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Biomedical subjects

A Usui

Publications and source records attributed to A Usui.

At least 91 records · Page 5Linked to original sources
PubMed1994

Comparative experimental study between retrograde cerebral perfusion and circulatory arrest.

To evaluate the efficacy of retrograde cerebral perfusion in protecting the brain, we comparatively studied retrograde cerebral perfusion and total circulatory arrest in 18 hypothermic (20 degrees C) mongrel dogs (retrograde cerebral perfusion, n = 10; total circulatory arrest, n = 8). Retrograde cerebral perfusion was performed, maintaining an external jugular venous pressure of 25 mm Hg for 60 minutes. Retrograde cerebral perfusion provided half the cerebral blood flow and a third of the oxygen that was supplied during hypothermic cardiopulmonary bypass, which had a flow rate of 100 ml/min per kilogram. Oxygen consumption and carbon dioxide exudation did not increase on resuming cardiopulmonary bypass after retrograde cerebral perfusion, whereas they increased after total circulatory arrest (oxygen consumption 10.7 +/- 5.3 versus 19.1 +/- 8.6 ml/min, p < 0.05; carbon dioxide exudation, 0.92 +/- 0.54 versus 1.64 +/- 0.78 mmol/min, p < 0.05). Therefore, oxygen debt during retrograde cerebral perfusion was smaller than during total circulatory arrest. Retrograde cerebral perfusion also cooled the brain better than did total circulatory arrest (20.4 degrees +/- 1.5 degrees C versus 22.7 degrees +/- 0.7 degrees C, p < 0.01). Cerebral tissue oxygen tension decreased slightly (27.5 +/- 7.7 versus 12.3 +/- 3.0 mm Hg, p < 0.01), and cerebral tissue carbon dioxide tension increased slowly during retrograde cerebral perfusion (95 +/- 34 versus 147 +/- 44 mm Hg, p < 0.05). These changes were smaller than those seen in total circulatory arrest. Tissue concentrations of adenosine triphosphate in the brain remained relatively high during retrograde cerebral perfusion but decreased rapidly during total circulatory arrest (0.49 +/- 0.16 versus 0.21 +/- 0.05 mmol/gm, p < 0.01, just before resuming cardiopulmonary bypass). Retrograde cerebral perfusion cannot maintain aerobic metabolism but may reduce ischemic damage of the brain and may safely extend the cerebral circulation interruption time.

Adenosine Triphosphate↗
PubMed1994

Determination of optimum retrograde cerebral perfusion conditions.

Retrograde cerebral perfusion through a superior vena caval cannula is a new technique used to protect the brain during operations on the aortic arch. We measured cerebral tissue blood flow, oxygen consumption, and cerebrospinal fluid pressure under various perfusion conditions in hypothermic (20 degrees C) mongrel dogs (n = 18, 12.8 +/- 0.6 kg) to determine the optimum conditions for retrograde cerebral perfusion. Retrograde cerebral perfusion was performed by infusion via the superior vena caval cannula and drainage via the ascending aortic cannula while the inferior vena cava and azygos vein were clamped. Retrograde cerebral perfusion was performed as the external jugular venous pressure was changed from 15 to 35 mm Hg in increments of 5 mm Hg. Cerebral tissue blood flow was measured by the hydrogen clearance method. Hypothermic retrograde cerebral perfusion with an external jugular venous pressure of 25 mm Hg provided about half the cerebral tissue blood flow of hypothermic (20 degrees C) cardiopulmonary bypass with a flow rate of 1000 ml/min (13.7 +/- 7.9 versus 32.7 +/- 8.5 ml/min per 100 gm). It decreased significantly as the external jugular venous pressure was decreased from 25 to 15 mm Hg but did not increase significantly as the external jugular venous pressure was increased from 25 to 35 mm Hg. Whole-body oxygen consumption during hypothermic retrograde cerebral perfusion with an external jugular venous pressure of 25 mm Hg was one quarter of that during hypothermic cardiopulmonary bypass (3.4 +/- 0.7 versus 12.7 +/- 5.6 ml/min) and varied in proportion to external jugular venous pressure. The cerebrospinal fluid pressure was a little lower than the external jugular venous pressure (19.2 +/- 4.5 mm Hg versus 24.8 +/- 2.4 mm Hg) but also varied with the external jugular venous pressure. The cerebrospinal fluid pressure remained lower than 25 mm Hg so long as the external jugular venous pressure remained lower than 25 mm Hg. High external jugular venous pressure was associated with high intracranial pressure, which restricts cerebral tissue blood flow and may cause brain edema. We believe that a venous pressure of 25 mm Hg is the optimum condition for retrograde cerebral perfusion.

Animals↗
PubMed1993

Effects of magnesium on isolated canine coronary arterial tension.

The effects of magnesium on the tension of isolated canine coronary arterial strips were studied. In the solution containing K+ of 20 mEq.l(-1), Ca2+ of 4 mEq.l(-1), and Na+ of 127 mEq.l(-1), the tension was 811 +/- 111 mg with Mg2+ of 1 mEq.l(-1), 494 +/- 135 mg with Mg2+ of 10 mEq.l(-1), 272 +/- 126 mg with Mg2+ of 20 mEq.l(-1), -52 +/- 63 mg with Mg2+ of 30 mEq.l(-1), -69 +/- 80 mg with Mg2+ of 40 mEq.l(-1). In the solution containing K+ of 20 mEq.l(-1), Na+ of 12 mEq.l(-1) and Ca2+ of 0 mEq.l(-1), the tension was 102 +/- 22 mg with Mg2+ of 1 mEq.l(-1), 3 +/- 35 mg with Mg2+ of 10 mEq.l(-1), -49 +/- 33 mg with Mg2+ of 20 mEq.l(-1), -59 +/- 49 mg with Mg2+ of 30 mEq.l(-1), -65 +/- 54 mg with Mg2+ of 40 mEq.l(-1). The data demonstrated that Mg2+ above 30 mEq.l(-1) inhibited the increase in tension caused by Ca2+ and Mg2+ above 20 mEq.l(-1) inhibited the increase in tension caused by low Na+ concentration.

Journal Article↗
PubMed1993

Sandwich repair with two sheets of equine pericardial patch for acute posterior post-infarction ventricular septal defect.

A 74-year-old man, who had posterior post-infarction ventricular septal defect, was treated successfully by early surgical repair with a sandwich technique involving two sheets of equine pericardial patch. In this technique the ventricular septal defect (VSD) was exposed through a trans-infarction approach. The inside patch covered the VSD and ventriculotomy from the inside. The outside patch generously covered the infarcted myocardium. The two patches completely sandwiched the infarcted myocardium including the VSD and ventriculotomy with eighteen interrupted sutures. This technique ensures strong fixation of the VSD, reducing the risk of bleeding and recurrence of VSD, and also maintains the proper shape and size of the left ventricle without the danger of ventricular aneurysm formation.

Aged↗
PubMed1993

Efficient adsorption of lysostaphin on bacterial cells of lysostaphin-resistant Staphylococcus aureus mutant.

A simple and efficient method for the purification of staphylolytic endopeptidase (lysostaphin) contained in culture supernatant of Staphylococcus simulans biovar staphylolyticus strain by adsorption of the enzyme on bacterial cells of lysostaphin-resistant S. aureus mutant was successfully devised. Lysostaphin was sufficiently absorbed on the heat-killed mutant cells derived from S. aureus Cowan I and efficiently eluted by 3 M KSCN. Enzyme preparation obtained by a single procedure of the affinity purification was pure enough for practical use. The yield of the enzyme was 25 mg from 1 liter culture and recovery rate was 64%.

Adsorption↗
PubMed1993

Effects of cytochalasins B and D on Staphylococcus aureus adherence to and ingestion by mouse renal cells from primary culture.

Cytochalasin B (CB) and cytochalasin D (CD), inhibitors of microfilament function of host cell, were examined for their effects on Staphylococcus aureus Cowan I adherence to and ingestion by several types of the hyperosmolarity-tolerant (HOT) cells obtained from primary culture of mouse kidney. Staphylococcal adherence to the HOT cells with epithelial appearance was extraordinarily enhanced by the treatment of those cells with both 5 micrograms/ml of CB and CD. In particular, staphylococci adhered to the periphery rather than the center of each cytochalasin-treated cell. Staphylococcal ingestion by all types of the HOT cells was markedly inhibited by CD in spite of the enhanced adherence. Contrary to our expectation, inhibition by CB was incomplete, and the enhanced adherence of staphylococci to CB-treated cells resulted in the enhanced ingestion.

Actin Cytoskeleton↗
PubMed1993

Effect of pravastatin on human sleep.

To evaluate the effect of pravastatin, an HMG-CoA reductase inhibitor, on sleep, the drug or a placebo was administered to 5 healthy adults for 16 days by the double-blind method. Pravastatin caused no changes in sleep parameters. This indicates that it had no effect on human sleep for the following possible reasons: Being hydrophilic, the drug does not readily cross the blood-brain barrier. It does not inhibit prostaglandin D2 synthase, a possible sleep-inducing substance. It was thought that a decrease in the total cholesterol level in the blood has no effect on sleep in healthy adults.

Adult↗
PubMed1993

Cerebral metabolism and function during normothermic retrograde cerebral perfusion.

Retrograde cerebral perfusion through a superior vena cava (SVC) cannula is a new technique used to protect the brain during circulatory arrest. Cerebral blood flow, oxygen consumption, blood sugar consumption and auditory brain stem responses were measured at various rates (100, 200 and 300 ml min-1) of retrograde cerebral perfusion in normothermic mongrel dogs (n = 12, body-weight 13-15 kg). During perfusion about 20% of the perfusate from the SVC was returned via the aorta, while the rest drained into the inferior vena cava. External jugular venous pressure increased as the perfusion rate increased (mean(s.d.) 26.0(6.4) mmHg at a rate of perfusion of 300 ml min-1). Oxygen and blood sugar consumption also increased as the rate of perfusion increased. Retrograde cerebral perfusion at 300 ml min-1 provided half of the cerebral blood flow (mean(s.d.) 14.7(6.4) versus 34.3(7.8)ml min-1) of antegrade cardiopulmonary bypass (CPB). Analysis of the blood returned through the aorta during perfusion at a rate of 300 ml min-1 showed that mean(s.d.) oxygen consumption was about one-third (4.4(2.1) versus 12.3(7.1) ml min-1) and blood sugar consumption about 15% (17(22) versus 114(54)mg min-1) of that seen in blood returned through the SVC during CPB. Auditory brain stem responses disappeared immediately when perfusion was started but recovered completely as soon as CPB was resumed. Although the oxygen provided by perfusion was not sufficient to maintain cerebral function, it should help protect the brain during circulatory arrest.

Animals↗
PubMed1993

Nafamostat mesilate reduces blood loss during open heart surgery.

BACKGROUND: Nafamostat mesilate (FUT-175) is a protease inhibitor inactivating coagulation, fibrinolysis, and platelet aggregation. A prospective, randomized trial was performed to assess the efficacy of FUT-175 in the reduction of postoperative bleeding tendency. METHODS AND RESULTS: FUT-175 was infused at a rate of 40 mg/h during cardiopulmonary bypass (CPB) along with 300 IU/kg of heparin in 20 patients undergoing aortocoronary bypass surgery (FUT group). This group was compared with another group of 20 patients undergoing aortocoronary bypass surgery, who were given only heparin (control group). Blood concentrations of FUT-175 and activated clotting time increased after cooling, peaking at 2050 +/- 1190 ng/mL and 2136 +/- 983 seconds at the lowest temperature and recovered after rewarming to values of 166 +/- 118 ng/mL and 510 +/- 148 seconds, respectively, at the end of CPB. In the FUT group, platelet counts were significantly higher at the end of CPB than those in the control group (168 +/- 10 versus 136 +/- 9 x 10(3)/mm3, P < .05). In the FUT group, serum concentrations of beta-thromboglobulin (307 +/- 102 versus 537 +/- 391 ng/mL, P < .05), PIC (3.6 +/- 1.7 versus 5.8 +/- 3.8 micrograms/mL, P < .05) and FDP (20.2 +/- 7.0 versus 41.4 +/- 11.9 ng/mL, P < .01) were significantly lower than those in the control group at the end of CPB. However, serum concentrations of TAT, FPA, and FPB beta 15-42 showed no significant differences between groups. FUT-175 significantly reduced heparin dosage and 24-hour postoperative blood loss (19,200 +/- 3200 versus 29,100 +/- 7700 IU, P < .01, and 382 +/- 129 versus 576 +/- 375 mL, P < .05). CONCLUSIONS: FUT-175 inhibits fibrinolysis and preserves platelet counts and function during CPB and reduces blood loss during open heart surgery.

Benzamidines↗
PubMed1993

[Clinical experience in extracorporeal shock wave lithotripsy with Sonolith 3000 for urinary stones].

Extracorporeal shock wave lithotripsy (ESWL) using Sonolith 3000 was performed on 153 patients with urolithiasis form October, 1990 to April, 1992. The location of the stone was as follows; kidney in 70 cases, ureter in 82 cases and a Kock reservoir in one case. A double J catheter was installed in 6 cases before ESWL. Epidural anesthesia was required in 4 cases because of severe pain. Among 149 cases available for follow up one month after ESWL, 119 cases (79.9%) became stone free and 19 cases (12.8%) retained stone fragments less than 4 mm in diameter. The effectiveness rate, calculated as the sum of the cases stated above, was 92.7%. A side effect was observed in one case which was perirenal hematoma but required no therapy.

Adolescent↗
PubMed1993

[Cerebral renal and hepatic tissue blood flow during retrograde inferior vena caval perfusion--an experimental study in dogs].

Cerebral tissue blood flow (CBF), renal tissue blood flow (RBF), hepatic tissue blood flow (HBF), and oxygen metabolism have been measured in 8 mongrel dogs which underwent hypothermic (20 degrees C) retrograde perfusion via the inferior vena cava (IVC). IVC perfusion was performed with aortic drainage and cross-clamping of superior vena cava (SVC) at IVC pressures of 20 or 30 mmHg. CBF, RBF, and HBF at 30 mmHg of IVC pressure were 10.4 +/- 6.8, 11.4 +/- 5.5, and 19.2 +/- 11.3 mL/min/100 g. These values were 33%, 47%, and 64% of those observed with a cardiopulmonary bypass and flow rate of 1000 mL/min, and 77%, 112%, and 168% of those observed with retrograde cerebral perfusion via the both internal maxillary veins at 25 mmHg of SVC pressure. Oxygen consumption at this time was 3.78 +/- 1.77 mL/min. CBF, RBF, HBF, and oxygen consumption at 20 mmHg of IVC pressure were 7.7 +/- 4.8, 7.5 +/- 4.7, and 9.9 +/- 4.7 mL/min/100 g and 2.02 +/- 0.72 mL/min, respectively. As IVC pressure increased, CBF, RBF, HBF, and oxygen consumption increased. However, high IVC pressure by the retrograde perfusion was associated with high portal venous pressure, which would cause ascites. IVC perfusion can supply some amount of blood flow to the liver and kidney. It may therefore be advantageous to maintain proper IVC pressure to protect the abdominal organs during systemic arterial circulatory arrest under deep hypothermia.

Animals↗
PubMed1992

Retrograde cerebral perfusion through a superior vena caval cannula protects the brain.

Retrograde cerebral perfusion through a superior vena caval cannula is a new technique for protecting the brain during aortic arch operations. In mongrel dogs (n = 10; 13 to 15 kg) we have performed retrograde cerebral perfusion (300 mL/min) by infusing blood through a superior vena caval cannula with aortic and inferior vena caval drainage. We have measured the cerebral tissue blood flow, oxygen consumption, and carbon dioxide exudation during retrograde cerebral perfusion at normothermia (NT, 37 degrees C) and hypothermia (HT, 20 degrees C) and have compared these values with values obtained in dogs during cardiopulmonary bypass (1,200 mL/min). Cerebral tissue blood flow was measured by the hydrogen clearance method. During retrograde cerebral perfusion about 20% of the superior vena caval perfusate was returned through the aorta and the rest drained from the inferior vena cava. Cerebral vascular resistance during retrograde cerebral perfusion was lower than that during cardiopulmonary bypass (NT, 63.8 +/- 52.5 versus 126.9 +/- 58.4; HT, 28.4 +/- 32.8 versus 69.5 +/- 28.7 x 10(3) dynes.s.cm(-5). Retrograde cerebral perfusion provided half the cerebral tissue blood flow of cardiopulmonary bypass (NT, 14.7 +/- 6.4 versus 34.3 +/- 7.8; HT, 17.6 +/- 5.6 versus 37.2 +/- 10.6 mL/min). Retrograde cerebral perfusion also provided a third of the oxygen (NT, 4.4 +/- 2.1 versus 12.3 +/- 7.1; HT, 1.4 +/- 0.8 versus 4.2 +/- 1.3 mL/min) and discharged 20% of the carbon dioxide (NT, 0.24 +/- 0.08 versus 1.19 +/- 0.58; HT, 0.15 +/- 0.06 versus 0.51 +/- 0.17 mmol/min) when compared with cardiopulmonary bypass. Retrograde cerebral perfusion may reduce ischemic damage during interruption of cerebral blood flow.

Animals↗
PubMed1992

Intracellular localization of Staphylococcus aureus within primary cultured mouse kidney cells.

Staphylococcus aureus Cowan I was incubated with monolayers of cells derived from several portions of mouse kidney, and found to be ingested by all types of the renal cells. Intracellular localization of S. aureus was determined by resistance of intracellular cocci against lysostaphin digestion and confirmed by electron microscopy. From renal medulla, three morphological variants of the hyperosmolarity-tolerant (HOT) cells were obtained. The rate of cocci-ingesting cells varied from 16.9% to 93.4% among these of the HOT cells at the end of 3-hr incubation. From renal cortex, three morphological variants of epithelial cells grew in medium RK-1. Among them, only the cells on the edge of colony ingested Cowan I, while the epithelial cells on the center of colony ingested few cocci. Transferred from medium RK-1 to MEM supplemented with 10% FBS, part of the cortical cells changed into fibroblast-like appearance and obtained the capacity to ingest Cowan I. This result may indicate the correlation between ingesting capacity and cellular morphology. From a glomerulus, epithelial (GE) cells and fibroblast-like (GF) cells were obtained. The GE cells ingested not only S. aureus Cowan I but Staphylococcus epidermidis and Staphylococcus saprophyticus after 30-min incubation, while the GF cells, like both of the HOT cells and the cortical cells, ingested only S. aureus. These results suggest a possibility that S. aureus is located within nonprofessional phagocytes during its infection and intracellular coccus plays an important role in its pathogenicity.

Animals↗
PubMed1992

Conspicuous ingestion of Staphylococcus aureus organisms by murine fibroblasts in vitro.

A conspicuous adhesion of Staphylococcus aureus organisms to murine cutaneous fibroblasts and NIH/3T3 cells cultured in vitro and subsequent ingestion of S. aureus organisms by these fibroblasts are described. In the present experimental system, only fibroblasts-adhering S. aureus organisms were efficiently ingested by fibroblasts unlike S. epidermidis and S. saprophyticus. These findings might suggest a correlation between the pathogenesis of S. aureus and its intracellular localization in non-professional phagocytes such as fibroblasts in a special reference to its higher pathogenicity than those of coagulase negative counterparts.

3T3 Cells↗
PubMed1992

Manganese-containing superoxide dismutase in blood and urine during open-heart surgery.

Concentrations of Manganese-containing superoxide dismutase (Mn-SOD) were measured perioperatively by enzyme immunoassay in serial samples of arterial and coronary sinus blood and urine taken from 18 patients undergoing mitral valve surgery. The mean Mn-SOD concentration in the arterial blood samples was 66.2 (SD 16.1 ng/ml) at induction of anesthesia, increased gradually after reperfusion and peaked on the 2nd post-operative day [150 (SD 58.3) ng/ml]. The mean concentration of Mn-SOD in the coronary sinus blood samples was significantly higher than in the arterial samples only at the 6th hour after reperfusion [97 (SD 21.8) ng/ml vs 90.3 (SD 20.9) ng/ml, p < 0.05]. Although concentrations of Mn-SOD in blood did not increase in 8 patients who underwent midline sternotomy for a mediastinal tumor, they increased dramatically in 3 patients who sustained a perioperative myocardial infarction. During open heart surgery the peak values of plasma Mn-SOD concentrations were correlated to that of plasma creatine kinase-MB concentrations (r = 0.5532, n = 18, p < 05) and cardiac ischemic period (r = 0.5186, n = 18, p < 05). Although the meaning of an increase in plasma Mn-SOD concentrations during open heart surgery is not clarified, it may be released from the heart and anywhere also in the body damaged during cardiopulmonary bypass.

Coronary Vessels↗
PubMed1992

Surgical treatment of ventricular tachycardia by balloon electric shock ablation. Potential effects on the mitral valve apparatus.

We have previously described a new surgical technique for control of arrhythmogenic foci in patients with recurrent ventricular tachycardia that we call balloon electric shock ablation. With this method sequential shocks are delivered to a grid of electrodes on a balloon that can be introduced across the mitral valve into the intact ventricle. A series of experiments was undertaken to investigate possible deleterious effects of balloon electric shock ablation when shocks are delivered directly to the mitral valve apparatus. In six animals shocks totaling 1200 joules were given through a closely spaced electrode grid applied to the area of the mitral valve. Nine to 12 weeks later, left ventricular and mitral valve function were assessed. Balloon electric shock ablation in the basilar portion of the ventricle was associated with decreased myocardial performance, as evidenced by ejection phase indices. In five of six animals balloon ablation led to minor thickening of the valve leaflets and chordal attachments plus necrosis of adjacent myocardium, including papillary muscles. In these animals there was no significant dysfunction of the valve observed. In the remaining animal, however, ablation was centered on the posterior papillary muscle and resulted not only in necrosis of the base of the papillary muscle but also in full-thickness scarring and thinning of the adjacent left ventricular wall. In this dog, mitral regurgitation was seen on long-term follow-up. We conclude that when balloon electric shock ablation is used to destroy a localized area of myocardium in the basilar portion of the intact ventricle, the procedure results in decreased myocardial performance. When shocks were directly applied to the mitral valve apparatus in five of six animals, ablation did not result in significant negative effects on the structure and function of the valve. In the sixth dog, however, shock delivery resulted in transmural necrosis and thinning at the site of papillary muscle insertion and was associated with severe mitral regurgitation with volume loading. Therefore caution should be used when considering clinical application of this technique if the area to be ablated is in the basal portion of the heart.

Animals↗
PubMed1992

[Surgical treatment of acquired tricuspid stenosis].

There is no definitive surgical procedure for acquired lesions of the tricuspid valve (TV). From Feb, 1978, through March, 1990, the surgical treatment for the organic lesions of TV was performed in 10 patients, repair in 6 and TV replacement in 4. TV was repaired by commissurotomy, annuloplasty or valvuloplasty, or combination of them. When residual significant tricuspid regurgitation (TR) and/or stenosis (TS) was detected by intraoperative pulsed Doppler echocardiography after reparative procedures, TV was replaced. Follow-up periods ranged from 1 to 12 years (mean, 45.3 months). There was no early death, and late death was noted in one patient 32 months after operation. Preoperatively, 7 patients were in NYHA class IV and 3 in class III. Out of survivors, 7 are in class I and 2 in class II because of progression of mitral stenosis or coronary artery disease. Following surgery, the patients exhibited significant decrease in the cardiothoracic ratio (69.3 +/- 7.2 to 56.9 +/- 6.4%; p less than 0.01) and in the mean right atrial pressure (11.4 +/- 3.6 to 8.6 +/- 3.1 mmHg; p less than 0.05). The postoperative right ventriculography showed mild to moderate TR in 3 of 6 patients who underwent TV repair. In conclusion, TV repair could be a reasonable procedure for the organic TV lesions, although careful follow-up is recommended for residual TR.

Adult↗