Biomedical subjects

Noriyuki Tabuchi

Publications and source records attributed to Noriyuki Tabuchi.

At least 19 recordsLinked to original sources

PubMed2006

Matrix metalloproteinase inhibitor (ONO-4817) attenuates ischemia-reperfusion injury in rat lung.

BACKGROUND: Ischemia-reperfusion injury of the lungs seems to be initiated by the activation of alveolar macrophages, and mediated by matrix metalloproteinases (MMP)s, although their roles have not been fully elucidated. Therefore, we used a novel MMP inhibitor (ONO-4817) with high affinities for MMP-2 and MMP-9 to investigate the roles of MMPs in reperfusion injury of the lungs. MATERIAL/METHODS: After 18 h of cold ischemia, isolated rat lungs were ventilated and reperfused. Lungs without ischemia served as controls. Lungs were reperfused with fresh blood with or without the MMP inhibitor for 120 min at 37 degrees C. RESULTS: The oxygenation capacity of lungs after ischemia deteriorated progressively during 120 min of reperfusion, but was preserved by the MMP inhibitor (p<0.05). The histopathology of the lungs after ischemia-reperfusion showed interstitial edema accompanied by neutrophil migration, and the number of neutrophils, but not macrophages, in the broncho-alveolar lavage increased to more than two-fold the value in control lungs without ischemia (p<0.01). These changes were attenuated by the MMP inhibitor (p<0.01). Similarly, an increase in the tissue malondialdehyde level in lungs after ischemia-reperfusion was ameliorated by the MMP inhibitor (p<0.01). The expressions of CD11c and CD31 adhesion molecules in extracted alveolar macrophages increased in lungs after ischemia-reperfusion compared with control lungs without ischemia, and the MMP inhibitor had no obvious effect. CONCLUSIONS: Our data show that ONO-4817 prevented neutrophil migration into the interstitial space and alveolus in the lungs, and reduced the production of oxygen free radicals, suggesting that this is an important mechanism in reperfusion injury.

Animals↗

PubMed2006

Physiological comparison of off-pump and on-pump coronary artery bypass grafting in patients on chronic hemodialysis.

OBJECTIVES: Despite the long-term benefit, the operative results of conventional coronary artery bypass grafting for chronic hemodialysis patients remain unsatisfactory. The efficacy of off-pump coronary artery bypass grafting for hemodialysis patients is yet to be determined. The purpose of this study was to investigate the postoperative physiology of off-pump coronary artery bypass grafting for hemodialysis patients. METHODS: Twenty-five hemodialysis cases who underwent isolated coronary artery bypass grafting were reviewed. Fifteen of these patients underwent off-pump coronary artery bypass grafting (off-group) and 10 underwent on-pump coronary artery bypass grafting (on-group). Comparisons were made in cardiac function (cardiac index and stroke volume index), respiratory function (AaDO2), hemodialysis management (blood urea nitrogen, creatinine, right atrial pressure, pulmonary wedge pressure), and bleeding tendency (postoperative blood loss and blood transfusion). RESULTS: There was no operative mortality, but 3 major postoperative complications occurred (2 sternal wound infections in the off-group and 1 pneumonia in the on-group). There was no difference in cardiac index or stroke volume index. AaDO2 was significantly lower in the off-group. Plasma concentrations of blood urea nitrogen and creatinine were similar between groups. Right atrial pressure was lower and pulmonary wedge pressure tended to be lower in the off-group. Postoperative bleeding and blood transfusion were similar between groups. CONCLUSION: Our study confirmed that off-pump coronary artery bypass grafting is feasible for hemodialysis patients. Physiologic data showed that off-pump coronary artery bypass grafting might be effective in preserving postoperative lung oxygenation.

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PubMed2005

Oral cibenzoline reduces postoperative atrial fibrillation in coronary artery bypass grafting.

OBJECTIVE: The objective of the present study was to investigate the effectiveness of postoperative oral administration of cibenzoline for the prevention of atrial fibrillation (AF) in coronary artery bypass grafting (CABG). METHODS: A total of 39 patients who underwent isolated CABG from September 2000 to February 2001 and who took oral cibenzoline (300 mg per day for 10 days beginning immediately after surgery) were compared to 59 patients who underwent surgery in our department 8 months prior to the study and who did not take cibenzoline for incidence of postoperative AF. Exclusion criteria encompassed age (>80 years), low ejection fraction (<30%), high serum creatinine level (>2.0 mg/dL), and history of supraventricular arrhythmia with or without treatment by anti-arrhythmic drugs. RESULTS: Postoperative AF occurred in 2 patients in the cibenzoline group (2/35, 5.7%) and 20 patients in the control group (20/59, 33.9%). There were significant differences in the incidence of postoperative AF (p = 0.002). Multivariate analysis revealed that the administration of cibenzoline reduced the incidence of AF significantly, and that a large number of bypass grafts significantly contributed to postoperative AF in CABG. The number of bypass grafts was significantly larger in the cibenzoline group, indicating that cibenzoline administration significantly suppresses the incidence of AF after CABG in high-risk patients. CONCLUSIONS: Postoperative administration of oral cibenzoline for 10 days is one effective method for the prevention of AF after CABG.

Administration, Oral↗

PubMed2005

Safe coronary artery occlusion with a new tourniquet in off-pump bypass grafting.

Coronary artery occlusion during off-pump coronary artery bypass grafting may lead to mechanical trauma of the arterial wall. My colleagues and I describe a safe coronary artery occlusion technique in off-pump bypass grafting that uses a new spring-equipped tourniquet, which enables precise adjustment of the least force necessary to occlude the coronary flow. This prevents snare-induced vessel wall damage.

Coronary Artery Bypass, Off-Pump↗

PubMed2005

Effects of the postoperative administration of diltiazem on renal function after coronary artery bypass grafting.

BACKGROUND: Radial artery grafts are used for coronary artery bypass grafting (CABG), and postoperative antispasm therapy with diltiazem is performed widely. Some investigators have warned that diltiazem administration after cardiac surgery is harmful to renal function. We designed a retrospective study to investigate the renal and hemodynamic effects of the postoperative administration of diltiazem in patients undergoing CABG. METHODS: Subjects were 90 consecutive CABG patients. All were treated with diltiazem during surgery (a 0.1 mg/kg bolus injection followed by continuous infusion at 2 microg x kg(-1) x min(-1)). In the 50 patients (diltiazem group) with a radial artery graft, intravenous diltiazem administration was continued until the oral intake of diltiazem (90 mg/d) was begun to avoid graft spasms. In the remaining 40 patients without a radial artery graft, diltiazem was not continued postoperatively (control group). Postoperative renal function, assessed by serum creatinine level and creatinine clearance, and hemodynamic variables (heart rate, arterial pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index) was compared between the two groups. RESULTS: Renal function: Serum creatinine concentrations on postoperative days 1 through 7 were lower, and the endogenous creatinine clearance in the early postoperative period was higher in diltiazem group than in control group, although the differences were not significant. Hemodynamics: Heart rate was lower in diltiazem group than in the control group, but blood pressure, pulmonary wedge pressure, cardiac index, left ventricular stroke work index, and urinary output were similar between the groups. CONCLUSIONS: Our results confirmed that intravenous diltiazem treatment in patients undergoing CABG is not harmful to renal function.

Coronary Artery Bypass↗

PubMed2005

Aprotinin attenuated ischemia-reperfusion injury in an isolated rat lung model after 18-hours preservation.

OBJECTIVE: Ischemia-reperfusion injury is a major factor in the early phase of lung transplantation. We hypothesized that aprotinin, a nonspecific serine protease inhibitor, attenuates ischemia-reperfusion lung injury by inhibiting the inflammatory response and suppressing NADPH oxidase. METHODS: We used an isolated rat lung model to test the above. A Control group was immediately perfused with fresh heparinized allogeneic blood after lung harvest without an ischemic period. Study lungs were flushed with low-potassium dextran (LPD) solution and stored for 18h at 4 degrees C then divided into two groups: the LPD group was flushed with LPD solution only, and the LPD+A group was flushed with LPD solution +200KIU/ml aprotinin. Lungs in all three groups were then reperfused with fresh heparinized allogeneic blood for 120min at 37 degrees C. RESULTS: Throughout reperfusion, PO(2) levels in the LPD+A group were similar to those in the Control group; although in the LPD group, PO(2) levels were significantly lower (P<0.05). Tissue MDA levels were significantly higher in the LPD group than the Control and LPD+A groups (P<0.05). IL-8 levels were significantly higher in the LPD group than the Control group (P<0.05), while in the LPD+A group they were similar to those in the Control group. Histological evaluation showed interstitial edema accompanied by neutrophil extravasation in the LPD group, whereas this effect was modest in the LPD+A group. An additional study of ischemia-reperfusion in an alveolar macrophage culture showed that the activitvation of NADPH oxidase, and translocation of p47(phox) from the cytosol to the membrane were suppressed in aprotinin group. CONCLUSIONS: Aprotinin attenuates ischemia-reperfusion lung injury by inhibiting the early inflammatory response, neutrophil extravasation and the production of oxygen free radicals through inhibition of the activation of the NADPH oxidase. The inhibition of p47(phox) translocation in alveolar macrophage seemed involved in this mechanism of aprotinin.

Animals↗

PubMed2005

Hand circulation after radial artery harvest for coronary artery bypass grafting.

Despite wide spread use of the radial artery (RA) graft for coronary artery bypass grafting, the change of hand circulation after RA harvest has not been fully clarified. Severe hand ischemia such as resting pain or gangrene is a rare complication and has been reported in 4 patients. These cases resulted from occlusive artery disease in forearm, which should be carefully explored before RA harvest. Incidence of mild hand ischemia such as hand claudication or fatigue is unknown, but our study suggested that around 10% of the patients developed mild hand ischemia after RA harvest. The blood flow to the forearm territory was decreased by 20% after RA harvest despite the compensatory dilatation of ulnar artery. The presence of low perfusion in the affected hand has been pointed out in some studies. We reported the decreased tissue oxygenation of the affected hand during hand grip exercise. The Allen test is the most popular preoperative screening method, but is associated with considerable numbers of false-positive and false-negative results. Full length scanning of ulnar artery by ultrasonography seems to have a lower false-positive rate. But further clinical experience is necessary to establish a more reliable screening method.

Coronary Artery Bypass↗

PubMed2005

Endoscopic radial artery harvesting: our initial experience and results of the first 25 patients.

BACKGROUND: The radial artery has become an increasingly popular arterial conduit for coronary artery bypass grafting (CABG). However, the traditional open harvesting technique requires a long incision, and is therefore associated with some wound complications and cosmetic problems. Here, we describe our experience of endoscopic radial artery harvesting (ERAH) through a small incision in 25 patients who underwent CABG. MATERIALS AND METHODS: Between February 2, 2004 and January 7, 2005, a total of 25 patients (4 females; mean age: 64+/-10 years) underwent ERAH using the VasoView System (Guidant Corporation, Indianapolis, IN) at our institution. All patients underwent a preoperative Allen test to assess the competence of the palmer arch. Twenty-four radial arteries were harvested from the nondominant arm and one from the dominant arm. The mean clinical follow-up was 8+/-2.9 months. RESULTS: All radial arteries were harvested through a 2-cm incision at the wrist, successfully removed with ERAH and successfully used as CABG conduits. The mean harvest time was 59+/-11 min, and the mean harvested length was 17+/-1.7 cm. No adjunctive procedures were required during vessel harvesting, and no conversions to the open technique were necessary. Harvesting complications included 2 cases of postoperative hematoma and 7 cases of superficial radial nerve paresthesia. Five postoperative angiographies were performed and all radial arteries were patent. Overall, 24/25 (96%) patients were satisfied with the procedure. CONCLUSION: The ERAH technique was performed as safely as the traditional open technique and the harvested radial arteries were acceptable as CABG conduits. In particular, patient satisfaction with the procedure regarding the cosmetic results was excellent.

Coronary Artery Bypass↗

PubMed2004

Perfusion flow assessment of coronary shunt during off-pump coronary artery bypass grafting.

BACKGROUND: Coronary shunts are widely used to prevent myocardial ischemia during off-pump coronary artery bypass graft (OPCAB) procedures. Although clinical effectiveness has been reported, actual perfusion flow has not been well assessed. The purpose of this study was to evaluate actual shunt flow and its pattern during passive coronary perfusion in clinical OPCAB. METHODS: In 15 OPCAB cases, the coronary perfusion flow of the external shunt (1.7 or 2.0 mm) during anastomosis and the free flow of the shunt were measured with an in-line electromagnetic or ultrasonic flow probe. The perfused coronary blood vessel was either the left anterior descending coronary artery or the right coronary artery. The inflow vessel of the external shunt was either the femoral artery (FA) or the ascending aorta (AA). RESULTS: Free flow values of a 1.7-mm FA shunt, 1.7-mm AA shunt, and 2.0-mm FA shunt were 34+/- 7, 39 +/- 3, and 44 +/- 7 mL/min. Perfusion flows were 13 +/- 4, 14 +/- 3, and 22 +/- 4 mL/min, respectively. Perfusion flow was significantly lower than free flow and correlated well with coronary resistance. Although inflow site did not influence net perfusion flow, diastolic/systolic flow fraction ratio was significantly greater when the shunt was perfused from the FA. CONCLUSIONS: External shunt from FA would provide limited but effective perfusion flow with a physiological pattern, which is passively regulated by coronary resistance.

Aged↗

PubMed2004

Oxygen pressure measurement during grip exercise reveals exercise intolerance after radial harvest.

BACKGROUND: Exercise intolerance of the hand after harvest of the radial artery is not well understood, although mild reductions of blood flow to the hand are reported. To ascertain its prevalence, patient symptoms implying potential exercise intolerance were evaluated by measuring transcutaneous oxygen pressure of the hand during grip exercise. For ascertaining predictive values, we verified ulnar flow reserve measured by Doppler ultrasonography before the harvest of radial artery. METHODS: Forty patients whose radial artery was harvested for coronary bypass graft, were interviewed and tested 1 year after operation, and their preoperative ultrasonographic data compared. RESULTS: Five patients (12.5%) had mild symptoms implying exercise intolerance. Exercise tests revealed severe decreases in tissue oxygenation in 7 patients (17.5%), but in accordance with symptoms (p = 0.0018). Tissue oxygenation in the operated hand was lower than in the nonoperated even in asymptomatic patients (p = 0.0011). Preoperative Doppler echography revealed that ulnar arteries of symptomatic patients were smaller (p = 0.0019) and carried lower blood flows during manual compression of the radial artery (p = 0.0004) compared with those of asymptomatic patients. Smaller ulnar arteries (less than 1.4 mm/m(2)) with poor flow reserves (less than 60 mL x min(-1) x m(-2) during radial compression) appear to indicate risks for exercise intolerance (p = 0.0004). CONCLUSIONS: More than 10% of patients after harvest of radial arteries had mild symptoms implying exercise-intolerance, which accorded with abnormal tissue oxygenation during grip exercise. Work habits of patients should be considered in radial harvest decisions, especially if preoperative Doppler echography indicates lower flow reserves for the ulnar artery.

Blood Flow Velocity↗

PubMed2004

Non-viral in vivo thrombomodulin gene transfer prevents early loss of thromboresistance of grafted veins.

OBJECTIVE: Immediate loss of thrombomodulin activity in the endothelium of vein grafts has been demonstrated during 90 min exposure to arterial circulation; this loss of activity is ascribed as an important cause of early thrombosis. Conventional ex vivo gene transfection after vein harvest cannot cover this acute period immediately after implantation. We have established a highly efficient non-viral gene therapy protocol utilizing modified transferrin receptor-facilitated gene transfer. Using this technique, we examined whether in vivo thrombomodulin gene therapy, directed to the endothelium of rat veins 2 days prior to grafting, may prevent thromboresistance impairment of vein grafts under simulated arterial circulation. METHODS: Abdomen of SD rat was opened and cationic liposome:transferrin:thrombomodulin gene complexes or the vector without DNAs were applied to the inferior vena cava of rats while blood flow was reduced by proximal and distal clamping. After 2 days, the transfected veins were harvested and thrombomodulin expression and thromboresistance properties determined before and after exposure to an artificial circuit. RESULTS: The trial of gene transfection using variable doses of DNAs confirmed that 7.5 microg of total DNAs was the most efficient quantity for thrombomodulin gene transfection to IVCs, although accompanying an increase of gene expression in other downstream organs. By transfection of the thrombomodulin gene in IVCs, the generation capacity of activated protein C in venous endothelium increased three-fold compared with veins treated with vector alone (P<0.01). Under simulated arterial circulation, perfusion of veins treated with vector alone decreased thrombomodulin activity to 36% of preperfused levels (P<0.01), whereas transfected grafts preserved the activity at normal vein endothelium levels even after perfusion. Consequently, the increase in endothelial thrombin activity induced by simulated arterial circulation was markedly attenuated in transfected veins (P<0.01), while immunohistochemistry confirmed the preservation of endothelial lining. CONCLUSIONS: Transferrin receptor-facilitated in vivo gene transfer to the inferior vena cava resulted in sufficient thrombomodulin gene expression immediately after graft implantation and subsequent maintenance of thromboresistance even after exposure to arterial pressure. Although further studies are needed, the present results suggest the possibility of gene therapy targeting acute phases of vein graft disease.

Animals↗

PubMed2004

Double-patch technique for postinfarction ventricular septal perforation.

A modified infarct-exclusion technique for postinfarction ventricular septal perforation is presented. The perforation is closed directly by a small patch next to the conventional patch, and biological glue is applied between the patches to induce stable polymerization. The patch stuck to the infarcted septum, and no residual shunt was observed in any patient because the wide adhesion prevents excessive pressure on the suture line. Seven of 9 patients in whom this method was used had good results. This technique appears suited for repair of ventricular septal perforations, especially those with extensive fresh infarction.

Cardiac Surgical Procedures↗

PubMed2004

Formation of tissue factor-bearing leukocytes during and after cardiopulmonary bypass.

During cardiopulmonary bypass (CPB), the extrinsic coagulation system initiated by tissue factor (TF) is a major procoagulant stimulus. TF is present in surgical wounds and could be expressed on activated monocytes. However, recent studies have suggested that collagen stimulation rapidly induces TF by leukocyte-platelet complex formation. Therefore, the appearance of TF-bearing leukocytes and their effect on promoting coagulation were investigated in 5 patients undergoing coronary bypass surgery. Neutrophils and monocytes positive for CD41a and TF increased abruptly in circulating blood during CPB. Their increase was most prominent in blood pooled in the pericardial cavity. Monocytes, but not neutrophils positive for TF showed a second peak one day after operation, which accords with the increase in TF mRNA levels in leukocytes. Similarly, an increase in leukocytes positive for TF accords with the activated factor X generation assay using isolated leukocytes, and with an increase in thrombin-antithrombin complex in circulating blood. The second increase in TF-positive monocytes seems to be responsible for these coagulation parameters that remained high one day after operation. After 10 min of blood incubation stimulated by collagen in vitro, simulating activation in the pericardial cavity, significant increases in neutrophils and monocytes positive for TF and platelet were observed. Our present study suggested the involvement of two distinct mechanisms for the appearance of TF-bearing leukocytes responsible for promoting coagulation: the quick appearance being partly explained by the formation of leukocyte-platelet complex that occurs mainly in the pericardial cavity, and the slow appearance via transcriptional activation in monocytes.

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PubMed2003

Transaortic stented graft implantation for aortic arch aneurysm. Its benefits and risk.

OBJECTIVES: Despite steady improvements, surgery for aortic arch disease, including the distal arch, continues to result in high rates of morbidity and mortality. We have performed aortic arch repair using a transaortic stented graft implantation into the descending aorta in 8 patients who had true aortic arch aneurysms, and here have reviewed the efficacy and problems from this procedure. METHODS: Six patients underwent transaortic stented graft implantation into the descending aorta with bypass to the arch vessels. The other two underwent stented graft implantation into the descending aorta with replacement of the ascending aorta and aortic arch. One patient had a ruptured aneurysm. RESULTS: Each operation was performed via a median sternotomy without left thoracotomy. There was no new postoperative occurrence of left recurrent laryngeal nerve palsy. All the five patients without perioperative neurological complication could be extubated within 24 h after surgery. In each case, postoperative enhanced computed tomography scans showed successful thromboexclusion of the aneurysm. There was no endoleak and no graft migration. One patient suffered cerebral injury. Spinal cord injury occurred in 2 patients, and this serious complication may have been caused by prolonged ischemia in the lower body and the long stented graft. CONCLUSIONS: This surgical strategy was effective for arch aneurysm and produced less damage than a conventional procedure to the postoperative respiratory function, while the operative technique need to be improved to decrease the frequency of brain and spinal cord injury.

Aged↗

PubMed2003

Triple quantum nutation in the two-level NMR system in the rotating frame.

The authors present the detailed theory and the new results associated with the triple quantum (TQ) nutation and the line narrowing effect of the TQ resonance in the two-level NMR system which we reported previously. The TQ resonance is induced in the spin-locked system by the oscillating field produced by the sinusoidal phase modulation (PM) of the RF field. The theory predicts that the TQ nutation is accompanied by several higher frequency oscillations and we detected them experimentally by improving the detection system. These higher frequency oscillations are due to the fluctuation of the angle between the transverse or effective field causing the TQ nutation and the RF field. We obtain the result that the modulation index 2phim of the PM is the key parameter that essentially controls the conditions of the TQ resonance and the narrowing effect. Under the exact TQ resonance, the ratio of the TQ resonance frequency to the Larmor frequency of the RF field depends only on phim, and the secular part of the magnetic dipole Hamiltonian of a like spin system in the triply rotating frame disappears at a particular value of phim. The condition is different from that of the well-known magic angle condition.

Journal Article↗

PubMed2003

Biventricular pacing with coronary bypass and Dor's ventriculoplasty.

We applied biventricular pacing to a patient with severe ischemic dilated cardiomyopathy (left ventricular [LV] ejection fraction 19%, LV end-diastolic volume 360 mL, and complete left bundle branch block). An epicardial LV lead was surgically implanted concomitant with on-pump beating coronary artery bypass grafting and Dor's endoventricular circular patch plasty. Biventricular pacing immediately achieved the resynchronization of the LV contraction, and improved cardiac function as well as reducing mitral regurgitation. Biventricular pacing combined with cardiac surgery for patients with cardiomyopathy and complete left bundle branch block may produce beneficial effects on LV function.

Aged↗

PubMed2003

Activated leukocytes adsorbed on the surface of an extracorporeal circuit.

Biocompatibility of extracorporeal circuits has mostly been investigated by sampling blood in circulation. However, a proportion of activated leukocytes leave circulation by sticking to the circuits, and might affect the circuit biocompatibility. To reveal these characteristics, we eluted the adsorbed leukocytes from circuits used for 6 patients by washing with ethylenediaminetetraacetic acid (EDTA)-HEPES buffer. 1.3 x 109 leukocytes, representing 5 to 10% of the circulating leukocytes, were collected. Most were neutrophils expressing CD11b antigens as high as those in circulation during cardiopulmonary bypass. Adsorbed monocytes expressed tissue factor higher than those in circulation (P < 0.05). An elution procedure by EDTA itself induced only a minimal activation of the leukocytes. These results indicate that extracorporeal circuits adsorb a large number of activated neutrophils and a small number of highly thrombogenic monocytes during their use. Although our data is limited, this elution procedure appears useful to investigate the biocompatibility of extracorporeal circuits.

Aged↗

PubMed2002

New line-narrowing effect in triple-quantum resonance in a two-level NMR system.

We report a new line-narrowing effect associated with triple-quantum resonance in a two-level NMR system. The experiment was carried out in the rotating frame on (19)F nuclei in Teflon; namely, the magnetization is spin-locked along the RF field and the triple-quantum resonance is induced by the oscillating field perpendicular to the RF field. We observed that the decay time of the triple-quantum nutation becomes extraordinarily long at a particular intensity and frequency of the oscillating field. The decay time is about seven times as long as that of the single-quantum nutation and also much longer than that of the magic angle nutation. The mechanism is not interpreted by straightforward analogy to the theory of the current magic angle narrowing.

Journal Article↗