The effects of chronic alpha-tocopherol administration on lipid peroxidation in an experimental model of acute spinal cord injury

Most of the numerous experimental studies to research pathophysiological changes following acute spinal cord injury suggest a two-step mechanism of damage to the spinal cord in which the primary (direct) or mechanical injury caused by the trauma initiates secondary (indirect) or progressive autodestructive injury of the cord. During recent years, free oxygen radical generation and lipid peroxidation have been considered to be responsible for secondary autodestructive injury.Alpha tocopherol occupies an important and unique position in the overall antioxidant defense. Alpha tocopherol-depleted animals are generally more susceptible to the adverse effects of environmental agents than are supplemented animals. This study was planned to study the effectiveness in counteracting this autodestructive process by supplementing alpha-tocopherol in rats maintained on a nutritionally adequate diet, and also to evaluate whether it will provide additional protection or not. Eighty healthy Wistar rats (treatment and controls) were included. The treatment group received 100 mg/kg alpha tocopherol each day, intraperitoneally for seven days. Using a standard acute spinal cord trauma model in Wistar rats trauma was applied, an malondialehyde (MDA) which is a lipid peroxidation product was measured in the traumatized spinal cord at various times following the trauma in order to indirectly evaluate the lipid peroxidation and generation of free oxygen radicals in a time sequence. Statistical analysis of the values demonstrated that malondialdehyde formation in the alpha-tocopherol administered group was significantly lower than in the control group. These findings indicate that longterm administration of alpha-tocopherol may be useful to decrease lipid peroxidation following acute spinal cord trauma.     

Direct cytotoxic effect of oxygen radicals on the gastric mucosa

Oxygen radical release has been proposed as a pathogenetic factor in the formation of acute gastric mucosal injury. We assessed the ability of the naturally occurring oxygen radical generating system hypoxanthine/xanthine oxidase (HX/XO) to cause gross gastric mucosal injury and measured the effect on regional mucosal blood flow. Local intra-arterial infusion of HX/XO into the vascular network of the stomach caused marked gross mucosal injury in the antrum and corpus. This injury occurred even in the absence of exogenous luminal acid and was aggravated by luminal acidification with 1 ml of 0.1N HCl. The selective oxygen radical scavenger superoxide dismutase (SOD) prevented mucosal injury caused by HX/XO. The effects of HX/XO and SOD were not mediated by alterations in regional gastric mucosal blood flow, as measured by the radiolabeled microspheres and reference sample method. These findings suggest that oxygen radicals are capable of causing substantial gastric mucosal injury by a direct cytotoxic effect independent of luminal acid or mucosal blood supply and give support to the concept that oxygen radical release may be a major primary pathogenetic factor in the development of acute gastric mucosal injury.     

Toxic oxygen metabolites induce vasoconstriction and bronchoconstriction in isolated, plasma-perfused rat lungs

Effects of toxic oxygen metabolites (TOM) on the pulmonary vascular bed and airways were studied in isolated, plasma-perfused rat lungs. TOM were generated by xanthine oxidase (XO) (0.1 or 0.25 unit.ml-1) and hypoxanthine (HX) (1 mol.l-1). In vitro measurements by chemiluminescence indicated that the major oxygen metabolite generated by XO and HX was H2O2. Measurements of PO2 in the perfusate as an indicator of O2-consumption suggested that production of TOM by XO and HX was finished within 30 min. XO and HX induced an early dose-dependent bronchoconstriction and a late increase in transpulmonary pressure (Ptp). Pulmonary arterial pressure (Ppa) increased gradually and levelled off within 30 min with low-dose XO, but not with high-dose XO. As judged by weight increase of the lungs, interstitial edema occurred regularly. Allopurinol, an inhibitor of XO, blocked the lung responses caused by XO and HX. Catalase attenuated all lung responses induced by XO and HX, while superoxide dismutase had no effect. The hydroxyl radical scavenger dimethylsulfoxide abolished the increase in Ptp and attenuated the increase in Ppa, but did not consistently protect the lungs from edema development. This study shows that TOM induce vasoconstriction, bronchoconstriction and lung edema in plasma-perfused rat lungs, mainly due to generation of H2O2 and the hydroxyl radical.     

Xanthine oxidase-derived oxygen radicals induce pulmonary edema via direct endothelial cell injury

Pulmonary hypoperfusion/ischemia-reperfusion (I/R) may initiate ARDS (nonhydrostatic pulmonary edema). Endothelial damage via xanthine oxidase (XO)-derived oxygen radicals (O2*) may mediate I/R injury. We previously documented Factor VIII antigen (F8) as a marker for endothelial injury. The purpose of this study was to (1) document I/R-induced nonhydrostatic pulmonary edema, (2) identify whether XO or O2* mediates nonhydrostatic edema, and (3) identify the site of injury (? endothelium). Rat lungs were isolated, ventilated, and perfused (100 min, control, or 40 min at 37 degrees C, I (static vent.), + 60 min, R). Effluent was analyzed for F8 release (ELISA: data relative to control). Tungsten-fed rats had negligible lung XO vs rats fed standard diet (3.6 vs 34.5 mU/g, (P less than 0.05). Catalase (CAT) 50 micrograms/ml) was added to perfusate prior to R. Sectioned lungs were fluorescein anti-F8 photographed (IF) and qualitatively assessed. (Table: see text). We conclude that (1) pulmonary hypoperfusion (I/R) leads to nonhydrostatic pulmonary edema, and (2) the edema results in part from XO-generated O2* directed at the capillary endothelium.     

Linking uric acid metabolism to diabetic complications

Hyperuricemia have been thought to be caused by the ingestion of large amounts of purines, and prevention or treatment of hyperuricemia has intended to prevent gout. Xanthine dehydrogenase/xanthine oxidase (XDH/XO) is rate-limiting enzyme of uric acid generation, and allopurinol was developed as a uric acid (UA) generation inhibitor in the 1950s and has been routinely used for gout prevention since then. Serum UA levels are an important risk factor of disease progression for various diseases, including those related to lifestyle. Recently, other UA generation inhibitors such as febuxostat and topiroxostat were launched. The emergence of these novel medications has promoted new research in the field. Lifestyle-related diseases, such as metabolic syndrome or type 2 diabetes mellitus, often have a common pathological foundation. As such, hyperuricemia is often present among these patients. Many in vitro and animal studies have implicated inflammation and oxidative stress in UA metabolism and vascular injury because XDH/XO act as one of the major source of reactive oxygen species Many studies on UA levels and associated diseases implicate involvement of UA generation in disease onset and/or progression. Interventional studies for UA generation, not UA excretion revealed XDH/XO can be the therapeutic target for vascular injury and renal dysfunction. In this review, the relationship between UA metabolism and diabetic complications is highlighted.     

Role of norepinephrine and excitatory amino acids in edema of the spinal cord after experimental compression injury in rats

The role of norepinephrine and excitatory amino acids in edema of the spinal cord after an acute experimental compression injury was studied in rats. Control rats received the compression injury only. Intraspinal norepinephrine was depleted in one rat group by injection of 6-hydroxydopamine (6-OHDA) into the subarachnoid space to selectively destroy catecholamine neurons and in a third group MK-801 was administered intravenously to block receptors for N-methyl-d-aspartate (NMDA), an excitatory amino acid. Recovery from motor paralysis and suppression of edema of the spinal cord were then compared in the three groups. Significant recovery from motor paralysis was found 12 h after injury in the 6-OHDA-treated rats, compared with the controls, and 24 h after injury in the MK-801-treated rats. Edema of the spinal cord was significantly suppressed for up to 24 h after injury in the 6-OHDA-treated rats. The MK-801-treated rats showed no significant suppression of the edema until 24 h after the spinal cord injury. It was concluded that norepinephrine is primarily involved in the formation of vasogenic edemas, which develop in the early stages after an injury, whereas excitatory amino acids affect the formation of cytotoxic edemas, which develop at a relatively later stage. Received for publication on March 26, 1997; accepted on July 8, 1997     

Pivotal role of xanthine oxidase in the initiation of tubulointerstitial renal injury in rats with hyperlipidemia

Hyperlipidemia can induce or aggravate renal tubulointerstitial injury. Experiments in a complex rat model with chronic glomerulonephritis and long-standing, coexisting hyperlipidemia suggested that induction of xanthine oxidase (XO), with increased oxygen radical generation, is involved in aggravation of tubulointerstitial injury. To separate the role of XO in the initial events of lipid-mediated tubulointerstitial injury, short-term experiments with diet-induced hyperlipidemia over 21 and 35 days were performed in otherwise healthy rats. XO expression in relation to the antioxidant enzymes was examined in the cortical tubulointerstitium (TIS) and proximal tubules (PT). Subsequent experiments with XO inhibition were performed, examining tubulointerstitial infiltration with ED1-positive cells and expression of adhesion molecules and monocyte chemoattractant protein-1 (MCP-1) as indicators of early injurious events. Hyperlipidemia increased XO activity in TIS by 40 and 86%, and in PT by 28 and 90% at days 21 and 35, compared with controls on regular diet. This increased activity was associated with increased reactive oxygen species. Among the antioxidant enzymes, glutathione peroxidase activity increased in TIS by 40% and in PT by 90%. Histological evaluation showed a three-fold increase in ED1-positive cells and increased MCP-1 and vascular cell adhesion molecule-1 (VCAM-1) expression at day 35 in the TIS. Inhibition of XO prevented tubulointerstitial ED1 cell infiltration, together with a decreased expression of MCP-1 and VCAM-1. These results point to an important role for XO in the early stage of hyperlipidemia-associated renal injury, mediating macrophage infiltration by a putatively redox-dependent upregulation of MCP-1 and VCAM-1.     

Investigation of the oxidative effect of chronic hyperammonemia on the kidney and the possible protective effect of allopurinol

Although there have been many studies on this topic, the molecular mechanism of the toxic effects of hyperammonemia on cells has not yet been fully explained. Recent studies have held oxidative stress mechanisms responsible for hyperammonemia-induced cell damage. Kidney functions are affected in diseases associated with an increase in ammonia in the blood. Our study tries to determine whether oxidative stress mechanisms are responsible for kidney damage in chronic hyperammonemia. We also investigated whether kidney damage is dependent on possible reactive oxygen products associated with the xanthine oxidase (XO) enzyme and whether the possible association can be inhibited with allopurinol, an XO enzyme inhibitor. The study took into consideration the enzyme activities of XO, xanthine dehydrogenase (XDH), superoxide dismutase (SOD), glutathione-S-transferase (GST), as well as protein thiol (P-SH) and malondialdehyde (MDA) levels. The data found demonstrated that chronic hyperammonemia had oxidative stress effects on the kidney, and that kidney XO and XDH activity changed. However, it was not possible to inhibit this oxidative stress in the kidney using allopurinol. Thus, we could not conclude that oxidative stress is an XO-dependent mechanism. The outcomes of the study suggested that this oxidative situation arising in hyperammonemia occurred through a mechanism other than the XO enzyme.     

Histologic characterization of acute spinal cord injury treated with intravenous methylprednisolone

OBJECTIVE: Many substances have been investigated for attenuation of spinal cord injury after acute trauma; however, pharmacologically only steroid administration has shown clinical benefits. This study attempts to characterize local spinal cord histologic response to human dose equivalent (HDE) intravenous methylprednisolone (MP) administration in a rodent model of acute spinal cord injury. DESIGN: Forty-eight Sprague-Dawley rats were divided equally into control and experimental groups. Each group was subdivided into eight sets of three animals each, according to postinjury intervals. Paraplegia after lower thoracic laminectomy was achieved using a standardized weight drop technique. INTERVENTION: Within one hour, experimental animals were treated with HDE MP followed by 23-hour continuous infusion of HDE MP. Spinal cords were harvested at variable intervals postinjury and prepared for histologic/immunohistochemistry examination. MAIN OUTCOME MEASUREMENTS: Edema, necrosis, and glial fibrillary acidic protein (GFAP) positivity in the specimens from treated/control groups were graded by microscopy and immunohistochemistry staining and compared in a blinded manner by a qualified neuropathologist and senior authors. RESULTS: Minimal differences were observed between control and MP-treated animals at zero and four hours. At eight hours, increased white matter and medullary edema was evident in control versus MP-treated rats. This trend continued through twelve, sixteen, twenty-four, forty-eight, and seventy-two hours. No difference was observed in the astrocytic response to injury by GFAP immunohistochemistry between the groups. CONCLUSIONS: Histologically, MP reduces the development of severe edema and preserves spinal cord architecture adjacent to the site of injury. In contrast, MP does not alter the development of spinal cord necrosis or astrocytic response at the zone of injury.     

Increased protein oxidation and decreased creatine kinase BB expression and activity after spinal cord contusion injury

Traumatic injury to the spinal cord triggers several secondary effects, including oxidative stress and compromised energy metabolism, which play a major role in biochemical and pathological changes in spinal cord tissue. Free radical generation and lipid peroxidation have been shown to be early events subsequent to spinal cord injury. In the present study, we demonstrated that protein oxidation increases in rat spinal cord tissue after experimental injury. As early as h after injury, the level of protein carbonyls at the injury epicenter was significantly higher than in control (169%, p < 0.05) and increased gradually over the next 4 weeks to 1260% of control level. Both caudal and rostral parts of the injured spinal cord demonstrated a mild increase of protein carbonyls by 4 weeks postinjury (135-138%, p < 0.05). Immunocytochemical analysis of protein carbonyls in the spinal cord cross-sections showed increased protein carbonyl immunoreactivity in the epicenter section compared to rostral and caudal sections of the same animal or control laminectomy animals. Increased protein carbonyl formation in damaged spinal cord tissue was associated with changes in activity and expression of an oxidative sensitive enzyme, creatine kinase BB, which plays an important role in the maintenance of ATP level in the CNS tissue. Damage to CK function in the CNS may severely aggravate the impairment of energy metabolism. The results of our study indicate that events associated with oxidative damage are triggered immediately after spinal cord trauma but continue to occur over the subsequent 4 weeks. These results suggest that antioxidant therapeutic strategies may be beneficial to lessen the consequences of the injury and potentially improve the restoration of neurological function.     

Effect of oxidative stress on glial cell volume

Cytotoxic brain edema is a major contributor of tissue damage following cerebral ischemia and traumatic brain injury. The pathophysiology of cytotoxic edema formation is still not well understood. Although it is widely believed that oxidative stress causes cytotoxic brain edema, experimental proof is lacking. The aim of the present study was therefore to examine the effect of oxidative stress on cell volume of glial cells. C6 glial cells were exposed to hydrogen peroxide and the superoxide forming complex hypoxanthine/xanthine oxidase (HX/XO). Exposure to hydrogen peroxide (0.5-5 mM) resulted in initial cell shrinkage by 5.7 +/- 1.5% (mean +/- SEM; p < 0.05) and was followed by a dose-dependent recovery to baseline. Exposure to superoxide anions generated by HX/XO provoked a delayed, but sustained decrease of cell volume by 11.8 +/- 0.9% (p < 0.05). Cell volume showed no tendency to recover upon sustained exposure to superoxide. Neither hydrogen peroxide nor HX/XO exposure was associated with a decrease of cell viability. Thereby, the present study demonstrates that oxidative stress by hydrogen peroxide and superoxide anions does not induce cytotoxic cell swelling and suggests that free radicals are not directly involved in the formation of cytotoxic brain edema.     

Ischemic preconditioning: a defense mechanism against the reactive oxygen species generated after hepatic ischemia reperfusion

BACKGROUND: Preconditioning protects against both liver and lung damage after hepatic ischemia-reperfusion (I/R). Xanthine and xanthine oxidase (XOD) may contribute to the development of hepatic I/R. OBJECTIVE: To evaluate whether preconditioning could modulate the injurious effects of xanthine/XOD on the liver and lung after hepatic I/R. METHODS: Hepatic I/R or preconditioning previous to I/R was induced in rats. Xanthine and xanthine dehydrogenase/xanthine oxidase (XDH/XOD) in liver and plasma were measured. Hepatic injury and inflammatory response in the lung was evaluated. RESULTS: Preconditioning reduced xanthine accumulation and conversion of XDH to XOD in liver during sustained ischemia. This could reduce the generation of reactive oxygen species (ROS) from XOD, and therefore, attenuate hepatic I/R injury. Inhibition of XOD prevented postischemic ROS generation and hepatic injury. Administration of xanthine and XOD to preconditioned rats led to hepatic MDA and transaminase levels similar to those found after hepatic I/R. Preconditioning, resulting in low circulating levels of xanthine and XOD activity, reduced neutrophil accumulation, oxidative stress, and microvascular disorders seen in lung after hepatic I/R. Inhibition of XOD attenuated the inflammatory damage in lung after hepatic I/R. Administration of xanthine and XOD abolished the benefits of preconditioning on lung damage. CONCLUSIONS: Preconditioning, by blocking the xanthine/XOD pathway for ROS generation, would confer protection against the liver and lung injuries induced by hepatic I/R.     

Hyperbaric oxygen treatment in the experimental spinal cord injury model

Background contextSpinal cord trauma is a major cause of mortality and morbidity. Although no known treatment for spinal cord injury exists, a limited number of effective treatment modalities and procedures are available that improve secondary injury. Hyperbaric oxygen (HBO) treatment has been used to assist in neurologic recovery after cranial injury or ischemic stroke.PurposeTo report the findings on the effectiveness of HBO treatment on rats with experimental traumatic spinal cord injury. Improvement was evaluated through motor strength assessment and nitrite level assay testing.Study designWe randomly distributed 40 rats among 5 groups of 8 rats each: sham incurable trauma, induced trauma, HBO treatment begun at the 1st hour, HBO treatment begun at the 6th hour, and HBO treatment begun at the 24th hour.MethodThe HBO treatment was administered to rats in three of the groups and conducted in two 90-minute sessions, under an absolute atmospheric pressure of 2.4 at 100% oxygen for 5 days. In the motor strength evaluations, all the rats were observed during the inclined plane test and clinical motor examination on the first, third, and fifth days. In addition, the nitrite levels of spinal cord tissues on the sixth day were also studied.ResultsResults from the inclined plane levels and motor strength test from all the three groups undergoing HBO treatment were higher than those from Group 2. It was also determined that early HBO treatment resulted in higher recovery rates (groups 3 and 4). The highest levels were seen in the group in which the HBO treatments were started in the first hour (Group 3). It was noted that nitrite levels of rats in the group exposed to trauma increased, compared with the sham group, but increased levels also diminished after HBO treatments. Again, the greatest decrease in nitrite levels was evident in the group where the HBO treatment was started the earliest (Group 3).ConclusionsPrompt HBO treatment after trauma significantly contributed to the clinical, histopathologic, and biochemical recovery of the rats.     

Effect of oxygen free radicals on the rat pancreas in vivo]

Many reports concerning the involvement of active oxygen free radicals in the pathogenesis and progression of acute pancreatitis have been published. In this study, the direct toxic effect of active oxygen free radicals on the rat pancreas was evaluated in vivo. Superoxide anions, generated via the xanthine/xanthine oxidase (X/XO) system, and hydrogen peroxide (H2O2) were used. After continuous arterial injection of X/XO into the celiac artery hemorrhage and extensive edema developed. However, additional continuous injection of superoxide dismutase (SOD) into the external jugular vein completely suppressed the hemorrhage and relieved the edema. When hydrogen peroxide (100 microM/Kg/hour) was injected continuously through the celiac artery made hemorrhage and edema were recognized in the pancreas, both of which were suppressed by continuous injection of catalase (10 mg/Kg/hour) or gabexate mesilate (10 mg/Kg/hour) into the external jugular vein. The amylase and lipase levels in the intraperitoneal fluid rose to more than 10 times the preoperative values 5 hours after drug administration. These levels were lowered to 2 times the preoperative values by the continuous venous injection of SOD or catalase (which are specific scavengers of superoxide anions or hydrogen peroxide, respectively) or by gabexate mesilate. On the other hand, serum amylase and lipase levels remained almost constant throughout the entire experiment. Thus, the administration of active oxygen free radicals caused acute pancreatitis, which was suppressed by the systemic administration of specific scavengers for each free radical. Active oxygen free radicals were shown to have a direct, toxic effect on the pancreas.     

Oxygenated fluorocarbon nutrient solution in the treatment of experimental spinal cord injury

We employed an extravascular perfusion system through the subarachnoid space of the traumatized spinal cord of the cat for the delivery of oxygen utilizing a fluorocarbon emulsion containing essential nutrients, termed the oxygenated fluorocarbon nutrient solution (OFNS). Animals perfused for 2 hours with saline after impact injury of the spinal cord had significantly less edema at 1 cm below this site of injury than injured, untreated animals. However, in injured animals perfused with OFNS there was significant protection from spinal cord edema at both 1 and 2 cm below the site of injury. OFNS perfusion reduced the magnitude of hemorrhagic necrosis in both the gray and the white matter and protected the anterior horn cells against lysis at the site of injury. Adenosine triphosphate (ATP) is decreased within 1 minute and remains suppressed for 1 hour in gray and white matter of unperfused, injured animals. The level of ATP in both gray and white matter was significantly higher in injured OFNS-perfused animals than in saline-treated animals at the site below the spinal cord injury. Our data show that OFNS perfusion of the injured spinal cord reduced necrosis and edema and tended to normalize the levels of high energy ATP and intact anterior horn cells. These results demonstrate the feasibility of treating ischemic hypoxia of the spinal cord after trauma through an extravascular perfusion route that utilizes a fluorocarbon emulsion as a vehicle for the delivery of oxygen and other cellular nutrients.     

Potent protective effects of melatonin on experimental spinal cord injury

STUDY DESIGN: Experimental biochemical, behavioral, and histologic investigations of spinal cord injury in rats. OBJECTIVE: To investigate the effects of melatonin, a pineal hormone, in compression ischemic-induced spinal cord injury. SUMMARY OF BACKGROUND DATA: The implication of activated neutrophils in the worsening of spinal cord injury has been shown. Melatonin was shown to play an important role in protecting animal cells from neutrophil-induced toxicity and damage by free radicals. There is no report on using melatonin for spinal cord injury. METHODS: Spinal cord injury was induced by placing 25 g of weight extradurally on the rat spinal cord at T12 for 20 minutes. The rats were randomly divided into three groups. Sham rats had only laminectomy. Melatonin rats were injected with melatonin (2.5 mg/kg) intraperitoneally (intraperitoneal) five times: at 5 minutes, then 1, 2, 3, and 4 hours after the injury. Correspondingly, the control rats were injected with saline. Measured levels of lipid peroxidation estimated thiobarbituric acid reactive substances (TBARS) and the accumulation of leukocytes at the site of trauma, which were evaluated by measuring tissue myeloperoxidase activity. The recovery was assessed by using three clinical scoring systems, and histologic changes of the damaged spinal cord were examined. RESULTS: The thiobarbituric acid reactive substances content in the spinal cord increased after the injury, with two peaks (at 1 and 4 hours), and nitrogen mustard-induced leukocytopenia significantly attenuated the thiobarbituric acid reactive substances content in four 4 after injury. Also in these 4 hours, myeloperoxidase activity increased and melatonin injection reduced thiobarbituric acid reactive substances content and myeloperoxidase activity, which attenuated the motor deficits as well. Histologic findings showed that the melatonin group had less cavity formation than the control group. CONCLUSION: Results showed that injection of melatonin reduced thiobarbituric acid reactive substances content and myeloperoxidase activity, facilitating recovery of the damaged spinal cord.     

Acute phase effects of ATP-MgCl<Subscript>2</Subscript> on experimental spinal cord injury

The purpose of this study was to study the acute phase effects of adenosine triphosphate (ATP)-MgCl₂ on experimental spinal cord clip compression injury. Spinal cord clip compression injury was performed on 36 albino Wistar rats. The rats were divided into five groups. T4–T8 total laminectomy was performed on all rats. Group 1: sham-operated group. Group 2: clip compression group. In group 3, ATP-MgCl₂ (100 μmol/kg) was given 2 min before the "clip compression injury." In group 4, ATP-MgCl₂ (100 μmol/kg) was given 5 min after the clip compression injury. In group 5, ATP MgC1₂ (100 μmol/kg) was administered 8 h after the injury. The spinal cords were excised for a length of 2 cm and deep frozen at –76°C. Tissue malondialdehyde (MDA) levels were used to determine the effects of ATP-MgCl₂ on spinal cord lipid peroxidation. In the groups in which ATP MgCl₂ was administered after the clip compression injury (groups 4 and 5), the decrease in spinal cord MDA levels was statistically significant when compared with those of the injury group (group 2). Although MDA levels of group 4 were lower than those of group 5, this difference was not statistically significant. Administration of the ATP-MgCl₂ before the clip compression injury (in group 3) did not have a statistically significant effect on lipid peroxidation when compared with the injury group (group 2). In this study, we found that ATP-MgCl₂ has decreased lipid peroxidation in spinal cord injury and protected the spinal cord from secondary injury after the trauma. We concluded that ATP-MgCl₂ may be used in the treatment of spinal cord injuries in conjunction with the other treatment modalities, but further investigations are mandatory. Electronic Publication     

An experimental study on preventive effect of vitamin E in spinal cord injury

The effects of vitamin E on compression injury of the spinal cord associated with ischemia were studied in rats. Growing rats were divided into two groups and given diet containing 2 IU/100 g (group C) or 50 IU/100 g (group E) of alpha-tocopherol acetate from 8-10 weeks before experiments. The motor disturbance induced by spinal cord injury was greatly reduced by vitamin E-supplementation. After injury, the value of TBA-reactive substances (TBARS) was immediately increased and the level of alpha-tocopherol was correspondingly decreased in the spinal cord. A higher level of TBARS was observed in the proximal region than in the injured region of the spinal cord. The high level persisted for 24 hrs in group C, but decreased within 1 hr in group E. Pathological examination of the spinal cord revealed less damage, such as bleeding and edema, in group E than in group C.     

Xanthine oxidase: its role in the no-reflow phenomenon.

This study was designed to probe the hypothesis that oxygen-derived free radicals are involved in initiation of the no-reflow phenomenon. We developed a reproducible model of no reflow in the rat hind limb. Laser Doppler studies confirmed that the hind limbs perfused well after 2 or 4 hours of ischemia, but perfusion ceased in the first 10 minutes after 6 hours of ischemia. Venous blood samples and biopsy specimens of skin and muscle were taken after 2 and 4 hours of ischemia to study tissue injury. Blood samples were evaluated for xanthine oxidase (XO), xanthine dehydrogenase, and creatine phosphokinase (CPK) activities. Conjugated dienes and iodine 125-labeled albumin extravasation were quantified in tissue samples. Groups of animals were treated with inhibitors of XO (allopurinol), antioxidant enzymes (superoxide dismutase plus catalase), and free radical scavengers (dimethyl sulfoxide and dimethyl thiourea) to assess the roles of free radicals in ischemia-reperfusion injury in the hind limbs. After 4 hours of ischemia followed by reperfusion, plasma XO activity rose threefold over preischemia levels (p less than 0.05). Xanthine dehydrogenase activity did not change; conjugated diene levels in muscle rose twofold; CPK levels rose sixfold, and 125I albumin extravasation rose twofold (p less than 0.05). Pretreatment with the XO inhibitor allopurinol reduced XO activity to negligible levels and significantly attenuated conjugated diene levels, CPK levels, and albumin extravasation. Albumin extravasation was also significantly attenuated by pretreating animals with superoxide dismutase together with catalase, dimethyl thiourea, and dimethyl sulfoxide. In all animals pretreated with allopurinol or superoxide dismutase and catalase, reperfusion persisted after 6 hours of ischemia. These data suggest that, in ischemia followed by reperfusion, tissue injury is related to oxygen products derived from XO activity.