The Prevalence and Magnitude of Impaired Cutaneous Sensation across the Hand in the Chronic Period Post-Stroke

Sensation is commonly impaired immediately post-stroke but little is known about the long-term changes in cutaneous sensation that have the capacity to adversely impact independence and motor-function. We investigated cutaneous sensory thresholds across the hand in the chronic post-stroke period. Cutaneous sensation was assessed in 42 community-dwelling stroke patients and compared to 36 healthy subjects. Sensation was tested with calibrated monofilaments at 6 sites on the hand that covered the median, ulnar and radial innervation territories and included both glabrous (hairless) and hairy skin. The motor-function of stroke patients was assessed with the Wolf Motor Function Test and the upper-limb motor Fugl-Meyer Assessment. Impaired cutaneous sensation was defined as monofilament thresholds >3 SD above the mean of healthy subjects and good sensation was ≤3 SD. Cutaneous sensation was impaired for 33% of patients and was 40–84% worse on the more-affected side compared to healthy subjects depending on the site (p<0.05). When the stroke patient data were pooled cutaneous sensation fell within the healthy range, although ∼1/3 of patients were classified with impaired sensation. Classification by motor-function revealed low levels of impaired sensation. The magnitude of sensory loss was only apparent when the sensory-function of stroke patients was classified as good or impaired. Sensation was most impaired on the dorsum of the hand where age-related changes in monofilament thresholds are minimal in healthy subjects. Although patients with both high and low motor-function had poor cutaneous sensation, overall patients with low motor-function had poorer cutaneous sensation than those with higher motor-function, and relationships were found between motor impairments and sensation at the fingertip and palm. These results emphasize the importance of identifying the presence and magnitude of cutaneous sensory impairments in the chronic period after stroke.     

Hepatitis C Virus Phylogenetic Clustering Is Associated with the Social-Injecting Network in a Cohort of People Who Inject Drugs

It is hypothesized that social networks facilitate transmission of the hepatitis C virus (HCV). We tested for association between HCV phylogeny and reported injecting relationships using longitudinal data from a social network design study. People who inject drugs were recruited from street drug markets in Melbourne, Australia. Interviews and blood tests took place three monthly (during 2005–2008), with participants asked to nominate up to five injecting partners at each interview. The HCV core region of individual isolates was then sequenced and phylogenetic trees were constructed. Genetic clusters were identified using bootstrapping (cut-off: 70%). An adjusted Jaccard similarity coefficient was used to measure the association between the reported injecting relationships and relationships defined by clustering in the phylogenetic analysis (statistical significance assessed using the quadratic assignment procedure). 402 participants consented to participate; 244 HCV infections were observed in 238 individuals. 26 genetic clusters were identified, with 2–7 infections per cluster. Newly acquired infection (AOR = 2.03, 95% CI: 1.04–3.96, p = 0.037, and HCV genotype 3 (vs. genotype 1, AOR = 2.72, 95% CI: 1.48–4.99) were independent predictors of being in a cluster. 54% of participants whose infections were part of a cluster in the phylogenetic analysis reported injecting with at least one other participant in that cluster during the study. Overall, 16% of participants who were infected at study entry and 40% of participants with newly acquired infections had molecular evidence of related infections with at least one injecting partner. Likely transmission clusters identified in phylogenetic analysis correlated with reported injecting relationships (adjusted Jaccard coefficient: 0.300; p<0.001). This is the first study to show that HCV phylogeny is associated with the injecting network, highlighting the importance of the injecting network in HCV transmission.     

NIST lipidomics workflow questionnaire: an assessment of community-wide methodologies and perspectives

Introduction

Efforts to harmonize lipidomic methodologies have been limited within the community. Here, we aimed to capitalize on the recent National Institute of Standards and Technology lipidomics interlaboratory comparison exercise by implementing a questionnaire that assessed current methodologies, quantitation strategies, standard operating procedures (SOPs), and quality control activities employed by the lipidomics community.

Objectives

Lipidomics is a rapidly developing field with diverse applications. At present, there are no community-vetted methods to assess measurement comparability or data quality. Thus, a major impetus of this questionnaire was to profile current efforts, highlight areas of need, and establish future objectives in an effort to harmonize lipidomics workflows.

Methods

The 54-question survey inquired about laboratory demographics, lipidomic methodologies and SOPs, analytical platforms, quantitation, reference materials, quality control procedures, and opinions regarding challenges existing within the community.

Results

A total of 125 laboratories participated in the questionnaire. A broad overview of results highlighted a wide methodological diversity within current lipidomic workflows. The impact of this diversity on lipid measurement and quantitation is currently unknown and needs to be explored further. While some laboratories do incorporate SOPs and quality control activities, these concepts have not been fully embraced by the community. The top five perceived challenges within the lipidomics community were a lack of standardization amongst methods/protocols, lack of lipid standards, software/data handling and quantification, and over-reporting/false positives.

Conclusion

The questionnaire provided an overview of current lipidomics methodologies and further promoted the need for community-accepted guidelines and protocols. The questionnaire also served as a platform to help determine and prioritize metrological issues to be investigated.

     

Evidence against the presence of fibres or chemically distinct layers in the cell wall ofSaccharomyces

The gross chemical composition of material extracted from yeast cell walls with various solvents or enzymes was studied. Attempts were made to locate these materials in situ by comparing electron micrographs of negatively stained and sectioned cell walls with those of the residues of the extraction procedures. There are at least two chemically distinct species of carbohydrate polymers which can be extracted with strong alkali: one yielding mainly mannose and some amino acid on hydrolysis and the other yielding mannose, glucose and amino acid. The alkali-insoluble material also yielded glucose, mannose and amino acid on hydrolysis but the glucose/mannose ratio was much higher. It was shown that none of these polymers constituted a physically distinct layer in the yeast cell wall. However, there does seem to be a region at the outer surface with distinctive properties. This is not fibrillar in nature and after extraction with ethylene diamine forms a double-layered structure. Materials which react with KMnO₄ to produce an electron-dense material are located throughout the wall but tend to be concentrated in the outer and inner regions. Procedures which remove this material also remove up to 80% of the mannose, 40% of the glucose and 35 % of the protein of the original wall material. It was shown that fibres do not constitute a major fraction of the normal cell wall, except possibly in the region of the bud scars but may be produced fairly readily by certain specific treatments. The classical view of the yeast cell wall with the structural integrity being maintained by a fibrous network of 1–3, 1–6 linked glucose residues is challenged and evidence to support an alternative view is presented.The results in wthis paper were presented to the University of Manchester Institute of Science and Technology by JKB in a Thesis for the degree of M.Sc. (Bowden, 1966). The authors are indebted to Miss C. Backhouse and Miss B. Murphy for help in preparing the electron micrographs.