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Biomedical subjects

Hiromi Kurosawa

Publications and source records attributed to Hiromi Kurosawa.

At least 19 recordsLinked to original sources
PubMed2007

A novel synthetic tissue-adhesive hydrogel using a crosslinkable polymeric micelle.

We prepared a novel tissue-adhesive hydrogel by using a polymeric micelle consisting of an aldehyde-terminated poly(ethylene glycol)-poly(D,L-lactide) (PEG-PLA) block polymer. A Schiff base is chemically formed between the amino groups in a polyallylamine and the aldehyde groups on the surface of polymeric micelles. The hydrogel was formed in approximately 2 s when the polymeric micelle solution and polyallylamine solution are mixed in vitro. The hydrogel was rapidly formed in vivo, and it adhered to a tissue surface. Our novel tissue-adhesive hydrogel creates no risk of infectious contaminations, because it consists of only synthetic materials. Further, PEG and PLA are known to be biocompatible and noncytotoxic. The results obtained in the present study show that a hydrogel prepared by the formation of a Schiff base between aldehyde and amine groups will potentially address the need for novel tissue-adhesive materials.

Cross-Linking Reagents↗
PubMed2007

Hemodilutional anemia impairs neurologic outcome after cardiopulmonary bypass in a piglet model.

OBJECTIVES: The effect of hemodilution on neurologic outcome after cardiopulmonary bypass remains unclear. We studied the influences of hematocrit on cerebral oxygenation and neuropathologic outcome in a piglet model. METHODS: Eleven piglets (9.3 +/- 1.1 kg) were randomized into 2 groups. Five piglets (group H) received a total blood prime resulting in a high hematocrit (33.0% +/- 2.3%), and 6 piglets (group L) received a crystalloid prime resulting in a low hematocrit (14.0% +/- 3.2%). Both groups underwent 90 minutes of moderate hypothermic cardiopulmonary bypass (28 degrees C) with alpha-stat strategy. Cerebral oxygenation was monitored by near-infrared spectroscopy. Group L received a blood transfusion immediately after cardiopulmonary bypass to reach the postoperative target hematocrit of 30%. The brain was fixed in situ 6 hours after weaning from cardiopulmonary bypass, and a histologic score for neurologic injury was assessed. RESULTS: There were no significant differences in arterial blood gas analyses throughout the experiment between the groups. Mean arterial pressure, mixed venous oxygen saturation, and heart rate were significantly higher in group H compared with group L during hypothermia. Oxyhemoglobin and total hemoglobin signals detected by near-infrared spectroscopy were significantly lower in group L (analysis of variance, P < .0001), although the tissue oxygenation index was not different during cardiopulmonary bypass. Group L showed a poorer histologic score compared with group H (P = .0071). CONCLUSIONS: Excessive hemodilution, such as a hematocrit of less than 15%, may be associated with a high incidence of neurologic injury. Further studies are required to determine the safety limits of hematocrit during pediatric cardiopulmonary bypass.

Anemia↗
PubMed2006

What is operative mortality? Defining death in a surgical registry database: a report of the STS Congenital Database Taskforce and the Joint EACTS-STS Congenital Database Committee.

The most concrete and universal outcome measure used in databases, whether governmental, professional society, research, or third-party payer, is operative mortality. To assure congruous data entry by multiple users of The Society of Thoracic Surgeons and the European Association for Cardiothoracic Surgery congenital heart surgery databases, operative mortality must be clearly defined. Traditionally, operative mortality has been defined as any death, regardless of cause, occurring (1) within 30 days after surgery in or out of the hospital, and (2) after 30 days during the same hospitalization subsequent to the operation. Differing hospital practices result in problems in use of the latter part of the definition (eg, the pediatric hospital that provides longer-term care will have higher mortality rates than one which transfers patients to another institution for such care). In addition, because of the significant number of pediatric multiple operation hospitalizations, issues of assignment of mortality to a specific operation within the hospitalization, calculation of operative mortality rates (operation based vs patient admission based), and discharge other than to home must be addressed and defined. We propose refinements to the definition of operative mortality which specifically meet the needs of our professional societies' multi-institutional registry databases, and at the same time are relevant and appropriate with respect to the goals and purposes of administrative databases, government agencies, and the general public.

Cardiac Surgical Procedures↗
PubMed2006

The nomenclature, definition and classification of hypoplastic left heart syndrome.

The hypoplastic left heart syndrome encompasses a spectrum of cardiac malformations that are characterized by significant underdevelopment of the components of the left heart and the aorta, including the left ventricular cavity and mass. At the severe end of the spectrum is found the combination of aortic and mitral atresia, when the left ventricle can be close to non-existent. At the mild end are the patients with hypoplasia of the aortic and mitral valves, but without intrinsic valvar stenosis or atresia, and milder degrees of left ventricular hypoplasia. Although the majority of the patients are suitable only for functionally univentricular repair, a small minority may be candidates for biventricular repair. The nature of the syndrome was a topic for discussion at the second meeting of the International Working Group for Mapping and Coding of Nomenclatures for Paediatric and Congenital Heart Disease, the Nomenclature Working Group, held in Montreal, Canada, over the period January 17 through 19, 2003. Subsequent to these discussions, the Nomenclature Working Group was able to create a bidirectional crossmap between the nomenclature initially produced jointly on behalf of the European Association for Cardio-Thoracic Surgery and the Society of Thoracic Surgeons, and the alternative nomenclature developed on behalf of the Association for European Paediatric Cardiology. This process is a part of the overall efforts of the Nomenclature Working Group to create a comprehensive and all-inclusive international system of nomenclature for paediatric and congenital cardiac disease, the International Paediatric and Congenital Cardiac Code. In this review, we discuss the evolution of nomenclature and surgical treatment for the spectrum of lesions making up the hypoplastic left heart syndrome and its related malformations. We also present the crossmap of the associated terms for diagnoses and procedures, as recently completed by the Nomenclature Working Group.

Diagnosis, Differential↗
PubMed2006

Video-assisted thoracoscopy to treat atrial tachycardia arising from left atrial appendage.

A 17-year-old male with tachycardia-induced cardiomyopathy presented with persistent, drug-resistant atrial tachycardia (AT). An electrophysiological study suggested focal abnormal automaticity, and localized the AT origin to the left atrial appendage. Radiofrequency catheter ablation at the site of the earliest endocardial activation during AT failed. A minimally invasive, video-assisted thoracoscopic (VAT) atrial appendectomy terminated the AT and restored left ventricular contractility. The patient remained free of AT and normal left ventricular function was maintained over a 24-month follow-up period. To our knowledge, we are the first to use VAT atrial appendectomy to treat focal AT.

Adolescent↗
PubMed2005

Survival benefit of exclusive use of in situ arterial conduits over combined use of arterial and vein grafts for multiple coronary artery bypass grafting.

BACKGROUND: The purpose of this study was to evaluate mortality after coronary artery bypass grafting (CABG) comparing the use of only in situ arterial grafts with the use of arterial and venous conduits. METHODS AND RESULTS: From April 1985 to March 1999, 1159 patients with multivessel disease underwent elective, isolated, primary, multiple CABG with at least one in situ arterial conduit. Patients who were on chronic dialysis, had active malignant disease, or had free arterial conduits were excluded. The long-term results were compared between 532 patients who had CABG using only in situ arterial conduits (group A; mean follow-up, 7.8 years) and 627 patients who underwent CABG using in situ arterial conduits and saphenous vein grafts (group B; mean follow-up, 10.3 years). Actuarial survival and freedom from cardiac death were determined by the Kaplan-Meier method. Propensity score was included in the Cox multivariable regression model for adjustment of selection bias. Survival at 10 years after surgery was 81.4% in group A and 76.9% in group B (P=0.11). Freedom from cardiac death at 10 years was 93.4% in group A and 90.4% in group B. Hazard ratio for cardiac death was significantly lower in group A (0.61; 95% confidence interval, 0.38 to 1.00; P=0.05). CONCLUSIONS: Our data suggest that the exclusive use of in situ arterial grafts in CABG achieves significantly better long-term survival compared with combined use of arterial and vein grafts.

Aged↗
PubMed2005

Successful application of pulmonary arterial patch for coronary angioplasty late after arterial switch operation.

Pulmonary artery is infrequently utilized as a material for coronary patch angioplasty in children. We applied a pulmonary arterial patch for coronary angioplasty on an 8-year-old boy with total occlusion of the left main coronary artery late after an arterial switch operation. The pulmonary arterial patch was easy to handle and the immediate result after the operation was satisfactory.

Angioplasty↗
PubMed2005

Long-term assessment of mitral valve reconstruction with resection of the leaflets: triangular and quadrangular resection.

BACKGROUND: The procedure of quadrangular resection and suture for prolapsed posterior leaflet of the mitral valve is a reliable and reproducible method that achieves excellent long-term results. However, triangular resection and suture of a prolapsed anterior leaflet is not widely supported and different techniques have been advocated. The aim of this study was to review our experience of mitral valve repair in which resection of the anterior and/or posterior leaflets was performed. METHODS: Between October 1991 and September 2003, 105 patients with mitral regurgitation underwent mitral valve reconstruction with leaflet resection, including 55 patients with quadrangular resection of the posterior leaflet (P), 32 patients with triangular resection of the anterior leaflet (A), and 18 patients with resection of both leaflets (A+P). RESULTS: The mean follow-up period was 63.6 (1 to 139) months. Reoperation was required in 2 patients, each after resection of the anterior or posterior leaflet. The freedom from reoperation rates at 10 years in 93% +/- 5% of patients after triangular resection of the anterior leaflet, 96% +/- 3% after quadrangular resection of the posterior leaflet, and 100% after resection of both leaflets. There were no significant differences of survival or risk of reoperation among these three groups. The postoperative mitral valve area was significantly smaller than the preoperative area in all three groups, but remained large enough (A: 2.84 +/- 1.07; P: 2.6 +/- 0.87; A+P: 3.09 +/- 1.20 cm2) for adequate valve function. CONCLUSIONS: Triangular resection of a prolapsed anterior mitral leaflet is a reliable, reproducible, and durable procedure, like quadrangular resection of a prolapsed posterior leaflet.

Actuarial Analysis↗
PubMed2005

Midterm results of Manouguian double valve replacement: comparison with standard double valve replacement.

OBJECTIVE: Surgical strategies for patients who have a small aortic annulus associated with a small mitral annulus remain controversial. The objective of this study was to assess the validity of the Manouguian procedure for double valve replacement with patch enlargement of the annuli. METHODS: We reviewed 57 consecutive patients who underwent double valve replacement for combined aortic and mitral disease between September 1991 and October 2000. Thirty patients underwent the Manouguian procedure with patch enlargement of the aortic and mitral annuli, and the other 27 patients had standard double valve replacement. The Manouguian procedure was selected for a small aortic annulus of less than 21 mm in diameter. The patients were followed for a median of 7.5 years. Results of echocardiography and the dobutamine stress test were compared postoperatively. RESULTS: Double valve replacement with the Manouguian procedure did not increase the early or midterm mortality because the survival (including operative death) at 8 years was 83% in the Manouguian group and 84% in the double valve replacement group (P = .82). The event-free rate at 8 years was 79% in the Manouguian group and 84% in the double valve replacement group (P = .6). The prostheses implanted at the aortic and mitral positions were smaller in the Manouguian group, even after annular enlargement. However, the transprosthetic gradient across the aortic valve evaluated by means of dobutamine stress echocardiography did not differ between the 2 groups, possibly because of a smaller body surface area in the Manouguian group. CONCLUSIONS: The Manouguian patch enlargement procedure is useful during double valve replacement when associated with the problem of small-valve annuli.

Adult↗
PubMed2005

The tissue-engineered vascular graft using bone marrow without culture.

OBJECTIVE: To overcome the shortcomings of current vascular grafts, tissue-engineering methods have been applied to cardiovascular regions. We previously reported the creation of a tissue-engineered vascular graft by using vascular mixed cells. However, the cost and manpower for harvesting and culturing the cells was too burdensome. To overcome these drawbacks, we have developed a new method for creating a tissue-engineered vascular graft by using bone marrow cells, which can be obtained easily and used immediately, without cell culture. METHODS: Biodegradable polymers seeded with different types of cells (group V, cultured venous cells; group B, bone marrow cells without culture; and group C, non-cell-seeded graft [as control]) were implanted into the inferior venae cavae of dogs. The grafts were explanted at 4 weeks and assessed histologically and biochemically. RESULTS: In the histologic examination, a regular layer of Masson-staining collagen fiber and a layer of factor VII-stained endothelial and ant-alpha-smooth muscle cell antigen-immunoreactive cells stained in groups V and B like native vascular tissue, whereas no such stained regular lining was detected in group C. A 4-hydroxyproline assay in group C showed significantly lower levels than in groups V and B or native tissue ( P < .05). The DNA content of the tissue-engineered vascular graft tended to be higher in group C than in groups V and B or in native tissue. CONCLUSIONS: In the creation of tissue-engineered vascular grafts, the method of using bone marrow cells seems to be useful and superior to that of using vascular cells because bone marrow cells can be used directly, without culture.

Animals↗
PubMed2005

Midterm clinical result of tissue-engineered vascular autografts seeded with autologous bone marrow cells.

OBJECTIVE: Prosthetic and bioprosthetic materials currently in use lack growth potential and therefore must be repeatedly replaced in pediatric patients as they grow. Tissue engineering is a new discipline that offers the potential for creating replacement structures from autologous cells and biodegradable polymer scaffolds. In May 2000, we initiated clinical application of tissue-engineered vascular grafts seeded with cultured cells. However, cell culturing is time-consuming, and xenoserum must be used. To overcome these disadvantages, we began to use bone marrow cells, readily available on the day of surgery, as a cell source. The aim of the study was to assess the safety and feasibility of this technique for creating vascular tissue under low-pressure systems such as pulmonary artery or venous pressure. METHODS: Since September 2001, tissue-engineered grafts seeded with autologous bone marrow cells have been implanted in 42 patients. The patients or their parents were fully informed and had given consent to the procedure. A 5-mL/kg specimen of bone marrow was aspirated with the patient under general anesthesia before the skin incision. The polymer tube serving as a scaffold for the cells was composed of a copolymer of l -lactide and -caprolactone (50:50). This copolymer is degraded by hydrolysis. The matrix is more than 80% porous, and the diameter of each pore is 20 to 100 microm. Polyglycolic acid woven fabric with a thickness of 0.5 mm was used for reinforcement. Twenty-three tissue-engineered conduits (grafts for extracardiac total cavopulmonary connection) and 19 tissue-engineered patches were used for the repair of congenital heart defects. The patients' ages ranged from 1 to 24 years (median 5.5 years). All patients underwent a catheterization study, computed tomographic scan, or both, for evaluation after the operation. The patients received anticoagulation therapy for 3 to 6 months after surgery. RESULTS: Mean follow-up after surgery was 490 +/- 276 days (1.3-31.6 months, median 16.7 months). There were no complications such as thrombosis, stenosis, or obstruction of the tissue-engineered autografts. One late death at 3 months after total cavopulmonary connection was noted in patient with hypoplastic left heart syndrome; this was unrelated to the tissue-engineered graft function. There was no evidence of aneurysm formation or calcification on cineangiography or computed tomography. All tube grafts were patent, and the diameter of the tube graft increased with time (110% +/- 7 % of the implanted size). CONCLUSION: Biodegradable conduits or patches seeded with autologous bone marrow cells showed normal function (good patency to a maximum follow-up of 32 months). As living tissues, these vascular structures may have the potential for growth, repair, and remodeling. The tissue-engineering approach may provide an important alternative to the use of prosthetic materials in the field of pediatric cardiovascular surgery. Longer follow-up is necessary to confirm the durability of this approach.

Adolescent↗
PubMed2004

Pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, reduces delayed neuronal death following transient forebrain ischemia in the adult rat hippocampus.

Recent evidence indicates that statins have beneficial effects on the brain in the ischemic condition. However, there is a lack of studies related to the effect of statins on delayed neuronal death. We investigated the effect of prophylactic therapy with pravastatin on delayed neuronal death in the rat hippocampus. The rats were given a daily dose of 20 mg/kg of pravastatin orally for 14 days. Transient forebrain ischemia was induced by the four-vessel occlusion method. Three days after ischemia, surviving neurons of the hippocampal CA1 subfield were counted. Our results demonstrated that prophylactic statin treatment significantly reduced delayed neuronal death after transient forebrain ischemia. Our findings suggest that prophylactic statin treatment may be useful in preventing functional neurological disorders after transient cerebral ischemic insult.

Animals↗