Therapeutic time window for the 21-aminosteroid, U-74389G, in global cerebral ischemia

A novel 21-aminosteroid (U-74389G), a new potent antioxidant, was evaluated for its protective effect on transient global cerebral ischemia. Ischemia was induced by 20 minutes of four-vessel occlusion in adult male Wistar rats. Injection of 21-aminosteroid (U-74389G, 5 mg/kg intraperitoneally injected) was repeated three times. The second injection was performed 30 minutes after the first injection, and the third injection was performed 210 minutes after that. Experimental animals were divided into five groups according to the time drug administration was initiated. Group I (n = 8) began vehicle administration 30 minutes before occlusion. Group II (n = 9) started 21-aminosteroid administration 30 minutes before occlusion. Drug administration in Group III (n = 9) began at the time of reperfusion, in Group IV (n = 8), 30 minutes after reperfusion, and in Group V (n = 6), 60 minutes after reperfusion. Animals in the control group (n = 5) underwent sham operations. One week after ischemia, the number of viable pyramidal neurons was counted in the hippocampal CA1 subfield. The results were as follows: the number of living neurons in Group I was 18.8 +/- 8.7; in Group II, was 44.7 +/- 9.5; in Group III, was 46.4 +/- 9.4; in Group IV, was 40.3 +/- 6.6; in Group V, was 10.2 +/- 2.5; and in the control group was 131 +/- 3.3. Groups II, III, and IV demonstrated significantly higher numbers of living neurons compared with Group I (P < 0.05). The present study revealed that U-74389G attenuated delayed neuronal death in global cerebral ischemia when it was administered before or soon after the ischemic episode.     

Postischemic application of lipid peroxidation inhibitor U-101033E reduces neuronal damage after global cerebral ischemia in rats

BACKGROUND AND PURPOSE: The lipid peroxidation inhibitor U-101033E was examined for effects on cerebral blood flow (CBF), cortical tissue hemoglobin oxygen saturation (HbSo2), and neuronal damage. METHODS: Fifteen minutes of global cerebral ischemia was induced by two-vessel occlusion and hypobaric hypotension. Wistar rats (n = 25) were randomized to receive vehicle (n = 9) or 40 mg/kg U-101033E (n = 9) intraperitoneally during 2 hours of reperfusion. A sham group (n = 7) had neither ischemia nor therapy. Histology was evaluated 7 days after ischemia. RESULTS: During late hyperperfusion (at 17 minutes), vehicle-treated animals had a higher (P = 0.044) cortical tissue HbSo2 (72.0 +/- 1.4%) than did U-101033E-treated animals (65.8 +/- 2.5%). Neuronal counts in the superficial cortex layer found after 7 days correlated negatively with rCBF (r = -0.76; P < 0.001) or cortical tissue HbSo2 (r = -0.56; P = 0.028) assessed during the late hyperperfusion phase. U-101033E reduced neuronal damage in hippocampal CA1 from 64.3 +/- 9.2% to 31.2 +/- 8.4% (P = 0.020), as well as in the superficial cortical layer from 53.5 +/- 14.6% to 12.8 +/- 11.7% (P = 0.046). While animals in the vehicle group had reduced counts in all four examined cortex layers (P < 0.05 versus sham group), there was significant cortical neuron loss in the U-101033E group in only one of four areas. U-101033E had no effect on resting CBF or CO2 reactivity. CONCLUSIONS: Postischemic application of U-101033E protects hippocampal CA1 and cortical neurons after 15 minutes of global cerebral ischemia. The results indicate that free radical-induced lipid peroxidation contributes to reperfusion injury, a process that can be inhibited by antioxidants such as U-101033E.     

Comparison of metoprolol and carvedilol pharmacology and cardioprotection in rabbit ischemia and reperfusion model

Carvedilol, a selective alpha1 and non-selective beta-adrenoceptor antagonist and antioxidant, has been shown to provide significant cardiac protection in animal models of myocardial ischemia. To further explore the mechanisms contributing to carvedilol cardioprotection efficacy, the effects of carvedilol on hemodynamic variables, infarct size and myeloperoxidase activity (an index of neutrophil accumulation) were compared with a beta1-selective adrenoceptor antagonist, metoprolol. Carvedilol (1 mg/kg) or metoprolol (1 mg/kg or 1 mg/kg + 0.5 mg/kg 90 min later) was given intravenously 5 min before reperfusion. In vehicle-treated rabbits, ischemia (60 min) and reperfusion (180 min) resulted in significant increments in left ventricular end diastolic pressure, large infarcts (59+/-2.6% of area-at-risk) and marked increase in myeloperoxidase activity (0.59+/-0.09 U/100 mg tissue). Carvedilol treatment resulted in sustained reduction of pressure-rate-index and significantly smaller infarcts (22.0+/-2.5%, P < 0.01 vs. vehicle) as well as decreased myeloperoxidase activity (0.186+/-0.056 U/100 mg tissue, P < 0.01 vs. vehicle). The highest dose of metoprolol, 1 mg/kg + 0.5 mg/kg, that resulted in pressure-rate-index comparable to that of 1.0 mg/kg carvedilol, failed to reduce myeloperoxidase activity in the ischemic myocardial tissue, and the infarct size (35+/-3.1%) was significantly larger than in carvedilol-treated animals. Taken together, this study suggests that the superior cardioprotection of carvedilol over metoprolol is not a consequence of hemodynamic variances but possibly the result of the additional pharmacological properties of carvedilol such as the antioxidant and anti-neutrophil effects.     

Treatment of embolic cerebral infarct via thrombolysis and cytoprotection with U-74389-G in rats

INTRODUCTION: The best treatment for cerebral ischemic will probably comprise the association of inhibition of ischemia-reperfusion injury mediators and early reperfusion. OBJECTIVE: We tried to demonstrate if reperfusion by thrombolysis (rt-PA) and free radical scavenging (U-74389-G) reduces ischemic-reperfusion cerebral injury in a rat model of embolic brain infarction. MATERIAL AND METHODS: 39 female Long Evans rats were embolized in right hemisphere with an autologous clot. Three groups are considered; A: control (n = 15), B: rt-PA i.v., 20 mg/kg starting 90-120 minutes after embolization (n = 15), C: rt-PA, same dose, and U-74389-G i.v., 3 mg/kg before and after embolization (n = 9). Arterial blood pressure, gasometry, glycemia and temperature were controlled. Volume of cerebral lesion in surviving animals 24 hours was measured. Autopsy was performed to verify the cause of death in rats which died. RESULTS: Mortality: group A: 8/15; group B: 9/15; group C: 8/9. Early death was related to cerebral injury except for five rats which developed peritoneal bleeding. We found severe acidosis in rats from group C. Differences in mean volume of ischemic lesion in group A and B are nosignificant despite a tendency to a reduction after thrombolysis. CONCLUSIONS: In this model thrombolysis alone and in association with U-74389-G failed to reduce cerebral lesion and mortality.     

Therapeutic implications of thymic uptake of radioiodine in thyroid carcinoma

BACKGROUND: NPC18915, a member of new antiinflammatory agent called nactins (neutrophil activation inhibitors), has been shown to reduce reperfusion injury in rat lung transplantation at high dosage. In vitro studies have demonstrated effectiveness of this compound even at low dosage. We hypothesized that this compound ameliorates lung ischemia reperfusion injury even at low dosage levels if administration is optimally timed. The aim of this study was to determine the efficacy and the best timing for administration of low-dose NPC18915. METHODS: Forty syngeneic rat left lung transplantations were performed. All isografts were flushed with low-potassium dextran-1% glucose solution 20 ml and preserved for 18 hours at 4 degrees C. Animals were divided into four groups. Group I animals (n = 10) served as control subjects. In groups II (n = 10), III (n = 10), and IV (n = 10), NPC18915 (0.04 mg) was added to the flush solution and was administered intravenously (0.4 mg/kg) immediately before reperfusion (group II) and 60 minutes (group III) and 120 minutes (group IV) after reperfusion. Pulmonary function was assessed 24 hours after reperfusion. RESULTS: In group III, oxygenation improved in comparison to group I (247.2 +/- 59.8 versus 76.6 +/- 16.0 mm Hg, p < 0.002). Wet-to-dry weight ratio and graft myeloperoxidase activity were significantly improved (group III versus group I, 6.02 +/- 0.21 versus 7.19 +/- 0.41, p = 0.013) (group III versus group I, 0.093 +/- 0.019 versus 0.207 +/- 0.023 delta optical density/min/mg, p < 0.002). There were no significant differences in CD11b expression. CONCLUSION: These data suggest that delayed administration of NPC18915, 60 minutes after reperfusion, dramatically improves pulmonary graft function.     

The relation between induced abortion and ectopic pregnancy

The present study was conducted to elucidate the effects of tirilazad mesylate (U-74006F), a potent inhibitor of lipid peroxidation, on vessel diameter, capillary perfusion, and contractile function of rat cremaster muscle during a 90-minute reperfusion period that followed 4 hours of warm ischemia. Two groups of 32 animals were treated with either 3 mg/kg U-74006F or the vehicle (citrate buffer) alone 30 minutes before ischemia, 90 minutes after ischemia, and immediately before reperfusion. With use of intravital videomicroscopy, the internal luminal diameters of preselected vessels were measured prior to ischemia and during reperfusion. The area that filled with fluorescein was determined at 15-minute intervals for as long as 90 minutes of reperfusion, and contractile function was examined in vitro in an organ bath at that point. In the U-74006F group, after 90 minutes of reperfusion the vessel diameters returned completely to baseline and the diameters of all three categories of vessels at every time point from 10 to 90 minutes of reperfusion had significantly more rapid recovery than the controls. Although some evidence of more rapid fluorescence was noted in the U-74006F group, the two groups did not differ significantly at any time period of reperfusion. In response to tetanic stimulation, the muscles treated with U-74006F had a significantly greater contractile force at all stimulation frequencies than the control muscles. Our findings indicate that pretreatment with U-74006F can effectively decrease the rise of vascular resistance and preserve the contractile function of skeletal muscle during early reperfusion, thereby attenuating ischemia-reperfusion injury.     

Attenuation of myocardial stunning in isolated rat hearts by a 21-aminosteroid lazaroid (U74389G)

The purpose of this study was to evaluate the effects of reperfusion or in vivo pretreatment with a lipid peroxidation inhibitor, lazaroid (U74389G), on attenuating systolic and diastolic alterations occurring during myocardial stunning in isolated rat hearts. Male Sprague-Dawley rats (350-400 g) were randomized into three groups: control animals (n = 13) received no drugs; hearts from reperfused animals (n = 11) received 5 microM U74389G in the reperfusion solution; pretreated animals (n = 11) received 6 mg/kg U74389G by i.v. infusion 30 min before killing. Isolated, isovolumic rat hearts were subjected to 20 min of ischemia at 37 degrees C and subsequent reperfusion for 30 min. Left ventricular isovolumic developed pressure (LVDP), its first derivative (LVDPdP/dt), end-diastolic pressure (LVEDP), and the time constant of diastolic relaxation (tau) were measured. At baseline, no statistically significant differences were detected in systolic or diastolic function in hearts of rats with or without U74389G treatment. After reperfusion, LVDP stabilized at 87 and 92% in both drug-treated groups compared with 52% in the control group (p < 0.01) and dP/dtmax recovered to 101 and 110% of baseline compared with 58% in the control group (p < 0.01). Diastolic dysfunction showed significant improvement in both U74389G pretreatment groups. The increases in LVEDP and tau were 2.0- and 1.2-fold in pretreated hearts and 2,8-fold and 1.5-fold in drug-reperfused hearts, respectively (compared with 6-fold increases in LVEDP and a 2.5-fold increase in tau in controls; p < 0.05). In conclusion, whether administered before ischemia or during reperfusion, U74389G effectively attenuated the systolic and diastolic dysfunction in this model of myocardial stunning, probably protecting cell membranes from peroxidation by oxygen-derived metabolites.     

Protective efficacy of a hypothermic pharmacological agent in gerbil forebrain ischemia

BACKGROUND AND PURPOSE: The novel muscarinic cholinergic partial agonist U-80816E was tested in the gerbil brief bilateral carotid occlusion ischemia model based on the rationale that the compound's hypothermic properties might afford effective protection of the selectively vulnerable hippocampal CA1 region. METHODS: Male gerbils were subjected to either 10 or 15 minutes of bilateral carotid occlusion, followed by histopathological assessment of the CA1 neuronal survival 7 days later. RESULTS: In saline-treated animals, 10 minutes of bilateral carotid occlusion resulted in a 30.5% loss of CA1 neurons, whereas a 15-minute insult resulted in a 49.6% loss. Administration of U-80816E (6 mg/kg i.p. 30 minutes before bilateral carotid occlusion and again 2 hours after reperfusion) resulted in a significant protective effect of the CA1 neuronal population with either duration of ischemia; neuronal loss was reduced to 12.6% in the milder model (p < 0.05 versus saline-treated) and 24.9% in the more severe model (p < 0.04 versus saline). However, the 6 mg/kg i.p. dose of U-80816E was found to produce a 1.0 degree C decrease in brain temperature (measured with a tympanic temperature probe) at 10 minutes of ischemia compared with that of saline-treated gerbils. At 10 minutes of reperfusion, after the 10-minute episode of ischemia, the brain temperature of the U-80816E-treated gerbils was 2.2 degrees C lower than that of saline-treated animals. When the U-80816E-treated gerbils were subjected to either 10 or 15 minutes of ischemia but placed in a heated chamber that prevented the hypothermic effects, no cerebroprotection was observed. CONCLUSIONS: These results show that the anti-ischemic efficacy of U-80816E is mediated through its hypothermic properties, thus suggesting the feasibility of pharmacologically induced hypothermia as a cerebroprotective approach.     

Feed intake and milk production in dairy cows fed whole fat soybeans]

Although the effect of hyperoxia on antioxidant enzymes is well known, the effect of subtoxic levels of hyperoxia on gamma-glutamyltransferase (gamma-GT), involved in the degradation and uptake of extracellular GSH for intracellular GSH synthesis, is unknown. The aim of the study was to investigate (1) the effects of in vitro hyperoxia on gamma-GT activity of type II cells and (2) the effects of the lazaroid U-74389G and N-acetylcysteine (NAC) on the hyperoxia-induced changes in gamma-GT and antioxidant enzyme activities. At 48 h after isolation, rat type II cells were exposed for 2 days to air, 60% O2 or 85% O2 with or without 30 microM U-74389G or 100 microM NAC. After the exposure, the cells were harvested and assayed for superoxide dismutase (SOD), glutathione peroxidase (GPx), gamma-GT activity, and GSH levels. In another series of experiments 85% O2-exposed cells, with or without U-74389G, were used for Northern blotting of gamma-GT mRNA. Exposure to 60% O2 decreased gamma-GT and GSH by -47 and -34%, respectively, while SOD and GPx activities remained unchanged. After 85% O2-exposure gamma-GT decreased by -55%, SOD and GPx increased by +55 and +87%, respectively, while GSH decreased by -35%. NAC treatment decreased gamma-GT activity by -42% in the air-exposed cells. After 60% O2, U-74389G led to significantly higher gamma-GT (+117%) and GSH (+26%) while NAC only led to higher GSH (+28%) compared to the oxygen-exposed cells not treated with NAC or U-74389G. After 85% O2 U-74389G increased gamma-GT, SOD, and GSH by +72, +58, and +68%, respectively, while NAC only increased SOD (+49%) and GSH (+26%) compared to the oxygen-exposed cells not treated with NAC or U-74389G. The 85% O2 exposure, with or without U-74389G, had no effect on gamma-GT mRNA levels. The results show that hyperoxia decreases rat type II cell gamma-GT activity in vitro. This effect was not related to an altered regulation at mRNA level and it was not associated with the hyperoxia-induced decrease in intracellular GSH, since restoration of the GSH levels by NAC did not restore gamma-GT activity. The lazaroid U-74389G with vitamin E-like properties effectively prevented the decrease in gamma-GT and GSH, so that direct inactivation of the membrane-bound gamma-GT by hyperoxia is the most likely mechanism.     

Herpes simplex virus-2 infection. An emerging disease?

Hyperoxia, used therapeutically in the treatment of respiratory insufficiencies, can cause lung injury, probably through the actions of reactive oxygen species. The present studies were designed to test the hypothesis that oxidation of specific proteins would provide useful biomarkers of the onset of tissue injury, and thereby provide clues as to the mechanisms responsible. We exposed adult male Sprague-Dawley rats to room air or to greater than 95% O2 for 60 h and examined proteins in pleural effusion and broncho-alveolar lavage (BAL) fluids, and in lung tissue homogenates and subfractions. Oxidation of protein thiols was assessed by derivatization with monobromobimane, separation by electrophoresis, and visualization of the fluorescent thioether derivatives. Derivatization with 2,4-dinitrophenylhydrazine (DNPH), electrophoresis, and western analysis was employed to assess a different class of oxidative modifications, frequently termed 'protein carbonyls'. In addition, we investigated the effects of the 21-aminosteroid U-74389G, 10 mg/kg, given intraperitoneally every 12 h, on biomarkers of protein oxidation and on manifestations of lung injury. Hyperoxia caused lung injury evidenced by pleural effusions, increases in BAL protein concentrations, and pulmonary edema; U-74389G attenuated the first two indices of lung injury, but did not alter edema. Protein thiol status of the fractions studied were not affected notably by hyperoxia, or by the aminosteroid. The formation of DNPH-reactive sites on a limited number of proteins by hyperoxia was observed, and some of these effects were attenuated in the animals given U-74389G. Histological examination of lung tissues showed accumulation of intra-alveolar protein exudates in hyperoxic rats, and a significant attenuation of this effect was observed in the animals treated with U-74389G. In conclusion, studies of shifts in protein thiol status that may be caused by hyperoxia will require increasingly specific methods of analysis, and characterization of the specific DNPH-reactive proteins formed in hyperoxia may provide critical insights into the mechanisms of lung injury. Administration of U-74389G offers some degree of protection against hyperoxia and attenuation of these biomarkers of oxidation, but the precise mechanisms by which this protection is effected will require additional study.     

Reduction of central nervous system reperfusion injury in rabbits using doxycycline treatment

BACKGROUND AND PURPOSE: Activated leukocytes appear to potentiate central nervous system reperfusion injury, and agents that block leukocyte adhesion have shown neuroprotective efficacy in experimental models. Doxycycline, a tetracycline antibiotic, inhibits leukocyte function in vitro, presumably through divalent cation binding. We used a model of focal central nervous system reperfusion injury to determine the efficacy of doxycycline treatment in preserving neurological function. METHODS: Rabbits randomly received 10 mg/kg i.v. doxycycline 30 minutes before ischemia (pretreatment group) or 45 minutes after ischemia (posttreatment group) or received phosphate-buffered saline vehicle (control group) followed by 10 mg/kg q 8 hours times two. The average length of reversible spinal cord ischemia required to produce paraplegia (P50) at 18 hours was calculated for each group. RESULTS: For the control group (n = 13), the P50 was 22.8 +/- 2.2 minutes; for the pretreatment group (n = 14), 35.5 +/- 2.4 minutes (P < .01; t = 3.8); and for the posttreatment group (n = 13), 31.4 +/- 4.2 minutes (not significant; t = 1.6). Doxycycline also attenuated postischemic decreases in vivo leukocyte counts and inhibited in vitro leukocyte adhesion. Therapeutic doxycycline levels at 24 hours were confirmed in the plasma and spinal cord. CONCLUSIONS: This significant protective effect suggests that doxycycline, a safe and readily available agent, may play a role in reducing clinical central nervous system reperfusion injury.     

Lipid peroxidation after acute renal ischemia and reperfusion in rats: the effect of trimetazidine

Lipid peroxidation is a critical pathway of reactive oxygen species inducing tissue injury in postischemic acute renal failure. In order to evaluate the effect of renal ischemia reperfusion on kidneys, renal tissue malondialdehyde (MDA, nmol/g wet weight) concentration was measured in 29 male Wistar rats subjected to a midline abdominal incision and 60 min occlusion of the left renal artery. A right nephrectomy was performed at the beginning of the ischemic period. The animals were separated in four groups. Groups 1 (n = 7) and 3 (n = 7) underwent 60 min of ischemia and 15 min of reperfusion, respectively. Groups 2 (n = 8) and 4 (n = 7) were subjected to the same procedure but, in addition, they received 2.5 mg/kg TMZ into the tail vein 2 h prior to the left renal artery occlusion. A significant elevation of MDA after 60 min of ischemia (1.43 vs. 2.1, p < 0.001), which was augmented after 15 min of reperfusion (1.4 vs. 3.72, p < 0.001) was observed. Furthermore, there was a significant reduction of renal tissue MDA in ischemic rats treated with TMZ (group 3) (2.1 vs. 1.52, p < 0.001). The maximum reduction of renal tissue MDA was observed in ischemic-reperfused rats (group 4) that had received TMZ (3.72 vs. 1.36, p < 0.001). It is suggested that lipid peroxidation is a critical event in postischemic acute renal failure, and TMZ is a useful protective agent of renal damage from oxygen free radicals.     

Immunosuppressants decrease neutrophil chemoattractant and attenuate ischemia/reperfusion injury of the liver in rats

BACKGROUND: Neutrophils may play an important role in the development of liver ischemia/reperfusion injury. We investigated the effects of the immunosuppressants azathioprine (AZA), cyclosporine A (CsA), tacrolimus (FK506), and rapamycin (RPM) on the expression of cytokine-induced neutrophil chemoattractant (CINC) after ischemia/reperfusion of the liver. METHODS: Liver ischemia was induced in male Wistar rats by occluding the portal vein with a microvascular clip for 30 minutes. Rats received two intramuscular injections of AZA (4 mg/kg), CsA (5 mg/kg), FK506 (0.5 mg/kg), or RPM (0.5 mg/kg) 3 and 24 hours before ischemia/reperfusion of the liver. RESULTS: Serum CINC concentrations in untreated animals increased, peaked 6 hours after reperfusion, and thereafter decreased gradually. Pretreatment with AZA, CsA, FK506, and RPM, however, inhibited the increase in serum CINC concentrations after reperfusion. CINC mRNA in liver tissue increased and peaked 3 hours after reperfusion, but was significantly lower in animals treated with AZA, CsA, FK506, and RPM. In vitro CINC production by Kupffer cells harvested from animals treated with AZA, CsA, FK506, or RPM 3 hours after reperfusion was also significantly lower than that observed in untreated animals. Both myeloperoxidase activity and the number of neutrophils accumulating in the liver 24 hours after reperfusion in animals treated with AZA, CsA, FK506, and RPM were significantly lower than in untreated animals. This correlated with lower serum aspartate transaminase, alanine transaminase, and lactate dehydrogenase levels in animals treated with AZA, CsA, FK506, and RPM 24 hours after reperfusion. CONCLUSION: The immunosuppressants AZA, CsA, FK506, and RPM reduce neutrophil accumulation and attenuate ischemia/reperfusion injury of the liver.     

Temporal variation in hepatic superoxide dismutase activity in mice

Intestinal ischemia is a common clinical event and reperfusion results in further tissue damage exceeding that of ischemia alone. The present study was designed to test this and to assess the role of pentoxifylline, (administered intravenously as a bolus dose of 25 mg/kg in 1 ml normal saline, followed by continuous infusion of 0.2 mg/kg/minute for 95 minutes), in ischemia-reperfusion injury of the rat intestine. Intestinal ischemia was produced by occlusion of the superior mesenteric artery (SMA) with interruption of the collateral flow for 30 minutes. Reperfusion was established by declamping the (SMA) for 1 hour and evaluation of the mucosal damage was determined using a grading scale from 0 to 5, with estimation of mean mucosal thickness, villous height and crypt depth. The grade of mucosal damage, mucosal thickness, villous height and crypt depth were 2.2, 407 microns, 210 microns, and 196 microns respectively in the ischemia group, and 3.6, 327 microns, 156 microns, and 171 microns respectively in the ischemia reperfusion group, while these values in ischemia reperfusion with administration of pentoxifylline group were 2.5, 505 microns, 294 microns, and 200 microns respectively. The severity of the tissue injury increased considerably after reperfusion of the ischemic intestine and pentoxifylline was effective in attenuating the reperfusion injury significantly.     

Donor treatment with the lazeroid U74389G reduces ischemia-reperfusion injury in a rat lung transplant model

BACKGROUND: Antioxidant treatment with lazeroids has proven beneficial for the amelioration of reperfusion injury in experimental lung transplantation. This study compares the effect of donor versus recipient treatment on immediate postoperative graft function. METHODS: A model of acute double-lung transplantation in rats was used to assess graft function. Transplanted controls after 2 (group I) and 16 hours of ischemia (group II) were compared to a recipient (group III; 16-hour ischemia) and a donor treatment group (group IV; 16-hour ischemia) using the lazeroid U74389G (6 mg/kg). Serial assessment of alveolar-arterial oxygen difference, dynamic lung compliance, airway and pulmonary vascular resistance was obtained during a 2-hour reperfusion period. Final analysis included survival, weight gain, and histologic examination. RESULTS: Graft function was significantly better after 2 hours of ischemia than in any of the three 16-hour ischemia groups (II, III, IV). After 16 hours of ischemia, donor treatment provided superior graft function with respect to dynamic lung compliance, airway resistance, and alveolar-arterial oxygen difference when compared with groups II and III. The pulmonary vascular resistance was significantly higher in group III when compared with groups II and IV. Graft weight increase reflecting edema was highest in groups III (104%) and II (98%). CONCLUSIONS: After prolonged ischemia only donor treatment with the lazeroid U74389G was able to significantly reduce ischemia-reperfusion-related graft dysfunction.     

A CD18 antibody prevents lung injury but not hypotension after intestinal ischemia-reperfusion

Antibodies to the neutrophil CD18 integrin have been shown to ameliorate the local effects of intestinal ischemia and reperfusion (I/R). In addition to local mucosal injury, intestinal I/R results in systemic hypotension and injury to the lungs with lung leukosequestration. This study tests the effect of a CD18 monoclonal antibody on the hypotension and lung injury after intestinal I/R. In anesthetized rabbits, the superior mesenteric artery was clamped for 60 min followed by 3 h of reperfusion. Animals were treated with saline, an anti-CD18 monoclonal antibody (R15.7 MAb), or nonspecific immunoglobulin G. Another non-ischemic group were sham controls. Neutrophil sequestration was assessed by measure of lung myeloperoxidase (MPO) and permeability by lung-to-blood concentration ratio of 125I-labeled bovine serum albumin and wet-to-dry weight ratio. Immediately after reperfusion, mean arterial pressure fell to 49 +/- 2.1 mmHg and remained at this level. The hypotension was unaffected by treatment with R15.7 MAb. Thirty minutes after reperfusion, the circulating white blood cell count fell to 2.91 +/- 0.53 x 10(3)/mm3 vs. sham 6.40 +/- 0.66 x 10(3)/mm3 (P < 0.05). Treatment with R15.7 MAb prevented this fall in white blood cell count (5.75 +/- 1.59 x 10(3)/mm3). At 3 h of reperfusion in saline-treated animals there was increased MPO, 74.8 +/- 4.9 U/g vs. 42.0 +/- 4.8 U/g in sham animals (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Arginine vasopressin release inhibitor RU51599 attenuates brain oedema following transient forebrain ischaemia in rats

RU51599 is an arginine vasopressin (AVP) release inhibitor and a selective kappa opioid agonist which has a pure water diuresis effect without associated electrolyte excretion. The effect of RU51599 on brain oedema following transient forebrain ischaemia in rats was examined. Under microscopy, the visible vertebral arteries at the second vertebra could be easily electrocauterized and completely cut by microscissors to yield complete cessation of circulation of both vertebral arteries. Transient forebrain ischaemia was induced by this improved highly reproducible technique of four-vessel occlusion model. Forty-three male Wistar rats were separated into six groups; saline-treated (1 ml/kg) normal rats (n = 10), RU51599-treated (1 mg/kg) normal rats (n = 4), saline-treated (1 ml/kg) rats with complete occlusion of both vertebral arteries (n = 5), RU51599-treated (1 mg/kg) rats with complete occlusion of both vertebral arteries (n = 5), saline-treated (1 ml/kg) rats with both complete occlusion of both vertebral arteries and carotid occlusion bilaterally during 45 minutes followed by 60 minutes of reperfusion (n = 11), RU51599-treated (1 mg/kg) rats with both complete occlusion of both vertebral arteries and carotid occlusion bilaterally during 45 minutes followed by 60 minutes of reperfusion (n = 8). The brain water content was determined by the dry-wet weight method. Cerebral blood flow was monitored during ischaemia and reperfusion was performed by laser Doppler flowmetry to make sure to obtain reversible forebrain ischaemia. Effects of RU51599 on concentration of glutamate released from the hippocampal CA1 of rats subjected to 5 minutes four-vessel occlusion and 60 minutes of reperfusion were also investigated by the microdialysis method. This modified four-vessel occlusion method produced reversible forebrain ischaemia with a high level of success. Bilateral carotid occlusion followed by 60 minutes reperfusion caused a significant increase in brain water content (P < 0.01), which was significantly attenuated by RU51599 (P < 0.01). These findings indicate that the AVP-release inhibitor RU51599 reduced brain oedema following transient forebrain ischaemia in rats.     

The relationship between the adenine nucleotide metabolism and the conversion of the xanthine oxidase enzyme system in ischemia-reperfusion of the rat small intestine

The time course of the energy metabolism after reperfusion, the relationship between the conversion of xanthine dehydrogenase to xanthine oxidase (D-to-O conversion) during ischemia, and the changes of the energy metabolism after reperfusion were studied using an ischemia-reperfusion model in the small intestine of the rat. The rat jejunum underwent an occlusion of the superior mesenteric artery and vein for either 30 minutes (group 1, n = 6) or 90 minutes (group 2, n = 6) with collateral interruption, and then it was reperfused. The contents of the adenine nucleotides in the small intestine of the rat were measured by high-performance liquid chromatography (HPLC) before ischemia, and 30, 60, and 90 minutes of ischemia, as well as 30, 60, 120, and 180 minutes after reperfusion. The recovery level of adenosine triphosphate (ATP) in group 1 (6.05 +/- 0.80 mumol/g dry weight) 30 minutes after reperfusion was significantly higher than that in group 2 (2.28 +/- 1.12 mumol/g dry weight) (P < .001). In addition, the ATP content after reperfusion in group 2 did not change from 30 to 180 minutes after reperfusion. The D-to-O conversion during ischemia in group 1 was not significantly greater than that before ischemia; however, that of group 2 did increase significantly during ischemia (P < .005). These results suggest that the tissue damage from ischemia-reperfusion injury after reperfusion under 90 minutes' ischemia is accomplished within the first 30 minutes after reperfusion. Therefore, the ATP level at 30 minutes after reperfusion may be useful for the evaluation of intestinal viability. Thus, the conversion of the xanthine oxidase enzyme system might play an important role in the expression of ischemia-reperfusion injury.     

Plasma nitrogen oxides and blood lactate concentrations in Ghanaian children with malaria

OBJECTIVES: To titrate a clinically effective eltenac dosage (0.1, 0.5, and 1.0 mg/kg of body weight), compared with vehicle only, and to compare efficacy of the most effective eltenac dosage with that of 1.1 mg of flunixin meglumine/kg. ANIMALS: 40 healthy horses, ranked after model induction on the basis of lameness severity, were randomly assigned to 5 treatment groups, with 4 replicates of 10 horses each. PROCEDURE: On day -5, after surgical preparation of the left carpal region, 0.7 ml of Freund's complete adjuvant was injected into the intercarpal space. Horses were observed daily, from the day of carpitis induction to day 0, when stride length was used as the method of ranking horses for randomization to treatment assignment. Treatments were administered i.v. once daily for 3 consecutive days, starting on day 0. Prior to carpitis induction on day -5, and at time 0 (pretreatment), 2, 4, 12, 24, 36, 48, 60, 72, and 96 hours after treatment initiation, resting respiratory rate and pulse, rectal temperature, carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain were recorded. RESULTS: Compared with the vehicle and 0.1 mg of eltenac/kg, 0.5 and 1.0 mg/kg caused statistically significant improvements (ie, reduction of carpal circumference, increase in carpal flexion angle, and increase in stride length of the affected limb), but values did not differ significantly between the 2 dosages. Thus, a dose-response plateau for eltenac was reached at 0.5 mg/kg. Comparison with flunixin meglumine at a dosage of 1.1 mg/kg did not indicate significant differences between the 2 treatment groups at the pivotal time of 96 hours for carpal circumference, carpal flexion angle, stride length, carpal hyperthermia, and signs of carpal pain. Adverse reactions were not observed. CLINICAL RELEVANCE: Under conditions of this study, a dosage plateau for eltenac was determined (0.5 mg/kg) that was statistically equivalent to eltenac (1.0 mg/kg) and flunixin meglumine (1.1 mg/kg) in a 3-day i.v. dosing regimen.     

Dendritic orientation of thalamocortical projection neurons in the ventrobasal complex of macaques

The present study measured the production of eicosanoids in the gerbil brain during early reperfusion after either a 3-h unilateral carotid occlusion (UCO, model of focal ischemia) or a 10-min bilateral carotid occlusion (BCO, model of global ischemia). Arachidonic acid (AA) metabolites were examined to determine if pretreatment with the 21-aminosteroid lipid peroxidation inhibitor U-74006F (tirilazad mesylate) could influence postreperfusion synthesis of brain eicosanoids. In the 3-h UCO focal ischemia model, there was an early (5-min) postreperfusion elevation in brain levels of PGF2 alpha, TXB2 and LTC4 (P < 0.05 vs. sham for all three eicosanoids). LTB4 also rose but not significantly. On the other hand, PGE2 and 6-keto-PGF1 alpha tended to decrease during ischemia and at 5-min postreperfusion (P < 0.05 vs. sham for PGE2). Pretreatment with known neuroprotective doses of U-74006F in this model (10 mg/kg i.p. 10 min before and again immediately upon reperfusion) did not affect the increase in PGF2 alpha or TXB2 but significantly blunted the elevations in LTC4 and LTB4. The postreperfusion decrease in PGE2 was also attenuated. In the 10-min BCO global ischemia model, there was also an increase in each of the measured eicosanoids, except LTB4, at 5 min after reperfusion. Pretreatment with U-74006F (10 mg/kg i.p. 10 min before ischemia) selectively decreased the rise in LTC4 but did not significantly affect the other eicosanoids. In contrast, the antioxidant actually caused a significant enhancement of the postreperfusion increase in PGE2 vs. vehicle-treated animals.(ABSTRACT TRUNCATED AT 250 WORDS)