Utility of Abdominal Computed Tomography in Geriatric Patients on Warfarin with a Fall from Standing.

CONTEXT: Geriatric head trauma resulting from falls has been extensively studied both in the presence and absence of blood thinners. In this population, however, the prevalence and extent of abdominal injury resulting from falls are much less defined. AIM: We aim to evaluate the utility of abdominal computed tomography (CT) imaging in geriatric patients on Warfarin with a recent history of fall. SETTING AND DESIGN: A retrospective analysis was completed of consecutive geriatric patients who presented to a Level 1 Trauma Center emergency department after fall from standing while taking Warfarin. METHODS: Inclusion criteria included age 65 years or older and fall while taking Warfarin. Incomplete medical records were excluded from the study. Data collection included the type of anticoagulant medications, demographics, physical examination, laboratories, CT/X-ray findings if ordered, and final diagnosis on admission. Categorical variables were examined using Pearson's Chi-square where appropriate (expected frequency >5), or Fisher's Exact test. Continuous variables were examined using nonparametric Wilcoxon rank tests. RESULTS: Eight hundred and sixty-three charts were reviewed. One hundred and thirty-one subjects met inclusion criteria. Mean age was 83 years. Nearly 39.6% of patients were male. A total of 48 patients had abdominal CT imaging. Seven of the 131 patients (5.3%) had an abdominal injury. Abdominal tenderness was predictive of injury, with 4 of 7 cases with abdominal injury demonstrating abdominal tenderness versus only 10 of 124 cases without abdominal injury demonstrating tenderness (P = 0.003). Abdominal CTs were ordered in 11 of 19 cases of patients that exhibited head trauma yet none of these patients were shown to have sustained abdominal trauma (P = 0.08). There was no association between international normalized ratio level and presence of abdominal injury (P = 0.99). CONCLUSIONS: A small percentage of elderly fall patients on Warfarin have a significant abdominal injury. Anticoagulated geriatric patients are sometimes subjected to abdominal scans liberally without supporting physical examination findings such as abdominal tenderness or presence of a distracting injury. Specifically, the utility of abdominal CT is questionable in isolated head injury patients. Further, taking Warfarin or other anticoagulant medications do not seem to increase the risk of intraabdominal injury.

Reduction of brain edema and expression of aquaporins with acute ethanol treatment after traumatic brain injury.

OBJECT: Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema by allowing excessive water passage through aquaporin (AQP) proteins. To establish the potential neuroprotective properties of ethanol as a post-TBI therapy, in the present study the authors determined the effect of ethanol on brain edema, AQP expression, and functional outcomes in a post-TBI setting. METHODS: Adult male Sprague-Dawley rats weighing between 425 and 475 g received a closed head TBI in which Maramarou's impact-acceleration method was used. Animals were given a subsequent intraperitoneal injection of 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI and were killed 24 hours after TBI. Brains were subsequently examined for edema along with AQP mRNA and protein expression. Additional animals treated with either 0.5 g/kg or 1.5 g/kg ethanol at 60 minutes post-TBI were designated for cognitive and motor testing for 3 weeks. RESULTS: Ethanol administration post-TBI led to significantly (p < 0.05) lower levels of brain edema as measured by brain water content. This downregulation in brain edema was associated with significantly (p < 0.05) reduced levels of AQP mRNA and protein expression as compared with TBI without treatment. These findings concur with cognitive studies in which ethanol-treated animals exhibited significantly (p < 0.05) faster radial maze completion times. Motor behavioral testing additionally demonstrated significant (p < 0.05) beneficial effects of ethanol, with treated animals displaying improved motor coordination when compared with untreated animals. CONCLUSIONS: The present findings suggest that acute ethanol administration after a TBI decreases AQP expression, which may lead to reduced cerebral edema. Ethanol-treated animals additionally showed improved cognitive and motor outcomes compared with untreated animals.

Neuronal damage and functional deficits are ameliorated by inhibition of aquaporin and HIF1α after traumatic brain injury (TBI).

The present study, using a rodent model of closed-head diffuse traumatic brain injury (TBI), investigated the role of dysregulated aquaporins (AQP) 4 and 9, as well as hypoxia inducible factor -1α(HIF-1α) on brain edema formation, neuronal injury, and functional deficits. TBI was induced in adult (400-425 g), male Sprague-Dawley rats using a modified Marmarou's head impact-acceleration device (450 g weight dropped from 2m height). Animals in each treatment group were administered intravenous anti-AQP4 or -AQP9 antibodies or 2-Methoxyestradiol (2ME2, an inhibitor of HIF-1α) 30 min after injury. At 24h post-TBI, animals (n=6 each group) were sacrificed to examine the extent of brain edema by water content, as well as protein expression of AQP and HIF-1α by Western immune-blotting. At 48-hours post-TBI, neuronal injury (n=8 each group) was assessed by FluoroJade (FJ) histochemistry. Spatial learning and memory deficits were evaluated by radial arm maze (n=8 each group) up to 21 days post-TBI. Compared to non-injured controls, significant (p<0.05) increases in the expression of AQP4 and -9 were detected in the brains of injured animals. In addition, significant (p<0.05) brain edema after TBI was associated with increases (p <0.05) both in neuronal injury (FJ labeling) and neurobehavioral deficits. Selective inhibition of either AQP4 or -9, or HIF-1α significantly (p<0.05) decreased the expression of the proteins. In addition, inhibition of the AQPs and HIF-1α significantly (p<0.05) ameliorated brain edema, as well as the number of injured neurons in cortical layers II/III and V/VI, striatum and hippocampal regions CA1/CA3. Finally, compared to the non-treated TBI animals, AQP or HIF-1α inhibition significantly (p<0.01) improved neurobehavioral outcomes after TBI. Taken together, the present data supports a causal relation between HIF-AQP mediated cerebral edema, secondary neuronal injury, and tertiary behavioral deficits post-TBI. The data further suggests that upstream modulation of the molecular patho-trajectory effectively ameliorates both neuronal injury and behavioral deficits post-TBI.

Glycerol accumulation in edema formation following diffuse traumatic brain injury.

Traumatic brain injury (TBI) induces brain edema via water and glycerol transport channels, called aquaporins (AQPs). The passage of glycerol across brain cellular compartments has been shown during edema. Using a modified impact/head acceleration rodent model of diffuse TBI, we assessed the role of hypoxia inducible factor (HIF)-1alpha in regulating AQP9 expression and glycerol accumulation during the edema formation. Adult (400-425 g) male Sprague-Dawley rats received a closed head injury with a weight drop (450 g, 2-m height) and were allowed to survive up to 48 hours. Some rat groups were administered 2-methoxyestradiol (2ME2, a HIF-1alpha inhibitor) 30 minutes after injury and were euthanized at 4 and 24 hours after injury. Brain edema was measured directly by water content, and glycerol concentration was determined by the Cayman Glycerol Assay. HIF-1alpha and AQP9 protein levels were assessed by Western immunoblotting. This study demonstrated a significant (P<0·05) increase in brain water content at 4-48 hours following impact. Cerebral glycerol was significantly (P<0.05) up-regulated at as early as 1 hour and remained at high levels for up to 48 hours. Similarly, significant (P<0.05) increases in HIF-1alpha and AQP9 protein levels were found at 1 hour and up to 48 hours after injury. Compared to untreated but injured rats, inhibition of HIF-1alpha by 2ME2 significantly (P<0.05) reduced the TBI-induced AQP9 up-regulation. This reduction was temporally associated with significant (P<0.05) decreases in both edema and glycerol accumulation. The data suggested an associated induction of HIF-1alpha, AQP9, and extracellular glycerol accumulation in edema formation following diffuse TBI. The implication of HIF-1alpha and AQP9 underlying TBI-induced edema formation offers possibilities for novel TBI therapies.

Endothelin receptors A and B are expressed in distinct cellular compartments of rat hippocampus following global ischemia: an immunocytochemical study.

OBJECTIVES: The syntheses of endothelin receptors A and B were previously shown to be upregulated in rat dorsal hippocampus after traumatic brain injury. Here we characterize endothelin receptor A and endothelin receptor B cellular distribution in hippocampus after permanent global brain ischemia and their possible association to nerve cell injury. METHODS: Twenty-minute global ischemia was induced using the Pulsinelli's four-vessel occlusion in conjunction with systemic hypovolemia in male rats. Endothelin receptor A and endothelin receptor B immunoreactivities from sham-operated and ischemic rats were assessed qualitatively in dentate gyrus, Cornu Ammonis, and hilus regions of the hippocampus. Quantitative immunoreactivity measurements were also obtained by optical densitometry. RESULTS: In sham-operated control hippocampus, endothelin receptor A immunoreactivity was absent in nerve cell bodies but strongly expressed in the mossy fiber pathway (axons of dentate gyrus granule cells). After ischemia endothelin receptor A immunoreactivity in the same regions was reduced by 40-50% from control. In contrast, endothelin receptor B immunoreactivity in control hippocampus was widely distributed in pyramidal neurons, granule cells and glial cells, this immunoreactivity increasing by approximately 25-30% after ischemia. DISCUSSION: Endothelin receptor A's marked decrease in mossy fibers after ischemia may contribute to glutamate release from mossy fiber terminals, thus enhancing excitotoxic effects on their Cornu Ammonis synaptic targets. Additionally, endothelin receptor B increased expression in neurons and glia could be related to a more generalized activation of survival mechanisms involving elements of the neurovascular unit.

Endothelin receptor A antagonism reduces the extent of diffuse axonal injury in a rodent model of traumatic brain injury.

OBJECTIVES: While endothelin-1 and its receptors have traditionally been associated with mediating vasoreactivity, we have recently shown that the vast majority of endothelin receptor A expression following traumatic brain injury is localized within the neuron. While it has been suggested that endothelin receptor A plays a role in influencing neuronal integrity, the significance of neuronally expressed endothelin receptor A remains unclear. One report suggests that endothelin-1 signaling mediates diffuse axonal injury. Therefore, this work sought to determine whether treatment with BQ-123, a selective endothelin receptor A antagonist, diminishes the extent of diffuse axonal injury following trauma. METHODS: A total of 12 male Sprague-Dawley rats (350-400 g) were used in this study. Two groups (n = 6 per group) were generated as follows: sham operation and traumatic brain injury+1·0 mg/kg BQ-123 delivered intravenously 30 minutes prior to the injury. Trauma was induced using a weight acceleration impact device. Animals were terminated 24 or 48 hours after trauma, and a series of six coronal sections through the entire anterior-posterior extent of the corpus callosum were selected from each brain for quantification of diffuse axonal injury by beta-amyloid precursor protein immunostaining. RESULTS: Our data indicated that animals treated with BQ-123 30 minutes prior to trauma showed a significant reduction in diffuse axonal injury in corpus callosum at both 24 and 48 hours post-injury. CONCLUSION: The results show that endothelin receptor A antagonism reduced the extent of diffuse axonal injury, demonstrating a potential influence of the endothelin system on the intra-axonal cascade of molecular events underlying diffuse axonal injury.

Differential effects of endothelin receptor A and B antagonism on behavioral outcome following traumatic brain injury.

OBJECTIVES: Previously we have reported that endothelin receptor A and B antagonists elicit differential effects on cerebral blood flow and cellular damage. In summary, endothelin receptor A antagonists restore microcirculation and diminish cellular damage after injury, while endothelin receptor B antagonists had no effect on either parameter. However, what is not known is the effect of either antagonist on behavioral outcome. Therefore, this work was designed to test the effects of endothelin receptor A and B antagonism on behavioral outcome following traumatic brain injury (TBI). METHODS: A total of 48 male Sprague-Dawley rats (400-450 g) were used in this study. Four groups (n = 12 per group) were generated as follows: sham operation, trauma+vehicle (0·9% saline), trauma+40 nmol BQ-123 (a selective endothelin receptor A antagonist) and trauma +20 nmol BQ-788 (a selective endothelin receptor B antagonist). All treatments were delivered via intracerebroventricular injection. Trauma was induced using a weight acceleration impact device. Twenty-four hours post-injection animals were tested for 21 days on a radial arm maze task to determine cognitive outcome. RESULTS: Our data indicated that endothelin receptor A antagonism significantly reduced the extent of behavioral deficits following TBI while endothelin receptor B and vehicle injection had no effect. CONCLUSION: The results suggest that endothelin receptor A, but not endothelin receptor B, antagonism improves behavioral outcome following TBI. Furthermore, these data provide a functional correlate to previously published findings in our laboratory showing that endothelin receptor A antagonism improves both blood flow and cellular outcome following TBI. In a broader sense, this work demonstrates that hypoperfusion following TBI likely contributes to poor outcome following head injury.

Clazosentan, a novel endothelin A antagonist, improves cerebral blood flow and behavior after traumatic brain injury.

OBJECTIVES: The purpose of this study was to test the efficacy of a novel endothelin receptor A antagonist on blood flow and behavioral outcome given 30 minutes following traumatic brain injury. METHODS: Male Sprague-Dawley rats (400-450 g) were used in this study. All animals were scanned for initial blood flow using arterial spin labeling magnetic resonance imaging (n = 72 total). Half were subjected to traumatic brain injury using a weight acceleration impact device (n = 36 total). Sham operated animals were used as control (n = 36 total). Thirty minutes following traumatic brain injury, animals were given one intravenous injection of vehicle (0·9% saline) or 1·0 mg/kg clazosentan, a novel endothelin receptor A antagonist, for a total of four groups. At 4, 24, and 48 hours post-traumatic brain injury, blood flow determination continued. On the second day post-traumatic brain injury/sham operation, behavioral testing commenced using a radial arm maze to assess cognitive function. RESULTS: Our results indicate that 1·0 mg/kg clazosentan was effective in ameliorating hypoperfusion seen after traumatic brain injury. Saline had no effect. Furthermore, clazosentan treatment was effective in significantly improving behavioral outcome following traumatic brain injury. CONCLUSION: Collectively, these results indicate that clazosentan, given at 30 minutes post-traumatic brain injury, is effective in improving outcome following injury.

The role of hypoxia-inducible factor-1α, aquaporin-4, and matrix metalloproteinase-9 in blood-brain barrier disruption and brain edema after traumatic brain injury.

OBJECT: The present study investigated the role of hypoxia-inducible factor-1α (HIF-1α), aquaporin-4 (AQP-4), and matrix metalloproteinase-9 (MMP-9) in blood-brain barrier (BBB) permeability alterations and brain edema formation in a rodent traumatic brain injury (TBI) model. METHODS: The brains of adult male Sprague-Dawley rats (400-425 g) were injured using the Marmarou closed-head force impact model. Anti-AQP-4 antibody, minocycline (an inhibitor of MMP-9), or 2-methoxyestradiol (2ME2, an inhibitor of HIF-1α), was administered intravenously 30 minutes after injury. The rats were killed 24 hours after injury and their brains were examined for protein expression, BBB permeability, and brain edema. Expression of HIF-1α, AQP-4, and MMP-9 as well as expression of the vascular basal lamina protein (laminin) and tight junction proteins (zona occludens-1 and occludin) was determined by Western blotting. Blood-brain barrier disruption was assessed by FITC-dextran extravasation, and brain edema was measured by the brain water content. RESULTS: Significant (p < 0.05) edema and BBB extravasations were observed following TBI induction. Compared with sham-operated controls, the injured animals were found to have significantly (p < 0.05) enhanced expression of HIF-1α, AQP-4, and MMP-9, in addition to reduced amounts (p < 0.05) of laminin and tight junction proteins. Edema was significantly (p < 0.01) decreased after inhibition of AQP-4, MMP-9, or HIF-1α. While BBB permeability was significantly (p < 0.01) ameliorated after inhibition of either HIF-1α or MMP-9, it was not affected following inhibition of AQP-4. Inhibition of MMP reversed the loss of laminin (p < 0.01). Finally, while inhibition of HIF-1α significantly (p < 0.05) suppressed the expression of AQP-4 and MMP-9, such inhibition significantly (p < 0.05) increased the expression of laminin and tight junction proteins. CONCLUSIONS: The data support the notion that HIF-1α plays a role in brain edema formation and BBB disruption via a molecular pathway cascade involving AQP-4 and MMP-9. Pharmacological blockade of this pathway in patients with TBI may provide a novel therapeutic strategy.

Hypoxia-inducible factor-1alpha signaling in aquaporin upregulation after traumatic brain injury.

Previous studies have demonstrated that traumatic brain injury (TBI) causes brain edema via aquaporins (AQPs), the water-transporting proteins. In the present study, we determined the role of hypoxia inducible factor-1alpha (HIF-1alpha), which is a transcription factor in response to physiological hypoxia, in regulating expression of AQP4 and AQP9. Adult male Sprague-Dawley rats (400-425g) received a closed head injury using the Marmarou weight drop model with a 450g weight and survived for 1, 4, 24 and 48h. Some animals were administered 30min after injury with 2-methoxyestradiol (2ME2), a naturally occurring metabolite of estradiol which is known to post-transcriptionally down-regulate HIF-1alpha expression, and sacrificed 4h after injury. Real-time PCR and Western blot were used, respectively, to detect gene and protein expressions of manganese superoxide dismutase (MnSOD, showing hypoxic stress), HIF-1alpha, AQP4, and AQP9. ANOVA analysis demonstrated a significant (p<0.05) increase in gene expression of MnSOD, HIF-1alpha, AQP4, and AQP9, starting at 1h after injury through 48h. Western blot analysis further indicated a significant (p<0.05) increase in protein expression of these molecules at the same time points. Pharmacological inhibition of HIF-1alpha by 2ME2 reduced the up-regulated levels of AQP4 and AQP9 after TBI. The present study suggests that hypoxic conditions determined by MnSOD expression after closed head injury contribute to HIF-1alpha expression. HIF-1alpha, in turn, up-regulates expression of AQP4 and AQP9. These results characterize the pathophysiological mechanisms, and suggest possible therapeutic targets for TBI patients.

Synapse loss regulated by matrix metalloproteinases in traumatic brain injury is associated with hypoxia inducible factor-1alpha expression.

The present study assessed the role of matrix metalloproteinase-2 (MMP-2) and -9 in synapse loss after traumatic brain injury (TBI) and the role of hypoxia inducible factor-1alpha (HIF-1alpha), a transcription factor up-regulated during hypoxia, in the regulation of MMP-2 and -9 expression post-TBI. Adult male Sprague-Dawley rats (n=6 per group, 400 g-425 g) were injured using Marmarou's closed-head acceleration impact model and allowed to survive for 1, 4, 24 and 48 h. In another set of experiments, 30 min after TBI, animals were treated with Minocycline (inhibitor of MMPs), or 2-Methoxyestradiol (2ME2, inhibitor of HIF-1alpha) and sacrificed at 4 h after injury. Relative amounts of synaptophysin, a presynaptic vesicular protein, HIF-1alpha, as well as MMP-2 and -9 were assessed by real-time PCR and Western blotting. Activity levels of MMP-2 and -9 were determined by zymography. Synaptophysin expression was significantly (p<0.05) decreased at 1 h through 48 h after TBI. A significant increase in gene and protein expressions of HIF-1alpha, MMP-2 and -9, as well as enzyme activity of MMP-2 and -9 at the same time points was also detected. Inhibition of either MMPs or HIF-1alpha significantly reversed the TBI-induced decrease in synaptophysin. Inhibition of HIF-1alpha reduced expression of MMP-2 and -9. This study showed an early detection of a correlation between synaptic loss and MMP expression after TBI. The data also supports a role for HIF-1alpha in the MMP regulatory cascade in synapse loss after TBI, suggesting potential targets for reducing loss of synaptic terminals.