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C C Chang

Publications and source records attributed to C C Chang.

At least 19 recordsLinked to original sources
PubMed2003

Spatial analysis of Yersinia pestis and Bartonella vinsonii subsp. berkhoffii seroprevalence in California coyotes (Canis latrans).

Zoonotic transmission of sylvatic plague caused by Yersinia pestis occurs in California, USA. Human infections with various Bartonella species have been reported recently. Coyotes (Canis latrans) are ubiquitous throughout California and can become infected with both bacterial agents, making the species useful for surveillance purposes. This study examined the geographic distribution of 863 coyotes tested for Y. pestis and Bartonella vinsonii subsp. berkhoffii serologic status to gain insight into the natural history of B. vinsonii subsp. berkhoffii and to characterize the spatial distribution of the two agents. We found 11.7% of specimens positive to Y. pestis and 35.5% positive to B. vinsonii subsp. berkhoffii. The two pathogens had distinct spatial clusters: Y. pestis was more prevalent in eastern portions of the state and B. vinsonii subsp. berkhoffii in coastal regions. Prevalence of Y. pestis increased with increasing elevation, whereas prevalence of B. vinsonii subsp. berkhoffii decreased with increasing elevation. There were differences in the proportions of positive animals on a yearly basis to both pathogens.

Animals↗
PubMed2003

Detection of HPV infection by analyzing the changes in structure of peripheral blood lymphocytes specifically induced by HPV E7 antigen.

PURPOSE: Detection of human papilloma virus (HPV) infection in clinical practice was examined based on the observation that peripheral blood lymphocytes exposed in vitro to antigenic or mitogenic stimulation change their intracellular structures as measured by polarization of fluorescent light emitted by labeled cells. MATERIALS AND METHODS: A total of 47 women were enrolled in this study. They were classified into four groups based on the results of HPV-DNA detection in cervical tissues by the Hybrid Capture II kit (Digene, Gaithersburg, MD, USA) and pathological examination. Ten women with no HPV-DNA detection were used as a normal control group. Fifteen women without pathological diagnosis in the cervical tissues had HPV-DNA detection. Ten women with CIN lesions had 80% HPV-DNA detection. Twelve women with invasive squamous cell carcinoma had 100% HPV detection. Peripheral blood lymphocytes derived from all women were collected and then exposed to HPV-E7 antigen and PHA mitogen. RESULTS: The positive response rate of HPV-E7 antigen was ten percent (1/10) in the normal control group, 73.3% (11/15) in the HPV infectious women, 50% (5/10) in the CIN women, and 91.7% (11/12) in the cervical cancer patients. The overall sensitivity rate of blood tests was 77.1% and the specificity rate was 57.8% when the Hybrid Capture II HPV Test kit was used as the standard detection method for cervical tissue. CONCLUSIONS: The results showed that peripheral blood lymphocytes derived from patients with cervical lesions might be another choice to be used as a screening method to detect HPV infection compared with conventional methods.

Carcinoma, Squamous Cell↗
PubMed2002

Validation for use with coyotes (Canis latrans) of a commercially available enzyme-linked immunosorbent assay for Dirofilaria immitis.

Serological tests offer a potentially powerful tool for monitoring parasites in wildlife populations. However, such tests must be validated before using them with target wildlife populations. We evaluated in coyotes (Canis latrans) the performance of a commercially available serological test used to detect canine heartworm (Dirofilaria immitis) in domestic dogs. We obtained 265 coyote carcasses and serological specimens from 54 additional coyotes from several regions of California, USA. We necropsied coyotes to determine the adult heartworm infection status. Blood was collected at necropsy on filter paper strips and allowed to dry; it was later eluted in a buffer solution, and the supernatant was tested for heartworm. Receiver operating characteristic (ROC) analysis was used to assess discriminatory power of the test and indicated a 93% probability that a randomly selected infected coyote would exhibit a higher enzyme-linked immunosorbent assay (ELISA) value than a randomly selected uninfected coyote. We estimated specificity at 96% (95% CI: 92-98%) for 165 uninfected coyotes and sensitivity at 85% (77-91%) for 100 infected coyotes, results similar to published values for the commercial serological test used with dog serum or plasma. Test performance was similar for filter paper specimens and supernatant of frozen whole blood collected in EDTA tubes (i.e. hemolyzed plasma). We found no difference in test performance among geographic or demographic coyote groups. Our findings support application of the test to filter paper or standard serological specimens for detection of heartworm in coyote populations.

Animals↗
PubMed2002

Tolerization of dendritic cells by T(S) cells: the crucial role of inhibitory receptors ILT3 and ILT4.

Immunoglobulin-like transcript 3 (ILT3) and ILT4 belong to a family of inhibitory receptors expressed by human monocytes and dendritic cells. We show here that CD8+CD28(-) alloantigen-specific T suppressor (TS) cells induce the up-regulation of ILT3 and ILT4 on monocytes and dendritic cells, rendering these antigen-presenting cells (APCs) tolerogenic. Tolerogenic APCs show reduced expression of costimulatory molecules and induce antigen-specific unresponsiveness in CD4+ T helper cells. Studies of human heart transplant recipients showed that rejection-free patients have circulating TS cells, which induce the up-regulation of ILT3 and ILT4 in donor APCs. These findings demonstrate an important mechanism of immune regulation.

Antigen-Presenting Cells↗
PubMed2002

Reduction in erythropoietin doses by the use of chronic intravenous iron supplementation in iron-replete hemodialysis patients.

BACKGROUND: Iron deficiency is the most common cause of suboptimal response to recombinant human erythropoietin (rHuEPO) in chronic hemodialysis (HD) patients. Iron supply can correct this situation, however, optimal dosage, route of administration, and monitoring of iron status during rHuEPO therapy in maintenance HD patients remains controversial. METHODS: We conducted a 12-month intravenous iron substitution trial in 149 iron-replete chronic HD patients receiving subcutaneous rHuEPO therapy. The available iron pool was maintained with 100 mg iron every 2 weeks or 1 month depending on serum ferritin and transferrin saturation levels, the rHuEPO dosage titrated depending on hematocrit (Hct) levels. RESULTS: After 12-month protocol, the Hct increased (28.7 +/- 4.1 vs 27.7 +/- 2.6, p = 0.003), rHuEPO requirement reduced 25% (46.1 +/- 28.9 vs 61.5 +/- 67.8 U/kg/week, p = 0.006), serum ferritin increased (1,383 +/- 727 vs 930 +/- 857 ng/ml, p < 0.001), so did the transferrin saturation (36.1 +/- 12.7 vs 27.5 +/- 12.8%, p < 0.001). The serum albumin decreased slightly but reached statistical significance (4.1 +/- 0.48 vs 4.2 +/- 0.36 g/dl, p = 0.006), so did the cholesterol levels (166 +/- 41 vs 173 +/- 38 mg/dl, p = 0.044) and pre-dialysis creatinine (11.3 +/- 2.3 vs 11.5 +/- 2.4 mg/dl, p = 0.015). Besides, the iPTH levels did not interfere with the rHuEPO dosage reduction and Hct increment in our patients. CONCLUSION: We conclude that maintaining high levels of serum ferritin and transferrin saturation could further reduce the requirement of rHuEPO in chronic HD patients, but the long-term effect of iron overloading to patients' nutritional status must be further evaluated in contrast to the economic saving.

Erythropoietin↗
PubMed2002

In vitro study of ultrasound based real-time tracking for renal stones in shock wave lithotripsy: Part II--a simulated animal experiment.

PURPOSE: We have previously developed and reported an ultrasound based real-time tracking system for renal stones. In the current study we continued to verify the reliability of this tracking system by a simulated animal test. MATERIALS AND METHODS: We used 13 prerecorded ultrasound stone trajectories to test the system. The real-time tracking system was implemented on the Litemed 9200 electrohydraulic lithotriptor (LiteMed Co., Taipei, Taiwan). An artificial stone and tap water were sealed in a balloon. The balloon was inserted into the pelvis of a pig kidney. While the kidney was affixed to and moved by a simulator, it was immersed in a specifically designed simulated animal model tank containing tap water. The stone was localized by ultrasound. The kidney was moved by the simulator according to a prerecorded stone trajectory. A total of 3,000 shock waves were delivered to the stone. For each recorded stone trajectory experiments were done under nontracking and tracking conditions. We performed tests of the fragment-to-weight ratio, which denotes the performance of a shock wave lithotriptor when fragmenting a stone. RESULTS: The mean fragment-to-weight ratio was 55.3% +/- 25.9% in the nontracking and 100% +/- 0% in the tracking group. The difference in these 2 groups was statistically significant (paired t test p <0.01). CONCLUSIONS: The ultrasound based real-time tracking system proved to improve the performance of a shock wave lithotriptor significantly when fragmenting stones in a simulated animal test. We believe that the tracking system would greatly reduce the number of shocks and time needed for treating renal stones.

Animals↗
PubMed2001

Mechanism of up-regulated gap junctional intercellular communication during chemoprevention and chemotherapy of cancer.

To develop a strategy for efficacious intervention in order to prevent or treat various cancers, one must understand the basic mechanism(s) by which various anticancer dietary factors prevent or reverse the tumor promotion or progression phases. Carcinogenesis is a multistage, multimechanism process, involving the irreversible alteration of a stem cell (the "initiation" phase), followed by the clonal proliferation of the initiated stem cell (the "promotion" phase), from which the acquisition of the invasive and metastatic phenotypes are generated (the "progression" phase). While intervention to prevent or treat cancer could occur at each step, the objective of this presentation will focus on the rate limiting step, the promotion phase.Gap junctional intercellular communication (GJIC) has been hypothesized to regulate growth control, differentiation and apoptosis. Most normal, contact-inhibited cells have functional GJIC, while most, if not all, tumor cells have dysfunctional homologous or heterologous GJIC. Cancer cells are characterized by the lack of growth control, by the inability to terminally differentiate and by resistance to apoptosis. Chemical tumor promoters (phorbol esters, DDT, phenobarbital, unsaturated fatty acids, saccharin, etc.) inhibit GJIC in a reversible fashion and at doses above particular chemical thresholds. Various oncogenes (e.g. ras, raf, neu, src, mos) down-regulate GJIC while several tumor suppressor genes can up-regulate GJIC. Antitumor promoters (retinoids, carotenoids, green tea components) and antioncogene drugs (i.e. lovastatin) can up-regulate GJIC. Transfection of gap junction genes ("connexins") into GJIC-deficient tumor cells can restore GJIC, growth control and reduce tumorigenicity. On the other hand, antisense gap junction genes can convert the phenotype of a non-tumorigenic cell to that of a tumorigenic one. Recently, a specific connexin knockout mouse was shown to have a higher frequency of spontaneous and induced liver cancers. Evidence from these studies clearly suggests that dietary factors can modulate GJIC by inducing various signal transducing systems. The modulation can either down-regulate GJIC and lead to tumor promotion or it can up-regulate GJIC and lead to suppression of the initiated cells. Multiple mechanisms of up- or down-regulation of GJIC exist, as well as multiple types of pre-malignant and malignant tumor cells that are unable able to have functional GJIC. GJIC can be down-regulated by mutations and by epigenetic means. Alteration of gene expression at the transcriptional, translational or post-translational levels would require specific dietary prevention or treatment of cancer. In conclusion, if dietary prevention or treatment of cancer is to occur, it must ameliorate the growth-stimulatory effects, above threshold levels, of chemicals, growth factors or hormones, that trigger various mitogenic/antiapoptotic signal transducing systems that block GJIC.

Animals↗
PubMed2001

Concentration variability of halocarbons over an electronics industrial park and its implication in compliance with the Montreal protocol.

This work investigated fugitive emissions of anthropogenic halocarbons in a semiconductor and electronics industrial park in Taiwan using both flask and in-situ measurement methods. Large concentration variabilities in methylchloroform, trichloroethene, and tetrachloroethene suggested substantial usage and emissions in the industrial park. While the variability of CFC-113, CCl4, and CFC-11 was rather small using the flask sampling technique, the in-situ method with its higher frequency, however, showed significantly larger variability arising from observing periodic emission episodes, which were highly correlated with wind direction and topography of the park.

Air Pollutants↗
PubMed2001

Dynamics of the 16O(e, e'p) reaction at high missing energies.

We measured the cross section and response functions for the quasielastic 16O(e,e'p) reaction for missing energies 25< or =E(m)< or =120 MeV at missing momenta P(m)< or =340 MeV/c. For 25<E(m)<50 MeV and P(m) approximately 60 MeV/c, the reaction is dominated by a single 1s(1/2) proton knockout. At larger P(m), the single-particle aspects are increasingly masked by more complicated processes. Calculations which include pion exchange currents, isobar currents, and short-range correlations account for the shape and the transversity, but for only half of the magnitude of the measured cross section.

Journal Article↗
PubMed2001

Epidemiology of Bartonella infection in domestic cats in France.

Blood samples were collected between February and June 1996 from a convenience sample of 436 domestic French cats living in Paris and its environs and were tested for Bartonella bacteremia and seropositivity. Seventy-two cats (16.5%) were Bartonella bacteremic, of which 36 cats (50%) were infected with Bartonella henselae type II (B.h. II) only, 15 cats (21%) were infected with Bartonella clarridgeiae (B.c.) only, and 11 cats (15%) were infected with B. henselae type I (B.h. I) only. Eight cats (11%) were co-infected with B. henselae and B. clarridgeiae (B.h. II/B.c.: five cats; B.h. I/B.c.: three cats). Two cats (2.8%) were concurrently bacteremic with B. henselae types I and II. Risk factors associated with bacteremia included ownership for <6months (prevalence ratio (PR)=1.80; 95% confidence interval (CI)=1.13-2.85), adoption from the pound or found as a stray (PR=1.67, 95% CI=1.05-2.65), and cohabitation with one or more cats (PR=1.60, 95% CI=1.01-2.53). Bartonella antibodies to either B. henselae or B. clarridgeiae were detected in 179 cats (41.1%). Risk factors associated with seroposivity paralleled those for bacteremia, except for lack of association with time of ownership. Prevalence ratios of bacteremic or seropositive cats increased with the number of cats per household (p=0.02). The lack of antibodies to B. henselae or B. clarridgeiae was highly predictive of the absence of bacteremia (predictive value of a negative test=97.3%). Multiple logistic regression analysis indicated that bacteremia, after adjustment for age and flea infestation, and positive serology, after adjustment for age, were associated with origin of adoption and number of cats in the household. Flea infestation was associated with positive serology.

Animals↗
PubMed2001

Polyoma virus infection after renal transplantation. Use of immunostaining as a guide to diagnosis.

BACKGROUND: Polyoma virus infection is characterized by lymphocytic interstitial infiltrate in the kidney, and it mimics acute rejection. The purpose of this study is to estimate renal allograft outcome with this infection and characterize the lymphocytic infiltrates in polyoma virus-infected renal allografts. METHODS: Patients who had polyoma virus inclusions in renal allograft biopsies were identified. Other viral inclusions were excluded by immunohistochemistry. The lymphocytic infiltrates of six cases of polyoma virus infection were compared with six cases of definite acute rejection by immunostaining for T and B cells. RESULTS: There were 10 cases of polyoma virus infections in renal transplant recipients. Immunosuppressants consisted of mycophenolate mofetil with tacrolimus in eight cases and mycophenolate mofetil with cyclosporine in two. The median time of diagnosis of polyoma virus infection after transplantation was 9.5 months, and the time to graft failure after the diagnosis was 4 months. Reduced allograft survival was seen in patients who had polyoma virus infection. Immunostaining for T and B cells revealed marked increase in the B cells (CD20) in renal allografts with polyoma virus infection of 21% (range, 5-40%) compared with 6% (range, 0-10%) in those with acute rejection (P=0.039). Reduced cytotoxic T cells (TIA-1: median, 7%; range, 2-15%) were seen in polyoma virus-infected allografts compared with 24% (range, 15-30%) in those patients who had acute rejection (P=0.0159). CONCLUSION: Irreversible graft failure is more prevalent with polyoma virus infection. Enhanced immunosuppressants with mycophenolate mofetil with tacrolimus may play a role in the development of this infection. An increase in CD20 and a decrease in cytotoxic T cells in allografts is characteristic of polyoma virus infection.

Acute Disease↗
PubMed2001

Polarization measurements in high-energy deuteron photodisintegration.

We present measurements of the recoil proton polarization for the d(gamma-->,p-->)n reaction at straight theta(c.m.) = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p(y) vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(gamma,p)n cross sections is not a result of perturbative QCD. These data should provide important tests of new nonperturbative calculations in the intermediate energy regime.

Journal Article↗
PubMed2001

Organization of human ACAT-2 gene and its cell-type-specific promoter activity.

Acyl-CoA:cholesterol acyltransferase (ACAT) plays important roles in cellular cholesterol homeostasis. Two ACAT genes exist in mammals. We report here the genomic organization of human ACAT-2 gene and analysis of its promoter activity in various cell lines. The human ACAT-2 gene spans over 18 kb and contains 15 exons. Three transcription start sites and one poly(A) site are identified by the 5'/3'-RACE. In addition, the human ACAT-2 gene is linked to the insulin-like growth factor binding protein 6 (IGFBP-6) gene in a head-to-tail manner with a small intergenic region of about 1.2 kb. The 5'-flanking region of human ACAT-2 gene contains many potential cis-acting elements for multiple transcriptional regulatory factors but lacks TATA and CCAAT boxes. Using promoter-luciferase reporter assays, we demonstrate the transcriptional activity of ACAT-2 gene promoter is high in Caco-2 cells, especially after these cells become postconfluent and behave as intestinal enterocytes.

Base Sequence↗
PubMed2001

Synergistic transcriptional activation of human Acyl-coenzyme A: cholesterol acyltransterase-1 gene by interferon-gamma and all-trans-retinoic acid THP-1 cells.

Acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme involved in cellular cholesterol homeostasis and in atherosclerotic foam cell formation. Human ACAT-1 gene contains two promoters (P1 and P7), each located in a different chromosome (1 and 7) (Li, B. L., Li, X. L., Duan, Z. J., Lee, O., Lin, S., Ma, Z. M., Chang, C. C., Yang, X. Y., Park, J. P., Mohandas, T. K., Noll, W., Chan, L., and Chang, T. Y. (1999) J. Biol Chem. 274, 11060-11071). Interferon-gamma (IFN-gamma), a cytokine that exerts many pro-atherosclerotic effects in vivo, causes up-regulation of ACAT-1 mRNA in human blood monocyte-derived macrophages and macrophage-like cells but not in other cell types. To examine the molecular nature of this observation, we identified within the ACAT-1 P1 promoter a 159-base pair core region. This region contains 4 Sp1 elements and an IFN-gamma activated sequence (GAS) that overlaps with the second Sp1 element. In the monocytic cell line THP-1 cell, the combination of IFN-gamma and all-trans-retinoic acid (a known differentiation agent) enhances the ACAT-1 P1 promoter but not the P7 promoter. Additional experiments showed that all-trans-retinoic acid causes large induction of the transcription factor STAT1, while IFN-gamma causes activation of STAT1 such that it binds to the GAS/Sp1 site in the ACAT-1 P1 promoter. Our work provides a molecular mechanism to account for the effect of IFN-gamma in causing transcriptional activation of ACAT-1 in macrophage-like cells.

Base Sequence↗
PubMed2001

p21 gene codon 31 arginine/serine polymorphism: non-association with endometriosis.

p21, an important regulator of the cell cycle, acts as a mediator of the growth-suppressing and -promoting functions of p53. We aimed to investigate the association between codon 31 polymorphisms of p21 gene and endometriosis. Women were divided into two groups: endometriosis (n = 102) and nonendometriosis (n = 119). The gene polymorphism for p21 codon 31 involved a base change from AGC to AGA and amino acid changes from serine (Ser) to arginine (Arg). Polymorphisms (Ser homozygotes, heterozygotes, Arg homozygotes) between both groups were detected and compared. Associations between the endometriosis and polymorphisms were evaluated. The results revealed that the distributions of different p21 polymorphisms in both groups were nonsignificantly different. The proportions of Ser homozygote/heterozygote/Arg homozygote in endometriosis and nonendometriois populations were 26.5/48.0/25.5% and 17.6/50.4/31.9%, respectively. We concluded the noncorrelation between the endometriosis and the p21 codon 31 polymorphism. p21 gene codon 31 arginine/serine polymorphism is not a useful marker for prediction of endometriosis susceptibility.

Arginine↗
PubMed2001

The significance of human papillomavirus viral load in prediction of histologic severity and size of squamous intraepithelial lesions of uterine cervix.

OBJECTIVES: Persistence of high-risk types of human papillomavirus (HPV) in cervical scrapes is responsible for the development, maintenance, and progression of squamous intraepithelial lesions (SILs). Previous studies of viral load and histologic severity have ended with controversial results. This study evaluated the relationships of HPV viral load with size and histologic severity of cervical lesions, which has not been reported previously. METHODS: By using Hybrid Capture II, DNA level of high-risk HPVs was determined in cervical scrapes and correlated with lesion size and histologic confirmation for 73 women referred for colposcopy. The lesion size was classified as nonvisible (n = 12), small (< or =2/5 of the 12x colposcopic visual filed, n = 36), and large (>2/5 of the 12x field, n = 25) lesions. The final disease status was categorized as high-grade SIL (HSIL)/squamous cell carcinoma (SCC) (designated HSIL+) (n = 32), low-grade SIL (LSIL) (n = 19), and no detectable SIL (n = 22). RESULTS: A distinct upward trend of high-risk HPV DNA levels paralleled increasing size and histologic severity of cervical lesions (P = 0.003 and 0.001, respectively). With respect to relative risk, women who had high viral load of HPV were at significantly greater risk for large lesion size (odds ratio [OR] = 5.3, 95% confidence interval [CI] = 1.1-24.9) and HSIL+ (OR = 35.0, 95% CI = 4.2-294.5). Of particular note, the risk of developing large lesion size and HSIL+ significantly increased with increasing viral load of HPV (P values for trend test were 0.008 and 0.0004, respectively). In contrast, there were no significant associations of trend in viral load with risk in small lesion size and LSIL. CONCLUSIONS: The present study revealed that the effect of HPV infection on SIL development is highly influenced by high viral load and highlighted a potential application of viral load testing in predicting the size and severity of lesions of the uterine cervix.

Adult↗