Self-assembling, coiled coil interfaces for nanoscale amperometric biosensors

Both gold nanostructures and carbon nanotubes are rapidly emerging platforms for amperometric biosensor detection. Homogeneous display of biomolecular ligands is a key process in forming nanoscale array biosensors, improving the chances for sufficient signal strength and reproducibility at the limits of sensor geometries. The use of selfassembling interfaces on gold electrodes and CNT arrays enables homogeneous display, solvent access, target capture, sensor surface regeneration and potential for molecular wiring. Our approach uses an anchor peptide, covalently linked to the sensor surface, that is able to non-covalently capture probe labeled targets in solution with a high affinity and minimal surface leaching. The use of non-disrupting, metal-chelating scaffolds within the coiled coil sequence was tested for molecular wiring capabilities using model redox targets. Recombinant cassette production of probe sequences was investigated as a means to enable control over spatial and stoichiometric placement of redox active mediators and/or biomolecules. This thesis defines potential challenges that face protein interfacing in amperometric biosensors as well as opportunities for future developments.Ph.D., Biomedical Engineering -- Drexel University, 200

Interactions of Peptide Triazole Thiols with Env gp120 Induce Irreversible Breakdown and Inactivation of HIV-1 Virions

Background: We examined the underlying mechanism of action of the peptide triazole thiol, KR13 that has been shown previously to specifically bind gp120, block cell receptor site interactions and potently inhibit HIV-1 infectivity. Results: KR13, the sulfhydryl blocked KR13b and its parent non-sulfhydryl peptide triazole, HNG156, induced gp120 shedding but only KR13 induced p24 capsid protein release. The resulting virion post virolysis had an altered morphology, contained no gp120, but retained gp41 that bound to neutralizing gp41 antibodies. Remarkably, HIV-1 p24 release by KR13 was inhibited by enfuvirtide, which blocks formation of the gp41 6-helix bundle during membrane fusion, while no inhibition of p24 release occurred for enfuvirtide-resistant virus. KR13 thus appears to induce structural changes in gp41 normally associated with membrane fusion and cell entry. The HIV-1 p24 release induced by KR13 was observed in several clades of HIV-1 as well as in fully infectious HIV-1 virions. Conclusions: The antiviral activity of KR13 and its ability to inactivate virions prior to target cell engagement suggest that peptide triazole thiols could be highly effective in inhibiting HIV transmission across mucosal barriers and provide a novel probe to understand biochemical signals within envelope that are involved in membrane fusion

The sensitivity of ECG contamination to surgical implantation site in brain computer interfaces.

BACKGROUND Brain sensing devices are approved today for Parkinson's, essential tremor, and epilepsy therapies. Clinical decisions for implants are often influenced by the premise that patients will benefit from using sensing technology. However, artifacts, such as ECG contamination, can render such treatments unreliable. Therefore, clinicians need to understand how surgical decisions may affect artifact probability. OBJECTIVES Investigate neural signal contamination with ECG activity in sensing enabled neurostimulation systems, and in particular clinical choices such as implant location that impact signal fidelity. METHODS Electric field modeling and empirical signals from 85 patients were used to investigate the relationship between implant location and ECG contamination. RESULTS The impact on neural recordings depends on the difference between ECG signal and noise floor of the electrophysiological recording. Empirically, we demonstrate that severe ECG contamination was more than 3.2x higher in left-sided subclavicular implants (48.3%), when compared to right-sided implants (15.3%). Cranial implants did not show ECG contamination. CONCLUSIONS Given the relative frequency of corrupted neural signals, we conclude that implant location will impact the ability of brain sensing devices to be used for "closed-loop" algorithms. Clinical adjustments such as implant location can significantly affect signal integrity and need consideration

Dystonia Management: What to Expect From the Future? The Perspectives of Patients and Clinicians Within DystoniaNet Europe

Improved care for people with dystonia presents a number of challenges. Major gaps in knowledge exist with regard to how to optimize the diagnostic process, how to leverage discoveries in pathophysiology into biomarkers, and how to develop an evidence base for current and novel treatments. These challenges are made greater by the realization of the wide spectrum of symptoms and difficulties faced by people with dystonia, which go well-beyond motor symptoms. A network of clinicians, scientists, and patients could provide resources to facilitate information exchange at different levels, share mutual experiences, and support each other's innovative projects. In the past, collaborative initiatives have been launched, including the American Dystonia Coalition, the European Cooperation in Science and Technology (COST—which however only existed for a limited time), and the Dutch DystonieNet project. The European Reference Network on Rare Neurological Diseases includes dystonia among other rare conditions affecting the central nervous system in a dedicated stream. Currently, we aim to broaden the scope of these initiatives to a comprehensive European level by further expanding the DystoniaNet network, in close collaboration with the ERN-RND. In line with the ERN-RND, the mission of DystoniaNet Europe is to improve care and quality of life for people with dystonia by, among other endeavors, facilitating access to specialized care, overcoming the disparity in education of medical professionals, and serving as a solid platform to foster international clinical and research collaborations. In this review, both professionals within the dystonia field and patients and caregivers representing Dystonia Europe highlight important unsolved issues and promising new strategies and the role that a European network can play in activating them

The impact of deep brain stimulation on tinnitus

BACKGROUND: Tinnitus is a disorder of the nervous system that cannot be adequately treated with current therapies. The effect of neuromodulation induced by deep brain stimulation (DBS) on tinnitus has not been studied well. This study investigated the effect of DBS on tinnitus by use of a multicenter questionnaire study. METHODS: Tinnitus was retrospectively assessed prior to DBS and at the current situation (with DBS). From the 685 questionnaires, 443 were returned. A control group was one-to-one matched to DBS patients who had tinnitus before DBS (n = 61). Tinnitus was assessed by the tinnitus handicap inventory (THI) and visual analog scales (VAS) of loudness and burden. RESULTS: The THI decreased significantly during DBS compared to the situation prior to surgery (from 18.9 to 15.1, P < .001), which was only significant for DBS in the subthalamic nucleus (STN). The THI in the control group (36.9 to 35.5, P = 0.50) and other DBS targets did not change. The VAS loudness increased in the control group (5.4 to 6.0 P < .01). CONCLUSION: DBS might have a modulatory effect on tinnitus. Our study suggests that DBS of the STN may have a beneficial effect on tinnitus, but most likely other nuclei linked to the tinnitus circuitry might be even more effective

A protein engineering approach differentiates the functional importance of carbohydrate moieties of interleukin-5 receptor α

Human interleukin-5 receptor alpha (IL5R alpha) is a glycoprotein that contains four N-glycosylation sites in the extracellular region. Previously, we found that enzymatic deglycosylation of IL5R alpha resulted in complete loss of IL5 binding To localize the functionally important carbohydrate moieties, we employed site directed mutagenesis at the N-glycosylation sites (Asn(15), Asn(111), Asn(196), and Asn(224)). Because Asn-to-Gln mutagenesis caused a significant loss of structural integrity, we used diverse mutations to identify stability changes. We also rationally designed mutations at and around the N-glycosylation sites based on sequence alignment with mouse IL5R alpha and other cytokine receptors. These approaches were most successful at Asn(15), Asn(111), and Asn(224). In contrast, any replacement at Asn(196) severely reduced stability, with the N196T mutant having a reduced binding affinity for IL5 and diminished biological activity because of the lack of cell surface expression. Lectin inhibition analysis suggested that the carbohydrate at Asn(196) is unlikely involved in direct ligand binding Taking this into account, we constructed a stable variant, with triple mutational deglycosylation (N15D, I109V/V110T/N111D, and L223R/N224Q). The re-engineered protein retained Asn(196) while the other three glycosylation sites were eliminated. This mostly deglycosylated variant had the same ligand binding affinity and biological activity as fully glycosylated IL5R alpha, thus demonstrating a unique role for Asn(196) glycosylation in IL5R alpha function. The results suggest that unique carbohydrate groups in multiglycosylated receptors can be utilized asymmetrically for function

Thalamic Deep Brain Stimulation for Orthostatic Tremor: A Multicenter International Registry

Background: We report the accumulated experience with ventral intermediate nucleus deep brain stimulation for medically refractory orthostatic tremor. Methods: Data from 17 patients were reviewed, comparing presurgical, short-term (0-48 months), and long-term (>= 48 months) follow-up. The primary end point was the composite activities of daily living/instrumental activities of daily living score. Secondary end points included latency of symptoms on standing and treatment-related complications. Results: There was a 21.6% improvement (P = 0.004) in the composite activities of daily living/instrumental activities of daily living score, which gradually attenuated (12.5%) in the subgroup of patients with an additional long-term follow-up (8 of 17). The latency of symptoms on standing significantly improved, both in the shortterm (P = 0.001) and in the long-term (P = 0.018). Three patients obtained no/minimal benefit from the procedure. Conclusions: Deep brain stimulation of the ventral intermediate nucleus was, in general, safe and well tolerated, yielding sustained benefit in selected patients with medically refractory orthostatic tremor. (C) 2017 Internationa