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Biomedical subjects

T Sueda

Publications and source records attributed to T Sueda.

At least 91 records · Page 5Linked to original sources
PubMed1998

Preparation and characterization of an Actinomyces naeslundii aggregation factor that mediates coaggregation with Porphyromonas gingivalis.

Intergeneric coaggregation is responsible for the complexity of the microbiota in human dental plaque and is believed to be important in the initial bacterial colonization of the human oral cavity. Actinomyces naeslundii, an early colonizer of the tooth surface, may enhance subsequent colonization by Porphyromonas gingivalis which is associated with adult periodontitis. The purpose of this study was to isolate and characterize the A. naeslundii aggregation factor (AnAF) that mediates coaggregation with P. gingivalis. AnAF was isolated from A. naeslundii sonic extract (SE) by gel filtration on a Sephacryl S-400HR, by hydrophobic interaction chromatography on a HiTrap Octyl Sepharose 4FF, and by ion exchange chromatography on a HiTrap Q. The specific activity increased 12-fold with a yield of 2.5%. SDS-PAGE analysis of AnAF revealed a protein band of high molecular weight in excess of 200 kDa. Carbohydrate was detected as the only material coinciding with the protein band, indicating that the AnAF was a glycoprotein. Immunoblotting analysis indicated that AnAF directly bound to P. gingivalis cells. AnAF was sensitive to sodium metaperiodate treatment but not to heat or protease treatments. These results suggest that the AnAF carbohydrate component mediated coaggregation with P. gingivalis cells. AnAF also inhibited coaggregation with other periodontal disease-associated bacteria such as Prevotella intermedia, Fusobacterium nucleatum, Capnocytophaga ochracea, but not streptococci.

Actinomyces↗
PubMed1998

Collateral flow detected by a Doppler guide wire in a case of vasospastic angina.

We could detect recruitable backward collateral flow in systole and diastole by using a Doppler guide wire during coronary artery spasm in a 42-year-old female among 20 patients with documented variant angina. The electrocardiogram (ECG) showed no ST-segment deviation, although she had chest pain and her coronary angiography showed a totally occluded right coronary artery. After administration of isosorbide dinitrate (ISDN) the collateral flow disappeared and the flow pattern recovered to normal. The good collateral flow pattern in patient with totally occluded coronary artery due to spasm was indicated to relieve myocardial ischemia, even when the patient felt chest pain.

Adult↗
PubMed1998

Simple right atrial procedure for chronic atrial fibrillation with atrial septal defect and aortic valvular regurgitation in an elderly patient.

A right atrial separation procedure was performed to eliminate atrial fibrillation (AF) during concomitant repair of an atrial septal defect and aortic valve regurgitation in an elderly patient. This procedure consisted of a Y-shaped incision in the right atrium, followed by cryoablation of the tricuspid annulus and the atrial septum. Only excision of the left atrial auricular appendage was performed in the left atrium. Although this procedure was devised to eliminate chronic AF associated with a solitary atrial septal defect, it was effective to eliminate chronic AF associated with atrial septal defect and aortic valve regurgitation in an elderly patient.

Aged↗
PubMed1998

Assessment of a new silicone tri-leaflet valve seamlessly assembled with blood chamber for a low-cost ventricular assist device.

We have developed a practical, low-cost ventricular assist device (VAD) comprising a newly designed blood chamber with a silicone lenticular sac and two silicone tri-leaflet valves (STV), made en bloc. This new VAD is seamless, can be made cost-effectively and assembled with the blood chamber and valve as one body. This novel design should reduce the incident of thrombus formation because of the absence of a junction at the connecting ring and because of the use of flexible silicone materials which have both antithrombogenecity and biocompatibility. In in vitro hemodynamics testing, a batch of 3 consecutively manufactured VADs with STVs underwent hydrodynamic functional testing. These showed less regurgitation, a lower value of water hammer phenomenon, and a slightly greater pressure gradient across the valves than a mechanical valve (MV) [Björk-Shiley monostrut valve]. The flow and pulsatile efficiency were adequate and similar to that of a VAD with MVs. In in vitro durability and hemolysis tests, a VAD with STV functioned well for 54 days and showed similar hemolytic profiles to a VAD with MVs. In an in vivo acute experiment using an adult sheep, our device was problem-free providing sufficient output as a left ventricular assist device (LVAD). Although it will be necessary to decrease the pressure gradient across this STV in the future, our device showed efficient performance as a practical land cost-effective VAD for short term use.

Adult↗
PubMed1998

Efficacy of a left atrial procedure for treatment of chronic atrial fibrillation in elderly patients.

A simple left atrial procedure for atrial fibrillation (AF) was performed in 16 elderly patients (age over 70 years old) with chronic AF associated with mitral and/or aortic valvular diseases. Chronic AF was eliminated upon discharge in 13 out of the 16 patients (81%). Twelve of the 13 patients (92%) whose AF had disappeared recovered the atrial kick of their right atrium, and 9 patients (70%) recovered the atrial kick of their left atrium. A simple surgical procedure to the left atrium was effective in the treatment of chronic AF associated with mitral valve disease in elderly patients. This simple procedure is preferable to other methods for the elimination of chronic AF with mitral valve disease in elderly patients.

Aged↗
PubMed1998

The significance of atrial monophasic action potentials for monitoring rat cardiac allograft rejection.

BACKGROUND: Changes in the monophasic action potential may be used for detecting early acute rejection in the transplanted rat heart. METHODS: Heterotopic heart transplantations were performed in allogeneic and syngeneic rats. During atrial pacing, monophasic action potentials were simultaneously recorded in the right atrium and ventricle of the transplanted hearts on postoperative days 1, 3, and 5. The amplitude and duration of monophasic action potentials, atrioventricular conduction time, and cardiac intervals were analyzed. Histopathologic examination for rejection was performed on postoperative days 1, 3, and 5. RESULTS: In the allogeneic group, monophasic action potential amplitude progressively decreased, and monophasic action potential duration gradually increased after heart transplantation in the atrium and ventricle. With rejection, the amplitude decreased to a greater extent, and monophasic action potential duration increased to a greater extent in the atrium than in the ventricle on day 3. The atrioventricular conduction time increased on day 5, but the cardiac interval did not change. An inverse correlation between histopathologic grade and the monophasic action potential amplitude, and a positive correlation between histopathologic grade and the monophasic action potential duration existed for both the atrium and ventricle. These electrophysiologic and histopathologic changes were not observed in the syngeneic group. CONCLUSIONS: We conclude that right atrial monophasic action potentials may be a useful and reliable indicator of early acute heart transplant rejection.

Acute Disease↗
PubMed1998

Three different approaches to spinal cord monitoring for the prediction of spinal cord ischemia during thoracic aortic aneurysm surgery.

We report the case of a 66-year-old man who had a descending thoracic aneurysm, diagnosed as aortitis syndrome. He subsequently underwent an aneurysmectomy under simultaneous sensory and motor spinal cord monitoring. Spinal cord ischemia was diagnosed during prosthetic replacement of the aneurysm by changes in evoked spinal cord potentials and motor evoked potentials from the lumbar spinal cord enlargement and 2 pairs of intercostal arteries were reconstructed at the level of T9 and 10. After surgery, the patient developed paraparesis below T10, but the resulting neurological deficits were overcome with postoperative rehabilitation. Simultaneous monitoring of evoked spinal cord potentials and motor evoked potentials were useful in evaluating spinal cord ischemia during aortic aneurysm surgery and in determing whether intercostal arteries should be reconstructed.

Aged↗
PubMed1997

Efficacy of a simple left atrial procedure for chronic atrial fibrillation in mitral valve operations.

BACKGROUND: We have devised a simple surgical procedure to be performed on the posterior wall of the left atrium for the treatment of chronic atrial fibrillation (AF) associated with mitral valve disease. The effectiveness of this procedure for serial mitral valve operations was then evaluated. We postulated that chronic AF associated with mitral valve disease could be attributable to a distended left atrium. The refractory period of the distended left atrium was significantly shorter in the left posterior atrial wall, especially at the base of the left atrial appendage and at the orifice of the left posterior pulmonary vein. We hypothesized that the left posterior atrial wall with its shorter fibrillatory cycle length would act as a driver for maintaining the AF, and therefore, surgical ablation of this critical area in the left atrium could terminate the chronic AF. METHODS: The surgical patients were divided into two groups. In group 1 (control group), 15 patients with chronic AF were operated on by the mitral valve procedure only. In group 2, 36 patients underwent this procedure in combination with a concomitant mitral valve operation. The disappearance rate of the AF was estimated by electrocardiography, and atrial function was estimated by transthoracic and transesophageal echocardiography. RESULTS: The chronic AF had been reduced significantly or eliminated at discharge in 4 of 15 patients (26.7%) in the group 1, versus 31 of 36 patients (86%) in group 2 (p < 0.05). In group 2, 29 of the 31 patients (94%) whose AF had disappeared recovered the atrial kick of their right atrium, and 21 patients (22/31; 71%) recovered the atrial kick of their left atrium. CONCLUSIONS: Surgical ablation of the posterior wall of the left atrium was effective in the treatment of chronic AF associated with mitral valve disease. This simple procedure could restore a sinus rhythm and also recovered atrial systolic function. We conclude that the left atrium may act as a driver for sustaining AF in mitral valve disease.

Aged↗
PubMed1997

Right atrial separation for chronic atrial fibrillation with atrial septal defects.

A right atrial separation procedure was performed for the ablation of atrial fibrillation during the concomitant repair of an atrial septal defect. This procedure consisted of a Y-shaped incision in the right atrium, followed by cryoablation of the tricuspid annulus and the atrial septum without any procedures performed on the left atrium. This is a simple and effective method for the elimination of chronic atrial fibrillation associated with atrial septal defects in adults.

Atrial Fibrillation↗
PubMed1997

Flow velocity of central retinal artery and retrobulbar vessels during cardiovascular operations.

OBJECTIVE: Both blood flow monitoring and pressure monitoring are necessary to avoid inadequate cerebral perfusion during cardiovascular operations. Inasmuch as transcranial Doppler ultrasonography does not provide a consistently good signal, especially during cardiopulmonary bypass, we examined the blood flow through the central retinal artery, which has proved to reflect an obstruction of the carotid artery. METHOD: Twenty-eight consecutive cases were examined with a 5 or 7.5 MHz conventional echocardiographic probe. Correlation between the maximal velocity at the central retinal artery and systolic blood pressure was examined. The blood flow of the central retinal artery and retrobulbar vessels was examined during selective or retrograde cerebral perfusion or intraaortic balloon pumping. RESULTS: Blood flow could be clearly visualized but disappeared below a certain pressure in every case. With data from 478 measuring points, systolic blood pressure correlated with maximal velocity (r = 0.6902, p < 0.0001). The blood pressure-axis intercept, known as "critical closing pressure," was 35.8 +/- 14.8 mm Hg, varying among individuals and bilateral eyes. Pulsatility index increased after cardiopulmonary bypass (1.095 +/- 0.245 to 1.525 +/- 0.268, p < 0.0001). Patency of the circle of Willis was confirmed by the blood flow during anastomosis of the ipsilateral artery. During retrograde cerebral perfusion, blood flow was detectable at the retrobulbar vessels. During intraaortic balloon pumping, the central retinal artery flow was augmented on inflation of the balloon. CONCLUSION: Orbital vessel monitoring provides the critical closing pressure of the central retinal artery and confirms patency of the circle of Willis. The eye can be "an acoustic window" into intracranial blood flow during cardiovascular surgery.

Aged↗
PubMed1997

Calcium and silicon from bioactive glass concerned with formation of nodules in periodontal-ligament fibroblasts in vitro.

Previously, the authors reported that bioactive glass promoted formation of nodules in cultured periodontal-ligament fibroblasts and high concentrations of calcium and silicon were detected in the culture medium. Herein, the effects of bioactive glass, calcium alone and calcium and silicon for formation of nodules on the periodontal-ligament fibroblasts are examined. The cells were cultured with bioactive glass, without bioactive glass, calcium and silicon, with calcium alone and with calcium and silicon. The cell growth, alkaline-phosphatase activity, amount of pro-collagen type I and the number of nodules were measured periodically until the 21st day. The cell growth rate with calcium and silicon was the highest, however the rate with bioactive glass and calcium alone were similar to that without them. The alkaline-phosphatase activity and the amount of pro-collagen showed peaks at the 11th day. At the peak, the alkaline-phosphatase activity with bioactive glass or calcium and silicon, and the pro-collagen with bioactive glass was higher than without them. The number of nodules with bioactive glass, calcium alone or calcium and silicon was greater than without them. These findings suggested that the combination of calcium and silicon released from bioactive glass was concerned with the formation of nodules on the periodontal-ligament cells.

Alkaline Phosphatase↗
PubMed1997

Development of a direct mechanical left ventricular assist device for left ventricular failure.

We have developed a direct mechanical left ventricular assist device (DMLVAD) for severe left ventricular failure. The DMLVAD was attached to the left ventricle and compressed the heart by a pneumatic driving unit. In a mock circulation model with an extracted nonbeating heart, a cardiac output (CO) of 1.93 L/min was obtained at a driving pressure of 200 mm Hg. In a canine left ventricular failure model induced by injection of sodium hydroxide into the myocardium, the systolic arterial pressure, systolic left ventricular pressure, maximum LV dP/dt, peak flow, and CO increased by 21, 24, 58, 144, and 37%, respectively. The mean left atrial pressure also decreased by 15% when the DMLVAD was driven. These effects were most prominent when the mean left atrial pressure was over 15 mm Hg, and the driving pressure was over 100 mm Hg. Compression at late systole was more effective in obtaining greater CO. We suggest that the DMLVAD could be an optional circulatory assist device for patients with left ventricular failure awaiting heart transplantation.

Animals↗
PubMed1997

Development of an intravascular pumping oxygenator using a new silicone membrane.

A new intravascular pumping oxygenator (IVPO) was developed for intravascular gas exchange and circulatory assistance in critically ill patients with respiratory and circulatory failure. The IVPO utilizes new silicone hollow fibers (diameter, 1 mm; membrane width, 50 microns) and consists of two driving tubes for the oxygenation and pumping of circulating blood. The performance characteristics of the IVPO were studied using an experiment ex vivo model. With a mean hemoglobin concentration of 10.5 +/- 2.3 g/dl, total oxygen transfer was 5.6 +/- 1.5 ml/min at a blood flow of 200 ml/min and 6.3 +/- 2.2 ml/min at a blood flow of 250 ml/min. Total CO2 transfer was 3.8 +/- 1.4 ml/min at a blood flow of 200 ml/min and 4.2 +/- 1.6 ml/min at a blood flow of 250 ml/min. Blood flow increased to a maximum of 250 ml/min during IVPO pumping. This preliminary experiment demonstrated that the IVPO has the capacity to function both as circulatory assist pump and as an intravascular hollow fiber oxygenator.

Animals↗
PubMed1997

Trial manufacture of eccentric roller type total artificial heart.

Working toward a completely implantable total artificial heart, we have designed an eccentric roller type total artificial heart. The actuator of this artificial heart is a drum type eccentric roller that squeezes the blood chambers. The blood chambers are made of silicone rubber and are torus in shape. The shape of the artificial heart is an almost circular cylinder, and its length and diameter are 10 cm and 8 cm, respectively. The 2 main characteristics of this artificial heart are that it discharges blood in a pulsatile mode and that it requires no reversing of the motor. Because we have not completed the artificial heart yet, we have tested the eccentric roller mechanism on the prototype with an overflow type mock circulation with a 100 mm Hg afterload. The prototype worked at the roller speeds of 50, 100, and 150 rpm with flow rates of 1.7, 3.7, and 5.4 L/min, respectively. Next the prototype was connected to a Donovan type mock circulatory system and worked at roller speeds of 88-214 rpm with flow rates of 3.0-8.4 L/min against mean afterloads of 82-120 mm Hg.

Biocompatible Materials↗
PubMed1997

Right atrial separation procedure for eliminating chronic atrial fibrillation associated with atrial septal defect.

Chronic atrial fibrillation (AF) had been documented in a patient with atrial septal defect for 7 years. A right atrial separation procedure was performed for ablation of chronic AF, concomitant with repair of the atrial septal defect, and followed by atrial electrophysiological mapping. A horizontal transectional incision extending to the borders of the atrial septum and the tricuspid annulus was made. Cryolesions of the atrial isthmus between the margin of the upper incision and the tricuspid valve annulus were created at -60 degrees C for 2 minutes at a time. After the operation, the patient had restored normal sinus rhythm during a subsequent follow-up period of 48 months.

Atrial Fibrillation↗
PubMed1997

A novel component different from endotoxin extracted from Prevotella intermedia ATCC 25611 activates lymphoid cells from C3H/HeJ mice and gingival fibroblasts from humans.

A novel immunobiologically active fraction was prepared from a phenol-water extract of Prevotella intermedia ATCC 25611 by Sephadex G-100 column chromatography. The fraction consisted mainly of carbohydrate and protein and was devoid of fatty acid. The fraction showed high-molecular-weight bands (10,000 to 12,000) on deoxycholate polyacrylamide gel electrophoresis (DOC-PAGE) and was scarcely active in a Limulus test. We designated the fraction Prevotella glycoprotein (PGP). The PGP fraction showed strong mitogenicity on splenocytes and cytokine-inducing activities on peritoneal macrophages from both C3H/HeJ and C3H/HeN mice, and it stimulated human gingival fibroblasts to produce cytokines. The activities of the PGP fraction were resistant to heat inactivation (100 degrees C for 1 h) and protease treatments and were scarcely inhibited by polymyxin B. In contrast, the purified lipopolysaccharide fraction (LPS-PCP) extracted from the same bacterium with a phenol-chloroform-petroleum ether mixture, which showed strong Limulus activity and a single low-molecular-weight band (approximately 3,000) on DOC-PAGE, lacked the activities on splenocytes and macrophages from C3H/HeJ mice and human gingival fibroblasts. The activities of the LPS-PCP fraction on cells from C3H/HeN mice were completely inhibited by polymyxin B. The LPS extracted from the same bacterium with hot phenol-water (LPS-PW) exhibited the properties of both the PGP fraction and the LPS-PCP fraction. These findings suggest that the unique bioactivities of the LPS-PW fraction of oral black-pigmented bacteria reported to date, which differed from those of the classical endotoxin, were derived from the PGP fraction and not from the LPS itself.

Adjuvants, Immunologic↗
PubMed1997

Effect of acute renal failure on the distribution of iomeprol, a nonionic contrast agent, to cerebrospinal fluid in rats.

The effect of acute renal failure on the pharmacokinetics concerning the cerebrospinal fluid (CSF) distribution of iomeprol, a nonionic contrast agent, was studied. The concentrations of iomeprol in the plasma and CSF were measured after intravenous (i.v.) administration at the dose of 50 or 500 mg/kg body weight. The time courses of plasma and CSF concentration were linear within the dose studied. Influx and efflux clearances estimated by simultaneous fitting were 4.6 x 10(-5) ml/min and 8.8 x 10(-4) ml/min, respectively, which suggested that the distribution of iomeprol to CSF low and linear. The distribution volume at steady state was 300-500 ml/kg, suggesting that iomeprol was readily distributed to the extracellular space but hardly distributed to the intercellular space. Total body clearance (9-13 ml/min/kg) indicated that iomeprol was mainly excreted by glomerular filtration. In the rat with acute renal failure induced by ligating the binary ureters, the concentration of iomeprol in CSF after i.v. administration of 500 mg/kg dose was much higher than that in the intact rat according to the delay of elimination from plasma (CLtot = 0.07 ml/min/kg). However, the time course of iomeprol concentration in CSF was predictable using the values of the influx clearance to CSF and the efflux clearance from CSF determined by intact rats. In conclusion, renal failure is one risk factor for central nervous system toxicity because of decreased total body clearance, while acute renal failure may not affect the transport of iomeprol to CSF.

Acute Kidney Injury↗