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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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phosphorylation (fos′for-i-la′shun)
Addition of phosphate to an organic compound, such as glucose to produce glucose monophosphate, through the action of a phosphotransferase (phosphorylase) or kinase. oxidative p. formation of high-energy phosphoric bonds ( e.g., in pyrophosphates) from the energy released by the flow of electrons to O2 and the dehydrogenation (i.e., oxidation) of various substrates, most notably isocitric acid, α-ketoglutaric acid, succinic acid, and malic acid in the tricarboxylic acid cycle. substrate-level p. the synthesis of ATP (or other NTP) not involving electron transport coupled with oxidative p. or with photophosphorylation.

phosphorylcholine (fos′for-il-ko′len)
SYN: phosphocholine.

phosphorylethanolamine glyceridetransferase (fos′for-il-eth-a-nol′a-men)
SYN: ethanolaminephosphotransferase.

phosphosphingosides (fos-fo-sfing′go-sidz)
SYN: sphingomyelins.

phosphosugar (fos-fo-shug′er)
A phosphorylated saccharide; any sugar containing an alcoholic group esterified with phosphoric acid.

phosphotransacetylase (fos′fo-trans-a-set′i-las)
SYN: phosphate acetyltransferase.

phosphotransferases (fos-fo-trans′fer-as-ez)
A subclass of transferases (EC subclass 2.7) transferring phosphorus-containing groups. P. include the “kinases” (2.7.1) transferring phosphate to alcohols, to carboxyl groups (2.7.2), to nitrogenous groups (2.7.3), or to another phosphate group (2.7.4). Phosphomutases (5.4.2) catalyze apparent intramolecular transfers; pyrophosphokinases (2.7.6) catalyze transfer of the pyrophosphate group; nucleotidyltransferases (2.7.7) catalyze transfer of the nucleotide (nucleotidyl) groups (including polyribonucleotide nucleotidyltransferase) and other similar groups (2.7.8). SYN: transphosphatases.

phosphotriose isomerase (fos-fo-tri′os)
SYN: triosephosphate isomerase.

phosphotungstic acid (PTA) (fos-fo-tung′stik)
A mixture of phosphoric and tungstic acids; a protein precipitant and reagent for arginine, lysine, histidine, and cystine; used with hematoxylin for nuclear and muscle staining; also used in electron microscopy as a stain for collagen and as a negative stain.

phosphovitin
SYN: phosvitin.

phosphuresis (fos′foo-re′sis)
Excretion of excessive amounts of phosphate in the urine. [phospho- + G. ouresis, urination]

phosphuria (fos-foo′re-a)
SYN: phosphaturia.

phosvitin (fos-vi′tin)
A phosphated protein constituting about 7% of the protein of egg yolk; it is about 60% serine, largely as O-phosphoserine, and has anticoagulant properties; an anticoagulant. SYN: phosphovitin.

phot (fot)
A unit of illumination; 1 p. equals 1 lumen/cm2 of surface. [G. phos (p.-), light]

phot-
See photo-.

photalgia (fo-tal′je-a)
Light-induced pain, especially of the eyes; for example, in uveitis, the light-induced movement of the iris may be painful. SYN: photodynia, photophobia. [phot- + G. algos, pain]

photaugiaphobia (fo-taw′je-a-fo′be-a)
Morbid fear of, or overreaction to, a glare of light. [G. photaugeia, glare of light, + phobos, fear]

photesthesia (fo-tes-the′ze-a)
Perception of light. [photo- + G. aisthesis, sensation]

photic (fo′tik)
Relating to light.

photism (fo′tizm)
Production of a sensation of light or color by a stimulus to another sense organ, such as of hearing, taste, or touch. SYN: pseudophotesthesia.

photo-, phot-
Light. [G. phos (phot-)]

photoablation (fo′to-ab-la′shun)
The process of photoablative decomposition of tissue by laser light, e.g., in photorefractive keratectomy.

photoactinic (fo′to-ak-tin′ik)
Denoting radiation that produces both luminous and chemical effects. [photo- + G. aktis, ray]

photoaging (fo′to-aj′ing)
Damage from years of sun exposure, particularly wrinkling of skin. [[photo- + aging]]

photoallergy (fo′to-al′er-je)
See photosensitization.

photoautotroph (fo′to-aw′to-trof)
An organism that depends solely on light for its energy and principally on carbon dioxide for its carbon. Cf.:photoheterotroph, photolithotroph, phototroph. [photo- + G. autos, self, + trophe, nourishment]

photoautotrophic (fo-to-aw′to-trof′ik)
Pertaining to a photoautotroph.

photobacteria (fo′to-bak-ter′e-a)
Plural of photobacterium.

Photobacterium (fo′to-bak-ter′e-um)
A genus of motile and nonmotile, aerobic to facultatively anaerobic bacteria (family Pseudomonadaceae) containing Gram-negative coccobacilli and occasional rods; under adverse conditions pleomorphic forms frequently occur. Motile cells have polar flagella. The metabolism of these organisms is fermentative. They are usually luminescent and occur symbiotically in tissues of luminous organs of cephalopods and deep-sea fishes and on the skin and in the intestines of some marine fish. The type species is P. phosphoreum. P. phosphoreum a luminescent species found on dead fish and in sea water; it is the type species of the genus P..

photobacterium, pl .photobacteria (fo′to-bak-ter′e-um, -bak-ter′e-a)
A vernacular term used to refer to any member of the genus P..

photobiology (fo′to-bi-ol′o-je)
The study of the effects of light upon plants and animals.

photobiotic (fo′to-bi-ot′ik)
Living or flourishing only in the light. [photo- + G. bios, life]

photobleach (fo′to-blech)
To lose color or make white by the action of light; E.G., the use of a laser to bleach a fluorescent dye covalently linked to a macromolecule.

photocatalyst (fo-to-kat′a-list)
A substance that helps bring about a light-catalyzed reaction; e.g., chlorophyll. [photo- + G. katalysis, dissolution (catalysis)]

photoceptor (fo′to-sep′ter, -tor)
SYN: photoreceptor.

photochemical (fo-to-kem′i-kal)
Denoting chemical changes caused by or involving light.

photochemistry (fo-to-kem′is-tre)
The branch of chemistry concerned with the chemical changes caused by or involving light.

photochemotherapy (fo′to-kem-o-thar′a-pe, -ke-mo-)
SYN: photoradiation.

photochromogens (fo′to-kro′mo-jenz)
SYN: Runyon group I mycobacteria. [photo- + G. chroma, color, + -gen, producing]

photocoagulation (fo′to-ko-ag′u-la′shun)
A method by which a beam of electromagnetic energy is directed to a desired tissue under visual control; localized coagulation results from absorption of light energy and its conversion to heat or conversion of tissue to plasma (atoms stripped of electrons). [photo- + L. coagulo, pp. -atus, to curdle]

photocoagulator (fo′to-ko-ag′u-la′ter, tor)
The apparatus used in photocoagulation. laser p. a high-energy source of electromagnetic radiation. See laser. xenon-arc p. a p. in which a xenon-arc bulb delivers radiation from the visible and near-infrared spectrum.

photodermatitis (fo′to-der-ma-ti′tis)
Dermatitis caused or elicited by exposure to sunlight; may be phototoxic or photoallergic, and can result from topical application, ingestion, inhalation, or injection of mediating phototoxic or photoallergic material. SEE ALSO: photosensitization. SYN: actinic dermatitis. [photo- + G. derma, skin, + -itis, inflammation]

photodistribution (fo′to-dis-tri-bu′shun)
Areas on the skin that receive the greatest amount of exposure to sunlight, and which are involved in eruptions due to photosensitivity.

photodromy (fo-tod′ro-me)
In the induced or spontaneous clarification of certain suspensions, the settlement of particles on the side nearest the light (positive p.) or on the dark side (negative p.). [photo- + G. dromos, a running]

photodynamic (fo′to-di-nam′ik)
Relating to the energy or force exerted by light. [photo- + G. dynamis, force]

photodynia (fo-to-din′e-a)
SYN: photalgia. [photo- + G. odyne, pain]

photodysphoria (fo′to-dis-for′e-a)
Extreme photophobia. [photo- + G. dysphoria, extreme discomfort]

photoelectric (fo′to-e-lek′trik)
Denoting electronic or electric effects produced by the action of light. See p. effect, p. absorption.

photoelectrometer (fo′to-e-lek-trom′e-ter)
A device employing a photoelectric cell for measuring the concentration of substances in solution.

photoelectron (fo′to-e-lek′tron)
An electron freed by the action of light.

photoerythema (fo′to-er-i-the′ma)
Erythema caused by exposure to light. [photo- + G. erythema, flush]

photoesthetic (fo′to-es-thet′ik)
Sensitive to light. [photo- + G. aisthesis, sensation]

photofluorography (fo′to-flor-og′ra-fe)
Miniature radiographs made by contact photography of a fluoroscopic screen, formerly used in mass radiographic examination of the lungs. SYN: fluorography, fluororoentgenography. [photo- + L. fluor, a flow, + G. graphe, a writing]

photogastroscope (fo′to-gas′tro-skop)
An instrument for taking photographs of the interior of the stomach. [photo- + G. gaster, stomach, + skopeo, to view]

photogen (fo′to-jen)
A microorganism that produces luminescence. [photo- + G. gen-, producing]

photogenesis (fo-to-jen′e-sis)
Production of light, as by bacteria, insects, or phosphorescence. [photo- + G. genesis, production]

photogenic, photogenous (fo-to-jen′ik, fo-toj′e-nus)
Denoting or capable of photogenesis.

photohemotachometer (fo′to-he′mo-ta-kom′e-ter)
An appliance for recording photographically the rapidity of the blood current. [photo- + G. haima, blood, + tachos, speed, + metron, measure]

photoheterotroph (fo′to-het′er-o-trof, -trof)
An organism that depends on light for most of its energy and principally on organic compounds for its carbon. Cf.:photoautotroph, photolithotroph, phototroph. [photo- + G. heteros, other, + trophe, nourishment]

photoheterotrophic (fo′to-het′er-o-trof′ik)
Pertaining to a photoheterotroph.

photoinactivation (fo′to-in-ak-ti-va′shun)
Inactivation by light; e.g., as in the treatment of herpes simplex by local application of a photoactive dye followed by exposure to a fluorescent lamp.

photokeratoscope (fo′to-ker′ah-to-skop)
A keratoscope fitted with a still film camera.

photokinesis (fo′to-ki-ne′sis)
Alteration of random movements of motile organisms in response to light. [photo- + G. kinesis, movement]

photokinetic (fo′to-ki-net′ik)
1. Pertaining to photokinesis. 2. Pertaining to photokinetics.

photokinetics (fo′to-ki-net′iks)
The changes in rate of a chemical reaction in response to light. [photo- + G. kinetikos, relating to movement]

photokymograph (fo-to-ki′mo-graf)
A device for moving film at a constant speed so that a continuous record of a physiologic event may be obtained, as by a beam of light shining on the film. [photo- + G. kyma, wave, + grapho, to record]

photolithotroph (fo′to-lith′o-trof)
An organism that requires inorganic compounds and that uses light for most of its energy needs. Cf.:photoautotroph, photoheterotroph, phototroph. [photo- + G. lithos, stone, mineral, + trophe, nourishment]

photoluminescent (fo′to-loo-mi-nes′ent)
Having the ability to become luminescent upon exposure to visible light. [photo- + L. lumen, light]

photolyase (fo-to-li′as)
See deoxyribodipyrimidine p.. [photo- + G. lyo, to loosen, + -ase]

photolysis (fo-tol′i-sis)
Decomposition of a chemical compound or cleavage of a chemical bond by the action of light. [photo- + G. lysis, dissolution]

photolyte (fo′to-lit)
Any product of decomposition by light.

photolytic (fo-to-lit′ik)
Pertaining to photolysis.




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