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Biomedical subjects

C P Yang

Publications and source records attributed to C P Yang.

At least 19 recordsLinked to original sources
PubMed2006

Modeling biodegradation of toluene in rotating drum biofilter.

Rotating drum biofilters (RDBs) are cost-effective for control of emissions of volatile organic compounds (VOCs) from waste gas streams. In this paper, a dynamic mathematical model is presented which simulates and predicts the variation in performance of a multi-layer RDB with time on the basis of the two-film theory. The model takes into account factors including biofilm growth and biomass loss, and a changing biofilm surface area and thickness assuming quasi-steady-state conditions in the two-phase system and uniform bacterial population. Toluene was assumed to be the only rate-limiting substrate. The model equations for the gas-phase mass balance and biofilm growth were solved using MATLAB based on the fourth-fifth-order Runge-Kutta technique, and the concentration profiles in the biofilms were obtained using the method of orthogonal collocation. Simulation results showed that the toluene removal efficiency decreased with increased toluene loading or increased duration of operation of the biofilter. Calculation results were compared to the experimental results, which demonstrated that the dynamic model provided a good simulation of the performance of the biofilter.

Biodegradation, Environmental↗
PubMed2003

Efficacy of Helicobacter pylori eradication on platelet recovery in children with chronic idiopathic thrombocytopenic purpura.

AIM: Little is known about the influence of environmental factors on the epidemiology of idiopathic thrombocytopenic purpura (ITP). The role of Helicobacter pylori infection in relation to the development and/or persistence of ITP in infected patients remains controversial. Therapy used for eradicating H. pylori has led to a rise in platelet counts in a significant number of adult patients. but few paediatric studies have been undertaken to evaluate such treatment. The aim of this prospective study was to determine the prevalence of H. pylori and to evaluate whether H. pylori eradication can induce chronic ITP regression in children. METHODS: To investigate new, noninvasive techniques for diagnosis of H. pylori infection, an enzyme immunoassay for H. pylori antigens in faeces (HpSA) was evaluated. Patient eligibility criteria included isolated thrombocytopenia (< or = 50 x 10(9) L-(-1)) for more than 6 months without any identifiable cause and either normal or increased marrow megakaryocytes. H. pylori status was monitored before eradication and 4, 12, and 24 mo, after the end of treatment using Premier Platinum HpSA. RESULTS: In this study we evaluated 22 chronic ITP patients, 9 of whom were infected with H. pylori. Using repeated HpSA testing, we demonstrated for eradication of H. pylori after treatment in all infected patients. Five of the nine patients had increased platelet counts that persisted throughout the follow-up period. CONCLUSION: These results should stimulate additional research into the involvement of H. pylori infection in chronic ITP in childhood. This approach may offer an accepted algorithm at least for some of these patients.

Adolescent↗
PubMed2002

Synergistic effects of corticosterone and kainic acid on neurite outgrowth in axotomized dorsal root ganglion.

Corticosterone is the main adrenal glucocorticoids induced by stress in rats. Therapeutic use of high concentration of synthetic glucocorticoids in clinical treatment of spinal cord injury suggests that pharmacological action of glucocorticoids might be beneficial for nerve repair. In this article we cultured axotomized rat dorsal root ganglion neurons to investigate the effects of corticosterone and a glutamate receptor agonist kainic acid on neurite outgrowth. Our results revealed a synergistic effect of corticosterone and kainic acid in promoting neurite outgrowth when applied as early as one and two days in vitro, but not effective at three and four days in vitro. In addition, applied corticosterone and kainic acid were neurotoxic at three and four days in vitro but not at one and two days in vitro. The minimal concentrations of corticosterone and kainic acid to be effective were 10 microM and 1 mM, respectively. The neurotrophic effect of corticosterone and kainic acid was attenuated by the receptor tyrosine kinase A (TrkA) inhibitor AG-879. Western blot analysis and immunocytochemical studies revealed an increase of expressions of both TrkA and growth-associated protein GAP-43 in dorsal root ganglion neurons with combined treatment of corticosterone and kainic acid. Immunocytochemistry showed that corticosterone+kainic acid increase nerve growth factor immunoreactivity in dorsal root ganglion neurites and enhance GAP-43 immunointensity in dorsal root ganglion neurons. These results suggest that the neurotrophic effect of glucocorticoids on axonal regeneration might require facilitation of excitatory stimulation at an early stage of nerve injury, and nerve growth factor may mediate a growth signaling to accomplish the effect.

Animals↗
PubMed2002

Pitfalls in the diagnosis of idiopathic pulmonary haemosiderosis.

Idiopathic pulmonary haemosiderosis is a very rare but devastating disorder. Diagnosis is sometimes difficult and the clinical course exceedingly variable, as illustrated by this report of a girl, aged 2 years 4 months, with severe iron deficiency anaemia. There was no response to iron therapy and transfusions. Sustained and striking reticulocytosis associated with low haptoglobin mimicked haemolytic anaemia. Positive faecal blood test was documented after repeated testing. There were no pulmonary symptoms. A chest radiograph showed bilateral diffuse alveolar infiltrates. Bronchoalveolar lavage fluid showed numerous siderophages. High resolution computed tomography of the thorax revealed early pulmonary fibrotic changes. Recurrent reticulocytosis appeared to be a very useful sign of recurrent bleeding episodes.

Anemia, Iron-Deficiency↗
PubMed2001

A two-dimensional water-quality model for a winding and topographically complicated river.

In this paper, a two-dimensional numerical calculation algorithm for water-quality modeling is presented. The algorithm is designed specifically for river systems with complicated geometric conditions. When velocity field data of the river are not available, the numerical calculation algorithm for the water-quality modeling can be used to project river-water quality by using a topographic map of the river course and a finite element method. The calculation results of the water-quality model can show the concentration fields of various pollutants. The water-quality model was applied to a case-study in the Hengyang City section of Xiangjiang River in Hunan Province, China. The river under consideration is winding and has an isle between two branches. In 1995, Chinese government secured a World Bank loan to conduct a Waterways Project in the study region. It was expected that construction works in the river section might affect water quality. Given that the project would change the hydrological regime of the river system and discharges, and so would affect water quality, there would be a need for model results that would predict the water-quality impacts of the Waterways Project. In particular, the study intended to apply the model to identify changes in river-water quality associated with the construction of Dayuandu navigation key project. It is hoped that the numerical calculation algorithm for the water-quality modeling presented in this paper can also be applied to other shallow rivers with similar topographical conditions.

Algorithms↗
PubMed2001

Partial purification and characterization of polyphenol oxidase from banana (Musa sapientum L.) peel.

Polyphenol oxidase (EC 1.10.3.1, o-diphenol: oxygen oxidoreductase, PPO) of banana (Musa sapientum L.) peel was partially purified about 460-fold with a recovery of 2.2% using dopamine as substrate. The enzyme showed a single peak on Toyopearl HW55-S chromatography. However, two bands were detected by staining with Coomassie brilliant blue on PAGE: one was very clear, and the other was faint. Molecular weight for purified PPO was estimated to be about 41 000 by gel filtration. The enzyme quickly oxidized dopamine, and its Km value (Michaelis constant) for dopamine was 3.9 mM. Optimum pH was 6.5 and the PPO activity was quite stable in the range of pH 5-11 for 48 h. The enzyme had an optimum temperature at 30 degrees C and was stable up to 60 degrees C after heat treatment for 30 min. The enzyme activity was strongly inhibited by sodium diethyldithiocarbamate, potassium cyanide, L-ascorbic acid, and cysteine at 1 mM. Under a low buffer capacity, the enzyme was also strongly inhibited by citric acid and acetic acid at 10 mM.

Catechol Oxidase↗
PubMed2001

Isolation of an aerobic denitrifying bacterial strain NS-2 from the activated sludge of piggery wastewater treatment systems in Taiwan possessing denitrification under 92% oxygen atmosphere.

AIMS: To isolate aerobic denitrifying bacteria which will be applied to piggery wastewater treatment facilities for enhanced nitrate and nitrite removal. METHODS AND RESULTS: Nitrate-supplemented basal medium in airtight, crimp-sealed serum bottles containing an atmosphere of 92% oxygen was inoculated with denitrifiers, strains NS-2 and SM-3, and incubated at 30 degrees C. After 20 h, the concentration of nitrate was decreased rapidly by both NS-2 and SM-3. Nitrite production was almost zero during the whole experimental period for both strains. Nitrogen gas production peaked at the 20 h for both NS-2 (8.20 +/- 1.03 mmol l(-1)) and SM-3 (3.93 +/- 0.16 mmol l(-1)). CONCLUSIONS: Strain NS-2, which produced the highest N2 concentration in this work, was identified as Pseudomonas stutzeri. This strain is the most capable of aerobic and anaerobic conversion of nitrate to N2 without forming a nitrite intermediate. SIGNIFICANCE AND IMPACT OF THE STUDY: Strain NS-2 is highly promising for future application in in situ piggery wastewater treatment.

Aerobiosis↗
PubMed2001

Mutations in beta-tubulin map to domains involved in regulation of microtubule stability in epothilone-resistant cell lines.

The epothilones (Epos) are a group of natural products isolated from the myxobacterium, Sorangium cellulosum. They have a mechanism of action similar to that of Taxol, i.e., they stabilize microtubules and induce the formation of microtubule bundles in cells. Because they are simpler in structure than Taxol and preserve their activity in P-glycoprotein-expressing cells, they are being studied as potential antitumor drugs. In this work, a series of Epo-resistant A549 and HeLa cell lines have been selected and analyzed. Class I beta-tubulin, the major isotype of beta-tubulin in these Epo-resistant cell lines, has been sequenced in a search for mutations. In the Epo B-resistant A549 cells, there is a mutation at beta 292 from Gln to Glu, in the Epo A-resistant HeLa cell line there is a mutation at beta 173 from Pro to Ala, and in the Epo B-resistant HeLa cell line there is a heterozygous mutation at beta 422 from Tyr to a mixture of Tyr and Cys. These mutations are close to the M-loop, the nucleotide-binding site, and the microtubule-associated protein binding sites, respectively. It is likely that these mutations in beta-tubulin provide cells with a mechanism of resistance to the Epos and taxanes. Among these resistant cell lines, A549.EpoB40 is hypersensitive to microtubule-destabilizing drugs, such as vinblastine and colchicine, and HeLa.EpoB1.8 is dependent on the Epos or taxanes for growth. Our studies provide evidence that the M-loop, the GTP binding site, and the microtubule-associated protein binding sites at the COOH terminus in beta-tubulin are critical for the regulation of microtubule stability.

Antineoplastic Agents↗
PubMed2000

Taxol mediates serine phosphorylation of the 66-kDa Shc isoform.

In the human lung carcinoma cell line A549, Taxol (20 nM) causes a decreased electrophoretic mobility of the 66-kDa Shc isoform (p66shc), beginning 4 h after drug exposure, and reaching a maximum at 9-18 h. No shift was observed for the 52- and 46-kDa isoforms of Shc. The electrophoretic mobility shift of p66shc caused by Taxol is not the result of tyrosine phosphorylation, and there is no indication of a Shc/Grb2 complex in Taxol-treated A549 cells. This modification is blocked by the serine/threonine protein phosphatase 2A. In vivo 32P-labeling and subsequent phosphoamino acid analysis of p66shc indicated that both the original and the shifted p66shc were predominantly serine phosphorylated. Cyanogen bromide digestion of p66shc produced a phosphorylated fragment with an apparent molecular weight of approximately 7.9 kDa from the untreated cells and two phosphorylated fragments, of approximately 7.9 and approximately 9.6 kDa, from the Taxol-treated cells. The domain of Taxol-induced serine phosphorylation is thought to be in the cyanogen bromide fragment containing residues 2-65. The Taxol-induced electrophoretic mobility shift of p66shc was inhibited by the protein synthesis inhibitor, cycloheximide, but not by the mitogen-activated and extracellular signal-regulated protein kinase kinase (MEK) inhibitor, PD98059. This mobility shift did not occur in Taxol-resistant A549-T12 cells treated with 20 nM Taxol. In addition to Taxol, other microtubule-interacting drugs caused a decreased electrophoretic mobility of p66shc. This Taxol-mediated serine phosphorylation seen in p66shc may result from a MEK-independent signaling pathway that is activated in cells that have a prolonged or abnormal mitotic phase of the cell cycle and may play a role in signaling events that lead to cell death.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Specific B cell tolerance is induced by cyclosporin A plus donor-specific blood transfusion pretreatment: prolonged survival of MHC class I disparate cardiac allografts.

Donor-specific blood transfusion (DST), designed to prolong allograft survival, sensitized recipients of the high-responder PVG-RT1u strain, resulting in accelerated rejection of MHC-class I mismatched (PVG-R8) allografts. Rejection was found to be mediated by anti-MHC class I (Aa) alloantibody. By pretreating recipients 4 wk before grafting with cyclosporin A (CsA) daily (x7), combined with once weekly (x4) DST, rejection was prevented. The investigation explores the mechanism for this induced unresponsiveness. CD4 T cells purified from the thoracic duct of CsA/DST-pretreated RT1u rats induced rejection when transferred to R8 heart-grafted RT1u athymic nude recipients, indicating that CD4 T cells were not tolerized by the pretreatment. To determine whether B cells were affected, nude recipients were pretreated, in the absence of T cells, with CsA/DST (or CsA/third party blood) 4 wk before grafting. The subsequent transfer of normal CD4 T cells induced acute rejection of R8 cardiac allografts in third party- but not DST-pretreated recipients; prolonged allograft survival was reversed by the cotransfer of B cells with the CD4 T cells. Graft survival correlated with reduced production of anti-MHC class I (Aa) cytotoxic alloantibody. The results indicated that the combined pretransplant treatment of CsA and DST induced tolerance in allospecific B cells independently of T cells. The resulting suppression of allospecific cytotoxic Ab correlated with the survival of MHC class I mismatched allografts. The induction of B cell tolerance by CsA has important implications for clinical transplantation.

Animals↗
PubMed2000

Purification and characterization of polyphenol oxidase from banana (Musa sapientum L.) pulp.

Polyphenol oxidase (EC 1.10.3.1, PPO) in the pulp of banana (Musa sapientum L.) was purified to 636-fold with a recovery of 3.0%, using dopamine as substrate. The purified enzyme exhibited a clear single band on polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate (SDS)-PAGE. The molecular weight of the enzyme was estimated to be about 41000 and 42000 by gel filtration and SDS-PAGE, respectively. The enzyme quickly oxidized dopamine, and its K(m) value for dopamine was 2.8 mM. The optimum pH was at 6.5, and the enzyme activity was stable in the range of pH 5-11 at 5 degrees C for 48 h. The enzyme had an optimum temperature of 30 degrees C and was stable even after a heat treatment at 70 degrees C for 30 min. The enzyme activity was completely inhibited by L-ascorbic acid, cysteine, sodium diethyldithiocarbamate, and potassium cyanide. Under a low buffer capacity, the enzyme was also strongly inhibited by citric acid and acetic acid at 10 mM.

Catechol Oxidase↗
PubMed2000

Taxol and discodermolide represent a synergistic drug combination in human carcinoma cell lines.

Recently, three natural products have been identified, the epothilones, eleutherobin, and discodermolide, whose mechanism of action is similar to that of Taxol in that they stabilize microtubules and block cells in the mitotic phase of the cell cycle. In this report, we have compared and contrasted the effects of these new agents in Taxol-sensitive and -resistant cell lines. We also have taken advantage of a human lung carcinoma cell line, A549-T12, that was isolated as a Taxol-resistant cell line and found to require low concentrations of Taxol (2-6 nM) for normal cell division. This study then examined the ability of these new compounds to substitute for Taxol in sustaining the growth of A549-T12 cells. Immunofluorescence and flow cytometry have both indicated that the epothilones and eleutherobin, but not discodermolide, can substitute for Taxol in this Taxol-dependent cell line. In A549-T12 cells, the presence of Taxol significantly amplified the cytotoxicity of discodermolide, and this phenomenon was not observed in combinations of Taxol with either the epothilones or eleutherobin. Median effect analysis using the combination index method revealed a schedule-independent synergistic interaction between Taxol and discodermolide in four human carcinoma cell lines, an effect that was not observed between Taxol and epothilone B. Flow cytometry revealed that concurrent exposure of A549 cells to Taxol and discodermolide at doses that do not induce mitotic arrest caused an increase in the hypodiploid population, thereby indicating that a possible mechanism for the observed synergy is the potentiation of apoptosis. Our results suggest that Taxol and discodermolide may constitute a promising chemotherapeutic combination.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2000

Cytogenetic pattern of childhood leukemia in Taiwan.

BACKGROUND: Cytogenetic analyses of leukemic cells can be used to define specific subgroups of leukemia with different prognoses and, thereby, indicate appropriate treatment for individual cases. In this study, we investigated the cytogenetic pattern of childhood leukemia in Taiwanese patients. METHODS: A modified trypsin method of Seabright was used for G-banding of metaphase cells. RESULTS: From October 1996 to January 1999, 111 children with a diagnosis of leukemia were enrolled in the study. Of these, 73 patients had a diagnosis of acute lymphoblastic leukemia (ALL) and 63 of these patients had successful karyotyping of their leukemic cells. Among them, 20 (30.3%) had a normal karyotype, five had hypodiploidy (all had 45 chromosomes), five had low hyperdiploidy (47-50 chromosomes), 16 (24.2%) had high hyperdiploidy (> 50 chromosomes), and 20 had pseudodiploidy. Chromosomal translocation was identified in 24 (36.4%) of the ALL patients, 17 of whom had recurrent translocations including 10 with CD10+ B-precursor ALL [4 with t(9;22), 5 with t(1;19), and 1 infant with t(8;14)(q24;q11)], one neonate with CD10- early pre-B ALL with t(4;11), three B-cell cases with t(8;14), and three T-cell cases [2 with t(11;19)(q23;p13), and 1 (11;14)(p13;q11)]. One B-precursor patient had dic (9;12). Karyotypes of the 30 patients with acute myeloid leukemia (AML) included eight with t(8;21); seven with the French-American-British-M2 subtype (FAB-M2) and one with M1. All four of the patients with M3 had t(15;17), one patient with M4 had inv(16) and 7q-, one with M4Eo (M4 with eosinophilia) had t(7;16)(q21;q22), one with M0 had t(4;11)(q21;q23), and the remaining 11 had a normal karyotype. Three of the five adult-type chronic myeloid leukemia patients had standard Philadelphia chromosome, and the other two had a variant-form of Philadelphia chromosome. Both of the patients with juvenile myelomonocytic leukemia and one patient with myelodysplastic syndrome had a normal karyotype. CONCLUSIONS: Most findings were similar to previous reports. Although the high proportion of FAB-M2 patients (7/8) with t(8;21) and the consequently higher frequency (26.7%) of this translocation in the 30 AML cases in this study might have significance, a larger series of cases is needed to establish this finding.

Adolescent↗
PubMed1999

Persisting alloantigen prevents primed CD45RC- CD4 T cells from inducing allograft rejection: implications for immunological memory.

Antigen stimulation induces specific CD4 T cells to change from a resting phenotype (CD45RC+) to a "memory" phenotype (CD45RC-), an isoform switch that is reversible and regulated by persisting antigen. We show here that CD4 T cells responsible for mediating allograft rejection undergo a similar CD45RC+ to CD45RC- switch irrespective of whether antigen priming results in sensitization or tolerance in vivo. Thus, skin allograft priming, designed to induce second set rejection, and a donor-specific blood transfusion (DST), designed to prolong cardiac allograft survival, will generate CD45RC- CD4 T cells that induce acute rejection when adoptively transferred to T cell-deficient athymic nude recipients. The ability of CD45RC- T cells, obtained from DST donors, to induce graft rejection was prevented by giving nude recipients a DST 14, 28 or even 56 days before grafting and T cell transfer. Thus, prolonged allograft survival in rats after DST was found to be strongly linked with persisting alloantigen from the blood transfusion but was not associated with detectable microchimerism. Importantly, CD45RC- T cells from skin graft-primed animals were similarly prevented from inducing rejection by residual DST-derived alloantigen. The investigation shows (1) that an allogeneic blood transfusion primes (not tolerizes) alloreactive CD4 T cells and (2) that residual DST-derived alloantigen can block the action of specifically primed "memory" CD4 T cells. These findings have implications for understanding immunological memory.

Adoptive Transfer↗
PubMed1999

Unexpected mortality from the use of E. coli L-asparaginase during remission induction therapy for childhood acute lymphoblastic leukemia: a report from the Taiwan Pediatric Oncology Group.

The relative efficacy and toxicity of E. coli L-asparaginase and epidoxorubicin used in remission induction therapy for childhood acute lymphoblastic leukemia (ALL) were assessed in a randomized trial conducted in Taiwan. All patients had standard-risk ALL, defined as a leukocyte count <10 x 10(9)/l and were aged between 1 and 2 or 7 and 10 years, or a leukocyte count <50 x 10(9)/l and were aged between 2 and 7 years, without evidence of a T cell or mature B cell immunophenotype, central nervous system leukemia or expression of two or more myeloid-associated antigens. Ninety-three patients were randomized to receive E. coli L-asparaginase at 10,000 IU/m2 thrice weekly for nine doses and 108 to receive epidoxorubicin at 20 mg/m2 weekly for two doses during remission induction with daily prednisolone, weekly vincristine and, on day 22, a dose of etoposide plus cytarabine. Patients treated with L-asparaginase had a significantly higher rate of fatal infection with or without hemorrhage than did those who received epidoxorubicin during remission induction (six of 93 vs none of 108, P = 0.009), resulting in a lower rate of complete remission in the former group (93.6 vs 99.1%, P = 0.05). In addition, patients treated with L-asparaginase had a higher frequency of hyperglycemia and hypoalbuminemia. The overall rate of event-free survival was lower in patients treated with L-asparaginase than in other patients (P = 0.06); estimated 3-year rates were 72% (95% confidence interval, 55-89%) and 87.2% (78-96%), respectively. We conclude that L-asparaginase (Leunase) given at 10,000 IU/m2 for nine doses was poorly tolerated and resulted in excessive toxicity, both through its effects as a single agent and possibly through potentiation of etoposide.

Adolescent↗