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Disease-free Subjects (disease-free + subject)

Distribution by Scientific Domains

Medical Sciences	50%

Selected Abstracts

Serum antioxidant micronutrient levels in oral lichen planus

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 5 2001
Toru Nagao
Abstract: The aim of this study was to elucidate any association between oral lichen planus (OLP) and serum antioxidant micronutrients by a population-based case-control study. A total of 9536 subjects were examined, and 62 (58 reticular, 4 atrophic and erosive) diagnosed with OLP at referral facilities were compared with four controls per case (n=248) selected among disease-free subjects matched for age and sex. Serum levels of micronutrients (retinol, ,-tocopherol, zeaxanthin/lutein and cryptoxanthin, lycopene, ,-carotene and ,-carotene) were estimated by the high performence liquid chromatography (HPLC) method. Among cases, mean serum retinol level (2.820±0.849 ,mol/l) was significantly higher compared with that of controls (2.562±0.735 ,mol/l) (P<0.05). No significant differences were noted in carotenoid levels examined in this study, except for a lower level of lycopene found in atrophic/erosive OLP cases. The results of this study suggest that low serum retinol or carotenoid levels are not risk factors for occurrence of lichen planus, and any specific benefits of antioxidant micronutrients cannot be claimed for this inflammatory disorder. [source]

On a Supplemented Case,Control Design

BIOMETRICS, Issue 2 2005
Ruth M. Pfeiffer
Summary The supplemented case,control design consists of a case,control sample and of an additional sample of disease-free subjects who arise from a given stratum of one of the measured exposures in the case,control study. The supplemental data might, for example, arise from a population survey conducted independently of the case,control study. This design improves precision of estimates of main effects and especially of joint exposures, particularly when joint exposures are uncommon and the prevalence of one of the exposures is low. We first present a pseudo-likelihood estimator (PLE) that is easy to compute. We further adapt two-phase design methods to find maximum likelihood estimates (MLEs) for the log odds ratios for this design and derive asymptotic variance estimators that appropriately account for the differences in sampling schemes of this design from that of the traditional two-phase design. As an illustration of our design we present a study that was conducted to assess the influence to joint exposure of hepatitis-B virus (HBV) and hepatitis-C virus (HCV) infection on the risk of hepatocellular carcinoma in data from Qidong County, Jiangsu Province, China. [source]

A Semiparametric Method for Analyzing Matched Case,Control Family Studies with a Continuous Outcome and Proband Sampling

BIOMETRICS, Issue 3 2004
Molin Wang
Summary We consider matched case,control familial studies which match a group of patients, called "case probands," with a group of disease-free subjects, called "control probands," using a set of family-level matching variables. Family members of each proband are then recruited into the study. Of interest here is the familial aggregation of the response variable and the effects of subject-specific covariates on the response. We propose an estimating equation approach to jointly estimate the main effects and intrafamilial correlations for matched family studies with a continuous outcome. Only knowledge of the first two joint moments of the response variable is required. The induced estimators for the main effects and intrafamilial correlations are consistent and asymptotically normally distributed. We apply the proposed method to sleep apnea data. A simulation study demonstrates the usefulness of our approach. [source]

Factors associated with elevated serum concentrations of anti-TPO antibodies in subjects with and without diffuse goitre.

CLINICAL ENDOCRINOLOGY, Issue 6 2007
American Cohort Study of Thyroid Cancer, Other Thyroid Diseases Following the Chornobyl Accident, Results from the Ukrainian
Summary Objectives, To examine factors associated with the prevalence of elevated anti-thyroid peroxidase antibodies (ATPO) among iodine-deficient adolescents and young adults and test whether associations vary according to the presence of diffuse goitre. Design, Subjects were members of the Ukrainian,American Cohort Study exposed to the Chornobyl accident whose 131I thyroid dose estimates were below 0·2 Gy. Measurements, The odds ratios (ORs) for ATPO above 60 U/ml were estimated using logistic regression models for a number of factors in the total population (N = 5133), and separately for thyroid disease-free subjects (N = 3875), those with diffuse goitre (N = 921), and diffuse goitre without autoimmune thyroiditis (AIT; N = 883). Results, Elevated ATPO was found in 9·9% of the total population and ORs were significantly higher in females, older individuals, those examined in earlier calendar years, residents of Kyiv and Chernihiv oblasts, subjects with a family history of thyroid disease, higher thyroid ultrasound volume, suppressed or elevated TSH, blood collection in March to May, very low thyroglobulin (Tg), and shorter serum storage time. When thyroid disease-free subjects and those with diffuse goitre were compared, there were few differences in antibody prevalence, and after excluding individuals with AIT, the only difference was an increased prevalence of elevated ATPO at low urinary iodine in those with goitre alone. Conclusions, Although a number of factors are associated with the prevalence of elevated ATPO in our study group, with the exception of urinary iodine these factors are independent of goitre, and differences between thyroid disease-free subjects and those with diffuse goitre are largely due to AIT. [source]