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Biomedical subjects

K Hayashi

Publications and source records attributed to K Hayashi.

At least 37 records · Page 2Linked to original sources
PubMed2005

Delayed segmental motor paralysis following laminoplasty: two case reports.

STUDY DESIGN: Two patients who experienced the onset of segmental motor paralysis several years after laminoplasty are presented. OBJECTIVES: To discuss the mechanism of development of delayed segmental motor paralysis following laminoplasty. SETTING: A department of orthopaedic surgery in Japan. METHODS: One patient experienced motor weakness in his deltoid and biceps muscles on the left side 5 years after laminoplasty. The other patient noticed motor weakness in his deltoid and biceps on the right side 7 years after laminoplasty. CT myelography revealed posterior spur formation and hypertrophic facet joints on the hinged side at the C4-C5 level in both patients. RESULTS: Posterior foraminotomy was performed at the C4-C5 level on the hinged side in both patients. Postoperatively, motor weakness in the deltoid and biceps muscles was improved in both patients. CONCLUSIONS: Although spondylotic changes, including spur formation and disc herniation, have occasionally developed in operated segments after laminoplasty, few patients have required additional surgery for treatment of relapse of neurological deficits. It has been believed that spinal cord is rarely compressed by the spondylotic changes since it shifts posteriorly in the enlarged spinal canal. However, laminoplasty disturbs the facet joints since the medial portion of dorsal cortex and cancellous bone in facet joints is drilled out to make a trough. Facet joints disturbed in this fashion undergo degeneration over time after surgery. Nerve roots may occasionally be compressed by degenerated facet joints and spurs that have developed at the entrance of root canal, resulting in segmental motor paralysis several years after laminoplasty. Careful long-term observation is necessary after this procedure.

Aged↗
PubMed2005

Effect of aging on carotid artery stiffness and baroreflex sensitivity during head-out water immersion in man.

To examine the possible age-related blood pressure (BP) deregulation in response to central hypervolemia, we measured spontaneous baroreflex sensitivity (SBRS), carotid arterial compliance (CC), and R-R interval coefficient of variation (RRICV) during basal and thermoneutral resting head-out-of-water immersion (HOWI) in 7 young (YG = 24.0 +/- 0.8 years) and 6 middle-aged/older (OL = 59.3 +/- 1.3 years) healthy men. Compared with basal conditions (YG = 19.6 +/- 4.0 vs OL = 6.1 +/- 1.5 ms/mmHg, P < 0.05), SBRS remained higher in YG than OL during rest HOWI (YG = 23.6 +/- 6.6 vs OL = 9.3 +/- 2.1 ms/mmHg, P < 0.05). The RRICV was significantly different between groups (YG = 6.5 +/- 1.4 vs OL = 2.8 +/- 0.4%, P < 0.05) under HOWI. The OL group had no increase in CC, but a significant increase in systolic BP (basal = 115.3 +/- 4.4 vs water = 129.3 +/- 5.3 mmHg, P < 0.05) under HOWI. In contrast, the YG group had a significant increase in CC (basal = 0.16 +/- 0.01 vs water = 0.17 +/- 0.02 mm(2)/mmHg, P < 0.05) with no changes in systolic BP. SBRS was positively related to CC (r = 0.58, P < 0.05 for basal vs r = 0.62, P < 0.05 for water). Our data suggest that age-related vagal dysfunction and reduced CC may be associated with SBRS differences between YG and OL groups, and with BP elevation during HOWI in healthy older men.

Adult↗
PubMed2005

Evidence for muon neutrino oscillation in an accelerator-based experiment.

We present results for nu(mu) oscillation in the KEK to Kamioka (K2K) long-baseline neutrino oscillation experiment. K2K uses an accelerator-produced nu(mu) beam with a mean energy of 1.3 GeV directed at the Super-Kamiokande detector. We observed the energy-dependent disappearance of nu(mu), which we presume have oscillated to nu(tau). The probability that we would observe these results if there is no neutrino oscillation is 0.0050% (4.0 sigma).

Journal Article↗
PubMed2005

Thermomechanical behavior of human carotid arteries in the passive state.

Localized heating or cooling is expanding the clinical procedures used to treat cardiovascular diseases. Advantageous implementation and development of these methods are linked indissolubly to a deeper understanding of the arterial response to combined mechanical and thermal loads. Despite this, the basic thermomechanical behavior of human blood vessels still remains largely unknown, primarily due to the lack of appropriate experimental data. In this work, the influence of temperature on the passive behavior of human carotid arteries was studied in vitro by means of inflation tests. Eleven carotid segments were tested in the range 0-200 mmHg at four different temperatures of 17, 27, 37, and 42 degrees C. The results show that the combined change of temperature and stress has a dramatic effect on the dilatation coefficient of the arterial wall, which is shifted from negative to positive depending on the stress state, whereas the structural stiffness of the arterial wall does not change appreciably in the range of temperatures tested.

Aged↗
PubMed2005

Impact of reproductive experience on women's smoking behaviour in Japanese nurses.

OBJECTIVES: The objectives of this study were to describe current and past smoking behaviour of female Japanese nurses, to examine factors associated with developing and stopping a smoking habit, and to examine how their reproductive experiences affect their smoking behaviour. STUDY DESIGN: A cross-sectional study. This study was a baseline survey of a prospective occupational cohort study. METHODS: A self-administered survey of 1748 female Japanese nurses aged over 20 years was conducted in Gunma prefecture, Japan, in 1999. RESULTS: Overall, 27.2% developed a smoking habit (current smokers, 19.8%; ex-smokers, 7.4%) and 72.2% were never smokers. Logistic regression analysis showed that the type of nursing certificate was statistically associated with developing a smoking habit. It also showed that the type of nursing certificate, work place, marital status and current pregnancy were statistically associated with smoking cessation. Currently pregnant women were more likely to stop smoking than non-pregnant women (adjusted odds ratio, 3.18; 95% confidence intervals, 1.25-8.06). For women aged 20-29 years, the proportions of current smokers, ex-smokers and never smokers among pregnant women were 11.5, 23.1 and 65.4%, respectively; among non-pregnant women of this age, the values were 22.3, 4.3 and 73.4%, respectively. There was a statistically significant difference in such proportions between the two groups (chi2=19.27; P<0.0001). More than half of the ex-smokers who were currently pregnant had stopped smoking in the last 12 months. Smoking behaviour showed no statistically significant difference between women who had had at least one delivery and women who had not. CONCLUSIONS: The results suggest that pregnancy provides a good opportunity for smoking cessation, but a large proportion of women who successfully quit smoking during pregnancy relapse after delivery.

Adult↗
PubMed2005

Association of MBL gene polymorphisms with major bacterial infection in patients treated with high-dose chemotherapy and autologous PBSCT.

A growing body of evidence indicates that genetic factors are involved in an increased risk of infection. We investigated whether mannose-binding lectin (MBL) gene polymorphisms that cause low levels of MBL are associated with the occurrence of major infections in patients, mainly bearing hematological malignancies, after high-dose chemotherapy (HDT) rescued by autologous peripheral blood stem cell transplantation (auto-PBSCT). A retrospective evaluation of 113 patients treated with HDT and auto-PBSCT revealed that the low-producing genotypes, B/B and B/LXA, were associated with major bacterial infection (P=0.0016, OR 7.9). We next performed a nation-wide large-scale study to assess the allele frequency of the MBL coding mutation in a total of 2623 healthy individuals in Japan. The frequency of allele B was estimated to be approximately 0.2, almost the same in seven different areas of Japan. This common occurrence suggests that MBL deficiency may play an important role in the clinical settings of immunosuppression.

Alleles↗
PubMed2005

Brachial-ankle pulse wave velocity: an index of central arterial stiffness?

Brachial-ankle pulse wave velocity (baPWV) is a promising technique to assess arterial stiffness conveniently. However, it is not known whether baPWV is associated with well-established indices of central arterial stiffness. We determined the relation of baPWV with aortic (carotid-femoral) PWV, leg (femoral-ankle) PWV, and carotid augmentation index (AI) by using both cross-sectional and interventional approaches. First, we studied 409 healthy adults aged 18-76 years. baPWV correlated significantly with aortic PWV (r = 0.76), leg PWV (r = 0.76), and carotid AI (r = 0.52). A stepwise regression analysis revealed that aortic PWV was the primary independent correlate of baPWV, explaining 58% of the total variance in baPWV. Additional 23% of the variance was explained by leg PWV. Second, 13 sedentary healthy men were studied before and after a 16-week moderate aerobic exercise intervention (brisk walking to jogging; 30-45 min/day; 4-5 days/week). Reductions in aortic PWV observed with the exercise intervention were significantly and positively associated with the corresponding changes in baPWV (r = 0.74). A stepwise regression analysis revealed that changes in aortic PWV were the only independent correlate of changes in baPWV (beta = 0.74), explaining 55% of the total variance. These results suggest that baPWV may provide qualitatively similar information to those derived from central arterial stiffness although some portions of baPWV may be determined by peripheral arterial stiffness.

Adolescent↗
PubMed2005

A mixture of pure cellulase, hemicellulase and pectinase improves broiler performance.

1. The effects of a mixture of pure enzymes (cellulase, hemicellulase and pectinase) and a commercial enzyme, Energex, were examined on performance and metabolisabilities in broiler chicks given a maize-soybean meal diet. Composition of the mixed enzyme was similar to Energex except that protease was not present. 2. Chicks were divided into three groups: control, mixed enzyme and Energex with 7 replicates per group. Male broiler chicks were raised at 25 degrees C in wire-floored cages for 12 d from 15 d of age. Feed and water were offered ad libitum. 3. The Energex group gained significantly more weight and the mixed enzyme group tended to gain more than the control. Feed intakes were similar and thus the feed conversion ratio of Energex was significantly improved while it tended to be improved by the mixed enzyme. 4. The mixed enzyme group showed significant improvement in carcase and muscle weight when compared with the control group. The mixed enzyme group also showed significant improvement in organic matter and crude protein metabolisabilities. In the groups given enzyme, abdominal fat weight tended to decrease. 5. It is concluded that a combination of cellulase, hemicellulase and pectinase is effective in improving organic matter and crude protein metabolisabilities and carcase yield of broilers on a maize-soybean meal diet.

Animal Feed↗
PubMed2005

Nested polymerase chain reaction for detection of the avian leukosis virus causing so-called fowl glioma.

The complete nucleotide sequence of the avian leukosis virus causing so-called fowl glioma has been previously determined. Primers were designed for detection of the fowl glioma-causal virus (FGV) based on the 3' untranslated region of the viral genome. The provirus and viral RNA of FGV were specifically detected in various organs and tissues, including feather pulp, from experimentally infected birds using nested polymerase chain reaction (PCR) and reverse transcription nested PCR. The prevalence of FGV was evaluated in 131 Japanese fowls of a zoological garden in Japan based on the detection of the FGV genome in feather pulp using PCR and the detection of viral antigen in faeces by enzyme-linked immunosorbent assay. FGV proviral DNA was detected in feather pulp of 52 birds (39.7%) by nested PCR. Later, nine dead birds from among the 52 were histologically diagnosed as having fowl glioma and found to have the proviral DNA in the affected brain. These results demonstrated that the PCR-based detection of FGV in feather pulp is useful for epidemiological studies on fowl glioma.

Animals↗
PubMed2005

Development of a simple method to evaluate medical staff radiation dose and its application to a software system supporting PET facility operation.

In recent years, positron-emitting labelled radiopharmaceuticals have come to be used in conjunction with positron emission tomography (PET) in various clinical diagnoses. Radiation exposure of the medical staff is a key issue in the design of PET facilities intended to handle large numbers of persons for PET diagnosis. As a first step, the radiation dose to individuals who received radiopharmaceuticals was calculated using a mathematical phantom model and the EGS4 electromagnetic cascade Monte Carlo code and MCNP Monte Carlo code. Dose rate behind a lead shield was also calculated for various lead thicknesses. The radiation dose distribution around a syringe containing a positron emitter was calculated. The calculated dose distributions were fitted to polynomial equations. These calculations were evaluated against measurements. The second step was to evaluate medical staff dose at a specified time by superimposing dose distribution from each person who received radioisotopes taking into account radioactive decay. In this way, we developed software to support PET facility operation, namely, planning, prediction, control of medical staff dose and facility operation. This system was also designed to schedule daily radiopharmaceuticals production and to manage radioactive wastes by taking decay time into account.

Body Burden↗
PubMed2005

Phenotypic differences between electrocardiographic and echocardiographic determination of hypertrophic cardiomyopathy in genetically affected subjects.

OBJECTIVES: In the molecular era, two types of phenotypic differences are recognized between electrocardiography (ECG) and echocardiography in hypertrophic cardiomyopathy (HCM); ECG abnormalities in carriers without left ventricular hypertrophy (LVH), and normal ECG patterns in carriers with LVH. The goal of this study was to evaluate the diagnostic value of ECG for detecting carriers without LVH, and also to assess normal ECG patterns in carriers with LVH from the genetic standpoint of HCM. SETTING: A matched case-control study in a university hospital and general hospitals in Japan. PATIENTS AND DESIGN: ECG and echocardiographic findings were analysed in 173 genotyped subjects (107 genetically affected, 66 unaffected) from families with disease-causing mutations in four genes. RESULTS: ECG abnormalities were found in 18 (54.5%) of 33 nonhypertrophic carriers, but only nine (13.6%) of 66 noncarriers (P < 0.001). For detecting nonhypertrophic carriers, ST-T abnormalities showed the highest accuracy amongst the three major ECG criteria. In contrast, normal ECG patterns were found in eight (10.8%) of 74 carriers with LVH. The sensitivity of ECG for detecting carriers with LVH in families with the cardiac myosin-binding protein C, cardiac troponin T and cardiac troponin I gene mutations was 83%, 88% and 94% respectively. CONCLUSION: These findings suggest that ECG may have favourable diagnostic value even for detecting nonhypertrophic carriers. Furthermore, diagnostic value of ECG may differ according to the genes involved. Our data may contribute to interpretation of phenotypic differences between ECG and echocardiography from the viewpoint of molecular genetics of HCM.

Adult↗
PubMed2005

Usefulness of a new immuno-radiometric assay to detect hepatitis C core antigen in a community-based population.

A new immuno-radiometric assay (IRMA) to detect hepatitis C virus (HCV) core antigen (HCVcAg) has been developed. The aim of the present study was to investigate the sensitivity and specificity of this IRMA to measure HCV antigenemia, based on the detection of HCV RNA as the gold standard, and to assess the utility of the IRMA in a community-based population. Anti-HCV positive residents in a hyperendemic area of HCV infection in Japan were studied. Serum levels of HCVcAg were measured using IRMA, and the presence of HCV RNA was determined by a qualitative reverse transcription-polymerase chain reaction (RT-PCR) assay. The sensitivity and the specificity of the IRMA were 96.4 and 100%, respectively. The sensitivity of the IRMA was similar between serological HCV group I (HCV genotypes 1a and 1b) (97.6%) and group II (HCV genotypes 2a and 2b) (94.0%). There was a strong correlation between serum HCVcAg level and HCV-RNA measured by a quantitative RT-PCR (r = 0.832, P < 0.0001). There also was a very strong correlation of HCVcAg level between IRMA measurements performed on serum and those performed on plasma (r = 0.984, P < 0.0001). In conclusion, this new IRMA is useful for the detection of HCV core antigen in a community-based population.

Female↗
PubMed2005

Effects of zinc and copper on adhesion and hemagglutination of Prevotella intermedia and Prevotella nigrescens.

This study investigated the mechanism of protein attachment to the surface of the putative periodontal pathogens Prevotella intermedia and Prevotella nigrescens in artificial gingival crevicular fluid, and ways to increase protein attachment to the bacterial cells. The effects of cations on protein attachment, bacterial adhesion, and hemagglutination were examined, and cation-binding components on both bacterial species were identified. The presence of cations, especially zinc, copper and cerium, increased attachment of human serum proteins to both bacterial species. In contrast, the presence of hydrophobic inhibitors or sugars had little effect. Protein attachment was reduced by heat treatment of the bacterial cells. Pretreatment of bacteria with human serum proteins inhibited adhesion of both species to buccal epithelial cells and hemagglutination. These effects were enhanced by the presence of zinc and copper during pretreatment. Using a chelating column, specific zinc- and copper-binding proteins were identified on the surfaces of both bacterial species.

Bacterial Adhesion↗
PubMed2005

Antimicrobial activity of murine lung cells against Staphylococcus aureus is increased in vitro and in vivo after elafin gene transfer.

Staphylococcus aureus is a pathogen often found in pneumonia and sepsis. In the context of the resistance of this organism to conventional antibiotics, an understanding of the regulation of natural endogenous antimicrobial molecules is of paramount importance. Previous studies have shown that both human and mouse airways express a variety of these molecules, including defensins, cathelicidins, and the four-disulfide core protein secretory leukocyte protease inhibitor. We demonstrate here by culturing mouse tracheal epithelial cells at an air-liquid interface that, despite the production of Defb1, Defb14, and Defr1 in this system, these cells are unable to clear S. aureus when exposed to this respiratory pathogen. Using an adenovirus (Ad)-mediated gene transfer strategy, we show that overexpression of elafin, an anti-elastase/antimicrobial molecule (also a member of the four-disulfide core protein family), dramatically improves the clearance of S. aureus. In addition, we also demonstrate that this overexpression is efficient in vivo and that intratracheal instillation of Ad-elafin significantly reduced the lung bacterial load and demonstrates concomitant anti-inflammatory activity by reducing neutrophil numbers and markers of lung inflammation, such as bronchoalveolar lavage levels of tumor necrosis factor and myeloperoxidase. These findings show that an increased antimicrobial activity phenotype is provided by the elafin molecule and have implications for its use in S. aureus-associated local and systemic infections.

Adenoviridae↗
PubMed2005

Normal radiographic anatomy of thoracic structures: analysis of 1000 chest radiographs in Japanese population.

The purpose of this paper was to study the frequency of visualization and characteristics of normal thoracic structures on posteroanterior (PA) chest radiographs in Japanese population. 1000 consecutive normal PA chest radiographs of men and women ranging in age from 20 years to 90 years were reviewed. Frequency of visualization and configuration of structures including (1) fissure lines such as major, minor, vertical fissure line, and accessory fissures, (2) vascular structures including normal apical opacity, aortic nipple, and descending aortic interface, and (3) other structures including air in the oesophagus, aortic pulmonary stripe, and diaphragm were studied. On PA chest radiographs: (1) minor fissure, superolateral major fissure, superomedial major fissure, vertical fissure line, superior accessory fissure, and inferior accessory fissure were visualized in 74.7%, 19.7%, 15.4%, 1.6%, 2.9% and 13.1%, respectively. (2) Normal apical opacity was seen in 3.7%, while aortic nipple was seen in 0.9%. Descending aortic interface was obliterated in 13.7%. (3) Air in the oesophagus and aortic pulmonary stripe were seen in 8.9% and 17.7%, respectively. Hemidiaphragm was obliterated in 10.3% on the right, and in 32.4% on the left. Scalloping of the diaphragm was seen in 10.6% on the right, 6.5% on the left, and 4.3% bilaterally. Frequency of visualization and characteristics of various normal anatomical structures on chest radiographs in Japanese population differ from those reported previously from the West. Familiarity with these normal thoracic structures and variations is important for our daily image interpretation.

Adult↗
PubMed2005

Prostaglandin EP4 receptor agonist augments fixation of hydroxyapatite-coated implants in a rat model of osteoporosis.

The reduced stability of hydroxyapatite (HA)-coated implants in osteopenic conditions is considered to be a major problem. We therefore developed a model of a boosted cementless implantation in osteopenic rats.Twelve-week-old rats were either ovariectomised (OVX) or sham-operated (SO), and after 24 weeks plain or HA-coated implants were inserted. They were treated with either a prostaglandin EP4 receptor agonist (ONO-4819) or saline for one month. The EP4 agonist considerably improved the osteoporosis in the OVX group. Ultrastructural analysis and mechanical testing showed an improvement in the implant-bone attachment in the HA-coated implants, which was further enhanced by the EP4 agonist. Although the stability of the HA-coated implants in the saline-treated OVX rats was less than in the SO normal rats, the administration of the EP4 agonist significantly compensated for this shortage. Our results showed that the osteogenic effect of the EP4 agonist augmented the osteoconductivity of HA and significantly improved the stability of the implant-bone attachment in the osteoporotic rat model.

Animals↗