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Satoshi Saito

Publications and source records attributed to Satoshi Saito.

At least 19 recordsLinked to original sources
PubMed2003

Chimeric DNA-RNA hammerhead ribozyme targeting PDGF A-chain mRNA specifically inhibits neointima formation in rat carotid artery after balloon injury.

OBJECTIVE: Restenosis of the coronary artery after percutaneous transluminal coronary angioplasty (PTCA) occurs in 30-50% of patients and remains a major clinical problem. We developed ribozyme that targets platelet-derived growth factor (PDGF) A-chain mRNA as a gene therapy for restenosis after PTCA. Thus, we examined the effects of a chimeric DNA-RNA ribozyme targeting PDGF A-chain mRNA on neointima formation in rat carotid artery after balloon injury and evaluated its specificity for PDGF A-chain mRNA by microarray analysis. METHODS: Rat carotid artery was injured with a 2F Fogarty catheter, and PDGF A-chain specific ribozyme was delivered to the injured artery with polyethylenimine. Two weeks after injury, the artery was removed, and the intima/media (I/M) ratio was evaluated. Six hours after injury, mRNA was extracted with oligo dT cellulose, and expression of PDGF A-chain mRNA was evaluated by reverse transcription-polymerase chain reaction. Expression of PDGF-AA protein was evaluated by Western blot analysis. Expression of 970 genes was evaluated by microarray (GeneChip, Affimetrix Inc). RESULTS: FITC-labeled ribozyme was taken up into the midlayer smooth muscle of the carotid artery until 24 h after balloon injury. Two and 5 microg of ribozyme significantly reduced neointima formation by 44 and 55% of control levels, respectively, in a dose-dependent manner. Ribozyme markedly inhibited expression of PDGF A-chain mRNA as well as production of PDGF-AA protein in injured vessels. Microarray analysis revealed that expression of 525 genes was increased after balloon injury. These genes included FLK-1, interleukin-1 receptor, retinoic acid receptor alpha2 isoform, heat shock protein, MAP kinase kinase, Fas antigen, G6Pase, PI-5-P-kinase, p38 MAP kinase, proliferating cell nuclear antigen, transforming growth factor-beta, extracellular signal-related kinase, and fibroblast growth factor receptor. With respect to expression of cytokine and growth factor mRNAs, the best ribozyme specifically inhibited expression of PDGF A-chain mRNA. CONCLUSIONS: Our chimeric DNA-RNA hammerhead ribozyme targeting PDGF A-chain mRNA inhibited neointima formation in rat carotid artery after balloon injury with specific inhibition of expression of PDGF A-chain mRNA, suggesting that this ribozyme may be useful for therapy of restenosis of coronary artery after PTCA.

Animals↗
PubMed2003

Hydrogen peroxide-dependent declines in Bcl-2 induces apoptosis in hypoxic liver.

BACKGROUND: Low-flow hypoxia induces xanthine oxidase-dependent hydrogen peroxide production by hepatocytes in the midzone of blood-perfused rat livers and apoptosis in sinusoidal endothelial cells (SECs). As Bcl-2 is a potent inhibitor of apoptotic cell death and is localized mainly in the inner mitochondrial membrane and crista, the purpose of this study was to determine whether cell-specific changes in mitochondrial Bcl-2 levels could account for the hypoxia-induced apoptosis in SECs. MATERIALS AND METHODS: A low-flow hypoxia model was generated in isolated rat livers by reducing perfusate inflow pressure from 10 to 2.5 cmH2O for 2 h. Apoptosis was then evaluated using the TdT-mediated dUTP-digoxigenin nick end-labeling (TUNEL) method. Mitochondrial Bcl-2 protein levels were determined in hepatocytes and SECs using cryosectioning immunogold labeling electron microscopy.Results. TUNEL-positive nonparenchymal cells, identified as SECs, were observed predominantly in the midzone of low-flow hypoxic rat livers, whereas few parenchymal cells were stained. Mitochondrial Bcl-2 levels were higher in SECs than in hepatocytes under control conditions, but they declined significantly during hypoxia, though no morphological signs of apoptosis were apparent. In hepatocytes, by contrast, Bcl-2 levels were unaffected by hypoxia. Pretreatment with a specific xanthine oxidase inhibitor, sodium (-)-8-(3-methoxy-4-phenylsulfinylphenyl) pyrazolo [1,5-a]-1,3,5-triazine-4-olate monohydrate, which blocks production of hydrogen peroxide, also blocked both the hypoxia-induced apoptosis and the decline in mitochondrial Bcl-2 in SECs. CONCLUSION: Hydrogen peroxide-dependent declines in Bcl-2 induce apoptosis in SECs in the hypoxic rat liver.

Animals↗
PubMed2003

Altered proliferative responses of dermal fibroblasts to TGF-beta1 may contribute to chronic venous stasis ulcer.

PURPOSE: Venous ulcer fibroblasts demonstrate decreased proliferative responses to growth factor stimulation, suggesting cellular senescence. However, the role of chronic venous insufficiency (CVI) disease progression and extracellular matrix (ECM) proteins in agonist-induced cellular proliferation is ill-defined. We hypothesize that CVI-induced fibroblast proliferative resistance to growth factors worsens with disease progression and is regulated by the composition of ECM. METHODS: Fibroblast explants were isolated from biopsy specimens from two patients without CVI and 16 patients with CVI of the lower calf (LC) and lower thigh (LT) and stratified according to CEAP disease severity: non-CVI (NC; n = 2), class 2-3 (n = 5), class 4 (n = 5), class 5 (n = 3), and class 6 (n = 3). Proliferation experiments were standardized with a neonatal foreskin fibroblast cell line (HS68). A 10-day course and dose response experiment with 0, 0.5, 1.0, 2.5, 5, 10, and 20 ng/mL of transforming growth factor-beta(1) (TGF-beta(1)) demonstrated maximal cell proliferation at 5 ng/mL of TGF-beta(1) on day 4. Under these conditions, CVI dermal fibroblasts were challenged with and without TGF-beta(1) and evaluated for proliferative responses on plates coated with polystyrene, collagen, and fibronectin. RESULTS: No differences in unstimulated proliferation were observed in LT and LC fibroblasts from patients with class 2-3 disease and LT fibroblasts from patients with class 4 and 5 disease, compared with NC and HS68 cells. LC fibroblasts from patients with class 4 disease (P <.05) and class 5 disease (P <.001), and LC (P <.001), and LT fibroblasts from patients with class 6 disease (P <.001) proliferated to a lesser degree than did NC and HS68 cells. The diminished proliferation observed in class 4 LC cells was reversible with TGF-beta(1) stimulation (P <.004); however, class 5 and class 6 LC and LT fibroblasts did not respond to stimulation with TGF-beta(1). Collagen increased proliferation of HS68 cells with (P <.05) and without (P <.01) TGF-beta(1), compared with cells grown on polystyrene, but did not increase proliferative responses in NC or CVI fibroblasts with and without TGF-beta(1). Similarly, fibronectin increased proliferation of HS68 cells (P <.05) compared with cells grown on polystyrene, but did not alter proliferation in CVI fibroblasts. Fibronectin did seem to inhibit TGF-beta(1)-induced proliferation observed in class 4 LC cells. CONCLUSION: These data indicate that clinical disease progression correlates with cellular dysfunction. Fibroblasts from patients with class 2-3 disease retain their unstimulated and agonist- induced proliferative capacity, compared with NC and HS68 cells. The onset of inflammatory skin changes (class 4 and class 5 disease) diminishes agonist-induced proliferation, and ulcer formation (class 6 disease) severely inhibits it. In addition, the composition of ECM does not affect TGF-beta(1)-induced proliferation of fibroblasts in CVI.

Cell Movement↗
PubMed2003

Effect of 60 minutes of rapid atrial pacing on atrial action potential duration in the in-situ canine heart.

Right atrial monophasic action potentials were recorded before and after 60 minutes of rapid atrial pacing (pacing cycle length (CL); 127 +/- 10 ms) in 12 closed-chest dogs. The right atrial (RA) monophasic action potential (MAP) duration at 90% repolarization (RAMAPD) was measured at CLs of 400 ms and 250 ms. CL-dependent changes in RAMAPD (CL 400 ms - 250 ms) before and after rapid atrial pacing were 24 +/- 1 ms and 16 +/- 5 ms, respectively (p < 0.02). RAMAP was recorded at each atrial pacing CL starting at 240 ms decreasing by 10-ms increments. RAMAPD alternans was observed in 10 of 12 dogs at a CL of 163 +/- 17 ms before and in 10 of 12 dogs at s CL of 198 +/- 29 ms (p < 0.01) after rapid atrial pacing. Sustained atrial fibrillation (AF) (>5 minutes) was induced in 1 of 12 dogs at a pacing CL of 130 ms before rapid atrial pacing and in 4 of 12 dogs at a pacing CL of 135 +/- 17 ms after rapid atrial pacing. Onset of AF was always preceded by the RAMAPD alternans. Sixty minutes of rapid atrial pacing leads to diminution of rate adaptation of atrial action potential duration (APD) and appearance of APD alternans of greater magnitude at longer CL, both of which may contribute to the initiation and perpetuation of AF during its early phase.

Action Potentials↗
PubMed2003

Intravenous administration of class I antiarrhythmic drug induced T wave alternans in an asymptomatic Brugada syndrome patient.

A 53-year-old man with an abnormal ECG was referred to the Nihon University School of Medicine. The 12-lead ECG showed right bundle branch block and saddleback-type ST elevation in leads V1-V3 (Brugada-type ECG). Signal-averaged ECG showed positive late potentials. Double ventricular extrastimuli (S1: 500 ms, S2: 250 ms, S3: 210 ms) induced VF. Amiodarone (200 mg/day) was administered for 6 months and programmed ventricular stimulation was repeated. VF was induced again by double ventricular stimuli (S1: 600 ms, S2: 240 ms, S3: 170 ms). Intravenous administration of class Ic antiarrhythmic drug, pilsicainide (1 mg/kg), augmented ST-T elevation in leads V1-V3, and visible ST-T alternans that was enhanced by atrial pacing was observed in leads V2 and V3. Visible ST-T wave alternans disappeared in 15 minutes. However, microvolt T wave alternans was present during atrial pacing at a rate of 70/min without visible ST-T alternans.

Amiodarone↗
PubMed2003

Serologic analysis of three cases of neonatal alloimmune thrombocytopenia associated with HLA antibodies.

BACKGROUND: Neonatal alloimmune thrombocytopenia (NAIT) is caused when maternal alloantibodies react with paternally inherited antigens present on the fetal PLTs, a reaction mainly due to antibodies against human PLT antigens. Cases in which NAIT has been caused by HLA antibodies are relatively rare. In this study, three cases of NAIT associated with HLA antibodies that occurred in a 1-year period are reported. STUDY DESIGN AND METHODS: The presence of HLA antibodies in these three NAIT case studies was elucidated by examining reactions of the neonatal and maternal sera with lymphocytes, PLTs, and beads from an HLA antibody screening test (FlowPRA, One Lambda Inc.). Absorption and elution tests with paternal cells were also conducted. In addition, the influence of titer and specificity of HLA antibodies on NAIT was analyzed in light of 24 other documented cases in Japan. RESULTS: In the three case studies presented herein, antibodies against human PLT antigens were found in neither the maternal nor neonatal sera, while specific HLA antibodies were identified in both sera. Absorption of maternal serum with paternal PLTs eliminated the reactivity against paternal PLTs and lymphocytes. CONCLUSION: Transplacental passage of maternal HLA antibodies was observed in the three neonates cited in the present study.

Adsorption↗
PubMed2003

Effects of antisense peptide nucleic acid to platelet-derived growth factor A-chain on growth of vascular smooth muscle cells.

To investigate antisense peptide nucleic acid (PNA) as a gene therapy for the arterial proliferative diseases, the authors designed and examined the effects of an antisense PNA targeting platelet-derived growth factor (PDGF) A-chain on expression of PDGF A-chain and growth of vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats. A 15-mer antisense PNA complementary to the initiation codon of rat and human PDGF A-chain mRNA was synthesized and purified by high-performance liquid chromatography. Gel-shift assay and biomolecular interaction analysis (BIAcore) revealed that the antisense PNA bound weakly to the target RNA, whereas it bound strongly to the target DNA. Fluorescein-isothiocyanate-labeled antisense PNA to PDGF A-chain was taken up slowly and maintained in VSMCs for a prolonged period of time. Antisense PNA inhibited expression of PDGF A-chain mRNA and protein as well as DNA synthesis in VSMCs in a dose-independent manner. Inhibition of DNA synthesis by the antisense PNA was greater than that by the antisense DNA at a low concentration (0.5 micromol/L). These results suggest that antisense PNA to PDGF A-chain will be used as a gene therapy for vascular proliferative diseases such as hypertensive vascular diseases, restenosis of coronary arteries after angioplasty, and atherosclerosis.

Animals↗
PubMed2003

Methylprednisolone inhibits low-flow hypoxia-induced mitochondrial dysfunction in isolated perfused rat liver.

OBJECTIVE: To investigate the mechanism by which methylprednisolone protects the liver from hypoxia-induced injury. DESIGN: Prospective control study using the isolated rat liver. SETTING: Animal research facility. SUBJECTS: Male, fasted, pathogen-free Sprague-Dawley rats. INTERVENTIONS: Low-flow hypoxia was produced by reducing afferent perfusate pressure from 10 to 2.5 cm H(2)O; isolated livers were portally perfused for 2 hrs. MEASUREMENTS AND MAIN RESULTS: We measured mitochondrial membrane potential and hydrogen peroxide production by imaging rhodamine 123 and 2'-7'-dichlorofluorescein fluorescence, respectively. Leakage of mitochondrial enzymes was also monitored by assaying mitochondrial aspartate aminotransferase activity in the outflow perfusate, and the radical-scavenging effect of methylprednisolone was assessed by measuring luminol-dependent hydrogen peroxide chemiluminescence. Apoptosis in liver cells was determined by using terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick-end labeling. Rhodamine 123 fluorescence was significantly diminished in the hypoxic liver, especially in the region of the terminal hepatic venules, which is indicative of membrane depolarization in the mitochondria in those areas. Hypoxia-induced mitochondrial dysfunction was indicated by leakage of aspartate aminotransferase into the outflow perfusate, and increased 2'-7'-dichlorofluorescein fluorescence indicated increased hydrogen peroxide levels, particularly in the midzone. Pretreatment with 30, 10, or 3 mg/kg of methylprednisolone inhibited the hypoxia-induced mitochondrial membrane depolarization and enzyme leakage, although hydrogen peroxide levels and apoptosis in sinusoidal endothelial cells were unaffected. CONCLUSIONS: Methylprednisolone does not protect the liver from hypoxia-induced injury by suppressing hydrogen peroxide production. Instead, the beneficial effect of methylprednisolone seems to be related to its ability to protect against mitochondrial membrane depolarization under hypoxic conditions.

Animals↗
PubMed2003

Combined atriofascicular and fasciculoventricular connections.

A 32-year-old man with a 20-year history of palpitation showed a short PQ interval and delta wave on 12-lead ECG. An electrophysiological study showed that the atrio-His (AH) and His-ventricular intervals were not influenced by rapid right atrial pacing or by bolus injection of adenosine triphosphate (ATP). The AH interval was shortened by coronary sinus ostium (CSos) pacing. Ventricular stimulus to the atrial activation interval was not affected by ATP but shortened by para-Hisian pacing and orthodromic His bundle activation was followed by atrial activation. The tricuspid - inferior vena cava isthmus was blocked by CSos pacing, but Ith conduction existed during low lateral right atrial pacing.

Adenosine Triphosphate↗
PubMed2002

Circulatory support for long-term treatment of heart failure: experience with an intraventricular continuous flow pump.

BACKGROUND: A lifetime mechanical solution for advanced heart failure must be reliable, with a low risk of life-threatening complications. After extensive laboratory testing, we began clinical trials with an axial flow pump for long-term treatment of New York Heart Association class IV, transplant-ineligible patients. METHODS AND RESULTS: The Jarvik 2000 is a continuous flow device that is implanted in the apex of the left ventricle with offloading to the descending thoracic aorta. Skull-based percutaneous power delivery was derived from cochlear implant technology. We used this system in 4 patients with end-stage dilated cardiomyopathy. Exercise capacity, quality of life, device parameters, and native heart function were monitored serially. One patient died from right heart failure at 3 months. The other patients were discharged from hospital between 3 and 8 weeks postoperatively and are currently New York Heart Association I or II. Follow-up lasted between 9 and 20 months. There has been no device failure or hemolysis. Native heart function and quality of life were markedly improved. CONCLUSIONS: The Jarvik 2000 is a true assist (rather than replacement) device that functions synergistically with the native left ventricle and provides excellent quality of life. Adverse events are infrequent. This blood pump may provide a mechanical solution for end-stage heart failure in the community.

Adrenergic beta-Antagonists↗
PubMed2002

Acute type A dissection: conservative methods provide consistently low mortality.

BACKGROUND: A wide spectrum of operative techniques are applied in acute type A dissection. Most convey hospital mortality between 10% and 20%. In this high-risk setting, we believe that a conservative approach to the aortic root and the complete resection of the primary tear are important. We reviewed the results of this policy from our aortic surgery database. METHODS: Between 1988 and December 2000, 95 acute type A dissection patients were operated on by one surgeon. They included 70 men and 25 women aged 37 to 81 years (mean 65 years). Six had Marfan syndrome. Aortic root restoration or replacement was performed during cooling, open arch repair during circulatory arrest, and hemostasis while rewarming. Eighty-seven patients had ascending aortic replacement with glue resuspension of the valve. Two others had had aortic valve replacement previously. Aortic root and partial arch replacement was performed in 6 Marfan patients. Eighteen patients had hemiarch replacement, and 6 had total arch replacement to excise the tear. RESULTS: Five patients died in hospital (5.3% 30-day mortality) and another after early readmission for mediastinal infection (6.3% total mortality). There were no deaths from bleeding. Two patients required aortic valve replacement for aortic regurgitation 2.5 and 3.0 years postoperatively. Two others required total arch replacement and thromboexclusion procedures, respectively. CONCLUSIONS: Our policy of primary tear excision and preservation of the native aortic valve has resulted in low overall mortality. We still prefer to replace the aortic root in dissected Marfan patients. In this high-risk condition, hospital survival is of paramount importance. A conservative "pathology-oriented" approach helps to achieve this aim.

Adult↗
PubMed2002

Implant technique for the Jarvik 2000 Heart.

The Jarvik 2000 Heart is a silent compact axial flow impeller pump which is now undergoing clinical trials for both bridge to transplantation and permanent mechanical circulatory support. The pump is implanted into the apex of the failing left ventricle by left thoracotomy. A vascular graft offloads to the descending thoracic aorta so that only the left pleural cavity is opened. Power supply is through an abdominal drive line or postauricular titanium pedestal according to the treatment strategy.

Heart, Artificial↗
PubMed2002

End-organ function during chronic nonpulsatile circulation.

BACKGROUND: Evolving blood pump technology has produced user-friendly continuous flow left ventricular assist devices, but uncertainty exists about the safety of chronic nonpulsatile circulation. We established consistently nonpulsatile blood flow in a sheep model using the Terumo magnetically suspended centrifugal pump. We then compared end-organ function between pulseless and control animals. METHODS: Fifteen healthy sheep (65 to 85 kg) were allocated to either left ventricular assist device (n = 9) or control (n = 6) groups. We implanted the device through a left thoracotomy and determined the flow rate at which pulse pressure was absent. The flow rate was then adjusted to exceed that rate (4.2 +/- 1.5 L/min), and all variables of pump function were continuously monitored by computer. Blood tests were taken serially for hepatic and renal function and plasma renin levels. The sheep were sacrificed electively at 30 (n = 3), 90 (n = 4), 180 (n = 1), and 340 (n = 1) days. Detailed histologic examination was made of the brain, liver, kidney, myocardium, and major arteries. RESULTS: All animals remained in good condition until sacrifice. All measures of end-organ function remained within normal limits for both groups. There were no histologic differences between the organs of pulsatile and nonpulsatile animals. Although there was no significant difference in mean blood pressure, plasma renin levels were substantially elevated in pulseless animals (1.4 +/- 0.3 pg/mL versus 2.9 +/- 0.3 pg/mL; p < 0.05). We also identified thinning of the medial layer of the ascending aorta in nonpulsatile sheep (1.8 +/- 0.4 mm in left ventricular assist device animals versus 2.6 +/- 0.6 mm in control sheep; p < 0.05). CONCLUSIONS: Chronic nonpulsatile circulation was well tolerated, and we found neither functional nor histologic changes in major end organs. The renin-angiotensin system was upregulated, but this did not provide a significant rise in blood pressure. The changes in the aortic wall merit further investigation. As a result of these findings, we consider that nonpulsatile devices can be used safely for long-term circulatory support.

Animals↗