F. Fraser. Gardner-Webb University.
Thrombin time detects the effectiveness of the final into joints) leading to severe crippling hemarthropathy stage of coagulation in which fibrinogen is converted are highly characteristic of the disease order sildigra master card erectile dysfunction pump. As platelet factor 3 acts as a cofactor for Diagnosis coagulation buy sildigra in india erectile dysfunction drugs over the counter, clotting occurs in less time in platelet rich plasma than in platelet poor plasma purchase sildigra 100 mg erectile dysfunction typical age. Clinical Features Mucocutaneous bleeding is the most commonest pre- Features sentation in type 1. Epistaxis, easy bruising, hematoma, the disease is clinically indistinguishable from hemophilia A. In type 3, Bleeding episodes are clinically identical to those in hemo- patients suffer from severe bleeding and present with philia A. This is also called consump- Willebrand described this bleeding disorder in both gen- tion coagulopathy or defibrination syndrome. Amniotic fluid embolism Treatment is based on early diagnosis, elimination of the 3. Gram-negative septicemia precipitating factors, and replacing coagulation factors 4. Normally, a balance is maintained between the processes of coagulation and Manifestations anticoagulation and therefore thrombus is not formed. Three factors (Virchow’s triad) predispose to the features: formation of thrombosis. Endothelial injury: Injury to vascular endothelium embolism occurs in chronic and sustained hypertension, ulcer- 2. Bleeding caused by consumption of platelets, fibrino- ated atherosclerosis, arterial diseases etc. Sluggishness of blood flow: Stasis of blood promotes (hence, called defibrination syndrome). Hpercoagulability of blood: Increased activity of pro- Diagnosis coagulants such as fibrinogen, prothrombin and other Laboratory features include thrombocytopenia, hypofi- coagulants leads to thrombosis. One common example is thrombosis of lower limb organs, such as brain (cerebral embolism), lungs (pul- veins in varicosities. Thrombosis also occurs in cardiac chambers and valve thrombosis leads to ischemic tissue death (infarction), leaflets. Pro- the major complication of thrombosis is thrombo- phylactic anticoagulation and antiplatelet therapy is embolism. Emboli are dislodged from thrombus and the mainstay of prevention of complications of throm- circulate to be lodged in microcirculation in visceral bosis. In the second stage, prothrombin is converted to thrombin, and thrombin converts fibrinogen to fibrin in the third stage. Fibrinolysis is initiated by plasmin that checks the spread of clot beyond the site of injury. In examinations, ‘Mechanism of blood coagulation’ usually comes as a Long Question. In Viva, examiners may ask… name the clotting factors, stages of blood clotting, steps of intrinsic and extrinsic pathways of clotting, clot retraction and its importance, mechanism of fibrinolysis, mechanism of action of Vitamin K antagonist, anticoagulants and their mechanisms, tests to detect defects in extrinsic and intrinsic mechanisms of clotting, and causes, features and treatment of common coagulation disorders. Anticoagulants are frequently asked for as they are commonly used in clinical as well as laboratory practices. Properties, Classification and Applied Aspects of Nerve Fibers Part B: Neuromuscular Junction 25. A God-given might of being in their force, A ray from self’s solitude of light the guide; the soul that can live alone with itself meets God. Its primary function is to receive the various stimuli and transmit the signals to other neurons and tissues. The neuron is an excitable cell where message transmission occurs in the form of action potentials. There are also supporting cells called glial cells, which are 10 to 30 times more in number than the neural cells. Santiago Ramón y Cajal “in recognition of their work on the structure of the neuron and the nervous system”. Axon is a single long thin pro- Dendrites are multiple, short, cess of nerve cell which ter- thick and tapering processes of minates away from the nerve the nerve cell which terminate cell body near the nerve cell 2. Dendrites Cell Body the numerous short extensions from the cell body are called dendrites. It contains the nucleus and cytoplasm drites have dendritic spines, that help in increasing containing cell organelles. Dendrites receive the incoming signals from other Cell organelles are mainly numerous Nissl granules, many cells and transmit it to the cell body. At some areas of the brain, they can cause protein syn- also contains cytoskeletal proteins like neurofilaments, thesis, also generate and conduct the action potentials. It is a long tubular process that extends away from ture of neurons is the presence of networks of fibrils the cell body to transmit output signals to target organs. These neurofibrils consist Dendrites transmit impulses toward cell body, whereas of microfilaments and microtubules. The axon arises from a thickened, tapered area of the Nucleus cell body called the axon hillock. The initial portion of the axon is known as the initial there may be two nucleoli, but centrioles are absent. The axon hillock continues as initial segment and this Functions of Soma part is known as axon hillock—initial segment portion 1. The action potential is generated at the initial segment has lost the capacity to regenerate as indicated by the in motor neurons and at the first node of Ranvier in absence of centriole. The soma at one end gives rise to small branching pro- Axon terminal: the terminal part of axon loses mye- cesses called dendrites and at the other end a long lin and divides into several branches, called telodendria. The endings of telodendria form bulb like enlargements Chapter 22: Structure and Functions of Neurons 217 A B Figs. In multiple sclerosis, an autoimmune disease, patchy contain neurotransmitter vesicles. The nature of this sheath is axons have a sheath around, called myelin sheath (Figs. An axon lying near a Schwann cell invaginates into the the large diameter somatic nerve fibers as well as the cytoplasm of Schwann cell. In this process the axon preganglionic fibers of the autonomic nervous system comes to be suspended by a fold of the cell membrane are myelinated. In some situations the mesaxon becomes greatly elon- eral processes that wrap around many axons. Lipids are deposited between adjacent the double layers of the membrane of a single Schwann layers of the membrane.
Effector chains each contribute three hypervariable regions to the function generally results in removal of antigen from the antigen binding region of the antibody molecule order sildigra no prescription erectile dysfunction treatment can herbal remedies help. There is only minor variability in the amino acid con- region provides considerable fexibility to this area order sildigra 50mg amex erectile dysfunction caused by hydrochlorothiazide, which tent of constant domains cheap 50mg sildigra otc erectile dysfunction oil treatment. A globular compact structure that enables the Fab region of an immunoglobulin molecule to consists of two antiparallel twisted β sheets. There are differ- combine with cell surface epitopes that it might not otherwise ences in the number and the irregularity of the β strands and reach. Fab regions of an Ig molecule can rotate on the hinge bilayers in variable (V) and constant (C) subunits of immu- region. In addition to the proline resi- resembles that of the domains, which are comprised of a fve- dues, there may be one or several half cysteines associated strand β sheet and a four-strand β sheet packed facing one with the interchain disulfde bonds. However, the C domain does not have a hairpin loop or pepsin occurs near the hinge region. Thus, the C domain has seven chains each contain a hinge region, μ and ε chains do not. Constant region is that part of an immunoglobulin polypep- Homology unit: A structural feature of an immunoglobulin tide chain that has an invariant amino acid sequence among domain. A few exons encode are the areas for specifc antigen binding, and they also the constant region of an immunoglobulin heavy chain, and determine the idiotype of an immunoglobulin molecule. The one exon encodes the constant region of an immunoglobulin remaining background support structures of the heavy and light chain. It is associated the κ and λ light chain hot spots are situated near amino acid with a number of antibody functions. Digestion of IgG molecules with2 a particular specifcity without inducing an immune response papain yields two Fab and one Fc fragments. L chains have a single vari- able and constant domain, whereas H chains possess one A humanized antibody is an engineered antibody pro- variable and three to four constant domains. A human- is found in body secretions such as saliva, milk, and intes- ized antibody contains the antigen-binding specifcity of an tinal and bronchial secretions. IgD and IgM are present as antibody developed in a mouse, whereas the remainder of membrane-bound immunoglobulins on B cells, where they the molecule is of human origin. IgE, associated variable genes that encode the antigen-binding regions of a with anaphylaxis and IgG, which is the only immunoglobu- mouse antibody are transferred to the normal human gene lin capable of crossing the placenta, is the major human which encodes an immunoglobulin molecule that is mostly immunoglobulin. An immunoglobulin monomer is the basic unit of immu- noglobulin, comprised of two heavy chains and two light An immunoglobulin is a mature B cell product synthe- chains. Antibody molecules are immunoglobulins of defned specifcity pro- the homology region is a 105- to 115-amino acid residue duced by plasma cells. The immunoglobulin molecule con- sequence of heavy or light chains of immunoglobulins which sists of heavy (H) and light (L) chains fastened together have a primary structure that resembles other correspond- by disulfde bonds. A homology region has a classes and subclasses based on the antigenic specifcity globular shape and an intrachain disulfde bond. Heavy chains are designated by lower that encode homology regions are separated by introns. IgG, IgD, and IgE have two H Reagin (historical): (1) Obsolete term for a complement- and two L polypeptide chains, whereas IgM and IgA con- fxing IgM antibody reacting in the Wassermann test for sists of multimers of this basic chain structure. The basic monomeric unit is Y shaped, with a the Fcε receptors on tissue mast cells leading to release of hinge region rich in proline and susceptible to cleavage by histamine and vasoactive amines following interaction with proteolytic enzymes. Approximately 60% of human immunoglobulin antibody to the antibody heavy chain variable sequence. The fve immunoglobulin classes are termed isotypes They are smaller and less immunogenic than the intact based on the heavy-chain specifcity of each immuno- heavy chains with immunogenic constant regions. Two immunoglobulin classes, IgA and IgG, many possible uses are in imaging and treatment of cancer, have been further subdivided into subclasses based on H in cardiovascular disease, as biosensors, and for chemical chain differences. However, in certain disease states, and light chain variable regions fastened together by a fex- such as demyelinating diseases and infections of the central ible linker. This structure is present in membrane- sible to derive information about deviation from normal. Whereas tail peptides of 20 comparative method is called Ig quotient and is calculated in amino acids each are present in IgM and IgA molecules that various ways: have been secreted, IgG and IgE molecules do not contain tail peptides. Such antibodies patients with local immunoglobulin production show a may confer protective immunity. The heavy chain is comprised of three to four constant domains, depending on class, and one vari- Immunoglobulin function is to link an antigen to its able domain. In addition, a hinge region is present in some elimination mechanism (effector system). There is approximately 30% homology with respect complement activation and cellular elimination mechanisms to amino acid sequence among the fve classes of immuno- that include phagocytosis and antibody-dependent cell- globulin heavy chain in humans. This type of activation usually is μ, of IgG is γ, of IgA is α, of IgD is δ, and of IgE is ε. A requires antibody molecules clustered together on a cell heavy chain is a principal constituent of immunoglobulin surface rather than as free unliganded antibody. Antibodies can combine with virus particles to render them noninfectious in vitro through neutralization. All immunoglobulin classes can be expressed on B cell surfaces where they act as antigen Light chain receptors although this is mainly a function of IgM and IgD. Surface immunoglobulin has an extra C-terminal sequence compared to secreted immunoglobulin containing linker, transmembrane, and cytoplasmic segments. The amount present is dependent on the immunoglobulin concentration in the serum, the molecular size of the immunoglobulin, and the permeability of the blood–brain barrier. Each immunoglobulin is comprised of at least one four-polypeptide chain monomer which consists of two heavy and two light polypeptide chains. The two heavy L chain chains are identical in any one molecule as are the two light chains. A heavy chain is an immunoglobulin polypeptide chain that designates the class of immunoglobulin. The fve immunoglobulin classes are based on the heavy chains they possess and are IgM, IgG, IgA, IgD, and IgE. Heavy-chain antigenic determi- region or constant terminal reveals no variation except for nants determine not only the immunoglobulin class but the the Km and Oz allotype markers in humans. Heavy chain class refers to the immunoglobulin heavy polypeptide chain primary (antigenic) structure present κ chain is one of two types of light polypeptide chains in all members of a species that is different from the other present in immunoglobulin molecules of human and other heavy chain classes. Lowercase Greek letters such as μ, γ, α, δ, and ε in approximately 40% of human immunoglobulin molecules. A single immunoglobulin molecule contains either κ or λ light chains, not one of each. Each immunoglobulin is comprised of at Light chain type is a term for the classifcation of immu- least one four-polypeptide chain monomer, which consists of noglobulin light chains based on their primary or antigenic two heavy and two light polypeptide chains. Two types of light chains have been described and chains are identical in any one molecule as are the two light are designated as κ and λ.
The dibasic nitrogen-rich amino acid arginine has a marked Therapeutic antisera cheap sildigra 120mg with visa erectile dysfunction treatment options uk, such as horse antitoxin against diph- immunomodulatory function buy sildigra 100mg line impotence prozac. It is critical for the main- theria discount sildigra online mastercard erectile dysfunction 18 years old, were widely used earlier in the 20th century. A few tenance of nitrogen balance and physiologic functions in specifc antisera such as tetanus antitoxin are still used. Supplemental administration of arginine in experi- mental animals has led to increased thymic size, lymphocyte Tetanus antitoxin: Antibody raised by immunizing horses count, and a lymphocyte mitogenic response to mitogens against Clostridium tetani exotoxin. It protects to treat or prevent tetanus in individuals with contaminated against posttraumatic thymic involution and the impairment lesions. It enhances delayed hypersensitivity reac- tivity) may occur in individuals receiving second injections tions in animal studies and also promotes host antitumor because of sensitization to horse serum proteins following ini- responses. Arginine is essential for the function of various tial exposure to horse antitoxin. One solution to this has been immunoregulatory proteins that include thymosin, thymo- the use of human antitetanus toxin of high titer. Arginine has a powerful effect on numer- of the IgG fraction yields F(ab2) fragments which retain all of ous cells and molecules of the immune system and may have the toxin-neutralizing capacity but with diminished antige- future potential as a pharmacologic agent in the treatment of nicity of the antitoxin preparation. Diphtheria antitoxin is an antibody generated by the Serotherapy is a form of treatment for an infectious disease hyperimmunization of horses against Corynebacterium developed almost a century ago in which antiserum raised diphtheriae exotoxin with injections of diphtheria toxoid by immunizing horses or other animals against exotoxin, and diphtheria toxins. When used earlier in the 20th cen- such as that produced by Corynebacterium diphtheriae, was tury to treat children with diphtheria, many of the recipients administered to children with diphtheria. Thus, serotherapy immunization to treat diphtheria or for short-term protection was intended for prevention and treatment. Presently, pepsin digestion of the serum globulin fraction of the antitoxin yields F(ab¢)2 fragments of Immunotherapy is a treatment mechanism in which ther- antibodies that retain their antigen-binding property but lose apy is the aim at targets of the immune system that include the highly antigenic Fc region. This process diminishes the antigen-presenting cells, activated T cells, macrophages, and development of serum sickness-type reactions and is called B cells. In the past, this antiserum was used together Has also been used for Kawasaki syndrome and has various with antibiotics and surgical intervention in the treatment of unlabeled uses including posttransfusion purpura, Guillain- wounds where gas gangrene was possible. This preparation may be Sjögren syndrome, type I diabetes mellitus, IgG4 subclass effective against hepatitis A and B, cytomegalovirus, rubella, defciencies, intractable epilepsy (possibly caused by IgG2 varicella-zoster, tetanus, and various other agents. Immune serum is an antiserum containing antibodies spe- cifc for a particular antigen or immunogen. Such antibodies Pegademase bovine is a modifed enzyme used for enzyme may confer protective immunity. This treatment corrects the metabolic viral infections including measles and hepatitis A. The method of pro- increase leading to metabolic abnormalities that are toxic duction is extraction by cold ethanol fractionation at acid pH. Bone marrow transplantation can cure the Viruses are inactivated, which permits the safe administra- immune defciency. It is employed in treatment with primary immunodefciency syndromes including con- to block the expression of selected proteins. Patients with (human—injection) has been indicated for prophylaxis severe combined immunodefciency have an impairment of of cytomegalovirus disease associated with transplantation antibody synthesis as well as a T cell defect. Monoclonal antibodies have multiple Low-titer (1:128) and high-titer (1:100,000) preparations are uses in health care. Oseltamivir (Tamifu®) is a powerful inhibitor of the the antimouse response affects the continued administration neuraminidase enzyme of infuenza viruses A and B. The hypersensitivity Neuraminidase leads to cleavage of sialic acid residues on induced can be expressed as anaphylaxis, subacute allergic newly formed virions and is critical to the release and spread reactions, delayed-type hypersensitivity, rash, urticaria, fu- of progeny viruses. On contact with oseltamivir, infuenza like symptoms, gastrointestinal disorders, dyspnea, hypoten- virions aggregate on host cell surfaces, which limits the sion, and renal failure. It is able to lyse acute illness due to infuenza in patients 1 year and older who cells using human complement, making no other manipu- have manifested symptoms for no more than 2 days. H5N1 lation necessary to deplete T cells other than to add donor infuenza virus strains are usually sensitive to the drug, but serum. This has been used to deplete T cells to prevent no clinical data of effcacy are available. Clinical effcacy is lytic agents, killing cells in vitro with human complement as 60–70%. These antibodies have been used for therapy were diminished if treatment was started within 48 hours. It was formed by transplanting only clinical side effect is mild gastrointestinal distress. Even though initial hydrolysis when converted to the active form oseltamivir binding affnity was decreased, this was corrected by modi- carboxylate. E5 may monoclonal antibody that selectively binds with high affn- recognize and combine with lipid A epitope. The antibody is an IgG1 kappa that contains human the lipid A domain of endotoxin. It prevents binding for the treatment of patients with sepsis and Gram-negative by the natural ligand and down-regulates the receptor. It is used bacteremia, whether or not they are in shock, but not in those in the treatment of metastatic breast cancer where the tumors with focal Gram-negative infection. Rituxan (rituximab) is an anticancer monoclonal antibody Herceptin® See Trastuzumab. It acts by complement-mediated lysis, Infiximab is a human-mouse chimeric IgG1 monoclonal antibody-dependent cellular cytotoxicity, and apoptosis of antibody comprised of human constant (Fc) regions and malignant lymphoma cells. It is associated with acti- sequence, the calculated mol wt of the protein is 144 kDa. It is vation of neutrophil and eosinophil functional activity and a glycoprotein obtained from fermentation of an established induction of acute phase reactants. The active ingredient, basiliximab, is disease, ulcerative colitis, rheumatoid arthritis, ankylosing water soluble. The drug product, Simulect, is a sterile lyo- spondylitis, and psoriatic arthritis. The Cetuximab is a human−mouse chimeric monoclonal anti- chimeric 7E3 antibody is produced by continuous perfusion body that combines with epidermal growth factor receptor in mammalian cell culture. It has a decreas- purifed from cell culture supernatant by a series of steps ing kinase activity, matrix metalloproteinase activity, and involving specifc viral inactivation and removal procedures, growth factor synthesis, as well as elevated apoptosis. E5 is a murine monoclonal IgM antibody to endotoxin that has proven safe and capable of diminishing mortality Moferumomab is a mouse monoclonal antibody labeled and helping to reverse organ failure in patients with Gram- with 99mTc used as a diagnostic aid to ascertain the extent of Therapeutic Immunology 791 disease and to stage patients with small cell lung cancer. It diminishes levels of C-reactive protein, eryth- types, but also on selected normal cells. It lyses surface cells in vitro in the lin that counteracts allograft rejection, possibly by blocking presence of complement. It interacts with and inhibits the function of the involved in infammatory and immune responses. This agent inhibits all known matory reaction and joint destruction that are hallmarks of T cell functions and interacts with most peripheral T cells in the disease.