Biomedical subjects

L Wijnberg

Publications and source records attributed to L Wijnberg.

9 recordsLinked to original sources

PubMed2001

Exposure to extremely low frequency magnetic fields among working women and homemakers.

Given concerns with potential health effects of exposure to magnetic fields, the goal of this study was to examine the magnitude and sources of occupational and residential exposure to extremely low frequency (primarily 60 Hz) magnetic fields among women. Exposure to 60 Hz magnetic fields was surveyed among cases and controls recruited for a study of breast cancer in 25 counties in North Carolina. The 273 women who participated wore an integrating personal magnetic-field exposure meter (AMEX 3-D) that measured their time-weighted average (TWA) exposure. A questionnaire was administered to determine the duration and frequency of electric appliance and machinery use. The geometric mean (GM) of the TWA exposure for employed women was 0.138 microT (range 0.022-3.636 microT) and for homemakers 0.113 microT (range 0.022-0.403 microT). Women working in manufacturing and industrial facilities had the highest exposure (GM 0.265 microT, range 0.054-3.436 microT), while nurses and health technicians (GM 0.134 microT, range 0.032-0.285 microT) and teachers and school administrators (GM 0.099 microT, range 0.035-0.673 microT) had the lowest exposures. Job titles, unless very limited in scope and/or environment, self-reported information about equipment use, potential exposure sources, time, and distance were not good predictors of magnetic-field exposure. Furthermore, the results show that occupations previously observed to have increased risk of breast cancer, such as teachers, nurses, administrative support, and housewives, did not have elevated average magnetic field exposures. Therefore, it is questionable whether exposure to power frequency magnetic fields is the cause of the increased breast cancer risk seen in these occupations.

Adult↗

PubMed2000

Trends in plasma cholesterol levels in the atherosclerosis risk in communities (ARIC) study.

BACKGROUND: Data from the Atherosclerosis Risk in Communities (ARIC) cohort study were examined both cross-sectionally and intraindividually to confirm recent findings from population-based studies showing a decline in total cholesterol (TC) levels in the United States. METHODS: For the cross-sectional analysis, mean plasma TC levels from 15,792 participants aged 45-64 at baseline visit, and who were selected randomly from four U.S. communities, were examined for each year covered by the first cohort visit (1987, 1988, and 1989). Ninety-three percent of the cohort participants returned for the follow-up visit (1990, 1991, and 1992), and were included in the assessment of intraindividual TC trends. RESULTS: Both mean TC and prevalence of hypercholesterolemia (defined as plasma cholesterol concentration >/=240 mg/dl) consistently declined over the 3 years covered by visit 1 for all age-gender-race groups. For 1987, 1988, and 1989, mean TC values (mg/dl) were, respectively, 220.3, 216.7, and 214.1 (annual average change, -1.4%, P < 0.001). For these same years, hypercholesterolemia prevalence rates were 30. 0, 27.8, and 25.3% (annual average change, -7.8%, P < 0.001). The mean plasma TC also decreased within individuals between the two visits across race, gender, and age decade categories. With the exception of black men, this decline was more marked for older than younger subjects, but no consistent differences were seen between the racial groups. However, in whites, decreases were greater for men than for women. Expected results were seen when these changes were correlated with changes in cardiovascular risk factors between the two visits. CONCLUSION: The current study results are consistent with those of previous studies, and confirm the notion that preventive programs appear to be effective in reducing mean population TC levels.

Arteriosclerosis↗

PubMed1996

Self-reported transient ischemic attack and stroke symptoms: methods and baseline prevalence. The ARIC Study, 1987-1989.

As part of the Atherosclerosis Risk in Communities (ARIC) Study assessment of the etiology and sequelae of atherosclerosis, a standardized questionnaire on transient ischemic attack (TIA) and nonfatal stroke and a computerized diagnostic algorithm simulating clinical reasoning were developed and tested at the four ARIC field centers: Forsyth County, North Carolina; Minneapolis, Minnesota; Jackson, Mississippi; and Washington County, Maryland. The diagnostic algorithm used participant responses to a series of questions about six neurologic trigger symptoms to identify symptoms of TIA or stroke and their vascular distribution. Among 12,205 ARIO participants reporting their lifetime occurrence of one or more symptoms probably due to cerebrovascular causes, nearly half (47%) reported the sudden onset of at least one symptom sometime prior to their ARIC examination. Of those with at least one symptom, only 12.9% were classified by the computer algorithm as having symptoms of TIA or stroke. Dizziness/loss of balance was the most frequently reported symptom (36%); 1.2% of these persons were classified by the algorithm as having a TIA/stroke event. Positive symptoms of speech dysfunction were classified most often (77.%) as being symptoms of TIA or stroke. Symptoms suggesting TIA were reported more frequently than symptoms suggesting stroke by both sexes. TIA or stroke-like phenomena were more frequent (p < 0.001) in females (7%) than in males (5%) and increased with age in both sexes (p = 0.13 for females; p = 0.02 for males). In Forsyth County, TIA and stroke symptoms were greater in African Americans than in Caucasians (p = 0.05, controlling for sex). The association of algorithmically defined symptoms of TIA or stroke with traditional cerebrovascular risk factors is the subject of a companion paper.

Algorithms↗

PubMed1996

Association of transient ischemic attack/stroke symptoms assessed by standardized questionnaire and algorithm with cerebrovascular risk factors and carotid artery wall thickness. The ARIC Study, 1987-1989.

The baseline examination (1987-1989) for the Atherosclerosis Risk in Communities (ARIC) Study was conducted in 15,792 free-living residents aged 45-64 years in four geographically dispersed US communities. A questionnaire on symptoms of transient ischemic attack (TIA) and stroke was evaluated by computer algorithm for 12,205 of these participants. Data were also collected on lipoprotein levels, hemostasis, hematology, anthropometry, blood pressure, medical history, lifestyle, socioeconomic status, and medication use. Noninvasive high resolution B-mode ultrasonographic imaging was used to determine carotid arterial intimal-medial wall thickness (IMT). The cross-sectional relation between the prevalence of TIA/stroke symptoms and putative risk factors was assessed by logistic regression, controlling for age and community. Odds ratios for TIA/stroke symptoms were significantly elevated (p < or = 0.01) for diabetes mellitus, current smoking, hypertension, lower levels of education, income, and work activity, and higher levels of lipoprotein(a), IMT, hemostasis factor VIII, and von Willebrand factor. However, the relations with education and carotid IMT were not present for black Americans. In whites, the relations of TIA/stroke symptoms to IMT were nonlinear. Only at extreme levels of IMT were symptoms substantially more frequent: For example, men with an IMT greater than 1.17 mm or women with an IMT greater than 0.85 mm had approximately twice the odds of having positive TIA/stroke symptoms as those with lower IMTs. The authors plan in future analyses to address the issue prospectively, as well as to examine the relation with magnetic resonance imaging-defined outcomes and clinically defined incident stroke.

Algorithms↗

PubMed1979