Age, Gender, Biometry, Refractive Error, and the Anterior Chamber Angle among Alaskan Eskimos

The prevalence of angle-closure glaucoma (ACG) is greater for Eskimos/Inuit than it is for any other ethnic group in the world. Although it has been suggested that this prevalence may be due to a population tendency toward shallower anterior chamber angles, available evidence for other populations such as Chinese with high rates of ACG has not consistently demonstrated such a tendency

A Simple Method for Combining Genetic Mapping Data from Multiple Crosses and Experimental Designs

Over the past decade many linkage studies have defined chromosomal intervals containing polymorphisms that modulate a variety of traits. Many phenotypes are now associated with enough mapping data that meta-analysis could help refine locations of known QTLs and detect many novel QTLs.We describe a simple approach to combining QTL mapping results for multiple studies and demonstrate its utility using two hippocampus weight loci. Using data taken from two populations, a recombinant inbred strain set and an advanced intercross population we demonstrate considerable improvements in significance and resolution for both loci. 1-LOD support intervals were improved 51% for Hipp1a and 37% for Hipp9a. We first generate locus-wise permuted P-values for association with the phenotype from multiple maps, which can be done using a permutation method appropriate to each population. These results are then assigned to defined physical positions by interpolation between markers with known physical and genetic positions. We then use Fisher's combination test to combine position-by-position probabilities among experiments. Finally, we calculate genome-wide combined P-values by generating locus-specific P-values for each permuted map for each experiment. These permuted maps are then sampled with replacement and combined. The distribution of best locus-specific P-values for each combined map is the null distribution of genome-wide adjusted P-values.Our approach is applicable to a wide variety of segregating and non-segregating mapping populations, facilitates rapid refinement of physical QTL position, is complementary to other QTL fine mapping methods, and provides an appropriate genome-wide criterion of significance for combined mapping results

Uncovering the Genetic Landscape for Multiple Sleep-Wake Traits

Despite decades of research in defining sleep-wake properties in mammals, little is known about the nature or identity of genes that regulate sleep, a fundamental behaviour that in humans occupies about one-third of the entire lifespan. While genome-wide association studies in humans and quantitative trait loci (QTL) analyses in mice have identified candidate genes for an increasing number of complex traits and genetic diseases, the resources and time-consuming process necessary for obtaining detailed quantitative data have made sleep seemingly intractable to similar large-scale genomic approaches. Here we describe analysis of 20 sleep-wake traits from 269 mice from a genetically segregating population that reveals 52 significant QTL representing a minimum of 20 genomic loci. While many (28) QTL affected a particular sleep-wake trait (e.g., amount of wake) across the full 24-hr day, other loci only affected a trait in the light or dark period while some loci had opposite effects on the trait during the light vs. dark. Analysis of a dataset for multiple sleep-wake traits led to previously undetected interactions (including the differential genetic control of number and duration of REM bouts), as well as possible shared genetic regulatory mechanisms for seemingly different unrelated sleep-wake traits (e.g., number of arousals and REM latency). Construction of a Bayesian network for sleep-wake traits and loci led to the identification of sub-networks of linkage not detectable in smaller data sets or limited single-trait analyses. For example, the network analyses revealed a novel chain of causal relationships between the chromosome 17@29cM QTL, total amount of wake, and duration of wake bouts in both light and dark periods that implies a mechanism whereby overall sleep need, mediated by this locus, in turn determines the length of each wake bout. Taken together, the present results reveal a complex genetic landscape underlying multiple sleep-wake traits and emphasize the need for a systems biology approach for elucidating the full extent of the genetic regulatory mechanisms of this complex and universal behavior

Spatial clustering of ocular chlamydial infection over time following treatment, among households in a village in Tanzania. Invest Ophthalmol Vis Sci 2006

PURPOSE. To observe the spatial distribution of households with high loads of ocular chlamydia infection in children, before and after mass treatment with azithromycin to determine whether there exists spatial clustering of households with high loads of infection and the spatial scale of the clustering. METHODS. All residents of a village in Tanzania were invited to participate in the study. A global positioning system unit recorded the location of each house. Mass treatment with azithromycin was offered, with participation above 80%. Active trachoma and swab samples of the conjunctiva were assessed at baseline and at 2, 6, 12, and 18 months after treatment. A k-function analysis was performed to detect clustering of households with high loads of ocular chlamydia in children younger than 8 years. RESULTS. A total of 1055 villagers were examined during the study; of these, 374 (35.4%) were children younger than 8 years. The total number of households was 215, with 182 (84.6%) households having at least one child. K-function analysis showed clustering of households with high loads of ocular chlamydia at distances up to 2 kilometers (km) at baseline; at 6 months, slight clustering existed within 0.5 km. At 12 and 18 months, high load households clustered at distances up to 1.3 km. CONCLUSIONS. This analysis suggests that infection spreads between households with children or that nearby households share the same risk factors for infection. Mass treatment has value in lowering infection prevalence within the community, and clustering of households with infection takes up to 1 year to reemerge at the same level as baseline. Re-treatment at yearly intervals may interrupt spread of infection. (Invest Ophthalmol Vis Sci. 2006;47:99 -104

Factors Affecting Family Presence During Fracture Reduction in the Pediatric Emergency Department

Introduction: Asking family members to leave during invasive procedures has historically been common practice; however, evidence-based recommendations have altered the trend of family presence during pediatric procedures. The aim of this study was to determine factors related to family members’ choice to be present or absent during fracture reductions in a pediatric emergency department (ED), and their satisfaction with that choice. Methods: We administered role-specific, anonymous surveys to a convenience sample of patients’ family members in the ED of a Level I pediatric trauma center. All family members were given a choice of where to be during the procedure. Results: Twenty-five family members of 18 patients completed surveys. Seventeen family members chose to stay in the room. Family member satisfaction with their decision to be inside or outside the room during the procedure (median = very satisfied) was almost uniformly high and not associated with any of the following variables: previous presence during a medical procedure; provider-reported procedure difficulty, or anxiety levels. Family member perception of procedure success (median = extremely well) was also high and not associated with other variables. Location during the procedure was associated with a desire to be in the same location in the future (Fisher’s exact test, p=0.001). Common themes found among family members’ reasons for their location decisions and satisfaction levels were a desire to support the patient, high staff competence, and their right as parents to choose their location. Conclusion: Family members self-select their location during their child’s fracture reduction to high levels of satisfaction, and they considered the ability to choose their location as important

Measures of Visual Function and Percentage of Preferred Walking Speed in Older Adults: The Salisbury Eye Evaluation Project

PURPOSE. The purpose of this study was to determine the association of static (visual acuity, visual fields, and contrast sensitivity) and dynamic (dynamic visual acuity and motion threshold) measures of vision with mobility performance on a mobility course with obstacles. METHODS. A cross-sectional population-based study of 1504 persons aged 72 to 92 years enrolled in the third round of the Salisbury Eye Evaluation Project. Standardized examinations were used to test binocular visual acuity, better eye-contrast sensitivity, visual fields, dynamic visual acuity, and motion threshold. Cognitive status was assessed by using the standardized Mini-Mental State Examination. Participants were timed when walking a straight 4-m distance and when walking through a mobility course seeded with obstacles. The percentage of preferred walking speed (PPWS) for each subject was calculated as the ratio of mobility course speed to a 4-m walking speed expressed as a percentage. RESULTS. The mean age of the participants was 78.2 years. The mean 4-m walking speed was 0.82 m/s, whereas the mean mobility course speed was 0.47 m/s. The mean PPWS was 57.1%. All vision variables except visual acuity were associated with PPWS in univariate analyses. Multivariate models found visual fields and the cognitive state to be associated with PPWS. There was no association with dynamic measures of vision. CONCLUSIONS. The mobility performance, as measured by PPWS, was associated with visual fields but not with visual acuity, contrast sensitivity, or dynamic vision measures. Deficits in cognition also play an important role in predicting mobility performance. (Invest Ophthalmol Vis Sci. 2006;47:65- 2 Aging brings with it the prospect of losing independence, and vast efforts are currently being made to study the factors leading to reduced quality of life in a bid to give the growing elderly population more active years. One such factor is the mobility of individuals. A basic level of physical mobility is required to manage many of the activities of daily living satisfactorily. 3 Reduced mobility performance has been shown to be associated with functional dependence, 4,5 falls in the elderly, 6,7 and nursing home placement, 8 -12 and it also has been found to predict depression. 13 Many studies have looked at the link between mobility and mortality, and have shown an association. 3,8,14 -16 Apart from the personal costs, the adverse sequelae of mobility impairment carry huge costs to society as well. 20,21 Small-scale convenience samples of visually impaired and/or older adults have shown that decrements in vision adversely affect mobility performance. Mobility performance can be measured by using several metrics. Some studies have used the number of errors or bumps 24 -26,30 PPWS was put forward by Clark-Carter et al. METHODS Subjects The Salisbury Eye Evaluation Project is a longitudinal, population-based study of community-dwelling seniors residing in Wicomico County, MD. The original sample was collected in 1993 and comprised 2520 persons aged 65 to 84 years. A description of the original cohort can be found elsewhere. 34 Data for this study were collected in round three of the study, which was conducted between 1999 and 2000. Follow-up rates were 95% and 86% of those still alive for the second and third rounds, respectively. The participants (n ϭ 1504) were aged between 72 and 92 years. Basic demographic data were obtained from a structured questionnaire. Cognitive status was assessed by using the standardized Mini-Mental State Examination (MMSE)