Pathologic myopia: an overview of the current understanding and interventions.

Pathologic myopia is a major cause of low vision and blindness worldwide. Its social and economic burden has been demonstrated by epidemiological studies. There have been recent advances in the classification system for myopic maculopathy that enables clinicians to describe different types of lesions, including tessellated fundus, diffuse/patchy chorioretinal atrophy, macular atrophy, lacquer cracks, choroidal neovascularization (CNV), and Fuchs' spot, in a standardized format. From a therapeutic point of view, anti-vascular endothelial growth factor therapy has been established as first-line choice for myopic CNV. For myopic retinoschisis and macular holes with/without retinal detachment, pars plana vitrectomy has been generally accepted as an efficient strategy. Studies are being conducted to determine how to avoid the development of a postoperative macular hole and to improve the quality of vision after surgery. In recent years, studies have revealed preventive measures that can be taken against myopia progression, including low-dose atropine eyedrops and contact lens wearing with peripheral myopic defocusing.

Enzymatic characteristics of Nudix hydrolase 2 (Nud2), an 8-oxo-dGTP hydrolase from Myxococcus xanthus.

Myxococcus xanthus Nudix hydrolase 2 (Nud2) hydrolyzed oxidized deoxynucleotides, such as 8-oxo-dGTP, 8-oxo-dGDP, 8-OH-dTP, and 2-OH-dATP, and showed the highest specific activity toward 8-oxo-dGTP. Mn2+ was the most effective co-factor for stimulating oxidized deoxynucleotide hydrolase activity. The Km of Nud2 with 8-oxo-dGTP for Mn2+ was 19-fold lower than that for Mg2+, and was 2-fold lower than that with dGTP for Mn2+. The specificity constant (kcat/Km) for 8-oxo-dGTP was 6-fold higher than that for dGTP. Nud2 contains a similar Nudix motif (84AX590GX7REX2EEXGX). Replacement of Ala84 and/or Gly90 in the Nudix motif of Nud2 by Gly or Glu had negligible effects on 8-oxo-dGTP hydrolase activity, suggesting that a strict Nudix motif sequence is not essential for complete hydrolase activity of Nud2.

Spectral domain optical coherence tomography and fundus autofluorescence findings in cytomegalovirus retinitis in HIV-infected patients.

PURPOSE: To assess the usefulness of spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF) findings in cytomegalovirus (CMV) retinitis. STUDY DESIGN: Observational case series. METHODS: Thirteen eyes of 11 human immunodeficiency virus (HIV)-positive patients with CMV retinitis underwent full ophthalmologic examinations, SD-OCT, and 4 eyes of 4 patients underwent FAF. FAF images included short-wavelength autofluorescence (SW-AF) and near-infrared autofluorescence (IR-AF). CMV retinitis was classified into proposed categories of acute, subacute, remission, and recurrent; the acute stage was further subdivided into initial, early, and late stages. RESULTS: In the initial stage, vertical structural disruption of all retinal layers was observed by SD-OCT, and FAF showed hyperautofluorescence on SW-AF and hypoautofluorescence on IR-AF. In the early stage, SD-OCT showed significant retinal thickening; cells and debris from the retinal surface to the vitreous; enlarged vessels with/without thickened vessel walls; and highly complicated serous retinal detachment. In the late to subacute stage, features observed included rhegmatogenous retinal detachment with shrinking posterior hyaloid membrane and waving from the ellipsoid zone to the retinal pigment epithelium. In remission, FAF findings were hypoautofluorescence on SW-AF and hyperautofluorescence on IR-AF. CONCLUSION: Although the number of examined eyes was limited, SD-OCT and FAF provide new information in various stages of CMV retinitis in patients with HIV infection that is not obtainable by conventional examination and which may be of great benefit when screening for the initial stage of CMV retinitis.

Sex ratio biases in termites provide evidence for kin selection.

Inclusive fitness theory, also known as kin selection theory, is the most general expansion of Darwin's natural selection theory. It is supported by female-biased investment by workers in the social Hymenoptera where relatedness to sisters is higher than to brothers because of haplodiploidy. However, a strong test of the theory has proven difficult in diploid social insects because they lack such relatedness asymmetry. Here we show that kin selection can result in sex ratio bias in eusocial diploids. Our model predicts that allocation will be biased towards the sex that contributes more of its genes to the next generation when sex-asymmetric inbreeding occurs. The prediction matches well with the empirical sex allocation of Reticulitermes termites where the colony king can be replaced by a queen's son. Our findings open broad new avenues to test inclusive fitness theory beyond the well-studied eusocial Hymenoptera.

Age-related decrease of the retinal vasculature area identified with a novel computer-aided analysis system.

Fundus photographs enable non-invasive analysis of the status of the microcirculation by directly observing the retinal vasculature. Retinal microvascular abnormalities are important clinical markers of hypertension and arteriosclerosis, but retinal microvascular changes can be observed in older individuals without hypertension. In this study, our goal is to elucidate the effects of aging on fundus vessels in the retinal photograph. We analyzed retinal vessels of 161 healthy volunteers (49.5 ± 18.7 years, range 18-87) using in-house computer-aided measurement system to measure areas and diameters of all retinal vessels across the entire area of a retinal photograph. The vessels were segmented according to color, and then their area, size, length and thickness were measured by image processing. We also analyzed the correlation between total blood vessel area, age and mean arterial blood pressure (MABP). The decrease in total blood vessel area was dependent on both age and MABP. Moreover, decrease in blood vessel area was also correlated with age for the normotensive group. Furthermore, the slope of the regression line for retinal vessel area with MABP was significantly higher in participants aged ≤ 60 years than in those aged over 60 years. Changes in retinal vessel area with aging were observed in both arterioles and venules. In conclusion, we found the significant decrease in retinal vessel area that is correlated well with calendar age. Therefore, we need to carefully apply traditional classifications of fundus examination for hypertensive retinopathy in older individuals.

Queen pheromone regulates egg production in a termite.

In social insects, resource allocation is a key factor that influences colony survival and growth. Optimal allocation to queens and brood is essential for maximum colony productivity, requiring colony members to have information on the total reproductive power in colonies. However, the mechanisms regulating egg production relative to the current labour force for brood care remain poorly known. Recently, a volatile chemical was identified as a termite queen pheromone that inhibits the differentiation of new neotenic reproductives (secondary reproductives developed from nymphs or workers) in Reticulitermes speratus. The same volatile chemical is also emitted by eggs. This queen pheromone would therefore be expected to act as an honest message of the reproductive power about queens. In this study, we examined how the queen pheromone influences the reproductive rate of queens in R. speratus. We compared the number of eggs produced by each queen between groups with and without exposure to artificial queen pheromone. Exposure to the pheromone resulted in a significant decrease in egg production in both single-queen and multiple-queen groups. This is the first report supporting the role of queen pheromones as a signal regulating colony-level egg production, using synthetically derived compounds in a termite.

Identification of a pheromone regulating caste differentiation in termites.

The hallmark of social insects is their caste system: reproduction is primarily monopolized by queens, whereas workers specialize in the other tasks required for colony growth and survival. Pheromones produced by reigning queens have long been believed to be the prime factor inhibiting the differentiation of new reproductive individuals. However, there has been very little progress in the chemical identification of such inhibitory pheromones. Here we report the identification of a volatile inhibitory pheromone produced by female neotenics (secondary queens) that acts directly on target individuals to suppress the differentiation of new female neotenics and identify n-butyl-n-butyrate and 2-methyl-1-butanol as the active components of the inhibitory pheromone. An artificial pheromone blend consisting of these two compounds had a strong inhibitory effect similar to live neotenics. Surprisingly, the same two volatiles are also emitted by eggs, playing a role both as an attractant to workers and an inhibitor of reproductive differentiation. This dual production of an inhibitory pheromone by female reproductives and eggs probably reflects the recruitment of an attractant pheromone as an inhibitory pheromone and may provide a mechanism ensuring honest signaling of reproductive status with a tight coupling between fertility and inhibitory power. Identification of a volatile pheromone regulating caste differentiation in a termite provides insights into the functioning of social insect colonies and opens important avenues for elucidating the developmental pathways leading to reproductive and nonreproductive castes.