EWOD driven cleaning of bioparticles on hydrophobic and superhydrophobic surfaces.

Environmental air monitoring is of great interest due to the large number of people concerned and exposed to different possible risks. From the most common particles in our environment (e.g. by-products of combustion or pollens) to more specific and dangerous agents (e.g. pathogenic micro-organisms), there are a large range of particles that need to be controlled. In this article we propose an original study on the collection of electrostatically deposited particles using electrowetting droplet displacement. A variety of particles were studied, from synthetic particles (e.g. Polystyrene Latex (PSL) microsphere) to different classes of biological particle (proteins, bacterial spores and a viral simulant). Furthermore, we have compared ElectroWetting-On-Dielectric (EWOD) collecting efficiency using either a hydrophobic or a superhydrophobic counter electrode. We observe different cleaning efficiencies, depending on the hydrophobicity of the substrate (varying from 45% to 99%). Superhydrophobic surfaces show the best cleaning efficiency with water droplets for all investigated particles (MS2 bacteriophage, BG (Bacillus atrophaeus) spores, OA (ovalbumin) proteins, and PSL).

Electrowetting and droplet impalement experiments on superhydrophobic multiscale structures.

The reversible actuation of droplets on superhydrophobic surfaces under ambient conditions is currently an important field of research due to its potential applicability in microfluidic lab-on-a-chip devices. We have recently shown that Si-nanowire (NW) surfaces allow for reversible actuation provided that the surface structures show certain characteristics. In particular it appears that, for such surfaces, the presence of structures with multiple specific length scales is indeed needed to have a robust reversibility of contact angle changes. Here we report on electrowetting (EW) and impalement experiments on double-scale structured surfaces prepared by a combination of silicon micropillars prepared by an association of optical lithography and silicon etching, and nanowire growth on top of these surfaces. We show that while micropillar surfaces have a low impalement threshold and irreversible EW behaviour, a surface with double-scale texture can show both a very high resistance to impalement and a limited reversibility under EW, provided that the roughness of the micro-scale is large enough--i.e. that the pillars are tall enough. The optimal performance is obtained for a space between pillars that is comparable to the height of the nanostructure.

[The main tunnel syndromes]. / Les principaux syndromes canalaires.

Several tunnel syndromes are responsible for substantial functional impairment. The diagnosis has to be made and treatment is most often very simple--nerve decompression--with excellent results. Of these syndromes, the most common are median and ulnar tunnel syndromes of the wrist and ulnar tunnel syndrome of the elbow, but other syndromes must be identified at the risk of therapy failure due to poorly adapted treatment. Finally, good knowledge of this pathology must lead to prevention of the iatrogenic forms (sequelae of inguinal hernia treatment, ileac crest graft harvesting) by educating all surgeons interested in peripheral nerve surgery.

[Anatomic bases of surgical approaches to the nerves of the lower limb: tips for young surgeons]. / Bases anatomiques des voies d'abord chirurgicales des nerfs du membre inférieur: à l'usage des jeunes neurochirurgiens.

For trainee surgeons, the surgical approaches of the lower limb's peripheral nerves remain partially or completely unknown, but traumatic nerve lesions are rather frequent at this level and nerve tumors require intervention. Young surgeons will also have to treat spasticity and perform selective neurotomies, which can provide dramatic improvement of the functional status of properly selected patients. Excellent knowledge of anatomy is the key point to successful surgery. For each nerve approach, the key points on the morphological data of the nerve and its surroundings are given, as are the typical indications for this surgery and certain particularities related to patient installation in the operating room. The surgical approach section details the incision, the nerve exposure and the technical pitfalls.

[Peripheral nerve tumors]. / Tumeurs des nerfs périphériques.

Peripheral nerve tumors are most often benign tumors of the nerve sheath; uncommonly they come from the nerve cells or are metastatic tumors. A precise diagnosis is required for well-adapted and effective treatment, as is good knowledge of fibromatosis diseases. In some cases, the diagnosis of the nerve tumor will lead to a diagnosis of phakomatosis. Surgical treatment must be clearly discussed, which, in case of schwannomas gives very good functional results. Primitive malignant tumors remain an unsolved therapeutic problem.

[Anatomic bases of surgical approaches to the nerves of the upper limb: tips for young surgeons]. / Bases anatomiques des voies d'abord chirurgicales des nerfs du membre supérieur: à l'usage des jeunes neurochirurgiens.

Peripheral nerve surgery requires a certain level of specialization. Surgeons must have solid knowledge of morphological anatomy of the different segments to be explored, decompressed, repaired, or even neurotized. This paper describes the most common approaches to the peripheral nerves of the upper limb.

[Review of the peripheral nerve]. / Rappels sur le nerf périphérique.

The peripheral nerve provides the pathway for motor, sensory, and vegetative axons belonging to the peripheral nervous system. It transmits information between these neurons and their peripheral effectors in both directions (sensory receptors, skeletal muscles, and viscera). The afferences to the periphery correspond to the nerve motor content, whereas efferences from the periphery, in charge of delivering information to the central integrators, correspond to nerve-sensitive content. This information support depends on the intrinsic properties of the nerve itself. Peripheral nerve injuries are frequent and generate significant deficits. Their treatment sometimes leads to functional recovery but is mostly incomplete or unpredictable, despite the regular use of sophisticated repair techniques. The clinician must clearly understand the peripheral nervous system's responses to injury, which reveal surprising degenerating and spontaneous regenerating abilities. This potential recovery is a peripheral nervous system specificity and follows a relatively complex process. Peripheral neurons depend on glial cell structure and metabolism, inducing the global and dynamic response of the whole axon environment, even in cases of focal lesion, modulated by the initial type and mechanism of injury. Today's progress remains insufficient to improve functional prognosis significantly, but a better understanding of peripheral nerve regenerating processes obtained in cellular and molecular biology has opened the door to new medical and surgical advances.

[Physiology of the injured peripheral nerve]. / Physiologie du nerf traumatisé.

Peripheral nerve injuries are frequent and generate significant deficits. Their treatment sometimes leads to functional recovery but is mostly incomplete or unpredictable, despite the regular use of sophisticated repair techniques. The clinician must clearly understand the peripheral nervous system's responses to injury, which reveal surprising degenerating and spontaneous regenerating abilities. This potential recovery is a peripheral nervous system specificity and follows a relatively complex process. Peripheral neurons depend on glial cell structure and metabolism, inducing a global and dynamic response of the whole axon environment, even in cases of focal lesion, modulated by the initial type and mechanism of injury. Today's progress remains insufficient to improve functional prognosis significantly, but a better understanding of peripheral nerve regenerating processes has opened the door to new medical and surgical advances.

[Pathophysiological, molecular and metabolic changes at the neuromuscular junction and the peripheral nerve after central nervous system lesions in humans]. / Caractérisation physiopathologique, moléculaire et métabolique de la jonction neuromusculaire et du nerf périphérique après lésion du système nerveux central chez l'homme.

From the elaborate information processing that takes place in the brain to the contraction of skeletal muscles, the neurotransmission pathways involve, at least in part, (1) in tissue, Na+, K+-ATPase electrogenesis making action potential (AP) propagation possible and (2) in the cell, the synthesis, maturation, and renewal of an amazing number of molecules concentrated at the neuromuscular junction (NMJ). Our aim is to clarify CNS and peripheral nerve system (PNS) interactions by determining whether the partial motor recovery sometimes observed after a lesion of the first motoneuron is related to (1) changes in active transportation of the ions in peripheral nerve and/or muscle and (2) morphological and/or molecular changes at the NMJ, illustrating a dysfunction. Peripheral nerve surgery is proposed to some spastic patients who have recovered partially after CNS lesions to improve their gait. During these surgical procedures, the nerve and muscle samples that are usually resected can be collected and analyzed. Here, we report on eight patients who showed strictly similar motor recovery 2 years after massive CNS lesions and who underwent a selective tibial neurotomy for a spastic equinus foot. In these eight spastic patients, we performed a pathophysiological, molecular, and metabolic study of their neuromuscular junctions and peripheral nerves to characterize the dysfunction of the neuromuscular transmission after a permanent CNS injury.

[The anatomical substrate of muscle contractility]. / Le support anatomique de la contraction musculaire.

Muscle fiber action participates in a true contractile machinery associated with noncontractile components providing mechanical stability. The myofibril, the muscle fiber subentity, has an extremely consistent architecture, composed of longitudinal cylindrical units called sarcomeres, the skeletal muscle length functional unit, a highly important place in the transduction of chemical signal into mechanical contractile energy, for the most part mediated by calcium. The sarcoplasmic reticulum is the other major component of muscle fiber and is dedicated to calcium storage, liberation and distribution to the fiber, under the influence of action potential propagation. This phenomenon is called excitation-contraction coupling. This paper explores muscle anatomy from its main embryologic stages of development to its histochemical specificity, including its molecular constitution, and details the main morphofunctional relations supporting muscle contraction.

[Retrospective study of the long-term results of selective peripheral neurotomy for the treatment of spastic upper limb]. / Etude rétrospective du résultat à long terme des neurotomies sélectives périphériques dans le traitement du membre supérieur spastique.

BACKGROUND/OBJECTIVE: Peripheral selective neurotomy is commonly used to treat the equinus spastic foot (tibial nerve), but is less frequently used in treating upper limb spasticity, because of the complexity of the articular deformities and the complex innervations of the different muscles. We present our experience and the long-term results of this surgery based on a retrospective series of 22 patients with a disabling spasticity of the upper limb. METHODS: Between 2003 and 2006, neurotomies were performed in 22 patients with disabling spasticity of the upper limb despite optimal medical treatment. Patients were evaluated before and after the surgical procedure. Twelve clinical parameters were studied for describing deformity (resting position and amplitude of each joint), spasticity (Ashworth and Tardieu scores), and the functional impacts of the spasticity. RESULTS: At long-term follow-up, all parameters were improved from the surgery, both in terms of spastic symptoms (highly significantly decreased in Ashworth and Tardieu scores) and the deformity of the upper limb (e.g., 60 degrees increase in the extension of the elbow). Pain, active amplitude, and functional impact scores were also statistically significantly improved after surgery. The mean satisfaction index was 7/10 (+/-1.6). CONCLUSIONS: Selective neurotomy is an effective treatment for patients with a disabling and excessive spasticity in the upper limb. It provides a long-term, objective improvement based on analytical and functional parameters. We emphasize the importance of accurate clinical evaluation and surgical planning. Finally, excessive time to treatment seems to be an important factor for recurrence or incomplete efficiency of the procedure.

[Mechanisms controlling axonal sprouting at the neuromuscular junction]. / Mécanismes contrôlant le bourgeonnement axonal à la jonction neuromusculaire.

This paper explores the specific roles of sprouting stimuli, perisynaptic Schwann cells and neuromuscular activity in axonal sprouting at the neuromuscular junction in partially denervated muscles. As for sprouting stimuli, insulin-like growth factor II which is generated from inactive muscle fibers in partially denervated and paralysed skeletal muscle is described. Likewise, perisynaptic Schwann cells can induce and guide axonal sprouting in partially denervated muscles. Finally, excessive neuromuscular activity significantly reduces bridging of the perisynaptic Schwann cell processes between denervated and innervated endplates and thereby inhibits axonal sprouting in partially denervated muscle. The lack of neuromuscular activity is also harmful in axonal sprouting, probably by impeding calcium influx into the nerve.

[Synapse formation and regeneration]. / Formation et régénération synaptique.

Synapse formation is probably the key process in neural development allowing signal transmission between nerve cells. As an interesting model of synapse maturation, we considered first the neuromuscular junction (NMJ), whose development is particularly dependent on intercellular interactions between the motor nerve and the skeletal muscle. Nerve and muscle have distinct roles in synaptic compartment differentiation. The initial steps of this differentiation and motor endplate formation require several postsynaptic molecular agents including agrin, the tyrosine kinase receptor MuSK and rapsyn. The agrin or motoneuron dependence of this process continues to be debated while the following steps of axonal growth and postsynaptic apparatus maintenance essentially depend on neuronal agrin and a neuron-specific signal dispersing ectopic AChR aggregate remainders, possibly mediated by acetylcholine itself. Neuregulin is essentially involved in Schwann's cell survival and guidance for axonal growth. In this paper, we will discuss the similarities between Central Nervous System (CNS) synaptic formation and Motor innervation. The limited ability of the CNS to create new synapses after nervous system injury will be then discussed with a final consideration of some new strategies elaborated to circumvent the limitations of lesion extension processes.

[Energetic applications: Na+/K+-ATPase and neuromuscular transmission]. / Applications énergétiques: Na/K-ATPase et transmission neuromusculaire.

Na/K-ATPase electrogenic activity and its indispensable role in maintaining gradients suggest that the modifications in isoform distribution and the functioning of the sodium pump have a major influence on both the neuronal functions, including excitability, and motor efficiency. This article proposes to clarify the involvement of Na/K-ATPase in the transmission of nerve influx within the peripheral nerve and then in the genesis, the maintenance, and the physiology of muscle contraction by comparing the data found in the literature with our work on neuron and muscle characterization of Na/K-ATPase activity and isoforms.

[Toward a metabolic approach of the central pattern generator concept in a spinal rat model]. / Vers une approche métabolique du centre locomoteur autonome chez l'animal: le modèle d'hémisection médullaire chez le rat.

It has been shown that the onset of a central nervous system lesion in the rat results in morphological modifications of the peripheral nerves and the underlying neuromuscular junctions, without suggesting a functional correlation between recuperation of motor functions and sublesional metabolic activity. Using double lesion localization (T2 and T6) in a spinal rat model has nevertheless pointed out the functional importance of the T2-T6 metameric interval in the reinnervation phenomena observed, raising the problem of spinal generation in locomotor movements. Motivated by electrophysiological data that have given support to the concept of an anatomic substrate for these intramedullary rhythm generators, we attempted to establish a relation between the functional recuperation possible after a central nervous system lesion and modifications within the metabolism of the underlying neuromuscular system. We notably focused on Na/K-ATPase, whose crucial role in neuromuscular transmission has been evidenced. This paper proposes to demonstrate the involvement in the mechanisms of metabolic regulation after trans-synaptic denervation, i.e., a central nervous system lesion. Our study includes the Na/K-ATPase activity analysis on the sublesional peripheral nerve and the combined analysis of the expression of different RNA messengers within the corresponding muscle groups. We have also investigated the spatiotemporal organization of the compensating processes of the nerves underlying the lesion using magnetic resonance spectroscopy.

[Structural and molecular organization, development and maturation of the neuromuscular junction]. / Organisation structurale, moléculaire, formation et maturation de la jonction neuromusculaire.

The neuromuscular junction is made up of the apposition of highly differentiated domains of three types of cell: the motor neuronal ending, the terminal Schwann cell and the muscle postsynaptic membrane. These three components are surrounded by a basal lamina, dedicated to molecular signal exchanges controlling neuromuscular formation, maturation and maintenance. This functional and structural differentiated complex conducts synaptic neurotransmission to the skeletal muscle fiber. Nerve and muscle have distinct roles in synaptic compartment differentiation. The initial steps of this differentiation and the motor endplate formation require several postsynaptic molecular agents including agrin, the tyrosine kinase receptor MuSK. Neuregulin is essentially involved in Schwann cell survival and guidance for axonal growth.

[Molecular architecture of the sarcoplasmic reticulum and its role in the ECC]. / Architecture moléculaire du réticulum sarcoplasmique et son rôle dans le couplage excitation-contraction.

The sarcoplasmic reticulum (SR) plays a fundamental role in excitation-contraction coupling, which propagates the electric signal conversion along the muscle fiber's plasmic membrane to a mechanical event manifested as a muscle contraction. It plays a crucial role in calcium homeostasis and intracellular calcium storage control (storage, liberation and uptake) necessary for fiber muscle contraction and then relaxation. These functions take place at the triad, made up of individualized SR subdomains where the protein-specific organization provides efficient and fast coupling. Ryanodine receptors (RyR) and dihydropyridine receptors (DHPR) mainly act in calcium exchanges in the SR. This particular structural and molecular architecture must be correlated to its functional specificity.

[Medical and economic reflections on Restore and Itrel neurostimulation systems for neuropathic pain treatment]. / Réflexion sur l'intérêt médicoéconomique des boîtiers de neurostimulation Restore et Itrel dans le traitement des douleurs neuropathiques chroniques.

In 2007, four patients where implanted with the Restore neurostimulation system for intractable chronic leg pain at the Poitiers Hospital. The potential for improving the patients' quality of life and medical-economic concerns motivated this choice for these highly selected patients. In this paper, we propose brief clinical case reports and discuss the reasons for choosing this new rechargeable system, even though it was initially more expensive than the standard neurostimulation system (Itrel 3). All patients receiving implants declared that they were very satisfied with the quality of stimulation provided by Restore and noted a significant improvement in their quality of life. If this solution becomes advantageous from an economic point of view, clinical data should lend support to the utility of this technological innovation for patients who have hitherto been in treatment failure.