Biomedical subjects

Shigeru Oshima

Publications and source records attributed to Shigeru Oshima.

At least 37 records · Page 2Linked to original sources

PubMed2005

Three-dimensional visualization of the coronary venous system using multidetector row computed tomography.

BACKGROUND: This study was undertaken to investigate the applicability and image quality of contrast-enhanced visualization of the coronary venous system (CVS) by multidetector row computed tomography (MDCT). METHODS AND RESULTS: A total of 70 patients underwent MDCT and for each patient, 6 data sets were created throughout the cardiac cycle. The number and location of coronary veins were evaluated in 3-dimensional images using the 6 data sets. The quality of all images reconstructed from the 6 data sets was too poor to evaluate the CVS in 6 patients (9%). In the remaining 64 patients (91%), the diameter of the CVS was usually greater in the images reconstructed from data acquired during systole than in those reconstructed from data acquired during diastole. However, artifacts were observed more often in images from systole than from diastole. The coronary sinus and middle cardiac vein were visible in all 64 patients. The left marginal and posterior veins also were identified in 54 (84%) and 60 patients (94%), respectively. CONCLUSIONS: MDCT can be used as a non-invasive modality for evaluating the CVS anatomy in most patients.

Adult↗

PubMed2005

Tissue Doppler imaging and strain Doppler imaging as modalities for predicting clinical improvement in patients receiving biventricular pacing.

BACKGROUND: The purpose of this study was to determine the utility and efficacy of tissue Doppler imaging (TDI) and strain Doppler imaging (SDI) for evaluating ventricular synchrony and function, and for predicting the long-term clinical improvement in patients undergoing biventricular pacing (BVP). METHODS AND RESULTS: TDI and SDI were performed before and <1 month after initiating BVP in 17 patients with advanced heart failure. An intraventricular conduction delay between the left ventricular (LV) septal and lateral walls was measured by TDI. The average LV strain (LV-strain) was calculated from data obtained at the center of 6 regions of the LV (base and mid-point between the basal and apical portions, and the mid-point between these 2 points on the septal and lateral walls). During a 23+/-7 month follow-up period, 12 patients improved clinically and did not require re-hospitalization for heart failure (responder group), but the remaining 5 did not improve (nonresponder group). Before BVP, the intraventricular conduction delay was greater in the responder group than in the nonresponder group (p<0.01), but after BVP, it did not differ between the 2 groups. LV-strain improved after BVP in the responder group but not in the nonresponder group (p<0.05). CONCLUSION: A high intraventricular conduction delay before BVP and decreased strain shortly after BVP may predict long-term clinical improvement in patients undergoing this treatment.

Aged↗

PubMed2005

Left atrial appendage outflow velocity is superior to conventional criteria for predicting of maintenance of sinus rhythm after simple cryoablation of pulmonary vein orifices.

BACKGROUND: We sought to identify factors favoring long-term restoration of sinus rhythm (SR) in patients with atrial fibrillation (AF) who underwent a simple cryoablation of pulmonary vein orifices (PV-cryo) as part of their cardiac surgery. METHODS AND RESULTS: Of 101 patients with AF undergoing PV-cryo, the 71 in SR at discharge were grouped according to whether they maintained or lost SR (group SR, n = 61, and group AF, n = 10) after an average of 2.3 years. Atrial fibrillation present at discharge (n = 30) persisted during follow up. Comparisons were made to identify preoperative predictive factors, including transthoracic and transesophageal echocardiographic parameters. Of patients discharged from the hospital with SR, 92% (46 of 50) of those with AF duration of 3 years or less were in group SR, as were 92% (23 of 25) of those with left atrial dimension of 50 mm or less, and 93% (37 of 40) of those with average peak left atrial appendage outflow velocities (LAA-V) of at least 30 cm/s. Of 25 patients in group SR who had no paroxysmal AF and did not require antiarrhythmic drugs, all had LAA-V over 20 cm/s. Patients in group AF all had LAA-V under 40 cm/s. CONCLUSIONS: Left atrial appendage outflow velocities was the best predictor of whether SR was maintained long-term after PV-cryo.

Aged↗

PubMed2005

Exercise tolerance, exercise hyperpnea and central chemosensitivity to carbon dioxide in sleep apnea syndrome in heart failure patients.

BACKGROUND: Sleep apnea syndrome (SAS) and exercise hyperpnea are common in patients with chronic heart failure (CHF), and although it is not known whether they are both regulated by the same mechanisms, the hypothesis of the present study was that they are related to augmented central chemosensitivity. METHODS AND RESULTS: The oxygen desaturation index (ODI) was evaluated in 29 patients and those with ODI > 5 times/h underwent polysomnography. Patients with an apnea-hypopnea index (AHI) > 15 /h without evidence of obstructive apnea were defined as central SAS (CSAS). Cardiopulmonary exercise testing was performed to determine peak oxygen uptake and the VE-VCO2 slope. A hypercapnic gas mixture (7% CO2/93% O2) was used to activate the central chemoreflex. Nine patients had central SAS (CHF-CSAS) and 20 did not have apnea (CHF-nonSAS). Patients with CHF-CSAS had a lower peak oxygen uptake than the CHF-nonSAS group (13.0+/-2.4 vs 16.9+/-4.3 ml x kg(-1) x min(-1), p < 0.05). There was a significant correlation between central chemosensitivity and the AHI (r = 0.63, p < 0.05), between central chemosensitivity and the VE - VCO2 slope (r = 0.50, p < 0.01), whereas the VE-VCO2 slope showed an insignificant tendency to correlate with AHI (r = 0.44, p = 0.07). Conclusion CHF-CSAS is associated with impaired exercise tolerance and elevated central chemosensitivity is the responsible mechanism for CSAS and exercise hyperpnea.

Aged↗

PubMed2005

Comparison of the rheologic parameters in left internal thoracic artery grafts with those in saphenous vein grafts.

BACKGROUND: Left internal thoracic artery (LITA) grafts have superior patency to saphenous vein grafts (SVG). Because shear stress augments the release of nitric oxide throughout the LITA endothelium, shear stress and shear rate in coronary artery bypass grafts (CABG) may play an important role in the higher patency, so the aim of the present study was to evaluate and compare the rheologic parameters in CABG using LITA and SVG. METHODS AND RESULTS: Rheologic examinations were done in 197 patients using a vacuum-suction glass tube viscometer after CABG surgery was completed. Shear stress and shear rate were calculated from the geometry of the graft, blood flow in the graft and blood viscosity. Of 197 patients, 177 underwent LITA grafting to the left anterior descending artery (LAD) and 160 had SVG anastomosis to coronary arteries. Mean wall shear stress in the LITA grafts to the LAD (13.8+/-1.0 dyne/cm2) was nearly 4-6-fold larger than that in the SVG grafts. Mean shear rate (559.1+/-57.0 s(-1)) of LITA-LAD grafts was approximately 2-3-fold higher than that of SVG. CONCLUSION: These results suggest that high wall shear stress and shear rate play an important role in the higher patency rate of LITA grafts.

Aorta, Thoracic↗

PubMed2005

Idiopathic premature ventricular contractions arising from the pulmonary artery: importance of mapping in the pulmonary artery in left bundle branch block-shaped ventricular arrhythmias.

A patient underwent radiofrequency (RF) catheter ablation of symptomatic idiopathic ventricular contractions (PVCs). RF energy applications at 2 sites in the right ventricular outflow tract (RVOT), where both the earliest ventricular activation and near-perfect pace mapping were obtained, did not abolish the PVC but resulted in changes in the QRS morphology of the PVC. Complete elimination of the PVC was achieved with RF energy application at a site within the pulmonary artery 13 mm above the pulmonary valve, which was greater than 20 mm away from the failed ablation sites within the RVOT.

Adult↗

PubMed2005

Acute myocardial infarction and ischemia in the left anterior descending artery territory in a patient with single coronary artery.

This report describes a 77-year-old woman with a single coronary artery who suffered an acute anterior wall myocardial infarction. The single coronary artery arose from the right coronary artery through the transverse trunk, and there were no other cardiovascular anomalies. Coronary angiography did not reveal significant coronary artery stenosis in the left anterior descending artery. The patient was treated medically in the acute phase. She developed typical angina and evidence of myocardial ischemia, and underwent successful coronary artery bypass grafting in the chronic phase with anterior chest pain.

Aged↗

PubMed2005

Effectiveness of distal protection with the GuardWire Plus during primary angioplasty for acute myocardial infarction.

OBJECTIVES: To evaluate the effectiveness of distal protection with the GuardWire Plus during primary angioplasty in patients with acute myocardial infarction. METHODS: Thirty-eight consecutive patients undergoing stent implantation with distal protection using the GuardWire Plus (DP-group) were compared with a matched control group undergoing conventional stent implantation after balloon angioplasty without distal protection (NDP-group). Microvascular circulation after revascularization was assessed by Thrombolysis in Myocardial Infarction (TIMI) flow grade, myocardial blush grade (MBG), serum creatine kinase peak release, and ST resolution. Left ventricular ejection fraction was measured by echocardiography at discharge. Follow-up quantitative coronary angiography and left ventriculography were performed 6 months after percutaneous coronary intervention. Quantitative coronary angiography data, restenosis rate, target lesion revascularization rate and follow-up left ventricular ejection fraction were also compared between the two groups. RESULTS: No significant differences were observed in baseline clinical and angiographic characteristics between the two groups. The TIMI flow grade 3 (DP-group 81.6% vs NDP-group 57.9%)and MBG 3 (57.9% vs 30.6%)were significantly greater in the DP-group respectively (p < 0.05). Post procedural ST-segment resolution > or = 50% was found in a significantly higher percentage of patients in the DP-group (68.4% vs 42.1%, p < 0.05). Left ventricular ejection fraction at discharge was significantly greater in the DP-group (55.5 +/- 8.5% vs 45.7 +/- 11.1%, p < 0.05). However, 6 months after the percutaneous coronary intervention, no significant difference was observed between the two groups. Restenosis rate and target lesion revascularization rate were similar in the two groups. CONCLUSIONS: Distal protection with the GuardWire Plus improved the microvascular circulation as assessed by TIMI flow grade, MBG, and ST resolution. Furthermore, left ventricular ejection fraction at discharge was improved.

Aged↗

PubMed2004

IL-7 exacerbates chronic colitis with expansion of memory IL-7Rhigh CD4+ mucosal T cells in mice.

We have previously demonstrated that mucosal CD4(+) T cells expressing high levels of IL-7 receptor (IL-7R(high)) are pathogenic cells responsible for chronic colitis. Here we investigate whether IL-7 is directly involved in the expansion of IL-7R(high) memory CD4(+) mucosal T cells and the exacerbation of colitis. We first showed that CD4(+) lamina propria lymphocytes (LPLs) from wild-type, T cell receptor-alpha-deficient (TCR-alpha(-/-)), and recombinase-activating gene (RAG)-2(-/-)-transferred mice with or without colitis showed phenotypes of memory cells, but only CD4(+) LPLs from colitic mice showed IL-7R(high). In vitro stimulation by IL-7, but not by IL-15 and thymic stromal lymphopoietin, enhanced significant proliferative responses and survival of colitic CD4(+), but not normal CD4(+) LPLs. Importantly, in vivo administration of IL-7 mice accelerated the expansion of IL-7R(high) memory CD4(+) LPLs and thereby exacerbated chronic colitis in RAG-2(-/-) mice transferred with CD4(+) LPLs from colitic TCR-alpha(-/-) mice. Conversely, the administration of anti-IL-7R monoclonal antibody significantly inhibited the development of TCR-alpha(-/-) colitis with decreased expansion of CD4(+) LPLs. Collectively, the present data indicate that IL-7 is essential for the expansion of pathogenic memory CD4(+) T cells under pathological conditions. Therefore, therapeutic approaches targeting the IL-7R pathway may be feasible in the treatment of human inflammatory bowel disease.

Animals↗

PubMed2004

CD4+CD25bright T cells in human intestinal lamina propria as regulatory cells.

It is well known that immune responses in the intestine remain in a state of controlled inflammation, suggesting that not only active suppression by regulatory T cells plays an important role in the normal intestinal homeostasis, but also its dysregulation leads to the development of inflammatory bowel disease. In this study, we demonstrate that the CD4(+)CD25(bright) T cells reside in the human intestinal lamina propria (LP) and functionally retain regulatory activities. All human LP CD4(+) T cells regardless of CD25 expression constitutively expressed CTLA-4, glucocorticoid-induced TNFR family-related protein, and Foxp3 and proliferate poorly. Although LP CD4(+)CD25(-) T cells showed an activated and anergic/memory phenotype, they did not retain regulatory activity. In LP CD4(+)CD25(+) T cells, however, cells expressing CD25 at high levels (CD4(+)CD25(bright)) suppressed the proliferation and various cytokine productions of CD4(+)CD25(-) T cells. LP CD4(+)CD25(bright) T cells by themselves produced fewer amounts of IL-2, IFN-gamma, and IL-10. Interestingly, LP CD4(+)CD25(bright) T cells with regulatory T activity were significantly increased in patients with active inflammatory bowel disease. These results suggest that CD4(+)CD25(bright) T cells found in the normal and inflamed intestinal mucosa selectively inhibit the host immune response and therefore may contribute to the intestinal immune homeostasis.

Antigens, CD↗

PubMed2004

Usefulness of quantitative gated single-photon emission computed tomography to evaluate ventricular synchrony in patients receiving biventricular pacing.

Quantitative gated single-photon emission computed tomography was performed in 10 patients before and shortly after (<1 month) receiving biventricular pacing (BVP). They were divided into 2 groups (responder and nonresponder groups) on the basis of clinical status and echocardiographic parameters 18 +/- 6 months later. In the responder group, left ventricular synchrony shortly after BVP improved significantly compared with that before BVP (p <0.05), but there was no change in the nonresponder group.

Aged↗

PubMed2004

Diagnostic use of serum deoxyribonuclease I activity as a novel early-phase marker in acute myocardial infarction.

BACKGROUND: The delayed release of serum cardiac markers such as creatine kinase isoenzyme MB and equivocal early electrocardiographic changes have hampered a diagnosis of acute myocardial infarction (AMI) in the early phase after its onset. Therefore, a reliable serum biochemical marker for the diagnosis of AMI in the very early phase is desirable. METHODS AND RESULTS: Serum samples were collected from the patients with AMI, unstable angina pectoris, stable angina pectoris, and other diseases. Levels of serum deoxyribonuclease I (DNase I) activity in the patients were determined. An abrupt elevation of serum DNase I activity was observed within approximately 3 hours of the onset of symptoms in patients with AMI, with significantly higher activity levels (21.7+/-5.10 U/L) in this group compared with the other groups with unstable angina pectoris (10.4+/-4.41 U/L), angina pectoris (10.8+/-3.70 U/L), and other diseases (9.22+/-4.16 U/L). Levels of the DNase I activity in serum then exhibited a marked time-dependent decline within 12 hours and had returned to basal levels within 24 hours. CONCLUSIONS: We suggest that serum DNase I activity could be used as a new diagnostic marker for the early detection of AMI.

Adult↗

PubMed2004

Usefulness of insulin resistance measured by homeostasis model assessment in predicting restenosis after coronary stent placement in nondiabetic patients.

The homeostasis model assessment enabled us to evaluate insulin resistance easily and accurately in the clinical setting. The restenosis rate of coronary stenting was significantly higher among patients with high values for the homeostasis model assessment. Our findings suggest that insulin resistance measured by the homeostasis model assessment predicts restenosis after coronary stent placement in nondiabetic patients.

Aged↗

PubMed2004

Evaluation of myocardial viability following acute myocardial infarction using 201Tl SPECT after thallium-glucose-insulin infusion--comparison with 18F-FDG positron emission tomography.

OBJECTIVE AND METHODS: The aim of this study was to evaluate myocardial viability in patients after acute myocardial infarction (AMI). We compared 201Tl SPECT after 201Tl with GIK (10% glucose 250 ml, insulin 5 U and KCl 10 mEq) infusion (GIK-201Tl) with resting 201Tl and 99mTc-pyrophosphate (PYP) dual SPECT, positron emission computed tomography (PET) using 18F-fluorodeoxyglucose (18F-FDG) in 21 patients with their first AMI, who all underwent successful reperfusion. GIK-201Tl SPECT, 201Tl and 99mTc-PYP dual SPECT were done within 10 days after admission and 18F-FDG-PET was performed at 3 weeks. GIK-201Tl SPECT was obtained after 30 min of GIK-201Tl infusion. 18F-FDG (370 MBq) was injected intravenously after oral glucose (1 g/ kg) loading, and then PET was obtained. PET and SPECT images were divided into 20 segments. Regional tracer uptake was scored using a 4-point scoring system (3 = normal to 0 = defect), and summed to a regional uptake score (RUS). Regional area means the infarcted area in which 99mTc-PYP accumulated. The number of decreased uptake segments (ES) was then determined. The infarcted area was defined as the area of 99mTc-PYP uptake. RESULTS: The ESs for the GIK-201Tl and 18F-FDG-PET images were significantly lower than the number of 99mTc-PYP uptake segments. The RUS for GIK-201Tl was higher than that for resting-201Tl imaging and similar to those for 18F-FDG-PET. CONCLUSIONS: In the detection of myocardial viability following AMI, GIK-201Tl imaging is useful with findings similar to those of 18F-FDG-PET.

Aged↗

PubMed2004

Significance of two potentials for predicting successful catheter ablation from the left sinus of Valsalva for left ventricular epicardial tachycardia.

The aim of this study was to identify the characteristics of electrograms that may be helpful in predicting successful ablation of idiopathic ventricular tachycardia from the aortic sinus of Valsalva. Data were obtained from 23 patients with symptomatic ventricular tachycardia or premature ventricular contractions (LV-VT) who underwent RF catheter ablation from the left sinus of Valsalva. Electrograms before and after application of RF energy during sinus rhythm and during LV-VT were analyzed. Complete elimination of LV-VT was finally achieved in 21 (91%) patients. The incidence of presystolic potentials preceding the QRS complex of LV-VT (P1 potential) was 90% for the 21 successful ablation sites, which did not differ from the incidence for the 24 unsuccessful sites (79%; P = 0.5). During sinus rhythm, a potential following the QRS complex (P2 potential) was more often recorded at the successful ablation site than at an unsuccessful ablation site before and after application of RF energy (before, P < 0.05; after, P < 0.001). The appearance of the P2 potential or a delay in the preexisting P2 potential after application of RF energy was observed only at the successful ablation sites (P < 0.001). In 18 control individuals who had no LV-VT, no P2 potential was recorded within the left sinus of Valsalva. Although the P1 potential may be useful for identifying the successful ablation site, its sensitivity is low. The appearance of the P2 potential or an increasingly delayed P2 potential after application of RF energy may be more useful than the P1 potential for predicting successful ablation.

Catheter Ablation↗

PubMed2004

Prevalence and characteristics of idiopathic outflow tract tachycardia with QRS alteration following catheter ablation requiring additional radiofrequency ablation at a different point in the outflow tract.

Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.

Adult↗

PubMed2004

Successful catheter ablation of atrial tachycardia originating near the atrioventricular node from the noncoronary sinus of Valsalva.

This report describes a patient who underwent RF catheter ablation of atrial tachycardia. Two applications of RF energy near the His-bundle region transiently terminated the tachycardia. With detailed mapping at the aortic sinus of Valsalva using a retrograde transaortic approach, the earliest atrial activation was found in the noncoronary sinus of Valsalva. Complete elimination of the tachycardia was achieved with RF energy application from this site.

Atrioventricular Node↗

PubMed2004

Regulation of hepatitis C virus replication by interferon regulatory factor 1.

Cellular antiviral responses are mediated partly by the expression of interferon-stimulated genes, triggered by viral genomes, their transcripts and replicative intermediates. Persistent replication of a hepatitis C virus (HCV) replicon suggests that the replicon does not elicit cellular innate antiviral responses. In the present study, we investigated regulatory factors of the interferon-mediated antiviral system in cells expressing an HCV replicon. Luciferase reporter assays revealed that the baseline activity of the interferon-stimulated response element (ISRE) was significantly lower in cells harboring the replicon than in naive cells. Among the proteins involved in the IFN/Jak/STAT pathway and in ISRE activity, the expression level of interferon regulatory factor 1 (IRF-1) was found to be significantly lower in cells harboring the replicon. Transfection of an IRF-1 expression construct into cells harboring the replicon caused an increase of ISRE activity, accompanied by suppression of expression of the HCV replicon. Moreover, in cured Huh7 cells from which the HCV replicon had been eliminated, the expression levels of IRF-1 and ISRE activity also were suppressed, demonstrating that the decrease of IRF-1 is attributable, not to active suppression by the viral proteins, but to adaptation of cells that enables replication of the HCV subgenome. The high permissiveness of the cured cells for the replicon was abolished by transgenic supplementation of IRF-1 expression. Taken together, IRF-1 is one of the key host factors that regulate intracellular HCV replication through modulation of interferon-stimulated-gene-mediated antiviral responses.

Base Sequence↗