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Biomedical subjects

W W Chen

Publications and source records attributed to W W Chen.

At least 37 records · Page 2Linked to original sources
PubMed1991

[Protection of biomembrane fatty acids by antioxidants studied with gas chromatography].

A gas chromatography method for the determination of degree of lipid peroxidation of polyunsaturated fatty acids (PUFA) in 3 kinds of biomembrane (human red blood cell, human platelet membrane and mitochondrial membrane of rat liver) was established. The method was used to study the inhibiting effect of several antioxidants on OH. radical induced lipid peroxidation reaction in biomembrane. The results showed that several compounds with phenolic hydroxyl groups (catechuicine, sodium ferulate, gallic acid and its derivatives) have significant protective effect on PUFA of the 3 kinds of biomembrane.

Animals↗
PubMed1991

[Antioxidative activity studies on the meaning of same original of herbal drug and food].

The antioxidative activity of aqueous extracts of 6 kinds of common food, Ziziphus jujuba, Crataegus pinnatifida, fresh Allium sativum, fresh Zingiper efficinale, Citrus tangerina and green tea, which are also used as traditional herbal drugs, was studied. The result indicated that all these extracts can scavenge (O2) free radical, inhibit lipid peroxidation of mice liver homogenate (in vivo and in vitro), decrease hyaluronic acid depolymerization induced by (O2), and inhibit the adenosine deaminase activity of mice liver homogenate (in vivo). These actions are very similar to the actions of those traditional Chinese tonic prescriptions and their individual herbal drugs studied before.

Adenosine Deaminase↗
PubMed1990

Taiwan, R.O.C.: perspectives in school health.

Continuous economic development and evolving social systems have created unique challenges for school health personnel in Taiwan. Due in part to economic growth and an improving health care system, average life expectancy has increased markedly for males and females since 1950. Traditional leading causes of death such as pneumonia, tuberculosis, and gastroenteritis have been replaced by accidents, neoplasms, and cardiovascular diseases. Schoolchildren suffer from various disorders that include hepatitis B, dental caries, and health problems related to scholastic pressure such as myopia, anxiety, and depression. However, new problems such as violence, substance use, and teen-age pregnancy may develop in the future. In response to the challenge, an extensive school health program has emerged that emphasizes school health instruction, school health services, and a healthful school environment. Increased attention has focused on teacher preparation in health education, and a cooperative approach to school health promotion emphasizes school, community, and interagency cooperation. Prompted by the establishment in 1980 of the Graduate Institute of Health Education, National Taiwan Normal University, school-based research initiatives have increased dramatically. Eighteen recommendations for further improvement are offered.

Delivery of Health Care↗
PubMed1990

Aberrant subcellular localization of peroxisomal 3-ketoacyl-CoA thiolase in the Zellweger syndrome and rhizomelic chondrodysplasia punctata.

Fibroblasts from patients with the inherited disorder Zellweger syndrome have few or no peroxisomes; multiple biochemical processes that normally occur in this organelle are defective. Rhizomelic chondrodysplasia punctata (RCDP) is another inherited disorder in which two unrelated peroxisomal metabolic processes, plasmalogen synthesis and phytanic acid oxidation, are impaired despite the normal appearance of peroxisomal structure. It was previously reported that one of the enzymes of peroxisomal fatty acid beta-oxidation, 3-ketoacyl-CoA thiolase (beta-keto-thiolase), was present in precursor rather than mature form in both of these diseases. Immunofluorescent staining for peroxisomal beta-ketothiolase showed the immunoreactivity to be localized in subcellular particles in fibroblasts from both Zellweger syndrome and RCDP patients, even though the former lack normal peroxisomes. Immunoblot studies were performed to determine the subcellular location of the thiolase precursor in fractionated fibroblasts from Zellweger and RCDP patients. In both disorders, thiolase immunoreactivity was detected in subcellular fractions having a lower density than normal peroxisomes and mitochondria, and was resistant to digestion by proteinase K. The density of the thiolase precursor-containing fractions was similar to that of peroxisomal membrane "ghost" fractions recently described by Santos et al. (J Biol Chem 263:10502-10509, 1988). Our results suggest that these are not empty membrane vesicles but contain at least one peroxisomal matrix protein. Furthermore, they exist not only in cells in which normal peroxisomes fail to form (Zellweger syndrome), but also in some cells which have catalase-containing peroxisomes (RCDP).

Acetyl-CoA C-Acyltransferase↗
PubMed1990

[Plasma pharmacokinetics of roxatidine in the healthy man: correlation with gastric antisecretory effect].

Inhibitory effects of roxatidine acetate upon human gastric secretion have been shown to be dose-related after oral administration. In order to correlate this effect with drug pharmacokinetics, blood concentration of the active metabolite, roxatidine, was assessed in 10 healthy volunteers, each receiving in random order 75, 150, 300, 600 mg of roxatidine acetate and placebo. Blood was drawn for roxatidine measurement at T 0 (time of drug intake) T 75, 90, 120, 150, 210, 240 and 300 min. Meal-induced gastric secretion was studied by intragastric titration (IGT) at 15 min intervals, from T 150 to T 240. Mean peak of blood concentration occurred at T 150 with significant correlation with the administered dosage. Gastric secretion inhibition over the 90 min of IGT correlated with peak concentration exclusively for the subpopulation with peak occurrence at T 150. Beyond the peak, decrease in roxatidine concentrations was slow, as expected from a known 6-h half-life. However, overall results showed that mean blood concentration was correlated with gastric secretion inhibition from T 180 on. The last IGT sample also correlated with the peak. Interpretation of these results would be different whether roxatidine concentration variations are appreciated as exhibiting a significant decrease or not. Infusion studies of roxatidine would be a valuable technique for further analysis and comparison of blood-concentration/efficacy relationships as compared with other H2-antagonists.

Adult↗
PubMed1989

Molecular analysis of peroxisomal beta-oxidation enzymes in infants with peroxisomal disorders indicates heterogeneity of the primary defect.

Immunoblot analysis of peroxisomal beta-oxidation enzymes proteins was carried on liver samples from 15 patients with peroxisomal disorders in which accumulation of very long chain fatty acids was always observed in plasma. In 11 cases including 4 cerebro-hepatorenal syndrome (CHRS), 4 neonatal adrenoleukodystrophy (NALD) and 3 infantile Refsum's disease, the liver peroxisomes could not be detected by electron microscopy. Immunoblot analysis revealed the absence, or presence in weak amounts, of the 72-kDa subunit of acyl-CoA oxidase, and the complete absence of the 52-kDa and 21-kDa subunits which are processed from the 72-kDa. The bifunctional protein (78-kDa) was absent or very reduced, as was the mature form of peroxisomal 3-ketoacyl-CoA thiolase (41-kDa). Multiple defects of peroxisomal beta-oxidation enzymes may be caused by an absence of synthesis or an inability to import proteins into peroxisomes in these patients. One patient, diagnosed as NALD, had no detectable liver peroxisomes but the presence, in normal amounts, of the three peroxisomal beta-oxidation enzyme proteins suggests that the transport of these enzymes into "peroxisomal ghosts" was still intact. The last 3 patients, clinically diagnosed as NALD, had normal liver peroxisomes. One patient had an isolated deficiency of the bifunctional protein and the 2 others had normal amounts of the 3 peroxisomal beta-oxidation enzymes, as shown by immunoblotting. This suggests that import and translocation of some peroxisomal proteins had occurred and that a mechanism is therefore required to explain the defect in these patients.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

Peroxisomal bifunctional enzyme deficiency.

Peroxisomal function was evaluated in a male infant with clinical features of neonatal adrenoleukodystrophy. Very long chain fatty acid levels were elevated in both plasma and fibroblasts, and beta-oxidation of very long chain fatty acids in cultured fibroblasts was significantly impaired. Although the level of the bile acid intermediate trihydroxycoprostanoic acid was slightly elevated in plasma, phytanic acid and L-pipecolic acid levels were normal, as was plasmalogen synthesis in cultured fibroblasts. The latter three parameters distinguish this case from classical neonatal adrenoleukodystrophy. In addition, electron microscopy and catalase subcellular distribution studies revealed that, in contrast to neonatal adrenoleukodystrophy, peroxisomes were present in the patient's tissues. Immunoblot studies of peroxisomal beta-oxidation enzymes revealed that the bifunctional enzyme (enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase) was deficient in postmortem liver samples, whereas acyl-CoA oxidase and the mature form of beta-ketothiolase were present. Density gradient centrifugation of fibroblast homogenates confirmed that intact peroxisomes were present. Immunoblots of fibroblasts peroxisomal fractions showed that they contained acyl-CoA oxidase and beta-ketothiolase, but bifunctional enzyme was not detected. Northern analysis, however, revealed that mRNA coding for the bifunctional enzyme was present in the patient's fibroblasts. These results indicate that the primary biochemical defect in this patient is a deficiency of peroxisomal bifunctional enzyme. It is of interest that the phenotype of this patient resembled neonatal adrenoleukodystrophy and would not have been distinguished from this disorder by clinical study alone.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1989

[The effect of biphenyl dimethyl dicarboxylate (DDB) on the fluidity of human erythrocyte membrane].

This paper deals with the effects of DDB on human RBC membrane fluidity as reflected by changes in the phase transition temperature and microviscosity monitored by ANS, NPN and DPH. The results showed that DDB decreased the fluidity of the shallow layer (ANS as probe), but increased the fluidity of the middle layer (NPN as probe) and deeper layer (DPH as probe). In addition, the drug was found to inhibit the hemolysis induced by MDA.

Dioxoles↗
PubMed1988

Prenatal diagnosis of rhizomelic chondrodysplasia punctata.

Plasmalogen biosynthesis and phytanic acid oxidation activity were measured in cultured chorionic villus samples or amniocytes from four pregnancies at risk for the rhizomelic form of chondrodysplasia punctata (RCDP). Normal results were obtained in three of the samples and post-natal examination or fetal ultrasound studies confirmed that the fetuses were unaffected. Chorionic villus culture in one case demonstrated defective plasmalogen biosynthesis and lack of phytanic acid oxidation. Pregnancy was interrupted at 10 weeks. Immunoblot studies of post-mortem fetal tissues showed that peroxisomal 3-oxoacyl-coenzyme A thiolase was present in the unprocessed form, a finding we had previously demonstrated in RCDP. These results establish that RCDP can be identified prenatally.

Amniocentesis↗
PubMed1988

Biochemical abnormalities in rhizomelic chondrodysplasia punctata.

Biochemical studies with emphasis on peroxisomal functions were conducted in six patients with well-documented rhizomelic chondrodysplasia punctata (RCDP) and compared with findings in patients with Zellweger syndrome and neonatal adrenoleukodystrophy (ALD). Patients with RCDP had three characteristic biochemical abnormalities: (1) profound defect in plasmalogen (ether lipid) synthesis, which is significantly greater than the analogous defect in Zellweger syndrome or neonatal ALD; (2) reduction of phytanic acid oxidation activity to 1% to 5% of control, similar to that observed in Refsum disease, Zellweger syndrome, and neonatal ALD; (3) presence of the unprocessed form of peroxisomal 3-oxoacyl-coenzyme A thiolase in the postmortem liver of two patients. Other peroxisomal functions were normal, including levels of very long chain fatty acids, pipecolic acid, and bile acid intermediates, and immunoblot studies of peroxisomal acyl-CoA oxidase and bifunctional enzyme in postmortem liver. Unlike what is observed in Zellweger syndrome and neonatal ALD, catalase activity in cultured skin fibroblasts was sedimentable, indicating that peroxisome structure is not grossly deficient in RCDP. The biochemical abnormalities in RCDP were consistent and set it apart from all the other known peroxisomal disorders.

Acetyl-CoA C-Acyltransferase↗
PubMed1988

Immunologic studies of rabies vaccination-induced Guillain-Barré syndrome.

Patients with Guillain-Barré syndrome (GBS) induced by rabies vaccines prepared from either suckling mouse brain (SMB) or mature sheep brain (Semple vaccine) and patients with sporadic, idiopathic GBS were studied for antibody to myelin basic protein (MBP), P2 protein, and Schwann cells. Sera from all four Semple vaccine- and one of five SMB vaccine-induced GBS patients, but none of the sporadic GBS patients, had antibody to MBP. Sera from Semple vaccinees also had antibody to fixed, transformed Schwann cells, but similar amounts of antibody were found in sera from Semple vaccinees with CNS complications and with minor non-neurologic complications, suggesting that this antibody was not specifically linked to the development of polyneuritis. None of the sera had detectable antibody to P2 protein. We conclude that patients with GBS constitute a heterogeneous population and that different target antigens may serve as a focus for this presumed autoimmune disease.

Animals↗
PubMed1988

Neonatal seizures and retardation in a girl with biochemical features of X-linked adrenoleukodystrophy: a possible new peroxisomal disease entity.

Neonatal hypotonia, seizures beginning at 5 days, and severe retardation were noted in a girl with normal karyotype and biochemical evidence of impaired adrenal function. Postmortem examination at 14 months revealed malformative and destructive lesions of central gray and white matter, atrophy of adrenal cortex with striated adrenocortical cells, hepatic fibrosis, and PAS-positive macrophages in several organs. Pathologically and clinically, this patient most closely approximated neonatal adrenoleukodystrophy (ALD) and differed strikingly from X-linked childhood ALD. In contrast, biochemical changes resembled the abnormalities observed in X-linked ALD and differed from those in the neonatal form. The very-long-chain fatty acid accumulation characteristic of both disorders was demonstrated, but unlike neonatal ALD, the levels or metabolism of plasmalogens, pipecolic acid, phytanic acid, and bile acid intermediates were normal, and peroxisomes in a liver biopsy specimen were present in normal number and appeared enlarged. While the case resembles the recently reported entity of peroxisomal acyl-CoA oxidase deficiency, assignment to this category was excluded by immunoblot studies on postmortem liver, which revealed normal amounts of this enzyme. Correlation of clinical, morphologic, and biochemical data suggests that this case is an example of a so-far undescribed entity, and reinforces the concept that the phenotypic spectrum of peroxisomal disorders is wider than realized.

Adrenoleukodystrophy↗
PubMed1988

Inhibition of food-stimulated acid secretion (intragastric titration) by roxatidine acetate. Dose-response study.

In 10 healthy male volunteers a dose-response study was carried out with roxatidine acetate, 75, 150, 300, and 600 mg, and placebo on food-stimulated gastric acid secretion (intragastric titration (IGT]. The design of the study, with drug intake 150 min before starting IGT, enabled stable inhibition over the 90-min observation period of the test. Cumulative secretory results showed a dose-related acid secretion inhibition (67% for 75 mg; 87.6% for 150 mg; 98.8% for 300 mg; 99.6% for 600 mg). The results were statistically significantly different from placebo and from each other, except for 300 mg versus 600 mg. With a Lineweaver-Burk plot, the ED50 was 41 mg and r = 0.98. Peak concentrations of roxatidine were observed either at T 150 or T 180. Significant correlation (r = 0.7; p less than 0.001) was obtained for the percentage inhibition with 75 mg and 150 mg together versus peak concentrations. Antisecretory potency with the IGT model applied to normal subjects appears to be of the same order for roxatidine acetate and for ranitidine.

Adult↗