Stochasticity and order: studies of keratinocyte proliferation

A central tenet of stem cell biology has been that proliferating tissues are maintained through a cellular hierarchy comprising of self-renewing stem cells at the apex, multiple lineage-restricted short-lived progenitor cells, and post-mitotic differentiated cells. The wide range of colony sizes in cultured human keratinocytes has been taken to support this hypothesis. Contrary to this model, researchers using genetic lineage tracing in mouse epidermis have inferred a single progenitor population for homeostasis, and a quiescent stem cell population activated upon wounding or genetic mutation. To study the proliferative behaviour of human keratinocytes, I used live imaging in vitro at single cell resolution. This shows two modes of proliferation: Type 1 cell division is stochastic with equal odds of generating dividing or non-dividing progeny, while Type 2 cell division predominantly produces two dividing daughters. These two modes are sufficient to explain the entire range of colony sizes seen after 7-12 days of culture and does not require a spectrum of proliferative ability. This insight provides a simple way to study the effects of external factors on cell fate. To exemplify this, I observed the effects of epidermal growth factor (EGF) and the Wnt agonist R-spondin on proliferation. Here I find proliferation in type 2 colonies changes by changing the proportion of cells dividing. This has implications for the limited success of EGF therapies in clinical trials following burns. To examine clonal contributions to wound repair, I used the mouse oesophageal epithelium which is exclusively composed of, and maintained by, a single progenitor population. I developed a micro-endoscopic wounding technique that produced localised superficial wounds. Here, I found that these wounds healed by uniform contribution from surrounding keratinocytes, demonstrating that reserve stem cells are not obligatory for wound repair. In summary, my work shows that human keratinocytes in vitro have two, and only two, modes of proliferation: a stochastic mode that is insensitive to external EGF signalling, and a EGF-sensitive exponential mode. Additionally, proliferation during wound repair can occur with stochastically dividing progenitors, and does not obligate stem cell recruitment in vivo

What Social Supports Are Available to Self-Employed People When Ill or Injured? A Comparative Policy Analysis of Canada and Australia

Self-employment (SE) is a growing precarious work arrangement internationally. In the current digital age, SE appears in configurations and contours that differ from the labor market of 50 years ago and is part of a 'paradigm shift' from manufacturing/managerial capitalism to entrepreneurial capitalism. Our purpose in this paper is to reflect on how a growing working population of self-employed people accesses social support systems when they are not working due to injury and sickness in the two comparable countries of Canada and Australia. We adopted 'interpretive policy analysis' as a methodological framework and searched a wide range of documents related to work disability policy and practice, including official data, legal and policy texts from both countries, and five prominent academic databases. Three major themes emerged from the policy review and analysis: (i) defining self-employment: contested views; (ii) the relationship between misclassification of SE and social security systems; (iii) existing social security systems for workers and self-employed workers: Ontario and NSW. Our comparative discussion leads us toward conclusions about what might need to be done to better protect self-employed workers in terms of reforming the existing social security systems for the countries. Because of similarities and differences in support available for SE'd workers in the two countries, our study provides insights into what might be required to move the different countries toward sustainable labour markets for their respective self-employed populations

Self-employment, work and health: A critical narrative review

BACKGROUND: Self-employment (SE) is a growing precarious and non-standard work arrangement internationally. Economically advanced countries that favor digital labor markets may be promoting the growth of a demographic of self-employed (SE’d) workers who are exposed to particular occupational diseases, sickness, and injury. However, little is known about how SE’d workers are supported when they are unable to work due to illness, injury, and disability. OBJECTIVE: Our objective was to critically review peer-reviewed literature focusing on advanced economies to understand how SE’d workers navigate, experience, or manage their injuries and illness when unable to work. METHODS: Using a critical interpretive lens, a systematic search was conducted of five databases. The search yielded 18 relevant articles, which were critically examined and synthesized. RESULTS: Five major themes emerged from the review: (i) conceptualizing SE; (ii) double-edged sword; (iii) dynamics of illness, injury, and disability; (iv) formal and informal health management support systems; and (v) occupational health services and rehabilitation. CONCLUSION: We find a lack of research distinguishing the work and health needs of different kinds of SE’d workers, taking into consideration class, gender, sector, and gig workers. Many articles noted poor social security system supports. Drawing on a social justice lens, we argue that SE’d workers make significant contributions to economies and are deserving of support from social security systems when ill or injured.The authors acknowledge the support from the SSHRC/CIHR Healthy Productive Workforce Partnership Grant, Grant number: 895-2018-4009

Le retour au travail dans un contexte de barrières linguistiques : Une étude comparative des politiques et des pratiques d’indemnisation des victimes de lésion professionnelle au Québec et en Ontario

La façon dont les régimes d’indemnisation des victimes de lésion professionnelle doivent tenir compte des barrières linguistiques est d’une importance capitale à la lumière de la diversification linguistique croissante du Canada. S’appuyant sur des entrevues menées auprès de travailleurs accidentés et d’informateurs clés, cette étude est la première à examiner, de manière empirique, les politiques et les pratiques du retour au travail sous l’angle des barrières linguistiques. En comparant les juridictions du Québec et de l’Ontario, l’étude met en lumière des similitudes et des différences touchant les accommodements linguistiques ainsi que les politiques et les pratiques du retour au travail qui déterminent les expériences des travailleurs accidentés ayant des besoins linguistiques. Elle fait valoir que les lacunes à cet égard, qui sont plus marquées au Québec, contribuent à un faible retour au travail pour ces travailleurs dans les deux provinces.The question of how workers’ compensation systems should account for language barriers is of increasing importance given Canada’s growing linguistic diversity. This study is the first to empirically examine, based on interviews with injured workers and key informants, return-to-work policies and practices through the lens of language barriers. By comparing two jurisdictions, Quebec and Ontario, the study highlights similarities and differences in language accommodation and return-to-work policies and practices that shape the experiences of injured workers with language needs. It argues that gaps in this regard, which are more pronounced in Quebec, contribute to poor return-to-work outcomes for these workers in both provinces

Return-to-Work in a Language Barrier Context : Comparing Quebec’s and Ontario’s Workers’ Compensation Policies and Practices

The question of how workers’ compensation systems should account for language barriers is of increasing importance given Canada’s growing linguistic diversity. This study is the first to empirically examine, based on interviews with injured workers and key informants, return-to-work policies and practices through the lens of language barriers. By comparing two jurisdictions, Quebec and Ontario, the study highlights similarities and differences in language accommodation and return-to-work policies and practices that shape the experiences of injured workers with language needs. It argues that gaps in this regard, which are more pronounced in Quebec, contribute to poor return-to-work outcomes for these workers in both provinces.La façon dont les régimes d’indemnisation des victimes de lésion professionnelle doivent tenir compte des barrières linguistiques est d’une importance capitale à la lumière de la diversification linguistique croissante du Canada. S’appuyant sur des entrevues menées auprès de travailleurs accidentés et d’informateurs clés, cette étude est la première à examiner, de manière empirique, les politiques et les pratiques du retour au travail sous l’angle des barrières linguistiques. En comparant les juridictions du Québec et de l’Ontario, l’étude met en lumière des similitudes et des différences touchant les accommodements linguistiques ainsi que les politiques et les pratiques du retour au travail qui déterminent les expériences des travailleurs accidentés ayant des besoins linguistiques. Elle fait valoir que les lacunes à cet égard, qui sont plus marquées au Québec, contribuent à un faible retour au travail pour ces travailleurs dans les deux provinces

The Work Disability Prevention CIHR Strategic Training Program: Program Performance After 5 Years of Implementation

Introduction The Work Disability Prevention (WDP) Canadian Institutes of Health Research (CIHR) Strategic Training Program was developed in 2001 and is a unique program in the world. The main objective of this program is to help future researchers develop transdisciplinary knowledge, skills and attitudes regarding WDP. The purpose of this paper is to present a descriptive portrait of the program's performance over the past 5 years, as well as the trainees' and alumni's perspectives on the WDP CIHR Training Program. Methods Data on the program's performance were collected from documents in the program records. The trainees' opinions on the WDP training program were obtained through focus groups and telephone interviews. The data collected were compiled and divided into themes to summarize the qualitative findings pertaining to each question. Results From 2003 to 2007, five successive summer sessions have been offered, involving 44 high-caliber applicants from nine countries, 34 mentors and collaborators, 29 guest speakers and 15 stakeholders. Overall, trainees appreciated the networking, the opportunity to interact with people from different disciplines and countries, the openness, and the international perspective and uniqueness of the program. The least appreciated aspects concerned mainly the e-learning course, evaluations and information on optional courses. The coordination and logistics were judged appropriate and several topics were suggested to improve the program quality. Conclusion In general, the program implementation went well, with good participation from mentors, speakers and stakeholders; the program was appreciated by the trainees and alumni. This paper underscores the importance of the international perspective, the transdisciplinarity and the scientific networking established through the progra