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Biomedical subjects

Y Yoda

Publications and source records attributed to Y Yoda.

At least 19 recordsLinked to original sources
PubMed2005

Normal mode analysis of Pyrococcus furiosus rubredoxin via nuclear resonance vibrational spectroscopy (NRVS) and resonance raman spectroscopy.

We have used (57)Fe nuclear resonance vibrational spectroscopy (NRVS) to study the Fe(S(cys))(4) site in reduced and oxidized rubredoxin (Rd) from Pyrococcus furiosus (Pf). The oxidized form has also been investigated by resonance Raman spectroscopy. In the oxidized Rd NRVS, strong asymmetric Fe-S stretching modes are observed between 355 and 375 cm(-1); upon reduction these modes shift to 300-320 cm(-1). This is the first observation of Fe-S stretching modes in a reduced Rd. The peak in S-Fe-S bend mode intensity is at approximately 150 cm(-1) for the oxidized protein and only slightly lower in the reduced case. A third band occurs near 70 cm(-1) for both samples; this is assigned primarily as a collective motion of entire cysteine residues with respect to the central Fe. The (57)Fe partial vibrational density of states (PVDOS) were interpreted by normal mode analysis with optimization of Urey-Bradley force fields. The three main bands were qualitatively reproduced using a D(2)(d) Fe(SC)(4) model. A C(1) Fe(SCC)(4) model based on crystallographic coordinates was then used to simulate the splitting of the asymmetric stretching band into at least 3 components. Finally, a model employing complete cysteines and 2 additional neighboring atoms was used to reproduce the detailed structure of the PVDOS in the Fe-S stretch region. These results confirm the delocalization of the dynamic properties of the redox-active Fe site. Depending on the molecular model employed, the force constant K(Fe-S) for Fe-S stretching modes ranged from 1.24 to 1.32 mdyn/A. K(Fe-S) is clearly diminished in reduced Rd; values from approximately 0.89 to 1.00 mdyn/A were derived from different models. In contrast, in the final models the force constants for S-Fe-S bending motion, H(S-Fe-S), were 0.18 mdyn/A for oxidized Rd and 0.15 mdyn/A for reduced Rd. The NRVS technique demonstrates great promise for the observation and quantitative interpretation of the dynamical properties of Fe-S proteins.

Iron Isotopes↗
PubMed2000

Observation of nuclear excitation by electron transition in 197Au with synchrotron X rays and an avalanche photodiode

We have succeeded in observing nuclear excitation by electron transition (NEET) in 197Au by a new method. Monochromatic x-rays of synchrotron radiation were used to ionize the K shell of gold atoms in a target foil. The internal-conversion electrons emitted from excited nuclei were detected with a silicon avalanche photodiode. At a photon energy of 80.989 keV, the NEET probability in 197Au was determined to be (5.0+/-0.6)x10(-8) from a comparison of the event number per photon between NEET and the nuclear resonance at 77.351 keV.

Journal Article↗
PubMed2000

Vascular endothelial growth factor expression and regulation of murine collagen-induced arthritis.

We have examined the expression and function of the angiogenic factor, vascular endothelial growth factor (VEGF) during the evolution of type II collagen-induced arthritis (CIA). Biologically active VEGF was expressed along a time course that paralleled the expression of two specific VEGF receptors, Flk-1 and Flt-1, and the progression of joint disease. Moreover, levels of VEGF expression correlated with the degree of neovascularization, as defined by vWF levels, and arthritis severity. Macrophage- and fibroblast-like cells, which infiltrated inflamed sites and were then activated by other inflammatory mediators, are probably important sources of VEGF and may thus regulate angiogenesis during the development of CIA. Administration of anti-VEGF antiserum to CIA mice before the onset of arthritis delayed the onset, reduced the severity, and diminished the vWF content of arthritic joints. By contrast, administration of anti-VEGF antiserum after the onset of the disease had no effect on the progression or ultimate severity of the arthritis. These data suggest that VEGF plays a crucial role during an early stage of arthritis development, affecting both neovascularization and the progression of experimentally induced synovitis.

Animals↗
PubMed2000

Precision wavelength measurement of the 14.4 keV Mössbauer photon.

The wavelength of the 14.4 keV Mössbauer photon has been determined by using undulator radiation and diffraction of FZ silicon crystals. For the wavelength determination a goniometer equipped with a laser rotary encoder and a sine-bar angle optical interferometer was developed; a temperature-monitoring system and X-ray optics related to the experiment were also developed. The mean wavelength was 0.08602557 nm with an uncertainty of 0.6 p.p.m., derived from 16 measurements of three pieces of FZ Si(840) crystals.

Journal Article↗
PubMed2000

Nuclear resonance scattering of synchrotron radiation by 40K

We have observed the excitation of the 29.83 keV nuclear level of the radioactive 40K nuclide, which level is not populated by any radioactive source, by synchrotron radiation for the first time. The absolute energy of the level of 29.834+/-0.011 keV and the half-life of 4.13+/-0.12 ns were obtained from our measurements. Our success in observing the nuclear excitation of radioactive 40K in a KCl powder sample shows the possibility for study of the local vibrational states and the electronic states of potassium in various areas of research.

Journal Article↗
PubMed2000

Expression of vascular endothelial growth factor by synovial fluid neutrophils in rheumatoid arthritis (RA).

Most of the leucocytes infiltrating rheumatoid synovial fluid (SF) are neutrophils capable of producing a variety of inflammatory mediators known to contribute significantly to the disease process during active RA. In the present study, we investigated the contribution made by SF neutrophils to the elevated levels of vascular endothelial growth factor (VEGF) seen in rheumatoid SF. Rheumatoid SF neutrophils were found to contain significantly larger amounts of both VEGF protein and its mRNA than peripheral blood neutrophils from either RA patients or healthy controls. Levels of cell-associated VEGF were well correlated with free VEGF in SF, which was significantly higher than in SF from osteoarthritis patients. Levels of SF neutrophil-associated VEGF also correlated with RA disease activity and cell surface integrin expression. Thus, SF neutrophil-associated VEGF may be considered an indicator of both local and systemic inflammation of RA, contributing to the neovascularization seen during RA synovitis.

Arthritis, Rheumatoid↗
PubMed1999

[A comparative study; one week treatment versus two weeks treatment with lansoprazol, amoxycillin and clarythromycin for the eradication of Helicobacter pylori in patient with gastric and duodenal ulcer].

The combination therapy of lansoprazol (LPZ), amoxycillin (AMPC), and clarythromycin (CAM) (LAC regimen) is one of the most effective eradication regimen of Helicobacter pylori (HP) positive ulcer patients, but the optimal treatment period of this therapy is still pending. The aim of this study was to assess the optimal treatment period of this regimen. One hundred and six patients who diagnosed as HP positive gastric and duodenal ulcer since August 1996 were randomized to one-week treatment group (group 1) or to two-weeks treatment group (group 2): LPZ 30 mg once daily, AMPC 1500 mg twice daily, CAM 800 mg twice daily. Both group received four weeks LPZ treatment (30 mg once daily) following the each combination therapy. The eradication rate of HP was 82.1% (43/56) in group 1 and 85.7% (36/42) in group 2. There was no statistical significant difference between two groups (p = 0.636). Although both treatment regimen was very useful for eradicating HP in the HP positive ulcer patients, one week LAC regimen would be better choice judging from the cost benefit.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1998

X-ray diffraction with a Bragg angle near pi/2 and its applications.

X-ray dynamical diffraction phenomena at a Bragg angle near pi/2 are studied. The X-ray transmissivity as well as the reflectivity from the (991) lattice plane of a silicon thin plate is observed. It agrees fairly well with the diffraction pattern calculated on the basis of the Darwin approach. The possibility is discussed whether a set of two crystal plates arranged face to face, in which the diffraction condition with a Bragg angle near pi/2 is satisfied, may be used as a very high resolution monochromator.

Journal Article↗
PubMed1998

X-ray parametric scattering by a diamond crystal.

Spontaneous X-ray parametric scattering from a diamond single crystal has been observed at the Photon Factory. The high perfection of the diamond single crystal and the small angular divergence of synchrotron radiation has enabled down-converted X-ray photon pairs to scatter into two small solid angles which satisfy the phase-matching condition. High-efficiency noise reduction was performed using avalanche photodiode detectors with good time resolution.

Journal Article↗
PubMed1998

A methylation imprint mark in the mouse imprinted gene Grf1/Cdc25Mm locus shares a common feature with the U2afbp-rs gene: an association with a short tandem repeat and a hypermethylated region.

We identified a sperm-specific methylation imprint mark (Site II) associated with a short tandem repeat sequence and a site/region methylated in both gametes (Site I) in the Grf1 locus on mouse chromosome 9, which shared a common feature with the U2afbp-rs gene. Sites or regions of gamete-specific methylation in imprinted genes are strong candidates for carrying information regarding the parental origin of alleles. The gamete-specific methylation pattern of Sites I and II was conserved after fertilization, but attained the somatic cell pattern by the blastocyst stage. In primordial germ cells, Site I was methylated, but Site II was unmethylated in both male and female embryos, suggesting that the sperm-specific methylation imprint mark in Site II was established during spermatogenesis. These common features in methylation imprint regions may be a clue to identifying regions carrying primary information for the imprinting regulation.

Animals↗
PubMed1997

Two-photon correlations in X-rays from a synchrotron radiation source.

The intensity correlation experiment using visible light performed by Hanbury Brown & Twiss [Nature (London) (1956), 177, 27-29] is extended to X-ray wavelengths. Correlations of 14.4 keV X-ray photons from a synchrotron radiation source are observed by the coincidence counting technique. The high brilliance of synchrotron radiation available in the Tristan main ring enables the observation of two-photon correlations with a reasonable measurement time.

Journal Article↗
PubMed1997

[Two-peak monoclonal protein (IgA kappa and IgG kappa) in non-Hodgkin lymphoma].

A 72-year-old man was admitted because of general weakness. On physical examination, marked splenomegaly was found. Blood tests revealed anemia, thrombocytopenia and two-peak hypergammaglobulinemia composed of kappa type IgG and IgA monoclonal proteins. Peripheral blood and bone marrow (BM) contained abnormal lymphocytes including plasmacytoid lymphocytes and/or plasma cells. Pathological examination of the biopsied BM showed non-Hodgkin lymphoma consistent with the lymphoplasmacytoid type. Immunohistochemical staining revealed two different populations of cells, one with IgG and the other with IgA; no cell stained both and no solitary cluster of either IgG or IgA positive cell was seen. The surface phenotype of the lymphoma cells was CD19+, CD20+, HLADR+. Double immunofluorescence staining of the BM smear showed IgG or IgA positive plasma cells, whereas small lymphocytes were negative for IgG and IgA. Analysis of immunoglobulin genes in the BM cells showed 2 rearranged bands in each of heavy chain genes and kappa light chain genes. The patient was treated with modified MVCP therapy and the two monoclonal proteins decreased in parallel with the improvement of splenomegaly. These findings strongly suggest that the two-peak monoclonal protein was produced by monoclonal lymphoma cells. The patients has been disease-free without any therapy since August, 1995.

Aged↗
PubMed1996

[An investigation of the factors influencing serum pepsinogen levels--sex, age, smoking, drinking].

BACKGROUND: Until now, the influence of sex, age, smoking, drinking on serum pepsinogen levels has been assessed by single regression analysis. However, the influence of those factors on pepsinogen levels should be assessed exactly by multiple regression analyses. SUBJECTS AND METHODS: 891 subjects were collected from by questionnaire and serum tests. Analyses were done with serum pepsinogen I (PG I), pepsinogen II (PG II) and pepsinogen I/II ratio (PG I/II) as a criterion variable and as categorized explanatory variables, sex, age, current or past smoking habit, and current drinking habit. And analyses are done by Mann-Whitney U test, correlation coefficient, single regression method, multiple regression method. RESULTS: PG I level is significantly higher in men than in women by Mann-Whitney U test. But the effect of sex factor is not remarkable by multiple regression analyses. PG II level increased and PG I/II level decreased with progression of age by all analyses methods. Current or past smoking elevates PG I level by Mann-Whitney U test, but current smoking dose and past smoking amount showed no dose-dependent associations with PG I level. Current drinking elevates PG I level by Mann-Whitney U test, but current drinking dose showed no dose-dependent associations with PG I. However, the effects of current smoking and current drinking to serum PG levels is not so large by multiple regression analyses. CONCLUSION: The effects of sex, current smoking and current drinking to serum PG levels are not remarkable by multiple regression analyses. Significantly, PG II level increased and PG I/II level decreased with progression of age. Therefore it may not be necessary to consider the effects of sex, smoking habit and drinking habit when serum pepsinogen levels are used as markers for gastric cancer.

Adult↗