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Biological Clock (aging)
An epigenetic clock is a biochemical test that can be used to measure age. The test is based on modifications that change over time and regulate how genes are expressed. Typically, the test examines DNA methylation levels, measuring the accumulation of methyl groups to one's DNA molecules, or more recently, based on the histone code. History The strong effects of age on DNA methylation levels have been known since the late 1960s. A vast literature describes sets of CpGs whose DNA methylation levels correlate with age. The first robust demonstration that DNA methylation levels in saliva could generate age predictors with an average accuracy of 5.2 years was published by a UCLA team including Sven Bocklandt, Steve Horvath, and Eric Vilain in 2011 (Bocklandt et al. 2011). The laboratories of Trey Ideker and Kang Zhang at the University of California, San Diego published the Hannum epigenetic clock (Hannum 2013), which consisted of 71 markers that accurately estimate age based on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomarkers Of Aging
Biomarkers of aging are biomarkers that could predict functional capacity at some later age better than chronological age. Stated another way, biomarkers of aging would give the true "biological age", which may be different from the chronological age. Validated biomarkers of aging would allow for testing interventions to life extension, extend lifespan, because changes in the biomarkers would be observable throughout the lifespan of the organism. Although maximum lifespan would be a means of validating biomarkers of aging, it would not be a practical means for long-lived species such as humans because longitudinal studies would take far too much time. Ideally, biomarkers of aging should assay the biological process of aging and not a predisposition to disease, should cause a minimal amount of trauma to assay in the organism, and should be reproducibly measurable during a short interval compared to the lifespan of the organism. An assemblage of biomarker data for an organism could b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergence
In philosophy, systems theory, science, and art, emergence occurs when a complex entity has properties or behaviors that its parts do not have on their own, and emerge only when they interact in a wider whole. Emergence plays a central role in theories of integrative levels and of complex systems. For instance, the phenomenon of life as studied in biology is an emergent property of chemistry and physics. In philosophy, theories that emphasize emergent properties have been called emergentism. In philosophy Philosophers often understand emergence as a claim about the etiology of a system's properties. An emergent property of a system, in this context, is one that is not a property of any component of that system, but is still a feature of the system as a whole. Nicolai Hartmann (1882–1950), one of the first modern philosophers to write on emergence, termed this a ''categorial novum'' (new category). Definitions This concept of emergence dates from at least the time of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Forensic
Forensic science combines principles of law and science to investigate criminal activity. Through crime scene investigations and laboratory analysis, forensic scientists are able to link suspects to evidence. An example is determining the time and cause of death through autopsies. This evidence can then be used for proof towards a crime. Forensic science, often confused with criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law. During criminal investigation in particular, it is governed by the legal standards of admissible evidence and criminal procedure. It is a broad field utilizing numerous practices such as the analysis of DNA, fingerprints, bloodstain patterns, firearms, ballistics, toxicology, microscopy, and fire debris analysis. Forensic scientists collect, preserve, and analyze evidence during the course of an investigation. While some forensic scientists travel to the scene of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Differentiation
Cellular differentiation is the process in which a stem cell changes from one type to a differentiated one. Usually, the cell changes to a more specialized type. Differentiation happens multiple times during the development of a multicellular organism as it changes from a simple zygote to a complex system of Tissue (biology), tissues and cell types. Differentiation continues in adulthood as adult stem cells divide and create fully differentiated Cell division, daughter cells during tissue repair and during normal cell turnover. Some differentiation occurs in response to antigen exposure. Differentiation dramatically changes a cell's size, shape, membrane potential, metabolism, metabolic activity, and responsiveness to signals. These changes are largely due to highly controlled modifications in gene expression and are the study of epigenetics. With a few exceptions, cellular differentiation almost never involves a change in the DNA sequence itself. Metabolic composition, however ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Developmental Biology
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of Regeneration (biology), regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism. Perspectives The main processes involved in the embryogenesis, embryonic development of animals are: tissue patterning (via regional specification and patterned cellular differentiation, cell differentiation); tissue growth; and tissue morphogenesis. * Regional specification refers to the processes that create the spatial patterns in a ball or sheet of initially similar cells. This generally involves the action of cytoplasmic determinants, located within parts of the fertilized egg, and of inductive signals emitted from signaling centers in the embryo. The early stages of regional specification do not generate functional differentiated cells, but cell populations committed to developing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rejuvenation (aging)
Rejuvenation is a medical discipline focused on the practical reversal of the aging process. Rejuvenation is distinct from life extension. Life extension strategies often study the causes of aging and try to oppose those causes to slow aging. Rejuvenation is the ''reversal'' of aging and thus requires a different strategy, namely repair of the damage that is associated with aging or replacement of damaged tissue with new tissue. Rejuvenation can be a means of life extension, but most life extension strategies do not involve rejuvenation. Historical and cultural background Various myths tell the stories about the quest for rejuvenation. It was believed that magic or intervention of a supernatural power can bring back youth and many mythical adventurers set out on a journey to do that, for themselves, their relatives or some authority that sent them anonymously. An ancient Chinese emperor sent out ships of young men and women to find a pearl that would rejuvenate him. This le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surrogate Marker
In clinical trials, a surrogate endpoint (or surrogate marker) is a measure of effect of a specific treatment that may correlate with a ''real'' clinical endpoint but does not necessarily have a guaranteed relationship. The National Institutes of Health (USA) defines surrogate endpoint as "a biomarker intended to substitute for a clinical endpoint". Surrogate markers are used when the primary endpoint is undesired (e.g., death), or when the number of events is very small, thus making it impractical to conduct a clinical trial to gather a statistically significant number of endpoints. The FDA and other regulatory agencies will often accept evidence from clinical trials that show a direct clinical benefit to surrogate markers. Surrogate endpoints can be obtained from different modalities, such as, behavioural or cognitive scores, or biomarkers from Electroencephalography ( qEEG), MRI, PET, or biochemical biomarkers. A correlate does not make a surrogate. It is a common misconception ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cancer
Cancer is a group of diseases involving Cell growth#Disorders, abnormal cell growth with the potential to Invasion (cancer), invade or Metastasis, spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible Signs and symptoms of cancer, signs and symptoms include a lump, abnormal bleeding, prolonged cough, unexplained weight loss, and a change in defecation, bowel movements. While these symptoms may indicate cancer, they can also have other causes. List of cancer types, Over 100 types of cancers affect humans. Tobacco use is the cause of about 22% of cancer deaths. Another 10% are due to obesity, poor Diet (nutrition), diet, sedentary lifestyle, lack of physical activity or Alcohol abuse, excessive alcohol consumption. Other factors include certain infections, exposure to ionizing radiation, and environmental pollutants. infectious causes of cancer, Infection with specific viruses, bacteria and parasites is an environmental factor cau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical conditions that are associated with specific signs and symptoms. A disease may be caused by external factors such as pathogens or by internal dysfunctions. For example, internal dysfunctions of the immune system can produce a variety of different diseases, including various forms of immunodeficiency, hypersensitivity, allergy, allergies, and autoimmune disorders. In humans, ''disease'' is often used more broadly to refer to any condition that causes pain, Abnormality (behavior), dysfunction, distress (medicine), distress, social problems, or death to the person affected, or similar problems for those in contact with the person. In this broader sense, it sometimes includes injury in humans, injuries, disability, disabilities, Disorder (medicine) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theories Of Biological Aging
Senescence () or biological aging is the gradual deterioration of functional characteristics in living organisms. Whole organism senescence involves an increase in death rates or a decrease in fecundity with increasing age, at least in the later part of an organism's life cycle. However, the resulting effects of senescence can be delayed. The 1934 discovery that calorie restriction can extend lifespans by 50% in rats, the existence of species having negligible senescence, and the existence of potentially immortal organisms such as members of the genus '' 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 age at different rates and distinctly, including the brain, the cardiovascular system, and muscle. Similarly, functions may di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organisms
An organism is any living thing that functions as an individual. Such a definition raises more problems than it solves, not least because the concept of an individual is also difficult. Many criteria, few of them widely accepted, have been proposed to define what an organism is. Among the most common is that an organism has autonomous reproduction, growth, and metabolism. This would exclude viruses, despite the fact that they evolve like organisms. Other problematic cases include colonial organisms; a colony of eusocial insects is organised adaptively, and has germ-soma specialisation, with some insects reproducing, others not, like cells in an animal's body. The body of a siphonophore, a jelly-like marine animal, is composed of organism-like zooids, but the whole structure looks and functions much like an animal such as a jellyfish, the parts collaborating to provide the functions of the colonial organism. The evolutionary biologists David Queller and Joan Strassmann ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomarkers Of Aging
Biomarkers of aging are biomarkers that could predict functional capacity at some later age better than chronological age. Stated another way, biomarkers of aging would give the true "biological age", which may be different from the chronological age. Validated biomarkers of aging would allow for testing interventions to life extension, extend lifespan, because changes in the biomarkers would be observable throughout the lifespan of the organism. Although maximum lifespan would be a means of validating biomarkers of aging, it would not be a practical means for long-lived species such as humans because longitudinal studies would take far too much time. Ideally, biomarkers of aging should assay the biological process of aging and not a predisposition to disease, should cause a minimal amount of trauma to assay in the organism, and should be reproducibly measurable during a short interval compared to the lifespan of the organism. An assemblage of biomarker data for an organism could b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
