Traumatic brain injury (TBI) is increasingly appreciated to be highly prevalent and deleterious to neurological function 1, 2 . At present no effective treatment options are available, and little is known about the complex cellular response to TBI during its acute phase. To gain novel insights into TBI pathogenesis, we developed a novel closed-skull brain injury model that mirrors some pathological features associated with mild TBI in humans and used long-term intravital microscopy to study the dynamics of the injury response from its inception. Here we demonstrate that acute brain injury induces vascular damage, meningeal cell death, and the generation of reactive oxygen species (ROS) that ultimately breach the glial limitans and promote spread of the injury into the parenchyma. In response, the brain elicits a neuroprotective, purinergic receptor dependent inflammatory response characterized by meningeal neutrophil swarming and microglial reconstitution of the damaged glial limitans. We additionally show that the skull bone is permeable to small molecular weight compounds and use this delivery route to modulate inflammation and therapeutically ameliorate brain injury through transcranial administration of the ROS scavenger, glutathione. Our results provide novel insights into the acute cellular response to TBI and a means to locally deliver therapeutic compounds to the site of injury.TBI encompasses injuries that range from mild to severe 1, 3 and occurs when the brain is exposed to external forces that induce focal and / or diffuse pathologies, including vascular damage, edema, axonal shearing, and neuronal cell death [4][5][6] . TBI is usually divided into two phases: the primary insult and ensuing secondary reaction. It is postulated that primary cell death cannot be prevented without avoiding the injury itself, but that secondary damage is amenable therapeutic intervention because it is driven by pathogenic parameters such as ROS 7,8 , calcium release 9 , glutamate toxicity 10, 11 , mitochondrial dysfunction 12 , inflammation 6 , etc. To date, animal models of TBI have been developed that reflect mild, Users may view, print, copy, download and text and data-mine the content in such documents, for the purposes of academic research, subject always to the full Conditions of use: http://www.nature.com/authors/editorial_policies/license.html#terms COMPETING FINANCIAL INTERESTSThe authors declare no competing financial interests. In humans, primary injury to the meninges and vasculature can be observed in the absence of conspicuous brain damage following minor head trauma. As part of an ongoing study of mild TBI, we evaluated research MRI with contrast from patients presenting to the emergency room within 48 hours of minor head injury. Over a period of 30 months, 142 patients were enrolled with a baseline Glasgow Coma Scale (GCS) of 15, reporting loss-ofconsciousness or post-traumatic amnesia, and a clinical computed tomography (CT) scan without evidence of injury to the parenchyma. Meningeal hemorrhag...

We describe a family of calcium indicators for magnetic resonance imaging (MRI), formed by combining a powerful iron oxide nanoparticle-based contrast mechanism with the versatile calciumsensing protein calmodulin and its targets. Calcium-dependent protein-protein interactions drive particle clustering and produce up to 5-fold changes in T2 relaxivity, an indication of the sensors' potency. A variant based on conjugates of wild-type calmodulin and the peptide M13 reports concentration changes near 1 M Ca 2؉ , suitable for detection of elevated intracellular calcium levels. The midpoint and cooperativity of the response can be tuned by mutating the protein domains that actuate the sensor. Robust MRI signal changes are achieved even at nanomolar particle concentrations (<1 M in calmodulin) that are unlikely to buffer calcium levels. When combined with technologies for cellular delivery of nanoparticulate agents, these sensors and their derivatives may be useful for functional molecular imaging of biological signaling networks in live, opaque specimens. magnetic resonance ͉ T2 relaxation ͉ signal transduction ͉ molecular imaging ͉ neuroimaging C alcium ions (Ca 2ϩ ) have been a favorite target in molecular imaging studies because of the important role of calcium as a second messenger in cellular signaling pathways. Fluorescent calcium sensors are used widely in optical imaging, both at the cellular level and at the cell population level. Calcium-sensitive dyes have recently been used in conjunction with laser scanning microscopy to follow neural network activity in small, threedimensional brain areas (1) and to characterize patterns of interaction among cells in developing vertebrate embryos (2). Because of the scattering properties of dense tissue, highresolution optical approaches like these are usually limited to superficial regions of specimens and to restricted fields of view (3). To probe calcium dynamics more globally in living systems, a different imaging modality must be used.Magnetic resonance imaging (MRI) is an increasingly accessible technique for imaging opaque subjects at fairly high spatial resolution, and MRI studies of calcium dynamics could, in principle, complement optical approaches by offering both greatly expanded coverage and depth penetration in vivo (4). Calcium isotopes are unsuitable for direct imaging by magnetic resonance, so attempts to sensitize MRI to calcium have focused around the use of molecular imaging agents. Fluorinated derivatives of the bivalent cation chelator 1,2-bis(2-aminophenoxy)ethane-N,N,NЈ,NЈ-tetraacetic acid (BAPTA) have permitted calcium measurements in vivo by 19 F MRI but only at Ϸ10 Ϫ5 the sensitivity of standard MRI methods (5, 6). Two potentially more powerful proton T1 relaxation-promoting contrast agents were subsequently introduced. The paramagnetic ion manganese (Mn 2ϩ ) mimics calcium by entering cells through calcium channels. Because it accumulates much faster than it is removed, Mn 2ϩ produces an ''integral'' of calcium signaling history that can be d...

Retrospective study of suicidal hangings was made on 175 cases (133 male victims, 42 female victims) for a 5-year period. The mean age was 47.33 +/- 17.51 years. The sample was divided in 4 groups according to the position of the ligature knot (anterior, right, left, and posterior hanging). The authors analyzed all visible injuries of soft tissues and bones and cartilage of the neck, and in 150 cases (85.7%), we established that there was at least one injury of these structures (hematoma or fracture for example). The most frequent injury was to sternocleidomastoid muscles. Fracture of throat skeleton was detected in 119 cases (68%). The proportion of fractures increases with age of the deceased. There was no clear correlation between frequency of neck injuries and type of hanging.

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