Search PubMed⌕ Search

Biomedical subjects

H Koyanagi

Publications and source records attributed to H Koyanagi.

At least 19 recordsLinked to original sources
PubMed1998

Inhibitory effect of Multiglycosidorum tripterygii on coronary arteriosclerosis after heart transplantation.

BACKGROUND: Graft coronary arteriosclerosis (GCA) is the major limiting factor for long-term survival after heart transplantation. In this study, we investigated the effect of Multiglycosidorum tripterygii (MT) on GCA and platelet-derived growth factor A (PDGF-A) mRNA expression of transplanted hearts. METHODS: Two groups of Lewis rats (n=7/group) underwent heterotopic heart transplantation from Wistar-King donors and were treated with either cyclosporine (CsA;10 mg/kg/day) or MT (30 mg/kg/ day). Histological evaluations of rejection and coronary arteriosclerosis, as well as Northern blot analysis on graft PDGF-A mRNA expression were made 60 days after transplantation. RESULTS: Morphometric results indicated no significant difference in rejection between the CsA- and MT-treated groups. However, the extent of GCA in the MT-treated group was significantly less than that seen in the CsA-treated group (P<0.01). The expression of PDGF-A mRNA of cardiac allograft was also significantly suppressed in the MT-treated group when compared with the CsA-treated group (P<0.01). CONCLUSION: MT is superior to CsA in preventing graft coronary arteriosclerosis, and this efficacy is probably associated with the depressed expression of graft PDGF-A mRNA in the MT-treated group.

Animals↗
PubMed1998

Effectiveness of ischemic preconditioning on long-term myocardial preservation.

BACKGROUND: This study was designed to assess whether the protective effect of ischemic preconditioning can be adapted for myocardium undergoing 6 hr of ischemia. METHODS: Eighteen isolated rat hearts were perfused with oxygen-bicarbonated Krebs-Henseleit buffer in the Langendorff mode for 35 min (group A, controls) or perfused in the Langendorff apparatus for 20 min, followed by 5 min of global normothermic ischemia and 10 min of buffer perfusion (group B, preconditioning) or followed by two cycles of 2.5 min of global normothermic ischemia plus 5 min of buffer perfusion (group C, preconditioning). The hearts were then arrested and preserved for 6 hr with Bretschneider's histidine-tryptophan-potassium cardioplegic solution at 4 degrees C, followed by 30 min of reperfusion. Recovery of cardiac function, postischemic enzyme leakage, and intracellular calcium concentration were compared. RESULTS: After 6 hr of ischemia, the hearts that underwent preconditioning in groups B and C showed better recovery of left ventricular developed pressure (P<0.05), a lower end-diastolic pressure level (P<0.05), less leakage of creatine kinase, and a lower intracellular calcium concentration than those in group A. There were no statistical differences in the rate of recovery of coronary flow. CONCLUSIONS: Our study demonstrated that ischemic preconditioning improves myocardial functional recovery after 6 hr of hypothermic preservation in the isolated rat heart. Preconditioning might be useful for preserving the heart against long-term ischemia/reperfusion injury.

Animals↗
PubMed1998

Association between the degree of platelet-derived growth factor-A chain mRNA expression and coronary arteriosclerosis in the transplanted heart.

Although intimal and medial proliferation of smooth muscle cells is recognized as one of the key mechanisms in the development of graft coronary arteriosclerosis, the role of platelet-derived growth factor (PDGF) in this process is still uncertain, because of the undetermined pathogenesis of graft coronary arteriosclerosis (GCA). In the present study, the correlation between the extent of GCA and the degree of PDGF-A chain expression in cardiac grafts was investigated in 21 rats with GCA of varying extent. Lewis rats underwent heterotopic heart transplantation from Wistar King donors and were treated with cyclosporine A (10 mg/kg/day) (n = 7), 15-deoxyspergualin (5 mg/kg/day) (n = 7), or Multiglycosidorum tripterygii (MT) (30 mg/kg/day) (n = 7). Histological evaluations of coronary arteriosclerosis, as well as Northern blot analysis of graft PDGF-A chain expression were made, 60 days after transplantation. Graft coronary arteriosclerosis of varying extent was observed among the 21 transplanted hearts. Significant correlations were found between the PDGF-A chain mRNA expression of cardiac allograft and the grade of arterial intimal thickening (Spearman's r = 0.76, P < 0.005) as well as the incidence of diseased vessels (r = 0.82, P < 0.001). The PDGF-A chain mRNA expression of the cardiac allograft is associated with the extent of GCA, indicating that PDGF-A plays an important role in the development of GCA.

Animals↗
PubMed1998

[A case of coronary artery bypass grafting for effort angina in a patient with post skin grafting for an extramammary Paget's disease].

The extramammary Paget's disease of anogenital area is rare, and is seen as a precancerous lesion or carcinoma in situ. In most cases, surgical treatment including dissection of regional lymph nodes, skin resection and grafting should be considered first. A 74-year-old male suffered from effort angina and underwent triple coronary artery bypass grafting (CABG) including saphenous vein graft (SVG) harvested from right lower leg. Five years previously he underwent skin grafting for extramammary Paget's disease of both inguinal areas and the perineal area. The postoperative course was uneventful and he was discharged 23 days after the CABG operation. Extramammary Paget's disease is localized in epidermis for years and there has been no report of direct invasion into vessels. Therefore, there appears to be no reason not to use an SVG if there is no luminal thrombus or occlusion.

Aged↗
PubMed1998

[Coronary artery bypass grafting for cases which were not amenable to preoperative left ventriculogram].

We evaluated the coronary artery bypass grafting (CABG) for the cases which were not amenable to preoperative left ventriculograms (LVG). Between June 1970 and March 1996, we had 2045 cases of isolated CABG, and 52 cases of which were not amenable to preoperative LVG. The reasons of no preoperative LVG were during cardiopulmonary resuscitation (CPR) in 4 cases, shock state in 14, NYHA class IV or CCS class IV in 26, angina attack after coronary angiography in 3 and so on. Preoperative diagnoses were acute myocardial infarction in 28, angina after infarction in 13, unstable angina in 9 and effort angina in 2. Preoperative conditions were reoperation in 6, insertion of intra-aortic balloon pumping in 46, chronic renal failure in 15 (hemodialysis in 4) and arrhythmia (VT or Vf) in 12. Concerning the coronary lesions, left main trunk and triple vessel diseases occupied 75% of all. Surgical deaths were 5 cases (9.6%) and hospital deaths were 4 cases (7.7%). The all cases which needed preoperative CPR were died with brain injury. The result of the cases which were not amenable to preoperative LVG were worse than the cases with ischemic cardiomyopathies. In conclusion, no preoperative LVG is one of the highest risk factors of all.

Adult↗
PubMed1998

[Postoperative complications after coronary bypass operations in patients with pulmonary impairment].

The postoperative courses of 112 patients with pulmonary disease (59 with obstructive disease = Group 0, 38 with restrictive disease = Group R and 15 with mixed disease = Group M) who underwent elective coronary artery bypass grafting were retrospectively reviewed. Preoperative pulmonary function test (percentage of vital capacity = %VC and percentage of forced expiratory volume at 1 second = FEV1.0%) of these group showed typical abnormal values, and velocity ratio of 50% and 25% of maximum expiratory flow volume (V50/V25) of each groups were measured abnormal values (3.99 +/- 1.44 of Group O, 4.26 +/- 1.42 of Group R and 3.74 +/- 1.82 of Group M). The our strategy for these groups were a). Using skeletonization method for harvesting internal mammary artery (IMA) b) Take care not to injure the phrenic nerve and open the pleural cavity as surgical techniques (Harvesting IMA) and c) Administration of theophylline derivatives and corticosteroids to prevent bronchospasm d) Administration of concentrated serum albumin and diuretics to prevent pulmonary edema as therapeutic measures. The length of stay in the intensive care unit and ventilation time of each groups were not significantly longer. Patients of group M had more respiratory complications (atelectasis, pleural effusion, pneumothrax, bronchospasm, and pneumonia) than did patients of group R (p < 0.05), but did not more nonpulmonary complications and hospital deaths. The four in hospital deaths (2 with group O, 1 with group R and 1 with group M) were not directly related to pulmonary complications. Thus, result of CABG in patients with pulmonary impairment definitely proved to be satisfactory by our strategy, but mixed pulmonary diseased significantly had more pulmonary complications.

Cardiac Surgical Procedures↗
PubMed1998

Should the aortic valve homograft be recryopreserved?

BACKGROUND: The number of homograft donors is limited and the once-thawed homograft may be unsuitable for the recipient and obliged to be wasted. The purpose of this study was to investigate the possibility of recryopreserving and using the once-thawed homograft for another patient. METHODS: Canine aortic valve leaflets were frozen to -80 degrees C by a programmed freezer, stored in liquid nitrogen, and thawed after 1 week. A subgroup of leaflets was left at 4 degrees C for 15 minutes, re-cryopreserved, and thawed after 1 week. Pathologic and flow cytometric evaluations were performed. RESULTS: After thawing, by pathology, alignment of the fibers was acceptably maintained but the membrane and cytoplasm of the fibroblast were damaged. These findings were not significantly aggravated even after rethawing. By flow cytometry, fibroblast viability was 90.7%+/-1.7% immediately after thawing, 87.6%+/-1.0% after thawing for 15 minutes at 4 degrees C, 63.7%+/-2.7% during refreezing at 0 degrees C, and 39.4%+/-4.3% after rethawing. CONCLUSIONS: From the standpoint of fibroblast viability, it is not possible to recryopreserve the once-cryopreserved and thawed aortic valve homograft.

Animals↗
PubMed1998

Models of lineage switching in hematopoietic development: a new myeloid-committed eosinophil cell line (YJ) demonstrates trilineage potential.

A new human leukemia cell line with an eosinophilic phenotype, designated YJ, was established from the peripheral blood cells of a patient with chronic myelomonocytic leukemia (CMMoL) with eosinophilia. When cultured in RPMI 1640 medium containing 10% fetal bovine serum, most YJ cells were myeloblastoid with a small number of the cells having eosinophilic granules. Cell surface markers in the YJ cells were positive for CD33 and were negative for CD34, CD16 and CD23. The eosinophilic characteristics of YJ cells were confirmed by histochemical staining with Fast-Green/Neutral-Red and by the expression of mRNAs for eosinophil-associated granule proteins, eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), eosinophil peroxidase (EPO), and major basic protein (MBP), and for the Charcot-Leyden crystal (CLC) protein. The YJ cells could be induced towards monocytic differentiation by stimulation with phorbol 12-myristate 13-acetate (PMA). The monocytic characteristics of YJ cells treated with PMA were confirmed by morphological analysis with alpha-naphthyl butyrate esterase staining, by CD14 expression, and by increased expression of Egr-1 mRNA. Furthermore, YJ cells could be differentiated towards the neutrophil lineage by stimulation with all-trans retinoic acid (RA). YJ cells treated in vitro with 2 microM RA differentiated into metamyelocytes and band neutrophils, and increased the number of nitroblue tetrazolium (NBT)-positive cells and increased gp91phox mRNA expression. Thus, the YJ cell line exhibited eosinophilic characteristics, but was able to differentiate to the monocytic or neutrophilic lineages in response to PMA or RA, respectively. The expression of genes for transcription factors involved in myeloid differentiation was evaluated by Northern blot analysis. Increased expression of Egr-1 was observed with macrophage differentiation. In contrast, increased expressions of C/EBPbeta and MZF-1 mRNA occurred with neutrophilic differentiation. The YJ cell line should be useful for elucidating the molecular mechanisms governing lineage switching from the eosinophil to monocytic or neutrophil lineages.

Antigens, Surface↗
PubMed1998

Effect of a balanced biventricular bypass system on left ventricular energies.

Left dominant biventricular failure is a common type of heart failure after cardiac surgery. We developed a biventricular bypass (BVB) system for treatment of postcardiotomy ventricular failure, and we previously reported that the clinical results of the BVB system were superior to those obtained with venoarterial bypass (VAB). The purpose of this study was to evaluate the effect of the BVB system on left ventricular (LV) performance in comparison to that of VAB by means of the LV pressure-volume relationship (PVR). Eight adult mongrel dogs (14-21 kg) underwent VAB with right atrial and aortic cannulation. Left atrial cannulation was added for BVB, and both atrial drainage tubes were joined with a Y-shaped connector. The bypass flow was maintained at half of the baseline cardiac output (0.7-1.0 L/min), and the hemodynamic parameters were monitored. A high fidelity microtip catheter and a conductance catheter were used to evaluate LV function. The slope of the LV end-systolic pressure-volume relation (Emax), the slope of the LV end-systolic pressure-stroke-volume relation (Ea), the LV stroke work (SW), LV potential energy (PE), LV pressure-volume area (PVA), the slope of the SW end-diastolic volume relation (PRSW), and an index of the LV energizing charge (ratio of PE/PVA) were assessed during transient occlusion of the inferior vena cava. LV contractility (Emax) showed no significant change during each experiment. Standardized LV work (PRSW) was reduced by BVB in comparison to the baseline and in comparison to VAB. The rate of LV energy charge (PE/PVA) significantly increased only during BVB. These results suggested that the BVB system might be an effective circulatory support for reducing LV work and improving the LV energizing charge in patients with severe heart failure after cardiac operation.

Animals↗
PubMed1998

Mechanical circulatory support for severe heart failure after operation.

To evaluate the clinical results of circulatory support for severe heart failure after operation, we examined 62 patients (39 males and 23 females) who underwent circulatory support for postoperative heart failure from 1984 to 1996. Their ages ranged from 22 to 78 (mean 52) years. In 62 patients, 35 had valvular, 25 had ischemic, and 2 had congenital heart disease. Postoperation, 29 patients underwent venoarterial bypass (VAB), 20 had biventricular bypass (BVB), and 8 had left ventricular bypass (LVB). The remaining 5 patients received a pulsatile left ventricular assist device (LVAD). The weaning and discharge rates of the patients by type of support were 51.7% and 31.0% with VAB, 75.0% and 55.0% with BVB, 87.5% and 37.5% with LVB, and 60.0% and 40.0% with LVAD, respectively. The complete results of this series (64.5% weaning rate and 40.3% discharge rate) were acceptable.

Adult↗
PubMed1998

Afterload-dependent flow fluctuation of centrifugal pump: should it be actively fixed?

To evaluate the clinical meaning and effects of afterload-dependent flow fluctuation in a centrifugal pump, concomitant measurement of flow rate and mixed venous oxygen saturation (SVO2) was performed in 5 cases of open heart surgery in which the patients underwent cardiopulmonary bypass (CPB) with the Terumo Capiox centrifugal pump. Continuous measurement of SVO2 using the 3M CDI System 100 was performed with a disposable cuvette incorporated into the drainage circuit. After the target flow rate of 2.4 L/min/m2 was obtained under a nonbeating condition, the pump rotational speed was fixed. During the cooling and low temperature period, SVO2 decreased as the flow rate spontaneously decreased but still stayed around 80% even with a 15-20% decrease in blood flow rate. This indicates that a luxury perfusion condition is ensured as long as the body temperature is kept low. In contrast, during the rewarming period, SVO2 decreased to around 70-75% despite a 15-25% spontaneous increase in flow rate. Although this level of SVO2 still indicates adequate systemic perfusion, there is a possibility of regional hypoperfusion in patients with such conditions as cerebrovascular disease. In conclusion, although diligent adjustment of the physiological fluctuating flow rate in the centrifugal pump seems unnecessary during conventional open heart surgery, manual control may be necessary especially during the rewarming period, normothermic surgery, or circulatory assist for shocked patients. From this study, we also conclude that the major benefit of the afterload-independent autoflow control system of the centrifugal pump is the improvement of safety in terms of the fixed reservoir level and the handling of cardiopulmonary bypass.

Blood Flow Velocity↗
PubMed1998

Fine trabecularized carbon: ideal material and texture for percutaneous device system of permanent left ventricular assist device.

The development of a percutaneous artificial internal organ system requires a reliable biocompatible connection between the external environment and the inside of the human body. Such is necessary for the success of a permanent left ventricular assist device. However, the search for a satisfactory interface at the epidermal level has proven to be difficult. Carbon has been proposed for this application, but its texture does not typically promote ingrowth from surrounding tissue. We have therefore employed a new processing method to produce a fine trabecularized carbon implant. The method for preparing the implant involves infiltrating low temperature pyrolytic carbon into the surface of a carbon core which is wrapped with carbon fabric. This results in a tightly woven porous structure of carbon (carbon fiber diameter: 35-50 microm, maximal pore size >200 microm) with gradually increasing porosity from 15-75%. We implanted test samples percutaneously in a calf for in vivo histological evaluation. Thirty days after implantation epidermal downgrowth was minimal. Microscopic analysis revealed that a thin fibrous capsule surrounded the implant, and mature connective tissue with accompanying blood vessels filled the pores of the fine trabecularized carbon layer. From these results we suggest that fine trabecularized carbon is ideally suited for a percutaneous device system in a permanent left ventricular assist device.

Animals↗
PubMed1998

An implantable centrifugal blood pump with a recirculating purge system (Cool-Seal system).

A compact centrifugal blood pump has been developed as an implantable left ventricular assist system. The impeller diameter is 40 mm, and pump dimensions are 55 x 64 mm. This first prototype, fabricated from titanium alloy, resulted in a pump weight of 400 g including a brushless DC motor. The weight of a second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon (DLC) to improve blood compatibility. Flow rates of over 7 L/min against 100 mm Hg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system (Cool-Seal) is used for the shaft seal. In this seal system, the seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. Purge fluid is continuously purified and sterilized by an ultrafiltration unit which is incorporated in the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular (LV) apex descending aorta bypass was performed utilizing an expanded polytetrafluoroethylene (ePTFE) vascular graft with the pump placed in the left thoracic cavity. In 2 in vivo experiments, the pump flow rate was maintained at 5-9 L/min, and pump power consumption remained stable at 9-10 W. All plasma free Hb levels were measured at less than 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (<0.5 ml/day). In both calves, the pumps demonstrated trouble free continuous function over 6 month (200 days and 222 days).

Alloys↗
PubMed1998

Effect of pressure-flow relationship of centrifugal pump on in vivo hemodynamics: a consideration for design.

We have been developing centrifugal pumps for an implantable left ventricular assist device. We manufactured 2 prototype centrifugal pumps (PI, PII). These two have similar designs except for the PII having a volute casing and a large output port. To determine the differences in the hydraulic characteristics between the PI and PII, we carried out in vitro and in vivo experiments. In vitro study showed that the PII had a shallower H-Q curve than that of the PI, and the PII required a pump speed faster than the PI for the same flow rate and pressure head. On the other hand, in vivo study showed that the PII demonstrated a flow pulsatility greater than that of the PI at 1,900 rpm and 8 L/min although no significant change was observed at low pump speeds (< or = 1,500 rpm). This greater pulsatility consisted of a large discharge according to the small differential pressure during the systolic phase and a small discharge according to the large differential pressure during the diastolic phase. In contrast, the PI, having the steeper H-Q curve, showed a small discharge in the systolic phase and a large discharge in the diastolic phase. These results showed that pulsatility synchronized with the native heart beating depended on the slope of the H-Q curve. As a result, the slope of the H-Q curve is important to determine the component of pulsatility synchronized with native cardiac output. Regarding the slope of the H-Q curve, a pump having a volute casing and a large outlet port demonstrates a shallow slope in the H-Q curve. In conclusion, we suggest that a centrifugal pump for use in left ventricular aortic bypass should be designed considering the effect on the native heart pulsatility.

Animals↗
PubMed1998

Minimally invasive cardiac surgery in the adult: surgical instruments, equipment, and techniques.

To clarify the special instruments and equipment used for minimally invasive cardiac surgery (MICS), we examined the initial experiences with MICS operations with ministernotomy or minithoracotomy at our institution. Fifty adult patients with congenital, valvular, and/or ischemic heart diseases underwent MICS operations, and all surgical procedures were completed without conversion to full sternotomy. The length of the skin incision was about 10 cm or less in all patients. Postoperative recovery was favorable, and the majority of the patients were discharged from the hospital around the end of the second postoperative week. In this series of patients, an oscillating bone saw, lifting type retractor, 2 blade spreader, cannula with a balloon, and right-angled aortic clamp among other items, were very useful for successfully performing various operations with MICS approaches and techniques. The associated results suggest that MICS with ministernotomy or minithoracotomy was feasible using special instruments and equipment and could be encouraged for adult patients with various cardiovascular diseases.

Adult↗
PubMed1998

Lower level of serum potassium and higher level of C-reactive protein as an independent risk factor for giant aneurysms in Kawasaki disease.

Giant aneurysms are the most serious issue of patients with Kawasaki disease (KD). To clarify risk factors for these giant aneurysms, we conducted a matched case-control study. Among the patients reported in nationwide surveys, 117 patients with giant aneurysms had an unequivocal new diagnosis and presented at the treatment center within 9 d of illness. We obtained clinical information on admission of about 69 patients (case) from the treatment centers. One control was selected for each case, an age- and sex-matched patient without coronary involvement, reported from the same treatment center at about the same time as the case, and we obtained the same clinical information about controls. Fourteen variables were analysed with a conditional logistic regression model: body temperature, hematocrit, hemoglobin, numbers of leukocyte and platelets, concentrations of serum albumin, globulin, total cholesterol, sodium, potassium and chloride, erythrocyte sedimentation rate, C-reactive protein and alanine aminotransferase activity. After adjustment for age, duration of illness before admission and use of intravenous gamma globulin therapy, C-reactive protein [odds ratio (OR)=1.142, 95% confidence interval (CI) 1.054-1.237], alanine aminotransferase activity (OR=1.008, 95% CI 1.002-1.014), serum sodium concentration (OR=0.877, 95% CI 0.770-0.999) and serum potassium concentration (OR=0.319, 95% CI 0.124-0.822) were significantly related to the risk for giant aneurysms. Further analyses with these four explanatory variables revealed that C-reactive protein (OR=1.159, 95% CI 1.022-1.315) and serum potassium concentration (OR=0.222, 95% CI 0.052-0.948) met the significant level. Thus, the values for serum C-reactive protein and potassium are independent risk factors for the development of the giant aneurysms of Kawasaki disease.

Age Distribution↗