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Biomedical subjects

K Tabayashi

Publications and source records attributed to K Tabayashi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Open surgical repair for a perigraft leak after endovascular stent-graft emplacement of descending thoracic aneurysm.

Although transluminal stent-graft implantation is less invasive for treating an aneurysm in the thoracic descending aorta, this technique is not always successful. Here, we report two cases of a perigraft leak identified after stent-graft deployment, and complete occlusion of the leak could not be attained by additional stent-graft deployment. Open surgical repair using a stented graft was performed through a median sternotomy without opening the left pleura. This procedure should be considered as one of the less-invasive techniques for treating a perigraft leak after endovascular stent-graft emplacement.

Aged↗
PubMed2001

Commissure holder: an innovative device for aortic valve-sparing technique.

The key to obtaining maximal valve coaptation from the aortic valve-sparing procedure is in appreciating the optimal geometry of each component of the aortic root. We describe a new device called the Commissure Holder (patent pending) that aids in the selection of an appropriate graft size and in the determination of the optimal position at which each commissure should be sutured to the graft.

Aorta, Thoracic↗
PubMed2001

Cleft on tricuspid anterior leaflet.

We report a case of isolated congenital tricuspid regurgitation caused by a cleft in the anterior tricuspid leaflet associated with a patent foramen ovale. Preoperative echocardiography revealed severe tricuspid regurgitation resulting from anterior tricuspid leaflet prolapse. The patient underwent successful tricuspid valve repair with simple cleft suture and annuloplasty and direct closure of the patent foramen ovale.

Cardiac Surgical Procedures↗
PubMed2001

Increased von Willebrand factor in the endocardium as a local predisposing factor for thrombogenesis in overloaded human atrial appendage.

OBJECTIVES: We investigated immunoreactive von Willebrand factor (vWF), a platelet adhesion molecule, in the endocardial endothelium and its relationship to thrombogenesis in the human atrial appendage. BACKGROUND: Intra-atrial thrombogenesis is generally thought to be induced by blood stasis in the atrial appendage involved with atrial fibrillation (AF). Little attention has been paid to alterations of the endocardial endothelium on which the thrombus develops. METHODS: Atrial appendage tissue was obtained at heart surgery or at autopsy from AF and non-AF cardiac patients and from noncardiac patients. Immunohistochemistry for endothelial cell markers including vWF, CD31, CD34 and endothelial nitric oxide synthase (eNOS) and platelet glycoprotein Ib/IX or IIb/IIIa was performed and semiquantitatively graded. RESULTS: In contrast to the apparent immunostaining for CD31, CD34 and eNOS, only focal or little immunoreactive vWF was seen in the endocardium of noncardiac patients. Immunoreactive vWF in the endocardial endothelium was increased in most cardiac patients, particularly in the left, but not in the right, atrial appendage of patients with mitral valvular disease, irrespective of whether AF was present. Platelet adhesion/thrombus formation in the endocardium was found in limited sites in which the overlying endothelium was deficient in eNOS and CD34. When warfarin-treated cases were excluded, there was a significant correlation between the immunohistochemical grade for vWF and the degree of platelet adhesion/thrombus formation in the endocardium. CONCLUSIONS: Immunoreactive vWF in the endocardial endothelium was increased in overloaded human atrial appendage, which may be a local predisposing factor for intraatrial thrombogenesis.

Adult↗
PubMed2001

Fluctuations of Emax of the left ventricle: effect of atrial natriuretic polypeptide.

Recently the circadian rhythm of fluctuations in heart rate variability (HRV) has gained increasing attention, and the use of appropriate treatment corresponding to the circadian rhythm has become an important issue. However, the question has been raised as to whether the rhythm of fluctuation is only limited to HRV, and if a rhythm is also present in the contraction of the heart. The mathematical technique of electrical circuit simulation of the cardiovascular system was used to observe the Emax rhythm. In this study, the therapeutic effect of various drugs, including atrial natriuretic polypeptide (ANP), was confirmed. The effect of inotropic drugs including ANP on Emax was observed, and the results based on an old and a new method of determining Emax . were examined. Furthermore, the chaos analysis of Emax was also made. The time series of Emax showed an increased complexity due to the administration of ANP. In conclusion, it might be important to consider not only the fluctuation of HRV, but also an analysis of the fluctuation in the contraction of the heart.

Adrenergic beta-Antagonists↗
PubMed2001

Recent progress on the vibrating flow pump as a totally implantable ventricular assist device.

This study describes the present state of progress in the development of the vibrating flow pump (VFP) ventricular assist system. We have proceeded with development aiming at a totally implantable ventricular assist system with smaller size and lighter weight appropriate for Asians like the Japanese by increasing the drive frequency. An actuator is important for the development of the miniature sized and lightweight artificial heart. We applied a linear motor for the mechanical part at first. The step motor was applied after that. This form may be best if we want the lightweight small sized motor for an actuator. The cross slider form is applied at present. It succeeded in the miniaturization compared with the linear motor. In the VFP-type ventricular assist system, the blood contact parts are a central vibration tube with inflow and outflow chambers. We designed round diaphragms to prevent thrombus formation. In addition, we developed an energy transmission system for total implantation. The VFP creates a high frequency oscillated blood flow. It has a unique flow pattern. Brain blood flow increased although the total flow of the circulation did not change in the frequency of 25 to 30 Hz. The quantitative evaluation of the autonomic nerve function during the left heart assistance with an oscillated blood flow was carried out by spectral analysis. Some influences on an autonomic nerve were observed by the VFP left heart assistance. We will continue development research with the aim of clinical application.

Animals↗
PubMed2001

Successful management of secondary aortoesophageal fistula with graft infection.

A 60-year-old woman was transferred to our institution after massive hematemesis and the diagnosis of secondary aortoesophageal fistula was made. Five months previously, she had undergone graft replacement from the origin of the left subclavian artery to midthoracic aorta for chonic type B dissection. After an extraanatomic bypass was performed through a sternotomy, the infected thoracic aortic graft was resected through a left thoracotomy. She remained well without evidence of infection.

Aortic Dissection↗
PubMed2001

Establishment of a local cooling model against spinal cord ischemia representing prolonged induction of heat shock protein.

OBJECTIVES: Paraplegia is one of the serious complications of thoracoabdominal aortic operations. Regional hypothermia protects against spinal cord ischemia although the protective mechanism remains unknown. We attempted to create a simple model of local cooling under transient spinal cord ischemia and evaluated the effect using functional and histologic findings. METHODS: Male domesticated rabbits were divided into 3 groups: control, normothermic group (group N), and local hypothermic group (group H). A balloon catheter was used for spinal cord ischemia by abdominal aortic clamping. A cold pack attached to the lumbar region could lower the regional cord temperature initially. Neurologic function was evaluated by the Johnson score. Cell damage was analyzed by observing motor neurons with the use of hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated deoxy-uracil triphosphate biotin in situ nick end labeling (TUNEL), and immunoreactivity of heat shock protein. RESULTS: Physiologic estimation showed that local hypothermia improved the functional deficits (group N, 1.3 +/- 0.9; group H, 4.9 +/- 0.3; P =.0020). Seven days after reperfusion, there was a significant difference in the motor neuron numbers between groups N and H (group N, 7.2 +/- 1.9; group H, 20.4 +/- 3.2; P =.0090). The number of TUNEL-positive motor neurons was reduced significantly (group N, 7.2 +/- 2.4; group H, 1.0 +/- 0.7; P =.0082). Heat shock protein immunoreactivity was prolonged up to 2 days after reperfusion in the hypothermic group. CONCLUSIONS: These results suggest that local hypothermia extended the production of heat shock protein in spinal cord motor neurons after reperfusion and inhibited their apoptotic change.

Animals↗
PubMed2001

Suppression of T(h)1 cell activation and prevention of autoimmune diabetes in NOD mice by local expression of viral IL-10.

Insulin-dependent diabetes mellitus in the NOD mouse model is caused by the T cell-mediated autoimmune destruction of pancreatic beta cells. Viral IL-10 (vIL-10), encoded in the Epstein-Barr virus genome, shares many of the anti-inflammatory properties of cellular IL-10, but lacks its immunostimulatory properties. In the present study, we generated transgenic (Tg) NOD mice in which vIL-10 was produced exclusively in pancreatic islets and investigated the effect of vIL-10 on the development of diabetes. The accumulation of lymphocytes around islets was more prominent, but the invasive insulitis decreased in the vIL-10 Tg mice. The incidence of diabetes was markedly reduced in the vIL-10 Tg mice, in clear contrast to the accelerated diabetes seen in the murine IL-10 Tg NOD mice. IL-12p40 and IFN-gamma mRNA levels were decreased in pancreata of the vIL-10 Tg mice, although CD4 mRNA level was markedly increased. These results suggest that locally produced vIL-10 induced leukocyte migration, but inhibited the activation of T(h)1, probably through suppressing the production of IL-12. They indicate that vIL-10 may well be superior to cellular IL-10 in the treatment of autoimmune diabetes. The vIL-10 Tg NOD mice should provide a useful tool for understanding the differential action of vIL-10 versus cellular IL-10.

Animals↗
PubMed2001

Hyperbaric oxygen therapy given 30 minutes after spinal cord ischemia attenuates selective motor neuron death in rabbits.

OBJECTIVE: Spinal cord ischemia sometimes causes paraplegia because the spinal motor neuron cells are vulnerable to ischemia. Although various protective remedies for spinal cord injury have been reported, there have been few established clinical methods. Although hyperbaric oxygen (HBO) has been used clinically as a treatment for ischemia, the reason for its effectiveness is still uncertain because sufficient experimental data are lacking. DESIGN: Prospective, randomized, controlled study. SETTING: Experimental animal research laboratory in a university research center. SUBJECTS: Twenty-three Japanese white rabbits, weighing 2-3 kg. INTERVENTIONS: A modified rabbit spinal cord ischemia model of infrarenal aortic occlusion for 15 mins was employed. Rabbits were randomly assigned to four groups; the rabbits in group A did not undergo ischemic insults (n = 5). The rabbits in groups B and C underwent ischemic insult for 15 mins, followed by 1 hr of HBO treatment at 3 atm absolute with 100% oxygen at 30 mins (n = 6) or 6 hrs (n = 7) after reperfusion, respectively. The rabbits in group D underwent ischemic insult for 15 mins without HBO treatment (n = 5). MEASUREMENTS AND MAIN RESULTS: We observed neurologic functions for 14 days. The sections of the spinal cords were stained with hematoxylin and eosin, and the number of spinal motor neurons in ventral region was counted by light microscopy. All rabbits in groups A and B could stand, whereas all rabbits in groups C and D showed irreversible paraplegia on days 2 and 14 after reperfusion. Spinal motor neurons in ventral gray matter in groups C and D decreased significantly compared with those in groups A and B. CONCLUSIONS: HBO therapy shortly after ischemic insult had protective effects against ischemic spinal cord damage. However, delayed treatment with HBO did not change the prognosis.

Animals↗
PubMed2001

[Aortic root replacement after operation for the ascending aorta and/or aortic valve].

We reviewed ten cases who underwent aortic root replacement after operation for the ascending aorta and/or aortic valve. As initial operation, aortic valve replacement (AVR) was performed in five patients, replacement of the ascending aorta in two, original Bentall operation in two, and entry closure and suspension of the aortic valve in one. At reoperation, three patients were diagnosed as aneurysm of the ascending aorta, two were annulo-aortic ectasia, and one was acute aortic dissection, chronic dissecting aneusym, pseudoaneurysm of the ascending aorta, prosthetic valve endocarditis, and massive aortic regurgitation. Aortic root replacement was performed using mechanical valved composite graft in all cases. One patient who underwent repeat aortic root replacement for prosthetic valve endocarditis was died of septemia and ventricular fibrillation. Five patients had nine complications (two low output syndrome, respiratory failure and cerebral infarction, one gastrointestinal bleeding, septemia and ventricular fibrillation). In conclusion, aortic root replacement after operation for the ascending aorta and/or aortic valve was performed with acceptable morbidity and mortality.

Adult↗
PubMed2001

[Efficacy of modified ultrafiltration in reoperation for valvular disease].

We evaluated the efficacy of modified ultrafiltration (MUF) in reoperation for valvular disease. Fourteen patients were divide into two groups consisting of a control group (n = 6) and a MUF group (n = 8). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 31% in the MUF group (p < 0.05). The percentage of the increase in body weight after the operation in the MUF group was significantly less than that in the control group (3.3 +/- 3.1% vs 8.3 +/- 4.3%, p < 0.05). The PaO2/FIO2 after the operation in the MUF group was significantly higher than that in the control group (376 +/- 125 mmHg vs 242 +/- 79 mmHg, p < 0.05). The duration of mechanical ventilation in the MUF group was significantly less than that in the control group (1.1 +/- 1.1 days vs 5.3 +/- 3.3 days, p < 0.05). In conclusion, MUF is useful to hemoconcentrate, reduce postoperative body weight gain and promote early recovery of pulmonary function in reoperation for valvular disease.

Aged↗
PubMed2001

[Efficacy of modified ultrafiltration in coronary artery bypass grafting].

We evaluated the efficacy of modified ultrafiltration (MUF) in coronary artery bypass grafting. Twenty patients were divide into two groups consisting of a control group (n = 11) and a MUF group (n = 9). MUF was carried out for fifteen minutes immediately after the completion of cardiopulmonary bypass. The blood flow through the ultrafilter was 300 ml/min and about 1,200 ml of water was removed. The hematocrit elevated significantly from 25% to 30% in the MUF group (p < 0.01). Postoperative blood loss in the first 24 hours in the MUF group was significantly less than that in the control group (8 +/- 2 ml/kg vs 12 +/- 4 ml/kg, p < 0.01). There was no statistical difference in the percentage of the increase in body weight after the operation, inflammatory reaction and pulmonary function (A-a DO2, PaO2/FIO2 and duration of intubation) between two groups. In conclusion, MUF is useful to hemoconcentrate and reduce postoperative blood loss in coronary artery bypass grafting.

Aged↗
PubMed2000

Altered distribution and density of myocardial beta-adrenoceptors during acute rejection in rats.

BACKGROUND: A better understanding of altered expression of myocardial beta-adrenoceptors can facilitate the diagnosis of early and late acute rejection of heart transplants. METHODS: We submitted rats to heterotopic heart transplantation (iso- and allografts) of which one of each were treated with or without cyclosporin A for 4, 7, and 14 days (n=5, respectively). The cardiac sections were incubated in vitro with [3H]CGP 12177, or the hearts were labeled in vivo by intravenous injection of [3H]CGP 12177. Autoradiographic images of both were analyzed digitally and compared with histologic findings. RESULTS: Beta-adrenoceptor distribution in native hearts and isografts was homogeneous, but highly differential distribution and density in allografts were observed in the left and right ventricular walls and in the interventricular septum despite treatment with cyclosporin A. High-density areas in the progressive course of acute rejection are commonly associated with up-regulation of beta-adrenoceptors in apparently viable myocytes, although histologic findings confirmed many infiltrating mononuclear cells. Low-density areas, which were identified in the right and left ventricular walls as early as 4 days after transplantation, correlated with derangement of myocytes, which was suggestive of early acute rejection. The images obtained by in vivo technique were comparable to in vitro images. CONCLUSIONS: The alteration of beta-adrenoceptor expression in allografts showed a close relationship with the severity of acute rejection, and the techniques employed in this model were useful in our study of the rejection process and in detecting early and late acute rejection in the rat.

Acute Disease↗