Tissue Typing: From 3 Different Sources
The classification of certain characteristics of the tissues of prospective organ donors and recipients (see transplant surgery). This minimizes the risk of rejection of a donor organ by the recipient’s immune system.
A person’s tissue type is classified in terms of their histocompatibility antigens, the most important of which are the human leukocyte antigens (HLAs), on the surface of cells. A person’s set of HLAs is inherited and unique (except for identical twins, who have the same set). Nevertheless, close relatives often have closely matching types. A person’s tissue-type is established by laboratory tests on cells from a blood sample. In one method, an antiserum containing antibodies to a particular is added to the test specimen. If the is present, it is detected by an observable colour or other change.
The essential procedure for matching the tissue of a recipient in need of transplanted tissue or organ to that of a potential donor. Unless there is a reasonable match, the recipient’s immune system (see IMMUNITY) will reject the donor’s organ. The main factors that are relevant to an individual’s reaction to donor tissue are called histocompatability antigens (see ANTIGEN). These are mostly human leucocyte antigens (HLAs – see HLA SYSTEM) present on the surface of cells. HLAs are inherited and, like ?ngerprints, unique to an individual, although identical twins have identical HLAs and hence are perfect matches for TRANSPLANTATION procedures.
determination of the *HLA profiles of tissues to assess their compatibility. It is the most important predictor of success or failure of a transplant operation.
Sometimes called ?brous tissue, this is one of the most abundant tissues in the body, holding together the body’s many di?erent structures. Connective tissue comprises a matrix of substances called mucopolysaccharides in which are embedded various specialist tissues and cells. These include elastic (yellow), collagenous (white) and reticular ?bres as well as macrophages (see MACROPHAGE) and MAST CELLS. Assembled in di?ering proportions, this provides structures with varying functions: bone, cartilage, tendons, ligaments and fatty and elastic tissues. Collagenous connective tissue binds the muscles together and provides the substance of skin. It is also laid down in wound repair, forming the scar tissue. Contracting with time, connective tissue becomes denser, causing the puckering that is typical in serious wounds or burns. (See ADHESION; SCAR; WOUNDS.)... connective tissue
Adipose tissue, or fat, is a loose variety of ?brous tissue in the meshes of which lie cells, each of which is distended by several small drops, or one large drop, of fat. This tissue replaces ?brous tissue when the amount of food taken is in excess of the bodily requirements. Adipose tissue occurs as a layer beneath the skin and also around several internal organs. (See DIET; FAT; OBESITY.)... adipose tissue
A collection of cells similar in structure or function.... tissue
CONNECTIVE TISSUE which contains a profusion of yellow elastic ?bres. Long, slender and branching, these ?bres (made up of elastin, an albumin-like PROTEIN) ensure that the elastic tissue is ?exible and stretchable. The dermis layer of the skin, arterial walls and the alveolar walls in the LUNGS all contain elastic tissue.... elastic tissue
Tissue involved in the formation of LYMPH, lymphocytes (see LYMPHOCYTE), and ANTIBODIES. It consists of the LYMPH NODES, THYMUS GLAND, TONSILS and SPLEEN.... lymphoid tissue
A group of generalised in?ammatory diseases that affect CONNECTIVE TISSUE in almost any system in the body. The term does not include those disorders of genetic origin. RHEUMATIC FEVER and RHEUMATOID ARTHRITIS were traditionally classi?ed in this group, as were those diseases classed under the outdated heading COLLAGEN DISEASES.... connective tissue disorders
See CONNECTIVE TISSUE.... fibrous tissue
A surgical dressing composed of a thick layer of cotton-wool between two layers of absorbent gauze, introduced by the Birmingham surgeon, Sampson Gamgee (1828–1886). Gamgee tissue has been a registered trademark since 1911.... gamgee tissue
A natural PROTEIN that occurs in the body. It has the property of breaking down a THROMBUS in a blood vessel (see THROMBOLYSIS). It is e?ective only in the presence of FIBRIN and activates plasminogen, which occurs normally on the surface of the ?brin. TPA is an important thrombolytic treatment immediately after a myocardial infarction (see HEART, DISEASES OF).... tissue plasminogen activator (tpa, tpa)
Types of autoimmune disorders that often affect blood vessels and produce secondary connective tissue damage. They include rheumatoid arthritis, systemic lupus erythematosus, polyarteritis nodosa, scleroderma, and dermatomyositis.... connective tissue diseases
A mass of red, moist, granular tissue that develops on the surface of an ulcer or open wound during the process of healing.... granulation tissue
Damage to the tissues (see ligament; tendon; muscle) that surround bones and joints.... soft-tissue injury
The watery liquid present in the tiny gaps between body cells, also known as interstitial fluid.... tissue fluid
A substance produced by body tissues that prevents abnormal blood clotting. Also called , it is produced by the inner lining of blood vessels. can be prepared artificially for use as a thrombolytic drug, which is called alteplase. This is used in the treatment of myocardial infarction, severe angina pectoris, and arterial embolism, including pulmonary embolism. Possible side effects include bleeding or the formation of a haematoma at the injection site and an allergic reaction. (See also fibrinolysis.)... tissue-plasminogen activator
loose *connective tissue consisting of a meshwork of collagen, elastic tissue, and reticular fibres interspersed with numerous connective tissue cells. It binds the skin to underlying muscles and forms a link between organs while allowing a high degree of relative movement.... areolar tissue
a collection of specialized cells that transmits electricity within the heart. It may be normal (e.g. the *sinoatrial node) or abnormal (e.g. an *accessory pathway).... conducting tissue
any one of a group of diseases that are characterized by inflammatory changes in connective tissue and can affect virtually any body system. Formerly known as collagen diseases (connective-tissue disease has been the preferred term since 1978), they include *dermatomyositis, systemic and discoid *lupus erythematosus, *morphoea, *polyarteritis nodosa, and *rheumatoid arthritis.... connective-tissue disease
the UK government agency, established by the Human Tissue Act 2004, that regulates the removal, use, and storage of human organs and tissue from both the living and the deceased for certain purposes as defined by the statute. These purposes include clinical research, clinical audit, and medical education. Anyone handling such material for those purposes should have a licence issued by the authority. Membership of the authority comprises clinical, scientific, academic, and lay representatives.... human tissue authority
a disease with features in common with systemic *lupus erythematosus, *polymyositis, and *scleroderma. It is characterized by high levels of antibodies to ribonucleoprotein and most commonly affects women between 20 and 40 years of age.... mixed connective tissue disease
a tissue in the *bone marrow in which the various classes of blood cells are produced. See also haemopoiesis.... myeloid tissue
the culture of living tissues, removed from the body, in a suitable medium supplied with nutrients and oxygen. Tissue engineering, in which skin, cartilage, and other connective-tissue cells are cultured on a *fibronectin ‘mat’ to create new tissues, is being explored for use in tissue grafting for patients with burns, sports injuries, etc.... tissue culture
(tPA, TPA) a natural protein, found in the body and able to be manufactured by genetic engineering, that can break up a thrombus (see thrombolysis). It requires the presence of *fibrin as a cofactor and is able to activate *plasminogen on the fibrin surface, which distinguishes it from the other plasminogen activators, *streptokinase and *urokinase. tPAs include reteplase and tenecteplase, given to treat acute myocardial infarction, and *alteplase.... tissue-type plasminogen activator
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