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Featured researches published by Masanobu Okayama.


Journal of Medical Virology | 2010

A nationwide survey of hepatitis E virus infection in the general population of Japan.

Masaharu Takahashi; Kazuko Tamura; Yu Hoshino; Shigeo Nagashima; Yasuyuki Yazaki; Hitoshi Mizuo; Sadahiko Iwamoto; Masanobu Okayama; Yoshikazu Nakamura; Eiji Kajii; Hiroaki Okamoto

To investigate nationwide the prevalence of hepatitis E virus (HEV) infection in the general population of Japan, serum samples were collected from 22,027 individuals (9,686 males and 12,341 females; age, mean ± standard deviation: 56.8 ± 16.7 years; range: 20–108 years) who lived in 30 prefectures located in Hokkaido, mainland Honshu, Shikoku, and Kyushu of Japan and underwent health check‐ups during 2002–2007, and were tested for the presence of IgG, IgM, and IgA classes of antibodies to HEV (anti‐HEV) by in‐house ELISA and HEV RNA by nested RT‐PCR. Overall, 1,167 individuals (5.3%) were positive for anti‐HEV IgG, including 753 males (7.8%) and 414 females (3.4%), the difference being statistically significant (P < 0.0001). The prevalence of anti‐HEV IgG generally increased with age and was significantly higher among individuals aged ≥50 years than among those aged <50 years (6.6% vs. 2.7%, P < 0.0001). Although 13 individuals with anti‐HEV IgG also had anti‐HEV IgM and/or anti‐HEV IgA, none of them had detectable HEV RNA. The presence of HEV RNA was further tested in 50 or 49‐sample minipools of sera from the remaining 22,014 individuals, and three individuals without anti‐HEV antibodies tested positive for HEV RNA. The HEV isolates obtained from the three viremic individuals segregated into genotype 3 and were closest to Japan‐indigenous HEV strains. When stratified by geographic region, the prevalence of anti‐HEV IgG as well as the prevalence of HEV RNA or anti‐HEV IgM and/or anti‐HEV IgA was significantly higher in northern Japan than in southern Japan (6.7% vs. 3.2%, P < 0.0001; 0.11% vs. 0.01%, P = 0.0056; respectively). J. Med. Virol. 82:271–281, 2010.


International Journal of General Medicine | 2014

Reasons for encounter and diagnoses of new outpatients at a small community hospital in Japan: an observational study

Taro Takeshima; Maki Kumada; Junichi Mise; Yoshinori Ishikawa; hiromichi Yoshizawa; Takashi Nakamura; Masanobu Okayama; Eiji Kajii

Purpose Although many new patients are seen at small hospitals, there are few reports of new health problems from such hospitals in Japan. Therefore, we investigated the reasons for encounter (RFE) and diagnoses of new outpatients in a small hospital to provide educational resources for teaching general practice methods. Methods This observational study was conducted at the Department of General Internal Medicine in a small community hospital between May 6, 2010 and March 11, 2011. We classified RFEs and diagnoses according to component 1, “Symptoms/Complaints”, and component 7, “Diagnosis/Diseases”, of the International Classification of Primary Care, 2nd edition (ICPC-2). We also evaluated the differences between RFEs observed and common symptoms from the guidelines Model Core Curriculum for Medical Students and Goals of Clinical Clerkship. Results We analyzed the data of 1,515 outpatients. There were 2,252 RFEs (1.49 per encounter) and 170 ICPC-2 codes. The top 30 RFE codes accounted for 80% of all RFEs and the top 55 codes accounted for 90%. There were 1,727 diagnoses and 196 ICPC-2 codes. The top 50 diagnosis codes accounted for 80% of all diagnoses, and the top 90 codes accounted for 90%. Of the 2,252 RFEs, 1,408 (62.5%) included at least one of the 36 symptoms listed in the Model Core Curriculum and 1,443 (64.1%) included at least one of the 35 symptoms in the Goals of Clinical Clerkship. On the other hand, “A91 Abnormal result investigation”, “R21 Throat symptom/complaint”, and “R07 Sneezing/nasal congestion”, which were among the top 10 RFEs, were not included in these two guidelines. Conclusion We identified the common RFEs and diagnoses at a small hospital in Japan and revealed the inconsistencies between the RFEs observed and common symptoms listed in the guidelines. Our findings can be useful in improving the general practice medical education curricula.


International Journal of General Medicine | 2012

Use of a semiquantitative procalcitonin kit for evaluating severity and predicting mortality in patients with sepsis

Tsuneaki Kenzaka; Masanobu Okayama; Shigehiro Kuroki; Miho Fukui; Shinsuke Yahata; Hiroki Hayashi; Akihito Kitao; Eiji Kajii; Masayoshi Hashimoto

Background The aim of this study was to evaluate the clinical usefulness of a semiquantitative procalcitonin kit for assessing severity of sepsis and early determination of mortality in affected patients. Methods This was a prospective, observational study including 206 septic patients enrolled between June 2008 and August 2009. Disseminated intravascular coagulation (DIC), Sequential Organ Failure Assessment (SOFA), Acute Physiology and Chronic Health Evaluation (APACHE) II scores were measured, along with semiquantitative procalcitonin concentrations. Patients were divided into three groups based on their semiquantitative procalcitonin concentrations (group A, <2 ng/mL; group B ≥ 2 ng/mL < 10 ng/mL; group C ≥ 10 ng/mL). Results A significant difference in DIC, SOFA, and APACHE II scores was found between group A and group C and between group B and group C (P < 0.01). Patients with severe sepsis and septic shock had significantly higher procalcitonin concentrations than did patients with less severe disease. The rate of patients with septic shock with high procalcitonin concentrations showed an upward trend. There was a significant (P < 0.01) difference between the three groups with regard to numbers of patients and rates of severe sepsis, septic shock, DIC, and mortality. Conclusion Semiquantitative procalcitonin concentration testing can be helpful for early assessment of disease severity in patients with sepsis. Furthermore, it may also help in predicting early mortality in septic patients. Based on the level of semiquantitative procalcitonin measured in patients with suspected sepsis, a timely decision can be reliably made to transfer them to a tertiary hospital with an intensive care unit for optimal care.


Wilderness & Environmental Medicine | 2014

Doppler Detection in Ama Divers of Japan

Frédéric Lemaître; Kiyotaka Kohshi; Hideki Tamaki; Kasuo Nakayasu; Mesanori Harada; Masanobu Okayama; Yuka Satou; Michiko Hoshiko; Tatsuya Ishitake; Guillaume Costalat; Bernard Gardette

OBJECTIVE Symptoms consistent with neurological decompression sickness (DCS) in commercial breath-hold (Ama) divers has been reported from a few districts of Japan. The aim of this study was to detect circulating intravascular bubbles after repetitive breath-hold diving in a local area where DCS has been reported in Ama divers. METHODS The participants were 12 partially assisted (descent using weights) male Ama divers. The equipment (AQUALAB system) consisted of continuous-wave Doppler with a 5-MHz frequency, and the Doppler probe was placed in the precordial site with the ultrasonic wave directed into the pulmonary infundibulum. We carried out continuous monitoring for 10 minutes at the end of the series of repetitive dives, and the recordings were made on numerical tracks and graded in a blind manner by 2 experienced investigators, according to the Spencer Doppler code. RESULTS Depths and number of dives were 8 to 20 m and 75 to 131 times. Mean diving duration and surface interval were 64 ± 12 seconds and 48 ± 8 seconds, respectively (mean ± SD). We detected the lowest grade of intravascular bubbles (Spencers grade I) in an Ama diver whose mean surface interval was only 35.2 ± 6.2 seconds. His mean descending, bottom, and ascending times were 10.4 ± 1.6 seconds, 39.2 ± 8 seconds, and 18.2 ± 3.0 seconds, respectively, over the course of 99 dives. CONCLUSIONS Intravascular bubbles may be formed after repetitive breath-hold dives with short surface intervals or after a long breath-holding session in Ama divers. Symptoms consistent with neurological accidents in repetitive breath-hold diving may be caused in part by the intravascular presence of bubbles, indicating the need for safety procedures.


Clinical Interventions in Aging | 2017

Factors involved in the discontinuation of oral intake in elderly patients with recurrent aspiration pneumonia: a multicenter study

Tsuneaki Kenzaka; Taro Takeshima; Koki Kosami; Ayako Kumabe; Yuki Ueda; Takeshi Takahashi; Yuya Yamamoto; Yurika Hayashi; Akihito Kitao; Masanobu Okayama

Purpose To assess the factors involved in oral intake discontinuation in elderly patients with recurrent aspiration pneumonia. Patients and methods This study included patients with pneumonia who were treated at Jichi Medical University Hospital between 2007 and 2013, at Toyooka Public Hospital between 2011 and 2013 and at Yuzawa Community Medical Center between 2010 and 2012. We consecutively enrolled patients with aspiration pneumonia. The primary study point was oral intake discontinuation after the initiation of oral intake during hospitalization in cases of recurrent aspiration. Various parameters were recorded at admission, at the initiation of intake, and during hospitalization; these parameters were statistically evaluated. Results A total of 390 patients were assigned to either a “no reaspiration of intake” group (n=310) or a “reaspiration of intake” group (n=80), depending on whether intake was discontinued owing to aspiration during hospitalization. At admission, the following items significantly differed between the groups: level of consciousness, respiratory rate, oxygen saturation, CURB-65 score, extent of infiltration/opacity on chest radiography, albumin levels, blood urea nitrogen levels, and application of swallowing function assessment. At the initiation of intake, level of consciousness, pulse rate, and albumin levels significantly differed between the groups. The following items did not significantly differ between groups: systolic blood pressure, pulse rate, C-reactive protein, bacteremia, use of ventilator at admission, oxygen administration, respiratory rate, and systolic blood pressure at initiation of intake. Multivariate analysis revealed that application of swallowing function assessment, level of consciousness at the initiation of intake, and extent of infiltration/opacity on chest radiography were significant predictive variables for discontinuation of intake. Conclusion A low level of consciousness at the initiation of intake and a greater extent of infiltration/opacity on chest radiography and the application of a swallowing function are important factors. These factors may be helpful to determine a suitable timing for resumption of oral intake.


Education for primary care | 2007

Primary Care Education in Japan: Is it Enough to Increase Student Interest in a Career in Primary Care?

Ayumi Takayashiki; Kazuo Inoue; Masanobu Okayama; Yosikazu Nakamura; Masatoshi Matsumoto; Junji Otaki; Eiji Kajii

Participation in primary care clerkships is known to be a strong facilitator for choosing primary care specialties. These programmes for undergraduate students in Japan are shorter and less intensive than those currently available in the USA or UK, as primary care is still an evolving discipline in Japan. The primary objectives of this paper are: to introduce the major issues that exist with respect to primary care education for undergraduates in Japan; to investigate the level of career preference for primary care among Japanese medical students; to examine the factors Education for Primary Care (2007) 18: 156–64 # 2007 Radcliffe Publishing Limited


Open Access Emergency Medicine | 2014

Injury mortality and accessibility to emergency care in Japan: an observational epidemiological study

Takashi Nakamura; Masanobu Okayama; Masakazu Aihara; Eiji Kajii

Background Unintentional injury is a major cause of death across the globe. The accessibility to emergency medical services may affect the rate of preventable trauma deaths. The purpose of this study was to analyze the accessibility to emergency medical hospitals in municipalities in Japan and to clarify whether accessibility was associated with the mortality rate attributed to unintentional injuries. Methods An observational epidemiological study was conducted in all 1,742 municipalities in Japan. Measurements assessed were population size, accessibility to emergency hospitals, and mortality rates attributed to unintentional injuries. Accessibility of each municipality to their nearest emergency hospital was calculated with a computer simulation using a geographic information system. After calculating demographic statistics and the Gini coefficient of accessibility, multivariate analyses were used to examine the correlation between accessibility time and mortality. Municipalities were divided into six groups according to accessibility time, and we then performed a correlation analysis between accessibility time and mortality using analysis of covariance. Results The median time of accessibility to emergency hospitals was 34.5 minutes. The Gini coefficient of accessibility time was 0.410. A total of 385 municipalities (23.4%) had an accessibility time of over 60 minutes. Accessibility was significantly related to mortality (beta coefficient =0.006; P<0.001). The mortality rate in municipalities with an accessibility time of <15 minutes was lower than that in all other groups. The mortality rate in municipalities with an accessibility time of 15–30 minutes was lower than that in municipalities with an accessibility time of >30 minutes, and the mortality rate in municipalities with an accessibility time of 30–45 minutes was lower than that in municipalities with an accessibility time of 60–90 minutes (P<0.001). Conclusion The geographical disparities for emergency care accessibility were related to the rate of death by unintentional injury. Improving accessibility to emergency hospitals could help decrease the mortality rate of preventable trauma. Meanwhile, our findings suggest the need for substantially shorter accessibility times to emergency care facilities in many municipalities in Japan.


Journal of the American College of Cardiology | 2014

INTERACTION BETWEEN ALCOHOL HABIT AND GENE POLYMORPHISM OF NEUROPEPTIDE Y ON THE RISK OF ESSENTIAL HYPERTENSION

Masahiko Eto; Masanobu Okayama; Maki Kumada; Taro Takeshima; Takanori Aonuma; Yoshikazu Nakamura; Kajii Eiji

It has been estimated that approximately 50% heavy drinkers experience alcohol-induced BP elevation. Inter-individual variation of alcohol effect might be due to genetic variations. Recent evidence has suggested that Neuropeptide Y(NPY) might control BP and low expression NPY genotype might be


International Medical Case Reports Journal | 2014

A case of thyroid storm with cardiac arrest

Yutaka Nakashima; Tsuneaki Kenzaka; Masanobu Okayama; Eiji Kajii

A 23-year-old man became unconscious while jogging. He immediately received basic life support from a bystander and was transported to our hospital. On arrival, his spontaneous circulation had returned from a state of ventricular fibrillation and pulseless electrical activity. Following admission, hyperthyroidism led to a suspicion of thyroid storm, which was then diagnosed as a possible cause of the cardiac arrest. Although hyperthyroidism-induced cardiac arrest including ventricular fibrillation is rare, it should be considered when diagnosing the cause of treatable cardiac arrest.


International Journal of General Medicine | 2013

Effects of disclosing hypothetical genetic test results for salt sensitivity on salt restriction behavior.

Taro Takeshima; Masanobu Okayama; Masanori Harada; Ryusuke Ae; Eiji Kajii

Background A few studies have explored the effects of disclosure of genetic testing results on chronic disease predisposition. However, these effects remain unclear in cases of hypertension. Reducing salt intake is an important nonpharmacological intervention for hypertension. We investigated the effects of genetic testing for salt sensitivity on salt restriction behavior using hypothetical genetic testing results. Methods We conducted a cross-sectional study using a self-completed questionnaire. We enrolled consecutive outpatients who visited primary care clinics and small hospitals between September and December 2009 in Japan. We recorded the patients’ baseline characteristics and data regarding their salt restriction behavior, defined as reducing salt intake before and after disclosure of hypothetical salt sensitivity genetic test results. Behavioral stage was assessed according to the five-stage transtheoretical model. After dividing subjects into salt restriction and no salt restriction groups, we compared their behavioral changes following positive and negative test results and analyzed the association between the respondents’ characteristics and their behavioral changes. Results We analyzed 1562 participants with a mean age of 58 years. In the no salt restriction group, which included patients at the precontemplation, contemplation, and preparation stages, 58.7% stated that their behavioral stage progressed after a positive test result, although 29.8% reported progression after a negative result (P < 0.001). Conversely, in the salt restriction group, which included patients at the active and maintenance stages, 9.2% stated that they would quit restricting salt intake following a negative test result, and 2.2% reported they would quit following a positive result (P < 0.001). Age < 65 years (adjusted odds ratio [OR] 1.74; 95% confidence interval [CI] 1.12–2.71), female gender (adjusted OR 1.84; CI 1.29–2.62), graduation from college or university (adjusted OR 1.66; CI 1.11–2.49), and desire for genetic testing (adjusted OR 4.53; CI 3.13–6.57) were associated with progression of behavioral stage in the no salt restriction group. Conversely, salt preference (adjusted OR 2.13; CI 1.31–3.49) was associated with quitting salt restriction in the salt restriction group. Conclusion Patients in the no salt restriction group show the possibility of progression from the behavioral stage to the action stage after testing positive for salt sensitivity. Conversely, patients in the salt restriction group, particularly those with a salt preference, would quit salt restriction after testing negative.

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Eiji Kajii

Jichi Medical University

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Taro Takeshima

Jichi Medical University

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Ryusuke Ae

Jichi Medical University

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