Blast Exposure and Risk of Recurrent Occupational Overpressure Exposure Predict Deployment TBIs.

INTRODUCTION: Traumatic brain injury (TBI) has been the leading cause of morbidity and mortality in recent military conflicts and deployment-related TBIs are most commonly caused by blast. However, knowledge of risk factors that increase susceptibility to TBI following an acute, high-level blast is limited. We hypothesized that recurrent occupational overpressure exposure (ROPE) may be one factor that increases susceptibility to mild TBI (mTBI) following blast. MATERIALS AND METHODS: Using military occupational specialty as a proxy, we examined the effects of high versus low ROPE on mTBI following blast exposure. Initial analyses included 111,641 active-duty-enlisted U.S. Marines who completed the 2003 or 2008 version of the Post-Deployment Health Assessment. Final analyses examined probable mTBI screens among Marines with at least one qualifying exposure as a function of whether the exposure was a blast and level of ROPE (N = 12,929). This study was approved by the Institutional Review Board at the Naval Health Research Center. RESULTS: Blast and ROPE were both independently and jointly associated with a probable mTBI. Marines who experienced a blast (vs other qualifying exposure) and those in high (vs low) risk occupations were 1.07 and 1.23 times more likely to sustain a probable mTBI, respectively. Furthermore, among those who experienced a blast during deployment, those in high-risk occupations were 1.45 times more likely than those in low-risk occupations to sustain a probable mTBI. CONCLUSIONS: Blast exposure and ROPE were independently associated with mTBIs, and Marines with both blast exposure during deployment and ROPE were especially likely to sustain an mTBI. This suggests that ROPE heightens the risk of mTBI following blast. Ongoing research is examining the severity, symptomology, and sequelae of TBIs as a function of ROPE.

Crystal structure and spectroscopic characterization of a cobalt(II) tetraazamacrocycle: completing a series of first-row transition-metal complexes.

The tetraazamacrocyclic ligand 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane (TMC) has been used to bind a variety of first-row transition metals but to date the crystal structure of the cobalt(II) complex has been missing from this series. The missing cobalt complex chlorido(1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane-κ4N)cobalt(II) chloride dihydrate, [CoCl(C14H32N4)]Cl·2H2O or [CoIICl(TMC)]Cl·2H2O, crystallizes as a purple crystal. This species adopts a distorted square-pyramidal geometry in which the TMC ligand assumes the trans-I configuration and the chloride ion binds in the syn-methyl pocket of the ligand. The CoII ion adopts an S = 3/2 spin state, as measured by the Evans NMR method, and UV-visible spectroscopic studies indicate that the title hydrated salt is stable in solution. Density functional theory (DFT) studies reveal that the geometric parameters of [CoIICl(TMC)]Cl·2H2O are sensitive to the cobalt spin state and correctly predict a change in spin state upon a minor perturbation to the ligand environment.