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Biomedical subjects

C C Hsieh

Publications and source records attributed to C C Hsieh.

At least 235 records · Page 13Linked to original sources
PubMed1989

Association between dental caries prevalence and Streptococcus mutans among 13-year-old children.

The prevalence of caries associated prevalence with Streptococcus mutans in saliva and pooled plaque was investigated among 13-year-old Chinese children. In conjunction with saliva sampling simplified greatly by adopting the oral rinse method, an initial threshold value of 10(4) colony forming units (cfu) per ml of rinse was established on the basis of the S. mutans counts from 27 caries-free individuals. The results of the present study showed that, of the total 58 children, 67.3% had S. mutans counts above the threshold value in their saliva, and they developed significantly more decayed surfaces (D) and decayed, missing, filled surfaces (DMFS) than did the children below this value. The association between caries activity and S. mutans counts either in saliva or in pooled plaque samples was even stronger when only decayed surfaces were taken into account. In addition, the detection frequency of S. mutans (81.8%) was higher in saliva than in the pooled plaque samples (43.2%). This may demonstrate that saliva is more sensitive than dental plaque in predicting caries activity. The most prevalent biotypes of the S. mutans strains observed in this study were c and d. The results of this study indicate a significant association of S. mutans levels with caries prevalence. In the estimation of salivary S. mutans levels, the rinse method offered an easy and rapid identification for children with high caries risk and proved to be very practicable for epidemiological study on a larger scale.

Adolescent↗
PubMed1988

The effect of non-differential exposure misclassification on estimates of the attributable and prevented fraction.

This paper considers the effect of non-differential exposure misclassification on the population attributable fraction and the population prevented fraction as a function of the sensitivity and specificity of the exposure classification, the true relative risk, and the true prevalence of the exposure. Given a certain set of sensitivity, specificity, and prevalence of the exposure, the apparent attributable fraction is a constant proportion of the true attributable fraction regardless of the true relative risk. This observation does not hold for the apparent prevented fraction and the apparent relative risk, both of which vary with the true relative risk. For both the attributable and the prevented fraction, the sensitivity of the exposure classification has a greater influence on the magnitude of the bias than the specificity; also, the higher the prevalence of the exposure, the larger is the bias caused by the imperfect exposure classification.

Disease↗
PubMed1988

Risk factors associated with the prevalence of pulmonary tuberculosis among sanitary workers in Shanghai.

The association between potential risk factors and the prevalence of pulmonary tuberculosis was studied in Shanghai Bureau of Sanitation. The study identified a total of 202 cases among 30,289 subjects, and showed that smoking, in particular heavy smoking, had a strong association with tuberculosis after simultaneous adjustment for other factors. Using a multivariate binomial regression, the factors adjusted included the age, sex, history of contact, area of housing and type of work. The relative risk of heavy smokers compared with nonsmokers was 2.17 (95% confidence interval 1.29-3.63). The study showed that although males and old age were associated with a higher risk of tuberculosis than females and young age respectively, these differences were due to the smoking factor. The study also found that the risk of tuberculosis among the subjects with previous patient contacts was twice as high as that among the non-contacts.

Adult↗
PubMed1988

Therapeutic gain factors for fractionated radiation treatment of spontaneous murine tumors using fast neutrons, photons plus O2(1) or 3 ATA, or photons plus misonidazole.

Therapeutic gain factors (TGFs) have been determined for three spontaneous tumors of the C3H mouse treated by photons + normobaric oxygen (O2(1) ATA), photons + hyperbaric oxygen (O2 3 ATA), photons + misonidazole, or fast neutrons. The tumors were early generation isotransplants of spontaneous tumors: MCaIV, a mammary carcinoma; FSaII, a fibrosarcoma; and SCCVII, a squamous cell carcinoma. The tumors, transplanted to the right leg, were 6 mm at start of treatment. Normal tissue responses studied were acute reaction of normal skin (all treatment modalities) and LD50 following irradiation of the upper abdomen (in test of photons + O2 at 1 or 3 ATA). Thus both the tumor and normal tissues would be classified as "acute responding." All subject tissues were at congruent to 34.5-35 degrees C at irradiation. Treatments were based on d(25)Be or p(43)Be fast neutron beams, 60Co and 137Cs photon beams. Treatments were given in 5 or 15 equal doses in 5 days. For photon treatments, TGFs (air/O2 3 ATA) were substantially and significantly larger than 1 for all three tumor systems treated at small or large doses per fraction when related to skin or abdominal tissue responses. The TGFs (air/O2 1 ATA) were greater than 1 at small doses per fraction for MCaIV and FSaII for skin as the normal tissue; the TGFs for all three tumors and at all doses per fraction would be greater than 1 when related to upper abdominal tissues. TGFs (O2 1 ATA/O2 3 ATA) for photon irradiation greater than 1 were found only for SCCVII and that obtained for both large and small doses per fraction. Misonidazole achieved impressive TGFs (air/air + miso or air/O2 1 ATA + miso); the drug was tested only at 10-12 Gy/fraction and relative to skin. RBEs(FN) for the three tumors were lower at 1.5-2 Gy(FN)/fraction than at 5-6 Gy(FN)/fraction, i.e. the opposite to that reported for normal tissue (RBE increases with decreasing dose per fraction). A TGF (relative to skin reaction) greater than 1 for fast neutron therapy was found only for SCCVII when treated at large doses/fraction; this was true for air or O2 1 ATA conditions.

Animals↗
PubMed1987

Extrahepatic bile duct cancer and smoking, beverage consumption, past medical history, and oral-contraceptive use.

Information on potential causal factors in 67 patients with histologically confirmed cancer of the extrahepatic bile ducts was compared with that from 273 patients with other cancers. The control group did not include subjects with tobacco- or alcohol-related cancers. The study subjects were interviewed at 11 large hospitals in eastern Massachusetts and Rhode Island between 1975 and 1979. Among the patients with extrahepatic bile duct cancer, the male-female ratio was 1.5. The use of cigarettes was associated with decreased risk of extrahepatic bile duct cancer. The use of alcohol and coffee was not related to risk of extrahepatic bile duct cancer. Fewer patients than controls reported tea consumption. A statistically significant association between the use of oral contraceptives and extrahepatic bile duct cancer was observed among women under 60 years of age. Patients reported significantly higher frequencies of history of ulcerative colitis or diseases of the gallbladder.

Aged↗
PubMed1987

Death from uveal melanoma. Number of epithelioid cells and inverse SD of nucleolar area as prognostic factors.

Criteria for the Callender classification of uveal melanoma are subjective and lead to variations among observers of the same tumor. Two other measures for cell type-the number of epithelioid cells per high-power field (Epi/HPF) and the inverse SD of nucleolar area (ISDNA)-were evaluated as prognostic factors for survival following enucleation for uveal melanoma in 232 patients. Variables significantly related to the number of Epi/HPF were related to ISDNA. Larger, more anteriorly located tumors had a high number of Epi/HPF and a low ISDNA. The two measures were also correlated. Using Kaplan-Meier survival analysis, both measures were related to tumor deaths. Worse prognosis was associated with a higher number of Epi/HPF and a lower ISDNA. Considered together in Cox' proportional hazards analysis, both measures independently predicted outcome. Separately, each measure predicted uveal melanoma-related deaths, in combination with largest tumor dimension, invasion of tumor to the line of transection, and location of the anterior tumor margin. Although ISDNA is the more objective measure of cell type, its practicality compared with other measures of cell type must also be considered.

Adult↗
PubMed1987

Tonsillectomy and Hodgkin's disease: results from companion population-based studies.

The question of whether persons with a history of tonsillectomy are at increased risk of Hodgkin's disease (HD) in adulthood was evaluated in companion population-based case-control studies conducted in the eastern Massachusetts and the Detroit metropolitan areas. These studies compared the history of tonsillectomy among incident cases with that of all their siblings by matched analysis controlling for confounding by childhood social class, family size, and birth order. Among young adults (15-39 yr) there is substantial evidence that tonsillectomy is not a risk factor and the relative risk (RR) is 1.0 (95% confidence interval, 0.72-1.4). Among middle-aged persons (40-54 yr) the RR is not significantly elevated, 1.5 (0.67-3.3), and the direction of the association differs between the sexes, consistent with the hypothesis of no association. Among older persons, the RR is significantly elevated, 3.0 (1.3-6.9), but the data are sparse. On the basis of these data, it appears unlikely that prior tonsillectomy is a causal factor in the development of HD in young and middle-aged adulthood. Whether it is a risk factor for the malignancy occurring late in life is unclear.

Adolescent↗
PubMed1986

Physical activity, all-cause mortality, and longevity of college alumni.

We examined the physical activity and other life-style characteristics of 16,936 Harvard alumni, aged 35 to 74, for relations to rates of mortality from all causes and for influences on length of life. A total of 1413 alumni died during 12 to 16 years of follow-up (1962 to 1978). Exercise reported as walking, stair climbing, and sports play related inversely to total mortality, primarily to death due to cardiovascular or respiratory causes. Death rates declined steadily as energy expended on such activity increased from less than 500 to 3500 kcal per week, beyond which rates increased slightly. Rates were one quarter to one third lower among alumni expending 2000 or more kcal during exercise per week than among less active men. With or without consideration of hypertension, cigarette smoking, extremes or gains in body weight, or early parental death, alumni mortality rates were significantly lower among the physically active. Relative risks of death for individuals were highest among cigarette smokers and men with hypertension, and attributable risks in the community were highest among smokers and sedentary men. By the age of 80, the amount of additional life attributable to adequate exercise, as compared with sedentariness, was one to more than two years.

Adult↗
PubMed1986

Prognostic factors for metastasis following proton beam irradiation of uveal melanomas.

Prognostic indicators for the development of metastasis following proton beam irradiation of uveal melanomas were evaluated for 510 patients treated from 1975 to 1984. Thirty-three patients developed metastasis (6.5%) from 3 to 51 months following treatment. The primary site of metastasis was the liver in 28 cases (85%). Both demographic and clinical factors were considered. The three leading predictors of survival without metastasis after proton beam irradiation in order of importance were: (1) largest diameter of the tumor; (2) location of the anterior margin of the tumor; and (3) age at treatment. Worse prognosis was associated with largest tumor diameter greater than 15.0 mm, tumor involvement of the ciliary body and age at treatment older than 59 years.

Adult↗
PubMed1986

Visual outcome after proton beam irradiation of uveal melanoma.

Prognostic factors for visual loss following proton irradiation of uveal melanoma were evaluated for 440 eyes treated from 1975 to 1984, with visual acuity 20/200 or better before treatment. Analysis involved Kaplan-Meier survival curves and Cox proportional hazards analysis with visual outcome defined as worse than 20/200. Prognostic factors were tumor height: rate ratio (ratio of rate of visual loss for one category of the variable relative to the rate of visual loss for a reference category of that variable) of 5.26 (95% confidence interval, 2.66-10.39) for tumors greater than 5 mm compared to tumors 3.0 mm or less in height; distance of tumor from the optic disc and fovea: rate ratio 2.59 (1.63-4.11) for tumors 2DD or less from both the optic disc and fovea compared to those greater than 2 DD from these structures. Also predictive of visual loss were tumor location close to disc only, or close to fovea only, macular detachment, worse pretreatment vision, and higher radiation doses delivered to both the disc and fovea, and lens. Regression analysis using a visual acuity scale gave similar results.

Adolescent↗
PubMed1986

Adolescent suicidal and self-destructive behavior. Results of an intervention study.

This study evaluates an intervention program designed to reduce suicidal, self-destructive behavior among high-risk adolescents aged 13- to 17 years. The intervention combined a program of community education and direct service to youth who had required emergency care for self-inflicted injuries. The intervention program was effective in increasing subjects' compliance with medical regimen. To a lesser degree, the intervention also facilitated early help seeking among adolescents with suicidal thoughts and appeared to diminish slightly the overall occurrence of emergency room admissions for suicidal behaviors. However, the intervention program had no demonstrable effect on the occurrence of repeat suicidal episodes.

Adolescent↗
PubMed1986

Power calculation in matched case-referent studies. Application and accuracy of the asymptotic power function.

Although the asymptotic power function for matched case-referent (case-control) studies has been given, it is not widely applied. One reason for this is that the parameters in the power function do not correspond directly to the usual description of the research situation. When designing a matched case-referent study, the potentially available relevant information concerns the joint distribution of the determinant and matching variate, and the illness rate in relation to those factors, in the study base. Application of the asymptotic power function using these inputs is described. The asymptotic power function is then assessed by use of the Monte Carlo method and is found to be accurate. An example of the application of the asymptotic power function is given.

Epidemiologic Methods↗
PubMed1986

Myoelectric analysis of the paraspinal musculature in relation to automobile driving.

In this study, the myoelectric activity of 12 paraspinal muscles of ten men aged 18-24 was recorded to examine the effects of backrest inclination and lumbar support in relation to driving. In total, 24 test conditions were evaluated over a 3.5-hour period in a single day. These tests were then repeated, changing the sequence over the next 4 days. The results indicate a complex interaction between the thoracic and lumbar regions of the back with the lowest myoelectric activity position of 120 degrees backrest inclination, 5 cm of lumbar support, and 13.5-18.5 degrees of seat inclination. Electromyogramatic (EMG) evidence of fatigue was not identified over a 3.5-hour period. The generally low levels of EMG activity and, presumably, disc pressure present in any seating position suggest that the paraspinal muscle activity may not play the predominant role in disc herniation as it relates to automobile driving.

Adolescent↗