Reduction in mesenchymal stem cell numbers in premature aging DNA repair deficient TTD mice

Background: Mice carrying mutations in DNA repair genes often show signs of accelerated ageing and therefore can be used as a model system to study age related diseases like osteoporosis. It has been shown that TTD mice, carrying a mutation in the nucleotide excision repair gene XPD (xeroderma pigmentosa group D), display features of ageing related osteoporosis as well as adipose tissue hypoplasia. Since both cell types involved, osteoblasts as well as adipocytes, arise from the same mesenchymal stem cell population, the aim of the current project was to study the number, proliferation and differentiation potential of these cells in TTD compared to wild type (WT) mice. This might provide us with useful information concerning the mechanism behind age-related osteoporosis and the loss of adipose tissue.Methods: Bone marrow from old TTD and WT mice was cultured under osteogenic or adipogenic conditions and analysed for alkaline phosphatase activity (ALP), mineralisation (osteoblast) and lipid deposition (adipocyte).Results: Under osteogenic conditions the number of ALP-positive colonies after 9 and 14 days of culture was significantly decreased (p=0.02) in TTD compared to WT mice. The rate at which new ALP-positive colonies are formed between day 9 and day 14 of culture has not changed between TTD and WT mice, indicating that the decrease in colony number is not due to a delay in differentiation. Mineralisation of ALP-positive colonies did not seem to be affected, with a borderline significant decrease on day 14 at the onset of mineralisation but no significant changes on day 21 of culture. Lipid deposition was strongly reduced in TTD compared to WT mice (p=0.01) after 35 days of culture.Conclusions: The observed reduction in osteoblast and adipocyte differentiation indicates a reduction of mesenchymal stem cell numbers in TTD mice. This reduction in mesenchymal stem cell numbers and the corresponding decline in osteoblast differentiation could explain the premature osteoporotic features observed in TTD mice. In line with this, the reduction of mesenchymal stem cells and adipocyte differentiation may underlie the adipose tissue hypoplasia observed in TTD mice

Deletion of the ghrelin receptor GHSR corrects the trabecular, but not the cortical bone changes in the femoral head of ob/ob mice

Background: There exists an intriguing and complex relationship between fat and bone cells with respect to aging and osteoporosis, which is mediated in part by leptin. Genetically obese mice (ob/ob), that lack leptin, have aheterogeneous bone phenotype, with differential effects on cortical and trabecular compartments. Besides its role in bone metabolism, leptin is most well known for its anorexigenic properties. Opposed in action to leptin is ghrelin, a potent orexigenic peptide hormone derived from the stomach. Ghrelin and leptin also act as each other’s antagonists in gonadal and immune system function.Objective: To determine if ghrelin opposes leptin action on bone metabolism.Methods: Characterization of femoral micro-architecture in 6 months old male wild type, ob/ob, ghrelin receptor knockout (Ghsr -/-), and ob/ob.Ghsr-/- mice using micro-computed tomography.Results: Deletion of Ghsr alone did not significantly alter bone micro-architecture in wild type mice. Deletion of leptin reduced cortical volume and thickness in the femoral head of wild type mice, while it increased endocortical volume. Tissue volume remained unaffected. Conversely, deletion of leptin increased trabecular bone volume, trabecular number and connectivity in wild type mice. Additional deletion of Ghsr in ob/ob mice restored the changes to wild type levels in trabecular bone, but not in cortical bone (all not significant).Conclusion: We found that leptin deficiency has a negative effect on cortical and a positive effect on trabecular bone micro-architecture, confirming the heterogeneous skeletal effects observed by others in ob/ob mice. Knocking out ghrelin signaling compensates for the effect of leptin deficiency on trabecular bone. These observations demonstrate the positive activity of ghrelin signaling in bone, and suggest that ghrelin and leptin have opposing actions on bone metabolism

Quality of Life

This book is a collection of chapters addressing various aspects of quality of life and health psychology from a biopsychosocial perspective. Chapters cover crucial issues, both clinical and social. Starting with an analysis of the concept of quality of life as it is described by the World Health Organization, subsequent chapters of the book examine the biological, psychological, social, and spiritual issues related to the concept. The book explores how health, climate, psychiatric diseases, and social conditions of specific geographical areas can impact quality of life

Making Black History

This study proposes that Afropolitanism may be best approached as a distinct cultural moment or historical constellation that allows us to glimpse the shifting and multiple silhouettes which Africa – as signifier, as real and imagined locus – embodies in the globalized cultural landscape of the 21st century. As such, Making Black History looks at contemporary diasporic fictions that have been written and received in the moment of Afropolitanism

Post Memes

Art-form, send-up, farce, ironic disarticulation, pastiche, propaganda, trololololol, mode of critique, mode of production, means of politicisation, even of subjectivation -- memes are the inner currency of the internet’s circulatory system. Independent of any one set value, memes are famously the mode of conveyance for the alt-right, the irony left, and the apoliticos alike,  and they are impervious to many economic valuations: the attempts made in co-opting their discourse in advertising and big business have made little headway, and have usually been derailed by retaliative meming. Post-Memes: Seizing the Memes of Production takes advantage of the meme’s subversive adaptability and ripeness for a focused, in-depth study. Pulling together the interrogative forces of a raft of thinkers at the forefront of tech theory and media dissection, this collection of essays paves a way to articulating the semiotic fabric of the early 21st century’s most prevalent means of content posting, and aims at the very seizing of the memes of production for the imagining and creation of new political horizons.With contributions from Scott and McKenzie Wark, Patricia Reed, Jay Owens, Thomas Hobson and Kaajal Modi, Dominic Pettman, Bogna M. Konior, and Eric Wilson, among others, this essay volume offers the freshest approaches available in the field of memes studies and inaugurates a new kind of writing about the newest manifestations of the written online. The book aims to become the go-to resource for all students and scholars of memes, and will be of the utmost interest to anyone interested in the internet’s most viral phenomenon

Embodiment in Evolution and Culture

From its beginnings, the theory of evolution has unsettled fundamental anthropological assumptions about the place of human beings in nature. The integration of human origins into natural history by Darwinism was countered by the philosophical anthropologies of the 20th century. Their attempts were to hold on even more resolutely to the special status of humans as beings 'open towards the world'. Today, evolutionary and philosophical anthropology have moved closer together via the paradigm of embodiment. Building on embodied cognitive science, this volume aims to establish how far the human mind and human cultural cognition can be attributed to the structures of human existence, structures which have emerged in the course of evolution and have in turn been affected by culture. The traditional dualism of nature and culture is transformed into an explanation of an evolutionary process in which body and mind are understood to be intertwined and mutually constitutive

Making Black History

This study proposes that Afropolitanism may be best approached as a distinct cultural moment or historical constellation that allows us to glimpse the shifting and multiple silhouettes which Africa – as signifier, as real and imagined locus – embodies in the globalized cultural landscape of the 21st century. As such, Making Black History looks at contemporary diasporic fictions that have been written and received in the moment of Afropolitanism