A dynamical measure of the black hole mass in a quasar 11 billion years ago

Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.

Fluctuations of a membrane nanotube covered with an actin sleeve

Many biological functions rely on the reshaping of cell membranes, in particular into nanotubes, which are covered in vivo by dynamic actin networks. Nanotubes are subject to thermal fluctuations, but the effect of these on cell functions is unknown. Here, we form nanotubes from liposomes using an optically trapped bead adhering to the liposome membrane. From the power spectral density of this bead, we study the nanotube fluctuations in the range of membrane tensions measured in vivo. We show that an actin sleeve covering the nanotube damps its high-frequency fluctuations because of the network viscoelasticity. Our work paves the way for further studies of the effect of nanotube fluctuations on cellular functions.

The first case of HIV-2 in Scotland

HIV-1 infects an estimated 37 million people worldwide, while the rarer HIV-2 infects 1–2 million worldwide. HIV-2 is mainly restricted to West African countries. The majority of patients in Scotland are diagnosed with HIV-1, but in 2013 the West of Scotland Specialist Virology Centre (WoSSVC) diagnosed Scotland’s first HIV-2 positive case in a patient from Côte d’Ivoire. HIV-2 differs from HIV-1 in terms of structural viral proteins, viral transmissibility, prolonged period of latency, intrinsic resistance to certain antivirals and how to monitor the effectiveness of treatment. Over the course of 5 years the patient has required several changes in treatment due to both side effects and pill burden. This case highlights the complexity of HIV-2 patient management over time.

Actin modulates shape and mechanics of tubular membranes

The actin cytoskeleton shapes cells and also organizes internal membranous compartments. In particular, it interacts with membranes for intracellular transport of material in mammalian cells, yeast, or plant cells. Tubular membrane intermediates, pulled along microtubule tracks, are formed during this process and destabilize into vesicles. While the role of actin in tubule destabilization through scission is suggested, literature also provides examples of actin-mediated stabilization of membranous structures. To directly address this apparent contradiction, we mimic the geometry of tubular intermediates with preformed membrane tubes. The growth of an actin sleeve at the tube surface is monitored spatiotemporally. Depending on network cohesiveness, actin is able to entirely stabilize or locally maintain membrane tubes under pulling. On a single tube, thicker portions correlate with the presence of actin. These structures relax over several minutes and may provide enough time and curvature geometries for other proteins to act on tube stability.

Design Issues for Socially Intelligent User Interfaces

Objectives: This study aims to demonstrate the usability of discourse analyses as a means of evaluating medical informatics systems by examining one particular computer-based data-to-text system for delivering neonatal health care information.

Methods: Six textual summaries of clinical information, three produced by human clinicians and three by the data-to-text system, were subjected to fine-grain discourse analysis. Analysis was performed ‘blind’ on all six textual summaries. Analysis focused on the identification of lexical items and on the potential effects of these items on users of these clinical information summaries.

Results: Results showed that there were clear differences between human- and system-generated clinical summaries, with human clinicians providing better narrative flow and textual detail. The data-to-text system successfully produced textual summaries although it fell short of human abilities.

Conclusions: These results indicate potential future improvements to the system. Discourse analysis as used here may offer significant advantages in evaluating and developing similar medical informatics systems.

Population Pharmacokinetics Modeling of Unbound Efavirenz, Atazanavir, and Ritonavir in HIV-Infected Subjects With Aging Biomarkers

Unbound drug is the pharmacodynamically relevant concentration. This study aimed to determine if chronologic age or markers of biologic aging, such as the frailty phenotype and p16INK4a gene expression, altered unbound pharmacokinetics (PKs) of efavirenz (EFV) and atazanavir/ritonavir (ATV/RTV). Sixty human immunodeficiency virus (HIV)-infected participants receiving EFV and 31 receiving ATV/RTV provided 1 to 11 samples to quantify total and unbound plasma concentrations. Population PK models with total and unbound concentrations simultaneously described are developed for each drug. The unbound fractions for EFV, ATV, and RTV are 0.65%, 5.67%, and 0.63%, respectively. Covariate analysis suggests RTV unbound PK is sensitive to body size; unbound fraction of RTV is 34% lower with body mass index (BMI) above 30 kg/m2 . No alterations in drug clearance or unbound fraction with age, frailty, or p16INK4a expression were observed. Assessing functional and physiologic aging markers to inform potential PK changes is necessary to determine if drug/dosing changes are warranted in the aging population.

p16INK4a , a Senescence Marker, Influences Tenofovir/Emtricitabine Metabolite Disposition in HIV-Infected Subjects

The goal of this study was to explore the relationships between tenofovir (TFV) and emtricitabine (FTC) disposition and markers of biologic aging, such as the frailty phenotype and p16^INK4a gene expression. Chronologic age is often explored in population pharmacokinetic (PK) analyses, and can be uninformative in capturing the impact of aging on physiology, particularly in human immunodeficiency virus (HIV)‐infected patients. Ninety‐one HIV‐infected participants provided samples to quantify plasma concentrations of TFV/FTC, as well as peripheral blood mononuclear cell (PBMC) samples for intracellular metabolite concentrations; 12 participants provided 11 samples, and 79 participants provided 4 samples, over a dosing interval. Nonlinear mixed effects modeling of TFV/FTC and their metabolites suggests a relationship between TFV/FTC metabolite clearance (CL) from PBMCs and the expression of p16^INK4a, a marker of cellular senescence. This novel approach to quantifying the influence of aging on PKs provides rationale for further work investigating the relationships between senescence and nucleoside phosphorylation and transport.

Fluctuations of a membrane nanotube revealed by high-resolution force measurements

Pulling membrane nanotubes from liposomes presents a powerful method to gain access to membrane mechanics. Here we extend classical optical tweezers studies to infer membrane nanotube dynamics with high spatial and temporal resolution. We first validate our force measurement setup by accurately measuring the bending modulus of EPC membrane in tube pulling experiments. Then we record the position signal of a trapped bead when it is connected, or not, to a tube. We derive the fluctuation spectrum of these signals and find that the presence of a membrane nanotube induces higher fluctuations, especially at low frequencies (10-1000 Hz). We analyse these spectra by taking into account the peristaltic modes of nanotube fluctuations. This analysis provides a new experimental framework for a quantitative study of the fluctuations of nanotubular membrane structures that are present in living cells, and now classically used for in vitro biomimetic approaches.

How cellular membrane properties are affected by the actin cytoskeleton

Lipid membranes define the boundaries of living cells and intracellular compartments. The dynamic remodelling of these membranes by the cytoskeleton, a very dynamic structure made of active biopolymers, is crucial in many biological processes such as motility or division. In this review, we present some aspects of cellular membranes and how they are affected by the presence of the actin cytoskeleton. We show that, in parallel with the direct study of membranes and cytoskeleton in vivo, biomimetic in vitro systems allow reconstitution of biological processes in a controlled environment. In particular, we show that liposomes, or giant unilamellar vesicles, encapsulating a reconstituted actin network polymerizing at their membrane are suitable models of living cells and can be used to decipher the relative contributions of membrane and actin on the mechanical properties of the cellular interface.

Elvitegravir concentrations in seminal plasma in HIV-1-infected men

OBJECTIVES

The aim of the study was to quantify elvitegravir (EVG) concentrations in the semen of HIV-1-infected men receiving antiretroviral therapy (ART) consisting of an elvitegravir/cobicistat/emtricitabine/tenofovir (EVG/COBI/FTC/TDF) single-tablet regimen.

METHODS

A phase IV, cross-sectional study was carried out including HIV-1-infected male adults with suppressed plasma HIV-1 RNA who switched ART to EVG/COBI/FTC/TDF. Total EVG concentrations at the end of the dosing interval (C_{24 h} ) and HIV-1 RNA were measured in paired seminal plasma (SP) and blood plasma (BP) samples 4 weeks after switching to EVG/COBI/FTC/TDF. Validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify EVG concentrations, and HIV-1 RNA was determined by real-time polymerase chain reaction (PCR).

RESULTS

Ten men were included. Their median age was 40 years (range 24-47 years), the median time on ART was 50 months (range 10-186 months), the median time with plasma HIV-1 RNA < 40 copies/mL was 37 months (range 7-113 months), and the median CD4 count was 737 cells/μL (range 190-1122 cells/μL). Four weeks after switching to EVG/COBI/FTC/TDF, all subjects had HIV-1 RNA < 40 copies/mL in both BP and SP. Median EVG C_{24 h} was 277 ng/mL (range 64.8-1790 ng/mL) in BP and 169 ng/mL (range 12.8-792 ng/mL) in SP. A significant correlation was observed between BP and SP EVG concentrations (Spearman rho 0.952; P < 0.001). The median SP:BP EVG concentration ratio was 0.39 (range 0.20-0.92). EVG C_{24 h} in SP was at least 23-fold the in vitro protein-unbound 50% effective response (EC₅₀ ) of HIV-1 clinical isolates (0.04-0.55 ng/mL). In all but one individual, EVG C_{24 h} in SP was also higher than the blood plasma protein binding-adjusted 95% inhibitory concentration (IC₉₅ ) of wild-type HIV-1 (45 ng/mL).

CONCLUSIONS

Seminal EVG concentrations in HIV-infected men treated with EVG/COBI/FTC/TDF sufficed to contribute to maintaining HIV-1 RNA suppression in this compartment.

Cell-sized liposome doublets reveal active tension build-up driven by acto-myosin dynamics

Cells modulate their shape to fulfill specific functions, mediated by the cell cortex, a thin actin shell bound to the plasma membrane. Myosin motor activity, together with actin dynamics, contributes to cortical tension. Here, we examine the individual contributions of actin polymerization and myosin activity to tension increase with a non-invasive method. Cell-sized liposome doublets are covered with either a stabilized actin cortex of preformed actin filaments, or a dynamic branched actin network polymerizing at the membrane. The addition of myosin II minifilaments in both cases triggers a change in doublet shape that is unambiguously related to a tension increase. Preformed actin filaments allow us to evaluate the effect of myosin alone while, with dynamic actin cortices, we examine the synergy of actin polymerization and myosin motors in driving shape changes. Our assay paves the way for a quantification of tension changes triggered by various actin-associated proteins in a cell-sized system.

Standardised (plain) cigarette packaging increases attention to both text-based and graphical health warnings: experimental evidence

Objective

To investigate whether standardised cigarette packaging increases the time spent looking at health warnings, regardless of the format of those warnings.

Study design

A factorial (two pack styles x three warning types) within-subject experiment, with participants randomised to different orders of conditions, completed at a university in London, UK.

Methods

Mock-ups of cigarette packets were presented to participants with their branded portion in either standardised (plain) or manufacturer-designed (branded) format. Health warnings were present on all packets, representing all three types currently in use in the UK: black & white text, colour text, or colour images with accompanying text. Gaze position was recorded using a specialised eye tracker, providing the main outcome measure, which was the mean proportion of a five-second viewing period spent gazing at the warning-label region of the packet.

Results

An opportunity sample of 30 (six male, mean age = 23) young adults met the following inclusion criteria: 1) not currently a smoker; 2) <100 lifetime cigarettes smoked; 3) gaze position successfully tracked for > 50% viewing time. These participants spent a greater proportion of the available time gazing at the warning-label region when the branded section of the pack was standardised (following current Australian guidelines) rather than containing the manufacturer's preferred design (mean difference in proportions = 0.078, 95% confidence interval 0.049 to 0.106, p < 0.001). There was no evidence that this effect varied based on the type of warning label (black & white text vs. colour text vs. colour image & text; interaction p = 0.295).

Conclusions

During incidental viewing of cigarette packets, young adult never-smokers are likely to spend more time looking at health warnings if manufacturers are compelled to use standardised packaging, regardless of the warning design.

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Standardised cigarette packs could increase the saliency of health warnings.

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Eye tracking can reveal how visual attention is allocated.

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Previous studies only assessed combined image-and-text health warnings.

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We found standardised packs increased attention to all current UK warning types.

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This provides additional support for statutory standardised cigarette packaging.

Pharmacokinetics of two common antiretroviral regimens in older HIV-infected patients: a pilot study

OBJECTIVES

The pharmacokinetics (PK) of antiretrovirals (ARVs) in older HIV-infected patients are poorly described. Here, the steady-state PK of two common ARV regimens [tenofovir (TFV)/emtricitabine (FTC)/efavirenz (EFV) and TFV/FTC/atazanavir (ATV)/ritonavir (RTV)] in older nonfrail HIV-infected patients are presented.

METHODS

HIV-infected subjects ≥ 55 years old not demonstrating the frailty phenotype were enrolled in an unblinded, intensive-sampling PK study. Blood plasma (for TFV, FTC, EFV, ATV and RTV concentrations) and peripheral blood mononuclear cells [PBMCs; for tenofovir diphosphate (TFV-DP) and emtricitabine triphosphate (FTC-TP) concentrations] were collected at 11 time-points over a 24-hour dosing interval. Drug concentrations were analysed using validated liquid chromatography-ultraviolet detection (LC-UV) or liquid chromatography tandem mass spectrometry (LC-MS/MS) methods. Noncompartmental pharmacokinetic analysis was used to estimate PK parameters [area under the concentration-time curve over 24 h (AUC0-24h ) and maximal concentration (Cmax )]. These parameters were compared with historical values from the general HIV-infected population.

RESULTS

Six subjects on each regimen completed the study. Compared with the general population, these elderly subjects had 8-13% decreased TFV AUC0-24h and Cmax , and 19-78% increased FTC and RTV AUC0-24h and Cmax . Decreased ATV AUC0-24h (12%) and increased Cmax (9%) were noted, while EFV exposure was unchanged (5%) with a 16% decrease in Cmax . Intracellular nucleoside/tide metabolite concentrations and AUC are also reported for these subjects.

CONCLUSIONS

This study demonstrates that the PK of these ARVs are altered by 5-78% in an older HIV-infected population. Implications of PK differences for clinical outcomes, particularly with the active nucleoside metabolites, remain to be explored. This study forms the basis for further study of ARV PK, efficacy, and toxicity in older HIV-infected patients.

The WHO Family of International Classifications

The concept of the Family of International Classifications has been created to have a common framework and language to report, compile, use, and compare health information at the national and international level. The family brings together different health classifications dealing with various dimensions of health and health care so as to present a more comprehensive picture of health care. The family of classifications in health consists of reference classifications, derived ones and related ones. The reference classifications cover the areas of death and disease, disability and health interventions. Other members cover fields like drugs, causes of injury and reasons for encounter. These classifications represent the building blocks of health information in order to be able to provide the best possible health to all people.

Adhesive capsulitis: sonographic changes in the rotator cuff interval with arthroscopic correlation

OBJECTIVE

To evaluate the sonographic findings of the rotator interval in patients with clinical evidence of adhesive capsulitis immediately prior to arthroscopy.

DESIGN AND PATIENTS

We prospectively compared 30 patients with clinically diagnosed adhesive capsulitis (20 females, 10 males, mean age 50 years) with a control population of 10 normal volunteers and 100 patients with a clinical suspicion of rotator cuff tears. Grey-scale and colour Doppler sonography of the rotator interval were used.

RESULTS

Twenty-six patients (87%) demonstrated hypoechoic echotexture and increased vascularity within the rotator interval, all of whom had had symptoms for less than 1 year. Three patients had hypoechoic echotexture but no increase in vascularity, and one patient had a normal sonographic appearance. All patients were shown to have fibrovascular inflammatory soft-tissue changes in the rotator interval at arthroscopy commensurate with adhesive capsulitis. None of the volunteers or the patients with a clinical diagnosis of rotator cuff tear showed such changes.

CONCLUSIONS

Sonography can provide an early accurate diagnosis of adhesive capsulitis by assessing the rotator interval for hypoechoic vascular soft tissue.

ActA and human zyxin harbour Arp2/3-independent actin-polymerization activity

The actin cytoskeleton is a dynamic network that is composed of a variety of F-actin structures. To understand how these structures are produced, we tested the capacity of proteins to direct actin polymerization in a bead assay in vitro and in a mitochondrial-targeting assay in cells. We found that human zyxin and the related protein ActA of Listeria monocytogenes can generate new actin structures in a vasodilator-stimulated phosphoprotein-dependent (VASP) manner, but independently of the Arp2/3 complex. These results are consistent with the concept that there are multiple actin-polymerization machines in cells. With these simple tests it is possible to probe the specific function of proteins or identify novel molecules that act upon cellular actin polymerization.

Growing an actin gel on spherical surfaces

Inspired by the motility of the bacteria Listeria monocytogenes, we have experimentally studied the growth of an actin gel around spherical beads grafted with ActA, a protein known to be the promoter of bacteria movement. On ActA-grafted beads F-actin is formed in a spherical manner, whereas on the bacteria a "comet-like" tail of F-actin is produced. We show experimentally that the stationary thickness of the gel depends on the radius of the beads. Moreover, the actin gel is not formed if the ActA surface density is too low. To interpret our results, we propose a theoretical model to explain how the mechanical stress (due to spherical geometry) limits the growth of the actin gel. Our model also takes into account treadmilling of actin. We deduce from our work that the force exerted by the actin gel on the bacteria is of the order of 10 pN. Finally, we estimate from our theoretical model possible conditions for developing actin comet tails.

The characteristics and intervention histories of incarcerated and conduct-disordered youth

OBJECTIVES

1) To determine if incarcerated youth and conduct-disordered youth in treatment display similar risk factors associated with chronicity of antisocial behaviour; 2) to determine if incarcerated youth had experienced high numbers of interventions by many different agencies as has been reported for conduct-disordered youth in treatment.

METHOD

The files of 25 conduct-disordered youth in treatment and 25 incarcerated youth were examined to extract all relevant data.

RESULTS

Incarcerated youth were similar to conduct-disordered youth with regard to the number of symptoms of disruptive behaviour disorders, age of onset of behavioural problems, and family backgrounds. Both groups had high numbers of interventions and agencies in their histories. Interventions began earlier for the conduct-disordered youth.

CONCLUSION

The distinction between conduct-disordered youth who are treated and youth who are incarcerated may be arbitrary and accidental. Given the similarity in the clinical characteristics, incarcerated youth should be offered help that is similar to that offered to conduct-disordered youth. Such help may lower the rate of recidivism.

Continuity of care for conduct disordered youth

The objectives of this study were to determine which risk factors associated with chronicity had been displayed by youths who had been treated for conduct disorder in a tertiary level mental health centre and also to count the number of interventions and the number of agencies involved during their many years in treatment. The files of 25 youths with conduct disorder were examined to extract all relevant data. The youths averaged nine years between first intervention and last discharge. Common risk factors were the early onset and the variety of antisocial behaviours and the multiple settings in which behaviours occurred. The youths experienced an average of 19 interventions by 15 agencies. Interventions lasted on average seven months with little occurrence of follow-up. The severity of antisocial behaviours increased from first to last intervention. The apparent ineffectiveness of treatment may be related to the short duration of treatments and the lack of follow-up which resulted in the involvement of many agencies.

Immunoglobulin isotype production by cycling human B lymphocytes in response to recombinant cytokines and anti-IgM

Actively cycling populations of purified human tonsilar B lymphocytes were examined for their capacity to secrete IgM, IgA, IgE and IgG of all four subclasses in direct response to recombinant cytokines; in some experiments, monoclonal antibody to IgM (anti-mu) was included in order to explore the influence of antigen receptor ligation on immunoglobulin (Ig) production. Enhanced IgM release was seen on culture of the cycling cells with either interleukin-2 (IL-2), IL-4 or interferon-alpha (IFN-alpha). IL-2 and IFN-alpha also augmented IgA production, whereas IL-4 had no effect on this isotype. IL-4 did, however, encourage the production of the IgG subclasses IgG1, IgG2 and IgG3, while IL-2 augmented IgG1 and IgG3 release and IFN-alpha increased IgG1 levels. IgG4 production, and that of IgE, failed to be perturbed by any of the cytokines assayed. Neither IL-1 alpha, IL-1 beta, IL-5 nor IFN-gamma significantly altered the profile of Ig isotype release. When confronted with anti-mu, cycling B cells demonstrated a marked suppression in IgM production. Suppression could not be overcome by the addition to culture of the normally IgM-promoting IL-4. Concomitant with the reduction in IgM levels, an increase in IgG release was observed. This was comprised of elevations in IgG1 and IgG3. Although not influencing IgA release directly, anti-mu was found to promote increased IgA production in co-culture with either IL-2 or IFN-alpha. The findings are discussed in the context of recent findings on Ig isotype control in both human and murine systems.

Chronic administration of the GABA-transaminase inhibitor ethanolamine O-sulphate leads to up-regulation of GABA binding sites

In rats receiving the gamma-aminobutyric acid (GABA)-transaminase inhibitor ethanolamine O-sulphate (EOS) in their drinking water for up to 28 days, the number of GABAA and GABAB binding sites was increased compared to controls. There was no change in binding affinity at GABAA or GABAB sites. One week after EOS withdrawal, the number of GABAA and GABAAB sites in previously treated EOS rats did not differ from controls. There was no difference in the number or affinity of benzodiazepine binding sites between EOS-treated and control rats during EOS administration or withdrawal. There was no difference in the stimulation of benzodiazepine binding by GABA (alone or in the presence of NaCl) during EOS administration. Cortical and cerebellar GABA concentration was increased 3.2- to 4.6-fold and cortical glutamate decarboxylase (GAD) activity reduced 30-42%. The current required to induce electroshock convulsions did not differ between EOS-treated rats and control rats during EOS administration. We speculate that the stimulus for the increased number of GABAA and GABAB binding sites is a reduction in GABA release subsequent to a reduction in GAD activity.

Impromidine (SK & F 92676) acts as a partial agonist on the isolated whole stomach of the rat

The present secretory studies on the isolated stomach of the rat provide evidence that impromidine acts as a partial agonist at the histamine H2-receptors. It was found to be 100 times more potent than histamine but with a maximal response only 50% that obtained with histamine.