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Hiromichi Hamada

Publications and source records attributed to Hiromichi Hamada.

17 recordsLinked to original sources
PubMed2006

Serum vascular endothelial growth factor in cyanotic congenital heart disease functionally contributes to endothelial cell kinetics in vitro.

BACKGROUND: Remarkable amounts of neovascularization develop in patients with cyanotic congenital heart disease who have low pulmonary blood flow and systemic cyanosis, but the factors functionally responsible for angiogenesis in cyanotic congenital heart disease have not been determined. METHODS AND RESULTS: To investigate the functional angiogenic molecules in serum from these patients, serum angiogenic activity was studied in 21 patients (systemic oxygen saturation: 82+/-1.9%) and in 17 healthy controls. Patient serum was more active in stimulating the tube formation of human umbilical vein endothelial cells (HUVECs) into capillary-like structures than control serum (150% vs 104% of internal control; p<0.001). This increased serum angiogenic activity normalized after total cardiac repair (p<0.001). The migration activity of HUVECs was also accelerated in patient serum (p=0.007). To identify the molecules in patient serum affecting tube formation of HUVECs, we examined the effects of an inhibitor or a neutralizing antibody against various angiogenic molecules on in vitro angiogenesis. Both the soluble vascular endothelial growth factor (VEGF) receptor 1 and the VEGF receptor 2 tyrosine kinase inhibitor SU5416 reduced the basal serum angiogenic activity of patients and this was reversed by a supplement of recombinant human VEGF. CONCLUSION: Our results indicate that serum VEGF functionally contributes to vascular endothelial cell kinetics in patients with cyanotic congenital heart disease.

Adolescent↗
PubMed2006

Estrogen receptors alpha and beta mediate contribution of bone marrow-derived endothelial progenitor cells to functional recovery after myocardial infarction.

BACKGROUND: Estradiol (E2) modulates the kinetics of circulating endothelial progenitor cells (EPCs) and favorably affects neovascularization after ischemic injury. However, the roles of estrogen receptors alpha (ER alpha) and beta (ER beta) in EPC biology are largely unknown. METHODS AND RESULTS: In response to E2, migration, tube formation, adhesion, and estrogen-responsive element-dependent gene transcription activities were severely impaired in EPCs obtained from ER alpha-knockout mice (ER alphaKO) and moderately impaired in ER betaKO EPCs. The number of ER alphaKO EPCs (42.4+/-1.5; P<0.001) and ER betaKO EPCs (55.4+/-1.8; P=0.03) incorporated into the ischemic border zone was reduced as compared with wild-type (WT) EPCs (72.5+/-1.3). In bone marrow transplantation (BMT) models, the number of mobilized endogenous EPCs in E2-treated mice was significantly reduced in ER alphaKO BMT (WT mice transplanted with ER alphaKO bone marrow) (2.03+/-0.18%; P=0.004 versus WT BMT) and ER betaKO BMT (2.62+/-0.07%; P=0.02 versus WT) compared with WT BMT (2.87+/-0.13%) (WT to WT BMT as control) mice. Capillary density at the border zone of ischemic myocardium also was significantly reduced in ER alphaKO BMT and ER betaKO BMT compared with WT mice (WT BMT, 1718+/-75/mm2; ER alphaKO BMT, 1107+/-48/mm2; ER betaKO BMT, 1567+/-50/mm2). ER alpha mRNA was expressed more abundantly on EPCs compared with ER beta. Moreover, vascular endothelial growth factor was significantly downregulated on ER alphaKO EPCs compared with WT EPCs both in vitro and in vivo. CONCLUSIONS: Both ER alpha and ER beta contribute to E2-mediated EPC activation and tissue incorporation and to preservation of cardiac function after myocardial infarction. ER alpha plays a more prominent role in this process. Moreover, ER alpha contributes to upregulation of vascular endothelial growth factor, revealing possible mechanisms of an effect of E2 on EPC biology. Finally, these data provide additional evidence of the importance of bone marrow-derived EPC phenotype in ischemic tissue repair.

Animals↗
PubMed2006

IL-10-induced TNF-alpha mRNA destabilization is mediated via IL-10 suppression of p38 MAP kinase activation and inhibition of HuR expression.

Inflammation plays an essential role in vascular injury and repair. Mononuclear phagocytes are important contributors in these processes, in part, via adhesive interactions and secretion of proinflammatory cytokines. The antiinflammatory cytokine interleukin (IL)-10 suppresses such responses via deactivation of monocytes/macrophages and repression of inflammatory cytokine expression. The mechanisms of IL-10's suppressive action are, however, incompletely characterized. Here, we report that systemic IL-10 treatment after carotid artery denudation in mice blunts inflammatory cell infiltration and arterial tumor necrosis factor (TNF) expression. At the molecular level, in a human monocytic cell line, U937 IL-10 suppressed LPS-induced mRNA expression of a number of inflammatory cytokines, mainly via posttranscriptional mRNA destabilization. Detailed studies on IL-10 regulation of TNF-alpha mRNA expression identified AU-rich elements (ARE) in the 3' untranslated region as a necessary determinant of IL-10-mediated TNF-alpha mRNA destabilization. IL-10 sensitivity to TNF depends on the ability of IL-10 to inhibit the expression and mRNA-stabilizing protein HuR and via IL-10 mediated repression of p38 mitogen-activated protein (MAP) kinase activation. Because IL-10 function and signaling are important components for control of inflammatory responses, these results may provide insights necessary to develop strategies for modulating vascular repair and other accelerated arteriopathies, including transplant vasculopathy and vein graft hyperplasia.

Animals↗
PubMed2006

Topical sonic hedgehog gene therapy accelerates wound healing in diabetes by enhancing endothelial progenitor cell-mediated microvascular remodeling.

BACKGROUND: Sonic hedgehog (Shh) is a prototypical morphogen known to regulate epithelial-mesenchymal interaction during embryonic development. Recent observations indicate that exogenous administration of Shh can induce angiogenesis and may accelerate repair of ischemic myocardium and skeletal muscle. Because angiogenesis plays a pivotal role in wound repair, we hypothesized that activation of the hedgehog pathway may promote a favorable effect on microvascular remodeling during cutaneous wound healing and thereby accelerate wound closure. Because diabetes is associated with impaired wound healing, we tested this hypothesis in a diabetic model of cutaneous wound repair. METHODS AND RESULTS: In Ptc1-LacZ mice, cutaneous injury resulted in LacZ expression, indicating that expression of the Shh receptor Patched was induced and therefore that the Shh signaling pathway was intact postnatally and upregulated in the process of wound repair. In diabetic mice, topical gene therapy with the use of naked DNA encoding for Shh resulted in significant local gene expression and acceleration of wound recovery. The acceleration in wound healing was notable for increased wound vascularity. In bone marrow transplantation models, the enhanced vascularity of the wound was shown to be mediated, at least in part, by enhanced recruitment of bone marrow-derived endothelial progenitor cells. In vitro, Shh promoted production of angiogenic cytokines from fibroblasts as well as proliferation of dermal fibroblasts. Furthermore, Shh directly promoted endothelial progenitor cell proliferation, migration, adhesion, and tube formation. CONCLUSIONS: These findings suggest that a simple strategy of topically applied Shh gene therapy may have significant therapeutic potential for enhanced wound healing in patients with impaired microcirculation such as occurs in diabetes.

Angiogenic Proteins↗
PubMed2006

Estradiol enhances recovery after myocardial infarction by augmenting incorporation of bone marrow-derived endothelial progenitor cells into sites of ischemia-induced neovascularization via endothelial nitric oxide synthase-mediated activation of matrix metalloproteinase-9.

BACKGROUND: Recent data have indicated that estradiol can modulate the kinetics of endothelial progenitor cells (EPCs) via endothelial nitric oxide synthase (eNOS)-dependent mechanisms. We hypothesized that estradiol could augment the incorporation of bone marrow (BM)-derived EPCs into sites of ischemia-induced neovascularization, resulting in protection from ischemic injury. METHODS AND RESULTS: Myocardial infarction (MI) was induced by ligation of the left coronary artery in ovariectomized mice receiving either 17beta-estradiol or placebo. Estradiol induced significant increases in circulating EPCs 2 and 3 weeks after MI in estradiol-treated animals, and capillary density was significantly greater in estradiol-treated animals. Greater numbers of BM-derived EPCs were observed at ischemic sites in estradiol-treated animals than in placebo-treated animals 1 and 4 weeks after MI. In eNOS-null mice, the effect of estradiol on mobilization of EPCs was lost, as was the functional improvement in recovery from acute myocardial ischemia. A decrease was found in matrix metalloproteinase-9 (MMP-9) expression in eNOS-null mice under basal and estradiol-stimulated conditions after MI, the mobilization of EPCs by estradiol was lost in MMP-9-null mice, and the functional benefit conferred by estradiol treatment after MI in wild-type mice was significantly attenuated. CONCLUSIONS: Estradiol preserves the integrity of ischemic tissue by augmenting the mobilization and incorporation of BM-derived EPCs into sites of neovascularization by eNOS-mediated augmentation of MMP-9 expression in the BM. Moreover, these data have broader implications with regard to our understanding of the role of EPCs in post-MI recovery and on the sex discrepancy in cardiac events.

Animals↗
PubMed2005

Sonic hedgehog myocardial gene therapy: tissue repair through transient reconstitution of embryonic signaling.

Sonic hedgehog (Shh) is a crucial regulator of organ development during embryogenesis. We investigated whether intramyocardial gene transfer of naked DNA encoding human Shh (phShh) could promote a favorable effect on recovery from acute and chronic myocardial ischemia in adult animals, not only by promoting neovascularization, but by broader effects, consistent with the role of this morphogen in embryogenesis. After Shh gene transfer, the hedgehog pathway was upregulated in mammalian fibroblasts and cardiomyocytes. This resulted in preservation of left ventricular function in both acute and chronic myocardial ischemia by enhanced neovascularization, and reduced fibrosis and cardiac apoptosis. Shh gene transfer also enhanced the contribution of bone marrow-derived endothelial progenitor cells to myocardial neovascularization. These data suggest that Shh gene therapy may have considerable therapeutic potential in individuals with acute and chronic myocardial ischemia by triggering expression of multiple trophic factors and engendering tissue repair in the adult heart.

Acute Disease↗
PubMed2005

Use of recombinant adeno-associated viral vectors as a tool for labeling bone marrow cells.

We have tested the feasibility of using recombinant adeno-associated virus (rAAV) vectors as a tool for labeling bone marrow (BM) cells in vivo. We infected BM cells of donor FVB mice with rAAV vectors containing the lacZ gene for 2 h. We then injected the rAAV-infected cells to lethally irradiated-recipient FVB mice. Peripheral blood (PB), BM and spleen harvested at 4 weeks after BM transplant (BMT) demonstrated stable engraftment in beta-galactosidase (beta-gal) expression. In contrast, Dil-labeling displayed only a faint signal 4 weeks after BMT. To analyze the kinetics of BM cells, we injected vascular endothelial growth factor (VEGF), which promotes mobilization of BM cells. Administration of VEGF protein significantly increased the rAAV-mediated beta-gal expression in PB and BM of recipient mice. Moreover, when myocardial infarction was induced in BMT mice, the ischemic area exhibited significant beta-gal staining in rAAV-labeled BMT group. rAAV vectors programmed stable transduction in BM cells in vivo through rapid infection. rAAV appears to represent a useful vector for labeling BM cells ex vivo prior to BMT for analysis of cardiovascular therapeutic purposes.

Animals↗
PubMed2004

Efficacy of intravenous immune globulin therapy combined with dexamethasone for the initial treatment of acute Kawasaki disease.

UNLABELLED: We studied the effects of a new regimen consisting of intravenous immune globulin (IVIG) combined with dexamethasone (DEX) on clinical outcome and serum levels of vascular endothelial growth factor (VEGF) in the initial treatment of Kawasaki disease (KD). A total of 46 KD patients received 0.3 mg/kg per day DEX plus heparin i.v. for 3 consecutive days, together with 2 g/kg IVIG over 4 to 5 days (DEX group). Low-dose acetylsalicylic acid was started after completion of DEX therapy. The control group consisted of 46 KD patients retrospectively treated earlier with 2 g/kg IVIG over 4 to 5 days plus higher dose acetylsalicylic acid (CONTROL group). No serious adverse effect was noted in either group. There were no differences in baseline and post-treatment laboratory data except for C-reactive protein between the groups. Post-treatment C-reactive protein in the DEX group (median 0.9 mg/dl, range 0.0 to 24.7 mg/dl) was lower than that (1.2 mg/dl, range 0.2 to 19.5 mg/dl) in the CONTROL group ( P=0.033 by Mann-Whitney U test). In addition, the mean duration of fever after the first IVIG infusion was 2.2 days (median 1 day, range 1 to 12 days) in the DEX group and 2.8 days (2 days, 1 to 16 days) in the CONTROL group ( P=0.015 by Mann-Whitney U test). The new regimen did not reduce VEGF levels. Two patients in each group developed small- or medium-sized coronary artery aneurysms. CONCLUSION: Although this regimen did not affect coronary outcome, intravenous immune globulin therapy combined with dexamethasone for the initial treatment of Kawasaki disease was safe and may accelerate the resolution of systemic inflammation.

Acute Disease↗
PubMed2004

Dilated cardiomyopathy caused by aberrant endoplasmic reticulum quality control in mutant KDEL receptor transgenic mice.

Aberrant protein folding beyond the capacity of endoplasmic reticulum (ER) quality control leads to stress response in the ER. The Lys-Asp-Glu-Leu (KDEL) receptor, a retrieval receptor for ER chaperones in the early secretory pathway, contributes to ER quality control. To elucidate the function of the KDEL receptor in vivo, we established transgenic mice expressing a mutant KDEL receptor. We found that the mutant KDEL receptor sensitized cells to ER stress and that the mutant mice developed dilated cardiomyopathy. Ultrastructural analyses revealed expanded sarcoplasmic reticulums and protein aggregates that obstructed the adjacent transverse tubules of the mutant cardiomyocytes. Cardiomyocytes from the mutant mice were sensitive to ER stress when treated with tunicamycin and showed a functional defect in the L-type Ca(2+) current. We observed ubiquitinated protein aggregates, enhanced expression of CHOP (a death-related transcriptional factor expressed upon ER stress), and apoptosis in the mutant hearts. These findings suggest that impairment of the KDEL receptor disturbs ER quality control, resulting in accumulation of misfolded proteins in the ER in an in vivo system, and that the dilated cardiomyopathy found in the mutant KDEL receptor transgenic mice is associated with ER stress.

Animals↗
PubMed2003

Role of TBX1 in human del22q11.2 syndrome.

BACKGROUND: Del22q11.2 syndrome is the most frequent known chromosomal microdeletion syndrome, with an incidence of 1 in 4000-5000 livebirths. It is characterised by a 3-Mb deletion on chromosome 22q11.2, cardiac abnormalities, T-cell deficits, cleft palate facial anomalies, and hypocalcaemia. At least 30 genes have been mapped to the deleted region. However, the association of these genes with the cause of this syndrome is not clearly understood. METHODS: To test for the chromosomal deletion at 22q11.2, we did fluorescence in-situ hybridisation analysis with ten probes on 22q11.2 in 235 unrelated patients with clinically diagnosed del22q11.2 syndrome. To investigate mutations in the coding sequence of TBX1, we also did genetic analysis in 13 patients from ten families who have the 22q11.2 syndrome phenotype but no detectable deletion of 22q11.2. FINDINGS: 96% (225 of 235) of patients had a defined 1.5-3-Mb deletion at 22q11.2. We identified three mutations of TBX1 in two unrelated patients without the 22q11.2 deletion-one with sporadic conotruncal anomaly face syndrome/velocardiofacial syndrome and one with sporadic DiGeorge's syndrome-and in three patients from a family with conotruncal anomaly face syndrome/velocardiofacial syndrome. We did not record these three mutations in 555 healthy controls (1110 chromosomes; p<0.0001). INTERPRETATION: Our results suggest that the TBX1 mutation is responsible for five major phenotypes in del22q11.2 syndrome. Therefore, we conclude that TBX1 is a major genetic determinant of the del22q11.2 syndrome.

Abnormalities, Multiple↗
PubMed2003

Prognostic impact of vascular leakage in acute Kawasaki disease.

BACKGROUND: Increased microvascular permeability is an initial step of Kawasaki disease (KD). We reported that vascular endothelial growth factor (VEGF) might play a role in the vascular leakage of KD. In fatal KD, plasma leakage was extensively documented at VEGF-positive microvessels. Increases in vascular leakage cause hypoalbuminemia and noncardiogenic edema. However, the prognostic impact of vascular leakage in KD remains unclear. METHODS AND RESULTS: We compared 76 patients who became afebrile within 5 days after starting intravenous gamma globulin (IVGG) (2 g/kg over 5 days) (IVGG-responsive) with 27 patients who did not respond (IVGG-resistant). Baseline levels of serum VEGF and albumin were similar between the groups. After IVGG, VEGF levels increased (P<0.0001) and albumin levels decreased (P<0.00001) in both groups. However, the IVGG-resistant group had higher VEGF levels (P=0.029) and severe hypoalbuminemia (P<0.00001) compared with the IVGG-responsive group. Coronary aneurysms were documented in 12 patients from the IVGG-resistant group but not in the IVGG-responsive group. Then IVGG-resistant patients were divided into 2 subgroups according to the presence (n=12) or absence (n=15) of coronary aneurysms. There was no difference between subgroups in age, sex, laboratory data including albumin, and retreated doses of IVGG. However, body weight gain after IVGG was documented in patients who subsequently developed coronary aneurysms (P=0.003) but not in those who did not (P=0.967). CONCLUSIONS: These results suggest that vascular leakage may be a key feature of KD pathophysiology. The present study may provide better insights into the pathogenesis and treatment of patients resistant to IVGG in acute KD.

Acute Disease↗
PubMed2003

The KDEL receptor modulates the endoplasmic reticulum stress response through mitogen-activated protein kinase signaling cascades.

The accumulation of misfolded proteins in the endoplasmic reticulum (ER) evokes the ER stress response. The resultant outcomes are cytoprotective but also proapoptotic. ER chaperones and misfolded proteins exit to the secretory pathway and are retrieved to the ER, during which process the KDEL receptor plays a significant role. Using an expression of a mutant KDEL receptor that lacks the ability for ligand recognition, we show that the impairment of retrieval by the KDEL receptor led to a mis-sorting of the immunoglobulin-binding protein BiP, an ER chaperone that has a retrieval signal from the early secretory pathway, which induced intense ER stress response and an increase in susceptibility to ER stress in HeLa cells. Furthermore, we show that the ER stress response accompanied the activation of p38 mitogen-activated protein (MAP) kinases and c-Jun amino-terminal kinases (JNKs) and that the expression of the mutant KDEL receptor suppressed the activation of p38 and JNK1 but not JNK2. The effect of the expression of the mutant KDEL receptor was consistent with the effect of a specific inhibitor for p38 MAP kinases, because the inhibitor sensitized HeLa cells to ER stress. We also found that activation of the KDEL receptor by the ligand induced the phosphorylation of p38 MAP kinases. These results indicate that the KDEL receptor participates in the ER stress response not only by its retrieval ability but also by modulating MAP kinase signaling, which may affect the outcomes of the mammalian ER stress response.

Carrier Proteins↗
PubMed2002

Influence of early repair of tetralogy of fallot without an outflow patch on late arrhythmias and sudden death: a 27-year follow-up study following a uniform surgical approach.

Pulmonary regurgitation and older age at the time of repair may have a large impact late after repair on subsequent mortality of patients with tetralogy of Fallot. We aimed to identify whether age at repair, and preservation of the pulmonary valve, had a favorable influence on morbidity and mortality. We also analyzed risk factors for late death subsequent to surgical repair. We identified 167 patients who, between 1965 and 1975, and at a mean age of 6 years, underwent total repair of tetralogy of Fallot by a single surgical team without use of an outflow patch. All patients were known to have survived for at least 30 days after repair, and late mortality was identified though the use of hospital records, interviews, and death certificates. The 29-year actuarial survival rate was 86%, with 24 late deaths. Of these deaths, seven occurred suddenly (4.2%). Morbidity was analyzed in 99 of the patients by means of a written questionnaire and telephone interview. It proved possible to analyze ventricular and valvar function in 50 of the patients. Survivors experienced no re-intervention, and 89% of them were in class I of the grading system of the New York Heart Association. We found evidence of 3 episodes of sustained ventricular tachycardia (3.0%), and two episodes of atrial tachycardia (2.0%). Of the 50 patients in whom serial examinations were available, 18 had pulmonary regurgitation of moderate degree or greater, and none had more than moderate tricuspid regurgitation, with a mean QRS duration of 148 ms and an ejection fraction for the left ventricle of 50%. Older age at repair (p = 0.03), and longer periods of cardiac arrest during repair (p = 0.02), were associated with late mortality. Although the mortality was similar to that observed in previous reports, our operative method might have a better effect in terms of late morbidity.

Age Factors↗
PubMed2002

Mortality and risk factors for late deaths in tetralogy of Fallot: the Japanese Nationwide Multicentric Survey.

OBJECTIVES: We have compared mortality and risk factors for late deaths in patients with tetralogy of Fallot undergoing surgical repair in 1972 and 1982 in a Japanese multicentric study, examining in particular the impact of time of repair. BACKGROUND: There is limited information on the effect that time of repair, and our constantly changing approach to it, has on late outcome in repaired tetralogy of Fallot. METHODS: We analysed the Japanese registry of deaths occurring after surgical repair of tetralogy of Fallot. We studied two postoperative 1-year cohorts of survivors of surgery performed in 12 centers. Of the patients, 122, aged 29+/-12 years, had undergone repair in 1972, their age at repair being 9.6 years. An additional 186 patients, aged 23+/-8.7 years, had been repaired in 1982 at the age of 7.7 years. RESULTS: Annual mortality, as judged per 100,000 population of patients with tetralogy of Fallot, declined from 0.387 in 1972 to 0.196 in 1982. Significant differences were deaths following surgery (27% vs. 13%, p < 0.001), patching of the subpulmonary outflow tract (48% vs. 89%, p < 0.001), and transjunctional patching (13% vs. 63%, p < 0.001). Late death was observed in 6 vs. 3 patients (9/308, 2.9%). The actuarial rate of survival calculated over 14 years was 97% vs. 98%. Reoperation was performed in 5 vs. 9 patients (14/308, 4.5%). Risk factors for late death were age at repair (p = 0.01), and history of reoperation (p < 0.001). Transjunctional patching (p = 0.01) proved to be associated with late mortality only in patients repaired in 1972. CONCLUSIONS: Late survival was excellent, with a low incidence of reoperations in both groups of patients. The era of repair has a big influence on total and operative mortality, but has only a small impact on late mortality. Ongoing analysis of follow-up will possibly reveal subsequent changes with time.

Adolescent↗
PubMed2002

Mortality from congenital cardiovascular malformations in Japan, 1968 through 1997.

Long-term mortality from congenital cardiovascular malformations (CCVM) remains unknown in most countries. Age- and sex-specific mortality rates from CCVM in Japan from 1968 through 1997 were determined from analyses, with official permission, of individual death records held by the Japanese Government. CCVM with chromosomal anomalies were not included. The number of deaths analyzed was 82,919. The mortality rate declined by 64% from 3.36 per 100,000 population in 1968 to 1.22 in 1997, largely because of a decrease in mortality among patients under 20 years of age. Infant mortality remained high until 1978, then sharply declined from 1979 to 1987 with the advent of 2-dimensional echocardiographic diagnosis and prostaglandin El therapy. The cumulative mortality rates in the first 20 years of life were expected to decline among cohort members born after 1978. In contrast, the mortality rates for subjects over 20 years of age increased during the 30-year study period. Mortality rates were higher for males than for females. The mortality rate among young patients with CCVM is expected to decline still further, suggesting that many if not most children with CCVM will survive to adulthood.

Adolescent↗