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Biomedical subjects

H Mohri

Publications and source records attributed to H Mohri.

At least 415 records · Page 23Linked to original sources
PubMedDate not supplied

The newly designed univalved artificial heart.

A univalved artificial heart (AH) powered electromagnetically in the frequency range of 1-30 Hz was developed to obtain a totally implantable AH. This small sized AH consisted of a vibrating tube, coils, magnets, and a jellyfish valve as an outlet AH valve. The fluid mechanical, hemodynamic, and hematologic properties were evaluated in a mock circulation and 10 animal experiments using adult goats. This vibrating electromagnetic AH could generate more than 10 L/min as an output volume, with 10 Hz vibration using 20 volts supplied voltage. It could also provide two kinds of flow and pressure patterns, in constant-peak and periodic-peak patterns. The values of free hemoglobin remained within acceptable limits. The authors concluded that this new type of pump was useful as a totally implantable AH, ventricular assist, or organ assist system.

Blood Flow Velocity↗
PubMedDate not supplied

Real time sound spectral analysis for early detection of thrombosed Björk-Shiley standard disc valves.

Clinical usefulness of sound spectral analysis (SSA) in early detection of thrombosed Bjork-Shiley standard tilting disc prostheses (B-SP) was evaluated. Among a total of 365 B-SP, nine valves developed thrombosis. These included seven MVR and two AVR, and replacement of the affected valves was performed in all cases. Thrombus formation was localized at the minor strut in two cases in which the SSA demonstrated preoperative abnormalities of only opening clicks. In four cases, thrombus formation was noted at both minor and major struts, and the SSA showed abnormalities both on opening and closing clicks. In two cases with pannus formation, no abnormalities were found by SSA. As the thrombi were seen on the minor strut during surgery in all cases with thrombosed valves, the minor strut is considered as the preferred, and probably initial area of thrombus formation, and the diagnosis therefore could be made by abnormal findings on opening clicks. In conclusion, the SSA was found to be a useful diagnostic tool for early detection of thrombosis of B-SP, because the opening clicks of the tilting disc valves were often too low in amplitude for abnormalities to be detected by auscultation.

Adult↗
PubMedDate not supplied

Recent advance in treatment of Stanford type A aortic dissection.

During the period between November 1986 and November 1988, 13 consecutive patients with Stanford type A aortic dissection (8 acute and 5 chronic) were treated as follows: (1) urgent operation for cases with pericardial tamponade or severe heart failure, (2) initial medical treatment followed by elective operation for acute but stable cases or chronic cases, and (3) routine use of open distal anastomosis or selective cerebral perfusion. One patient died during medical treatment: 5 patients were operated on emergently. The remaining 2 acute and 5 chronic cases were operated on electively. There were no operative deaths, neurological disturbances, or late deaths. It is suggested that acute dissection of the ascending aorta requires immediate surgical intervention, especially when the entry is in the ascending aorta. On the other hand, it is also suggested that one could avoid emergency operations in selected cases with retrograde extension of the aortic dissection.

Acute Disease↗
PubMedDate not supplied

Multi-institutional evaluation of the Tokyo University Ventricular Assist System.

A total of 61 VASs developed in Tokyo University were evaluated at 21 institutions in the period 1985-1989 for determination of its reliability and effectiveness. The system is comprised of a pneumatic sack-type pump (Nippon Zeon Co.), and its driving console (Aishin Seiki Co.). The stroke volume of the pump is 40 ml and blood contacting surfaces are coated with Cardiothane. Ages of the patients (pts) ranged from 12-82 yrs (mean 58 yrs). VASs were used in the assist mode of LVAD (54 pts), RVAD (5 pts) and BVAD (2 pts). Most of the cases (58 pts) included postocardiotomy cardiogenic shock after surgery for ischemic (28 pts), valvular (22 pts), both ischemic and valvular (7 pts) and congenital (1 pt) heart diseases. Average duration of the assist ranged from 1 hr-20 days (mean 5.6 dys). The VADs could be weaned in 34 cases (56%) and among these, 13 cases (21%) survived to discharge from the hospital. Causes of death in cases which could be weaned from the VAD included multiple organ failure/due to delayed institution of adequate circulatory support, renal failure and systemic infection. Small and minute thrombus formations were noted in 7 cases however, no pump originated thromboembolism were complicated. No troubles of the pump including leakage nor breakage, no mechanical failures of the driving consoles were experienced in any of the cases. Thus, it is concluded that the system was proved to be clinically effective and reliable.

Adolescent↗
PubMedDate not supplied

Myocardial tissue blood flow in allotransplanted rat heart with a special reference to acute rejection.

To evaluate the severity of acute rejection of the homologous heart, myocardial tissue blood flow was measured after a heterotopic heart transplantation in rats. The autograft group (Lewis to Lewis) and the allograft group (DA to Lewis) were compared by graft survival time, myocardial tissue blood flow, myocardial water content, and degrees of histologic alterations. Average graft survival times were longer than 100 days in the autograft group and 5.9 +/- 0.4 days in the allograft group. In the autograft group, myocardial tissue blood flows on postoperative days 1 and 5 were 206 +/- 12 and 189 +/- 18 ml/min/100 gm myocardial wet weight in the left ventricle and 205 +/- 11 and 188 +/- 12 ml/min/100 gm myocardial wet weight in the right ventricle, respectively. In the allograft group, myocardial tissue blood flows on postoperative days 1, 3, and 5 were 222 +/- 30, 164 +/- 22, and 141 +/- 49 ml/min/100 gm myocardial wet weight in the left ventricle and 202 +/- 17, 156 +/- 15, and 147 +/- 46 ml/min/100 gm myocardial wet weight in the right ventricle, respectively. Myocardial tissue blood flows in both ventricles showed significant decreases on days 3 and 5 as compared with those on day 1. Myocardial water content did not alter significantly by day 5 in the autograft group, registering 77.9% +/- 0.6% and 78.4% +/- 1.6%. Myocardial water contents in the allograft group increased significantly as rejection progressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMedDate not supplied

Mecobalamin promotes mouse sperm maturation.

The effect of Mecobalamin (alpha-(5,6-dimethyl benzimidazolyl)-Co-methyl-cobamide: Me-B 12) on sperm production in the oligozoospermic mice experimentally induced by the treatment with adriamycin (0.3 mg/kg, three times a week for 5 weeks) was evaluated quantitatively by means of equilibrium sedimentation in Percoll. After centrifugation, the distribution profile of the sperm showed two peaks, i.e. the first peak near the bottom consisting of mature sperm with good motility and the second peak containing immature and/or immotile sperm. By oral administration of Me B 12 (1.0 mg/kg/day) to the oligozoospermic mice for 10 weeks, the sperm count, sperm motility, motile sperm count, diameter of seminiferous tubules and the percentage of good motile sperm with higher apparent density were increased as compared with those of the control. These results suggest that Me-B 12 enhanced the testicular function, resulting in an increased output of mature sperm.

Animals↗
PubMedDate not supplied

Antithrombogenicity of ventricular assist devices for postoperative myocardial dysfunction.

Antithrombogenicity of pneumatic ventricular assist devices (VAD) for postoperative ventricular failure was evaluated macroscopically and microscopically in relation to VAD flow, coagulation parameters, and other potentially thrombogenic factors. A total of 12 sack type pumps were used in nine cases after operations for ischemic heart diseases (4 cases), valvular diseases (3 cases), and congenital anomalies (2 cases). Durations of pumping of each device ranged from 18 hours to 37 days (mean, 10.9 days). The clinical protocol for antithrombogenicity of the device indicates maintenance of ACT around 150 sec and keeping VAD flow more than 2.0 L/min. In our clinical series, however, heparin was given only in most cases to maintain activated clotting times (ACT) at 120-140 sec for the first three postoperative days. Minute ringlike thrombi were noted at connectors of cannula in two pumps after low flow (1.5 L/min) pumping for 5 days or after frequent on/off studies for weaning. A small thrombus (2 X 2 mm) and fine granular thrombi were noted on actuating bladders in two pumps that were used with frequent on/off studies or in a patient with severe sepsis during VAD pumping. Other VAD pumps were macroscopically free of thrombus. SEM analyses on surfaces of actuating bladders demonstrated mild to moderate platelet adhesions, which were correlated with platelet count, but not with other coagulation parameters including platelet agglutination and pumping duration. In cases with leucocytosis during VAD uses, leucocyte adhesion was noted as well without correlation to the coagulation parameters.

Adolescent↗
PubMedDate not supplied

Real time sound spectral analysis for diagnosis of thrombosed prosthetic valves.

A real time sound spectral analyzer was developed at the authors' institute and has been used for diagnosis of thrombosed valves for 15 years. The analyzer consists of a wider frequency microphone, a digital signal processor with multiple bandpass filters, and displays. To quantify the high frequency component in section pattern of opening and closing clicks, maximal frequency at -30 dB level was used at a diagnostic parameter (normalized maximal frequency, NMF). A total of 17 thrombosed valves with or without pannus formations have been experienced and SSA showed abnormality in 13 valves, which comprised of Björk-Shiley (N = 6), Starr-Edwards 2320, 6120, 6520 (N = 5) and Kay-Shiley (N = 2). The abnormal findings included NMF of opening or closing clicks lower than normal range of each type of prosthesis, and significant decrease of NMF more than 450 Hz from the value previously obtained. All diagnoses of thrombus formations and their locations were confirmed by operative or autopsy findings. The SSA failed to diagnose in four valves, which comprised of Starr-Edwards 6520 (N = 3) and Björk-Shiley (N = 1). Operative findings revealed that thrombi were formed in a manner that permitted direct collision of disc and valvular ring causing clicks with high frequency component. No pseudo-positive diagnosis for thrombosed valve was experienced in the authors series, and SSA is thought to be a reliable noninvasive technique that enables early diagnosis of a thrombosed valve.

Adult↗
PubMedDate not supplied

Effect of pancreatopeptidase E (elastase) on the suppression of intimal fibrous proliferation after arterial reconstruction in high cholesterol fed rabbits.

The purpose of this study was to investigate the effect of pancreatopeptidase E (Elastase) administration on the healing of anastomosed arteries. A segment of infrarenal aorta was resected and reanastomosed in rabbits. In the control group, rabbits were fed commercial chow (ORC 4). In the cholesterol group, rabbits were fed a diet of 1% cholesterol added to ORC 4. In the Elastase group, rabbits were fed the same diet as the cholesterol group but received intraabdominal injections of Elastase. The rabbits were kept for 4 months and the abdominal aorta was retrieved for examination. All anastomosed aortas were patent. The cholesterol group developed aneurysmal dilatation in one and stenosis of the anastomosed sites due to hypergranulation in the remaining rabbits. Neither aneurysmal nor stenotic changes were detected in the other groups. We concluded that the administration of Elastase suppressed cholesterol induced atherosclerotic changes at the anastomotic sites in these animals.

Anastomosis, Surgical↗
PubMedDate not supplied

Transcutaneous PO2 response to transient arterial occlusion in peripheral occlusive disease.

Transcutaneous oxygen tension response to transient arterial occlusion (tcPO2T/2) was examined at the medial mid-calf and dorsum of the foot in 20 patients with thromboangiitis obliterans or arteriosclerosis obliterans, and in normal subjects in order to accurately assess the rate of skin oxygenation. Though the mean value of transcutaneous oxygen tension (tcPO2) correlated with the mean value of tcPO2T/2 before and after arterial reconstruction, a discrepancy between the tcPO2 and tcPO2T/2 values was demonstrated in some cases. The tcPO2T/2 values manifested the severity of the peripheral skin oxygenation more clearly than tcPO2 values because changes in the tcPO2T/2 value paralleled improvement in symptoms after arterial reconstruction. It was concluded that the tcPO2T/2 value was useful in grading the severity of disease, in detecting the site of the arterial occlusion and in evaluating changes in symptoms before and after arterial reconstruction.

Adult↗
PubMedDate not supplied

Methods of suppression of myonephropathic metabolic syndrome.

Acute arterial occlusion of the extremities may result in severe and complex metabolic derangements. In order to investigate therapeutic means of controlling such metabolic derangements, 19 adult mongrel dogs weighing between 7 and 15 kg underwent acute arterial occlusion by cross-clamping the infrarenal aorta. Clamping was released after 48 hours. The experimental animals were divided into three groups: an untreated group, a THAM group, and a perfusion group. Biochemical and electrolyte analyses were measured before and 1 hour after occlusion, and 1, 3, 12, 24, and 48 hours after the release of occlusion. The SGOT, creatinine, CPK, and aldolase levels rose after release of the occlusion and were significantly higher in the untreated group than in the THAM and perfusion groups. Among these enzymatic changes, the CPK level showed the largest increase. The serum potassium levels remained almost at preocclusion levels after release of the occlusion. It was concluded that the intravenous administration of THAM and peripheral washing were effective against untoward metabolic changes occurring in the ischemic extremities.

Animals↗
PubMedDate not supplied

Late changes in hemostatic parameters following open-heart surgery.

Changes in hemostatic parameters following open-heart surgery with cardiopulmonary bypass were studied in twelve patients for two postoperative weeks. No clinical manifestations of hemostatic abnormalities were found in these patients throughout the study period. The prothrombin time and activated partial thromboplastin time were within normal limits. The platelet counts and fibrinogen levels were depleted on the first postoperative day, followed by a rapid return to above normal levels within 7 days. The fibrinogen/fibrin degradation products (FDP) showed a peak elevation on the first day, followed by a gradual decline. In 92% of the patients, the FDP levels became elevated to more than 10 micrograms/ml. Rate of the increase in FDP level was closely reflected by the amount of postoperative blood loss when the loss exceeded 10 ml/kg of body weight during 48 hours postoperatively. The levels of plasmin inhibitors (alpha 1-antitrypsin and alpha 2-macroglobulin) were also measured. the alpha 1 antitrypsin was elevated during the postoperative period. The alpha 2-macroglobulin showed no significant changes. In summary, the hemostatic changes following open-heart surgery included activation of the fibrinolytic system and depletion of coagulation factors immediately after surgery, followed by hypercoagulability due to a rapid return to above normal levels of coagulation factors and plasmin inhibitors. We consider, however, these changes to be part of the homeostatic response following open-heart surgery.

Adult↗
PubMedDate not supplied

Leakage across the premoulded dacron baffle used for correction of transposition of the great arteries.

The use of a pre-moulded dacron baffle, as described by Dillard, and used as an interatrial baffle in transposition of the great arteries resulted in an extensive leakage of blood through the baffle for several days. Pre-clotting of the baffle on one occasion only was ineffective in preventing the leakage. But complete sealing was effected by pre-clotting three times according to the method of Sauvage. These clinical findings were confirmed by microscopic analysis. A porous baffle way will be an advantage in patients with pulmonary hypertension when it would act as a safety valve.

Angiocardiography↗
PubMedDate not supplied

Proposal of a working left heart model with a heterotopic transplantation technique in rats.

BACKGROUND: A heterotopically transplanted rat heart model described by Ono and Lindsey in 1969 has been widely used as a fundamental animal model of heart transplantation. However this "nonworking" model is greatly different from the orthotopic heart in view of left ventricular work, in which the experimental results obtained may not always reflect the clinical setting with an orthotopic transplanted "working" heart. We herein propose a new "working" left heart model in rats using a heterotopic abdominal transplantation technique by modifying the method of Ono and Lindsey. METHODS: First, a donor heart graft and a recipient were prepared in the conventional fashion. Second, the donor heart was tailored by the ligation of main pulmonary artery and the removal of tricuspid valve and interatrial septum. Third, the ascending aorta and right atrium of the donor heart were anastomosed to the infrarenal abdominal aorta and to the inferior vena cava of the recipient, respectively. Consequently, the left atrium and ventricle of heart graft were loaded with the blood from the right atrium through the interatrial communication. RESULTS: This surgical procedure required an average of 58 minutes and had negligible operative risk. The donor left ventricle produced a systolic blood pressure almost equal to the recipient's aortic pressure and maintained vigorous beat. CONCLUSIONS: This model is easily reproducible and would be useful for various studies on heart transplantation.

Animals↗