Biomedical subjects

T Shimono

Publications and source records attributed to T Shimono.

At least 55 records · Page 3Linked to original sources

PubMed1998

Arterial baroreceptor afferent activity in nonpulsatile systemic circulation.

We directly measured aortic depressor nerve activity (ADNA) in rabbits to investigate changes in arterial baroreceptor afferent activity (ABAA) in response to nonpulsatile systemic circulation (NC) during total left heart bypass (TLHB). ADNA was measured before and 5, 20, 30, 40, 50, and 60 min after the start of TLHB while maintaining the mean aortic pressure (MAP) at preestablished values (n=10). At 5 min, the ADNA was significantly increased compared to its baseline value. At 30 min, it was significantly decreased compared to its value at 5 min and thereafter remained the same. The ADNA was then measured before and 5 and 30 min after the start of TLHB under increased MAP (n=10). The results showed that the percentage changes in ADNA during TLHB were significantly less than that observed when the MAP was increased before TLHB. We conclude that ABAA acutely adapts to NC 30 min after its initiation, but changes in ABAA are depressed under NC combined with increased MAP.

Afferent Pathways↗

PubMed1998

[Selection criterion of limited operation for lung cancer as a radical operation].

We reviewed partial resection and segmentectomy for 75 cases (6.5%) out of 1,212 cases treated surgically for primary lung cancer between 1957 and 1996. The surgical results of limited operation in radicality group and risk group was comparable to that of standard operation for the stage I lung cancer. Five-year survival of clinical stage I non-small cell lung cancer patients that tumor size is 2.0 cm or less was excellent (88.9%). Although risk group may be the best candidates for limited surgery, careful patient selection and theoretical operative procedure could make limited operation a standard procedure in radicality group.

Adenocarcinoma↗

PubMed1998

[Surgical treatment for primary lung cancer in octogenarians: the role of limited operations].

34 octogenarians out of 1,214 cases treated surgically for primary lung cancer in our unit between 1957 and 1996. 12 patients underwent limited operation because they had one or more risk factors besides their age actor. We could suppress postoperative complications in octogenarians. 5-year survival rate in octogenarians was comparable to that in younger patients. The octogenarians underwent limited operations were better than those had lobectomies in 5-year survival rate and postoperative quality of life. So our surgical strategy for primary lung cancer in octogenarians was evaluated to be appropriate. However, we should improve the radicality of limited operation furthermore because 5-year survival rate for stage I non-small cell lung cancer was poor in octogenarians than in younger patients.

Adenocarcinoma↗

PubMed1998

A heparin-coated circuit maintains platelet aggregability in response to shear stress in an in vitro model of cardiopulmonary bypass.

Alterations in platelet aggregability may play a role in the pathogenesis of qualitative platelet defects associated with cardiopulmonary bypass (CPB). We circulated fresh heparinized whole blood through tubing sets coated with heparin (C group, n = 10) and through non-coated sets (N group, n = 10) as a simulated CPB circuit. Shear stress (108 dyne/cm2)-induced platelet aggregation (hSIPA), plasma von Willebrand factor (vWF) activity and platelet glycoprotein (GP) Ib expression were measured, before, during, and after this in vitro set up of circulation. In the two groups, the extent of hSIPA significantly decreased during circulation and was partially restored after circulation. Decreases in the extent of hSIPA were significantly less with use of heparin-coated circuits. There was an equivalent reduction in plasma vWF activity, in the two groups. Expression of platelet surface GP Ib decreased significantly during circulation and recovered after circulation. Reduction of surface GP Ib expression during circulation was significantly less in the C group than that in the N group. Decrease in surface GP Ib expression correlated (r = 0.88 in either group) with the magnitude of hSIPA, in the two groups. The progressive removal of surface GP Ib was mainly attributed to redistribution of GP Ib from the membrane skeleton into the cytoskeleton. Our observations suggest that use of heparin-coated circuits partly blocks the reduction of hSIPA, as a result of a lesser degree of redistribution of GP Ib.

Blood Platelets↗

PubMed1998

[Results of surgical treatment for pT3 primary lung cancer].

We reviewed pT3 lung cancer for 86 cases (13.1%) out of 659 cases treated surgically for primary lung cancer between 1985 and march 1998. Five-year and ten-year survival rates for all pT3 cases were 48% and 40% respectively and those for pT3N0M0 cases were 67.2%. The operative mortality between 1990 and 1998 (2.4%) was better than that between 1985 and 1989 (6.7%). The extensive resection for pT3 lung cancer was evaluated to be appropriate. However, the prognosis of the patients who underwent combined resection of mediastinal pleura, pericardium or diaphragm was very poor. Five-year survival rate was significantly worse in patients with N2 disease (17.3%) than in patients with N0 disease (65.8%) (p < 0.05). Although the surgical indication for the patients with mediastinal pleura, pericardium or diaphragm disease and N2 disease is still controversial, there is not the extensive surgical indication.

Adolescent↗

PubMed1997

Single transduction in the transcriptional activator CooA containing a heme-based CO sensor: isolation of a dominant positive mutant which is active as the transcriptional activator even in the absence of CO.

We constructed an in vivo reporter system to measure the activity of CooA as the transcriptional activator and showed that the recombinant CooA was active as the transcriptional activator in the presence of CO even in E. coli cells. A dominant positive mutant of CooA, in which Met131 was replaced by Leu, was isolated by a random mutagenesis with this reporter system. The electronic absorption spectra of M131L mutant were identical to those of wild type CooA in oxidized (Fe3+), reduced (Fe2+), and CO-bound (CO-Fe2+) state, indicating that the coordination structure and environment of the heme were not changed by this mutation. Methionine at position 131 was the carboxyl-terminal end of the heme-binding domain of CooA, which would be adjacent to the hinge region connecting the heme-binding domain and the DNA-binding domain.

Bacterial Proteins↗

PubMed1997

Silicone-coated polypropylene hollow-fiber oxygenator: experimental evaluation and preliminary clinical use.

BACKGROUND: A membrane oxygenator consisting of a microporous polypropylene hollow fiber with a 0.2-microm ultrathin silicone layer (cyclosiloxane) was developed. Animal experimental and preliminary clinical studies evaluated its reliability in bypass procedures. METHODS: Five 24-hour venoarterial bypass periods were conducted on dogs using the oxygenator (group A). In 5 controls, bypass periods were conducted using the same oxygenator without silicone coating (group B). As a preliminary clinical study, 14 patients underwent cardiopulmonary bypass with the silicone-coated oxygenator. RESULTS: Eight to 16 hours (mean, 12.2 hours) after initiation of bypass, plasma leakage occurred in all group B animals, but none in group A. The O2 and CO2 transfer rates after 24 hours in group A were significantly higher than at termination of bypass in group B (p < 0.005 and p < 0.03, respectively). Scanning electron microscopy of silicone-coated fibers after 24 hours of bypass revealed no damage to the silicone coating of the polypropylene hollow fibers. In the clinical study, the oxygenator showed good gas transfer, acceptable pressure loss, low hemolysis, and good durability. CONCLUSIONS: This oxygenator is more durable and offers greater gas transfer capabilities than the previous generation of oxygenators.

Animals↗

PubMed1997

Changes in hemostatic parameters in hepatic veno-occlusive disease following bone marrow transplantation.

Hepatic veno-occlusive disease (VOD) is a major complication after bone marrow transplantation (BMT). Its prediction, diagnosis and treatment remain unclear. Examination was made of changes in hemostatic parameters in patients with or without VOD after BMT. Twenty-seven children were studied following BMT. Eight of them developed VOD. Tissue plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), thrombomodulin (TM), von Willebrand factor (vWF), factor VII, fibrinogen (FBG), FDP, D-dimer (D-D), plasminogen (PLG), thrombin-antithrombin III (TAT), alpha 2-plasmin inhibitor/plasmin complex (PIC), antithrombin III (AT-III), protein C, N-terminal propeptide for type III procollagen (P-III-P), were measured weekly from pre-BMT to day 28 after BMT. In VOD patients, t-PA and PAI-1 significantly increased (P < 0.05) and FBG significantly fell during the post-transplant period (P < 0.05). Significantly low AT-III and PLG were also noted before VOD (P < 0.05). There were no changes in other hemostatic parameters. t-PA, PAI-1 and FBG would thus appear useful markers for the diagnosis of VOD, and AT-III and PLG, predictive markers for VOD. The coagulation-fibrinolysis system following endothelial cell damage may contribute to the onset of VOD.

Adolescent↗

PubMed1997

Reconsideration of total erythrocyte destruction phenomenon.

During a particular long-term in vitro hemolysis test, the plasma free hemoglobin suddenly increased even though the hemolysis level had risen linearly for the previous several hours. This phenomenon was dubbed the total destruction of erythrocytes (TDE) phenomenon, and it was hypothesized that this was the result of the accumulation of sublethal damage to erythrocytes. It was suggested that the TDE might demonstrate the hemolytic characteristics of a pump more sensitively than a conventional hemolysis test. However, the previous report did not consider the effects of temperature or contamination. To study these effects, 3 long-term hemolysis tests were concluded under the following conditions. For Study 1 blood temperature was maintained at 27 degrees C (n = 2); for Study 2, at 37 degrees C (n = 4); and for Study 3, at 37 degrees C with gentamicin (n = 4). The BioMedicus and Nikkiso pumps were used as they were in our previous report. Gas sterilization of all circuits and pumps preceded experimentation. In Studies 1 and 3, hemolysis increased linearly for 29 h. However, in Study 2 a sudden increase of hemolysis occurred for both pumps. Possible causes of this were the dramatic changes in environmental factors such as severe acidosis, high O2 and glucose consumption, and CO2 accumulation. In contrast, neither Study 1 nor Study 3 showed a sudden increase in hemolysis. The plasma free hemoglobin increased linearly in both groups until 29 h of pumping. The environmental changes resulting from contamination were considered to be the cause of the sudden increase in hemolysis. In conclusion, the TDE did not reflect mechanical blood cell damage, but rather different environment situations. Hemolysis increased linearly up to 29 h in either 27 degrees C or germ-free conditions.

Animals↗

PubMed1997

[Treatments for T4 advanced lung cancer with invasion to the superior vena cava].

We discussed on the treatments for T4 lung cancer with invasion to the superior vena cava, whose prognosis has been poor. However, surgical resection may improve the prognosis compared with radiation therapy. The prosthetic replacement of superior vena cava can be done safely, and its patency is good in cases of ring-enforced ePTFE graft. Although superior vena caval obstruction syndrome had been a hard issue in the advanced cases, stenting in superior vena using the interventional radiological technique is a safe and reliable method. We should consider the stenting as the first choice for superior vena cava obstruction syndrome, because it makes the QOL improve so much.

Adult↗

PubMed1997

Synthesis of cyclodeca-1,5-diyne derivatives having o-nitrophenylseleno group.

7-Benzoyloxy-3-(2-nitrophenylseleno)-1,5-cyclodecadiyne (13) was prepared from 5-hexyn-1-ol and propargyl bromide via 10-iodo-7-(t-butyldiphenylsiloxy)-5,9-decadiynal (10). The facile cyclization of the acyclic precursor 10 would be rationalized in terms of "bulky group (TBDPSO) assisted conformational control". Oxidation of 13 by NaIO4, followed by thermal treatment gave tetrahydronaphthalene derivative 15, indicating the generation of biradical.

Antibiotics, Antineoplastic↗

PubMed1996

Ex vivo phase 1 evaluation of the DeBakey/NASA axial flow ventricular assist device.

A small ventricular assist device intended for long-term implantation has been developed by a cooperative effort between the Baylor College of Medicine and the NASA/Johnson Space Center. To date, in vitro tests have been performed to address hemolysis and pump performance issues. In this Phase 1 study, we assessed the durability and atraumatic features aiming for 2 day implantation. Eight pumps were implanted in 2 calves as paracorporeal left ventricular assist devices. The pump running times ranged from 18 to 203 h (78.1 +/- 23.7; mean +/- SEM). All the pump implantations were terminated because of thrombus formation. Plasma-free hemoglobin levels were below 13.7 mg/dl, except for 1 case complicated by inflow cannula obstruction. The pump speed was maintained between 10,100 and 11,400 rpm. Pump outputs were from 3.6 to 5.2 L/min. The electrical power required by the system ranged between 9 and 12 W. Clinically there was no detectable organ dysfunction noted, and postmortem evaluation demonstrated no pump related adverse effects in either calf except for small kidney infarctions. Thrombus deposition was observed mainly at the hub portions and the flow straightener.

Alanine Transaminase↗

PubMed1996

Development of a pivot bearing supported sealless centrifugal pump for ventricular assist.

Since 1991, in our laboratory, a pivot bearing-supported, sealless, centrifugal pump has been developed as an implantable ventricular assist device (VAD). For this application, the configuration of the total pump system should be relatively small. The C1E3 pump developed for this purpose was anatomically compatible with the small-sized patient population. To evaluate antithrombogenicity, ex vivo 2-week screening studies were conducted instead of studies involving an intracorporeally implanted VADs using calves. Five paracorporeal LVAD studies were performed using calves for longer than 2 weeks. The activated clotting time (ACT) was maintained at approximately 250 s using heparin. All of the devices demonstrated trouble-free performances over 2 weeks. Among these 5 studies, 3 implantations were subjected to 1-month system validation studies. There were no device-induced thrombus formations inside the pump housing, and plasma-free hemoglobin levels in calves were within the normal range throughout the experiment (35, 34, and 31 days). There were no incidents of system malfunction. Subsequently, the mass production model was fabricated and yielded a normalized index of hemolysis of 0.0014, which was comparable to that of clinically available pumps. The wear life of the impeller bearings was estimated at longer than 8 years. In the next series of in vivo studies, an implantable model of the C1E3 pump will be fabricated for longer term implantation. The pump-actuator will be implanted inside the body; thus the design calls for substituting plastic for metallic parts.

Blood Cell Count↗

PubMed1996

New method of evaluating sublethal damage to erythrocytes by blood pumps.

We recently proposed a new concept, the total destruction time of erythrocytes, to indicate sublethal damage to erythrocytes by blood pumps. In this article, results of additional experiments concerning this new concept are reported. Five paired in vitro hemolysis tests with bovine blood were conducted using a cone-type centrifugal pump (Group A) and an impeller-type pump (Group B). A total pressure head of 100 mm Hg was applied. The factors evaluated were the normalized index of hemolysis and the total destruction time, or the pumping duration, required to raise the level of the plasma-free hemoglobin to 50% of the total hemoglobin. The morphologic change of the erythrocytes also was analyzed. The percentage of crenated cells was calculated from blood smear specimens 1 min after starting the pumps and 2 h before the total destruction time of Group A in each experiment. Although there was no statistical difference in the normalized index of hemolysis between the two groups, the total destruction time of Group A erythrocytes was significantly shorter than that of Group B (18.9 +/- 4.5 h and 33.7 +/- 9.9 h in Group A and Group B, respectively; p < 0.02). The rate of crenated erythrocytes was higher in Group A than in Group B at a point 2 h before the total destruction time of Group A. The total destruction time values seem to define a good method for establishing sublethal traumatic damage to erythrocytes in blood pumps.

Animals↗

PubMed1996

Clinical experience with the Nikkiso centrifugal pump.

The Nikkiso HPM-15 is a minimally sized centrifugal pump. Preliminary results regarding clinical use of this pump for cardiopulmonary bypass (CPB) procedures have been reported previously. Recently, we have managed some additional cases using a newly developed controller. This article reports our clinical experiences with the use of this pump. We have managed 23 cases with a Nikkiso centrifugal pump. Twenty-two patients underwent CPB and 1 patient with fulminant viral myocarditis underwent percutaneous cardiopulmonary support (PCPS). With this pump, the circuit was extremely easy to prepare and deaeration was achieved readily. Hemodynamics during CPB and PCPS were stable in all cases. The increase in serum-free hemoglobin levels during CPB with this pump was as low as that seen in preliminary tests. A decrease in the platelet count was observed after the initiation of CPB with this pump; however, platelet counts returned to preoperative values 7 days after surgery. Moreover, urine output during CPB with this pump was as high as that seen in preliminary tests. No abnormalities in renal or liver function occurred during CPB. It appears that this new centrifugal pump is safe and easy to operate, and we conclude that it is useful for CPB and PCPS.

Adult↗

PubMed1995

Total erythrocyte destruction time: the new index for the hemolytic performance of rotary blood pumps.

To date an index of hemolysis is the only parameter to evaluate in vitro the hemolytic properties of blood pumps. However, this index does not reflect the sublethal conditions of erythrocytes. In this paper, a new concept, the total destruction of erythrocytes, to indicate traumatic features on erythrocytes is proposed. Five paired long duration in vitro hemolysis tests were conducted using the BioMedicus pump; BP80, and the Nikkiso pump, HMS12. The pumps ran until either a sudden change in blood color to dark red was noted or the pumps ran for over 24 h. At a certain point, the plasma-free hemoglobin levels suddenly and dramatically increased in each experiment except one Nikkiso case. At a certain point in time, the destruction of most erythrocytes suddenly and simultaneously occurred. We call this phenomenon total destruction of erythrocytes and define the pumping duration required to raise the level of the plasma-free hemoglobin to 50% of the total hemoglobin as total destruction time. Although there is no statistical difference in the normalized index of hemolysis between the two pumps, the total destruction time of the BioMedicus pump is significantly shorter than that of the Nikkiso pump. It appears that an accumulation of sublethal damage on erythrocytes resulted in the decrease of the hemolytic threshold of the entire erythrocyte and also resulted in a sudden entire destruction of erythrocytes.

Animals↗

PubMed1995

Initial clinical experience with the Baylor-Nikkiso centrifugal pump.

Recently, a newly developed centrifugal pump, the Baylor-Nikkiso pump, was approved for clinical use in the United States. This pump is the most compact centrifugal pump with a priming volume of only 25 ml. Although it is small, this pump can provide a flow of 4 L/min against a total pressure head of 300 mm Hg at 3,000 rpm. In vitro and in vivo validation of the Baylor-Nikkiso pump has proved that this pump could effectively reduce blood trauma even under high total head pressure. In addition, 48-h durability tests with biventricular bypass using calves verified the reliability of shaft sealing and antithrombogenicity. Clinical trials of the Baylor-Nikkiso pumps have been initiated in our department. This pump provides flows of 60-70 ml/kg/min with stable hemodynamic conditions. No leakage of thrombus formation was observed. The results of the initial clinical experience of the Baylor-Nikkiso pump suggest that it is suitable for cardiopulmonary bypass surgery.

Animals↗

PubMed1995

Left atrial myxomas. Using gross anatomic tumor types to determine clinical features and coronary angiographic findings.

PURPOSE: To our knowledge, there have been no reports focusing on differences of clinical characteristics according to two gross anatomic types of cardiac myxomas. This study evaluated the differences of clinical features, coronary arteriographic findings, and histopathologic findings. PATIENTS AND METHODS: Twenty-six patients who underwent surgical excisions for left atrial myxomas were analyzed. According to the gross anatomic types, they were divided into two groups: group 1 having solid and ovoid myxomas (n = 14), and group 2 having soft and papillary myxomas (n = 12). Differences of presenting symptoms, prevalence of brain infarction, coronary angiographic findings, and histopathologic findings were analyzed. RESULTS: An incidence of dyspnea was significantly higher in group 1 (78.6% vs 33.3%, p < 0.05) than in group 2. That of neurologic symptoms was higher in group 2 (75% vs 14.3%, p < 0.01) than in group 1. A prevalence of brain infarction was higher in group 2 (75% vs 2.5%, p < 0.05) than in group 1. On coronary angiography, an identification rate of clusters of tortuous vessels was higher in group 1 (81.8% vs 0%, p < 0.01) than in group 2. In histologic findings, most of group 1 tumors displayed many hemorrhages, small vessels, and fibrosis in the stroma, but group 2 had few such structures. CONCLUSIONS: Coronary angiographic findings of tumor-feeding arteries without clusters of tortuous tumor vessels predict a myxoma that is papillary in type. At that time, close attention should be given for the possible existence of silent brain infarction.

Adolescent↗