|Medical Dictionary - Dictionary of Medicine and Human Biology|
A neoplasm composed of chromaffin cells occurring in the medullae of adrenal glands, the organs of Zuckerkandl, or the paraganglia of the thoracolumbar sympathetic chain; may secrete catecholamines. SEE ALSO: pheochromocytoma. SYN: chromaffin tumor.
Obsolete term for any pathologic condition of chromaffin tissue, as in the medullae of adrenal glands or the organs of Zuckerkandl. [chromaffin + G. pathos, suffering]
chroman, chromane (kro′man, -man)
Fundamental unit of the tocopherols (vitamin E). SEE ALSO: chromanol, chromene, chromenol.
6-Hydroxychroman (6-c.) is the fundamental unit of the tocopherols (vitamin E), tocols, and tocotrienols, as well as of ubi-, toco-, and phyllochromanol. SEE ALSO: chroman, chromene, chromenol. SYN: hydroxychroman.
A salt of chromic acid. sodium c. Cr 51 anionic hexavalent radioactive chromium in the form of sodium c. (Na251CrO4) with a half-life of 27.8 days; used for the determination of circulating red cell volume and red cell survival time.
Of or pertaining to color or colors; produced by, or made in, a color or colors.
Each of the two strands formed by longitudinal duplication of a chromosome that becomes visible during prophase of mitosis or meiosis; the two chromatids are joined by the still undivided centromere; after the centromere has divided at metaphase and the two chromatids have separated, each c. becomes a chromosome. [G. chroma, color, + -id (2),]
The genetic material of the nucleus, consisting of deoxyribonucleoprotein, which occurs in two forms during the phase between mitotic divisions: 1) as heterochromatin, seen as condensed, readily stainable clumps; 2) as euchromatin, dispersed lightly staining or nonstaining material. During mitotic division the c. condenses into chromosomes. [G. chroma, color] heteropyknotic c. SYN: heterochromatin. oxyphil c. SYN: oxychromatin. sex c. a small condensed mass of the inactivated X-chromosome usually located just inside the nuclear membrane of the interphase nucleus; the number of sex c. bodies per nucleus is one less than the number of X-chromosomes, hence normal males and females with Turner syndrome (XO) have none (sex c. negative), normal females and males with Klinefelter syndrome (XXY) have one, and XXX-females have two c. masses. For technical reasons only about half the cells in a preparation show typical masses. SEE ALSO: Lyon hypothesis. SYN: Barr c. body.
Fragmentation of the chromatin. [chromatin + G. rhexis, rupture]
1. Abnormal pigmentation. 2. SYN: chromatic aberration. [G. chroma, color]
Producing color; causing pigmentation. [chromato- + -gen, producing]
The graphic record produced by chromatography.
To perform chromatography.
Pertaining to chromatography.
The separation of chemical substances and particles (originally plant pigments and other highly colored compounds) by differential movement through a two-phase system. The mixture of materials to be separated is percolated through a column or sheet of some suitable chosen absorbent ( e.g., an ion-exchange material); the substances least absorbed are least retarded and emerge the earliest; those more strongly absorbed emerge later. SYN: absorption c.. [chromato- + G. grapho, to write] absorption c. SYN: c.. adsorption c. c. in which separation of substances is achieved by the difference in degree of adsorption of the compounds to a stationary phase. affinity c. c. where the absorbent has a unique chemical affinity for a particular component of the passing solution. SYN: affinity column. column c. a form of partition, adsorption, ion exchange, or affinity c. in which one phase is liquid (aqueous) flowing down a column packed with the second phase, a solid; the dissolved substances form a partition between the solid and liquid phases depending on the chemical and physical conditions of each phase; the more strongly adsorbed solutes reach the bottom of the column later than the less strongly adsorbed ones. gas c. a chromatographic procedure in which the mobile phase is a mixture of gases or vapors, which are separated in the process by their differential adsorption on a stationary phase. gas-liquid c. (GLC) gas c., with the stationary phase being liquid rather than solid. gel filtration c. gel filtration. high-performance liquid c. (HPLC) a chromatographic technology used to separate and quantitate mixtures of substances in solution. A sample is injected into a moving stream of solvent that flows through a column and detector. Separation during passage through the column occurs by absorption, partition, ion exchange, or size exclusion. The technique is commonly used in laboratories to measure organic compounds including steroid hormones, pesticides and poisons, toxic and carcinogenic compounds, and drugs. SYN: high-pressure liquid c.. high-pressure liquid c. (HPLC) SYN: high-performance liquid c.. ion exchange c. c. in which cations or anions in the mobile phase are separated by electrostatic interactions with the stationary phase. SEE ALSO: anion exchange, cation exchange. liquid-liquid c. c. in which both the moving phase and the stationary (or reverse-moving) phase are liquids, as in countercurrent distribution. paper c. partition c. in which the moving phase is a liquid and the stationary phase is paper. partition c. the separation of similar substances by repeated divisions between two immiscible liquids, so that the substances, in effect, cross the partition between the liquids in opposite directions; where one of the liquids is bound as a film on filter paper, the process is termed paper partition c. or paper c.. reversed phase c. a form of partitionary c. in which the stationary phase is less polar than the mobile phase. thin-layer c. (TLC) c. through a thin layer of cellulose or similar inert material supported on a glass or plastic plate. two-dimensional c. paper c. in which a spot, located originally in one corner of a sheet, is developed in one direction along one side of the sheet, after which the sheet is rotated 90° and developed, with another solvent, in the new direction; the resultant spots are thus spread over the entire paper, giving a “map” or “fingerprint.” Also generalized to include c. followed by electrophoresis (or vice versa), column c. followed by paper c., etc.
A refractile substance composed of chromatin, thought to be a nonglycogen food reserve contained within the cytoplasm of certain protozoa; seen in cysts of Entamoeba histolytica as rounded bars or chromatoidal bodies in contrast to the splintery form of c. bodies in cysts of Entamoeba coli. [chromato- + G. eidos, form]
Rearrangement of the chromatin into various forms. [chromato- + G. kinesis, movement]
The disintegration of the granules of chromophil substance (Nissl bodies) in a nerve cell body that may occur after exhaustion of the cell or damage to its peripheral process; other changes considered part of c. include swelling of the perikaryon and shifting of the nucleus from its central position to the periphery. SYN: chromatinolysis, chromolysis, tigrolysis. [chromato- + G. lysis, dissolution] central c. c. associated with significant axonal injury. SYN: retrograde c.. retrograde c. SYN: central c.. transsynaptic c. SYN: transsynaptic degeneration.
Relating to chromatolysis.
SYN: colorimeter. [chromato- + G. metron, measure]
Relating to or causing chromatopexis. SYN: chromopectic.
The fixation of color or staining fluid, i.e., as the liver functions in forming bilirubin. SYN: chromopexis. [chromato- + G. pexis, fixation]
1. SYN: chromophilic. 2. SYN: chromophil (2) . 3. SYN: chromaffin.
chromatophilic, chromatophilous (kro-ma-to-fil′ik, -tof′i-lus)
1. A colored plastid, due to the presence of chlorophyll or other pigments, found in certain forms of protozoa. 2. Melanophage; a pigment-bearing phagocyte found chiefly in the skin, mucous membrane, and choroid coat of the eye, and also in melanomas. 3. SYN: chromophore. 4. A colored plastid in plants; e.g., chloroplasts, leukoplasts, etc. [chromato- + G. phoros, bearing]
Denoting the attraction of chromatophores to the skin or other organs. [chromatophore + G. tropos, a turning]
The part of the cytoplasm containing pigment.
A condition in which objects appear to be abnormally colored or tinged with color; designated according to the color seen: xanthopsia, yellow vision; erythropsia, red vision; chloropsia, green vision; cyanopsia, blue vision. SYN: chromatic vision, colored vision, tinted vision. Cf.:dyschromatopsia. [chromato- + G. opsis, vision]
A nucleosome with one bound histone-1 protein.
1. A change of color. 2. The phenomenon of orientation in response to color. [chromato- + G. trope, turn]
Abnormal coloration of the urine. [chromato- + G. ouron, urine]
Chromium, especially as a source of pigment. [G. chroma, color]
A word termination indicating relationship to color. [G. chroma color]
2H-1-Benzopyran;fundamental unit of the tocopherolquinones. SEE ALSO: chroman, chromanol, chromenol.
6-Hydroxychromene (6-c.) is the fundamental unit of the tocopherolquinones (oxidized tocopherol) and plastochromenol-8. SEE ALSO: chroman, chromanol, chromene. SYN: hydroxychromene.
Basic lead chromate.
1. The color sense. 2. A condition in which nonvisual stimuli, such as taste or smell, cause the perception of color. [G. chroma, color, + aisthesis, sensation]
chrome yellow [C.I. 77600]
A fine yellow powder used in paints and dyes. SYN: lead chromate, Leipzig yellow, lemon yellow, Paris yellow.
A rare condition characterized by the excretion of sweat containing pigment. SYN: chromidrosis. [chrom- + G. hidros, sweat] apocrine c. excretion of colored sweat, usually black, from apocrine glands.
chromic acid (kro′mik)
H2CrO4 or H2Cr2O7;a strong oxidizing agent formed by dissolving chromium trioxide (CrO3) in water. Has been used in solution as a topical antiseptic.
Plural of chromidium.
An outpouring of nuclear substance and chromatin into the cell protoplasm. SYN: chromidiation.
chromidium, pl .chromidia (kro-mid′e-um, -e-a)
A basophilic particle or structure in the cell cytoplasm, rich in RNA, often found in specialized cells. [G. chroma, color, + -idion, a diminutive termination]
chromium (Cr) (kro′me-um)
A metallic element, atomic no. 24, atomic wt. 51.9961. A dietary essential bioelement. 51Cr (half-life of 27.70 days) is used as a diagnostic aid in many disorders ( e.g., gastrointestinal protein loss). [G. chroma, color] c. trioxide CrO3;chromic acid, a strong oxidizing agent used as a caustic in the removal of warts and other small growths from the skin and genitals; the hydrated acid, H2CrO4, forms variously colored salts with potassium, lead, and other bases.
A genus of bacteria containing Gram-negative, motile rods. These microorganisms produce a violet pigment (violacein) and are occasionally pathogenic to humans and other animals. The type species is C. violaceum. C. violaceum type species of the genus C.; it is found in soil and water.
An embryonic cell with the potentiality of developing into a pigment cell. [chromo- + G. blastos, germ]
A localized chronic mycosis of the skin and subcutaneous tissues characterized by skin lesions so rough and irregular as to present a cauliflowerlike appearance; caused by dematiaceous fungi such as Phialophora verrucosa, Exophiala (wangiella) dermatitidis, Fonsecaea pedrosoi, F. compacta, and Cladosporium carrionii; fungal cells resembling copper pennies form rounded sclerotic bodies in tissue, with epidermal hyperplasia and intraepidermal microabscesses. SYN: chromomycosis. [chromo- + G. blastos, germ, + myke, fungus, + -osis, condition]
Any pigmented cell, such as a red blood corpuscle. [chromo- + G. kytos, cell]
1. A substance, itself without definite color, that may be transformed into a pigment; denoting especially benzene and its homologs toluene, xylene, quinone, naphthalene, and anthracene, from which the aniline dyes are manufactured. 2. A microorganism that produces pigment. 3. A compound, containing a chromophore, that is colorless if that chromophore is removed. Porter-Silber chromogens yellow phenylhydrazones formed by the reaction of 17,21-dihydroxy-20-oxosteroids with a phenylhydrazine-ethanol-sulfuric acid reagent; used chiefly to determine plasma cortisol concentrations and the urinary output of 17-hydroxycorticoids.
Production of coloring matter or pigment, often via an enzyme-catalyzed reaction. [chromo- + G. genesis, production]
1. Denoting a chromogen. 2. Relating to chromogenesis.
Soluble proteins of chromaffin granules; c. A, an acidic glycoprotein, accounts for approximately half of the total protein of the granule matrix.
Isomerism in which the isomers display different colors.
SYN: lipochrome (1) .
1. A condensed segment of a chromonema; densely staining bands visible in chromosomes under certain conditions. 2. SYN: granulomere. [chromo- + G. meros, a part]
SYN: chromoblastomycosis. [chromo- + G. mykes, fungus, + -osis, condition]
4H-1-Benzopyran-4-one;fundamental unit of various plant pigments and other substances. SEE ALSO: flavone, chromene, chroman.
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