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focus-object distance. The distance from the target of an x-ray tube to the surface being radiographed.


[Acronym of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols] Any of the short-chain carbohydrates and monosaccharides that are poorly absorbed in the small intestine. Some evidence links the poor absorption of these nutrients to the symptoms of irritable bowel syndrome.


Droplets suspended in a gas, as minute water droplets in air.


(fog′ing) 1. A method of testing vision, used particularly in testing myopia and in postcycloplegic examination, in which accommodation is relaxed by overcorrection. 2. A method of intense application of an insecticide. The solution is nebulized and appears in the air as a mist. 3. Unwanted density on radiographic film resulting from exposure to secondary radiation, light, chemicals, or heat. 4. The loss of intensity of the radiologic appearance of a cerebral infarct on magnetic resonance imaging (MRI) of the brain several weeks after the stroke occurs.

fogging effect

Transient difficulty in visualizing an ischemic stroke with computed tomography (CT) or magnetic resonance (MR) imaging, typically occurring about 10 days after the stroke.

fogo selvagem

(fō′gō, sel-va′zhĕm) [Portuguese fogo selvagem, wild fire] ABBR: FS. An autoimmune disease that causes blistering of the skin of the head, neck or trunk, esp. when the skin is rubbed (Nikolsky sign).

INCIDENCE: The disease is typically found in Brazil or Colombia. It has been associated with chronic or recurrent exposure to black flies.

SYMPTOMS AND SIGNS: FS often causes an unpleasant burning sensation (dysesthesia) on the skin, from which the popular name of the disease is derived.

DIAGNOSIS: Skin biopsies reveal blistering beneath the corneal layer of the skin with acantholysis (detachment of keratinocytes). Immunoglobulin G (IgG) autoantibodies against intracellular adhesion molecules (anti-desmoglein 1-(Dsg1) are pathogenic and are found in the serum of affected patients and on direct immunofluorescent staining of skin biopsies.

TREATMENT: Imiquimod (a topical immune response modifier), immune-suppressing drugs, and monoclonal antibody therapies have been used to treat all forms of pemphigus foliaceus, which includes FS.

PATIENT CARE: Blisters should be kept clean and dry andshould not be disturbed (rubbed, scratched, or popped). Affected skin should be protected from abrasion against neighboring body parts or clothing, and kept out of direct sunlight. Professional health care should be sought when blisters become painful or obviously infected or when they form near or in the eyes, mouth, or anus. SYN: endemic pemphigus foliaceus.


A thin, pliable sheet of metal. In dentistry, various types of gold foil are used ...

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