Pathogenesis of ischemia reperfusion injury of the kidney after transient renal arterial clamping in rats

Renal function can be severely impaired through injuries sustained after both short and prolonged periods of complete ischemia. The magnitude of renal dysfunction resulting from these conditions and their reversibility depend on the duration of anoxia. In this study, we used a Sprague-Dawley rat model (5 to 7 rats in each group) to study the pathogenesis of short-term ischemia (30, 60, and 120 min)/reperfusion (2, 4, 24 h, 1 wk, and 3 wk) injury of the kidney under warm (room temperature) or cold (4 degrees C) conditions. Ischemia was induced by clamping the renal artery. Changes in kidney weight, histopathology, concentrations of serum thromboxane and leukotriene, and tissue malonyldialdehyde (MDA) concentration, numbers of apoptotic bodies, and p53 expression in the kidney were compared with those of sham-operated rats. The results showed that the immediate increase in kidney weight due to inflammatory swelling was associated with simultaneous elevation of serum thromboxane and leukotriene levels. The changes in mediator levels were closely related to the duration of ischemia and temperature. Histologic structures were preserved better when renal artery clamping was done at 4 degrees C. MDA peroxidation products from the ischemic tissue prominently increased 1 week following ischemia; this paralleled a secondary increase in leukotriene levels. Flow cytometric detection of p53 oncoprotein showed a marked increase at 1 week following ischemia, which was accompanied by the development of apoptotic bodies in ischemic tissues. These changes were also closely related to the ischemic time and temperature during ischemia. This animal model may be useful for future studies of the prevention of ischemia/reperfusion injury of the kidney and for selection of effective antioxidants.     

Lipid peroxidation and antioxidant system changes in acute L-arginine pancreatitis in rats

The World Wide Web-based form is a promising method for the construction of an on-line data collection system for clinical and epidemiological research. It is, however, laborious to prepare a common gateway interface (CGI) program for each project, which the World Wide Web server needs to handle the submitted data. In medicine, it is even more laborious because the CGI program must check deficits, type, ranges, and logical errors (bad combination of data) of entered data for quality assurance as well as data length and meta-characters of the entered data to enhance the security of the server. We have extended the specification of the hypertext markup language (HTML) form to accommodate information necessary for such data checking and we have developed software named AUTOFORM for this purpose. The software automatically analyzes the extended HTML form and generates the corresponding ordinary HTML form, 'Makefile', and C source of CGI programs. The resultant CGI program checks the entered data through the HTML form, records them in a computer, and returns them to the end-user. AUTOFORM drastically reduces the burden of development of the World Wide Web-based data entry system and allows the CGI programs to be more securely and reliably prepared than had they been written from scratch.     

Lipid peroxidation and phospholipid composition in rat brain regions after ischemia and in early perfusion periods

A configuration of bi-group neural networks (BGNN) is proposed combined with an evidential reasoning framework to interpret 12-lead electrocardiograms for three mutually exclusive classes. A number of pre-processing feature selection techniques were investigated prior to application of the input feature vector to each individual BGNN. The network outputs were discounted within a belief interval of 1 based on their performance on test data prior to combination. It was found that the application of the feature selection techniques enhanced the individual performance of the BGNN, and subsequently enhanced the overall performance. The proposed framework was compared with conventional classification techniques of multi-output neural networks and linear multiple regression. The framework attained a higher level of classification in comparison with the other methods; 70.4% compared with 66.7% for both multi-output neural and statistical techniques.     

Effects of nimodipine on acute cerebral ischemia and reperfusion injury of rats

AIM: To study the effect of nimodipine (Nim) on ischemic cerebral damage. METHODS: The four-vessel occlusion method was performed on rats. Monoamines were measured by fluorospectrophotometry. RESULTS: Intraperitoneal injection of Nim 0.75 and 1.5 mg.kg-1 quickened the recovery of EEG changes to 19 +/- 3 and 17 +/- 4 min (P < 0.01), respectively. Nim reduced the decreases of monoamines (NE, DA, 5-HT, and 5-HIAA) contents after 30-min cerebral ischemia and 1-h reperfusion. CONCLUSION: Nim protects the brain from ischemic damage.     

Decreased complement activity after bilateral renal ischemia in rats

The bilateral occlusion of the renal arteries for 2h resulted in a marked decrease of serum complement activity after recirculation. The release of a proteinic factor with anticomplementary activity detectable in vitro in normal kidney supernate is considered a probable cause of the phenomenon. This factor is able to activate the alternative complement pathway in human serum.     

Lipid peroxidation and antioxidant status in the liver, erythrocytes, and serum of rats after methanol intoxication

Lipid peroxidation products measured as a malondialdehyde and activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), and concentrations of ascorbic acid, alpha-tocopherol, and glutathione (GSH) were measured in the liver, erythrocytes, and serum of rats 6, 14, and 24 h and 2, 5, and 7 d after treatment with 3 g methanol/kg. GSH-Px and GSSG-R activities, GSH level, and ascorbate concentration in the liver, erythrocytes, and blood serum were significantly decreased. In addition, SOD and alpha-tocopherol in erythrocytes were diminished, while malondialdehyde (MDA) in liver, erythrocytes, and serum were elevated. Further, erythrocyte counts, hemoglobin levels, hematocrit, and mean corpuscular volume (MCV) were reduced. These results indicate that methanol intoxication in rats leads to an increase in the lipid peroxidation and impairment in the antioxidant mechanisms in liver, erythrocytes, and blood serum.     

Reperfusion injury: demonstration of brain damage produced by reperfusion after transient focal ischemia in rats

During reperfusion after ischemia, deleterious biochemical processes can be triggered that may antagonize the beneficial effects of reperfusion. Research into the understanding and treatment of reperfusion injury (RI) is an important objective in the new era of reperfusion therapy for stroke. To investigate RI, permanent and reversible unilateral middle cerebral artery/common carotid artery (MCA/CCA) occlusion (monitored by laser Doppler) of variable duration in Long-Evans (LE) and spontaneously hypertensive (SH) rats and unilateral MCA and bilateral CCA occlusion in selected LE rats was induced. In LE rats, infarct volume after 24 hours of permanent unilateral MCA/CCA occlusion was 31.1 +/- 34.6 mm3 and was only 28% of the infarct volume after 120 to 300 minutes of reversible occlusion plus 24 hours of reperfusion, indicating that 72% of the damage of ischemia/reperfusion is produced by RI. When reversible ischemia was prolonged to 480 and 1080 minutes, infarct volume was 39.6 mm3 and 16.6 mm3, respectively, being indistinguishable from the damage produced by permanent ischemia and significantly smaller than damage after 120 to 300 minutes of ischemia. Reperfusion injury was not seen in SH rats or with bilateral CCA occlusion in LE rats, in which perfusion is reduced more profoundly. Reperfusion injury was ameliorated by the protein synthesis inhibitor cycloheximide or spin-trap agent N-tert-butyl-alpha-phenylnitrone pretreatment.     

The protective effects of dichloroacetate on cerebral ischemia after reperfusion of fed rats

OBJECTIVE: To study the brain protective mechanisms of dichloroacetate (DCA) by observing the influence of DCA on the biochemical and pathological changes in ischemic brain tissues in different periods of reperfusion. METHODS: The FED-RAT cerebral ischemic model induced by 4-vessel occlusion was applied. 55 mature male Sprague-Dawley rats were divided into the control group, normal saline and DCA-treated groups before ischemia, normal saline and DCA-treated groups after ischemia equally and randomly. RESULTS: DCA could significantly lower the brain lactic acid, water content, and the diameter of cortical neurons, and protect the pathological damage of the membranaceous structure, before or after ischemia at a dose of 25 mg/kg, compared with the normal saline treated groups. CONCLUSION: Lowering brain lactate, resisting brain edema and protecting the membranaceous structures are the main brain protective mechanisms of DCA in biochemistry and ultrastructure.     

Lipid peroxidation and lysosomal integrity in different inflammatory models in rats: the effects of indomethacin and naftazone

The authors tried to establish quantitative and qualitative acoustic parameters of a good voice, suitable for future voice professionals. In their work they used long-time average spectrum analysis (LTAS) and three-dimensional analysis of periodicity (3D-PAN). They consider the regression straight line of formant regions and the parameters offered by 3D-PAN--jitter first of all--as the main acoustic parameters for the evaluation of voice quality and draw attention to the fact that acoustic parameters represent only one part of the evaluation of voice quality.     

Lipid peroxidation contributes to hydrogen peroxide induced cytotoxicity in renal epithelial cells

During inflammation neutrophils receive multiple signals that are integrated, allowing a single modified response. One mechanism for this discrimination is receptor desensitization, a process whereby ligand-receptor binding is disassociated from cell activation. We examined the effect of heterologous receptor desensitization on neutrophil chemotaxis, calcium mobilization, and arachidonic acid production, using interleukin-8 (IL-8), C5a, and N-formyl-methionyl-leucyl-phenylalanine (fMLP). We observed reciprocal inhibition with respect to chemotaxis. We demonstrated that homologous desensitization, with respect to the mobilization of intracellular calcium stores, lasted approximately 15 min. Heterologous desensitization between the fMLP receptor and the C5a receptor was reciprocal; either stimulant would diminish the cells' response to stimulation by the other for approximately 3-5 min. However, we observed a unidirectional heterologous desensitization of the IL-8 receptor by both the fMLP and the C5a receptor. This unidirectional heterologous desensitization was observed with respect to both calcium mobilization and arachidonic acid production (i.e., prestimulation of the IL-8 receptor had no effect on subsequent stimulation by either fMLP or C5a).     

Downregulation of calpastatin in rat heart after brief ischemia and reperfusion

The activities of calpain and its endogenous inhibitor, calpastatin, were measured in the soluble fraction of perfused rat heart after ischemia for 5-20 min and reperfusion for up to 30 min. The method for m-calpain measurement was modified: washing of the DEAE-cellulose column with 0.18 M NaCl instead of 0.15 M NaCl increased the m-calpain activity 12.5-fold. Ischemia for 20 min followed by reperfusion for 30 min did not affect the m-calpain activity but decreased the calpastatin activity. m-Calpain was enriched in the nucleus-myofibril fraction but was not further translocated on ischemia-reperfusion. Mu-calpain was below the limit of detection on immunoblotting or casein zymography, but its mRNA was substantially expressed, as detected on Northern blotting. Casein zymography also revealed a novel Ca2+-dependent protease without the typical characteristics of mu- or m-calpain. The immunoblotting of myocardial fractions showed that calpastatin was proteolyzed on ischemia-reperfusion. The calpastatin proteolysis was suppressed by a calpain inhibitor, Ac-Leu-Leu-norleucinal. Calpastatin may sequester calpain from its substrates in the normal myocardium, but may be proteolyzed by calpain in the presence of an unidentified activator in the early phase of calpain activation during ischemia-reperfusion, resulting in the proteolysis of calpastatin and then other calpain substrates.     

Healing of tibial fractures is not impaired after acute hindlimb ischemia in rats

The influence of transient circulatory arrest on the healing of closed tibial fractures was investigated in rats by the use of a hindlimb tourniquet technique. Twenty-four animals were randomly divided into three groups. In all animals, the left lower leg was fractured and fixed with an intramedullary nail system. In the ischemic group, complete acute transient ischemia for 4.5 h and neurapraxia of the sciatic and femoral nerves were induced prior to fracture. In the neurapraxia group, the sciatic and femoral nerves were crushed with forceps before fracture. In the control group, no other intervention than fracture was made. The rats of the control group ambulated normally 3-4 days after the operation. The animals of the ischemic and neurapraxia groups resumed normal weight-bearing after about 3 weeks. After 6 weeks, all animals were killed, and mechanical strength and bone mineral turnover of the healing tibia as well as blood flow of the bone and musculature were evaluated. The weight of the tibia and the corresponding anterior tibial muscle in the ischemic and neurapraxia animals were reduced compared with the control rats. Bone mineral turnover was found to be lower in the ischemic group. There were no differences between the groups in mechanical strength nor in blood circulation of bone and muscle. In conclusion, complete, acute hindlimb ischemia for 4.5 h in rats did not cause delayed healing of closed tibial fractures.     

Protective effect of hyperin against myocardial ischemia and reperfusion injury

AIM: To study the protective and antiperoxidative effects of hyperin (hyperoside; quercetin-3-O-galactoside; Hyp) on myocardial ischemia/reperfusion. METHODS: The rabbit anterior descenging branch of left coronary artery was occluded for 60 min and then released to allow reperfusion for 20 min. Hemodynamics (LVP, LV +/- dp/dt) and electrocardiogram (ECG, lead II) were monitored continuously with polygraph. After reperfusion, the blood sample and myocardium were taken to assay plasma creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and cations in myocardium. Using a Langendorff system, the isolated heart of rat was initiated by ischemia for 40 min followed by 30 min of reperfusion. Malondialdehyde (MDA) contents of cardiac effluent and myocardium were measured with fluorescence spectrophotometer. RESULTS: Hyp 10 mg.kg-1 i.v. depressed changes in LVP, LV +/- dp/dtmax, ECG, plasma CPK, LDH, and cations (Ca2+, Mg2+, Na+) in myocardium induced by ischemia/reperfusion in rabbits. Hyp 10 and 100 mumol.L-1 markedly reduced the increase in MDA production in isolated rat hearts after ischemia/reperfusion. CONCLUSION: Hyp possesses a protective effect against myocardial ischemia/reperfusion injury via attenuating lipid peroxidation.     

Controlled reperfusion after lung ischemia: implications for improved function after lung transplantation

OBJECTIVES: Despite improvements in organ preservation, reperfusion injury remains a major source of morbidity and mortality after lung transplantation. This pilot study was designed to investigate the effects of controlled reperfusion after lung ischemia. METHODS: Twenty adult pigs underwent 2 hours of warm lung ischemia by crossclamping the left bronchus and pulmonary artery. In five (group 1), the clamp was simply removed at the end of ischemia (uncontrolled reperfusion). The 15 other pigs underwent modified reperfusion using blood from the femoral artery to perfuse the lung through the pulmonary artery (pressure 40 to 50 mm Hg) for 10 minutes before removing the pulmonary artery clamp. In five (group 2), the blood was mixed with crystalloid, resulting in a substrate-enriched, hypocalcemic, hyperosmolar, alkaline solution. In five (group 3), the blood was circulated through a leukocyte-depleting filter, and the last five (group 4) underwent reperfusion with both a modified solution and white blood cell filter. Lung function was assessed 60 minutes after reperfusion, and biopsy specimens were taken. RESULTS: Controlled reperfusion with both a white blood cell filter and modified solution (group 4) completely eliminated the reperfusion injury that occurred with uncontrolled reperfusion (group 1), resulting in complete preservation of compliance (98% +/- 1% vs 77% +/- 1%; p < 0.001, and arterial/alveolar ratio (97% +/- 2% vs 27% +/- 2%; p < 0.001); no increase in pulmonary vascular resistance (106% +/- 1% vs 198% +/- 1%; p < 0.001); lowered tissue edema (82.1% +/- 0.4% vs 84.3% +/- 0.2%; p < 0.001), and myeloperoxidase activity (0.18 +/- 0.02 vs 0.35 +/- 0.02 deltaOD/min/mg protein; p < 0.001). In contrast, using either a white blood cell filter or modified solution separately improved but did not avoid the reperfusion injury, resulting in pulmonary function and tissue edema levels that were intermediate between group 1 (uncontrolled reperfusion) and group 4 (white blood cell filter and modified solution). CONCLUSION: After 2 hours of warm pulmonary ischemia, (1) a severe lung injury occurs after uncontrolled reperfusion, (2) controlled reperfusion with either a modified reperfusion solution or white blood cell filter limits, but does not avoid, a lung reperfusion injury, (3) reperfusion using both a modified reperfusate and white blood cell filter results in complete preservation of pulmonary function. We therefore believe surgeons should control the reperfusate after lung transplantation to improve postoperative pulmonary function.