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C C Chang

Publications and source records attributed to C C Chang.

At least 73 records · Page 4Linked to original sources
PubMed2001

Training nu-support vector classifiers: theory and algorithms.

The nu-support vector machine (nu-SVM) for classification proposed by Schölkopf, Smola, Williamson, and Bartlett (2000) has the advantage of using a parameter nu on controlling the number of support vectors. In this article, we investigate the relation between nu-SVM and C-SVM in detail. We show that in general they are two different problems with the same optimal solution set. Hence, we may expect that many numerical aspects of solving them are similar. However, compared to regular C-SVM, the formulation of nu-SVM is more complicated, so up to now there have been no effective methods for solving large-scale nu-SVM. We propose a decomposition method for nu-SVM that is competitive with existing methods for C-SVM. We also discuss the behavior of nu-SVM by some numerical experiments.

Journal Article↗
PubMed2001

Decreased CD10 expression in grade III and in interfollicular infiltrates of follicular lymphomas.

CD10 expression in various grades and interfollicular infiltrates of follicular lymphoma (FL) has not been well documented. Immunohistochemical staining for CD10 (clone 56C6) was performed on paraffin-embedded tissue from 26 cases of classic FL. Negative or weak expression of CD10 was more frequent in grade III (5/6 [83%]) than in grade I FLs (3/15 [20%]). CD10+ interfollicular infiltrates were present in 16 cases. Six (38%) of 16 cases showed that CD10 expression was strong or moderate in follicular areas but weak or negative in interfollicular infiltrates. Our results suggest that CD10 expression is frequently weak to negative in grade III and in interfollicular infiltrates of FLs. Therefore, lack of CD10 expression on small specimens, such as from needle core biopsy or fine-needle aspiration, does not preclude the possibility of a diagnosis of FL. Furthermore, lack of CD10 expression in diffuse large B-cell lymphoma does not exclude the possibility that the neoplastic lymphocytes are of follicle center cell origin.

Adult↗
PubMed2001

Role of stem cells and gap junctional intercellular communication in human carcinogenesis.

Epidemiological data, experimental animal bioassays, studies of in vitro neoplastic transformation, and molecular oncology studies have implicated a multistage, multimechanism process in human carcinogenesis. From animal carcinogenesis studies, the operational concept of a single normal cell being irreversibly altered during the first step in carcinogenesis is called initiation. The subsequent interruptible or reversible clonal expansion of these initiated cells by non-cytotoxic mitogenic stimuli, compensatory hyperplasia due to cell death by necrosis, or inhibition of apoptosis is referred to as the promotion phase. Last, when one of these clonally expanded, initiated cells acquires sufficient genetic/epigenetic alterations to become neoplastically transformed and acquire the phenotypes of promoter independence, invasiveness and metastasis, it is referred to as the progression step of carcinogenesis. This report hypothesizes that the single normal cell that is initiated is a pluripotent stem cell. By assuming that the normal pluripotent stem cell is immortal and becomes mortal when induced to terminally differentiate, initiation would be viewed as the irreversible process by which a stable alteration in a finite number of proto-oncogenes and/or tumor suppressor genes could block terminal differentiation or "mortalization". Promotion would involve the reversible inhibition of gap junctional intercellular communication (GJIC) and while progression occurs with the stable down-regulation of GJIC.

Animals↗
PubMed2001

A human breast epithelial cell type with stem cell characteristics as target cells for carcinogenesis.

Two types of human breast epithelial cells (HBEC) have been characterized. In contrast to Type II HBEC, which express basal epithelial cell phenotypes, Type I HBEC are deficient in gap junctional intercellular communication and are capable of anchorage-independent growth and of expressing luminal epithelial cell markers, estrogen receptors, and stem cell characteristics (i.e. the ability to differentiate into other cell types and to form budding/ductal organoids on Matrigel). A comparative study of these two types of cells has revealed a high susceptibility of Type I HBEC to immortalization by SV40 large T antigen, although both types of cells are equally capable of acquiring an extended life span (bypassing senescence) after transfection with SV40. The immortalization was accompanied by elevation of a low level of telomerase activity in the parental cells after mid-passage ( approximately 60 cumulative population doubling levels). Thus HBEC do have a low level of telomerase activity, and Type I HBEC with stem cell characteristics are more susceptible to telomerase activation and immortalization, a mechanism which might qualify them as target cells for breast carcinogenesis. The immortalized Type I HBEC can be converted to highly tumorigenic cells by further treatment with X rays (2 Gy x 2) and transfection with a mutated ERBB2 (also known as NEU) oncogene, resulting in the expression of p185(ERBB2) which is tyrosine phosphorylated.

Animals↗
PubMed2001

Primary tumour volume delineation in nasopharyngeal carcinoma and correlation with 1997 AJCC tumour stage classification.

OBJECTIVE: To investigate the variability in primary tumour volume in nasopharyngeal carcinoma and compare it with the tumour staging of the 1997 American Joint Committee on Cancer. DESIGN: Prospective study. SETTING: Tertiary care centre. METHOD: A series of 33 newly diagnosed patients who were treated with high-dose radiotherapy participated in the study. MAIN OUTCOME MEASURES: Using computed tomographic scans, primary tumour volumes were measured using the summation-of-areas technique, and the variability in tumour volume was determined. The Mann-Whitney test was used for statistical analysis. RESULTS: A large variation in primary tumour volume was observed, especially in advanced-stage cases. CONCLUSIONS: Nasopharyngeal carcinoma shows considerable variability in primary tumour volume. Incorporation of primary tumour volume may lead to further refinement of the 1997 tumour staging system.

Adult↗
PubMed2001

Shedding of porcine reproductive and respiratory syndrome virus in mammary gland secretions of sows.

OBJECTIVE: To document shedding of porcine reproductive and respiratory syndrome (PRRS) virus in mammary gland secretions of experimentally inoculated sows, to evaluate effects of vaccination during gestation on virus shedding during the subsequent lactation, and to evaluate shedding of PRRS virus in milk of sows in commercial herds. ANIMALS: 6 sows seronegative for PRRS virus were used for experiment 1, and 2 sows were retained for experiment 2. For experiment 3, 202 sows in commercial herds were used. PROCEDURE: In experiment 1, 2 sows were inoculated with PRRS virus, 2 sows were vaccinated with modified-live PRRS virus vaccine, and 2 sows served as control pigs. Mammary gland secretions were assayed for PRRS virus. In experiment 2, pregnant vaccinated sows from experiment 1 were vaccinated with another modified-live PRRS virus vaccine. Mammary gland secretions were assayed in the same manner as for experiment 1. For experiment 3, milk collected from 202 sows in commercial herds was assayed for PRRS virus. RESULTS: In experiment 1, PRRS virus was detected in mammary gland secretions of both vaccinated and 1 of 2 virus-inoculated sows. In experiment 2, virus was not detected in samples from either vaccinated sow. In experiment 3, all samples yielded negative results. CONCLUSIONS AND CLINICAL RELEVANCE: Naïve sows inoculated late in gestation shed PRRS virus in mammary secretions. Previous vaccination appeared to prevent shedding during the subsequent lactation. Results for samples obtained from sows in commercial herds suggested that virus shedding in mammary gland secretions of such sows is uncommon.

Animals↗
PubMed2001

Prevalence of Bartonella species and 16s rRNA gene types of Bartonella henselae from domestic cats in Thailand.

Prevalence of Bartonella infection among 275 cats in 9 sites from 4 geographical regions (northern area: Chiang Mai; central area: Kanchanaburi, Ratchaburi, and Bangkok; northeastern area: Khon Kaen, Roi Et, Ubon Ratcharthani, and Nakhonratchasima; southern area: Songkhla) of Thailand was investigated. Overall, Bartonella species were isolated from 27.6% (76 of 275) of the cats. The isolation rate varied from 12.8% (5 of 39) in Songkhla (southern area) to 50.0% (26 of 52) in Khon Kaen (northeastern area). Bartonella henselae and B. clarridgeiae were isolated from 82.9% (63 of 76) and 11.8% (9 of 76) of the Bartonella-positive cats, respectively. Coinfection with both species was found in 5.3% (4 of 76) of the bacteremic cats. Of the 67 bacteremic cats from which B. henselae was isolated, 48 (71.6%) and 13 (19.4%) were infected with only Type I and Type II, respectively. Coinfection with both types was observed in 9.0% (6 of 67) of the B. henselae-positive cats. To our knowledge, this is the first report on the presence of Bartonella infection in domestic cats from Thailand, which constitute a large reservoir of Bartonella infection in this country.

Animals↗
PubMed2001

Mixed-effects models for the evaluation of long-term trends in exposure levels with an example from the nickel industry.

Longitudinal studies play an important role in evaluating the temporal behavior of occupational exposures. The purpose of this paper is to examine certain features of longitudinal data and to present a general conceptual framework by which these features may be taken into account so that statistically valid inferences can be made. Statistical methods that rely on the application of mixed-effects models are proposed for evaluating long-term trends in exposures to workplace contaminants. The mixed-effects model presented herein has fixed effects for trend components and random effects for workers, job groups, buildings and plants. These models differ from conventional techniques in that they accommodate hierarchically structured data and account for the correlation that may arise due to the clustering of measurements based on when and where the data were collected. While primary interest is focused on determining the magnitude of trends in exposure levels over time, the model also provides information about the magnitude of the sources of variation associated with different groupings of workers. Application of the mixed-effects model is illustrated with a large database of shift-long personal exposure measurements collected on workers exposed to nickel aerosols in the nickel-producing industry.

Cluster Analysis↗
PubMed2001

Induction of acyl-coenzyme A:cholesterol acyltransferase-1 by 1,25-dihydroxyvitamin D(3) or 9-cis-retinoic acid in undifferentiated THP-1 cells.

We have previously shown that acyl-coenzyme A: cholesterol acyltransferase-1 (ACAT-1) protein content increases significantly during the human monocyte-macrophage differentiation process. To gain further insight, we used undifferentiated human monocytic THP-1 cells as a model system with which to examine whether ACAT-1 mRNA and protein content can be increased by treating cells with 1,25-dihydroxyvitamin D(3) [1,25-(OH)(2)D(3)] or with 9-cis-retinoic acid (9-cis-RA), two agents known to upregulate the expression of various genes during the monocyte-macrophage differentiation process. Immunoblot analysis with anti-human ACAT-1 antibodies revealed that ACAT-1 protein was increased by 2.6-fold, using 1,25-(OH)(2)D(3) at a physiological concentration (100 pM). ACAT-1 protein was also increased when using 9-cis-RA, but only at relatively high concentrations (0.1;-1 microM). Northern blot analysis revealed that among the four ACAT-1 mRNA transcripts (2.8, 3.6, 4.2, and 7.0 kb) examined, only the 2.8- and 3.6-kb transcripts were selectively increased. On the basis of enzyme assays in vitro, ACAT activity was increased 3.0-fold by using 100 nM 1,25-(OH)(2)D(3), and 1.8-fold by using 1 microM 9-cis-RA. Together, our results suggest that 1,25-(OH)(3) participates in ACAT-1 gene expression during the monocyte-macrophage differentiation process.

Alitretinoin↗
PubMed2001

Prenatal diagnosis of oculocutaneous albinism two mutations located at the same allele.

A pregnant woman accepted amniocentesis on account of the previous birth of type 1 oculocutaneous albinism (OCA1). PCR revealed that the fetus had two mutations (862delTT, Arg 299His). The father had one missense mutation (Arg 299Ser) and the mother had the same mutations as the fetus. Two mutations of the fetus located at the same allele were suspected. Postpartal follow-up confirmed his carrier status. For recessive disorders, faced with a fetus with two mutations, the importance of performing segregation analysis of mutation on both parents is emphasized. This could exclude two mutations located at the same allele and prevent the unnecessary termination of a fetus with carrier status.

Adult↗
PubMed2001

Antigenic specificity of anti-neutrophil cytoplasmic antibody.

PURPOSE: To determine the antigens recognized by sera containing classic anti-neutrophil cytoplasmic antibodies (c-ANCAs) and perinuclear anti-neutrophil cytoplasmic antibodies (p-ANCAs). METHODS: A total of 160 serum samples (all from a reference laboratory) that were originally collected from different clinics for ANCA tests were examined for c-ANCA and p-ANCA by indirect immunofluorescence (IIF). All positive sera were further tested for reactivity to proteinase 3 (PR3), myeloperoxidase (MPO), lactoferrin (LF), and lysozyme (LZ) by enzyme-linked immunosorbent assay (ELISA). In addition, sera from 110 patients with systemic lupus erythematosus (SLE), 51 patients with rheumatoid arthritis (RA), and 40 healthy subjects were also tested for reactivity to these antigens. RESULTS: HF detected ANCA in 81 (51%) of the 160 clinical serum samples. Of these 81 serum samples, 21 (26%) contained c-ANCA and 60 (74%) contained p-ANCA. P-ANCA was more commonly found in antinuclear antibody (ANA)-positive sera than in ANA-negative sera (p < 0.01). Of the 21 serum samples positive for c-ANCA, 12 (57%) reacted to PR3, four (19%) to LF, four (19%) to LZ, and three (14%) to MPO on ELISA. By contrast, of the 60 sera positive for p-ANCA, 15 (25%) reacted to MPO, 13 (22%) to PR3, eight (13%) to LF, and four (7%) to LZ. The prevalence of ANCA specificities in serum samples from SLE patients were as follows: anti-PR3, 0%; anti-MPO, 1%; anti-LF, 27%; and anti-LZ, 29%. The prevalence of ANCA specificities in serum samples from RA patients were as follows: anti-PR3, 6%; anti-MPO, 2%; anti-LF, 8%; anti-LZ, 4%. CONCLUSION: Sera positive for c-ANCA and p-ANCA reacted to diverse cytoplasmic antigens from neutrophils. P-ANCA was found in 55% of ANA-positive serum samples. LF and LZ were most commonly found in serum samples from patients with SLE.

Antibodies, Antineutrophil Cytoplasmic↗
PubMed2001

Legionnaires' disease in a patient with rheumatoid arthritis.

A 62-year-old male with rheumatoid arthritis (RA) who was taking nonsteroid anti-inflammatory drug for controlling synovitis developed a flare of his arthritis, hepatitis, and pneumonia due to infection with Legionella pneumophila serotype 1. Adult respiratory distress syndrome (ARDS) occurred following the development of pneumonia. After the introduction of erythromycin and ventilator support with positive end expiratory pressure (PEEP), his condition stabilized and he recovered gradually. We suggest that L. pneumophila should be considered early in the differential diagnosis of pneumonia in RA patients due to their immunocompromised status.

Arthritis, Rheumatoid↗
PubMed2001

Thickened pituitary stalk with central diabetes insipidus: report of three cases.

Diabetes insipidus of central origin usually results from lesions in the hypothalamic neurohypophyseal system. Lymphocytic infundibuloneurohypophysitis is an uncommon cause. Cases of lymphocytic infundibuloneurohypophysitis with thickening of the pituitary stalk and enlargement of the neurohypophysis with no hyperintense signal in the posterior pituitary have been reported. Reported cases presenting with isolated thickening of the pituitary stalk are very rare. We report three such cases, one in a nulliparous woman and the other two in men. Magnetic resonance (MR) imaging in these patients revealed isolated thickening of the pituitary stalk, loss of the hyperintense signal of the posterior pituitary, and an adenohypophysis of normal size. All cases had abnormal nodular infundibular enlargement. One male patient had hypogonadism; the other patients showed no sign of adenohypophyseal deficiency on stimulation test. Serial follow-up MR imaging revealed that all three patients had persistent thickening of the pituitary stalk. Diabetes insipidus was controlled by the administration of desmopressin acetate in all patients.

Adult↗
PubMed2001

Effect of methylglyoxal on mouse embryogenesis.

BACKGROUND: Methylglyoxal (MG), a highly active and mutagenetic compound, has been found widely in a variety of foods and beverages. We investigated the effect of MG on mouse embryo development in-vitro. METHODS: Two-cell mouse embryos were divided into six groups according to the MG concentration in the culture medium: Group 1 (control group). 0 mM; Group 2, 10(-4) mM; Group 3, 10(-3) mM; Group 4, 10(-2) mM; Group 5, 10(-1) mM; Group 6, 1 mM. Embryo development and cleavage were compared every day for 5 days. RESULTS: The percentages of embryos reaching blastocyst/hatching stages were as follows: Group 1, 66.8%/34.2%; Group 2, 67.9%/38.7%; Group 3, 56.2%/31.5%; Group 4, 39.4%/14.1%; Group 5, 11.4%/10.2%; Group 6, 0%/0%. Higher MG concentrations (> or = 10(-2) mM) were associated with morphological aberrations and blocked development of embryos. CONCLUSION: The cutoff value of MG concentration on the mouse embryo development in-vitro is 10(-2) mM. An increased risk of embryotoxicity occurs with MG concentrations > or = 10(-2) mM in vitro. There were no significant effects on the growth rate at MG concentrations of 10(-3) and 10(-4) mM.

Animals↗
PubMed2001

Relationship of duodenal ulcer recurrence to gastric metaplasia of the duodenal mucosa and duodenal bulb deformity.

BACKGROUND AND PURPOSE: This study investigated changes in the severity of gastric metaplasia (GM) of the duodenal mucosa before and after ulcer healing and Helicobacter pylori eradication. It also investigated whether deformity of the duodenal bulb affects the severity of GM and the likelihood of ulcer recurrence. METHODS: Eleven patients were consecutively enrolled in this study. They all had duodenal ulcer(s) and H. pylori infection, for which they had received anti-H. pylori triple therapy during the active ulcer stage, and had all undergone serial endoscopic examinations during both the active ulcer and scarring ulcer stages, and at 1 year after ulcer healing. Duodenal biopsies were obtained at each endoscopy to identify the severity of GM. Duodenal ulcers were divided into three types by bulbar shape and GM was classified into four grades of severity. RESULTS: All 11 patients had increased GM severity just after ulcer healing. The 1-year follow-up study revealed that the GM was unchanged in six of eight patients with grade 3 GM severity at the scarring stage, while in the other two it regressed to grade 1 or 2; these two patients suffered ulcer recurrence. A markedly deformed bulb (type III) was found in three patients, of whom two had ulcer recurrence. CONCLUSION: Two characteristic conditions were found in patients with duodenal ulcer recurrence after H. pylori eradication: a markedly deformed bulb with grade 3 GM at the scarring stage, and a change in GM from high to low grade at or around the previous ulcer site after ulcer healing.

Adult↗
PubMed2001

In vitro study of ultrasound based real-time tracking of renal stones for shock wave lithotripsy: part 1.

PURPOSE: We developed a real-time tracking system for renal stones that decreases the number of shock waves and treatment time of shock wave lithotripsy. MATERIALS AND METHODS: Ultrasound images were analyzed to identify the renal stones. A computer software module for ultrasound image processing was developed to monitor stone location instantaneously. Another computer software module controlled generator movement in real time for tracking the stone. We used 13 ultrasound stone trajectories recorded from patients to test the system in vitro. Two tests were established to verify tracking system reliability. One test focused on improvement in the coincidence ratio, which denotes the matching extent of the stone within the effective focal area. The other test focused on improvement in the efficiency ratio, that is a decrease in the number of shocks for stone fragmentation. For each recorded stone trajectory 2 experiments were done under tracking and nontracking conditions. RESULTS: The average coincidence and efficiency ratios plus or minus standard deviation were 79.6% +/- 9.8% and 45.0% +/- 12.7% without tracking, and 97.0% +/- 3.0% and 85.5 +/- 6.8% with tracking, respectively. All tests were statistically significant (paired t test p <0.01). CONCLUSIONS: An ultrasound based real-time tracking system proved to be significantly helpful for in vitro lithotripsy. It appears that the tracking system may greatly decrease the number of shocks and treatment time for renal stones.

Follow-Up Studies↗
PubMed2001

Doppler study of the fetal middle cerebral artery at three locations: preliminary report.

BACKGROUND: Middle cerebral artery (MCA) detection is useful in monitoring fetal well-being. Knowledge of Doppler flow velocity of the fetal MCA may assist in prenatal diagnosis and management of complicated pregnancies. The aim of this study was to compare the pulsatility index (PI) and resistance index (RI) of the MCA at different locations throughout pregnancy. METHODS: Uncomplicated singleton pregnancies accepted Doppler surveys of the bilateral MCA. PI and RI values of the proximal, middle, and distal 1/3 of the MCA were measured. The gestation periods for Doppler surveys were (1) 15 to 19 weeks; (2) 20 to 24 weeks; (3) 25 to 29 weeks; (4) 30 to 34 weeks; and (5) 35 to 40 weeks. The MCA flows at different locations and at different gestational aged were compared. RESULTS: There were 21 patients included. Average PI/RI values of the proximal, middle and distal MCA were 1.62/0.80, 1.69/0.81, and 1.71/0.83, which were non-significantly different. The PI/RI values of MCA in each gestational phase were also non-significantly different: (1) 1.70/0.84; (2) 1.72/0.82; (3) 1.68/0.83; (4) 1.65/0.81; (5) 1.62/0.77. CONCLUSIONS: The PI and RI values of the proximal MCA were non-significantly lower than those of middle and distal MCA. Middle MCA could represent three locations of MCA. A trend of lower PI/RI values with advancing gestation was noted.

Adult↗