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Biomedical subjects

C J Chang

Publications and source records attributed to C J Chang.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1999

Postural hypotension and postural dizziness in patients with non-insulin-dependent diabetes.

BACKGROUND: Postural hypotension with a decline of 20 mm Hg or more in systolic blood pressure on standing is considered a potentially dangerous hypotensive response. Postural dizziness is often strongly associated with postural hypotension. However, there is conflicting evidence, and previous studies have been confined to the elderly, not specifically to patients with diabetes. Thus, we evaluated the association between postural hypotension and postural dizziness, and determined the factors most likely related to postural hypotension in patients with diabetes. METHODS: The subjects were 204 consecutive noninsulin-dependent patients with diabetes and 408 age- and sex-matched control subjects. Postural hypotension was defined as a decline of 20 mm Hg or more in systolic blood pressure 1 minute after standing. Postural dizziness was any feelings of dizziness, lightheadedness, or faintness that occurred while standing during the examination. RESULTS: The prevalence of postural hypotension and postural dizziness in patients with diabetes was higher than in control subjects. Those patients with both diabetes and postural hypotension were older and had higher supine systolic blood pressures and higher plasma glycosylated hemoglobin and fasting glucose levels. They had higher prevalence of postural dizziness, hypertension, and cerebrovascular disease, and lower standing systolic blood pressures than those without postural hypotension. They also were more often being treated with antihypertensive agents. Only 32.8% of patients with diabetes with postural hypotension suffered from postural dizziness. Postural dizziness, hypertension, cerebrovascular disease, and plasma glycosylated hemoglobin levels were independently associated with postural hypotension in patients with diabetes. CONCLUSIONS: Postural dizziness, glycemic control, hypertension, and cerebrovascular disease were important determinants of postural hypotension in patients with diabetes. Postural hypotension was associated with postural dizziness, but it cannot be determined clinically just from the presence of postural dizziness because the sensitivity for diagnosis of postural hypotension is low.

Aged↗
PubMed1999

In vitro and in vivo photosensitizing capabilities of 5-ALA versus photofrin in vascular endothelial cells.

BACKGROUND AND OBJECTIVE: The objective of the present study was to evaluate the feasibility of photodynamic therapy (PDT) for complicated hemangiomas. The photosensitizing activities of 5-aminolevulinic acid (5-ALA) and Photofrin were evaluated in vitro with human dermal microvascular endothelial cells (MEC) and in vivo with the chicken cox comb. STUDY DESIGN/MATERIALS AND METHODS: The in vitro absorption and photosensitizing activities of 5-ALA and Photofrin were examined in a MEC culture system. The percentages of MEC killed by different drug concentrations at a wavelength of 630 nm were measured by either live/dead or lactate dehydrogenase-released assays. Similarly, the in vivo biological activities of 5-ALA and Photofrin exposed to different total light dosages at 630 nm were studied by determining the amount of necrosis produced in chicken combs. RESULTS: MEC incubated with 5-ALA at a concentration of 35 microg/ml and exposed to laser light at 630 nm at a power density of 100 mW/cm2 showed a 50% cell kill. MEC incubated with Photofrin at a concentration of 3.5 microg/ml and exposed to laser light at 630 nm at a power density of 100 mW/cm2 showed a 50% cell kill. Chicken combs that received 200 mg/kg of 5-ALA exposed to laser light at 630 nm at a power density of 100 mW/cm2 had an injury depth of 362.5+/-27.6 microm at histologic examination. Combs exposed to a power density of 100 or 120 mW/cm2 showed injury depths of 732.5+/-29.1 and 792.5+/-36.0 microm, respectively. Chicken combs that received 2.5 mg/kg of Photofrin exposed to laser light at 630 nm at a power density of 80 mW/cm2 had an injury depth of 535.6+/-22.3 microm at histologic examination. Combs exposed to a power density of 100 or 120 mW/cm2 showed injury depths of 795.8+/-32.5 and 805.2+/-49.1 microm, respectively. CONCLUSION: Both 5-ALA and Photofrin have the capability to destroy MEC in vitro and vasculature in vivo. However, Photofrin achieved a higher degree of cell kill and tissue destruction at lower drug concentrations and at lower power densities.

Aminolevulinic Acid↗
PubMed1999

The impact of redefining affection status for alcoholism on affected-sib-pair analysis.

The analysis of a complex disease such as alcohol dependence requires a more precise definition of affection status. Collaborative Study on the Genetics of Alcoholism (COGA) provided a variety of qualitative and quantitative measures as well as genotype information, in addition to two criteria of affection status. To identify two groups of phenotypically "more homogeneous" individuals among alcoholics (COGA criterion), we redefined affection status by using cluster analysis and classification and regression tree, incorporating some important covariates such as event related potentials, monoamine oxidase B activity, status of smoking, age of onset, three variables of personality assessed with the Tridimensional Personality Questionnaire and three latent class variables. With redefined affection status, we repeated nonparametric analysis by three sib pair analysis programs (SIBPAL, SIBPAIR, and BETA) using nine candidate DNA markers identified by Reich et al. [1998] and Long et al. [1998]. The goals of our analysis are 1) to confirm previous results for these nine markers with redefined affection status and 2) to compare the performance from these three programs.

Adolescent↗