A tool to facilitate implantation of electrodes for electromyographic telemetry experiments

Conventional techniques for implanting electrodes into axial swimming musculature of fish are reviewed. A new device is described that reduces time for electrode implantation, ensures constancy in electrode orientation, implantation depth, and separation distance. This device is inexpensive, simple to build, and easy to use.     

A Procedure for Implanting Organized Arrays of Microwires for Single-unit Recordings in Awake,Behaving Animals

In vivo electrophysiological recordings in the awake, behaving animal provide a powerful method for understanding neural signaling at the single-cell level. The technique allows experimenters to examine temporally and regionally specific firing patterns in order to correlate recorded action potentials with ongoing behavior. Moreover, single-unit recordings can be combined with a plethora of other techniques in order to produce comprehensive explanations of neural function. In this article, we describe the anesthesia and preparation for microwire implantation. Subsequently, we enumerate the necessary equipment and surgical steps to accurately insert a microwire array into a target structure. Lastly, we briefly describe the equipment used to record from each individual electrode in the array. The fixed microwire arrays described are well-suited for chronic implantation and allow for longitudinal recordings of neural data in almost any behavioral preparation. We discuss tracing electrode tracks to triangulate microwire positions as well as ways to combine microwire implantation with immunohistochemical techniques in order to increase the anatomical specificity of recorded results.     

Large Animal Model for Development of Functional Restoration Paradigms Using Epidural and Intraspinal Stimulation

Restoration of movement following spinal cord injury (SCI) has been achieved using electrical stimulation of peripheral nerves and skeletal muscles. However, practical limitations such as the rapid onset of muscle fatigue hinder clinical application of these technologies. Recently, direct stimulation of alpha motor neurons has shown promise for evoking graded, controlled, and sustained muscle contractions in rodent and feline animal models while overcoming some of these limitations. However, small animal models are not optimal for the development of clinical spinal stimulation techniques for functional restoration of movement. Furthermore, variance in surgical procedure, targeting, and electrode implantation techniques can compromise therapeutic outcomes and impede comparison of results across studies. Herein, we present a protocol and large animal model that allow standardized development, testing, and optimization of novel clinical strategies for restoring motor function following spinal cord injury. We tested this protocol using both epidural and intraspinal stimulation in a porcine model of spinal cord injury, but the protocol is suitable for the development of other novel therapeutic strategies. This protocol will help characterize spinal circuits vital for selective activation of motor neuron pools. In turn, this will expedite the development and validation of high-precision therapeutic targeting strategies and stimulation technologies for optimal restoration of motor function in humans.     

Model-based optimization of a conductive matrix enzyme electrode

A mathematical model has been developed to describe the mechanism for internal mass transfer and enzyme reaction kinetics of an amperometric conductive matrix enzyme electrode. The model is simplified and solved analytically to arrive at a representation for the response slope in the linear range as well as for the response time. This is the first time that the response time of an enzyme electrode is described by a mathematical model. Simulations give information on how the design parameters influence the performance of the electrode for a glucose oxidase catalyzed sensing reaction process. Based on this information, several designs were constructed and tested showing suitable agreement with theoretical predictions. Finally, an optimized electrode was designed and validated.     

Protein modified- and membrane electrodes: strategies for the development of biomolecular sensors

Different procedures used for constructing protein/enzyme-modified electrodes are examined, in particular adsorption, covalent attachment and film deposition. The performances of such modified electrodes with electroactive proteins or enzymes attached to their active surface are examined, especially in the case of c-type cytochromes, hydrogenases and glucose oxidase. Another strategy presented in this review consists of the use of membrane electrodes with an electroactive protein imprisoned between a dialysis membrane and the electrode surface. The versatility and other advantages of such a procedure are underlined. Applications of membrane electrodes to the bioremediation of soils and effluents and as models for investigating interactions between proteins and soils are described.     

Chronic polyelectromyography in awake, unrestrained animals.

A procedure is described for making an implantable electrode array for recording EMG activity in muscles of awake, unrestrained animals (rats and cats) at rest, during rhythmic activity and in response to various reflexogenic stimuli. The electrode array consists of a percutaneous connector (covered with Dow-Corning Silastic Medical Adhesive), steel wire spiral leads contained in silicone tubing and silicone plate probes with platinum electrodes. These plate probes can be fixed either to the bone underneath the muscle, slipped under the fascia, or fixed between muscles. EMG records are presented of postural activity and ambulation in rats, mastication in cats and unilateral and bilateral spinal and supraspinal reflex responses in rat hind limb muscles up to 6 months after implantation. The advantages (and drawbacks) of this technique and its possible uses in neurophysiology are enumerated in the discussion.     

In vivo19F MRI for Cell Tracking

In vivo¹⁹F MRI allows quantitative cell tracking without the use of ionizing radiation. It is a noninvasive technique that can be applied to humans. Here, we describe a general protocol for cell labeling, imaging, and image processing. The technique is applicable to various cell types and animal models, although here we focus on a typical mouse model for tracking murine immune cells. The most important issues for cell labeling are described, as these are relevant to all models. Similarly, key imaging parameters are listed, although the details will vary depending on the MRI system and the individual setup. Finally, we include an image processing protocol for quantification. Variations for this, and other parts of the protocol, are assessed in the Discussion section. Based on the detailed procedure described here, the user will need to adapt the protocol for each specific cell type, cell label, animal model, and imaging setup. Note that the protocol can also be adapted for human use, as long as clinical restrictions are met.     

Decrease in the electrostimulation threshold of the heart by saturating the electrode with glucocorticoids

A pacing electrode with a porous surface saturated with glucocorticoids has been designed in order to diminish the pacing threshold of the heart. The data obtained in animal studies show that saturation of the electrode with dexamethasone before implantation significantly reduces the pacing threshold.     

A new method for the assay of glutaminase activity: direct measurement of product formation by an ammonia electrode

A simple, reliable procedure is described for the quantitative assay of glutaminase reaction by measuring product formation using an ammonia electrode. The ammonia electrode is a gas-detecting electrode, sensing the level of dissolved ammonia in aqueous solutions. Ammonia concentration can be read from calibration curves after converting ammonium ion to ammonia by adding sufficient base. Sample color and turbidity do not affect measurements, and samples need not be distilled. The concentrations of the three glutaminase isoenzymes from rat tissues measured by this method are strictly comparable to those measured by other methods.     

Allogeneic materials in complications associated with pre-implantation restoration of maxillary and mandibular alveolar processes. A four case report

There are numerous types of bone replacement materials used to regenerate atrophic alveolar processes before the elective intraosseous implantation. Properties of these materials differ one from another, therefore the choice of material should be thoroughly analysed as well as its type and texture in regard of intraoral conditions and the objective to be achieved. The study involved reconstruction of atrophic alveolar processes with allogeneic bone following unsuccessful use of synthetic and animal materials. The procedure of bone regeneration was performed with frozen bone block (case 1) and allogeneic bone granulate (cases 2, 3, 4) radiation-sterilised with 35 kGy prepared by the Tissue Bank. In all of the presented cases after 3-month implant reorganisation optimal width of the process was obtained, which allowed implant embedment (case 1) or correct implant submergence in the osseous tissue, when implantation took place at the same time (case 2, 3, 4). Allogeneic bone material both, in the form of a block as well as granulate, seems to be an adequate alternative for other materials used in order to widen the bone of the alveolar process, particularly in difficult, complicated cases, where the first regeneration procedure was not successful.     

Adsorptive transfer stripping voltammetry: Determination of nanogram quantities of DNA immobilized at the electrode surface

In adsorptive transfer stripping voltammetry (AdTSV), DNA is first adsorbed at the electrode, the electrode is washed and transferred (with the adsorbed layer) in the medium not containing DNA, and voltammetric analysis is performed in this medium. Adsorption can be performed from a drop of DNA solution, which makes it possible to reduce the volume of the analyzed sample by two orders of magnitude as compared to that of conventional voltammetry. With the hanging mercury drop electrode the limit of detection of single-stranded DNA is below 0.1 micrograms/ml; thus if the adsorption is performed from a 10-microliter drop of DNA solution subnanogram quantities of single-stranded DNA are sufficient for the analysis. In AdTSV the behavior of single- and double-stranded DNAs markedly differ from each other in a manner similar to that in the conventional voltammetric or polarographic analysis; AdTSV can thus be used in DNA structure analysis. In AdTSV the DNA transport and its adsorption at the electrode are separated from the electrode process; due to this fact it is possible (a) to perform the voltammetric analysis of DNA from media not suitable for voltammetric analysis of the conventional type, (b) to study the interaction of immobilized DNA with other substances in solution without the results of the voltammetric analysis being influenced by DNA interactions in the bulk of solution, and (c) to exploit the differences of adsorbability of DNA and other substances in order to separate them on the electrode.     

Polyploidy in fungi: evolution after whole-genome duplication

Polyploidy is a major evolutionary process in eukaryotes-particularly in plants and, to a less extent, in animals, wherein several past and recent whole-genome duplication events have been described. Surprisingly, the incidence of polyploidy in other eukaryote kingdoms, particularly within fungi, remained largely disregarded by the scientific community working on the evolutionary consequences of polyploidy. Recent studies have significantly increased our knowledge of the occurrence and evolutionary significance of fungal polyploidy. The ecological, structural and functional consequences of polyploidy in fungi are reviewed here and compared with the knowledge acquired with conventional plant and animal models. In particular, the genus Saccharomyces emerges as a relevant model for polyploid studies, in addition to plant and animal models.     

MoS2 Nanosheets Vertically Aligned on Carbon Paper: A Freestanding Electrode for Highly Reversible Sodium‐Ion Batteries

The development of sodium‐ion batteries for large‐scale applications requires the synthesis of electrode materials with high capacity, high initial Coulombic efficiency (ICE), high rate performance, long cycle life, and low cost. A rational design of freestanding anode materials is reported for sodium‐ion batteries, consisting of molybdenum disulfide (MoS₂) nanosheets aligned vertically on carbon paper derived from paper towel. The hierarchical structure enables sufficient electrode/electrolyte interaction and fast electron transportation. Meanwhile, the unique architecture can minimize the excessive interface between carbon and electrolyte, enabling high ICE. The as‐prepared MoS₂@carbon paper composites as freestanding electrodes for sodium‐ion batteries can liberate the traditional electrode manufacturing procedure, thereby reducing the cost of sodium‐ion batteries. The freestanding MoS₂@carbon paper electrode exhibits a high reversible capacity, high ICE, good cycling performance, and excellent rate capability. By exploiting in situ Raman spectroscopy, the reversibility of the phase transition from 2H‐MoS₂ to 1T‐MoS₂ is observed during the sodium‐ion intercalation/deintercalation process. This work is expected to inspire the development of advanced electrode materials for high‐performance sodium‐ion batteries.     

Mutant mice: Experimental organisms as materialised models in biomedicine

Animal models have received particular attention as key examples of material models. In this paper, we argue that the specificities of establishing animal models—acknowledging their status as living beings and as epistemological tools—necessitate a more complex account of animal models as materialised models. This becomes particularly evident in animal-based models of diseases that only occur in humans: in these cases, the representational relation between animal model and human patient needs to be generated and validated. The first part of this paper presents an account of how disease-specific animal models are established by drawing on the example of transgenic mice models for Alzheimer’s disease. We will introduce an account of validation that involves a three-fold process including (1) from human being to experimental organism; (2) from experimental organism to animal model; and (3) from animal model to human patient. This process draws upon clinical relevance as much as scientific practices and results in disease-specific, yet incomplete, animal models. The second part of this paper argues that the incompleteness of models can be described in terms of multi-level abstractions. We qualify this notion by pointing to different experimental techniques and targets of modelling, which give rise to a plurality of models for a specific disease.     

Computational Tissue Volume Reconstruction of a Peripheral Nerve Using High-Resolution Light-Microscopy and Reconstruct

The development of neural cuff-electrodes requires several in vivo studies and revisions of the electrode design before the electrode is completely adapted to its target nerve. It is therefore favorable to simulate many of the steps involved in this process to reduce costs and animal testing. As the restoration of motor function is one of the most interesting applications of cuff-electrodes, the position and trajectories of myelinated fibers in the simulated nerve are important. In this paper, we investigate a method for building a precise neuroanatomical model of myelinated fibers in a peripheral nerve based on images obtained using high-resolution light microscopy. This anatomical model describes the first aim of our “Virtual workbench” project to establish a method for creating realistic neural simulation models based on image datasets. The imaging, processing, segmentation and technical limitations are described, and the steps involved in the transition into a simulation model are presented. The results showed that the position and trajectories of the myelinated axons were traced and virtualized using our technique, and small nerves could be reliably modeled based on of light microscopy images using low-cost OpenSource software and standard hardware. The anatomical model will be released to the scientific community.     

Adrenal gland modulates oestrogen requirement for implantation in the rat

The effect of adrenal steroids upon implantation was evaluated by examining the efficacy of oestradiol-17 beta on the initiation of implantation in ovariectomized, ovariectomized plus adrenalectomized or hypophysectomized pregnant rats treated with progesterone. More oestrogen (X 5) was required in ovariectomized animals to obtain results equivalent to those obtained with the other animal models.     

Analysis of Ion‐Diffusion‐Induced Interface Degradation in Inverted Perovskite Solar Cells via Restoration of the Ag Electrode

Straightforward evidence for ion‐diffusion‐induced interfacial degradation in inverted perovskite solar cells is presented. Over 1000 h, solar cells inevitably undergo degradation, especially with respect to the current density and fill factor. The Ag electrode is peeled off and re‐evaporated to investigate the effect of the Ag/[6,6]‐phenyl C71 butyric acid methyl ester (PCBM) interfacial degradation on the photovoltaic performance at days 10 (240 h), 20 (480 h), 30 (720 h), and 40 (960 h). The power conversion efficiency increases after the Ag electrode restoration process. While the current density shows a slightly decreased value, the fill factor and open‐circuit voltage increase for the new electrode devices. The decrease in the activation energy due to the restored Ag electrode induces recovery of the fill factor. The diffused I^? ions react with the PCBM molecules, resulting in a quasi n‐doping effect of PCBM. Upon electrode exchange, the reversible interaction between the iodine ions and PCBM causes current density variation. The disorder model for the open‐circuit voltage over a wide range of temperatures explains the open‐circuit voltage increase at every electrode exchange. Finally, the degradation mechanism of the inverted perovskite solar cell over 1000 h is described under the proposed recombination system.     

Ultrasound-guided insertion of intramuscular electrodes into suboccipital muscles in the non-human primate

The head-neck system is highly complex from a biomechanical and musculoskeletal perspective. Currently, the options for recording the recruitment of deep neck muscles in experimental animals are limited to chronic approaches requiring permanent implantation of electromyographic electrodes. Here, we describe a method for targeting deep muscles of the dorsal neck in non-human primates with intramuscular electrodes that are inserted acutely. Electrode insertion is guided by ultrasonography, which is necessary to ensure placement of the electrode in the target muscle. To confirm electrode placement, we delivered threshold electrical stimulation through the intramuscular electrode and visualized the muscle twitch. In one animal, we also compared recordings obtained from acutely- and chronically-implanted electrodes. This method increases the options for accessing deep neck muscles, and hence could be used in experiments for which the invasive surgery inherent to a chronic implant is not appropriate. This method could also be extended to the injection of pharmacological agents or anatomical tracers into specific neck muscles.     

提高1，1’-二甲基二茂铁石墨糊谷氨酸电极寿命的研究

自从Cass1984年首先报道了二茂铁介铁电极以来,已有不少文献报道了这方面的研究工作。还原态的二茂铁不溶于水,而氧化态的二茂铁却溶于水。这样介体电极在使用过程中会因介体的逐渐丢失而失去作用。为了提高介体的稳定性,已报道了多种方法。 提高酶膜的稳定性是生物传感器研制中的一个重要方面。以前一般采用改进固定化方法与选择固定化载体来提高酶膜的稳定性。本文将报道用DEAE-葡聚糖提高DcFe介体电极稳定性的新方法与用DEAE-葡聚糖和乳糖混合物稳定自产的谷氨酸氧化酶的研究结果。