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Biomedical subjects

D Y Lin

Publications and source records attributed to D Y Lin.

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

Leisure-time physical activity and the risk of primary cardiac arrest.

BACKGROUND: Because the risks of sudden cardiac death and myocardial infarction are transiently increased during acute bouts of high-intensity activity, it is an important question from the public health perspective whether regular participation in moderate-intensity activity confers overall protection from sudden cardiac death. PARTICIPANTS AND METHODS: We used data from a population-based case-control study to assess the associations of regular high-intensity and moderate-intensity leisure-time physical activity with primary cardiac arrest. Cases were patients with primary cardiac arrest, aged 25 to 74 years, attended by paramedics between 1988 and 1994 in King County, Washington (n = 333). Controls were randomly identified from the same community (n = 503), matched for age and sex. All case patients and controls were free of prior clinical heart disease, major comorbidity, and self-reported poor health. Spouses of case patients and controls were interviewed to assess participation in 15 high-intensity and 6 moderate-intensity physical activities during the prior year. RESULTS: Compared with subjects who performed none of the activities, the odds ratio for primary cardiac arrest from matched analyses was 0.34 (95% confidence interval, 0.13-0.89) among subjects who performed only gardening activities for more than 60 minutes per week; 0.27 (95% confidence interval, 0.11-0.67) among subjects who walked for exercise for more than 60 minutes per week; and 0.34 (95% confidence interval, 0.16-0.75) among subjects who engaged in any high-intensity activities, after adjustment for age, smoking, education, diabetes, hypertension, and health status. CONCLUSIONS: The results suggest that regular participation in moderate-intensity activities, such as walking and gardening, are associated with a reduced risk of PCA and support current exercise recommendations.

Adult↗
PubMed1999

The RARgamma selective agonist CD437 inhibits gastric cell growth through the mechanism of apoptosis.

Retinoids are differentiation-inducing agents that exhibit multiple functions. Their activities are mediated through interaction with nuclear retinoic acid receptors (RAR) and retinoid X receptors (RXR). We have investigated the activities of synthetic retinoids on the growth of five gastric cancer cell lines. The effects of agonists selective for RARalpha, RARbeta and RARgamma (AM580, CD2019 and CD437, respectively) on cell growth were determined, in comparison to all-trans retinoic acid, by measuring total cellular DNA. AM580 and CD2019 had little or no effect on the growth of all five cell lines. In contrast, the RARgamma agonist CD437 inhibited cell growth up to 90-99% in both retinoic acid sensitive and resistant gastric cancer cells at a concentration of 1 microM. The growth suppression caused by CD437 was accompanied by the induction of apoptosis as judged by morphological criteria and DNA ladder formation. However, the extent of CD437-induced growth suppression was not correlated with RARgamma mRNA levels, which indicates that CD437 induces apoptosis in gastric cancer cells via an RARgamma independent pathway.

Amnion↗
PubMed1999

Etiology of sporadic acute viral hepatitis in Taiwan: the role of hepatitis C virus, hepatitis E virus and GB virus-C/hepatitis G virus in an endemic area of hepatitis A and B.

The etiology of sporadic acute hepatitis was studied in 334 consecutive patients from Taiwan (237 men and 97 women, aged 16-81 years), with emphasis on the role of hepatitis C virus (HCV), hepatitis E virus (HEV), and GB virus-C/hepatitis G virus (GBV-C/HGV) in acute non-A, non-B (NANB) hepatitis and in HBsAg carriers with superimposed acute hepatitis. According to the conventional diagnostic criteria, there were 12 cases (3.6%) of acute hepatitis A, 17 cases (5.1%) of acute hepatitis B, 128 cases (38.3%) of acute NANB hepatitis, and 177 cases (53.0%) of acute hepatitis in HBsAg carriers (those who were HBsAg positive but IgM anti-HBc negative). Among 128 cases of acute NANB hepatitis, 70 (54.7%) had acute hepatitis C (HCV RNA positive), 5 (3.9%) had acute hepatitis E (IgM anti-HEV positive), and the other 53 (41.4%) were presumably acute hepatitis non-A-E. The prevalence of acute hepatitis A, B, E, and non-A-E showed no significant sex difference, whereas acute hepatitis C was significantly more prevalent in females. The prevalence of acute hepatitis A and B decreased and that of acute hepatitis C increased significantly with increasing age. In contrast, acute hepatitis E and non-A-E showed no significant age predominance. Of 177 HBsAg carriers with acute hepatitis, 64 (36.1%) demonstrated non-B hepatotropic virus superinfection, with HCV being the most common (60.9%), followed by hepatitis D, E, and A viruses, and the other 55 (31.1%) and 58 (32.8%) were presumed to have acute exacerbation of chronic hepatitis B or superimposed acute hepatitis non-A-E, respectively. Serum GBV-C/HGV RNA was detected in 3-4% of acute hepatitis non-A-E cases, suggesting its limited role in these cases.

Acute Disease↗
PubMed1999

The role of digital fundus photography in diabetic retinopathy screening. Digital Diabetic Screening Group (DDSG).

PURPOSE: The role of digital monochromatic nonmydriatic fundus photography as an adjunct in the diagnosis of diabetic retinopathy is evaluated. METHODS: 197 patients were sequentially evaluated by three different techniques: dilated ophthalmoscopy by an experienced ophthalmologist, performance of 7 standard color mydriatic stereo fields, and a single digital monochromatic nonmydriatic image incorporating the disc and macula. Stereo color photographs served as the reference standard and were compared to either ophthalmoscopy performed by a physician, or a single digital photograph transmitted electronically to a reading site and evaluated by a trained non-physician grader. Sensitivity and specificity of the three methods were compared. The decision as to whether or not to refer to an ophthalmologist for potential treatment (Kaiser modified ETDRS level > 21) was then chosen for analysis. RESULTS: A single nonmydriatic monochromatic digital photograph appeared equivalent to standard color photography and more sensitive than mydriatic ophthalmoscopy in the detection of diabetic retinopathy in this patient population. Sensitivity of digital photography compared with color photography was 78%, and the specificity 86% contrasted with comparable ratios of 34% and 100% for ophthalmoscopy versus color photography. No patient identified by ophthalmoscopy alone for referral based on retinopathy level of > 21 would have been missed by a single digital monochromatic photographic image. CONCLUSION: A single nonmydriatic monochromatic wide field digital photograph of the disc and macula in diabetic patients is a sensitive and cost-effective means for detecting diabetic retinopathy in high-risk populations.

Allied Health Personnel↗
PubMed1999

Poisson regression with missing durations of exposure.

In this paper, we develop Poisson-type regression methods that require the durations of exposure be measured only on a possibly nonrandom subset of the cohort members. These methods can be used to make inferences about the incidence density during exposure as well as the ratio of incidence densities during exposure versus not during exposure. Numerical studies demonstrate that the proposed methods yield reliable results in practical settings. We describe an application to a population-based case-control study assessing the transient increase in the risk of primary cardiac arrest during leisure-time physical activity.

Biometry↗
PubMed1999

Estimation of population size based on additive hazards models for continuous-time recapture experiments.

We use the semiparametric additive hazards model to formulate the effects of individual covariates on the capture rates in the continuous-time capture-recapture experiment, and then construct a Horvitz-Thompson-type estimator for the unknown population size. The resulting estimator is consistent and asymptotically normal with an easily estimated variance. Simulation studies show that the asymptotic approximations are adequate for practical use when the average capture probabilities exceed .5. Ignoring covariates would underestimate the population size and the coverage probability is poor. A wildlife example is provided.

Animals↗
PubMed1999

Identity of a novel swine hepatitis E virus in Taiwan forming a monophyletic group with Taiwan isolates of human hepatitis E virus.

Recently, we found that more than 10% of the cases of acute non-A, non-B, non-C hepatitis in Taiwan were caused by a novel strain of hepatitis E virus (HEV). Since none of these patients had a history of travel to areas where HEV is endemic, the source of transmission remains unclear. The recent discovery of a swine HEV in herd pigs in the United States has led us to speculate that HEV may also circulate in herd pigs in Taiwan and may serve as a reservoir for HEV in Taiwan. Of 275 herd pigs obtained from 10 pig farms in Taiwan, 102 (37%) were seropositive for serum anti-HEV immunoglobulin G (IgG). A 185-bp genomic sequence within the ORF-2 of the HEV genome was amplified and cloned from serum samples of an anti-HEV positive pig and subsequently from serum samples of a patient with acute hepatitis E. Sequence comparison revealed that the swine and human isolates of HEV share 97.3% identity. Phylogenetic analyses further showed that the Taiwan swine and human isolates of HEV form a distinct branch divergent from all other known strains of HEV, including the U.S. swine strain. To examine the potential risk of cross-species transmission of swine HEV to humans, the seroprevalences of anti-HEV IgG in 30 swine handlers, 20 pork dealers, and 50 control subjects were assessed and were found to be 26.7, 15, and 8%, respectively (for swine handlers versus controls, P = 0.048). Our findings may help provide an understanding of the modes of HEV transmission and may also raise potential public health concerns for HEV zoonosis.

Animals↗
PubMed1999

Methods for analyzing health care utilization and costs.

Important questions about health care are often addressed by studying health care utilization. Utilization data have several characteristics that make them a challenge to analyze. In this paper we discuss sources of information, the statistical properties of utilization data, common analytic methods including the two-part model, and some newly available statistical methods including the generalized linear model. We also address issues of study design and new methods for dealing with censored data. Examples are presented.

Data Interpretation, Statistical↗
PubMed1999

Time-dependent covariates in the Cox proportional-hazards regression model.

The Cox proportional-hazards regression model has achieved widespread use in the analysis of time-to-event data with censoring and covariates. The covariates may change their values over time. This article discusses the use of such time-dependent covariates, which offer additional opportunities but must be used with caution. The interrelationships between the outcome and variable over time can lead to bias unless the relationships are well understood. The form of a time-dependent covariate is much more complex than in Cox models with fixed (non-time-dependent) covariates. It involves constructing a function of time. Further, the model does not have some of the properties of the fixed-covariate model; it cannot usually be used to predict the survival (time-to-event) curve over time. The estimated probability of an event over time is not related to the hazard function in the usual fashion. An appendix summarizes the mathematics of time-dependent covariates.

Humans↗
PubMed1999

Indocyanine green clearance test in non-cirrhotic hepatitis patients: a comparison and analysis between conventional blood sampling method and Finger Piece Monitoring method.

BACKGROUND: The indocyanine green (ICG) Finger Piece Monitor system is a non-invasive method for measuring blood ICG concentrations for the evaluation of hepatic function. This study was conducted to determine its clinical usefulness in non-cirrhotic patients. METHODS: Traditional liver function tests, alpha-fetoprotein, prothrombin time, and ICG clearance tests, by both blood sampling method and Finger Piece Monitoring method were performed simultaneously on 56 non-cirrhotic hepatitis patients. The plasma clearance rate (K) and 15-minute retention ratio (R15) of ICG were analyzed and compared with traditional liver function test results. RESULTS: The clearance rate using the Finger Piece Monitoring method was slightly lower than that of the blood sampling method (9.16 +/- 5.00%/min vs. 11.24 +/- 3.56%/min) with good correlation (r = 0.721, p = 0.0003). The 15-minute retention ratio using the Finger Piece Monitoring method showed better correlation with blood sampling method (32.83 +/- 23.99% vs. 28.49 +/- 23.74%, r = 0.944, p = 0.0002). Analysis between traditional laboratory tests and fR15 revealed a higher fR15 value in patients with bilirubin-total-T > or = 3 mg/dl (49.71 +/- 26.22% vs. 22.23 +/- 13.48%), alpha-fetoprotein > or = 100 ng/ml (61.96 +/- 15.84% vs. 28.52 +/- 21.74%), and PT prolongation > or = 3 sec (71.46 +/- 16.80% vs. 29.03 +/- 21.06%). CONCLUSION: There is a good correlation between the conventional blood sampling method and the ICG Finger Piece Monitoring system method. The ICG Finger Monitoring system provides an alternative for traditional laboratory tests for the evaluation of hepatic dysfunction in hepatitis patients.

Adult↗
PubMed1999

Percutaneous ethanol injection therapy in 47 cirrhotic patients with hepatocellular carcinoma 5 cm or less: a long-term result.

To elucidate the long-term results of percutaneous ethanol injection (PEI) for hepatocellular carcinoma (HCC), 47 cirrhotic patients with HCC < or = 5 cm after PEI were analysed. Thirty-two of the patients were male. The age range was 37-68 years. Thirty-nine patients were seropositive either for hepatitis B surface antigen or antihepatitis C virus antibody. There were a total of 61 tumours, including solitary tumours in 35 patients, double tumours in 10 and triple tumours in two. The size of the main tumour was < or = 3 cm in 29 patients and more than 3 cm in 18 patients. Seventeen, 27 and three patients were in Child's class A, B and C respectively; 5-10 ml 95% ethanol was injected into the tumour every three to seven days until the echogenicity of the tumour changed to a hyperechoic or heterogeneous one. A booster PEI was given in 34 (56%) lesions with viable tumour, which was detected by dynamic computed tomography. The one, two, three and four-year survival rates were 85%, 75%, 61% and 39% respectively for all patients. Good liver reserve significantly improved the survival rate (p < 0.01, Child's class A and B vs Child's class C). The one, two, three and four-year recurrence rates were 24%, 55%, 69% and 79% for all patients. HCC recurred more frequently in patients with multiple tumours (p < 0.02).

Adult↗
PubMed1998

Assessing the sensitivity of regression results to unmeasured confounders in observational studies.

This paper presents a general approach for assessing the sensitivity of the point and interval estimates of the primary exposure effect in an observational study to the residual confounding effects of unmeasured variable after adjusting for measured covariates. The proposed method assumes that the true exposure effect can be represented in a regression model that includes the exposure indicator as well as the measured and unmeasured confounders. One can use the corresponding reduced model that omits the unmeasured confounder to make statistical inferences about the true exposure effect by specifying the distributions of the unmeasured confounder in the exposed and unexposed groups along with the effects of the unmeasured confounder on the outcome variable. Under certain conditions, there exists a simple algebraic relationship between the true exposure effect in the full model and the apparent exposure effect in the reduced model. One can then estimate the true exposure effect by making a simple adjustment to the point and interval estimates of the apparent exposure effect obtained from standard software or published reports. The proposed method handles both binary response and censored survival time data, accommodates any study design, and allows the unmeasured confounder to be discrete or normally distributed. We describe applications on two major medical studies.

Appetite Depressants↗
PubMed1997

Estimating the proportion of treatment effect explained by a surrogate marker.

In this paper, we measure the extent to which a biological marker is a surrogate endpoint for a clinical event by the proportional reduction in the regression coefficient for the treatment indicator due to the inclusion of the marker in the Cox regression model. We estimate this proportion by applying the partial likelihood function to two Cox models postulated on the same failure time variable. We show that the resultant estimator is asymptotically normal with a simple variance estimator. One can construct confidence intervals for the proportion by using the direct normal approximation to the point estimator or by using Fieller's theorem. Extensive simulation studies demonstrate that the proposed methods are appropriate for practical use. We provide applications to HIV/AIDS clinical trials.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Prospective study of hepatocellular carcinoma and liver cirrhosis in asymptomatic chronic hepatitis B virus carriers.

The authors conducted a study to assess the importance of underlying liver cirrhosis in the development of hepatocellular carcinoma (HCC) and the multifactorial etiology of liver cirrhosis in chronic carriers of hepatitis B virus (HBV). Between November 1980 and May 1990, all male hepatitis B surface antigen (HBsAg) carriers who routinely attended a clinic for asymptomatic HBV carriers at the Liver Unit of Chang-Gung Memorial Hospital, Taiwan, were enrolled in the study (n = 1,506). The authors used this cohort to investigate prospectively for liver cirrhosis and HCC at 6-month intervals by means of ultrasonography and clinical assessment. There were 16 incident cases of HCC and 89 cases of liver cirrhosis (78 of whom were detected during follow-up) identified after an average follow-up of 7.1 years. Subclinical liver cirrhosis diagnosed by ultrasonography was significantly associated with the risk for HCC (multivariate-adjusted relative risk (RR) = 11.8, 95% confidence interval (CI) 3.9-35.8). By multivariate analysis, the significant risk factors found for liver cirrhosis in HBsAg carriers were age, hepatitis B e antigen (HBeAg) carrier status, chronic hepatitis manifested by sustained elevated serum aminotransferase levels for > or = 6 months, cigarette smoking, non-A blood types, and low educational levels. Habitual alcohol drinking was not independently related to liver cirrhosis. However, the risk of liver cirrhosis associated with smoking was more striking among drinkers than nondrinkers (> or = 20 cigarettes/day vs. nonsmokers: drinkers, RR = 9.3, 95% CI 1.1-78.8; nondrinkers, RR = 1.85, 95% CI 0.98-3.51), which suggests a possible modification effect of alcohol drinking on the liver cirrhosis risk of cigarette smoking. The authors observed synergistic effects on liver cirrhosis development for cigarette smoking with HBeAg carrier status and chronic hepatitis.

Adult↗
PubMed1997

Non-parametric inference for cumulative incidence functions in competing risks studies.

In the competing risks problem, a useful quantity is the cumulative incidence function, which is the probability of occurrence by time t for a particular type of failure in the presence of other risks. The estimator of this function as given by Kalbfleisch and Prentice is consistent, and, properly normalized, converges weakly to a zero-mean Gaussian process with a covariance function for which a consistent estimator is provided. A resampling technique is developed to approximate the distribution of this process, which enables one to construct confidence bands for the cumulative incidence curve over the entire time span of interest and to perform Kolmogorov-Smirnov type tests for comparing two such curves. An AIDS example is provided.

AIDS-Related Opportunistic Infections↗