Neural Stimulation Hardware for the Selective Intrafascicular Modulation of the Vagus Nerve.

The neural stimulation of the vagus nerve is able to modulate various functions of the parasympathetic response in different organs. The stimulation of the vagus nerve is a promising approach to treating inflammatory diseases, obesity, diabetes, heart failure, and hypertension. The complexity of the vagus nerve requires highly selective stimulation, allowing the modulation of target-specific organs without side effects. Here, we address this issue by adapting a neural stimulator and developing an intraneural electrode for the particular modulation of the vagus nerve. The neurostimulator parameters such as amplitude, pulse width, and pulse shape were modulated. Single-, and multi-channel stimulation was performed at different amplitudes. For the first time, a polyimide thin-film neural electrode was designed for the specific stimulation of the vagus nerve. In vivo experiments were performed in the adult minipig to validate to elicit electrically evoked action potentials and to modulate physiological functions, validating the spatial selectivity of intraneural stimulation. Electrochemical tests of the electrode and the neurostimulator showed that the stimulation hardware was working correctly. Stimulating the porcine vagus nerve resulted in spatially selective modulation of the vagus nerve. ECAP belonging to alpha and beta fibers could be distinguished during single- and multi-channel stimulation. We have shown that the here presented system is able to activate the vagus nerve and can therefore modulate the heart rate, diastolic pressure, and systolic pressure. The here presented system may be used to restore the cardiac loop after denervation by implementing biomimetic stimulation patterns. Presented methods may be used to develop intraneural electrodes adapted for various applications.

Decoding bladder state from pudendal intraneural signals in pigs.

Neuroprosthetic devices used for the treatment of lower urinary tract dysfunction, such as incontinence or urinary retention, apply a pre-set continuous, open-loop stimulation paradigm, which can cause voiding dysfunctions due to neural adaptation. In the literature, conditional, closed-loop stimulation paradigms have been shown to increase bladder capacity and voiding efficacy compared to continuous stimulation. Current limitations to the implementation of the closed-loop stimulation paradigm include the lack of robust and real-time decoding strategies for the bladder fullness state. We recorded intraneural pudendal nerve signals in five anesthetized pigs. Three bladder-filling states, corresponding to empty, full, and micturition, were decoded using the Random Forest classifier. The decoding algorithm showed a mean balanced accuracy above 86.67% among the three classes for all five animals. Our approach could represent an important step toward the implementation of an adaptive real-time closed-loop stimulation protocol for pudendal nerve modulation, paving the way for the design of an assisted-as-needed neuroprosthesis.

Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole.

During its orbit around the four million solar mass black hole Sagittarius A* the star S2 experiences significant changes in gravitational potential. We use this change of potential to test one part of the Einstein equivalence principle: the local position invariance (LPI). We study the dependency of different atomic transitions on the gravitational potential to give an upper limit on violations of the LPI. This is done by separately measuring the redshift from hydrogen and helium absorption lines in the stellar spectrum during its closest approach to the black hole. For this measurement we use radial velocity data from 2015 to 2018 and combine it with the gravitational potential at the position of S2, which is calculated from the precisely known orbit of S2 around the black hole. This results in a limit on a violation of the LPI of |ß_{He}-ß_{H}|=(2.4±5.1)×10^{-2}. The variation in potential that we probe with this measurement is six magnitudes larger than possible for measurements on Earth, and a factor of 10 larger than in experiments using white dwarfs. We are therefore testing the LPI in a regime where it has not been tested before.

Uniaxial strain of cultured mouse and rat cardiomyocyte strands slows conduction more when its axis is parallel to impulse propagation than when it is perpendicular.

AIM: Cardiac tissue deformation can modify tissue resistance, membrane capacitance and ion currents and hence cause arrhythmogenic slow conduction. Our aim was to investigate whether uniaxial strain causes different changes in conduction velocity (θ) when the principal strain axis is parallel vs perpendicular to impulse propagation. METHODS: Cardiomyocyte strands were cultured on stretchable custom microelectrode arrays, and θ was determined during steady-state pacing. Uniaxial strain (5%) with principal axis parallel (orthodromic) or perpendicular (paradromic) to propagation was applied for 1 minute and controlled by imaging a grid of markers. The results were analysed in terms of cable theory. RESULTS: Both types of strain induced immediate changes of θ upon application and release. In material coordinates, orthodromic strain decreased θ significantly more (P < .001) than paradromic strain (2.2 ± 0.5% vs 1.0 ± 0.2% in n = 8 mouse cardiomyocyte cultures, 2.3 ± 0.4% vs 0.9 ± 0.5% in n = 4 rat cardiomyocyte cultures, respectively). The larger effect of orthodromic strain can be explained by the increase in axial myoplasmic resistance, which is not altered by paradromic strain. Thus, changes in tissue resistance substantially contributed to the changes of θ during strain, in addition to other influences (eg stretch-activated channels). Besides these immediate effects, the application of strain also consistently initiated a slow progressive decrease in θ and a slow recovery of θ upon release. CONCLUSION: Changes in cardiac conduction velocity caused by acute stretch do not only depend on the magnitude of strain but also on its orientation relative to impulse propagation. This dependence is due to different effects on tissue resistance.

In vitro evaluation of gel-encapsulated adipose derived stem cells: Biochemical cues for in vivo peripheral nerve repair.

Adipose-derived stem cells (ASC) are becoming one of the most exploited cells in peripheral nerve repair. They are fast-growing and able to protect neurons from apoptosis; they can reduce post-injury latency and the risk of muscle atrophy. This study evaluates laminin-loaded fibrin gel as an ASC-carrying scaffold for nerve repair. In vitro, ASC retained their proliferative activity but showed significant increase in proliferation rate when encapsulated in gels with low laminin concentrations (i.e., 1 µg/mL). We observed a linear decrease of ASC proliferation rate with increasing laminin concentration from 1 to 100 µg/mL. We next examined the effect of the ASC-carrying fibrin gels on in vitro dorsal root ganglia (DRG) neurite extension, then in vivo sciatic nerve regeneration in adult rats. The ASC-carrying gel was embedded in 15-mm-long, 1.5-mm-diameter polydimethylsiloxane regenerative conduits for in vivo evaluation. At 8-week post implantation, robust regeneration was observed across the long gap. Taken together, these results suggest ASC-carrying gels are a potential path to improve the efficacy of nerve regeneration through artificial guidance conduits and electrode nerve interfaces.

Identification and characterization of immunodominant linear epitopes on the antigenic region of a serine protease in newborn Trichinella larvae.

An immunodominant serine protease of Trichinella spiralis named NBL1 showed encouraging potential in early diagnosis of trichinellosis in pigs and elicited protective immune responses during infection of animals. To further define serological reagents for diagnostic use, the specific epitopes on NBL protein recognized by the antibody responses of different susceptible hosts need to be defined. The present study described comprehensive mapping of immunodominant linear epitopes in the antigenic region (NBL-C, the C-terminal part of the protein) using various serum samples obtained from three kinds of hosts - pig, wild boar and mice. We identified six peptides which were commonly recognized by sera from pigs experimentally infected with Trichinella and pigs immunized with rNBL1-C; five and four peptides were recognized by sera from wild boars and mice infected with Trichinella, respectively. Three peptides (NBL1-6, -7 and -9) were commonly recognized by antisera in all three hosts, which share the sequence PSSGSRPTYP. We also found that one peptide (NBL1-12) was only recognized by antibodies from pigs immunized with rNBL1-C. The identification of specific epitopes targeted by the host antibody response is important both for understanding the natural response to infection and for the development of subunit vaccines and diagnostic tools for trichinellosis.

A wireless system with stimulation and recording capabilities for interfacing peripheral nerves in rodents.

Considerable progress has been made in the last decade in implantable bioelectronic neurosystems. Yet most neural implants are used in acute and tethered experimental conditions. Here, we present a preliminary prototype of a multichannel system for simultaneous peripheral nerve stimulation and neural recording. The system comprises miniaturized electronics with a total volume of less then 1.4cm3 including a 3.7V battery which is expected to last for 94 days of standby operation or 18 hours of continuous recording and stimulation. Data read-out and device configuration are wireless. Visceral nerves in rodents are interfaced with compliant extraneural electrodes. The 100×350µm2 electrodes display a low impedance (1.8kn at 1kHz) with a PEDOT:PSS coating. We validated the prototype in acute experiments by applying electrical stimulation to the aortic depressor nerve (ADN), resulting in effective and reproducible decrease in blood pressure and heart rate. The combination of miniaturized electronics and flexible electrodes makes the presented system a versatile platform for future implantable devices interfacing small peripheral nerves and potentially enables new applications in the field of neuroscience.

Long-term sensorimotor and therapeutical effects of a mild regime of prism adaptation in spatial neglect. A double-blind RCT essay.

Spatial neglect (SN) is commonly associated with poor functional outcome. Adaptation to a rightward optical deviation of vision has been shown to benefit to SN rehabilitation. The neurophysiological foundations and the optimal modalities of prism adaptation (PA) therapy however remain to be validated. This study is aimed at exploring the long-term sensory-motor, cognitive and functional effects produced by weekly PA sessions over a period of four weeks. A double-blind, monocentric randomized and controlled trial (RCT) was carried out. Twenty patients with left SN secondary to stroke were included, 10 in the "prism" group and 10 in the "control" group. The sensory-motor effects of PA were evaluated by measurement of manual and visual straight-ahead, and also by precision of pointing without visual feedback before and after each PA session. The functional independence measure (FIM) was evaluated before and at 1, 3 and 6 months after PA, while SN severity was assessed using the Behavioural Inattention Test (BIT) before and 6 months after PA. Before the intervention, only manual straight-ahead pointing constituted a reproducible sensory-motor measurement. During prism exposure, a questionnaire showed that not a single patient were aware of the direct effects of optical deviation on pointing movement performance. The sensory-motor after-effects produced by the PA produced a more rapid reduction of the rightward manual straight-ahead, which was secondarily followed by visual straight-ahead. These sensory-motor effects helped to clarify the action mechanisms of PA on SN. At the conclusion of the 6-month follow-up, the two groups showed similar improvement, indicating that a weekly PA session over 4 weeks was not sufficient to produce long-term functional benefit. This improvement was correlated with the evolution of visual straight-ahead, which can be proposed as a marker for patients outcome.

Screening of early antigen genes of adult-stage Trichinella spiralis using pig serum from different stages of early infection.

The goal of this work was to identify novel, early antigens present in Trichinella spiralis. To this end, a cDNA library generated from 3-day old adult worms (Ad3) was immunologically screened using serum from a pig infected with 20,000 muscle larvae. The serum was obtained from multiple, time course bleeds coinciding with early worm development. Seventeen positive clones were isolated using serum obtained at 20 days post infection (dpi). All clones corresponded to one gene that exhibited high sequence identity with the T. spiralis ATP-dependent RNA helicase DDX19B which is involved in parasite growth and development. In addition, nine additional positive clones representing 5 unique genes were identified when the library was screened with 30 dpi serum; four of these five genes displayed high similarity with members of a putative T. spiralis serine protease family known to be involved in host invasion and host-parasite interactions. The remaining gene aligned with the T. spiralis hypothetical ORF 11.30. The identification of these antigens provides potential candidates for the early diagnosis of trichinellosis and for the development of a vaccine against this parasite.

Disseminated sparganosis in a cynomolgus macaque (Macaca fascicularis).

An adult male cynomolgus macaque (Macaca fascicularis) from Mauritius arrived at our facility in France after a 1-year period of quarantine in Spain. Clinical examination soon after arrival revealed the presence of numerous firm cutaneous and subcutaneous nodules (0.1-0.5 cm diameter) in the scrotal and inguinal areas, and persistent mild eosinophilia. On necropsy examination additional similar nodules were found in the peritoneum and abdominal wall, omentum and mesentery. Microscopical examination revealed disseminated eosinophilic granulomas containing tapeworm larvae identified as Spirometra erinaceieuropaei by direct sequencing of the cox1 gene.

Use of an implanted sacral nerve stimulator to restore urine voiding in chronically paraplegic dogs.

BACKGROUND: Loss of urinary control after spinal cord injury increases risk of urinary tract disease and is problematical for owners of affected dogs. OBJECTIVES: To design, implant, and test a sacral nerve stimulating device for controlling urine voiding in paraplegic dogs. ANIMALS: Nine pet dogs with severe thoracolumbar spinal cord injury causing paraplegia, loss of hindquarter sensation, and incontinence for more than 3 months. The procedure was offered prospectively to owners of suitable candidates after the irreversibility of the incontinence had been ascertained. METHODS: Open label clinical study. Surgically implantable electrode "books" were designed for insertion and retention of mixed sacral nerves. Sacral nerves were accessed via laminectomy and stimulated to test their ability to elicit detrusor contraction and then inserted into the electrode book, which was attached to a subcutaneously implanted, externally activated receiver. RESULTS: In 8/9 dogs, S2 nerves elicited the largest increases in intravesicular pressure with minimum stimulation and were placed in electrode books. Voiding efficiency was >90% in 8 of the 9 implanted dogs. No important detrimental effects of the procedure were observed. CONCLUSIONS AND CLINICAL IMPORTANCE: This sacral nerve stimulating implant is a simple and apparently effective neuroprosthetic device that restores urine voiding in paraplegic dogs.

Fabrication and electromechanical characterization of near-field electrospun composite fibers.

We report the use of near-field electrospinning (NFES) as a route to fabricate composite electrodes. Electrodes made of composite fibers of multi-walled carbon nanotubes in polyethylene oxide (PEO) are formed via liquid deposition, with precise control over their configuration. The electromechanical properties of free-standing fibers and fibers deposited on elastic substrates are studied in detail. In particular, we examine the elastic deformation limit of the resulting free-standing fibers and find, similarly to bulk PEO composites, that the plastic deformation onset is below 2% of tensile strain. In comparison, the apparent deformation limit is much improved when the fibers are integrated onto a stretchable, elastic substrate. It is hoped that the NFES fabrication protocol presented here can provide a platform to direct-write polymeric electrodes, and to integrate both stiff and soft electrodes onto a variety of polymeric substrates.

A giant planet imaged in the disk of the young star beta Pictoris.

Here, we show that the approximately 10-million-year-old beta Pictoris system hosts a massive giant planet, beta Pictoris b, located 8 to 15 astronomical units from the star. This result confirms that gas giant planets form rapidly within disks and validates the use of disk structures as fingerprints of embedded planets. Among the few planets already imaged, beta Pictoris b is the closest to its parent star. Its short period could allow for recording of the full orbit within 17 years.

Epidemiological survey of trichinellosis in wild boar (Sus scrofa) and fox (Vulpes vulpes) in a French insular region, Corsica.

The Mediterranean island of Corsica was considered Trichinella-free until 2004, when T. britovi larvae were discovered in domestic pigs at meat inspection. One red fox was also found infected the same year and in the same area than the infected pigs. This last finding highlighted the presence of trichinellosis in Corsican wildlife. A Trichinella survey was thus performed in wild boar (Sus scrofa) and fox (Vulpes vulpes), the two large wild species present on the island, to determine prevalence of muscle larvae and antibodies. Diaphragm muscles of 1881 wild boars and 74 forelegs of foxes were tested by artificial digestion. No Trichinella larva was identified. The highly sensitive ELISA was used to test muscle fluid samples of 1492 wild boars. The apparent serological prevalence of Trichinella infections in wild boar was 2.01% (95% CI: 1.36-2.86). The present results suggest that wildlife is currently exposed to Trichinella in Corsica. In this context, adequate cooking and veterinary controls of meat offer the only complete sanitary warranties to consumers.

Novel use of X-ray micro computed tomography to image rat sciatic nerve and integration into scaffold.

This paper describes how specimens of nervous tissue can be prepared for successful imaging in X-ray Micro Computed Tomography (microCT), and how this method can be used to study the integration of nervous tissue into a polymeric scaffold. The sample preparation involves staining the biological tissue with osmium tetroxide to increase its X-ray attenuation, and a technique for maintaining the specimen in a moist environment during the experiment to prevent drying and shrinkage. Using this method it was possible to observe individual nerve fascicles and their relationship to the 3-D tissue structure. A scaffold supporting a regenerated sciatic nerve was similarly stained to distinguish the nervous tissue from the scaffold, and to observe how the nerve grew through a 2.5 mm long, 100 microm x 100 microm cross-section channel polyimide array. Furthermore, blood vessels could be identified in these images, and it was possible to monitor how a large proximal blood vessel split through the channel scaffold and proceeded down individual channels. This paper explains how microCT is a useful tool both for studying the location and extent of growth into a polymeric scaffold, and for determining whether the regenerated tissue has blood supply.

Pupil remapping for high contrast astronomy: results from an optical testbed.

The direct imaging and characterization of Earth-like planets is among the most sought-after prizes in contemporary astrophysics, however current optical instrumentation delivers insufficient dynamic range to overcome the vast contrast differential between the planet and its host star. New opportunities are offered by coherent single mode fibers, whose technological development has been motivated by the needs of the telecom industry in the near infrared. This paper presents a new vision for an instrument using coherent waveguides to remap the pupil geometry of the telescope. It would (i) inject the full pupil of the telescope into an array of single mode fibers, (ii) rearrange the pupil so fringes can be accurately measured, and (iii) permit image reconstruction so that atmospheric blurring can be totally removed. Here we present a laboratory experiment whose goal was to validate the theoretical concepts underpinning our proposed method. We successfully confirmed that we can retrieve the image of a simulated astrophysical object (in this case a binary star) though a pupil remapping instrument using single mode fibers.

Assessment of the biocompatibility of photosensitive polyimide for implantable medical device use.

Polyimides have been widely used for biosensor encapsulation and more recently as substrates for neural implants. They have excellent thermal stability, high chemical resistance, and can be prepared as thin, flexible films. Photosensitive polyimides present similar physical properties to polyimides, and have the advantage that they can be photo-lithographically patterned. However, to date little data on their biocompatibility has been reported. Two commercially available polyimides (PI) and one photo-sensitive polyimide (PSPI) were evaluated in vitro using the ISO 10993 standard on biocompatibility. The materials were Dupont Kapton foil HN, HD Microsystem PI2611, and Fujifilm Durimide 7020 (PSPI). PI2611 and Durimide 7020 were spin-coated on silicon wafers, cured at temperatures ranging from 150 to 450 degrees C, and sterilized by autoclave. All materials were evaluated using a scanning electron microscope pre- and postcell culture. Cell viability was determined by an MTS assay. Their mechanical properties and stability during cell culture as a function of time and environment were investigated by nanoindentation. The MTS results show that PSPI is noncytotoxic compared with the negative control of polyethylene and the conventional PIs tested. Fibroblast adhesion, morphology, and spreading were good and better on the PSPI substrate than on the PI2611. Schwann cell appearance was similar on each of the PIs and the PSPI tested. The results suggest that PSPIs may have potential use for biological microsystem and neuroprosthetic applications.

Charon's size and an upper limit on its atmosphere from a stellar occultation.

Pluto and its satellite, Charon (discovered in 1978; ref. 1), appear to form a double planet, rather than a hierarchical planet/satellite couple. Charon is about half Pluto's size and about one-eighth its mass. The precise radii of Pluto and Charon have remained uncertain, leading to large uncertainties on their densities. Although stellar occultations by Charon are in principle a powerful way of measuring its size, they are rare, as the satellite subtends less than 0.3 microradians (0.06 arcsec) on the sky. One occultation (in 1980) yielded a lower limit of 600 km for the satellite's radius, which was later refined to 601.5 km (ref. 4). Here we report observations from a multi-station stellar occultation by Charon, which we use to derive a radius, R(C) = 603.6 +/- 1.4 km (1sigma), and a density of rho = 1.71 +/- 0.08 g cm(-3). This occultation also provides upper limits of 110 and 15 (3sigma) nanobar for an atmosphere around Charon, assuming respectively a pure nitrogen or pure methane atmosphere.

Anticancer agents sensitize tumor cells to tumor necrosis factor-related apoptosis-inducing ligand-mediated caspase-8 activation and apoptosis.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a new cytokine that was proposed to specifically induce apoptosis of cancer cells. In tumor cells that are resistant to the cytokine, subtoxic concentrations of chemotherapeutic drugs can restore the response to TRAIL. The present study further explores the mechanisms that determine tumor cell sensitivity to TRAIL by comparing four human colon carcinoma cell lines We show that colon cancer cell sensitivity to TRAIL-induced apoptosis and cytotoxicity correlates with the expression of the death receptors TRAIL-R1 and TRAIL-R2 at the cell surface, as determined by now cytometry, whereas the two decoy receptors TRAIL-R3 and TRAIL-R4 can be detected only in permeabilized cells. Clinically relevant concentrations of cisplatin and doxorubicin sensitize the most resistant colon cancer cell lines to TRAIL-induced cell death without modifying the expression nor the localization of TRAIL receptors in these cells. TRAIL induces the activation of procaspase-8 and triggers caspase-dependent apoptosis off colon cancer cells. Cytotoxic drugs lower the signaling threshold required for TRAIL-induced procaspase-8 activation. In turn, caspase-8 cleaves Bid, a BH3 domain-containing proapoptotic molecule of the Bcl-2 family and activates effector caspases. Together, these data indicate that chemotherapeutic drugs sensitize colon tumor cells to TRAIL-mediated caspase-8 activation and apoptosis.