Search

Dravet syndrome is a developmental epileptic encephalopathy caused by pathogenic variation in SCN1A To characterize the pathogenic substitution (p.H939R) of a local individual with Dravet syndrome, fibroblast cells from the individual were reprogrammed to pluripotent stem cells and differentiated into neurons. Sodium currents of these neurons were compared with healthy control induced neurons. A novel Scn1a H939R/+ mouse model was generated with the p.H939R substitution. Immunohistochemistry and electrophysiological experiments were performed on hippocampal slices of Scn1a H939R/+ mice. We found that the sodium currents recorded in the proband-induced neurons were significantly smaller and slower compared to wild type (WT). The resting membrane potential and spike amplitude were significantly depolarized in the proband-induced neurons. Similar differences in resting membrane potential and spike amplitude were observed in the interneurons of the hippocampus of Scn1a H939R/+ mice. The Scn1a H939R/+ mice showed the characteristic features of a Dravet-like phenotype: increased mortality and both spontaneous and heat-induced seizures. Immunohistochemistry showed a reduction in amount of parvalbumin and vesicular acetylcholine transporter in the hippocampus of Scn1a H939R/+ compared to WT mice. Overall, these results underline hyper-excitability of the hippocampal CA1 circuit of this novel mouse model of Dravet syndrome which, under certain conditions, such as temperature, can trigger seizure activity. This hyper-excitability is due to the altered electrophysiological properties of pyramidal neurons and interneurons which are caused by the dysfunction of the sodium channel bearing the p.H939R substitution. This novel Dravet syndrome model also highlights the reduction in acetylcholine and the contribution of pyramidal cells, in addition to interneurons, to network hyper-excitability., (Copyright © 2020 by the Genetics Society of America.)

Rapid (<2 min) and quantitative genotyping for single nucleotide polymorphisms (SNPs) associated with spinal muscular atrophy was done using a reusable (approximately 80 cycles of application) fibre-optic biosensor over a clinically relevant range (0-4 gene copies). Sensors were functionalized with oligonucleotide probes immobilized at high density (approximately 7 pmol/cm2) to impart enhanced selectivity for SNP discrimination and used in a total internal reflection fluorescence detection motif to detect 202 bp PCR amplicons from patient samples. Real-time detection may be done over a range of ionic strength conditions (0.1-1.0 M) without stringency rinsing to remove non-selectively bound materials and without loss of selectivity, permitting a means for facile sample preparation. By using the time-derivative of fluorescence intensity as the analytical parameter, linearity of response may be maintained while allowing for significant reductions in analysis time (10-100-fold), permitting for the completion of measurements in under 1 min.

Purpose: Although there is a body of knowledge relating to the different challenges residents encounter after nursing home placement, less is known about the actual process of how they handle these challenges and adjust after such placement. This study described the process whereby Hong Kong Chinese residents adjust following nursing home placement., Design and Methods: The grounded theory methodology was employed. Data were collected from 98 interviews with 18 residents newly admitted to a nursing home in Hong Kong one week after admission and then monthly until no new information about their adjustment experiences could be discovered. Data were analyzed using constant comparative analysis., Results: Newly admitted elders adjusted through the four stages of orienting, normalizing, rationalizing, and stabilizing as they struggled to regain normality with a life that was as close to that lived before admission as possible. A number of experiences suggested in the literature as barriers to adjustment, such as living with rules and regulations, and the communal nature of nursing home life were not regarded as important by Chinese elders. However, establishing relations with other residents was a particular challenge for them., Implications: Interventions to promote adjustment should aim to assist with the process of regaining normality with the different aspects of nursing home living, taking into consideration residents' life experience and sociocultural values.

The inhibitor of apoptosis proteins (IAPs) constitute a family of highly conserved apoptosis suppressor proteins that was originally identified in baculoviruses. Although IAP homologs have been recently identified and demonstrated to suppress apoptosis in mammalian cells, their expression and role during follicular development and atresia are unknown. The present study was conducted to address these questions. Using established in vivo models for the induction of follicular development and atresia in immature rats, it was possible to compare the immunolocalization of X-link inhibitor of apoptosis protein (Xiap) and human inhibitor of apoptosis protein-2 (Hiap-2), two members of the IAP family, at defined stages of follicular maturation and to relate the differences observed with those of follicular cell proliferation and apoptosis [as determined by proliferating cell nuclear antigen (PCNA) immunohistochemistry and in situ terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (TUNEL), respectively]. In addition, granulosa cell DNA and proteins were assessed for apoptotic fragmentation by 3'-end labeling/agarose gel electrophoresis (DNA ladder) and Hiap-2 and Xiap protein content by Western blot analysis, respectively. Hiap-2 and Xiap expression in both granulosa and theca cells increased with follicular maturation, reaching maximal levels at the antral stage of development. The immunoreactivity for PCNA, Xiap, and Hiap-2 decreased markedly in atretic (TUNEL-positive) follicles at the small to medium sized antral stage of development, suggesting follicular atresia may be associated with decreased granulosa cell IAP protein content and decreased proliferation. Atresia was also associated with a change in the intracellular distribution of IAPs in granulosa cells. Biochemical analysis of DNA fragmentation (DNA ladder) in granulosa cells from preantral and early antral follicles indicates extensive apoptosis that was associated with minimal IAP protein content. Gonadotropin treatment increased Hiap-2 and Xiap protein content and suppressed apoptosis in granulosa cells, resulting in the development of follicles to the antral and preovulatory stages. In addition, gonadotropin withdrawal induced apoptotic DNA fragmentation in granulosa cells in early antral and antral follicles, which is accompanied by a marked decrease in Hiap-2 and Xiap expression. These data suggest that IAPs may be involved in the suppression of granulosa cell apoptosis by gonadotropin in small to medium-sized antral follicles and play an important role in determining the fate of the cells, and thus also the eventual follicular destiny (atresia vs. ovulation).