Selectivity in the Reinnervation of the Lateral Gastrocnemius Muscle after Nerve Repair with Ethyl Cyanoacrylate in the Rat

There is a need for complementary surgical techniques that enable rapid and reliable primary repair of transected nerves. Previous studies after peripheral nerve transection and repair with synthetic adhesives have demonstrated regeneration to an extent comparable to that of conventional techniques. The aim of this study was to compare two different repair techniques on the selectivity of muscle reinnervation after repair and completed regeneration. We used the cholera toxin B technique of retrograde axonal tracing to evaluate the morphology, the number, and the three-dimensional location of α-motoneurons innervating the lateral gastrocnemius muscle and compared the results after repair with either ethyl cyanoacrylate (ECA) or epineural sutures of the transected parent sciatic nerve. In addition, we recorded the wet weight of the muscle. Six months after transection and repair of the sciatic nerve, the redistribution of the motoneuron pool was markedly disorganized, the motoneurons had apparently increased in number, and they were scattered throughout a larger volume of the spinal cord gray matter with a decrease in the synaptic coverage compared to controls. A reduction in muscle weight was observed as well. No difference in morphometric variables or muscle weight between the two repair methods could be detected. We conclude that the selectivity of motor reinnervation following sciatic nerve transection and subsequent repair with ECA is comparable to that following conventional micro suturing

Expression of Semaphorins, Neuropilins, VEGF, and Tenascins in Rat and Human Primary Sensory Neurons after a Dorsal Root Injury

Dorsal root injury is a situation not expected to be followed by a strong regenerative growth, or growth of the injured axon into the central nervous system of the spinal cord, if the central axon of the dorsal root is injured but of strong regeneration if subjected to injury to the peripherally projecting axons. The clinical consequence of axonal injury is loss of sensation and may also lead to neuropathic pain. In this study, we have used in situ hybridization to examine the distribution of mRNAs for the neural guidance molecules semaphorin 3A (SEMA3A), semaphorin 3F (SEMA3F), and semaphorin 4F (SEMA4F), their receptors neuropilin 1 (NP1) and neuropilin 2 (NP2) but also for the neuropilin ligand vascular endothelial growth factor (VEGF) and Tenascin J1, an extracellular matrix molecule involved in axonal guidance, in rat dorsal root ganglia (DRG) after a unilateral dorsal rhizotomy (DRT) or sciatic nerve transcetion (SNT). The studied survival times were 1-365 days. The different forms of mRNAs were unevenly distributed between the different size classes of sensory nerve cells. The results show that mRNA for SEMA3A was diminished after trauma to the sensory nerve roots in rats. The SEMA3A receptor NP1, and SEMA3F receptor NP2, was significantly upregulated in the DRG neurons after DRT and SNT. SEMA4F was upregulated after a SNT. The expression of mRNA for VEGF in DRG neurons after DRT showed a significant upregulation that was high even a year after the injuries. These data suggest a role for the semaphorins, neuropilins, VEGF, and J1 in the reactions after dorsal root lesions

Spinal motoneurons and molecules related to neurotrophic function after axon injury

The capacity of motoneurons to survive and regenerate new axons after injuries such as axotomy depends on a great variety of parameters. After sciatic nerve transection (SNT) in adult rats and to some extent after a ventral funiculus lesion (VFL), many cells survive and regeneration is highly prioritated. After SNT in neonatal rats or ventral root avulsion (VRA) in adult rats, on the other hand, a large proportion of the lesioned cells die and overall chances of regeneration are small. Differences in protein expression patterns of trophic factors, their receptors and receptors to extracellular matrix molecules, integrins, were studied in motoneurons and sear tissue after the mentioned types of injury. The effect of infiltrating inflammatory cells and substances produced by such cells was studied on rat motoneurons in vivo and in cell cultures, with the aim to determine some of the factors that have an influence on the outcome of the injured motoneuron. In all lesion models the expression of mRNA encoding growth-associated protein (GAP-43) was highly upregulated. Alpha-CGRP was downregulated in response to a SNT in newborn rats, but was upregulated in two week old and in adult rats. GAP-43 and CGRP mRNA expressions in spinal motoneurons are regulated, at least in part, by target-derived factors like CNTF and bFGF and may be nerve cell-derived substances that are involved in sprouting and regulation of neuromuscular junctions during development and regeneration. The trophic factors glial cell-line derived neurotrophic factor (GDNF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF) and insulin-like growth factors (IGF-1 and -2) have been shown to be crucial for survival and regeneration of spinal motoneurons after various kinds of axotomy and in vitro. The mRNA expression in transected sciatic nerve was correlated to the regulation of their receptor subunits in spinal motoneurons and compared in the different lesion models. GDNF receptor alpha (GFR[alpha]1), c-RET and LIF receptor (LIFR) mRNAs were extensively upregulated after axotomy, with an earlier response after avulsion and highly prioritated expression of GFR[alpha]1 in surviving motoneurons. Levels of CNTF receptor alpha (CNTFR[alpha]) and the BDNF high affinity receptor trkB were rather unaffected. The largest difference in response between SNT and VRA in the adult rat was found for the NT-3 receptor trkC and membrane glycoprotein 130 (gpl30) mRNAs. Thus, after SNT there were only minor changes, while VRA induced a profound down-regulation. IGF-1 is available for lesioned motoneurons both after peripheral and central axonal lesions, while significant IGF-2 expression was restricted to denervated nerve. Also the regulation of IGF binding proteins (IGFBPs) are important. Thus, IGFBP-4 and IGFBP-5 were dominant in peripheral nerve, while IGFBP-2 and IGFBP-5 were preferentially found in the CNS. IGFBP-6 mRNA was strongly upregulated in spinal motoneurons and may be of special relevance for the severed cells, probably in relation to the IGF-2 expression in denervated nerve. Both integrin subunits [alpha]7 and ß1 were highly upregulated in spinal motoneurons after SNT, VRA and VFL and, in addition, integrin [alpha]6, which is not normally detectable. The levels of integrin 0 remained elevated longer after SNT than after VRA and VFL whereas integrin [alpha]6 displayed the opposite pattern. Interestingly, at 21 and 42 days after VFL, some motoneurons once again upregulated [alpha]7, possibly indicating a regeneration through the scar and contact with ventral roots. Also taken in consideration was the lesion-accompanied local inflammatory response. The traditional view has been that the relative immune privilege of the CNS serves to protect delicate neuronal networks from damage by immune reactions, but herein is demonstrated that axotomy induces an upregulation of MHC I and ß2-microglobulin mRNA in motoneurons, indicating an active participation in the immune response after injury. Experimental autoimmune encephalomyelitis (EAE) induced by active immunization with an encephalitogenic MBP peptide led to a robust survival promoting effect on avulsed motoneurons in spite of a very intense inflammatory reaction with high levels of pro-inflammatory cytokines in the lesioned segments. Furthermore, the expression of the neurotrophic factors BDNF, NT-3 and GDNF by encephalitogenic T and NK cells, may constitute an important mechanism for neuronal protection in CNS inflammation and is supported by the fact that interferon-[gamma] (IFN-[gamma]) or tumor necrosis factor-[alpha] (TNF-[alpha]) treatment increased death of motoneurons only in cultures deprived of neurotrophic support. In conclusion, this thesis demonstrates a complex regulation of a network of substances that are decisive for the regenerative potential of motoneurons after mechanical nerve trauma

Sensors and AI Techniques for Situational Awareness in Autonomous Ships: A Review

Autonomous ships are expected to improve the level of safety and efficiency in future maritime navigation. Such vessels need perception for two purposes: to perform autonomous situational awareness and to monitor the integrity of the sensor system itself. In order to meet these needs, the perception system must fuse data from novel and traditional perception sensors using Artificial Intelligence (AI) techniques. This article overviews the recognized operational requirements that are imposed on regular and autonomous seafaring vessels, and then proceeds to consider suitable sensors and relevant AI techniques for an operational sensor system. The integration of four sensors families is considered: sensors for precise absolute positioning (Global Navigation Satellite System (GNSS) receivers and Inertial Measurement Unit (IMU)), visual sensors (monocular and stereo cameras), audio sensors (microphones), and sensors for remote-sensing (RADAR and LiDAR). Additionally, sources of auxiliary data, such as Automatic Identification System (AIS) and external data archives are discussed. The perception tasks are related to well-defined problems, such as situational abnormality detection, vessel classification, and localization, that are solvable using AI techniques. Machine learning methods, such as deep learning and Gaussian processes, are identified to be especially relevant for these problems. The different sensors and AI techniques are characterized keeping in view the operational requirements, and some example state-of-the-art options are compared based on accuracy, complexity, required resources, compatibility and adaptability to maritime environment, and especially towards practical realization of autonomous systems

Secretagogin is expressed in sensory CGRP neurons and in spinal cord of mouse and complements other calcium-binding proteins, with a note on rat and human

Abstract Background Secretagogin (Scgn), a member of the EF-hand calcium-binding protein (CaBP) superfamily, has recently been found in subsets of developing and adult neurons. Here, we have analyzed the expression of Scgn in dorsal root ganglia (DRGs) and trigeminal ganglia (TGs), and in spinal cord of mouse at the mRNA and protein levels, and in comparison to the well-known CaBPs, calbindin D-28k, parvalbumin and calretinin. Rat DRGs, TGs and spinal cord, as well as human DRGs and spinal cord were used to reveal phylogenetic variations. Results We found Scgn mRNA expressed in mouse and human DRGs and in mouse ventral spinal cord. Our immunohistochemical data showed a complementary distribution of Scgn and the three CaBPs in mouse DRG neurons and spinal cord. Scgn was expressed in ~7% of all mouse DRG neuron profiles, mainly small ones and almost exclusively co-localized with calcitonin gene-related peptide (CGRP). This co-localization was also seen in human, but not in rat DRGs. Scgn could be detected in the mouse sciatic nerve and accumulated proximal to its constriction. In mouse spinal cord, Scgn-positive neuronal cell bodies and fibers were found in gray matter, especially in the dorsal horn, with particularly high concentrations of fibers in the superficial laminae, as well as in cell bodies in inner lamina II and in some other laminae. A dense Scgn-positive fiber network and some small cell bodies were also found in the superficial dorsal horn of humans. In the ventral horn, a small number of neurons were Scgn-positive in mouse but not rat, confirming mRNA distribution. Both in mouse and rat, a subset of TG neurons contained Scgn. Dorsal rhizotomy strongly reduced Scgn fiber staining in the dorsal horn. Peripheral axotomy did not clearly affect Scgn expression in DRGs, dorsal horn or ventral horn neurons in mouse. Conclusions Scgn is a CaBP expressed in a subpopulation of nociceptive DRG neurons and their processes in the dorsal horn of mouse, human and rat, the former two co-expressing CGRP, as well as in dorsal horn neurons in all three species. Functional implications of these findings include the cellular refinement of sensory information, in particular during the processing of pain.</p

Sensors and AI Techniques for Situational Awareness in Autonomous Ships : A Review

Autonomous ships are expected to improve the level of safety and efficiency in future maritime navigation. Such vessels need perception for two purposes: to perform autonomous situational awareness and to monitor the integrity of the sensor system itself. In order to meet these needs, the perception system must fuse data from novel and traditional perception sensors using Artificial Intelligence (AI) techniques. This article overviews the recognized operational requirements that are imposed on regular and autonomous seafaring vessels, and then proceeds to consider suitable sensors and relevant AI techniques for an operational sensor system. The integration of four sensors families is considered: sensors for precise absolute positioning (Global Navigation Satellite System (GNSS) receivers and Inertial Measurement Unit (IMU)), visual sensors (monocular and stereo cameras), audio sensors (microphones), and sensors for remote-sensing (RADAR and LiDAR). Additionally, sources of auxiliary data, such as Automatic Identification System (AIS) and external data archives are discussed. The perception tasks are related to well-defined problems, such as situational abnormality detection, vessel classification, and localization, that are solvable using AI techniques. Machine learning methods, such as deep learning and Gaussian processes, are identified to be especially relevant for these problems. The different sensors and AI techniques are characterized keeping in view the operational requirements, and some example state-of-the-art options are compared based on accuracy, complexity, required resources, compatibility and adaptability to maritime environment, and especially towards practical realization of autonomous systems