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Biomedical subjects

R S Lin

Publications and source records attributed to R S Lin.

At least 37 records · Page 2Linked to original sources
PubMed1999

Hyperinsulinemia and related atherosclerotic risk factors in the population at cardiovascular risk: a community-based study.

BACKGROUND: A population-based study was conducted in Taiwan to investigate the prevalence of insulin resistance and high serum insulin concentrations and their relationships with potential atherosclerotic risk factors. METHODS: We studied 2165 subjects, ages >35, from a community cohort. RESULTS: The distributions of fasting insulin were skewed to the right, with higher concentrations in women than in men. As age increased, insulin increased in women, but decreased in men. As fasting insulin concentrations increased, postloading insulin, glucose, blood pressure, body mass index, waist-to-hip ratio, total cholesterol, triglycerides, LDL-cholesterol, apoprotein B, plasminogen activator inhibitor 1, tissue plasminogen activator, and fibrinogen increased, but lipoprotein(a), HDL-cholesterol, and apoprotein A1 decreased. Multiple logistic regression showed that obesity, high LDL-cholesterol, and low HDL-cholesterol were significant predictors of hyperinsulinemic status. CONCLUSION: The study subjects with insulin resistance syndrome and related risk factors may be at risk for atherosclerosis, thrombosis, and other coronary heart diseases.

Age Factors↗
PubMed1999

Perinatal mortality in Taiwan.

Information on perinatal deaths was obtained from 310 women by collecting detailed obstetric histories dating from marriage to the start of the survey. These histories were compared to those of 688 age matched controls. Potential risk factors, levels and time trends of perinatal mortality in Taiwan were examined and factors underlying stillbirths and early neonatal deaths were also compared using conditional logistic regression analyses. A nearly 56% decline of the perinatal mortality rate during the 35 y, approximately, prior to the survey was observed. Risk of stillbirths was increased among those who had abused illegal drugs during pregnancy, those who reported that the pregnancy was unwanted and those with Thalassemia trait. Body mass index was log-linearly related with stillbirths, with higher body mass associated with higher risk. For early neonatal deaths, those mothers aged 19 y or less, those giving birth to either their first children or to their fifth or later child, those who had their first prenatal care visit after the first three months of pregnancy were associated with increased risk in the logistic model. Those with a birth interval of less than two years and those with less education were associated with increased risk in both perinatal death groups. While some of these factors have already been associated with perinatal deaths, others have not; the new associations provide clues to mechanisms by which the risk of death increases before or after delivery.

Age Factors↗
PubMed1998

Zinc is essential for binding of p56(lck) to CD4 and CD8alpha.

Binding of the protein tyrosine kinase p56(lck) to T-cell co-receptors CD4 and CD8alpha is necessary for T-lymphocyte development and activation. Association of p56(lck) with CD4 requires two conserved cysteine residues in the cytosolic domain of CD4 and two in the amino terminus of p56(lck), consistent with the notion that these four residues coordinate a single metal atom (1-5). Here we demonstrate that Zn2+ is essential for complex formation. In an in vitro binding reaction, Zn2+ mediates p56(lck) association with a glutathione S-transferase (GST) fusion protein containing the cytosolic domains of CD4 or CD8alpha; no other metals tested support binding. Treatment of preformed GST-CD4.p56(lck) dimers with the Zn2+ chelators 1,10-O-phenanthroline or 8-hydroxyquinoline-5-sulfonic acid results in dissociation of GST-CD4 from p56(lck), consistent with the finding of Huse et al. (5) that Zn2+ is contained within similar complexes. Furthermore, we show that, within live cells, CD4.p56(lck) and CD8alpha.p56(lck) interactions occur in a zinc-dependent fashion. Specifically, pretreatment of the human Jurkat T-cell line with membrane permeable zinc chelators disrupts CD4.p56(lck) complexes, and treatment of COS cells co-expressing CD8alpha and p56(lck) with such chelators likewise leads to dissociation of CD8alpha.p56(lck) complexes. CD4. p56(lck) and CD8alpha.p56(lck) represent the first examples of intracellular proteins that require zinc as a bridge for heterodimerization.

Animals↗
PubMed1998

Carboxy-terminal CFFL-sequence-specific monomeric protein geranylgeranyltransferase I from the eyes of the shrimp Penaeus japonicus.

Protein geranylgeranyltransferase I from the eyes of Penaeus japonicus geranylgeranylates predominantly the sequence CFFL and Drosophila-specific Ras1 carboxyl termini, with the sequence CKML, as well as mammalian-specific G gamma carboxyl termini, with the sequence CAIL, but not the protein farnesyltransferase-specific sequence CVLS. The purified protein geranylgeranyltransferase I from shrimp was evidenced by immunoblotting and polyacrylamide gel electrophoresis under denaturing conditions to consist of single subunit of Mr 66,000 +/- 500. Since the active protein geranylgeranyltransferase I was found to have a relative mass of 67,000 +/- 1,000, the purified enzyme was deduced to be a monomer. The enzyme had an optimal pH of 8.0 with 100 mM Tris as the buffer and a K(m) of 7 +/- 2 microM with the synthetic peptide KCFFL as the substrate. The enzyme was inhibited by Zn++ and Mg++ ions at micromolar concentrations.

Alkyl and Aryl Transferases↗
PubMed1998

Oral contraceptives and breast cancer risk in Taiwan, a country of low incidence of breast cancer and low use of oral contraceptives.

One hundred and seventy four (81% of all) pathologically confirmed new incident cases of female breast cancer identified from a medical center in Taipei from February, 1993 to June, 1994 were selected as the case group. Four hundred and fifty three inpatient controls who were without obstetric-gynecological, breast, or malignant diseases were individually matched for each case by age and date of admission. Information was obtained through direct interview and review of medical records. Conditional logistic regression was used to estimate the effects of each risk factor. After adjusting for education level, body mass index, age at menarche and first full-term pregnancy, parity, menopausal status and age at menopause, lifetime lactation, use of lactation inhibition hormones, and family history of breast cancer, breast cancer risk significantly elevated in use of OC before 25 years old and before 1971. In stratified analysis, significantly higher risk were found in OC use before 25 years old and in duration of use less than one year among post-menopausal subjects. Our results support the notion that OC use in early life for younger women and in early calendar years increase breast cancer risk.

Age Factors↗
PubMed1998

Urbanization and childhood leukaemia in Taiwan.

BACKGROUND: In the 1980s socioeconomic development was dramatically rapid in the urbanized municipalities of Taiwan due to a prospering economy. This study addressed the question: Could differences in the incidence of childhood leukaemia (age <15) be demonstrated between urban and rural communities in Taiwan between 1981 and 1990? METHODS: The log-linear regression model was used to assess the effects of age, level of urbanization, and calendar year on the variation of childhood leukaemia incidence rates between 1981 and 1990. RESULTS: Between 1981 and 1990, the overall incidence rate of childhood leukaemia increased by 20% (rate ratio (RR) = 1.2, 95% CI: 1.0-1.5). As compared to rural areas, metropolitan regions showed a significantly higher incidence rate during the study period (RR = 1.3, 95% CI: 1.1-1.6). This urban-rural difference was particularly notable among children <5 years old (RR = 1.5, 95% CI: 1.2-1.9). Dose-response analysis further indicated that risk of childhood leukaemia was monotonically associated with levels of urbanization. The significant gradient in the risk of childhood leukaemia with urbanization was contributed solely by children in the 0-4 years age group. CONCLUSIONS: We noticed a relationship between urbanization and risk of leukaemia in children. Because of a dramatic influx of people into metropolitan areas during the 1980s, our findings may have provided support for the putative association between 'population mixing' or 'population density' and risk of childhood leukaemia. Whether such association can be attributable to virus infection or other aetiologically related leukemogens warrants further investigations.

Adolescent↗
PubMed1998

Changes in platelet function and susceptibility of lipoproteins to oxidation associated with administration of aged garlic extract.

Garlic and some of its organosulfur components have been found to be potent inhibitors of platelet aggregation in vitro. Demonstration of their efficacy in vivo, however, especially when administered over extended periods, is sparse. We recently performed a 10-month study comparing the effect of aged garlic extract (AGE) with placebo on the lipid profiles of moderately hypercholesterolemic men. In the course of the intervention trial, we examined platelet functions and susceptibility of lipoproteins to oxidation in a subgroup of this study population. Study subjects supplemented with 7.2 AGE per day showed a significant reduction of epinephrine- and, to a lesser degree, collagen-induced platelet aggregation but failed to demonstrate an inhibition of adenosine diphosphate (ADP)-induced aggregation. Platelet adhesion to fibrinogen, measured in a laminar flow chamber at moderately high shear rate, was reduced by approximately 30% in subjects taking AGE compared with placebo supplement. A trend toward decreased susceptibility of lipoproteins to oxidation also was noted during AGE administration compared with the placebo period. We conclude that the beneficial effect of garlic preparations on lipids and blood pressure extends also to platelet function, thus providing a wider potential protection of the cardiovascular system.

Adult↗
PubMed1998

Risk of leukemia in children living near high-voltage transmission lines.

We conducted a study to examine the risk of leukemia between 1987 and 1992 among children living near high-voltage transmission lines (HVTL) in three urban districts of northern Taiwan. Twenty-eight cases of leukemia among some 120,696 children aged 14 years or less were reported to the national cancer registry between 1987 and 1992. Compared with children living in households more than 100 meters away from HVTL, children living in households less than 100 meters from HVTL experienced an essentially elevated risk of leukemia (7 versus 2.88, standardized incidence ratio [SIR] = 2.43, 95% confidence interval [CI] = 0.98-5.01). The elevated risk stands when compared with all children of Taiwan alternatively (7 versus 2.60, SIR = 2.69, 95% CI = 1.08-5.55). Such elevated risk was particularly noteworthy among children aged 5-9 years. The findings suggest that children living near HVTL tend to experience an elevated risk of leukemia. Further investigations are undoubtedly needed to unveil whether such tendency may have implied the putative association between exposure to elevated magnetic fields and risk of childhood leukemia.

Adolescent↗
PubMed1998

Sex difference in the mortality trends of acute myocardial infarction in Taiwan, 1974 to 1993.

The mortality patterns of coronary heart disease (CHD) vary among countries. Although the mortality rates from this disease are decreasing in the majority of developed nations, most developing countries are experiencing upward trends, especially among men. The mortality trends of acute myocardial infarction (AMI) in Taiwan have not been reported. The purpose of this study was to investigate the effects of age, chronicle period, and birth cohort on the AMI mortality rates using computerized vital statistics data from 1974 through 1993. Compared with the age-adjusted AMI mortality rates in 1974, the mortality rates in 1993 were 2.4 times higher for men and 2.2 times higher for women. When the log-linear Poisson model was used to assess age, birth cohort, and chronicle period simultaneously, women had no elevated relative risk of dying from AMI in different periods. The relative risk of dying from AMI increased 2.5 times for men in the 1955-1959 birth cohort compared with those in the 1890-1894 birth cohort, while the relative risk for females declined by 3.7 times for the corresponding birth cohorts. Based on birth cohort, the trends in mortality differ substantially between sexes in Taiwan. These results may help to generate hypotheses regarding the possible factors, prevention, and control of mortality from AMI in Taiwan.

Adult↗
PubMed1997

Residential exposure to 60-Hertz magnetic fields and adult cancers in Taiwan.

We conducted a case-control study, using matching on date of birth, sex, and date of diagnosis, in northern Taiwan to evaluate the risks of adult leukemia, brain tumors, and female breast cancers in relation to residential exposure to 60-Hertz (Hz) magnetic fields. Cases were persons with newly diagnosed cancers reported to the cancer registry between 1987 and 1992, and controls were persons with cancers sites other than those previously suspected of being associated with magnetic fields. Magnetic fields in the residences occupied by the study subjects at the time of diagnosis were estimated from high-voltage transmission lines. The results were based on the separate analysis of 870 cases of leukemia, 577 brain tumors, and 1,980 female breast cancers. We estimated the risk of leukemia among those exposed to magnetic fields of > 0.2 microtesla (microT), relative to the risk among those exposed to fields of < 0.1 microT; the odds ratio was 1.4 [95% confidence interval (CI) = 1.0-1.9]. For distance < 50 meters relative to > or = 100 meters, the relative risk was 2.0 (95% CI = 1.4-2.9). For brain tumors and female breast cancers, the odds ratios were close to unity.

Adult↗
PubMed1997

Age-period-cohort analysis of cervical cancer mortality in Taiwan, 1974-1992.

OBJECTIVES: To develop a hypothesis about the carcinogenesis of cervical cancer from a descriptive analysis. METHODS: The mortality data of cervical cancer were analyzed over the period from 1974 to 1992 among Taiwanese women using a log-linear Poisson model modified from the method of Osmond and Gardner to examine the effects of age, calendar period of death, and birth cohort on cervical cancer mortality. RESULTS: This age-period-cohort model provides a summary guide for interpretation of cancer mortality trends. According to this model, age was found to be the strongest factor predicting cervical cancer mortality. Women in 50-54 age group have 89.3-fold risk of cervical cancer compared to those in the 30-34 age group. The cohort effect is also of particular interest because the generation at greatest risk for cervical cancer is the one born between 1893 and 1938, and a dramatically declining trend is observed thereafter for 1938-1963 birth cohort. Interest has emerged about the increasing trend in recent cohorts (after 1963 birth cohort). However calendar time only has a slight effect in the APC analysis. The model also identified a possible role of female sex hormones as the age effect, promiscuous sexual activity as the period effect (promoter) and the change in reproductive behavior as the cohort effect (initiator). CONCLUSIONS: These results may help to develop a hypothesis of carcinogenesis of cervical cancer in Taiwan.

Adult↗
PubMed1996

Autoregressive age-period-cohort models.

Age-period-cohort analysis of vital data has received much attention recently, and it is already well known that the exact linear relation of the three time factors creates a non-identifiability problem. Previous studies have shown that the curvature terms of these factors are estimable but the linear trends are not. However, little attention has been paid to the possibility that the effects due to cohort and/or period might change through time stochastically rather than deterministically and hence display a stochastic trend. In this paper, we model the cohort effects as an AR(1) process and use lung cancer mortality data from 1966 to 1990 for males in Taiwan as an example. The parameters are identifiable in the proposed model and the estimates are found to be stable. However, the assumption made in the model should be carefully considered before using our methodology.

Adult↗
PubMed1996

Risk factors for cervical intraepithelial neoplasia in Taiwan.

A population-based case-control study was conducted in Taiwan between July 1991 and June 1994 to evaluate the significance between risk factors for cervical intraepithelial neoplasia (CIN) among Taiwanese women. Personal interviews were compiled with 288 histologically confirmed CIN who were matched by age to 576 randomly selected controls with normal cervical smears. Using logistic regression models to simultaneously evaluate the effects of multiple factors as predictors of CIN, we found that the strongest risk was associate with HPV infection (OR = 5.02). Other significant risks included husband's visiting prostitutes (OR = 2.56), four or more vaginal deliveries (OR = 2.01), two or more induced abortions (OR = 1.96), and multiple sex partners (OR = 1.87). A protective effect was also noted with the use of condoms (OR = 0.38). These data support the hypothesis that CIN is sexually transmitted in Taiwan's population and may have a viral etiology. Furthermore the results indicate the important role of the husband's visiting prostitutes and the nonuse of condoms as contributing factors in the high incidence rate for CIN in a population.

Case-Control Studies↗
PubMed1996

Epidemiology of cervical cancer in Taiwan.

Because the prevalence of several risk factors for cervical cancer, including sexual behavior, reproductive patterns, contraceptive use, and cigarette smoking, has changed significantly over time among Taiwanese women, it is of interest to analyze the impact of these trends on the incidence and mortality rates for this cancer during the decades between 1970 and 1990. The number of deaths from cervical cancer was obtained from the Taiwan Provincial Department of Health during the period from 1974 to 1992. Data of all incident cervical cancer cases from 1979 through 1990 obtained from the Taiwan Cancer Registry were also used for the analyses. The trends in the age-adjusted and age-specific rates were examined. Age, period, and cohort effects on the incidence and mortality rates were also examined, using age-period-cohort (APC) models. The age-adjusted mortality rate has been increasing since the 1970s, particularly in both the youngest group (20-29 years) and the oldest group (65 years and over). While the age-adjusted incidence rate decreased from 1979 to 1990, and decreases were apparent across all broad age groups, nevertheless, the incidence of adenocarcinoma was moderating during the same time period. The APC models disclosed a decreasing cohort effect for the mortality and incidence rates among women born after 1936. Decreasing incidence rates after menopause were more consistent with a hormonal effect than a cohort effect. Declining trends in cervical cancer incidence may be related to the screening practices which may have counteracted the increasing prevalence of several risk factors, although poor survival influenced the incidence/mortality differentials for cervical cancer. Continued surveillance is warranted; however, attention might be directed to the trends in cervical adenocarcinoma.

Adult↗
PubMed1996

Sociodemographic factors of Pap smear screening in Taiwan.

Substantial evidence exists that regular screening is effective in preventing cervical cancer. However, the existing services are underused by many women in Taiwan. To examine the effects of sociodemographic characteristics on the underuse of Papanicolaou (Pap) smear screening, from September to December 1993 we conducted a questionnaire interview on a sample of 4,400 women aged 20 years and older in Taipei city using multistage sampling with probability proportional to size. Our results indicate that 40% of the women sampled have never had a Pap smear and 86% have not had one in the past year. Age is the strongest factor affecting Pap smear use, particularly for women below age 30 and over the age of 65. In addition, women with lower levels of education, women who are not employed, never-married women and women who live outside the city tend to underuse Pap smear screening. These findings help indicate priority groups which should be targeted to increase screening and consequently reduce cervical cancer. Our data also provides a good baseline for comparison of rates of Pap smear screening by various sociodemographic factors in the future.

Adult↗
PubMed1996

Epidemiological appraisal of studies of residential exposure to power frequency magnetic fields and adult cancers.

OBJECTIVES: To appraise epidemiological evidence of the purported association between residential exposure to power frequency magnetic fields and adult cancers. METHODS: Literature review and epidemiological evaluation. RESULTS: Seven epidemiological studies have been conducted on the risk of cancer among adults in relation to residential exposure to power frequency magnetic fields. Leukaemia was positively associated with magnetic fields in three case-control studies. The other two case-control studies and two cohort studies did not show such a link. Brain tumours and breast cancer have rarely been examined by these studies. Based on the epidemiological results, the analysis of the role of chance and bias, and the criteria for causal inferences, it seems that the evidence is not strong enough to support the putative causal relation between residential exposure to magnetic fields and adult leukaemia, brain tumours, or breast cancer. Inadequate statistical power is far more a concern than selection bias, information bias, and confounding in interpreting the results from these studies, and in explaining inconsistencies between studies. CONCLUSIONS: Our reviews suggested that the only way to answer whether residential exposure to magnetic fields is capable of increasing the risks of adult cancers is to conduct more studies carefully avoiding methodological flaws, in particular small sample size. We also suggested that the risk of female breast cancer should be the object of additional investigations, and that future studies should attempt to include information on exposure to magnetic fields from workplaces as well as residential exposure to estimate the effects of overall exposure to magnetic fields.

Bias↗