Patterns of connexin36 and eGFP reporter expression among motoneurons in spinal sexually dimorphic motor nuclei in mouse.

Background: Sexually dimorphic spinal motoneurons (MNs) in the dorsomedial nucleus (DMN) and dorsolateral nucleus (DLN) as well as those in the cremaster nucleus are involved in reproductive behaviours, and the cremaster nucleus additionally contributes to testicular thermoregulation. It has been reported that MNs in DMN and DLN are extensively linked by gap junctions forming electrical synapses composed of connexin36 (Cx36) and there is evidence that subpopulation of MNs in the cremaster nucleus are also electrically coupled by these synapses.

Methodology: We used immunofluorescence methods to detect enhanced green fluorescent protein (eGFP) reporter for Cx36 expression in these motor nuclei.

Association of connexin36 with adherens junctions at mixed synapses and distinguishing electrophysiological features of those at mossy fiber terminals in rat ventral hippocampus.

Background: Granule cells in the hippocampus project axons to hippocampal CA3 pyramidal cells where they form large mossy fiber terminals. We have reported that these terminals contain the gap junction protein connexin36 (Cx36) specifically in the stratum lucidum of rat ventral hippocampus, thus creating morphologically mixed synapses that have the potential for dual chemical/electrical transmission.

Methodology: Here, we used various approaches to characterize molecular and electrophysiological relationships between the Cx36-containing gap junctions at mossy fiber terminals and their postsynaptic elements and to examine molecular relationships at mixed synapses in the brainstem.

Connexin36 localization along axon initial segments in the mammalian CNS.

Electrical synapses formed by gap junctions occur at a variety of neuronal subcellular sites in the mammalian central nervous system (CNS), including at somatic, dendritic and axon terminal compartments. Numerous electrophysiological studies using mice and rats, as well as computer modelling approaches, have predicted the additional occurrence of electrical synapses between axons near their emergence from neuronal somata. Here, we used immunofluorescence methods to search for localization of the neuronal gap junction-forming protein connexin36 (Cx36) along axon initial segments (AISs) labelled for the AIS marker ankyrinG.

E3 ubiquitin ligases LNX1 and LNX2 localize at neuronal gap junctions formed by connexin36 in rodent brain and molecularly interact with connexin36.

Electrical synapses in the mammalian central nervous system (CNS) are increasingly recognized as highly complex structures for mediation of neuronal communication, both with respect to their capacity for dynamic short- and long-term modification in efficacy of synaptic transmission and their multimolecular regulatory and structural components. These two characteristics are inextricably linked, such that understanding of mechanisms that contribute to electrical synaptic plasticity requires knowledge of the molecular composition of electrical synapses and the functions of proteins associated with these synapses. Here, we provide evidence that the key component of gap junctions that form the majority of electrical synapses in the mammalian CNS, namely connexin36 (Cx36), directly interacts with the related E3 ubiquitin ligase proteins Ligand of NUMB protein X1 (LNX1) and Ligand of NUMB protein X2 (LNX2).

Molecular and functional asymmetry at a vertebrate electrical synapse.

Electrical synapses are abundant in the vertebrate brain, but their functional and molecular complexities are still poorly understood. We report here that electrical synapses between auditory afferents and goldfish Mauthner cells are constructed by apposition of hemichannels formed by two homologs of mammalian connexin 36 (Cx36) and that, while Cx35 is restricted to presynaptic hemiplaques, Cx34.7 is restricted to postsynaptic hemiplaques, forming heterotypic junctions.

Difficulties in demonstrating long term immunity in FeLV vaccinated cats due to increasing age-related resistance to infection.

Background: Feline leukaemia virus (FeLV) is a pathogen causing fatal illness in cats worldwide, and as such there is a high demand for products to protect against disease. The duration of immunity provided by an inactivated FeLV vaccine, Versifel FeLV, when administered to cats of the target age was determined. Kittens received two vaccinations when aged 7 to 9 weeks old, and were subsequently challenged up to 36 months later with the FeLV-A Glasgow isolate.

Characterization of connexin31.1-deficient mice reveals impaired placental development.

The gap junction gene Connexin31.1 has been reported to be expressed predominantly in the epidermis of murine skin. To study the function of this gene, we generated mice in which the coding DNA of the Connexin31.

Longitudinal sliding of the median nerve in patients with non-specific arm pain.

In patients with non-specific arm pain (NSAP; also known as repetitive strain injury), there are clinical signs of altered median nerve sliding. It is possible that a restriction along the nerve course will lead to abnormal increases in local strain during limb movements, possibly contributing to symptoms. The present study uses ultrasound imaging to examine median nerve sliding through the proximal and distal nerve segments in 18 NSAP patients.

An in vivo investigation of ulnar nerve sliding during upper limb movements.

Background: Peripheral nerves straighten and stretch in order to accommodate increases in bed length during joint movements. The ulnar nerve is predicted to show large bed length changes, particularly on elbow flexion. The present study examines sliding of the ulnar nerve during limb movements, to determine how far these changes are accommodated by straightening and stretch.

Evaluation of novel technique for studying ureteral function in vivo.

Background And Purpose: Knowledge of the ureteral response to instrumentation is limited. Ureterodynamic parameters such as intraureteral pressure, conduction velocity, direction of peristalsis, and electromyography have been measured using a variety of methods; however, these techniques are impractical for routine clinical use. The aim of this study was to evaluate a new commercial ureteral pressure transducer catheter, which records peristaltic frequency, conduction velocity, and intraureteral pressure.

Pressure and stretch mechanosensitivity of peripheral nerve fibres following local inflammation of the nerve trunk.

Patients with non-specific limb pain often show signs of nerve mechanosensitivity, i.e. local tenderness over nerve trunks and pain in response to limb movements that cause nerve stretch.

In vivo study of nerve movement and mechanosensitivity of the median nerve in whiplash and non-specific arm pain patients.

Chronic pain following whiplash injury and non-specific arm pain (NSAP, previously termed diffuse repetitive strain injury) present clinicians with problems of diagnosis and management. In both patient groups there are clinical signs of altered nerve movement and increased nerve trunk mechanosensitivity. Previous studies of NSAP patients have identified altered median nerve movement at the wrist.

Shoulder posture and median nerve sliding.

Background: Patients with upper limb pain often have a slumped sitting position and poor shoulder posture. Pain could be due to poor posture causing mechanical changes (stretch; local pressure) that in turn affect the function of major limb nerves (e.g.

Quantitative in vivo studies of median nerve sliding in response to wrist, elbow, shoulder and neck movements.

Objective: To examine median nerve sliding in response to upper limb movements in vivo. To determine whether the median nerve can be unloaded.

Design: Exploratory study in healthy subjects.

Connexin29 and connexin32 at oligodendrocyte and astrocyte gap junctions and in myelin of the mouse central nervous system.

The cellular localization, relation to other glial connexins (Cx30, Cx32, and Cx43), and developmental expression of Cx29 were investigated in the mouse central nervous system (CNS) with an anti-Cx29 antibody. Cx29 was enriched in subcellular fractions of myelin, and immunofluorescence for Cx29 was localized to oligodendrocytes and myelinated fibers throughout the brain and spinal cord. Oligodendrocyte somata displayed minute Cx29-immunopositive puncta around their periphery and intracellularly.

Sensory and autonomic function in the hands of patients with non-specific arm pain (NSAP) and asymptomatic office workers.

Chronic pain in the upper limb associated with repetitive movements of the arm and hand is often seen in patients in the absence of specific pathology such as epicondylitis, carpal tunnel syndrome and tenosynovitis. This condition has been given many names and will be referred to here as non-specific arm pain (NSAP). Previous work has shown elevated vibration thresholds and reduced flare suggesting a neuropathic cause for this condition.

C-fibre Function During the 6 Weeks Following Brief Application of Capsaicin to a Cutaneous Nerve in the Rat.

The functional properties of afferent fibres, especially C-fibres, have been studied over the 46 days following application of capsaicinoids to a segment of the saphenous nerve in the rat. After 1 - 3 days, approximately half of the C-afferents were found to be non-conducting at or immediately distal to the treatment site. By 6 - 9 days there was some recovery of conduction at the treatment site, but few of the conducting fibres were excitable from the skin.

Capsaicin: actions on nociceptive C-fibres and therapeutic potential.

Recent work on the excitatory action of capsaicin on somatic and visceral afferent neurones shows that depolarization is selective for C-fibre polymodal nociceptor afferents and involves opening a non-selective cation channel. Exposure to significantly suprathreshold amounts of capsaicin causes permanent degeneration of C-fibre afferents in adult rats. Functional changes in rats (hypalgesia, diminished neurogenic inflammation) are likely to be a direct consequence of the loss of C-fibre nociceptors, and so are the reductions in neuropeptide levels that follow adult capsaicin treatment.

Long-Term Reduction in the Number of C-Fibre Nociceptors Following Capsaicin Treatment of a Cutaneous Nerve in Adult Rats.

The structure and function of C- and A-fibres have been studied 3 - 12 months following a single 30 min exposure of the saphenous nerve of adult rats to 1% capsaicin. Examination of nerve cross-sections showed that the number of C-fibres was reduced by 36%, but A-fibres were unaffected. The remaining C-fibres included many that were unusually small in size.

A comparison of four tests for assessing the pain sensitivity of different subjects and test areas.

Four different testing methods were used to estimate the sensitivity of body surfaces to pain-causing stimuli for a group of 24 healthy male subjects. These methods were (a) determination of the heat pain threshold, (b) determination of the pain threshold for pinching of a skin fold, (c) discrimination of a sharp prick from a blunt contact, and (d) estimation of the pain caused by application of an ice-cold cylinder. Three different body regions were tested: the abdomen, the anterior surface of the neck and the lateral surface of the thigh.