Elastic properties of grafted microtubules

We use single-particle tracking to study the elastic properties of single microtubules grafted to a substrate. Thermal fluctuations of the free microtubule's end are recorded, in order to measure position distribution functions from which we calculate the persistence length of microtubules with contour lengths between 2.6 and 48 micrometers. We find the persistence length to vary by more than a factor of 20 over the total range of contour lengths. Our results support the hypothesis that shearing between protofilaments contributes significantly to the mechanics of microtubules.Comment: 9 pages, 3 figure

A socio-ecological analysis of factors influencing HIV treatment initiation and adherence among key populations in Papua New Guinea

Background: In Papua New Guinea (PNG) members of key populations, including female sex workers (FSW), men who have sex with men (MSM) and transgender women (TGW), have higher rates of HIV compared to the general adult population and low engagement in HIV care. This paper examines the socio-ecological factors that encourage or hinder HIV treatment initiation and adherence among HIV positive members of key populations in PNG. Methods: As part of a larger biobehavioural survey of key populations in PNG, 111 semi-structured interviews were conducted with FSW, MSM and TGW, of whom 28 identified as living with HIV. Interviews from 28 HIV positive participants are used in this analysis of the influences that enabled or inhibited HIV treatment initiation and treatment adherence. Results: Enablers included awareness of the biomedical benefits of treatment; experiences of the social, familial and health benefits of early treatment initiation and adherence; support provided by family and friends; and nonjudgmental and supportive HIV service provision. Factors that inhibited treatment initiation and adherence included perception of good health and denial of HIV diagnosis; poor family support following positive diagnosis; and anonymity and stigma concerns in HIV care services. Conclusion: Exploring health promotion messages that highlight the positive health impacts of early treatment initiation and adherence; providing client-friendly services and community-based treatment initiation and supply; and rolling out HIV viral load testing across the country could improve health outcomes for these key populations

Convergent and parallel evolution in life habit of the scallops (Bivalvia: Pectinidae)

<p>Abstract</p> <p>Background</p> <p>We employed a phylogenetic framework to identify patterns of life habit evolution in the marine bivalve family Pectinidae. Specifically, we examined the number of independent origins of each life habit and distinguished between convergent and parallel trajectories of life habit evolution using ancestral state estimation. We also investigated whether ancestral character states influence the frequency or type of evolutionary trajectories.</p> <p>Results</p> <p>We determined that temporary attachment to substrata by byssal threads is the most likely ancestral condition for the Pectinidae, with subsequent transitions to the five remaining habit types. Nearly all transitions between life habit classes were repeated in our phylogeny and the majority of these transitions were the result of parallel evolution from byssate ancestors. Convergent evolution also occurred within the Pectinidae and produced two additional gliding clades and two recessing lineages. Furthermore, our analysis indicates that byssal attaching gave rise to significantly more of the transitions than any other life habit and that the cementing and nestling classes are only represented as evolutionary outcomes in our phylogeny, never as progenitor states.</p> <p>Conclusions</p> <p>Collectively, our results illustrate that both convergence and parallelism generated repeated life habit states in the scallops. Bias in the types of habit transitions observed may indicate constraints due to physical or ontogenetic limitations of particular phenotypes.</p

Risk factors for Coronavirus disease 2019 (Covid-19) death in a population cohort study from the Western Cape province, South Africa

Risk factors for coronavirus disease 2019 (COVID-19) death in sub-Saharan Africa and the effects of human immunodeficiency virus (HIV) and tuberculosis on COVID-19 outcomes are unknown. We conducted a population cohort study using linked data from adults attending public-sector health facilities in the Western Cape, South Africa. We used Cox proportional hazards models, adjusted for age, sex, location, and comorbidities, to examine the associations between HIV, tuberculosis, and COVID-19 death from 1 March to 9 June 2020 among (1) public-sector “active patients” (≥1 visit in the 3 years before March 2020); (2) laboratory-diagnosed COVID-19 cases; and (3) hospitalized COVID-19 cases. We calculated the standardized mortality ratio (SMR) for COVID-19, comparing adults living with and without HIV using modeled population estimates.Among 3 460 932 patients (16% living with HIV), 22 308 were diagnosed with COVID-19, of whom 625 died. COVID19 death was associated with male sex, increasing age, diabetes, hypertension, and chronic kidney disease. HIV was associated with COVID-19 mortality (adjusted hazard ratio [aHR], 2.14; 95% confidence interval [CI], 1.70–2.70), with similar risks across strata of viral loads and immunosuppression. Current and previous diagnoses of tuberculosis were associated with COVID-19 death (aHR, 2.70 [95% CI, 1.81–4.04] and 1.51 [95% CI, 1.18–1.93], respectively). The SMR for COVID-19 death associated with HIV was 2.39 (95% CI, 1.96–2.86); population attributable fraction 8.5% (95% CI, 6.1–11.1)

Investigation of integrin expression on the surface of osteoblast-like cells by atomic force microscopy.

The transforming growth factor beta1 (TGF-beta1) is a human cytokine which has been demonstrated to modulate cell surface integrin repertoire. In this work integrin expression in response to TGF-beta1 stimulation has been investigated on the surface of human osteoblast-like cells. We used atomic force microscopy (AFM) and confocal laser scanning microscopy to assess integrin expression and to evaluate their distribution over the dorsal side of the plasma membrane. AFM probes have been covalently functionalized with monoclonal antibodies specific to the beta1 integrin subunit. Force curves have been collected in order to obtain maps of the interaction between the immobilized antibody and the respective cell membrane receptors. Adhesion peaks have been automatically detected by means of an ad hoc developed data analysis software. The specificity of the detected interactions has been assessed by adding free antibody in the solution and monitoring the dramatic decrease in the recorded interactions. In addition, the effect of TGF-beta1 treatment on both the fluorescence signal and the adhesion events has been tested. The level of expression of the beta1 integrin subunit was enhanced by TGF-beta1. As a further analysis, the adhesion force of the single living cells to the substrate was measured by laterally pushing the cell with the AFM tip and measuring the force necessary to displace it. The treatment with TGF-beta1 resulted in a decrease of the cell/substrate adhesion force. Results obtained by AFM have been validated by confocal laser scanning microscopy thus demonstrating the high potential of the AFM technique for the investigation of cell surface receptors distribution and trafficking at the nanoscale

Schwann cell TRPA1 mediates neuroinflammation that sustains macrophage-dependent neuropathic pain in mice.

It is known that transient receptor potential ankyrin 1 (TRPA1) channels, expressed by nociceptors, contribute to neuropathic pain. Here we show that TRPA1 is also expressed in Schwann cells. We found that in mice with partial sciatic nerve ligation, TRPA1 silencing in nociceptors attenuated mechanical allodynia, without affecting macrophage infiltration and oxidative stress, whereas TRPA1 silencing in Schwann cells reduced both allodynia and neuroinflammation. Activation of Schwann cell TRPA1 evoked NADPH oxidase 1 (NOX1)-dependent H2O2 release, and silencing or blocking Schwann cell NOX1 attenuated nerve injury-induced macrophage infiltration, oxidative stress and allodynia. Furthermore, the NOX2-dependent oxidative burst, produced by macrophages recruited to the perineural space activated the TRPA1-NOX1 pathway in Schwann cells, but not TRPA1 in nociceptors. Schwann cell TRPA1 generates a spatially constrained gradient of oxidative stress, which maintains macrophage infiltration to the injured nerve, and sends paracrine signals to activate TRPA1 of ensheathed nociceptors to sustain mechanical allodynia

“This is really something: same place, same day result, same day treatment” women’s experiences of testing positive for HPV and receiving same-day treatment in Papua New Guinea: an interpretative phenomenological analysis

Abstract Introduction Human papillomavirus (HPV) testing is transforming cervical screening globally. The World Health Organization (WHO) now recommends same-day HPV screen-and-treat for primary cervical screening in low- and middle-income countries (LMIC) but there is a lack of evidence on women’s lived experience of testing positive for oncogenic HPV and receiving same-day treatment. This study aimed to address this knowledge gap among women participating in a same-day HPV screen-and-treat (HPV S&T) program in Papua New Guinea. Methods As part of a larger qualitative study, this paper explores the lived experiences of 26 women who tested positive for oncogenic HPV and were treated the same day. We analysed the data using the interpretative phenomenological analysis method. All data were managed using Nvivo 12.5. Results The interpretative phenomenological analysis led to three superordinate themes: 1) facing and alleviating initial worries, (2) transforming the disclosure process, and (3) connecting to their faith. Women’s experiences of the same day HPV screen-and-treat were framed by initial emotional reactions to their positive HPV test result, and having access to treatment on the same day, which helped address their worries and fears, and transformed their experience of disclosing their test result and subsequent treatment to family and friends. Conclusion This study shows that, while women experience similar initial emotional reactions, undergoing same day treatment quickly resolved the women’s worries, making this program highly acceptable. Overall, women’s engagement in the program confirmed its high acceptability and cultural congruence, leaving women feeling empowered and hopeful about their future, and the future of all Papua New Guinea women