Culture of human pluripotent stem cells using completely defined conditions on a recombinant E-cadherin substratum

<p>Abstract</p> <p>Background</p> <p>To maintain pluripotency of human embryonic stem (huES) cells in feeder-free culture it has been necessary to provide a Matrigel substratum, which is a complex of poorly defined extracellular matrices and growth factors derived from mouse Engelbreth-Holm-Swarm sarcoma cells. Culture of stem cells under ill-defined conditions can inhibit the effectiveness of maintaining cells in a pluripotent state and reduce reproducibility of differentiation protocols. Moreover recent batches of Matrigel have been found to be contaminated with the single stranded RNA virus, Lactate Dehydrogenase Elevating Virus (LDEV), raising concerns regarding the safety of using stem cells that have been cultured on Matrigel in a therapeutic setting. To circumvent such concerns, we attempted to identify a recombinant matrix that could be used as an alternative to Matrigel for the culture of human pluripotent stem cells. huES and human induced pluripotent stem (hiPS) cells were grown on plates coated with a fusion protein consisting of E-cadherin and the IgG Fc domain using mTeSR1 medium.</p> <p>Results</p> <p>Cells grown under these conditions maintained similar morphology and growth rate to those grown on Matrigel and retained all pluripotent stem cell features, including an ability to differentiate into multiple cell lineages in teratoma assays. We, therefore, present a culture system that maintains the pluripotency of huES and hiPS cells under completely defined conditions.</p> <p>Conclusions</p> <p>We propose that this system should facilitate growth of stem cells using good manufacturing practices (GMP), which will be necessary for the clinical use of pluripotent stem cells and their derivatives.</p

Exploring the ‘middle ground’ between state and market: the example of China

Studies of housing systems lying in the ‘middle ground’ between state and market are subject to three important shortcomings. First, the widely used Esping-Andersen (EA) approach assesses only a subset of the key housing outcomes and may be less helpful for describing changes in housing policy regimes. Second, there is too much emphasis on tenure transitions, and an assumed close correspondence between tenure labels and effective system functioning may not be valid. Third, due attention has not been given to the spatial dimensions in which housing systems operate, in particular when housing policies have a significant devolved or localised emphasis. Updating EA’s framework, we suggest a preliminary list of housing system indicators in order to capture the nature of the housing systems being developed and devolved. We verified the applicability of this indicator system with the case of China. This illustrates clearly the need for a more nuanced and systematic basis for categorising differences and changes in welfare and housing policies

Scalable Control Variates for Monte Carlo Methods via Stochastic Optimization

Control variates are a well-established tool to reduce the variance of Monte Carlo estimators. However, for large-scale problems including high-dimensional and large-sample settings, their advantages can be outweighed by a substantial computational cost. This paper considers control variates based on Stein operators, presenting a framework that encompasses and generalizes existing approaches that use polynomials, kernels and neural networks. A learning strategy based on minimising a variational objective through stochastic optimization is proposed, leading to scalable and effective control variates. Novel theoretical results are presented to provide insight into the variance reduction that can be achieved, and an empirical assessment, including applications to Bayesian inference, is provided in support

Association between physical education classes and physical activity among 187,386 adolescents aged 13-17 years from 50 low- and middle-income countries

OBJECTIVE: This study aimed to examine the association between physical education classes and PA among adolescents from 50 low- and middle-income countries (LMICs). METHODS: A self-reported questionnaire from the Global School-based Student Survey (GSHS) was used to collect information on participation frequency of physical education classes and being physically active over the last week, as well as other control variables (e.g., sex, age, country, sedentary behavior). Multivariable logistic regression and a pooled meta-analysis were performed to explore the association and compared country-wise differences. RESULTS: Included adolescents aged from 13 to 17 years (n = 187,386, %boys = 51.7; mean age = 14.6 years), the prevalence of sufficient PA (meeting the PA guidelines) was 14.9%. The prevalence of 5 days or more to engage in physical education classes was 16.5%. Compared with adolescents who had 0 days for physical education classes, higher participation frequency was more likely related to sufficient PA (OR: 1 day = 1.34, 2 days = 1.66, 3 days = 1.67, 4 days = 1.79, 5 days or more = 2.46), these findings were also observed in both sexes. A moderate inconsistency on the association across the included countries was found (I(2) = 53%, p < 0.01), although the pooled OR was 1.50 (95% CI: 1.36–1.65). CONCLUSIONS: Participating in more physical education classes may be an effective approach to increase physical activity levels among adolescents in LMICs. However, promoting physical activity levels among adolescents in LMICs through physical education classes should consider more country-specific factors

Generation of human induced pluripotent stem cells by simple transient transfection of plasmid DNA encoding reprogramming factors

<p>Abstract</p> <p>Background</p> <p>The use of lentiviruses to reprogram human somatic cells into induced pluripotent stem (iPS) cells could limit their therapeutic usefulness due to the integration of viral DNA sequences into the genome of the recipient cell. Recent work has demonstrated that human iPS cells can be generated using episomal plasmids, excisable transposons, adeno or sendai viruses, mRNA, or recombinant proteins. While these approaches offer an advance, the protocols have some drawbacks. Commonly the procedures require either subcloning to identify human iPS cells that are free of exogenous DNA, a knowledge of virology and safe handling procedures, or a detailed understanding of protein biochemistry.</p> <p>Results</p> <p>Here we report a simple approach that facilitates the reprogramming of human somatic cells using standard techniques to transfect expression plasmids that encode OCT4, NANOG, SOX2, and LIN28 without the need for episomal stability or selection. The resulting human iPS cells are free of DNA integration, express pluripotent markers, and form teratomas in immunodeficient animals. These iPS cells were also able to undergo directed differentiation into hepatocyte-like and cardiac myocyte-like cells in culture.</p> <p>Conclusions</p> <p>Simple transient transfection of plasmid DNA encoding reprogramming factors is sufficient to generate human iPS cells from primary fibroblasts that are free of exogenous DNA integrations. This approach is highly accessible and could expand the use of iPS cells in the study of human disease and development.</p

Sleep as a Priority:24-Hour Movement Guidelines and Mental Health of Chinese College Students during the COVID-19 Pandemic

Research on the combined role of 24-hour movement behaviors (sleep, sedentary behavior [SB], and physical activity) in adult mental health, though important, is in its infancy. In the context of Canadian 24-hour movement guidelines integrating quantitative recommendations for sleep, SB, and moderate-to-vigorous physical activity (MVPA), this study aimed to examine the associations between meeting guidelines and mental health among college students. The study used a cross-sectional sample of 1846 Chinese college students surveyed online in August 2020. Through network analysis and multivariate analysis of covariance, the individual and combined associations between meeting 24-hour movement guidelines and the levels of depression and anxiety after adjusting sociodemographic factors were analyzed. Results indicated that meeting the sleep guideline had stronger associations with depression and anxiety than meeting the SB or MVPA guideline. Specifically, compared to meeting no guidelines, meeting the sleep guideline (alone or in combination with other guidelines) was associated with significantly lower levels of depression and anxiety; meeting both SB and MVPA guidelines was also associated with a significantly lower level of depression. Hence, meeting more guidelines, especially adhering to a healthy sleep routine, may play an important role in promoting the mental health of young adults

Quantum Criticality and Novel Phases: Summary and Outlook

This conference summary and outlook provides a personal overview of the topics and themes of the August 2009 Dresden meeting on quantum criticality and novel phases. The dichotomy between the local moment and the itinerant views of magnetism is revisited and refreshed in new materials, new probes and new theoretical ideas. New universality and apparent zero temperature phases of matter move us beyond the old ideas of quantum criticality. This is accompanied by alternative pairing interactions and as yet unidentified phases developing in the vicinity of quantum critical points. In discussing novel order, the magnetic analogues of superconductivity are considered as candidate states for the hidden order that sometimes develops in the vicinity of quantum critical points in metallic systems. These analogues can be thought of as "pairing" in the particle-hole channel and are tabulated. This analogy is used to outline a framework to study the relation between ferromagnetic fluctuations and the propensity of a metal to nematic type phases which at weak coupling correspond to Pomeranchuk instabilities. This question can be related to the fundamental relations of Fermi liquid theory.Comment: Conference summary for the 2009 Dresden Meeting on Quantum Criticality and Novel Phases. 7 pages and 4 figures. The associated presentation may be found at http://www.theory.bham.ac.uk/staff/schofield/talks/Dresden

Effector-triggered defence against apoplastic fungal pathogens

Copyright 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license CC BY 3.0 (http://creativecommons.org/licenses/by/3.0/). hR gene-mediated host resistance against apoplastic fungal pathogens is not adequately explained by the terms pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) or effector-triggered immunity (ETI). Therefore, it is proposed that this type of resistance is termed ‘effector-triggered defence’ (ETD). Unlike PTI and ETI, ETD is mediated by R genes encoding cell surface-localised receptor-like proteins (RLPs) that engage the receptor-like kinase SOBIR1. In contrast to this extracellular recognition, ETI is initiated by intracellular detection of pathogen effectors. ETI is usually associated with fast, hypersensitive host cell death, whereas ETD often triggers host cell death only after an elapsed period of endophytic pathogen growth. In this opinion, we focus on ETD responses against foliar fungal pathogens of cropsPeer reviewe

Nebuliser therapy in the intensive care unit

The relationship between identity, lived experience, sexual practices and the language through which these are conveyed has been widely debated in sexuality literature. For example, ‘coming out’ has famously been conceptualised as a ‘speech act’ (Sedgwick 1990) and as a collective narrative (Plummer 1995), while a growing concern for individuals’ diverse identifications in relations to their sexual and gender practices has produced interesting research focusing on linguistic practices among LGBT-identified individuals (Leap 1995; Kulick 2000; Cameron and Kulick 2006; Farqhar 2000). While an explicit focus on language remains marginal to literature on sexualities (Kulick 2000), issue of language use and translation are seldom explicitly addressed in the growing literature on intersectionality. Yet intersectional perspectives ‘reject the separability of analytical and identity categories’ (McCall 2005:1771), and therefore have an implicit stake in the ‘vernacular’ language of the researched, in the ‘scientific’ language of the researcher and in the relationship of continuity between the two. Drawing on literature within gay and lesbian/queer studies and cross-cultural studies, this chapter revisits debates on sexuality, language and intersectionality. I argue for the importance of giving careful consideration to the language we choose to use as researchers to collectively define the people whose experiences we try to capture. I also propose that language itself can be investigated as a productive way to foreground how individual and collective identifications are discursively constructed, and to unpack the diversity of lived experience. I address intersectional complexity as a methodological issue, where methodology is understood not only as the methods and practicalities of doing research, but more broadly as ‘a coherent set of ideas about the philosophy, methods and data that underlie the research process and the production of knowledge’ (McCall 2005:1774). My points are illustrated with examples drawn from my ethnographic study on ‘lesbian’ identity in urban Russia, interspersed with insights from existing literature. In particular, I aim to show that an explicit focus on language can be a productive way to explore the intersections between the global, the national and the local in cross-cultural research on sexuality, while also addressing issues of positionality and accountability to the communities researched