Inter-rater reliability of occupational exposure assessment in a case-control study of female breast cancer.

The objective of this paper was to estimate the inter-rater reliability of expert assessments of occupational exposures. An inter-rater reliability sub-study was conducted within a population-based case-control study of postmenopausal breast cancer. Detailed information on lifetime occupational histories was obtained from participants and two industrial hygienists assigned exposures to 185 jobs using a checklist of 293 agents. Experts rated exposure for each job-agent combination according to exposure status (unexposed/exposed), confidence that the exposure occurred (possible/probable/definite), intensity (low/medium/high), and frequency (% time per week). The statistical unit of observation was each job-agent assessment (185 jobs × 293 agents = 54,205 assessments per expert). Crude agreement, Gwet AC1/2 statistics, and Cohen's Kappa were used to estimate inter-rater agreement for confidence and intensity; for frequency, the intra-class correlation coefficient (ICC) was used. The majority of job-agent combinations were evaluated by the two experts to be not exposed (crude agreement >98% of decisions). The degree of agreement between the experts for the confidence of exposure status was Gwet AC1/2 = 0.99 (95% CI: 0.99-0.99), and for intensity, a Gwet AC2 = 0.99 (95% CI: 0.99-0.99). For frequency, an ICC of 0.31 (95% CI: 0.26-0.35) was found. A sub-analysis restricted to job-agent combinations for which the two experts agreed on exposure status revealed a moderate agreement for confidence of exposure (Gwet AC2 = 0.66) and high agreement for intensity (Gwet AC2 = 0.96). For frequency, the ICC was 0.52 (95% CI: 0.47-0.57). A high level of inter-rater agreement was found for identifying exposures and for coding intensity, but agreement was lower for the coding of frequency of exposure.

High burden of neurological disease in the older general population: results from the Canadian Longitudinal Study on Aging.

BACKGROUND AND PURPOSE: Our objective was to study the association between the presence of a neurological disease and the comorbidity burden as well as healthcare utilization (HCU). METHODS: Using baseline data from the Canadian Longitudinal Study on Aging (CLSA), we examined the burden of five neurological conditions. The CLSA is a population-based study of approximately 50 000 individuals, aged 45-85 years at baseline. We used multivariable Poisson regression to identify correlates of comorbidity burden and HCU. RESULTS: The lifetime prevalence of five neurological diseases is presented: epilepsy, Parkinson's disease/parkinsonism, stroke/transient ischaemic attack, multiple sclerosis and migraine. We found the somatic and psychiatric comorbidity burden to be higher in those individuals with a neurological disease (an 18-45% mean increase in the number of chronic conditions) as compared with the comparison group without a neurological disease, except for Parkinson's disease/parkinsonism. The presence of a neurological disease was associated with only a modest increase in the probability of visiting a general practitioner but was associated with a greatly increased probability of visiting a medical specialist (up to 68% more likely) or an emergency department (up to 79% more likely) and an overnight hospitalization (up to 108% more likely). CONCLUSIONS: We found striking associations between our neurological diseases and increased comorbidity burdens and HCU. These findings are important for informing public policy planning as well as driving avenues for future research. The present study established the CLSA as an important research platform for the study of neurological conditions in an aging general population.

Genetic hitchhiking and resistance evolution to transgenic Bt toxins: insights from the African stalk borer Busseola fusca (Noctuidae).

Since transgenic crops expressing Bacillus thuringiensis (Bt) toxins were first released, resistance evolution leading to failure in control of pests populations has been observed in a number of species. Field resistance of the moth Busseola fusca was acknowledged 8 years after Bt maize was introduced in South Africa. Since then, field resistance of this corn borer has been observed at several locations, raising questions about the nature, distribution and dynamics of the resistance trait. Using genetic markers, our study identified four outlier loci clearly associated with resistance. In addition, genetic structure at neutral loci reflected extensive gene flow among populations. A realistically parameterised model suggests that resistance could travel in space at speed of several kilometres a year. Markers at outlier loci delineated a geographic region associated with resistance spread. This was an area of approximately 100 km radius, including the location where resistance was first reported. Controlled crosses corroborated these findings and showed significant differences of progeny survival on Bt plants depending on the origin of the resistant parent. Last, our study suggests diverse resistance mutations, which would explain the widespread occurrence of resistant larvae in Bt fields across the main area of maize production in South Africa.

AFLP analysis of the phenetic organization and genetic diversity of Vigna unguiculataL. Walp. reveals extensive gene flow between wild and domesticated types.

Amplified fragment length polymorphisms (AFLPs) were used to evaluate genetic relationships within cowpea [ Vigna unguiculata (L.) Walp.] and to assess the organization of its genetic diversity. Nei's genetic distances were estimated for a total of 117 accessions including 47 domesticated cowpea (ssp. unguiculata var. unguiculata), 52 wild and weedy annuals (ssp. unguiculata var. spontanea), as well as 18 perennial accessions of the wild subspecies pubescens, tenuis and alba. AFLP variation was also used to study genetic variation among and within domesticated and wild accessions based on their geographical origin (western, eastern and southern Africa). Wild annual cowpea (var. spontanea) ( H (T)=0.175) was more diverse than domesticated cowpea ( H (T)=0.108). Wild cowpea was more diverse in eastern ( H (S)=0.168) than in western Africa ( H (S)=0.129), suggesting an eastern African origin for the wild taxon. The AFLP data were consistent with earlier findings of a unique domestication event in cowpea in the northern part of the continent and suggested that domestication in eastern or southern Africa was unlikely. It did not allow a more precise localization of domestication due to extensive gene flow between wild and domesticated forms that has led to a large crop-weed complex distributed over the entire African continent. In addition, wild materials from northeastern Africa are still lacking. Overall, the superiority of the AFLP technique over isozymes resided in its ability to uncover variation both within domesticated and wild cowpea, and should be a powerful tool once additional wild material becomes available.