A case of type B botulism in a pregnant bitch

A two-year-old pregnant Gordon setter presented with acute onset of flaccid tetraparesis and respiratory distress. Neurological examination revealed diffuse lower motor neuron dysfunction. Clostridium botulinum neurotoxin B was isolated from the dog's serum. The dog was hospitalised and received supportive care; respiratory function was monitored but positive-pressure ventilation was not required. Recovery was complete within 1 month and parturition occurred without complication 49 days after admission. The puppies delivered lacked any obvious congenital defects and development during the first few months of life was normal. The source of contamination was suspected to be poorly conserved dry food. To the authors' knowledge, this is the first report of C. botulinum neurotoxin B isolation in a dog and the first report of botulism in a pregnant bitch.

Cross-neurotization of the caudal brachial plexus with the contralateral C-8 ventral nerve branch in the cat. Potential surgical applications, effects of graft collection on the healthy donor limb and results

Contralateral transfer of the right, eighth ventral nerve branch (C8) (C8 cross-transfer - C8CT) was performed in 6 adult cats, in which the caudal part of the left brachial plexus (C8 and T1) had been severed, in order to mimic nerve root avulsion. Clinical and electrophysiological parameters, muscle contraction force measurements and histology were used to evaluate the effects of the surgery in a 14- to 36-month follow-up. The right forelimb (donor side) was clinically normal (no lameness) in all the cats at the end of the study. Electromyography performed 14 days after surgery revealed denervation fibrillation potentials in both forelimbs. Fibrillation potentials disappeared in all the cats at the end of the study. Direct stimulation of the right C8 ventral branch induced motor and sensory evoked potentials in the left limb muscles in all the cats. The left to right contraction ratio of the extensor carpi radialis muscle was approximately 1. This experimental study demonstrates that C8CT enables re-innervation of the contralateral brachial plexus and allows the establishment of new functional neuromuscular units. This can in turn enable the restoration of function, and could potentially lead to partial recovery after caudal brachial plexus avulsion in the cat.

The electroretinographic phenotype of dogs with Golden Retriever muscular dystrophy

OBJECTIVE

To characterize the flash electroretinogram (ERG) in the Golden Retriever muscular dystrophy (GRMD) dog and to compare the results with those from a control group of Golden Retrievers. To investigate whether similar abnormalities of the ERG as those found in a majority of human patients with Duchenne muscular dystrophy (DMD) are also observed in the GRMD dog, the canine model for DMD. Animals Five GRMD dogs and five age-matched clinically normal Golden Retrievers.

PROCEDURE

An ophthalmic examination was carried out prior to performing electroretinography under general anesthesia. Rod, combined rod-cone and oscillatory potentials responses were recorded after dark adaptation. Responses to 30-Hz-flicker were recorded after light adaptation. The ERG responses of the GRMD dogs were compared with those of the control dogs by use of a Wilcoxon signed rank test.

RESULTS

GRMD dogs had significantly reduced a and b-wave amplitudes after dim white flash stimuli (rod response) and reduced a-wave amplitude after bright white flash stimuli (rod-cone response).

CONCLUSION AND CLINICAL RELEVANCE

The ERG abnormalities observed in the GRMD dog suggest a dysfunction in the rod signaling pathway. These ERG alterations are different from those observed in human patients with DMD.

Gene transfer into canine myoblasts

We have developed and characterized cultures of healthy and dystrophic canine myoblasts for the evaluation of various gene transfer protocols. The number of desmin-positive myoblasts was elevated (>>80%) in cultures of myoblasts obtained from different muscle territories, the diaphragm muscle giving rise to the purest cultures. Myoblasts from dogs turned out to be a very convenient source of well transfectable and transducible cells. Transfection with plasmid DNA allowed efficient transgene expression (50% of beta-galactosidase positive cells and about 375 ng luciferase/mg protein after transfection with a calcium phosphate-precipitated plasmid). Infection with high concentrations of adenoviral and retroviral vectors allowed transgene (beta-galactosidase or mini-dystrophin) detection in about 75 to 90% of the canine cells. Therefore, primary dog myoblast cultures represent a useful in vitro model for viral and non-viral gene delivery, as well as for functional evaluation and cell grafting with applications in genetic diseases, vaccination or production of circulating therapeutic proteins.

In vitro and in vivo behaviour of NDF-expanded monkey Schwann cells

Schwann cells, the myelin-forming cells of the peripheral nervous system may play a major role in the regeneration and remyelination not only of the peripheral but also of the central nervous system. The discovery of the mitogenicity of human recombinant forms of neuregulins (glial growth factors) on primate Schwann cells allows us to envisage a considerable expansion of these cells in culture with a view to autologous transplantation in the central nervous system. To assay this possibility, we used human recombinant neu-differentiation factor beta (NDFbeta) to expand monkey Schwann cells derived from perinatal and adult nerve biopsies. We report that NDFbeta containing the epidermal growth factor (EGF)-like domain (residues 177-228) is a potent mitogen for monkey Schwann cells but is more effective on perinatal than adult Schwann cells. Moreover, continuous treatment with NDFbeta, does not seem to prevent Schwann cells differentiation into myelin-forming cells after their transplantation into the demyelinated mouse spinal cord. These observations, in addition to the close similarities of in vitro behaviour which exist between human and monkey Schwann cells, indicate that monkey Schwann cells could be an ideal tool to study the potential and limits of autologous transplantation in a non-human primate model of central nervous system demyelination.