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Biomedical subjects

S J Wu

Publications and source records attributed to S J Wu.

At least 19 recordsLinked to original sources
PubMed1992

Plasma renin activity, aldosterone level, serum and urinary electrolytes in normal pregnant women aged 35 and older.

Plasma renin activity (PRA), the plasma aldosterone (PA) level, and serum and urinary electrolytes were measured in 39 elderly pregnant women of greater than or equal to 35 (Group 1) and in 60 pregnant women less than 35 (Group 2) every four weeks from the 20th week of gestation to the fourth week postpartum. The PRA and PA levels increased in both groups. The PA levels increased after the 20th week and reached a peak at the 32nd week of gestation, while PRA decreased after the 20th week of gestation. This dissociation was observed in both groups. Daily urinary sodium excretion in Group 1 was higher than that of Group 2, while daily potassium excretion was not different between the two groups. Higher aldosterone secretion was observed after the 20th week of pregnancy in Group 1. It is concluded that pregnancy in older women is associated with higher sodium excretion and aldosterone secretion.

Aldosterone↗
PubMed1991

Cofactor interactions and the regulation of glutamate decarboxylase activity.

More than 50% of glutamate decarboxylase (GAD) in brain is present as apoenzyme. Recent work has opened the possibility that apoGAD can be studied in brain by labeling with radioactive cofactor. Such studies would be aided by a compound that inhibits specific binding. One possibility is 4-deoxy-pyridoxine 5'-phosphate, a close structural analog of the cofactor pyridoxal 5'-phosphate. The effects of deoxypyridoxine-P on the cyclic series of reactions that interconverts apo- and holoGAD was investigated and found to be consistent with simple competitive inhibition of the activation of apoGAD by pyridoxal-P. As expected from the cycle GAD was inactivated when incubated with glutamate and deoxypyridoxine-P even though cofactor was present, but no inactivation was observed with deoxypyridoxine-P in the absence of glutamate. Deoxypyridoxine-P also stabilized apoGAD against heat denaturation. These effects were quantitatively accounted for by a kinetic model of the apo-holoGAD cycle. Deoxypyridoxine-P inhibited the labeling by [32P]pyridoxal-P of GAD isolated from rat brain. Hippocampal extracts were labeled with [32P]pyridoxal-P and analyzed by SDS-polyacrylamide gel electrophoresis. Remarkably few bands were strongly labeled. The major labeled band (at 63 kDa) corresponded to one of the forms of GAD. Other strongly-labeled bands were observed at 65 kDa (corresponding to the higher molecular weight form of GAD) and at 69--72 kDa. Labeling of the 63- and 65-kDa bands was inhibited by deoxypyridoxine-P, but the 69-72 kDa bands were unaffected, suggesting that the latter were non-specifically labeled. The results suggest that the 63-kDa form of GAD makes up the majority of apoGAD in hippocampus.

Animals↗
PubMed1991

The protective efficacy of recombinant hepatitis B vaccine in newborn infants of hepatitis B e antigen-positive-hepatitis B surface antigen carrier mothers.

Recombinant hepatitis B vaccine has been shown to be as safe and effective as plasma-derived vaccines. However, its efficacy in the prevention of perinatal infection has not been fully evaluated in an endemic area. We recruited 110 high risk infants born to hepatitis B e antigen-positive-hepatitis B surface antigen (HBsAg) carrier mothers in a study of recombinant vaccine efficacy. They were randomized into 2 groups, A (54 infants) and B (56 infants), to receive 4 doses of vaccine, containing 20 or 10 micrograms of surface antigen, respectively, at 0, 1, 2 and 12 months of age. An additional 60 high risk infants were recruited later (Group C) and received three 20-micrograms doses of vaccine at 0, 1 and 6 months of age. All infants also received a dose (145 IU) of hepatitis B immunoglobulin soon after birth. Sera were collected at 0, 1, 2, 3, 6, 12 and 14 months of age to assay HBsAg and anti-HBs. At 12 months of age the HBsAg carrier rates were 7.4 and 1.8%, in Groups A and B, respectively. In Group C the HBsAg-positive rate was 3.3%. HBsAg was invariably first observed between 0 and 2 months of age. Virtually all noncarrier infants developed substantial titers of anti-HBs at 12 months of age. No serious adverse effect was observed after vaccination.

Carrier State↗
PubMed1991

Identification of Campylobacter jejuni and Campylobacter coli antigens with mucosal and systemic antibodies.

The development of a rapid and specific diagnostic assay for Campylobacter infections is important in determining the etiology of acute diarrhea in humans. Studies have shown that sonicated whole bacteria or partially purified antigens cross-reacted with antibodies against other closely related bacteria. To solve the problems of specificity, we identified specific antigens of Campylobacter jejuni and Campylobacter coli for use in diagnostic assays. We investigated the responses of serum, urine, and intestinal lavage antibodies in infected (fed live bacteria) and parenterally immunized (intraperitoneal injection of sonicated whole bacteria with adjuvant) mice directed against C. jejuni or C. coli by Western blot (immunoblot) analysis. Antibody responses were examined weekly for up to 28 days. Fewer antigens were detected by urinary and intestinal lavage fluid immunoglobulin A (IgA) than serum IgG and IgM for both parenterally immunized and infected mice. Serum from parenterally immunized mice detected more antigens than that from infected mice. Two high-molecular-weight antigens (62,000 and 43,000) were predominantly detected by serum, urine, and intestinal lavage fluids of both parenterally immunized and infected mice. Serum antibodies from 28-day parenterally immunized mice detected one antigen specific to C. coli with a molecular weight of 38,000 and one antigen specific to C. jejuni with a molecular weight of 27,000. An immunodominant protein with a molecular weight of 31,000 common to both C. jejuni and C. coli was also recognized by serum antibodies from parenterally immunized mice.

Animals↗
PubMed1991

Sequential changes in plasma renin activity and aldosterone level during pregnancy.

Sequential changes in plasma renin activity (PRA) and the plasma aldosterone (PA) level were studied prospectively in 101 patients at Taipei Municipal Women and Children Hospital from the 20th week of gestation to the 4th week postpartum. Average maternal age was 31.8 years old and average fetal birth weight was 3,235 g. The PRA and PA levels during pregnancy were higher than those of the normal nonpregnant women. PRA decreased gradually from the 20th week of gestation and dropped markedly after delivery. The PA level increased after the 20th week of gestation and peaked at the 32nd gestational week, then returned to the nonpregnancy level after delivery. A dissociation between the PRA and PA levels after the 28th week of gestation was observed. Possible causes for this dissociation are discussed. This study provides reference data on PA and PRA levels during the course of a normal pregnancy for use in further studies on abnormal gestation.

Adult↗
PubMed1991

Regulatory properties of brain glutamate decarboxylase (GAD): the apoenzyme of GAD is present principally as the smaller of two molecular forms of GAD in brain.

The apoenzyme of glutamate decarboxylase [enzyme without bound cofactor, pyridoxal 5'-phosphate (pyridoxal-P)] serves as a reservoir of inactive glutamate decarboxylase (GAD) that can be activated when additional GABA synthesis is required. We have investigated which of two molecular forms of GAD is present as apoenzyme in synaptosomes and in cortex, caudate nucleus, hippocampus, and cerebellum of rat brain. Endogenous glutamate apodecarboxylase (apoGAD) was labeled by incubating extracts of synaptosomes or punches of each region with 32P-pyridoxal-P, followed by reduction with NaBH4, to link covalently the 32P-pyridoxal-P to GAD. Proteins were separated by SDS-PAGE. Punches from all four brain regions and forebrain synaptosomes contained two forms of GAD with apparent Mrs of 63 and 65 kDa as identified by immunoblotting with four antiGAD sera. Punches and synaptosomes contained a major 32P-pyridoxal-P-labeled band with an apparent Mr of 63 kDa that was stained on immunoblots by the antiGAD serum 1440 and the monoclonal antibody GAD-6, and a minor labeled band at 65 kDa that was stained by the 1440, 6799, and K2 antisera. Synaptosomes contained remarkably few other strongly labeled proteins, but punches contained several other labeled bands. Three additional lines of evidence indicate that the labeled 63-kDa protein is apoGAD: (1) it was purified by immunoaffinity chromatography with the GAD-1 monoclonal antibody; (2) it yielded one major labeled peptide when digested with chymotrypsin, and that peptide appeared identical in peptide-mapping experiments to the labeled active-site peptide isolated from chromatographically prepared rat brain GAD; and (3) its labeling was selectively blocked by 4-deoxypyridoxine 5'-phosphate, a competitive inhibitor of the binding of pyridoxal-P to GAD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[Autogenous transplantation of pedicle iliac crest epiphysis to epiphyseal defect of joint. An experimental study in puppy].

In 24 immature dogs, autogenous iliac-crest apophyseal graft was transplanted into the defect created in epiphysis of the femoral head. The dogs were divided into 2 group. In the group I, the graft was pedicled with circumflex iliac vessels. In the group II, the same technique was used without pedicle. All the animals were followed up for 1-6 months. The specimens were studied by macroscopic, histological, histochemical and electron-microscopical examinations. The examinations revealed that the pedicle grafts survived with good remodelling in joint defects. The ossification of the iliac-crest physis seemed to be normal. The superficial part of the graft did not undergo ossification, and the histologic structure of the graft was similar to the articular cartilage of the femoral head. It is possible to reconstruct a joint surface and to repair the epiphyseal defect of joint.

Animals↗
PubMed1991

Electromyography interference pattern decomposition.

Decomposition of an interference pattern enables examination of individual electromyography (EMG) motor units and their firing rates at more than minimal contraction forces. In this decomposition method, significant events with a constant occurrence (near motor unit action potentials) can be enhanced, and unwanted events (distant motor unit action potentials, artifacts) eliminated, by calculating the average accumulated change while sliding a fixed-width window along the digitized EMG interference pattern. Nonparametric statistical methods are then applied to these data to determine which information is significant at the .05 level. The exact duration of significant information is identified without the need for arbitrary thresholds and filters to eliminate unwanted information. Events are then classified into groups of similar events by comparing: (1) correlation coefficients, (2) point-to-point differences, (3) amplitudes, and (4) areas. The classification is further refined by the use of firing-rate information.

Action Potentials↗
PubMed1990

Antiplatelet effects of chelerythrine chloride isolated from Zanthoxylum simulans.

Chelerythrine chloride is an antiplatelet agent isolated from Zanthoxylum simulans. Aggregation and ATP release of washed rabbit platelets caused by ADP, arachidonic acid, PAF, collagen, ionophore A23187 and thrombin were inhibited by chelerythrine chloride. Less inhibition was observed in platelet-rich plasma. The thromboxane B2 formation of washed platelets caused by arachidonic acid, collagen, ionophore A23187 and thrombin was decreased by chelerythrine chloride. Phosphoinositides breakdown caused by collagen and PAF was completely inhibited by chelerythrine chloride, while that of thrombin was only partially suppressed. Chelerythrine chloride inhibited the intracellular calcium increase caused by arachidonic acid, PAF, collagen and thrombin in quin-2/AM-loaded platelets. The cyclic AMP level of washed platelets did not elevated by chelerythrine chloride. The antiplatelet effect of chelerythrine chloride was not dependent on the incubation time and the aggregability of platelets inhibited by chelerythrine chloride was easily recovered after sedimenting the platelets by centrifugation and then the platelet pellets were resuspended. Chelerythrine chloride did not cause any platelet lysis, since lactate dehydrogenase activity was not found in the supernatant. These data indicate that the inhibitory effect of chelerythrine chloride on rabbit platelet aggregation and release reaction is due to the inhibition on thromboxane formation and phosphoinositides breakdown.

Adenosine Triphosphate↗
PubMed1990

An alternatively processed mRNA specific for gamma-glutamyl transpeptidase in human tissues.

Human gamma-glutamyl transpeptidase (GGT)1 is composed of two subunits derived from a single precursor (Nash, B., and Tate, S.S. (1984) J. Biol. Chem. 259, 678-685; Finidori, J., Laperche, Y., Tsapis, R., Barouki, R., Guellaën, G., and Hanoune, J. (1984) J. Biol. Chem. 259, 4687-4690) consisting of 569 amino acids (Laperche, Y., Bulle, F., Aissani, T., Chobert, M.N., Aggerbeck, M., Hanoune, J., and Guellaën, G. (1986) Proc Natl. Acad. Sci. U.S.A. 83, 937-941). In the present study we report the cloning of an altered form of this precursor from human liver. We have isolated two clones, one 2,632 base pairs (bp) long from a fetal liver cDNA library and one 926 bp long from an adult liver cDNA library, each containing a 22-bp insertion that introduces a premature stop codon and shortens the open reading frame to 1,098 bp when compared with known human cDNA sequences specific for GGT. Sequence analysis of a human genomic GGT clone shows that this insertion of 22 bp is generated by a splicing event involving an alternative 3'-acceptor site. By polymerase chain reaction experiments we demonstrate that the alternatively spliced mRNA is present in polysomes from the microsomal fraction of a human hepatoma cell line (Hep G2) and thus could encode an altered GGT molecule of 39,300 Da (366 amino acids) encompassing most of the heavy subunit which is normally 41,500 Da (380 amino acids). The altered mRNA is detected in various human tissues including liver, kidney, brain, intestine, stomach, placenta, and mammary gland. This report is the first demonstration of an alternative primary sequence in the mRNA coding for GGT, a finding that could be related to the presence of some inactive forms of GGT detected in human tissues.

Adult↗
PubMed1990

Species- and infective stage-specific monoclonal antibodies to Leishmania major produced by an in vitro immunization method.

Monoclonal antibodies specific to the infective-stage promastigotes of Leishmania major are needed for developing rapid diagnostic assays of infected sand flies. An in vitro immunization protocol was applied for the production of monoclonal antibodies using small amounts of L. major. Infective-stage promastigotes were isolated from sand flies (Phlebotomus papatasi) 7-10 days after infection and used as antigen for immunization. Two weeks after a primary immunization, murine splenocytes were removed and immunized in vitro with antigen in murine EL-4 thymoma cell conditioned medium. Three fusions were performed using X63-Ag.653 myeloma cells as fusion partners and two fusions were performed using FOX-NY cells. Antibodies specific to promastigotes were detected using an indirect enzyme-linked immunosorbent assay (ELISA). Initially 56 monoclonal antibodies were selected, and their species and stage specificity were determined using both an ELISA and an indirect fluorescent antibody assay (IFA). Twelve monoclonal antibodies showed species specificity to L. major when tested against four sympatric species of Leishmania. Four other monoclonal antibodies showed species and infective-stage specificity to L. major promastigotes. When tested in immunoblots, all four species- and stage-specific monoclonal antibodies bound to five protein bands that were unique to the infective-stage promastigotes.

Animals↗
PubMed1990

Glutamate-dependent active-site labeling of brain glutamate decarboxylase.

A major regulatory feature of brain glutamate decarboxylase (GAD) is a cyclic reaction that controls the relative amounts of holoenzyme and apoenzyme [active and inactive GAD with and without bound pyridoxal 5'-phosphate (pyridoxal-P, the cofactor), respectively]. Previous studies have indicated that progression of the enzyme around the cycle should be stimulated strongly by the substrate, glutamate. To test this prediction, the effect of glutamate on the incorporation of pyridoxal-P into rat-brain GAD was studied by incubating GAD with [32P]pyridoxal-P, followed by reduction with NaBH4 to link irreversibly the cofactor to the enzyme. Adding glutamate to the reaction mixture strongly stimulated labeling of GAD, as expected. 4-Deoxypyridoxine 5'-phosphate (deoxypyridoxine-P), a close structural analogue of pyridoxal-P, was a competitive inhibitor of the activation of glutamate apodecarboxylase by pyridoxal-P (Ki = 0.27 microM) and strongly inhibited glutamate-dependent labeling of GAD. Analysis of labeled GAD by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis showed two labeled proteins with apparent molecular masses of 59 and 63 kDa. Both proteins could be purified by immunoaffinity chromatography on a column prepared with a monoclonal antibody to GAD, and both were labeled in a glutamate-dependent, deoxypyridoxine-P-sensitive manner, indicating that both were GAD. Three peaks of GAD activity (termed peaks I, II, and III) were separated by chromatography on phenyl-Sepharose, labeled with [32P]pyridoxal-P, purified by immunoaffinity chromatography, and analyzed by SDS-polyacrylamide gel electrophoresis. Peak I contained only the 59-kDa labeled protein. Peaks II and III contained the both the 59- and 63-kDa proteins, but in differing proportions.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1990

Determination of erythrocyte glutathione peroxidase activity and its reference range in Chinese adults.

A method to assess selenium status of the body by measuring glutathione peroxidase activity in erythrocytes was studied. Reaction was measured by continuous monitoring of the decrease of NADPH at 340 nm. The erythrocyte glutathione peroxidase activity was determined at 37 degrees C, pH 7.5 by using one of the substrates, t-butyl hydroperoxide, to initiate the reaction, and using glutathione reductase as the coupling enzyme. The Km of the enzyme for glutathione and t-butyl hydroperoxide were determined to be 1.8 mM and 238 microM, respectively. The enzyme was stable at -20 degrees C or -70 degrees C for at least 5 months, and for at least 2 months when stored at 4 degrees C. The within-run and between-run coefficients of variation for this method were 3.3-4.9% and 3.0-7.1%, respectively. The test was linear up to 100 U/g hemoglobin, and had a sensitivity of 0.002 delta A/min at 3 U/L. The reference range of erythrocyte glutathione peroxidase in Chinese adults was estimated to be 28.6-87.8 U/g hemoglobin (n = 84), without a significant difference in the results between males and females.

Adult↗
PubMed1989

Different gamma-glutamyl transpeptidase mRNAs are expressed in human liver and kidney.

In human, the two subunits of gamma-glutamyl transpeptidase (GGT) arise from a common precursor encoded by a multigene family. Until now, a single specific coding sequence for this precursor (type I) has been identified in human placenta and liver. In the present study, we have isolated from a human kidney cDNA library, a GGT specific clone (0.8 Kb). The sequence of which (type II) i) covers the carboxy terminal part of the GGT precursor, ii) exhibits 22 point mutations and a 30 bp deletion as compared to the type I GGT sequence. The sequencing of a human genomic clone reveals that this type II GGT mRNA is encoded by a different gene than the type I GGT mRNA. Both type I and type II GGT mRNAs are expressed in human liver, while almost exclusively type II GGT mRNA is detected in human kidney.

Adult↗
PubMed1989

Screening of congenital hypothyroidism, phenylketonuria, galactosemia, homocystinuria, and maple syrup urine disease in moderate to severe mentally retarded Chinese children.

Five-hundred and fifty one mentally retarded children from seven institutes in Northern Taiwan were screened by dried blood spot for the detection of treatable congenital metabolic diseases, including congenital hypothyroidism, phenylketonuria, homocystinuria, maple syrup urine disease and galactosemia. We found 2 children (0.36%) with congenital hypothyroidism, 1 case (0.18%) of classical phenylketonuria and two cases (0.36%) of trisomy 21 associated with autoimmune thyroiditis. The results of our investigation suggest that congenital hypothyroidism and phenylketonuria can be the factors causing mental retardation among children in Taiwan and mass neonatal screening of these treatable inborn metabolic diseases is strongly indicated for efficiently circumventing mental retardation in our community.

Adolescent↗
PubMed1989

Abnormal thyroid function and hypercholesterolemia in a case of acute intermittent porphyria.

Acute intermittent porphyria is a genetic hepatic porphyria characterized by acute gastrointestinal and neurological symptoms, and accompanied by excess excretion of delta-aminolevulinic acid and porphobilinogen. Here, we report a case of acute intermittent porphyria with attacks of abdominal pain, an elevated serum thyroxine level, and hypercholesterolemia with an increased level of high-density lipoprotein-cholesterol concentration. The diagnosis of acute intermittent porphyria was confirmed by a high urinary excretion of porphobilinogen and a low level of erythrocyte hydroxymethylbilane synthase activity. After being treated with a high carbohydrate intake and propranolol, the patient improved gradually during the following 3 weeks. The patient remained asymptomatic during the 6-month follow-up period. The serum thyroxin and cholesterol levels returned to normal 6 months later. In conclusion, we suggest that for any patient who presents with unexplained abdominal pain, abnormal thyroid function and hypercholesterolemia, a simple Watson-Schwartz urine test should be performed for the screening of acute intermittent porphyria. If the Watson-Schwartz test is positive, the erythrocyte hydroxymethylbilane synthase activity should be determined to confirm the diagnosis of acute intermittent porphyria.

Acute Disease↗
PubMed1988

[A modified medium, bile esculin-pyrrolidonyl-beta-naphthylamide, for rapid differentiation between enterococci and nonenterococci].

A new medium was developed by adding 40 mg pyrrolidonyl-beta-naphthylamide (PYR) to 1 l bile esculin (BE) agar, and was named as BE-PYR agar. To evaluate the efficacy of BE-PYR agar in differentiating enterococci from nonenterococci, we inoculated 207 strains of group D streptococci (including 157 enterococci and 50 nonenterococci) to BE-PYR agar. After incubating overnight at 35 degrees C incubator, following by applying the PYR reagent to test the color change of colonies, results indicate that the accuracy of BE-PYR agar in the differentiation of enterococci from nonenterococci reaches to 100%. Therefore, BE-PYR agar was considered to be an effective laboratory tool in further differentiation of group D streptococci.

Agar↗