| ARI | acute respiratory illness; airway reactivity index; anxiety reaction, intense |
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| ARM | adrenergic receptor material; aerosol rebreathing method; ambulatory renal monitor; anorectal manome... |
| ASR | aldosterone secretion rate; antistreptolysin reaction |
| ASSR | adult situation stress reaction |
| BFPR | biologic false-positive reaction |
| magnet reaction | A reaction seen in an animal deprived of its cerebellum; when the animal is placed upon its back and the head strongly flexed, the four limbs become flexed in all their joints. Due to stimulation of receptors in the deep layers of the skin, light pressure made upon a toe-pad with the finger causes reflex contraction of the limb extensors; the limb is thus pressed gently against the finger, and when the finger is withdrawn slightly, the experimenter has the sensation that his finger is raising the limb or drawing it out as by a magnet. (05 Mar 2000) |
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| maillard reaction | One of a group of nonenzymatic reactions in which aldehydes, ketones, or reducing sugars react with amino acids, peptides, or proteins. Food browning reactions, such as those that occur with cooking of meats, and also food deterioration reactions, resulting in decreased nutritional value and colour changes, are attributed to this reaction type. The maillard reaction is studied by scientists in the agriculture, food, nutrition, and carbohydrate chemistry fields. (12 Dec 1998) |
| Pandy's reaction | A test to determine the presence of proteins (chiefly globulins) in the spinal fluid, by adding one drop of spinal fluid to 1 ml of solution (e.g., carbolic acid crystals in distilled water, cresol, or pyrogallic acid); the reaction varies from a faint turbidity to a dense "milky" precipitate according to the degree of protein content. Synonym: Pandy's test. (05 Mar 2000) |
| gemistocytic reaction | <cell biology> A reaction to injury resulting in the proliferation of reactive, protoplastic, or gemistocytic astrocytes. (05 Mar 2000) |
| reaction | Standard method for identifying Clostridium perfringens. When grown on agar containg egg yolk, an opalescent halo is formed around colonies that produce _ toxin (lecithinase). (18 Nov 1997) |
| reaction, allergic | A reaction that occurs when the immune system attacks a usually harmless substance (an allergen) that gains access to the body. The immune system calls upon a protective substance called immunoglobulin e (IgE) to fight these invading allergic substances ( allergens). Even though everyone has some IgE, an allergic person has an unusually large army of these IgE defenders -in fact, too many for their own good. This army of IgE antibodies attacks and engages the invading army of allergic substances of allergens. As is often the case in war, innocent bystanders are affected by this battle. These innocent bystanders are special cells called mast cells. These cells are frequently injured during the warring of the IgE antibodies and the allergic substances. When a mast cell is injured, it releases a variety of strong chemicals including histamine into the tissues and blood that frequently cause allergic reactions. These chemicals are very irritating and cause itching, swelling, and fluid leaking from cells. These allergic chemicals can cause muscle spasm and can lead to lung and throat tightening as is found in asthma and loss of voice. (12 Dec 1998) |
| reaction centre | <plant biology> The site in the chloroplast that receives the energy trapped by chlorophyll and accessory pigments and initiates the electron transfer process. A photosynthetic complex containing chlorophyll (or bacteriochlorophyll) and other components, within which occurs the initial electron transfer reactions of photophosphorylation. (09 Oct 1997) |
| reaction formation | In psychoanalysis, a postulated defense mechanism in which attitudes and behaviours that are adopted are the opposites of that which the individual would ordinarily be expected to express and actually feel at an unconscious level. (05 Mar 2000) |
| reaction intermediate | <biochemistry> Any biomolecule which iscreated and destroyed during the course of of a particular reaction pathway. (09 Oct 1997) |
| reaction of degeneration | The electrical reaction in a degenerated nerve and the muscles supplied by it; characterised by absence of response to both galvanic and faradic stimulus in the nerve and to faradic stimulus in the muscles; the muscles may still respond to galvanic stimulation, but the cathodal closing contraction is greater than the anodal closing contraction, the reverse of normal. (05 Mar 2000) |
| reaction of identity | See: gel diffusion precipitin tests in two dimensions. (05 Mar 2000) |
| reaction of nonidentity | See: gel diffusion precipitin tests in two dimensions. (05 Mar 2000) |
| reaction of partial identity | See: gel diffusion precipitin tests in two dimensions. (05 Mar 2000) |
| reaction quotient | <chemistry> A constant represented by the symbol Q which is defined as the product of the concentrations of the products, each raised to the power that corresponds to its coefficient in the balanced equation, divided by the product of the concentrations of reactants, each raised to the power that corresponds to its coefficient in the balanced equation (see the equation in the equations page). at equilibrium conditions Q=K, the equilibrium constant. (09 Jan 1998) |
| reaction time | The time from the onset of a stimulus until the organism responds. (12 Dec 1998) |