Jeanna Tsenter

Erythropoietin is neuroprotective, improves functional recovery, and reduces neuronal apoptosis and inflammation in a rodent model of experimental closed head injury

Traumatic brain injury (TBI) is a leading cause of morbidity and mortality in young people in industrialized countries. Although various anti‐inflammatory and antiapoptotic modalities have shown neuroprotective effects in experimental models of TBI, to date, no specific pharmacological agent aimed at blocking the progression of secondary brain damage has been approved for clinical use. Erythropoietin (Epo) belongs to the cytokine superfamily and has traditionally been viewed as a hematopoiesis‐regulating hormone. The newly discovered neuroprotective properties of Epo lead us to investigate its effect in TBI in a mouse model of closed head injury. Recombinant human erythropoietin (rhEpo) was injected at 1 and 24 h after TBI, and the effect on recovery of motor and cognitive functions, tissue inflammation, axonal degeneration, and apoptosis was evaluated up to 14 days. Motor deficits were lower, cognitive function was restored faster, and less apoptotic neurons and caspase‐3 expression were found in rhEpo‐treated as compared with vehicle‐treated animals (P<0.05). Axons at the trauma area in rhEpo‐treated mice were relatively well preserved compared with controls (shown by their density; P<0.01). Immunohistochemical analysis revealed a reduced activation of glial cells by staining for GFAP and complement receptor type 3 (CD11b/CD18) in the injured hemisphere of Epo‐ vs. vehicle‐treated animals. We propose that further studies on Epo in TBI should be conducted in order to consider it as a novel therapy for TBI.

Dynamic changes in the recovery after traumatic brain injury in mice: effect of injury severity on T2-weighted MRI abnormalities, and motor and cognitive functions.

Memory and neurobehavioral dysfunctions are among the sequelae of traumatic brain injury (TBI). The Neurological Severity Score (NSS) includes 10 tasks and was previously designed to assess the functional status of mice after TBI. The object recognition task (ORT) measures specific episodic memory and is expressed by the percent time spent by an animal at a novel, unfamiliar object (Discrimination Index [DI]). It is an ideal tool for evaluating cognitive function after TBI. The present study sought to validate the use of the NSS and ORT in severe and mild focal TBI in mice, and to confirm that the spontaneous recovery and the radiological abnormalities, shown by T2-weighted magnetic resonance imaging (MRI), are dependent upon injury severity. Mice were subjected to severe and mild closed head injury (NSS at 1 h 7.52 +/- 0.34 and 4.62 +/- 0.14, respectively). NSS was evaluated for 25 days and showed a decrease by 3.86 +/- 0.26 and 2.54 +/- 0.35 units in the severely and mildly injured mice, respectively. ORT revealed DI in severely injured group of 51.7 +/- 6.15%, (vs approximately 75-80% in uninjured animal) on day 3 and 66.2 +/- 6.81% on day 21. In contrast, the mildly injured mice did not show cognitive impairment throughout the same period. The damage seen by MRI at 24 h after injury, strongly correlated with NSS(1h) (R = 0.87, p < 0.001). We conclude that NSS is a reliable tool for evaluation of neurological damage in head-injured mice, NSS(1h) predicts the motor dysfunction, cognitive damage, and brain-damage characteristics as depicted by T2-weighted MRI. The combined assessment of neurobehavioral and cognitive function along with MRI is most useful in evaluating recovery from injury, especially when testing effectiveness of novel treatments or genetic manipulations.

D-cycloserine improves functional recovery and reinstates long-term potentiation (LTP) in a mouse model of closed head injury

Traumatic brain injury triggers a massive glutamate efflux, activation of NMDA receptor channels, and cell death. Recently, we reported that NMDA receptors in mice are down‐regulated from hours to days following closed head injury (CHI), and treatment with NMDA improved recovery of motor and cognitive functions up to 14 d post‐injury. Here we show that a single injection of a low dose of D‐cycloserine (DCS), a partial NMDA receptor agonist, in CHI mice 24 h post‐injury, resulted in a faster and greater recovery of motor and memory functions as assessed by neurological severity score and object recognition tests, respectively. Moreover, DCS treatment of CHI mice led to a significant improvement of hippocampal long‐term po‐tentiation (LTP) in the CA1 region that was completely blunted in CHI control mice. However, DCS did not improve CHI‐induced impairment in synaptic gluta‐mate release measured by paired pulse facilitation (PPF) ratio in hippocampal CA1 region. Finally, CHI‐induced reduction of brain‐derived neurotrophic factor (BDNF) was fully restored following DCS treatment. Since DCS is in clinical use for other indications, the present study offers a novel approach to treat human brain injury.–Yaka, R., Biegon, A., Grigoriadis, N., Simeonidou, C., Grigoriadis, S., Alexandrovich, A. G., Matzner, H., Schumann, J., Trembovler, V., Tsenter, J., Shohami, E. D‐cycloserine improves functional recovery and reinstates long‐term potentiation (LTP) in a mouse model of closed head injury. FASEB J. 21, 2033–2041 (2007)

Heat Acclimation Increases Hypoxia-Inducible Factor 1α and Erythropoietin Receptor Expression: Implication for Neuroprotection after Closed Head Injury in Mice

Experimental evidence indicates that long-term exposure to moderately high ambient temperature (heat acclimation, HA) mediates cross-tolerance to various types of subsequently applied stress. The transcriptional activator hypoxia-inducible factor 1 (HIF-1) has been implicated in playing a critical role in HA. It also regulates the expression of Erythropoietin (Epo), whose neuroprotective effects have been shown in a variety of brain injuries. The aim of the present study was to examine whether HA exerts a beneficial effect on the outcome of closed head injury (CHI) in mice and to explore the possible involvement of HIF-1 and Epo in this process. Heat acclimated mice and matched normothermic controls were subjected to CHI or sham surgery. Postinjury motor and cognitive parameters of acclimated mice were compared with those of controls. Mice were killed at various time points after injury or sham surgery and brain levels of HIF-1α, the inducible subunit of HIF-1, Epo, and the specific erythropoietin receptor (EpoR) were analyzed by Western immunoblotting. Motor and cognitive functions of acclimated mice were significantly better than those of controls. Heat acclimation was found to induce a significant increase in expression of nuclear HIF-1α and EpoR. The EpoR/Epo ratio was also significantly higher in acclimated mice as compared with controls. Nuclear HIF-1α and EpoR were higher in the acclimated group at 4 h after injury as well. The improved outcome of acclimated mice taken together with the basal and postinjury upregulation of the examined proteins suggests the involvement of this pathway in HA-induced neuroprotection.

Incensole Acetate: A Novel Neuroprotective Agent Isolated from Boswellia Carterii

Boswellia resin has been used as a major anti-inflammatory agent and for the healing of wounds for centuries. Incensole acetate (IA), isolated from this resin, was shown to inhibit the activation of nuclear factor-κB, a key transcription factor in the inflammatory response. We now show that IA inhibits the production of inflammatory mediators in an in vitro model system of C6 glioma and human peripheral monocytes. Given the involvement of postinjury inflammation in the pathophysiology and outcome of traumatic brain injury, we examined the effect of IA on the inflammatory process and on the recovery of neurobehavioral and cognitive functions in a mouse model of closed head injury (CHI). In the brains of post-CHI mice, IA reduced glial activation, inhibited the expression of interleukin-1β, and tumor necrosis factor-α mRNAs, and induced cell death in macrophages at the area of trauma. A mild hypothermic effect was also noted. Subsequently, IA inhibited hippocampal neurodegeneration and exerted a beneficial effect on functional outcome after CHI, indicated by reduced neurological severity scores and improved cognitive ability in an object recognition test. This study attributes the anti-inflammatory activity of Boswellia resin to IA and related cembranoid diterpenes and suggests that they may serve as novel neuroprotective agents.

CD38 Facilitates Recovery from Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. It causes progressive tissue atrophy and consequent neurological dysfunctions. TBI is accompanied by neuroinflammation, a process mediated largely by microglia. CD38 is an ectoenzyme that promotes transmembrane signaling via the synthesis of potent calcium mobilizing agents or via its receptor activity. CD38 is expressed in the brain in various cell types including microglia. In previous studies, we showed that CD38 regulates microglial activation and response to chemokines. In view of the important role of neuroinflammation in TBI and the effects of CD38 on microglial responses, the present study examines the role of CD38 in the recovery of mice from closed head injury (CHI), a model of focal TBI. For this purpose, CD38-deficient and wild-type (WT) mice were subjected to a similar severity of CHI and the effect of the injury on neurobehavioral and cognitive functions was assessed by the Neurological Severity Score (NSS) and the Object Recognition Test, at various time points post-injury. The results show that recovery after CHI (as indicated by the NSS) was significantly lower in CD38-deficient mice than in WT mice and that the object recognition performance after injury was significantly impaired in injured CD38-deficient mice than in WT mice. In addition, we also observed that the amount of activated microglia/macrophages at the injury site was significantly lower in CD38-deficient mice compared with WT mice. Taken together, our findings indicate that CD38 plays a beneficial role in the recovery of mice from CHI and that this effect is mediated, at least in part, via the effect of CD38 on microglia responses.

CuZn-SOD Deficiency, Rather than Overexpression, is Associated with Enhanced Recovery and Attenuated Activation of NF-κB After Brain Trauma in Mice

Superoxide-dismutases (SOD) catalyze O2− conversion to hydrogen peroxide (H2O2) and with other antioxidant enzymes and low molecular weight antioxidants (LMWA) constitute endogenous defense mechanisms. We first assessed the effects of SOD1 levels on outcome after closed head injury (CHI) and later, based on these results, the effects of SOD−/- deficiency on cellular redox homeostasis. Superoxide-dismutase 1-deficient (SOD1−/-) and -overexpressing (transgenic (Tg)) mice and matched wild-type (WT) controls were subjected to CHI and outcome (neurobehavioral and memory functions) was assessed during 14 days. Brain edema, LMWA, and SOD2 activity were measured along with histopathological analysis. Transactivation of nuclear factor-kappa B (NF-κB) was evaluated by electromobility shift assay. Mortality, motor, and cognitive outcome of Tg and WT mice were comparable. Mortality and edema were similar in SOD1−/- and WT mice, yet, unexpectedly, SOD1−/- displayed better neurobehavioral recovery (P < 0.05) at 14 days after CHI. Basal LMWA were higher in the cortex and liver of SOD1−/- mice (P < 0.05) and similar to WT in the cerebellum. Five minutes after CHI, cortical LMWA decreased only in SOD1−/- mice. One week after CHI, SOD2 activity decreased fourfold in WT cortex (P < 0.001), but was preserved in the SOD1−/- . Constitutive NF-κB transactivation was comparably low in SOD1−/- and WT; however, CHI induced a robust NF-κB activation that was absent in SOD1−/- cortices (P > 0.005 versus WT). At the same time, immunohistochemical analysis of brain sections revealed that astrogliosis and neurodegeneration were of lesser severity in SOD1−/- mice. We suggest that SOD1 deficiency impairs H2O2-mediated activation of NF-κB, decreasing death-promoting signals, and leading to better outcome.

Experimental pressure pain in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy).

Research in animals shows that the levels of neuropathic pain expression is genetically associated with a characteristic response profile to sensory stimuli. The aim of the present investigation was to examine if pressure algometry can identify a specific pain sensitivity profile in patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), and to distinguish complex regional pain syndromes from other chronic pain dysfunction syndromes. Pressure pain threshold and pain tolerance measured at the sternum in 17 patients with complex regional pain syndrome, Type I (reflex sympathetic dystrophy), were compared with values obtained in 13 patients suffering from other chronic pain dysfunction syndromes and in a control group of 24 pain-free volunteers. The pressure algometer consisted of a force displacement transducer with a 0.25 cm2 tip connected to a recorder. The rate of force application was 1 kg/0.25 cm2/s. The difference between threshold and tolerance was defined as the pain sensitivity range. Young patients with complex regional pain syndrome (<40 yr) demonstrated a significantly higher mean pain sensitivity range compared with young subjects who had chronic pain or who were pain-free. Mean threshold and tolerance values were significantly lower in patients with complex regional pain syndrome (2.7+/-1.0 kg (mean +/- standard deviation) and 5.4+/-2.0 kg, respectively) and in patients suffering from other chronic pain syndromes (2.6+/-1.1 and 4.6+/-1.7 kg) than in healthy subjects (5.4+/-2.3 and 8.4+/-2.6 kg). Women in the chronic pain group exhibited a significantly lower pressure pain threshold than all other subgroups. Regardless of group, women exhibited lower pressure pain tolerance than men. In conclusion, the study contained herein shows a specific pain sensitivity profile to experimental stimuli behavior in young patients with complex regional pain syndrome expressed by a large pressure pain sensitivity range, at a location away from the painful area. However, one single pressure pain measurement over the sternum is insufficient for differentiation of patients with complex regional pain syndrome from those with chronic pain because of intersubject variation.

Similarities Between the Psychological Profiles of Complex Regional Pain Syndrome and Conversion Disorder Patients

The psychological profile of 17 Complex Regional Pain Syndrome type I (CRPS) and 20 Conversion Disorder (CD) patients were compared, using the Minnesota Multiphasic Personality Inventory (MMPI) and standardized, semistructured psychological interviews. Both groups presented abnormally high somatization scores. Low anxiety scores in both groups indicate that somatization may have served as a defense mechanism to bind anxiety. Depression was apparent in both groups, indicating that psychological distress accompany these syndromes. About one third of the participants in both groups presented comorbid Axis I disorders, mostly depression and PTSD. CRPS patients have traditionally been looked upon as suffering from mainly organic symptoms, whereas CD patients have been labeled as psychiatric patients. These results may indicate the need to reexamine the traditional classifications in respect to disorders that involve “body and mind.”

Cognitive and functional outcomes of terror victims who suffered from traumatic brain injury

Primary objective: To describe the outcomes of terror victims suffered from traumatic brain injury (TBI). Research design: Retrospective chart review of 17 terror and 39 non-terror TBI patients treated in a rehabilitation department during the same period. Methods and procedure: Variables include demographic data, Injury Severity Scale (ISS), length of stay (LOS) and imaging results. ADL was measured using the Functional Independence Measurement (FIM), cognitive and memory functions were measured using the Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) battery and the Rivermead Battery Memory Test (RBMT), respectively. Main outcome and results: Terror TBI patients were significantly younger, had higher ISS score and higher rates of intracerebral haemorrhage (ICH), brain surgery and penetrating brain injuries than the non-terror TBI group. There was no difference in mean LOS, mean FIM values, mean FIM gain and mean cognitive and memory improvement between groups. Terror victims suffered from a higher percentage of post-traumatic epilepsy (35% vs. 10%, p= 0.05), whereas the rate of PTSD and the rate of return to previous occupation were similar between groups. Conclusions: Although TBI terror victims had more severe injury, they gained most of ADL functions and their rehabilitation outcomes were similar to non-terror TBI patients. These favourable results were achieved due to a comprehensive interdisciplinary approach to terror victims and also by national support which allowed an adequate period of treatment and sufficient resources as needed.