168 research outputs found
Contributions to Foundation Engineering in Geotechnique
Many of the important developments in the field of foundation engineering have been addressed in Géotechnique papers over the past 60 years. This paper briefly reviews some of these developments and related articles, particularly with respect to shallow and deep foundations. In the early days of Géotechnique, the power to perform sophisticated numerical analyses did not exist. Papers tended to focus on the solution of problems using simple models in which soil was modelled either as linear elastic or as perfectly plastic. Engineers sought simple closed-form analytical solutions for boundary-value problems. With the development of more powerful analytical, computational and experimental capabilities, and of more sophisticated pile installation technology (especially offshore), more recent papers have explored much more sophisticated approaches to a range of foundation problems, striving to achieve more realistic representation of working conditions. Géotechnique papers have attempted to solve the problems faced by the foundation engineering industry, with a strong emphasis on the underlying science; as a result, these papers have played a key role in the advancement of both the science and its applications in our discipline
MDM2 Integrates Cellular Respiration and Apoptotic Signaling through NDUFS1 and the Mitochondrial Network
Signaling diversity and subsequent complexity in higher eukaryotes is partially explained by one gene encoding a polypeptide with multiple biochemical functions in different cellular contexts. For example, mouse double minute 2 (MDM2) is functionally characterized as both an oncogene and a tumor suppressor, yet this dual classification confounds the cell biology and clinical literatures. Identified via complementary biochemical, organellar, and cellular approaches, we report that MDM2 negatively regulates NADH:ubiquinone oxidoreductase 75 kDa Fe-S protein 1 (NDUFS1), leading to decreased mitochondrial respiration, marked oxidative stress, and commitment to the mitochondrial pathway of apoptosis. MDM2 directly binds and sequesters NDUFS1, preventing its mitochondrial localization and ultimately causing complex I and supercomplex destabilization and inefficiency of oxidative phosphorylation. The MDM2 amino-terminal region is sufficient to bind NDUFS1, alter supercomplex assembly, and induce apoptosis. Finally, this pathway is independent of p53, and several mitochondrial phenotypes are observed in Drosophila and murine models expressing transgenic Mdm2
Adaptation and qualitative evaluation of the BETTER intervention for chronic disease prevention and screening by public health nurses in low income neighbourhoods : views of community residents
The adaptation phase is one component of a study funded as a grant proposal entitled 'Advancing Cancer Prevention Among Deprived Neighbourhoods' by the Canadian Cancer Society Research Institute grant #704042 and by the Canadian Institutes of Health Research Institute of Cancer grant OCP #145450. Aisha Lofters is supported by a CIHR New Investigator Award, as a Clinician Scientist by the Department of Family and Community Medicine, University of Toronto, and as Chair in Implementation Science at the Peter Gilgan Centre for Women’s Cancers at Women’s College Hospital in partnership with the Canadian Cancer Society. Dr. Andrew Pinto holds a Canadian Institutes of Health Research Applied Public Health Chair and is supported as a Clinician-Scientist in the Department of Family and Community Medicine, Temerty Faculty of Medicine, University of Toronto, and supported by the Department of Family and Community Medicine, St. Michael’s Hospital, and the Li Ka Shing Knowledge Institute, St. Michael’s Hospital. He is also the Associate Director for Clinical Research at the University of Toronto Practice-Based Research Network. Lawrence Paszat is supported by a Clinician Scientist award funded by the Ontario Ministry of Health and Long Term Care.Background The BETTER intervention is an effective comprehensive evidence-based program for chronic disease prevention and screening (CDPS) delivered by trained prevention practitioners (PPs), a new role in primary care. An adapted program, BETTER HEALTH, delivered by public health nurses as PPs for community residents in low income neighbourhoods, was recently shown to be effective in improving CDPS actions. To obtain a nuanced understanding about the CDPS needs of community residents and how the BETTER HEALTH intervention was perceived by residents, we studied how the intervention was adapted to a public health setting then conducted a post-visit qualitative evaluation by community residents through focus groups and interviews. Methods We first used the ADAPT-ITT model to adapt BETTER for a public health setting in Ontario, Canada. For the post-PP visit qualitative evaluation, we asked community residents who had received a PP visit, about steps they had taken to improve their physical and mental health and the BETTER HEALTH intervention. For both phases, we conducted focus groups and interviews; transcripts were analyzed using the constant comparative method. Results Thirty-eight community residents participated in either adaptation (n = 14, 64% female; average age 54 y) or evaluation (n = 24, 83% female; average age 60 y) phases. In both adaptation and evaluation, residents described significant challenges including poverty, social isolation, and daily stress, making chronic disease prevention a lower priority. Adaptation results indicated that residents valued learning about CDPS and would attend a confidential visit with a public health nurse who was viewed as trustworthy. Despite challenges, many recipients of BETTER HEALTH perceived they had achieved at least one personal CDPS goal post PP visit. Residents described key relational aspects of the visit including feeling valued, listened to and being understood by the PP. The PPs also provided practical suggestions to overcome barriers to meeting prevention goals. Conclusions Residents living in low income neighbourhoods faced daily stress that reduced their capacity to make preventive lifestyle changes. Key adapted features of BETTER HEALTH such as public health nurses as PPs were highly supported by residents. The intervention was perceived valuable for the community by providing access to disease prevention. Trial registration #NCT03052959, 10/02/2017.Peer reviewe
Effects of Antiplatelet Therapy After Stroke Caused by Intracerebral Hemorrhage:Extended Follow-up of the RESTART Randomized Clinical Trial
Importance: The Restart or Stop Antithrombotics Randomized Trial (RESTART) found that antiplatelet therapy appeared to be safe up to 5 years after intracerebral hemorrhage (ICH) that had occurred during antithrombotic (antiplatelet or anticoagulant) therapy.
Objectives: To monitor adherence, increase duration of follow-up, and improve precision of estimates of the effects of antiplatelet therapy on recurrent ICH and major vascular events.
Design, setting and participants: From May 22, 2013, through May 31, 2018, this prospective, open, blinded end point, parallel-group randomized clinical trial studied 537 participants at 122 hospitals in the UK. Participants were individuals 18 years or older who had taken antithrombotic therapy for the prevention of occlusive vascular disease when they developed ICH, discontinued antithrombotic therapy, and survived for 24 hours. After initial follow-up ended on November 30, 2018, annual follow-up was extended until November 30, 2020, for a median of 3.0 years (interquartile range [IQR], 2.0-5.0 years) for the trial cohort.
Interventions: Computerized randomization that incorporated minimization allocated participants (1:1) to start or avoid antiplatelet therapy.
Main outcomes and measures: Participants were followed up for the primary outcome (recurrent symptomatic ICH) and secondary outcomes (all major vascular events) for up to 7 years. Data from all randomized participants were analyzed using Cox proportional hazards regression, adjusted for minimization covariates.
Results: A total of 537 patients (median age, 76.0 years; IQR, 69.0-82.0 years; 360 [67.0%] male; median time after ICH onset, 76.0 days; IQR, 29.0-146.0 days) were randomly allocated to start (n = 268) or avoid (n = 269 [1 withdrew]) antiplatelet therapy. The primary outcome of recurrent ICH affected 22 of 268 participants (8.2%) allocated to antiplatelet therapy compared with 25 of 268 participants (9.3%) allocated to avoid antiplatelet therapy (adjusted hazard ratio, 0.87; 95% CI, 0.49-1.55; P = .64). A major vascular event affected 72 participants (26.8%) allocated to antiplatelet therapy compared with 87 participants (32.5%) allocated to avoid antiplatelet therapy (hazard ratio, 0.79; 95% CI, 0.58-1.08; P = .14).
Conclusions and relevance: Among patients with ICH who had previously taken antithrombotic therapy, this study found no statistically significant effect of antiplatelet therapy on recurrent ICH or all major vascular events. These findings provide physicians with some reassurance about the use of antiplatelet therapy after ICH if indicated for secondary prevention of major vascular events.
Trial registration: isrctn.org Identifier: ISRCTN71907627
The REstart or STop Antithrombotics Randomised Trial (RESTART) after stroke due to intracerebral haemorrhage:statistical analysis plan for a randomised controlled trial
Background
For adults surviving stroke due to spontaneous (non-traumatic) intracerebral haemorrhage (ICH) who had taken an antithrombotic (i.e. anticoagulant or antiplatelet) drug for the prevention of vaso-occlusive disease before the ICH, it is unclear whether starting antiplatelet therapy modifies the risks of recurrent ICH, major haemorrhagic events, major occlusive vascular events, or a composite of all major vascular events compared to avoiding antiplatelet therapy.
Methods/design
The REstart or STop Antithrombotics Randomised Trial (RESTART) is an investigator-led, parallel group, open, assessor-blind, randomised trial comparing starting versus avoiding antiplatelet therapy for adults surviving antithrombotic-associated ICH. Recruitment began on 22 May 2013 and ended on 31 May 2018. Follow-up ended on 30 November 2018. This update to the protocol describes the statistical analysis plan (version 1.7, finalised on 25 January 2019). Database lock and un-blinding occurred on 29 January 2019, after which the un-masked trial statistician conducted the final analyses according to this statistical analysis plan.
Discussion
Final results of RESTART will be analysed and disseminated in May 2019.
Trial registration
ISRCTN registry 71907627. Prospectively registered on 25 April 2013
Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke
Genetic factors have been implicated in stroke risk but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) in ischemic stroke and its subtypes in 3,548 cases and 5,972 controls, all of European ancestry. Replication of potential
signals was performed in 5,859 cases and 6,281 controls. We replicated reported associations between variants close to PITX2 and ZFHX3 with cardioembolic stroke, and a 9p21 locus with large vessel stroke. We identified a novel association for a SNP within the histone deacetylase 9(HDAC9) gene on chromosome 7p21.1 which was associated with large vessel stroke including additional replication in a further 735 cases and 28583 controls (rs11984041, combined P =
1.87×10−11, OR=1.42 (95% CI) 1.28-1.57). All four loci exhibit evidence for heterogeneity of effect across the stroke subtypes, with some, and possibly all, affecting risk for only one subtype. This suggests differing genetic architectures for different stroke subtypes
The REstart or STop Antithrombotics Randomised Trial (RESTART) after stroke due to intracerebral haemorrhage: study protocol for a randomised controlled trial
Background
For adults surviving stroke due to spontaneous (non-traumatic) intracerebral haemorrhage (ICH) who had taken an antithrombotic (i.e. anticoagulant or antiplatelet) drug for the prevention of vaso-occlusive disease before the ICH, it is unclear whether starting antiplatelet drugs results in an increase in the risk of recurrent ICH or a beneficial net reduction of all serious vascular events compared to avoiding antiplatelet drugs.
Methods/design
The REstart or STop Antithrombotics Randomised Trial (RESTART) is an investigator-led, randomised, open, assessor-blind, parallel-group, randomised trial comparing starting versus avoiding antiplatelet drugs for adults surviving antithrombotic-associated ICH at 122 hospital sites in the United Kingdom. RESTART uses a central, web-based randomisation system using a minimisation algorithm, with 1:1 treatment allocation to which central research staff are masked. Central follow-up includes annual postal or telephone questionnaires to participants and their general (family) practitioners, with local provision of information about adverse events and outcome events. The primary outcome is recurrent symptomatic ICH. The secondary outcomes are: symptomatic haemorrhagic events; symptomatic vaso-occlusive events; symptomatic stroke of uncertain type; other fatal events; modified Rankin Scale score; adherence to antiplatelet drug(s). The magnetic resonance imaging (MRI) sub-study involves the conduct of brain MRI according to a standardised imaging protocol before randomisation to investigate heterogeneity of treatment effect according to the presence of brain microbleeds. Recruitment began on 22 May 2013. The target sample size is at least 720 participants in the main trial (at least 550 in the MRI sub-study).
Discussion
Final results of RESTART will be analysed and disseminated in 2019.
Trial registration
ISRCTN71907627 (www.isrctn.com/ISRCTN71907627). Prospectively registered on 25 April 2013
Rare missense functional variants at COL4A1 and COL4A2 in sporadic intracerebral Hhmorrhage
Objective:
To test the genetic contribution of rare missense variants in COL4A1 and COL4A2 in which common variants are genetically associated with sporadic intracerebral hemorrhage (ICH), we performed rare variant analysis in multiple sequencing data for the risk for sporadic ICH.
Methods:
We performed sequencing across 559Kbp at 13q34 including COL4A1 and COL4A2 among 2,133 individuals (1,055 ICH cases; 1,078 controls) in US-based and 1,492 individuals (192 ICH cases; 1,189 controls) from Scotland-based cohorts, followed by sequence annotation, functional impact prediction, genetic association testing, and in silico thermodynamic modeling.
Results:
We identified 107 rare nonsynonymous variants in sporadic ICH, of which two missense variants, rs138269346 (COL4A1I110T) and rs201716258 (COL4A2H203L), were predicted to be highly functional and occurred in multiple ICH cases but not in controls from the US-based cohort. The minor allele of rs201716258 was also present in Scottish ICH patients, and rs138269346 was observed in two ICH-free controls with a history of hypertension and myocardial infarction. Rs138269346 was nominally associated with non-lobar ICH risk (P=0.05), but not with lobar ICH (P=0.08), while associations between rs201716258 and ICH subtypes were non-significant (P>0.12). Both variants were considered pathogenic based on minor allele frequency (<0.00035 in EUR), predicted functional impact (deleterious or probably damaging), and in silico modeling studies (substantially altered physical length and thermal stability of collagen).
Conclusions:
We identified rare missense variants in COL4A1/A2 in association with sporadic ICH. Our annotation and simulation studies suggest that these variants are highly functional and may represent targets for translational follow-up
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