Mortality in red squirrels (Sciurus vulgaris) associated with exudative dermatitis.

Red squirrels (Sciurus vulgaris) found dead or dying on the Isle of Wight and the island of Jersey were suffering from exudative, ulcerative dermatitis and superficial staphylococcal pyoderma. The principal gross lesions were on the lips, eyelids and feet and showed similarities to those of squirrelpox. The histopathological lesions were also similar and, although there was no ballooning degeneration of epidermal cells, intracytoplasmic inclusions resembling those seen in poxvirus infections were present. Examination of lesions by electron microscopy failed to identify any virions, and PCR analysis for squirrelpox virus proved negative. The skin lesions also resembled those of mange, but although numerous mites were present in the fur these were mostly Dermacarus sciurinus with small numbers of Metalistrophorus pagenstecheri. The occurrence of these species on red squirrels in Britain is confirmed, but neither is pathogenic and they were not considered to have been involved in the pathogenesis of the dermatitis, the primary cause of which was not established.

Haematological and biochemical values for grey seal pups (Halichoerus grypus) during early rehabilitation.

Haematological and biochemical data were collected over a period of six years from grey seal (Halichoerus grypus) pups undergoing rehabilitation. Pups bled during the first three days were allocated retrospectively to one of seven clinical groups and statistical analyses were carried out on six of these groups (130 pups). Compared with reference ranges, all the groups had lower mean packed-cell volumes (pcv), red blood cell (rbc) counts haemoglobin and albumin levels, pups with severe trauma had higher total white blood cell (wbc) and neutrophil counts, pups with severe trauma and malnourished pups had higher total bilirubin levels, and pups in all the clinical groups except those with severe trauma had lower sodium levels. There were significant differences (P<0.05) between some clinical groups for mean pcv, rbc counts, all wbc counts except monocytes, haemoglobin, total bilirubin, creatine kinase, amylase and potassium levels. Forty-nine pups were bled more than once during the first 10 days of rehabilitation for haematology, and 11 were bled more than once for biochemistry. There were significant decreases (P<0.05) during this period in pcv, and in the activities of alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase and lactate dehydrogenase, and significant increases in all wbc counts, total protein, globulin, amylase and calcium levels.

Synaptic organisation of the basal ganglia.

The basal ganglia are a group of subcortical nuclei involved in a variety of processes including motor, cognitive and mnemonic functions. One of their major roles is to integrate sensorimotor, associative and limbic information in the production of context-dependent behaviours. These roles are exemplified by the clinical manifestations of neurological disorders of the basal ganglia. Recent advances in many fields, including pharmacology, anatomy, physiology and pathophysiology have provided converging data that have led to unifying hypotheses concerning the functional organisation of the basal ganglia in health and disease. The major input to the basal ganglia is derived from the cerebral cortex. Virtually the whole of the cortical mantle projects in a topographic manner onto the striatum, this cortical information is 'processed' within the striatum and passed via the so-called direct and indirect pathways to the output nuclei of the basal ganglia, the internal segment of the globus pallidus and the substantia nigra pars reticulata. The basal ganglia influence behaviour by the projections of these output nuclei to the thalamus and thence back to the cortex, or to subcortical 'premotor' regions. Recent studies have demonstrated that the organisation of these pathways is more complex than previously suggested. Thus the cortical input to the basal ganglia, in addition to innervating the spiny projection neurons, also innervates GABA interneurons, which in turn provide a feed-forward inhibition of the spiny output neurons. Individual neurons of the globus pallidus innervate basal ganglia output nuclei as well as the subthalamic nucleus and substantia nigra pars compacta. About one quarter of them also innervate the striatum and are in a position to control the output of the striatum powerfully as they preferentially contact GABA interneurons. Neurons of the pallidal complex also provide an anatomical substrate, within the basal ganglia, for the synaptic integration of functionally diverse information derived from the cortex. It is concluded that the essential concept of the direct and indirect pathways of information flow through the basal ganglia remains intact but that the role of the indirect pathway is more complex than previously suggested and that neurons of the globus pallidus are in a position to control the activity of virtually the whole of the basal ganglia.

Selective innervation of neostriatal interneurons by a subclass of neuron in the globus pallidus of the rat.

A subpopulation of neurons in the globus pallidus projects to the neostriatum, which is the major recipient of afferent information to the basal ganglia. Given the moderate nature of this projection, we hypothesized that the pallidostriatal projection might exert indirect but powerful control over principal neuron activity by targeting interneurons, which comprise only a small percentage of neostriatal neurons. This was tested by the juxtacellular labeling and recording of pallidal neurons in combination with immunolabeling of postsynaptic neurons. In addition to innervating the subthalamic nucleus and output nuclei, 6 of 23 labeled pallidal neurons projected to the neostriatum. Both the firing characteristics and the extent of the axonal arborization in the neostriatum were variable. However, light and electron microscopic analysis of five pallidostriatal neurons revealed that each neuron selectively innervated neostriatal interneurons. A large proportion of the boutons of an individual axon (19-66%) made contact with parvalbumin-immunoreactive interneurons. An individual parvalbumin-immunoreactive neuron (n = 27) was apposed on average by 6.7 boutons (SD = 6.1) from a single pallidal axon (n = 2). Individual pallidostriatal boutons typically possessed more than one symmetrical synaptic specialization. In addition, 3-32% of boutons of axons from four of five pallidal neurons contacted nitric oxide synthase-immunoreactive neurons. Descending collaterals of pallidostriatal neurons were also found to make synaptic contact with dopaminergic and GABAergic neurons of the substantia nigra. These data imply that during periods of cortical activation, individual pallidal neurons may influence the activity of GABAergic interneurons of the neostriatum (which are involved in feed-forward inhibition and synchronization of principle neuron activity) while simultaneously patterning neuronal activity in basal ganglia downstream of the neostriatum.

Resin-bonded arch bars.

A technique for constructing acid etched arch bars is described, this technique provides appropriate location of osteotomy segments in the absence of orthodontic brackets. The arch bars can be applied preoperatively with a subsequent economy of operating theatre time.