There is an additional, more subtle alteration in the dermis that also appears to be independent of UV exposure, namely less compacted collagen bundles in the reticular dermis in association with age. The attenuation of the rete ridges also results in a decreased capacity of the skin to resist shearing forces, commonly illustrated by the comparative difficulty in removing a band aid from the skin of an elderly person versus the skin of a child without incurring epidermal disruption or associated hemorrhage. This change is accompanied by attenuation and loss of dermal papillae that undulate with rete ridges and that contain the delicate capillary loops in part responsible for epidermal nourishment. One of the first alterations that occurs with age and that appears independent of repeated exposure to UV light is thinning of the epidermal layer associated with loss of epidermal rete ridges. Figure 1 provides a histochemical overview that compares some of the salient structural and compositional attributes of the aged skin phenotype through examination of sun-exposed (face) and non–sun-exposed (lower abdomen) skin from subjects who are vicenarians (in the third decade) and octogenarians (in the ninth decade). Despite the mirth and laughter of wrinkles, what is going on under the wrinkled surface when skin is pathologically altered during an individual lifetime is no laughing matter. Whereas not all organs show overt structural/gross pathologic findings of aging, the skin regularly, albeit variably, shows the clinical ravages of time. Conquest of the oft overlooked disease of skin aging should have broad implications that transcend the integument and inform novel approaches to retarding aging and age-related dysfunction in those internal organs that youthful skin was designed to envelop and safeguard. Herein, the authors provide a review of current insights into skin aging, including the mechanisms of skin aging, the role of stem cells in skin aging and the implications of skin aging for the microbiome and for the development of cancer. Past and current understanding of the cellular and molecular intricacies of skin aging provide a foundation for future approaches designed to thwart the aging phenotype. At a cellular level, stem cell dysfunction and attrition appear to be key events, and both genetic and epigenetic factors are involved in a complex interplay that over time results in deterioration of our main protective interface with the external environment. The pathobiologic basis for skin aging remains poorly understood. The consequences of this disorder are many and varied, ranging from atrophy and fragility to defective repair to deficient immunity and vulnerability to certain infections. Send us feedback about these examples.Long considered both physiologic and inevitable, skin aging is a degenerative phenomenon whereby both intrinsic and environmental factors conspire to produce an authentic disease. These examples are programmatically compiled from various online sources to illustrate current usage of the word 'pathogenic.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. George Makari, The New Yorker, 13 July 2023 See More Julia Ries, SELF, 27 July 2023 At any of these different levels of biology, a pathogenic event might disrupt us. 2023 The end result: Your trusty little earbuds may very well be covered in potentially pathogenic germs. 2023 Whether the changes will lead to variants that are more pathogenic or transmissible is unclear, the researchers say. Annie Berman, Anchorage Daily News, The move comes amid mounting concern over the threat posed by the ongoing spread of highly pathogenic avian influenza over the past few years, which has devastated flocks of wild and commercial birds around the continent. 2023 Now, Atwood and others are contending with what a future where the highly pathogenic strain is here to stay - a daunting possibility. 2023 The research team, decked out in full PPE, was witnessing the toll of the spread of a highly pathogenic avian influenza, H5N1, which has reached nearly every corner of the globe in recent years and decimated untold millions of birds, domestic and wild. Claire Hao, San Francisco Chronicle, 12 Apr. Fish and Wildlife Service suspects to be the disease, according to a Wednesday update. 2023 Six California condors in the Arizona-Utah population are confirmed to have died of highly pathogenic avian influenza, and 12 from the same flock have died of what the U.S. Meghan Bartels, Scientific American, 29 Aug. Recent Examples on the Web But in Europe a highly pathogenic strain became epidemic in numerous species of wild birds by 2021, and the strain reached the U.S.
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