Biomedical subjects

Y Kikuchi

Publications and source records attributed to Y Kikuchi.

At least 19 recordsLinked to original sources

PubMed2006

Forced magnetic reconnection and field penetration of an externally applied rotating helical magnetic field in the TEXTOR tokamak.

The magnetic field penetration process into a magnetized plasma is of basic interest both for plasma physics and astrophysics. In this context special measurements on the field penetration and field amplification are performed by a Hall probe on the dynamic ergodic divertor (DED) on the TEXTOR tokamak and the data are interpreted by a two-fluid plasma model. It is observed that the growth of the forced magnetic reconnection by the rotating DED field is accompanied by a change of the plasma fluid rotation. The differential rotation frequency between the DED field and the plasma plays an important role in the process of the excitation of tearing modes. The momentum input from the rotating DED field to the plasma is interpreted by both a ponderomotive force at the rational surface and a radial electric field modified by an edge ergodization.

Journal Article↗

PubMed2006

Mobile phone use and acoustic neuroma risk in Japan.

OBJECTIVES: The rapid increase of mobile phone use has increased public concern about its possible health effects in Japan, where the mobile phone system is unique in the characteristics of its signal transmission. To examine the relation between mobile phone use and acoustic neuroma, a case-control study was initiated. METHODS: The study followed the common, core protocol of the international collaborative study, INTERPHONE. A prospective case recruitment was done in Japan for 2000-04. One hundred and one acoustic neuroma cases, who were 30-69 years of age and resided in the Tokyo area, and 339 age, sex, and residency matched controls were interviewed using a common computer assisted personal interview system. Education and marital status adjusted odds ratio was calculated with a conditional logistic regression analysis. RESULTS: Fifty one cases (52.6%) and 192 controls (58.2%) were regular mobile phone users on the reference date, which was set as one year before the diagnosis, and no significant increase of acoustic neuroma risk was observed, with the odds ratio (OR) being 0.73 (95% CI 0.43 to 1.23). No exposure related increase in the risk of acoustic neuroma was observed when the cumulative length of use (<4 years, 4-8 years, >8 years) or cumulative call time (<300 hours, 300-900 hours, >900 hours) was used as an exposure index. The OR was 1.09 (95% CI 0.58 to 2.06) when the reference date was set as five years before the diagnosis. Further, laterality of mobile phone use was not associated with tumours. CONCLUSIONS: These results suggest that there is no significant increase in the risk of acoustic neuroma in association with mobile phone use in Japan.

Adult↗

PubMed2006

Clear cell carcinoma of the ovary: a retrospective multicentre experience of 254 patients with complete surgical staging.

A retrospective analysis was performed to evaluate the clinical characteristics and prognostic factors in the patients with clear cell carcinoma (CCC) of the ovary. After central pathological review and scanning of the medical records of nine Japanese institutions between 1992 and 2003, a total of 254 patients with CCC of the ovary were enrolled in the present study. Mean age was 52.4 years (range 23-73 years). Tumours were 13% (33/254) stage Ia, 36% (92/254) stage Ic, 13% (33/254) stage II, 30% (80/254) stage III, and 6% (16/254) stage IV. Five-year progression-free survival and overall survival was 84 and 88% in stage I, 57 and 70% in stage II, 25 and 33% in stage III and 0 and 0% in stage IV, respectively. Retroperitoneal lymph node metastasis was observed in 9% in pT1a tumours, 7% in pT1c tumours, 13% in pT2 tumours, and 58% in pT3 tumours, respectively. There was no survival benefit according to chemotherapeutic differences in the patients who received complete surgical staging procedures and conventional chemotherapy. Peritoneal cytological status was an independent prognostic factor in stage Ic patients (P=0.03) and only residual tumour diameter was an independent prognostic factor in stage III, IV patients (P=0.02). Our results suggest that cytoreductive surgery resulting in no residual tumour only could improve the prognosis of advanced CCC patients.

Adenocarcinoma, Clear Cell↗

PubMed2006

Secretion of human epidermal growth factor by Corynebacterium glutamicum.

AIMS: To examine the secretion of human epidermal growth factor (hEGF) by Corynebacterium glutamicum. METHODS AND RESULTS: We recently showed that a novel protein-secretion system in C. glutamicum could produce Streptomyces mobaraensis transglutaminase. In the present study, the industrially important protein hEGF was secreted into the culture medium in a fully active form by C. glutamicum and accumulated at a rate of up to 156 mg l(-1) day(-1). CONCLUSIONS: These results demonstrated that the hEGF protein could be secreted in an active form by C. glutamicum. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data confirmed that the pharmaceutically important human protein hEGF could be efficiently secreted in an active form by the C. glutamicum protein-expression system. Moreover, we demonstrated that this bacterium has potential as a host for the industrial-scale production of human proteins.

Blotting, Western↗

PubMed2006

Does informed consent exempt Japanese doctors from reporting therapeutic deaths?

The Japanese Medical Act section 21 states that doctors must report unnatural deaths to the police, even though the term "unnatural death" is not defined by law. However, many doctors are reluctant to report potential therapeutic deaths (PTDs). The Japanese Society of Legal Medicine has submitted guidelines for unnatural death, including PTD. These define a PTD as an unexpected death, the cause of which is unknown, but which is potentially related to medical practice. Such deaths are "reportable" to the coroner in the UK. In this study, we addressed the question of whether physicians would report each of eight hypothetical PTDs. Although the clinical societies (the Japan Society of Internal Medicine and the Japan Surgical Society) declare that doctors must report deaths due to gross negligence, 60% of the participants said that they would not report gross negligence involving an overdose in cases where they had obtained informed consent or had provided an explanation after the death occurred. This can be accounted for by the mistaken belief on the part of the participants that obtaining informed consent exempts Japanese physicians from the duty of reporting PTDs. The attitude of Japanese physicians is caused by the death investigation system, which is designed to discover whether a crime has been committed rather than focusing on the cause of death. Accordingly, the Japanese Government has decided to commission a pilot study from an independent organisation in which medical specialists will investigate PTDs in order to prevent deaths occurring as a result of gross negligence.

Accidental Falls↗

PubMed2006

A cross sectional study of the respiratory health of workers handling printing toner dust.

BACKGROUND: Although recent case reports have suggested possible respiratory effects of solid toner dust inhalation, this hypothesis has not been verified by epidemiological studies. OBJECTIVES: To conduct a cross sectional study to evaluate the association between the biological indices of lung fibrosis and toner dust exposure in an occupational cohort handling solid toner dust in their work life. METHODS: A total of 600 male toner workers and 212 control subjects were surveyed in terms of their subjective respiratory symptoms, pulmonary functions, and chest radiographic findings. In addition to the exposure history, the current working conditions and personal exposure levels to toner dust were also examined. RESULTS: Although subjects handling toner for more than 20 years tended to show a higher prevalence of respiratory symptoms and minimal chest x ray abnormalities, there was no consistent relation between the exposure to toner dust and the biological responses of the respiratory system. CONCLUSION: Deterioration of respiratory health related to toner dust exposure is less likely to occur in current well controlled work environments, especially if the powdered toner is handled carefully. Nonetheless, it is important to collect further epidemiological evidence on the biological effects of toner dust inhalation, preferably using a longitudinal study design.

Adult↗

PubMed2006

Streptococcal origin of a case of Henoch-Schoenlein purpura nephritis.

We report the case of a 25-year-old man with abdominal pain, purpura on the legs and proteinuria occurring 2 weeks after acute tonsillitis, and admitted to our hospital with suspected Henoch-Schönlein purpura nephritis (HSPN). He had increased anti-streptolysin O (ASO) titer and hypocomplementemia. A renal biopsy specimen showed endocapillary proliferative changes, which are typical of acute poststreptococcal glomerulonephritis (APSGN). However, immunofluorescence study revealed predominant IgA and C3 deposits in mesangial lesions, indicating a diagnosis of HSPN. Because of massive proteinuria initially, the treatment with a combination of prednisolone, cyclophosphamide, dipyridamole and warfarin was started along with 3 plasma exchanges. Angiotensin-converting enzyme inhibitor was also given. Response to the treatment was favorable. A follow-up biopsy was performed 8 months after the first biopsy. The renal biopsy specimen showed a figure of typical HSPN. To further investigate the cause of glomerular changes in our patient, an immunofluorescent study of nephritogenic nephritis-associated plasmin receptor (NAPlr) of group A, beta-hemolytic streptococci was performed. NAPlr was significantly positive in the glomeruli in the first biopsy specimen, but not in the second. His clinical course and pathological findings suggest that NAPlr may be related to the pathogenesis in a part of patients with HSPN, especially in patients with high ASO titer and hypocomplementemia.

Adult↗

PubMed2006

[Elderly patient with acute type A aortic dissection; report of a case].

A 93-year-old woman complained of severe back pain. Computed tomography (CT) and echocardiography revealed acute type A aortic dissection with enlargement of the ascending aorta, moderate aortic regurgitation and cardiac tamponade. Despite her age, the patient was able to support herself, and she and her family desired to have a surgical treatment. Therefore she was referred to our hospital immediately and underwent an emergent ascending aortic replacement using a 28mm woven Dacron graft under deep hypothermic circulatory arrest. Postoperative course was uneventful, and the patient was discharged from our hospital on the 34 th postoperative day in good condition.

Acute Disease↗

PubMed2005

Rickettsia infection in natural leech populations.

Field-collected specimens of glossiphoniid leeches, Torix tagoi, Torix tukubana, Hemiclepsis marginata, and Hemiclepsis japonica, were surveyed for Rickettsia infection by using a diagnostic PCR assay. Rickettsia was detected in 96% (69/72) of T. tagoi, 83% (24/29) of T. tukubana, 29% (33/113) of H. marginata, and 0% (0/30) of H. japonica. The frequencies of Rickettsia infection were stably maintained in different seasons. In H. marginata and T. tukubana, distant local populations exhibited remarkably different frequencies of Rickettsia infection. Eggs carried by infected females of T. tagoi and H. marginata were all Rickettsia-positive, indicating nearly 100% vertical transmission. Analysis of 16S rDNA sequences revealed that phylogenetic relationship of the leech-associated Rickettsia reflected the specific and populational divisions of the host leeches. However, circumstantial lines of evidence strongly suggested that horizontal transmission of Rickettsia must have occurred in the ancestors of these leeches. In T. tagoi and T. tukubana, infected individuals were remarkably larger in size than uninfected individuals, wheras in H. marginata, infected and uninfected individuals were almost comparable in size. This study first provides information on ecological aspects of leech-bone endocellular bacteria of the genus Rickettsia. On the basis of these data, we discuss possible mechanisms whereby Rickettsia infection is maintained in natural populations of these leeches in the freshwater ecosystem.

Animals↗

PubMed2005

Toroidal plasma rotation induced by the dynamic ergodic divertor in the TEXTOR tokamak.

The first results of the Dynamic Ergodic Divertor in TEXTOR, when operating in the m/n=3/1 mode configuration, are presented. The deeply penetrating external magnetic field perturbation of this configuration increases the toroidal plasma rotation. Staying below the excitation threshold for the m/n=2/1 tearing mode, this toroidal rotation is always in the direction of the plasma current, even if the toroidal projection of the rotating magnetic field perturbation is in the opposite direction. The observed toroidal rotation direction is consistent with a radial electric field, generated by an enhanced electron transport in the ergodic layers near the resonances of the perturbation. This is an effect different from theoretical predictions, which assume a direct coupling between rotating perturbation and plasma to be the dominant effect of momentum transfer.

Journal Article↗

PubMed2005

Irreducible chronic palmar dislocation of the distal radioulnar joint--a case report.

We report a rare case of irreducible chronic palmar dislocation of the distal radioulnar joint (DRUJ). This case showed that the dislocated ulnar head was impacted to the palmar cortex of the radius probably due to the dynamic force of the pronator quadratus muscle. Re-attachment of the ulnar styloid and partial resection of the ulnar head were necessary to make the reduction of the DRUJ possible. The continuity of the radioulnar ligament to the ulnar head was restored and the stability of DRUJ was maintained after reduction.

Adult↗

PubMed2004

Spatiotemporal brain activity in mental rotation.

There are many higher-order cognitive processes whose neural mechanisms are hard to study by using nonhuman primates. The mental rotation task is one of the best studied of these. We investigated the spatiotemporal brain activity underlying mental rotation of different kinds of stimuli by measuring the magnetoencephalogram of subjects performing two kinds of mental rotation tasks. Visual stimuli in one experiment consisted of hand shapes presented at various orientations, and those in the other consisted of a set of alphabetic characters and their mirror images presented at various orientations. All stimuli were presented in the left visual field. Activity associated with visual stimulus processing was estimated in the lateral occipital lobe, basal occipitotemporal area, and inferior temporal gyrus. Activities related to higher visual processing were differed between the two kinds of stimuli we used. For the hand shape experiment, we found right inferior parietal lobule activity at 200-300 ms after the stimulus presentation. For the alphabetic characters, activity was found in the left superior temporal region at about 300 ms. Furthermore, activity related to mental stimulation in the inferior parietal lobule and premotor area were seen in the both experiments. In the experiments with hands, the premotor activity showed left-hemispheric dominance. However, in the experiments with alphabetic characters, the laterality of the premotor activity did not show left-hemispheric dominance. We inferred this difference was influenced by the subjects' familiarity with the mental rotation of visual stimuli.

Adult↗

PubMed2004

Lattice imaging in low-angle and high-angle bright-field scanning transmission electron microscopy.

Atomic resolution low-angle bright-field (LABF) scanning transmission electron-microscope (STEM) images and high-angle bright-field (HABF) STEM images of [011]-orientated Si have been experimentally obtained together with high-angle annular dark-field (HAADF) STEM images. The contrast formation mechanisms of the LABF STEM and HABF STEM images are examined in comparison with HAADF STEM images. The HABF STEM images independent of defocus and thickness have spatial resolution comparable with HAADF STEM images, and are shown to be given as a simple convolution under the non-dispersion approximation of localized Bloch waves.

Journal Article↗

PubMed2004

Precision control of the surface structure of gelatin films using micropit plates.

We attempted to use micropit plates as a silicon mold in order to control the surface structures of gelatin films. The three-dimensional micropit plates, fabricated with micromachining technology, have uniform quadrangular or circular pits with side lengths or diameters from 25-400 microm and depths of 40 microm. The micropit plates were originally hydrophilic because of silanol groups on the surface. In order to facilitate peeling the aqueous gelatin film from the micropit plates, the plate was therefore modified with hexamethyldisilazane. Gelatin films with precisely microfabricated structures on the surfaces were obtained by using the modified micropit plates. The release behavior of the films with different surface structures was examined.

Electroplating↗

PubMed2004

Properties and applications of microbial transglutaminase.

Some properties and applications of the transglutaminase (TGase) referred to as microbial TGase (MTGase), derived from a variant of Streptomyces mobaraensis (formerly classified as Streptoverticillium mobaraense), are described. MTGase cross-linked most food proteins, such as caseins, soybean globulins, gluten, actin, myosins, and egg proteins, as efficiently as mammalian TGases by forming an epsilon-(gamma-glutamyl)lysine bond. However, unlike many other TGases, MTGase is calcium-independent and has a relatively low molecular weight. Both of these properties are of advantage in industrial applications; a number of studies have illustrated the potential of MTGase in food processing and other areas. The crystal structure of MTGase has been solved. It provides basic structural information on the MTGase and accounts well for its characteristics. Moreover, an efficient method for producing extracellular MTGase has been established using Corynebacterium glutamicum. MTGase may be expected to find many uses in both food and non-food applications.

Coenzymes↗

PubMed2004

Breath sample collection through the nostril reduces false-positive results of 13C-urea breath test for the diagnosis of helicobacter pylori infection.

BACKGROUND: One of the disadvantages of '3C-urea breath test is possible interference by urease activity not related to Helicobacterpylori. AIMS: We design the simple and non-invasive modification to avoid the contamination of 13CO(2) produced in the mouth. PATIENTS AND METHODS: One hundred and twenty-nine patients who underwent diagnostic upper endoscopy were enrolled. Within 1 week of the endoscopic procedure, each patient received the modified 13C-urea breath test. Breath samples were collected at baseline and at 1, 3, 5, 10, 15, 20 and 30 min after ingestion of 100 mg 13C-urea solution through the mouth and the nostril at each time point. RESULTS: The breath delta13CO2 value through the nostril at 1 min was already higher in H. pylori-positive patients than in H. pylori-negative patients. Using 2.5% as the cut-off value, the sensitivity and specificity of the modified 13C-urea breath test at 20 min were both 100%, whereas the sensitivity and specificity of the standard 13C-urea breath test were 97.7 and 94%, respectively, using 3% as the cut-off value. CONCLUSIONS: The modified 13C-urea breath test in which breath samples are collected through the nostril provides an easy way of avoiding false-positive results for the detection of H. pylori infection.

Adolescent↗

PubMed2004

Symmetries in BF and HAADF STEM image calculations.

Reductions in bright-field (BF) scanning transmission electron microscopy (STEM) and high-angle annular dark-field (HAADF) STEM image calculations with the aid of Bloch wave symmetry are discussed under assumptions that an absorption potential is written by a local potential and a zero-order Laue zone lies parallel to the crystal surface. Translational symmetry allows us to take only partial incident beams in the first Brillouin zone instead of enormous number of partial incident beams in a large convergent disk. Two dimensional point group confines partial incident beams to an irreducible area in addition to factoring a dispersion matrix into noninteracting submatrices on a high symmetry line using the projection operator. The drastic reductions in computing time and memory enable us to readily calculate various BF STEM and HAADF STEM images. The validity and accuracy are demonstrated in comparisons with high resolution experimental BF STEM and HAADF STEM images.

Algorithms↗

PubMed2004

Specific alcoholic beverage and blood pressure in a middle-aged Japanese population: the High-risk and Population Strategy for Occupational Health Promotion (HIPOP-OHP) Study.

The purpose of this study was to clarify the effects of popular Japanese alcoholic beverages on blood pressure. We performed a cross-sectional study on 4335 Japanese male workers using baseline data from an intervention study. We defined six groups according to the type of alcoholic beverage that provided two-thirds of the subject's total alcohol consumption: beer, sake (rice wine), shochu (traditional Japanese spirits), whiskey, wine and others. The partial regression coefficients of daily alcohol intake (1 drink=11.5 g of ethanol) to systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 0.87(P<0.001, standard error (s.e.)=0.09) and 0.77(P<0.001, s.e.=0.06), respectively. A comparison among the types of alcoholic beverages mainly consumed revealed significant differences in SBP and DBP. Both SBP and DBP were highest in the shochu group. However, an analysis of covariance adjusting for total alcohol consumption resulted in the disappearance of these differences. Although after adjustment for total alcohol consumption, the shochu group exhibited a significant positive association with 'high-normal blood pressure or greater' (odds ratio 1.43, 95% confidence interval 1.06-1.95) compared with the beer group, this significant relation disappeared after adjusting for the body mass index (BMI), urinary sodium and potassium excretion. The pressor effect, per se, of popular Japanese alcoholic beverages on blood pressure may not be different among the types of alcoholic beverages after adjusting for other lifestyle factors.

Adult↗