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O Kawaguchi

Publications and source records attributed to O Kawaguchi.

72 records · Page 4Linked to original sources
PubMed1991

[Modified Fontan operation for a single ventricle with a nonconfluent pulmonary artery].

A 8-year-old boy with a double inlet right ventricle with a non-confluent pulmonary artery was operated on with a modified Fontan operation. He had right isomerism, right aortic arch, bilateral superior caval veins, and left-sided inferior caval vein. Hepatic veins were separately drained to the right-side atrium. Left Blalock-Taussig shunt and right central shunt operations had been previously performed. Firstly, we had reconstructed the central pulmonary artery with a 16 mm porcine pericardial roll to unify the nonconfluent pulmonary arteries. Secondly, about 2 months after the first operation, we performed a modified Fontan operation. Systemic venous return from the inferior caval vein and the hepatic veins were drained to a reconstructed pericardial roll with an intraatrial Gore-Tex graft, and bilateral superior caval veins were also anastomosed to the roll. The structure of the pulmonary arterial system is one of the most important factors to determine the outcome of a modified Fontan operation. Even if the central pulmonary artery is absent, however, a modified Fontan operation is applicable for the patient whose peripheral pulmonary arteries have enough growth.

Blood Vessel Prosthesis↗
PubMed1991

[Non-occlusive mesenteric infarction following cardiovascular surgery].

In the majority of patients with intestinal infarction, it is generally agreed that the occlusion of mesenteric arteries or vein is the primary etiologic factor; however, some showed no evidence of thrombosis, embolization or vasculitis as the causative factor. In many patients, this particular type of infarction is the terminal event of the episode. From October 1977 to December 1986, 24 patients with mesenteric infarction were investigated following cardiovascular surgery in our institute. Among them, 15 were diagnosed with organic vascular occlusion; however, the other 9 showed no evidence of thromboembolism or any other organic vascular occlusive lesion of mesenteric vessels and were diagnosed as non-occlusive mesenteric infarctions. All of these patients were in severe cardiac failure (LOS) postoperatively. There was no typical symptom, although abdominal fullness and diarrhea were the major and consistent findings. In blood chemical analysis, the enzymatic levels such as serum GOT, LDH and CPK were significantly elevated and discrepancy between serum GOT and serum GPT was observed. In this clinical situation, it was difficult to establish a correct diagnosis mainly because of the few signs and symptoms present relating to the mesenteric infarction. On the other hand, when the correct diagnosis was made, these patients were too critically ill to be treated conservatively. The outcome of these patients was grave and all of them died which showed 100% of mortality rate. The conservative management did not produce favorable progress, which accelerated LOS and prevented patients from recovering from cardiac failure. The aggressive surgical approach to this particular type of acute mesenteric ischemia might have offered an improved prognosis from these catastrophic events.

Adult↗
PubMed1990

Simulation of mechanoenergetics of asynchronously contracting ventricle.

We simulated mechanoenergetics of ventricular asynchronous contraction using a model comprising two compartmentalized asynchronous time-varying elastic elements, E1 and E2. Their elastances [e1(t) and e2(t)] waxed and waned cyclically with a variable time lag (tau). The pressure-volume area (PVA1 or PVA2) circumscribed by the maximum (emax) and minimum e1(t) or e2(t) lines and the contracting pressure-volume trajectory of E1 or E2 quantifies the mechanical energy generated by a contraction of E1 or E2. Similarly, the PVA circumscribed by the resultant Emax (ventricular contractility index) line, the end-diastolic pressure-volume (P-V) line, and the systolic P-V trajectory quantifies the mechanical energy of the entire ventricle. PVA of the ventricle is equal to the sum of PVA1 and PVA2. We found that Emax decreased with increases in tau despite constant emax, and hence ventricular PVA decreased with increases in tau. This simulation helps us to better understand the mechanism of decreased oxygen consumption with increasing ventricular asynchrony reported in the literature.

Animals↗
PubMed1990

New method to determine oxygen cost for contractility.

We developed a new method to determine the oxygen cost for myocardial contractility and applied it to epinephrine in the excised cross-circulated dog heart. We utilized the relation between myocardial oxygen consumption (VO2) and the systolic pressure-volume area (PVA) which represents the total mechanical energy generated by contraction. We first obtained a reference VO2-PVA relation in a baseline contractile state. Then, the end-diastolic and stroke volumes were fixed constant and a global index of ventricular contractility, Emax, was enhanced by infusing epinephrine. The VO2-PVA data point was shifted linearly right-upward with the increases in Emax. From the slopes of both the reference VO2-PVA relation line and the regression line of VO2 on PVA during the gradually increased Emax, we calculated the oxygen cost for contractility, i.e., the ratio of the elevation of the VO2-PVA relation to enhanced Emax in each heart. The ratio was 0.00095 +/- 0.00013 ml O2.ml.mmHg-1.beat-1.100 g LV-2. The result indicates that the oxygen cost for contractility can be reliably and efficiently determined by this new method.

Animals↗
PubMed1990

Comparison between Bretschneider's total myocardial energy demand (Et) and our total mechanical energy (PVA) as a predictor of cardiac oxygen consumption in dogs.

We compared the predictive capability of two indexes of ventricular oxygen consumption (VO2) in excised cross-circulated dog hearts. One of the indexes was Bretschneider's Et, formulated as the sum of energies for 5 different mechanical and nonmechanical activities of myocardium. The other one was the left ventricular systolic pressure-volume area (PVA), originally proposed by Suga. PVA is a measure of total mechanical energy and has been combined with Emax (ventricular contractility index) to predict VO2 in different inotropic states. When all data sampled from different hearts under various loading and inotropic conditions were pooled, both VO2 (Bret) predicted from Bretschneider's index and VO2 (Suga) predicted from Suga's index correlated well with the measured VO2 (VO2 (Measured)). However, VO2 (Bret) was more affected by the contraction mode as compared with VO2 (Suga), because the former includes ejection period as a parameter. Among the 5 terms of VO2 (Bret), the major correlate of VO2 (Measured) was found to be tension development energy term E3 which includes dP/dtmax as a parameter. VO2(Suga), as a predictive index of VO2 (Measured), was more reliable in each heart than in pooled data from all the hearts because of the interindividual variations of the coefficients. We conclude that both indexes have usefulness and limitations, and should be chosen depending on the application.

Animals↗
PubMed1990

Assessment of left ventricular regional work under ischemia.

The wall tension-regional area (T-A) loop method, a new approach assessing regional contractile function of the left ventricle, has been developed in experiments performed on the isolated dog heart. Regional work is quantitatively determined by the area within a T-A loop with physically correct dimensions of energy (Joule) and regional contractility can be reliably assessed by the end-systolic T-A relation (ESTAR). During global ischemia, both the T-A loop area and the slope of the linear ESTAR decreased in proportion to the decreases in left ventricular stroke work and contractility. During regional ischemia, the T-A loop area in an ischemic region decreased to near zero, and the ESTAR markedly shifted to the right with a decreased slope and an increased regional area intercept. In contrast, the T-A loop in a non-ischematic region showed an increase in systolic area shrinkage and a decrease in regional work, demonstrating hyperkinesis due to regional afterload reduction. In addition, the ESTAR in a non-ischemic region remained almost unchanged. Thus, using the T-A loop method we can reliably assess regional work and contractility of a left ventricular region under ischemia.

Animals↗
PubMed1989

[Comparative analysis of long-term results with porcine-aortic, bovine pericardial and tilting disc valves].

The three series with the first-generation valve prostheses were reviewed for long-term clinical evaluation in isolated aortic and mitral valve replacement. Hancock porcine xenograft was implanted in 71 patients from 1977 to 1979, ionescu-Shiley pericardial xenograft (standard model) in 271 patients from 1979 to 1983, and Bjork-Shiley tilting disc valve in 194 from 1978 to 1986. In aortic position, no any significant difference among three valve types could be demonstrated in the actuarial survival and freedom from thromboembolism and valve infection, while the actuarial freedom from valve dysfunction in lonescu-Shiley valve was significantly lower than that in other two valves. Björk-Shiley valve in mitral position showed satisfactory clinical performance in terms of valve-related complications and survival in comparison with two types of bioprosthetic valves. In our conclusion at present time, Björk-Shiley valve is suitable for the first choice of both aortic and mitral valve prostheses. In case of valve replacement with a bioprosthesis, however, porcine aortic valve is a better choice for aortic, and bovine pericardial valve likely for mitral replacement.

Aortic Valve↗
PubMed1984

Isolation of two beta-xylosidase genes of Bacillus pumilus and comparison of their gene products.

The chromosomal DNA fragments of Bacillus pumilus IPO, a potent xylan-hydrolyzing bacterium, were ligated to a vector plasmid, pBR322, and used to transform Escherichia coli C600 cells. Two hybrid plasmids, pOXD28 and pOXN29, were found to enable the transformants to produce beta-xylosidase. The former was found to contain a 2.6-MDa Bg/II fragment and the latter, a 7.7-MDa PstI fragment, both coding beta-xylosidase, but xylanase is coded only on the latter hybrid plasmid. The DNAs inserted in both plasmids originated from the B. pumilus chromosome, but from different regions, as shown by Southern hybridization and the analysis of restriction fragments. beta-Xylosidases I and II, coded on pOXN29 and pOXD28 respectively, were purified to homogeneous preparations and compared. Both were dimer enzymes consisting of 65000-70000-Da subunits. Specific activity and the Km value of beta-xylosidase I to p-nitrophenyl beta-D-xyloside as substrate were respectively 100 and 1/40 times those of beta-xylosidase II. The mobilities of beta-xylosidases I and II on polyacrylamide gel electrophoresis were also different. beta-Xylosidase I, the gene of which is located near the xylanase gene on pOXN29, can convert xylooligosaccharides to xylose, but beta-xylosidase II had little activity on xylobiose. These results suggest that beta-xylosidase I is the main enzyme for xylan hydrolysis in B. pumilus.

Bacillus↗
PubMedDate not supplied

Histological remodeling in an ovine heart failure model resembles human ischemic cardiomyopathy.

Staged coronary embolization, causing myocardial microinfarctions, has been shown in dogs and sheep to cause chronic ischemic heart failure (HF) that resembles the hemodynamics of the human condition. However, its histopathological basis remains unclear. We examined the hypothesis that the ventricular remodeling seen in such sheep resembles the histopathology of human ischemic cardiomyopathy (ICM). Understanding the pathophysiology of this model will determine its place in the development of treatment strategies for HF. Global left ventricular (LV) damage resulting in HF was induced by staged coronary embolization in 11 sheep. Six others served as controls (normal control, NC). In HF sheep, the heart was harvested 6 months after LV ejection fraction (EF) had stabilized at <35%. Histopathological profiles were compared in biventricular transverse sections at midpapillary level using computed image analysis. LV end-diastolic volume increased in the HF group from 84.9+/-29 to 122.4+/-30.3 ml (n=11, P<.05), but myocytes across the LV wall in noninfarcted zones decreased (435.7+/-38.2 NC; 297.8+/-48.4/unit area HF; n=11, P<.0001) as did myocyte nuclear density (990.5+/-51.5 NC; 677.5+/-121.1/mm(2) HF, n=11, P<.0001). In contrast, LV replacement and interstitial fibrosis increased as did myocyte diameter in noninfarcted zones: 0.1+/-0.1 to 6.2+/-4.5% (P=.0049); 2.0+/-1.0 to 7.6+/-4.9% (P=.0149); and 10.0+/-0.5 to 15.9+/-2.2 microm (P<.0001), respectively. Although LV myocyte nuclear length increased (10.2+/-1.0 NC; 12.2+/-0.9 microm HF, n=11, P=.0006), right ventricular (RV) myocyte nuclear density and length did not alter. In this ovine chronic HF model, LV dilation and interstitial and myocyte remodeling resemble human ICM.

Animals↗
PubMedDate not supplied

An electrically powered total artificial heart. Over 1 year survival in the calf.

An electric motor driven orthotopic artificial heart was implanted in a 110 kg female Holstein calf as part of a series of 12 such implants intended to demonstrate the in vivo durability and compatibility of the device. The device uses pusher plates set into motion by a reversing brushless DC motor and roller screw to alternately eject two cylindrical sac type blood pumps. The pumps use Bjork-Shiley Delrindisc convexo-concave or monostrut valves. The left pump provides an 88-90 ml dynamic stroke volume. Woven Dacron grafts and polyurethane coated Dacron/Lycra cuffs are used to attach the device to the major arteries and atria, respectively. A polyurethane conduit and anchoring skin button bring motor wires percutaneously to an extracorporeal controller. The controller provides balanced cardiac output sensitive to atrial or aortic pressures, without operator intervention. The system is hermetically sealed and uses a simple compliance sac to maintain thoracic pressure between the pumps. The calf recovered uneventfully from surgery and thrived thereafter. She was killed on the 388th post-operative day because of worsening cardiac insufficiency. The previous three operative survivors in this series lived 131, 134, and 204 days. These results indicate the device's good potential for durability and body compatibility.

Animals↗
PubMedDate not supplied

Breast-conserving therapy for ductal carcinoma in situ.

This retrospective analysis evaluates the treatment results and prognostic factors of 114 patients with ductal carcinoma in situ (DCIS) undergoing breast conserving therapy (BCT) at Keio University Hospital Department of Radiology, between 1988 and 1997. A total of 132 patients with DCIS of the breast came to our hospital between 1988 and 1997, and 114 cases were suitable candidates for BCT. All of the patients were female and ranged in age from 26 to 81 years (median 46). Ninety-one patients were premenopausal, and 23 were postmenopausal. Median clinical tumor size was 2.0 cm (0-8.0 cm). Postoperatively 48 cases received 50 Gy/25 fractions of external irradiation to the whole breast via tangential ports. The follow-up period after treatment ranged from 11 to 162 months (median 46.7). The local relapse-free rate and overall survival rate of the 114 patients were 89.5% and 100%, respectively. Local failure and regional nodal failure occurred in 12 and 1 patient, respectively. Radiotherapy was a significant risk factor for local failure (p=0.05). No postmenopausal patients developed local failure, but the difference did not reach statistical significance (p=0.103). The 12 recurrent cases underwent additional surgery and all remain alive without recurrence, to date, i.e., at least 16 months. Breast-conserving surgery plus irradiation is appropriate treatment for DCIS patients.

Adult↗
PubMedDate not supplied

Effect of combined treatment with radiation and low dose etoposide on cell survival.

BACKGROUND: To improve the radiotherapy results, we evaluated etoposide as an effective radiosensitizer by using cultured cell-lines. MATERIALS AND METHODS: Four cell lines having different doubling times (DT) were used: V79 (Chinese hamster fibroblasts, DT = 9 hours), (1), T24 (human bladder cancer, DT = 19 hours) (2), MDA-MB231 (human breast cancer, DT = 25-30 hours) (3) and RMG1 (human ovarian cancer, DT = 50 hours) (4). Cell survival was determined by colony assay and cell cycle analysis was performed by flow-cytometry. RESULTS: The survival curves showed RMG1 to be the most radiosensitive, followed by MDA-MB231, T24, and V79. V79 was most chemosensitive to etoposide, followed by T24, MDA-MB231 and RMG1. Neither 24-hours exposure to etoposide (< or = 0.05 microgram/ml) or 0.5-h exposure (< or = 1.0 microgram/ml) had any cell killing effect on any of the cell lines used. When the cells were irradiated after exposure to 1 microgram/ml of etoposide for 0.5 hours, no radiosensitization was observed in any of the cell lines except V79. Enhanced radiosensitivity was observed in V79 and T24 cells (which have a relatively short DT) when they were incubated with 0.05 microgram/ml etoposide for 24 hours but no enhanced effect was seen in MDA-MB231 or RMG1 cells (which have a relatively long DT). CONCLUSION: It is suggested that a combination of radiation and etoposide may be useful in the treatment of rapidly growing cancer.

Animals↗
PubMedDate not supplied

In vivo testing of a completely implanted total artificial heart system.

The authors performed 14 implants of a completely implanted total artificial heart (TAH) system in calves. The system consisted of a dual pusher plate rollerscrew energy converter, two sac type blood pumps, an implanted electronic control and battery package, and a transcutaneous energy transmission system. Ten of the implants included a percutaneous lead for monitoring of the implant; the remainder made use of wireless two way telemetry between the implant and the outside. Three animals survived the perioperative period. These calves survived for 98 to 118 days, and one was still alive at 150 days. Causes for termination of the 98 and 118 day cases were abdominal pocket sepsis originating at a monitoring line, and systemic sepsis acquired perioperatively. Death or termination in the shorter cases was mainly due to respiratory complications or bleeding. The TAH system proved capable of providing adequate cardiac outputs at modest atrial pressures. Wireless monitoring and wireless intervention for weaning from cardiopulmonary bypass were readily achieved. All organ systems functioned normally in the presence of the device. Once recovery from implantation in these very young animals was achieved, the system proved its ability to reliably support these animals until body mass exceeded its cardiac output capabilities.

Animals↗
PubMedDate not supplied

A completely implanted left ventricular assist device. Chronic in vivo testing.

A completely implantable left ventricular assist device (LVAD) designed for permanent circulatory support has recently been tested in animals without the use of percutaneous leads, using transcutaneous energy transmission and wireless telemetry. The LVAD consists of a brushless DC motor and rollerscrew energy converter, a pusher plate actuated blood pump with a seamless segmented polyurethane blood sac, Bjork-Shiley Delrin disk monostrut valves, an implanted compliance chamber, an implanted electronic controller and battery, and a transcutaneous energy transmission system. The blood pump/energy converter assembly weighs 565 g and displaces 295 cc. The dynamic stroke volume is 60 ml, and the maximum output is 9 L/min. Pump output is automatically controlled to maintain full stroke volume as preload varies. Hall effect sensors for detecting rotary position of the motor are the only sensors used. Six bovine implants were performed, with durations of 84, 208, 244, 130, 70 (ongoing), and 15 (ongoing) days. Four animals used two-way telemetry, whereas the remaining two used one-way (outgoing) telemetry. These first chronic in vivo tests with the Penn State completely implanted LVAD system have demonstrated that it is a feasible solution to long-term ventricular support.

Animals↗
PubMedDate not supplied

A stable ovine congestive heart failure model. A suitable substrate for left ventricular assist device assessment.

Similarities in coronary circulation and heart size of sheep to that of humans are specific advantages of a sheep model of congestive heart failure (CHF). CHF was created in 11 sheep (51 +/- 4 kg) by selective sequential intracoronary injection of 90 microns microspheres under 1.5% isoflurane anesthesia. Hemodynamic characteristics were assessed at baseline, 4 weeks after establishment of CHF (ejection fraction [EF] < 35%, n = 11), and 26 weeks (n = 7) later. Baseline echocardiographic EF was 59 +/- 5% and fell to 26 +/- 5% after 5 +/- 2 embolizations. The left ventricular (LV) pressure-volume relationship showed stable decreases in LV end-systolic elastance (Ees) and preload recruitable stroke work. Intravenous infusion of dobutamine increased Ees from 2.8 +/- 1.7 to 4.3 +/- 2.2 and 4.5 +/- 1.4 mmHg/ml at heart rates of 140 and 160/min, respectively, at baseline. Increases of Ees (from 1.3 +/- 0.5 to 2.3 +/- 0.7 and 1.9 +/- 0.5 mmHg/ml at heart rates of 140 and 160/min, respectively) with dobutamine under CHF conditions did not exceed Ees values at baseline without dobutamine. This response to dobutamine infusion did not change 26 weeks after establishment of CHF. This stable ovine CHF model is proposed for studies on the long-term effects of cardiac assist devices.

Animals↗