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Biomedical subjects

C Y Huang

Publications and source records attributed to C Y Huang.

At least 73 records · Page 4Linked to original sources
PubMed2000

Chimeric dengue type 2 (vaccine strain PDK-53)/dengue type 1 virus as a potential candidate dengue type 1 virus vaccine.

We constructed chimeric dengue type 2/type 1 (DEN-2/DEN-1) viruses containing the nonstructural genes of DEN-2 16681 virus or its vaccine derivative, strain PDK-53, and the structural genes (encoding capsid protein, premembrane protein, and envelope glycoprotein) of DEN-1 16007 virus or its vaccine derivative, strain PDK-13. We previously reported that attenuation markers of DEN-2 PDK-53 virus were encoded by genetic loci located outside the structural gene region of the PDK-53 virus genome. Chimeric viruses containing the nonstructural genes of DEN-2 PDK-53 virus and the structural genes of the parental DEN-1 16007 virus retained the attenuation markers of small plaque size and temperature sensitivity in LLC-MK(2) cells, less efficient replication in C6/36 cells, and attenuation for mice. These chimeric viruses elicited higher mouse neutralizing antibody titers against DEN-1 virus than did the candidate DEN-1 PDK-13 vaccine virus or chimeric DEN-2/DEN-1 viruses containing the structural genes of the PDK-13 virus. Mutations in the envelope protein of DEN-1 PDK-13 virus affected in vitro phenotype and immunogenicity in mice. The current PDK-13 vaccine is the least efficient of the four Mahidol candidate DEN virus vaccines in human trials. The chimeric DEN-2/DEN-1 virus might be a potential DEN-1 virus vaccine candidate. This study indicated that the infectious clones derived from the candidate DEN-2 PDK-53 vaccine are promising attenuated vectors for development of chimeric flavivirus vaccines.

Animals↗
PubMed2000

Polymorphism in the transmembrane region of the MICA gene and type 1 diabetes.

Although MHC class II genes have a stronger association with type 1 diabetes than MHC class I genes, studies have shown that MHC class I molecules play an independent role in the etiology of type 1 diabetes, and the existence of susceptibility genes within a segment of MHC between the HLA-B and TNF genes has been predicted, where MHC class I chain-related gene A (MICA) resides. MICA has a triplet repeat polymorphism in the transmembrane region consisting of five alleles. We analyzed this polymorphism in 162 unrelated children (82 boys) with type 1 diabetes (age at diagnosis 7.01 +/- 3.76 yr) and 154 randomly selected unrelated children (87 boys), age 2.81 +/- 2.12 yr. Phenotype frequency of allele A9 in children with type 1 diabetes was significantly higher than in controls (RR = 2.42, 95% CI = 1.52-3.85, p = 0.000162, pc = 0.00081). Gene frequency of allele A9 was also significantly higher in children with type 1 diabetes when compared with control children (RR = 2.73, 95% CI = 1.85-4.03, p = 2.62 x 10(-7), pc = 1.31 x 10(-6)). This study demonstrates that MICA allele A9 confers risk of type 1 diabetes.

Alleles↗
PubMed2000

Open total talar dislocation--report of two cases.

Total dislocation of talus from all its surrounding joints (tibiotalar, subtalar and talonavicular) is an extremely rare injury. Because of its rarity, only few case reports can be found in the literature. In the review of the literature, infection and AVN are the most commonly encountered complications that affect the outcome of these severe injuries. Herein we report two cases of open total talar dislocation. Immediate debridement, reduction of the talus, and primary skin closure was done followed by cast immobilization. After more than 2 years follow up, neither infection nor AVN was found. We conclude that reimplantation of the talus is preferable if the wound is relatively clean. Talectomy, or combined with tibiocalcaneal fusion should be reserved for later salvage procedure.

Adult↗
PubMed2000

Clinical experience in using polymerase chain reaction for rapid diagnosis of pulmonary tuberculosis.

BACKGROUND: Polymerase chain reaction (PCR) techniques have revolutionized the diagnosis of tuberculosis (TB). PCR has significantly improved the sensitivity and specificity of existing diagnostic methods. In this study, we report our experience using a modified IS6110-based nested PCR assay for rapid diagnosis of pulmonary TB. METHODS: A total of 327 respiratory specimens from 275 patients suspected of having pulmonary TB at Taipei Veterans General Hospital were tested using the nested PCR assay, acid-fast smear and culture for the presence of Mycobacterium tuberculosis complex (MTB). Nested PCR was performed with IS6110-based primers specific for MTB. We reviewed the medical records of patients and analyzed the clinical features. The PCR results were compared with the final clinical diagnosis. RESULTS: We identified MTB in 167 of 327 samples by the nested PCR assay. No non-tuberculous Mycobacterium (NTM) was identified among the clinical samples. Diagnosis by PCR took about 6 hours in this study. The sensitivity and specificity compared with culture were 94.7% and 100%, respectively for the smear-positive, culture-positive samples, and 76.7% and 98.6% for the smear-negative, culture-positive samples. The overall sensitivity, specificity, positive and negative predictive values, compared with culture results, were 91.7%, 98.6%, 98.8% and 90.6%, respectively. Two specimens positive by PCR and negative by culture were taken from patients on anti-TB drug therapy. These specimens were culture-positive before anti-TB drug therapy. After resolution of the discrepancies by studying the patients' clinical data, both specificity and positive predictive value reached 100%. CONCLUSIONS: The results indicated that this in-house nested PCR assay is a rapid and sensitive method for diagnosing pulmonary TB. It is also good for excluding infections caused by NTM.

Humans↗
PubMed1999

Adsorption of BTEX from aqueous solution by macroreticular resins.

Theoretical and experimental investigations were conducted on the adsorption of benzene, toluene, ethylbenzene and xylene (BTEX) by macroreticular resins. A mass transfer model based on the squared-driving force principle is presented for describing the BTEX transfer between the aqueous and solid phases. Also proposed is a theoretical model for describing the BTEX breakthrough curves of the adsorption column. While the mass transfer model involves only an overall mass transfer coefficient, the column adsorption model has two model parameters. Those parameters are conveniently estimated using the observed mass transfer and breakthrough data. The predictions using the proposed models were found to compare well with the experimental data of batch and column BTEX adsorption tests.

Adsorption↗
PubMed1999

Neuroprotective effects of an antioxidant in cortical cerebral ischemia: prevention of early reduction of the apurinic/apyrimidinic endonuclease DNA repair enzyme.

We examined the effects of the free radical scavenger, 21-aminosteroid, on apurinic/apyrimidinic endonuclease (APE/Ref-1) protein expression and subsequent infarction volume after photothrombotic cortical cerebral ischemia in mice. Immunohistochemistry and Western blot analysis showed a significant reduction in APE/Ref-1 expression 6 and 24 h after ischemia in untreated animals, whereas in drug-treated animals the reduction was much less at the same time points. The administration of 21-aminosteroid significantly decreased subsequent infarction volume 3 days after ischemia. These data suggest that 21-aminosteroid prevents the early decrease of APE/Ref-1 expression, thereby reducing cortical infarction after photothrombotic cerebral ischemia.

Animals↗
PubMed1999

M phase phosphorylation of cytoplasmic dynein intermediate chain and p150(Glued).

To understand how the dramatic cell biological changes of oocyte maturation are brought about, we have begun to identify proteins whose phosphorylation state changes during Xenopus oocyte maturation. Here we have focused on one such protein, p83. We partially purified p83, obtained peptide sequence, and identified it as the intermediate chain of cytoplasmic dynein. During oocyte maturation, dynein intermediate chain became hyperphosphorylated at the time of germinal vesicle breakdown and remained hyperphosphorylated throughout the rest of meiosis and early embryogenesis. p150(Glued), a subunit of dynactin that has been shown to bind to dynein intermediate chain, underwent similar changes in its phosphorylation. Both dynein intermediate chain and p150(Glued) also became hyperphosphorylated during M phase in XTC-2 cells and HeLa cells. Thus, two components of the dynein-dynactin complex undergo coordinated phosphorylation changes at two G2/M transitions (maturation in oocytes and mitosis in cells in culture) but remain constitutively in their M phase forms during early embryogenesis. Dynein intermediate chain and p150(Glued) phosphorylation may positively regulate mitotic processes, such as spindle assembly or orientation, or negatively regulate interphase processes such as minus-end-directed organelle trafficking.

Animals↗
PubMed1999

Sequencing of prototype viruses in the Venezuelan equine encephalitis antigenic complex.

The 5' nontranslated region (5'NTR) and nonstructural region nucleotide sequences of nine enzootic Venezuelan equine encephalitis (VEE) virus strains were determined, thus completing the genomic RNA sequences of all prototype strains. The full-length genomes, representing VEE virus antigenic subtypes I-VI, range in size from 11.3 to 11.5 kilobases, with 48-53% overall G+C contents. Size disparities result from subtype-related differences in the number and length of direct repeats in the C-terminal nonstructural protein 3 (nsP3) domain coding sequence and the 3'NTR, while G+C content disparities are attributable to strain-specific variations in base composition at the wobble position of the polyprotein codons. Highly-conserved protein components and one nonconserved protein domain constitute the VEE virus replicase polyproteins. Approximately 80% of deduced nsP1 and nsP4 amino acid residues are invariant, compared to less than 20% of C-terminal nsP3 domain residues. In two enzootic strains, C-terminal nsP3 domain sequences degenerate into little more than repetitive serine-rich blocks. Nonstructural region sequence information drawn from a cross-section of VEE virus subtypes clarifies features of alphavirus conserved sequence elements and proteinase recognition signals. As well, whole-genome comparative analysis supports the reclassification of VEE subtype-variety IF and subtype II viruses.

5' Untranslated Regions↗
PubMed1999

CHL1 is a dual-affinity nitrate transporter of Arabidopsis involved in multiple phases of nitrate uptake.

Higher plants have both high- and low-affinity nitrate uptake systems. These systems are generally thought to be genetically distinct. Here, we demonstrate that a well-known low-affinity nitrate uptake mutant of Arabidopsis, chl1, is also defective in high-affinity nitrate uptake. Two to 3 hr after nitrate induction, uptake activities of various chl1 mutants at 250 microM nitrate (a high-affinity concentration) were only 18 to 30% of those of wild-type plants. In these mutants, both the inducible phase and the constitutive phase of high-affinity nitrate uptake activities were reduced, with the inducible phase being severely reduced. Expressing a CHL1 cDNA driven by the cauliflower mosaic virus 35S promoter in a transgenic chl1 plant effectively recovered the defect in high-affinity uptake for the constitutive phase but not for the induced phase, which is consistent with the constitutive level of CHL1 expression in the transgenic plant. Kinetic analysis of nitrate uptake by CHL1-injected Xenopus oocytes displayed a biphasic pattern with a Michaelis-Menten Km value of approximately 50 microM for the high-affinity phase and approximately 4 mM for the low-affinity phase. These results indicate that in addition to being a low-affinity nitrate transporter, as previously recognized, CHL1 is also involved in both the inducible and constitutive phases of high-affinity nitrate uptake in Arabidopsis.

Animals↗
PubMed1999

Hip arthroplasty for osteonecrosis in patients with systemic lupus erythematosus.

Thirty-seven hip arthroplasties including 19 bipolar hemiarthroplasties (BH) and 18 total hip arthroplasties (THA) were performed in our hospital in 23 patients with systemic lupus erythematosus (SLE) for femoral head osteonecrosis between July 1984 and July 1996. These patients were followed up retrospectively to compare the results of BH and THA. One case with right side BH and left side THA expired about 1 year after operation and was excluded from this study. In both groups, these hips with pre-operative osteonecrosis were subclassified in Ficat and Arlet classification. The mean duration of follow-up was 44.5 months (24-85 months) for THA was 70.2 months (24-119 months) for BH. The mean Harris scores pre-operatively were 56.7 +/- 1.09 points in the BH group and 50.7 +/- 1.29 points in the THA group. The mean post-operative scores were 81.9 +/- 4.37 points in the BH group and 95.5 +/- 0.80 points in the THA group at final follow up. The clinical results of the THA group were better than those of the BH group. However, at an early stage before collapse of the femoral head (Ficat stage II), the results of BH were as good as those of THA. Five BH were converted to THA at the time ranging from 39 months to 113 months (mean 63.2 months) after primary operation due to acetabular cartilage wearing or severe groin pain. The failure rate of BH group was 27.8% (5/18). There was no loosening or revision in the THA group. Although the follow-up durations were different in these two groups, the clinical result was obviously superior in the THA group, particularly after the femoral heads had collapsed. Considering the relatively short life span of SLE patients, we prefer THA over BH in the treatment of the femoral head osteonecrosis in SLE patients. However, based on our results, BH is still a very good choice of treatment before the collapse of the femoral head.

Adolescent↗
PubMed1999

Effects of spinach powder fat-soluble extract on proliferation of human gastric adenocarcinoma cells.

Four kinds of assays were used to study the effect of a fat-soluble extract of spinach powder (SPFE) on the proliferation of human gastric adenocarcinoma cell line (SGC-7901) in vitro. These studies included: (i) cell growth assay, (ii) colony forming assay, (iii) MTT colorimetric assay, and (iv) 3H-TdR incorporation assay. The concentrations of SPFE expressed as the level of beta-carotene in the medium were 2 x 10(-8), 2 x 10(-7) and 2 x 10(-6) mol/L beta-carotene in assay (i)-(iii), but 4 x 10(-8), 4 x 10(-7) and 4 x 10(-6) mol/L beta-carotene in assay (iv) respectively. The results indicated that SPFE inhibited the proliferation and colony forming ability of SGC-7901 cells. And in MTT assay, SPFE inhibited the viability of SGC-7901 cells, but no inhibitory effect of SPFE was observed on the viability of lymphocytes in peripheral blood of healthy people. Finally, in the 3H-TdR incorporation test, both SPFE and beta-carotene showed significant inhibitory effects on DNA synthesis in SGC-7901 cells, but SPFE was more effective than beta-carotene.

Adenocarcinoma↗
PubMed1998

Rapid deletion of rearranged T cell antigen receptor (TCR) Valpha-Jalpha segment by secondary rearrangement in the thymus: role of continuous rearrangement of TCR alpha chain gene and positive selection in the T cell repertoire formation.

A rearranged T cell receptor (TCR) Valpha and Jalpha gene from a cytochrome c-specific T cell hybridoma was introduced into the genomic Jalpha region. The introduced TCR alpha chain gene is expressed in a majority of CD3 positive and CD4 CD8 double-negative immature thymocytes. However, only a few percent of the double-positive and single-positive thymocytes express this TCR alpha chain. This decrease is caused by a rearrangement of TCR alpha chain locus, which deletes the introduced TCR gene. Analysis of the mice carrying the introduced TCR alpha chain and the transgenic TCR beta chain from the original cytochrome c-specific T cell hybridoma revealed that positive selection efficiently rescues double-positive thymocytes from the loss of the introduced TCR alpha chain gene. In the mice with negatively selecting conditions, T cells expressing the introduced TCR alphabeta chains were deleted at the double-positive stage. However, a large number of thymocytes escape negative selection by using an endogenous TCR alpha chain created by secondary rearrangement maintaining normal thymocyte development. These results suggest that secondary rearrangements of the TCR alpha chain gene play an important role in the formation of the T cell repertoire.

Animals↗
PubMed1998

Single amino acid substitutions at the N-terminus of a recombinant cytotoxic ribonuclease markedly influence biochemical and biological properties.

Onconase is a cytotoxic ribonuclease with antitumor properties. A semisynthetic gene encoding the entire protein sequence was constructed by fusing oligonucleotides coding for the first 15 and the last 6 of the 104 amino acids to a genomic clone that encoded the remaining amino acid residues [Newton, D. L., et al. (1997) Protein Eng. 10, 463-470]. The resulting protein product expressed in Escherichia coli exhibited little enzymatic or cytotoxic activity due to the unprocessed N-terminal Met amino acid residue. In this study, we demonstrate that modification of the 5'-region of the gene to encode [Met-(-1)]Ser or [Met-(-1)]Tyr instead of the native pyroglutamate results in recombinant onconase derivatives with restored activities. [Met-(-1)]rOnc(E1S) was more active than [Met-(-1)]rOnc(E1Y) in all assays tested. Consistent with the action of native onconase, [Met-(-1)]rOnc(E1S) was a potent inhibitor of protein synthesis in the cell-free rabbit reticulocyte lysate assay, degrading tRNA at concentrations that correlated with inhibition of protein synthesis. An interesting difference between the recombinant onconase derivatives and the native protein was their susceptibility to inhibition by the major intracellular RNase inhibitor, PRI (onconase is refractory to PRI inhibition). [Met-(-1)]rOnc(E1S) and [Met-(-1)]rOnc(E1Y) inhibited protein synthesis in intact SF539 neuroblastoma cells with IC50's very similar to that of onconase (IC50 3.5, 10, and 10 microg/mL after 1 day and 0.16, 0.35, and 2.5 microg/mL after 5 days for onconase, [Met-(-1)]rOnc(E1S), and [Met-(-1)]rOnc(E1Y), respectively). Similar to that of onconase, cytotoxic activity of the recombinant derivatives was potentiated by monensin, NH4Cl, and retinoic acid. Brefeldin A completely blocked the enhancement of cytotoxicity caused by retinoic acid with all three proteins. Thus, drug-induced alterations of the intracellular trafficking of the recombinant derivatives also resembles that of onconase. Stability studies as assessed in serum-containing medium in the presence or absence of cells at 37 degreesC showed that the recombinant proteins were as stable to temperature and cell culture conditions as the native protein. Therefore, exchanging the Glu amino acid residue at the amino terminus of onconase with an amino acid residue containing a hydroxyl group produces recombinant proteins with ribonuclease and cytotoxic properties similar to native onconase.

Animals↗
PubMed1998

Social desirability and the clinical self-report inventory: methodological reconsideration.

This study assesses how social desirability affects responses in clinical self-report inventories. Six hundred items gathered from four normal personality questionnaires were adapted to devise a pre-experimental personality questionnaire (pre-EMHQ). Results obtained from administering Ko's Mental Health Questionnaire (KMHQ) and the pre-EMHQ to separate samples were the proportion of individuals answering "true" to each item (i.e., P(t)) and the social desirability scale value (i.e., SDSV) of each item. The Experimental Mental Health Questionnaire (EMHQ) was established from the pre-EMHQ by closely matching the P(t)s and the SDSVs of the two questionnaires. Administering the KMHQ and the EMHQ concurrently to another sample provided results for factor analysis and other statistical analyses. The SDSVs and the P(t)s for each of the KMHQ items certainly displayed a linearly increasing relation. The two sets of corresponding subscales also correlated significantly. By applying the polynomial regression analysis, the tendency to score might be expressed as a quadratic function of SDSVs. Two iterative principal-factor analyses of the two sets of subscales each resulted in two factors, and Factor 1 is similar in both the KMHQ and the EMHQ. In brief, social desirability plays a critical role in affecting responses in a clinical self-report inventory. The factors involved and suggestions proposed will be of value for further research.

Adolescent↗
PubMed1998

Hepatitis C virus variants circumventing cytotoxic T lymphocyte activity as a mechanism of chronicity.

BACKGROUND & AIMS: High rate of chronicity after acute hepatitis C virus (HCV) infection cannot be explained in the presence of a multispecific cytotoxic T lymphocyte (CTL) response. The aim of this study was to investigate the effect of virus variants on CTL activity in patients in whom chronicity developed. METHODS: CTL clones specific to a decapeptide epitope derived from hypervariable region 1 were generated from 5 HLA-A2-positive patients with acute hepatitis C by in vitro stimulation with synthetic peptides. The sequential change of this CTL epitope and its influence on the CTL recognition were examined. RESULTS: Virus variants did not appear in 3 patients with recovery, whereas variants with altered peptide ligands capable of antagonizing CTL activity emerged rapidly in the remaining 2 patients in whom chronicity developed. Importantly, these HLA-A2-restricted, hypervariable region 1-specific CTL clones shared the use of T-cell receptor (TCR) genes AV6 and BV17. CONCLUSIONS: These data suggest that there is only a narrow T-cell repertoire responding to a single viral peptide/HLA ligand. The emergence of HCV variants with altered peptide ligands as TCR antagonists accompanied by a limited TCR repertoire may provide a mechanism for HCV chronicity.

Acute Disease↗
PubMed1998

Evolution of bamboo mosaic virus in a nonsystemic host results in mutations in the helicase-like domain that cause reduced RNA accumulation.

A mutant population of bamboo mosaic potexvirus (BaMV) was isolated after serial passage using Chenopodium quinoa plants. While the wild type inoculum induced indistinct chlorotic lesions, the mutant produced obvious lesions on C. quinoa although RNA accumulation of the mutant in Nicotiana benthamiana protoplasts was significantly reduced compared to wild type. Mutations were identified in the helicase-like domain. One RT-PCR-generated cDNA clone (designated pL1-33) representing the helicase-like region showed four nucleotide mutations encoding three amino acid changes that were shown to result in dramatically decreased viral accumulation. Independent analyses of the effects of these substitutions showed that nucleotide changes at position 1722 resulting in a leucine to proline switch and position 2129 resulting in a histidine to tyrosine switch had the greatest effect on viral accumulation. Combination of these two mutations resulted in a undetectable viral accumulation. We have identified that amino acids within the helicase domain but outside the universally conserved helicase-like motifs that play an important role in viral amplification.

Amino Acid Sequence↗