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885 result(s) for "Stephens, Richard"
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Key considerations to reduce or address respondent burden in patient-reported outcome (PRO) data collection
Patient-reported outcomes (PROs) are used in clinical trials to provide evidence of the benefits and risks of interventions from a patient perspective and to inform regulatory decisions and health policy. The collection of PROs in routine practice can facilitate monitoring of patient symptoms; identification of unmet needs; prioritisation and/or tailoring of treatment to the needs of individual patients and inform value-based healthcare initiatives. However, respondent burden needs to be carefully considered and addressed to avoid high rates of missing data and poor reporting of PRO results, which may lead to poor quality data for regulatory decision making and/or clinical care. The collection of patient-reported outcomes (PROs) may capture patients’ assessments of their health status. Here authors highlight PRO-specific issues that should be considered to minimise respondent burden in clinical trials and routine care.
Mechanisms of host cell exit by the intracellular bacterium Chlamydia
The mechanisms that mediate the release of intracellular bacteria from cells are poorly understood, particularly for those that live within a cellular vacuole. The release pathway of the obligate intracellular bacterium Chlamydia from cells is unknown. Using a GFP-based approach to visualize chlamydial inclusions within cells by live fluorescence videomicroscopy, we identified that Chlamydia release occurred by two mutually exclusive pathways. The first, lysis, consisted of an ordered sequence of membrane permeabilizations: inclusion, nucleus and plasma membrane rupture. Treatment with protease inhibitors abolished inclusion lysis. Intracellular calcium signaling was shown to be important for plasma membrane breakdown. The second release pathway was a packaged release mechanism, called extrusion. This slow process resulted in a pinching of the inclusion, protrusion out of the cell within a cell membrane compartment, and ultimately detachment from the cell. Treatment of Chlamydia-infected cells with specific pharmacological inhibitors of cellular factors demonstrated that extrusion required actin polymerization, neuronal Wiskott-Aldrich syndrome protein, myosin II and Rho GTPase. The participation of Rho was unique in that it functioned late in extrusion. The dual nature of release characterized for Chlamydia has not been observed as a strategy for intracellular bacteria.
High-density stable glasses formed on soft substrates
Enabled by surface-mediated equilibration, physical vapour deposition can create high-density stable glasses comparable with liquid-quenched glasses aged for millions of years. Deposition is often performed at various rates and temperatures on rigid substrates to control the glass properties. Here we demonstrate that on soft, rubbery substrates, surface-mediated equilibration is enhanced up to 170 nm away from the interface, forming stable glasses with densities up to 2.5% higher than liquid-quenched glasses within 2.5 h of deposition. Gaining similar properties on rigid substrates would require 10 million times slower deposition, taking ~3,000 years. Controlling the modulus of the rubbery substrate provides control over the glass structure and density at constant deposition conditions. These results underscore the significance of substrate elasticity in manipulating the properties of the mobile surface layer and thus the glass structure and properties, allowing access to deeper states of the energy landscape without prohibitively slow deposition rates. Controlling substrate elasticity during physical vapour deposition allows access to high-density stable glasses that would otherwise be formed under prohibitively slow deposition conditions on rigid substrates.
Polyamorphism of vapor-deposited amorphous selenium in response to light
Enhanced surface mobility is critical in producing stable glasses during physical vapor deposition. In amorphous selenium (a-Se) both the structure and dynamics of the surface can be altered when exposed to above-bandgap light. Here we investigate the effect of light on the properties of vapor-deposited a-Se glasses at a range of substrate temperatures and deposition rates. We demonstrate that deposition both under white light illumination and in the dark results in thermally and kinetically stable glasses. Compared to glasses deposited in the dark, stable a-Se glasses formed under white light have reduced thermal stability, as measured by lower density change, but show significantly improved kinetic stability, measured as higher onset temperature for transformation. While light induces enhanced mobility that penetrates deep into the surface, resulting in lower density during vapor deposition, it also acts to form more networked structures at the surface, which results in a state that is kinetically more stable with larger optical birefringence. We demonstrate that the structure formed during deposition with light is a state that is not accessible through liquid quenching, aging, or vapor deposition in the dark, indicating the formation of a unique amorphous solid state.
Preoperative radiotherapy versus selective postoperative chemoradiotherapy in patients with rectal cancer (MRC CR07 and NCIC-CTG C016): a multicentre, randomised trial
Preoperative or postoperative radiotherapy reduces the risk of local recurrence in patients with operable rectal cancer. However, improvements in surgery and histopathological assessment mean that the role of radiotherapy needs to be reassessed. We compared short-course preoperative radiotherapy versus initial surgery with selective postoperative chemoradiotherapy. We undertook a randomised trial in 80 centres in four countries. 1350 patients with operable adenocarcinoma of the rectum were randomly assigned, by a minimisation procedure, to short-course preoperative radiotherapy (25 Gy in five fractions; n=674) or to initial surgery with selective postoperative chemoradiotherapy (45 Gy in 25 fractions with concurrent 5-fluorouracil) restricted to patients with involvement of the circumferential resection margin (n=676). The primary outcome measure was local recurrence. Analysis was by intention to treat. This study is registered, number ISRCTN 28785842. At the time of analysis, which included all participants, 330 patients had died (157 preoperative radiotherapy group vs 173 selective postoperative chemoradiotherapy), and median follow-up of surviving patients was 4 years. 99 patients had developed local recurrence (27 preoperative radiotherapy vs 72 selective postoperative chemoradiotherapy). We noted a reduction of 61% in the relative risk of local recurrence for patients receiving preoperative radiotherapy (hazard ratio [HR] 0·39, 95% CI 0·27–0·58, p<0·0001), and an absolute difference at 3 years of 6·2% (95% CI 5·3–7·1) (4·4% preoperative radiotherapy vs 10·6% selective postoperative chemoradiotherapy). We recorded a relative improvement in disease-free survival of 24% for patients receiving preoperative radiotherapy (HR 0·76, 95% CI 0·62–0·94, p=0·013), and an absolute difference at 3 years of 6·0% (95% CI 5·3–6·8) (77·5% vs 71·5%). Overall survival did not differ between the groups (HR 0·91, 95% CI 0·73–1·13, p=0·40). Taken with results from other randomised trials, our findings provide convincing and consistent evidence that short-course preoperative radiotherapy is an effective treatment for patients with operable rectal cancer. Medical Research Council (UK) and the National Cancer Institute of Canada.
Attachment and Entry of Chlamydia Have Distinct Requirements for Host Protein Disulfide Isomerase
Chlamydia is an obligate intracellular pathogen that causes a wide range of diseases in humans. Attachment and entry are key processes in infectivity and subsequent pathogenesis of Chlamydia, yet the mechanisms governing these interactions are unknown. It was recently shown that a cell line, CHO6, that is resistant to attachment, and thus infectivity, of multiple Chlamydia species has a defect in protein disulfide isomerase (PDI) N-terminal signal sequence processing. Ectopic expression of PDI in CHO6 cells led to restoration of Chlamydia attachment and infectivity; however, the mechanism leading to this recovery was not ascertained. To advance our understanding of the role of PDI in Chlamydia infection, we used RNA interference to establish that cellular PDI is essential for bacterial attachment to cells, making PDI the only host protein identified as necessary for attachment of multiple species of Chlamydia. Genetic complementation and PDI-specific inhibitors were used to determine that cell surface PDI enzymatic activity is required for bacterial entry into cells, but enzymatic function was not required for bacterial attachment. We further determined that it is a PDI-mediated reduction at the cell surface that triggers bacterial uptake. While PDI is necessary for Chlamydia attachment to cells, the bacteria do not appear to utilize plasma membrane-associated PDI as a receptor, suggesting that Chlamydia binds a cell surface protein that requires structural association with PDI. Our findings demonstrate that PDI has two essential and independent roles in the process of chlamydial infectivity: it is structurally required for chlamydial attachment, and the thiol-mediated oxido-reductive function of PDI is necessary for entry.
Energy Consumption and Environmental Quality in Africa: Does Energy Efficiency Make Any Difference?
In line with the quest by policymakers to reduce greenhouse gas emissions towards Agenda 2050 and environmental sustainability, this study examines whether in the remit of Sustainable Development Goal 7, energy efficiency plays a significant role in mitigating environmental concerns associated with energy consumption. We do this by drawing macro-data on 20 sub−Saharan African countries for the period 2000–2020. Evidence based on the dynamic Generalize Method of Moments estimator shows that although overall, energy consumption triggers remarkable environmental setbacks, renewable energy consumption shows a favourable environmental effect. The results further show that energy efficiency is both directly and indirectly effective for reducing environmental pollution. Notably, the study finds that energy efficiency interacts with energy consumption to yield marked greenhouse gas emission reductions measured against carbon and nitrous emissions. In particular, we find that while renewable energy is significant for propelling Africa towards environmental sustainability, non-renewable energy shows a harmful effect. We provide policy recommendations based on the finding that investments in energy efficiency and renewable energy provide solutions to maintaining environmental sustainability. African countries should strive to include renewable energy in their energy mix and improve investments in line with SDG7 and Aspiration 1.7 of Africa’s Agenda 2063.
Direct visualization of the expression and localization of chlamydial effector proteins within infected host cells
Chlamydia secrete into host cells a diverse array of effector proteins, but progress in characterizing the spatiotemporal localization of these proteins has been hindered by a paucity of genetic approaches in Chlamydia and also by the challenge of studying these proteins within the live cellular environment. We adapted a split-green fluorescent protein (GFP) system for use in Chlamydia to label chlamydial effector proteins and track their localization in host cells under native environment. The efficacy of this system was demonstrated by detecting several known Chlamydia proteins including IncA, CT005 and CT694. We further used this approach to detect two chlamydial deubiquitinases (CT867 and CT868) within live cells during the infection. CT868 localized only to the inclusion membrane at early and late developmental stages. CT867 localized to the chlamydial inclusion membrane at an early developmental stage and was concomitantly localized to the host plasma membrane at a late stage during the infection. These data suggest that chlamydial deubiquitinase play important roles for chlamydial pathogenesis by targeting proteins at both the plasma membrane and the chlamydial inclusion membrane. The split-GFP technology was demonstrated to be a robust and efficient approach to identify the secretion and cellular localization of important chlamydial virulence factors.
Rituximab versus a watch-and-wait approach in patients with advanced-stage, asymptomatic, non-bulky follicular lymphoma: an open-label randomised phase 3 trial
Patients with advanced-stage, low-tumour-burden follicular lymphoma have conventionally undergone watchful waiting until disease progression. We assessed whether rituximab use could delay the need for chemotherapy or radiotherapy compared with watchful waiting and the effect of this strategy on quality of life (QoL). Asymptomatic patients (aged ≥18 years) with low-tumour-burden follicular lymphoma (grades 1, 2, and 3a) were randomly assigned centrally (1:1:1), by the minimisation approach stratified by institution, grade, stage, and age, to watchful waiting, rituximab 375 mg/m2 weekly for 4 weeks (rituximab induction), or rituximab induction followed by a maintenance schedule of 12 further infusions given at 2-monthly intervals for 2 years (maintenance rituximab). On Sept 30, 2007, recruitment into the rituximab induction group was closed and the study was amended to a two-arm study. The primary endpoints were time to start of new treatment and QoL at month 7 (ie, 6 months after completion of rituximab induction). All randomly assigned patients were included in the analysis of time to start of new treatment on an intention-to-treat basis. The main study is now completed and is in long-term follow-up. The study is registered with ClinicalTrials.gov, NCT00112931. Between Oct 15, 2004, and March 25, 2009, 379 patients from 118 centres in the UK, Australia, New Zealand, Turkey, and Poland were randomly assigned to watchful waiting or maintenance rituximab. 84 patients were recruited to the rituximab induction group before it was closed early. There was a significant difference in the time to start of new treatment, with 46% (95% CI 39–53) of patients in the watchful waiting group not needing treatment at 3 years compared with 88% (83–92) in the maintenance rituximab group (hazard ratio [HR] 0·21, 95% CI 0·14–0·31; p<0·0001). 78% (95% CI 69–87) of patients in the rituximab induction group did not need treatment at 3 years, which was significantly more than in the watchful waiting group (HR 0·35, 95% CI 0·22–0·56; p<0·0001), but no different compared with the maintenance rituximab group (0·75, 0·41–1·34; p=0·33). Compared with the watchful waiting group, patients in the maintenance rituximab group had significant improvements in the Mental Adjustment to Cancer scale score (p=0·0004), and Illness Coping Style score (p=0·0012) between baseline and month 7. Patients in the rituximab induction group did not show improvements in their QoL compared with the watchful waiting group. There were 18 serious adverse events reported in the rituximab groups (four in the rituximab induction group and 14 in the maintenance rituximab group), 12 of which were grade 3 or 4 (five infections, three allergic reactions, and four cases of neutropenia), all of which fully resolved. Rituximab monotherapy should be considered as a treatment option for patients with asymptomatic, advanced-stage, low-tumour-burden follicular lymphoma. Cancer Research UK, Lymphoma Research Trust, Lymphoma Association, and Roche.
Exit strategies of intracellular pathogens
Key Points How intracellular pathogens exit host cells is an important and overlooked topic in the study of host–pathogen interactions. This Review highlights the diverse strategies and specialized mechanisms that are used by intracellular pathogens to escape their resident vacuole and, subsequently, the host cell. Vacuole exit is typically accomplished by the action of pathogen-secreted pore-forming proteins, or phospholipases, on vacuole membranes to cause their disruption. Strategies for pathogen exit from cells include: triggering host-cell lysis from within the cell; using actin-based motility to protrude out of the host cell; budding out of the cell; vacuole extrusion out of the cell; vacuole exocytosis; induction of inflammatory pyroptosis in the host cell; and induction of host-cell apoptosis. The exit of intracellular bacteria from host cells is a crucial stage in microbial pathogenesis that is driven by an evolutionary requirement for efficient dissemination to neighbouring cells and transmission to new hosts. In this comprehensive Review, the authors discuss the diverse repertoire of strategies that is used by intracellular pathogens to escape their host cells. The exit of intracellular pathogens from host cells is an important step in the infectious cycle, but is poorly understood. It has recently emerged that microbial exit is a process that can be directed by organisms from within the cell, and is not simply a consequence of the physical or metabolic burden that is imposed on the host cell. This Review summarizes our current knowledge on the diverse mechanisms that are used by intracellular pathogens to exit cells. An integrated understanding of the diversity that exists for microbial exit pathways represents a new horizon in the study of host–pathogen interactions.