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Programmed cell death - Wikipedia, the free encyclopedia In contrast to necrosis, which is a form of cell death that results from acute tissue injury and provokes an inflammatory response, PCD is carried out in a regulated process that generally confers advantages during an organism's life cycle. The fact that programmed cell death has been the subject of increasing attention and research efforts was highlighted by the award of the 2002 Nobel Prize in Physiology or Medicine to Sydney Brenner (United Kingdom), H. Most of the time, invading bacteria are destroyed by the white blood cells; however, it is not uncommon for the chemical warfare waged by the prokaryotes to succeed, with the known consequences of infection, and the resulting damage. en.wikipedia.org /wiki/Cell_death   (1381 words)

Programmed cell death Programmed cell death proceeds in three genetically distinguishable phases: during the "specification phase", a cell is instructed to undergo programmed cell death; in the "killing phase", the apoptotic program is activated in the cell instructed to die; during the "execution phase", cells are dismantled and subsequently engulfed by neighboring cells (Horvitz, 1999; Figure 2). Sulston, J.E., and Horvitz, H.R. Post-embryonic cell lineages of the nematode, Caenorhabditis elegans. Sulston, J.E., and Horvitz, H.R. Abnormal cell lineages in mutants of the nematode Caenorhabditis elegans. www.wormbook.org /chapters/www_programcelldeath/programcelldeath.html   (5937 words)

Death - Wikipedia, the free encyclopedia Death was once defined as the cessation of heartbeat (cardiac arrest) and of breathing, but the development of CPR and prompt defibrillation posed a challenge, rendering the previous definition inadequate. Identifying the moment of death is important in cases of transplantation, as organs for transplant (the brain excluded) must be harvested as quickly as possible after the death of the body. Soon after death (15–120 minutes depending on various factors), the body begins to cool (algor mortis), becomes pallid (pallor mortis), and internal sphincter muscles relax, leading to the release of urine, feces, and stomach contents if the body is moved. en.wikipedia.org /wiki/Death   (3687 words)

Apoptosis in Development Programmed cell death (PCD) is an important mechanism in both development and homeostasis in adult tissues for the removal of either superfluous, infected, transformed or damaged cells by activation of an intrinsic suicide program. Cells undergoing apoptosis usually exhibit a characteristic morphology, including fragmentation of the cell into membrane-bound apoptotic bodies, nuclear and cytoplasmic condensation and endolytic cleavage of the DNA into small oligonucleosomal fragments (Steller, 1995). Recently, the dependence of prostate cells on androgens to avoid cell death has been exploited therapeutically by the use of androgen ablation to invoke apoptosis in prostate cancer cells and prolong survival in men with prostate cancer. www.ucalgary.ca /~browder/apoptosis.html   (1406 words)

Cell Death and Its Regulation Programmed cell death, a central mechanism controlling multicellular development, leads to deletion of entire structures (e.g., the tail in developing human embryos), sculpts specific tissues by ablating fields of cells (e.g., tissue between developing digits), and regulates the number of neurons in the nervous system. Whether cells commit suicide for lack of survival signals or are murdered by killing signals from other cells, recent studies suggest that death is mediated by a common molecular pathway. The demise of cells by programmed cell death is marked by a well-defined sequence of morphological changes, collectively referred to as apoptosis, a Greek word that means "dropping off" or "falling off" as in leaves from a tree. www.ncbi.nlm.nih.gov /books/bv.fcgi?rid=mcb.section.6889   (2307 words)

Collagen gel overlay induces apoptosis of polarized cells in cultures: disoriented cell death -- Tang et al. 275 (4): ... To determine whether the cell death induced by collagen gel overlay was apoptosis, we employed Hoechst 33258 staining. For these experiments, cells were cultured to certain stage and then underwent specific treatment and their cell numbers were assessed at 24, 48, and 72 h. Previous reports have demonstrated that MDCK cells cultured at a lower density were resistant to homeless cell death (7). ajpcell.physiology.org /cgi/content/full/275/4/C921   (5117 words)

Cell Death - Search Results - MSN Encarta Cell Death, in multicellullar organisms, the tightly regulated cell suicide programme in which the cell implements its own death in response to a... Animal cells need signals from other cells not only to proliferate but even to survive. Living cells reproduce by carrying out an orderly sequence of events in which they duplicate their contents and then divide into two. uk.encarta.msn.com /Cell_Death.html   (129 words)

CELL DEATH University of Chicago Magazine, June 96   (Site not responding. Last check: 2007-11-01) Cells, it turns out, are active players in their own demise, and stand ever ready to fall on their swords in flamboyant suicide. A cell infected by a virus or injured by radiation, for example, serves the greater good of the organism by giving its life to prevent the damage from spreading. A cell can be murdered by poison or suffocation and die by necrosis, a messy but passive departure: The membrane begins to leak, water and calcium rush in, and the cell bursts, spewing debris over the whole crime scene. magazine.uchicago.edu /9606/9606Celldeath.html   (449 words)

Importance of glucose-6-phosphate dehydrogenase activity in cell death -- Tian et al. 276 (5): C1121 -- AJP - Cell ... Cells were either incubated with combinations of substrates for G6PDH [100 µM NADP and 200 µM glucose 6-phosphate (G6P)] and PGD [100 µM NADP and 200 µM 6-phosphogluconate (6PG)]. that an increase in ROS induces cell death (9, 27). Inhibition of growth of Hela and WI-38 cells by dehydroepianandrosterone and its reversal by ribo- and deoxyribonucleosides. ajpcell.physiology.org /cgi/content/full/276/5/C1121   (6041 words)

Coming to Terms with Death: Science News Online, June 16, 2001 Two years ago, a California scientist stumbled onto evidence for one of these new types of cell death while she was attempting to measure rates of apoptosis in genetically modified human cancer cells. Another form of cell death is in the process of reclaiming its maiden name, oncosis. Cell dying from apoptosis (above) is only half the size of the swollen cell succumbing to oncosis (below). www.sciencenews.org /20010616/bob13.asp   (2107 words)

H. Robert Horvitz Naturally occurring, or programmed, cell death (apoptosis) is common during animal development, and abnormalities in programmed cell death are associated with many human diseases, including certain cancers and neurodegenerative disorders. We have characterized genes that cause cells to die, that protect cells from dying, that function in the engulfment of dying cells by their neighbors, and that are involved in destroying the debris generated by cell corpses. We are now analyzing genes that control how specific cells decide whether to live or die, and we have found that mammalian counterparts of such genes are involved in deafness and cancer. www.hhmi.org /research/investigators/horvitz.html   (1226 words)

Stem Cell Death Gives Clue to Brain Cell Survival   (Site not responding. Last check: 2007-11-01) Cells destined to survive, and likely further divide and differentiate, are handed instead a protein called nestin. It also makes sense that the lethal coupling that signals cell suicide, or apoptosis, comes at a point where the doomed cells seem to have lost their potential usefulness and where their continued survival would result in a malformed brain. They also are intrigued by where the work may lead, including helping minimize cell death that occurs when stem cells in the adult brain begin to once again divide in response to a stroke, as an example. www.mcg.edu /news/2003NewsRel/stemcell.html   (1089 words)

ScienceDaily: When 'Reaper' Gene Comes, Cell Death Follows Death of obsolete larval tissue is critical in insect metamorphosis. When DIAP1 is no longer functioning, cell death is unleashed in the salivary glands, leading to the destruction of larval tissue and their replacement by adult structures. In contrast to necrosis, which is a form of cell death that results from acute tissue injury and... www.sciencedaily.com /releases/2004/05/040518073233.htm   (1612 words)

Cellular Aging and Cell Death Cellular Aging and Cell Death provides a thorough understanding of the mechanisms responsible for cellular aging, covering the recent research on programmed cell death and senescence, and describing their role in the control of cell proliferation and the aging process. Leading experts contribute to give readers an authoritative overview of the distinct fields of cellular aging and programmed cell death, as well as to demonstrate how both fields are critical to understanding the aging process. Individual chapters discuss such topics as the role and regulation of apoptosis in development, the potential impact of cell death on such postmitotic tissues as nerve and muscle, and suggest that programmed cell death plays an important role in both pathological and nonpathological aspects of aging, including neurodegenerative diseases. www.ramex.com /jw/jw-cell03.html   (365 words)

2001 GRC on Cell Death Correct cell number is maintained by a balance of two physiological processes: cell division (mitosis) and cell death (apoptosis). Until 10 or so years ago the efforts of the scientific community were focused almost exclusively on analysis of the cell cycle, with cell death being overlooked. Commencing in 1965, John Kerr studied the process of shrinkage necrosis, which, with Andrew Wyllie and Alistair Currie, was renamed "apoptosis" in 1972 to distinguish this active process from necrosis. www.grc.org /programs/2001/celdeath.htm   (531 words)

hybrid vigor | the birth of death Common examples include the death of leaves in the autumn, the death of a tadpole's tail, and the death of cells in the developing human hand, causing separation of the fingers. Molecular pumps maintaining the cell membrane gradient (an ion concentration difference between the exterior and interior of the cell) shut down, and the membrane bursts, spilling the cell's contents into the surroundings. Clark writes, "...it is in the programmed death of the macronuclei of early eukaryotes like paramecia that our own corporeal deaths are foreshadowed." In multicellular organisms, the micronuclei and macronuclei have counterparts in our germ and somatic cells, respectively. www.students.emory.edu /HYBRIDVIGOR/death.htm   (1498 words)

HHMI News: Researchers Discover Cell Death Switch Scientists have learned a great deal about this orderly, programmed cell deathwhich is known to scientists as apoptosisbut the mechanisms that turn on the process have remained largely hidden from researchers. It may be possible, for example, to construct synthetic molecules that can act within cells to block or inhibit the cell death that occurs in heart and liver disease. "In cancer cells, where nitric oxide is overproduced, for example, we should be able to take out nitric oxide and promote cell death." One catch, Stamler added, is that scientists do not yet know how to remove NO from its position on the caspase enzyme. www.hhmi.org /news/stamler.html   (603 words)

Distinctions - May 2002 - Life and Death for the Cell   (Site not responding. Last check: 2007-11-01) Kenichi Fujise, M.D. Researchers at The University of Texas Health Science Center at Houston have identified a protein that may play a key role in regulation of the cell's life cycle, and also be involved in a wide range of diseases. An intricate network of proteins tightly controls the regulation of a cell's life cycle, and when that system is disrupted, dangerous overproduction of cells, as in cancers and atherosclerosis, or underproduction of cells, as in the degenerative diseases heart failure and multiple sclerosis, can occur in the body. Currently, his laboratory is applying what is known about fortilin's role as an apoptosis and cell cycle regulator to smooth muscle proliferation and atherosclerosis in particular. www.uthouston.edu /distinctions/archive/2002/may/life_death.html   (496 words)

Cell-Death Protein and Its Role in Neurodegeneration - Medgadget - www.medgadget.com Mitochondria are distributed throughout cells, including in the dendrites, and are important in maintaining the energy stores and regulating viability and death of the cell. The Elk-1 proteins translated in the dendrites were transported to the nucleus and cell death depended on subsequent transcription. Protein is also being made in the cell body, but there may be a difference in the Elk-1 protein made in the cell body. www.medgadget.com /archives/2006/06/celldeath_prote.html   (800 words)

CELL During the G2 phase, the cell again undergoes growth and protein sythesis (it needs enough proteins for 2 cells!)...priming it to be able to divide. It recognizes when something has gone wrong (for example the DNA has been damaged or the cell is being stimulated by an oncogene) and immediately halts the cell cycle to prevent the cell from becoming cancerous. Abundant heterochromatin is seen in resting, or reserve cells such as small lymphocytes (memory cells) waiting for exposure to a foreign antigen. www.angelfire.com /md/danil/celldeath/id26.htm   (2767 words)

Cell Death   (Site not responding. Last check: 2007-11-01) Molecular Cell Biology, 4th edition, W. Freeman and Co., pp. Cell death induced by the Fas/Fas ligandpathway and its role in pathology. Derived from H. Lodish, et al., Molecular Cell Biology text and CD-ROM, 4th edition, © 2000 W. Freeman and Co. and Sumanas, Inc. www.whfreeman.com /kuby/content/anm/kb04an01.htm   (113 words)

UT Southwestern researchers discover master switch in cell death The life and death of cells is a complex avalanche of reactions, controlled by a few molecules that sit atop a biochemical "pyramid." The beneficial side of cell death - known as apoptosis - occurs when it kills cells at appropriate times, as is the case, for example, when it removes the webbing from the fingers of an embryo or shapes a developing brain. Wang said that while there are many possible routes a cell may take toward apoptosis, this interaction serves as one of the "master switches" controlling whether or not those other pathways are triggered. www.utsouthwestern.edu /utsw/cda/dept37389/files/230609.html   (728 words)

Harvard Gazette: New route to cell death found These suicides and uncontrolled deaths have always been thought of as separate processes, comparable to killing one's self as opposed to dying by accident or malignancy. The team calls the new death pathway "necroptosis," a word that connects programmed cell death, or suicide, and unavoidable lethal breakdown. Yuan and her group have continued to work on this mystery, and in a telephone interview she said that they are very close to solving it. www.news.harvard.edu /gazette/daily/2005/06/30-celldeath.html   (939 words)

Nature Publishing Group Web Focus Cell Death and Immunity: Classics: CTL Killing The study of cell death dates back to the turn of the century, and many seminal findings over the years have shaped the course of this evolving and progressive field. With the generation of granzyme B knockout mice, this report established that this granzyme is indeed critical for the induction of rapid apoptotic cell death by cytotoxic cells. Using targets deficient in procaspase-3, this paper firmly established that granzyme B initiates apoptosis by recapitulating the action of the apical caspases and emphasizes that processing of intracellular substrates depends on both accessibility and reactivity of the substrate. www.nature.com /focus/celldeathimm/classics/ctl_killing.html   (743 words)

Cell Death   (Site not responding. Last check: 2007-11-01) Some cells have very short lifespans because their jobs are completed quickly, (disease-fighting cells in the human blood stream are an example) but others just seem to "wear out." A part of this "wearing out" results from MITOSIS. Human cells can only divide (go through mitosis) about 50 times. This is called the "Hayflick Limit." Eventually the DNA is no longer able to divide, so the cell dies, so the tissue cannot repair itself and dies, so the organism dies. www.geo.arizona.edu /Antevs/nats104/celldeath.html   (105 words)

Streptococci That Kill White Blood Cells Although a neutrophil can kill this bead-like string of Streptococcus pyogenes, this particular strain of bacteria expresses streptolysin-s on its surface which causes the white cell to self-destruct. The white cell's lytic granules, which are supposed to fire their antibacterial contents onto the bacteria, are emptied into the white cell's cytoplasm instead, leading eventually to cell membrane lysis. This clip may be purchased for classroom use as one of seven clips in the "Immune System Collection". www.cellsalive.com /strep.htm   (100 words)

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