Reaction Formation: From 1 Different Sources
(in psychoanalysis) a *defence mechanism by which unacceptable unconscious ideas are replaced in consciousness by their opposites. For instance, a man might make an ostentatious show of affection to someone for whom he has an unconscious hatred.
A test introduced for the diagnosis of SYPHILIS by examination of the blood. It has now been largely supplanted by other, more speci?c tests.... wassermann reaction
See AGGLUTINATION.... widal reaction
(PCR) A method of rapidly copying DNA sequences so that they can be analysed.... polymerase chain reaction
Any undesirable or unwanted consequence of a preventive, diagnostic or therapeutic procedure.... adverse event / reaction
(Eisenmenger syndrome) a condition in which *pulmonary hypertension is associated with a *septal defect, so that blood flows from the right to the left side of the heart or from the pulmonary artery to the aorta. This allows blue blood, poor in oxygen, to bypass the lungs and enter the general circulation. This reduces the oxygen content of the arterial blood in the aorta and its branches, resulting in a patient with a dusky blue appearance (*cyanosis) and an increased number of red blood cells (*polycythaemia). There is no curative treatment at this stage, but the patient may be helped by the control of heart failure and polycythaemia. The condition may be prevented by appropriate treatment of the septal defect in early childhood before irreversible pulmonary hypertension develops. [V. Eisenmenger (1864–1932), German physician]... eisenmenger reaction
a method of demonstrating the presence of DNA in cell nuclei. The tissue section under investigation is first hydrolysed with dilute hydrochloric acid and then treated with *Schiff’s reagent. A purple coloration develops in the presence of DNA. [R. Feulgen (1884–1955), German chemist]... feulgen reaction
see Jarisch-Herxheimer reaction.... herxheimer reaction
a curved band of cortex lying within each cerebral hemisphere: in evolutionary terms one of the brain’s most primitive parts. It forms a portion of the *limbic system and is involved in the complex physical aspects of behaviour governed by emotion and instinct.... hippocampal formation
(Herxheimer reaction) exacerbation of the symptoms of syphilis that may occur on starting antibiotic therapy for the disease. The effect is transient and requires no treatment. [A. Jarisch (1850–1902), Austrian dermatologist; K. Herxheimer (1861–1944), German dermatologist]... jarisch–herxheimer reaction
a test for syphilis, in which antibodies specific to the disease are detected in a sample of the patient’s blood by means of a *precipitin reaction. This test is not as reliable as some. [R. L. Kahn (20th century), US bacteriologist]... kahn reaction
an aggravation of lumps on the skin caused by *leprosy, accompanied by fever and malaise.... lepra reaction
a histochemical test for proteins, in which ninhydrin (triketohydrindene hydrate) is boiled with the test solution and gives a blue colour in the presence of amino acids and proteins.... ninhydrin reaction
(PAS reaction) a test for the presence of glycoproteins, polysaccharides, certain mucopolysaccharides, glycolipids, and certain fatty acids in tissue sections. The tissue is treated with periodic acid, followed by *Schiff’s reagent. A positive reaction is the development of a red or magenta coloration.... periodic acid–schiff reaction
a reaction in which antibodies against the bacterium Streptococcus pneumoniae combine with the bacterial capsule, which becomes swollen and visible to light microscopy.... quellung reaction
a network of nerve pathways and nuclei throughout the *brainstem, connecting motor and sensory nerves to and from the spinal cord, the cerebellum and the cerebrum, and the cranial nerves. It is estimated that a single neuron in this network may have synapses with as many as 25,000 other neurons.... reticular formation
a diagnostic test for typhus. A sample of the patient’s serum is tested for the presence of antibodies against the organism Proteus vulgaris. Although this relatively harmless organism is not the cause of typhus, it possesses certain antigens in common with the causative agent of the disease and can therefore be used instead of it in laboratory tests. Typhus is suspected if antibodies are found to be present. [E. Weil (1880–1922), German physician; A. Felix (1887–1956), Czech bacteriologist]... weil–felix reaction
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