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Biomedical subjects

H Okamoto

Publications and source records attributed to H Okamoto.

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

High prevalence of hepatitis B, C and delta virus infections among blood donors in Mongolia.

Serum samples obtained from 289 first-time and 114 repeat donors at the Blood Center of Mongolia (MBC) were tested for serological and molecular markers of hepatitis B virus (HBV), hepatitis C virus (HCV), and hepatitis delta virus (HDV) infections. Among the 403 blood donors, 33 (8.2%), 21 (5.2%), and 27 (6.7%) tested positive for hepatitis B surface antigen (HBsAg) and/or HBV DNA, HCV RNA, and HDV RNA, respectively. Collectively, 55 donors were viremic for one or more of these viruses, and included 54 first-time donors (18.7%) and 1 repeat donor (0.9%) (P < 0.0001). One discrepant case with HBsAg detectable only at MBC was negative for HBsAg, HBV DNA and anti-HBc in this study. Four donors who were HCV-viremic in this study were negative for anti-HCV by the MBC method. Further efforts to increase the sensitivity and specificity of the currently-used tests are urgently required in Mongolia. Three donors who were positive for anti-HBc and anti-HDV but negative for HBsAg, had both HBV DNA and HDV RNA. This suggests that introduction of a new anti-HDV serological test is useful for not only HDV screening but also HBV screening of anti-HBc-positive, HBsAg negative donors, considering a possibility of viral interference by coexisting HDV.

Adolescent↗
PubMed2005

General features of photoinduced spin dynamics in ferromagnetic and ferrimagnetic compounds.

Ultrafast photoinduced spin dynamics has been investigated by time-resolved magneto-optical Kerr spectroscopy for various ferromagnetic and ferrimagnetic compounds: FeCr2S4, CoCr2S4, CuCr2Se4, CdCr2Se4, La0.6Sr0.4MnO3, and SrRuO3. The temporal demagnetization process, which is observed commonly for all the compounds, essentially consists of two components: One is an instantaneous change which originates perhaps from multiple emissions of magnetic excitations during nonradiative decay of photoexcited carriers, and the other is a delayed response due to thermalization of the spin system. The time constant of the delayed change depends strongly on materials and is scaled with the magnetocrystalline anisotropy, indicating that spin-orbit coupling is a dominant interaction for this process.

Journal Article↗
PubMed2005

Large optical nonlinearity of semiconducting single-walled carbon nanotubes under resonant excitations.

We measured third-order nonlinear susceptibility (chi(3)) spectra in semiconducting single-walled carbon nanotubes (SWNTs) by the Z-scan method. |Imchi(3)| is remarkably enhanced under resonant excitation to the lowest interband transition, reaching 4.2 x 10(-6) esu and 1.5 x 10(-7) esu in SWNTs grown by the laser ablation and HiPco methods, respectively. A comparison of the transient absorption changes evaluated by degenerate and nondegenerate pump-probe measurements suggests that the resonant enhancement of |Imchi(3)| is dominated by a coherent process rather than by saturation of absorption.

Journal Article↗
PubMed2005

Clinical significance of Ki-67 proliferation index in disease progression and prognosis of patients with resected colorectal carcinoma.

BACKGROUND: The prognostic role of proliferation markers in patients with colorectal neoplasia is inconclusive. The aim of this study was to evaluate proliferation markers in patients with colorectal carcinoma, to relate these to standard clinicopathological findings and to investigate their potential role in the prediction of long-term survival. METHODS: Archived formalin-fixed, paraffin-embedded tissue samples from a cohort of 106 patients who underwent curative resection for colorectal carcinoma were analysed to determine a Ki-67 (MIB-1)-derived proliferation index (PI) using a double immunostaining technique. The relationship between PI and standard clinicopathological variables was assessed and its association with long-term survival evaluated. RESULTS: A significant association was found between PI and tumour (T) status (P = 0.001), lymph node (N) involvement (P = 0.0098), the presence of distant metastases (P < 0.010) and advanced stage of disease (P < 0.001). On multivariate analysis, PI was shown to be an independent prognostic factor for long-term survival (hazard ratio 2.1 (95 per cent confidence interval 1.1 to 4.1); P = 0.032). CONCLUSION: Cell proliferation is significantly associated with tumour progression and may be used to identify patients with a predicted adverse outcome after resection of colorectal carcinoma.

Adult↗
PubMed2005

Extended aortic bypass for atherosclerotic occlusive disease of high abdominal aorta.

We describe a case of acute renal failure caused by extension of an atherosclerotic occlusive process to the suprarenal aorta. A 68-year-old man underwent bypass grafting from the ascending aorta to the femoral arteries using straight and Y-grafts. Additional saphenous vein grafts were placed from the intra-abdominal portion of the graft to the left and right renal arteries and the splenic artery. As a consequence, relief of limb ischemia was achieved and dialysis could be discontinued.

Acute Kidney Injury↗
PubMed2005

Comparative study of two Japanese rhinoconjunctivitis quality-of-life questionnaires.

CONCLUSION: Two questionnaires were used to assess quality of life (QOL) in allergic rhinitis: the Japanese translation of the Rhino-conjunctivitis Quality of Life Questionnaire (RQLQJ) and an original Japanese QOL questionnaire (JRQLQ). Either questionnaire may be used to assess QOL depending on differences in target domains. OBJECTIVES: Although pollinosis is a common disease which has a major impact on patient QOL, no internationally standardized questionnaire has been available in Japan until now. The aim of this study was to compare two currently available QOL questionnaires for allergic rhinitis in Japan-the RQLQJ and JRQLQ-in terms of their appropriateness for clinical use and their psychometric properties. MATERIAL AND METHODS: A multicenter, inter-group, cross-sectional study was conducted in 187 adult symptomatic patients with Japanese cedar pollinosis in 2003. Patient scores on the two questionnaires were compared in terms of both overall and comparable domains. We also examined the acceptability, construct and reliability of both questionnaires. RESULTS: The questionnaires were highly correlated in terms of both overall and comparable domain scores. In addition, both questionnaires had equal and satisfactory psychometric validity, demonstrating that they are both useful tools for assessing QOL in rhinitis. However, when compared with each other, the JRQLQ focuses mainly on activities of daily life and is simpler, while the RQLQJ focuses mainly on rhinitis-related health and is more responsive.

Adult↗
PubMed2005

Selective expansion of CD16highCCR2- subpopulation of circulating monocytes with preferential production of haem oxygenase (HO)-1 in response to acute inflammation.

Monocytes are composed of two distinct subpopulations in the peripheral blood as determined by their surface antigen expressions, profiles of cytokine production and functional roles played in vivo. We attempted to delineate the unique functional roles played by a minor CD16(high)CCR2(-) subpopulation of circulating monocytes. They produced significant levels of interleukin (IL)-6 and tumour necrosis factor (TNF)-alpha, but very low levels of IL-10 upon in vitro stimulation. Characteristic profiles of cytokine production were confirmed by stimulating purified subpopulations of monocytes after cell sorting. It was noteworthy that freshly isolated CD16(high)CCR2(-) monocyte subpopulations produced significant levels of haem oxygenase (HO)-1, whereas the major CD16(low)CCR2(+) subpopulation produced little. These results were contrary to the generally accepted notion that the CD16(high)CCR2(-) monocyte subpopulation plays a predominantly proinflammatory role in vivo. The CD16(high)CCR2(-) subpopulation increased in Kawasaki disease and influenza virus infection. In accord with this, HO-1 mRNA expression by mononuclear cells was significantly increased in these illnesses. These results indicate that CD16(high)CCR2(-) subpopulations are of a distinct lineage from CD16(low)CCR2(+) monocytes. More importantly, they may represent a monocyte subpopulation with a unique functional role to regulate inflammation by producing HO-1 in steady state in vivo.

Acute Disease↗
PubMed2005

The dependence of the auditory evoked N1m decrement on the bandwidth of preceding notch-filtered noise.

The auditory evoked response is known to be changed by a preceding sound. In this study we investigated by means of magnetoencephalography how a preceding notch-filtered noise (NFN) with different bandwidths influences the human auditory evoked response elicited by the following test stimulus. We prepared white noise (WN) and four NFNs which were derived from WN by suppressing frequency regions around 1 kHz with 1/8-, 1/4-, 1/2- and 1-octave bandwidths. Stimulation for 3 s with this set of noises resulted in differences in responsiveness to a 1-kHz test tone presented 500 ms after the offset of the noises. The N1m response to the 1-kHz test tone stimulus was at a minimum when the preceding NFN had 1/4-octave stop-band frequencies as compared with 1/8-, 1/2- and 1-octave NFN and WN. This N1m decrement is explained by the imbalanced neural activities caused by habituation and lateral inhibition in the auditory system. The results contribute to understanding of the inhibitory system in the human auditory cortex.

Acoustic Stimulation↗
PubMed2005

Single nucleotide polymorphisms in the gene encoding the major histocompatibility complex class II transactivator (CIITA) in systemic lupus erythematosus.

BACKGROUND: The major histocompatibility complex (MHC) class II transactivator (CIITA) is a master switch of antigen presentation and activates expression of the MHC II gene. Insufficient up regulation of MHC class II molecules is reported to be one of the major immunological mechanisms in systemic lupus erythematosus (SLE). OBJECTIVE: To examine the association between single nucleotide polymorphisms (SNPs) in the human CIITA gene (MHC2TA) and SLE. METHODS: Promoters and coding regions of MHC2TA were evaluated for polymorphisms in 100 patients with SLE and 100 healthy donors. Eight oligonucleotide primer sets that covered the coding region and each promoter region were used for genomic analysis of SNPs. RESULTS: Allele frequencies of previously reported SNPs did not differ between healthy donors and patients with SLE. Additionally, a new polymorphism in an intronic region at nt 485 (A-->A/G) was identified, which is close to the polymorphism at nt 474 that has been associated with one of the disease causing CIITA cDNA mutations in bare lymphocyte syndrome. This SNP was found in 11% of patients with SLE and in 3% of healthy donors, suggesting it may have a role in the pathogenesis of SLE. CONCLUSIONS: A newly identified polymorphism in an intronic region at nt 485 (A-->A/G) may have an important role in the pathogenesis of SLE.

Adolescent↗
PubMed2005

Localization of am3 using EL congenic mouse strains.

EL/Sea mice have 100% incidence of the absence of third molars (M3). Our previous linkage analysis using EL/Sea and MSM/Msf mouse strains provides statistical evidence of a major locus for the absence of M3, designated am3, of EL/Sea at the middle region of chromosome 3. To obtain independent evidence for linkage and more precisely determine the location of the am3 locus, we generated EL/Sea congenic strains for am3 in which the restricted interval of chromosome 3 of EL/Sea was replaced by an MSM/Msf-derived homologue. EL/Sea congenic mice that were either heterozygous or homozygous for the MSM/Msf-derived interval exhibited a significant decrease in the incidence of the absence of third molars, confirming previous genome scan results. These results confine the am3 locus to an approximately 4.4-cM region, and demonstrate that other unmapped genes are also involved in the absence of M3 in EL/Sea mice.

Animals↗
PubMed2005

Anti-CD38 autoimmunity in children with newly diagnosed type 1 diabetes mellitus.

AIMS: To test for anti-CD38 autoimmunity in children with newly-diagnosed type 1 diabetes mellitus (DM1). METHODS: Serum anti-CD38 autoantibodies were detected by Western blot in 270 children (130 girls, 140 boys, mean age 8 +/- 4 years) with newly-diagnosed DM1 and 179 gender- and age-matched non-diabetic children. In 126 diabetic children, another blood sample was obtained 15 +/- 4 months after the diagnosis. RESULTS: Anti-CD38 autoantibody titers at least 3 SD above the mean value for the control group were found in 4.4% of children with DM1 vs 0.6% of controls (chi2 = 5.8, p <0.016). No statistical differences were observed between anti-CD38 positive and negative patients in terms of phenotype. At follow-up, of six diabetic children who were positive for anti-CD38 antibodies, two were new cases. A positive correlation was found between the antibody titer of diabetic sera at diagnosis and follow up (r = 0.46, p <0.0001). CONCLUSION: An autoimmune reaction against CD38, a protein expressed in human islets, is associated with newly-diagnosed DM1. In children with DM1, CD38 autoimmunity increases with time and persists.

ADP-ribosyl Cyclase 1↗
PubMed2005

[Aortic dissection induced by symmetry aortic connector system].

A 74-year-old male with severe triple vessel disease underwent off-pump coronary artery bypass grafting (OPCAB). Preoperative computed tomography (CT) showed severely calcified ascending aorta. We revasculize the left coronary arteries with in situ internal thoracic artery (ITA) graft and the right coronary artery with a saphenous vein graft, which was attached to the disease-free portion of the aortic root, using Symmetry aortic connector system (ACS). Although the operation was uncomplicated, and postoperative course was uneventful until the 5th postoperative day when acute type A aortic dissection occurred. The patient died of aortic rupture on the 7th postoperative day. Necropsy disclosed that the entry located just on the proximal anastomotic site of the vein graft. It is possible placement of ACS device would trigger the dissecting process. With regard to the use of these one-shot devices for diseased aorta, its safety needs further investigation, even though it might be placed on an apparently intact portion.

Aged↗
PubMed2005

Long-term results of combined iliac endovascular intervention and infrainguinal surgical revascularization for treatment of multilevel arterial occlusive disease.

AIM: The purpose of this study was to investigate the long-term results of combined iliac endovascular intervention and infrainguinal surgical revascularization. METHODS: A retrospective review of 39 infrainguinal bypasses combined with iliac endovascular intervention in 35 patients over a 16-year period was performed (Combined group). These results were compared to those of 43 infrainguinal bypasses performed with suprainguinal bypass operation in 39 patients (Surgical group), who had iliac lesions not amenable to angioplasty/stenting. There was no significant difference in the preoperative limb ischemic symptoms between them. RESULTS: Although the proportion of patients with coronary artery disease in the Combined group was significantly higher than that in the Surgical group, there was a trend toward lower morbidity/mortality in the Combined group compared with the Surgical group (8.6% vs 15.4%; P=0.3706). No significant differences in the rates of clinical and hemodynamic improvement and limb salvage rate were observed between the two groups. The primary patency rate of infrainguinal bypass at 1, 3, and 5 years was 83.2%, 80%, and 71.2% in the Combined group, and 97.1%, 89.9%, and 80.5% in the Surgical group, respectively. The secondary patency rate at 1, 3, and 5 years was 91.9%, 91.9%, and 76.3% in the Combined group, and 97.1%, 89.9%, and 84.6% in the Surgical group, respectively. Importantly, there was no significant difference in the primary/secondary patency rates between the two groups (Kaplan-Meier, log-rank test, primary patency, P=0.116; secondary patency, P=0.4407). CONCLUSIONS: Infrainguinal surgical reconstruction combined with iliac endovascular procedure may reduce operative risk, and further, long-term patency is comparable to that in the Surgical group.

Aged↗
PubMed2005

Persistent sciatic artery in a patient with extracranial internal carotid artery aneurysm and infrarenal abdominal aortic aneurysm. A case report.

A rare case of a persistent sciatic artery (PSA) in a patient with aneurysms of the internal carotid artery and abdominal aorta is presented. A 70-year-old man was referred with intermittent claudication of the right lower extremity. Angiography and computed tomography demonstrated that this symptom was due to occlusion of the PSA. On preoperative examinations, aneurysms of the extracranial internal carotid artery and abdominal aorta were incidentally discovered, and then surgically treated prior to the management of PSA. Systemic examinations must be performed in patients with PSA in order to scrutinize associated anomalies or vascular disease.

Aged↗
PubMed2004

Generating ultralow-emittance ion beams in a storage ring.

Laser cooling of heavy-ion beams in a storage ring is systematically studied with a multiparticle simulation code where not only exact lattice characteristics and space-charge forces but also realistic laser-ion interactions can be incorporated. The resonant coupling method is applied in order to extend the powerful longitudinal photon pressure to the transverse degrees of freedom. It is shown that, in spite of a space-charge-induced tune shift, the synchrobetatron resonance mechanism required for fast damping of transverse oscillations operates throughout the cooling process. Extremely efficient three-dimensional cooling of stored ion beams is thus feasible. It is demonstrated that, at low line density, normalized root-mean-squared emittances of the order of 10(-12) m.rad can be reached in all three directions by employing only existing technologies.

Journal Article↗
PubMed2004

One-dimensional ordering of ultra-low-density ion beams in a storage ring.

The two-particle model, first introduced by Hasse, is employed to predict the beam temperature at which a one-dimensional ordered state of ions will be established in a cooler storage ring. The proposed state does not have the ions (in the beam frame) at rest, but simply has them not passing each other; i.e., remaining in the same (ordered) sequence. The model is applicable to an ultra-low-density beam where collective Coulomb interactions are negligible. It is pointed out that the nature of the anomalous beam behavior observed in electron-cooling experiments at GSI (Darmstadt) and MSL (Stockholm) is approximately free from such parameters as the lattice design, ion species, beam density, and energy. On the basis of the model, which is put in Hamiltonian form, scaled, and numerically studied, a universal criterion of one-dimensional beam ordering at low line density is derived. Analytic work is employed to explain the numerical results and derives an approximate criterion.

Journal Article↗