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Biomedical subjects

Satoshi Saito

Publications and source records attributed to Satoshi Saito.

At least 91 records · Page 5Linked to original sources
PubMed2004

Development of angiogenic cell and gene therapy by transplantation of umbilical cord blood with vascular endothelial growth factor gene.

Endothelial progenitor cells (EPCs) are present in the mononuclear cells (MNCs) of umbilical cord blood and peripheral blood. To establish the efficiency of angiogenic cell and gene therapies, we transfected the human vascular endothelial growth factor (hVEGF) gene into cord blood MNCs to enhance endothelialization. MNCs from cord blood and peripheral blood were isolated and transfected with pCR3 expressing hVEGF165 or GFP by the Hemagglutinating Virus of Japan (HVJ)-envelope and the cells were cultured in endothelium basal medium-2. The number of attached cells from cord blood was higher than that from peripheral blood. Attached cells expressed Flk-1, VE-cadherin, PECAM-1, CD34, and Tie-2. The increase in the number of attached cells was transient with the transfection of vascular endothelial growth factor (VEGF) gene early in the experimental period. Flt-1 mRNA was not expressed early in the culture period, but was expressed at 2 weeks after separation. VEGF gene transfer into MNCs at 12 days after separation, i.e., when Flt-1 mRNA was expressed continuously, increased the number of attached cells. We evaluated the effects of the transplantation of cord blood MNCs expressing the hVEGF gene on regional blood flow in an ischemic area in a rat model of chronic hindlimb ischemia. Blood flow was significantly improved in nude rats that received transplanted control MNCs. Transplantation of cord blood MNCs transfected with the hVEGF gene yielded greater improvements in blood flow. These results indicate that the hVEGF gene enhances endothelialization of EPCs, and that the transplantation of cord blood MNCs transfected with the VEGF gene may be feasible for the treatment of ischemic diseases as a type of angiogenic cell and gene therapy.

Animals↗
PubMed2004

Brugada-like electrocardiographic pattern unmasked by fever.

Brugada syndrome is characterized by right bundle branch block morphology and ST-segment elevation in the right precordial leads and a propensity to develop ventricular arrhythmias. Mutations in a cardiac sodium channel gene have been linked to this syndrome, and the ionic mechanisms responsible for the electrocardiographic phenotype are temperature-dependent. This case report describes a patient in whom a typical Brugada ECG pattern developed during fever and could be reproduced at normal body temperature by administration of pilsicainide.

Adult↗
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

Reproducible induction of atrioventricular nodal reentrant tachycardia with adenosine triphosphate.

A 29-year-old woman was referred for electrophysiological testing and radiofrequency ablation because of repeated episodes of palpitation of a 8-year duration. The 12-lead ECG during palpitations showed narrow QRS tachycardia at a rate of 160 beats/min. Dual AVN physiology according to electrophysiological criteria was not shown by single atrial extrastimulation and the tachycardia could not be induced. Slow/fast atrioventricular nodal reentrant tachycardia (AVNRT) was induced once by double atrial extrastimuli, but it was not reproducible. However, intravenous bolus injection of adenosine triphosphate (12.5 mg) during sinus rhythm led to reproducible initiation of slow/fast AVNRT.

Adenosine Triphosphate↗
PubMed2003

Plaque morphology at coronary sites with focal spasm in variant angina: study using intravascular ultrasound.

In the present study, the intravascular ultrasound (IVUS) morphologic appearance of coronary atherosclerotic plaque associated with focal spasm was prospectively studied in 45 patients with or without focal coronary spasm provoked by ergonovine or acetylcholine. The percent plaque area and plaque arc were determined from the IVUS images at the sites of spasm. Calcified lesion was defined as the presence of high-intensity echo with acoustic shadowing. Twenty-three patients had focal coronary spasm defined as angiographic narrowing >75% and IVUS demonstrated atherosclerotic plaque in these 23 sites. In the 22 patients without focal spasm, IVUS demonstrated 18 atherosclerotic lesions in 17 patients and the remaining 5 patients did not have significant lesions. There was no difference in the percent plaque area and plaque arc between plaque lesions with (47+/-10%, 298+/-71 degrees ) and without (39+/-15%, 249+/-83 degrees ) coronary spasm. Interestingly, calcified lesion was less frequently present at the sites with than at those without spasm (p<0.05). These results indicate that the presence of plaque without calcification is likely to be related to the occurrence of focal vasospasm, although the severity and distribution of the disease did not differ between each patient group.

Adult↗
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↗
PubMed2003

Noninvasive diagnosis of dual AV nodal physiology in patients with AV nodal reentrant tachycardia by adenosine triphosphate test.

Atrioventricular nodal reentrant tachycardia (AVNRT) is a relatively common paroxysmal supraventricular tachycardia. This study investigated whether adenosine-5'-triphosphate (ATP) injection during sinus rhythm might be useful in the noninvasive diagnosis of dual AV nodal pathways. The study group consisted of 9 patients with slow/fast AVNRT and 11 control patients without antegrade dual AV nodal physiology (DAVNP). ATP (2.5 to 30 mg, in 2.5-mg increments was injected during sinus rhythm until signs of DAVNP (> or = 50 msec increase or decrease in AH or PR interval in two consecutive beats) or > or = second-degree AV block was observed. DAVNP was diagnosed by ATP test in all 9 patients with slow/fast AVNRT. DAVNP was observed by ATP test in 3 of the 11 control patients. Thus, the test had a sensitivity of 100% and specificity of 73%. ATP test given during sinus rhythm is useful for identifying patients with dual AV nodal pathways who are prone to AVNRT.

Adenosine Triphosphate↗