Thomas A. Swift's Electric Rifle Injuries to the Eye and Ocular Adnexa: The Management of Complex Trauma.

PURPOSE: To report the ocular and adnexal injuries sustained by patients with Thomas A. Swift's electric rifles (TASER; TASER International, Scottsdale, AZ), review the literature, and discuss the management of this complex trauma. DESIGN: Multicenter, retrospective case series and literature review. PARTICIPANTS: Seventeen eyes of 16 patients (5 eyes of 5 patients treated at 3 institutions, and 12 eyes of 11 previously reported cases). METHODS: The clinical data of 17 eyes were pooled. Spearman's correlation coefficient was used to assess the association between the extent of TASER injury and patient outcomes. MAIN OUTCOME MEASURES: Extent of TASER injury (zone of injury, penetrating vs. perforating) and association with patient outcomes (visual acuity [VA] and retinal detachment [RD]). RESULTS: In our cohort, 4 patients were transported by law enforcement and 1 was transferred from a community hospital. Four patients were taken to the operating room for TASER removal and globe repair; 1 patient underwent removal in the emergency room. Of 17 pooled cases, 12 (71%) involved open-globe injury. Of these, there was a high rate of zone 3 injuries (100%; n = 12) and a high incidence of RD (73%; 8 of 11, eviscerated eye excluded). Among patients with closed-globe injury (n = 5), 1 patient demonstrated exudative RD and 1 patient demonstrated retinal dialysis with RD. Of 10 patients with RD, 1 (10%) achieved resolution with monitoring (exudative RD); 1 (10%) underwent cryopexy and pneumatic retinopexy; 3 (30%) underwent vitrectomy, and 5 (50%) with poor prognosis did not undergo vitreoretinal surgery. In the 3 patients who underwent vitrectomy, all 3 (100%) demonstrated redetachment resulting from proliferative vitreoretinopathy and required additional surgery. Visual acuity on presentation was significantly correlated with final VA (ρ = 0.783; P = 0.02). Men (94%) were more likely than women (6%) to sustain TASER trauma. Median age was 26 years. There was a 50% rate of loss to follow-up. CONCLUSIONS: Thomas A. Swift's electric rifle injuries to the eyes or ocular adnexa represent complex trauma. Zone 3 injuries are common. The visual prognosis is guarded, and eyes may require multiple surgeries to preserve vision. Patients are at high risk for loss to follow-up by way of incarceration.

Ca2+/calmodulin regulates trafficking of Ca(V)1.2 Ca2+ channels in cultured hippocampal neurons.

As the Ca2+-sensor for Ca2+-dependent inactivation, calmodulin (CaM) has been proposed, but never definitively demonstrated, to be a constitutive Ca(V)1.2 Ca2+ channel subunit. Here we show that CaM is associated with the Ca(V)1.2 pore-forming alpha1C subunit in brain in a Ca2+-independent manner. Within its CaM binding pocket, alpha1C has been proposed to contain a membrane targeting domain. Because ion channel subunits assemble early during channel biosynthesis, we postulated that this association with CaM could afford the opportunity for Ca2+-dependent regulation of membrane targeting. We showed that the isolated domain functioned as a Ca2+/CaM regulated trafficking determinant for CD8 (a model transmembrane protein) using fluorescent-activated cell sorting analysis and, using green fluorescent protein-tagged alpha1C subunits expressed in cultured hippocampal neurons, that Ca2+/CaM interaction with this domain accelerated trafficking of Ca(V)1.2 channels to distal regions of the dendritic arbor. Furthermore, this Ca2+/CaM-accelerated trafficking was activity dependent. Thus, CaM imparts Ca2+-dependent regulation not only to mature Ca(V)1.2 channels at the cell surface but also to steps during channel biosynthesis.

Voltage sensor movement and cAMP binding allosterically regulate an inherently voltage-independent closed-open transition in HCN channels.

The hyperpolarization-activated cyclic nucleotide-modulated cation (HCN) channels are regulated by both membrane voltage and the binding of cyclic nucleotides to a cytoplasmic, C-terminal cyclic nucleotide-binding domain (CNBD). Here we have addressed the mechanism of this dual regulation for HCN2 channels, which activate with slow kinetics that are strongly accelerated by cAMP, and HCN1 channels, which activate with rapid kinetics that are weakly enhanced by cAMP. Surprisingly, we find that the rate of opening of HCN2 approaches a maximal value with extreme hyperpolarization, indicating the presence of a voltage-independent kinetic step in the opening process that becomes rate limiting at very negative potentials. cAMP binding enhances the rate of this voltage-independent opening step. In contrast, the rate of opening of HCN1 is much greater than that of HCN2 and does not saturate with increasing hyperpolarization over the voltage range examined. Domain-swapping chimeras between HCN1 and HCN2 reveal that the S4-S6 transmembrane region largely determines the limiting rate in opening kinetics at negative voltages. Measurements of HCN2 tail current kinetics also reveal a voltage-independent closing step that becomes rate limiting at positive voltages; the rate of this closing step is decreased by cAMP. These results are consistent with a cyclic allosteric model in which a closed-open transition that is inherently voltage independent is subject to dual allosteric regulation by voltage sensor movement and cAMP binding. This mechanism accounts for several properties of HCN channel gating and has potentially important physiological implications.

OCHROCONIS GALLOPAVA ENDOPHTHALMITIS SUCCESSFULLY TREATED WITH INTRAVITREAL VORICONAZOLE AND AMPHOTERICIN B.

PURPOSE: Ochroconis gallopava is a darkly pigmented septated fungus that rarely infects humans, almost universally immunocompromised individuals. Only one previous case has been reported of O. gallopava endophthalmitis, in which the patient progressed to a visual acuity of no light perception. The authors currently describe the first successfully treated case of O. gallopava endophthalmitis. METHODS: A 65-year-old Hispanic woman on chronic immunosuppression after a right lung transplant was admitted to the hospital for O. gallopava respiratory tract infection and was found to have bilateral endogenous endophthalmitis. Examination revealed multiple, cream-colored, chorioretinal lesions in the fundus, including one near the temporal macula in the left eye. There was no diffuse vitritis. Visual acuity was 20/30 in both eyes at presentation but dropped to 20/400 in the right eye and counting fingers at 3 feet in the left eye over the hospital course despite receiving an intravitreal injection of voriconazole in the left eye and concurrent IV amphotericin B, posaconazole, and micafungin. The patient was then treated with multiple simultaneous intravitreal amphotericin B and voriconazole injections bilaterally, as well as IV posaconazole, which was switched to IV voriconazole for improved intraocular penetration. RESULTS: The chorioretinal lesions were noted to regress with treatment. Concomitantly, the patient's respiratory status improved, and she was discharged with a visual acuity of 20/40 in the right eye and 20/60 in the left eye. The patient completed a 1-year course of oral voriconazole as an outpatient without signs of recurrent activity. Seventeen months after the initial presentation, the patient had 20/40 vision bilaterally with a residual, white, fibrotic scar at the temporal macula in the left eye. CONCLUSION: This report describes the first successful treatment regimen against O. gallopava endophthalmitis using a combination of intravitreal amphotericin B and voriconazole injections, as well as IV posaconazole and voriconazole, which resulted in an excellent visual outcome.

HCN hyperpolarization-activated cation channels inhibit EPSPs by interactions with M-type K(+) channels.

The processing of synaptic potentials by neuronal dendrites depends on both their passive cable properties and active voltage-gated channels, which can generate complex effects as a result of their nonlinear properties. We characterized the actions of HCN (hyperpolarization-activated cyclic nucleotide-gated cation) channels on dendritic processing of subthreshold excitatory postsynaptic potentials (EPSPs) in mouse CA1 hippocampal neurons. The HCN channels generated an excitatory inward current (I(h)) that exerted a direct depolarizing effect on the peak voltage of weak EPSPs, but produced a paradoxical hyperpolarizing effect on the peak voltage of stronger, but still subthreshold, EPSPs. Using a combined modeling and experimental approach, we found that the inhibitory action of I(h) was caused by its interaction with the delayed-rectifier M-type K(+) current. In this manner, I(h) can enhance spike firing in response to an EPSP when spike threshold is low and can inhibit firing when spike threshold is high.