Investigating the persistence of tick-borne pathogens via the R-0 model

In the epidemiology of infectious diseases, the basic reproduction number, R-0, has a number of important applications, most notably it can be used to predict whether a pathogen is likely to become established, or persist, in a given area. We used the R-0 model to investigate the persistence of 3 tick-borne pathogens; Babesia microti, Anaplasma phagocytophilum and Borrelia burgdorferi sensu lato in an Apodemus sylvaticus-Ixodes ricinus system. The persistence of these pathogens was also determined empirically by screening questing ticks and wood mice by PCR. All 3 pathogens behaved differently in response to changes in the proportion of transmission hosts on which I. ricinus fed, the efficiency of transmission between the host and ticks and the abundance of larval and nymphal ticks found on small mammals. Empirical data supported theoretical predictions of the R-0 model. The transmission pathway employed and the duration of systemic infection were also identified as important factors responsible for establishment or persistence of tick-borne pathogens in a given tick-host system. The current study demonstrates how the R-0 model can be put to practical use to investigate factors affecting tick-borne pathogen persistence, which has important implications for animal and human health worldwide.

Characterisation of protein stability in rod-insert vaginal rings

A major goal in vaccine development is elimination of the ‘cold chain’, the transport and storage system for maintenance and distribution of the vaccine product. This is particularly pertinent to liquid formulation of vaccines. We have previously described the rod-insert vaginal ring (RiR) device, comprising an elastomeric body into which are inserted lyophilised, rod-shaped, solid drug dosage forms, and having potential for sustained mucosal delivery of biomacromolecules, such as HIV envelope protein-based vaccine candidates. Given the solid, lyophilised nature of these insert dosage forms, we hypothesised that antigen stability may be significantly increased compared with more conventional solubilised vaginal gel format. In this study, we prepared and tested vaginal ring devices fitted with lyophilised rod inserts containing the model antigen bovine serum albumin (BSA). Both the RiRs and the gels that were freeze-dried to prepare the inserts were evaluated for BSA stability using PAGE, turbidimetry, microbial load, MALDI-TOF and qualitative precipitate solubility measurements. When stored at 4 oC, but not when stored at 40 oC / 75% RH, the RiR formulation offered protection against structural and conformational changes to BSA. The insert also retained matrix integrity and release characteristics. The results demonstrate that lypophilised gels can provide relative protection against degradation at lower temperatures compared to semi-solid gels. The major mechanism of degradation at 40 oC / 75% RH was shown to be protein aggregation. Finally, in a preliminary study, we found that addition of trehalose to the formulation significantly reduces the rate of BSA degradation as compared to the original formulation when stored at 40 oC /75% RH. Establishing the mechanism of degradation, and finding that degradation is decelerated in the presence of trehalose, will help inform further development of RiRs specifically and polymer based freeze-dried systems in general.

Late-Holocene marine radiocarbon reservoir correction (Delta R) for the west coast of South Africa

In order to calibrate radiocarbon ages based on samples with a marine carbon component it is important to know the marine carbon reservoir correction or Delta R value. This study measured the Delta R on both known-age pre-bomb marine shells and paired marine and terrestrial samples from two regions on the west coast of South Africa: the southwestern Cape and Namaqualand. Pooling the data by region produces Delta R values that are similar enough to use a west coast weighted mean Delta R of 146 +/- 85 C-14 years to correctly calibrate marine shell or mixed marine and terrestrial C-14 ages. There are however temporal differences in Delta R throughout the Holocene, which we compare with proxy data for upwelling and sea surface temperatures.

Catalysing open innovation through publicly funded R&D: A Comparison of University and Company-based research centres

Public funding of university and company-based R&D centres of excellence is widespread both in core and more peripheral regions. What is less well-known is whether these R&D centres can catalyse multi-directional, multi-actor and iterative innovation. Based on data from a real-time monitoring study, this article explores the development of 18 R&D centres’ external connections. University-based R&D centres establish more new connections than company-based centres and are more likely to be interacting with small or micro-firms. However, there is a general bias towards links with larger firms; micro, small and medium-sized enterprises also are less likely to be involved in collaborative R&D with research centres than other types of relationships. The results suggest the potential for R&D centres to act as a catalyst for open innovation but emphasise the need to ensure that the focus of the R&D being conducted is relevant to the needs of smaller firms.

Development of liposome gel based formulations for intravaginal delivery of the recombinant HIV-1 envelope protein CN54gp140

Mucosally-administered vaccine strategies are widely investigated as a promising means of preventing HIV infection. This study describes the development of liposomal gel formulations, and novel lyophilised variants, comprising HIV-1 envelope glycoprotein, CN54gp140, encapsulated within neutral, positively charged or negatively charged liposomes. The CN54gp140 liposomes were evaluated for mean vesicle diameter, polydispersity, morphology, zeta potential and antigen encapsulation efficiency before being incorporated into hydroxyethyl cellulose (HEC) aqueous gel and subsequently lyophilised to produce a rod-shaped solid dosage form for practical vaginal application. The lyophilised liposome-HEC rods were evaluated for moisture content and redispersibility in simulated vaginal fluid. Since these rods are designed to revert to gel form following intravaginal application, mucoadhesive, mechanical (compressibility and hardness) and rheological properties of the reformed gels were evaluated. The liposomes exhibited good encapsulation efficiency and the gels demonstrated suitable mucoadhesive strength. The freeze-dried liposome-HEC formulations represent a novel formulation strategy that could offer potential as stable and practical dosage form.

Cell type-dependent uptake, localization, and cytotoxicity of 1.9 nm gold nanoparticles

Background: This follow-up study aims to determine the physical parameters which govern the differential radiosensitization capacity of two tumor cell lines and one immortalized normal cell line to 1.9 nm gold nanoparticles. In addition to comparing the uptake potential, localization, and cytotoxicity of 1.9 nm gold nanoparticles, the current study also draws on comparisons between nanoparticle size and total nanoparticle uptake based on previously published data.r/>r/>Methods: We quantified gold nanoparticle uptake using atomic emission spectroscopy and imaged intracellular localization by transmission electron microscopy. Cell growth delay and clonogenic assays were used to determine cytotoxicity and radiosensitization potential, respectively. Mechanistic data were obtained by Western blot, flow cytometry, and assays for reactive oxygen species.r/>r/>Results: Gold nanoparticle uptake was preferentially observed in tumor cells, resulting in an increased expression of cleaved caspase proteins and an accumulation of cells in sub G1 phase. Despite this, gold nanoparticle cytotoxicity remained low, with immortalized normal cells exhibiting an LD50 concentration approximately 14 times higher than tumor cells. The surviving fraction for gold nanoparticle-treated cells at 3 Gy compared with that of untreated control cells indicated a strong dependence on cell type in respect to radiosensitization potential.r/>r/>Conclusion: Gold nanoparticles were most avidly endocytosed and localized within cytoplasmic vesicles during the first 6 hours of exposure. The lack of significant cytotoxicity in the absence of radiation, and the generation of gold nanoparticle-induced reactive oxygen species provide a potential mechanism for previously reported radiosensitization at megavoltage energies.

Association Testing of Previously Reported Variants in a Large Case-Control Meta-analysis of Diabetic Nephropathy

We formed the GEnetics of Nephropathy–an International Effort (GENIE) consortium to examine previously reported genetic associations with diabetic nephropathy (DN) in type 1 diabetes. GENIE consists of 6,366 similarly ascertained participants of European ancestry with type 1 diabetes, with and without DN, from the All Ireland-Warren 3-Genetics of Kidneys in Diabetes U.K. and Republic of Ireland (U.K.-R.O.I.) collection and the Finnish Diabetic Nephropathy Study (FinnDiane), combined with reanalyzed data from the Genetics of Kidneys in Diabetes U.S. Study (U.S. GoKinD). We found little evidence for the association of the EPO promoter polymorphism, rs161740, with the combined phenotype of proliferative retinopathy and end-stage renal disease in U.K.-R.O.I. (odds ratio [OR] 1.14, P = 0.19) or FinnDiane (OR 1.06, P = 0.60). However, a fixed-effects meta-analysis that included the previously reported cohorts retained a genome-wide significant association with that phenotype (OR 1.31, P = 2 × 10-9). An expanded investigation of the ELMO1 locus and genetic regions reported to be associated with DN in the U.S. GoKinD yielded only nominal statistical significance for these loci. Finally, top candidates identified in a recent meta-analysis failed to reach genome-wide significance. In conclusion, we were unable to replicate most of the previously reported genetic associations for DN, and significance for the EPO promoter association was attenuated.

Job Strain and Alcohol Intake:A Collaborative Meta-Analysis of Individual-Participant Data from 140 000 Men and Women

BACKGROUND: The relationship between work-related stress and alcohol intake is uncertain. In order to add to the thus far inconsistent evidence from relatively small studies, we conducted individual-participant meta-analyses of the association between work-related stress (operationalised as self-reported job strain) and alcohol intake. METHODOLOGY AND PRINCIPAL FINDINGS: We analysed cross-sectional data from 12 European studies (n?=?142 140) and longitudinal data from four studies (n?=?48 646). Job strain and alcohol intake were self-reported. Job strain was analysed as a binary variable (strain vs. no strain). Alcohol intake was harmonised into the following categories: none, moderate (women: 1-14, men: 1-21 drinks/week), intermediate (women: 15-20, men: 22-27 drinks/week) and heavy (women: >20, men: >27 drinks/week). Cross-sectional associations were modelled using logistic regression and the results pooled in random effects meta-analyses. Longitudinal associations were examined using mixed effects logistic and modified Poisson regression. Compared to moderate drinkers, non-drinkers and (random effects odds ratio (OR): 1.10, 95% CI: 1.05, 1.14) and heavy drinkers (OR: 1.12, 95% CI: 1.00, 1.26) had higher odds of job strain. Intermediate drinkers, on the other hand, had lower odds of job strain (OR: 0.92, 95% CI: 0.86, 0.99). We found no clear evidence for longitudinal associations between job strain and alcohol intake. CONCLUSIONS: Our findings suggest that compared to moderate drinkers, non-drinkers and heavy drinkers are more likely and intermediate drinkers less likely to report work-related stress.

Job Strain and Tobacco Smoking:An Individual-Participant Data Meta-Analysis of 166 130 Adults in 15 European Studies

BACKGROUND: Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job strain, is associated with tobacco smoking in working adults. METHODOLOGY AND PRINCIPAL FINDINGS: We analysed cross-sectional data from 15 European studies comprising 166 130 participants. Longitudinal data from six studies were used. Job strain and smoking were self-reported. Smoking was harmonised into three categories never, ex- and current. We modelled the cross-sectional associations using logistic regression and the results pooled in random effects meta-analyses. Mixed effects logistic regression was used to examine longitudinal associations. Of the 166 130 participants, 17% reported job strain, 42% were never smokers, 33% ex-smokers and 25% current smokers. In the analyses of the cross-sectional data, current smokers had higher odds of job strain than never-smokers (age, sex and socioeconomic position-adjusted odds ratio: 1.11, 95% confidence interval: 1.03, 1.18). Current smokers with job strain smoked, on average, three cigarettes per week more than current smokers without job strain. In the analyses of longitudinal data (1 to 9 years of follow-up), there was no clear evidence for longitudinal associations between job strain and taking up or quitting smoking. CONCLUSIONS: Our findings show that smokers are slightly more likely than non-smokers to report work-related stress. In addition, smokers who reported work stress smoked, on average, slightly more cigarettes than stress-free smokers.

Photon collisions with atoms and ions within an intermediate-energy R-matrix framework

Recent experimental advances in light technology necessitate the availability of sophisticated theoretical models which can incorporate an accurate treatment of double-electron continua. We describe here a new intermediate-energy R-matrix approach to photoionisation and photo-double-ionisation and illustrate its feasibilty by application to photoionisation and photo-double-ionisation of He, and photodetachment and photo-double-detachment of H^-. Results are shown to be in excellent agreement with previous theoretical and experimental studies. This work is a key step in the development of a multipurpose R-matrix code for multiple-electron ejection. © 2012 American Physical Society

Pharmacokinetics and efficacy of a vaginally administered maraviroc gel in rhesus macaques

Objectives: To investigate the pharmacokinetics (PK) of maraviroc, a CCR5-targeted HIV-1 entry inhibitor, in rhesus macaques following vaginal administration of various maraviroc-loaded aqueous hydroxyethylcellulose (HEC) gels, and to correlate the PK data with efficacy in a single high-dose vaginal SHIV-162P3 challenge model.r/>r/>Methods: Maraviroc concentrations in vaginal fluid (Weck-Cel® sponge), vaginal tissue (punch biopsy) and plasma were assessed over 72 h following single dose vaginal application of various maraviroc-loaded HEC gels. The range of maraviroc gel concentrations was sufficiently broad (0.003 – 3.3% w/w) such that test gels included both fully solubilised and predominantly dispersed formulations. The efficacy of the HEC gels against a single high dose vaginal SHIV-162P3 challenge was also measured, and correlated with the PK concentrations. r/>r/>Results: Maraviroc concentrations in vaginal fluid (range 104 – 107 ng/mL), vaginal tissue (100-1200 ng/g) and plasma (< 102 ng/mL) were highly dependent on maraviroc gel loading, irrespective of the form of the maraviroc component within the gel (solubilised vs. dispersed). Fluid and plasma concentrations were generally highest 0.5 or 2 h after gel application, before declining steadily out to 72 h. Maraviroc concentrations in the various biological compartments correlated strongly with the extent of protection against vaginal SHIV-162P3 challenge. Complete protection was achieved with a 3.3% w/w maraviroc gel. r/>r/>Conclusions: A high degree of correlation between PK and efficacy was observed. Based on the data obtained with the 3.3% w/w maraviroc gel, maintenance of vaginal fluid and tissue levels in the order of 107 ng/mL and 103 ng/g, respectively, are required for complete protection with this compound.

Identification of a UDP-Gal:GlcNAc-R galactosyltransferase activity in Escherichia coli VW187

A novel acceptor substrate for galactosyltransferase was synthesized containing GlcNAcalpha-pyrophosphate, covalently bound to a hydrophobic phenoxyundecyl moiety (GlcNAc alpha-O-PO(3)-PO(3)-(CH(2))(11)-O-Phenyl). The new substrate was used to develop an assay for a galactosyltransferase activity from Escherichia coli strain VW187 that is involved in lipopolysaccharide synthesis and has not been studied by others. We showed that Gal was transferred from UDP-Gal to the novel acceptor substrate. This was a significant improvement over our previous preliminary assays of the enzyme using endogenous substrate, and showed that these synthetic substrates are useful for assaying enzymes that utilize lipid-bound substrates in O-chain synthesis in Gram-negative bacteria.