Genetic characterization of measles virus genotype D6 subacute sclerosing panencephalitis case, Alberta, Canada

Subacute sclerosing panencephalitis (SSPE) is a progressive and eventually fatal neurological disease arising from a persistent infection with measles virus (MV) acquired at a young age. SSPE measles virus strains are defective and unable to produce progeny virions, due to multiple and extensive mutations in a number of key genes. We sequenced the full MV genome from our recently reported SSPE case, which typed as genotype D6, and compared it with other genotype D6 wild type and SSPE sequences. The Alberta D6 strain was significantly different from other reported SSPE D6 sequences. Mutations were observed in all the genes of the Alberta strain, with the greatest sequence divergence noted in the M gene with 17.6% nucleotide and 31% amino acid variation. The L gene showed the least variation with 1.3% nucleotide and 0.7% amino acid differences respectively. The nucleotide variability for 15,672 bases of the complete genome compared to the wild type and other SSPE D6 strains was around 3%.

Smoking does not influence disability accumulation in primary progressive multiple sclerosis

BACKGROUND AND PURPOSE

The modifiable risk factor cigarette smoking has been associated with an increased risk of developing multiple sclerosis (MS) and with disease activity in relapsing-remitting MS. However, less is known about the effect of smoking on disease progression in progressive MS. Here the association between cigarette smoking and disability accumulation in primary progressive MS (PPMS) is investigated.

METHODS

Kaplan-Meier survival analyses and Cox proportional hazard modelling were used to investigate the influence of cigarette smoking on the risk of reaching Expanded Disability Status Scale (EDSS) 4 and 6 as well as the time from EDSS 4 to 6 in patients with PPMS.

RESULTS

In all, 416 patients with PPMS and available smoking history were identified. Median time to EDSS 4 was 4 years in ever-smokers and 5 years in never-smokers (P = 0.27), and it was 9 years to EDSS 6 in both ever-smokers and never-smokers (P = 0.48). Smokers were not at increased risk of faster progression to EDSS 4, 6 and from EDSS 4 to 6. Age at disease onset was the strongest risk factor for progression to EDSS 4, 6 and from EDSS 4 to 6.

CONCLUSIONS

Our investigation of a large and well-characterized population based PPMS cohort suggests that cigarette smoking does not influence disability accumulation in PPMS. Our findings support the idea that PPMS is driven by different underlying pathomechanisms than relapsing-remitting MS.

Mental health, violence, sexual abuse, tobacco and alcohol Acculturation and mental health — empirical verification of J.W. Berry’s model of acculturative stress

OBJECTIVES

Many studies concerning mental health among ethnic minorities have used the concept of acculturation as a model of explanation, in particular J.W. Berry's model of acculturative stress. But Berry's theory has only been empirically verified few times. The aims of the study were to examine whether Berry's hypothesis about the connection between acculturation and mental health can be empirically verified for Greenlanders living in Denmark and to analyse whether acculturation plays a significant role for mental health among Greenlanders living in Denmark.

STUDY DESIGN AND METHODS

The study used data from the 1999 Health Profile for Greenlanders in Denmark. As measure of mental health we applied the General Health Questionnaire (GHQ-12). Acculturation was assessed from answers to questions about how the respondents value the fact that children maintain their traditional cultural identity as Greenlander and how well the respondents speak Greenlandic and Danish. The statistical methods included binary logistic regression.

RESULTS

We found no connection between Berry's definition of acculturation and mental health among Greenlanders in Denmark. On the other hand, our findings showed a significant relation between mental health and gender, age, marital position, occupation and long-term illness.

CONCLUSION

The findings indicate that acculturation in the way Berry defines it plays a lesser role for mental health among Greenlanders in Denmark than socio-demographic and socio-economic factors. Therefore we cannot empirically verify Berry's hypothesis.

Performance on Paced Auditory Serial Addition Test and cerebral blood flow in multiple sclerosis

BACKGROUND

To assess the relationship between performance on the Paced Auditory Serial Addition Test (PASAT) and both cerebral blood flow (CBF) and axonal metabolic integrity in normal appearing white matter (NAWM) of the centrum semiovale in patients with multiple sclerosis (MS).

METHODS

Normal appearing white matter of the centrum semiovale was investigated with magnetic resonance (MR) imaging in 28 non-depressed individuals (18 patients with MS and 10 healthy controls). CBF was assessed with pseudo-continuous arterial spin labeling. N-acetylacetate/creatine (NAA/Cr) ratios (a metabolic axonal marker) were measured using (1) H-MR spectroscopy. CBF was also measured in frontoparietal cortices and cerebellar hemispheres.

RESULTS

In subjects with MS, we found a positive correlation between performance on the PASAT and CBF to the left centrum semiovale (P = 0.008), but not with the NAA/Cr ratio. There were no correlations between PASAT scores and CBF to the right centrum semiovale, frontoparietal cortices, and cerebellar hemispheres. There was no correlation between PASAT scores and NAA/Cr ratios.

CONCLUSIONS

Our preliminary results suggest that performance on the PASAT in subjects with MS correlates with CBF to the left centrum semiovale, which contains left frontoparietal white matter association tracts involved in information processing speed and working memory.

Does smoking influence outcome after intravenous thrombolysis for acute ischaemic stroke?

BACKGROUND AND PURPOSE

It remains uncertain whether current smoking influences outcome in patients with acute ischaemic stroke.

OBJECTIVES

To evaluate the effect of current smoking in routinely tissue plasminogen activator (tPA)-treated stroke patients on the 3-month functional outcome and the occurrence of symptomatic intracerebral hemorrhage (ICH).

METHODS

We analyzed data from a single stroke care unit registry of 345 consecutive patients with ischaemic stroke, treated with tPA. Logistic regression models were used to assess if smoking was independently associated with 3-months good outcome defined as a modified Rankin Scale score of < or =2, and the occurrence of symptomatic ICH.

RESULTS

In the multivariable models, smoking was not associated with a good outcome or a decreased risk of symptomatic ICH.

CONCLUSION

Current smoking did not affect functional outcome at 3 months or the risk of symptomatic ICH in patients routinely treated with tPA for ischaemic stroke.

Reproducibility over a 1-month period of 1H-MR spectroscopic imaging NAA/Cr ratios in clinically stable multiple sclerosis patients

N-acetylaspartate/creatine (NAA/Cr) ratios, assessed with proton magnetic resonance spectroscopy, are increasingly used as a surrogate marker for axonal dysfunction and degeneration in multiple sclerosis (MS). The purpose of this study was to test short-time reproducibility of NAA/Cr ratios in patients with clinically stable MS. In 35 MS patients we analysed NAA/Cr ratios obtained with ¹H-MR spectroscopic imaging at the centrum semiovale either with lateral ventricles partially included (group 1; n=15) or more cranially with no ventricles included (group 2; n=20). To test short-term reproducibility of the NAA/Cr measurements, patients were scanned twice 4 weeks apart. We determined mean NAA/Cr and Cho/Cr ratios of 12 grey matter and 24 white matter voxels. Mean NAA/Cr ratios of both the white and grey matter did not change after 4 weeks. Overall 4-week reproducibility of the NAA/Cr ratio, expressed as coefficient of variation, was 4.8% for grey matter and 3.5% for white matter. Reproducibility of cranial scanning of the ventricles was slightly better than with cerebrospinal fluid included. Our study shows good short-term reproducibility of NAA/Cr ratio measurements in the centrum semiovale, which supports the reliability of this technique for longitudinal studies.

Using polygons to recognize and locate partially occluded objects

We present computer vision algorithms that recognize and locate partially occluded objects. The scene may contain unknown objects that may touch or overlap giving rise to partial occlusion. The algorithms revolve around a generate-test paradigm. The paradigm iteratively generates and tests hypotheses for compatibility with the scene until it identifies all the scene objects. Polygon representations of the object's boundary guide the hypothesis generation scheme. Choosing the polygon representation turns out to have powerful consequences in all phases of hypothesis generation and verification. Special vertices of the polygon called ``corners'' help detect and locate the model in the scene. Polygon moment calculations lead to estimates of the dissimilarity between scene and model corners, and determine the model corner location in the scene. An association graph represents the matches and compatibility constraints. Extraction of the largest set of mutually compatible matches from the association graph forms a model hypothesis. Using a coordinate transform that maps the model onto the scene, the hypothesis gives the proposed model's location and orientation. Hypothesis verification requires checking for region consistency. The union of two polygons and other polygon operations combine to measure the consistency of the hypothesis with the scene. Experimental results give examples of all phases of recognizing and locating the objects.