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Hayflick Limit Theory
Leonard Hayflick (born 20 May 1928) is a Professor of Anatomy at the UCSF School of Medicine, and was Professor of Medical Microbiology at Stanford University School of Medicine. He is a past president of the Gerontological Society of America and was a founding member of the council of the National Institute on Aging (NIA). The recipient of a number of research prizes and awards, including the 1991 Sandoz Prize for Gerontological Research, he has studied the aging process for more than fifty years. He is known for discovering that normal human cells divide for a limited number of times ''in vitro'' (refuting the contention by Alexis Carrel that normal body cells are immortal). This is known as the Hayflick limit. His discoveries overturned a 60-year old dogma that all cultured cells are immortal. Hayflick demonstrated that normal cells have a memory and can remember at what doubling level they have reached. He demonstrated that his normal human cell strains were free from ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philadelphia
Philadelphia, often called Philly, is the largest city in the Commonwealth of Pennsylvania, the sixth-largest city in the U.S., the second-largest city in both the Northeast megalopolis and Mid-Atlantic regions after New York City. Since 1854, the city has been coextensive with Philadelphia County, the most populous county in Pennsylvania and the urban core of the Delaware Valley, the nation's seventh-largest and one of world's largest metropolitan regions, with 6.245 million residents . The city's population at the 2020 census was 1,603,797, and over 56 million people live within of Philadelphia. Philadelphia was founded in 1682 by William Penn, an English Quaker. The city served as capital of the Pennsylvania Colony during the British colonial era and went on to play a historic and vital role as the central meeting place for the nation's founding fathers whose plans and actions in Philadelphia ultimately inspired the American Revolution and the nation's inde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar working in the 19th century in Brno, was the first to study genetics scientifically. Mendel studied "trait inheritance", patterns in the way traits are handed down from parents to offspring over time. He observed that organisms (pea plants) inherit traits by way of discrete "units of inheritance". This term, still used today, is a somewhat ambiguous definition of what is referred to as a gene. Trait inheritance and molecular inheritance mechanisms of genes are still primary principles of genetics in the 21st century, but modern genetics has expanded to study the function and behavior of genes. Gene structure and function, variation, and distribution are studied within the context of the cell, the organism (e.g. dominance), and within the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mycoplasma
''Mycoplasma'' is a genus of bacteria that, like the other members of the class ''Mollicutes'', lack a cell wall around their cell membranes. Peptidoglycan (murein) is absent. This characteristic makes them naturally resistant to antibiotics that target cell wall synthesis (like the beta-lactam antibiotics). They can be parasitic or saprotrophic. Several species are pathogenic in humans, including '' M. pneumoniae'', which is an important cause of "walking" pneumonia and other respiratory disorders, and '' M. genitalium'', which is believed to be involved in pelvic inflammatory diseases. ''Mycoplasma'' species (like the other species of the class ''Mollicutes'') are among the smallest organisms yet discovered, can survive without oxygen, and come in various shapes. For example, ''M. genitalium'' is flask-shaped (about 300 x 600 nm), while ''M. pneumoniae'' is more elongated (about 100 x 1000 nm), many ''Mycoplasma'' species are coccoid. Hundreds of ''Mycoplasma'' species i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atypical Pneumonia
Atypical pneumonia, also known as walking pneumonia, is any type of pneumonia not caused by one of the pathogens most commonly associated with the disease. Its clinical presentation contrasts to that of "typical" pneumonia. A variety of microorganisms can cause it. When it develops independently from another disease, it is called primary atypical pneumonia (PAP). The term was introduced in the 1930s and was contrasted with the bacterial pneumonia caused by ''Streptococcus pneumoniae'', at that time the best known and most commonly occurring form of pneumonia. The distinction was historically considered important, as it differentiated those more likely to present with "typical" respiratory symptoms and lobar pneumonia from those more likely to present with "atypical" generalized symptoms (such as fever, headache, sweating and myalgia) and bronchopneumonia. Signs and symptoms Usually the atypical causes also involve atypical symptoms: * No response to common antibiotics such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Immortality
Biological immortality (sometimes referred to as bio-indefinite mortality) is a state in which the rate of mortality from senescence is stable or decreasing, thus decoupling it from chronological age. Various unicellular and multicellular species, including some vertebrates, achieve this state either throughout their existence or after living long enough. A biologically immortal living being can still die from means other than senescence, such as through injury, poison, disease, predation, lack of available resources, or changes to environment. This definition of immortality has been challenged in the ''Handbook of the Biology of Aging'', because the increase in rate of mortality as a function of chronological age may be negligible at extremely old ages, an idea referred to as the late-life mortality plateau. The rate of mortality may cease to increase in old age, but in most cases that rate is typically very high. The term is also used by biologists to describe cells that are not ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alexis Carrel
Alexis Carrel (; 28 June 1873 – 5 November 1944) was a French surgeon and biologist who was awarded the Nobel Prize in Physiology or Medicine in 1912 for pioneering vascular suturing techniques. He invented the first perfusion pump with Charles A. Lindbergh opening the way to organ transplantation. His positive description of a miraculous healing he witnessed during a pilgrimage earned him scorn of some of his colleagues. This prompted him to relocate to the United States, where he lived most of his life. He had a leading role in implementing eugenic policies in Vichy France.Sade, Robert M. MD''Alexis Carrel, Pioneer Surgeon''Medical University of South Carolina, Charleston, South Carolina.(see Reggiano (2002) as well as Caillois, p. 107) A Nobel Prize laureate in 1912, Alexis Carrel was also elected twice, in 1924 and 1927, as an honorary member of the Academy of Sciences of the USSR. Biography Born in Sainte-Foy-lès-Lyon, Rhône, Carrel was raised in a devout Catholic fam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Senescence
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute On Aging
The National Institute on Aging (NIA) is a division of the U.S. National Institutes of Health (NIH), located in Bethesda, Maryland. The NIA itself is headquartered in Baltimore, Maryland. The NIA leads a broad scientific effort to understand the nature of aging and to extend the healthy, active years of life. In 1974, under Public Law 93-296, Congress granted authority to form NIA to provide leadership in aging research, training, health information dissemination, and other programs relevant to aging and older people. In January 2011, President Obama signed into law the National Alzheimer’s Project Act, designating the NIA as the primary federal agency on Alzheimer's disease research. NIA is led by Director, Richard J. Hodes, M.D, and Acting Deputy Director Melinda Kelley, M.D. Mission NIA's mission is to improve the health and well-being of older Americans through research, and specifically to: *Support and conduct high-quality research on: **Aging processes **Age-related dis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerontological Society Of America
The Gerontological Society of America (GSA) is a multidisciplinary organization devoted to research and education in all aspects of gerontology: medical, biological, psychological and social. History and organization The Gerontological Society of America (GSA) was incorporated in New York City in 1945 as an outgrowth of a group of scientists and physicians who had been calling themselves "the Club for Research on Ageing" since the 1930s. GSA has been holding scientific conferences since 1946. In 1969, GSA moved its main office from St. Louis, Missouri to Washington, D.C. The Gerontological Society of America, along with the American Geriatrics Society advocated for the formation of a National Gerontological Institute. These efforts bore fruit in 1974 when President Richard Nixon signed legislation to create the National Institute on Aging (NIA). In 1946, GSA began publishing ''Journal of Gerontology''. In 1961, material in ''Journal of Gerontology'' dealing with GSA organiza ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stanford University
Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is considered among the most prestigious universities in the world. Stanford was founded in 1885 by Leland and Jane Stanford in memory of their only child, Leland Stanford Jr., who had died of typhoid fever at age 15 the previous year. Leland Stanford was a U.S. senator and former governor of California who made his fortune as a railroad tycoon. The school admitted its first students on October 1, 1891, as a coeducational and non-denominational institution. Stanford University struggled financially after the death of Leland Stanford in 1893 and again after much of the campus was damaged by the 1906 San Francisco earthquake. Following World War II, provost of Stanford Frederick Terman inspired and supported faculty and graduates' entrepreneu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microbiology
Microbiology () is the scientific study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, bacteriology, protistology, mycology, immunology, and parasitology. Eukaryotic microorganisms possess membrane-bound organelles and include fungi and protists, whereas prokaryotic organisms—all of which are microorganisms—are conventionally classified as lacking membrane-bound organelles and include Bacteria and Archaea. Microbiologists traditionally relied on culture, staining, and microscopy. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means. Microbiologists often rely on molecular biology tools such as DNA sequence based identification, for example the 16S rRNA gene sequence used for bacteria identification. Viruses have been variably classified as organisms, as they have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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