Medical Dictionary banner
Medical Dictionary - Dictionary of Medicine and Human Biology

Medical Dictionary


lacrimation (lak′ri-ma′shun)
The secretion of tears, especially in excess. [L. lacrimatio]

lacrimator (lak′ri-ma-ter)
An agent (such as tear gas) that irritates the eyes and produces tears. [L. lacrima, tear]

lacrimatory (lak′ri-ma-to-re)
Causing lacrimation.

lacrimotomy (lak-ri-mot′o-me)
The operation of incising the lacrimal duct or sac. [L. lacrima, tear, + G. tome, incision]

lact-, lacti-, lacto-
Milk. SEE ALSO: galacto-. [L. lac, lactis]

lactacidemia (lak-tas-i-de′me-a)
SYN: lactic acidemia.

lactacidosis (lak-tas-i-do′sis)
Acidosis due to increased lactic acid.

lactalbumin (lak-tal-bu′min)
The albumin fraction of milk. It contains two proteins: α- and β-l.; the former, minor l., interacts with galactosyl transferase to form lactose synthase which synthesizes lactose from d-glucose and UDP-galactose in milk production; β-l. is the chief whey protein in bovine milk; α-l. is the most heat-stable of the whey proteins.

lactam, lactim (lak′tam, -tim)
Contractions of “lactoneamine” and “lactoneimine,” and applied to the tautomeric forms –NH–CO– and –N&dbond;C(OH)–, respectively, observed in many purines, pyrimidines, and other substances; the latter form accounts for the acidic properties of uric acid.

lactamase (lak′ta-maz)
SYN: β-l..

lactase (lak′tas)
SYN: β-d-galactosidase.

lactate (lak′tat)
1. A salt or ester of lactic acid. 2. To produce milk in the mammary glands. l. dehydrogenase (LDH) name for a number of enzymes, including: l-l. dehydrogenase (cytochrome), d-l. dehydrogenase (cytochrome), l-l. dehydrogenase, and d-l. dehydrogenase. The first two enzymes transfer hydrogen to ferricytochrome c or to cytochrome b2, the last two enzymes transfer it to NAD+, in catalyzing the oxidation of l. to pyruvate; the isozyme distribution of heart and muscle l. dehydrogenase is of significant use in cases of myocardial infarction; a deficiency of a subunit will result in myoglobinuria after intense exercise. SYN: lactic acid dehydrogenase. excess l. the increase in l. concentration beyond what would be expected from the increase in pyruvate concentration resulting from a change in redox potential; used as an index of anaerobic carbohydrate metabolism. Ringer l. SYN: Ringer solution.

lactate 2-mono-oxygenase
A flavoprotein oxidoreductase catalyzing oxidation (with O2) of l-lactate to acetate plus CO2 and water. SYN: lactic acid oxidative decarboxylase.

lactation (lak-ta′shun)
1. Production of milk. 2. Period following birth during which milk is secreted in the breasts. [L. lactatio, suckle]

lactational (lak-ta′shun-al)
Relating to lactation.

lacteal (lak′te-al)
1. Relating to or resembling milk; milky. 2. A lymphatic vessel that conveys chyle. SYN: chyle vessel, l. vessel. central l. the blindly ending lymphatic capillary in the center of an intestinal villus.

lactenin (lak′te-nin)
An antibacterial agent active against streptococci isolated from cow's milk.

lactescent (lak-tes′ent)
Resembling milk; milky.

See lact-.

lactic (lak′tik)
Relating to milk. [L. lac (lact-), milk]

lactic acid
A normal intermediate in the fermentation (oxidation, metabolism) of sugar. In pure form, a syrupy, odorless, and colorless liquid obtained by the action of the l. bacillus on milk or milk sugar; in concentrated form, a caustic used internally to prevent gastrointestinal fermentation. A culture of the bacillus, or milk containing it, is usually given in place of the acid. l-L. is also known as sarcolactic acid.

lactic acid dehydrogenase
SYN: lactate dehydrogenase.

lactic acidemia (lak′tik-as-i-de′me-a)
The presence of dextrorotatory lactic acid in the circulating blood. SYN: lactacidemia. [lactic acid + G. haima, blood]

lactic acid oxidative decarboxylase
SYN: lactate 2-mono-oxygenase.

lactiferous (lak-tif′er-us)
Yielding milk. [lacti- + L. fero, to bear]

lactifugal (lak-tif′u-gal)
SYN: lactifuge (1) .

lactifuge (lak′ti-fuj)
1. Causing arrest of the secretion of milk. SYN: lactifugal. 2. An agent having such an effect. [lacti- + L. fugo, to drive away]

lactigenous (lak-tij′e-nus)
Producing milk. [lacti- + -gen, producing]

lactim (-tim)
See lactam.

lactimorbus (lak-ti-mor′bus)
SYN: milk sickness. [lacti- + L. morbus, disease]

lactinated (lak′ti-na-ted)
Prepared with or containing milk sugar.

See lact-.

Lactobacillaceae (lak′to-bas′i-la′se-e)
A family of anaerobic to facultatively anaerobic, ordinarily nonmotile bacteria (order Eubacteriales) containing straight or curved, Gram-positive rods which usually occur singly or in chains; motile cells are peritrichous. These organisms have complex organic nutritional requirements; they produce lactic acid from carbohydrates. They are found in fermenting animal and plant products where carbohydrates are available; they are also found in the mouth, vagina, and intestinal tract of various warm-blooded animals, including humans. Only a few species are pathogenic. The type genus is Lactobacillus, which contains 56 species.

lactobacilli (lak-to-ba-sil′i)
Plural of lactobacillus.

lactobacillic acid (lak′to-ba-sil′ik)
A major constituent of the lipids of lactobacilli; notable for the presence of a cyclopropane ring in the molecule.

Lactobacillus (lak-to-ba-sil′us)
A genus of microaerophilic or anaerobic, nonsporeforming, ordinarily nonmotile bacteria (family Lactobacillaceae) containing Gram-positive curved or straight rods that vary from long and slender cells to short coccobacilli; chains are commonly produced especially in the later part of the logarithmic phase of growth. These organisms possess complex nutritional requirements, generally characteristic for each species; metabolism is fermentative and at least half of the end product is lactic acid. They are found in dairy products, effluents of grain and meat products, water, sewage, beer, wine, fruits and fruit juices, pickled vegetables, and in sourdough and mash, and are part of the normal flora of the mouth, intestinal tract, and vagina of many warm-blooded animals, including humans; as normal flora, they produce bacterocidins protective against pathogenic bacteria; rarely are they pathogenic. The type species is L. delbrueckii. [lacto- + bacillus] L. acidophilus a bacterial species found in the feces of milk-fed infants and also in the feces of older persons on a high milk-, lactose-, or dextrin-containing diet. L. brevis a bacterial species widely distributed in nature, especially in plant and animal products; it is also found in the mouth and intestinal tract of humans and rats. L. buchneri a bacterial species widely distributed in fermenting substances. L. bulgaricus a bacterial species used in the production of yogurt. L. casei a bacterial species found in milk and cheese. L. catenaformis an anaerobic bacterial species found in the intestines and pulmonary cavities of humans. L. crispatus a bacterial species found in pus from a dental abscess. L. curvatus a bacterial species found in cow dung, dairy barn air, silage, milk, and in a case of endocarditis. L. delbrueckii a bacterial species found in fermenting vegetables and grain mashes; it is the type species of the genus L.. L. fermentum a bacterial species found widely distributed in nature, especially in fermenting plant and animal products. Also found in the mouth of human beings. L. jensenii a bacterial species isolated from human sources such as vaginal discharge and blood clot. L. plantarum a bacterial species found in dairy products and environments, fermenting plants, silage, sauerkraut, pickled vegetables, spoiled tomato products, sour dough, cow dung, and the human mouth, intestinal tract, and stools. L. salivarius a bacterial species found in the mouth and intestinal tract of the hamster, the mouth of humans, and the intestinal tract of the hen. L. trichodes a bacterial species found in wines containing 20% ethanol and in lees in California, Australia, France, and Spain; in California this organism is commonly referred to as the hair bacillus, cottony bacillus, cottony mold, or Fresno mold.

lactobacillus (lak-to-ba-sil′us)
A vernacular term used to refer to any member of the genus L..

lactobezoar (lak′to-be′zor)
A bezoar attributed to enriched calcium or casein content in some formulas prepared for premature infants. [lacto- + bezoar]

lactobutyrometer (lak′to-bu-ti-rom′e-ter)
A type of lactocrit. [lacto- + G. boutyron, butter, + metron, measure]

lactocele (lak′to-sel)
SYN: galactocele. [lacto- + G. kele, tumor]

lactochrome (lak′to-krom)
SYN: lactoflavin (1) .

lactocrit (lak′to-krit)
An instrument used to estimate the amount of butterfat in milk. [lacto- + G. krino, to separate]

lactodensimeter (lak′to-den-sim′e-ter)
A type of galactometer. [lacto- + L. densus, thick, + G. metron, measure]

lactoferrin (lak′to-far-in)
A transferrin found in the milk of several mammalian species and thought to be involved in the transport of iron to erythrocytes; relatively high concentrations are found in human milk.

lactoflavin (lak′to-fla-vin)
1. The flavin in milk. SYN: lactochrome. 2. SYN: riboflavin.

lactogen (lak′to-jen)
An agent that stimulates milk production or secretion. [lacto- + G. -gen, producing] human placental l. (HPL) l. isolated from human placentas and structurally similar to somatotropin; its biologic activity weakly mimics that of somatotropin and prolactin; secreted into maternal circulation; a deficiency of HPL during pregnancy leads to children having abnormal intrauterine and postnatal growth. SYN: choriomammotropin, chorionic “growth hormone-prolactin”, human chorionic somatomammotropic hormone, human chorionic somatomammotropin, placenta protein, placental growth hormone, purified placental protein.

lactogenesis (lak-to-jen′e-sis)
Milk production. [lacto- + G. genesis, production]

lactogenic (lak-to-jen′ik)
Pertaining to lactogenesis.

lactoglobulin (lak-to-glob′u-lin)
The globulin present in milk, making up 50–60% of bovine whey protein.

lactometer (lak-tom′e-ter)
SYN: galactometer. [lacto- + G. metron, measure]

lactonase (lak′to-nas)
SYN: gluconolactonase.

lactone (lak′ton)
An intramolecular organic anhydride formed from a hydroxyacid by the loss of water between a hydroxyl and a –COOH group; a cyclic ester.

lactoperoxidase (lak′to-per-oks′i-das)
A peroxidase obtained from milk. It also catalyzes the oxidation of iodide to iodine.

lactoprotein (lak-to-pro′ten)
Any protein normally present in milk.

lactorrhea (lak-to-re′a)
SYN: galactorrhea. [lacto- + G. rhoia, a flow]

lactoscope (lak′to-skop)
SYN: galactoscope. [lacto- + G. skopeo, to view]

lactose (lak′tos)
A disaccharide present in mammalian milk, occurring naturally as α- and β-l.; obtained from cow's milk and used in modified milk preparation, in food for infants and convalescents, and in pharmaceutical preparations; large doses act as an osmotic diuretic and as a laxative. Human milk contains 6.7% l.. SYN: milk sugar, saccharum lactis. l. synthase the enzyme responsible for the synthesis of l., catalyzing the reaction between UDP-galactose and d-glucose to l. and UDP.

lactosuria (lak′to-soo′re-a)
Excretion of lactose (milk sugar) in the urine; a common finding during pregnancy and lactation, and in newborns, especially premature babies. [lactose + G. ouron, urine, + -ia]

lactotherapy (lak-to-thar′a-pe)
SYN: galactotherapy.

Older term for prolactin-producing.

lactotropin (lak-to-tro′pin)
SYN: prolactin.

lactovegetarian (lak′to-vej-e-ta′re-an)
1. One who lives on a mixed diet of milk and milk products, eggs, and vegetables, but eschews meat. 2. A vegetarian who consumes milk and dairy products but not eggs or meats or seafood.

lactoylglutathione lyase (lak′to-il-gloo-ta-thi′on)
Glyoxalase I;a lyase cleaving S-d-lactoylglutathione to glutathione and methylglyoxal. SYN: aldoketomutase, ketone-aldehyde mutase, methylglyoxalase.

lactulose (lak′too-los)
A synthetic disaccharide used to treat hepatic encephalopathy and chronic constipation.

lacuna, pl .lacunae (la-koo′na, -koo′ne)
1. [TA] A small space, cavity, or depression. 2. A gap or defect. 3. An abnormal space between strata or between the cellular elements of the epidermis. 4. SYN: corneal space. [L. a pit, dim. of lacus, a hollow, a lake] cartilage l. a cavity within the matrix of cartilage, occupied by a chondrocyte. SYN: cartilage space. cerebral l. a small circumscribed loss of brain tissue caused by occlusion of one of the small penetrating arteries. SYN: l. cerebri. l. cerebri SYN: cerebral l.. Howship lacunae tiny depressions, pits, or irregular grooves in bone that is being resorbed by osteoclasts. SYN: resorption lacunae. intervillous l. one of the blood spaces in the placenta into which the chorionic villi project. lateral lacunae [TA] SYN: lateral lacunae of superior sagittal sinus. lacunae laterales [TA] SYN: lateral lacunae of superior sagittal sinus. lateral lacunae of superior sagittal sinus [TA] lateral expansions of the superior sagittal sinus of the dura mater, often increasing in width with advancing age until, in the very old, they may extend two cm lateral to the midline; the endothelium-lined lumens of the lacunae are usually reduced to a spongelike labyrinth by numerous arachnoid granulations and dural trabeculae. SYN: lacunae laterales [TA] , lateral lacunae [TA] , lateral lakes, lateral venous lacunae, parasinoidal sinuses. lateral venous lacunae SYN: lateral lacunae of superior sagittal sinus. l. magna a recess on the roof of the fossa navicularis of the penis, formed by a fold of mucous membrane, the valve of the navicular fossa. Morgagni l. SYN: urethral l.. muscular l. SYN: muscular space of retroinguinal compartment. l. musculorum SYN: muscular space of retroinguinal compartment. l. musculorum retroinguinalis SYN: muscular space of retroinguinal compartment. osseous l. a cavity in bony tissue occupied by an osteocyte. pharyngeal l. a depression near the pharyngeal opening of the pharyngotympanic (auditory) tube. SYN: l. pharyngis. l. pharyngis SYN: pharyngeal l.. resorption lacunae SYN: Howship lacunae. trophoblastic l. one of the spaces in the early syncytiotrophoblastic layer of the chorion before the formation of villi; in human embryos maternal blood enters these spaces by the 10th day; with the differentiation of the chorionic villi they become intervillous spaces, sometimes called intervillous lacunae. urethral l. [TA] one of a number of little recesses in the mucous membrane of the spongy urethra into which empty the ducts of the urethral glands. SYN: l. urethralis [TA] , Morgagni l.. l. urethralis, pl .lacunae urethrales [TA] SYN: urethral l.. vascular l. SYN: vascular space of retroinguinal compartment. l. vasorum SYN: vascular space of retroinguinal compartment. l. vasorum retroinguinalis [TA] SYN: vascular space of retroinguinal compartment.

lacunar (la-koo′nar)
Relating to a lacuna.

lacunule (la-koo′nool)
A very small lacuna. [Mod. L. lacunula, dim. of L. lacuna]


. . . Feedback