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Ann Thorac Surg 1997;64:1279-1285
© 1997 The Society of Thoracic Surgeons

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Original Articles: Cardiovascular

Neuronal Cell Death in the Ischemic Spinal Cord: The Effect of Methylprednisolone

Division of Cardiothoracic Surgery, Department of Surgery, and the Center for the Study of Nervous System Injury and Department of Neurology, Washington University School of Medicine, St. Louis, Missouri

	Abstract

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 
Background. Cell death occurs by either necrosis or apoptosis. The role of apoptosis in the neuronal degeneration after ischemia remains to be defined. We studied (1) the nature of neuronal death and (2) the neuroprotective action of methylprednisolone in a rat model of spinal cord ischemia.

Methods. Spinal cord ischemia was induced in adult Long-Evans rats by occluding the aortic arch for 14 minutes and simultaneously equilibrating the femoral artery pressure to the atmospheric pressure. Twenty rats were subjected to ischemia without treatment and another twenty to ischemia after treatment with methylprednisolone (30 mg/kg, 4 hours before ischemia). The animals were sacrificed and the lumbar spinal cords were examined on postoperative days 1 and 2.

Results. On day 1, neurons with morphology indicative of apoptosis were present in the gray matter. Their numbers increased from the ventral to the dorsal location. There were significantly fewer apoptotic neurons in the dorsal horn of the methylprednisolone-treated animals. DNA obtained from the spinal cord of untreated rats on days 1 and 2 showed laddering after electrophoresis, a feature of apoptosis. Pretreatment with methylprednisolone inhibited the development of DNA laddering. Methylprednisolone treatment was not associated with significantly improved neurologic function in the postoperative period.

Conclusions. Apoptotic neuronal death occurs in the rat spinal cord after transient ischemia and is attenuated by pretreatment with methylprednisolone.

	Introduction

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 
See also page 1286.

Paraplegia is a well recognized and not infrequent complication after operations on the descending thoracic and thoracoabdominal aorta. Histopathologic evidence of the associated spinal cord ischemic injury (SCII) has accumulated since the beginning of this century [1]. Injury to the gray matter of the spinal cord, with neuronal death, has generally been considered an important element in the pathology of SCII. The mechanism of ischemic cell death has traditionally been attributed to necrosis, a pathologic process that follows irreversible cell injury [2, 3].

A nonnecrotic and physiologic process of selective cellular death and elimination was first recognized as a component of normal embryonic development in the beginning of this century [4]. Kerr and colleagues [5] suggested in 1972 that a similar type of cell death, which they termed apoptosis, remains active throughout the life of the adult organism and contributes to the control of cell populations in the healthy tissues. They stated that apoptosis may also be triggered by noxious agents, after observations that this physiologic progress rather paradoxically appeared to be augmented and often occurred in association with necrosis after tissue injury both in vivo and in vitro. Apoptosis was initially characterized morphologically by cell shrinkage, nuclear condensation, and chromatin fragmentation [5]. It was later found that the pathogenesis of the chromatin destruction involves the activation of endonucleases resulting in cleavage of the DNA at linker regions between the nucleosomes [6]. Apoptosis has been shown in many cases to require de novo gene expression and protein synthesis by the cell as a step in the death process. For this reason, apoptosis has often been considered within the context of programmed cell death [4].

Recently, evidence has been presented that apoptosis may play a role in the death of cultured neurons after exposure to neurotoxins or to hypoxia [7]. Subsequent studies have provided further observations indicating that apoptosis may indeed occur in the brain [8–11] or the spinal cord [12] of adult animals after ischemia in vivo.

Methylprednisolone (MP), a glucocorticoid, is the only drug proven to be effective in improving neurologic function after traumatic spinal cord injury [13]. Although the beneficial effect of MP in reducing the incidence or the severity of SCII in humans remains unproven, the drug is administered to patients before cross-clamping of the aorta during operations on the descending thoracic and thoracoabdominal aorta [14]. Furthermore, the relative importance of the various plausible neuroprotective mechanisms of MP in the setting of central nervous system ischemia still remains obscure [15]. The objective of our study was to investigate the nature of neuronal cell death in the spinal cord of the rat after a period of aortic occlusion and to evaluate the effects of MP administration.

	Material and Methods

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 
Animal Care and Surgical Technique
Forty-four Long Evans outbred male rats, obtained from Harlan Sprague Dawley, Inc, were used in the study. They weighed between 300 and 330 g at the time of the operation. All animals were allowed free access to laboratory chow and tap water in day–night regulated quarters at 25°C. Animal care complied with the "Principles of Laboratory Animal Care" and the "Guide for the Care and Use of Laboratory Animals" (NIH Publication 85-23, revised 1985) and was approved by the Animal Studies Committee, Washington University School of Medicine (protocol number 96261). The rats were operated on in a room kept at 24°C. They were anesthetized in a chamber containing 3% halothane. The anesthetic state was maintained by inhalation through a facial mask of 1.25% to 1.5% halothane driven by oxygen at a flow rate of 2 L/min. The animals were placed in the supine position with the head and neck partially turned toward the right side. The tail artery was cannulated with a PE-50 catheter for monitoring the distal aortic blood pressure. An arteriotomy was made in the left common carotid artery and a second PE-50 catheter was introduced and advanced cephalad into the left internal carotid artery. This cannula was used for monitoring the distal left internal carotid artery back pressure. The temperature was continuously monitored with a flexible probe (T-probe, USE-YSI 400 series) inserted 3 cm into the rectum. During the surgical preparation, the temperature was maintained between 36.5°C and 37.5°C with an underbody thermal pad and a heat lamp. Heparin (100 U/kg) was administered intraarterially 5 minutes before aortic occlusion. Arterial blood gases (Arterial Blood Gases Analyzer; Nova Biomedical) and blood glucose (Accu-Chek Easy Blood Glucose Monitor; Boehringer Mannheim) were determined just before aortic occlusion. Through the left common carotid arteriotomy, a 2F Fogarty catheter was inserted and subsequently advanced into the descending thoracic aorta for approximately 8 cm. The catheter balloon was partially inflated with 0.03 mL of water and the catheter was gently withdrawn. When the balloon reached the origin of the common carotid artery, definite resistance to further catheter withdrawal was clearly felt by the operator. At this point, the full inflation of the balloon with up to 0.10 mL of water was achieved. The left femoral artery was partially incised transversely immediately after full inflation of the catheter balloon to equilibrate the arterial pressure to the atmospheric pressure. Blood was collected in a 10 mL syringe containing 25 U of heparin during the period of ischemia. The period of ischemia was 14 minutes, based on data from a series of preliminary studies. The recovered blood was administered to the animals during the later stages of the period of aortic occlusion through the internal carotid artery cannula to maintain the distal internal carotid artery pressure at approximately 50 mm Hg. The remaining blood was administered immediately after deflation of the balloon, resulting in recovery of both the distal aortic blood pressure and the distal internal carotid artery pressure to preocclusion levels within 2 minutes after the onset of reperfusion in all animals. At the end of the period of ischemia, the balloon was deflated and the catheter withdrawn.

The rats were divided into two groups. The control group (n = 20), received a single injection of 0.3 mL sterile water intraperitoneally, 4 hours before the time of aortic occlusion. The treatment group (n = 20), received 30 mg/kg methylprednisolone sodium succinate (Solu-Medrol, 30 mg/kg; Upjohn Co, Kalamazoo, MI) in a similar manner. Four additional animals underwent sham aortic occlusion without blood drainage. The animals were sacrificed at either 24 or 48 hours after reperfusion. Their neurologic status was assessed at 1, 6, 12, 24, and 48 hours. Crede's maneuver was used for evacuation of the urinary bladder when necessary.

Evaluation of Neurologic Status
Hindlimb motor function deficit was scored using the following system, which was a modification of the system reported by Marsala and Yaksh [16]. A motor deficit score was given to each rat at each assessment according to the following criteria:

• 0 = normal
  
• 1 = walks normally but legs are weak (cannot pull the legs if one holds them)
  
• 2 = assumes normal body posture on a flat surface and is able to walk but there is ataxia, with or without spasticity
  
• 3 = able to walk on the knuckles or walk on the feet but without proper stepping
  
• 4 = drags legs but there is movement at the knees
  
• 5 = drags legs without significant movement in the lower limbs and spasticity is present
  
• 6 = drags legs without significant movement in the lower limbs and flaccidity is present
  

Spasticity was defined as the continuous or intermittent tonic positioning of the hind limbs in extension and especially of the feet in plantar flexion. The degree of the spasticity ranged from mild (usually present intermittently after provocation by lifting the tail or by stressing the animal) to conspicuous (continuous, even at rest and characterized by the assumption of a striking posture with hind limbs in extreme extension and occasionally with tonic upwards curvature of the tail). Flaccidity was defined as the absence or great reduction of the muscle tone during passive movement at the ankle joints.

Light Microscopy
The animals used for histopathologic examination of the spinal cords under the light microscope were sacrificed at 24 hours after reperfusion. They were anesthetized with intraperitoneal injection of pentobarbital (150 mg/kg) and transcardially perfused with 0.9% saline solution for 1 minute followed by 400 mL 10% buffered formalin. The cadavers were kept at 4°C for 4 hours and then the lumbar enlargements of the spinal cords were harvested and postfixed in the same fixative overnight. The specimens were embedded into paraffin and transverse sections were obtained from a level corresponding to the middle of the fourth lumbar segment. Sections were stained with hematoxylin and eosin (H&E) and Nissl for light microscopy. Cells with eosinophilic cytoplasm and loss of cytoplasmic structure ("red neurons") in H&E-stained sections were considered to be necrotic [2]. Adjacent sections were used for staining of fragmented DNA using a TdT-mediated dUTP-biotin nick-end labeling (TUNEL) immunohistochemical method as described by Du and associates [10]. The ApopTag in situ apoptosis detection kit (Oncor, Gaithersburg, MD) was used for this purpose. Cells with nuclei well stained by the TUNEL method or containing apoptotic bodies were considered to be apoptotic. Some of the neurons that were considered to be necrotic in H&E-stained sections were stained with the TUNEL method, but in these cells the staining was very faint and there were no apoptotic bodies seen. Necrotic and apoptotic cells were counted in H&E- and ApopTag-stained sections, respectively, by a blinded observer, at the following gray matter areas: the head of the dorsal horns (Rexed's laminae 1 and 2), the body of the dorsal horns (lamina 5), the intermediate zone (lamina 7), and the area of the motoneurons in the anterior horns (lamina 9).

Analysis of DNA Fragmentation by Agarose Gel Electrophoresis
Twelve separate animals were anesthetized with 3% halothane in oxygen delivered through a facial mask at 24 and 48 hours of reperfusion. They were placed in the prone position and a laminectomy was performed from the mid-thoracic spine to the sacrum. The whole lower spinal cord was harvested and immediately placed in a -80°C freezer. The animals were euthanized with an overdose of pentobarbital. The Puregene DNA isolation kit (Gentra Systems, Minneapolis, MN) was used to extract DNA from the spinal cord specimens (lumbar segments 4 and 5). DNA electrophoresis was performed as described by Du and coworkers [10].

Statistical Analysis
Data are expressed as mean ± standard error of the mean. Differences in the physiologic parameters and in the neuronal numbers between groups were assessed by Student's t test with Dunn-Sidak adjustment as a protection for multiple testing. Single factor analysis of variance was used for the analysis of the difference between necrotic and apoptotic neuronal counts in the various gray matter areas within each of the two groups. The motor deficit scores were analyzed by Mann-Whitney U test. A p value of less than 0.05 was considered significant.

	Results

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 
Statistical analysis between the two groups for the various physiologic variables did not disclose differences, except for the pH in the MP group, which was significantly lower compared with the control group (Table 1). Fourteen minutes of ischemia resulted in severe motor deficit in the hind limbs of all animals in the control group, as assessed by the motor deficit score (Fig 1). Pretreatment with methylprednisolone did not prevent the development of paraplegia. In the follow-up period, there was mild recovery of the neurologic function of animals in both groups. The recovery was more pronounced in the MP group; however, the difference in mean motor deficit score between the two groups was not statistically significant at any time.

View larger version (21K): [in this window] [in a new window]   Fig 1. . Motor deficit score in the control and treatment group during the 48-hour follow-up period

View larger version (138K): [in this window] [in a new window]   Fig 2. . (A) Normal motor neuron in the anterior horn of the gray matter (arrow). The section was obtained from a rat that underwent sham ischemia. The nucleus contains loose chromatin and a prominent nucleolus. Nissl substance can be seen in the cytoplasm. (B) Necrotic neuron in the anterior horn (arrow). The section was obtained from a control animal 24 hours after reperfusion. The cytoplasm is eosinophilic and there is loss of cytoplasmic structure (red neuron). The nucleus is more pyknotic compared with the normal cell but the appearance of the chromatin is rather homogeneous. (Both, hematoxylin and eosin-stained sections, x400 before 3% reduction.)

View larger version (25K): [in this window] [in a new window]   Fig 3. . Distribution of the necrotic neurons in the gray matter of the lumbar spinal cord in control and methylprednisolone-treated animals 24 hours after reperfusion. The difference between the control and the methylprednisolone group is not statistically significant

View larger version (97K): [in this window] [in a new window]   Fig 4. . (A) Apoptotic neuron in the head of the dorsal horn (arrow). The cell is shrunken and apoptotic bodies can be seen. The section was obtained from a control animal 24 hours after reperfusion. Cells with very dense nuclei may also be seen (arrowheads) but their identity is less clear. (Hematoxylin and eosin-stained section, x400 before 3% reduction.) (B) Apoptotic neuron in the body of the dorsal horn (arrow). The section was obtained from a control animal 24 hours after reperfusion. Distinct apoptotic bodies may be seen. (TUNEL-stained section, x400 before 3% reduction.)

View larger version (25K): [in this window] [in a new window]   Fig 5. . Distribution of apoptotic neurons in the gray matter of the lumbar spinal cord in control and methylprednisolone-treated animals 24 hours after reperfusion. (*p < 0.05 compared with control.)

DNA extracted from the whole lower lumbar spinal cord from animals in the control group at 24 (n = 2) and 48 (n = 2) hours after reperfusion showed laddering after electrophoresis in agarose gel (Fig 6). This appearance is consistent with the presence of significant amounts of low-molecular weight DNA fragments with lengths that are multiples of 180 bp. DNA extracted from sham-operated animals (n = 2 at 24 hours and n = 2 at 48 hours) exhibited no laddering. DNA extracted in a similar way from the MP-treated animals at 24 (n = 2) and at 48 hours (n = 2) also did not show laddering.

View larger version (98K): [in this window] [in a new window]   Fig 6. . Gel electrophoresis of DNA extracted from animals that underwent sham ischemia (S), ischemia without treatment (I), and ischemia after methylprednisolone treatment (T) 24 and 48 hours after reperfusion. DNA marker positions in base pairs are shown at the left. (+) or (-) indicate the presence or absence of laddering, respectively

	Comment

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

The difference in the distribution of the neurons with necrotic and apoptotic characteristics in the ischemic spinal cord is of interest. Neuronal culture [19] and in vivo brain ischemia [10] studies have provided evidence supporting the contention that the severity of injury sustained by neurons may be a factor that could influence the type of the subsequent neuronal cell death. Transient occlusion of the thoracic aorta has been shown to produce regional differences in the severity of ischemia and patterns of reperfusion in the spinal cord in a rat model [20]. Neurons located in central areas of the gray matter, an area known to sustain a more severe ischemic injury [16], may die preferentially by severe membrane failure and necrosis. Neurons in the head and body of the dorsal horns, areas with better blood supply through collateral vessels, may be able to maintain a critical level of homeostasis despite the injury; some of these neurons may subsequently undergo apoptosis.

The lower concentration of apoptotic neurons in the ventral horn and the intermediate zone of the gray matter, as compared with necrotic ones, indicates that neuronal apoptosis may have a less important role compared with necrosis in the pathogenesis of paraplegia associated with severe SCII. Such a contention is reinforced by the absence of significant improvement in the hindlimb motor function despite the attenuation of apoptotic neuronal death in the MP-treated animals. However, the demonstration of a process that could lead to delayed neuronal cell death 24 to 48 hours after transient spinal cord ischemia raises the possibility that such a process may be contributory to the development of delayed onset paraplegia [14].

	Methylprednisolone as a Neuroprotective Agent Against Spinal Cord Ischemic Injury

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 
A single dose of methylprednisolone succinate 30 mg/kg given 4 hours before transient aortic occlusion prevented the appearance of laddering after electrophoresis of the spinal cord DNA at 24 and 48 hours after reperfusion. This finding indicates that there was reduced formation of double helix DNA fragments in the postischemic spinal cord of animals treated with MP. In addition, pretreatment with MP reduced the numbers of apoptotic neurons within the gray matter of the lumbar spinal cord. The molecular mechanism for attenuation of apoptotic neuronal death in the ischemic spinal cord by MP was not addressed in this study. Glucocorticoids exert most of their effects by binding to nuclear receptors and regulating gene expression [21]. Animal studies have documented that expression of immediate early genes occurs after ischemia of the central nervous system [17]. Evidence has recently been presented that postischemic gene expression may be involved in the biochemical cascade leading to apoptotic neuronal death after hypoxic or ischemic brain injury [17]. Methylprednisolone may have attenuated the apoptotic neuronal death in the spinal cord by altering the postischemic gene expression.

In addition, there are other effects of glucocorticoids, particularly when they are administered in high doses, that may be unrelated to the steroid hormone receptors [15]. A notable example of such an effect is the inhibition of lipid peroxidation, which has been considered the most likely neuroprotective mechanism of MP in the setting of spinal cord trauma [13, 15]. Oxygen-derived free radicals have been implicated in the pathogenesis of spinal cord neuronal injury after both trauma and ischemia–reperfusion [22, 23]. Recent experimental evidence has implicated oxidative stress as a causative factor in some types of apoptosis [24]. The antioxidant effect of high-dose MP may be responsible for the observed attenuation of apoptotic neuronal death in the ischemic spinal cord.

In the current study, MP was given as a single intraperitoneal dose 4 hours before the expected time of the aortic occlusion. We assumed that perioperative MP administration would result in better neuroprotection if the concentration of the drug within the central nervous system would be close to its peak at the time of aortic occlusion. In a study in the rat, MP was found to first bind to the brain capillaries and thereafter cross the blood–brain barrier slowly, probably using a cytoplasmic endothelial cell glucocorticoid receptor with saturable kinetics [25]. In a clinical study, intravenous administration of high-dose MP to patients with multiple sclerosis resulted in progressive increase of the drug concentration in the cerebrospinal fluid for at least 4 hours [26].

Pretreatment with MP failed to prevent the development of paraplegia after aortic occlusion in our experimental paradigm. Nevertheless, a mild attenuation of the hindlimb neurologic deficits was found on the second postoperative day. A different MP administration schedule might have resulted in different effects on neuronal necrosis and apoptosis or on the final behavioral outcome. In addition, because the present study examined the acute neuronal degeneration in SCII, all the animals were sacrificed within 2 days after reperfusion. Neurologic evaluation of animals for extended time periods is necessary to assess the full effect of MP on the recovery of motor function. Previous studies in animals [15] and humans [13, 15] have confirmed the neuroprotective efficacy of MP in traumatic spinal cord injury. The effect of MP in SCII is less clear. Methylprednisolone (30 mg/kg) administered intravenously during the 30 minutes before aortic occlusion did not alter the neurologic outcome at 48 hours after reperfusion in a rabbit model of SCII [27]. In contrast, administration of the same dose of MP intravenously 10 minutes before aortic occlusion and at 4 hours of reperfusion resulted in significantly improved neurologic outcome 7 days postoperatively in a dog model of SCII [28]. In the same study MP was demonstrated to have no effect on the spinal cord blood flow during the period of ischemia–reperfusion and its beneficial effect on neurologic outcome was attributed to protective effects on cellular and subcellular neural components. Comparisons between the results of various studies are difficult as a means to provide meaningful conclusions owing to the differences in species, experimental protocols, and outcome measures.

Results from the current study provide evidence that neuronal apoptosis as well as necrosis contributes to acute spinal cord degeneration after a period of transient aortic occlusion. They also support the contention that MP may be beneficial in SCII by inhibiting the apoptotic process in selected regions of the ischemic spinal cord. Further studies of MP and other agents directed at apoptosis may broaden our insight into the mechanisms of cell death in SCII. Combinations of drugs acting on the different pathophysiologic cascades that lead to ischemic cell death may further reduce the incidence and severity of neurologic complications in aortic surgery.

	Footnotes

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Presented at the Thirty-third Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Feb 3–5, 1997.

Address reprint requests to Dr Kouchoukos, 3009 North Ballas Rd, Suite 266, St. Louis, MO 63131.

	References

Top Footnotes Abstract Introduction Material and Methods Results Comment Methylprednisolone as a... References

 

1. Gomez L, Pike FH. The histological changes in nerve cells due to temporary anaemia of the central nervous system. J Exp Med 1909;11:257–65.[Abstract]
2. Garcia JH, Kamijyo Y. Cerebral infarction. Evolution of histopathological changes after occlusion of a middle cerebral artery in primates. J Neuropathol Exp Neurol 1974;33:408–21.[Medline]
3. Buja LM, Eigenbrodt ML, Eigenbrodt EH. Apoptosis and necrosis. Basic types and mechanisms of cell death. Arch Pathol Lab Med 1993;117:1208–14.[Medline]
4. Schwarch LM, Osborne BA. Programmed cell death, apoptosis and killer genes. Immunol Today 1993;14:582–90.[Medline]
5. Kerr JFR, Wyllie AH, Currie AR. Apoptosis: a basic biological phenomenon with wide-ranging implications in tissue kinetics. Br J Cancer 1972;26:239–57.[Medline]
6. Wyllie AH. Glucocorticoid-induced thymocyte apoptosis is associated with endogenous endonuclease activation. Nature 1980;284:555–6.[Medline]
7. Kure S, Tominaga T, Yoshimoto T, Tada K, Narisawa K. Glutamate triggers internucleosomal DNA cleavage in neuronal cells. Biochem Biophys Res Commun 1991;179:39–45.[Medline]
8. MacManus JP, Buchan AM, Hill IE, Rasquinha I, Preston E. Global ischemia can cause DNA fragmentation indicative of apoptosis in rat brain. Neurosci Lett 1993;164:89–92.[Medline]
9. Volpe BT, Wessel TC, Murherjee B, Federoff HJ. Temporal pattern of internucleosomal DNA fragmentation in the striatum and hippocampus after transient forebrain ischemia. Neurosci Lett 1995;186:157–60.[Medline]
10. Du C, Hu R, Csernansky CA, Hsu CY, Choi DW. Very delayed infarction after mild focal cerebral ischemia: a role for apoptosis? J Cereb Blood Flow Metab 1996;16:195–201.[Medline]
11. Li Y, Sharov VG, Jiang N, Zaloga C, Sabbah HN, Chopp M. Ultrastructural and light microscopic evidence of apoptosis after middle cerebral artery occlusion in the rat. Am J Pathol 1995;146:1045–51.[Abstract]
12. Kato H, Kanellopoulos GK, Mackey M, et al. Apoptosis and necrosis following spinal cord ischemia in the rat. Soc Neurosci Abstr 1996;22:1177.
13. Bracken MB, Shepard MJ, Collins WF, et al. A randomized, controlled trial of methylprednisolone or naloxone in the treatment of acute spinal-cord injury. N Engl J Med 1990;322:1405–11.[Abstract]
14. Marini CP, Cunningham JNJ. Issues surrounding spinal cord protection. Adv Card Surg 1993;4:89–107.[Medline]
15. Hall ED. The neuroprotective pharmacology of methylprednisolone. J Neurosurg 1992;76:13–22.[Medline]
16. Marsala M, Yaksh TY. Transient spinal ischemia in the rat: characterization of behavioural and histopathological consequences as a function of the duration of aortic occlusion. J Cereb Blood Flow Metab 1994;14:526–35.[Medline]
17. Johnson EMJ, Greenlund LJS, Akins PT, Hsu CY. Neuronal apoptosis: current understanding of molecular mechanisms and potential role in ischemic brain injury. J Neurotrauma 1995;12:843–52.[Medline]
18. Katoh K, Ikata T, Katoh S, et al. Induction and its spread of apoptosis in rat spinal cord after mechanical trauma. Neurosci Lett 1996;216:9–12.[Medline]
19. Bonfoco E, Krainc D, Ankarcrona M, Nicotera P, Lipton SA. Apoptosis and necrosis: two distinct events induced, respectively, by mild and intense insults with N-methyl-D-aspartate or nitric oxide/superoxide in cortical cell cultures. Proc Natl Acad Sci USA 1995;92:7162–6.[Abstract/Free Full Text]
20. Follis F, Miller K, Scremin OU, et al. Experimental delayed postischemic spinal cord hypoperfusion after aortic cross-clamping. Can J Neurol Sci 1995;22:202–7.[Medline]
21. Beato M. Gene regulation by steroid hormones. Cell 1989;56:335–44.[Medline]
22. Qayumi AK, Janusz MT, Jamieson WR, Lyster DM. Pharmacologic interventions for prevention of spinal cord injury caused by aortic crossclamping. J Thorac Cardiovasc Surg 1992;104:256–61.[Abstract]
23. Hall ED, Braughler JM. Free radicals in CNS injury. Res Publ Assoc Res Nerv Ment Dis 1993;71:81–105.[Medline]
24. Slater AFG, Nobel SI, Orrenius S. The role of intracellular oxidants in apoptosis. Biochim Biophys Acta 1995;1271:59–62.[Medline]
25. Chen TC, Mackic JB, McComb JG, Gianotta SL, Weiss MH, Zlokovic BV. Cellular uptake and transport of methylprednisolone at the blood-brain barrier. Neurosurgery 1996;38:348–354.[Medline]
26. Defer GL, Barre J, Ledudal P, Tillement JP, Degos JD. Methylprednisolone infusion during acute exacerbation of MS: plasma and CSF concentrations. Eur Neurol 1995;35:143–8.[Medline]
27. Cheng M, Robertson C, Grossman RG, Foltz R, Williams V. Neurological outcome correlated with spinal evoked potentials in a spinal cord ischemia model. J Neurosurg 1984;60:789–95.
28. Laschinger JC, Cunningham JN Jr, Cooper MM, Krieger K, Nathan IM, Spencer FC. Prevention of ischemic spinal cord injury following aortic cross-clamping: use of corticosteroids. Ann Thorac Surg 1984;38:500–7.[Abstract]

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