Biomedical subjects

N Muramatsu

Publications and source records attributed to N Muramatsu.

At least 19 recordsLinked to original sources

PubMed2006

Differential cross section and photon-beam asymmetry for the gamma n --> K+ Sigma- reaction at E gamma = 1.5-2.4 GeV.

Differential cross sections and photon-beam asymmetries have been measured for the gamma n --> K+ Sigma- and gamma p --> K+Sigma0 reactions separately using liquid deuterium and hydrogen targets with incident linearly polarized photon beams of E gamma = 1.5-2.4 GeV at 0.6 < cos ThetacmK< 1. The cross section ratio of sigma K+ Sigma-/sigma K+ Sigma0, expected to be 2 on the basis of the isospin 1/2 exchange, is found to be close to 1. For the K+ Sigma- reaction, large positive asymmetries are observed, indicating the dominance of K* exchange. The large difference between the asymmetries for the K+ Sigma- and K+ Sigma0 reactions cannot be explained by simple theoretical considerations based on Regge model calculations.

Journal Article↗

PubMed2005

Near-threshold diffractive psi-meson photoproduction from the proton.

Photoproduction of a phi meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections at t = -|t|min do not increase smoothly as Egamma increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that phi mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

Journal Article↗

PubMed2004

Improved measurement of the K+-->pi+nunu; branching ratio.

An additional event near the upper kinematic limit for K+-->pi(+)nunu; has been observed by experiment E949 at Brookhaven National Laboratory. Combining previously reported and new data, the branching ratio is B(K+-->pi(+)nunu;)=(1.47(+1.30)(-0.89))x10(-10) based on three events observed in the pion momentum region 211<P<229 MeV/c. At the measured central value of the branching ratio, the additional event had a signal-to-background ratio of 0.9.

Journal Article↗

PubMed2003

Beam-polarization asymmetries for the p(gamma-->, K+)Lambda and p(gamma-->, K+)Sigma(0) reactions for E(gamma)=1.5-2.4 GeV.

Beam polarization asymmetries for the p(gamma-->,K+)Lambda and p(gamma-->,K+)Sigma(0) reactions are measured for the first time for E(gamma)=1.5-2.4 GeV and 0.6<cos((theta(c.m.)(K+))<1.0 by using linearly polarized photons at the Laser-Electron-Photon facility at SPring-8 (LEPS). The observed asymmetries are positive and gradually increase with rising photon energy. The data are not consistent with theoretical predictions based on tree-level effective-Lagrangian approaches. Including the new results in the development of the models is, therefore, crucial for understanding the reaction mechanism and to test the presence of baryon resonances which are predicted in quark models but are thus far undiscovered.

Journal Article↗

PubMed2003

Evidence for a narrow S = +1 baryon resonance in photoproduction from the neutron.

The gamman-->K(+)K(-)n reaction on 12C has been studied by measuring both K+ and K- at forward angles. A sharp baryon resonance peak was observed at 1.54+/-0.01 GeV/c(2) with a width smaller than 25 MeV/c(2) and a Gaussian significance of 4.6sigma. The strangeness quantum number (S) of the baryon resonance is +1. It can be interpreted as a molecular meson-baryon resonance or alternatively as an exotic five-quark state (uuddsmacr;) that decays into a K+ and a neutron. The resonance is consistent with the lowest member of an antidecuplet of baryons predicted by the chiral soliton model.

Journal Article↗

PubMed2002

Further evidence for the decay K+ -->pi+nu(nu).

Additional evidence for the rare kaon decay K+-->pi+nu(nu) has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211 pi+nu(nu)) = 1.57(+1.75)(-0.82)x10(-10).

Journal Article↗

PubMed2002

Expression of E-cadherin-catenin complex in human benign schwannomas.

The Ca2+-dependent cell adhesion molecule E-cadherin has been known to express in normal and reactive Schwann cells in rodents, and to play an important role in Schwann cell-Schwann cell adhesion and maintenance of peripheral nervous tissue architecture. However, little is known about expression of E-cadherin in schwannomas. The aim of the present study was to investigate the cellular expression and localization of E-cadherin, and its associated protein, alpha E-, alpha N- and beta-catenins in human schwannomas, which are supposed to derive from Schwann cells. We tested the hypothesis that these proteins might show an altered expression/distribution in schwannoma cells which correlates with their neoplastic behavior, including sparse cell-cell contact, as seen those in meningiomas and various carcinomas. In human schwannomas, however, E-cadherin, alpha E-catenin, and beta-catenin were detected by western blotting and immunohistochemistry, whereas alpha N-catenin was not. Immunoprecipitation using anti-E-cadherin antibody resulted in alpha E-catenin forming a complex with E-cadherin. SSCP analysis revealed no mutations in the transmembrane domain or in intracellular catenin-binding site of E-cadherin. These data suggest that the E-cadherin-alpha E-catenin complex is well preserved in human schwannoma cells, which is compatible with its benign behavior, and these molecules might be used as additional cell markers of Schwann cell-derived tumors.

Adult↗

PubMed2000

Measurement of structure-dependent K+ --> &mgr;(+)nu(&mgr;)gamma decay

We report the first measurement of a structure-dependent component in the decay K+-->&mgr;(+)nu(&mgr;)gamma. Using the kinematic region where the muon kinetic energy is greater than 137 MeV and the photon energy is greater than 90 MeV, we find that the absolute value of the sum of the vector and axial-vector form factors is |F(V)+F(A)| = 0.165+/-0.007+/-0.011. This corresponds to a branching ratio of B(SD+) = (1.33+/-0.12+/-0.18)x10(-5). We also set the limit -0. 04<F(V)-F(A)<0.24 at 90% C.L.

Journal Article↗

PubMed2000

Further search for the decay K+-->pi(+)nunu;

A search for additional evidence for the rare kaon decay K+-->pi(+)nunu; has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event. No new events were found in the pion momentum region examined, 211 pi(+)nunu;) = 1.5(+3.4)(-1.2)x10(-10).

Journal Article↗

PubMed2000

Hospital provision of institutional long-term care: pattern and correlates.

PURPOSE: This study examined the pattern and correlates of institutional long-term care provision among U.S. community hospitals, differentiating two categories of services: (1) skilled nursing and rehabilitation (SN-R) and (2) other long-term care (O-LTC). DESIGN AND METHODS: Multinomial logistic regression analysis was used to examine the associations of hospital and community characteristics with the pattern of long-term care provision (SN-R only, O-LTC only, both SN-R and O-LTC, and None) among 3,842 hospitals. RESULTS: The pattern of long-term care provision was significantly associated with hospitals' mission (for-profit and teaching status) and their internal and external resources. IMPLICATIONS: Results suggest the importance of considering hospital and community characteristics in predicting the impact of policy changes and in envisioning the role of hospitals in long-term care.

Continuity of Patient Care↗

PubMed1999

Galectin-1 regulates initial axonal growth in peripheral nerves after axotomy.

The signals that prompt the axons to send out processes in peripheral nerves after axotomy are not well understood. Here, we report that galectin-1 can play an important role in this initial stage. We developed an in vitro nerve regeneration model that allows us to monitor the initial axon and support cell outgrowth from the proximal nerve stump, which is comparable to the initial stages of nerve repair. We isolated a factor secreted from COS1 cells that enhanced axonal regeneration, and we identified the factor as galectin-1. Recombinant human galectin-1 (rhGAL-1) showed the same activity at low concentrations (50 pg/ml) that are two orders of magnitude lower than those of lectin activity. A similarly low concentration was also effective in in vivo experiments of axonal regeneration with migrating reactive Schwann cells to a grafted silicone tube after transection of adult rat peripheral nerve. Moreover, the application of functional anti-rhGAL-1 antibody strongly inhibited the regeneration in vivo as well as in vitro. The same effect of rhGAL-1 was confirmed in crush/freeze experiments of the adult mouse sciatic nerve. Because galectin-1 is expressed in the regenerating sciatic nerves as well as in both sensory neurons and motor neurons, we suggest that galectin-1 may regulate initial repair after axotomy. This high activity of the factor applied under nonreducing conditions suggests that galectin-1 may work as a cytokine, not as a lectin.

Animals↗

PubMed1999

Hospital length of stay in the United States and Japan: a case study of myocardial infarction patients.

Patients in Japan stay in the hospital significantly longer than those in the United States. This study investigates factors that may account for the difference from a sociocultural perspective. In an intensive case study on patients with uncomplicated acute myocardial infarction at a university hospital in Japan and its U.S. counterpart, the authors collected data from interviews with patients, their families, physicians, and other medical professionals and from medical, nursing, and billing records. Patients with comparable medical conditions were studied; U.S. patients stayed in the hospital for 8.8 days on average, Japanese patients for 25.0 days. The average total charge of hospitalization was 2.3 times higher in the United States than in Japan. Although length of stay is determined mainly by physicians' clinical judgment and by health care system factors, patients and their family members often actively participate in decision-making about discharge dates. This case study approach revealed how different health care systems manifest themselves in the individual patient's course of illness, which cannot be examined by macro-level comparison of nations' health care systems.

Adult↗

PubMed1998

High-performance liquid chromatographic determination of erdosteine and its optical active metabolite utilizing a fluorescent chiral tagging reagent, R-(-)-4-(N,N-dimethylamiosulfonyl)-7-(3-aminopyrrolidin-1-yl)-2 ,1,3-benzoxadiazole.

Chiral separation of racemic M1 metabolized from erdosteine was investigated by reversed-phase chromatography. The sensitive determination of M1 and erdosteine with UV detection was difficult because of their low absorptivity in the effective wavelength region. To improve the sensitivity and separatability, one thiol and two carboxyl groups in the M1 structure were labelled with DBD-F and R-(-)-DBD-APy, respectively. Non-fluorescent DBD-F quantitatively reacted with thiol in M1 at room temperature for 30 min in borate buffer (pH 9.3) to produce the fluorescent derivative. On the other hand, the labelling of two carboxyls was carried out with a chiral fluorescent reagent, R-(-)-DBD-APy, in acetonitrile containing DPPA. The derivatives corresponding to a pair of the enantiomers were completely separated with water-acetonitrile containing 0.1% TFA as the mobile phase by an ODS column. Erdosteine with a carboxyl group was also labelled with R-(-)-DBD-APy and separated together with M1 derivatives. The detection limits (S/N=3) of erdosteine and M1 were 0.37 and 0.22 pmol, respectively. The proposed derivatization and separation methods were applied to simultaneous determination of racemic M1 and erdosteine in rat plasma after administration of erdosteine. The amounts of both enantiomers of M1 were essentially the same in oral and intravenous administrations. In contrast, total amounts (reduced-form and oxidized-form) of S-(-)-M1 in rat plasma were higher than those of R(+)-M1 in both administrations.

Animals↗

PubMed1998

The cluster of arachnoid diverticula in the occipital bone: report of two cases with literature review.

The authors report two cases of multicentric osteolytic lesions in the occipital bone without any history of head trauma. The excisional biopsy of the first case revealed that the lesion was multicentric but a continuous cavity with the subarachnoid space through various sizes of dural defect, and the cavities were covered by arachnoid lining. Together with the previously reported similar 5 cases, the characteristic common feature is multicentric osteolytic lesions in the occipital bone at advanced age without marginal sclerosis. "The cluster of arachnoid diverticula in the occipital bone (CADOB)" is probably the most appropriate term for these non-traumatic lesions with the following characteristics: elderly patients, occipital bone, midline, multiple, intact outer table, nonsclerotic margin and without history of trauma. Operation may not be indicated because of its non-progressive and benign nature.

Aged↗

PubMed1997

Transitions in chronic low back pain in Japanese older adults: a sociomedical perspective.

This study examines the patterns and determinants of chronic low back pain over a three-year period among older adults in Japan. We tested our model based on a sociomedical perspective, using a two-wave national probability sample survey of persons aged 60 and older (N = 2,200) conducted in 1987 and 1990 in Japan. At baseline, the prevalence of chronic low back pain was 18 percent. Among those who were free of back pain at baseline, the probabilities of onset, death, and nonresponse were 13 percent, 7 percent, and 10 percent. Among those who had back pain at baseline, the probabilities of recovery, death, and nonresponse were 43 percent, 8 percent, and 9 percent, respectively. Our multinomial logistic regression analysis supports our thesis that societal factors (age, gender, education, and social relationships) affect transitions in chronic back pain not only directly, but also indirectly through mediating health and health behavior factors. The results suggest that social relationships have both favorable and unfavorable effects on chronic low back pain.

Aged↗

PubMed1997

Use of medical care by African American and White older persons: comparative analysis of three national data sets.

Historically, there has been a large gap between African Americans and Whites in access to health care, but this gap was ostensibly lessened by the advent of Medicare and Medicaid for older adults in the mid 1960s. The extent to which older African Americans continue to receive less access to medical care as a result of economic inequalities, institutionalized forms of discrimination, and life-style factors remains a subject of policy debate. Empirical enquiry has produced inconsistent results. The purpose of this study is to test the same set of models of medical use using identically measured predictor variables in three nationally representative data sets of older Americans: 1984 Study of Aging (SOA); 1984 National Long-Term Care Survey (NLTC); and the 1987 National Medical Care Expenditure Survey (NMES). Multivariate logistic regression of use of physician and hospital services and Poisson regression of amount of service use identified inconsistent results in race differences across data sets, but consistent results in terms of the importance of health status and insurance as predictors of use and amount of use. The findings suggest that health status and financial resources may be more relevant areas for policy interventions than considerations related to race and ethnicity.

Black or African American↗

PubMed1997

Determinants of mental health providers' expectations of patients' improvement.

OBJECTIVE: Characteristics of individual mental health providers and of treatment settings were examined to determine their effects on providers' expectations about the improvement of patients with serious mental illness. METHODS: The sample consisted of 1,567 treatment providers working in 107 inpatient and outpatient units or programs in 29 Veterans Affairs mental health facilities. They completed a questionnaire about their prognostic expectations and a broad range of attitudes toward job satisfaction, professional relations, and team functioning. Unit or program directors of all 107 units completed another questionnaire about the average functional ability of patients, unit workload, and unit size. Hierarchical linear modeling was used to assess the effects of both individual and unit-level attributes on providers' expectations of improvement in clinical symptomatology and social-functional skills of patients in their care. RESULTS: The providers had generally low expectations about the improvement of patients with serious mental illness. Expectations were higher among staff in units or programs that were smaller and that had an outpatient focus, a greater proportion of staff involved in the treatment team, and higher-functioning patients. Individual characteristics significantly associated with prognostic expectations were occupation, age, and membership on the treatment team. CONCLUSIONS: Prognostic expectations among providers of care to persons with serious mental illness vary with identifiable individual and unit or program characteristics. The latter may be amenable to manipulation and intervention to improve mental health providers' prognostic expectations.

Attitude of Health Personnel↗

PubMed1996

Study on neurotoxic shellfish poisoning involving the oyster, Crassostrea gigas, in New Zealand.

Lipid-soluble polyether marine toxins were isolated from 80% methanol extract of oysters, Crassostrea gigas, harvested in 1993 at Tiki Road, Coromandel Peninsula, New Zealand, by chromatography on columns of LH-20 and ODS (C18), followed by reversed-phase high-performance liquid chromatography. They were identified as known brevetoxins, PbTx-2 and 3. PbTx-3 was also isolated from oysters collected at Rangaunu Harbour in February 1994 and June 1995, followed by the above procedures.

Animals↗