Targeted Vagus Nerve Stimulation does not Disrupt Cardiac Function in the Diabetic Rat

In this study, we acutely identified a target branch of the vagus nerve known as the pancreatic branch of the vagus nerve, which exclusively innervates the pancreas by applying electrical stimulus to the known cervical vagus nerve and observing compound neural action potentials at the target nerve. In a set of chronically implanted rats, the target nerve was again cuffed using an electrode and also implanted with a continuous glucose monitor. A model of type 1 diabetes (T1D) was chemically induced and hyperglycemic state confirmed. After induction, stimulation was applied to the pancreatic branch of the vagus nerve and heart rate variability measured to assess the targeted nature of the stimulation. Pancreatic vagus nerve stimulation in a diabetic model was not found to influence heart rate demonstrating the ability of targeted stimulation to be used as for organ-specific neuromodulation while minimizing side effects.

Enteric Neuromodulation for the Gut and Beyond

The small intestine is the longest organ in the human body, spanning a length of ∼5 m and compartmentalized into three distinct regions with specific roles in maintenance of comprehensive homeostasis. Along its length exists as a unique and independent system-called the enteric nervous system (ENS)-which coordinates the multitude of functions continuously around the clock. Yet, with so many vital roles played, the functions, relationships, and roles of the small intestine and ENS remain largely elusive. This fundamental hole in the physiology of the small intestine and ENS introduces a substantial number of challenges when attempting to create bioelectronic approaches for treatment of various disorders originating in the small intestine. Here, we review existing therapeutic options for modulating the small intestine, discuss fundamental gaps that must be addressed, and highlight novel methods and approaches to consider for development of bioelectronic approaches aiming to modulate the small intestine.

Open Ephys: an open-source, plugin-based platform for multichannel electrophysiology

OBJECTIVE

Closed-loop experiments, in which causal interventions are conditioned on the state of the system under investigation, have become increasingly common in neuroscience. Such experiments can have a high degree of explanatory power, but they require a precise implementation that can be difficult to replicate across laboratories. We sought to overcome this limitation by building open-source software that makes it easier to develop and share algorithms for closed-loop control.

APPROACH

We created the Open Ephys GUI, an open-source platform for multichannel electrophysiology experiments. In addition to the standard 'open-loop' visualization and recording functionality, the GUI also includes modules for delivering feedback in response to events detected in the incoming data stream. Importantly, these modules can be built and shared as plugins, which makes it possible for users to extend the functionality of the GUI through a simple API, without having to understand the inner workings of the entire application.

MAIN RESULTS

In combination with low-cost, open-source hardware for amplifying and digitizing neural signals, the GUI has been used for closed-loop experiments that perturb the hippocampal theta rhythm in a phase-specific manner.

SIGNIFICANCE

The Open Ephys GUI is the first widely used application for multichannel electrophysiology that leverages a plugin-based workflow. We hope that it will lower the barrier to entry for electrophysiologists who wish to incorporate real-time feedback into their research.

A Systematic Review and Meta-Analysis of Baseline Ohip-Edent Scores

BACKGROUND

OHIP-EDENT is widely used in the literature to assess Oral-Health-Related-Quality-of-Life (OHRQoL) for edentulous patients. However the normal variance and mean of the baseline OHIP scores has not been reported. It would facilitate critical appraisal of studies if we had knowledge of the normal variation and mean of baseline OHIP-EDENT scores. An established figure for baseline OHIP-EDENT, obtained from a meta-analysis, would simplify comparisons of studies and quantify variations in initial OHRQoL of the trial participants.

OBJECTIVES

The aim of this study is to quantify a normal baseline value for pre-operative OHIP-EDENT scores by a systematic review and meta-analysis of the available literature.

METHODS

A systematic literature review was carried. 83 papers were identified that included OHIP-EDENT values. After screening and eligibility assessment, 7 papers were selected and included in the meta-analysis.

RESULTS

A meta-analysis for the 7 papers by a random-effect model yielded a mean baseline OHIP-EDENT score of 28.63 with a 95% Confidence intervals from 21.93 to 35.34.

CONCLUSION

A pre-operative baseline OHIP-EDENT has been established by meta-analysis of published papers. This will facilitate the comparison of the initial OHRQoL of one study population to that found elsewhere in the published literature.

High-density EEG characterization of brain responses to auditory rhythmic stimuli during wakefulness and NREM sleep

Auditory rhythmic sensory stimulation modulates brain oscillations by increasing phase-locking to the temporal structure of the stimuli and by increasing the power of specific frequency bands, resulting in Auditory Steady State Responses (ASSR). The ASSR is altered in different diseases of the central nervous system such as schizophrenia. However, in order to use the ASSR as biological markers for disease states, it needs to be understood how different vigilance states and underlying brain activity affect the ASSR. Here, we compared the effects of auditory rhythmic stimuli on EEG brain activity during wake and NREM sleep, investigated the influence of the presence of dominant sleep rhythms on the ASSR, and delineated the topographical distribution of these modulations. Participants (14 healthy males, 20-33 years) completed on the same day a 60 min nap session and two 30 min wakefulness sessions (before and after the nap). During these sessions, amplitude modulated (AM) white noise auditory stimuli at different frequencies were applied. High-density EEG was continuously recorded and time-frequency analyses were performed to assess ASSR during wakefulness and NREM periods. Our analysis revealed that depending on the electrode location, stimulation frequency applied and window/frequencies analysed the ASSR was significantly modulated by sleep pressure (before and after sleep), vigilance state (wake vs. NREM sleep), and the presence of slow wave activity and sleep spindles. Furthermore, AM stimuli increased spindle activity during NREM sleep but not during wakefulness. Thus, (1) electrode location, sleep history, vigilance state and ongoing brain activity needs to be carefully considered when investigating ASSR and (2) auditory rhythmic stimuli during sleep might represent a powerful tool to boost sleep spindles.

Microneedle cuff electrodes for extrafascicular peripheral nerve interfacing

OBJECTIVE

The work presented here describes a new tool for peripheral nerve interfacing, called the microneedle cuff (μN-cuff) electrode.

APPROACH

μN arrays are designed and integrated into cuff electrodes for penetrating superficial tissues while remaining non-invasive to delicate axonal tracts.

MAIN RESULTS

In acute testing, the presence of 75 μm height μNs decreased the electrode-tissue interface impedance by 0.34 kΩ, resulting in a 0.9 mA reduction in functional stimulation thresholds and increased the signal-to-noise ratio by 9.1 dB compared to standard (needle-less) nerve cuff electrodes. Preliminary acute characterization suggests that μN-cuff electrodes provide the stability and ease of use of standard cuff electrodes while enhancing electrical interfacing characteristics.

SIGNIFICANCE

The ability to stimulate, block, and record peripheral nerve activity with greater specificity, resolution, and fidelity can enable more precise spatiotemporal control and measurement of neural circuits.

Hard real-time closed-loop electrophysiology with the Real-Time eXperiment Interface (RTXI)

The ability to experimentally perturb biological systems has traditionally been limited to static pre-programmed or operator-controlled protocols. In contrast, real-time control allows dynamic probing of biological systems with perturbations that are computed on-the-fly during experimentation. Real-time control applications for biological research are available; however, these systems are costly and often restrict the flexibility and customization of experimental protocols. The Real-Time eXperiment Interface (RTXI) is an open source software platform for achieving hard real-time data acquisition and closed-loop control in biological experiments while retaining the flexibility needed for experimental settings. RTXI has enabled users to implement complex custom closed-loop protocols in single cell, cell network, animal, and human electrophysiology studies. RTXI is also used as a free and open source, customizable electrophysiology platform in open-loop studies requiring online data acquisition, processing, and visualization. RTXI is easy to install, can be used with an extensive range of external experimentation and data acquisition hardware, and includes standard modules for implementing common electrophysiology protocols.

Kilohertz frequency nerve block enhances anti-inflammatory effects of vagus nerve stimulation

Efferent activation of the cervical vagus nerve (cVN) dampens systemic inflammatory processes, potentially modulating a wide-range of inflammatory pathological conditions. In contrast, afferent cVN activation amplifies systemic inflammatory processes, leading to activation of the hypothalamic-pituitary-adrenal (HPA) axis, the sympathetic nervous system through the greater splanchnic nerve (GSN), and elevation of pro-inflammatory cytokines. Ideally, to clinically implement anti-inflammatory therapy via cervical vagus nerve stimulation (cVNS) one should selectively activate the efferent pathway. Unfortunately, current implementations, in animal and clinical investigations, activate both afferent and efferent pathways. We paired cVNS with kilohertz electrical stimulation (KES) nerve block to preferentially activate efferent pathways while blocking afferent pathways. Selective efferent cVNS enhanced the anti-inflammatory effects of cVNS. Our results demonstrate that: (i) afferent, but not efferent, cVNS synchronously activates the GSN in a dose-dependent manner; (ii) efferent cVNS enabled by complete afferent KES nerve block enhances the anti-inflammatory benefits of cVNS; and (iii) incomplete afferent KES nerve block exacerbates systemic inflammation. Overall, these data demonstrate the utility of paired efferent cVNS and afferent KES nerve block for achieving selective efferent cVNS, specifically as it relates to neuromodulation of systemic inflammation.

Differential fiber-specific block of nerve conduction in mammalian peripheral nerves using kilohertz electrical stimulation

Kilohertz electrical stimulation (KES) has been shown to induce repeatable and reversible nerve conduction block in animal models. In this study, we characterized the ability of KES stimuli to selectively block specific components of stimulated nerve activity using in vivo preparations of the rat sciatic and vagus nerves. KES stimuli in the frequency range of 5-70 kHz and amplitudes of 0.1-3.0 mA were applied. Compound action potentials were evoked using either electrical or sensory stimulation, and block of components was assessed through direct nerve recordings and muscle force measurements. Distinct observable components of the compound action potential had unique conduction block thresholds as a function of frequency of KES. The fast component, which includes motor activity, had a monotonically increasing block threshold as a function of the KES frequency. The slow component, which includes sensory activity, showed a nonmonotonic block threshold relationship with increasing KES frequency. The distinct trends with frequency of the two components enabled selective block of one component with an appropriate choice of frequency and amplitude. These trends in threshold of the two components were similar when studying electrical stimulation and responses of the sciatic nerve, electrical stimulation and responses of the vagus nerve, and sensorimotor stimulation and responses of the sciatic nerve. This differential blocking effect of KES on specific fibers can extend the applications of KES conduction block to selective block and stimulation of neural signals for neuromodulation as well as selective control of neural circuits underlying sensorimotor function.

A randomized, open labeled, comparative study to assess the efficacy and safety of controller medications as add on to inhaled corticosteroid and long-acting β2 agonist in the treatment of moderate-to-severe persistent asthma

BACKGROUND

The goal of asthma therapy is to achieve clinical control and near normal lung functions. Many patients with persistent asthma fail to achieve this goal with a single controller medication add on to a inhaled corticosteroid. We have checked whether another controller medication add on to inhaled corticosteroid and long-acting β2 agonist helps in achieving the asthma goal or not.

OBJECTIVES

To identify the effect of controller medication add on to inhaled corticosteroid and the long-acting β2 agonist on the clinical symptom, lung function, and compliance in patients with asthma.

MATERIALS AND METHODS

We conducted a randomized, open-labeled, comparative trial in 50 participants with moderate-to-severe persistent asthma. The study duration was of 10 weeks. During the first two weeks of the run-in period all the participants received a dry powder inhaler drug delivery of budesonide (400 mcg/day) and formoterol (12 mcg/day) combination. At the end of the run-in period the participants were randomly allocated into three groups: group A (n = 16) received oral montelukast (10 mg/day); group B (n = 17) received oral doxophylline (400 mg/day), and group C (n = 17) received inhaled budesonide (400 mcg) as add on to the above-mentioned drugs of the run-in period. The primary outcome was improvement in forced expiratory volume at 1 second (FEV1 ).

RESULTS

All the participants of the three groups had significant improvement in FEV1 (P < 0.001) and asthma symptoms at the end of 10 weeks. The mean increase in FEV1 (% of predicted) from the baseline, in groups A, B, and C was: 24.6; 21.33, and 19.86%, respectively.

CONCLUSIONS

All add on controller medications helped, with a significant improvement of lung functions and asthma symptoms.

Cutaneous melanoma in a patient with neurofibromatosis

Although neurofibromatosis and cutaneous melanoma are both diseases of neuroectodermal origin, reports of their association are rare. The case history of a patient with histologically documented neurofibromatosis and a nodular melanoma unrelated to a cafe-au-lait spot or congenital nevus is reported, and the literature reviewed. The appearance of only one patient with neurofibromatosis in a series of 900 patients with melanoma suggests that these diseases are probably not associated with greater frequency than that predicted by chance alone.

The phase II evaluation of Bacillus Calmette-Guerin plus megestrol acetate in patients with metastatic renal adenocarcinoma

The case is reported of a patient with pulmonary metastases from a renal adenocarcinoma who experienced subjective improvement and objective tumor regression on Bacillus Calmette-Guerin (BCG) and megestrol acetate therapy. In a subsequent Phase II trial, no objective responses were noted among 15 patients treated with megestrol acetate (160 mg/day X 56 days) and BCG (five immunizing doses intradermally, every 2 weeks X 5). It is concluded that this treatment regimen is not clinically useful in patients with metastatic renal adenocarcinoma.