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Clonal Selection Theory
In immunology, clonal selection theory explains the functions of cells of the immune system (lymphocytes) in response to specific antigens invading the body. The concept was introduced by Australian doctor Frank Macfarlane Burnet in 1957, in an attempt to explain the great diversity of antibodies formed during initiation of the immune response. The theory has become the widely accepted model for how the human immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens. The theory states that in a pre-existing group of lymphocytes (specifically B cells), a specific antigen activates (i.e. selects) only its counter-specific cell, which then induces that particular cell to multiply, producing identical clones for antibody production. This activation occurs in secondary lymphoid organs such as the spleen and the lymph nodes. In short, the theory is an explanation of the mechanism for the generation of diversity o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clonal Selection
In immunology, clonal selection theory explains the functions of cells of the immune system (lymphocytes) in response to specific antigens invading the body. The concept was introduced by Australian doctor Frank Macfarlane Burnet in 1957, in an attempt to explain the great diversity of antibodies formed during initiation of the immune response. The theory has become the widely accepted model for how the human immune system responds to infection and how certain types of B and T lymphocytes are selected for destruction of specific antigens. The theory states that in a pre-existing group of lymphocytes (specifically B cells), a specific antigen activates (i.e. selects) only its counter-specific cell, which then induces that particular cell to multiply, producing identical clones for antibody production. This activation occurs in secondary lymphoid organs such as the spleen and the lymph nodes. In short, the theory is an explanation of the mechanism for the generation of diversity o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
V(D)J Recombination
V(D)J recombination is the mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. It results in the highly diverse repertoire of antibodies/immunoglobulins and T cell receptors (TCRs) found in B cells and T cells, respectively. The process is a defining feature of the adaptive immune system. V(D)J recombination in mammals occurs in the primary lymphoid organs (bone marrow for B cells and thymus for T cells) and in a nearly random fashion rearranges variable (V), joining (J), and in some cases, diversity (D) gene segments. The process ultimately results in novel amino acid sequences in the antigen-binding regions of immunoglobulins and TCRs that allow for the recognition of antigens from nearly all pathogens including bacteria, viruses, parasites, and worms as well as "altered self cells" as seen in cancer. The recognition can also be allergic in nature (''e.g.'' to pollen or other allergens) or may match ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunological Tolerance
Immune tolerance, or immunological tolerance, or immunotolerance, is a state of unresponsiveness of the immune system to substances or tissue that would otherwise have the capacity to elicit an immune response in a given organism. It is induced by prior exposure to that specific antigen and contrasts with conventional immune-mediated elimination of foreign antigens (see Immune response). Tolerance is classified into central tolerance or peripheral tolerance depending on where the state is originally induced—in the thymus and bone marrow (central) or in other tissues and lymph nodes (peripheral). The mechanisms by which these forms of tolerance are established are distinct, but the resulting effect is similar. Immune tolerance is important for normal physiology. Central tolerance is the main way the immune system learns to discriminate self from non-self. Peripheral tolerance is key to preventing over-reactivity of the immune system to various environmental entities (allergens, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Medawar
Sir Peter Brian Medawar (; 28 February 1915 – 2 October 1987) was a Brazilian-British biologist and writer, whose works on graft rejection and the discovery of acquired immune tolerance have been fundamental to the medical practice of tissue and organ transplants. For his scientific works, he is regarded as the "father of transplantation". He is remembered for his wit both in person and in popular writings. Famous zoologists such as Richard Dawkins referred to him as "the wittiest of all scientific writers", and Stephen Jay Gould as "the cleverest man I have ever known". Medawar was the youngest child of a Lebanese father and a British mother, and was both a Brazilian and British citizen by birth. He studied at Marlborough College and Magdalen College, Oxford, and was professor of zoology at the University of Birmingham and University College London. Until he was partially disabled by a cerebral infarction, he was Director of the National Institute for Medical Research at M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globulin
The globulins are a family of globular proteins that have higher molecular weights than albumins and are insoluble in pure water but dissolve in dilute salt solutions. Some globulins are produced in the liver, while others are made by the immune system. Globulins, albumins, and fibrinogen are the major blood proteins. The normal concentration of globulins in human blood is about 2.6-3.5 g/dL. The term "globulin" is sometimes used synonymously with "globular protein". However, albumins are also globular proteins, but are ''not'' globulins. All other serum globular proteins are globulins. Types of globulins All globulins fall into one of the following three categories : * Alpha globulins * Beta globulins * Gamma globulins (one group of gamma globulins is the immunoglobulins, which are also known as "antibodies") Globulins can be distinguished from one another using serum protein electrophoresis. Globulins exert oncotic pressure. Their deficiency results in loss of carrier fun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antigenic Determinant
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds. The part of an antibody that binds to the epitope is called a paratope. Although epitopes are usually non-self proteins, sequences derived from the host that can be recognized (as in the case of autoimmune diseases) are also epitopes. The epitopes of protein antigens are divided into two categories, conformational epitopes and linear epitopes, based on their structure and interaction with the paratope. Conformational and linear epitopes interact with the paratope based on the 3-D conformation adopted by the epitope, which is determined by the surface features of the involved epitope residues and the shape or tertiary structure of other segments of the antigen. A conformational epitope is formed by the 3-D conformation adopted by the interac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Immunological Memory
Immunological memory is the ability of the immune system to quickly and specifically recognize an antigen that the body has previously encountered and initiate a corresponding immune response. Generally, these are secondary, tertiary and other subsequent immune responses to the same antigen. The adaptive immune system and antigen-specific receptor generation ( TCR, antibodies) are responsible for adaptive immune memory. After the inflammatory immune response to danger-associated antigen, some of the antigen-specific T cells and B cells persist in the body and become long-living memory T and B cells. After the second encounter with the same antigen, they recognize the antigen and mount a faster and more robust response. Immunological memory is the basis of vaccination.Hammarlund, Erika, et al. (2003). "Duration of antiviral immunity after smallpox vaccination." Nature medicine 9.9, 1131. Emerging resources show that even the innate immune system can initiate a more efficient immune ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
David W
David (; , "beloved one") (traditional spelling), , ''Dāwūd''; grc-koi, Δαυΐδ, Dauíd; la, Davidus, David; gez , ዳዊት, ''Dawit''; xcl, Դաւիթ, ''Dawitʿ''; cu, Давíдъ, ''Davidŭ''; possibly meaning "beloved one". was, according to the Hebrew Bible, the third king of the United Kingdom of Israel. In the Books of Samuel, he is described as a young shepherd and harpist who gains fame by slaying Goliath, a champion of the Philistines, in southern Canaan. David becomes a favourite of Saul, the first king of Israel; he also forges a notably close friendship with Jonathan, a son of Saul. However, under the paranoia that David is seeking to usurp the throne, Saul attempts to kill David, forcing the latter to go into hiding and effectively operate as a fugitive for several years. After Saul and Jonathan are both killed in battle against the Philistines, a 30-year-old David is anointed king over all of Israel and Judah. Following his rise to power, David ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phagocytosis
Phagocytosis () is the process by which a cell uses its plasma membrane to engulf a large particle (≥ 0.5 μm), giving rise to an internal compartment called the phagosome. It is one type of endocytosis. A cell that performs phagocytosis is called a phagocyte. In a multicellular organism's immune system, phagocytosis is a major mechanism used to remove pathogens and cell debris. The ingested material is then digested in the phagosome. Bacteria, dead tissue cells, and small mineral particles are all examples of objects that may be phagocytized. Some protozoa use phagocytosis as means to obtain nutrients. History Phagocytosis was first noted by Canadian physician William Osler (1876), and later studied and named by Élie Metchnikoff (1880, 1883). In immune system Phagocytosis is one main mechanisms of the innate immune defense. It is one of the first processes responding to infection, and is also one of the initiating branches of an adaptive immune response. Although mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Serum
Serum () is the fluid and solute component of blood which does not play a role in clotting. It may be defined as blood plasma without the clotting factors, or as blood with all cells and clotting factors removed. Serum includes all proteins not used in blood clotting; all electrolytes, antibodies, antigens, hormones; and any exogenous substances (e.g., drugs or microorganisms). Serum does not contain white blood cells (leukocytes), red blood cells (erythrocytes), platelets, or clotting factors. The study of serum is serology. Serum is used in numerous diagnostic tests as well as blood typing. Measuring the concentration of various molecules can be useful for many applications, such as determining the therapeutic index of a drug candidate in a clinical trial. To obtain serum, a blood sample is allowed to clot (coagulation). The sample is then centrifuged to remove the clot and blood cells, and the resulting liquid supernatant is serum. Clinical and laboratory uses The serum of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Niels Jerne
Niels is a male given name, equivalent to Nicholas, which is common in Denmark, Belgium, Norway (formerly) and the Netherlands. The Norwegian and Swedish variant is Nils. The name is a developed short form of Nicholas or Greek Nicolaos after Saint Nicholas. Its pet form is Nisse, and female variants are Nielsine, Nielsina, and Nielsa. Niels may refer to: People *Niels, King of Denmark (1065–1134) *Niels, Count of Halland (died 1218) * Niels Aagaard (1612–1657), Danish poet *Niels Aall (1769–1854), Norwegian businessman and politician *Niels Henrik Abel (1802–1829), Norwegian mathematician *Niels Arestrup (born 1949), French actor *Niels Viggo Bentzon (1919–2000), Danish composer and pianist *Niels Bohr (1885–1962), Danish physicist and Nobel Prize recipient *Niels Busk (born 1942), Danish politician *Niels Ebbesen (died 1340), Danish squire and national hero *Niels Feijen (born 1977), Dutch pool player * Niels Ferguson (born 1965), Dutch cryptographer *Niels Friis (d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Side Chain
In organic chemistry and biochemistry, a side chain is a chemical group that is attached to a core part of the molecule called the "main chain" or backbone. The side chain is a hydrocarbon branching element of a molecule that is attached to a larger hydrocarbon backbone. It is one factor in determining a molecule's properties and reactivity. A side chain is also known as a pendant chain, but a pendant group (side group) has a different definition. Conventions The placeholder R is often used as a generic placeholder for alkyl (saturated hydrocarbon) group side chains in chemical structure diagrams. To indicate other non-carbon groups in structure diagrams, X, Y, or Z are often used. History The ''R'' symbol was introduced by 19th-century French chemist Charles Frédéric Gerhardt, who advocated its adoption on the grounds that it would be widely recognizable and intelligible given its correspondence in multiple European languages to the initial letter of "root" or "residue": ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
