Axonopathy is a hallmark of many neurodegenerative diseases including glaucoma, where elevated intraocular pressure (ocular hypertension, OHT) stresses retinal ganglion cell (RGC) axons as they exit the eye and form the optic nerve. OHT causes early changes in the optic nerve such as axon atrophy, transport inhibition, and gliosis. Importantly, many of these changes appear to occur prior to irreversible neuronal loss, making them promising points for early diagnosis of glaucoma. It is unknown whether OHT has similarly early effects on the function of RGC output to the brain. To test this possibility, we elevated eye pressure in mice by anterior chamber injection of polystyrene microbeads. Five weeks post-injection, bead-injected eyes showed a modest RGC loss in the peripheral retina, as evidenced by RBPMS antibody staining. Additionally, we observed reduced dendritic complexity and lower spontaneous spike rate of On-αRGCs, targeted for patch clamp recording and dye filling using a Opn4-Cre reporter mouse line. To determine the influence of OHT on retinal projections to the brain, we expressed Channelrhodopsin-2 (ChR2) in melanopsin-expressing RGCs by crossing the Opn4-Cre mouse line with a ChR2-reporter mouse line and recorded post-synaptic responses in thalamocortical relay neurons in the dorsal lateral geniculate nucleus (dLGN) of the thalamus evoked by stimulation with 460 nm light. The use of a Opn4-Cre reporter system allowed for expression of ChR2 in a narrow subset of RGCs responsible for image-forming vision in mice. Five weeks following OHT induction, paired pulse and high-frequency stimulus train experiments revealed that presynaptic vesicle release probability at retinogeniculate synapses was elevated. Additionally, miniature synaptic current frequency was slightly reduced in brain slices from OHT mice and proximal dendrites of post-synaptic dLGN relay neurons, assessed using a Sholl analysis, showed a reduced complexity. Strikingly, these changes occurred prior to major loss of RGCs labeled with the Opn4-Cre mouse, as indicated by immunofluorescence staining of ChR2-expressing retinal neurons. Thus, OHT leads to pre- and post-synaptic functional and structural changes at retinogeniculate synapses. Along with RGC dendritic remodeling and optic nerve transport changes, these retinogeniculate synaptic changes are among the earliest signs of glaucoma.

The collection efficiency of two widely used gunshot residue (GSR) collection techniques-carbon-coated adhesive stubs and alcohol swabs-has been compared by counting the number of characteristic GSR particles collected from the firing hand of a shooter after firing one round. Samples were analyzed with both scanning electron microscopy and energy dispersive X-rays by an experienced GSR analyst, and the number of particles on each sample containing Pb, Ba, and Sb counted. The adhesive stubs showed a greater collection efficiency as all 24 samples gave positive results for GSR particles whereas the swabs gave only positive results for half of the 24 samples. Results showed a statistically significant collection efficiency for the stub collection method and likely reasons for this are considered.

27Axonopathy is a hallmark of many neurodegenerative diseases including glaucoma, where elevated 28 intraocular pressure (ocular hypertension, OHT) stresses retinal ganglion cell (RGC) axons as they exit 29 the eye and form the optic nerve. OHT causes early changes in the optic nerve such as axon atrophy, 30 transport inhibition, and gliosis. Importantly, many of these changes appear to occur prior to irreversible 31 neuronal loss, making them promising points for early diagnosis of glaucoma. It is unknown whether 32OHT has similarly early effects on the function of RGC output to the brain. To test this possibility, we 33 elevated eye pressure in mice by anterior chamber injection of polystyrene microbeads. 5 weeks post-34injection, bead-injected eyes showed a modest RGC loss in the peripheral retina, as evidenced by RBPMS 35 antibody staining. Additionally, we observed reduced dendritic complexity and lower spontaneous spike 36 rate of On-RGCs, targeted for patch clamp recording and dye filling using a Opn4-cre reporter mouse 37 line. To determine the influence of OHT on retinal projections to the brain, we expressed 38Channelrhodopsin-2 (ChR2) in melanopsin-expressing retinal ganglion cells by crossing the Opn4-cre 39 mouse line with a ChR2-reporter mouse line and recorded post-synaptic responses in thalamocortical 40relay neurons in the dorsal lateral geniculate nucleus (dLGN) of the thalamus evoked by stimulation with 41 460 nm light. The use of a Opn4-cre reporter system allowed for expression of ChR2 in a narrow subset 42of RGCs responsible for image-forming vision in mice. Five weeks following OHT induction, paired 43 pulse and high-frequency stimulus train experiments revealed that presynaptic vesicle release probability 44at retinogeniculate synapses was elevated. Additionally, miniature synaptic current frequency was slightly 45 reduced in brain slices from OHT mice and proximal dendrites of post-synaptic dLGN relay neurons, 46assessed using a Sholl analysis, showed a reduced complexity. Strikingly, these changes occurred prior to 47 major loss of RGCs labeled with the Opn4-Cre mouse, as indicated by immunofluorescence staining of 48ChR2-expressing retinal neurons. Thus, OHT leads to pre-and post-synaptic functional and structural 49 changes at retinogeniculate synapses. Along with RGC dendritic remodeling and optic nerve transport 50 changes, these retinogeniculate synaptic changes are among the earliest signs of glaucoma. 51 52