Role of epac in the pathogenesis of ischemic stroke

Poster Presentations: Theme 2published_or_final_version15th Research Postgraduate Symposium, Hong Kong, China, 1-2 December 2010. In Abstract - Poste Presentations (Theme II) of 15th Research Postgraduate Symposium, 2010, p. 8

EPAC2-deficiency leads to more severe neurological deficit and larger infarct with higher glial reactivity after transient middle cerebral occlusion

Abstract no. 912INTRODUCTION: Exchange proteins activated by cAMP (Epac1 and Epac2) belong to a family of cAMP-regulated guanine nucleotide exchange factors (cAMPGEFs) for the small GTPases, Rap1 and Rap2[1]. Epac1 was thought to be important in maintenance of tight and adhesion junctions between endothelial cells[2] , suggesting that Epac may play an important role in blood brain barrier (BBB) function. OBJECTIVE: Previously, it was shown that Epac2 mRNA is expressed in the brain[3]. Here, the protein expression of Epac2 was determined and compared to that of Epac1. In addition, the role of Epac2 was determined in the BBB and brain function after ischemia/reperfusion injury. METHOD: Six regions of brain from Epac2 wild type (Epac2+/+) mice was dissected, and proteins were extracted in order to determine the expression of Epac1 and Epac2 under normal and …postprintThe 25th International Symosium on Cerebral Blood Flow, Metabolism, and Function & 10th International Conference on Quantification of Brain Function with PET (BRAIN’11 & BRAINPET’11 ), Barcelona, Spain, 25-28 May 2011

Performance of large-size superconducting coil in 0.21T MRI system

A high-temperature superconductor (HTS) was used on magnetic resonance imaging (MRI) receiver coils to improve image quality because of its intrinsic low electrical resistivity [1], [2]. Typical HTS coils are surface coils made of HTS thin-film wafers. Their applications are severely limited by the field of view (FOV) of the surface coil configuration, and the improvement in image quality by HTS coil is also reduced as the ratio of sample noise to coil noise increases. Therefore, previous HTS coils are usually used to image small in vitro samples, small animals, or peripheral human anatomies [3]-[5]. We used large-size HTS coils (2.5-, 3.5-, and 5.5-in mean diameter) to enhance the FOV and we evaluated their performance through phantom and human MR images. Comparisons were made among HTS surface coils, copper surface coils, and cool copper surface coils in terms of the signal-to-noise ratio (SNR) and sensitivity profile of the images. A theoretical model prediction was also used to compare against the experimental result. We then selected several human body parts, including the wrist, feet, and head, to illustrate the advantage of HTS coil over copper coil when used in human imaging. The results show an SNR gain of 200% for 5.5-in HTS coil versus same size copper coils, while for 2.5- and 3.5-in coils it is 250%. We also address the various factors that affect the performance of large size HTS coils, including the coil-to-sample spacing due to cryogenic probe and the coil-loading effect.published_or_final_versio

Floor transfer test for assessing people with chronic stroke

published_or_final_versio

Targeted overexpression of endothelin-1 in astrocytes leads to more severe cytotoxic brain edema and higher mortality

Transgenic mice overexpressing endothelin-1 (ET-1) in astrocytes (GET-1) displayed more severe brain edema and neurologic dysfunction after experimental ischemic stroke. However, it was not clear whether astrocytic ET-1 contributed to cytotoxic or vasogenic edema associated with stroke. In this study, the role of astrocytic ET-1 in cytotoxic edema and brain injury was investigated. Upon acute water intoxication, the GET-1 mice had a lower survival rate and more severe neurologic deficits. Such an exacerbated condition in the GET-1 mice may be a result of a significant increase in cerebral water content and increased expression of the water channel protein, aquaporin 4 (AQP-4). The GET-1 mice treated with OPC-31260, a nonpeptide arginine vasopressin V2 receptor antagonist, were alleviated from the cerebral water accumulation and neurologic deficit during the early time period after water intoxication. In addition, a significant reduction of AQP-4 expression was observed in astrocytic end-feet AQP-4 in the hippocampus of the GET-1 mice treated with OPC-31260. Therefore, ET-1-induced AQP-4 expression and cerebral water accumulation are the key factors in brain edema associated with acute water intoxication. The V 2 receptor antagonist, OPC-31260, may be one of the effective drugs for the early treatment of ET-1-induced cytotoxic edema and brain injury. © 2009 ISCBFM All rights reserved.link_to_subscribed_fulltex

Glucose-dependent insulinotropic polypeptide gene expression in the stomach: Revealed by a transgenic mouse study, in situ hybridization and immunohistochemical staining

Glucose-dependent insulinotropic polypeptide (GIP) plays an important role in stimulating insulin release in the pancreas as well as inhibiting gastric acid secretion in the stomach. GIP has been found in specific endocrine cells located in the mucosal layer of the small intestine and in the submandibular salivary gland. In this study, the tissue-specific expression of GIP guided by 1.2 kb of the human GIP (hGIP) gene 5' flanking region was investigated by a transgenic mouse approach. A chimeric promoter-reporter gene construct linking the 5'-flanking region of the hGIP gene with the thymidine kinase gene of the herpes simplex virus was introduced into the genomes of mice by microinjection. By reverse transcriptase-PCR (RT-PCR) and thymidine kinase assays, transgene expression was found in the stomach and pancreas. The enzyme activity detected in the stomach was about 6-fold higher than that found in the pancreas, suggesting that GIP may be expressed in the stomach. This observation is supported by RT-PCR studies since both human and mouse GIP transcripts are detected in the stomach and small intestine. In addition, distinct GIP-producing cells were identified in both tissues in mouse by in situ hybridization and immunohistochemical staining. Taken together, our data demonstrate for the first time that GIP is expressed in human and mouse stomach. Copyright (C) 1999 Elsevier Science Ireland Ltd.link_to_subscribed_fulltex

Floor Transfer Test for assessing people with chronic stroke

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