Pretreatment with a single bolus injection of polyoxyethylene-modified superoxide dismutase prevents reperfusion induced arrhythmias in the anesthetized rat

Effects of a newly introduced polyoxyethylene-modified superoxide dismutase (SOD-POE) on reperfusion induced arrhythmias were examined in the pentobarbital anesthetized rat. Reperfusion induced arrhythmias were elicited by occlusion of the left anterior descending coronary artery (LAD) for 15 min and subsequent release. The LAD occlusion was performed by compressing the artery using a suction cup of 2 mm in diameter placed on the LAD to which negative pressure was applied. The LAD occlusion and release was repeated at an interval of 30 min. SOD-POE or human SOD (h-SOD) (1000 U/kg) was injected intravenously 15 min prior to the occlusion at the second trial of the occlusion. In the control group, various types of arrhythmias including ventricular fibrillation (Vf), ventricular tachycardia (VT), premature ventricular contraction (PVC) and premature atrial contraction (PAC) were elicited immediately after release of the occlusion. In the SOD-POE-treated group, Vf and VT were completely prevented and the numbers of PVC and PAC significantly decreased, while pretreatment with h-SOD did not prevent the occurrence of reperfusion induced arrhythmias. The protective effects of SOD-POE lasted for more than 90-120 min. The plasma half life for SOD-POE was 10.8 hr, while that for h-SOD was 8.6 min. Results indicate that intravenous administration of SOD-POE would provide a new means of preventing reperfusion induced arrhythmias occurring in clinical situations.

Effects of polyoxyethylene-modified superoxide dismutase on reperfusion induced arrhythmias in isolated rat and guinea-pig hearts

Effects of a newly introduced polyoxyethylene-modified superoxide dismutase (SOD-POE) with prolonged plasma half life (10 h) on reperfusion induced arrhythmias were examined using a 15 min left anterior descending coronary artery (LAD) occlusion followed by reperfusion in the isolated perfused rat and guinea-pig hearts. LAD occlusion was performed by compressing the artery using a suction cup placed on the LAD to which negative pressure was applied. The LAD occlusion was repeated twice at an interval of 20 min. Drugs were infused from 10 min prior to the occlusion to 3 min after reperfusion at either first or second trial of the occlusion and release. ECG was monitored throughout the experiments. In the control group (rat hearts), arrhythmias including ventricular fibrillation (Vf) (incidence, 64.3 to 83.3%), ventricular tachycardia (VT) (66.7 to 84.6%), premature ventricular contraction (PVC) and premature atrial contraction (PAC) occurred immediately after reperfusion and lasted for 1 to 3 min. In both groups treated with SOD-POE (10 U/ml) or native human SOD (10 U/ml), the incidence of Vf and VT was 0% and the number of PVCs significantly decreased. Lidocaine (5 x 10(-7) M, 10(-6) M) also reduced the incidence of VT and the number of PVCs. In guinea-pig hearts, the occlusion and release induced Vf (50%), VT (80%), PVCs and PACs. Both SOD-POE and SOD markedly depressed the incidence of Vf (0%) and VT (14.3% in both groups) and decreased the number of PVCs and PACs. Results demonstrate that SOD-POE has the same pharmacological activity as SOD does in preventing reperfusion induced arrhythmias in isolated rat and guinea-pig hearts, suggesting that it will provide a novel therapeutic approach for preventing oxygen radical-related injury in myocardium and other tissues.

In vitro evaluation of a pyridoxalated hemoglobin polyoxyethylene conjugate in reversing cell sickling

In sickle cell disease (SCD) microcirculatory blockage by red blood cells (RBC) occurs because of their low oxygen concentration, which results in both sickling and painful crises. Pyridoxalated hemoglobin polyoxyethylene (PHP), developed from human RBC hemoglobin (Hb) by chemical modification as an oxygen carrier, was evaluated in vitro for its ability to reverse cell sickling. PHP solutions of 6 or 8 g % Hb and a P50 of 20 mmHg were evaluated. RBC were obtained from SCD patients treated by exchange transfusion. The in vitro positive pressure filtration method (47 mm 5 microns Nuclepore membrane) was used. Comparisons of PHP with low oxygen carrier solutions (Hespan, saline) were made at flows of 0.43 to 6.0 ml/min. PO2 increases in a 20% mixture of air saturated solutions with deoxygenated sickle cell suspensions (SCS), at a hematocrit of 1%, were significantly higher in PHP as compared with saline and Hespan. The filtration resistance of deoxygenated SCS mixed with PHP was significantly lower than that of deoxygenated SCS mixed with saline and Hespan, and was comparable to that of air oxygenated SCS. By the 20% (v/v) addition of air saturated PHP to deoxygenated SCS, 89 +/- 2% of the sickled cells were unsickled. A novel artificial capillary system (ACS) modeling the dynamics of the microcirculation of the body was used. With the ACS plugged with deoxygenated cells, perfusion with oxygenated cell-PHP solutions was significantly more efficient in reversing the blockage than oxygenated saline and Hespan solutions. PHP reverses cell sickling by its effective delivery of oxygen.

Renal effects of a pyridoxalated-hemoglobin-polyoxyethylene conjugate solution as a blood substitute in exchange transfusions

With PHP as an oxygen carrier, histologic studies in ET showed changes of renal tubular epithelial cells at 2 weeks post ET, with normal structure by 3-12 months post ET. The renal functional effects of PHP were evaluated by ET (30%, N = 3; 50%, N = 1; 80%, N = 3) in seven healthy mongrel dogs. Blood, urine, and renal biopsy specimens were taken pre ET and at 0, 1, and 2 days, 2, 4, and 6 weeks, and 3, and 6 months post ET. Data were compared to modified criteria of acute tubular necrosis. All dogs tolerated the procedure well and survived for 1 year. Urine output was normal with elevation during the first 2 days in the 50 and 80% ET, followed by stable output by 2 weeks, ranging from 12 to 60 ml/kg/day. Blood urea nitrogen (BUN) and serum creatinine (SCr) were normal. BUN/SCr was normal. The urine to plasma osmolality ratios were 2.6 to 8.3 (normal greater than 1), and fractional percent excretions of sodium (FES) were stable throughout. No existence of broad granular pigmented casts (BGPC) in urine sediment were noted. Renal histologic evaluation of vacuolization in the renal tubules were seen to be dose-dependent and transient, with normal histology by 3-6 months post ET. Dose-dependent vacuole formation observed in the early weeks post ET with PHP showed no renal functional changes. Based upon the modified criteria for acute tubular necrosis, no histologic abnormalities were noted.

A new resuscitation fluid "stabilized hemoglobin" preparation and characteristics

A new oxygen carrier for use as a blood substitute was prepared and characterized in vitro. Pyridoxylated hemoglobin, which was obtained by the reaction of human hemoglobin with pyridoxal-5-phosphate, was modified by alpha-carboxymethyl, omega-carboxymethoxyl polyoxyethylene (POE) of the molecular weight 3600 daltons. In order to eliminate viruses and nucleic acids possibly contaminated, the hemoglobin solution was purified by ultrafiltration with a membrane of the nominal molecular weight limit 300 Kdaltons. Furthermore POE conjugated pyridoxylated hemoglobin was treated with 20% ethanol to inactivate viruses. A concentration of hemoglobin, which is incorporated in the conjugate, of the final product was fixed at 6% to make normovolemic exchange transfusion possible. In consideration of the stability during transporting and storage, lyophilized product was selected as a final form ("Stabilized Hemoglobin"). "Stabilized hemoglobin" could be stored in a refrigerator over one year within the acceptable methemoglobin increase. (15%) Viscosity of Stabilized Hemoglobin solution was determined at 2.4 centipoise and is almost half of whole blood and therefore this will be useful not only in resuscitation but also in improvement of microcirculation.

Efficacy and safety of hemoglobin-polyethylene glycol conjugate (pyridoxalated polyethylene glycol hemoglobin) as an oxygen-carrying resuscitation fluid

The safety and efficacy of a conjugate of pyridoxalated hemoglobin and polyethylene glycol (pyridoxalated PEG hemoglobin) were evaluated after administration to rats. The LD50 (lethal dose for 50% survival of group) of pyridoxalated polyethylene glycol (PEG) hemoglobin was greater than 200 ml/kg. Any pro- or anticoagulation activity was not demonstrated in in vitro coagulation tests. One day after 70% exchange-transfusion with pyridoxalated PEG hemoglobin, slight elevations of the serum glutamic-oxaloacetic transaminase, serum glutamic-pyruvic transaminase, and blood urea nitrogen values, which were 101.7 +/- 22.6 IU/L, 33.3 +/- 7.2 IU/L, and 23.1 +/- 1.4 mg/dl, respectively, were observed. However, these values were in the normal range after 3 days. With greater than 90% exchange-transfusion, all rats exchange-transfused with pyridoxalated PEG hemoglobin survived for greater than 2 weeks in contrast to the death of all the rats exchange-transfused with stroma-free hemoglobin or albumin.

Preparation and evaluation of hemoglobin-polyethylene glycol conjugate (pyridoxalated polyethylene glycol hemoglobin) as an oxygen-carrying resuscitation fluid

Human hemoglobin was pyridoxalated and subsequently coupled with the activated ester of polyethylene glycol (PEG) to provide an oxygen-carrying resuscitation fluid. The PEG conjugate of pyridoxalated hemoglobin (pyridoxalated PEG hemoglobin) has a longer half-life in the circulation (12.8 h) than does hemoglobin (2.2 h) when the solutions are exchange-transfused by approximately 60%. The P50 of pyridoxalated PEG hemoglobin, which is the partial pressure of oxygen at which one-half of the absorbed oxygen is released, was 21.3 +/- 1.4 mm Hg (mean +/- SD, n = 5) (37 degrees C, pH = 7.4), which is close to that of human whole blood (25.9 +/- 0.6 mm Hg). The colloidal osmotic pressure and the viscosity were 36.5 +/- 2.4 mm Hg (n = 5) and 2.6 +/- 0.4 cp (n = 5), respectively. The results indicate that the pyridoxalated PEG hemoglobin solution has favorable properties for use as an oxygen-carrying resuscitation fluid.

Diplopodia with reversed foot. Normal gait after operation at 8 years of age

Diplopodia with the duplicated foot tucked up posteriorly, was reconstructed successfully in an 8-year-old boy. The knee joint, fibula and tibia were uninvolved; he had been walking on the dorsum of the foot wearing an ordinary shoe with the heel forward. The foot had ten toes, nine metatarsals and nine tarsal bones including one talus and one large calcaneus on which two Achilles tendons were inserted into two tuberosities. The lateral supernumerary foot was excised and the medial foot was dorsiflexed by almost 180 degrees by massive release and elongation of tendons. He could walk on his bare reconstructed foot without a brace 10 months after the operation.

Hemoglobin-inulin conjugate as an oxygen carrying blood substitute

Pyridoxylated hemoglobin was modified with the activated ester of inulin. From the oxygen equilibrium curve, this conjugate was estimated to have about fivefold oxygen carrying capacity compared with a free hemoglobin. The half disappearance time of this conjugate in the circulation of a rat was 21 hours in contrast to 3 hours of a free hemoglobin. The oncotic pressure and the viscosity can be adjusted nearly equal to those of whole blood. This conjugate can be concluded to have sufficient properties for use as a blood substitute.