Mild traumatic brain injury (mTBI) is an increasing public health concern as repetitive injuries can exacerbate existing neuropathology and result in increased neurologic deficits. In contrast to other models of repeated mTBI (rmTBI), our study focused on long-term white-matter abnormalities after bilateral mTBIs induced 7 days apart. A controlled cortical impact (CCI) was used to induce an initial mTBI to the right cortex of Single and rmTBI Sprague Dawley rats, followed by a second injury to the left cortex of rmTBI animals. Shams received only a craniectomy. Ex vivo diffusion tensor imaging (DTI), transmission electron microscopy (TEM), and histology were performed on the anterior corpus callosum at 60 days after injury. The rmTBI animals showed a significant bilateral increase in radial diffusivity (myelin), while only modest changes in axial diffusivity (axonal) were seen between the groups. Further, the rmTBI group showed an increased g-ratio and axon caliber in addition to myelin sheath abnormalities using TEM. Our DTI results indicate ongoing myelin changes, while the TEM data show continuing axonal changes at 60 days after rmTBI. These data suggest that bilateral rmTBI induced 7 days apart leads to progressive alterations in white matter that are not observed after a single mTBI.

Graphic abstract KeywordsAlkyne, halo-functionalization, one-pot, iron. AbstractAromatic and aliphatic alkynes can be halo-functionalized to α,α-dihalodimethyl ketals catalyzed by FeCl 3 in excellent yields. MeOH is used as a nucleophilic solvent and N-halosuccinimide as the halogen source for this efficient transformation. The resulting α,α-dibromodimethyl ketals can be converted to the corresponding α,α-dibromoketones by treatment with 8% FeCl 3 in silica gel.

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1,3‐Dipolar cycloaddition of in situ generated nitrile oxides with α,β‐acetylenic aldehydes allows the isolation of the expected isoxazoles as single regioisomers.

Iron(III) Catalyzed Halo-Functionalization of Alkynes. -The FeCl 3-catalyzed reaction of alkynes with NBS or NIS in methanol provides ,-dihalodimethyl ketals in excellent yields. The dihaloproducts such as (Ia-f) are easily converted to the corresponding dihaloketones. -(CATANO, B.; LEE, J.; KIM, C.; FARRELL, D.; PETERSEN, J. L.; XING*, Y.; Tetrahedron Lett. 56 (2015) 27, 4124-4127, http://dx.