A Comparison of the Maximal Torque Production of the Quadriceps Muscle during Morning and Afternoon Strength Assessment

The purpose of this study was to compare maximal quadriceps torque production in morning hours (AM) to maximal quadriceps torque production in afternoon hours (PM). Thirty healthy male subjects between the ages of 19 and 45 were tested during an AM and a PM session on the Kin-Com dynamometer. A trial of six concentric isokinetic contractions of the right quadriceps were tested at a speed of 60° Is. The maximal peak torque measurements were compared between the AM and the PM sessions to establish the accuracy of results taken at differing times of the day. No significant difference in strength assessment due to the time of day of assessment was found. The data collected in this study indicates that clinical assessments of maximal peak torque production can be achieved without bias to the time of day the exercise is performed

Genome-wide association identifies ATOH7 as a major gene determining human optic disc size

Optic nerve assessment is important for many blinding diseases, with cup-to-disc ratio (CDR) assessments commonly used in both diagnosis and progression monitoring of glaucoma patients. Optic disc, cup, rim area and CDR measurements all show substantial variation between human populations and high heritability estimates within populations. To identify loci underlying these quantitative traits, we performed a genome-wide association study in two Australian twin cohorts and identified rs3858145, P = 6.2 × 10−10, near the ATOH7 gene as associated with the mean disc area. ATOH7 is known from studies in model organisms to play a key role in retinal ganglion cell formation. The association with rs3858145 was replicated in a cohort of UK twins, with a meta-analysis of the combined data yielding P = 3.4 × 10−10. Imputation further increased the evidence for association for several SNPs in and around ATOH7 (P = 1.3 × 10−10 to 4.3 × 10−11, top SNP rs1900004). The meta-analysis also provided suggestive evidence for association for the cup area at rs690037, P = 1.5 × 10−7, in the gene RFTN1. Direct sequencing of ATOH7 in 12 patients with optic nerve hypoplasia, one of the leading causes of blindness in children, revealed two novel non-synonymous mutations (Arg65Gly, Ala47Thr) which were not found in 90 unrelated controls (combined Fisher's exact P = 0.0136). Furthermore, the Arg65Gly variant was found to have very low frequency (0.00066) in an additional set of 672 controls

Mapping Neurogenesis Onset in the Optic Tectum of Xenopus Laevis

Neural progenitor cells have a central role in the development and evolution of the vertebrate brain. During early brain development, neural progenitors first expand their numbers through repeated proliferative divisions and then begin to exhibit neurogenic divisions. The transparent and experimentally accessible optic tectum of Xenopus laevis is an excellent model system for the study of the cell biology of neurogenesis, but the precise spatial and temporal relationship between proliferative and neurogenic progenitors has not been explored in this system. Here we construct a spatial map of proliferative and neurogenic divisions through lineage tracing of individual progenitors and their progeny. We find a clear spatial separation of proliferative and neurogenic progenitors along the anterior-posterior axis of the optic tectum, with proliferative progenitors located more posteriorly and neurogenic progenitors located more anteriorly. Since individual progenitors are repositioned toward more anterior locations as they mature, this spatial separation likely reflects an increased restriction in the proliferative potential of individual progenitors. We then examined whether the transition from proliferative to neurogenic behavior correlates with cellular properties that have previously been implicated in regulating neurogenesis onset. Our data reveal that the transition from proliferation to neurogenesis is associated with a small change in cleavage plane orientation and a more pronounced change in cell cycle kinetics in a manner reminiscent of observations from mammalian systems. Our findings highlight the potential to use the optic tectum of Xenopus laevis as an accessible system for the study of the cell biology of neurogenesis. This article is protected by copyright. All rights reserved

Expression of Neurog1 Instead of Atoh1 Can Partially Rescue Organ of Corti Cell Survival

In the mammalian inner ear neurosensory cell fate depends on three closely related transcription factors, Atoh1 for hair cells and Neurog1 and Neurod1 for neurons. We have previously shown that neuronal cell fate can be altered towards hair cell fate by eliminating Neurod1 mediated repression of Atoh1 expression in neurons. To test whether a similar plasticity is present in hair cell fate commitment, we have generated a knockin (KI) mouse line (Atoh1KINeurog1) in which Atoh1 is replaced by Neurog1. Expression of Neurog1 under Atoh1 promoter control alters the cellular gene expression pattern, differentiation and survival of hair cell precursors in both heterozygous (Atoh1+/KINeurog1) and homozygous (Atoh1KINeurog1/KINeurog1) KI mice. Homozygous KI mice develop patches of organ of Corti precursor cells that express Neurog1, Neurod1, several prosensory genes and neurotrophins. In addition, these patches of cells receive afferent and efferent processes. Some cells among these patches form multiple microvilli but no stereocilia. Importantly, Neurog1 expressing mutants differ from Atoh1 null mutants, as they have intermittent formation of organ of Corti-like patches, opposed to a complete ‘flat epithelium’ in the absence of Atoh1. In heterozygous KI mice co-expression of Atoh1 and Neurog1 results in change in fate and patterning of some hair cells and supporting cells in addition to the abnormal hair cell polarity in the later stages of development. This differs from haploinsufficiency of Atoh1 (Pax2cre; Atoh1f/+), indicating the effect of Neurog1 expression in developing hair cells. Our data suggest that Atoh1KINeurog1 can provide some degree of functional support for survival of organ of Corti cells. In contrast to the previously demonstrated fate plasticity of neurons to differentiate as hair cells, hair cell precursors can be maintained for a limited time by Neurog1 but do not transdifferentiate as neurons

Moral Hazard and Adverse Selection in the Insurance Market

Willardsen presented on his upcoming article with the same title. The abstract from this paper is as follows: Understanding the relative significance of adverse selection and moral hazard is important in determining effective policy for insurance markets. Separate identification of these two effects, empirically, is difficult. To overcome this limitation, this paper uses experimental methods to examine how adverse selection and moral hazard separately affect agent performance in a real-effort task. In particular, we explore how agent behavior (effort in the task) changes across a baseline with no insurance option, a treatment where individuals can choose to purchase insurance, and a third treatment where individuals must purchase insurance. We find that our platform can be helpful in studying issues that may arise in different insurance settings (e.g., workers compensation insurance or unemployment insurance).https://corescholar.libraries.wright.edu/econ_econometrics/1001/thumbnail.jp

Moral Hazard and Adverse Selection in the Insurance Market

Willardsen presented on his upcoming article with the same title. The abstract from this paper is as follows: Understanding the relative significance of adverse selection and moral hazard is important in determining effective policy for insurance markets. Separate identification of these two effects, empirically, is difficult. To overcome this limitation, this paper uses experimental methods to examine how adverse selection and moral hazard separately affect agent performance in a real-effort task. In particular, we explore how agent behavior (effort in the task) changes across a baseline with no insurance option, a treatment where individuals can choose to purchase insurance, and a third treatment where individuals must purchase insurance. We find that our platform can be helpful in studying issues that may arise in different insurance settings (e.g., workers compensation insurance or unemployment insurance)

Local Public Services Costs and the Geography of Development: Evidence from Florida Counties

Theory suggests that the spatial distribution of development within a local jurisdiction affects the costs of providing local public services. We use GINI coefficients to characterize these distributions at the county level and estimate the effects on real per capita expenditures from reductions in the spatial concentration of all buildings and nine alternative types of development. We also estimate the effect on expenditures from expansions in the developed area of a county. The results obtained from a panel of Florida counties confirm our theory and suggest that the geography of development within a county affects public services costs