Biological immortality can be defined as the absence of a sustained increase in rate of mortality as a function of chronological age. A cell or organism that does not experience, or at some future point will cease aging, is biologically immortal. However this definition of immortality was challenged in the new "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 (late-life mortality plateau). But even though the rate of mortality ceases to increase in old age, those rates are very high (e.g., 50% chance of surviving another year at age 110 or 115 years of age).
There is no known organism or individual cell that is inviolably immortal. Any life enjoying biological immortality can die if exposed to a toxic environment, or otherwise killed or destroyed
Monday, May 5, 2008
Telomere
A telomere is a region of repetitive DNA at the end of chromosomes, which protects the end of the chromosome from destruction. Derived from the Greek telos (end) and meres (part).
During cell division, the enzymes that duplicate the chromosome and its DNA can't continue their duplication all the way to the end of the chromosome. If cells divided without telomeres, they would lose the end of their chromosomes, and the necessary information it contains. (In 1972, James Watson named this phenomenon the "end replication problem.") The telomere is a disposable buffer, which is consumed during cell division and is replenished by an enzyme, the telomerase reverse transcriptase.
This mechanism usually limits cells to a fixed number of divisions, and animal studies suggest that this is responsible for aging on the cellular level and affects lifespan. Telomeres protect a cell's chromosomes from fusing with each other or rearranging. These chromosome abnormalities can lead to cancer, so cells are normally destroyed when telomeres are consumed. Most cancer is the result of cells bypassing this destruction. Biologists speculate that this mechanism is a tradeoff between aging and cancer.
During cell division, the enzymes that duplicate the chromosome and its DNA can't continue their duplication all the way to the end of the chromosome. If cells divided without telomeres, they would lose the end of their chromosomes, and the necessary information it contains. (In 1972, James Watson named this phenomenon the "end replication problem.") The telomere is a disposable buffer, which is consumed during cell division and is replenished by an enzyme, the telomerase reverse transcriptase.
This mechanism usually limits cells to a fixed number of divisions, and animal studies suggest that this is responsible for aging on the cellular level and affects lifespan. Telomeres protect a cell's chromosomes from fusing with each other or rearranging. These chromosome abnormalities can lead to cancer, so cells are normally destroyed when telomeres are consumed. Most cancer is the result of cells bypassing this destruction. Biologists speculate that this mechanism is a tradeoff between aging and cancer.
Chondrocyte
Chondrocytes (from Greek chondros cartilage + kytos cell) are the only cells found in cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and proteoglycans. Although chondroblast is still commonly used to describe an immature chondrocyte, use of the term is discouraged, for it is technically inaccurate since the progenitor of chondrocytes (which are mesenchymal stem cells) can also differentiate into osteoblasts.
Fibroblast
A fibroblast is a type of cell that synthesizes and maintains the extracellular matrix of many animal tissues. Fibroblasts provide a structural framework (stroma) for many tissues, and play a critical role in wound healing. They are the most common cells of connective tissue in animals. Fibroblasts were first discovered by Dr. Matthias De Oliveira in 1968.
The main function of fibroblasts is to maintain the structural integrity of connective tissues by continuously secreting precursors of the extracellular matrix. Fibroblasts secrete the precursors of all the components of the extracellular matrix, primarily the ground substance and a variety of fibres. The composition of the extracellular matrix determines the physical properties of connective tissues.
Fibroblasts are morphologically heterogeneous with diverse appearances depending on their location and activity. Though morphologically inconspicuous, ectopically transplanted fibroblasts can often retain positional memory of the location and tissue context where they had previously resided, at least over a few generations
The main function of fibroblasts is to maintain the structural integrity of connective tissues by continuously secreting precursors of the extracellular matrix. Fibroblasts secrete the precursors of all the components of the extracellular matrix, primarily the ground substance and a variety of fibres. The composition of the extracellular matrix determines the physical properties of connective tissues.
Fibroblasts are morphologically heterogeneous with diverse appearances depending on their location and activity. Though morphologically inconspicuous, ectopically transplanted fibroblasts can often retain positional memory of the location and tissue context where they had previously resided, at least over a few generations
Stem cell
Stem cellular structures are cells found in most multi-cellular organisms. They are capable of retaining the ability to reinvigorate themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types. Research in the stem cell field grew out of findings by Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s. The two broad types of mammalian stem cells are: embryonic stem cells that are found in blastocysts, and adult stem cells that are found in adult tissues. In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.
As stem cells can be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed. In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates
As stem cells can be grown and transformed into specialized cells with characteristics consistent with cells of various tissues such as muscles or nerves through cell culture, their use in medical therapies has been proposed. In particular, embryonic cell lines, autologous embryonic stem cells generated through therapeutic cloning, and highly plastic adult stem cells from the umbilical cord blood or bone marrow are touted as promising candidates
Stem cell treatments
Medical researchers believe that stem cell treatments have the potential to change the face of human disease and alleviate suffering. A number of stem cell treatments already exist, although most are still experimental and/or costly, with the notable exception of bone marrow transplantation. In the future, medical researchers anticipate being able to use technologies derived from adult and embryonic stem cell research to treat cancer, Type 1 diabetes mellitus, spinal cord injuries, and muscle damage, amongst a number of other diseases and impairments.
However, there still exists a great deal of social and scientific uncertainty surrounding embryonic stem cell research, which will only be overcome through years of intensive research and by gaining the acceptance of the public.
Furthermore, very promising treatments of serious diseases with adult stem cells have already been attempted. The advantage of adult stem cells over embryonic stem cells is that there are no rejection issues, because the stem cells are from the same body.
However, there still exists a great deal of social and scientific uncertainty surrounding embryonic stem cell research, which will only be overcome through years of intensive research and by gaining the acceptance of the public.
Furthermore, very promising treatments of serious diseases with adult stem cells have already been attempted. The advantage of adult stem cells over embryonic stem cells is that there are no rejection issues, because the stem cells are from the same body.
Bioartificial liver device
A bioartificial liver device (BAL) is an artificial extracorporeal supportive device for an individual who is suffering from acute liver failure.
Artificial Pancreas
The artificial pancreas is a technology in development to help people with diabetes automatically control their blood glucose level by providing the substitute endocrine functionality of a healthy pancreas.
There are several important exocrine (digestive) and endocrine (hormonal) functions of the pancreas, but it is the lack of insulin production which is the motivation to develop a substitute. While the current state of insulin replacement therapy is appreciated for its life-saving capability, the task of manually managing the blood sugar level with insulin alone is arduous and inadequate.
There are several important exocrine (digestive) and endocrine (hormonal) functions of the pancreas, but it is the lack of insulin production which is the motivation to develop a substitute. While the current state of insulin replacement therapy is appreciated for its life-saving capability, the task of manually managing the blood sugar level with insulin alone is arduous and inadequate.
Urinary Bladder
In anatomy, the urinary bladder is a hollow, muscular, and distensible (or elastic) organ that sits on the pelvic floor in mammals. It is the organ that collects urine excreted by the kidneys prior to disposal by urination. Urine enters the bladder via the ureters and exits via the urethra.
In males, the bladder is superior to the prostate, and separated from the rectum by the rectovesical excavation.
In females, the bladder is separated from the rectum by the rectouterine excavation, and it is separated from the uterus by the vesicouterine excavation.
In males, the bladder is superior to the prostate, and separated from the rectum by the rectovesical excavation.
In females, the bladder is separated from the rectum by the rectouterine excavation, and it is separated from the uterus by the vesicouterine excavation.
Circulatory system
The circulatory system is an organ system that moves nutrients, gases, and wastes to and from cells, helps fight diseases and helps stabilize body temperature and pH to maintain homeostasis. This system may be seen strictly as a blood distribution network, but some consider the circulatory system as composed of the cardiovascular system, which distributes blood, and the lymphatic system, which distributes lymph. While humans, as well as other vertebrates, have a closed cardiovascular system (meaning that the blood never leaves the network of arteries, veins and capillaries), some invertebrate groups have an open cardiovascular system. The most primitive animal phyla lack circulatory systems. The lymphatic system, on the other hand, is an open system
Blood vessels
The blood vessels are part of the cardiovascular system and function to transport blood throughout the body. The most important vessels in the system are the capillaries, the microscopic vessels which enable the actual exchange of water and chemicals between the blood and the tissues, while the conduit vessels, arteries and veins, carry blood away from the heart and through the capillaries or back towards the heart, respectively
Cartilage
Cartilage is a type of dense connective tissue. It is composed of specialized cells called chondrocytes that produce a large amount of extracellular matrix composed of collagen fibers, abundant ground substance rich in proteoglycan, and elastin fibers. Cartilage is classified in three types, elastic cartilage, hyaline cartilage and fibrocartilage, that differ in the relative amounts of these three main components.
Cartilage is found in many places in the body including the articular surface of the bones, the rib cage, the ear, the nose, the bronchial tubes and the intervertebral discs. Its mechanical properties are intermediate between bone and dense connective tissue like tendon.
Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are fed by diffusion, helped by the pumping action generated by compression of the articular cartilage or flexion of the elastic cartilage. Thus, compared to other connective tissues, cartilage grows and repairs more slowly.
Cartilage is found in many places in the body including the articular surface of the bones, the rib cage, the ear, the nose, the bronchial tubes and the intervertebral discs. Its mechanical properties are intermediate between bone and dense connective tissue like tendon.
Unlike other connective tissues, cartilage does not contain blood vessels. The chondrocytes are fed by diffusion, helped by the pumping action generated by compression of the articular cartilage or flexion of the elastic cartilage. Thus, compared to other connective tissues, cartilage grows and repairs more slowly.
Bone
Bones are rigid organs that form part of the endoskeleton of vertebrates. They function to move, support, and protect the various organs of the body, produce red and white blood cells and store minerals. Because bones come in a variety of shapes and have a complex internal and external structure, they are lightweight, yet strong and hard, in addition to fulfilling their many other functions. One of the types of tissues that makes up bone is the mineralized osseous tissue, also called bone tissue, that gives it rigidity and honeycomb-like three-dimensional internal structure. Other types of tissue found in bones include marrow, endosteum and periosteum, nerves, blood vessels and cartilage. There are 206 bones in the adult body and about 300 bones in the infant body.
Biochemical
Biochemistry (from Greek: βίος, bios, "life" and Egyptian kēme, "earth" is the study of the chemical processes in living organisms. It deals with the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules. Chemical biology aims to answer many questions arising from biochemistry by using tools developed within chemical synthesis.
Although there are a vast number of different biomolecules, many are complex and large molecules (called polymers) that are composed of similar repeating subunits (called monomers). Each class of polymeric biomolecule has a different set of subunit types. For example, a protein is a polymer made up of 20 or more amino acids. Biochemistry studies the chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions.
The biochemistry of cell metabolism and the endocrine system has been extensively described. Other areas of biochemistry include the genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction.
Although there are a vast number of different biomolecules, many are complex and large molecules (called polymers) that are composed of similar repeating subunits (called monomers). Each class of polymeric biomolecule has a different set of subunit types. For example, a protein is a polymer made up of 20 or more amino acids. Biochemistry studies the chemical properties of important biological molecules, like proteins, in particular the chemistry of enzyme-catalyzed reactions.
The biochemistry of cell metabolism and the endocrine system has been extensively described. Other areas of biochemistry include the genetic code (DNA, RNA), protein synthesis, cell membrane transport, and signal transduction.
Material science
Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials and their properties. It includes elements of applied physics and chemistry, as well as chemical, mechanical, civil and electrical engineering. With significant media attention to nanoscience and nanotechnology in recent years, materials science has been propelled to the forefront at many universities. It is also an important part of forensic engineering and forensic materials engineering, the study of failed products and components
Engineering
Engineering is the discipline and profession of applying scientific knowledge and utilizing natural laws and physical resources in order to design and implement materials, structures, machines, devices, systems, and processes that realize a desired objective and meet specified criteria. The American Engineers' Council for Professional Development, also known as ECPD, (later ABET), defines Engineering as: “the creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate the same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property.
One who practices engineering is called an engineer, and those licensed to do so may have more formal designations such as Professional Engineer, Chartered Engineer, or Incorporated Engineer. The broad discipline of engineering encompasses a range of more specialized subdisciplines, each with a more specific emphasis on certain fields of application and particular areas of technology
One who practices engineering is called an engineer, and those licensed to do so may have more formal designations such as Professional Engineer, Chartered Engineer, or Incorporated Engineer. The broad discipline of engineering encompasses a range of more specialized subdisciplines, each with a more specific emphasis on certain fields of application and particular areas of technology
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