Refers to diarrhea that develops in a person who is taking, or has recently taken antibiotics. The most common cause of severe antibiotic-associated diarrhea (AAD) is Clostridium difficile (C. difficile; a.k.a.: C. diff).
Letter: a
A substance formed in the body by B cells. They reacted very specifically with bacteria, viruses, allergens or other substances that initiated their production. Depending on their subtype, they can cause hypersensitivity (IgE) or resistance to infection (IgA, IgD, IgE, IgG, IgM). The Ig stands for immunoglobulin and the A, D, E, G, and M are the categories of antibodies. Antibodies have several functions. An antibody is specific to an antigen.
Any substance that is capable of eliciting an immune response; a molecule that causes the creation of and subsequently combines with the antibody or antigen-specific receptor on a T-cell.
Chemical contact sensitizers that can elevate the level of sensitization to that specific chemical if the individual has the genetic capability to react. When their reaction threshold is reached, the sensitized individual, will present symptoms on subsequent exposures usually as allergic contact dermatitis (Type IV, delayed type hypersensitivity).
Refers to small, gradual, random point mutations in the genetic material responsible for the main viral surface proteins, hemagglutinin, and neuraminidase. Vaccines against initial virus may no longer be effective.
Antigenic shift refers to an abrupt, major change to produce a novel influenza A virus subtype in humans that was not currently circulating among people (see more information below under Influenza Type A and its subtypes). This can occur when viruses from two different host species (man and bird) infect the same cell and swap genetic information. Vaccines against either of the two original viruses will no longer be effective.
The terminal portion of an air passageway within the lung. Its wall is made of simple squamous epithelium and is surrounded by a netting of pulmonary capillaries. This is the site of gas exchange. Each alveolar sac is connected to a respiratory bronchiole by an alveolar duct.
Alveolar ventilation (Va or VA) is the volume of air breathed in per minute that reaches the alveoli and takes part in gas exchange.
The difference between the partial pressure of oxygen in the alveoli and that in the systemic arterial blood. The difference may indicate ventilation-perfusion mismatching.
The structures and substances through which gases must pass as they diffuse from air to blood (oxygen) or blood to air (carbon dioxide). These include the alveolar fluid, surfactant, and cells of the alveolar wall. Interstitial space (tissue fluid), and cells of the capillary wall. SYN: respiratory membrane.