Myotonic dystrophy (DM) is a multi-systemic disease that impacts cardiac and skeletal muscle as well as the central nervous system (CNS). DM is unusual because it is an RNA-mediated disorder due to the expression of toxic microsatellite expansion RNAs that alter the activities of RNA processing factors, including the muscleblind-like (MBNL) proteins. While these mutant RNAs inhibit MBNL1 splicing activity in heart and skeletal muscles, Mbnl1 knockout mice fail to recapitulate the full-range of DM symptoms in these tissues. Here, we generate mouse Mbnl compound knockouts to test the hypothesis that Mbnl2 functionally compensates for Mbnl1 loss. Although Mbnl1−/−; Mbnl2−/− double knockouts (DKOs) are embryonic lethal, Mbnl1−/−; Mbnl2+/− mice are viable but develop cardinal features of DM muscle disease including reduced lifespan, heart conduction block, severe myotonia and progressive skeletal muscle weakness. Mbnl2 protein levels are elevated in Mbnl1−/− knockouts where Mbnl2 targets Mbnl1-regulated exons. These findings support the hypothesis that compound loss of MBNL function is a critical event in DM pathogenesis and provide novel mouse models to investigate additional pathways disrupted in this RNA-mediated disease.

The present study suggests that WE hair is relatively susceptible and African hair is more resistant to chemical stresses, such as those imposed by straightening and coloring.

BackgroundNo comprehensive study currently exists on the supply of ophthalmologists across Latin America. We explored sociogeographic inequalities in the availability and distribution of ophthalmologists across 14 Latin American countries.MethodsThe National Ophthalmologic Societies of Argentina, Bolivia, Brazil, Colombia, Costa Rica, Chile, the Dominican Republic, Ecuador, Guatemala, Mexico, Paraguay, Peru, Uruguay and Venezuela provided data on affiliated ophthalmologists by first-order subnational divisions in 2013. Human Development Index (HDI) estimates at the corresponding subnational division were used as equity stratifiers. Distributional inequality of ophthalmologists within each country was assessed by the health concentration index (HCI) and the index of dissimilarity (ID), along with the mean level of ophthalmologists per population.ResultsAcross all countries studied, there were 5.2 ophthalmologists per 100 000 population on average (95% CI 5.0 to 5.4) in 2013, with a mean HCI of 0.26 (0.16 to 0.37) and a mean relative ID of 22.7% (20.9% to 24.7%). There was wide inequality in ophthalmologist availability between countries, ranging from 1.2 (1.1 to 1.4) in Ecuador to 8.6 (8.5 to 8.8) in Brazil. All countries had positive (ie, pro-rich) HCI values ranging from 0.68 (0.66 to 0.71) in Guatemala to 0.02 (−0.11 to 0.14) in Venezuela. Correspondingly, redistributive potential to achieve equity was closest in Venezuela (ID: 1.5%) and farthest in Guatemala (ID: 60.3%). Benchmarked against regional averages, most countries had a lower availability of ophthalmologists and higher relative inequality.ConclusionsThere is high inequality in the level and distribution of ophthalmologists between and within countries in Latin America, with a disproportionate number concentrated in more developed, socially advantaged areas. More equitable access to ophthalmologists could be achieved by implementing incentivised human resources redistribution programmes and by improving the social determinants of health in underserved areas.

Pattern hair loss (PHL) is the most common form of baldness in both sexes. The Norwood-Hamilton classification is the most commonly used classification worldwide, but it has many limitations. The basic and specific (BASP) classification was introduced as an improvement over the Norwood-Hamilton classification. Previous research was done to estimate the reliability of the Norwood-Hamilton classification and the result was unsatisfactory. However, the reliability of the BASP and Norwood-Hamilton classifications has not yet been compared. Eight dermatological specialists, 17 dermatological residents and 15 general physicians classified PHL in 100 sets of photographs using both the BASP and Norwood-Hamilton classifications. Intergroup reproducibility was evaluated by examining the match rate of the individual data in each group and the match rate between hair specialist and the other examiners. Intragroup repeatability was determined by calculating the match rate between the first and second studies. In terms of intergroup reproducibility of the match rate for individual data in each group, the basic type had the best agreement, the specific type had the second best, and the Norwood-Hamilton classification had the lowest match rate. In comparison, hair specialist and intragroup repeatability showed the same patterns. The BASP classification not only distinguishes all kinds of hair loss patterns, but also has better reproducibility and repeatability than the Norwood-Hamilton classification.

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