Retinal dysfunction, photoreceptor protein dysregulation and neuronal remodelling in the R6/1 mouse model of Huntington's disease

Huntington's disease (HD) is a progressive neurological disease characterised by motor dysfunction, cognitive impairment and personality changes. Previous work in HD patients and animal models of the disease has also highlighted retinal involvement. This study characterised the changes in retinal structure and function early within the progression of disease using the R6/1 mouse model of HD. The retinal phenotype was observed to occur at the same time in the disease process as other neurological deficits such as motor dysfunction (by 13 weeks of age). There was a specific functional deficit in cone response to the electroretinogram and using immunocytochemical techniques, this dysfunction was found to be likely due to a progressive and complete loss of cone opsin and transducin protein expression by 20 weeks of age. In addition, there was an increase in Müller cell gliosis and the presence of ectopic rod photoreceptor terminals. This retinal remodelling is also observed in downstream neurons, namely the rod and cone bipolar cells. While R6/1 mice exhibit significant retinal pathology simultaneously with other more classical HD alterations, this doesn't lead to extensive cell loss. These findings suggest that in HD, cone photoreceptors are initially targeted, possibly via dysregulation of protein expression or trafficking and that this process is subsequently accompanied by increased retinal stress and neuronal remodelling also involving the rod pathway. As retinal structure and connectivity are well characterised, the retina may provide a useful model tissue in which to characterise the mechanisms important in the development of neuronal pathology in HD.     

Progress in the treatment of Friedreich ataxia

Friedreich ataxia (FRDA) is a progressive neurological disorder affecting approximately 1 in 29,000 individuals of European descent. At present, there is no approved pharmacological treatment for this condition however research into treatment of FRDA has advanced considerably over the last two decades since the genetic cause was identified. Current proposed treatment strategies include decreasing oxidative stress, increasing cellular frataxin, improving mitochondrial function as well as modulating frataxin controlled metabolic pathways. Genetic and cell based therapies also hold great promise. Finally, physical therapies are being explored as a means of maximising function in those affected by FRDA.     

A polymorphic miR-155 binding site in AGTR1 is associated with cardiac hypertrophy in Friedreich ataxia

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative condition with a heterogeneous cardiac phenotype caused primarily by an expanded GAA trinucleotide repeat in the frataxin gene (FXN). FXN is important in mitochondrial iron efflux, sensitivity to oxidative stress, and cell death. The number of GAA repeats on the smaller FXN allele (GAA1) only accounts for a portion of the observed variability in cardiac phenotype. Genetic modifying factors, such as single nucleotide polymorphisms (SNPs) in genes of the Renin–Angiotensin–Aldosterone system (RAAS), may contribute to phenotype variability. This study investigated genetic variability in the angiotensin-II type-1 receptor (AGTR1), angiotensin-converting enzyme (ACE), and ACE2 genes as cardiac phenotype modifying factors in FRDA patients. Comprehensive review of the AGTR1, ACE and ACE2 genes identified twelve haplotype tagging SNPs. Correlation of these SNPs with left ventricular internal diameter in diastole (LVIDd), interventricular septal wall thickness (SWT) and left ventricular mass (LVM) was examined in a large Australian FRDA cohort (n = 79) with adjustments performed for GAA repeats, age, sex, body surface area and diastolic blood pressure. A significant inverse relationship was observed between GAA1 and LVIDd (p = 0.010) but not with SWT or LVM after adjustment for covariates. The AGTR1 polymorphism rs5186 was more common in FRDA patients than in a control population (p = 0.002). Using a recessive model of inheritance, the C allele of rs5186 was associated with a significant increase in SWT (p = 0.003) and LVM (p = 0.001). This functional polymorphism increases expression of AGTR1 by altering the binding site for miR-155, a regulatory microRNA. No significant associations with left ventricular structure were observed for the remaining RAAS polymorphisms. The AGTR1 polymorphism rs5186 appears to modify the FRDA cardiac phenotype independently of GAA1. This study supports the role of RAAS polymorphisms as modifiers of cardiac phenotype in FRDA patients.     

The role of television advertising in increasing pneumococcal vaccination coverage among the elderly, North Coast, New South Wales, 2006

North Coast Area Health Service (NCAHS) conducted a seven week television advertising campaign to raise community awareness of the availability of free adult pneumococcal vaccination and to increase coverage among North Coast residents in high risk groups. Effectiveness of the campaign was evaluated by examining vaccine ordering patterns of North Coast vaccination providers from 2005/2006 as a proxy for vaccination coverage. In the months during and immediately following (June-September 2006) the advertising campaign, a significantly higher proportion of vaccines were despatched to North Coast immunisation service providers. The advertising campaign was an effective strategy to promote vaccination among NCAHS residents not immunised in the first year of the National Pneumococcal Program for Older Australians. This higher immunisation coverage is expected to contribute to the statewide trend of significant reductions in invasive pneumococcal disease (IPD) notifications.     

The Buckinghamshire nursing record audit tool: a unique approach to documentation

A project to examine the quality of manual nursing documentation using an action research approach, prior to the introduction of a computerized system is described. The findings showed that there was a general lack of understanding about care planning. There was therefore a need to find an audit tool which could identify and develop nurses' knowledge of documentation as well as identifying the strengths and weaknesses of existing documentation. A literature review revealed Phaneuf's audit tool, but this proved difficult to use. Two nurse teachers agreed to develop their own documentation audit tool, based on the UKCC document on record keeping, which identifies criteria for effective documentation. A tool was developed which adopts a facilitative educational approach enabling the practitioner to audit and learn simultaneously. Much interest is being shown by other areas, and the questions are worded so that it could be used in a variety of settings.     

Impairment in motor reprogramming in Friedreich ataxia reflecting possible cerebellar dysfunction

The cerebellar and spinocerebellar dysfunction seen in Friedreich ataxia (FRDA) has known effects on motor function. Recently, it was suggested that people with FRDA may also have impairment in motor planning, either because of cortical pathology or because of cerebello-cortical projections. Fifteen adults with FRDA and 15 matched controls completed a task requiring reciprocating movements between two buttons on a tapping board. Occasionally there was one of three “oddball” stimuli requiring reprogramming of movement. These were change in (1) direction, (2) extent or (3) direction and extent. We hypothesized that people with FRDA would have prolonged movement times due to their movement disorder, and that changes in preparation time would be affected in a way similar to controls, unless there was impairment in motor planning in FRDA. Movement execution and, to a lesser degree, movement preparation were impaired in individuals with FRDA. We argue this points to disturbed cortical function. There was a significant negative correlation between age of onset and all three reprogramming conditions, suggesting an impact of FRDA on developing motor planning. Future studies will be required to establish whether this dysfunction is due to cerebellar impairment interrupting cerebro-ponto-cerebello-thalamo-cerebral loops, primary cortical pathology or a combination of the two.