The Effect of Injury Severity on Behavioral Tasks Used for the Assessment of Cognitive Functioning Following Traumatic Brain Injury

Cognitive impairment is the most frequent cause of disability in humans following traumatic brain injury (TBI), yet the behavioral tasks used to assess cognitive behavior in rodent models of brain injury are underrepresented in the field. Additionally, few of these tasks have been used to assess behavior across degrees of injury severity. The goal of the present study was to compare four behavioral tasks commonly used in the field in frontally-injured rats with both mild and moderate-to-severe brain injuries. At the start of the study, rats were assigned to two of the following behavioral tasks: Dig scent discrimination (Dig) task, novel object recognition (NOR) task, Morris water maze (MWM), and passive avoidance (PA) task. Four days prior to injury, Dig rats were trained to dig in unscented sand and MWM rats were trained to locate a hidden platform positioned in the northeast quadrant of the MWM. Following training, bilateral controlled cortical impact injuries were induced (mild bilateral frontal TBI, moderate-to-severe bilateral frontal TBI, or non-injured, sham). Following a seven day recovery period, rats were tested on the two assigned behavioral tasks. Following testing, linear mixed effects modeling was performed assessing performance differences on the four tasks as a function of injury (injured vs. non-injured), injury severity (mild TBI vs. moderate-to-severe TBI), and task interaction. The results indicated that, while all four behavioral tasks were effective at assessing injury, some of the tasks were more effective at differentiating between injury severities than others. Specifically, the Dig task and MWM were effective at differentiating between rats with mild TBIs and rats with moderate-to-severe TBIs. Interactions between tasks also occurred such that Dig rats also assigned to the NOR task had significantly higher learning curves on the scent discriminations. The results from the current study indicate that all four behavioral tasks have the potential to assess cognitive impairment after TBI. However, these results are only a beginning. More work is needed before we can fully understand the efficacy of each of these tasks as behavioral assessment measures for cognitive functioning after TBI

ApoA-I Deficiency Increases Cortical Amyloid Deposition, Cerebral Amyloid Angiopathy, Cortical and Hippocampal Astrogliosis, and Amyloid-associated Astrocyte Reactivity in APP/PS1 Mice

Background Alzheimer’s disease (AD) is defined by amyloid beta (Aβ) plaques and neurofibrillary tangles and characterized by neurodegeneration and memory loss. The majority of AD patients also have Aβ deposition in cerebral vessels known as cerebral amyloid angiopathy (CAA), microhemorrhages, and vascular co-morbidities, suggesting that cerebrovascular dysfunction contributes to AD etiology. Promoting cerebrovascular resilience may therefore be a promising therapeutic or preventative strategy for AD. Plasma high-density lipoproteins (HDL) have several vasoprotective functions and are associated with reduced AD risk in some epidemiological studies and with reduced Aβ deposition and Aβ-induced inflammation in 3D engineered human cerebral vessels. In mice, deficiency of apoA-I, the primary protein component of HDL, increases CAA and cognitive dysfunction, whereas overexpression of apoA-I from its native promoter in liver and intestine has the opposite effect and lessens neuroinflammation. Similarly, acute peripheral administration of HDL reduces soluble Aβ pools in the brain and some studies have observed reduced CAA as well. Here, we expand upon the known effects of plasma HDL in mouse models and in vitro 3D artery models to investigate the interaction of amyloid, astrocytes, and HDL on the cerebrovasculature in APP/PS1 mice. Methods APP/PS1 mice deficient or hemizygous for Apoa1 were aged to 12 months. Plasma lipids, amyloid plaque deposition, Aβ protein levels, protein and mRNA markers of neuroinflammation, and astrogliosis were assessed using ELISA, qRT-PCR, and immunofluorescence. Contextual and cued fear conditioning were used to assess behavior. Results In APP/PS1 mice, complete apoA-I deficiency increased total and vascular Aβ deposition in the cortex but not the hippocampus compared to APP/PS1 littermate controls hemizygous for apoA-I. Markers of both general and vascular neuroinflammation, including Il1b mRNA, ICAM-1 protein, PDGFRβ protein, and GFAP protein, were elevated in apoA-I-deficient APP/PS1 mice. Additionally, apoA-I-deficient APP/PS1 mice had elevated levels of vascular-associated ICAM-1 in the cortex and hippocampus and vascular-associated GFAP in the cortex. A striking observation was that astrocytes associated with cerebral vessels laden with Aβ or associated with Aβ plaques showed increased reactivity in APP/PS1 mice lacking apoA-I. No behavioral changes were observed. Conclusions ApoA-I-containing HDL can reduce amyloid pathology and astrocyte reactivity to parenchymal and vascular amyloid in APP/PS1 mice

PepShell : visualization of conformational proteomics data

Proteins are dynamic molecules; they undergo crucial conformational changes induced by post-translational modifications and by binding of cofactors or other molecules. The characterization of these conformational changes and their relation to protein function is a central goal of structural biology. Unfortunately, most conventional methods to obtain structural information do not provide information on protein dynamics. Therefore, mass spectrometry-based approaches, such as limited proteolysis, hydrogen-deuterium exchange, and stable-isotope labeling, are frequently used to characterize protein conformation and dynamics, yet the interpretation of these data can be cumbersome and time consuming. Here, we present PepShell, a tool that allows interactive data analysis of mass spectrometry-based conformational proteomics studies by visualization of the identified peptides both at the sequence and structure levels. Moreover, PepShell allows the comparison of experiments under different conditions, including different proteolysis times or binding of the protein to different substrates or inhibitors

Belgian rare diseases plan in clinical pathology : identification of key biochemical diagnostic tests and establishment of reference laboratories and financing conditions

BackgroundOne objective of the Belgian Rare Diseases plan is to improve patients' management using phenotypic tests and, more specifically, the access to those tests by identifying the biochemical analyses used for rare diseases, developing new financing conditions and establishing reference laboratories.MethodsA feasibility study was performed from May 2015 until August 2016 in order to select the financeable biochemical analyses, and, among them, those that should be performed by reference laboratories. This selection was based on an inventory of analyses used for rare diseases and a survey addressed to the Belgian laboratories of clinical pathology (investigating the annual analytical costs, volumes, turnaround times and the tests unavailable in Belgium and outsourced abroad). A proposal of financeable analyses, financing modalities, reference laboratories' scope and budget estimation was developed and submitted to the Belgian healthcare authorities. After its approval in December 2016, the implementation phase took place from January 2017 until December 2019.ResultsIn 2019, new reimbursement conditions have been published for 46 analyses and eighteen reference laboratories have been recognized. Collaborations have also been developed with 5 foreign laboratories in order to organize the outsourcing and financing of 9 analyses unavailable in Belgium.ConclusionsIn the context of clinical pathology and rare diseases, this initiative enabled to identify unreimbursed analyses and to meet the most crucial financial needs. It also contributed to improve patients' management by establishing Belgian reference laboratories and foreign referral laboratories for highly-specific analyses and a permanent surveillance, quality and financing framework for those tests

Protein identification based on matrix assisted laser desorption/ionization-post source decay-mass spectrometry.

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