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Search Results: 1 - 10 of 1834 matches for " Keita Hayashi "
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The Effective Catalyst (Cobalt Salt/Lewis Acid) for Beckmann Rearrangement of Cycloalkanone Oximes to Lactams under Mild Conditions  [PDF]
Masahiro Komeda, Ayana Ozaki, Keita Hayashi, Michinori Sumimoto, Kenji Hori, Tsunemi Sugimoto, Hidetoshi Yamamoto
International Journal of Organic Chemistry (IJOC) , 2015, DOI: 10.4236/ijoc.2015.52007
Abstract: The Beckmann rearrangement of cyclohexanone oxime was achieved by the combined use of cobalt salt and Lewis acids co-catalysts (each 10 mol%). Various combinations of cobalt salts and Lewis acids gave lactams in a satisfactory yield under mild conditions. This method makes it possible to reduce undesirable byproducts.
Active Targeting to Osteosarcoma Cells and Apoptotic Cell Death Induction by the Novel Lectin Eucheuma serra Agglutinin Isolated from a Marine Red Alga
Keita Hayashi,Peter Walde,Tatsuhiko Miyazaki,Kenshi Sakayama
Journal of Drug Delivery , 2012, DOI: 10.1155/2012/842785
Enhanced Cytotoxicity for Colon 26 Cells Using Doxorubicin-Loaded Sorbitan Monooleate (Span 80) Vesicles
Keita Hayashi, Tsuyoshi Tatsui, Toshinori Shimanouchi, Hiroshi Umakoshi
International Journal of Biological Sciences , 2013,
Abstract: Span 80 (sorbitan monooleate) vesicles behaved differently from conventional phospholipid vesicles (liposomes) because the former had a more fluid interface. After doxorubicin hydrochloride (DOX) was encapsulated into the Span 80 vesicle (loading efficiency: 63 %), DOX-loaded Span 80 vesicles (DVs) were thereafter added to Colon 26 cells. It was suggested, from the flow cytometric analysis and confocal laser microscopic observation, that DVs directly deliver DOX into the cytoplasm of Colon 26 cells. DVs showed the different delivery manner from the DOX-loaded liposomes (DLs). It is considered that the difference of delivery manner between DVs and DLs resulted in the difference of cytotoxicity (IC50); i.e. IC50 values for DVs and DLs were 5 and > 30 μM, respectively. The results obtained herein would give the fundamental findings which can contribute to the improvement of formulation of conventional liposome-based carrier and its cytotoxicity.
Note on a Continuum Multi-Country and International Trade  [PDF]
Keita Kamei
Theoretical Economics Letters (TEL) , 2012, DOI: 10.4236/tel.2012.22040
Abstract: We provide an analytical solution for the continuum multi-country two-sector Ricardian model of Yanagawa (1996) [1], and obtain additional results that are not observed in the standard two-country two-good Ricardian model. Increases in productivity in each sector results in an increase in the number of countries producing high technology goods and a de- crease in the number of countries producing low technology goods.
Blow Flies Were One of the Possible Candidates for Transmission of Highly Pathogenic H5N1 Avian Influenza Virus during the 2004 Outbreaks in Japan
Kyoko Sawabe,Keita Hoshino,Haruhiko Isawa,Toshinori Sasaki,Kyeong Soon Kim,Toshihiko Hayashi,Yoshio Tsuda,Hiromu Kurahashi,Mutsuo Kobayashi
Influenza Research and Treatment , 2011, DOI: 10.1155/2011/652652
Abstract: The 2003-2004 H5N1 highly pathogenic avian influenza (HPAI) outbreaks in Japan were the first such outbreaks in 79 years in Japan. Epidemic outbreaks have been occurring in Southeast Asia, with the most recent in 2010. Knowledge of the transmission route responsible for the HPAI outbreaks in these countries remains elusive. Our studies strongly suggested that field and laboratory studies focusing on mechanical transmission by blow flies should be considered to control H5N1 avian influenza outbreaks, in particular in epidemic areas, where there are high densities of different fly species throughout the year. In this paper, we review these field and laboratory entomological studies and discuss the possibility of blow flies transmitting H5N1 viruses. 1. Avian Influenza Outbreaks in Japan The H5N1 subtype of highly pathogenic avian influenza (HPAI) A virus has frequently infected wild and domestic ducks in Asia, causing huge economic damage to both poultry farms and governments in the affected countries. Most avian influenza viruses do not infect humans, but the 1997 outbreak of the H5N1 virus in Hong Kong [1, 2] alerted the medical community that some subtypes of avian influenza viruses include highly pathogenic strains that can affect humans. In this influenza virus outbreak, there were 6 deaths in the 18 human cases caused by the H5N1 subtype [3]. As of August 2, 2010, WHO has identified 502 human cases of H5N1 influenza around the world, and 298 of these were fatal [4]. In particular, H5N1 outbreaks have occurred recently in Egypt, Indonesia, and Vietnam. Therefore, H5N1 influenza virus can cause serious public health problems in birds and humans and is one of the most infectious avian diseases transmissible to humans. From January 2004 to March 2004, there were outbreaks of acute, highly transmissible, lethal diseases in chickens at four poultry farms in Japan: one in Oita, one in Yamaguchi, and two in Kyoto Prefecture (Figure 1). Virus isolates from infected chickens were all identified as influenza A virus of the H5N1 subtype [5]. Such highly pathogenic avian influenza (HPAI) epidemics had not been reported in Japan for 79 years. Two avian influenza outbreaks at poultry farms in Tamba Town, Kyoto Prefecture, were the last two outbreaks of the 2004 avian epidemics in Japan. Since then, there were outbreaks of H5N1 avian influenza in Okayama and Miyazaki Prefectures in 2007. The H5N1 virus was also isolated from dead Whooper swans, Cygnus cygnus, in 2008 in Towada Lake, Akita Prefecture [6]. In addition, outbreaks of other subtypes of avian influenza
Active Targeting to Osteosarcoma Cells and Apoptotic Cell Death Induction by the Novel Lectin Eucheuma serra Agglutinin Isolated from a Marine Red Alga
Keita Hayashi,Peter Walde,Tatsuhiko Miyazaki,Kenshi Sakayama,Atsushi Nakamura,Kenji Kameda,Seizo Masuda,Hiroshi Umakoshi,Keiichi Kato
Journal of Drug Delivery , 2012, DOI: 10.1155/2012/842785
Abstract: Previously, we demonstrated that the novel lectin Eucheuma serra agglutinin from a marine red alga (ESA) induces apoptotic cell death in carcinoma. We now find that ESA induces apoptosis also in the case of sarcoma cells. First, propidium iodide assays with OST cells and LM8 cells showed a decrease in cell viability after addition of ESA. With 50? g/ml ESA, the viabilities after 24 hours decreased to 54.7 ± 11.4% in the case of OST cells and to 41.7 ± 12.3% for LM8 cells. Second, using fluorescently labeled ESA and flow cytometric and fluorescence microscopic measurements, it could be shown that ESA does not bind to cells that were treated with glycosidases, indicating importance of the carbohydrate chains on the surface of the cells for efficient ESA-cell interactions. Third, Span 80 vesicles with surface-bound ESA as active targeting ligand were shown to display sarcoma cell binding activity, leading to apoptosis and complete OST cell death after 48 hours at 2? g/ml ESA. The findings indicate that Span 80 vesicles with surface-bound ESA are a potentially useful drug delivery system not only for the treatment of carcinoma but also for the treatment of osteosarcoma. 1. Introduction Osteosarcoma has one of the worst prognosis among all malignant tumors. Before 1970, the 5-year survival rate of the treated patients was only about 20% [1, 2]. The treatment of osteosarcoma currently involves surgical resection in combination with neoadjuvant chemotherapy. Despite advances in the neoadjuvant chemotherapy and in limb-salvage surgery, the disease-free survival rate still remains poor for patients with metastatic, recurrent, or unresectable osteosarcoma. Thus, novel selective therapeutic approaches against osteosarcoma are highly required. Previously, we found that the novel lectin Eucheuma serra agglutinin (ESA), which was successfully isolated by Kawakubo et al. [3] from the marine red alga Eucheuma serra, specifically binds to carcinoma cell lines of human adenocarcinoma, human cervical squamous cell carcinoma, and marine adenocarcinoma but not to normal human fibroblasts or lymphocytes [4]. We also revealed, that the specific binding of ESA to carcinoma cells is based on specific interactions between ESA and the unique sugar chains of high mannose type on the surface of the carcinoma cells [4]. In a more recent study, Hori et al. [5] investigated the specific interactions between ESA and various unique sugar chains of high mannose type in detail. Furthermore, we successfully elaborated the basis for a novel type of drug delivery system (DDS) for cancer
Cholera in Guinea: The Implication for Safe Water Sources and Sanitations  [PDF]
Keita Mamady, Sylla Mafoule
Open Journal of Preventive Medicine (OJPM) , 2014, DOI: 10.4236/ojpm.2014.47064

Objectives: To lay stress upon the importance of adequate water and sanitation in the prevention of cholera in Guinea. Methods: The data on deaths and cases of cholera in Guinea from 2000 to 2011 were downloaded from the WHO Official website. The data on deaths and cases of cholera outbreak which occurred in Guinea from 02 February to 15 October 2012 were collected from the Guinean Ministry of Public Health. The cholera index case is confirmed by a laboratory test. Cholera cases were defined as individuals over one year old who had had watery stools with or without vomiting. Cholera incidence and case fatality rates between different areas of cholera occurrence in the country over time were computed. Results: Over the overall 12-year period (2000-2012), the case fatality rate showed a somewhat sign of slight rising trend when the incidence rates increased rapidly. During the seven consecutive years of cholera outbreaks in Guinea, between 2003 and 2009, the most affected areas were Conakry, Dubreka, Coyah, Boffa, Forécariah, Guékédou, Dalaba and Télimélé. In 2012, Cholera outbreak resulted in an incidence rate of 23.23 per 10,000 population and a case fatality ratio (CFR) of approximately 1.8%. Cases and deaths were reported in 12 prefectures out of 34: Conakry, Coyah, Forecariah, Fria, Boffa, Dubréka, Boké, Mamou, Kindia, Kankan, Kerouané and Dabola. Conclusion: Cholera is an important health problem in Guinea. Any earnest attempts to improve water and sanitation alongside with promotion of good hygienic practices will likely ward off the threat of cholera in the country.

Assessment of Head Injury Criterion Score of Shock Attenuation Material Employed around Playground Equipment Using Nonlinear Spring Contact Model  [PDF]
Yuji Ohue, Keita Miyoshi
Open Journal of Safety Science and Technology (OJSST) , 2014, DOI: 10.4236/ojsst.2014.42009
Abstract: In order to investigate the influence factors on HIC (Head Injury Criterion) score of shock attenuation materials employed around playground, impact tests were carried out in accordance with ASTM standard. Four kinds of the commercial shock attenuation materials were employed for the test. The apparatus is composed of the missile made from aluminum alloy with a mass of 4.6 kg and a triaxial accelerometer. The higher the missile was dropped, the more HIC score increased. The HIC score depended on the peak deceleration in collision. From the time-frequency analysis, it was obvious that HIC score depended on the characteristic frequency of the vibration system in collision between the missile and the shock attenuation material. There was sufficient evidence to suggest that the use of a simple vibration system with a nonlinear hardening spring is beneficial to assess HIC score and peak deceleration for the shock attenuation material.
On Canard Homoclinic of a Liénard Perturbation System  [PDF]
Makoto Hayashi
Applied Mathematics (AM) , 2011, DOI: 10.4236/am.2011.210170
Abstract: The classification on the orbits of some Liénard perturbation system with several parameters, which is relation to the example in [1] or [2], is discussed. The conditions for the parameters in order that the system has a unique limit cycle, homoclinic orbits, canards or the unique equilibrium point is globally asymptotic stable are given. The methods in our previous papers are used for the proofs.
Fatality from Road Traffic Accident in Guinea: A Retrospective Descriptive Analysis  [PDF]
Keita Mamady, Bin Zou, Sylla Mafoule, Jiabi Qin, Keita Hawa, Keita Fodé Lamine, Guoqing Hu
Open Journal of Preventive Medicine (OJPM) , 2014, DOI: 10.4236/ojpm.2014.411091
Abstract: Objectives: Causes and risk factors that result in fatal road traffic accident have not been described at the national level in Guinea yet. The goal of this study is to explore the causes and risk factors related to fatal road traffic accident, identified most vulnerable road users, and inform the road traffic prevention policy in Guinea. Methods: We made a retrospective descriptive analysis based on national fatal road traffic accident data from the Department of Health Information at the Guinean Ministry of Health for year 2011. Results: In 2011, road traffic accident was responsible for an aggregate number of 1655 deaths with an overall death rate of 15.3 per 100,000 population. Male experienced more than twice the risk of death from road traffic accidents (21.9 deaths per 100,000 population) compared with female (9.0 deaths per 100,000 population). While taking the population as a whole, the highest death rate was found among the middle aged in 35 - 49 age group accounting for (29.7 deaths per 100,000 population), followed successively by young adults age group 25 - 34 years (24.6 deaths per 100,000 population), and the middle aged in 50 - 64 age group (22.9 deaths per 100,000 population). Principally, occupants, motorcyclists and pedestrians sustained considerable burden of deaths respectively (9.2; 2.9; 2.2 per 100,000 population). In re-gional setting, the highest death rate was found in Upper Guinea (19.5 per 100,000 population), followed by Forest Guinea (18.7 per 100,000 population) and Middle Guinea (16.8 per 100,000 population). A large proportion of male was killed as motorcyclist than female while high per-centage of female died as occupant than male for all age group. The regional distribution showed that when a remarkable number of occupant death were observed in Upper and Forest Guinea, more people died as pedestrian and pedal cyclist in Conakry. Conclusions: This study demonstrated that most of the deaths were among occupants, motorcyclists and pedestrians, and the productive workforce aged 25 - 49 years. It was found that majority of the deaths happened in Upper Guinea followed by Forest Guinea. Improvement of roads design, strict enforcement of road safety laws and raising the awareness of general public about the causes and risks factors of road traffic accident through various channels are highly required which will promote economic growth in the local communities and then help people escape the poverty trap.
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