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Biomedical subjects

Kenji Ito

Publications and source records attributed to Kenji Ito.

12 recordsLinked to original sources
PubMed2006

Inner-valence states of N2+ and the dissociation dynamics studied by threshold photoelectron spectroscopy and configuration interaction calculation.

The N2(+) states lying in the ionization region of 26-45 eV and the dissociation dynamics are investigated by high-resolution threshold photoelectron spectroscopy and threshold photoelectron-photoion coincidence spectroscopy. The threshold photoelectron spectrum exhibits several broad bands as well as sharp peaks. The band features are assigned to the N2(+) states associated with the removal of an inner-valence electron, by a comparison with a configuration interaction calculation. In contrast, most of the sharp peaks on the threshold photoelectron spectrum are allocated to ionic Rydberg states converging to N2(2+). Dissociation products formed from the inner-valence N2(+) states are determined by threshold photoelectron-photoion coincidence spectroscopy. The dissociation dynamics of the inner-valence ionic states is discussed with reference to the potential energy curves calculated.

Journal Article↗
PubMed2006

Study of hemodynamic changes in portal systemic shunts and their relation to variceal relapse after endoscopic variceal ligation combined with ethanol sclerotherapy.

BACKGROUND: Among the factors influencing variceal relapse after endoscopic treatment, portal hemodynamic changes, especially in portal systemic shunts, could be the most important factor because hemodynamics are directly related to the development of esophageal varices. We aimed to clarify the influence of endoscopic treatment for esophageal varices on portal systemic shunts as well as its predictive value for variceal relapse. METHODS: Fifty patients who underwent combined endoscopic variceal ligation and injection sclerotherapy were examined with sonography and portography. RESULTS: Decrease of diameter, hepatopetal flow direction in the left gastric vein, or the presence of non-varices portal systemic shunt were sonographic findings related to a low incidence of variceal relapse. The presence of blood flow in and around the esophagus on venograms was highly predictive for variceal relapse. In patients with such venograms, non-varices portal systemic shunts did not develop. CONCLUSIONS: Sonographic assessment of hemodynamic changes in portal systemic shunt could be useful for estimating the results of endoscopic treatment for esophageal varices.

Esophageal and Gastric Varices↗
PubMed2006

Development of a safe guidewire.

As the result of a locking phenomenon that may occur in a guidewire inside a metal puncture needle when using the Seldinger technique to insert a central venous catheter, the guidewire can break and cause an embolism. To counter this possibility we devised a guidewire with a structure that made it difficult for locking to occur and compared it to conventional guidewires. Conventional guidewires are wound lengthways with a spring. The improved version has a special multi-ply structure. A series of 100 cases were divided into two groups: group A, the conventional guidewire group; and group B, the improved guidewire group. We punctured the internal jugular vein and attempted insertion of the guidewire through the side hole of a 22-gauge metal needle. We then compared the frequency of locking and the frequency of bending of the guidewire tips that have been withdrawn. In group A, locking occurred in 72% of the cases where the guidewire was unable to be inserted, but this figure was 0% in group B. The improved guidewire has the advantage of reducing the risk of locking and of guidewire breakage.

Catheterization, Central Venous↗
PubMed2005

Acute treatment with morphine augments the expression of serine racemase and D-amino acid oxidase mRNAs in rat brain.

To obtain further insight into the interactions between the N-methyl-D-aspartate receptor and opioid receptor systems, we have investigated the effects of the acute treatment of morphine on the expression of serine racemase and D-amino acid oxidase mRNAs in several brain areas of rats. The morphine administration produced a dose-dependent and transient elevation in the levels of serine racemase and D-amino acid oxidase mRNAs in all the brain areas. The present results are the first to suggest an interaction between the expression of the mRNAs for the D-serine-related enzymes and the opioid receptor activation.

Analgesics, Opioid↗
PubMed2005

Osteogenic potential of injectable tissue-engineered bone: a comparison among autogenous bone, bone substitute (Bio-oss), platelet-rich plasma, and tissue-engineered bone with respect to their mechanical properties and histological findings.

Recently, tissue engineering has become available as a regenerative treatment for bone defects. However, the evaluation of its success is limited to histological analysis, and its effects on mechanical hardness remain to be investigated. This study investigated mechanical strength in support of histological findings, specifically for tissue-engineered bone with mesenchymal stem cells (MSCs) and platelet-rich-plasma (PRP). Initially, teeth were extracted, and bone defects on both sides of the mandible were prepared with a trephine bar. The defects were implanted by using the following graft materials: 1) PRP, 2) PRP and dog MSCs (dMSCs), 3) autogenous bone (PCBM), 4) bone substitute (Bio-Oss), and 5) control (defects only). After 2, 4, 8, and 12 weeks of implantation, the defects were histologically assessed to examine their mechanical properties. According to histological observations, the dMSCs/PRP groups had well-formed mature bone compared with the control (defects only), Bio-Oss, and PRP groups. The Vickers hardness test values were 8 (control), 9 (PRP), not detected (Bio-Oss), 11 (PCBM), and 17 (dMSCs/PRP) after 2 weeks. Therefore, tissue-engineered bone can be used for early stage bone regeneration from the viewpoint of histology and mechanical properties.

Animals↗
PubMed2005

Sinus floor elevation applied tissue-engineered bone. Comparative study between mesenchymal stem cells/platelet-rich plasma (PRP) and autogenous bone with PRP complexes in rabbits.

In the present study, we compared bone regeneration ability in sinus floor elevation between a tissue engineering method using mesenchymal stem cells (MSCs) and platelet-rich plasma (PRP), and a promising new method using particulate cancellous bone and marrow (PCBM) and PRP. Bilateral sinus floor elevation procedures were performed in 18 adult Japanese white rabbits. MSCs/PRP or PCBM/PRP complexes were grafted to each maxillary sinus in the same rabbits. The MSCs were isolated from rabbit iliac crest marrow, and PRP was obtained from peripheral blood. PCBM were collected from the rabbit iliac crest and mixed with PRP. The animals were sacrificed at 2, 4, and 8 weeks after transplantation, and the bone formation ability of each implant was evaluated histologically and histometrically. According to the histological observations, both sites (MSCs/PRP and PCBM/PRP) showed well newly formed bone and neovascularization at 2 and 4 weeks. However, at 8 weeks, the lamellar bone was observed to be occupied by fatty marrow in large areas in both sites. There was no significant difference in bone volume or augmented height between MSCs/PRP and PCBM/PRP groups each week, but there were significant differences in bone volume and augmented height between 2 and 8 weeks in PCBM/PRP or MSCs/PRP groups and in bone volume between 4 and 8 weeks in the PCBM/PRP group (P<0.05). These results suggest that the MSCs/PRP complex may well be used for bone regeneration in sinus floor elevation, compared with the PCBM/PRP complex.

Animals↗
PubMed2004

Rydberg-valence interactions of CO, and spectroscopic evidence characterizing the C' 1Sigma+ valence state.

Rotationally cold absorption and two-photon ionization spectra of CO in the 90-100 nm region have been recorded at a resolution of 0.3-1.0 cm(-1). The analyses of up to four isotopomers seek to clarify the observations in regions where the Rydberg levels built on the ground state X (2)Sigma(+) of the ion interact with valence states of (1)Sigma(+) and (1)Pi symmetry. Previous observations of the 3ssigma, B (1)Sigma(+) Rydberg state, reviewed by Tchang-Brillet et al. [J. Chem. Phys. 96, 6735 (1992)], have been extended to energies above its avoided crossing with the repulsive part of the D(') (1)Sigma(+) valence state where resonances of varying intensities and widths have been attributed to the fully coupled 3ssigma or 4ssigma and D(') potentials, and where the B state approaches a second avoided crossing with the C(') (1)Sigma(+) valence state [Cooper and Kirby, J. Chem. Phys. 87, 424 (1987); 90, 4895 (1989); Chem. Phys. Lett. 152, 393 (1988)]. Fragments of a progression of weak and mostly diffuse bands, observed for all four isotopomers, have been assigned to the C(')<--X transition. The least-squares modeling of the 4p and 5p complexes reveals the 3ppi, E (1)Pi Rydberg state to be one of the perturbers, violating the Deltav=0 selection rule for Rydberg-Rydberg interactions on account of its rapid transition with increasing v from Rydberg to valence state. A second (1)Pi perturber, very loosely bound and clearly of valence type, contributes to the confusion in the published literature surrounding the 5p, v=0 complex.

Journal Article↗
PubMed2002

Successful experiences with a handy equipment to measure dust concentrations in various workplaces.

Performance of a direct-reading handy equipment for dust counting in workroom air, PDR (MIE, USA), was field-tested in comparison with the results of low-volume air sampling-gravimetry. Application in 64 workplaces of various type dust work with dust concentrations of up to 1.6 mg/m3 showed that the agreement was generally good with a correlation coefficient (r) >0.64. The calculated regression line had a slope close to one, and the intercept on the axis was next to nil, suggesting that the measurement with PDR is essentially the same with that by low-volume air sampling. Further analysis by types of dust work disclosed that the correlation was best when examined in 12 foundries with r as large as 0.95. In contrast, r was small (0.52) in 11 welding workplaces, possibly due to smaller particle size of dust generated during welding.

Air Pollutants, Occupational↗
PubMed2002

Effect of ethanol on antigenicity of hepatitis B virus envelope proteins.

Hepatitis B e antigen-positive human serum was treated with 50-90% ethanol at room temperature for 1-60 min, then the antigenicity of S antigen (hepatitis B surface antigen, in a narrow sense) was determined by radioimmunoassay and the antigenicities of pre-S1 and pre-S2 antigens were measured by enzyme immunoassay. In addition, hepatitis B virus (HBV) DNA in the treated serum was detected by polymerase chain reaction. All antigenicities markedly decreased within 60 min at an ethanol concentration of 70-80%, and the decrease was faster in pre-S1 and pre-S2 antigens than in S antigen. Although HBV DNA remained in all ethanol-treated serum samples, no HBV DNA was detected after treatment with 1% sodium hypochlorite for 1 min. Based on the results, we speculate that one mechanism of loss of HBV infectivity by ethanol is the inhibition of virus binding to hepatocytes.

Ethanol↗