Faculty Bibliography

Pain is a complex sensory and affective experience. The current definition for pain relies on verbal reports in clinical settings and behavioral assays in animal models. These definitions can be subjective and do not take into consideration signals in the neural system. Local field potentials (LFPs) represent summed electrical currents from multiple neurons in a defined brain area. Although single neuronal spike activity has been shown to modulate the acute pain, it is not yet clear how ensemble activities in the form of LFPs can be used to decode the precise timing and intensity of pain. The anterior cingulate cortex (ACC) is known to play a role in the affective-aversive component of pain in human and animal studies. Few studies, however, have examined how neural activities in the ACC can be used to interpret or predict acute noxious inputs. Here, we recorded in vivo extracellular activity in the ACC from freely behaving rats after stimulus with non-noxious, low-intensity noxious, and high-intensity noxious stimuli, both in the absence and chronic pain. Using a supervised machine learning classifier with selected LFP features, we predicted the intensity and the onset of acute nociceptive signals with high degree of precision. These results suggest the potential to use LFPs to decode acute pain.

Natural products have many health benefits, and their application can improve the quality of life. Recently, the diterpene (+)-larixol and its acetylated congeners demonstrated selective inhibition of the second-messenger-gated cation channel transient receptor potential canonical 6 (TRPC6) over its close isoforms TRPC3 and TRPC7. Building on this knowledge, we expanded these findings by chemical diversification of (+)-larixol mostly at position C6. Implementing high-throughput Ca2+ FLIPR screening assays and electrophysiological patch-clamp recordings, we showcase larixyl N-methylcarbamate, termed SH045, as a compound with nanomolar affinity and 13-fold subtype selectivity over TRPC3 in stably expressing HEK293 cells. Expanding on this finding, TRPC6 inhibition was also observed in rat pulmonary smooth muscle cells. Furthermore, treatment of isolated perfused lung preparations with SH045 led to a decrease in lung ischemia-reperfusion edema (LIRE), a life-threatening condition associated with TRPC6 that may occur after organ transplantation. Taken together, and given the inexpensive, straightforward, and scalable preparation of SH045, we report a TRPC6 blocker that holds promise for the translational treatment of LIRE.

BACKGROUND:Atrial standstill is an arrhythmogenic condition characterized by the absence of spontaneous electrical and mechanical atrial activity or in response to stimulation. There are few reported familial cases which have been associated with SCN5A mutations co-segregating with GJA5 or RYR2 however isolated SCN5A mutations are rare. OBJECTIVE:The purpose of this study was to determine the clinical and biophysical consequence of a novel SCN5A mutation identified in a family with progressive atrial standstill and sudden death. METHODS:The family of a sporadic case of congenital atrial standstill underwent genetic screening. Human Embryonic Kidney 293 cells were transfected with wild-type (WT) or mutant SCN5A cDNAs. Biophysical properties were studied using whole-cell using patch clamp methods. RESULTS:A novel homozygous SCN5A mutation, p.V1340L was identified in the proband and her sister. The proband had complete atrial standstill whereas the sister had partial atrial standstill. Heterozygous mutations were identified in the mother, father and brother. All three had normal sinus rhythm and were asymptomatic. The mutant Nav1.5(V1340L) reduced Nav1.5 current density as well as showed a depolarizing shift in the voltage-dependent steady-state activation (WT: -35.3±1.62 mV; V1340L: -22.4±2.59 mV; P = 0.001). CONCLUSIONS:A homozygous loss-of-function SCN5A mutation likely results in atrial standstill and sudden death due to suppression of initiation of action potential.

STUDY OBJECTIVES/OBJECTIVE:A relationship between obstructive sleep apnea (OSA) and exposure to the World Trade Center (WTC) dust and fumes has been suggested in responders but little is known about a possible relationship in community members. We characterized sleep studies performed in community members with WTC dust exposure to improve our understanding of the relationship between the diagnosis and severity of OSA and WTC dust exposure in this population. METHODS:Single-center, retrospective study of patients enrolled in a clinical treatment program for community members with WTC dust exposure. Patients were included if they had undergone sleep studies for evaluation of possible OSA through September 2016 and provided written informed consent. RESULTS:. Most reported upper and lower respiratory symptoms. An apnea-hypopnea index (AHI) ≥ 5 events/h was measured in 66% of the patients, and respiratory disturbance index was ≥ 5 events/h in 97%. The proportion of patients with moderate-severe OSA (defined by the AHI 4% criteria) was 50%. Multivariate logistic regression revealed that acute WTC dust cloud exposure was associated with severity but not diagnosis of OSA. CONCLUSIONS:We identified a high rate of OSA in the WTC community cohort who were referred for sleep studies. Exposure to the massive WTC dust cloud caused by the WTC collapse was independently associated with the severity of OSA in this population. This finding highlights the role that environmental exposures may play in the development of OSA.

Transcranial electrical stimulation (TES) is a powerful and relatively simple approach to diffusely influence brain activity either randomly or in a closed-loop event-triggered manner. Although many studies are focusing on the possible benefits and side-effects of TES in healthy and pathologic brains, there are still many fundamental open questions regarding the mechanism of action of the stimulation. Therefore, there is a clear need for a robust and reproducible method to test the acute and the chronic effects of TES in rodents. TES can be combined with regular behavioral, electrophysiological, and imaging techniques to investigate neuronal networks in vivo. The implantation of transcranial stimulation electrodes does not impose extra constraints on the experimental design while it offers a versatile, flexible tool to manipulate brain activity. Here we provide a detailed, step-by-step protocol to fabricate and implant transcranial stimulation electrodes to influence brain activity in a temporally constrained manner for months.

In this issue of Cell, Shin et al. report the first live-cell imaging of a fusion pore. Directly visualized pores in neuroendocrine cells can be much larger than expected yet not require vesicular full-collapse. These fusion-fission pores have diverse fates arising from opposing dynamin-driven pore constriction and F-actin-mediated pore expansion.

OBJECTIVE Since the first clinical application of the incisionless magnetic resonance-guided focused ultrasound (MRgFUS) technology only small series of patients have been reported, and thus only extrapolations of the procedure-related risks could be offered. In this study, the authors analyze side-effects and targeting accuracy in 180 consecutive treatments with MRgFUS for chronic therapy-resistant idiopathic Parkinson's disease (PD), essential tremor (ET), cerebellar tremor (CT), and neuropathic pain (NP), all performed in their dedicated center. METHODS A total of 180 treatments with MRgFUS for chronic therapy-resistant idiopathic PD, ET, CT, and NP were prospectively assessed for side-effects and targeting accuracy. Monitoring for later side-effects was continued for at least 3 months after the procedure in all but 1 case (0.6%); in that single case, the patient was lost to follow-up after an uneventful early postoperative course. The surgical targets were the pallidothalamic tract (pallidothalamic tractotomy, n = 105), the cerebellothalamic tract (cerebellothalamic tractotomy, n = 50), the central lateral nucleus (central lateral thalamotomy, n = 84), the centrum medianum (centrum medianum thalamotomy, n = 12), and the globus pallidus (pallidotomy, n = 2). Cognitive testing was performed before, 1-2 days after, and 1 year after the procedure. The Mini-Mental State Examination (MMSE) was used for the first 29 cases and was then replaced by the Montreal Cognitive Assessment (MoCA). Lesion reconstruction and measurement of targeting accuracy were done on 2-day posttreatment MR images for each performed target. To determine targeting accuracy measurement, 234 out of the 253 lesions depicted in the 2-day postoperative MR examination could be 3D-reconstructed. RESULTS The mean MoCA score was slightly improved 2 days postoperatively (p = 0.002) and remained stable at 1-year follow-up (p = 0.03). The mean MMSE score was also slightly improved 2 days postoperatively and at 1-year follow-up, but the improvement was not statistically significant (p = 0.06 and p = 0.2, respectively). The mean (± SD) accuracy was 0.32 ± 0.29 mm, 0.29 ± 0.28 mm, and 0.44 ± 0.39 mm for the mediolateral, anteroposterior, and dorsoventral dimensions, respectively. The mean 3D accuracy was 0.73 ± 0.39 mm. As to side-effects, 14 events over 180 treatments were documented. They were classified into procedure-related (n = 4, 2.2%), effect on neighboring structures (n = 3, 1.7%), and disease-related (n = 7, 3.9%). There was no bleeding. CONCLUSIONS The incisionless transcranial MRgFUS technology demonstrates a higher targeting accuracy and a lower side-effect profile than techniques requiring cerebral penetration. In the absence of penetration brain shift, this technique avoids the placement of a thermolesion away from the chosen target, thus suppressing the need for reversible therapeutic energy application. With the use of proper physiopathology-based targets, definitive therapeutic effects can be coupled with sparing of sensory, motor, and paralimbic/multimodal thalamocortical functions. Clinical efficacy, not analyzed in this investigation, will ultimately rest in proper target selection and optimized thermolesional coverage of the target.