Challenges of Recruiting a Vulnerable Population in a Grounded Theory Study

Recruitment is a crucial and fundamental part of research and one that poses various degrees of difficulty. This is particularly so when the area of research is one that is either highly sensitive, or that involves participants who are deemed to be particularly vulnerable. This article explores the inherent tensions in matters of participant recruitment among meeting the demands of institutional ethics committees, satisfying the concerns of clinicians in the field and the need to maintain methodological rigor. A postgraduate research student’s experience of these tensions underpins the discussion. The article concludes with an outline of the student’s strategies and resolution of these issues.postprin

Polyamide/Polyimide Aerogels

An aerogel and method of making the aerogel is disclosed. The aerogel is a polyimide/polyamide hybrid with a cross-linking agent that induces gelation

A Spectroscopic Survey of the Fields of 28 Strong Gravitational Lenses: Implications for H0H_0

Strong gravitational lensing provides an independent measurement of the Hubble parameter ($H_0$). One remaining systematic is a bias from the additional mass due to a galaxy group at the lens redshift or along the sightline. We quantify this bias for more than 20 strong lenses that have well-sampled sightline mass distributions, focusing on the convergence $\kappa$ and shear $\gamma$. In 23% of these fields, a lens group contributes a $\ge$1% convergence bias; in 57%, there is a similarly significant line-of-sight group. For the nine time delay lens systems, $H_0$ is overestimated by 11$^{+3}_{-2}$% on average when groups are ignored. In 67% of fields with total $\kappa \ge$ 0.01, line-of-sight groups contribute $\gtrsim 2\times$ more convergence than do lens groups, indicating that the lens group is not the only important mass. Lens environment affects the ratio of four (quad) to two (double) image systems; all seven quads have lens groups while only three of 10 doubles do, and the highest convergences due to lens groups are in quads. We calibrate the $\gamma$-$\kappa$ relation: $\log(\kappa_{\rm{tot}}) = (1.94 \pm 0.34) \log(\gamma_{\rm{tot}}) + (1.31 \pm 0.49)$ with a rms scatter of 0.34 dex. Shear, which, unlike convergence, can be measured directly from lensed images, can be a poor predictor of $\kappa$; for 19% of our fields, $\kappa$ is $\gtrsim 2\gamma$. Thus, accurate cosmology using strong gravitational lenses requires precise measurement and correction for all significant structures in each lens field.Comment: 34 pages, 11 figures, accepted for publication in Ap

Inter-individual variation in nucleotide excision repair in young adults: effects of age, adiposity, micronutrient supplementation and genotype

Nucleotide excision repair (NER) is responsible for repairing bulky helix-distorting DNA lesions and is essential for the maintenance of genomic integrity. Severe hereditary impairment of NER leads to cancers such as those in xeroderma pigmentosum, and more moderate reductions in NER capacity have been associated with an increased cancer risk. Diet is a proven modifier of cancer risk but few studies have investigated the potential relationships between diet and NER. In the present study, the plasmid-based host cell reactivation assay was used to measure the NER capacity in peripheral blood mononuclear cells from fifty-seven volunteers aged 18–30 years before and after 6 weeks of supplementation with micronutrients (selenium and vitamins A, C and E). As a control, nine individuals remained unsupplemented over the same period. Volunteers were genotyped for the following polymorphisms in NER genes: ERCC5 Asp1104His (rs17655); XPC Lys939Gln (rs2228001); ERCC2 Lys751Gnl (rs13181); XPC PAT (an 83 bp poly A/T insertion–deletion polymorphism in the XPC gene). NER capacity varied 11-fold between individuals and was inversely associated with age and endogenous DNA strand breaks. For the first time, we observed an inverse association between adiposity and NER. No single polymorphism was associated with the NER capacity, although significant gene–gene interactions were observed between XPC Lys939Gln and ERCC5 Asp1104His and XPC Lys939Gln and ERCC2 Lys751Gnl. While there was no detectable effect of micronutrient supplementation on NER capacity, there was evidence that the effect of fruit intake on the NER capacity may be modulated by the ERCC2 Lys751Gnl single nucleotide polymorphism

Isolation of Plasmodium berghei ookinetes in culture using Nycodenz density gradient columns and magnetic isolation

BACKGROUND: Large scale in vitro production of the mosquito stages of malaria parasites remains elusive, with only limited success for complete sporogonic development and only one report of development through to infective sporozoites. The initial step in this process is the production, in vitro, of ookinetes from gametocytaemic blood. Methods for isolation of these ookinetes from blood cells have been described; however, in addition to yield often being low, processing time and potential for contamination by erythrocytes remain high. METHODS: This study compares two procedures for retaining mature ookinetes from blood stage cultures, whilst removing red blood cells and other contaminants prior to further culture of the parasite. The well established method of isolation on Nycodenz cushions is compared with a novel method utilizing the innate magnetic properties of the haem pigment crystals found in the cytoplasm of ookinetes. RESULTS: Yield and viability of ookinetes were similar with both isolation methods. However, in our hands magnetic isolation produced a cleaner ookinete preparation much more quickly. Moreover, decreasing the flow rate through the magnetic column could further enhance the yield. CONCLUSION: We recommend the enrichment of an ookinete preparation prior to further culture being performed using the magnetic properties of Plasmodium berghei ookinetes as an alternative to their density. The former technique is faster, removes more erythrocytes, but day-to-day costs are greater

Exacerbated inflammatory arthritis in response to hyperactive gp130 signalling is independent of IL-17A

Objective Interleukin (IL)-17A producing CD4 T-cells (TH-17 cells) are implicated in rheumatoid arthritis (RA). IL-6/STAT3 signalling drives TH-17 cell differentiation, and hyperactive gp130/STAT3 signalling in the gp130F/F mouse promotes exacerbated pathology. Conversely, STAT1-activating cytokines (eg, IL-27, IFN-γ) inhibit TH-17 commitment. Here, we evaluate the impact of STAT1 ablation on TH-17 cells during experimental arthritis and relate this to IL-17A-associated pathology. Methods Antigen-induced arthritis (AIA) was established in wild type (WT), gp130F/F mice displaying hyperactive gp130-mediated STAT signalling and the compound mutants gp130F/F:Stat1−/− and gp130F/F: Il17a−/− mice. Joint pathology and associated peripheral TH-17 responses were compared. Results Augmented gp130/STAT3 signalling enhanced TH-17 commitment in vitro and exacerbated joint pathology. Ablation of STAT1 in gp130F/F mice (gp130F/F: Stat1−/− ) promoted the hyperexpansion of TH-17 cells in vitro and in vivo during AIA. Despite this heightened peripheral TH-17 cell response, disease severity and the number of joint-infiltrating T-cells were comparable with that of WT mice. Thus, gp130-mediated STAT1 activity within the inflamed synovium controls T-cell trafficking and retention. To determine the contribution of IL-17A, we generated gp130F/F:IL-17a−/− mice. Here, loss of IL-17A had no impact on arthritis severity. Conclusions Exacerbated gp130/STAT-driven disease in AIA is associated with an increase in joint infiltrating T-cells but synovial pathology is IL-17A independent

Reduced intraepithelial corneal nerve density and sensitivity accompany desiccating stress and aging in C57BL/6 mice

Dry Eye disease causes discomfort and pain in millions of patients. Using a mouse acute desiccating stress (DS) model we show that DS induces a reduction in intraepithelial corneal nerve (ICN) density, corneal sensitivity, and apical extension of the intraepithelial nerve terminals (INTs) that branch from the subbasal nerves (SBNs). Topical application of 0.02% Mitomycin C (MMC) or vehicle alone has no impact on the overall loss of axon density due to acute DS. Chronic dry eye, which develops progressively as C57BL/6 mice age, is accompanied by significant loss of the ICNs and corneal sensitivity between 2 and 24 months of age. QPCR studies show that mRNAs for several proteins that regulate axon growth and extension are reduced in corneal epithelial cells by 24 months of age but those that regulate phagocytosis and autophagy are not altered. Taken together, these data demonstrate that dry eye disease is accompanied by alterations in intraepithelial sensory nerve morphology and function and by reduced expression in corneal epithelial cells of mRNAs encoding genes mediating axon extension. Précis: Acute and chronic mouse models of dry eye disease are used to evaluate the pathologic effects of dry eye on the intraepithelial corneal nerves (ICNs) and corneal epithelial cells. Data show reduced numbers of sensory nerves and alterations in nerve morphology, sensitivity, corneal epithelial cell proliferation, and expression of mRNAs for proteins mediating axon extension accompany the pathology induced by dry eye