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Biomedical subjects

M J Chang

Publications and source records attributed to M J Chang.

At least 19 recordsLinked to original sources
PubMed2005

Effects of Panax ginseng extract on exercise-induced oxidative stress.

AIM: This study was designed to study the effects of Panax ginseng extract (PGE) on lipid peroxidation and scavenger enzymes induced by an acute exhaustive exercise in sedentary humans. METHODS: Seven healthy male subjects performed 2 exhaustive incremental exercises on the treadmill before and after 8 weeks' PGE ingestion (2 g each time, 3 times a day) as the control and PGE exercise, respectively. VO2, HR, and exercise duration during exercise were measured. Blood samples were collected at rest, and immediately, 10 and 30 min after each test and used to measure malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD). RESULTS: PGE administration significantly increased exercise duration until exhaustion by 1.5 min (p<0.05). MDA was significantly elevated following both trials (p<0.01), however, it was attenuated after PGE administration (p<0.01). CAT and SOD activities following exercise were significantly elevated, but the activities following control exercise were much lower than those following PGE exercise. CONCLUSIONS: These results suggest that the elevation in CAT and SOD activities as scavenger enzymes after PGE administration result in decrease of MDA level as one of PGE action mechanisms and consequently, prolong exercise duration until exhaustion. These findings support scientific claims that ginseng has ergogenic properties in facilitating recovery from exhaustive exercise.

Adolescent↗
PubMed2002

Slurry sampling for the determination of arsenic, cadmium, and lead in mainstream cigarette smoke condensate by graphite furnace-atomic absorption spectrometry and inductively coupled plasma-mass spectrometry.

The slurry sampling technique has been applied for the determination of As, Cd, and Pb in mainstream cigarette smoke condensate (MS CSC) by graphite furnace-atomic absorption spectrometry (GF-AAS) and inductively coupled plasma-mass spectrometry (ICP-MS). The MS CSC of the 1R4F Reference Cigarette was collected by electrostatic precipitation and was subsequently prepared as two slurry samples with and without the dispersing agent Triton X-100. Comparison of results determined by ICP-MS analyses of the 1R4F MS CSC slurry samples with those from the conventional microwave digestion method revealed good agreement. The precision of Triton X-100 slurry sampling and of microwave-assisted digestion was better than 10% RSD, and both were superior to slurry sampling without use of Triton X-100. The accuracy of the analytical results for the Triton X-100 slurry sample was further verified by graphite furnace-atomic absorption spectrometry (GF-AAS). For GF-AAS, the method limits of detection are 1.6, 0.04, and 0.5 microg x L(-1) for As, Cd, and Pb, respectively. For ICP-MS, the method limits of detection are 0.06, 0.01, and 0.38 microg x L(-1) for As, Cd, and Pb, respectively. The MS CSC of the 1R4F Reference Cigarette was collected in accordance with the Federal Trade Commission (FTC) smoking regime (35 mL puff volume of 2-s puff duration at an interval of 60 s) and the concentrations of As, Cd and Pb were 6.0+/-0.5, 69.3+/-2.8, and 42.0+/-2.1 ng/cigarette, respectively.

Journal Article↗
PubMed2001

Protective effects of acetylbergenin against carbon tetrachloride-induced hepatotoxicity in rats.

The present study was undertaken to investigate whether or not the hepatoprotective activity of acetylbergenin was superior to bergenin in carbon tetrachloride (CCl4)-intoxicated rat. Acetylbergenin was synthesized by acetylating bergenin, which was isolated from Mallotus japonicus. The hepatoprotective effects of acetylbergenin were examined against CCl4-induced liver damage in rats by means of serum and liver biochemical indices. Acetylbergenin was administered orally once daily for 7 successive days, then a 0.5 ml/kg mixture of CCl4 in olive oil (1:1) was intraperitoneally injected at 12 h and 36 h after the final administration of acetylbergenin. Pretreatment with acetylbergenin reduced the elevated serum enzymatic activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase and gamma-glutamyltransferase in a dose dependent fashion. Acetylbergenin also prevented the elevation of hepatic malondialdehyde formation and depletion of glutathione content dose dependently in CCl4-intoxicated rats. In addition, the decreased activities of glutathione S-transferase and glutathione reductase were restored to almost normal levels. The results of this study strongly suggest that acetylbergenin has potent hepatoprotective activity against CCl4-induced hepatic damage in rats by glutathione-mediated detoxification as well as having free radical scavenging activity. In addition, acetylbergenin doses of 50 mg/kg showed almost the same levels of hepatoprotective activity as 100 mg/kg of bergenin, indicating that lipophilic acetylbergenin is more active against the antihepatotoxic effects of CCl4 than those of the much less lipophilic bergenin.

Animals↗
PubMed2001

Abnormal liver function associated with occupational exposure to dimethylformamide and hepatitis B virus.

N,N-Dimethylformamide (DMF) has excellent solvent properties and is used intensively in the production of synthetic leather and resins. It has caused hepatoxicity in human and animal studies. Hepatitis B virus (HBV) and hepatitis C virus infections are reported to be the major causes of chronic liver diseases (including liver cirrhosis and liver cancer) in Taiwan. This study examined the dose-response relationship of the observed abnormal liver function among the DMF-exposed workers and the interactions among DMF, other chemical exposures, HBV infection, and potential confounders on liver abnormalities. The average DMF exposure concentration was 11.6 ppm (median, 5.9 ppm; range, 0.1 to 86.6 ppm); 65 of 176 workers (36.9%) had high (> 10 ppm) DMF exposure, 37 (21%) had middle (> 5 ppm, < or = 10 ppm) exposure, and 74 (42%) had low (< or = 5 ppm) exposure. There were 24 of 65 abnormal liver function test results (LFTs) (36.9%) (elevations of either glutamate oxaloacetate transaminase, glutamate pyruvate transaminase, or gamma-glutamyl transpeptidase) among the workers with high DMF exposure, 10 of 37 abnormal LFTs (27%) among workers with middle DMF exposure, and 11 of 74 abnormal LFTs (22%) among workers with low DMF exposure. Compared with the workers having low DMF exposure, the HBV, drinking, body mass index (BMI), sex, duration of employment, epichlorohydrin, and toluene exposure adjusted odds ratios (ORs) (and 95% confidence intervals [CIs]) for abnormal LFTs were 1.62 (0.61, 4.28) for workers with middle DMF exposure and 2.93 (1.27, 6.8) for those with high DMF exposure, and there was a significant dose response between DMF exposure and the prevalence of abnormal LFTs (P = 0.006). There were significant associations between abnormal LFTs and HBV carriers (adjusted OR: 3.11; 95% CI: 1.29, 7.5; P = 0.01) and between abnormal LFTs and increased BMI (adjusted OR: 2.2; 95% CI: 1.02, 4.72; P = 0.041). Ultrasonography showed significant associations between chronic liver diseases and HBV carrier status, increased BMI, and high cumulative (> 100 ppm-years) DMF exposure (respectively, adjusted OR: 9.58, 95% CI: 1.79, 51.4, P = 0.007; adjusted OR: 13.2, 95% CI: 1.32, 132, P = 0.025; and adjusted OR: 6.2, 95% CI: 1.14, 34.1, P = 0.032). Drinking and BMI were significantly associated with fatty liver (respectively, adjusted OR: 4.9, 95% CI: 1.39, 17.3, P = 0.012; and adjusted OR: 7.93, 95% CI: 1.6, 39.3, P = 0.01). In conclusion, this study demonstrated that (1) a significant dose-response relationship existed between liver function abnormalities and DMF exposure among workers in Taiwan, (2) HBV carrier status or increased BMI had synergistic effects with DMF in causing liver abnormalities (abnormal LFTs and clinical chronic liver diseases).

Adult↗
PubMed2001

Effects of bergenin, the major constituent of Mallotus japonicus against D-galactosamine-induced hepatotoxicity in rats.

The hepatoprotective effects of bergenin, a major constituent of Mallotus japonicus, were evaluated against D-galactosamine (GalN)-induced liver damage in rats. Bergenin (50, 100 and 200 mg/kg) was given orally once daily for 7 successive days and then GalN 400 mg/kg was injected intraperitoneally to rats at 24 and 96 h after the final administration of bergenin. Pretreatment with bergenin reduced the increased enzyme activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase, gamma-glutamyltransferase and the elevated level of malondialdehyde induced by GalN. Bergenin restored the decreased hepatic contents of glutathione as well as the decreased activities of glutathione S-transferase and glutathione reductase by GalN towards normalization, suggesting that the hepatoprotective effects of bergenin may consist in maintaining adequate levels of hepatic glutathione for the removal of xenobiotics. The present results indicate that bergenin has hepatoprotective effects against GalN-induced hepatotoxicity in rats.

Animals↗
PubMed2000

The antihypertensive and cardioprotective effects of (-)-MJ-451, an ATP-sensitive K(+) channel opener.

ATP-sensitive K(+) (K(ATP)) channel openers have been shown to be a potential class of therapeutic agents for the control of cardiovascular diseases, including angina, arrhythmias, and hypertension. In this study, the pharmacological activity of 6-cyano-3S,4R-dihydro-2, 2-dimethyl-2H-3-hydroxy-4-[5S-(1-hydroxymethyl)-2-oxo-1-pyrrolidinyl] -1-benzopyran ((-)-MJ-451), a synthetic K(ATP) opener, was evaluated in anesthetized rat models and in isolated rat thoracic rings. Results demonstrated that intravascular injection of (-)-MJ-451 (0. 02, 0.05 and 0.1 mg/kg) produced an immediate, dose-related reduction in mean arterial blood pressure in anesthetized spontaneously hypertensive rats (SHR), which persisted for more than 3 h and was not accompanied by reflex tachycardia. The hemodynamic changes were completely abolished by pretreatment with glibenclamide (4 mg/kg, i.v. bolus), a selective K(ATP) channel blocker. In isolated thoracic aorta, (-)-MJ-451 (10 nM-3 microM) produced a concentration-dependent vasodilator effect on the phenylephrine (0.3 microM)-induced vasoconstriction. Moreover, (-)-MJ-451 relaxed the thoracic aorta contracted by low (5, 20 and 30 mM), but not high (40 and 60 mM) concentrations of extracellular potassium. In addition, (-)-MJ-451 showed cardioprotective effects in the rat model of 45-min left coronary artery occlusion followed by 1-h reperfusion. In myocardial ischemia, pretreatment with (-)-MJ-451 (2, 5 and 10 microg/kg, i.v. bolus) significantly reduced the incidence of ventricular fibrillation and the mortality, also reducing the total number of ventricular premature contractions, total duration of ventricular tachycardia and ventricular fibrillation. A significant reduction in infarct size was noted in three (-)-MJ-451 (2, 5 and 10 microg/kg)-treated groups. Also, the cardioprotective effects of (-)-MJ-451 were virtually abolished by pretreating the rats with glibenclamide (4 mg/kg, i.v. bolus). In conclusion, (-)-MJ-451, through opening the K(ATP) channel, exerted antihypertensive and cardioprotective effects. Therefore, it is suggested that (-)-MJ-451 has potential in the treatment of hypertension or acute myocardial infarction.

Adenosine Triphosphate↗
PubMed2000

Effects of acetylbergenin against D -galactosamine-induced hepatotoxicity in rats.

The hepatoprotective effects of acetylbergenin were examined against D -galactosamine (GalN)-induced liver damage in rats, compared with that of bergenin reported previously. Acetylbergenin was synthesized from acetylation of bergenin, isolated from Mallotus japonicus, to increase lipophilic and physiological activities. Acetylbergenin was administered orally once daily for 7 days and then GalN (400 mg kg(-1), i.p.) was injected at 24 h and 96 h after the final administration of acetylbergenin. Acetylbergenin reduced the elevated serum enzyme activities of alanine/aspartate aminotransferase, sorbitol dehydrogenase and gamma -glutamyltransferase and the formation of hepatic malondialdehyde induced by GalN. Acetylbergenin also significantly restored towards normalization the decreased levels of glutathione and the decreased activities of glutathione S-transferase and glutathione reductase induced by GalN. Therefore, these results suggest that acetylbergenin has hepatoprotective effects against GalN-induced hepatotoxicity by inhibiting lipid peroxidation and maintaining an adequate level of GSH for the detoxification of xenobiotics as underlying hepatoprotective mechanisms. In addition, lipophilic acetylbergenin showed more activity in the hepatoprotection than that of the much less lipophilic bergenin reported previously.

Analysis of Variance↗
PubMed2000

Dimethylacetamide, ethylenediamine, and diphenylmethane diisocyanate poisoning manifest as acute psychosis and pulmonary edema: treatment with hemoperfusion.

CASE REPORT: A 27-year-old man, employed by a synthetic fiber company, had been exposed to dimethylacetamide, ethylenediamine, and diphenylmethane diisocyanate in a confined space continuously for 4-6 hours per day for 3 days before admission. Hallucinations and delusions were noted at admission; pulmonary edema developed subsequently. The electroencephalogram showed diffuse moderate cortical dysfunction and slow waves at 4-7 Hz, 20-80 microV. Seizures, liver injury, and rhabdomyolysis were noted on the 4th hospital day. The patient was treated by hemoperfusion with a decrease in urine dimethylacetamide from 3,265 mg/g to 4 mg/g creatinine over 4 days. Serial urinary dimethylacetamide and electroencephalogram correlated with the clinical condition.

Acetamides↗
PubMed2000

N-Methyl-D-aspartate receptor antagonists enhance the head-twitch response, a 5-hydroxytryptamine2 receptor-mediated behaviour, in reserpine-treated mice.

In this study, N-methyl-D-aspartate (NMDA)-receptor antagonists enhanced the head-twitch response induced by 5-hydroxytryptamine (5-HT) in reserpine-treated mice. To minimize the risk of any indirect involvement of NMDA-receptor antagonists (D(-)-2-amino-5-phosphonopentanoic acid (AP-5), D(-)-3-(2-carboxypiperazine-4-yl)-propyl-1-phosphonic acid (CPP), (+)-5-methyl-10,11-dihydroxy-5H-dibenzo-[a,d]-cyclohepten-5,10-imi ne (MK-801), ketamine, dextrorphan and dextromethorphan) with 5-HT neurones, vesicle stores of monoamines, especially 5-HT, were depleted with reserpine. In addition, the enhancement of 5-HT-induced head-twitch response was inhibited by apomorphine and NMDA as well as ritanserin in reserpine-treated mice. These results support our previous conclusion that NMDA receptors play important roles in the glutamatergic modulation of 5-HTergic function at the postsynaptic 5-HT2 receptors in mice.

Adrenergic Uptake Inhibitors↗
PubMed1999

Modulation of translational efficiency by contextual nucleotides flanking a baculovirus initiator AUG codon.

In a previous study of translational regulation of a baculovirus gene, we observed that translation initiated at an unexpectedly high efficiency from an AUG codon found in what was believed to be a poor context (M.-J. Chang and G. W. Blissard, 1997, J. Virol. 71, 7448-7460). In the current study, we examined the roles of nucleotides flanking a baculovirus AUG initiator codon in modulating translation initiation in lepidopteran insect cells. The roles of nucleotides flanking the AcMNPV gp64 initiator codon were examined by site-directed mutagenesis and functional assays in transfected Sf9 cells. To eliminate potential cis-acting sequences and effects, the gp64 initiator context was cloned in-frame with a chloramphenicol acetyl transferase reporter gene and under the control of a heterologous promoter. All possible single-nucleotide substitutions were generated in positions -6 to -1 and +4 to +6, relative to the A of the initiator AUG codon, which was designated +1. Constructs were transfected into lepidopteran cells and translation products were quantified by an enzyme-linked immunosorbent assay procedure. Substitutions of pyrimidines or other nucleotides at the -3 position resulted in little or no detectable effect on translation efficiency. In contrast, specific substitutions at the +4 and +5 positions resulted in approximately 2- to 3-fold increases in translation. Substitution of A in the +4 position resulted in an approximately 3-fold increase in translation, and substitution of any nucleotide for T in the +5 position resulted in approximately 1.9- to 2.8-fold increases. Substitutions at other positions (-6 to -1 and +6) resulted in no detectable increase or decrease in translation efficiency. These experimental results suggest an optimal initiator context of 5'-N N N N N N A U G A a/c/g N-3' for efficient translation initiation in lepidopteran cells. Consensus translation initiation contexts were generated from baculovirus genes and lepidopteran genes, then compared with the experimental results from the gp64 initiator context.

Animals↗
PubMed1998

Induction of retinoblastoma gene expression during terminal growth arrest of a conditionally immortalized fetal rat lung epithelial cell line and during fetal lung maturation.

The process by which fetal lung epithelial cells differentiate into type 1 and type 2 cell is largely unknown. In order to study lung epithelial cell proliferation and differentiation we have infected 20-day fetal lung epithelial cells with a retrovirus carrying a temperature-sensitive SV40 T antigen (T Ag) and isolated several immortalized fetal epithelial cell lines. Cell line 20-3 has characteristics of lung epithelial cells including the presence of distinct lamellar bodies, tight junctions, keratin 8 and 18 mRNA, HFH8, and T1 alpha mRNA and low levels of surfactant protein A mRNA. At 33 degrees C 20-3 grows with a doubling time of 21 h. At 40 degrees C the majority of cells cease to proliferate. Growth arrest is accompanied by significant morphological changes including an increase in cell size, transition to a squamous phenotype that resembles type 1 cells, and an increase in the number of multinucleated cells within the population. Greater than 95% of the cells incorporate [3H]thymidine into DNA at 33 degrees C whereas at 40 degrees C label incorporation drops to less than 20%. When shifted down to 33 degrees C 40% of the cells remain terminally growth arrested. In addition, cells plated at 40 degrees C have a reduced ability to form colonies when replated at 33 degrees C. Treatment with TGF-beta increases the percentage of cells that terminally growth arrest to greater than 80%. Growth arrest is accompanied by an increase in the levels of c-jun, jun D, cyclin D1, C/EBP-beta, transglutaminase type II, and retinoblastoma (Rb) mRNA and an induction of p105, the hypophosphorylated, growth regulatory form of Rb. Evaluation of Rb mRNA in fetal lung indicates that it is induced 2.5-fold between 17 and 21 days of gestation. These studies indicate that 20-3 terminally growth arrests in culture at the nonpermissive temperature and that it may be useful in studying changes in gene expression that accompany terminal growth arrest during lung development.

Animals↗
PubMed1998

Synthesis of 2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carbonitriles as ATP-sensitive potassium channel openers.

A series of optically active tetrahydro-oxazino[2,3-c]benzopyran derivatives have been synthesized and evaluated for potassium channel opening activity. (4aR,11bR)-1-Benzoyl- 5,5-dimethyl-2,3,4a,11b-tetrahydro-oxazino[2,3-c]benzopyran-9-carb onitrile ((-)-11e) was identified as a bladder-selective potassium channel opener (IC50, bladder = 8.15 microM, IC50, portal vein = 34.5 microM).

Adenosine Triphosphate↗
PubMed1998

Bone marrow failure and myelofibrosis in a case of PVP storage disease.

"PVP storage disease" is a disorder occurring in patients who have received high molecular weight polyvinylpyrrolidone (PVP), which cannot be excreted from the body. These large polymers deposit in the histiocytes and cause proliferation and infiltration of histiocytes in the reticuloendothelial system. There was usually no significant damage to these organs except that prolonged administration might cause bone destruction, skin lesions, arthritis, and polyneuropathy. We describe a patient who had received a large amount of PVP-containing solution for years. Severe bone marrow failure with extensive infiltration of bone marrow by foamy histiocytes occurred later. In addition, she suffered from multiple pathological fractures with spinal cord compression and arthritis of bilateral knee joints.

Adult↗
PubMed1998

Lung function and general illness symptoms in a semiconductor manufacturing facility.

Large quantities of potent gases, dopants, photoactive chemicals (photoresists, photoinitiators), solvents, and ionizing radiation are used in the semiconductor manufacturing process, but little is known about the occurrence of respiratory disease from exposures in this industry. The purpose of this study was to assess the pulmonary risk by conducting pulmonary function tests and symptoms survey in a semiconductor plant in Taiwan. This study is part of a clinical survey conducted on 926 workers in a semiconductor plant in Taiwan in July 1995. The study items included a standard self-administered questionnaire, chest x-rays, pulmonary function tests, and physical examinations in 249 workers. There was a borderline significance of higher prevalence (P = 0.06) of restrictive lung abnormality in male photolithographic workers (4 of 21; 19.1%) than in male control workers (0 of 17; 0%), and the smoking- and age-adjusted odds ratio was 4.1 (95% confidence interval [CI], 0.41-41.6). There was a significantly higher prevalence (P = 0.02) of restrictive lung abnormality in male ion-implantation workers (5 of 19; 26.3%) than in male control workers (0 of 17; 0%), and the smoking- and age-adjusted odds ratio was 3.7 (95% CI, 0.52-26.7). There were significantly higher prevalences of airway irritation, eye irritation, headache, stress, tiredness, and poor memory in female photolithographic or etch/diffusion workers than in control workers. This study suggests that restrictive lung abnormality is a potential health effect in male silicon-wafer fabrication workers in the semiconductor industry. The tasks of male process, maintenance, and equipment engineers put them at risk for intermittent short-term peak exposure. This may account for a higher prevalence of mild restrictive lung abnormality among male engineers of photolithographic and ionimplantation sections. The findings of this medical surveillance are tentative, but they suggest that further investigation of the etiologic factors and the subsequent health effects is necessary.

Adult↗
PubMed1997

Late promoter selection in the baculovirus gp64 envelope fusion protein gene.

The upstream promoter region of the Autographa californica multicapsid nuclear polyhedrosis virus (AcMNPV) gp64 gene contains five copies of TAAG, the conserved sequence found at the transcriptional initiation sites of almost all baculovirus late genes. In AcMNPV-infected Sf9 cells, late transcription initiation is detected from only two upstream TAAG sites and not from three downstream TAAG sites. To examine several models for preferential TAAG site utilization, we constructed a series of recombinant AcMNPV baculoviruses that contain promoter region sequences from the gp64 gene fused to a chloramphenicol acetyl transferase reporter gene. Promoter-reporter constructs were inserted in the polyhedrin locus. To test a scanning model in which TAAG sites are sequentially selected according to their location in the region, we generated recombinant viruses in which the highly transcribed sites were inactivated by point mutations. Transcription from the mutant promoter constructs was compared qualitatively and quantitatively to transcription from the wild-type gp64 promoter. Inactivation of the upstream TAAG sites did not result in increased transcription from the downstream TAAG sites, suggesting that immediate context, rather than position, determines promoter utilization. To test this hypothesis, we made a series of minimal promoter constructs containing decreasing quantities of the sequences immediately flanking one of the active gp64 TAAG sites. Reporter constructs containing a gp64 TAAG site and > or = 12 bp of flanking sequence on both sides were transcribed at near wild-type levels. Constructs with less flanking sequence (9 or 6 bp of flanking sequence) were accurately transcribed, but at substantially lower levels, and transcription was not detected from constructs containing only 3 bp of flanking sequence. These results suggest that nucleotides immediately flanking the TAAG site (4-6 bp) are necessary for basal promoter activity while additional flanking sequences (> or = 12 bp) are required for late promoter activation and regulation. To further examine late promoter selection, we constructed recombinant AcMNPV baculoviruses that contain heterologous late promoters from the gp64 gene of the related virus Orgyia pseudotsugata MNPV (OpMNPV). TAAG sites that serve as functional late promoters in OpMNPV were found to mediate transcription initiation at only basal levels in the context of the AcMNPV genome, suggesting that late promoter activation may be virus specific within the family Baculoviridae.

Amino Acid Sequence↗
PubMed1997

Comparative evaluation on the biological monitoring of exposure to parathion and its methyl analog.

The effects of both parathion and methyl parathion on the inhibition of plasma cholinesterase were elaborated in a rat model employing a modified isocratic reverse-phase HPLC method coupled with UV detection for the determination of the urinary metabolite p-nitrophenol (U-4NP). A linearity of r2 > 0.995 was found for a standard curve ranging from 0.06 to 0.96 microg/mL with a % relative error of </= +/- 10% and a recovery of 89 +/- 2%. The % CV at all levels was </= 11%. A linear correlation was observed between the oral administration of parathion and methyl parathion for both the percent inhibiton of cholinesterase as well as the urinary elimination of 4NP. It is tentatively recommended that an U-4NP of 2. 0 mg/g creatinine be established as a biological exposure index (BEI) for methyl parathion.

Animals↗