震災復旧・復興におけるソーシャル・キャピタルの役割についての経済学的分析 -日本の事例にもとづく実証分析と東日本大震災への政策含意

早大学位記番号:新6729早稲田大

Use of the Metropolis algorithm to simulate the dynamics of protein chains

The Metropolis implementation of the Monte Carlo algorithm has been developed to study the equilibrium thermodynamics of many-body systems. Choosing small trial moves, the trajectories obtained applying this algorithm agree with those obtained by Langevin's dynamics. Applying this procedure to a simplified protein model, it is possible to show that setting a threshold of 1 degree on the movement of the dihedrals of the protein backbone in a single Monte Carlo step, the mean quantities associated with the off-equilibrium dynamics (e.g., energy, RMSD, etc.) are well reproduced, while the good description of higher moments requires smaller moves. An important result is that the time duration of a Monte Carlo step depends linearly on the temperature, something which should be accounted for when doing simulations at different temperatures.Comment: corrections to the text and to the figure

Underwater robotic suturing

Background Laparoscopic and robotic surgeries have become popular, and this popularity is increasing. However, the environment in which such surgeries are performed is rarely discussed. Similar to arthrosurgery performed in water, artificial ascites could be a new environment for laparoscopic surgery. This study was performed to determine whether robotic surgery is applicable to complicated suturing underwater. Material and methods A da Vinci Surgical System S was used. A weighted fabric sheet was placed at the bottom of a tank. Identical sets were made for each environment: One tank was dry, and the other was filled with water. The suturing task involved placement of a running silk suture around the perimeter of a small circle. The task was performed eight times in each environment. The task time and integrity score were determined. The integrity score was calculated by evaluating accuracy, tightness, thread damage, and uniformity; each factor was evaluated using a five-point scale. Results Although statistically significant differences were not shown in either task time or integrity score between the underwater and air environments, robotic suturing underwater is not inferior to performance in air. Conclusions The feasibility of robotic suturing underwater was confirmed under the herein-described experimental conditions. © 2016 Taylor & FrancisEmbargo Period 12 month

Saline-filled laparoscopic surgery: A basic study on partial hepatectomy in a rabbit model

Background: There is still a poor understanding of the effects of pneumoperitoneum with insufflation of carbon dioxide gas (CO2) on malignant cells, and pneumoperitoneum has a negative impact on cardiopulmonary responses. A novel saline-filled laparoscopic surgery (SAFLS) is proposed, and the technical feasibility of performing saline-filled laparoscopic partial hepatectomy (LPH) was evaluated in a rabbit model. Material and methods: Twelve LPH were performed in rabbits, with six procedures performed using an ultrasonic device with CO2 pneumoperitoneum (CO2 group) and six procedures performed using a bipolar resectoscope (RS) in a saline-filled environment (saline group). Resection time, CO2 and saline consumption, vital signs, blood gas analysis, complications, interleukin-1 beta (IL-1β) and C-reactive protein (CRP) levels were measured. The effectiveness of the resections was evaluated by the pathological findings. Results: LPH was successfully performed with clear observation by irrigation and good control of bleeding by coagulation with RS. There were no significant differences in all perioperative values, IL-1βand CRP levels between the two groups. All pathological specimens of the saline group showed that the resected lesions were coagulated and regenerated as well as in the CO2 group. Conclusions: SAFLS is feasible and provides a good surgical view with irrigation and identification of bleeding sites. © 2014 Informa Healthcare

Simulation, Experiment, and Evolution: Understanding Nucleation in Protein S6 Folding

In this study, we explore nucleation and the transition state ensemble of the ribosomal protein S6 using a Monte Carlo Go model in conjunction with restraints from experiment. The results are analyzed in the context of extensive experimental and evolutionary data. The roles of individual residues in the folding nucleus are identified and the order of events in the S6 folding mechanism is explored in detail. Interpretation of our results agrees with, and extends the utility of, experiments that shift f-values by modulating denaturant concentration and presents strong evidence for the realism of the mechanistic details in our Monte Carlo Go model and the structural interpretation of experimental f-values. We also observe plasticity in the contacts of the hydrophobic core that support the specific nucleus. For S6, which binds to RNA and protein after folding, this plasticity may result from the conformational flexibility required to achieve biological function. These results present a theoretical and conceptual picture that is relevant in understanding the mechanism of nucleation in protein folding.Comment: PNAS in pres

Laparoscopic pancreaticoduodenectomy after endovascular repair for abdominal aortic aneurysm

INTRODUCTION Most gastroenterological surgeries, even pancreatic surgery, can now be performed laparoscopically. However, the management of concomitant abdominal aortic aneurysm (AAA) and intra-abdominal malignancy is controversial. The performance of endovascular repair (EVAR) for AAA has been increasing; however, there is no report of laparoscopic pancreaticoduodenectomy after EVAR. PRESENTATION OF CASE A pancreatic tumor was detected during follow-up after EVAR for AAA. The enlarging tumor was diagnosed as an intraductal papillary mucinous tumor with a nodule. Laparoscopic pancreaticoduodenectomy was safely performed. After laparoscopic dissection around the pancreas head, an additional incision was made in the upper abdomen, and pancreatic reconstruction was performed through the incision. In spite of grade B pancreatic fistulae, the patient recovered with medical therapy. The pathological diagnosis was intraductal papillary mucinous adenoma with small foci of carcinoma in situ. The patient has been well with neither recurrence of the tumor nor any cardiovascular events for 18 months. DISCUSSION The management of concomitant malignancy and AAA is challenging, especially in patients with a pancreatic tumor. The reasons for the rarity of treatment include prognosis, anatomical vicinity, and postoperative complications. EVAR reduces retroperitoneal adhesions. A laparoscopic approach provides a small operative field and decreases mutual interference with AAA. Moreover, reconstruction is performed through an upper abdominal incision apart from the AAA. Hand-sewing provides more reliable stability of the anastomosis. CONCLUSION The increasing frequency of performance of EVAR for AAA and subsequent computed tomography may help to detect malignancy. Laparoscopic surgery appears to be a valid approach to malignancy after EVAR. © 2013 The Authors

Insights from Coarse-Grained Gō Models for Protein Folding and Dynamics

Exploring the landscape of large scale conformational changes such as protein folding at atomistic detail poses a considerable computational challenge. Coarse-grained representations of the peptide chain have therefore been developed and over the last decade have proved extremely valuable. These include topology-based Gō models, which constitute a smooth and funnel-like approximation to the folding landscape. We review the many variations of the Gō model that have been employed to yield insight into folding mechanisms. Their success has been interpreted as a consequence of the dominant role of the native topology in folding. The role of local contact density in determining protein dynamics is also discussed and is used to explain the ability of Gō-like models to capture sequence effects in folding and elucidate conformational transitions

Klotho and the Aging Process

The klotho gene was originally identified as a putative age-suppressing gene in mice that extends life span when overexpressed. It induces complex phenotypes resembling human premature aging syndromes when disrupted. The gene was named after a Greek goddess Klotho who spun the thread of life. Since then, various functional aspects of the klotho gene have been investigated, leading to the identification of multiple novel endocrine axes that regulate various metabolic processes and an unexpected link between mineral metabolism and aging. The purposes of this review were to overview recent progress on Klotho research and to discuss a novel aging mechanism