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J C Wang

Publications and source records attributed to J C Wang.

At least 145 records · Page 8Linked to original sources
PubMed1999

A radiation hybrid map of 48 loci including the clouston hidrotic ectodermal dysplasia locus in the pericentromeric region of chromosome 13q.

To facilitate the identification of the gene responsible for Clouston hidrotic ectodermal dysplasia (HED), we used a chromosome 13-specific radiation hybrid panel to map 54 loci in the HED candidate region. The marker retention data were analyzed using RHMAP version 3. The 54 markers have an average retention frequency of 31.6% with decreasing retention as a function of distance from the centromere. Two-point analysis identified three linkage groups with a threshold lod score of 4.00; one linkage group consisted of 49 loci including the centromeric marker D13Z1 and the telomeric flanking marker for the HED candidate region D13S143. Assuming a centromeric retention model, multipoint maximum likelihood analysis of these 49 loci except D13Z1 provided a 1000:1 framework map ordering 29 loci with 21 unique map positions and approximately 2000 times more likely than the next order. Loci that could not be ordered with this level of support were positioned within a range of adjacent intervals. This map spans 347 cR9000, has an average resolution of 17.3 cR9000, and includes 3 genes (TUBA2, GJbeta2, and FGF-9), 18 ESTs, 19 polymorphic loci, and 8 single-copy DNA segments. Comparison of our RH map to a YAC contig showed an inconsistency in order involving a reversed interval of 6 loci. Fiber-FISH and FISH on interphase nuclei analyses with PACs isolated from this region supported our order. We also describe the isolation of 8 new chromosome 13q polymorphic (CA)n markers that have an average PIC value of 0.67. These data and mapping reagents will facilitate the isolation of disease genes from this region.

Chromosomes, Human, Pair 13↗
PubMed1999

Similarity in the catalysis of DNA breakage and rejoining by type IA and IIA DNA topoisomerases.

Studies of yeast DNA topoisomerase II with various alanine-substitution mutations provide strong biochemical support of a recent hypothesis that the type IA and IIA DNA topoisomerases act similarly in their cleavage and rejoining of DNA. DNA breakage and rejoining by either a type IA or a type IIA enzyme are shown to involve cooperation between a DNA-binding domain containing the active-site tyrosine and a Rossmann fold containing several highly conserved acidic residues. For a homodimeric type IIA enzyme, cooperation occurs in trans: the active-site tyrosine in the DNA-binding domain of one protomer cooperates with several residues in the Rossmann fold as well as other regions of the other protomer.

Alanine↗
PubMed1999

Effect of magnolol on in vitro mitochondrial lipid peroxidation and isolated cold-preserved warm-reperfused rat livers.

BACKGROUND/AIM: A mechanism suggested to cause injury to preserved organs is the generation of oxygen free radicals. Lipid peroxidation is one of the biological damages caused by oxygen free radicals. It is our aim to investigate whether magnolol, a strong antioxidant, suppresses the generation of oxygen free radicals and improves the viability of cold-preserved warm-reperfused rat livers. MATERIALS AND METHODS: In vitro lipid peroxidation was induced in rat hepatic mitochondria with ADP and FeSO4. The inhibitory effect of magnolol on lipid peroxidation was measured with oxygen consumption and malondialdehyde (MDA) formation. Subsequently, we preserved and reperfused rat livers in preservation solutions that contained magnolol. The hepatic enzymes and liver MDA were measured to assess the protective effect of magnolol on isolated rat livers. RESULTS: In rat hepatic mitochondria, magnolol was 470 times more potent than alpha-tocopherol in inhibiting oxygen consumption and 340 times more potent than alpha-tocopherol in inhibiting MDA formation. Addition of magnolol to Ringer's lactate solution had a protective effect, in terms of MDA formation and leakage of hepatic enzymes, on warm-reperfused but not cold-stored liver tissue. Addition of magnolol to University of Wisconsin (UW) solution, a widely used preservation solution, did not modify the effect of this solution on isolated liver tissues. CONCLUSIONS: We conclude that magnolol is an effective antioxidant and suppresses lipid peroxidation in rat liver mitochondria and can be used as a rinsing solution in protecting transplanted organs from lipid peroxidation during reperfusion, especially for those organs not preserved with UW solution.

Animals↗
PubMed1999

Cloning, sequence analysis, and expression in Escherichia coli of the gene encoding phenylacetaldehyde reductase from styrene-assimilating Corynebacterium sp. strain ST-10.

The gene encoding phenylacetaldehyde reductase (PAR), a useful biocatalyst for producing chiral alcohols, was cloned from the genomic DNA of the styrene-assimilating Corynebacterium sp. strain ST-10. The gene contained an opening reading frame consisting of 1,158 nucleotides corresponding to 385 amino acid residues. The subunit molecular weight was calculated to be 40,299, which was in agreement with that determined by polyacrylamide gel electrophoresis. The enzyme was sufficiently expressed in recombinant Escherichia coli cells for practical use and purified to homogeneity by three-column chromatography steps. The predicted amino acid sequence displayed only 20-29% identity with zinc-containing, NAD(+)-dependent, long-chain alcohol dehydrogenases. Nevertheless, the probable NAD(+)- and zinc-binding sites are conserved although one of the three catalytic zinc-binding residues of the zinc-containing, long-chain alcohol dehydrogenases was substituted by Asp in PAR. The protein contains 7.6 mol zinc/mol tetramer. Therefore, the enzyme was considered as a new member of zinc-containing, long-chain alcohol dehydrogenases with a particular and broad substrate specificity.

Alcohol Oxidoreductases↗
PubMed1999

P16 gene deletions and point mutations in patients with agnogenic myeloid metaplasia (AMM).

Studies of p16 alterations with homozygous deletions and mutation analysis were done in 32 patients with agnogenic myeloid metaplasia (AMM) including six patients in leukemic phase. No homozygous deletions were found and, one patient was found to have a shift band in exon 2C fragment by PCR-SSCP analysis. Further sequence analysis demonstrated that the mutated band was a point mutation of G to A in exon 2 codon 140 (GCG-->ACG) causing an amino acid substitution of alanine to threonine demonstrating this patient either carried an mutated gene in one allele as a polymorphism (heterozygous carrier of a mutant p16 gene) or carried a mutant p16 gene clone. This study demonstrates that p16 alterations with homozygous deletions and mutations were very rare in patients with AMM. A single patient found to have a shifted band by PCR-SSCP may be represented as a coincidence or as a polymorphism with a heterozygous carrier of mutated p16 gene, predisposable to AMM or as a mutant p16 gene which can be infrequently observed in this disease.

Blast Crisis↗
PubMed1999

Immunological characterization of two major secreted forms of recombinant hepatitis B virus e antigens.

Plasmids containing PCR-amplified hepatitis B virus e antigen (HBeAg) genes (HBeAg-MV and HBeAg-SV) were constructed and expressed in E. coli strain DH5alpha. The induced intracellular glutathione S-transferase (GST) fusion proteins of HBeAg-MV and HBeAg-SV were recovered and purified from bacterial lysates by affinity chromatography with glutathione-sepharose beads. The HBeAg-MV protein contained an additional 19 amino acids at its amino terminus. These two proteins were specifically cleaved from GST by the protease factor Xa and recognized by a monoclonal antibody against HBeAg. HBeAg-MV and HBeAg-SV were found to be the two major components of the post-modified HBcAg during viral infection. The antigenic specificities of the fusion and purified HBeAgs (factor Xa-digested) were confirmed by the Abbott HBe enzyme immunoassay (EIA) detection system. Sera from patients with confirmed hepatocellular carcinoma (HCC) specifically reacted only with HBeAg moiety of fusion proteins. HCC sera bound more strongly to the HBeAg-SV protein than to the HBeAg-MV one. This indicates that HBeAg-SV is either more antigenic than -MV or is the major target protein for the elicitation of antibody production after HBV infection. Thus, the two recombinant HBeAgs expressed and obtained in this study are appropriate immunological agents for the diagnostic detection of hepatitis B virus infection in humans.

Blotting, Western↗
PubMed1999

Characterization and retroviral transduction of an early human lymphomyeloid precursor assayed in nonswitched long-term culture on murine stroma.

In the hierarchy of human hematopoietic progenitors, long-term culture-initiating cells (LTC-IC) and extended LTC-IC belong to the earliest cell populations that can be assayed in vitro. We report the identification of a multipotential lymphomyeloid progenitor detected in a nonswitch culture system. We observed the emergence of CD33+ myeloid and CD19+ B-lymphoid cells following plating of lineage-depleted (Lin-) CD34 -enriched or purified CD34+ CD38- cord blood cells on MS-5 stroma in the absence of exogenous cytokines. Both CD19+ CD20- pro-B and CD19+ CD20+ pre-B lymphocytes coexist with myeloid cells in long-term culture. A limiting dilution approach was used to show that a single CD34+ CD38- cell can generate lymphomyeloid progeny in conventional (5-week) and extended (10-week) cultures. Most of the clones in long-term culture or extended long-term culture contained not only lymphoid and myeloid cells, but also myeloid clonogenic progenitors. A high proportion of CD34+ CD38- cells gave rise to lymphomyeloid clones after 5 and 10 weeks of culturing (up to 48% and 16%, respectively), which distinguishes the assay reported here from those using switch culture conditions. We performed retroviral gene transfer experiments involving 1-3 days of exposure of Lin CD34+ -enriched cells to virus encoding enhanced green fluorescent protein. Monitoring of gene transfer efficiency into LTC-IC by enhanced green fluorescent protein fluorescence showed that it is possible to achieve marking of lymphomyeloid LTC-IC, albeit to a lesser extent than myeloid-restricted LTC-IC.

ADP-ribosyl Cyclase↗
PubMed1999

MR imaging of cervical spine motion with HASTE.

The HASTE (half-Fourier acquisition single-shot turbo spin-echo) technique delivers images with T2-weighting in about half a second and could be ideal for fast dynamic studies when T2-weighting is needed. We evaluated cardiac-triggered HASTE to study cervical spine flexion/extension. The cervical spines of ten asymptomatic volunteers were studied during flexion/extension motion on a 1.5 Tesla imager using a cardiac triggered version of the HASTE technique. Midline sagittal images were acquired every 2 to 3 s during neck flexion and extension. Image quality was compared to traditional T2-weighted Turbo spin-echo. The study duration per flexion/ extension was typically less than 20 seconds and well tolerated. The cardiac-gated T2-weighted HASTE images compared favorably to the traditional T2-weighted TSE images in quality and overall anatomic detail. Range of motion averaged: flexion 30 degrees (range 8 degrees -48 degrees) and extension 23 degrees (range 0 degrees -57 degrees ). Greatest motion occurred in the lower cervical spine (C4-C7). At the intervertebral discs the canal diameter, anterior and posterior CSF spaces were widest in neutral position and decreased with flexion and extension. Therefore, Cardiac-gated T2 HASTE sequences provide diagnostic and time-efficient dynamic MR images of cervical spine motion.

Adult↗
PubMed1999

Mutation analysis of the putative tumor suppression gene PTEN/MMAC1 in sporadic breast cancer.

PTEN/MMAC1, a potential human tumor suppressor gene, has been found to have inactivating mutations in several types of cancer, including breast cancer. The incidence of breast cancer in Chinese is quite low in comparison with Caucasians, and genetic factors may play some roles. To further determine the role of PTEN/MMAC1 in breast cancer in Chinese, we used loss of heterozygosity (LOH), single strand conformation polymorphism (SSCP) with direct sequencing of variant bands, and Southern blot analysis methods to analyze mutations in PTEN/MMAC1 in 52 cases of breast cancer. None had LOH at chromosome 10q23.3. One mutation was identified, a somatic 3-base deletion, in one case. Our results suggest PTEN/MMAC1 does not play a major role in the development of sporadic breast cancer.

Adult↗
PubMed1999

Effects of pimobendan on the L-type Ca2+ current and developed tension in guinea-pig ventricular myocytes and papillary muscle: comparison with IBMX, milrinone, and cilostazol.

In this study, we compared the effects of pimobendan (PIM), a putative Ca(2+)-sensitizer and phosphodiesterase (PDE) inhibitor, on the L-type Ca2+ current (ICa) of guinea-pig ventricular myocytes and contractile tension of ventricular papillary muscles with those of a nonselective PDE inhibitor, isobutylmethylxanthine (IBMX), and selective PDE-III inhibitors, that is, milrinone (MIL) and cilostazol (CIL). The efficacy (maximum attainable effect) of these drugs for increasing ICa or developed tension (DT) ranged in the order of IBMX >> MIL > PIM > CIL. This finding suggests that the positive inotropic effect of each drug is roughly proportional to its increasing effect on ICa. The additional effect of PIM (a Ca(2+)-sensitizing effect) was not identified in "intact" preparations, and the potentiating effects of PIM on the DT and ICa were virtually the same as those observed for MIL. To isolate the Ca(2+)-sensitizing effect of PIM on the DT, we studied the effects of PIM in the presence of H89, an isoquinoline derivative possessing a selective inhibitory effect on cAMP-dependent protein kinase. In the absence of H89, 50 microM PIM increased the DT by 68 +/- 11% (mean +/- SE, n = 6). However, in the presence of 20 microM H89, which completely blocked the PIM-induced increase in ICa, PIM (50 microM) significantly increased the DT by 19 +/- 6% (n = 6), thereby indicating the presence of a positive inotropic effect attributable to a mechanism other than increased intracellular cAMP, that is, a Ca(2+)-sensitizing effect. The latter notion was supported by the finding that in the presence of H89 (20 microM), the PIM-induced augmentation of DT was accompanied by a prolongation of the time to 50% relaxation of contractile tension. In contrast, MIL (50 microM) and forskolin, a direct activator of adenylate cyclase (1-10 nM), did not increase DT in the presence of 20 microM H89. These results suggest that the fraction of positive inotropic effect of PIM attributable to its Ca(2+)-sensitizing effect is masked by its potent PDE-III inhibitory effect in "intact" ventricular preparations.

1-Methyl-3-isobutylxanthine↗
PubMed1999

Assessment of value and applications of in vitro testing of topical dermatological drug products.

The FDA recently issued a guidance covering practices of scaleup and post approval changes with semisolids (SUPAC-SS). This guidance outlines the steps that must be taken by a company to maintain certification of its semisolid dermatological products after quantitative changes have been made in their compositions and/or after changes have been made in the sourcing of their key ingredients, in their processing, in their batch sizes, and/or after their site of manufacture has been relocated. A key element within the guidance is a release test to be used to determine if the diffusional release of a drug found in a formulation is the same after changes have been made to the formulation as it was prior to implementing the changes. The AAPS-FDA sponsored workshop was set up to explore this qualifying test. The stated aims of the workshop were: a) to illustrate the methodology and techniques of in vitro release testing, b) to show the sensitivity of in vitro release with respect to manufacturing variables and to variations in components and composition (of specific formulations), c) to recognize in vitro release testing as a useful procedure for SUPAC documentation, d) to highlight and evaluate other applications of in vitro release testing, e) to explore the degree to which in vitro release testing and bioavailability may be related, and f) to evaluate the role of in vitro release testing of topical dosage forms as a tool to improve product quality.

Administration, Topical↗
PubMed1999

Analysis of TSG101 tumour susceptibility gene transcripts in cervical and endometrial cancers.

Carcinoma of the uterine cervix is a common malignancy among women that has been found to show loss of heterozygosity in the chromosome 11p. Recent studies have localized the TSG101 gene in this region, and also demonstrated a high frequency of abnormalities of this gene in human breast cancer. To determine the role of the TSG101 gene in the carcinogenesis of cervical and uterine carcinoma, 19 cases of cervical carcinoma and five cases of endometrial carcinoma, as well as nearby non-cancerous tissue from the same patients, and 16 blood samples from healthy persons as normal control were analysed by Southern blot analysis of genomic DNA, reverse transcription of the TSG101 mRNA followed by PCR amplification and sequencing of the products. We found that abnormal transcripts of the TSG101 gene were common both in cancerous or non-cancerous tissues of the uterus and cervix and in normal peripheral mononuclear cells. There was no genomic deletion or rearrangement in spite of the presence of abnormal transcripts, and no definite relationship between the abnormal transcripts and HPV infection was found. Although the frequency of abnormal transcripts was higher in cancerous than in non-cancerous tissue, normal peripheral mononuclear cells also had abnormal transcripts. Given these findings, the role of the TSG101 gene as a tumour-suppressor gene should be re-evaluated. Because some aberrant transcripts could be found at the first PCR reaction, we suggest that the aberrant transcripts might be the result of imperfect minor splicesome products.

Adult↗
PubMed1999

Bepridil differentially inhibits two delayed rectifier K(+) currents, I(Kr) and I(Ks), in guinea-pig ventricular myocytes.

1. We investigated the effects of bepridil on the two components of the delayed rectifier K(+) current, i.e., the rapidly activating (I(Kr)) and the slowly activating (I(Ks)) currents using tight-seal whole-cell patch-clamp techniques in guinea-pig ventricular myocytes, under blockade of L-type Ca(2+) current with nitrendipine (5 microM) or D600 (1 microM). 2. Bepridil decreased I(Ks) under blockade of I(Kr) with E4031 (5 microM), in a concentration-dependent manner. The concentration-dependent inhibition of I(Ks) by bepridil was fitted by a curve, assuming one-to-one interactions between the channel and the drug molecule. The concentration of half-maximal inhibition (IC(50)) was found to be 6.2 microM. 3. The effect of bepridil on I(Kr) was assessed using an envelope-of-tails test. In the control condition, a ratio of the tail current to the time-dependent current measured during depolarization was large (>1) at shorter pulses (<200 ms), and it decreased to a steady state value of approximately 0.4 with increases in the pulse duration. Bepridil at a concentration of 2 microM did not decrease this ratio at shorter pulses. 4. In a short-pulse (duration=50 ms) experiment that largely activates I(Kr), the drug was found to block I(Kr) in a cooperative manner (Hill coefficient=3.03) and the IC(50) was 13.2 microM. 5. These results suggest that bepridil at a clinical therapeutic concentration ( approximately 2 microM) selectively blocks I(Ks) but does not inhibit I(Kr). This may relate to the characteristic frequency-dependent effects of bepridil on the action potential duration (APD), e.g., the non-reverse use-dependent prolongation of APD.

Action Potentials↗
PubMed1999

Cytokine treatment or accessory cells are required to initiate engraftment of purified primitive human hematopoietic cells transplanted at limiting doses into NOD/SCID mice.

Little is known about the cell types or mechanisms that underlie the engraftment process. Here, we have examined parameters affecting the engraftment of purified human Lin-CD34+CD38- normal and AML cells transplanted at limiting doses into NOD/SCID recipients. Mice transplanted with 500 to 1000 Lin-CD34+CD38- cord blood (CB) or AML cells required the co-transplantation of accessory cells (ACs) or short-term in vivo cytokine treatment for engraftment, whereas transplantation of higher doses (>5000 Lin-CD34+CD38- cells) did not show these requirements suggesting that ACs are effective for both normal and leukemic stem cell engraftment in this model. Mature Lin+CD34- and primitive Lin-CD34+CD38+ cells were capable of acting as ACs even though no repopulating cells are present. Cytokine treatment of NOD/SCID mice could partially replace the requirement for co-transplantation of AC. Furthermore, no difference was seen between the percentage of engrafted mice treated with cytokines for only the first 10 days after transplant compared to those receiving cytokines for the entire time of repopulation. Surprisingly, no engraftment was detected in mice when cytokine treatment was delayed until 10 days posttransplant. Together, these studies suggest that the engraftment process requires pluripotent stem cells plus accessory cells or cytokine treatment which act early after transplantation. The NOD/SCID xenotransplant system provides the means to further clarify the processes underlying human stem cell engraftment.

Acute Disease↗
PubMed1999

Cervical flexion and extension radiographs in acutely injured patients.

Flexion and extension lateral radiographs of the cervical spine may suggest signs of ligamentous and soft tissue injuries in a potentially unstable spine. However, patients with acute injuries and severe pain and muscle spasms may not be able to move their necks effectively, severely compromising the diagnostic yield of the radiographs. In addition, there are reports of serious neurologic injuries occurring with the use of these radiographs in acutely injured patients. The purpose of this study was to determine the effectiveness and yield of obtaining cervical spine flexion and extension radiographs in the emergency department on acutely injured patients. Review of all patients with cervical flexion and extension radiographs presenting to a Level 1 trauma center was performed. All radiographs were judged based on the adequacy of flexion and extension movement and positive findings indicative of instability by the radiologist in the emergency room. The radiographs of one patient (0.34%) revealed positive findings of instability. Of the 290 flexion and extension radiographs, 97 (33.5%) of them showed such little or inadequate flexion or extension movement that cervical stability could not be assessed. Flexion and extension cervical radiographs should not be obtained routinely in the emergency department because 1/3 of these studies will be inadequate because of pain and muscle spasms experienced by patients. Patients with cervical injuries may not be able to fully flex and extend their necks; this may lead to false reassurance to patients who actually have had an inadequate study to diagnose potential instability.

Acute Disease↗
PubMed1999

Radial forearm free flap: hybrid version.

The hybrid version of the radial forearm free flap provides an alternative method for reconstruction in the head and neck. It is versatile and has certain theoretical and practical advantages, including high-flow venous drainage, long venous pedicle, lymphatic drainage, and the avoidance of venous anastomosis or venous transpositional graft. In those situations when the availability of veins is reduced after a radical neck dissection or the quality of vein is poor because of previous irradiation, the hybrid free flap is the method of choice for microvascular reconstruction in the head and neck region.

Aged↗
PubMed1999

Dermatoses in cement workers in southern Taiwan.

Construction workers are known to have occupational dermatoses. The prevalence of such dermatoses was unknown in Taiwanese construction workers. The objective of this study was to determine the work exposure, prevalence of skin manifestations, and sensitivity to common contact allergens in cement workers of southern Taiwan. A total of 1147 current regular cement workers were telephone-interviewed about skin problems during the past 12 months, work exposure, and personal protection. Among those interviewed, 166 were examined and patch tested with common contact allergens. A high % of cement workers reported skin problems in the past 12 months. More men (13.9%) reported skin problems possibly related to work than women (5.4%). Prevalence was associated with lower use of gloves, duration of work as cement worker, and more time in jobs involving direct manual handling of cement, especially tiling. A high % of dermatitis was noted in the 166 workers examined, which correlated with reported skin problems. On patch testing, construction workers had a high frequency of sensitivity to chromate. Sensitivity to chromate or cobalt was associated with reported skin problems, or dorsal hand dermatitis on examination. These workers' dermatitis was under-diagnosed and inadequately managed. It is concluded that cement workers in southern Taiwan had a high prevalence of skin problems related to cement use. Protective measures, work practice, and physician education should be improved to prevent or manage such problems.

Adult↗