放射線影響による認知機能障害に関するfMRIを用いた研究

学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 久恒 辰博, 東京大学教授 片岡 宏誌, 東京大学教授 福田 健二, 東京大学准教授 尾田 正二, 東京大学准教授 小嶋 徹也University of Tokyo(東京大学

Recent Research Progress in the Applied Microbiology Laboratory : Enzymes, Toxins and Cell-Envelope Structure of Environmental and Pathogenic Bacteria(Recent Topics of the Agricultunal Biological Science in Tohoku University)

Here we describe the current status of our studies of xylanases of Paenibacillus sp. W-61, poly (D-lactic acid) hydrolases of Amycolatopsis sp. K104-1 and Brevibacterium sp. 93, pectin lyase of plant pathogenic Pectobacterium carotovora and bi-component toxins of Staphylococcus aureus. Paenibacillus sp. W-61 utilizes xylan as a carbon source via three enzymes, of which Xyn5 plays a crucial role both in xylan utilization and in the synthesis of the other two xylanases. Understanding the roles of each xylanase in xylan degradation will help to develop an enzymatic preparation of xylose from xylan. The poly (D-lactic acid) [PLA] hydrolases of Amycolatopsis sp. K104-1 and Brevibacterium sp. 93 appear to be novel enzymes with potential for PLA recycling. We recently purified and characterized the PLA hydrolases produced by these bacteria. The plant-soft rotting bacterium P. carotovora produces pectin lyase, a potential pathogenic factor, and a bacteriocin when exposed to DNA-damaging agents. We recently determined the cis-acting regulatory sequences responsible for the DNA-damage-inducible synthesis of the enzyme and bacteriocin. Leukocidin and γ-hemolysin are bi-component toxins that lyse leukocytes and erythrocytes respectively. We describe the molecular structure and pore-forming mechanism of the toxin components encoded by the chromosome and by a phage genome. Finally, we briefly describe the cell-envelope structure of the rumen bacterium Selenomonas ruminantium and its outer membrane protein Mep45 that possibly bridges the outer membrane and the peptidoglycan. The objects of our studies include environmental bacteria (xylanolytic Paenibacillus sp. W-61 and poly (D-lactic acid)-hydrolyzing bacteria Amycolatopsis sp. K104-1 and Brevibacterium sp. 93), as well as the plant and animal pathogens, Pectobacterium carotovora and Staphylococcus aureus, respectively. Here we briefly describe the current status of our investigations into these bacteria, their extracellular enzymes (or toxins), and an outer membrane protein in the rumen bacterium Selenomonas ruminantium subsp. lactilytica. Our research also includes polyglutamate biosynthesis and the degradation enzymes of a Bacillus subtilis Natto starter, acetan (a polysaccharide produced by Acetobacter and Gluconobacter)-degrading enzymes of Paenibacillus sp. and catabolic enzymes of amino acid and polyamine in Pseudomonas aeruginosa PAOl. The topics of these projects are available on our Web site

A Cryptographic Moving-Knife Cake-Cutting Protocol

This paper proposes a cake-cutting protocol using cryptography when the cake is a heterogeneous good that is represented by an interval on a real line. Although the Dubins-Spanier moving-knife protocol with one knife achieves simple fairness, all players must execute the protocol synchronously. Thus, the protocol cannot be executed on asynchronous networks such as the Internet. We show that the moving-knife protocol can be executed asynchronously by a discrete protocol using a secure auction protocol. The number of cuts is n-1 where n is the number of players, which is the minimum.Comment: In Proceedings IWIGP 2012, arXiv:1202.422

Eosinophil Cationic Protein Shows Survival Effect on H9c2 Cardiac Myoblast Cells with Enhanced Phosphorylation of ERK and Akt/GSK-3β under Oxidative Stress

Eosinophil cationic protein (ECP) is well known as a cationic protein contained in the basic granules of activated eosinophils. Recent studies have reported that ECP exhibits novel activities on various types of cells, including rat neonatal cardiomyocytes. Here we evaluated the effects of ECP on rat cardiac myoblast H9c2 cells. Our results showed that ECP enhanced the survival of the cells, in part by promoting the ERK and Akt/GSK-3β signaling pathways. ECP attenuated the cytotoxic effects of H2O2 on H9c2 cells as well as the production of reactive oxygen species, the number of apoptotic cells and caspase 3/7 activity in the cells. In conclusion, ECP activated the ERK and Akt/GSK-3β pathways, resulting in anti-oxidative effects on H9c2 cells that attenuated apoptosis

Perfusion MRI for brain tumors

Purpose : To compare data on brain tumors derived from intravoxel incoherent motion (IVIM) and arterial spin labeling (ASL) imaging with multiple parameters obtained on dynamic susceptibility contrast (DSC) perfusion MRI and to clarify the characteristics of IVIM and ASL perfusion data from the viewpoint of cerebral blood flow (CBF) analysis. Methods : ASL-CBF and IVIM techniques as well as DSC examination were performed in 24 patients with brain tumors. The IVIM data were analyzed with the two models. The relative blood flow (rBF), relative blood volume (rBV) corrected relative blood volume (crBV), mean transit time (MTT), and leakage coefficient (K2) were obtained from the DSC MRI data. Results : The ASL-CBF had the same tendency as the perfusion parameters derived from the DSC data, but the permeability from the vessels had less of an effect on the ASL-CBF. The diffusion coefficient of the fast component on IVIM contained more information on permeability than the f value. Conclusion : ASL-CBF is more suitable for the evaluation of perfusion in brain tumors than IVIM parameters. ASL-CBF and IVIM techniques should be carefully selected and the biological significance of each parameter should be understood for the correct comprehension of the pathological status of brain tumors

Gastric Endocrine Cell Carcinoma with Long-Term Survival Developing Metachronous Remnant Cancer

A rare case of primary gastric endocrine cell carcinoma in a 79-year-old man is reported. Upper gastrointestinal endoscopy showed a large Bormann's type 2 tumour located in the middle of the stomach. On computed tomography, the gastric wall was thickened by the large tumour, and there were no distant metastases. Distal gastrectomy, lymph node dissection, and partial resection of the transverse colon were performed because the tumour involved the transverse mesocolon. The final pathological diagnosis was endocrine cell carcinoma, with tumour infiltration up to the subserous layer. Adjuvant chemotherapy was given, but metachronous remnant gastric cancer developed 2 years after surgery. Endoscopic submucosal dissection was performed for the early 0-IIc type gastric cancer, and the surgical margin was preserved. The patient has survived for 5 years after the primary surgery, remaining disease-free so far

Relationship between Stage of Diabetic Retinopathy and Pulse Wave Velocity in Japanese Patients with Type 2 Diabetes

Objectives. We investigated the relationship between the stage of diabetic retinopathy and pulse wave velocity (PWV). Methods. This was a cross-sectional study of 689 patients (406 men and 283 women) with type 2 diabetes who were admitted to our hospital from 2004 to 2007. Brachial-ankle pulse wave velocity (baPWV) was measured by an arterial pressure measurement device as PWV/ABI. Diagnosis of diabetic retinopathy was made by ophthalmologists based on the Davis classification: no diabetic retinopathy (NDR), simple retinopathy (SDR), pre-proliferative retinopathy (pre-PDR), and proliferative retinopathy (PDR). Results. There was a significant difference in PWV between patients without diabetic retinopathy (1657.0 ± 417.9 m/s (mean ± SD)) and with diabetic retinopathy (1847.1 ± 423.9 m/s) (P < 0.001). In addition, the stage of diabetic retinopathy was associated with aortic PWV (1657.0 ± 417.9 m/s in NDR (n = 420), 1819.4 ± 430.3 m/s in SDR (n = 152), 1862.1 ± 394.0 m/s in pre-PDR (n = 54), and 1901.1 ± 433.5 m/s in PDR (n = 63) (P < 0.001)). Conclusions. In patients with diabetic retinopathy, even in those with SDR, PWV was higher than that in patients without diabetic retinopathy. Physicians should therefore pay attention to the value of PWV and macroangiopathy regardless of the stage of diabetic retinopathy