Impact of diabetes and glycaemic control on peripheral artery disease in Japanese patients with end-stage renal disease: long-term follow-up study from the beginning of haemodialysis.

AIMS/HYPOTHESIS: End-stage renal disease (ESRD) patients with diabetes have been regarded as being at the highest risk of cardiovascular disease. We therefore investigated the relationship between diabetes and the incidence of peripheral artery disease (PAD) in new haemodialysis patients. METHODS: We enrolled 1,513 ESRD patients who had just begun haemodialysis therapy. They were divided into two groups: those with (n = 739) and those without diabetes (n = 774). The endpoint was the development of PAD, defined as ankle brachial pressure index ≤ 0.9 or toe brachial pressure index <0.7 in patients with an ankle brachial pressure index >0.9. RESULTS: According to the Kaplan-Meier method, the 10 year event-free rate for development of PAD and lower limb amputation was significantly lower in the diabetes group than in the non-diabetes group (60.3% vs 82.8%, HR 2.99, 95% CI 2.27, 3.92, p<0.0001 and 93.9% vs 98.9%, HR 5.59, 95% CI 2.14, 14.7, p = .0005 for PAD and lower limb amputation, respectively). In patients with diabetes, quartile analysis of HbA1c levels showed that the highest quartile group (≥ 6.8% [51 mmol/mol]) had significant development of PAD and lower limb amputation compared with lower quartile groups (PAD HR 1.63, 95% CI 1.17, 2.28, p = .0038; lower limb amputation HR 2.99, 95% CI 1.17, 7.70, p = .023). CONCLUSIONS/INTERPRETATION: Diabetes was a strong predictor of PAD after initiation of haemodialysis therapy in patients with ESRD. In addition, higher HbA1c levels were associated with increased risk of developing PAD and requiring limb amputation in such diabetic populations.

Effect of artificial carbon dioxide foot bathing on critical limb ischemia (Fontaine IV) in peripheral arterial disease patients.

BACKGROUND: It has been reported that artificial carbon dioxide (CO(2)) foot bathing improves subcutaneous microcirculation in peripheral arterial disease (PAD) patients. However, the effect for critical limb ischemia (CLI) with ulceration or gangrene (Fontaine stage IV) is not identified. The physiological effects of CO(2) bathing and the outcome of limb salvage in such patients were studied. METHODS: In 18 healthy volunteers (Study I), the dorsal pedis peripheral blood flow was measured by a laser Doppler flow-meter during CO(2) foot bathing (1000 ppm, 37 degrees C) for 10 min. A Holter electrocardiogram was also recording in the same period. Blood flow and cell volume significantly increased during bathing. Eighty-three CLI limbs (Fontaine IV) in 68 PAD patients (Study II) underwent artificial CO(2) foot bathing (for 10 minutes twice daily >2 months) were followed up >6 months. RESULTS: In Study I, analysis of heart rate variability showed that high frequency amplitude (HFA) considerably increased and the ratio of low frequency amplitude to HFA (LF/HF) noticeably decreased during bathing. In Study II, 69 limbs (83.1%) could be salvaged. Twenty-seven of 28 limbs (96.4%) which have ulcer and gangrene in only one toe, 13/16 limbs (81.2%) in multiple toes and 29/39 limbs (74.4%) in all toes and/or heel respectively were saved. CONCLUSIONS: The effect of CO(2) enriched water on the subcutaneous microcirculation might be brought about by peripheral vasodilation reflected by increased parasympathetic and decreased sympathetic activity, and the artificial CO(2) foot bathing is clinically effective on salvage of CLI (Fontaine stage IV) limbs.

[An elderly case of ruptured aortic arch aneurysm with hemorrhagic cardiac tamponade].

We reported a case of successful aortic arch replacement using selective cerebral perfusion for ruptured distal aortic arch aneurysm (DAAA) with cardiac tamponade. A 80-year-old man who had preoperative episode of severe chest pain. Computed tomography showed saccular DAAA and pericardial effusion. He was diagnosed as ruptured DAAA with hemorrhagic cardiac tamponade. We performed urgent graft replacement of the aortic arch using selective cerebral perfusion. Postoperatively he had no complication. Thirty days after the operation he was discharged from the hospital and he is now leading a normal life.

Predictability of dielectric properties for ischemic injury of the skeletal muscle before reperfusion.

OBJECTIVE: The purpose of this study is to assess whether or not dielectric properties could predict the severity of ischemic injury of the skeletal muscle before reperfusion to prevent the myonephropathic metabolic syndrome (MNMS). METHODS: Japanese White rabbits were anesthetized and their hind limbs were subjected to 0, 2, 4, and 6 h of ischemia and then 10 h of reperfusion (n = 4, 5, 6, and 6). Dielectric properties of the gastrocnemius muscle were measured and tan delta(m) and D were calculated from them. To assess ischemic injury, we also measured (a) creatine phosphate kinase (CPK) and aldolase, (b) spectrophotometric assay of triphenyltetrazolium chloride assay, and (c) histological evaluation by H & E staining, 10 h after reperfusion. RESULTS: The tan delta(m) increased and D decreased significantly compared with those in preischemia (P < 0.01). The tan delta(m) value just before reperfusion significantly correlated positively with the maximum value of CPK (CPK(max)) or the maximum value of aldolase (ALD(max)) (r = 0.73, 0.69) and negatively with %TTC (r = 0.66). The D value just prior to reperfusion significantly correlated negatively with CPK(max) and ALD(max) (r = 0.81, 0.86) and positively with %TTC (r = 0.79) after reperfusion, respectively. Histologically, skeletal muscle necrosis was detected in 11 out of 12 skeletal muscles with tan delta(m) values which were 3.70 or more and 11 out of 14 muscles with D values which were 1.47 or less. CONCLUSION: The severity of skeletal muscle ischemic injury can be evaluated before reperfusion by measuring the dielectric properties during ischemia.

[Reoperation for diffuse supravalvular aortic stenosis with Williams syndrome--extended patch aortoplasty and extra-anatomic bypass from the ascending aorta to the descending aorta in a median sternotomy].

A case of diffuse supravalvular aortic stenosis (SVAS) with Williams syndrome is reported. In this case of severe diffuse SVAS, we performed the diamond-patch aortoplasty in a child. However he has been suffering from residual SVAS. At 9-years old, the myocardial injury was noted by myocardial scintigraphy. Preoperative cardiac catheterization and angiography revealed the hypoplastic ascending aorta and arch with a pressure gradient of 89 mmHg at the distal site from the left subclavian artery. Through only a median stenotomy, an extended patch aortoplasty between the valsalva sinus and distal arch was performed and an extraanatomic bypass from the ascending aorta to the descending aorta was employed using a 10 mm tube graft. We realize this technique is available because this method can relieve the left ventriculus of the pressure load and operate via only median sternotomy.

Primary cardiac leiomyosarcoma growing rapidly and causing right ventricular outflow obstruction.

Leiomyosarcomas are extremely rare primary cardiac tumors. We report a rapidly growing primary leiomyosarcoma of the right ventricle, which obstructed the right ventricular outflow tract within one month after symptom onset in a 68-year-old man. Two-dimensional echocardiography was useful in diagnosing the extent and progression of the tumor. The tumor was surgically resected on an emergency basis, and the right ventricle and pulmonary artery were successfully reconstructed. Recurrence of the tumor on the right ventricle was observed, and the patient was overcome by sudden dyspnea and died three months after surgery.

[Decreasing sarcoplasmic reticular calcium gives rise to myocardial protection--the effect of thapsigargin for myocardial protection under conditions of normothermia].

Deceasing sarcoplasmic reticular (SR) calcium may contribute to the myocardiac protection against ischemia and reperfusion-induced injury. Therefore, using the isolated working rat heart model, we investigated the effect of Thapsigargin (TH)-induced SR calcium diminution on the myocardial protection when added either before onset of ischemia or at time of reperfusion under conditions of normothermic ischemia. Hearts (n = 6/group) from male Wistar rats were aerobically (37 degrees C) perfused (20 min) with bicarbonate buffer. In the experimental protocol A, this was followed by a 3 min infusion of St. Thomas' Hospital cardioplegic solution No. 2 (STS) containing various concentrations of TH. Hearts were then subjected to 34 min of normothermic (37 degrees C) global ischemia and 35 min of reperfusion (15 min Langendorff, 20 min working). Reperfusion cardiac functions at 20 min of working perfusion was measured and compared with the preischemia values. STS added to 0.1 and 0.25 mumol/L TH improved recovery of aortic flow after 20 min reperfusion from 47 +/- 3% in the TH free controls to 62 +/- 3, 63 +/- 2% (n = 6) (p < 0.05). There was no difference in creatine kinase (CK) leakage during Langendorff reperfusion between the TH treated groups and the control group. In the experimental protocol B, 3 min of cardioplegia without TH and 34 min of ischemia (37 degrees C) were followed by a 10 min Langendorff reperfusion with various concentrations of TH, then 10 min Langendroff reperfusion for washing out, and 20 min working reperfusion. When TH was added to reperfusate the recovery of aortic flow did not change, 0.5 mumol/L TH group had the detelious effect. Thus, TH, when added to the cardioplegia, enhanced myocardial protection. We conclude that lessened uptake of Ca2+ into sarcoplasmic reticulum by inhibitors of the Ca(2+)-ATPase pump can decrease ischemia and reperfusion-induced injury.

[The temperature dependency of the protective properties of the St. Thomas' Hospital cardioplegic solution, the University of Wisconsin solution, and Bretschneider buffered solution].

We studied three preservation solutions such as St. Thomas' hospital cardioplegic solution No. 2 (ST), the University of Wisconsin solution (UW) and Bretschneider's solution (BR) for protective properties, especially in terms of temperature dependence during the preservation. Rat hearts were studied and divided into three groups; ST. UW and BR. In each group, six hearts were carried out perfusion, cardioplegic infusion, ischemia and reperfusion for four different conditions. Using an isolated working rat heart model, the hearts were subjected to 5 minutes Langendorff perfusion followed by 20 minutes working perfusion. During this working period, cardiac functions such as aortic and coronary flow, aortic pressure, and heart rates were measured every 5 minutes. After working perfusion, 3 minutes of cardioplegic infusion was carried out either with UW, ST, and BR at 37, 20, 4, 1 degree C. The hearts were subjected to either 35 min at 37 degrees C, 120 min at 20 degrees C, 300 min at 4 degrees C, or 450 min at 1 degree C. The hearts were immersed in the same solution during ischemia. The hearts were reperfused at 37 degrees C, initially in the Langendorff mode for 15 min. Coronary effluent was collected for the measurement of CK leakage during reperfusion. The heart were then converted to the working mode for 20 minutes. During working reperfusion period, the variables of cardiac function were again measured and expressed as a percentage of their individual preischemic control values. Under conditions of 37 degrees C ischemia, % recovery of cardiac output (%CO) in ST group is 62.8 +/- 2.8%, although the hearts preserved with UW and BR were not recovered. Under conditions of 20 degrees C ischemia, %CO in UW, ST and BR were 46.8 +/- 2.7, 82.0 +/- 3.1 and 41.4 +/- 2.6%, respectively. Under conditions of 4 degrees C ischemia, %CO in UW, ST and BR were 66.2 +/- 8.0, 68.6 +/- 2.3 and 47.2 +/- 2.9%, respectively. Under conditions of 1 degrees C ischemia, %CO in UW, ST and BR were 70.6 +/- 3.3, 56.5 +/- 1.6 and 43.0 +/- 2.5%, respectively. In conclusions, ST revealed the best protective properties for the heart preservation between 37 degrees C and 20 degrees C ischemia. The properties of ST was similar to that of UW under conditions of 4 degrees C, although UW showed most excellent protective properties under conditions of 1 degrees C ischemia. These results suggested that, protective ability of preservation solution might be changed by the temperature during preservation period.

[The effect of continuous perfusion with St. Thomas' Hospital cardioplegic solution containing glucose, insulin and L-aspartate on functional recovery after myocardial preservation in the rat].

UNLABELLED: The aim of this study was to determine the effect of the continuous perfusion with St. Thomas' Hospital cardioplegic solution (ST solution) containing glucose, insulin and L-aspartate upon post-preservation recovery of cardiac function in the isolated rat heart. METHODS: Hearts from Wistar male rats were perfused with Krebs-Henseleit bicarbonate buffer (KHBB) solution and cardiac function was measured using an isolated working heart preparation. Hearts were then preserved by continuous perfusion, (1) with ST solution or ST solution containing L-aspartate (20 mmol/L9 at 20 degrees C and 4 degrees C for 12 hours, (2) with ST solution containing L-aspartate at 4 degrees C for 24 hours, (3) with ST solution containing glucose (9 mmol/L) and insulin (10 U/L solution) or ST solution containing glucose, insulin and L-aspartate at 20 degrees C for 24 hours. This was followed by 15 minutes of Langendorff perfusion and 20 minutes of working perfusion with KHBB solution. During the working perfusion in the post-preservation period, cardiac function was remeasured. RESULTS: (1) At 20 degrees C, percent recovery of cardiac output (%CO) was 57.7 +/- 3.8% and 79.9 +/- 1.4*% in the L-aspartate-free group and the L-aspartate-containing group, respectively (*p < 0.05). At 4 degrees C, %CO was 74.4 +/- 2.2% and 80.5 +/- 1.7% in the L-aspartate-free group and the L-aspartate-containing group, respectively (NS). (2) %CO in L-aspartate-containing group at 4 degrees C decreased to 46.8 +/- 2.4% when preservation time was extended to 24-hours from 12 hours. (3) On the other hands, the addition of L-aspartate to the ST solution containing glucose and insulin resulted in an additive protection and %CO was 76.0 +/- 1.1% even after 24 hour preservation at 20 degrees C. CONCLUSIONS: Our results indicate that L-aspartate as an additive to perfusion medium might be beneficial for myocardial preservation, and that at 20 degrees C, the addition of L-aspartate to the ST solution containing glucose and insulin could improve the post-preservation recovery after the 24-hour preservation.

[A surgically treated case of ruptured true aortic arch aneurysm in association with Stanford type A chronic dissection].

A 72-year-old woman was admitted to our hospital because of hemosputum. Enhanced CT showed ruptured true aortic arch aneurysm. True aortic arch aneurysm ruptured at distal portion of aneurysm. The aorta was chronically dissected from an entry proximal to ruptured portion, to ascending aorta. Ascending aorta to aortic arch was replaced with 20 mm gelatin sealed graft under selective cerebral perfusion with hypothermia. Post-operatively tracheostomy was done because of respiratory failure, and there was some leak from distal anastomosis portion which was 42 mm in diameter at the operation. So replacement of descending thoracic aorta was performed using elephant trunk of the previously replaced graft. Post-reoperative course has been uneventful. She weaned from respiratory support. True aortic arch aneurysm combined with Stanford type A dissection is very rare. We presented ruptured true aortic arch aneurysm in association with Stanford type A chronic dissection which had an entry in true aneurysm.

[Coronary artery bypass grafting in cases with the atherosclerotic ascending aorta].

Among 172 cases of coronary artery bypass grafting, 9 cases (5%) revealed severely atherosclerotic ascending aorta. In 3 of the 9 cases, total aortic cross-clamping in the distal anastomoses of saphenous vein graft (SVG) and partial aortic clamp in the proximal anastomoses of SVG were performed. In 1 case with this technique, cerebral infarction was occurred. In 4 cases, total aortic cross-clamping in the distal and proximal anastomoses of SVG was performed. In 2 of these cases with this technique, cerebral infarctions were occurred. Hypothermic circulatory arrest was performed in 2 of the rest. In one case that was predicted to have atherosclerosis of ascending aorta prior to operation, the left internal thoracic artery was anastomosed to the left anterior descending, and SVG to the right coronary artery with hypothermia and ventricular fibrillation. And during the proximal anastomoses of SVG, hypothermic circulatory arrest without aortic clamping was initiated. In another case, atherosclerosis of ascending aorta was noted after aortic cross-clamping. Then the aorta was declamped, hypothermic circulatory arrest was established, the aorta was opened, the diseased segment was resected, and proximal anastomoses of SVG was performed to Dacron patch which was implanted for aortic wall. There were no cerebral infarction in last two patients.

[Treatment of patients with chronic dissecting aortic aneurysm (DeBakey type IIIb) presenting with compromised renal perfusion].

We reviewed our experience for 6 patients of chronic dissecting aortic aneurysm (DeBakey type IIIb) with the false lumen extending into the abdominal aorta and the renal arteries being perfused from the false lumen. In three cases, whose abdominal aorta presenting with large aneurysmal lesions, we performed graft replacement of the thoracic descending aorta and abdominal aorta simultaneously. In other three cases, whose abdominal aorta presenting without aneurysmal lesions, and moreover age advanced or perioperative conditions poor, we performed graft replacement of thoracic descending aorta, using double barreled distal anastomosis technique to ensure of enough blood flow into both true and false lumens. All patients survived and there were no early postoperative complications. In 3 cases of thoracic aortic replacement alone, the mean follow-up term was 38 months, postoperative computed tomography showed neither apparent expansion of the false lumen nor compression of the true lumen of the abdominal aorta, and postoperative renal function were maintained. In conclusion, in treatment of chronic dissecting aortic aneurysm (DeBakey type IIIb) presenting with compromised renal perfusion, we considered that replacement of the thoracic descending aorta and abdominal aorta brings patient the most radical improvements. But in the patients, who are elder or in poor perioperative conditions, the replacement of thoracic descending aorta using double barreled distal anastomosis technique is one easier applicable and safer procedure to preserve the renal perfusion.

[A trial of antegrade perfusion to the lower half of the body with selective cerebral perfusion for repair of aortic arch aneurysm combined with atherosclerosis obliterance].

A 73-year-old man with aortic arch aneurysm combined with atherosclerosis obliterance underwent aortic arch replacement. As he had bilateral femoral artery obstruction, we instituted ECC with arterial perfusion through the ascending aorta. Then, the left ventricle started dilating due to mild degree of aortic regurgitation. So with selective cerebral perfusion, we perfused the lower half of the body through a Foley balloon catheter which was inserted from the aortic arch antegradely. We could perfuse with the catheter for 20 minutes for core cooling and then during repair until the catheter disturbed the operation. The Foley catheter had given us some difficulties for handling during the procedure. Based on this experience, we have made a catheter which had both a balloon for aortic occlusion and a tube for perfusion and which we could keep away from operative fields, similar to the way we used antegradely insertable aortic occlusion balloon catheter.

[The effects of glucose and insulin upon functional recovery in the rat heart preserved by continuous perfusion with St. Thomas' Hospital cardioplegic solution].

UNLABELLED: The aim of this study was to determine the effect of the continuous perfusion with Krebs-Henseleit bicarbonate buffer (KHBB) solution or St. Thomas' Hospital cardioplegic solution (ST solution) containing glucose and insulin upon the post-preservation recovery in the isolated rat heart. METHODS: Hearts from male Wistar rats (n = 6/group) were subjected to working perfusion with KHBB solution for measurement of cardiac function. They were continuously perfused (1) with KHBB solution or ST solution for 12 hours at 20 degrees C, (2) with ST solution for 12 hours at 37 degrees C, 20 degrees C or 4 degrees C, (3) with ST solution or ST solution containing glucose (9 mmol/L) for 12 hours at 20 degrees C or 4 degrees C, and (4) with ST solution containing glucose (9 mmol/L) or ST solution containing glucose (9 mmol/L) and insulin (10 U/L solution) for 20 hours at 20 degrees C. This was followed by 15 min of Langendorff perfusion and 20 min of working perfusion with KHBB solution. During the second working perfusion after preservation, cardiac function was measured again. RESULTS: (1) Percent recoveries of cardiac output (%CO) preserved with KHBB and ST solution were 44.9 +/- 4.0 and 57.7 +/- 3.8%, respectively (p < 0.05). (2) %CO after preservation with ST solution at 37, 20, 4 degrees C were 0*, 57.7 +/- 3.8 and 74.4 +/- 2.2*%, respectively (*p < 0.05 vs the 20 degrees C group). (3) At 20 degrees C, glucose addition to ST solution increased %CO to 76.5 +/- 2.4% from 57.7 +/- 3.8% in glucose-free ST solution group (p < 0.05). However, at 4 degrees C, glucose addition to ST solution was rather harmful and decreased %CO to 61.4 +/- 2.8% from 74.4 +/- 2.2 in glucose-free ST solution group (p < 0.05). (4) The addition of insulin to the glucose-containing ST solution resulted in a significant increase in %CO from 24.6 +/- 4.0% in the insulin-free solution to 69.2 +/- 2.0%. CONCLUSIONS: Our results indicate that 1) ST solution might be better than KHBB solution for a continuous perfusion medium of myocardial preservation, and 2) at 20 degrees C, the addition of glucose and insulin to the ST solution could be beneficial for the continuous infusion as a method of preservation, however, at 4 degrees C, these addition might be harmful, suggesting the temperature dependence in the utility of energy substrate.

[Changes in analgesic levels, plasma concentrations and epidurogram during long-term continuous epidural block].

The change of analgesic levels, plasma concentrations and the radiographical changes of epidural space due to continuous epidural block were studied in 54 patients receiving pain relief. All the patients received 2 ml per hour of 2% lidocaine or 0.5% bupivacaine via the catheter over two weeks. The effect of epidural block was determined on 1, 2, 4, 7, 10 and 14 days, the epidurogram was performed on 1, 7, 14 days, and plasma concentration of lidocaine or bupivacaine was measured on 1, 3, 7, 14 days. We removed catheters in 8 patients because of infection around the catheter, pain in the back during injection, the leakage of anesthetics, and spontaneous removal. The effects and plasma concentrations of epidural block decreased significantly after a week, and the mean segmental number of radiographic spread decreased significantly after two weeks. The decreasing effect or duration of epidural block was due to decrease in spread of anesthetics because of adhesion around the catheter in the epidural space. We conclude that the safety period of continuous epidural block is within 2 weeks.

[Use of ketamine combined with local anesthetics in epidural anesthesia].

Postoperative pain relief and sedation with epidural ketamine were studied. Twenty-four patients for elective upper abdominal surgery were divided into 4 groups. Epidural catheter was inserted into thoracic epidural space before induction of general anesthesia. In each group, either 0.25% bupivacaine 5 ml only, ketamine 0.1 mg.kg-1 + bupivacaine 5 ml, or ketamine 0.3 mg.kg-1 + bupivacaine 5 ml, or ketamine 0.5 mg.kg-1 + bupivacaine 5 ml was injected into epidural catheter for complaint of pain in recovery room. In ketamine injected groups, blood pressure and heart were unchanged, but respiration rate increased significantly. Patients in ketamine 0.3 or 0.5 mg.kg-1 injected groups, pain relief and sedation score were significantly intensified, but patients in ketamine 0.5 mg.kg-1 injected group, incidence of pain in the back during injection and headache was high. We conclude that epidural ketamine is useful for postoperative pain relief, and the superior dose of epidural ketamine is 0.3 mg.kg-1.

[The effects of Ebselen upon post-ischemic functional recovery in rat heart].

The effects of Ebselen (DR-3305) upon cardiac function and CK leakage with or without ischemia reperfusion insults were investigated in this isolated working rat heart study. In order to evaluate the effects of Ebselen upon cardiac function, it was administrated to the isolated rat heart with Langendorff perfusion for 15 min at 100 cmH2O. Cardiac functions such as aortic and coronary flow, heart rate and aortic pressure, before and after Ebselen treatment, were measured and expressed as percent of the control value. The coronary resistance was significantly reduced in 100 nM, 500 nM and 1000 nM of Ebselen pretreatment with dose dependent manner. However pretreatment with 1000 nM of Ebselen significantly decreased cardiac output with significant increase of CK leakage. The myocardial protective effects of Ebselen in the cardioplegia or reperfusate were investigated under conditions of normothermic ischemia. After measuring preischemic cardiac functions, the St. Thomas' Hospital cardioplegic solution was infused for 3 min followed by 35 min of global ischemia at 37 degrees C. Hearts were then aerobically reperfused for 15 min in the Langendorff mode. Subsequently, cardiac function was measured and expressed as percent of the preischemic control value. Ebselen addition to the St. Thomas' cardioplegic solution did not possess any myocardial protective effects, although addition to reperfusate possess the protective abilities at a concentration of 10 nM. From these data, Ebselen, which was one of the free radical scavenger, had the myocardial protective effects if it was added to reperfusate at a concentration of 10 nM.

[Myocardial preservation by continuous perfusion of Krebs-Henseleit solution--the temperature dependency of the optimal perfusion pressure].

The aim of this study was to determine the temperature dependency of the optimal pressure in myocardial preservation by continuous perfusion with Krebs-Henseleit bicarbonate buffer (KHBB) solution. Hearts from Wistar male rats were perfused with KHBB solution and cardiac function (aortic flow) was measured using an isolated working rat heart preparation. In the preliminary experiment, hearts were then preserved using Langendorff perfusion with KHBB solution of 37, 20 or 4 degrees C for 2 hours at a perfusion pressure of 100 cmH2O. This was followed by 15 min of Langendorff perfusion (37 degrees C, 100 cmH2O) and 20 min working perfusion. The 37 degrees C group and 20 degrees C group exhibited better functional recoveries of aortic flow (%AF) in the post-preservation period compared to the 4 degrees C group. In the test experiment, hearts were preserved using Langendorff perfusion for 4 hours at 37 degrees C or for 8 hours at 20 degrees C at various perfusion pressures. At 37 degrees C, %AF after 4 hours of the preservation were 64.7 +/- 2.6, 69.0 +/- 3.2, 81.9 +/- 3.1, 94.7 +/- 3.3 and 63.5 +/- 4.0% (p < 0.05 vs the 100 cmH2O group) at the perfusion pressure of 100, 60, 20, 15 and 10 cmH2O, respectively. %AF after 8 hours of the preservation at 15 cmH2O was 56.3 +/- 2.5%. At 20 degrees C, %AF after 8 hours of the preservatin was 78.9 +/- 3.3, 81.9 +/- 2.3, 67.4 +/- 1.9 and 65.9 +/- 2.2% (p < 0.05 vs the 60 cmH2O group) at the perfusion pressure of 60, 30, 10 and 15 cmH2O, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen radical-induced inhibition of alkaline phosphatase activity in reconstituted membranes.

The effects of lipid peroxidation on membrane-bound enzyme activity were examined using reconstituted membranes consisting of intestinal alkaline phosphatase (ALP) and phosphatidylcholine (PC) or dipalmitoylphosphatidylcholine (DPPC). When the PC-reconstituted membranes were incubated with ascorbic acid/Fe2+, the ALP activity decreased with increases in the thiobarbituric acid-reactive substances and conjugated diene values in a time-dependent manner. The kinetic studies on the ALP activity with varying the p-nitrophenyl phosphate or beta-glycerophosphate concentrations showed that the inhibition of the enzyme activity by treatment with these oxidizing agents is mainly due to a decrease in the Vmax value rather than a change in the Km value. The results with several antioxidants suggested that ascorbic acid/Fe(2+)-induced inhibition of the ALP activity is related to generation of .OH radicals. Modification of the reconstituted membranes with malondialdehyde, trans-2-nonenal, or n-heptaldehyde did not affect the ALP activity, suggesting that the secondary degraded products of lipid hydroperoxides had no influence on the enzyme activity. Increasing bityrosine production in the membrane constituents was observed by ascorbic acid/Fe2+ treatment, depending on the incubation time. This finding suggests the possibility that amino acid modifications in the protein molecule are induced by the treatment. Furthermore, the contribution of the lipid organization in ascorbic acid/Fe(2+)-induced inhibition of the ALP activity in the reconstituted membranes was examined by measurements of the fluorescence anisotropy of diphenylhexatriene-labeled membranes. In addition, it was found that the ALP activity in DPPC-reconstituted membranes was also inhibited by treatment with ascorbic acid/Fe2+, similar to the case in PC-reconstituted ones. On the basis of these results, a possible mechanism of ascorbic acid/Fe(2+)-induced inhibition of membrane-bound ALP activity is discussed.