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Biomedical subjects

H J Chang

Publications and source records attributed to H J Chang.

65 records · Page 4Linked to original sources
PubMed1990

Accuracy of screening for cervical cancer in Taiwan, 1974-1984.

The cervical cancer screening program in Taiwan was carried out in two phases. This study attempted to estimate the specificity, predictive value, and cancer detection rate of screening for cervical cancer in Taiwan, 1974-1984. They were 99.30%, 46.28%, and 0.60% respectively for Phase I screening (1974-1978) and 99.44%, 50.14% and 0.57% respectively for Phase II screening (1979-1984). It was found consistently that the suspicious rate for women screened for the first time in Taiwan was around 1.30%. Some issues of laboratory errors (or technical errors) in the screening were discussed by screening year and by geographic area respectively. A problem in the cytologic laboratory which produced some technical errors resulting in high false negative results was identified. In order to correct the above laboratory errors, an intensive and obligatory training program including lecture and laboratory sessions was set up and a quality control protocol was established, in which 10% random samples were selected and re-read by the supervisor, and consistency was established and monitored. Besides, subjectivity of cytopathologists was also considered and discussed. Standardization and quality control of the cytopathological laboratory is the most important issue in the accuracy of screening for cervical cancer.

Chi-Square Distribution↗
PubMed1990

Epidemiology of cervical cancer in the screened population in Taiwan, 1979-1984.

This study was based on the screening data of April 1979-June 1984 to provide descriptive epidemiology of cervical cancer in Taiwan. During the 63 months, 175,823 women were screened and 1988 (1.13%) suspicious cases were found. The predictive value of a positive test was 50.14% and the specificity of the screening test was 99.44%. The estimated cancer rate among the screened population was 0.57%. The ratio of carcinoma in situ to invasive carcinoma was 1.91. The mean ages were 37.5 years for screened population, 44.1 years for suspects, 46.3 years for cancer cases (44.1 years for carcinoma in situ and 50.8 years for invasive carcinoma), 57.3 years for cervical cancer deaths in 1981 and 58.1 years for uterine cancer deaths in 1981. Univariate descriptive analyses on all women screened revealed the following variables to be positively associated (p less than 0.05) with suspicious Pap smears and cancer confirmed cases: age, number of years married, number of full-term deliveries, number of abortions/miscarriages, and abnormal vaginal bleeding. Negative associations were found with age at first marriage, education level, previous Pap smear and use of condom for contraception. Suspicious rates (but not detected cancer rates) were significantly higher for those women who themselves or whose husbands worked in mining, salt production, fishery or agriculture occupations. They were lowest for those (self or husband) employed in civil service, teaching, military service or police. By residence, suspicious rates were highest for those residing in the most urbanized areas (cities) and lowest for those in the second most urbanized areas (country cities). Thus urbanization level was not significantly involved. Other risk variables reported in the literature such as family history of uterine and other cancers were not significantly associated with either the suspicious or the cancer rate in this study.

Adult↗
PubMed1990

[A feasibility study on teaching evaluation system in medical education].

The purpose of this study is to develop an evaluation instrument with high feasibility and acceptability, and to quantify the outcome of evaluation, in order to set up an efficient evaluation system. Teaching evaluation with questionnaire by students has been carried out in National Yang-Ming Medical College for two years. With the support of both teachers and students, the system has been established and conducted on a regular basis. The most important purpose of evaluation is to improve the quality of teaching. During the two academic years (Sep. 1986-June 1988) of the program, the overall response rate was 44.5%, the Department of Nursing had the highest response rate, followed by Dentistry, Medicine-Post Graduate, Medical Technology, and Medicine. Taking into consideration of the year and the class size, the regression analysis found that higher year or smaller size of the class had better response rate. The response rates dropped significantly after the first academic year regardless of department or year. A total of 23 classes were included in the evaluation program and 99 courses were evaluated. All questions in the questionnaire used a 0 to 4 ordinal scale, in which 0 (improvement needed) was the low end and 4 (excellent) the high end. The mean score of the seven questions of teaching evaluation was 2.47. As a whole, the students were satisfied with the teaching. As to the categories of courses, clinical courses had better mean score than basic medical courses, and basic medical courses had better mean score than common required courses. To evaluate the effectiveness of the teaching, students' achievement was used as the outcome variable. The most important predictive variable was the method of instruction, followed by the content of lecture such as degree of difficulty of the lecture and cognitiveness of the contents. The above 3 variables explained 76% of the variation of the students' achievement. However, the significant of teachers' speech, performance and attitude were not so influential. Analysis based on the characteristics of the teachers (sex, age, position, and teaching experience), the characteristics of students (department and year), teaching environments (time and place), and the 3 categories of courses (clinical, basic medical and common required courses) showed that all the above variables only explained less then 10% of the variation of the students' achievement.

Education, Medical↗
PubMed1990

The phenotype of 45,X/46,XY mosaicism: an analysis of 92 prenatally diagnosed cases.

We undertook an international survey of prenatally diagnosed 45,X/46,XY mosaicism to ascertain the phenotypic spectrum of this condition. Ninety-two cases were obtained by means of a questionnaire sent to over 730 cytogenetic laboratories. Seventy-six cases (75 males and 1 female) had physical examinations after delivery or termination of pregnancy. Among these, there were four significant genital anomalies: three hypospadias and one female with clitoromegaly. Gonadal histology was abnormal in three (27%) of 11 cases, all of whom had normal male external genitalia. Other anomalies were noted in five cases: one cystic hygroma in a male, two cardiac anomalies, one spina bifida with multiple other defects, and one intrauterine growth retardation. There was no relationship between the percent mosaicism and the presence or degree of abnormalities. We conclude that 95% of 45,X/46,XY fetuses will have normal male genitalia, although there will also be a significant risk (27%) for abnormal gonadal histology. Long-term follow-up studies of prenatally diagnosed cases of 45,X/46,XY mosaicism are needed to study, without ascertainment bias, stature, pubertal development, tumor risk, and fertility.

Female↗
PubMed1990

Physician variation in anticoagulating patients with atrial fibrillation. Dartmouth Primary Care COOP Project.

We investigated variations in the oral anticoagulant treatment of atrial fibrillation by physicians in three specialties: family physicians (or general practitioners), general internists, and cardiologists. Results showed general agreement in the anticoagulation decision regarding patients with either mitral valve disease or a history of chronic alcohol abuse, but substantial disagreement in other categories of patients. Estimations of the risk of embolization and risk of hemorrhage differed widely among all physicians, cardiologists generally rating the embolization risks lower than the other physicians. A physician's treatment decision was strongly related to the relative risk of embolism vs hemorrhage derived for each case. A relationship between physician specialty and treatment decision was also demonstrated, with cardiologists least likely, and family practitioners most likely, to institute anticoagulation in nonrheumatic patients with atrial fibrillation. The reason for this variation appears to be differences in the estimated risk of systemic embolism.

Aged↗
PubMed1989

Risk assessment of diet in a community-based study.

A community-based screening for colorectal cancer targeted to all residents over 30 in Luh-Guu Town in Taiwan was conducted in mid-1986 and diet history was taken at the same time to examine the relationship between diet and screening positives of Hemoccult Test. Using dichotomous screening result as the outcome variable, we divided the exposure variable, diet history, into 3 categories: (A) meat less than vegetable, (B) meat = vegetable, and (C) meat greater than vegetable. The control variables in this study were age, sex, and upper G.-I bleeding history. The bivariate analysis with Chisquare test and the multivariable analysis with logistic regression were applied respectively. Although upper G-I bleeding was a protective factor for screening positive (OR = 0.5732 and 95% C.I = 0.34-0.96), it was not a confounder in this study. The main effect of age and sex were not correlated with screening positive. The interaction terms up to 3-factor were not significant. Based on the best fitted model in this study, those taking more meat than vegetable have a 1.74 times higher risk for screening positive of colorectal cancer than those taking less meat than vegetable (OR (3.1) = 1.74, 95% C.I. = 1.09-2.80). However the 95% C.I. for OR (2,1) and OR (3,2) included the null value OR = 1 [OR (2,1) = 1.30, 95% C.I = 0.93-1.82 and OR (3,2) = 1.34, 95% C.I = 0.84-2.08)]. High vegetable together with low meat diet is recommended.

Colorectal Neoplasms↗
PubMed1988

Prediction of local cooling rates and cell survival during the freezing of a cylindrical specimen.

A finite element numerical model was implemented to simulate the freezing process of an aqueous salt solution in a cylindrical container. Local cooling rates within the container were computed for several defined cooling protocols applied at the boundary. Characteristic cell survival signatures were used to predict the associated local survival rates throughout the system. These calculations show that there are two definite time domains during a typical freezing process: (1) while the surface temperature is changing and (2) after the surface temperature reaches a constant storage value. The calculations also show significant spatial variations in the local cooling rates within the container and considerable local deviation from the volumetric average survival for various simulated freezing protocols.

Animals↗
PubMed1981

Baseline and sodium arsenite-induced sister chromatid exchanges in cultured lymphocytes from patients with Blackfoot disease and healthy persons.

A significantly higher frequency of baseline sister chromatid exchange (SCE) was found in the cultured lymphocytes of 13 Blackfoot disease patients (BFP) in comparison with that of healthy persons (HP). Twelve of these BFP consumed well water containing a high concentration of arsenic for 15 years or longer and had switched to drinking tap water 12 years before the time of this study. Sodium arsenite was found to be effective in increasing the SCE frequency and delaying the cell growth of the lymphocytes from both BFP and HP. However, the SCE increment induced by sodium arsenite as well as the progression of the cell divisions in the cultured lymphocytes showed no significant difference between BFP and HP.

Adult↗
PubMedDate not supplied

Risk factors for nasopharyngeal carcinoma.

In an effort to assess the relative importance of various risk factors of nasopharyngeal carcinoma (NPC), which includes antibodies to Epstein-Barr virus capsid antigen (anti-VCA) and early antigen (anti-EA) as well as other environmental factors, a multivariate logistic regression method was applied to analyze previously collected data from an epidemiologic study on 343 cases with NPC and 1017 neighborhood controls. Anti-VCA and anti-EA titers were found significantly associated with NPC. The relative risk increased with the increase of antibody titers. Individuals who smoked 30 or more cigarettes per day had more than 3.4 times higher risk than those who never smoked, while no increase in the risk was observed for those smoking less than 20 cigarettes per day and ex-smokers. Use of herb drugs, working under poor ventilation and nativity were also found to increase the NPC risk. In cases other than smoking 20 or more cigarettes per day and the frequent use of herb drugs, the synergistic interaction was not observed. In addition, male NPC individuals and Mainland Chinese were found to have relatively lower antibody titers as compared with female individuals or native Taiwanese.

Antibodies, Viral↗