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Biomedical subjects

Shigeaki Aoyagi

Publications and source records attributed to Shigeaki Aoyagi.

At least 19 recordsLinked to original sources
PubMed2007

Concomitant traumatic aortic valve and coronary artery injury.

A 79-year-old man, who had sustained nonpenetrating chest trauma 1 month previously, was admitted for dyspnea. Echocardiography demonstrated prolapse of the noncoronary aortic cusp with severe regurgitation. Aortography showed no intimal flap in the ascending aorta. Coronary arteriography showed dissection extending from the left main trunk to the proximal circumflex artery. At surgery, no abnormalities were found in the aortic wall or around the left coronary ostium. Avulsion of the commissure between the right coronary cusp and the noncoronary cusp from its aortic wall attachment was detected. Aortic valve replacement and coronary artery bypass grafting were performed.

Aged↗
PubMed2006

Moderate cerebral venous congestion induces rapid cerebral protection via adenosine A1 receptor activation.

Stroke is a devastating complication in cardiovascular surgery, and neuronal damage is worsened by intracranial pressure elevation caused by cerebral venous circulatory disturbances (CVCD). However, we have previously reported that CVCD before cerebral ischemia decreases the infarct area. In the present study, focal cerebral ischemia was induced in spontaneously hypertensive rats by filament insertion through the carotid artery. Rats were divided into the following four groups: sham-operated, mild or severe venous congestion (VC), and DPCPX. The DPCPX group received the adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) prior to mild VC. Behavior, infarct volume, edema and S-100 protein were evaluated among the four groups. The infarct volume rates in mild VC and severe VC groups were significantly less than that in sham-operated and DPCPX groups. However, the mortality of the severe VC group worsened in a time-dependent manner. We observed a significant decrease in edema in the mild VC group compared to the DPCPX group. Behavioral scores also indicated that the mild VC group had fewer neurological deficits than the other three groups, including the DPCPX group. We were able to induce rapid cerebral protection via adenosine A1 receptor activation by administering an appropriate degree of VC prior to cerebral ischemia produced by middle cerebral artery occlusion. Our work suggests possible mechanisms by which such effective VC may lead to cerebral protection and adenosine A1 receptor activation.

Adenosine A1 Receptor Antagonists↗
PubMed2006

Effects of nicorandil preconditioning on membrane dystrophin.

OBJECTIVE: Dystrophin is an integral membrane protein that stabilizes the sarcolemmal membrane integrity, and its loss may be involved in the mechanism of ischemia and reperfusion injury. It has been reported that ischemic preconditioning is related to the preservation of membrane dystrophin during ischemia and reperfusion. Preconditioning with nicorandil, a mitochondrial K(ATP) channel opener, may attenuate the injury by preventing a disturbance in the level of this membrane-associated protein. METHODS: The isolated rat hearts were subjected to 60 min of cardioplegic arrest, followed by 60 min of reperfusion. The hearts were divided into the following three groups according to the drugs given before cardioplegic arrest. The control group received saline intravenously 30 min before heart isolation. The nicorandil group received nicorandil (0.3 mg/kg) intravenously 30 min before isolation. The 5-HD group received 5-hydroxydecanoate (1 mg/kg) intravenously, a mitochondrial K(ATP) channel blocker, 5 min before nicorandil administration. Cardiac function, myocardial metabolism, dystrophin distribution and protein levels of dystrophin were assessed before and after cardioplegic arrest. RESULTS: The nicorandil group showed significantly better cardiac function and a significant reduction in creatine kinase release during reperfusion. After 60 min of cardioplegic arrest, dystrophin, which was distributed predominantly in the sarcolemmal membrane before ischemia, was translocated to the costameric cytoskeleton in all groups. During reperfusion, the level of membrane dystrophin remained decreased in the majority of cardiomyocytes in the control and 5-HD groups, whereas it was restored to nearly the baseline level in the nicorandil group. The immunoblot analysis supported this result. CONCLUSIONS: Depletion of sarcolemmal membrane dystrophin occurred during cardioplegic arrest and reperfusion. Nicorandil preconditioning may attenuate ischemia and reperfusion injury by maintaining the membrane structural integrity.

Animals↗
PubMed2006

The prostacyclin analog beraprost sodium augments the efficacy of therapeutic angiogenesis induced by autologous bone marrow cells.

Implantation of autologous bone marrow (BM) mononuclear cells (MNCs) has been shown to augment neovascular formation in ischemic tissues in experimental animals and in humans. Prostaglandin derivatives improve the symptoms of patients with critical limb ischemia, possibly by their vasodilating and antiplatelet actions. We therefore examined whether therapeutic angiogenesis by implantation of autologous BM-MNCs would be enhanced by beraprost sodium (BPS), using a rabbit ischemic hindlimb model. Ischemia was induced by surgical resection of the left femoral artery. Twenty-five New Zealand white rabbits were divided into four groups. The first group (BM group, n = 4) received autologous BM-MNCs (2 x 10(6)/animal) implanted into the ischemic tissue 1 week after limb ischemia. The second group (BM+BPS group, n = 8) received BPS injected into the dorsal skin (300 microg/kg daily) starting 1 week before limb surgery. This group received BM-MNC implantation 1 week after surgery. Daily injection of BPS was continued until the end of the protocol. The third group (BPS group, n = 8) received BPS injected into the dorsal skin (600 microg/kg daily) starting 1 week before limb surgery. The fourth group received saline as a control (n = 4). The extent of angiogenesis in the ischemic hindlimb was assessed using the angiographic score (AS), ischemic/normal limb calf blood pressure ratio (CBPR), and tissue capillary density. Four weeks after limb ischemia, the ischemic/normal CBPR was highest in the BM+BPS group, followed by the BPS, BM, and control groups (0.56 +/- 0.16, 0.51 +/- 0.25, 0.44 +/- 0.15, and 0.30 +/- 0.10, respectively). The AS was also the greatest in the BM+BP group, followed by the BM, BP, and S group (1.63 +/-0.21, 1.31 +/- 0.25, 1.26 +/- 0.21 and 0.80 +/- 0.10, respectively). The TCD was greatest in the BM+BP group, followed in by the BM, BP, and S group? (46 +/- 4.1, 34 +/- 0.7, 33 +/- 6.9, and 19 +/- 1.8 per field, respectively). BP treatment is an effective means to enhance the efficacy of therapeutic angiogenesis induced by autologous BM-MNCs implantation in ischemic hindlimb tissues.

Angiogenesis Inducing Agents↗
PubMed2006

Tumor growth suppression in pancreatic cancer by a putative metastasis suppressor gene Cap43/NDRG1/Drg-1 through modulation of angiogenesis.

Cap43 has been identified as a nickel- and calcium-induced gene, and is also known as N-myc downstream-regulated gene 1 (NDRG1), Drg-1 and rit42. It is also reported that overexpression of Cap43 suppresses metastasis of some malignancies, but its precise role remains unclear. In this study, we asked how Cap43 could modulate the tumor growth of pancreatic cancer. Stable Cap43 cDNA transfectants of pancreatic cancer cells with Cap43 overexpression showed similar growth rates in culture as their control counterparts with low Cap43 protein level. By contrast, Cap43 overexpression showed a marked decrease in tumor growth rates in vivo. Moreover, a marked reduction in tumor-induced angiogenesis was observed. Gelatinolytic activity by matrix metalloproteinase-9 and invasive ability in Matrigel invasion activity were markedly decreased in pancreatic cancer cell lines with high Cap43 expression. Cellular expression of matrix metalloproteinase-9 and two major angiogenic factors, vascular endothelial growth factor and interleukin-8, were also significantly decreased in cell lines with Cap43 overexpression as compared with their parental counterparts. Immunohistochemical analysis of specimens from 65 patients with pancreatic ductal adenocarcinoma showed a significant association between Cap43 expression and tumor microvascular density (P = 0.0001) as well as depth of invasion (P = 0.0003), histopathologic grading (P = 0.0244), and overall survival rates for patients with pancreatic cancer (P = 0.0062). Thus, Cap43 could play a key role in the angiogenic on- or off-switch of tumor stroma in pancreatic ductal adenocarcinoma.

Animals↗
PubMed2006

Infection management in a patient with a left ventricular assist device: a case report of long-term cefazolin sodium hydrate administration.

A 55-year-old woman suffered from a bloodstream infection (Staphylococcus aureus), which originated from pump inflow and outflow skin exits, from 4 months after a parocorporeal left ventricular assist device (LVAD) had been implanted. In addition to local irrigation, repeated administration of a weekly unit of cefazolin hydrate was temporarily effective, but fever frequently recurred. Because short-term antibiotic administration had limited effectiveness, a much longer-term course of cefazolin was begun at 14 months post-LVAD implantation and was planned to continue until future transplantation. Unfortunately, the patient died from a cerebral embolism at 19 months after LVAD implantation; long-term consecutive cefazolin administration had suppressed the infection for over 5 months without side effects. To treat intractable LVAD-associated bloodstream infection, long-term administration of a narrow-spectrum beta-lactam drug is an effective option.

Anti-Bacterial Agents↗
PubMed2006

Leaflet movement of the ATS valve in the aortic position: unique behavior observed in 19-mm valves.

BACKGROUND: Leaflet opening angles of ATS valves in vivo tend to be less than those reported by the manufacturer, and there is a wide variation in opening angles even among valves of the same size. METHODS: Leaflet movement of aortic ATS valves was evaluated by cineradiography in 77 patients. The mean period from valve replacement to cineradiography was 40.2 months, and during that period, the ATS valve was replaced due to prosthetic valve obstruction in 1 of the 77 patients. RESULTS: In 76 patients with a normally functioning ATS valve, the mean opening angle of 19-mm valves (66.3 degrees +/- 2.3 degrees) was significantly less (p < 0.0001) than that of ATS valves 21 mm or larger (72.2 degrees +/- 3.8 degrees in 21-mm, 72.4 degrees +/- 2.8 degrees in 23-mm, and 72.8 degrees +/- 2.9 degrees in 25-mm valves). No significant differences were found in the opening angles of ATS valves 21 mm or larger, and the opening angles exceeded 65 degrees in all 69 patients with valves in this category. In one case of obstruction in a 21-mm valve, the opening angle was 57.5 degrees. The closing angle was 24.9 degrees +/- 1.3 degrees, which corresponded well with the manufacturer's in vitro data. CONCLUSIONS: The opening angle in the 19-mm ATS aortic valve is significantly less than that in valves 21 mm or larger, and an opening angle of less than 65 degrees probably indicates prosthetic valve obstruction in aortic ATS valves sized 21 mm or larger.

Adolescent↗
PubMed2006

In vivo recellularization of plain decellularized xenografts with specific cell characterization in the systemic circulation: histological and immunohistochemical study.

Decellularized biological scaffolds have been used for the tissue engineering of heart valves with good results in the pulmonary circulation. However, little information is available on the recellularization of plain decellularized biological scaffolds in the systemic circulation. The aim of this study was to determine whether plain decellularized xenografts (PDXs) can recellularize with specific cell characterization in the systemic circulation. The xenogenic aortic valved conduit grafts of rabbits were implanted in the abdominal aorta of dogs after decellularization. The grafts were explanted at 4, 12, or 24 weeks after implantation for histological, immunohistochemical examination, scanning electron microscope, and Western blot analysis. Although the valvular structures were completely lost after implantation, supravalvular conduits showed normal shapes and endothelialization. The PDXs were repopulated with basic vascular cell components in approximate natural proportions without immunological responses. The PDXs had been recellularized with specific cell characterization in the systemic circulation.

Actins↗
PubMed2006

Long-term survivors after valve replacement with a Starr-Edwards mitral disk valve prosthesis.

We report four long-term survivors after valve replacement with a Starr-Edwards (S-E) mitral caged-disk valve. A model 6520 disk valve, size 3M, had been used in all of the four patients. Of the four patients, three underwent replacement of the disk valves 23, 24, and 26 years after mitral valve replacement (MVR), respectively. A pacemaker was implanted in the remaining patient 33 years after MVR. The S-E disk valves were considered hemodynamically slightly stenotic compared with modern bileaflet valves. No disk wear was detected in any of the three explanted valves, and in the remaining patient, a noninvasive evaluation of the disk showed that it was functioning normally. These results suggest the favorable long-term durability of the S-E disk valve.

Aged↗
PubMed2006

Late re-operation for aortic and mitral Starr-Edwards ball valve prostheses.

Starr-Edwards ball valves removed more than 15 years after implantation were retrospectively investigated macroscopically. Eight patients required re-operation. Valve models used in the initial operations were a non-cloth-covered valve in 2 patients and a cloth-covered valve in 6. Two patients had replacement of an aortic ball valve (model 1260 and model 2320) and 6 underwent mitral valve replacement (model 6120 in one, model 6320 in 5). The mean time to re-operation was 23.0 +/- 4.8 years after implantation. Cloth wear causing significant hemolysis was observed in all cloth-covered valves, regardless of valve position. Autologous tissue growth was noted on the orifice ring and struts in both aortic and mitral prostheses. Thrombus formation was not found in any of the valves. Ball variance in silicone rubber balls was mild in the non-cloth-covered valves, even in the aortic position. The most significant problem with the cloth-covered ball valve was cloth wear. Cloth wear should always be considered when 15 years or more have passed since valve implantation. Significant hemolysis, elevation of lactate dehydrogenase values, and echocardiographic detection of transvalvular regurgitation are diagnostic of cloth wear, and are indications for replacement of a cloth-covered ball valve.

Adult↗
PubMed2006

Initial and midterm results for repair of aortic diseases with handmade stent grafts.

BACKGROUND: The purpose of this study was to determine the initial and midterm results for repair of thoracic and abdominal aortic diseases using handmade stent-grafts (SGs). METHODS AND RESULTS: Between 1999 and 2004, 41 consecutive patients (31 patients with thoracic and 10 patients with abdominal aortic disease) underwent endovascular stent-graft repair using handmade SGs. The follow-up averaged 24.8+/-17.6 months. The technical and initial clinical success rates were 82.9% (34/41) and 80.5% (33/41), respectively. Primary type I or III endoleaks occurred in 12.2% (5/41) of the patients. The hospital mortality rate was 4.9% (2/41). Persistent type I or III endoleaks occurred in 9.8% (4/41) and SG migrations occurred in 4.9% (2/41) of the patients. Open surgical conversion was undertaken in 12.2% (5/41) of the patients because of an endoleak and/or migration. The mean change observed in the aneurysm diameter was -6.2+/-10.5 mm, and shrinkage in the diameter occurred in 51.4% (18/35) of the cases. There was 1 patient death because of aneurysm rupture. Neither stent fracture nor graft hole was observed. The overall clinical success rate during follow-up was 78.0% (32/41). CONCLUSION: The initial and midterm results obtained after repair of the aortic diseases using handmade SGs were considered to be satisfactory. More surgical experience and long-term patient follow-up are both required to further reassess the effect of this treatment.

Adult↗
PubMed2006

Coronary artery fistula from the left circumflex to the coronary sinus.

A 27-year-old woman, who had received mitral valve repair for mitral regurgitation resulting from infective endocarditis, was admitted for a close examination of abnormal echocardiographic findings in the left atrium. Transthoracic echocardiography showed trivial mitral regurgitation with normal left ventricular contraction and dilatation of the coronary sinus. Auscultation revealed a grade 2 continuous murmur along the left sternal border. Transesophageal echocardiography demonstrated a marked dilatation of the coronary sinus just behind the posterior wall of the left atrium and turbulent blood flow in the dilated coronary sinus. Cardiac catheterization showed no significant step-up of oxygen saturation in the right heart and normal pulmonary artery pressure. Coronary angiography revealed a markedly dilated and tortuous circumflex coronary artery connected to the coronary sinus through a fistula. A left circumflex artery with a fistulous connection to the coronary sinus is extremely rare.

Adult↗
PubMed2006

Aortic valve replacement after esophagectomy with substernal gastric tube reconstruction.

A 67-year-old woman with a history of esophagectomy with substernal gastric tube (GT) reconstruction and left lower lobectomy required aortic valve replacement (AVR) for aortic valve regurgitation and stenosis. Through a median sternotomy (MS) with cardiopulmonary bypass (CPB), we performed AVR without injury to the GT. Careful peeling of the GT and detailed information of the operative field by multidetector-row computed tomography (MDCT) scan enabled us to carry out the operation safely in the usual operative view.

Aged↗
PubMed2005

Dysfunction of an ATS valve in the aortic position: the first reported case caused by pannus formation.

A 64-year-old woman underwent aortic valve replacement with a 21-mm Advancing The Standard (ATS) open-pivot mechanical heart valve for bicuspid aortic valve stenosis. In addition to the appearance of a new cardiac murmur, echocardiography performed 3 years after surgery showed a high pressure gradient across the ATS valve and a reduction in the valve orifice area. Cineradiography of the valve revealed restricted leaflet opening. Subsequent multidetector-row computed tomography clearly demonstrated pannus overgrowth on the inflow aspect of the ATS valve. During a repeat operation, subvalvular overgrown pannus was confirmed and the ATS valve was replaced with a bioprosthetic valve. This is the first reported case of prosthetic valve dysfunction resulting from pannus formation in a patient with an ATS valve in the aortic position.

Aortic Valve Stenosis↗
PubMed2005

P-wave signal-averaged electrocardiogram for predicting atrial arrhythmia after cardiac surgery.

BACKGROUND: Atrial arrhythmias (AF) are usually benign, but occur frequently after cardiac surgery. P-wave signal-averaged electrocardiogram has been used to characterize atrial conduction delay as a marker of risk of AF during sinus rhythm. METHODS: Ninety-five patients undergoing either primary isolated coronary artery bypass grafting or aortic valve replacement were enrolled. The duration and the root mean square voltage for the last 20 ms of filtered (40 to 300 Hz) P-wave of the spatial magnitude were recorded before surgery. Any episode of postoperative atrial fibrillation, atrial flutter, or paroxysmal atrial fibrillation lasting longer than 1 hour was considered as AF. RESULTS: Twenty-eight patients (29%) exhibited AF 3.0 +/- 2.3 days after surgery. The P-wave duration recorded with P-wave signal-averaged electrocardiogram was significantly prolonged in patients with AF (135 +/- 14 ms versus 127 +/- 9 ms; p = 0.002). Patients with AF more often had dilated left atrium (p = 0.003), left ventricular hypertrophy (p = 0.03), and advanced age (p = 0.02). Logistic regression analysis identified the following three variables as predictive of AF: P-wave duration of 135 ms or greater (p = 0.02; odds ratio, 3.5), patients 70 years of age and older (p = 0.03; odds ratio, 3.2), and left atrial dimension of 35 mm or greater (p = 0.03; odds ratio, 3.2). If a patient had two or more of these three risk factors, the occurrence of AF was predicted with a sensitivity of 75%, specificity of 76%, positive predictive accuracy of 57%, and negative predictive accuracy of 88%. CONCLUSIONS: The prolonged P-wave duration recorded with P-wave signal-averaged electrocardiogram, together with advanced age and left atrial enlargement, is a potent and independent predictor of AF after cardiac surgery. Patients with these risk factors may benefit from prophylactic antiarrhythmic treatment.

Aged↗