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Biomedical subjects

H Ito

Publications and source records attributed to H Ito.

At least 163 records · Page 9Linked to original sources

Cyclin A/cdk2 activation is involved in hypoxia-induced apoptosis in cardiomyocytes.

Cardiomyocytes are terminally differentiated cells characterized as withdrawal cell-cycle machinery, but nonetheless they are known to express cell-cycle regulators. Because many proteins related to the cell cycle induce apoptosis in proliferating cells, we examined the involvement of these proteins in the apoptosis pathway in cardiomyocytes. Primary rat cardiomyocytes were exposed to a severe hypoxic condition to induce apoptosis. The apoptosis rate of cardiomyocytes increased to approximately 40% under 24 hours of hypoxia as evaluated by the TUNEL method. The cyclin A protein level assessed by immunoblot analysis accumulated in a time-dependent manner in cardiomyocytes, but there was no increase in nonmyocytes. Hypoxia increased the activity of cyclin A-associated kinase but not the activity of cyclin E-associated kinase, and the apoptosis was inhibited by infection of dominant-negative cdk2 adenovirus, suggesting that cyclin A and its associated kinase play significant roles in the apoptosis of cardiomyocytes. To investigate the cyclin A-mediated apoptosis, we infected cultured cells with cyclin A adenovirus. Apoptosis was induced in 63+/-12% of the infected cardiomyocytes in contrast to only 12+/-3% of the LacZ-infected control cells. In addition, the cells in the hypoxic condition showed an increase in caspase-3 activity and a subsequent decrease in p21(cip1/waf1) protein, which is partly cleaved by caspase-3. These findings confirm that cyclin A-associated kinase mediates hypoxia-induced apoptosis in cardiomyocytes, and they also suggest that additional elements of the cell-cycle-dependent machinery participate in this mechanism.

Animals↗

CD4 T cell-mediated alloresistance to fully MHC-mismatched allogeneic bone marrow engraftment is dependent on CD40-CD40 ligand interactions, and lasting T cell tolerance is induced by bone marrow transplantation with initial blockade of this pathway.

Costimulatory blockade can be used to promote allogeneic marrow engraftment and tolerance induction, but on its own is not 100% reliable. We sought to determine whether one or the other of the CD4 or CD8 T cell subsets of the recipient was primarily responsible for resistance to allogeneic marrow engraftment in mice receiving costimulatory blockade, and to use this information to develop a more reliable, minimal conditioning regimen for induction of mixed chimerism and transplantation tolerance. We demonstrate that a single anti-CD40 ligand mAb treatment is sufficient to completely overcome CD4 cell-mediated resistance to allogeneic marrow engraftment and rapidly induce CD4 cell tolerance, but does not reliably overcome CD8 CTL-mediated alloresistance. The data suggest that costimulation, which activates alloreactive CTL, is insufficient to activate alloreactive CD4 cells when the CD40 pathway is blocked. The addition of host CD8 T cell depletion to anti-CD40 ligand treatment reliably allows the induction of mixed chimerism and donor-specific skin graft tolerance in 3 Gy-irradiated mice receiving fully MHC-mismatched bone marrow grafts. Thus, despite the existence of multiple costimulatory pathways and pathways of APC activation, our studies demonstrate an absolute dependence on CD40-mediated events for CD4 cell-mediated rejection of allogeneic marrow. Exposure to donor bone marrow allows rapid tolerization of alloreactive CD4 cells when the CD40 pathway is blocked, leading to permanent marrow engraftment and intrathymic tolerization of T cells that develop subsequently.

Animals↗

Changes in the composition of serum bile acid as a predictor of small bowel allograft rejection in rats.

Composition of bile acid was studied as a noninvasive rejection marker after small bowel transplantation (SBT). Orthotopic SBT were performed in rats, and they were divided into four groups: group 1, sham-operated rats; group 2, recipients with isografts; group 3, recipients with allografts treated with FK506; and group 4, recipients with untreated allografts. On postoperative days (POD) 5 and 7, the graft histology, intraluminal bacterial overgrowth, individual bile acids concentration of the recipient serum and bile were examined. On POD 5, early histological findings of acute rejection were observed in group 4, and the ratio of secondary bile acids of this group were significantly higher than the other groups. The bile acid changes were enhanced by bacterial overgrowth on POD 7. The ratio of secondary bile acids changed in relation to acute rejection after SBT, suggesting that they can be useful for early diagnosis of acute SBT allograft rejection.

Animals↗

Expression of type I, type II, and type X collagen genes during altered endochondral ossification in the femoral epiphysis of osteosclerotic (oc/oc) mice.

The osteosclerotic (oc/oc) mouse, a genetically distinct murine mutation that has a functional defect in its osteoclasts, also has rickets and shows an altered endochondral ossification in the epiphyseal growth plate. The disorder is morphologically characterized by an abnormal extension of hypertrophic cartilage at 10 days after birth, which is later (21 days after birth) incorporated into the metaphyseal woven bone without breakdown of the cartilage matrix following vascular invasion of chondrocyte lacunae. In situ hybridization revealed that the extending hypertrophic chondrocytes expressed type I and type II collagen mRNA, as well as that of type X collagen and that the osteoblasts in the metaphysis expressed type II and type X collagen mRNA, in addition to type I collagen mRNA. The topographic distribution of the signals suggests a possible co-expression of each collagen gene in the individual cells. Immunohistochemically, an overlapping deposition of type I, type II, and type X collagen was observed in both the extending cartilage and metaphyseal bony trabeculae. Such aberrant gene expression and synthesis of collagen indicate that pathologic ossification takes place in the epiphyseal/metaphyseal junction of oc/oc mouse femur in different way than in normal endochondral ossification. This abnormality is probably not due to a developmental disorder in the epiphyseal plate but to the failure in conversion of cartilage into bone, since the epiphyseal plate otherwise appeared normal, showing orderly stratified zones with a proper expression of cartilage-specific genes.

Animals↗

Peripheral deletion after bone marrow transplantation with costimulatory blockade has features of both activation-induced cell death and passive cell death.

Two major pathways of death of previously activated T cells have been described: activation-induced cell death can be triggered by restimulating activated T cells with high concentrations of Ag, is Fas-dependent, is not influenced by proteins of the Bcl family, and is blocked by cyclosporin A; in contrast, passive cell death is induced by the withdrawal of growth factors and activation stimuli, is Fas-independent, and is blocked by Bcl family proteins. We examined the role of these two forms of cell death in the peripheral deletion of donor-reactive host T cells after allogeneic bone marrow transplantation and costimulatory blockade with anti-CD154 plus CTLA4Ig in two murine models. The substantial decline in donor-reactive CD4 cells seen in wild-type recipients 1 wk after bone marrow transplantation with costimulatory blockade was largely inhibited in Fas-deficient recipients and in Bcl-x(L)-transgenic recipients. We observed these effects both in a model involving low-dose total body irradiation and a conventional dose of bone marrow, and in a radiation-free regimen using high-dose bone marrow transplantation. Furthermore, cyclosporin A did not completely block the deletion of donor-reactive CD4(+) T cells in recipients of bone marrow transplantation with costimulatory blockade. Thus, the deletion of donor-reactive T cells occurring early after bone marrow transplantation with costimulatory blockade has features of both activation-induced cell death and passive cell death. Furthermore, these in vivo data demonstrate for the first time the significance of in vitro results indicating that proteins of the Bcl family can prevent Fas-mediated apoptosis under certain circumstances.

Abatacept↗

Emergence of anti-inflammatory monocytes in long-term surviving hosts of IL-10-transduced liver allografts.

We previously reported that transduction of IL-10 to rat liver allografts facilitates survival prolongation after orthotopic liver transplantation (OLT). In the current study, we examined Lewis hosts of IL-10-transduced allografts that had survived longer than 50 days in order to characterize peripheral blood mononuclear cells (PBMC). Phenotype analysis of the PBMC demonstrated an 18-fold increase in monocytes (CD11b/c(+)) with a massive increase in the monocyte/lymphocyte ratio. The monocytes expressed downregulated MHC class II (RT1B) but upregulated Fcgamma receptors in comparison with monocytes from the control hosts. The capacity of enriched monocytes to secrete TNF-alpha in response to LPS stimulation was downregulated in the survivors, while production of IL-10 was comparable. The monocytes from long-term survivors significantly inhibited the donor antigen stimulated secretion of IFN-gamma and IL-2. Monocytosis characterized by a shift to anti-inflammatory monocytes is associated with survival prolongation in the hosts of IL-10 transduced liver allografts.

Animals↗

Persistently increased serum concentrations of cardiac troponin t in patients with idiopathic dilated cardiomyopathy are predictive of adverse outcomes.

BACKGROUND: The measurement of serum concentrations of cardiac troponin T (TnT) is a simple, useful method to detect myocyte injury that may be repeated multiple times to follow patients without interobserver variability. METHODS AND RESULTS: Multiple measurements of TnT with a second-generation assay were performed in 60 patients with dilated cardiomyopathy confirmed by coronary angiography and endomyocardial biopsy between April 1996 and December 1999. Three evolutionary patterns of TnT concentrations were identified. Thirty-three patients had concentrations of TnT <0.02 ng/mL throughout the follow-up period (group 1). The remaining 27 patients had high initial serum concentrations of TnT (>/=0.02 ng/mL). In 10 of these 27 patients, TnT decreased to <0.02 ng/mL during follow-up (group 2), whereas 17 had persistently high serum TnT concentrations despite being conventionally treated for chronic congestive heart failure (group 3). Although the initial echocardiographic left ventricular diastolic dimension (LVDd) and left ventricular ejection fraction (LVEF) were not significantly different among the 3 groups, follow-up echocardiography showed significantly decreased LVDd and increased LVEF in group 1 (each P:<0.01) and group 2 (each P:<0.05) compared with increased LVDd and decreased LVEF in group 3 (each P:<0.05). The cardiac event-free rate was significantly lower in group 3 than in groups 1 and 2 (each P:<0.001), and the survival rate was lower in group 3 than in group 1 (P:<0.05). CONCLUSIONS: Persistently increased TnT concentrations in dilated cardiomyopathy suggest ongoing subclinical myocyte degeneration associated with deterioration of the patients' clinical status.

Biopsy↗

Characterization of whole blood aggregation with a new type of aggregometer by a screen filtration pressure method.

A new type of platelet aggregometer of whole blood, based on the screen filtration pressure method, has been developed and characterized. It measures resistance of flow of whole blood samples through a screen of microsieve with 30-microm(2) openings and provides pressure rate as an index of platelet aggregation. On optical microscopic observation, platelet aggregates, but not fibrin fibers, were found to be trapped on microsieves, and the pressure rate and protein amounts on microsieves are correlated. The aggregometer showed good reproducibility for investigations performed on different days. The time course of pressure rates indicated a bell curve change, where the pressure rate was very low immediately after blood collection and gradually increased up to 60 min thereafter. Use of the aggregometer was able to confirm that orally administered aspirin inhibits ADP- and collagen-induced whole blood aggregation as well as platelet aggregation. The results suggest that this platelet aggregometer might be useful in research and clinical diagnosis of thrombotic diseases.

Adenosine Diphosphate↗

Neurogenic failures of the external urethral sphincter closure and relaxation; a videourodynamic study.

Urinary urgency and voiding difficulty are common features in neurological diseases, which can be attributed to dysfunction of the urethral sphincter and the detrusor. However, little is known about dynamic sphincter behaviour in neurological diseases. The present study aimed at investigating neurogenic failures of the external urethral sphincter closure and relaxation by videourodynamic study. We recruited 44 neurological patients with urinary urgency and frequency, 27 men and 17 women, mean age 61 years, and 28 of them had voiding difficulty as well. None had abnormal finding of digital examination or ultrasound echography of the pelvic organs. Using triple-lumen 7F catheter under X-ray fluoroscope, we measured detrusor pressure, external urethral sphincter pressure (Pura) and external sphincter EMG in all patients. We also performed pressure-flow study and obtained the Abram-Griffiths (AG) number, a numerical grade of obstruction. During filling 30 had detrusor hyperreflexia. EMG-cystometry showed uninhibited external sphincter relaxation (UESR) in eight patients, seven of whom had detrusor hyperreflexia as well. Patients with UESR showed an abnormal reduction of Pura, mean reduction 64 +/- 27 cmH2O (mean +/- standard deviation). During UESR the Pura and EMG activity fluctuated, and fluoroscopic image showed bladder neck opening in four with extreme urge sensation, including one without detrusor hyperreflexia. During an attempt of voiding three patients with voiding difficulty had detrusor-external sphincter dyssynergia (DESD) with detrusor contraction and eight had unrelaxing external sphincter without detrusor contraction. Fluoroscopic image showed an incomplete or absent urethral opening at the external sphincter. Four of them had severe straining on voiding together with intermittent increment of EMG activity without a normal funneling of the bladder neck. The mean reduction of Pura during voiding was 6.4 +/- 6.7 cmH2O and 5.0 +/- 9.5 cmH2O (in women and men, respectively) with DESD or unrelaxing external sphincter which was less than 39 +/- 25 cmH2O and 53 +/- 47 cmH2O in those without (P < 0.01). The mean AG number was 15 +/- 21 and 51 +/- 19 (for women and men, respectively) with DESD or unrelaxing external sphincter which was larger than 6.2 +/- 34 and 35 +/- 22 in those without (P < 0.05). In conclusion, UESR and DESD/unrelaxing external sphincter could be a factor for urinary urgency and voiding difficulty in neurological patients, evidence of central dysregulation affecting the Onuf's nucleus and its fibres to the external urethral sphincter.

Adolescent↗

Real-time detection system for quantitation of hepatitis C virus RNA: a comparison with the other three methods.

Real-time detection (RTD) system for quantitation of hepatitis C virus (HCV) was developed. Its sensitivity and usefulness were compared with the other three commercially available methods for quantitation of HCV. The sera of 166 patients positive for serum HCV RNA by Amplicor HCV test were assessed. HCV was detected in 78.5% (128/163) by branched DNA assay, in 88.8% (111/125) by HCV core protein assay, in 94.5% (156/165) by Amplicor HCV Monitor test, and in 97.0% (161/166) by the RTD system. The values of viral load by the RTD system were significantly well correlated with those obtained by the other three methods. In the 50 patients treated by interferons (IFNs), the range which predicts the highest sustained response rate was less than 0.5 Meq/ml for branched DNA assay (sustained response rate: 57.9% (11/19)), less than 1 kcopies/ml for Amplicor HCV Monitor test (85.7% (6/7)), and less than 10(4) copies/ml for RTD system (100% (7/7)). None of the patients with greater than or equal to 2.8 Meq/ml by branched DNA assay (n=14), greater than or equal to 250 kcopies/ml by Amplicor HCV Monitor test (n=19), or greater than or equal to 2x10(6) copies/ml by RTD system (n=16) obtained sustained response. In conclusion, RTD system was demonstrated to be the most sensitive method for quantitation of HCV, and useful for the prediction of sustained response to IFN therapy.

Journal Article↗

Increasing rice productivity and yield by manipulation of starch synthesis.

Plant productivity and yield are dependent on source-sink relationships, i.e. the capacity of source leaves to fix CO2 and the capacity of developing sink tissues and organs to assimilate and convert this fixed carbon into dry matter. Studies from our laboratories as well as others have demonstrated that rice productivity and yield are mainly sink-limited during its development because of limited capacity to utilize the initial photosynthetic product (triose phosphate). This limitation in triose phosphate utilization, evident at both the vegetative and reproductive stages of rice development, may be associated with limited capacity for carbohydrate synthesis in rice leaves (which are poor accumulators of starch) or feedback due to limited sink strength of developing seeds. Strategies in improving triose phosphate utilization by enhancing starch production in leaves and developing seeds by the expression of engineered genes for ADP glucose pyrophosphorylase, a key regulatory enzyme of starch biosynthesis, are discussed.

Arabidopsis↗

Identification of recurrent chromosomal rearrangements and the unique relationship between low-level amplification and translocation in glioblastoma.

To elucidate the structural abnormalities and the relationship between chromosome structural disorders and DNA copy number aberrations in tumor cells, we applied the techniques of spectral karyotyping (SKY), comparative genomic hybridization (CGH), and fluorescence in situ hybridization (FISH), using yeast artificial chromosome (YAC) probes for nine human glioblastoma cell lines. One striking finding was that independently derived cell lines had the same recurrent marker chromosomes. Seven recurrent chromosomes were detected by these cytogenetic methods. In particular, cell lines U251, SNB-19, and U373-MG showed very similar karyotypes. It is also interesting that regions of DNA amplification were found translocated and/or inserted at a high rate (91.7%). In all, there were 12 amplified loci in five of the nine cell lines. These amplified chromosomal bands were scattered on the chromosomes, including the normal chromosome, with one exception (7q32-qter in U373-MG). FISH with YAC clones mapping to these chromosomal regions as DNA probes often showed DNA probe signals not only at original chromosomal sites but also in translocated or inserted segments. This form of DNA amplification was characterized by low-level increases (four- to 10-fold) and by translocation or insertion of the relevant chromosomal locus. These studies shed light on typical derivative chromosomes and the relationship between DNA amplification and chromosomal translocation in glioblastoma.

Chromosome Aberrations↗

Are the care levels of people with dementia correctly assessed for eligibility of the Japanese long-term care insurance?

BACKGROUND: A new long-term care insurance system was launched in Japan in April 2000. OBJECTIVES: We performed the first national survey on special units of psychiatric hospitals for dementia patients to examine whether their disabilities were well reflected in the eligibility assessment. METHODS: Of all 248 dementia special units of psychiatric hospitals in Japan, 180 units (72.6%) participated in the survey. Five patients were randomly selected in each unit, and we used data of 802 (89.1%) of 900 patients whose care levels were obtained by the primary computer assessment. These patients were assessed using the Mini-Mental State Examination (MMSE), dementia rating scale by Gottfries et al. (1982) (GBS), and Activities of Daily Living (ADL). The mean score (SD) of the MMSE was 9.3 (6.9). RESULTS: Multiple regression analysis revealed that the scores of motor function in GBS, ADL, MMSE, and the degree of bedridden explained 73% of the variation of care level. The higher care levels were inversely related to lower MMSE scores. In the group of people who were not bedridden, the MMSE score sharply decreased even though their physical functions were maintained. There were no significant differences in the MMSE scores among the care level 1 and 5 groups except between care level 1 and 3 after controlling for the motor function scores in GBS. CONCLUSIONS: Our results suggest that care level and cognitive impairment are generally correlated in the primary assessment, but some adjustment measure for cognitive impairment is needed in mildly or moderately physically disabled patients.

Aged↗

Contrasting effects of midazolam on induction of heat shock protein 27 by vasopressin and heat in aortic smooth muscle cells.

We previously showed that vasopressin stimulates the induction of heat shock protein (HSP) 27, a low molecular-weight HSP, through protein kinase C activation in aortic smooth muscle A10 cells. In the present study, we examined the effects of midazolam, an intravenous anesthetic, on the HSP27 induction stimulated by vasopressin, heat, or sodium arsenite (arsenite) in A10 cells. Midazolam inhibited the accumulation of HSP27 induced by vasopressin or 12-O-tetradecanoylphorbol 13-acetate (TPA), a direct activator of protein kinase C. Midazolam also reduced the vasopressin-induced level of the mRNA for HSP27. In contrast, midazolam enhanced the HSP27-accumulation induced by heat or arsenite. Midazolam also enhanced the heat-increased level of the mRNA for HSP27. However, midazolam had no effect on the dissociation of the aggregated form of HSP27 following stimulation by vasopressin, heat, or arsenite. These results suggest that midazolam suppresses vasopressin-stimulated HSP27 induction in vascular smooth muscle cells, and that this inhibitory effect is exerted at a point downstream from protein kinase C. In contrast, midazolam enhanced heat- or arsenite-stimulated HSP27 induction. Thus, midazolam has dual effects on the HSP27 induction stimulated by various stresses in vascular smooth muscle cells.

Anesthetics, Intravenous↗

Multidrug resistance gene (MDR-1) expression as a useful prognostic factor in patients with human hepatocellular carcinoma after surgical resection.

BACKGROUND: Multidrug resistance gene (MDR-1) overexpression has been correlated with tumor aggressiveness and worse prognosis in some human neoplasms. The aim of this study is to evaluate the clinical value of MDR-1 mRNA expression as a prognostic factor after surgical resection in human hepatocellular carcinoma (HCC). METHODS: MDR-1 mRNA levels in tissue samples from 34 patients with HCC, who underwent surgical resection, were measured by quantitative northern blot analysis. We stratified these patients into two groups according to a ratio of MDR-1 mRNA levels of HCC to nontumorous tissue; MDR-1 mRNA ratio > or = 1.0 and < 1.0. The overall and disease-free survival rates were analyzed using multivariate regression analysis. RESULTS: The median survival periods were 10.3 and 35.8 months for patients with the MDR-1 mRNA ratio > or = 1.0 and < 1.0, respectively, and the corresponding 5-year survival rates were 33 and 54%, respectively, P < 0.05. The multivariate analysis revealed that TNM stage and MDR-1 mRNA ratio were independent factors for predicting overall survival after surgical resection. CONCLUSION: This study suggested that the measurement of the MDR-1 mRNA levels in HCC and nontumorous liver tissue might be a useful prognostic factor after surgical resection in patients with HCC.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Digital subtraction angiogram registration method with local distortion vectors to decrease motion artifact.

We have been investigating registration methods for improving digital subtraction angiography (DSA) images to extract blood vessels by reducing artifacts due to body motion, such as rotation, contraction, and dilation. In this paper, we propose a new and simple DSA registration algorithm with local distortion vectors to reduce artifacts. According to the results, the proposed method works well for vascular system around the nasal cavity and the orbit of the head and neck DSA images, which cannot be observed clearly by conventional methods. Additionally, we have applied the proposed method to abdominal and leg DSA images.

Algorithms↗

Overexpression of cdk Inhibitor p16INK4a by adenovirus vector inhibits cardiac hypertrophy in vitro and in vivo: a novel strategy for the gene therapy of cardiac hypertrophy.

Cardiac hypertrophy is one of the serious complications which increase mortality due to cardiovascular diseases. However, only a partial reduction of cardiac hypertrophy has been successful using current drug therapy. We demonstrate here reduction of cardiac hypertrophy in vitro and in vivo using an adenovirus vector encoding cyclin-dependent kinase (cdk) inhibitor p16INK4a. Adenovirus-mediated overexpression of cdk inhibitor p16INK4a completely inhibited cardiac myocyte hypertrophy induced by endothelin (ET)-1, as evaluated by [3H]leucine incorporation into the cells and mRNA levels of skeletal alpha -actin (SK-A) or atrial natriuretic peptide (ANP) as well as by morphometric analyses. We then evaluated whether p16INK4a can suppress left-ventricular (LV) hypertrophy induced by aortic banding (AOB) in rats. Catheter-mediated gene transfer of AxCAp16 was performed according to the method reported by Hajjar et al. LV overload was produced by coarctation of the ascending aorta immediately after inoculation of the heart with adenovirus. Two weeks after the procedure, the left ventricular weight/body weight ratio (LVW/BW) increased in the AOB+LacZ group in comparison to that in controls. However, LVW/BW was identical in the AOB+p16 group and controls. Histologic analysis revealed that p16INK4a inhibited hypertrophy of cardiac myocytes. These results suggest that G1 cell cycle regulators may restrict cardiac hypertrophy, and offer a novel strategy for the gene therapy of cardiac hypertrophy.

Actins↗

Error analysis for quantification of [(11)C]FLB 457 binding to extrastriatal D(2) dopamine receptors in the human brain.

To estimate receptor binding of ligand by positron emission tomography (PET) without an arterial input function, several quantitative approaches based on the use of a reference region have been proposed. We compared three approaches for quantifying extrastriatal D(2) dopamine receptors using [(11)C]FLB 457. The PET measurements were performed on seven healthy men. Binding potential (BP) of [(11)C]FLB 457 was calculated by the reference tissue model method, transient equilibrium method, and late time method. The reference tissue model describes the time-activity curve in a brain region in terms of that in the reference region, assuming that the levels of nondisplaceable radioligand binding in both regions are the same. The transient equilibrium theoretically occurs when the derivative for specific binding is zero. With the late time method, BP is calculated by integrating a late part of the time-activity curve. BP values obtained by all methods were in good agreement with those obtained by the kinetic approach, and the highest coefficient of correlation was observed in the reference tissue model method. In the simulation study, the error of BP calculated by the reference tissue model method was smallest. Moreover, the effect of the difference in the influx rate constant K(1) between the brain and the reference regions on BP was nearly avoided as theoretically predicted. We concluded that the reference tissue model method is most suitable for calculating BP of extrastriatal D(2) dopamine receptors with [(11)C]FLB 457.

Adult↗