group 2 rabbits received 10% 5-FU microparticles 10 mg; group 3 rabbits received 10% 5-FU microparticles 5 mg and MMC 0.01 mg (5-FU/MMC); and group 4 rabbits received MMC 0.02 mg. Postoperatively, intraocularpressure (IOP), bleb survival, complications and IOP dynamics were compared during a follow-up period of 42 days. The results showed that IOPs were significantly lower in the eyes that received groups 3 and 4 treatments, while the eyes that received low concentrations of 5-FU microparticles resulted in no difference in IOPs as compared with those of controls. At 42 days, blebs were present in 100% of the eyes treated with 5-FU/MMC and MMC, but 0% of the eyes treated with 5-FU microparticles. The blebs in the eyes treated with MMC 0.02 mg were thinner, and significant complications (endophthalmitis, transient corneal opacification and neovascularization) occurred. In addition, the IOP dynamics study revealed that the eyes treated with 5-FU/MMC and MMC resulted in less IOP spikings after intravenous infusion of 0.9% NaCl solution. Our study suggested that the use of 5-FU microparticles in promoting the success of trabeculectomy in rabbits is dose-dependent, and its effect is less potent than a single intraoperative application of MMC.

Animals↗
PubMed2000

Hypertension in elderly persons: its prevalence and associated cardiovascular risk factors in Tainan City, southern Taiwan.

BACKGROUND: Hypertension was the eighth leading cause of death in Taiwan in 1996, and the prevalence of hypertension has increased recently. The purpose of the study was to assess the prevalence of hypertension and its associated cardiovascular risk factors in elderly persons in Tainan City, southern Taiwan. METHODS: The study was a cross-sectional, population-based study. We used the stratified cluster sampling method to enroll subjects aged 65 years and above, 1435 persons in total, into our study. Questionnaire interview, body weight, body height, and blood pressure measurement were completed for 876 participants (response rate of 70.2%) at each subject's home by home visit. RESULTS: Hypertension was defined according to the criteria of the Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. The crude prevalence of hypertension was 60.4% (men 59.1%, women 61.9%); previously diagnosed hypertension was 31.1% (men 29.4%, women 33.1%); and newly diagnosed hypertension was 29.3% (men 29.7%, women 28.8%). The hypertensive group had a higher body mass index (BMI) than the normotensive group. There were no lifestyle differences such as smoking, drinking, eating a vegetarian diet, reading health information, and undergoing a health examination in the past year between the hypertensive and normotensive groups. However, the hypertensive group had a higher prevalence of regular exercise than did the normal blood pressure group on univariate analysis. Only BMI and family history of hypertension had a significantly positive association with hypertension on multiple logistic regression analysis. CONCLUSIONS: The crude prevalence of hypertension was 60.4% in elderly persons in Tainan City. Subjects who had family history of hypertension and higher BMI had a higher risk of hypertension, so they should be screened for high blood pressure regularly.

Age Factors↗
PubMed2000

Ventricular tachycardia in a patient with primary hyperparathyroidism.

We present a case of primary hyperparathyroidism with hypercalcemia in a patient who had spontaneous attacks of ventricular tachycardia. Right ventricular burst pacing reproducibly induced ventricular tachycardia in the electrophysiological laboratory after intravenous administration of calcium-gluconate, and verapamil could terminate the tachycardia. After resection of the parathyroid adenoma, the calcium level was restored to normal, and ventricular tachycardia did not occur again during the follow-up period.

Adenoma↗
PubMed2000

Nutritional requirements of Xylella fastidiosa, which causes Pierce's disease in grapes.

A defined medium (XF-26) containing 3 inorganic salts, 2 tricarboxylic acids, 17 amino acids, potato starch, phenol red, and agar was used as the starting point for the study. Deletions of one or more ingredients were performed to prepare various media. A medium was considered able to support growth of Xylella fastidiosa strains responsible for Pierce's disease in grapes, only after 10 serial passages had been completed. Of 3 inorganic salts, K2HPO4 and MgSO4 x 7H2O were essential, and (NH4)2HPO4 was nonessential for growth. Of the Krebs cycle intermediates, all (citrate, alpha-ketoglutarate, succinate, fumarate, malate, and oxaloacetate) but isocitrate supported growth of cultivated strains, whereas only citrate alone or citrate plus succinate supported the primary isolation of PD bacterium. Of 17 amino acids, 6 uncharged polar R groups (asparagine, cysteine, glutamine, glycine, serine, and threonine) supported growth, whereas 8 nonpolar R groups (alanine, isoleucine, leucine, methionine, phenylalanine, proline, tryptophan, and valine) or 3 positively charged polar groups (arginine, histidine, and lysine) did not. Starch proved to be nonessential.

Culture Media↗
PubMed2000

Hormone-independent activation of EGP during hypoglycemia is absent in type 1 diabetes mellitus.

It has been suggested that insulin-induced suppression of endogenous glucose production (EGP) may be counteracted independently of increased epinephrine (Epi) or glucagon during moderate hypoglycemia. We examined EGP in nondiabetic (n = 12) and type 1 diabetic (DM1, n = 8) subjects while lowering plasma glucose (PG) from clamped euglycemia (5.6 mmol/l) to values just above the threshold for Epi and glucagon secretion (3.9 mmol/l). Individualized doses of insulin were infused to maintain euglycemia during pancreatic clamps by use of somatostatin (250 microg/h), glucagon (1.0 ng. kg(-1). min(-1)), and growth hormone (GH) (3.0 ng. kg(-1). min(-1)) infusions without need for exogenous glucose. Then, to achieve physiological hyperinsulinemia (HIns), insulin infusions were fixed at 20% above the rate previously determined for each subject. In nondiabetic subjects, PG was reduced from 5.4 +/- 0.1 mmol/l to 3.9 +/- 0.1 mmol/l in the experimental protocol, whereas it was held constant (5. 3 +/- 0.2 mmol/l and 5.5 mmol/l) in control studies. In the latter, EGP (estimated by [3-(3)H]glucose) fell to values 40% of basal (P < 0.01). In contrast, in the experimental protocol, at comparable HIns but with PG at 3.9 +/- 0.1 mmol/l, EGP was activated to values about twofold higher than in the euglycemic control (P < 0.01). In DM1 subjects, EGP failed to increase in the face of HIns and PG = 3.9 +/- 0.1 mmol/l. The decrease from basal EGP in DM1 subjects (4.4 +/- 1.0 micromol. kg(-1). min(-1)) was nearly twofold that in nondiabetics (2.5 +/- 0.8 micromol. kg(-1). min(-1), P < 0.02). When PG was lowered further to frank hypoglycemia ( approximately 3.1 mmol/l), the failure of EGP activation in DM1 subjects was even more profound but associated with a 50% lower plasma Epi response (P < 0. 02) compared with nondiabetics. We conclude that glucagon- or epinephrine-independent activation of EGP may accompany other counterregulatory mechanisms during mild hypoglycemia in humans and is impaired or absent in DM1.

Adult↗
PubMed2000

Role of adenosine in insulin-stimulated release of leptin from isolated white adipocytes of Wistar rats.

Leptin, the ob gene product that can decrease caloric intake and increase energy expenditure, is functionally released by insulin from adipose tissue. Adenosine is thought to be an important regulator of the action of insulin in adipose tissue. The present study investigated the role of adenosine in the release of leptin by insulin in isolated rat white adipocytes. Release of leptin, measured by radioimmunoassay, from insulin-stimulated samples was seen after 30 min. Adenosine deaminase, at concentrations sufficient to metabolize endogenous adenosine, decreased insulin-stimulated leptin release. Also, the insulin-stimulated leptin release was completely blocked by the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX). Mediation of endogenous adenosine in this action of insulin was further supported by the assay of adenosine released into the medium from adipocytes stimulated with insulin. In addition, activation of adenosine A1 receptors by N6-cyclopentyladenosine (CPA) induced an increase in leptin release in a concentration-dependent manner that could be blocked by antagonists, either DPCPX or 8-(p-sulfophenyl)theophylline (8-SPT). In the presence of U73312, a specific inhibitor of phospholipase C (PLC), CPA-stimulated leptin secretion from adipocytes was reduced in a concentration-dependent manner, but it was not affected by U73343, the negative control for U73312. Moreover, chelerythrine and GF 109203X diminished the CPA-stimulated leptin secretion at concentrations sufficient to inhibit protein kinase C (PKC). These results suggest that, in isolated white adipocytes, the released adenosine acts as a helper and/or a positive regulator for insulin in the release of leptin via an activation of adenosine A1 receptors that involves the PLC-PKC pathway.

Adenosine↗