ER-mitochondria tethering by PDZD8 regulates Ca2+ dynamics in mammalian neurons

Interfaces between organelles are emerging as critical platforms for many biological responses in eukaryotic cells. In yeast, the ERMES complex is an endoplasmic reticulum (ER)-mitochondria tether composed of four proteins, three of which contain a SMP (synaptotagmin-like mitochondrial-lipid binding protein) domain. No functional ortholog for any ERMES protein has been identified in metazoans. Here, we identified PDZD8 as an ER protein present at ER-mitochondria contacts. The SMP domain of PDZD8 is functionally orthologous to the SMP domain found in yeast Mmm1. PDZD8 was necessary for the formation of ER-mitochondria contacts in mammalian cells. In neurons, PDZD8 was required for calcium ion (Ca2+) uptake by mitochondria after synaptically induced Ca2+-release from ER and thereby regulated cytoplasmic Ca2+ dynamics. Thus, PDZD8 represents a critical ER-mitochondria tethering protein in metazoans. We suggest that ER-mitochondria coupling is involved in the regulation of dendritic Ca2+ dynamics in mammalian neurons

Evaluation of Cerebral White Matter in Prelingually Deaf Children Using Diffusion Tensor Imaging

This study compared white matter development in prelingually deaf and normal-hearing children using a tract-based spatial statistics (TBSS) method. Diffusion tensor imaging (DTI) was performed in 21 prelingually deaf (DEAF group) and 20 normal-hearing (HEAR group) subjects aged from 1.7 to 7.7 years. Using TBSS, we evaluated the regions of significant difference in fractional anisotropy (FA) between the groups. Correlations between FA values and age in each group were also analyzed using voxel-wise correlation analyses on the TBSS skeleton. Lower FA values of the white matter tract of Heschl’s gyrus, the inferior frontooccipital fasciculus, the uncinate fasciculus, the superior longitudinal fasciculus, and the forceps major were evident in the DEAF group compared with those in the HEAR group below 4 years of age, while the difference was not significant in older subjects. We also found that age-related development of the white matter tracts may continue until 8 years of age in deaf children. These results imply that development of the cerebral white matter tracts is delayed in prelingually deaf children

Janus-FTL Adjusting the Size of Page and Block Mapping Areas using Reference Pattern

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TinyFTL: An FTL architecture for flash memory cards with scarce resources

In this paper, we focus on firmware design for flash memory cards that have scarce resources such as small amount of SRAM and low performance processors. Our design goals include devising practical, commercial grade features required for commercial flash memory cards and minimizing memory requirements to support these features. To this end, we propose TinyFTL (Flash Translation Layer) that has low memory requirements for implementing full features such as efficient garbage collection, mapping, caching, and fast boot-up. Through implementation and experiments, we show that even with smaller memory footprints TinyFTL performs better in terms of performance and boot-up time than implementations of state-of-the-art FTL

Preliminary evidence of a relationship between sleep spindles and treatment response in epileptic encephalopathy

Abstract Objective Epileptic encephalopathy with spike‐wave activation in sleep (EE‐SWAS) is a challenging neurodevelopmental disease characterized by abundant epileptiform spikes during non‐rapid eye movement (NREM) sleep accompanied by cognitive dysfunction. The mechanism of cognitive dysfunction is unknown, but treatment with high‐dose diazepam may improve symptoms. Spike rate does not predict treatment response, but spikes may disrupt sleep spindles. We hypothesized that in patients with EE‐SWAS: (1) spikes and spindles would be anti‐correlated, (2) high‐dose diazepam would increase spindles and decrease spikes, and (3) spindle response would be greater in those with cognitive improvement. Methods Consecutive EE‐SWAS patients treated with high‐dose diazepam that met the criteria were included. Using a validated automated spindle detector, spindle rate, duration, and percentage were computed in pre‐ and post‐treatment NREM sleep. Spikes were quantified using a validated automated spike detector. The cognitive response was determined from a chart review. Results Spindle rate was anti‐correlated with the spike rate in the channel with the maximal spike rate (p = 0.002) and averaged across all channels (p = 0.0005). Spindle rate, duration, and percentage each increased, and spike rate decreased, after high‐dose diazepam treatment (p ≤ 2e‐5, all tests). Spindle rate, duration, and percentage (p ≤ 0.004, all tests) were increased in patients with cognitive improvement after treatment, but not those without. Changes in spindle rate but not changes in spike rate distinguished between groups. Interpretation These findings confirm thalamocortical disruption in EE‐SWAS, identify a mechanism through which benzodiazepines may support cognitive recovery, and introduce sleep spindles as a promising mechanistic biomarker to detect treatment response in severe epileptic encephalopathies

A Flash-Aware Cluster Allocation Scheme for Legacy File Systems

As the multimedia handheld devices using NAND flash memory as storage media is becoming more popular, the importance of the flash file system is increasing. Although there has been substantial research on file systems dedicated to NAND flash memory, little attention has been paid to legacy file systems running on top of NAND flash memory. In this paper, we propose an anti-fragmentation cluster allocation (AFCA) scheme for the Linux Ext2 file system. For the proposed scheme, we re-define the concept of file system fragmentation that takes into account the characteristics of NAND flash memory. The proposed AFCA scheme tries to minimize the performance degradation resulting from the fragmentation problem by discriminately allocating free clusters to files depending on their size relative to the flash memory block size. Evaluation results show that compared to the original cluster allocation scheme in Ext2, the proposed AFCA scheme significantly reduces the file system fragmentation according to the new definition and improves the file system performance, especially the write performance, by up to 43%ope