Natural history of Tay-Sachs disease in sheep.

Tay-Sachs disease (TSD) is a fatal neurodegenerative disease caused by a deficiency of the enzyme ß-N-acetylhexosaminidase A (HexA). TSD naturally occurs in Jacob sheep is the only experimental model of TSD. TSD in sheep recapitulates neurologic features similar to juvenile onset and late onset TSD patients. Due to the paucity of human literature on pathology of TSD, a better natural history in the sheep TSD brain, which is on the same order of magnitude as a child's, is necessary for evaluating therapy and characterizing the pathological events that occur. To provide clinicians and researchers with a clearer understanding of longitudinal pathology in patients, we compare spectrum of clinical signs and brain pathology in mildly symptomatic (3-months), moderately symptomatic (6-months), or severely affected TSD sheep (humane endpoint at ~9-months of age). Increased GM2 ganglioside in the CSF of TSD sheep and a TSD specific biomarker on MRS (taurine) correlate with disease severity. Microglial activation and reactive astrocytes were observed globally on histopathology in TSD sheep with a widespread reduction in oligodendrocyte density. Myelination is reduced primarily in the forebrain illustrated by loss of white matter on MRI. GM2 and GM3 ganglioside were increased and distributed differently in various tissues. The study of TSD in the sheep model provides a natural history to shed light on the pathophysiology of TSD, which is of utmost importance due to novel therapeutics being assessed in human patients.

Awake intracerebroventricular delivery and safety assessment of oligonucleotides in a large animal model.

Oligonucleotide therapeutics offer great promise in the treatment of previously untreatable neurodegenerative disorders; however, there are some challenges to overcome in pre-clinical studies. (1) They carry a well-established dose-related acute neurotoxicity at the time of administration. (2) Repeated administration into the cerebrospinal fluid may be required for long-term therapeutic effect. Modifying oligonucleotide formulation has been postulated to prevent acute toxicity, but a sensitive and quantitative way to track seizure activity in pre-clinical studies is lacking. The use of intracerebroventricular (i.c.v.) catheters offers a solution for repeated dosing; however, fixation techniques in large animal models are not standardized and are not reliable. Here we describe a novel surgical technique in a sheep model for i.c.v. delivery of neurotherapeutics based on the fixation of the i.c.v. catheter with a 3D-printed anchorage system composed of plastic and ceramic parts, compatible with magnetic resonance imaging, computed tomography, and electroencephalography (EEG). Our technique allowed tracking electrical brain activity in awake animals via EEG and video recording during and for the 24-h period after administration of a novel oligonucleotide in sheep. Its anchoring efficiency was demonstrated for at least 2 months and will be tested for up to a year in ongoing studies.

Brain Alterations in Aged OVT73 Sheep Model of Huntington's Disease: An MRI Based Approach.

BACKGROUND: Huntington's disease (HD) is a fatal neurodegenerative autosomal dominant disorder with prevalence of 1 : 20000 that has no effective treatment to date. Translatability of candidate therapeutics could be enhanced by additional testing in large animal models because of similarities in brain anatomy, size, and immunophysiology. These features enable realistic pre-clinical studies of biodistribution, efficacy, and toxicity. OBJECTIVE AND METHODS: Here we non-invasively characterized alterations in brain white matter microstructure, neurochemistry, neurological status, and mutant Huntingtin protein (mHTT) levels in cerebrospinal fluid (CSF) of aged OVT73 HD sheep. RESULTS: Similar to HD patients, CSF mHTT differentiates HD from normal sheep. Our results are indicative of a decline in neurological status, and alterations in brain white matter diffusion and spectroscopy metric that are more severe in aged female HD sheep. Longitudinal analysis of aged female HD sheep suggests that the decline is detectable over the course of a year. In line with reports of HD human studies, white matter alterations in corpus callosum correlates with a decline in gait of HD sheep. Moreover, alterations in the occipital cortex white matter correlates with a decline in clinical rating score. In addition, the marker of energy metabolism in striatum of aged HD sheep, shows a correlation with decline of clinical rating score and eye coordination. CONCLUSION: This data suggests that OVT73 HD sheep can serve as a pre-manifest large animal model of HD providing a platform for pre-clinical testing of HD therapeutics and non-invasive tracking of the efficacy of the therapy.

An evidence-based specialist breast nurse role in practice: a multicentre implementation study.

The objective of this study was to examine the feasibility, implementation, acceptability and impact of an evidence-based specialist breast care nurse (SBN) model of care in Australia. Primary data were collected from four diverse Australian breast cancer treatment centres over a 12-month period. The design was a multicentre demonstration project. Information about the provision of care and patient needs was collected through prospective logs. Structured interviews were conducted with women who received the SBN intervention (N = 167) and with a control group of women treated prior to the intervention period (N = 133). Health professionals (N = 47) were interviewed about their experience of the SBN. Almost all women had contact with an SBN at five scheduled consultations and 67% of women in the intervention group requested at least one additional consultation with the SBN. Women in the intervention group were more likely to receive hospital fact sheets and to be told about and participate in clinical trials. Ninety-eight per cent of women reported that the availability of an SBN would affect their choice of hospital, with 48% indicating that they would recommend only a hospital with a SBN available. Health professionals reported that SBNs improved continuity of care, information and support for the women, and resulted in more appropriate referrals and use of the time of other members of the team. In conclusion, the SBN model is feasible and acceptable within diverse Australian treatment centres; there is evidence that some aspects of care were improved by the SBN.