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Insidious changes in behaviour herald the onset of progressive neurodegenerative disorders such as Huntington's disease (HD), sometimes years before overt symptoms are seen. Sleep and circadian disturbances are particularly disruptive symptoms in patients with neurological disorders, but they are difficult to measure in humans. Here we studied circadian behaviour in transgenic HD sheep expressing the full-length human huntingtin protein with an expanded CAG repeat mutation in the juvenile range. Young HD sheep with no other symptoms exhibited circadian behavioural abnormalities that worsened with age. The most obvious change was a disturbed evening behaviour reminiscent of 'sundowning' that is seen in some patients with dementia. There were no structural abnormalities seen with magnetic resonance imaging, even in 5-year-old HD sheep. Interestingly, detection of the circadian abnormalities depended upon their social grouping. Abnormalities emerged in sheep kept in an 'HD-only' flock, whereas the behaviour of HD sheep kept mixed with normal sheep was relatively normal. Sleep-wake abnormalities in HD patients are also likely to be hidden, and may precede overt symptoms by many years. Sleep disruption has deleterious effects, even in normal people. The knock-on effects of sleep-wake disturbance may exacerbate, or even cause symptoms such as irritability and depression that are common in early stage HD patients. HD sheep will be useful models for probing the mechanisms underlying circadian behavioural disorder in HD.

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Reductions in information processing speed have frequently been reported following moderate and severe traumatic brain injuries (TBIs), consistent with the effects of diffuse white matter damage. Although the corpus callosum (CC) is a common site for diffuse damage following TBI, the effects of this damage on information processing speed have not been adequately examined. This study assessed a TBI group and a matched control group on tests of attention, memory, fluency, and set shifting ability, together with reaction time (RT) tasks requiring the inter- and intrahemispheric processing of visual and tactile information. The RT tasks were designed to target the cognitive functions that are likely to be affected by diffuse white matter damage, including damage to the CC. The TBI group demonstrated deficits in verbal and visual fluency and verbal memory. They were also slower on the visual and tactile RT tasks, were more affected by task complexity, and slower on RT tasks requiring the interhemispheric transfer of information. In fact, one of the interhemispheric tactile RT tasks proved to be the most discriminating of all the cognitive and RT measures. MRIs completed on a subset of TBI participants indicated that the mean CC measurements were 5% to 19% smaller than a normative control group, with the most atrophied areas being the isthmus and anterior midbody. Although white matter atrophy was moderately related to visual and tactile RT performance, and total hippocampal volume related to memory performance, CC area was not related to many of the tasks that were designed to tap interhemispheric processing. None of the standard cognitive tests correlated with outcome in the TBI group, but 1 of the tactile RT measures was significantly related to 2 measures of outcome.

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Blood samples were collected from a total of 70 rabbits at three locations in Trinidad. The locations were the University Field Station (n=46), the School of Veterinary Medicine (n=11), and the Eastern Caribbean Institute of Agriculture and Forestry (n=13). Complete blood counts and serum chemistry determinations were done for each sample. Values obtained were compared to reference ranges in the literature. The effects of gender, maturity (juveniles vs. adults), breed (New Zealand White vs. Mixed), and rabbitry on all parameters were examined. Mixed rabbits were crossbreds consisting of at least two breeds: New Zealand White, Californian, Checkered Giant. A comparison was made between values for haemoglobin, packed cell volume, mean corpuscular haemoglobin concentration, and white blood cell count, obtained by manual and automated methods. Most values obtained were within the ranges of those in the literature with the exception of urea (5.5-7.0 mmol/L), albumin (50.56-52.98 g/L) and creatine phosphokinase (CPK) (572.70-821.98 U/L). Albumin and CPK concentrations were higher and urea lower (P<0.05) for the present study. Significant differences (P<0.05) between automated and manual values were found for haemoglobin (Hb), packed cell volume (PCV), and mean corpuscular haemoglobin concentration (MCHC), with values for automated methods being higher for Hb and MCHC and lower for PCV. For the leukon, husbandry practices had an effect on neutrophil, eosinophil, basophil, lymphocyte, and platelet values while maturity influenced neutrophil and lymphocyte counts (P<0.05). The automated white blood cell count (WBC a ) was affected by breed (P<0.05). In the case of the erythron, husbandry practices affected automated PCV and MCHC values, and red blood cell counts (RBC) (P<0.05). Maturity influenced automated Hb and PCV values, and RBC (P<0.05). Mixed breeds had higher automated Hb, PCV and RBC values than New Zealand White rabbits (P<0.05). Male rabbits had higher values than females for manual and automated Hb, manual and automated PCV, and RBC (P<0.05). For serum chemistry, husbandry practices had an effect on potassium (K), phosphorus (P), creatinine, bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), amylase and calcium (P<0.05). Phosphorus, AST, cholesterol and glucose were higher for juveniles; while chloride was higher for adult rabbits (P<0.05). Only CPK was affected by breed, with the mixed breed having higher values than New Zealand White rabbits (P<0.05). Males had higher values for potassium, total protein, and albumin, while females had higher values for cholesterol (P<0.05). Haematology and serum chemistry reference intervals obtained in this study may therefore be considered useful baseline values for domestic rabbit populations in the Caribbean.

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