Kaspar Keledjian

Glial fibrillary acidic protein is highly correlated with brain injury.

BACKGROUND Glial fibrillary acidic protein (GFAP) is an intermediate filament protein found in the cytoskeleton of astroglia. Recent work has indicated that GFAP may serve as a serum marker of traumatic brain injury (TBI) that is released after central nervous system cell damage. METHODS Serum from 51 critically injured trauma patients was prospectively collected on admission and on hospital day 2. All patients underwent an admission head computed tomography (CT) scan as a part of their clinical evaluation. Patients with facial fractures in the absence of documented TBI and patients with spinal cord injury were excluded. Demographic and outcome data were collected prospectively. Serum GFAP was measured in duplicate using enzyme-linked immunosorbent assay techniques. RESULTS Thirty-nine (76%) of the 51 patients had CT-documented TBI. The study cohort was 72.5% men with a mean age of 43 years and mean Injury Severity Score (ISS) of 30.2. There were no statistically significant demographic differences between the two groups. At admission day, the mean GFAP level in non-TBI patients was 0.07 pg/mL compared with 6.77 pg/mL in TBI patients (p = 0.002). On day 2 the mean GFAP level was 0.02 in non-TBI patients compared with 2.17 in TBI patients (p = 0.003). Using regression analysis to control for age, sex, and ISS, the Head Abbreviated Injury Scale was predictive of the level of GFAP on both days 1 and 2 (p values 0.006 and 0.026, respectively). Although GFAP levels were not predictive of increased hospital length of stay, intensive care unit length of stay, or ventilator days, high GFAP levels on hospital day 2 were predictive of mortality when controlling for age, sex, and ISS (odds ratio 1.45, p value 0.028). The area under the receiver operating characteristic curve for GFAP was 0.90 for day 1 and 0.88 for day 2. A GFAP cutoff point of 1 pg/mL yielded 100% specificity and 50% to 60% sensitivity for TBI. CONCLUSIONS GFAP is a serum marker of TBI, and persistent elevation on day 2 is predictive of increased mortality. Excellent specificity for CT-documented brain injury was found using a cutoff point of 1 pg/mL.

Rodent model of direct cranial blast injury.

Traumatic brain injury resulting from an explosive blast is one of the most serious wounds suffered by warfighters, yet the effects of explosive blast overpressure directly impacting the head are poorly understood. We developed a rodent model of direct cranial blast injury (dcBI), in which a blast overpressure could be delivered exclusively to the head, precluding indirect brain injury via thoracic transmission of the blast wave. We constructed and validated a Cranium Only Blast Injury Apparatus (COBIA) to deliver blast overpressures generated by detonating .22 caliber cartridges of smokeless powder. Blast waveforms generated by COBIA replicated those recorded within armored vehicles penetrated by munitions. Lethal dcBI (LD(50) ∼ 515 kPa) was associated with: (1) apparent brainstem failure, characterized by immediate opisthotonus and apnea leading to cardiac arrest that could not be overcome by cardiopulmonary resuscitation; (2) widespread subarachnoid hemorrhages without cortical contusions or intracerebral or intraventricular hemorrhages; and (3) no pulmonary abnormalities. Sub-lethal dcBI was associated with: (1) apnea lasting up to 15 sec, with transient abnormalities in oxygen saturation; (2) very few delayed deaths; (3) subarachnoid hemorrhages, especially in the path of the blast wave; (4) abnormal immunolabeling for IgG, cleaved caspase-3, and β-amyloid precursor protein (β-APP), and staining for Fluoro-Jade C, all in deep brain regions away from the subarachnoid hemorrhages, but in the path of the blast wave; and (5) abnormalities on the accelerating Rotarod that persisted for the 1 week period of observation. We conclude that exposure of the head alone to severe explosive blast predisposes to significant neurological dysfunction.

Novel Model of Frontal Impact Closed Head Injury in the Rat

Frontal impact, closed head trauma is a frequent cause of traumatic brain injury (TBI) in motor vehicle and sports accidents. Diffuse axonal injury (DAI) is common in humans and experimental animals, and results from shearing forces that develop within the anisotropic brain. Because the specific anisotropic properties of the brain are axis-dependent, the anatomical site where force is applied as well as the resultant acceleration, be it linear, rotational, or some combination, are important determinants of the resulting pattern of brain injury. Available rodent models of closed head injury do not reproduce the frontal impact commonly encountered in humans. Here we describe a new rat model of closed head injury that is a modification of the impact-acceleration model of Marmarou. In our model (the Maryland model), the impact force is applied to the anterior part of the cranium and produces TBI by causing anterior-posterior plus sagittal rotational acceleration of the brain inside the intact cranium. Skull fractures, prolonged apnea, and mortality were absent. The animals exhibited petechial hemorrhages, DAI marked by a bead-like pattern of beta-amyloid precursor protein (beta-APP) in damaged axons, and widespread upregulation of beta-APP in neurons, with regions affected including the orbitofrontal cortex (coup), corpus callosum, caudate, putamen, thalamus, cerebellum, and brainstem. Activated caspase-3 was prominent in hippocampal neurons and Purkinje cells at the grey-white matter junction of the cerebellum. Neurobehavioral dysfunction, manifesting as reduced spontaneous exploration, lasted more than 1 week. We conclude that the Maryland model produces diffuse injuries that may be relevant to human brain injury.

Doxazosin inhibits human vascular endothelial cell adhesion, migration, and invasion.

The quinazoline‐derived α1‐adrenoceptor antagonists, doxazosin and terazosin have been recently shown to induce an anoikis effect in human prostate cancer cells and to suppress prostate tumor vascularity in clinical specimens [Keledjian and Kyprianou, 2003 ]. This study sought to examine the ability of doxazosin to affect the growth of human vascular endothelial cells and to modulate vascular endothelial growth factor (VEGF)‐mediated angiogenesis. Human umbilical vein endothelial cells (HUVECs) were used as an in vitro model to determine the effect of doxazosin on cell growth, apoptosis, adhesion, migration, and angiogenic response of endothelial cells. The effect of doxazosin on cell viability and apoptosis induction of human endothelial cells, was evaluated on the basis of trypan blue and Hoechst 33342 staining, respectively. Doxazosin antagonized the VEGF‐mediated angiogenic response of HUVEC cells, by abrogating cell adhesion to fibronectin and collagen‐coated surfaces and inhibiting cell migration, via a potential downregulation of VEGF expression. Furthermore there was a significant suppression of in vitro angiogenesis by doxazosin on the basis of VEGF‐mediated endothelial tube formation (P < 0.01). Fibroblast growth factor‐2 (FGF‐2) significantly enhanced HUVEC cell tube formation (P < 0.01) and this effect was suppressed by doxazosin. These findings provide new insight into the ability of doxazosin to suppress the growth and angiogenic response of human endothelial cells by interfering with VEGF and FGF‐2 action. This evidence may have potential therapeutic significance in using this quinazoline‐based compound as an antiangiogenic agent for the treatment of advanced prostate cancer.

Relationship of Serum and Cerebrospinal Fluid Biomarkers With Intracranial Hypertension and Cerebral Hypoperfusion After Severe Traumatic Brain Injury

BACKGROUND There is little that can be done to treat or reverse the primary injury that occurs at the time of a traumatic brain injury (TBI). Initial management of the patient with severe TBI focuses on prevention of subsequent secondary insults, namely, intracranial hypertension (ICH) and cerebral hypoperfusion (CH). Currently, there is no reliable way to predict which patients will develop ICH and CH other than clinical acumen; therefore, indicators of impending secondary intracranial insults may be useful in predicting these events and allowing for prevention and early intervention. This study was undertaken to investigate the relationship of cytokine levels with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in patients with severe TBI. METHODS Patients at the R Adams Cowley Shock Trauma Center were prospectively enrolled for a 6-month period. Inclusion criteria were older than 17 years, admission within the first 6 hours after injury, Glasgow Coma Scale<9 on admission, and placement of a clinically indicated ICP monitor. Serum and cerebrospinal fluid, when available, were collected on admission and twice daily for 7 days. Cytokine levels of interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor (TNF)-α were analyzed by multiplex bead array assays. Hourly values for ICP and CPP were recorded, and means, minimum (for CPP) or maximum (for ICP) values, percentage time ICP>20 mm Hg (%ICP20) and CPP<60 mm Hg (%CPP60), and cumulative Pressure Times Time Dose (PTD; mm Hg·h) for ICP>20 mm Hg (PTD ICP20) and CPP<60 mm Hg (PTD CPP60) were compared with the serum and cerebrospinal fluid levels that were drawn before 12-hour time periods (PRE) and after 12-hour time periods (POST) of monitoring. RESULTS Twenty-four patients were enrolled. In-hospital mortality was 12.5%, and good functional outcome was noted in 58%. Two hundred and seventy-five serum samples were taken and analyzed. IL-6 levels in the serum were found in the highest concentration of the cytokines measured. PTD ICP20 and PTD CPP60 were moderately correlated with increased PRE IL-8 levels (r=0.34, p<0.001; r=0.53, p<0.001). PTD ICP20 was also correlated with PRE TNF-α levels (r=0.27, p<0.001) as was PTD CPP60 (r=0.25, p<0.001). POST IL-8 levels were found to be correlated with PTD ICP20 (r=0.46, p<0.001) and PTD CPP60 (r=0.54, p<0.001). POST TNF-α was associated with PTD ICP20 (r=0.45, p<0.001). PTD CPP60 was also moderately correlated with POST TNF-α levels (r=0.26, p<0.001). When comparing patients with good versus poor outcome, median daily serum IL-8 levels were associated with poor outcome. CONCLUSIONS IL-8 and, to a lesser extent, TNF-α demonstrated the most promise in this study to be candidate serum markers of impending ICH and CH. The clinical relevance of this is the suggestion that we may be able to predict impending secondary insults after TBI before the clinical manifestation of these events. Given the known morbidity of ICH and CH, early intervention and prevention may have a significant impact on outcome. This becomes even more important when decisions must be made about timing of interventions. Increased levels of IL-8 and TNF-α in the serum during episodes of ICH and CH imply there are significant systemic effects of these events. These serum biomarkers are promising as diagnostic targets. In addition, further study of the precise role of these molecules may have significant implications for inflammatory system manipulation in the management of severe TBI.

Induced TRPC1 expression sensitizes intestinal epithelial cells to apoptosis by inhibiting NF-κB activation through Ca2+ influx

Apoptosis occurs within crypts and at the intestinal luminal surface and plays a critical role in mucosal homoeostasis. NF-kappaB (nuclear factor-kappaB) is the central regulator of the transcription of genes involved in apoptosis, and its activity is highly regulated in the intestinal mucosa. We have recently demonstrated that TRPC1 (transient receptor potential canonical-1) is expressed in IECs (intestinal epithelial cells) and functions as a Ca2+ permeable channel activated by Ca2+ store depletion. The present study tests the hypothesis that TRPC1 channels are implicated in the regulation of apoptosis by inhibiting NF-kappaB through the induction of TRPC1-mediated Ca2+ influx in the IEC-6 line. The expression of TRPC1 induced by stable transfection of IEC-6 cells with the wild-type TRPC1 gene (IEC-TRPC1 cells) increased Ca2+ influx after Ca2+ store depletion and repressed NF-kappaB transactivation, which was associated with an increase in susceptibility to apoptosis induced by exposure to TNFalpha (tumour necrosis factor-alpha) plus CHX (cycloheximide) (TNF-alpha/CHX), or STS (staurosporine). By contrast, the induction of endogenous NF-kappaB activity, by the depletion of cellular polyamines, promoted resistance to apoptosis, which was prevented by the ectopic expression of the IkappaBalpha super-repressor. Furthermore, inhibition of TRPC1 expression by transfection with siRNA (small interfering RNA) targeting TRPC1 (siTRPC1) decreased Ca2+ influx, increased NF-kappaB transactivation, and prevented the increased susceptibility of IEC-TRPC1 cells to apoptosis. Decreasing Ca2+ influx by exposure to a Ca2+-free medium also induced NF-kappaB activity and blocked the increased susceptibility to apoptosis of stable IEC-TRPC1 cells. These results indicate that induced TRPC1 expression sensitizes IECs to apoptosis by inhibiting NF-kappaB activity as a result of the stimulation of Ca2+ influx.

Determination of efficacy of novel modified chitosan sponge dressing in a lethal arterial injury model in swine

BACKGROUND: Chitosan is a functional biopolymer that has been widely used as a hemostat. Recently, its efficacy has been questioned due to clinical failures as a result of poor adhesiveness. The purpose of this study was to compare, in a severe groin injury model in swine, the hemostatic properties of an unmodified standard chitosan sponge with standard gauze dressing and a novel hydrophobically modified (hm) chitosan sponge. Previous studies have demonstrated that hm-chitosan provides greatly enhanced cellular adhesion and hemostatic effect via noncovalent insertion of hydrophobic pendant groups into cell membranes. METHODS: Twenty-four Yorkshire swine were randomized to receive hm-chitosan (n = 8), unmodified chitosan (n = 8), or standard Accu-Sorb gauze dressing (n = 8) for hemostatic control. A complex groin injury involving arterial puncture (4.4-mm punch) of the femoral artery was made after splenectomy. After 30 seconds of uncontrolled hemorrhage, the randomized dressing was applied and compression was held for 3 minutes. Fluid resuscitation was initiated to achieve and maintain the baseline mean arterial pressure and the wound was inspected for bleeding. Failure of hemostasis was defined as pooling of blood outside the wound. Animals were then monitored for 180 minutes and surviving animals were killed. RESULTS: Blood loss before treatment was similar between groups (p < 0.1). Compared with the hm-chitosan sponge group, which had no failures, the unmodified chitosan sponge group and the standard gauze group each had eight failures over the 180-minute observation period. For the unmodified chitosan sponge failures, six of which provided initial hemostasis, secondary rebleeding was observed 44 minutes ± 28 minutes after application. Standard gauze provided no initial hemostasis after the 3-minute compression interval. CONCLUSIONS: Hm-chitosan is superior to unmodified chitosan sponges (p < 0.001) or standard gauze for controlling bleeding from a lethal arterial injury. The hm-chitosan technology may provide an advantage over native chitosan-based dressings for control of active hemorrhage.

Exposure of the Thorax to a Sublethal Blast Wave Causes a Hydrodynamic Pulse That Leads to Perivenular Inflammation in the Brain

Traumatic brain injury (TBI) caused by an explosive blast (blast-TBI) is postulated to result, in part, from transvascular transmission to the brain of a hydrodynamic pulse (a.k.a., volumetric blood surge, ballistic pressure wave, hydrostatic shock, or hydraulic shock) induced in major intrathoracic blood vessels. This mechanism of blast-TBI has not been demonstrated directly. We tested the hypothesis that a blast wave impacting the thorax would induce a hydrodynamic pulse that would cause pathological changes in the brain. We constructed a Thorax-Only Blast Injury Apparatus (TOBIA) and a Jugular-Only Blast Injury Apparatus (JOBIA). TOBIA delivered a collimated blast wave to the right lateral thorax of a rat, precluding direct impact on the cranium. JOBIA delivered a blast wave to the fluid-filled port of an extracorporeal intravenous infusion device whose catheter was inserted retrograde into the jugular vein, precluding lung injury. Long Evans rats were subjected to sublethal injury by TOBIA or JOBIA. Blast injury induced by TOBIA was characterized by apnea and diffuse bilateral hemorrhagic injury to the lungs associated with a transient reduction in pulse oximetry signals. Immunolabeling 24 h after injury by TOBIA showed up-regulation of tumor necrosis factor alpha, ED-1, sulfonylurea receptor 1 (Sur1), and glial fibrillary acidic protein in veins or perivenular tissues and microvessels throughout the brain. The perivenular inflammatory effects induced by TOBIA were prevented by ligating the jugular vein and were reproduced using JOBIA. We conclude that blast injury to the thorax leads to perivenular inflammation, Sur1 up-regulation, and reactive astrocytosis resulting from the induction of a hydrodynamic pulse in the vasculature.

Use of a modified chitosan dressing in a hypothermic coagulopathic grade V liver injury model.

BACKGROUND Exsanguination from hepatic trauma is exacerbated by the lethal triad of acidosis, coagulopathy, and hypothermia. We evaluated the application of a modified chitosan dressing in a hypothermic coagulopathic model of grade V liver injury. METHODS Subject swine underwent induced hypothermic coagulopathy followed by standardized grade V liver injuries. A modified chitosan dressing was applied and compared with standard packing. RESULTS Pretreatment temperature, activated clotting time, and blood loss were similar between groups. Post treatment blood loss was significantly less and resuscitation mean arterial pressure were significantly greater in the modified chitosan group (P < .0001 and P < .018, respectively). Mean fluid resuscitative volume was significantly less in the modified chitosan group (P < .0056). Hemostasis was achieved on average 5.2 minutes following modified chitosan and never achieved with standard packing. At 1 hour post injury, all treatment animals survived compared with half of controls. CONCLUSIONS Modified chitosan dressings provide simple rapid treatment of life-threatening liver injuries.

Hemostatic Efficacy of Modified Amylopectin Powder in a Lethal Porcine Model of Extremity Arterial Injury

STUDY OBJECTIVE Rapid hemostasis is crucial in controlling severe extremity hemorrhage. Our objective is to evaluate the hemostatic efficacy of a newly modified amylopectin powder in a model of severe extremity arterial hemorrhage. METHODS Anesthetized pigs underwent severe, reproducible femoral artery injuries. Animals were randomized (nonblinded) to either modified amylopectin powder (n=10) or standard gauze application (n=6). Each hemostatic agent was applied through a pool of blood with manual compression for 3-minute intervals until hemostasis was achieved. Fluid resuscitation was infused as necessary to reestablish a mean arterial pressure within at least 80% of the preinjury mean arterial pressure if possible. The primary measured outcome was total blood loss. Secondary endpoints were survival, time to hemostasis, resuscitation mean arterial pressure, and resuscitation volume. RESULTS Pretreatment blood losses were similar in both groups. Median (absolute average deviation of the median) posttreatment blood loss was significantly less in the modified amylopectin powder group than in the gauze group, 275 (108) mL versus 1,312 (171) mL. Resuscitation mean arterial pressure at 180 minutes after injury was 68% of preinjury mean arterial pressure in the modified amylopectin powder group and undetectable in all control animals. Fluid volume required for resuscitation was 1,962 (258) mL in the modified amylopectin powder group and 2,875 (150) mL in the gauze group. Time to hemostasis was 9.0 (2.1) minutes in the modified amylopectin powder group. Hemostasis was not achieved in any animal in the gauze group. Survival was 100% in the modified amylopectin powder group, whereas no animals survived in the gauze group. CONCLUSION Modified amylopectin powder demonstrates the ability to control major vascular bleeding in a lethal arterial injury model during a 3-hour period.