Substantial progress in controlling schistosomiasis has also been achieved in most of the remaining endemic areas and the total number of infected people has been reduced by over 90% since 1950 [127,128]. A nationwide sampling survey conducted in 2004 provided a detailed picture of the contemporary epidemiological situation and put the number of infections any other enquiries at 720,000 [129]. In 2008, the number of infections was estimated at about 412,000 [130]. The schistosome-endemic areas of China have been stratified into three types, based on ecosystem characteristics, namely the plain and water-network region, marshland and lake region, and hilly and mountainous region.
The parasite has been eliminated from the formerly most heavily endemic plain and water-network region and has lar
The retina of all vertebrates contains rod photoreceptors for dim light environments and cone photoreceptors for brighter environments; cones are further divided into short-wavelength-sensitive (S) and long- and middle-wavelength-sensitive (L/M) subtypes. These photoreceptors, which are organized into mosaic structures with characteristic rod/cone ratio in retinal position and species specific manner, are organized to provide useful visual sensation for the animals during their entire life span. Thus, a normal retina is controlled by a multitude of interacting factors that determine the precise developmental organization and lifetime maintenance of interconnected neurons for optimal visual function (1, 2). Disruption of these complex interactions during development or in the mature retina can give rise to cellular pathology, mainly manifesting as loss of vision.
In addition to the development and maintenance processes of the photoreceptor itself, homeostatic processes in neighboring cells contribute to photoreceptor health. A key example of this support function is continuous phagocytosis of shed photoreceptor discs by the neighboring retinal pigment epithelium (RPE; refs. 3�C5). Enhanced S-cone syndrome (ESCS) is a human visual disorder first recognized for its unique feature of showing increased S-cone vision. With noninvasive studies, ESCS was demonstrated to result in supernormal sensitivity to blue colors and an excess number of S cones, normally the minority photoreceptor in the human retinal mosaic consisting mainly of rods and L/M cones. In contrast, rod and L/M-cone vision are reduced in ESCS.
A hypothesis emerging from these results was that abnormal retinal development Drug_discovery causes ESCS involving a disturbance in photoreceptor cell specification (6�C8). A search for the causative genes ensued, and mutations in most patients mapped to the gene encoding the human photoreceptor-specific nuclear receptor, NR2E3, while a few mapped to the neural retina leucine zipper, NRL, gene (9�C11).