Biomedical subjects

S H Graham

Publications and source records attributed to S H Graham.

At least 19 recordsLinked to original sources

PubMed2001

Caspase-activated DNase/DNA fragmentation factor 40 mediates apoptotic DNA fragmentation in transient cerebral ischemia and in neuronal cultures.

Nuclear changes, including internucleosomal DNA fragmentation, are characteristic features of neuronal apoptosis resulting from transient cerebral ischemia and related brain insults for which the molecular mechanism has not been elucidated. Recent studies suggest that a caspase-3-mediated mechanism may be involved in the process of nuclear degradation in ischemic neurons. In this study, we cloned from rat brain a homolog cDNA encoding caspase-activated deoxyribonuclease (CAD)/DNA fragmentation factor 40 (DFF40), a 40 kDa nuclear enzyme that is activated by caspase-3 and promotes apoptotic DNA degradation. Subsequently, we investigated the role of CAD/DFF40 in the induction of internucleosomal DNA fragmentation in the hippocampus in a rat model of transient global ischemia and in primary neuronal cultures under ischemia-like conditions. At 8-72 hr after ischemia, CAD/DFF40 mRNA and protein were induced in the degenerating hippocampal CA1 neurons. CAD/DFF40 formed a heterodimeric complex in the nucleus with its natural inhibitor CAD (ICAD) and was activated after ischemia in a delayed manner (>24 hr) by caspase-3, which translocated into the nucleus and cleaved ICAD. Furthermore, an induced CAD/DFF40 activity was detected in nuclear extracts in both in vivo and in vitro models, and the DNA degradation activity of CAD/DFF40 was inhibited by purified ICAD protein. These results strongly suggest that CAD/DFF40 is the endogenous endonuclease that mediates caspase-3-dependent internucleosomal DNA degradation and related nuclear alterations in ischemic neurons.

Animals↗

PubMed2001

Bax kappa, a novel Bax splice variant from ischemic rat brain lacking an ART domain, promotes neuronal cell death.

Bax is a pro-apoptotic Bcl-2 family protein that regulates programmed cell death through homodimerization and through heterodimerization with Bcl-2. Bax alpha is encoded by six exons and undergoes alternative splicing. Bax kappa, a splice variant of Bax with conserved BH1, BH2 and BH3 binding domains and a C-terminal transmembrane domain (TM), but with an extra 446-bp insert between exons 1 and 2 leading to loss of an N-terminal ART domain, was identified from an ischemic rat brain cDNA library. Expression of Bax kappa mRNA and protein was up-regulated in hippocampus after cerebral ischemic injury. The increased Bax kappa mRNA was distributed mainly in selectively vulnerable hippocampal CA1 neurons that are destined to die after global ischemia. Overexpression of Bax kappa protein in HN33 mouse hippocampal neuronal cells induced cell death, which was partially abrogated by co-overexpression of Bcl-2. Moreover, co-overexpression of Bax kappa and Bax alpha increased HN33 cell death. The results suggest that the Bax kappa may have a role in ischemic neuronal death.

Alternative Splicing↗

PubMed2001

Excitatory amino acid concentrations in ventricular cerebrospinal fluid after severe traumatic brain injury in infants and children: the role of child abuse.

BACKGROUND: Excitotoxicity is an important mechanism in secondary neuronal injury after traumatic brain injury (TBI). Excitatory amino acids (EAAs) are increased in cerebrospinal fluid (CSF) in adults after TBI; however, studies in pediatric head trauma are lacking. We hypothesized that CSF glutamate, aspartate, and glycine would be increased after TBI in children and that these increases would be associated with age, child abuse, poor outcome, and cerebral ischemia. METHODS: EAAs were measured in 66 CSF samples from 18 children after severe TBI. Control samples were obtained from 19 children who received lumbar punctures to rule out meningitis. RESULTS: Peak and mean CSF glycine and peak CSF glutamate levels were increased versus control values. Subgroups of patients with TBI were compared by using univariate regression analysis. Massive increases in CSF glutamate were found in children <4 years old and in child abuse victims. Increased CSF glutamate and glycine were associated with poor outcome. A trend toward an association between high glutamate concentration and ischemic blood flow was observed. CONCLUSIONS: CSF EAAs are increased in infants and children with severe TBI. Young age and child abuse were associated with extremely high CSF glutamate concentrations after TBI. A possible role for excitotoxicity after pediatric TBI is supported.

Adolescent↗

PubMed2001

Detection of single- and double-strand DNA breaks after traumatic brain injury in rats: comparison of in situ labeling techniques using DNA polymerase I, the Klenow fragment of DNA polymerase I, and terminal deoxynucleotidyl transferase.

DNA damage is a common sequela of traumatic brain injury (TBI). Available techniques for the in situ identification of DNA damage include DNA polymerase I-mediated biotin-dATP nick-translation (PANT), the Klenow fragment of DNA polymerase I-mediated biotin-dATP nick-end labeling (Klenow), and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL). While TUNEL has been widely utilized to detect primarily double-strand DNA breaks, the use of PANT to detect primarily single-strand DNA breaks and Klenow to detect both single- and double-strand DNA breaks has not been reported after TBI. Accordingly, coronal brain sections from naive rats and rats at 0, 0.5, 1, 2, 6, 24, and 72 h (n = 3-5/group) after controlled cortical impact with imposed secondary insult were processed using the PANT, Klenow, and TUNEL methods. Cells with DNA breaks were detected by PANT in the ipsilateral hemisphere as early as 0.5 h after injury and were maximal at 6 h (cortex = 66.3+/-15.8, dentate gyrus 58.6+/-12.8, CA1 = 15.8+/-5.9, CA3 = 12.8+/-4.2 cells/x 400 field, mean +/- SEM, all p < 0.05 versus naive). Cells with DNA breaks were detected by Klenow as early as 30 min and were maximal at 24 h (cortex = 56.3+/-14.3, dentate gyrus 78.0+/-16.7, CA1 = 25.8+/-4.7, CA3 = 29.3+/-15.1 cells/x 400 field, all p < 0.05 versus naive). Cells with DNA breaks were not detected by TUNEL until 2 h and were maximal at 24 h (cortex = 47.7+/-21.4, dentate gyrus 63.0+/-11.9, CA1 = 5.6+/-5.4, CA3 = 6.9+/-3.7 cells/x 400 field, cortex and dentate gyrus p < 0.05 versus naive). Dual-label immunofluorescence revealed that PANT-positive cells were predominately neurons. These data demonstrate that TBI results in extensive DNA damage, which includes both single- and double-strand breaks in injured cortex and hippocampus. The presence of multiple types of DNA breaks implicate several pathways in the evolution of DNA damage after TBI.

Animals↗

PubMed2001

Increased adenosine in cerebrospinal fluid after severe traumatic brain injury in infants and children: association with severity of injury and excitotoxicity.

OBJECTIVES: To measure adenosine concentration in the cerebrospinal fluid of infants and children after severe traumatic brain injury and to evaluate the contribution of patient age, Glasgow Coma Scale score, mechanism of injury, Glasgow Outcome Score, and time after injury to cerebrospinal fluid adenosine concentrations. To evaluate the relationship between cerebrospinal fluid adenosine and glutamate concentrations in this population. DESIGN: Prospective survey. SETTING: Pediatric intensive care unit in a university-based children's hospital. PATIENTS: Twenty-seven critically ill infants and children who had severe traumatic brain injury (Glasgow Coma Scale < 8), who required placement of an intraventricular catheter and drainage of cerebrospinal fluid as part of their neurointensive care. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Patients ranged in age from 2 months to 14 yrs. Cerebrospinal fluid samples (n = 304) were collected from 27 patients during the first 7 days after traumatic brain injury. Control cerebrospinal fluid samples were obtained from lumbar puncture on 21 infants and children without traumatic brain injury or meningitis. Adenosine concentration was measured by using high-pressure liquid chromatography. Adenosine concentration was increased markedly in cerebrospinal fluid of children after traumatic brain injury vs. controls (p < .001). The increase in cerebrospinal fluid adenosine was independently associated with Glasgow Coma Scale < or = 4 vs. > 4 and time after injury (both p < .005). Cerebrospinal fluid adenosine concentration was not independently associated with either age (< or = 4 vs. > 4 yrs), mechanism of injury (abuse vs. other), or Glasgow Outcome Score (good/moderately disabled vs. severely disabled, vegetative, or dead). Of the 27 patients studied, 18 had cerebrospinal fluid glutamate concentration previously quantified by high-pressure liquid chromatography. There was a strong association between increases in cerebrospinal fluid adenosine and glutamate concentrations (p < .005) after injury. CONCLUSIONS: Cerebrospinal fluid adenosine concentration is increased in a time- and severity-dependent manner in infants and children after severe head injury. The association between cerebrospinal fluid adenosine and glutamate concentrations may reflect an endogenous attempt at neuroprotection against excitotoxicity after severe traumatic brain injury.

Adenosine↗

PubMed2001

Programmed cell death in cerebral ischemia.

Programmed cell death (PCD) is an ordered and tightly controlled set of changes in gene expression and protein activity that results in neuronal cell death during brain development. This article reviews the molecular pathways by which PCD is executed in mammalian cells and the potential relation of these pathways to pathologic neuronal cell death. Whereas the classical patterns of apoptotic morphologic change often do not appear in the brain after ischemia, there is emerging biochemical and pharmacologic evidence suggesting a role for PCD in ischemic brain injury. The most convincing evidence for the induction of PCD after ischemia includes the altered expression and activity in the ischemic brain of deduced key death-regulatory genes. Furthermore, studies have shown that alterations in the activity of these gene products by peptide inhibitors, viral vector-mediated gene transfer, antisense oligonucleotides, or transgenic mouse techniques determine, at least in part, whether ischemic neurons live or die after stroke. These studies provide strong support for the hypothesis that PCD contributes to neuronal cell death caused by ischemic injury. However, many questions remain regarding the precise pathways that initiate, sense, and transmit cell death signals in ischemic neurons and the molecular mechanisms by which neuronal cell death is executed at different stages of ischemic injury. Elucidation of these pathways and mechanisms may lead to the development of novel therapeutic strategies for brain injury after stroke and related neurologic disorders.

Animals↗

PubMed2001

bcl-2 Antisense treatment prevents induction of tolerance to focal ischemia in the rat brain.

In the rat, 60 minutes of transient ischemia to the middle cerebral artery results in infarction of the caudate putamen. Ischemic preconditioning with 20 minutes of transient focal ischemia produced tolerance (attenuated infarction volume) to 60 minutes of subsequent focal ischemia administered three days, five days, or seven days later. Western blots from tolerant caudate putamen demonstrated increased bcl-2 expression, maximum at 3 days and persisting through 7 days. Immunocytochemical examination found that bcl-2 was expressed in cells with both neuronal and nonneuronal morphology in striatum after preconditioning ischemia. bcl-2 antisense oligodeoxynucleotides (ODNs), bcl-2 sense ODNs, or artificial cerebrospinal fluid (CSF, vehicle) was infused into the lateral ventricle for the 72 hours between the 20-minute ischemic preconditioning and the 60-minute period of ischemia. Antisense ODN treatment reduced expression of bcl-2 in the striatum and blocked the induction of tolerance by preconditioning ischemia. Sense and CSF treatments had no effect on either bcl-2 expression or tolerance. In this model of induced tolerance to focal ischemia, bcl-2 appears to be a major determinant.

Animals↗

PubMed2001

Intracellular Bax translocation after transient cerebral ischemia: implications for a role of the mitochondrial apoptotic signaling pathway in ischemic neuronal death.

Activation of terminal caspases such as caspase-3 plays an important role in the execution of neuronal cell death after transient cerebral ischemia. Although the precise mechanism by which terminal caspases are activated in ischemic neurons remains elusive, recent studies have postulated that the mitochondrial cell death-signaling pathway may participate in this process. The bcl-2 family member protein Bax is a potent proapoptotic molecule that, on translocation from cytosol to mitochondria, triggers the activation of terminal caspases by increasing mitochondrial membrane permeability and resulting in the release of apoptosis-promoting factors, including cytochrome c. In the present study, the role of intracellular Bax translocation in ischemic brain injury was investigated in a rat model of transient focal ischemia (30 minutes) and reperfusion (1 to 72 hours). Immunochemical studies revealed that transient ischemia induced a rapid translocation of Bax from cytosol to mitochondria in caudate neurons, with a temporal profile and regional distribution coinciding with the mitochondrial release of cytochrome c and caspase-9. Further, in postischemic caudate putamen in vivo and in isolated brain mitochondria in vitro, the authors found enhanced heterodimerization between Bax and the mitochondrial membrane permeabilization-related proteins adenine nucleotide translocator (ANT) and voltage-dependent anion channel. The ANT inhibitor bongkrekic acid prevented Bax and ANT interactions and inhibited Bax-triggered caspase-9 release from isolated brain mitochondria in vitro. Bongkrekic acid also offered significant neuroprotection against ischemia-induced caspase-3 and caspase-9 activation and cell death in the brain. These results strongly suggest that the Bax-mediated mitochondrial apoptotic signaling pathway may play an important role in ischemic neuronal injury.

Animals↗

PubMed2001

Fas (CD95) may mediate delayed cell death in hippocampal CA1 sector after global cerebral ischemia.

Cell death-regulatory genes like caspases and bcl-2 family genes are involved in delayed cell death in the CA1 sector of hippocampus after global cerebral ischemia, but little is known about the mechanisms that trigger their expression. The authors found that expression of Fas and Fas-ligand messenger ribonucleic acid and protein was induced in vulnerable CA1 neurons at 24 and 72 hours after global ischemia. Fas-associating protein with a novel death domain (FADD) also was upregulated and immunoprecipitated and co-localized with Fas. Caspase-10 was activated and interacted with FADD protein to an increasing extent as the duration of ischemia increased. Moreover, caspase-10 co-localized with both FADD and caspase-3. These findings suggest that Fas-mediated death signaling may play an important role in signaling hippocampal neuronal death in CA1 after global cerebral ischemia.

Adaptor Proteins, Signal Transducing↗

PubMed2001

Altered expression of the neuropeptide-processing enzyme carboxypeptidase E in the rat brain after global ischemia.

Carboxypeptidase E, an exoprotease involved in the processing of bioactive peptides released by a regulated secretory pathway, was identified in a subtractive complementary DNA library derived from an ischemic rat brain by differential screening. In situ hybridization and immunocytochemical analysis showed the presence of carboxypeptidase E messenger RNA and protein in the cerebral cortex, thalamus, striatum, and hippocampus of a healthy rat brain. After 15 minutes of transient global ischemia followed by 8 hours of reperfusion, increased levels of carboxypeptidase E messenger RNA and protein were observed in the hippocampal CA1 and CA3 regions and in the cortex, as detected by Northern and Western blot analyses and in situ hybridization. After extended reperfusion (24 to 72 hours), both carboxypeptidase E messenger RNA and protein levels were decreased. The ischemia-induced changes in carboxypeptidase E expression suggest that this enzyme may play a role in modulating the brain's response to ischemia.

Animals↗

PubMed2000

10 kD mitochondrial matrix heat shock protein mRNA is induced following global brain ischemia in the rat.

Heat shock proteins (HSP's) are a family of highly conserved proteins whose expression is increased by stress. The expression of many HSP's is induced in neurons by ischemia; however, the response of the 10 kDa mitochondrial matrix HSP (HSP10) is less well characterized. To address this issue, asphyxial cardiac arrest was induced in 28 male Sprague-Dawley rats. Northern blot analysis revealed that hsp10 mRNA was increased 2.7-fold in asphyxiated rats compared to sham-operated controls. In situ hybridization demonstrated increased mRNA in the cortex, septal nuclei, hippocampus, thalamic nuclei, purkinje cell layer of the cerebellum, and isolated brainstem nuclei of asphyxiated rats. The increase of mRNA was most robust 8 h after the injury but remained increased for 72 h. These results show that hsp10 mRNA is increased following asphyxial cardiac arrest in rats and suggest that hsp10 could be another determinate of neuronal survival after ischemia.

Animals↗

PubMed2000

Expression of the RNA-binding protein TIAR is increased in neurons after ischemic cerebral injury.

T-cell restricted intracellular antigen-related protein (TIAR) is an RNA recognition motif-type RNA-binding protein that has been implicated in the apoptotic death of T-lymphocytes and retinal pigment epithelial cells. Western blots prepared with a monoclonal antibody against TIAR showed expression in normal rat hippocampus, and induction by 15 min of global cerebral ischemia. This increased expression was evident at 8 hr after ischemia and maximal at 24 hr, whereas expression at 72 hr was reduced below basal levels. Expression of TIAR protein was also increased in parietal cortex 6 and 24 hr after 90 min of focal cerebral ischemia induced by middle cerebral artery (MCA) occlusion, as well as in cultured cortical neurons and astroglia after exposure to hypoxia in vitro. Immunocytochemistry showed that increased expression of TIAR occurred mainly in the CA1 sector of hippocampus 24 hr after global ischemia, and in cortical and striatal neurons 24 hr after 20 or 90 min of focal ischemia. Double-labeling studies showed that TIAR protein expression was co-localized with DNA damage in neuronal cells. The findings suggest that TIAR may be involved in neuronal cell death after cerebral ischemic injury.

Animals↗

PubMed2000

Assessment of 2-chloroadenosine treatment after experimental traumatic brain injury in the rat using arterial spin-labeled MRI: a preliminary report.

Adenosine is a putative endogenous neuroprotectant. Its action at A1 receptors mitigates excitotoxicity while action at A2 receptors increases cerebral blood flow (CBF). We hypothesized that cerebral injection of the adenosine analog, 2-chloroadenosine, would decrease swelling and increase CBF early after experimental traumatic brain injury (TBI). To test this hypothesis, rats were anesthetized and subjected to TBI using a controlled cortical impact (CCI) model (n = 5/group). Immediately after injury, 2-chloroadenosine (0.3 nmole in 2 microliters) or an equal volume of vehicle were stereotactically injected lateral to the area of contusion. Using magnetic resonance imaging (MRI), in vivo spin-lattice relaxation time of tissue water (Tlobs) and CBF (arterial spin labeling) were measured in a 2-mm thick slice in the injured and non-injured hemispheres at 3-4 h after CCI. In a separate, preliminary experiment, the effect of 2-chloroadenosine injection in normal rat brain was studied. Rats (n = 2) were anesthetized and a burr hole was made for injection of 2-chloroadenosine into the same site as in the TBI model. One rat received the standard dose of 0.3 nmole and one rat received a 6 nmole injection. Tlobs and CBF studies were obtained 1.5-3.5 h after injection, using the same MRI methods as in the TBI study. In rats subjected to TBI, treatment with 2-chloroadenosine attenuated the increase in Tlobs after injury (p < 0.05 for treatment vs vehicle) in both hippocampus and cortex ipsilateral to injury. However, treatment with 2-chloroadenosine did not improve post-traumatic hypoperfusion. In normal rats, injection of 0.3 nmole of 2-chloroadenosine did not increase CBF, but the higher dosage of 6 nmole dramatically increased hemispheric CBF by 1.5-2.0-fold. The effect of local injection of 2-chloroadenosine at a dose of 0.3 nmole after experimental TBI on Tlobs presumably represents a reduction in post-traumatic edema. This reduction in edema, along with the augmentation of CBF seen in normal rats at higher dosage (6 nmole), supports a role for adenosine in neuroprotection following TBI.

2-Chloroadenosine↗

PubMed2000

Increased expression of apoptosis-linked gene 2 (ALG2) in the rat brain after temporary focal cerebral ischemia.

Calcium is an important mediator of programmed cell death induced by transient cerebral ischemia, and calcium-binding proteins have been implicated in calcium-regulated signal transduction. Apoptosis-linked gene 2 is a calcium-binding protein required for cell death induced by different apoptotic stimuli. By Western blot analysis, we found that apoptosis-linked gene 2 protein was expressed in normal brains, and that expression increased in ischemic brains after 20 or 90 min of transient focal cerebral ischemia. Immunocytochemistry showed increased apoptosis-linked gene 2 protein expression in frontal cortex, a region where neurons underwent ischemic stress but still survived, after 20 or 90 min of focal cerebral ischemia. Apoptosis-linked gene 2 protein was also up-regulated in the ischemic border-zone of parietal cortex 24h after 20 min of focal ischemia, and was remarkably over-expressed in the caudate-putamen and parietal cortex, (where cells are destined to die) 24h after 90 min of ischemia. The expression pattern of apoptosis-linked gene 2 protein was similar to that of deoxyribonucleic acid damage detected by Klenow labeling assay. Our results suggest that apoptosis-linked gene 2 may be involved in the regulation of cell death after transient focal cerebral ischemia.

Animals↗

PubMed2000

Oxidative stress following traumatic brain injury in rats: quantitation of biomarkers and detection of free radical intermediates.

Oxidative stress may contribute to many pathophysiologic changes that occur after traumatic brain injury. In the current study, contemporary methods of detecting oxidative stress were used in a rodent model of traumatic brain injury. The level of the stable product derived from peroxidation of arachidonyl residues in phospholipids, 8-epi-prostaglandin F(2alpha), was increased at 6 and 24 h after traumatic brain injury. Furthermore, relative amounts of fluorescent end products of lipid peroxidation in brain extracts were increased at 6 and 24 h after trauma compared with sham-operated controls. The total antioxidant reserves of brain homogenates and water-soluble antioxidant reserves as well as tissue concentrations of ascorbate, GSH, and protein sulfhydryls were reduced after traumatic brain injury. A selective inhibitor of cyclooxygenase-2, SC 58125, prevented depletion of ascorbate and thiols, the two major water-soluble antioxidants in traumatized brain. Electron paramagnetic resonance (EPR) spectroscopy of rat cortex homogenates failed to detect any radical adducts with a spin trap, 5,5-dimethyl-1-pyrroline N:-oxide, but did detect ascorbate radical signals. The ascorbate radical EPR signals increased in brain homogenates derived from traumatized brain samples compared with sham-operated controls. These results along with detailed model experiments in vitro indicate that ascorbate is a major antioxidant in brain and that the EPR assay of ascorbate radicals may be used to monitor production of free radicals in brain tissue after traumatic brain injury.

Animals↗

PubMed2000

Caspase-3 mediated neuronal death after traumatic brain injury in rats.

During programmed cell death, activation of caspase-3 leads to proteolysis of DNA repair proteins, cytoskeletal proteins, and the inhibitor of caspase-activated deoxyribonuclease, culminating in morphologic changes and DNA damage defining apoptosis. The participation of caspase-3 activation in the evolution of neuronal death after traumatic brain injury in rats was examined. Cleavage of pro-caspase-3 in cytosolic cellular fractions and an increase in caspase-3-like enzyme activity were seen in injured brain versus control. Cleavage of the caspase-3 substrates DNA-dependent protein kinase and inhibitor of caspase-activated deoxyribonuclease and co-localization of cytosolic caspase-3 in neurons with evidence of DNA fragmentation were also identified. Intracerebral administration of the caspase-3 inhibitor N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethyl ketone (480 ng) after trauma reduced caspase-3-like activity and DNA fragmentation in injured brain versus vehicle at 24 h. Treatment with N-benzyloxycarbonyl-Asp-Glu-Val-Asp-fluoromethyl ketone for 72 h (480 ng/day) reduced contusion size and ipsilateral dorsal hippocampal tissue loss at 3 weeks but had no effect on functional outcome versus vehicle. These data demonstrate that caspase-3 activation contributes to brain tissue loss and downstream biochemical events that execute programmed cell death after traumatic brain injury. Caspase inhibition may prove efficacious in the treatment of certain types of brain injury where programmed cell death occurs.

Animals↗

PubMed2000

Increases in bcl-2 protein in cerebrospinal fluid and evidence for programmed cell death in infants and children after severe traumatic brain injury.

OBJECTIVES: To determine whether bcl-2, a protein that inhibits apoptosis, would be increased in cerebrospinal fluid (CSF) in infants and children after traumatic brain injury (TBI) and to examine the association of bcl-2 concentration with clinical variables. STUDY DESIGN: Bcl-2 was measured in CSF from 23 children (aged 2 months-16 years) with severe TBI and from 19 children without TBI or meningitis (control subjects) by enzyme-linked immunosorbent assay. CSF oligonucleosome concentration was also determined as a marker of DNA degradation. Brain samples from 2 patients undergoing emergent decompressive craniectomies were analyzed for bcl-2 with Western blot and for DNA fragmentation with TUNEL (terminal deoxynucleotidyl-transferase mediated biotin-dUTP nick-end labeling). RESULTS: CSF bcl-2 concentrations were increased in patients with TBI versus control subjects (P =.01). Bcl-2 was increased in patients with TBI who survived versus those who died (P =.02). CSF oligonucleosome concentration tended to be increased after TBI (P =.07) and was not associated with bcl-2. Brain tissue samples showed an increase in bcl-2 in patients with TBI versus adult brain bank control samples and evidence of DNA fragmentation within cells with apoptotic morphology. CONCLUSIONS: Bcl-2 may participate in the regulation of cell death after TBI in infants and children. The increase in bcl-2 seen in patients who survived is consistent with a protective role for this anti-apoptotic protein after TBI.

Adolescent↗

PubMed2000

Isoflurane improves long-term neurologic outcome versus fentanyl after traumatic brain injury in rats.

Despite routine use of fentanyl in patients after traumatic brain injury (TBI), it is unclear if it is the optimal sedative/analgesic agent. Isoflurane is commonly used in experimental TBI. We hypothesized that isoflurane would be neuroprotective versus fentanyl after TBI. Rats underwent controlled cortical impact (CCI) and received 4 h of N2O/O2 (2:1) and either fentanyl (10 microg/kg i.v. bolus, 50 microg/kg/h infusion) or isoflurane (1% by inhalation) with controlled ventilation. Shams underwent identical preparation, without CCI. Functional outcome (beam balance, beam walking, Morris water maze [MWM] tasks) was assessed over 20 days. Lesion volume and hippocampal neuron survival were quantified on day 21. Additional rats underwent identical CCI and anesthesia with intracranial pressure (ICP) monitoring, and brain water content was assessed. Motor and MWM performances were better in injured rats treated with isoflurane versus fentanyl (p < 0.05). CA1 hippocampal damage was attenuated in isoflurane-treated rats (p < 0.05). Fentanyl-treated rats had higher mean arterial blood pressure after injury (p < 0.05); however, ICP and brain water were similar between groups. Isoflurane improved functional outcome and attenuated damage to CA1 versus fentanyl in rats subjected to CCI. Isoflurane may be neuroprotective by augmenting cerebral blood flow and/or reducing excitotoxicity, not by reducing ICP or brain water content. Alternatively, fentanyl may be detrimental. Isoflurane may mask beneficial effects of novel agents tested in TBI models. Additionally, fentanyl may not be optimal early after TBI in humans.

Analgesics, Opioid↗