globulin

globulin (glob´yu-lin)

Name for a family of proteins precipitated from plasma (or serum) by half-saturation with ammonium sulfate (i.e., addition of an equal volume of saturated ammonium sulfate). G.'s may be further fractionated by solubility, electrophoresis, ultracentrifugation, and other separation methods into many subgroups, the main groups being a-, beta-, and gamma-g.; these differ with respect to associated lipids or carbohydrates and in their content of many physiologically important factors. Among the latter are immunoglobulins (antibodies) in the beta and gamma fractions, lipoproteins in the a and beta fractions, gluco- or mucoproteins (orosomucoid, haptoglobin), and metal-binding and metal-transporting proteins (transferrin, siderophilin, ceruloplasmin). Other substances found in g. fractions are: macroglobulin, plasminogen, prothrombin, euglobulin, antihemophilic g., fibrinogen, cryoglobulin. [L. globulus, globule]
accelerator g. (AcG, ac-g) [MIM*227300] g. in serum that promotes the conversion of prothrombin to thrombin in the presence of thromboplastin and ionized calcium. See factor Va, factor V, serum accelerator g.
antihemophilic g. (AHG) 1. factor VIII 2. human antihemophilic factor
antihemophilic g. A factor VIII
antihemophilic g. B factor IX
antihuman g. serum from a rabbit or other animal previously immunized with purified human g. to prepare antibodies directed against IgG and complement; used in the direct and indirect Coombs' tests.Coombs' serum;
antilymphocyte g. (ALG) antilymphocyte serum
beta1C g. the third component (C3) of complement. See component of complement.
beta1E g. the fourth component (C4) of complement. See component of complement.
beta1F g. the fifth component (C5) of complement. See component of complement.
chickenpox immune g. (human) g. fraction of serum from persons recently recovered from herpes zoster infection; used to prevent infection of high-risk children.chickenpox immunoglobulin;
corticosteroid-binding g. (CBG) transcortin
gonadal steroid-binding g. (GBG) a protein that transports 65% of the testosterone in plasma.sex steroid-binding g;
human gamma g. a preparation of the proteins of liquid human plasma, containing the antibodies of normal adults; it is obtained from pooled liquid human plasma from a number of donors and may be prepared by precipitation with organic solvents under controlled conditions of pH, ionic strength, and temperature.human normal immunoglobulin;
immune serum g. a sterile solution of g.'s that contains many antibodies normally present in adult human blood; a passive immunizing agent frequently used for prophylaxis against hepatitis A.
measles immune g. (human) a sterile solution of g.'s derived from the blood plasma of normal adult human donors; it is prepared from immune serum g. that complies with the measles antibody reference standard; a passive immunizing agent.measles immunoglobulin;
pertussis immune g. a sterile solution of g.'s derived from the plasma of adult human donors who have been immunized with pertussis vaccine; used both prophylactically and therapeutically.pertussis immunoglobulin;
plasma accelerator g. factor V
poliomyelitis immune g. (human) a sterile solution of g.'s that contains those antibodies normally present in adult human blood; it is a passive immunologic agent that attenuates or prevents poliomyelitis, measles, and infectious hepatitis, and confers temporary but significant protection against paralytic polio.poliomyelitis immunoglobulin;
rabies immune g. (human) g. fraction of pooled plasma of high anti-rabies virus titer from immunized persons.rabies immunoglobulin;
RHo(D) immune g. a g. fraction of antibody, derived from human donors, specific for the most common antigen, Rho(D), of the Rh group; used to prevent Rh-sensitization of an Rh-negative woman after delivery of an Rh-positive fetus.anti-D immunoglobulin, Rho(D) immunoglobulin;
serum accelerator g. a substance in serum that accelerates the conversion of prothrombin to thrombin in the presence of thromboplastin and calcium; produced by the action of traces of thrombin upon plasma accelerator g.
sex hormone-binding g. (SHBG) a plasma beta-g., produced by the liver, that binds testosterone and, with a weaker affinity, estrogen; serum levels of SHBG in women are twice the levels seen in men; serum concentrations are increased in certain types of liver disease and in hyperthyroidism; are decreased with advancing age, by androgens, and in hypothyroidism.testosterone-estrogen-binding g;
sex steroid-binding g. gonadal steroid-binding g
specific immune g. (human) g. fraction of pooled serums (or plasma) selected for high titer of antibodies specific for a particular antigen, or from persons specifically immunized.
testosterone-estrogen-binding g. sex hormone-binding g
tetanus immune g. a sterile solution of g.'s derived from the blood plasma of adult human donors who have been immunized with tetanus toxoid; a passive immunizing agent.tetanus immunoglobulin;
thyroxine-binding g. (TBG) an a-globulin of blood with a strong binding affinity for thyroxine; triiodothyronine is bound to it much less firmly; a deficiency or excess of this protein may occur as a rare benign X-linked disorder.thyroxine-binding protein (1) ;
zoster immune g. a g. fraction of pooled plasma from individuals who have recovered from herpes zoster; used prophylactically and therapeutically for varicella.

 

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