Prevalence of age-related macular degeneration in Nakuru, Kenya: a cross-sectional population-based study.

BACKGROUND: Diseases of the posterior segment of the eye, including age-related macular degeneration (AMD), have recently been recognised as the leading or second leading cause of blindness in several African countries. However, prevalence of AMD alone has not been assessed. We hypothesized that AMD is an important cause of visual impairment among elderly people in Nakuru, Kenya, and therefore sought to assess the prevalence and predictors of AMD in a diverse adult Kenyan population. METHODS AND FINDINGS: In a population-based cross-sectional survey in the Nakuru District of Kenya, 100 clusters of 50 people 50 y of age or older were selected by probability-proportional-to-size sampling between 26 January 2007 and 11 November 2008. Households within clusters were selected through compact segment sampling. All participants underwent a standardised interview and comprehensive eye examination, including dilated slit lamp examination by an ophthalmologist and digital retinal photography. Images were graded for the presence and severity of AMD lesions following a modified version of the International Classification and Grading System for Age-Related Maculopathy. Comparison was made between slit lamp biomicroscopy (SLB) and photographic grading. Of 4,381 participants, fundus photographs were gradable for 3,304 persons (75.4%), and SLB was completed for 4,312 (98%). Early and late AMD prevalence were 11.2% and 1.2%, respectively, among participants graded on images. Prevalence of AMD by SLB was 6.7% and 0.7% for early and late AMD, respectively. SLB underdiagnosed AMD relative to photographic grading by a factor of 1.7. After controlling for age, women had a higher prevalence of early AMD than men (odds ratio 1.5; 95% CI, 1.2-1.9). Overall prevalence rose significantly with each decade of age. We estimate that, in Kenya, 283,900 to 362,800 people 50 y and older have early AMD and 25,200 to 50,500 have late AMD, based on population estimates in 2007. CONCLUSIONS: AMD is an important cause of visual impairment and blindness in Kenya. Greater availability of low vision services and ophthalmologist training in diagnosis and treatment of AMD would be appropriate next steps. Please see later in the article for the Editors' Summary

FRET: Validity of a Fall Risk Evaluation Tool for Individuals with Acquired Brain Injuries

Objective: The purpose of this study is to evaluate the predictive validity of the Fall Risk Evaluation Tool (FRET) for individuals with acquired brain injuries (ABIs). Methods: Ten participants were included for the study. Inclusion criteria for participants included: age 18 and older, English speaking, 6-months post ABI, ambulatory with or without an assistive device, and uses a wheelchair less than 25% of the day. Exclusion criteria for participants included: global confusion and degenerative neurological conditions. Following the administration of the FRET, participants recorded falls that occurred over the following 3-month study period. Results: Data was analyzed using the Pearson’s r correlation coefficient. No correlation was found between the FRET score and the participants’ reported number of falls during the study period. Correlation between individual subtests within the FRET and actual fall occurrence was also examined. The medication subtest was the only item on the FRET that showed a significant correlation with the participants’ falls. A significant correlation was found between the number of falls during 6-months prior to the study and the fall occurrence during the 3-month study period. Conclusion: There is currently a lack of multi-factorial fall risk assessments specifically designed for individuals with ABIs. The FRET was designed to fill this gap in assessments for individuals with ABIs, although no conclusion can currently be drawn regarding its predictive validity. The study suggests modifications should be made to the FRET to increase the predictive validity the FRET

Trends in Mortality from Septicaemia and Pneumonia with Economic Development: An Age-Period-Cohort Analysis

BackgroundHong Kong population has experienced drastic changes in its economic development in the 1940s. Taking advantage of Hong Kong’s unique demographic and socioeconomic history, characterized by massive, punctuated migration waves from Southern China, and recent, rapid transition from a pre-industrialized society to the first ethnic Chinese community reaching ‘‘first world’’ status over the last 60 years (i.e., in two or three generations), we examined the longitudinal trends in infection related mortality including septicemia compared to trends in non-bacterial pneumonia to generate hypotheses for further testing in other recently transitioned economies and to provide generalized aetiological insights on how economic transition affects infection-related mortality. Methods We used deaths from septicemia and pneumonia not specified as bacterial, and population figures in Hong Kong from 1976–2005. We fitted age-period-cohort models to decompose septicemia and non-bacterial pneumonia mortality rates into age, period and cohort effects. Results Septicaemia-related deaths increased exponentially with age, with a downturn by period. The birth cohort curves had downward inflections in both sexes in the 1940s, with a steeper deceleration for women. Non-bacterial pneumoniarelated deaths also increased exponentially with age, but the birth cohort patterns showed no downturns for those born in the 1940s. Conclusion The observed changes appeared to suggest that better early life conditions may enable better development of adaptive immunity, thus enhancing immunity against bacterial infections, with greater benefits for women than men. Given the interaction between the immune system and the gonadotropic axis, these observations are compatible with the hypothesis that upregulation of the gonadotropic axis underlies some of the changes in disease patterns with economic development

Measuring the neighborhood environment: associations with young girls' energy intake and expenditure in a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Neighborhood environments affect children's health outcomes. Observational methods used to assess neighborhoods can be categorized as indirect, intermediate, or direct. Direct methods, involving in-person audits of the neighborhoods conducted by trained observers, are recognized as an accurate representation of current neighborhood conditions. The authors investigated the associations of various neighborhood characteristics with young girls' diet and physical activity.</p> <p>Methods</p> <p>This study is based on a subset of participants in the Cohort Study of Young Girls' Nutrition, Environment and Transitions (CYGNET). In-person street audits were conducted within 215 girls' residential neighborhoods using a modified St. Louis Audit Tool. From the street audit data, exploratory factor analysis revealed five neighborhood scales: "mixed residential and commercial," "food and retail," "recreation," "walkability," and "physical disorder." A Neighborhood Deprivation Index was also derived from census data. The authors investigated if the five neighborhood scales and the Neighborhood Deprivation Index were associated with quartiles of total energy intake and expenditure (metabolic equivalent (MET) hours/week) at baseline, and whether any of these associations were modified by race/ethnicity.</p> <p>Results</p> <p>After adjustment for demographic characteristics, there was an inverse association between prevalence of "food and retail" destinations and total energy intake (for a one quartile increase, OR = 0.84, 95% CI 0.74, 0.96). Positive associations were also observed between the "recreation" and "walkability" scales with physical activity among Hispanic/Latina girls (for a one quartile increase in MET, OR = 1.94, 95% CI 1.31, 2.88 for recreation; OR = 1.71, 95% CI 1.11, 2.63 for walkability). Among African-American girls, there was an inverse association between "physical disorder" and physical activity (OR = 0.31, 95% CI 0.12, 0.80).</p> <p>Conclusions</p> <p>These results suggest that neighborhood food and retail availability may be inversely associated with young girls' energy intakes in contrast to other studies' findings that focused on adults. There is considerable variation in neighborhoods' influences on young girls' physical activity behaviors, particularly for young girls of different racial/ethnic backgrounds.</p

The MOSDEF survey: a stellar mass-SFR-metallicity relation exists at z∼2.3z\sim2.3

We investigate the nature of the relation among stellar mass, star-formation rate, and gas-phase metallicity (the M$_*$-SFR-Z relation) at high redshifts using a sample of 260 star-forming galaxies at $z\sim2.3$ from the MOSDEF survey. We present an analysis of the high-redshift M$_*$-SFR-Z relation based on several emission-line ratios for the first time. We show that a M$_*$-SFR-Z relation clearly exists at $z\sim2.3$. The strength of this relation is similar to predictions from cosmological hydrodynamical simulations. By performing a direct comparison of stacks of $z\sim0$ and $z\sim2.3$ galaxies, we find that $z\sim2.3$ galaxies have $\sim0.1$ dex lower metallicity at fixed M$_*$ and SFR. In the context of chemical evolution models, this evolution of the M$_*$-SFR-Z relation suggests an increase with redshift of the mass-loading factor at fixed M$_*$, as well as a decrease in the metallicity of infalling gas that is likely due to a lower importance of gas recycling relative to accretion from the intergalactic medium at high redshifts. Performing this analysis simultaneously with multiple metallicity-sensitive line ratios allows us to rule out the evolution in physical conditions (e.g., N/O ratio, ionization parameter, and hardness of the ionizing spectrum) at fixed metallicity as the source of the observed trends with redshift and with SFR at fixed M$_*$ at $z\sim2.3$. While this study highlights the promise of performing high-order tests of chemical evolution models at high redshifts, detailed quantitative comparisons ultimately await a full understanding of the evolution of metallicity calibrations with redshift.Comment: 19 pages, 8 figures, accepted to Ap

Measurement of retinal vessels as a biomarker of cerebrovascular ageing in older HIV positive men compared to controls

Background: To compare retinal vascular measurements, biomarkers of cerebral small vessel disease (SVD), in HIV positive men aged 50 years and above with similarly-aged HIV negative men and younger HIV positive men. Methods: We recruited white, non-diabetic men to a cross-sectional substudy of a larger cohort including three demographically-matched groups. Optic disc centred 45° colour fundus photographs were used to calculate central retinal arterial and venous calibre and the arterial- venous ratio (AVR). We used univariate and multivariable linear regression to compare retinal vessel measurements in the three groups and to identify factors associated with AVR. Results: All HIV positive men were virologically suppressed. In a multivariable model, study group was not associated with AVR (adjusted β 0.010 for HIV positive men 50 years [n=120], 95% CI -0.018 to 0.038, p=0.47; adjusted β 0.00002 for HIV negative men >50 years [n=52], 95% CI -0.022 to 0.022, p=0.99). Factors associated with lower AVR were systolic BP (adjusted β -0.009 per +10 mmHg, 95% CI - 0.015 to -0.003, p=0.002), history of stroke or transient ischemic attack (adjusted β -0.070, 95% CI -0.12 to -0.015, p=0.01), and recent recreational drug use (adjusted β -0.037, 95% CI -0.057 to -0.018, p=0.0002). Conclusion: There were no differences in retinal vascular indices between HIV positive men aged >50 years and HIV negative men aged >50 years or HIV positive men aged <50 years, suggesting that HIV is not associated with an increased burden of cerebral SVD

The MOSDEF Survey: Kinematic and Structural Evolution of Star-Forming Galaxies at 1.4≤z≤3.81.4\leq z\leq 3.8

We present ionized gas kinematics for 681 galaxies at $z\sim 1.4-3.8$ from the MOSFIRE Deep Evolution Field survey, measured using models which account for random galaxy-slit misalignments together with structural parameters derived from CANDELS Hubble Space Telescope (HST) imaging. Kinematics and sizes are used to derive dynamical masses. Baryonic masses are estimated from stellar masses and inferred gas masses from dust-corrected star formation rates (SFRs) and the Kennicutt-Schmidt relation. We measure resolved rotation for 105 galaxies. For the remaining 576 galaxies we use models based on HST imaging structural parameters together with integrated velocity dispersions and baryonic masses to statistically constrain the median ratio of intrinsic ordered to disordered motion, $V/\sigma_{V,0}$. We find that $V/\sigma_{V,0}$ increases with increasing stellar mass and decreasing specific SFR (sSFR). These trends may reflect marginal disk stability, where systems with higher gas fractions have thicker disks. For galaxies with detected rotation we assess trends between their kinematics and mass, sSFR, and baryon surface density ($\Sigma_{\mathrm{bar},e}$). Intrinsic dispersion correlates most with $\Sigma_{\mathrm{bar},e}$ and velocity correlates most with mass. By comparing dynamical and baryonic masses, we find that galaxies at $z\sim 1.4-3.8$ are baryon dominated within their effective radii ($R_E$), with Mdyn/Mbaryon increasing over time. The inferred baryon fractions within $R_E$, $f_{\mathrm{bar}}$, decrease over time, even at fixed mass, size, or surface density. At fixed redshift, $f_{\mathrm{bar}}$ does not appear to vary with stellar mass but increases with decreasing $R_E$ and increasing $\Sigma_{\mathrm{bar},e}$. For galaxies at $z\geq2$, the median inferred baryon fractions generally exceed 100%. We discuss possible explanations and future avenues to resolve this tension.Comment: Accepted to ApJ. Added Figure 9, corrected sample size (main results unchanged). 28 pages, 13 figure

Effectiveness of a COVID-19 contact tracing app in a simulation model with indirect and informal contact tracing

During the COVID-19 pandemic, contact tracing was used to identify individuals who had been in contact with a confirmed case so that these contacted individuals could be tested and quarantined to prevent further spread of the SARS-CoV-2 virus. Many countries developed mobile apps to find these contacted individuals faster. We evaluate the epidemiological effectiveness of the Dutch app CoronaMelder, where we measure effectiveness as the reduction of the reproduction number R. To this end, we use a simulation model of SARS-CoV-2 spread and contact tracing, informed by data collected during the study period (December 2020 - March 2021) in the Netherlands. We show that the tracing app caused a clear but small reduction of the reproduction number, and the magnitude of the effect was found to be robust in sensitivity analyses. The app could have been more effective if more people had used it, and if notification of contacts could have been done directly by the user and thus reducing the time intervals between symptom onset and reporting of contacts. The model has two innovative aspects: i) it accounts for the clustered nature of social networks and ii) cases can alert their contacts informally without involvement of health authorities or the tracing app.</p