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Aging DNA
Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. The word ''senescence'' can refer to either cellular senescence or to senescence of the whole organism. Organismal senescence involves an increase in death rates and/or a decrease in fecundity with increasing age, at least in the latter part of an organism's life cycle. Senescence is the inevitable fate of almost all multicellular organisms with germ-soma separation, but it can be delayed. The discovery, in 1934, that calorie restriction can extend lifespan by 50% in rats, and the existence of species having negligible senescence and potentially immortal organisms such as '' Hydra'', have motivated research into delaying senescence and thus age-related diseases. Rare human mutations can cause accelerated aging diseases. Environmental factors may affect aging – for example, overexposure to ultraviolet radiation accelerates skin aging. Different parts of the body may ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ann Pouder
American supercentenarians are citizens or residents of the United States who have attained or surpassed 110 years of age. , the Gerontology Research Group (GRG) had validated the longevity claims of 782 American supercentenarians. As of , it lists the oldest living American-born person as Spanish emigrant María Branyas Morera (born in San Francisco, California on March 4, 1907), aged . The oldest American resident is listed as Edie Ceccarelli (born in Willits, California on February 5, 1908), aged . The longest-lived person ever from the United States is Sarah Knauss, of Hollywood, Luzerne County, Pennsylvania, who died on December 30, 1999, aged 119 years and 97 days. 100 oldest known Americans Below is a list of the 100 longest lived American supercentenarians according to the GRG and reliable sourcing. Biographies Ann Pouder Ann Pouder (née Ann Marie Alexander; April 8, 1807 – July 10, 1917) was one of the first modern recognized supercentenarians, living to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin Aging
The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue guarding muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals' skin, and it is very similar to pig skin. Though nearly all human skin is covered with hair follicles, it can appear hairless. There are two general types of skin, hairy and glabrous skin (hairless). The adjective ''cutaneous'' literally means "of the skin" (from Latin ''cutis'', skin). Because it interfaces with the environment, skin plays an important immunity role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discoloured and depigmented. In humans, skin pigmentation (affected by m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nutrient Sensing
Nutrient sensing is a cell's ability to recognize and respond to fuel substrates such as glucose. Each type of fuel used by the cell requires an alternate pathway of utilization and accessory molecules. In order to conserve resources a cell will only produce molecules that it needs at the time. The level and type of fuel that is available to a cell will determine the type of enzymes it needs to express from its genome for utilization. Receptors on the cell membrane's surface designed to be activated in the presence of specific fuel molecules communicate to the cell nucleus via a means of cascading interactions. In this way the cell is aware of the available nutrients and is able to produce only the molecules specific to that nutrient type. Nutrient Sensing in Mammalian Cells A rapid and efficient response to disturbances in nutrient levels is crucial for the survival of organisms from bacteria to humans. Cells have therefore evolved a host of molecular pathways that can sense ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteostasis
Proteostasis is the dynamic regulation of a balanced, functional proteome. The proteostasis network includes competing and integrated biological pathways within cells that control the biogenesis, folding, trafficking, and degradation of proteins present within and outside the cell. Loss of proteostasis is central to understanding the cause of diseases associated with excessive protein misfolding and degradation leading to loss-of-function phenotypes, as well as aggregation-associated degenerative disorders. Therapeutic restoration of proteostasis may treat or resolve these pathologies. Cellular proteostasis is key to ensuring successful development, healthy aging, resistance to environmental stresses, and to minimize homeostatic perturbations from pathogens such as viruses. Cellular mechanisms for maintaining proteostasis include regulated protein translation, chaperone assisted protein folding, and protein degradation pathways. Adjusting each of these mechanisms based on the need f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigenetics
In biology, epigenetics is the study of stable phenotypic changes (known as ''marks'') that do not involve alterations in the DNA sequence. The Greek prefix '' epi-'' ( "over, outside of, around") in ''epigenetics'' implies features that are "on top of" or "in addition to" the traditional genetic basis for inheritance. Epigenetics most often involves changes that affect the regulation of gene expression, but the term can also be used to describe any heritable phenotypic change. Such effects on cellular and physiological phenotypic traits may result from external or environmental factors, or be part of normal development. The term also refers to the mechanism of changes: functionally relevant alterations to the genome that do not involve mutation of the nucleotide sequence. Examples of mechanisms that produce such changes are DNA methylation and histone modification, each of which alters how genes are expressed without altering the underlying DNA sequence. Gene expression c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telomere
A telomere (; ) is a region of repetitive nucleotide sequences associated with specialized proteins at the ends of linear chromosomes. Although there are different architectures, telomeres, in a broad sense, are a widespread genetic feature most commonly found in eukaryotes. In most, if not all species possessing them, they protect the terminal regions of chromosomal DNA from progressive degradation and ensure the integrity of linear chromosomes by preventing DNA repair systems from mistaking the very ends of the DNA strand for a double-strand break. Discovery In the early 1970s, Soviet theorist Alexei Olovnikov first recognized that chromosomes could not completely replicate their ends; this is known as the "end replication problem". Building on this, and accommodating Leonard Hayflick's idea of limited somatic cell division, Olovnikov suggested that DNA sequences are lost every time a cell replicates until the loss reaches a critical level, at which point cell division end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genomic Instability
Genome instability (also genetic instability or genomic instability) refers to a high frequency of mutations within the genome of a cellular lineage. These mutations can include changes in nucleic acid sequences, chromosomal rearrangements or aneuploidy. Genome instability does occur in bacteria. In multicellular organisms genome instability is central to carcinogenesis, and in humans it is also a factor in some neurodegenerative diseases such as amyotrophic lateral sclerosis or the neuromuscular disease myotonic dystrophy. The sources of genome instability have only recently begun to be elucidated. A high frequency of externally caused DNA damage can be one source of genome instability since DNA damage can cause inaccurate translesion DNA synthesis past the damage or errors in repair, leading to mutation. Another source of genome instability may be epigenetic or mutational reductions in expression of DNA repair genes. Because endogenous (metabolically-caused) DNA damage is very fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
