Willingness to participate in future HIV prevention studies among gay and bisexual men in Scotland, UK: a challenge for intervention trials

This article examines willingness to participate in future HIV prevention research among gay and bisexual men in Scotland, UK. Anonymous, self-complete questionnaires and Orasure Gäó oral fluid samples were collected in commercial gay venues. 1,320 men were eligible for inclusion. 78.2% reported willingness to participate in future HIV prevention research; 64.6% for an HIV vaccine, 57.4% for a behaviour change study, and 53.0% for a rectal microbicide. In multivariate analysis, for HIV vaccine research, greater age, minority ethnicity, and not providing an oral fluid sample were associated with lower willingness; heterosexual orientation and not providing an oral fluid sample were for microbicides; higher education and greater HIV treatment optimism were for behaviour change. STI testing remained associated with being more willing to participate in microbicide research and frequent gay scene use remained associated with being more willing to participate in behaviour change research. Having an STI in the past 12 months remained significantly associated with being willing to participate in all three study types. There were no associations between sexual risk behaviour and willingness. Although most men expressed willingness to participate in future research, recruitment of high-risk men, who have the potential to benefit most, is likely to be more challenging

Prospects for resolving the Hubble constant tension with standard sirens

The Hubble constant ($H_0$) estimated from the local Cepheid-supernova (SN) distance ladder is in 3-$\sigma$ tension with the value extrapolated from cosmic microwave background (CMB) data assuming the standard cosmological model. Whether this tension represents new physics or systematic effects is the subject of intense debate. Here, we investigate how new, independent $H_0$ estimates can arbitrate this tension, assessing whether the measurements are consistent with being derived from the same model using the posterior predictive distribution (PPD). We show that, with existing data, the inverse distance ladder formed from BOSS baryon acoustic oscillation measurements and the Pantheon SN sample yields an $H_0$ posterior near-identical to the Planck CMB measurement. The observed local distance ladder value is a very unlikely draw from the resulting PPD. Turning to the future, we find that a sample of $\sim50$ binary neutron star "standard sirens" (detectable within the next decade) will be able to adjudicate between the local and CMB estimates

Temporal proteomic analysis of HIV infection reveals remodelling of the host phosphoproteome by lentiviral Vif variants

Viruses manipulate host factors to enhance their replication and evade cellular restriction. We used multiplex tandem mass tag (TMT)-based whole cell proteomics to perform a comprehensive time course analysis of >6500 viral and cellular proteins during HIV infection. To enable specific functional predictions, we categorized cellular proteins regulated by HIV according to their patterns of temporal expression. We focussed on proteins depleted with similar kinetics to APOBEC3C, and found the viral accessory protein Vif to be necessary and sufficient for CUL5-dependent proteasomal degradation of all members of the B56 family of regulatory subunits of the key cellular phosphatase PP2A (PPP2R5A-E). Quantitative phosphoproteomic analysis of HIV-infected cells confirmed Vif-dependent hyperphosphorylation of >200 cellular proteins, particularly substrates of the aurora kinases. The ability of Vif to target PPP2R5 subunits is found in primate and non-primate lentiviral lineages, and remodeling of the cellular phosphoproteome is therefore a second ancient and conserved Vif function.This work was supported by a Wellcome Trust PRF (101835/Z/13/Z) to PJL and RTF to NJM (093964/Z/10/Z), NHSBT and the NIHR Cambridge BRC, a Wellcome Trust Strategic Award to CIMR, and the Addenbrooke’s Charitable Trust

Multi-color Molecular Visualization of Signaling Proteins Reveals How C-Terminal Src Kinase Nanoclusters Regulate T Cell Receptor Activation

Elucidating the mechanisms that controlled T cell activation requires visualization of the spatial organization of multiple proteins on the submicron scale. Here, we use stoichiometrically accurate, multiplexed, singlemolecule super-resolution microscopy (DNA-PAINT) to image the nanoscale spatial architecture of the primary inhibitor of the T cell signaling pathway, Csk, and two binding partners implicated in its membrane association, PAG and TRAF3. Combined with a newly developed co-clustering analysis framework, we find that Csk forms nanoscale clusters proximal to the plasma membrane that are lost post-stimulation and are re-recruited at later time points. Unexpectedly, these clusters do not co-localize with PAG at the membrane but instead provide a ready pool of monomers to downregulate signaling. By generating CRISPR-Cas9 knockout T cells, our data also identify that a major risk factor for autoimmune diseases, the protein tyrosine phosphatase non-receptor type 22 (PTPN22) locus, is essential for Csk nanocluster re-recruitment and for maintenance of the synaptic PAG population

A versatile cholera toxin conjugate for neuronal targeting and tracing

Tracing of neurons plays an essential role in elucidating neural networks in the brain and spinal cord. Cholera toxin B subunit (CTB) is already widely used as a tracer although its use is limited by the need for immunohistochemical detection. A new construct incorporating non-canonical azido amino acids (azido-CTB) offers a novel way to expand the range and flexibility of this neuronal tracer. Azido-CTB can be detected rapidly in vivo following intramuscular tongue injection by ‘click’ chemistry, eliminating the need for antibodies. Cadmium selenide/zinc sulfide (CdSe/ZnS) core/shell nanoparticles were attached to azido-CTB by strain-promoted alkyne–azide cycloaddition to make a nano-conjugate. Following tongue injections the complex was detected in vivo in the brainstem by light microscopy and electron microscopy via silver enhancement. This method does not require membrane permeabilization and so ultrastructure is maintained. Azido-CTB offers new possibilities to enhance the utility of CTB as a neuronal tracer and delivery vehicle by modification using ‘click’ chemistry

Effects of hyperoxia on 18F-fluoro-misonidazole brain uptake and tissue oxygen tension following middle cerebral artery occlusion in rodents: Pilot studies.

PURPOSE: Mapping brain hypoxia is a major goal for stroke diagnosis, pathophysiology and treatment monitoring. 18F-fluoro-misonidazole (FMISO) positron emission tomography (PET) is the gold standard hypoxia imaging method. Normobaric hyperoxia (NBO) is a promising therapy in acute stroke. In this pilot study, we tested the straightforward hypothesis that NBO would markedly reduce FMISO uptake in ischemic brain in Wistar and spontaneously hypertensive rats (SHRs), two rat strains with distinct vulnerability to brain ischemia, mimicking clinical heterogeneity. METHODS: Thirteen adult male rats were randomized to distal middle cerebral artery occlusion under either 30% O2 or 100% O2. FMISO was administered intravenously and PET data acquired dynamically for 3hrs, after which magnetic resonance imaging (MRI) and tetrazolium chloride (TTC) staining were carried out to map the ischemic lesion. Both FMISO tissue uptake at 2-3hrs and FMISO kinetic rate constants, determined based on previously published kinetic modelling, were obtained for the hypoxic area. In a separate group (n = 9), tissue oxygen partial pressure (PtO2) was measured in the ischemic tissue during both control and NBO conditions. RESULTS: As expected, the FMISO PET, MRI and TTC lesion volumes were much larger in SHRs than Wistar rats in both the control and NBO conditions. NBO did not appear to substantially reduce FMISO lesion size, nor affect the FMISO kinetic rate constants in either strain. Likewise, MRI and TTC lesion volumes were unaffected. The parallel study showed the expected increases in ischemic cortex PtO2 under NBO, although these were small in some SHRs with very low baseline PtO2. CONCLUSIONS: Despite small samples, the apparent lack of marked effects of NBO on FMISO uptake suggests that in permanent ischemia the cellular mechanisms underlying FMISO trapping in hypoxic cells may be disjointed from PtO2. Better understanding of FMISO trapping processes will be important for future applications of FMISO imaging

Brain hypoxia mapping in acute stroke: Back-to-back T2′ MR versus 18F-fluoromisonidazole PET in rodents

Background Mapping the hypoxic brain in acute ischemic stroke has considerable potential for both diagnosis and treatment monitoring. PET using (18)F-fluoro-misonidazole (FMISO) is the reference method; however, it lacks clinical accessibility and involves radiation exposure. MR-based T2' mapping may identify tissue hypoxia and holds clinical potential. However, its validation against FMISO imaging is lacking. Here we implemented back-to-back FMISO-PET and T2' MR in rodents subjected to acute middle cerebral artery occlusion. For direct clinical relevance, regions of interest delineating reduced T2' signal areas were manually drawn. Methods Wistar rats were subjected to filament middle cerebral artery occlusion, immediately followed by intravenous FMISO injection. Multi-echo T2 and T2* sequences were acquired twice during FMISO brain uptake, interleaved with diffusion-weighted imaging. Perfusion-weighted MR was also acquired whenever feasible. Immediately following MR, PET data reflecting the history of FMISO brain uptake during MR acquisition were acquired. T2' maps were generated voxel-wise from T2 and T2*. Two raters independently drew T2' lesion regions of interest. FMISO uptake and perfusion data were obtained within T2' consensus regions of interest, and their overlap with the automatically generated FMISO lesion and apparent diffusion coefficient lesion regions of interest was computed. Results As predicted, consensus T2' lesion regions of interest exhibited high FMISO uptake as well as substantial overlap with the FMISO lesion and significant hypoperfusion, but only small overlap with the apparent diffusion coefficient lesion. Overlap of the T2' lesion regions of interest between the two raters was ∼50%. Conclusions This study provides formal validation of T2' to map non-core hypoxic tissue in acute stroke. T2' lesion delineation reproducibility was suboptimal, reflecting unclear lesion borders.This study was funded by an EU Grant (EUSTROKE Health-F2-2008-2022131). DJW was funded by an MRC collaborative grant (G0600986), RM by the NIHR Cambridge Biomedical Research Centre, and UJK by a fellowship from the Deutsche Forschungsgemeinschaft (Je 598/1-1)

The DNA methylome of human sperm is distinct from blood with little evidence for tissue-consistent obesity associations

Epidemiological research suggests that paternal obesity may increase the risk of fathering small for gestational age offspring. Studies in non-human mammals indicate that such associations could be mediated by DNA methylation changes in spermatozoa that influence offspring development in utero. Human obesity is associated with differential DNA methylation in peripheral blood. It is unclear, however, whether this differential DNA methylation is reflected in spermatozoa. We profiled genome-wide DNA methylation using the Illumina MethylationEPIC array in a cross-sectional study of matched human blood and sperm from lean (discovery n = 47; replication n = 21) and obese (n = 22) males to analyse tissue covariation of DNA methylation, and identify obesity-associated methylomic signatures. We found that DNA methylation signatures of human blood and spermatozoa are highly discordant, and methylation levels are correlated at only a minority of CpG sites (~1%). At the majority of these sites, DNA methylation appears to be influenced by genetic variation. Obesity-associated DNA methylation in blood was not generally reflected in spermatozoa, and obesity was not associated with altered covariation patterns or accelerated epigenetic ageing in the two tissues. However, one cross-tissue obesity-specific hypermethylated site (cg19357369; chr4:2429884; P = 8.95 × 10^{-8}; 2% DNA methylation difference) was identified, warranting replication and further investigation. When compared to a wide range of human somatic tissue samples (n = 5,917), spermatozoa displayed differential DNA methylation across pathways enriched in transcriptional regulation. Overall, human sperm displays a unique DNA methylation profile that is highly discordant to, and practically uncorrelated with, that of matched peripheral blood. We observed that obesity was only nominally associated with differential DNA methylation in sperm, and therefore suggest that spermatozoal DNA methylation is an unlikely mediator of intergenerational effects of metabolic traits

Analysing detection gaps in acoustic telemetry data to infer differential movement patterns in fish

A wide array of technologies are available for gaining insight into the movement of wild aquatic animals. Although acoustic telemetry can lack the fine‐scale spatial resolution of some satellite tracking technologies, the substantially longer battery life can yield important long‐term data on individual behavior and movement for low per‐unit cost. Typically, however, receiver arrays are designed to maximize spatial coverage at the cost of positional accuracy leading to potentially longer detection gaps as individuals move out of range between monitored locations. This is particularly true when these technologies are deployed to monitor species in hard‐to‐access locations. Here, we develop a novel approach to analyzing acoustic telemetry data, using the timing and duration of gaps between animal detections to infer different behaviors. Using the durations between detections at the same and different receiver locations (i.e., detection gaps), we classify behaviors into “restricted” or potential wider “out‐of‐range” movements synonymous with longer distance dispersal. We apply this method to investigate spatial and temporal segregation of inferred movement patterns in two sympatric species of reef shark within a large, remote, marine protected area (MPA). Response variables were generated using network analysis, and drivers of these movements were identified using generalized linear mixed models and multimodel inference. Species, diel period, and season were significant predictors of “out‐of‐range” movements. Silvertip sharks were overall more likely to undertake “out‐of‐range” movements, compared with gray reef sharks, indicating spatial segregation, and corroborating previous stable isotope work between these two species. High individual variability in “out‐of‐range” movements in both species was also identified. We present a novel gap analysis of telemetry data to help infer differential movement and space use patterns where acoustic coverage is imperfect and other tracking methods are impractical at scale. In remote locations, inference may be the best available tool and this approach shows that acoustic telemetry gap analysis can be used for comparative studies in fish ecology, or combined with other research techniques to better understand functional mechanisms driving behavior

Gene expression drives the evolution of dominance.

Dominance is a fundamental concept in molecular genetics and has implications for understanding patterns of genetic variation, evolution, and complex traits. However, despite its importance, the degree of dominance in natural populations is poorly quantified. Here, we leverage multiple mating systems in natural populations of Arabidopsis to co-estimate the distribution of fitness effects and dominance coefficients of new amino acid changing mutations. We find that more deleterious mutations are more likely to be recessive than less deleterious mutations. Further, this pattern holds across gene categories, but varies with the connectivity and expression patterns of genes. Our work argues that dominance arises as a consequence of the functional importance of genes and their optimal expression levels