Blood group and protein polymorphism gene frequencies for seven breeds of horses in the United States

Gene frequencies at 20 blood group and protein polymorphism loci (A, C, D, K, P, Q, U, Al, Tf, Pi, Xk, Es, Gc, PGD, CA, Cat, PGM, AP, Hb and PHI) are given for seven horse breeds in the United States (Thoroughbred, Arabian, Standardbred, Morgan, Quarter Horse, Paso Fino and Peruvian Paso). These data are used to calculate that the battery of tests is at least 96% effective for recognizing incorrect paternity in these breeds. In addition to paternity testing, these tests can be applied to studies of breed relationships.

Excess of heterozygotes at albumin locus in American Standardbred horses

Data from 5934 matings of American Standardbred horses provided evidence for an excess of heterozygotes at the albumin locus, statistically significant (P less than 0.01) in one mating class (A1-AB stallions x Al-A dams), primarily attributed to an excess of heterozygotes among male offspring.

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.

The simple model versus the super model: translating experimental traumatic brain injury research to the bedside

Despite considerable investigation in rodent models of traumatic brain injury (TBI), no novel therapy has been successfully translated from bench to bedside. Although well-described limitations of clinical trails may account for these failures, several modeling factors may also contribute to the lack of therapeutic translation from the laboratory to the clinic. Specifically, models of TBI may omit one or more critical, clinically relevant pathophysiologic features. In this invited review article, the impact of the limited incorporation of several important clinical pathophysiologic factors in TBI, namely secondary insults (i.e., hypotension and/or hypoxemia), coma, and aspects of standard neurointensive care monitoring and management strategies (i.e., intracranial pressure [ICP] monitoring and ICP-directed therapies, sedation, mechanical ventilation, and cardiovascular support) are discussed. Comparative studies in rodent and large animal models of TBI (which may, in some cases, represent super models) are also presented. We conclude that therapeutic breakthroughs will likely require a multidisciplinary approach, involving investigation in a range of models, including clinically relevant modifications of established animal models, along with development and application of new innovations in clinical trial design.

Traumatic brain injury in mice deficient in poly-ADP(ribose) polymerase: a preliminary report

Poly (ADP-ribose) polymerase (PARP) is a ubiquitous nuclear enzyme that, when activated by free-radical induced DNA damage, contributes to energy failure and cell death in models of central nervous system ischemia and reperfusion. PARP contributes to neuronal cell death in vivo after cerebral ischemia/reperfusion, however, the role of PARP in the pathogenesis of traumatic brain injury (TBI) is unknown. We hypothesized that, compared to wild type mice (+/+), mice deficient in PARP (-/-) would have reduced motor and cognitive deficits after TBI. Mice underwent controlled cortical impact (CCI) (6 m/s, 1.2 mm depth) and were tested for motor (d 1-5) and cognitive (d 14-18) function after CCI. PARP -/- mice demonstrated improved motor performance and improved cognitive function after CCI (both p < 0.05 compared to +/+). This is the first study to evaluate a role for PARP in functional outcome after TBI. The results suggest a detrimental role for PARP in the pathogenesis of TBI.

Cerebral resuscitation after traumatic brain injury and cardiopulmonary arrest in infants and children in the new millennium

As outlined in Figure 1, it is likely that a series of interventions beginning in the field and continuing through the emergency department, ICU, rehabilitation center, and possibly beyond, will be needed to optimize clinical outcome after severe TBI or asphyxial CA in infants and children. Despite the many differences between these two important pediatric insults, it is likely that many of the therapies targeting neuronal death, in either condition, will need to be administered early after the insult, possibly at the injury scene. Even cerebral swelling, a pathophysiologic derangement routinely treated in the PICU, almost certainly is better prevented rather than treated. Finally, this review includes, for one of the first times, a brief discussion of additional horizons in the management of patients with severe brain injury, namely, manipulation of the injured circuitry and stimulation of regeneration. Further research is needed to define better the pathobiology of these two important conditions at the bedside, to understand the optimal application of contemporary therapies, and to develop and apply novel therapies. The tools necessary to carry out these studies are materializing, although the obstacles are great. This difficult but important challenge awaits further investigation by clinician-scientists in pediatric neurointensive care.

Interstitial brain adenosine and xanthine increase during jugular venous oxygen desaturations in humans after traumatic brain injury

OBJECTIVE

Adenosine decreases the cerebral metabolic rate for oxygen and increases cerebral blood flow, and it may play an important role in cerebrometabolic and cerebrovascular responses to hypoperfusion after traumatic brain injury. Jugular venous oxygen saturation is monitored after traumatic brain injury to assess brain oxygen extraction, and desaturations may reflect secondary brain insults. We hypothesized that brain interstitial adenosine and related purine metabolites would be increased during jugular venous oxygen saturation desaturations (<50%) and determined associations between the purines, lactate, and glucose to assess the role of adenosine during secondary insults in humans.

DESIGN

Study of critically ill adults with severe traumatic brain injury.

SETTING

Adult neurointensive care unit.

PATIENTS

We prospectively defined periods of normal saturation and desaturation in six patients after severe traumatic brain injury.

INTERVENTIONS

During these periods, cerebral microdialysis samples of brain interstitial fluid were collected, and adenosine and purine metabolites were measured by high-pressure liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Adenosine increased 3.1-fold and xanthine increased 2.5-fold during desaturation periods (both p <.05 vs. normal saturation period, signed rank). Adenosine, xanthine, hypoxanthine, and cyclic-adenosine monophosphate correlated with lactate over both study periods (r(2) =.32,.14,.31,.07, and.26, respectively, all p <.05, Pearson product moment correlation).

CONCLUSION

The marked increases in interstitial brain adenosine that occur during jugular venous oxygen desaturations suggest that adenosine may play an important role during periods of secondary insults after traumatic brain injury. The correlation of these metabolites with lactate further suggests that adenosine is increased during periods of enhanced glycolytic metabolism.

Adenovirus-mediated transfer and expression of beta-gal in injured hippocampus after traumatic brain injury in mice

In models of focal cerebral ischemia, adenoviral gene transfer is often attenuated or delayed versus naive. After controlled cortical impact (CCI)-induced traumatic brain injury in mice, CA1 and CA3 hippocampus exhibit delayed neuronal death by 3 days, with subsequent near complete loss of hippocampus by 21 days. We hypothesized that adenoviral-mediated expression of the reporter gene beta-Galactosidase (beta-Gal) in hippocampus would be attenuated after CCI in mice. C57BL6 mice (n = 16) were subjected to either CCI to left parietal cortex or sham (burr hole). Adenovirus carrying the beta-Gal gene (AdlacZ; 1 x 10(9) plaque-forming units [pfu]/mL) was then injected into left dorsal hippocampus. At 24 or 72 h, beta-Gal expression was quantified (mU/mg protein). Separate mice (n = 10) were used to study beta-Gal spatial distribution in brain sections. Beta-Gal expression in left hippocampus was similar in shams at 24 h (48.4 +/- 4.1) versus 72 h (68.8 +/- 8.8, not significant). CCI did not reduce beta-Gal expression in left hippocampus (68.8 +/- 8.8 versus 88.1 +/- 7.0 at 72 h, sham versus CCI, not significant). In contrast, CCI reduced beta-Gal expression in right (contralateral) hippocampus versus sham (p < 0.05 at both 24 and 72 h). Beta-Gal was seen in many cell types in ipsilateral hippocampus, including CA3 neurons. Despite eventual loss of ipsilateral hippocampus, adenovirus-mediated gene transfer was surprisingly robust early after CCI providing an opportunity to test novel genes targeting delayed hippocampal neuronal death.

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.

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.

Effect of neutropenia and granulocyte colony stimulating factor-induced neutrophilia on blood-brain barrier permeability and brain edema after traumatic brain injury in rats

OBJECTIVE

Granulocyte colony stimulating factor (GCSF) has been used to increase systemic absolute neutrophil count (ANC) in patients with severe traumatic brain injury to reduce nosocomial infection risk. However, the effect of increasing systemic ANC on the pathogenesis of experimental traumatic brain injury has not been studied. Thus, we evaluated the effect of systemic ANC on blood-brain barrier (BBB) damage and brain edema after traumatic brain injury in rats.

DESIGN

Experimental study.

SETTING

Research laboratory at the University of Pittsburgh, PA.

SUBJECTS

Forty-three adult male Sprague-Dawley rats.

INTERVENTIONS

Protocol I: rats were randomized to receive either vinblastine sulfate to reduce ANC, GCSF to increase ANC, or saline before controlled cortical impact (CCI) of moderate overall severity. Evans blue was used to assess BBB damage at 4-24 hrs after CCI. Protocol II: rats received GCSF or saline before CCI. Brain edema was estimated at 24 hrs using wet - dry) / wet weight method. Protocol III: rats received GCSF or saline before CCI. Brain neutrophil accumulation was estimated at 24 hrs using a myeloperoxidase assay.

MEASUREMENTS AND MAIN RESULTS

Physiologic variables were controlled before CCI was maintained at normal in all animals before traumatic brain injury. No rats were anemic, hypoglycemic, or hypotensive before CCI. Protocol I: compared with control, systemic ANC decreased in vinblastine-treated rats and increased in GCSF-treated rats. BBB damage correlated with systemic ANC. Protocol II: mean systemic ANC before traumatic brain injury increased 15-fold in rats given GCSF vs. control; however no difference in brain edema was observed at 24 hrs after injury between groups. Protocol III: median systemic ANC at the time of CCI was increased ten-fold in rats given GCSF vs. control. No difference in brain myeloperoxidase activity 24 hrs after CCI was observed in rats treated with GCSF vs. control.

CONCLUSIONS

Systemic ANC influences BBB damage after traumatic brain injury produced by CCI. Because BBB damage and brain edema are discordant, mechanisms other than BBB damage likely predominate in the pathogenesis of brain edema after contusion. The implications of increased BBB permeability with the administration of GCSF in our model remains to be determined. Increasing systemic ANC before CCI with GCSF administration does not increase posttraumatic brain neutrophil accumulation or brain edema after CCI in rats. The finding that neutrophil infiltration is not enhanced by systemic neutrophilia suggests that the ability of GCSF-stimulated neutrophils to migrate into injured tissue may be impaired. Further studies are needed to evaluate the effects of GCSF administration on secondary injury and functional outcome in experimental models of traumatic brain injury.

Bcl-2 family gene products in cerebral ischemia and traumatic brain injury

The proto-oncogene bcl-2 plays a key role in regulating programmed cell death in neurons. The present review discusses the mechanisms by which bcl-2 family genes regulate programmed cell death, and their role in controlling cell death in cerebral ischemia and traumatic brain. Expression of several bcl-2 family members is altered in brain tissues after ischemia and trauma, suggesting that bcl-2 family genes could play a role in determining the fate of injured neurons. Furthermore, alteration of expression of bcl-2 family genes using transgenic approaches, viral vectors, or anti-sense oligonucleotides modifies neuronal cell death and neurological outcome after injury. These data suggest that the activity of bcl-2 family gene products participates in determining cellular and neurologic outcomes in ischemia and trauma. Strategies that either mimic the death-suppressor effects or inhibit the death-promoter effects of bcl-2 family gene products may improve outcome after ischemia and trauma.

No long-term benefit from hypothermia after severe traumatic brain injury with secondary insult in rats

OBJECTIVES

To evaluate the effect of application of transient, moderate hypothermia on outcome after experimental traumatic brain injury (TBI) with a secondary hypoxemic insult.

DESIGN

Prospective, randomized study.

SETTING

University-based animal research facility.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

All rats were subjected to severe TBI followed by 30 mins of moderate hypoxemia, associated with mild hypotension. Rats were randomized to three groups: a) normothermia (37 degrees C + 0.5 degrees C); b) immediate hypothermia (32 degrees C +/- 0.5 degrees C initiated after trauma, before hypoxemia); and c) delayed hypothermia (32 degrees C +/- 0.5 degrees C after hypoxemia). The brain temperature was controlled for 4 hrs after TBI and hypoxemia.

MEASUREMENTS AND MAIN RESULTS

Animals were evaluated after TBI for motor and cognitive performance using beam balance (days 1-5 after TBI), beam walking (days 1-5 after TBI), and Morris Water Maze (days 14-18 after TBI) assessments. On day 21 after TBI, rats were perfused with paraformaldehyde and brains were histologically evaluated for lesion volume and hippocampal neuron counts. All three groups showed marked deficits in beam balance, beam walking, and Morris Water Maze performance. However, these deficits did not differ between groups. There was no difference in lesion volume between groups. All animals had significant hippocampal neuronal loss on the side ipsilateral to injury, but this loss was similar between groups.

CONCLUSIONS

In this rat model of severe TBI with secondary insult, moderate hypothermia for 4 hrs posttrauma failed to improve motor function, cognitive function, lesion volume or hippocampal neuronal survival. Combination therapies may be necessary in this difficult setting.

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.

Alterations in bcl-2 and caspase gene family protein expression in human temporal lobe epilepsy

OBJECTIVE

To address the role of cell death regulatory genes of the bcl-2 and caspase families in the neuropathology of human epilepsy using tissue extracted from patients undergoing temporal lobectomy for intractable seizures.

METHODS

Using Western blotting and immunohistochemistry, the authors investigated the expression of bcl-2, bcl-xL, bax, caspase-1,and caspase-3 in temporal cortex samples from patients who had undergone temporal lobectomy surgery for intractable epilepsy (n = 19). Nonepileptic postmortem tissue from a brain bank served as control (n = 6).

RESULTS

Western blot analysis demonstrated significant increases in levels of bcl-2 and bcl-xL protein in seizure brain compared to control. Cleavage of caspase-1 was evidenced by a reduction in levels of the 45 kDa proenzyme form and an increase in levels of the p10 fragment. Levels of the 32 kDa proenzyme form of caspase-3 were elevated in seizure patients, as were levels of the 12 kDa cleaved fragment. Bcl-2, bax, and caspase-3 immunoreactivity was increased predominantly in cells with the morphologic appearance of neurons, whereas bcl-xL immunoreactivity was increased in cells with the appearance of glia. DNA fragmentation was detected in some but not all sections from epileptic brain samples.

CONCLUSIONS

Cell death regulatory genes of the bcl-2 and caspase families may play a role in ongoing neuropathologic processes in human epilepsy, and offer novel targets as an adjunct to anticonvulsant therapy.

Interleukin-8 is increased in cerebrospinal fluid of children with severe head injury

OBJECTIVE

To determine interleukin (IL)-8 concentrations in ventricular cerebrospinal fluid from children with severe traumatic brain injury (TBI).

DESIGN

Prospective study.

SETTING

University children's hospital.

PATIENTS

Twenty-seven children hospitalized with severe TBI (Glasgow Coma Scale score < or =8), seven children with cerebrospinal fluid culture-positive bacterial meningitis, and twenty-four age-equivalent controls.

INTERVENTIONS

Placement of an intraventricular catheter and continuous drainage of cerebrospinal fluid.

MEASUREMENTS AND MAIN RESULTS

Median [range] cerebrospinal fluid IL-8 concentration in children with TBI (0-12 hrs) (4,452.5 [0-20,000] pg/mL) was markedly greater than that in controls (14.5 [0-250]) (p < .0001) and equivalent to concentrations in children with meningitis (5,300 [1,510-22,000] pg/mL) (p = .33). Cerebrospinal fluid IL-8 remained increased in children with severe TBI for up to 108 hrs after injury. Univariate logistic regression analysis demonstrated an association between cerebrospinal fluid IL-8 and child abuse (p = .07) and mortality (p = .01). Multivariate analysis demonstrated a strong, independent association between cerebrospinal fluid IL-8 and mortality (p = .01).

CONCLUSIONS

The data are consistent with an acute inflammatory component of TBI in children and suggest an association between cerebrospinal fluid IL-8 and outcome after TBI. IL-8 may represent a potential target for anti-inflammatory therapy.

Reduced brain edema after traumatic brain injury in mice deficient in P-selectin and intercellular adhesion molecule-1

Platelet (P-) selectin and intercellular adhesion molecule-1 (ICAM-1) mediate accumulation of neutrophils in brain. However, the mechanisms regulating neutrophil accumulation and damage after traumatic brain injury (TBI) are poorly defined. We hypothesized that mice deficient in both P-selectin and ICAM-1 (-/-) would have decreased brain neutrophil accumulation and edema, and improved functional and histopathological outcome after TBI compared with wild-type (+/+). In Protocol I, neutrophils and brain water content were quantified at 24 h after TBI. No difference in brain neutrophil accumulation was observed between groups; however, brain edema was decreased in dual P-selectin and ICAM-1 -/- (P < 0.05 vs. +/+ mice). In Protocol II, after TBI, tests of motor and memory function and histopathology were assessed over 21 days. No difference in motor or memory function or histopathological damage was observed between +/+ and -/- mice. A role for adhesion molecules in the pathogenesis of brain edema independent of leukocyte accumulation in brain is suggested.

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.

Inducible nitric oxide synthase is an endogenous neuroprotectant after traumatic brain injury in rats and mice

Nitric oxide (NO) derived from the inducible isoform of NO synthase (iNOS) is an inflammatory product implicated both in secondary damage and in recovery from brain injury. To address the role of iNOS in experimental traumatic brain injury (TBI), we used 2 paradigms in 2 species. In a model of controlled cortical impact (CCI) with secondary hypoxemia, rats were treated with vehicle or with 1 of 2 iNOS inhibitors (aminoguanidine and L-N-iminoethyl-lysine), administered by Alzet pump for 5 days and 1. 5 days after injury, respectively. In a model of CCI, knockout mice lacking the iNOS gene (iNOS(-/-)) were compared with wild-type (iNOS(+/+)) mice. Functional outcome (motor and cognitive) during the first 20 days after injury, and histopathology at 21 days, were assessed in both studies. Treatment of rats with either of the iNOS inhibitors after TBI significantly exacerbated deficits in cognitive performance, as assessed by Morris water maze (MWM) and increased neuron loss in vulnerable regions (CA3 and CA1) of hippocampus. Uninjured iNOS(+/+) and iNOS(-/-) mice performed equally well in both motor and cognitive tasks. However, after TBI, iNOS(-/-) mice showed markedly worse performance in the MWM task than iNOS(+/+) mice. A beneficial role for iNOS in TBI is supported.

Reduction of cognitive and motor deficits after traumatic brain injury in mice deficient in poly(ADP-ribose) polymerase

Poly(ADP-ribose) polymerase (PARP), or poly-(ADP-ribose) synthetase, is a nuclear enzyme that consumes NAD when activated by DNA damage. The role of PARP in the pathogenesis of traumatic brain injury (TBI) is unknown. Using a controlled cortical impact (CCI) model of TBI and mice deficient in PARP, the authors studied the effect of PARP on functional and histologic outcome after CCI using two protocols. In protocol 1, naive mice (n = 7 +/+, n = 6 -/-) were evaluated for motor and memory acquisition before CCI. Mice were then subjected to severe CCI and killed at 24 hours for immunohistochemical detection of nitrated tyrosine, an indicator of peroxynitrite formation. Motor and memory performance did not differ between naive PARP +/+ and -/- mice. Both groups showed nitrotyrosine staining in the contusion, suggest ing that peroxynitrite is produced in contused brain. In protoco 2, mice (PARP +/+, n = 8; PARP -/-, n = 10) subjected to CCI were tested for motor and memory function, and contusion volume was determined by image analysis. PARP -/- mice demonstrated improved motor and memory function after CC versus PARP +/+ mice (P < 0.05). However, contusion volume was not different between groups. The results suggest a detri mental effect of PARP on functional outcome after TBI.

Neutrophils do not mediate blood-brain barrier permeability early after controlled cortical impact in rats

Controlled cortical impact (CCI) produces blood-brain barrier (BBB) permeability and an acute inflammatory response in injured brain, associated with upregulation of cell adhesion molecules and accumulation of neutrophils. Nevertheless, the role of acute inflammation in the pathogenesis of BBB permeability after traumatic brain injury (TBI) is undefined. The purpose of this study was to examine the time course of acute inflammation and BBB permeability after CCI in rats and to determine the effect of neutrophil depletion on BBB permeability early after CCI. In the first protocol, four groups of rats (n = 4-7/group) were subjected to CCI. Expression of endothelial (E)-selectin on cerebrovascular endothelium, accumulation of neutrophils, and BBB permeability were measured in brain at 1, 4, 8, and 24 hours after injury by immunohistochemistry or spectrophotometric quantification of Evans blue. E-selectin upregulation and neutrophil accumulation in injured brain occurred at later times than maximal BBB permeability. In a second protocol, rats made neutropenic with a murine monoclonal IgM antibody (RP-3) specific for rat neutrophils were subjected to CCI, given Evans blue at 3.5 hours, and sacrificed at 4 hours after injury. Neutrophil depletion did not affect BBB permeability at 4 hours after CCI. We conclude that events other than those mediated by neutrophils initiate BBB permeability early after CCI.

Increases in Bcl-2 and cleavage of caspase-1 and caspase-3 in human brain after head injury

The bcl-2 and caspase families are important regulators of programmed cell death in experimental models of ischemic, excitotoxic, and traumatic brain injury. The Bcl-2 family members Bcl-2 and Bcl-xL suppress programmed cell death, whereas Bax promotes programmed cell death. Activated caspase-1 (interleukin-1beta converting enzyme) and caspase-3 (Yama/Apopain/Cpp32) cleave proteins that are important in maintaining cytoskeletal integrity and DNA repair, and activate deoxyribonucleases, producing cell death with morphological features of apoptosis. To address the question of whether these Bcl-2 and caspase family members participate in the process of delayed neuronal death in humans, we examined brain tissue samples removed from adult patients during surgical decompression for intracranial hypertension in the acute phase after traumatic brain injury (n=8) and compared these samples to brain tissue obtained at autopsy from non-trauma patients (n=6). An increase in Bcl-2 but not Bcl-xL or Bax, cleavage of caspase-1, up-regulation and cleavage of caspase-3, and evidence for DNA fragmentation with both apoptotic and necrotic morphologies were found in tissue from traumatic brain injury patients compared with controls. These findings are the first to demonstrate that programmed cell death occurs in human brain after acute injury, and identify potential pharmacological and molecular targets for the treatment of human head injury.

Effect of traumatic brain injury in mice deficient in intercellular adhesion molecule-1: assessment of histopathologic and functional outcome

Intercellular adhesion molecule-1 (ICAM-1) is an adhesion molecule of the immunoglobulin family expressed on endothelial cells that is upregulated in brain as part of the acute inflammatory response to traumatic brain injury (TBI). ICAM-1 mediates neurologic injury in experimental meningitis and stroke; however, its role in the pathogenesis of TBI is unknown. We hypothesized that mutant mice deficient in ICAM-1 (-/-) would have decreased neutrophil accumulation, diminished histologic injury, and improved functional neurologic outcome versus ICAM-1 +/+ wild type control mice after TBI. Anesthetized ICAM-1 -/- mice and wild-type controls were subjected to controlled cortical impact (CCI, 6 m/sec, 1.2 mm depth). Neutrophils in brain parenchyma and ICAM-1 on vascular endothelium were assessed by immunohistochemistry in cryostat brain sections from the center of the contusion 24 h after TBI (n = 4/group). Separate groups of wild-type and ICAM-1-deficient mice (n = 9-10/group) underwent motor (wire grip test, days 1-5) and cognitive (Morris water maze [MWM], days 14-20) testing. Lesion volume was determined by image analysis 21 days following TBI. Robust expression of ICAM-1 was readily detected in choroid plexus and cerebral endothelium at 24 h in ICAM-1 +/+ mice but not in ICAM-1 -/- mice. No differences between groups were observed in brain neutrophil accumulation (9.4 +/- 2.2 versus 11.1 +/- 3.0 per x100 field, -/- versus +/+), wire grip score, MWM latency, or lesion volume (7.24 +/- 0.63 versus 7.21 +/- 0.45 mm3, -/- versus +/+). These studies fail to support a role for ICAM-1 in the pathogenesis of TBI.

Quinolinic acid in the cerebrospinal fluid of children after traumatic brain injury

OBJECTIVE

To measure quinolinic acid, a macrophage-derived neurotoxin, in the cerebrospinal fluid (CSF) of children after traumatic brain injury (TBI) and to correlate CSF quinolinic acid concentrations to clinically important variables.

DESIGN

A prospective, observational study.

SETTING

The pediatric intensive care unit in Children's Hospital of Pittsburgh, a tertiary care, university-based children's hospital.

PATIENTS

Seventeen critically ill children following severe TBI (Glasgow Coma Scale score <8) whose care required the placement of an intraventricular catheter for continuous drainage of CSF.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients ranged in age from 2 mos to 16 yrs (mean 6.0 yrs). CSF was collected immediately on placement of the ventricular catheter and daily thereafter. Quinolinic acid concentration was measured by gas chromatography/mass spectroscopy in 69 samples (4.0 +/- 0.4 [SEM] samples per patient). CSF quinolinic acid concentration progressively increased after injury (p = .034, multivariate analysis) and was increased in nonsurvivors vs. survivors (p = .002, multivariate analysis). CSF quinolinic acid concentration was not associated with age. Although overall CSF quinolinic acid concentration was not associated with shaken injury (p = .16, multivariate analysis), infants suffering with shaken infant syndrome had increased admission CSF quinolinic acid concentrations compared with children with accidental mechanisms of injury (p = .027, Mann-Whitney Rank Sum test).

CONCLUSIONS

A large and progressive increase in the macrophage-derived neurotoxin quinolinic acid is seen following severe TBI in children. The increase is strongly associated with increased mortality. Increased CSF quinolinic acid concentration on admission in children with shaken infant syndrome could reflect a delay in presentation to medical attention or age-related differences in quinolinic acid production. These findings raise the possibility that quinolinic acid may play a role in secondary injury after TBI in children and suggest an interaction between inflammatory and excitotoxic mechanisms of injury following TBI.

A synteny map of the horse genome comprised of 240 microsatellite and RAPD markers

To generate a domestic horse genome map we integrated synteny information for markers screened on a somatic cell hybrid (SCH) panel with published information for markers physically assigned to chromosomes. The mouse-horse SCH panel was established by fusing pSV2neo transformed primary horse fibroblasts to either RAG or LMTk mouse cells, followed by G418 antibiotic selection. For each of the 108 cell lines of the panel, we defined the presence or absence of 240 genetic markers by PCR, including 58 random amplified polymorphic DNA (RAPD) markers and 182 microsatellites. Thirty-three syntenic groups were defined, comprised of two to 26 markers with correlation coefficient (r) values ranging from 0.70 to 1.0. Based on significant correlation values with physically mapped microsatellite (type II) or gene (type I) markers, 22 syntenic groups were assigned to horse chromosomes (1, 2, 3, 4, 6, 9, 10, 11, 12, 13, 15, 18, 19, 20, 21, 22, 23, 24, 26, 30, X and Y). The other 11 syntenic groups were provisionally assigned to the remaining chromosomes based on information provided by heterologous species painting probes and work in progress with type I markers.

Soluble adhesion molecules in CSF are increased in children with severe head injury

Leukocyte-endothelial adhesion molecules, critical to the development of acute inflammation, are expressed in brain as part of the acute inflammatory response to traumatic brain injury (TBI). We measured the concentrations of the adhesion molecules P-selectin, ICAM-1, E-selectin, L-selectin, and VCAM-1 in ventricular cerebrospinal fluid (CSF) from children with severe TBI (Glasgow coma score < 8) and compared these findings with those from children with bacterial meningitis. P-selectin, an adhesion molecule associated with ischemia/reperfusion, was increased in children with TBI versus meningitis and control. Univariate and multivariate regression analyses demonstrated associations between CSF P-selectin and child abuse and age of < 4 years, and a significant, independent association between CSF intercellular adhesion molecule-1 (ICAM-1) and child abuse. These results are consistent with a specific acute inflammatory component to TBI in children. Future studies of secondary injury mechanisms and therapy after TBI should assess on the roles of P-selectin and ICAM-1 in injury and repair processes in brain after TBI.

Quinolinic acid is increased in CSF and associated with mortality after traumatic brain injury in humans

We tested the hypothesis that quinolinic acid, a tryptophan-derived N-methyl-D-aspartate agonist produced by macrophages and microglia, would be increased in CSF after severe traumatic brain injury (TBI) in humans, and that this increase would be associated with outcome. We also sought to determine whether therapeutic hypothermia reduced CSF quinolinic acid after injury. Samples of CSF (n = 230) were collected from ventricular catheters in 39 patients (16 to 73 years old) during the first week after TBI, (Glasgow Coma Scale [GCS] < 8). As part of an ongoing study, patients were randomized within 6 hours after injury to either hypothermia (32 degrees C) or normothermia (37 degrees C) treatments for 24 hours. Otherwise, patients received standard neurointensive care. Quinolinic acid was measured by mass spectrometry. Univariate and multivariate analyses were used to compare CSF quinolinic acid concentrations with age, gender, GCS, time after injury, mortality, and treatment (hypothermia versus normothermia). Quinolinic acid concentration in CSF increased maximally to 463 +/- 128 nmol/L (mean +/- SEM) at 72 to 83 hours after TBI. Normal values for quinolinic acid concentration in CSF are less than 50 nmol/L. Quinolinic acid concentration was increased 5- to 50-fold in many patients. There was a powerful association between time after TBI and increased quinolinic acid (P < 0.00001), and quinolinic acid was higher in patients who died than in survivors (P = 0.003). Age, gender, GCS, and treatment (32 degrees C versus 37 degrees C) did not correlate with CSF quinolinic acid. These data reveal a large increase in quinolinic acid concentration in CSF after TBI in humans and raise the possibility that this macrophage-derived excitotoxin may contribute to secondary damage.

Augmented neuronal death in CA3 hippocampus following hyperventilation early after controlled cortical impact

Minimizing secondary injury after severe traumatic brain injury (TBI) is the primary goal of cerebral resuscitation. For more than two decades, hyperventilation has been one of the most often used strategies in the management of TBI. Laboratory and clinical studies, however, have verified a post-TBI state of reduced cerebral perfusion that may increase the brain's vulnerability to secondary injury. In addition, it has been suggested in a clinical study that hyperventilation may worsen outcome after TBI.

OBJECT

Using the controlled cortical impact model in rats, the authors tested the hypothesis that aggressive hyperventilation applied immediately after TBI would worsen functional outcome, expand the contusion, and promote neuronal death in selectively vulnerable hippocampal neurons.

METHODS

Twenty-six intubated, mechanically ventilated, isoflurane-anesthetized male Sprague-Dawley rats were subjected to controlled cortical impact (4 m/second, 2.5-mm depth of deformation) and randomized after 10 minutes to either hyperventilation (PaCO2 = 20.3 +/- 0.7 mm Hg) or normal ventilation groups (PaCO2 = 34.9 +/- 0.3 mm Hg) containing 13 rats apiece and were treated for 5 hours. Beam balance and Morris water maze (MWM) performance latencies were measured in eight rats from each group on Days 1 to 5 and 7 to 11, respectively, after controlled cortical impact. The rats were killed at 14 days postinjury, and serial coronal sections of their brains were studied for contusion volume and hippocampal neuron counting (CA1, CA3) by an observer who was blinded to their treatment group. Mortality rates were similar in both groups (two of 13 in the normal ventilation compared with three of 13 in the hyperventilation group, not significant [NS]). There were no differences between the groups in mean arterial blood pressure, brain temperature, and serum glucose concentration. There were no differences between groups in performance latencies for both beam balance and MWM or contusion volume (27.8 +/- 5.1 mm3 compared with 27.8 +/- 3.3 mm3, NS) in the normal ventilation compared with the hyperventilation groups, respectively. In brain sections cut from the center of the contusion, hippocampal neuronal survival in the CA1 region was similar in both groups; however, hyperventilation reduced the number of surviving hippocampal CA3 neurons (29.7 cells/hpf, range 24.2-31.7 in the normal ventilation group compared with 19.9 cells/hpf, range 17-23.7 in the hyperventilation group [25th-75th percentiles]; *p < 0.05, Mann-Whitney rank-sum test).

CONCLUSIONS

Aggressive hyperventilation early after TBI augments CA3 hippocampal neuronal death; however, it did not impair functional outcome or expand the contusion. These data indicate that CA3 hippocampal neurons are selectively vulnerable to the effects of hyperventilation after TBI. Further studies delineating the mechanisms underlying these effects are needed, because the injudicious application of hyperventilation early after TBI may contribute to secondary neuronal injury.

72-kDa heat shock protein and mRNA expression after controlled cortical impact injury with hypoxemia in rats

As part of the stress response, the 72 kDa heat shock protein (hsp72) is induced in neurons after ischemic and traumatic brain injury (TBI). To examine the stress response after TBI with secondary insult, we examined the regional and cellular expression of hsp72 mRNA and protein after controlled cortical impact (CCI) injury with secondary hypoxemia and mild hypotension in rats. Rats were killed at 6, 8, 24, 72, or 168 h after trauma. Naive and sham-operated rats were used as controls. Brains were removed, and in situ hybridization (n = 2/group), immunocytochemistry (n = 4/group), and Western blot analysis (n = 3 to 5/group) for hsp72 was performed. Hsp72 mRNA was expressed in neurons in the ipsilateral cortex, CA3 region of the hippocampus, hilus, and dentate gyrus at 6 h. Hsp72 mRNA was expressed primarily in the ipsilateral cortex, at 24 h, and by 72 h hsp72 mRNA expression returned to near basal levels. Hsp72 protein was seen in ipsilateral cortical neurons, hilar neurons, and neurons in the medial aspect of the CA3 region of the hippocampus (CA3-c) at 24 h. At 72 h, hsp72 immunoreactivity was reduced versus 24 h in these same regions, but it was increased versus baseline. Western blot analysis confirmed an increase in hsp72 protein in the ipsilateral cortex. The regional pattern of hsp72 mRNA induction in neurons was similar to the pattern of protein expression after CCI, with the exceptions that hsp72 mRNA, but not protein, was expressed in the dentate gyrus and the lateral aspect of the CA3 region of the hippocampus (CA3-a). The stress response, as detected by hsp72 expression, is induced in some neurons in some regions that are selectively vulnerable to delayed neuronal death in this model of TBI. The failure to translate some proteins including hsp72 may be associated with delayed neuronal death in certain hippocampal regions after TBI.

Interstitial adenosine, inosine, and hypoxanthine are increased after experimental traumatic brain injury in the rat

Adenosine is a putative neuroprotectant in ischemia, but its role after traumatic brain injury (TBI) is not clear. Metabolites of adenosine, particularly inosine and hypoxanthine, are markers of ischemia and energy failure. Adenosine triphosphate (ATP) breakdown early after injury and metabolism of cyclic adenosine monophosphate (cAMP) are potential sources of adenosine. Further delineation of the magnitude, location, time course, and source of production of adenosine after TBI is needed. We measured adenosine, inosine, and hypoxanthine in brain interstitial fluid after controlled cortical impact (CCI) in the rat. Rats (n = 15) were prepared for TBI induced by CCI. A microdialysis probe was placed in the cortex, and samples were collected every 10 min. After 3 h of equilibration, the catheter was removed, CCI was performed (4 m/sec, depth 2.5 mm), and the catheter was replaced. In the shams, the catheter was removed and replaced without CCI. The injury group included rats (n = 10) subjected to CCI. Within the injury group, the microdialysis probe was placed in the center of the eventual contusion (center, n = 5) or in the penumbral region (penumbra, n = 5). Purine metabolites were measured using ultraviolet-based high-pressure liquid chromatography. Adenosine, inosine, and hypoxanthine were dramatically increased after injury (61-fold, 37-fold, and 16-fold, respectively sham, all p < 0.05, two-way analysis of variance for repeated measures). No changes in cAMP were observed (p = 0.62 vs. sham). Adenosine peaked in the first 20 min and returned to near baseline 40 min, whereas inosine and hypoxanthine peaked at 30 min and remained increased for 40 min after CCI. Interstitial brain adenosine, inosine, and hypoxanthine were increased early after CCI in rats in the contusion and penumbra. ATP breakdown is a potential source of adenosine in this early period while metabolism of cAMP does not appear to play a role. Confirmation of these data in humans may suggest new strategies targeting this important metabolic pathway.

The relationship between brain temperature and neutrophil accumulation after traumatic brain injury in rats

Mild hypothermia reduces secondary damage after traumatic brain injury (TBI) in rodent models; however, the mechanisms involved in this beneficial effect remain unclear. We previously reported that TBI induces the upregulation of adhesion molecules and infiltration of neutrophils (PMN) in brain. Since PMN accumulation may be associated with the development of hyperemia and blood-brain barrier injury, we hypothesized that hypothermia would reduce acute inflammation after TBI in rats. To test this hypothesis, rats were anesthetized and subjected to TBI by controlled cortical impact to left parietal cortex. Brain temperature was controlled at 32 degrees C, 37 degrees C, or 39 degrees C (n = 8 per group) for 4 h after TBI, then rats were sacrificed and brain were harvested. Immunohistochemistries were performed on brain sections using antibodies that recognize the adhesion molecules E-selectin and intercellular adhesion molecule-1 (ICAM-1), and PMN. PMN were also quantified using a myeloperoxidase (MPO) assay. PMN accumulation in injured brain was decreased in rats maintained at 32 degrees C vs 39 degrees C (4-fold by immunohistochemistry and 8-fold by MPO, p < 0.05). E-selectin was induced after TBI, but not attenuated by hypothermia. ICAM-1 was not up-regulated at this early time after TBI. Based on these preliminary data, we conclude that mild hypothermia reduces PMN accumulation in injured brain during the initial 4 h after TBI, without decreasing adhesion molecule expression.

Comparison of the interleukin-6 and interleukin-10 response in children after severe traumatic brain injury or septic shock

Inflammation may play an important role in the evolution of damage after traumatic brain injury (TBI). IL-6 and IL-10 are markers of inflammation that are pro- and anti-inflammatory in nature, respectively. They have been used as an index of the degree of inflammation in diseases including sepsis and meningitis. We hypothesized that both IL-6 and IL-10 would be increased in the cerebrospinal fluid (CSF) of children after TBI. We measured ventricular CSF concentrations of these metabolites (ELISA) each of the first 3 days after TBI in 15 children. CSF IL-6 was increased on day 1 (p < 0.05 vs days 2 or 3). CSF IL-10 was similarly increased on day 1 (p < 0.05). CSF IL-6 after TBI is similar to serum IL-6 levels previously reported in children with septic shock. In contrast, the CSF IL-10 response was markedly attenuated following TBI compared to sepsis. These data suggest a unique balance between pro- and anti-inflammatory cytokines in brain after TBI.

The role of adenosine during the period of delayed cerebral swelling after severe traumatic brain injury in humans

Cerebrovascular failure with an increase in cerebral blood volume or hyperemia contributes delayed cerebral swelling after severe traumatic brain injury (TBI) in humans. One mediator that could be involved in this process is adenosine, which stimulates a concurrent reduction in cerebral metabolic rate and an increase in cerebral blood flow (CBF). We hypothesized that during the delayed phase after TBI in humans: 1) CSF adenosine concentration is associated with uncoupling of CBF and CMRO2, and 2) adenosine formation is driven by mediator-stimulated cAMP production in injured brain. We serially measured CBF and AVDO2, and CSF adenosine, lactate and cAMP after severe TBI in 13 humans. After 6-18 h, global CBF was increased and AVDO2 was reduced vs all other time periods, defining the uncoupling phase as the period between 18 h and 5 days. CSF adenosine concentration was negatively associated with AVDO2 and strongly associated with death (both p < 0.05), CSF lactate peaked during the initial 18 h, but remained increased for 5 days. CSF cAMP concentration was not increased (vs normal). The association between CSF adenosine concentration and death, and the correlation between uncoupling of CBF and oxidative metabolism and CSF adenosine concentration support our first hypothesis. In contrast, the low levels of cAMP in CSF observed in these patients, but persistently increased CSF lactate, refute our second hypothesis. We speculate that hyperglycolysis or occult ischemic foci are possible sources of ATP breakdown and adenosine formation, and that adenosine is playing a neuroprotective role.

Cerebrospinal fluid adenosine concentration and uncoupling of cerebral blood flow and oxidative metabolism after severe head injury in humans

OBJECTIVE

Uncoupling of cerebral blood flow (CBF) and oxidative metabolism is observed after severe head injury in comatose patients; however, the mechanism(s) involved remain undefined. Adenosine can produce cerebral vasodilation and reduce neuronal activity and is a possible mediator of uncoupling. We hypothesized that cerebrospinal fluid (CSF) adenosine concentrations would be increased during uncoupling of CBF and oxidative metabolism, defined as a narrow arterio-jugular venous oxygen difference [D(a-v)O2 4 vol%] after head injury.

METHODS

Adenosine concentrations were measured using fluorescent-based high-pressure liquid chromatography in 67 CSF samples obtained from 13 comatose (Glasgow Coma Scale score 7) adult patients who sustained a severe closed head injury. At the time each sample was obtained, CBF was measured by the xenon-133 method, and blood samples were obtained for determination of D(a-v)O2.

RESULTS

CSF adenosine concentration was negatively associated with D(a-v)O2 (P < 0.05, generalized multivariate linear regression model). In addition, CSF adenosine concentration was increased when D(a-v)O2 was 4 versus > 4 vol% (38.5 [3.2-306.3] versus 14.0 [2.7-795.5] nmol/L, respectively, median [range]; P < 0.025) and in patients who died versus survivors (40.1 [6.9-306.3] versus 12.9 [2.7-795.5] nmol/L, respectively, median [range]; P < 0.001).

CONCLUSION

The association between increased CSF adenosine concentration and a reduction in global cross-brain extraction of oxygen supports a regulatory role for adenosine in the complex balance between CBF and oxidative and nonoxidative metabolism severe head injury in humans.

Apoptosis-suppressor gene bcl-2 expression after traumatic brain injury in rats

Neuronal death after experimental traumatic brain injury (TBI) has features of both apoptosis and necrosis. Neurons in the peritrauma cortex, hippocampus, and dentate gyrus are particularly vulnerable. The apoptosis-suppressor gene bcl-2 is induced in brain after ischemia and epilepsy-induced injury and may serve to regulate neuronal death. We studied expression of bcl-2 mRNA and protein after experimental TBI in rats. To determine whether bcl-2 protein expression occurred in cells with evidence of apoptosis, triple-labeling studies were performed using (1) antibody against bcl-2, (2) bis-benzimide dye to examine gross nuclear morphology, and (3) terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick-end labeling (TUNEL) to assess for DNA fragmentation. At 6 and 24 hr, bcl-2 mRNA was induced in ipsilateral peritrauma cortex, hippocampus, and dentate gyrus. By 72 hr the increase in bcl-2 mRNA was detected only in cortex. bcl-2 protein was induced at 8, 24, 72, and 168 hr in ipsilateral cortex and hippocampus. Cells expressing bcl-2 protein included neurons in the peritrauma cortex, hippocampus, hilus, and dentate gyrus. The gross nuclear morphology of neurons expressing bcl-2 appeared normal. Furthermore, biochemical evidence of DNA fragmentation, in a pattern characteristic of either apoptosis or necrosis, was seldom seen in neurons expressing bcl-2 protein (bcl-2 colocalized with TUNEL in 0-2% of TUNEL-positive cells observed). These data suggest that bcl-2 may play an important role in the regulation of neuronal death after TBI, and they support a role for bcl-2 as an inducible neuroprotective gene.

A longitudinal clinical assessment of spark erosion technology in implant-retained overdenture prostheses: a preliminary report

STATEMENT OF PROBLEM

As adapted for the dental profession, spark erosion technology permits precise machining of retentive metal overdenture frameworks for use in implant prosthetics.

PURPOSE

The resultant prostheses are retentive and provide a number of benefits offered by both conventional overdenture and fixed prosthetic designs.

MATERIAL AND METHODS

Preliminary data collected from an ongoing 5-year clinical trial were reviewed to qualitatively assess the clinical results obtained from 25 spark eroded implant-retained overdenture prostheses placed in 24 subjects.

RESULTS

Throughout an evaluation period of 13.33 months (range 4 to 19 months), subject responses measured by questionnaire were uniformly good. Few complications were encountered and were limited to resin denture base/tooth fractures or retentive component failures that were easily repaired.

CONCLUSION

Overdenture prostheses retained by spark eroded milled frameworks offer an acceptable treatment alternative for patients undergoing dental implant therapy.

The effect of brain temperature on acute inflammation after traumatic brain injury in rats

The effect of varying brain temperature on neutrophil accumulation in brain and the expression of E-selectin and intercellular adhesion molecule-1 (ICAM-1) on cerebrovascular endothelium after controlled cortical impact (CCI) was studied in rats. Sprague Dawley rats were anesthetized and subjected to CCI to the left parietal cortex. Ten minutes after CCI, brain temperature was modulated and maintained at 32 degrees C, 37 degrees C, or 39 degrees C (n = 8 per group) for 4 h. Rats were then decapitated and immunohistochemistry on brain sections was performed using monoclonal antibodies (MoAb) that recognize neutrophils (RP-3), ICAM-1 (TM-8, Athena Neurosciences), or MoAb that react with E-selectin (La-Roche). Each of these markers was quantified in 100 x fields. Neutrophil accumulation was also quantified with myeloperoxidase (MPO) assay. Absolute neutrophil count (ANC) was measured in blood samples before and 1 h and 4 h after CCI. Neutrophil accumulation in injured brain was decreased in rats maintained at 32 degrees C vs 39 degrees C (4-fold difference as assessed by immunohistochemistry, p < 0.05; 8-fold difference as assessed by MPO assay, p < 0.05). Peripheral blood ANC was not affected by temperature. E-selectin was induced on cerebrovascular endothelium after CCI (p < 0.05), but was only decreased modestly at 32 degrees C versus 39 degrees C (p = 0.11). ICAM-1 was not upregulated on cerebrovascular endothelium at this early time following CCI. Neutrophil accumulation is directly dependent on brain temperature during the initial 4 h after CCI. This appears to be mediated by mechanisms other than effects of temperature on E-selectin or ICAM-1 expression or systemic ANC.

Validation of microsatellite markers for routine horse parentage testing

A parallel testing of 4803 routine Quarter Horse parentage cases, using 15 loci of blood group and protein polymorphisms (blood typing) and 11 loci of dinucleotide repeat microsatellites (DNA typing), validated DNA markers for horse pedigree verification. For the 26 loci, taken together, the theoretical effectiveness of detecting incorrect parentage was 99.999%, making it extremely unlikely that false parentage would fail to be recognized. The tests identified incorrect parentage assignment for 95 offspring (2% of cases). Despite fewer loci, DNA typing was as effective as blood typing and, in parentage exclusion cases, provided more systems to substantiate the genetic incompatibility. Five offspring presented potential genetic incompatibilities with their parents in only a single microsatellite system, but the parentage exclusions could not be confirmed with discordant results at additional loci. Two of these five incompatibilities could be explained as consequences of a null allele and three as fragment size increases or decreases (putative mutations). Provided that an exclusion assignment was based on at least two systems of genetic incompatibility, such rare genetic events did not lead to false exclusions. Notwithstanding the near 100% effectiveness estimations for either typing panel alone to identify incorrect parentage, this validation test showed an actual effectiveness of 97.3% for blood typing and 98.2% for DNA typing. The DNA-based test, however, may feasibly achieve higher efficacy than reported here by adding selected systems to the parentage test panel.

Interleukin-6 and interleukin-10 in cerebrospinal fluid after severe traumatic brain injury in children

Cytokines may play an important role in the pathophysiology of traumatic brain injury (TBI) in children. Interleukin-6 (IL-6) is a proinflammatory cyotkine that plays a role in regenerative processes within the central nervous system (CNS), whereas interleukin-10 (IL-10) is an antiinflammatory cytokine. Both have been measured in serum and cerebrospinal fluid (CSF) as an index of the degree of inflammation in diseases, including sepsis and meningitis. We hypothesized that both IL-6 and IL-10 would be increased in the CSF of children after severe TBI. Fifteen children who sustained severe TBI (Glascow Coma Score [GCS] < or = 7) were studied. Standard neurointensive care was provided. Ventricular CSF collected the first 3 days after TBI was analyzed for IL-6 and IL-10 concentrations by ELISA. Controls were 20 children who were evaluated for meningitis with diagnostic lumbar puncture subsequently found to have no CSF pleocytosis and negative cultures. IL-6 was increased in children after TBI versus controls on all days studied (day 1, 3158.2 +/- 621.8 pg/ml; day 2, 1111.6 +/- 337.0 pg/ml; day 3, 826.7 +/- 193.5 pg/ml vs. 20.6 +/- 5.8 pg/ml, p < 0.0001, Mann-Whitney Rank Sum). IL-10 was increased in children after TBI vs controls on all days studied (day 1, 47.2 +/- 12.9 pg/ml; day 2, 21.0 +/- 6.7 pg/ml; day 3, 15.5 +/- 5.9 pg/ml vs. 8.9 +/- 7.5 pg/ml, p < 0.01). Increased IL-10 concentrations were independently associated with age < 4 years and mortality (p = 0.004 and 0.04, respectively, multivariate linear model). This study demonstrates that IL-6 is increased after TBI in children to levels similar to those reported in adults and is the first to show that IL-10 is increased in CSF of humans after TBI. These data suggest that there may be an age-dependent production of IL-10 after TBI in children.

Early neuropathologic effects of mild or moderate hypoxemia after controlled cortical impact injury in rats

Hypoxemia has detrimental effects after traumatic brain injury (TBI) in both experimental models and humans. The purpose of this study was to determine the effect of mild or moderate hypoxemia on early histologic and motor functional outcome after controlled cortical impact (CCI) in rats. Anesthetized rats underwent CCI and were randomized to receive mild (FiO2 = 13%, n = 6), moderate (FiO2 = 11%, n = 9), or no (FiO2 = 33%, n = 6) hypoxemia for 30 min after trauma. Sham-operated rats without hypoxemia (n = 7) were used as controls. Motor function (beam balance latency) was assessed on days 0-5. Rats were killed 7 days after injury and their brains removed for assessment of survival of hippocampal neurons and contusion volume. Terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end labeling (TUNEL) was performed on brain sections from rats killed at 6, 24, and 72 h after CCI and moderate hypoxemia to assess DNA fragmentation in situ. Mild and moderate hypoxemia augmented motor function deficits after CCI in a dose-dependent manner. Moderate hypoxemia after CCI reduced 7-day survival of CA3 neurons but not CA1 neurons vs. sham (55 [46-86] vs. 99 [95-130], p < 0.05, and 79 [63-86] vs. 101 [81-123], NS, respectively; % uninjured hemisphere, median [range]). The addition of mild or moderate hypoxemia did not increase contusion volume. TUNEL-positive neurons were seen in ipsilateral cortex and dentate gyrus at 6, 24, and 72 h after trauma, and in ipsilateral CA3 hippocampal neurons and thalamus at 24 and 72 h. Moderate hypoxemia augments CA3 neuronal death and early motor functional deficits after CCI. The pattern of DNA fragmentation in selectively vulnerable neurons suggests that apoptosis may play a role in the delayed neuronal death seen after TBI.

Expression of endothelial adhesion molecules and recruitment of neutrophils after traumatic brain injury in rats

Traumatic brain injury (TBI) is often accompanied by an acute inflammatory reaction mediated initially by neutrophils. Adhesion molecules expressed on vascular endothelium are requisite elements during recruitment of leukocytes at sites of inflammation. In a rat model of TBI the induction and persistent expression of E-selectin (CD62E) on cerebrovascular endothelium ipsilateral, but not contralateral, to the site of contusion was demonstrated (P < 0.05 at 4 and 48 h posttrauma). In addition, these studies confirmed up-regulation and prolonged expression of ICAM-1 (CD54) on endothelium in the traumatized hemisphere (P < 0.05 at 4, 24, 48, and 72 h posttrauma). It is of interest that increased expression of CD54 was noted on blood vessels in the contralateral, non-traumatized hemisphere 48 h posttrauma. Expression of a third endothelial adhesion molecule, PECAM-1 (CD31), was unchanged following trauma. Administration of a murine monoclonal antibody (TM-8) that inhibits the adhesive function of CD54 blocked a significant portion (37.9%) of neutrophil recruitment 24 h posttrauma (P = 0.04). Employing immunocytochemistry and a monoclonal antibody specific for rat neutrophils (RP-3), peak infiltration of neutrophils was shown to occur 48 h after trauma. In contrast to emigration of neutrophils from blood vessels within the contusion, however, entry of neutrophils occurred from the surrounding leptomeninges and choroidal vessels. These studies demonstrate the relevance of CD54 (ICAM-1) in recruitment of neutrophils following TBI. However, the majority of neutrophil influx relies on endothelial adhesion molecules other than CD54. Because emigration of neutrophils was shown to occur predominantly from vessels within the leptomeninges and choroid plexus, intrathecal delivery of agents that inhibit the adhesive interactions between neutrophils, endothelial CD54, and other endothelial adhesion molecules to be defined may offer a novel form of therapy to prevent the acute inflammatory response that follows TBI.

Cerebrospinal fluid and plasma nitrite and nitrate concentrations after head injury in humans

OBJECTIVES

To measure cerebrospinal fluid and plasma nitrite and nitrate concentrations as indicators of nitric oxide production in adults after severe closed-head injury. To determine if there is an association between cerebrospinal fluid and plasma nitrite and nitrate concentrations, and cerebral blood flow, arterio-jugular oxygen content difference, injury severity, and outcome after severe closed-head injury.

DESIGN

A prospective, clinical study.

SETTING

Multidisciplinary intensive care unit.

PATIENTS

Fifteen comatose (Glasgow Coma Scale score of < or = 7) adult patients with severe closed-head injury were studied during the prospective, randomized evaluation of the effect of moderate hypothermia (32 degrees C for 24 hrs) on neurologic outcome after closed-head injury. Seven patients were in the hypothermic group and eight patients were in the normothermic treatment group.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were examined sequentially, every 12 hrs for 2 days. Intraventricular cerebrospinal fluid was assayed for nitrite and nitrate concentrations. Cerebral blood flow was measured by the 133xenon intravenous method. Simultaneous blood samples were obtained for measurements of arterio-jugular oxygen content difference and plasma nitrite and nitrate concentrations. Cerebral metabolic rate for oxygen was calculated. Cerebrospinal fluid nitrite and nitrate concentrations were highest at 30 to 42 hrs vs. 6 to 18, 18 to 30, and 42 to 54 hrs (26.4 +/- 3.3 vs. 17.3 +/- 2.1, 20.0 +/- 2.2, and 18.8 +/- 2.4 microM, respectively, p < .05). There was no difference over time in plasma nitrite and nitrate concentrations. Cerebral blood flow was increased and arterio-jugular oxygen content difference was reduced at 18 to 30, 30 to 42, and 42 to 54 hrs vs. 6 to 18 hrs (p < .05). At 30 to 42 hrs, cerebrospinal fluid nitrite and nitrate concentrations were 80% higher in patients who died vs. survivors (36.4 +/- 3.2 vs. 20.2 +/- 3.6, p < .05). Using a generalized, multivariate, linear regression model, both plasma nitrite and nitrate concentrations and injury Severity Score independently predicted cerebrospinal fluid nitrite and nitrate concentrations (p < .00001 and p = .0053, respectively). Cerebral blood flow and arterio-jugular oxygen content difference were not associated with cerebrospinal fluid or plasma nitrite and nitrate concentrations using this model. Cerebrospinal fluid nitrite and nitrate concentrations were increased over time in hypothermic vs. normothermic patients. But, where this difference occurred could not be determined by multiple comparisons (p = .03). The hypothermic patients had lower admission Glasgow Coma Scale scores than normothermic patients (p = .04) and tended to have higher injury Severity Scores (p = .09).

CONCLUSIONS

Increases in cerebrospinal fluid nitrite and nitrate concentrations peaked at 30 to 42 hrs after severe closed-head injury. This increase in cerebrospinal fluid nitrite and nitrate concentrations was greater in nonsurvivors. Also, cerebrospinal fluid and plasma nitrite and nitrate concentrations were associated with injury Severity Score, suggesting that increased nitric oxide production in the brain is associated with injury severity and death. Hypothermia did not prevent the increase in cerebrospinal fluid nitrite and nitrate concentrations. Further study is required to determine the source of this increase in cerebrospinal fluid nitrite and nitrate concentrations and to further define the relationship to outcome and the effect of hypothermia on this process.