Difficulty in micturition, with straining to void; urine may be passed intermittently with pain and tenesmus. [G. stranx (strang-), something squeezed out, a drop, + ouron, ...
1. A strip of adhesive plaster. 2. To apply overlapping strips of adhesive plaster. [A.S. stropp]
Gustav A., German physiologist, *1848. See S. test.
The process or result of separating a sample into subsamples according to specified criteria such as age or occupational groups. [L. stratum, layer, + facio, to make]
Arranged in the form of layers or strata.
SYN: tomography. [L. stratum, layer, + G. graphe, a writing]
One of the layers of differentiated tissue, the aggregate of which forms any given structure, such as the retina or the skin. SEE ALSO: lamina, layer. [L. sterno, pp. stratus, ...
The stratum corneum as a rule refers to the outermost layer of the epidermis, which is itself the outer layer of the skin. The full name of the stratum corneum of the skin is ...
Isidore, French physician, 1845–1896. See S. reaction, S. sign.
Lotte, U.S. pathologist, *1913. See Churg-S. syndrome.
See Gerstmann-Sträussler-Scheinker syndrome.
A line, stria, or stripe, especially one that is indistinct or evanescent. [A.S. strica]
- angioid streaks calcification of lamina basalis choroideae visible in the ...
- hair streams the curved lines along which the hairs are arranged on the head and various parts of the body, especially noticeable in the fetus. SYN: flumina ...
SYN: camptodactyly. [G. streblos, twisted, + daktylos, finger]
George L., U.S. embryologist, 1873–1948. See S. developmental horizon(s).
Streeter developmental horizon
A term borrowed from geology and archeology by Streeter to define 23 developmental stages in young human embryos, from fertilization through the first 2 months; each horizon ...
Enrico Bernard, Swiss ophthalmologist, *1908. See Hallermann-S. syndrome, Hallermann-S.-François syndrome.
1. The quality of being strong or powerful. 2. The degree of intensity. 3. The property of materials by which they endure the application of force without yielding or breaking.
Very commonly used shortened form of Streptococcus, a very common and important group of bacteria. See Streptococcus
Strep test, rapid
A diagnostic test commonly used to demonstrate whether streptococcus bacteria ("strep") are present in the throat. A throat infection with strep needs to be treated with an ...
1. Generally, the perception of objects reversed as if in a mirror. 2. Specifically, difficulty in distinguishing written or printed letters that extend in opposite directions ...
Rarely used term for a noise, usually an auscultatory sound. [L.]
A bacterial protein used as a probe in immunologic assays because of its strong affinity and specificity for biotin; s. is used as a bridge to link a chromogen to a ...
Curved or twisted (usually relating to organisms thus described). [G. streptos, twisted, fr. strepho, to twist]
A genus of nonmotile, non–spore-forming, aerobic to facultatively anaerobic bacteria (family Bacteroidaceae) containing Gram-negative, pleomorphic cells that vary from short ...
A methylamino disaccharide ( streptose + N-methyl-l-glucosamine), with the oxygen link between C-2 of streptose and C-1 of the glucosamine; with streptidine, it forms ...
Infection of humans and higher primates with the nematode Mansonella streptocerca.
Relating to or caused by any organism of the genus Streptococcus.
The presence of streptococci in the blood. SYN: streptosepticemia. [ streptococcus + G. haima, blood]
Relating to or caused by any organism of the genus Streptococcus.
A group of bacteria, familiarly known as strep, that can (and do) cause a multitude of diseases. The name comes from the Greek strepto- meaning twisted + kokkos meaning berry, ...
Streptococcus pneumoniae (pneumococcus)
A type of bacterium that comes in pairs and is shaped like a lancet (a surgical knife with a short wide two-edged blade). Pneumococcus is the leading cause of bacterial ...
The bacterial cause of strep throats, impetigo, rheumatic fever, scarlet fever, glomerulonephritis, and invasive fasciitis. A common bacteria of the skin.
Streptococcus, group B
A major cause of infections, including infections involving the pregnant woman and her newborn infant. Strep B can infect the mother’s uterus, placenta, and urinary tract; in ...
A “dornase” ( deoxyribonuclease) obtained from streptococci; used with streptokinase to facilitate drainage in septic surgical conditions.
An extracellular metalloenzyme from hemolytic streptococci that cleaves plasminogen, producing plasmin, which causes the liquefaction of fibrin (same activity as ...
A purified mixture containing streptokinase, streptodornase, and other proteolytic enzymes; used by topical application or by injection into body cavities to remove clotted ...
A hemolysin produced by streptococci.
- s. O a hemolysin that is produced by β-hemolytic streptococci and is hemolytically active only in the reduced state; anti-s. O ...
A genus of nonmotile, aerobic, Gram-positive bacteria (family Streptomycetaceae) that grow in the form of a many-branched mycelium; conidia are produced in chains on aerial ...
A family of aerobic Gram-positive bacteria (order Actinomycetales) that produce a vegetative mycelium which does not fragment into bacillary or coccoid forms; they produce ...
A term used to refer to a member of the genus Streptomyces; it is sometimes improperly used to refer to any member of the family Streptomycetaceae.
An antibiotic agent obtained from Streptomyces griseus that is active against the tubercle bacillus and a large number of Gram-positive and Gram-negative bacteria; also used in ...
Old term for streptococcemia. [ strepto- + G. mykes, fungus, + -osis, condition]
An unusual l-pentose that is a component of streptobiosamine, hence of streptomycin. SYN: streptofuranose.
An antineoplastic agent used in the treatment of metastatic islet-cell carcinoma of the pancreas. SYN: streptozotocin.
Forces from the outside world impinging on the individual. Stress is a normal part of life that can help us learn and grow. Conversely, stress can cause us significant problems. ...
A device that relieves the abutment teeth, to which a fixed or removable partial denture is attached, of all or part of the forces generated by occlusal function.
A supplement to the routine exercise cardiac stress test. During stress echocardiography, the sound waves of ultrasound are used to produce images of the heart at rest and at the ...
Stress exercise thallium scan
A method of examining the heart to obtain information about the blood supply to the heart muscle. Special cameras take a series of pictures of the heart. A radioactive substance ...
A mechanical defect, such as a hole, in bone or other materials, that concentrates stress in the area and increases the risk of failure of the bone or material at that site.
Osteopenia occurring in bone as the result of removal of normal stress from the bone by an implant.
Stress test, pharmacologic
There are a diversity of pharmacologic stress tests. Here this refers specifically to a pharmacologic cardiac stress test in which certain medications are administered that ...
Stress test, physiologic
Although there can be a diversity of physiologic stress tests, this refers here to a physiologic cardiac stress test in which certain medications are administered that stimulate ...
Stress testing, exercise cardiac
The exercise cardiac stress testing (ECST) is the most widely used cardiac (heart) screening test. The patient exercises on a treadmill according to a standardized protocol, ...
Stress testing, radionucleide
This procedure involves injecting a radioactive isotope (typically thallium or cardiolyte) into the patient’s vein after which an image of the patient’s heart becomes visible ...
An exercise to stretch the quadriceps muscle, the large muscle in the front of the thigh. To do this exercise, lie on your left side, on the floor. Your hips should be lined up ...
1. A litter, usually a sheet of canvas stretched to a frame with four handles, used for transporting the sick or injured. 2. A cart with four wheels and a flat top for the ...
1. A stripe, band, streak, or line, distinguished by color, texture, depression, or elevation from the tissue in which it is found. SYN: striation (1). 2. SYN: striae cutis ...
Relating to the corpus striatum.
Striped; marked by striae. [L. striatus, furrowed]
1. SYN: stria (1). 2. A striate appearance. 3. The act of streaking or making striae.
- basal striations the vertical infranuclear striations due to the infolded plasma ...
Referring to the efferent connection of the striatum with the substantia nigra.
Part of the basal ganglia of the brain. The basal ganglia are interconnected masses of gray matter located in the interior regions of the cerebral hemispheres and in the upper ...
An abnormal narrowing of a body passage, especially a tube or a canal. The stricture may be due, for example, to scar tissue or to a tumor. Stricture refers to both the process of ...
Stricture, esophagus, acute
A narrowing or closure of the normal opening of the swallowing tube leading to the stomach, usually caused by scarring from acid irritation. Acute, complete obstruction of the ...
Surgical procedure for widening a structured segment of intestine that involves incision and closure in opposing directions. [ stricture + G. plastos, formed]
Surgical opening or division of a stricture. [ stricture + G. tome, incision]
Creaking; grating; harsh-sounding; denoting an auscultatory sound or rale. [L. stridens, pres. p. of strideo, to creak]
A high-pitched, noisy respiration, like the blowing of the wind; a sign of respiratory obstruction, especially in the trachea or larynx. [L. a harsh, creaking sound]
- congenital ...
Having a shrill or creaking sound. [L. stridulus, fr. strideo, to creak, to hiss]
A slender cord or cordlike structure.
- auditory strings bundles of parallel filaments in the zona pectinata of the lamina basilaris of the cochlea; the length of the strings ...
The narrow central area of the utricular macula where the orientations of the tallest stereocilia and kinocilia change. [L. stria, stripe, + -ola, dim. suffix]
Striopallidodentate (SPD) calcinosis, a condition first described in 1930 by T. Fahr and therefore called Fahr syndrome, is a genetic (inherited) neurological disorder ...
1. To express the contents from a collapsible tube or canal, such as the urethra, by running the finger along it. SYN: milk (4). 2. Subcutaneous excision of a vein in its ...
1. In anatomy, a streak, line, band, or stria. 2. In radiography, a linear opacity differing in density from the adjacent parts of the image; usually represents the tangential ...
vein s. an instrument used to remove a vein by tying the vein at one end and pulling it, tearing its branches, and thus, stripping it out of the body.
Removal, often of a covering.
- membrane s. separation of gestational membranes from the lower uterine segment by insertion of a finger through the cervical os, to initiate the ...
A chain of segments, less the scolex and unsegmented neck portion, of a tapeworm; in the monozoic tapeworms ( subclass Cestodaria and some members of the subclass Cestoda), ...
A taenioid tapeworm larva of the cysticercus type, but with a conspicuous segmented neck, small terminal bladder, and everted scolex; the larval form of Taenia taeniaeformis, ...
Resembling a chain of segments of a tapeworm. [G. strobile, strobile, + eidos, resemblance]
An electronic instrument that produces intermittent light flashes of controlled frequency; used to influence electrical activity of the cerebral cortex.
Pertaining to the illusion of motion, retarded or accelerated, produced by visual images observed intermittently in rapid succession. [G. strobos, a twisting around, fr. strepho, ...
Endoscopy performed with an intermittent light at a frequency that approximates the frequency of movement of the object visualized so that it appears to be motionless; useful in ...
1. Any acute clinical event, related to impairment of cerebral circulation, that lasts more than 24 hours. SYN: apoplexy, brain attack. 2. A harmful discharge of lightning, ...
The amount of blood pumped by the left ventricle of the heart in one contraction. The stroke volume is not all of the blood contained in the left ventricle. The heart does not ...
Heat stroke can be LIFE-THREATENING! Victims of heat stroke almost always die, so immediate medical attention is essential when problems first begin. A person with heat stroke has ...
The nonverbal fondling and nurturance accorded infants or the nonverbal and verbal forms of acceptance, reassurance, and positive reinforcement accorded to children and adults ...
The supportive framework of an organ (or gland or other structure). The stroma is usually composed of connective tissue. It is distinct from the parenchyma, which consists of ...
Stromatic; relating to the stroma of an organ or other structure. SYN: stromic.
An insoluble protein in the stroma of erythrocytes.
Destruction of the enveloping membrane of a cell, such as a red blood cell. [stroma + G. lysis, dissolution]
An instrument for measuring the quantity of blood that flows per unit of time through a blood vessel. [Ger. Strom, stream, + Uhr, clock]
- Ludwig s. one of the first devices for ...
Edward K., Jr., U.S. psychologist, *1884. See S. vocational interest test.
Common name for members of the family Strongylidae. [G. strongylos, round]
A family of parasitic nematode worms (order Strongyloidea) including the genera Strongylus and Oesophagostomum. [see Strongyloides]
A superfamily of strongyle nematode parasites including the genera Ancyclostoma, Necator, Ostertagia, Haemonchus, and Strongylus, as well as the tapeworms of fowl, the ...
The threadworm, a genus of small nematode parasites (superfamily Rhabditoidea), commonly found in the small intestine of mammals (particularly ruminants), that are characterized ...
Infection with soil-borne nematodes of the genus Strongyloides, considered to be a parthenogenetic parasitic female. Larvae passed to the soil develop through four larval ...
Disease caused by infection with a species of the nematode Strongylus; effects may be extreme from worm-caused lesions, nodules, and aneurysms.
The palisade worm, a genus of large strongyle nematodes ( subfamily Strongylinae, family Strongylidae) parasitic in horses and other equids, and the cause of strongylosis. [G. ...
A metallic element, atomic no. 38, atomic wt. 87.62; one of the alkaline earth series and similar to calcium in chemical and biological properties. Various salts of s. are used ...
A radioactive strontium isotope with a half-life of 64.84 days; used in bone imaging.
A radioactive strontium isotope with a half-life of 2.80 h; used in bone imaging.
A radioactive strontium isotope; a β emitter with a half-life of 50.52 days; used as a tracer in studies of strontium absorption by the body, strontium incorporation in ...
A radioactive strontium isotope; a β emitter with a half-life of 29.1 years; a major component (about 5%) of the uranium fission products; it is incorporated into bone tissue ...
A glycoside or mixture of glycosides from Strophanthus kombé; a cardiac tonic, like ouabain (G-s.); extremely toxic.
A genus of vines of east Africa (family Apocynaceae); the dried ripe seeds of S. kombé or S. hispidus contain the cardiac glycoside strophanthin and were used as an arrow ...
Condition characterized by a congenitally distorted head and face, in which there is a tendency toward cyclopia and malformation of the oral region. [G. strophe, a twist, + ...
Severe form of a congenital ventral fissure, extremely rare in humans. [G. strophe, a twist, + soma, body]
- structurae oculi accessoriae [TA] SYN: accessory visual structures, under structure.
Relating to the structure of a part; having a structure. SYN: anatomical (2).
The study of the proteome, the three-dimensional structures of thousands upon thousands of proteins, in fact, all of the proteins produced by a species. In the Human Genome ...
A fixed lateral (sideway) curve of the spine. Structural scoliosis often occurs from unknown factors without reference to other physical problems (idiopathic scoliosis). It ...
A branch of psychology interested in the basic structure and elements of consciousness.
1. The arrangement of the details of a part; the manner of formation of a part. 2. A tissue or formation made up of different but related parts. 3. In chemistry, the specific ...
1. SYN: goiter. 2. Formerly, any enlargement of a tissue. [L. a scrofulous tumor, fr. struo, to pile up, build]
- s. aberrata SYN: aberrant goiter.
- s. colloides SYN: ...
Resembling a goiter. [ struma + L. forma, form]
Inflammation, with swelling, of the thyroid gland. SEE ALSO: thyroiditis. [ struma + G. -itis, inflammation]
Denoting or characteristic of a struma.
Ernst Adolf von, German physician, 1853–1925. See S. disease, S. phenomenon, S. reflex, Fleischer-S. ring, S.- Marie disease, Marie-S. disease.
The hexahydrate of magnesium ammonium phosphate; found in some renal calculi. Cf.:bobierrite, newberyite. [H.C.G. von Struve, Russian diplomat + -ite]
An alkaloid from Strychnos nux-vomica; colorless crystals of intensely bitter taste, nearly insoluble in water. It stimulates all parts of the central nervous system, and was ...
Chronic strychnine poisoning, the symptoms being those that arise from central nervous system stimulation; the first signs are tremors and twitching, progressing to severe ...
A genus of tropical shrubs or trees (family Loganiaceae); most South American species contain chiefly quaternary neuromuscular blocking alkaloids, e.g., curare; the African, ...
Garold V., U.S. pathologist, *1896. See S.-Halbeisen syndrome.
Homer H., U.S. orthopedic surgeon. See S. frame, S. saw.
Commonly used abbreviation for "sequence tagged site." A short (200 to 500 base pair) DNA sequence that occurs but once in the genome and whose location and base sequence are ...
Abbreviation for sequence-tagged sites, under site.
Surname of a patient in whom the S. or S.- Prower factor was first discovered.
Pseudonym for William Sealy Gosset, British statistician, and chemist, 1876–1937. See S.'s t test.
Research, detailed examination, and/or analysis of an organism, object, or phenomena. [L. studium, s., inquiry]
- analytic s. in epidemiology, a s. designed to examine ...
Study, antro-duodenal motility
An antro-duodenal motility study is a study for detecting and recording the contractions of the muscles of the stomach and the first part of the small intestine, the duodenum. It ...
A study done at one time, not over the course of time. A cross-sectional study a disease such as AIDS might be designed to learn its prevalence and distribution within the ...
A type of clinical trial in which the study subjects receive each treatment in a random order. In this type of study, every patient serves as his or her own control.
Study, electrophysiologic (EPS)
A test of the electrical conduction system of the heart (the system that generates the heart beat). EPS is done by threading thin plastic tubes (catheters) into a vein where the ...
A landmark medical research project begun in 1948 in which some 12,000 residents of the town of Framingham, Massachusetts were enrolled in a study designed to gather medical data ...
Study, gastric emptying
A gastric emptying study evaluates the emptying of food from the stomach. For a gastric emptying study, a patient eats a meal in which the solid food, liquid food or both are ...
A study aimed at establishing linkage between genes. Linkage is the tendency for genes and other genetic markers to be inherited together because of their location near one ...
A study done over the passage of time. For example, a longitudinal study of children with Down syndrome (trisomy 21) might involve the study of 100 children with this condition ...
A study to test a drug, procedure or medical treatment in animals. The aim is to collect data in support of safety. Preclinical studies are required before clinical trials can ...
Study, stomach emptying
Also called a gastric emptying study, this test evaluates the emptying of food from the stomach. For a gastric emptying study, a patient eats a meal in which the solid food, ...
1. The extremity of a limb left after amputation. 2. The pedicle remaining after removal of the tumor attached to it. [M.e. stumpe]
To stupefy; to render unconscious by cerebral trauma. [A.S. stunian, to make a loud noise]
A compress or cloth wrung out of hot water, usually impregnated with turpentine or other irritant, applied to the surface to produce counterirritation. [L. stupa, oakum, tow]
A state of impaired consciousness in which the individual shows a marked diminution in reactivity to environmental stimuli and can be aroused only by continual stimulation. [L. ...
Relating to or marked by stupor. SYN: carotic.
William A., English physician, 1850–1919. See S.- Weber syndrome, S.- Weber disease.
A congenital, but not inherited, disorder that affects the skin, the neurological system, and sometimes the eyes and internal organs. The main sign of Sturge-Weber syndrome is a ...
Johann C., 1635–1703. See S. conoid, S. interval.
Arnold, U.S. gynecologist, 1861–1934. See S. operation.
To speak dysfluently; to enunciate certain words with difficulty and with frequent halting and repetition of the initial consonant of a word or syllable. [frequentative of stut, ...
A phonatory or articulatory disorder, characteristically beginning in childhood, with intense anxiety about the efficiency of oral communications, and characterized by ...
SYN: hordeolum externum.
- meibomian s. SYN: hordeolum internum.
- zeisian s. inflammation of one of Zeis glands.
1. A flexible metallic rod inserted in the lumen of a flexible catheter to stiffen it and give it form during its passage. 2. A slender probe. SYN: style, stylus (3), stilus. ...
SYN: styloid. [L. stilus (stylus), a stake, + forma, form]
Styloid (specifically the styloid process of the temporal bone). [G. stylos, pillar, post]
Relating to the styloid process and the tongue. See s. (muscle).
Relating to the styloid process of the temporal bone and to the hyoid bone. SYN: stylohyoid (1).
1. SYN: stylohyal. 2. Relating to the s. muscle.
Peg-shaped; denoting one of several slender bony processes. See s. process of third metacarpal bone, s. process of temporal bone, s. process of radius, s. process of ulna. SYN: ...
Relating to the styloid process of the temporal bone and the mandible; denoting the s. ligament. SYN: stylomaxillary.
Relating to the styloid and the mastoid processes of the temporal bone; denoting especially a small artery and a foramen.
The proximal intermediate segment of the limb skeleton, the humerus and the femur, in the embryo. [ stylo- + G. podion, small foot]
Relating to the styloid process of the temporal bone and the uvula.
A peg-shaped bony outgrowth. [G. stylos, post, + osteon, bone, + phyton, growth]
1. Any pencil-shaped structure. 2. A pencil-shaped medicinal preparation for external application; e.g., a medicated bougie, or a pencil or stick of silver nitrate or other ...
A tampon. [G. s., tow]
1. Having an astringent or hemostatic effect. 2. An astringent agent used topically to stop bleeding. SYN: hemostyptic. [G. styptikos, astringent]
An orally effective skeletal muscle relaxant with a relatively long duration of action.
Phenylethylene; the monomer from which polystyrenes, plastics, and synthetic rubber are made; together with divinylbenzene (for cross-linking), it is the basis of many synthetic ...
C9H10O; obtained from storax by distillation with potassium hydroxide; used as a deodorant in 12% glycerin solution, and as a decolorizing agent in histology. SYN: cinnamic ...
Beneath, less than the normal or typical, inferior. Cf.:hypo-. [L. sub, under]
Beneath the abdominal, as distinguished from the pelvic, peritoneum. SYN: subperitoneoabdominal.
A mixture or complex of a base and its acetate.
Rather recent onset or somewhat rapid change. The term “subacute” is used in contrast to acute which indicates very sudden onset or rapid change and chronic which indicates ...
Subacute sclerosing panencephalitis (SSPE)
A chronic brain disease of children and adolescents that occurs months to often years after an attack of measles, causing convulsions, motor abnormalities, mental retardation ...
A condition of insufficient nourishment. SYN: hypoalimentation.
Narrowing of the left ventricle of the heart just below the aortic valve through which blood must pass on its way up into the aorta. The narrowing cuts the flow of blood. ...
Literally, beneath the arachnoid, the middle of three membranes that cover the central nervous system. In practice, subarachnoid usually refers to the space between the ...
Bleeding within the head into the space between two membranes that surround the brain. The bleeding is beneath the arachnoid membrane and just above the pia mater. (The ...
Beneath an areola; especially the areola of the mamma.
Pertaining to particles making up the intraatomic structure; e.g., protons, electrons, neutrons.
Below an auricle; especially the concha or pinna of the ear.
Below the axis of the body or any part.
Below the axillary fossa. SYN: infraaxillary.
Beneath any base or basal membrane.
Below the calcarine fissure; denoting the lingual gyrus.
Below the corpus callosum; denoting either the s. gyrus or the fasciculus.
A mixture or complex of a base and its carbonate.
Lying ventral to the anterior or posterior cardinal veins in the embryo.
Below the cecum; denoting a fossa.
Subliminal perception as in the reaction to a stimulus not fully perceived. See subliminal. [ sub- + L. -ceptum, perceived]
The chloride of a series that contains proportionally the greatest amount of the other element in the compound; e.g., s. of mercury is Hg2Cl2, whereas chloride or perchloride of ...
Beneath or below the cartilages of the ribs.
In biologic classification, a division between class and order.
1. Beneath the clavicle. SYN: infraclavicular. 2. Pertaining to the s. artery or vein.
Denoting the presence of a disease without manifest symptoms; may be an early stage in the evolution of a disease.
An illness that stays below the surface of clinical detection. A subclinical disease has no recognizable clinical findings. It is distinct from a clinical disease, which has ...
The process by which a DNA clone is cleaved into smaller pieces and recloned; analysis of overlapping regions of these smaller DNA fragments can confirm the entire sequence of ...
Below the collateral fissure; denoting a cerebral convolution, or gyrus.
A very common cause of a painless bloody eye usually first noticed by somebody else or by the person with it when they look in the mirror. The bleeding results from a break in a ...
1. Not wholly conscious. 2. Denoting an idea or impression which is present in the mind, but of which there is at the time no conscious knowledge or realization. 3. That part of ...
1. Partial unconsciousness. 2. The state in which mental processes take place without the conscious perception of the individual.
Any part of the brain lying below the cerebral cortex, and not itself organized as cortex.
Relating to the subcortex; beneath the cerebral cortex.
1. Beneath a rib or the ribs. SYN: infracostal. 2. Denoting certain arteries, veins, and nerves.
Pain in the subcostal region. [ subcostal + G. algos, pain]
Nearly, but not frankly, crepitant; denoting a rale.
1. The presence of subcrepitant rales. 2. A sound approaching crepitation in character.
SYN: articularis genus (muscle). [ sub- + L. crus, leg]
Abbreviation for subcutaneous. Subcutaneous means under the skin. It implies just under the skin. With a subcutaneous injection, a needle is inserted just under the skin. A drug ...
1. A culture made by transferring to a fresh medium microorganisms from a previous culture; a method used to prolong the life of a particular strain where there is a tendency to ...
Denoting a dose less than that necessary for a curative effect.