Social Stress Alters Inhibitory Synaptic Input to Distinct Subpopulations of Raphe Serotonin Neurons

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Retrieval of contextual memories increases activity-regulated cytoskeleton-associated protein in the amygdala and hippocampus

Activity-regulated cytoskeleton-associated protein (Arc) integrates information from multiple intracellular signaling cascades and, in turn, regulates cytoskeletal proteins involved in structural synaptic modifications. The purposes of the present study were: (1) to determine if the retrieval of contextual memories would induce Arc in hippocampal and amygdalar neurons; (2) use unbiased stereology at the ultrastructural level to quantify synapses contacting Arc-labeled (Arc+) and unlabeled (Arc?) postsynaptic structures in brain regions in which the amount of Arc integrated density (ID) correlated strongly with the degree of amphetamine conditioned place preference (AMPH CPP). The retrieval of contextual memories increased the Arc ID in the dentate gyrus, cornu ammonis (CA)1, and CA3 fields of the hippocampus and the basolateral, lateral, and central nuclei of the amygdala but not the primary auditory cortex, a control region. Stereological quantification of Arc+ and Arc? synapses in the basolateral nucleus of the amygdala (BLA) was undertaken because the strongest relationship between the amount of Arc ID and AMPH CPP was observed in the BLA. The retrieval of contextual memories increased the number and density of asymmetric (presumed excitatory) synapses contacting Arc+ spines and dendrites of BLA neurons, symmetric (presumed inhibitory or modulatory) synapses contacting Arc+ dendrites of BLA neurons, and multisynaptic boutons contacting Arc+ postsynaptic structures. Thus, the retrieval of contextual memories increases Arc in the amygdala and hippocampus, an effect that could be important for approach behavior to a drug-associated context.     

Human tooth germ stem cell response to calcium-silicate based endodontic cements

Objective

The aim of this study was to compare the cytotoxic effects of endodontic cements on human tooth germ stem cells (hTGSCs). MTA Fillapex, a mineral trioxide aggregate (MTA)-based, salicylate resin containing root canal sealer, was compared with iRoot SP, a bioceramic sealer, and AH Plus Jet, an epoxy resin-based root canal sealer.

Material and Methods

To evaluate cytotoxicity, all materials were packed into Teflon rings (4 mmµ3 mm) and co-cultured with hTGSCs with the aid of 24-well Transwell permeable supports, which had a pore size of 0.4 µm. Coverslips were coated with MTA Fillapex, iRoot SP and AH Plus Jet and each coverslip was placed onto the bottom of one well of a six-well plate for scanning electron microscopy (SEM) analysis. Before the cytotoxicity and SEM analysis, all samples were stored at 37ºC and at 95% humidity and 5% CO₂ for 24 hours to set. The cellular viability was analyzed using MTS test (3-(4,5-dimethyl-thiazol-2-yl)-5-(3-carboxy-methoxy-phenyl)-2-(4-sulfo-phenyl)-2H-tetrazolium). The cytotoxic effects and SEM visualization of the tested materials were analyzed at 24-hour, 72-hour, one-week and two-week periods.

Results

On the 1^st day, only MTA Fillapex caused cytotoxicity compared to negative control (NC) group (p<0.008). No significant difference was observed between the other tested materials at this period (p>0.05). After 14 days of incubation with the test materials, MTA Fillapex exhibited significantly higher cytotoxicity compared with iRoot SP, AH Plus Jet and the NC group (P<0.008). In the SEM analysis, the highest levels of cell attachment were observed for iRoot SP and the control group. After 24 hours, MTA Fillapex reduced the number of cells attached to the surface.

Conclusions

Within the limitations of this study, sealers exerted different cytotoxic effects on hTGSCs. Although all materials have exerted cellular toxicity, iRoot SP and AH Plus Jet may promote better attachment to hTGSCs.     

A profile of the Youth Olympic Taekwondo Athlete

Our study aims to identify trends in anthropomorphic attributes and competitive strategies of successful (medalists) versus non medalist young Olympic Taekwondo competitors by gender in terms of body mass, body-mass index (BMI) and fighting technique at the Youth Olympic Games 2010. Results were then compared to adult Taekwondo Olympic athletes in 2000, 2004 and 2008. Data on 96 Taekwondo athletes were obtained from the official Youth Olympic website. A LOGIT analysis was performed on the following six independent variables: height, body mass, body mass index, gender, techniques used to score, and warnings obtained during a match. The study did find some differences between winners and non-winners for males and female, although none of the differences were statistically significant. Consequently, training personnel may enhance winning potential of Taekwondo competitors by focusing on offensive versus defensive techniques and improving the quality of punching.     

Waiting time for transfer of patients with prostaglandin dependant congenital heart defects to tertiary cardiac centers

Worldwide congenital heart defects (CHD) are the leading cause of infant deaths owing to congenital anomalies. Delay in diagnosing and operating in neonates with prostaglandin dependant CHD may lead to significant morbidity and mortality.Objectives: To assess the time interval needed for acceptance and transfer of patients with critical CHD to a tertiary cardiac center and the impact on the patient’s survival.Study design: Retrospective database reviews of all cases diagnosed to have prostaglandin dependant (PG) CHD at Prince Sultan Cardiac Center-Qassim during a 43 months period (from May 2007 to December 2010).Results: During the study period 104 patients were diagnosed to have PG dependant CHD. Patients with PG dependant systemic circulation constitute 60% of patients. Patients with ventricular septal defect (VSD) associated with coarctation of the aorta constituted 16% of patients. The mean waiting time for transfer to a tertiary cardiac center was 10 ± 10 days. Twenty-two (21%) patients died while waiting for acceptance and transfer. Eleven patients were diagnosed with hypoplastic left heart syndrome (HLHS). There was no significant difference in the waiting time for those with or without HLHS, with a mean of 9 days for both. Six of our patients had infections with positive blood cultures. The mean waiting period for those with proved infection was 25 days compared with 8 days for those with no proved infection (p value < 0.005).Conclusion: There are a significant number of patients with severe CHD who die while waiting for acceptance and transfer to a tertiary cardiac center. The causes for delay could be the presence of infection, prematurity and low birth weight. The limited numbers of tertiary cardiac centers in Saudi Arabia as well as cardiac ICU beds are among the factors delaying the acceptance of patients requiring cardiac surgery.