Senescence The Last Half of Life G. Stanley Hall, Ph.D., LL.D.

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Excerpt from Senescence: The Last Half of Life In this book I have tried to present the subjects of Old Age and Death from as many viewpoints as possible in order to show how the ignorant and the learned, the child, the adult, and the old, savage and civilized man, pagans and Christians, the ancient and the modern world, the representatives of various sciences, and different individuals have viewed these problems, letting each class, so far as I could, speak for itself. This part of the task has been long and arduous and my conspectus is not entirely encyclopedic, as it set out to be. I have also tried to develop an idea of death, and especially of old age, which I believe to be, if not essentially new, more true to the facts of life and mind than those now current, and which I think much needed by the world just now. Despite the great and growing interest that has impelled this study, its themes have proved increasingly depressing, so that its conclusion brings a unique relief that I may now turn to more cheerful occupations, although it would be craven to plead this as an extenuation of the shortcomings of which I am increasingly conscious. If I have at certain points drawn too frankly upon my own personal experiences with age I realize that this does not compensate for my limitations in some of the special fields I ventured to enter. I have had in mind throughout chiefly the nature and needs of intelligent people passing or past middle life quite as much as of those actually entering old age. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.

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In this second volume in the series exploring Tumor Dormancy, Quiescence, and Cellular Senescence, discussion is focused on the role of tumor dormancy in diseases such as breast cancer, melanoma, prostate cancer, liver cancer and lung cancer. M. A. Hayat, the series editor, writes in the preface that little is known of factors regulating the transition of residual cancer into a dormant state or the subsequent reinitiation of growth. A majority of us, he says, have in situ tumors that may remain dormant or may progress into a lethal form of cancer; the former are prevented from recruiting their own blood supply. Section I covers Molecular Mechanisms, with chapters on the role of NAE inhibitor MLN4924; oncogene-induced senescence; the role played by mitogen-activated protein kinase in the induction of cellular senescence; mechanisms of premature cell senescence and other topics. Section II examines Tumor and Cancer, discussing defects in chromatin structure and diseases; the role of fibrosis in tumor progression and the dormant to proliferative switch; the function of ING proteins in cancer and senescence and more. The final section is devoted to Stem Cells and Cancer Stem Cells, featuring chapters showing that senescent-derived pluripotent stem cells are able to redifferentiate into fully rejuvenated cells; that the transcription factor Gata2 regulates quiescence in haematopoietic stem and progenitor cells; and discussing dormancy and recurrence of cancer stem cells in bone. The contributors point out that the quiescent state regulates hematopoietic stem cells and muscle stem cells, and detail the role of kinase in the mediation of reversible quiescent state in a subset of ovarian, pancreatic, and colon cancers. Molecular mechanisms underlying stress-induced cellular senescence and accumulation of reactive oxygen species and induction of premature senescence are also presented. Discussion includes the important role of microRNAs in oxidative stress-induced apoptosis and senescence and the effect of microRNA as a modulator of cell proliferation in lung cancer. The book includes an explanation of the suppression of cellular senescence in glioblastoma brain tumor. Taking a broad and varied perspective, this volume was written by 70 contributors representing 11 countries.