4,434 research outputs found
Comparative analysis of Mycobacterium tuberculosis pe and ppe genes reveals high sequence variation and an apparent absence of selective constraints.
No full textContains fulltext :
110619.pdf (Publisher’s version ) (Open Access)Mycobacterium tuberculosis complex (MTBC) genomes contain 2 large gene families termed pe and ppe. The function of pe/ppe proteins remains enigmatic but studies suggest that they are secreted or cell surface associated and are involved in bacterial virulence. Previous studies have also shown that some pe/ppe genes are polymorphic, a finding that suggests involvement in antigenic variation. Using comparative sequence analysis of 18 publicly available MTBC whole genome sequences, we have performed alignments of 33 pe (excluding pe_pgrs) and 66 ppe genes in order to detect the frequency and nature of genetic variation. This work has been supplemented by whole gene sequencing of 14 pe/ppe (including 5 pe_pgrs) genes in a cohort of 40 diverse and well defined clinical isolates covering all the main lineages of the M. tuberculosis phylogenetic tree. We show that nsSNP's in pe (excluding pgrs) and ppe genes are 3.0 and 3.3 times higher than in non-pe/ppe genes respectively and that numerous other mutation types are also present at a high frequency. It has previously been shown that non-pe/ppe M. tuberculosis genes display a remarkably low level of purifying selection. Here, we also show that compared to these genes those of the pe/ppe families show a further reduction of selection pressure that suggests neutral evolution. This is inconsistent with the positive selection pressure of "classical" antigenic variation. Finally, by analyzing such a large number of genes we were able to detect large differences in mutation type and frequency between both individual genes and gene sub-families. The high variation rates and absence of selective constraints provides valuable insights into potential pe/ppe function. Since pe/ppe proteins are highly antigenic and have been studied as potential vaccine components these results should also prove informative for aspects of M. tuberculosis vaccine design
Spatiotemporal characterization of brain infarction by sequential multimodal MR imaging following transient focal ischemia in a Rat model of intra-arterial middle cerebral artery occlusion
No full textObjectives To assess spatiotemporal brain infarction evolu- tion by sequential multimodal magnetic resonance (MR) im- aging in an endovascular model of acute stroke in rats. Materials and methods A microwire was selectively placed in the middle cerebral artery (MCA) in 16 consecutives rats dur- ing 90 minutes occlusion. Longitudinal 7-T MR imaging, in- cluding angiography, diffusion, and perfusion was performed during ischemia, immediately after reperfusion, 3 h and 24 h after subsequent reperfusion.
Results MCA occlusion was complete in 75 % and partial in 18.7 %. Hypoperfusion (mean ± SD) was observed in all ani- mals during ischemia (-59 ± 18 % of contralateral hemisphere, area 31±5 mm2). Infarction volume (mean±SD) was 90 ± 64 mm3 during ischemia and 57 ± 67 mm3 at 24 h. Brain infarction was fronto-parietal cortical in five animals (31 %), striatal in four animals (25 %), and cortico-striatal in seven animals (44 %) at 24 h. All rats survived at 24 h.
Conclusion This model is suitable to neuroprotection studies because of possible acute and close characterization of spatio- temporal evolution of brain infarction by MR imaging
techniques, and evidence of ischemic penumbra, the target of neuroprotection agents. However, optimization of the brain infarct reproducibility needs further technical and neurointerventional tools improvements.
Key points
• Nitinol microwire is MRI compatible allowing spatiotempo-
ral characterization of brain infarction in rats.
• Microwire selective placement in middle cerebral artery al-
lows complete artery occlusion in 75 %.
• A diffusion/perfusion mismatch during arterial occlusion is
observed in 77 % of rats
Hemodynamics, inflammation, vascular remodeling, and the development and rupture of intracranial aneurysms: a review
No full textThe central nervous system is an immunologically active environment where several components of the immune and inflammatory response interact among them and with the constituents of nervous tissue and vasculature in a critically orchestrated manner, influencing physiologic and pathologic processes. In particular, inflammation takes a central role in the pathogenesis of intracranial aneurysms (IAs). The common pathway for aneurysm formation involves endothelial dysfunction and injury, a mounting inflammatory response, vascular smooth muscle cells (VSMCs) phenotypic modulation, extracellular matrix remodeling, and subsequent cell death and vessel wall degeneration. We conducted a literature review (1980-2014) by Medline and EMBASE databases using the searching terms “IA” and “cerebral aneurysm” and further search was performed to link the search terms with the following key words: inflammation, hemodynamic(s), remodeling, macrophages, neutrophils, lymphocytes, complement, VSMCs, mast cells, cytokines, and inflammatory biomarkers. The aim of this review was to summarize the most recent and pertinent evidences regarding the articulated processes of aneurysms formation, growth, and rupture. Knowledge of these processes may guide the diagnosis and treatment of these vascular malformations, the most common cause of subarachnoid hemorrhage, which prognosis remains dismal
DWI lesions reversal in posterior circulation stroke after reperfusion: Two illustrative cases and review of the literature
No full textIn acute stroke, diffusion-weighted imaging (DWI) lesions are commonly considered markers of irreversible ischemia, and accurate assessment of DWI lesion volume is crucial in order to establish cutoffs above which reperfusion may not be beneficial. However, some case reports have suggested DWI lesion reversal after reperfusion in posterior circula- tion. We present two cases of brainstem and cerebellar DWI lesions’ reversal after intravenous thrombolysis, and sum- marize currently available data on this issue
Ethylene vinyl alcohol copolymer (Onyx®) embolization of cranial dural arteriovenous fistula via the ascending pharyngeal artery.
No full textTreatment of ruptured cranial dural arteriovenous fis- tula (DAVF) is mandatory, and the therapeutic goal is to occlude the proximal draining vein and the site of the fistula itself, which may be achieved by surgery or endovascular embolization [1]. Endovascular embolization has become the primary treatment of intracranial DAVFs, however, the presence of an access as close to the site of the fistula as possible remains a primary concern for a successful endovas- cular treatment. We present a patient who had a safe, complete and successful embolization of a posterior fossa DAVF via the ascending pharyngeal artery (APA) and summa- rize currently available data on this specific approach
On minimal non-PE-groups
No full textAbstractIf H is a subgroup of a finite group G, by HG denote the normal closure of H in G. G is called a PE-group if every minimal subgroup X of G satisfies NG(X) ∩ XG = X. The author proves that all PE-groups are solvable with the Fitting height at most 3 and classifies the minimal non-PE-groups
Endovascular treatment of bifurcation intracranial aneurysms with the WEB SL/SLS: 6-month clinical and angiographic results
No full textBackground: The WEB device is a recent intrasaccular flow disruption technique developed for the treatment of wide-necked intracranial aneurysms. To date, a single report on the WEB Single-Layer (SL) treatment of intracranial aneurysms has been published with 1-months’ safety results. The aim of this study is to report our experience and 6-month clinical and angiographic follow-up of endovascular treatment of wide-neck aneurysm with the WEB SL.
Methods: Ten patients with 10 unruptured wide-necked aneurysms were prospectively enrolled in this study. Feasibility, intraoperative and postoperative complications, and outcomes were recorded. Immediate and 6-month clinical and angio- graphic results were evaluated.
Results: Failure of WEB SL placement occurred in two cases. Eight aneurysms were successfully treated using one WEB SL without additional treatment. Three middle cerebral artery, four anterior communicating artery, and one basilar artery aneurysms were treated. Average dome width was 7.5 mm (range 5.4–10.7 mm), and average neck size was 4.9 mm (range 2.6–6.5 mm). No periprocedural complication was observed, and morbi-mortality at discharge and 6 months was 0.0%. Angiographic follow-up at 6 months demonstrated complete aneurysm occlusion in 2/8 aneurysms, neck remnant in 5/8 aneurysms, and aneurysm remnant in 1/8 aneurysm.
Conclusions: From this preliminary study, treatment of bifurcation intracranial aneurysms using WEB SL is feasible. WEB SL treatment seems safe at 6 months; however, the rate of neck remnants is not negligible due to compression of the WEB SL. Further technical improvements may be needed in order to ameliorate the occlusion in the WEB SL treatment
[[alternative]]The Study of Acknowledgement of Risk Management on Perception of PE Teachers in Taoyuan Junior High Schools
No full text[[abstract]]The purpose of this study was to (1) explore the acknowledgement about physical activity risk management of junior high school PE teachers in Taoyuan, (2) compare PE teachers’ perception difference about risk management with different background (3) realize the strategy of risk management plan of PE teachers in junior high school. (4) finally build effective risk management plan for all PE teachers in junior high school.
One hundred and ninety two Taoyuan PE teachers served as the subjects of this study with the questionnaire of ” PE Teacher’s Perception of The Risk Management”. This study used descriptive statistics, t-test, and one-way ANOVA to analyze data. Besides, the research also chose seven PE teachers to do semi-structured interview, trying to understand risk management strategy of PE teachers. The results were listed as below:
1.The perception of risk management of physical teachers in junior high school, based on the importance, was: theory layer, practical layer, law layer, entity and application layer.
2.Significant difference was found in gender, practical layer, law layer and entity; while other factors showed no significant difference.
3.All the interviewees didn’t take action about risk management , but all of them agreed that risk management plan of physical activity is necessary. They suggested higher authorities ask junior high school to set risk management plan for physical activity, and become an evaluated item.
In conclusion of the research, the PE teachers in junior high school think it is important to execute a better physical activity risk management. Author suggested junior high school should set risk management plan for physical activity to get “zero risk” in school.
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