|Medical Dictionary - Dictionary of Medicine and Human Biology|
An instrument for use in dividing a stricture.
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 s. crowing inspiration occurring at birth or within the first few months of life; sometimes without apparent cause and sometimes due to abnormal flaccidity of epiglottis or arytenoids. SYN: laryngeal s.. s. dentium grinding of the teeth. expiratory s. a singing sound due to the semiapproximated vocal folds offering resistance to the escape of air or to tracheal or bronchial obstruction. inspiratory s. a crowing sound during the inspiratory phase of respiration due to pathology involving the upper respiratory tract especially at the epiglottis or larynx. laryngeal s. SYN: congenital s.. s. serraticus a rough grating like the sound of a saw.
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 varies from 64 μm in the basal coil to 480 μm in the apex.
The narrow central area of the utricular macula where the orientations of the tallest stereocilia and kinocilia change. [L. stria, stripe, + -ola, dim. suffix]
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 longitudinal axis, performed with a stripper. 3. Any narrow piece, relatively long and of uniform width. [A.S. strypan, to rob] abrasive s. a ribbon-like piece of linen on one side of which is bonded abrasive particles; used in dentistry for contouring and polishing proximal surfaces of restorations. amalgam s. a linen s. without abrasive used to smooth proximal contours of newly placed amalgam restorations. celluloid s. a clear plastic s. used as a matrix when inserting a cement or resin in proximal cavity preparations of anterior teeth. lightning s. a s. of metal with abrasive on one side, used to open rough or improper contacts of proximal restorations.
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 image of a planar structure such as the pleura or peritoneum. SEE ALSO: psoas margin. [M.E.] s. of Gennari SYN: line of Gennari. Hensen s. a band on the undersurface of the membrana tectoria of the cochlear duct. inner stripes of renal medulla [TA] the deeper or more central portion of the outer medulla of the kidney, recognizable on sagittal section through the pyramid of a fresh specimen; it is structurally distinct from the outer s. in that it is traversed by thin as well as thick portions (limbs) of nephron tubules. SYN: stria interna medullae renalis [TA] . mallear s. SYN: malleolar stria. Mees stripes SYN: Mees lines, under line. occipital s. [TA] SYN: line of Gennari. outer stripes of renal medulla [TA] the more superficial or more peripheral portion of the outer medulla of the kidney, recognizable on sagittal section through the pyramid of a fresh specimen; it is structurally distinct from the outer s. in that it is traversed by only thick portions (limbs) of nephron tubules. SYN: stria externa medullae renalis [TA] . pleural s. SYN: pleural lines, under line. tracheal wall s. on a chest radiograph, the linear opacity between air in the trachea and in the right upper lobe. vascular s. SYN: stria vascularis of cochlear duct.
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 Ferguson reflex or prostaglandin release from the decidua and hasten labor.
See Schellong-S. phenomenon.
strobila, pl .strobilae (stro′bi-la, -le)
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), it may consist of a single proglottid. [G. stobile, a twist of lint]
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, called Cysticercus fasciolaris. [G. strobile, a twist of lint, + kerkos, tail]
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, to twist, + skopeo, to view]
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 analyzing vocal cord structure and motion.
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, particularly one that affects a human being. 3. A pulsation. 4. To pass the hand or any instrument gently over a surface. SEE ALSO: stroking. 5. A gliding movement over a surface. [A.S. strac] Acute neurologic deficits resulting from circulatory impairment that resolve within 24 hours are called transient ischemic attacks (TIAs); most TIAs last only 15–20 minutes. In contrast, a s. involves irreversible brain damage, the type and severity of symptoms depending on the location and extent of brain tissue whose circulation has been compromised. The outcome of a s. varies from minimal impairment to rapid onset of coma followed quickly by death. S. ranks third as a cause of death in adults in the U.S., after ischemic heart disease and cancer. About 700,000 people a year experience strokes in this country, and at any given time the population includes about 3 million s. survivors. The incidence of s. has gradually declined during the past generation. Risk factors for s. include hypertension, valvular heart disease, atrial fibrillation, hyperlipidemia, diabetes mellitus, cigarette smoking, and a family history of s.. In addition, recent studies have shown that elevation of plasma homocysteine, low circulating levels of folic acid and pyridoxine (vitamin B6), periodontal disease, and chronic bronchitis are all independent risk factors. Ischemic s., which accounts for about 85% of all strokes, is generally caused by atherothrombosis or embolism of a major cerebral artery. Less common causes of ischemic s. include nonatheromatous vascular disease and coagulation disorders. Severe, acute ischemia in nerve tissue triggers cellular changes (calcium influx, protease activation) that can swiftly cause irreversible damage (infarction). Around the infarct zone lies a so-called penumbra of ischemic, electrically silent tissue that may be salvageable by prompt reperfusion. The mortality of ischemic s. is 15–30% within the first 30 days. Hemorrhagic s., which makes up the other 15%, has a graver prognosis, with a 30-day mortality rate of 40–80%. The diagnostic evaluation of the patient with s. includes history, physical examination, blood count, blood chemistries, coagulation profile, electrocardiogram, and imaging studies. While cranial CT is the procedure of choice to identify subarachnoid hemorrhage, MRI is a more sensitive indicator of parenchyal hemorrhage as well as of ischemia and infarction. About 20% of persons initially thought to have had a s. prove to have some other disorder, and as many as 20% of strokes are missed on initial evaluation by emergency department physicians. Early and aggressive treatment is crucial in limiting damage to brain tissue and achieving an optimal outcome. In ischemic s., intravenous administration of tissue plasminogen activator (TPA) within the first 3 hours, with the purpose of dissolving an obstructing thrombus, has been shown to improve overall outcome at 90 days. Limiting factors in the use of thrombolytic therapy are the need to rule out hemorrhagic s. (sometimes difficult with available imaging methods) and the fact that the therapy itself may induce hemorrhage. Intravenous thrombolytic agents other than TPA are not only less effective but also more likely to cause hemorrhage. In limited studies, intraarterial injection of prourokinase up to 6 hours after stoke onset has favorably influenced outcome. During the acute phase of a s., respiratory and circulatory support and attention to fluid and electrolyte balance and nutrition are vitally important. Hypothermia and intravenous administration of heparin and magnesium also improve outcome in selected cases. Long-term consequences may depend on the aggressiveness and persistence of physical therapy and rehabilitation. Effective measures for the prevention of s. include aggressive management of hypertension, hyperlipidemia, and diabetes mellitus, cessation of smoking, and chemoprophylaxis in persons at high risk. Administration of aspirin (acetylsalicylic acid) prophylactically inhibits platelet aggregation by suppressing thromboxane A2. A meta-analysis of randomized controlled trials involving a total of more than 50,000 people indicated that low-dosage aspirin (80–325 mg/day) reduces the risk of ischemic s. by 39 events per 10,000 persons but increases the risk of hemorrhagic s. by 12 events per 10,000 persons. Other studies suggest that aspirin at higher dosage (1.3 g/day in divided doses) protects men but not women from ischemic s. because in women aspirin also suppresses prostacyclin, a natural inhibitor of platelet aggregation. Prophylaxis with other antiplatelet agents (clopidogrel, ticlopidine) is equally effective in men and women and at least as protective as aspirin. In nonvalvular atrial fibrillation, warfarin prophylaxis reduces s. risk by two-thirds. Most studies show that, in persons with carotid artery stenosis of at least 60%, carotid endarterectomy reduces the risk of s.. The National S. Association has recommended adoption of the term brain attack for s., by analogy with the familiar heart attack, to emphasize to the public both the location of the lesion and the urgency of the need for assessment and treatment. See Also tissue plasminogen activator. effective s. the rapid forward movement of cilia. heart s. impact of the apex of the heart against the wall of the chest. heat s. heatstroke. recovery s. the slow return movement of cilia. spinal s. abrupt onset of focal spinal cord dysfunction caused by a disturbance in its blood supply. sun s. sunstroke.
The nonverbal fondling and nurturance accorded infants or the nonverbal and verbal forms of acceptance, reassurance, and positive reinforcement accorded to children and adults either by an individual to himself or herself or to another person in order to satisfy a basic biopsychological need of all developing humans; various psychopathologic conditions are believed to result when such s. is absent or faulty.
stroma, pl .stromata (stro′ma, stro′ma-ta)
1. The framework, usually of connective tissue, of an organ, gland, or other structure, as distinguished from the parenchyma or specific substance of the part. 2. Aqueous phase of chloroplasts; i.e., chloroplast matrix. 3. Archaic term for mitochondrial matrix. [G. s., bed] s. glandulae thyroideae SYN: s. of thyroid gland. s. iridis SYN: s. of iris. s. of iris the delicate vascular connective tissue that lies between the anterior surface of the iris and the pars iridica retinae. SYN: s. iridis. lymphatic s. the network of reticular fibers and associated reticular cells of lymphatic tissue. nerve s. the connective tissue supporting structures of peripheral nerve fibers, consisting of endoneurium, perineurium, and epineurium. s. ovarii SYN: s. of ovary. s. of ovary the fibrous tissue of the medulla of the ovary. SYN: s. ovarii. Rollet s. the colorless s. of the red blood cells. s. of thyroid gland the connective tissue that supports the lobules and follicles of the thyroid gland. SYN: s. glandulae thyroideae. s. of vitreous the delicate framework of the vitreous body embedded in or enclosing the vitrous humor. SYN: s. vitreum. s. vitreum SYN: s. of vitreous.
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 measuring flow in blood vessels. thermo-s. thermostromuhr.
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 lungworms of carnivores, and some of the most important helminth pathogens of humans and domestic animals. [see Strongyloides]
The threadworm, a genus of small nematode parasites (superfamily Rhabditoidea), commonly found in the small intestine of mammals (particularly ruminants), that are characterized by an unusual life cycle that involves one or several generations of free-living adult worms. Human infection is chiefly by S. stercoralis, the small roundworm of man, widespread in all tropical regions, or by S. fuelleborni, a parasite of non-human primates in African and Asian tropics and of humans in African tropics. The subspecies S. fuelleborni kellyi occurs in New Guinea where it causes widespread infection. Fatal infection in 2-month-old infants, possibly infected by transmammary transmission, produces the condition known locally as swollen belly disease or swollen belly syndrome, which causes grossly distended abdomens, invariably fatal in these infants. Other species include S. papillosus in cattle, sheep, and goats, and S. ransomi in swine. [G. strongylos, round, + eidos, resemblance]
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 instars to form free-living adults or develop from first and second free-living stages into infective third-stage strongyliform or filariform larvae, which penetrate the skin or enter the buccal mucosa via drinking water. Infection can occur by larvae of a new generation developed in the soil (indirect cycle), by infective larvae developed without an intervening adult stage (direct cycle), or by larvae that develop directly in the feces within the intestine of the host, penetrate the mucosa, and pass by blood/lung sputum migration back to the intestine (autoreinfection); most serious human infections and nearly all fatalities result from autoreinfection and subsequent disseminated infection, which commonly follow immunosuppression by steroids, ACTH, or other immunosuppressive agents. Autoreinfection also may develop in patients with AIDS. SYN: strongyloidosis.
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. strongylos, round] S. asini a species that occurs in the large intestine of the ass and other wild equids. S. edentatus a bloodsucking species occurring in the cecum and colon of the horse, ass, mule, and zebra. S. equinus a cosmopolitan bloodsucking species found in the cecum and (rarely) colon of horses and other equids. S. radiatus SYN: Cooperia oncophora. S. ventricosus SYN: Cooperia oncophora. S. vulgaris a bloodsucking species found chiefly in the cecum of horses and other equids; in the course of their migration, larvae commonly lodge in the wall of the posterior aorta, causing wall damage and the development of verminous aneurysms in this vessel, especially in the anterior mesenteric arteries.
strontium (Sr) (stron′she-um)
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 therapeutically for their anions; e.g., s. bromide, iodide, lactate. [Strontian, a town in Scotland]
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 bone, etc.
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 where turnover is slow; used in the therapy of certain eye conditions ( e.g., pterygia).
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 poison; the seeds of S. gratus are the botanical source of ouabain. [G. strophos, a twisted cord, + anthos, flower]
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, + kephale, head]
Severe form of a congenital ventral fissure, extremely rare in humans. [G. strophe, a twist, + soma, body]
SYN: structure. structurae oculi accessoriae [TA] SYN: accessory visual structures, under structure.
Relating to the structure of a part; having a structure. SYN: anatomical (2) .
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 connections of the atoms in a given molecule. SYN: structura. [L. structura, fr. struo, pp. structus, to build] accessory structures [TA] parts accessory to the main organ or s.. SYN: accessory organs (1) , adnexa, annexa. accessory visual structures [TA] the eyelids, with lashes and eyebrows, lacrimal apparatus, conjunctival sac, and extrinsic muscles of the eyeball. SYN: structurae oculi accessoriae [TA] , accessory organs of the eye, accessory visual apparatus, adnexa oculi, appendages of eye, organa oculi accessoria. brush heap s. haphazard interlocking of fibrils in a gel or hydrocolloid impression material. chi s. a joint between two DNA duplex molecules. SEE ALSO: chi sequence. cointegrate s. a s. of DNA produced by the fusion of two replicons, one possessing a transposon. complementary structures structures that define one another; E.G., the two strands of duplex DNA. crystal s. the arrangement in space and the interatomic distances and angles of the atoms in crystals, usually determined by x-ray diffraction measurements. denture-supporting structures the tissues, teeth, and/or residual ridges, which serve as the foundation for removable partial or complete dentures. fine s. SYN: ultrastructure. gel s. brush heap s. of fibrils giving firmness to hydrocolloids. Holliday s. SYN: Holliday junction. primary s. in a macromolecule, the sequence of subunits that make up that macromolecule; e.g., the amino acid sequence of a protein. quaternary s. the three-dimensional arrangement and constitution of a multimeric ( I.E., a substance containing more than one biopolymer) macromolecule; E.G., the α2β2 tetramer of hemoglobin A. secondary s. the localized arrangement in space of regions of a biopolymer; often these types of structures are regular and recurring along one dimension; E.G., the α-helix often found in proteins. tertiary s. the three-dimensional configuration of a biopolymer. tuboreticular s. tubules 20–30 nm in length that lie within cisterns of smooth endoplasmic reticulum; observed in connective tissue diseases such as SLE, and in various cancers and virus infections.
struma, pl .strumae (stroo′ma, -me)
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: colloid goiter. Hashimoto s. SYN: Hashimoto thyroiditis. ligneous s. SYN: Riedel thyroiditis. s. lymphomatosa SYN: Hashimoto thyroiditis. s. maligna obsolete term for cancer of the thyroid gland. s. medicamentosa goiter due to the use of some therapeutic agent. s. ovarii a rare ovarian tumor, regarded as teratomatous, in which thyroid tissue has surpassed the other elements; occasionally associated with hyperthyroidism. Riedel s. SYN: Riedel thyroiditis.
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]
strychnine (strik′nin, -nen, -nin)
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 used as a stomachic, an antidote for depressant poisons, and in the treatment of myocarditis. S. blocks the inhibitory neurotransmitter glycine, and thus can cause convulsions. The formerly used salts of s. are s. hydrochloride, s. phosphate, and s. sulfate. It is a potent chemical capable of producing acute or chronic poisoning of humans or animals.
Chronic strychnine poisoning, the symptoms being those that arise from central nervous system stimulation; the first signs are tremors and twitching, progressing to severe convulsions and respiratory arrest.
A genus of tropical shrubs or trees (family Loganiaceae); most South American species contain chiefly quaternary neuromuscular blocking alkaloids, e.g., curare; the African, Asiatic, and Australian species contain tertiary strychnine-like alkaloids ( e.g., strychnine, brucine, and yohimbine-type alkaloids). [G. nightshade]
Garold V., U.S. pathologist, *1896. See S.-Halbeisen syndrome.
Homer H., U.S. orthopedic surgeon. See S. frame, S. saw.
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 associations, commonly putative or hypothesized causal relationships; usually concerned with identifying or measuring the effects of risk factors or with the health effects of specific exposures. blind s. a s. in which the experimenter is unaware of which group is subject to which procedure. case control s. an epidemiologic method that begins by identifying persons with the disease or condition of interest (the cases) and compares their past history of exposure to identified or suspected risk factors with the past history of similar exposures among persons who resemble the cases but do not have the disease or condition of interest (the controls). cohort s. a s. using epidemiologic methods, such as a clinical trial, in which a cohort with a particular attribute ( e.g., smokers, recipients of a drug) is followed prospectively and compared for some outcome ( e.g., disease, cure) with another cohort not possessing the attribute. SYN: follow-up s. (1) . cross-over s. a s. in which the subject is switched from the experimental to the control procedure (or vice versa). cross-sectional s. a s. in which groups of individuals of different types are composed into one large sample and studied at only a single point in time ( e.g., a survey in which all members of a given population, regardless of age, religion, gender, or geographic location, are sampled for a given characteristic or finding in one day). SYN: synchronic s.. diachronic s. SYN: longitudinal s.. double blind s. a s. in which neither the patients, the experimenter, nor any other assessor of the results, knows which individuals are subject to which procedure, thus helping to ensure that the biases or expectations of either will not influence the results. ecologic s. epidemiologic s. in which the units of analysis are populations or groups of people rather than individuals. flow-volume loop studies diagnostic methods in which inspiratory and expiratory flow-volume curves are used to determine the location of an obstruction in the tracheobronchial tree. follow-up s. 1. SYN: cohort s.. 2. s. in which persons exposed to risk or given a designated preventive or therapeutic regimen are observed over a period or at intervals to determine the outcome of the exposure or regimen. Framingham Heart S. the first major U.S. s. of the epidemiology of cardiovascular disease, begun in Framingham, Massachusetts, in 1948 under the auspices of the National Heart Institute (now the National Heart, Lung, and Blood Institute) and still in operation. Initially the Framingham researchers enrolled over 5000 people between the ages of 30 and 60 to s. the evolution of heart disease and identify risk factors for heart attack. In 1971, offspring of the original s. participants began to be enrolled for a second generation of observations.The Framingham s. has had a major impact on the modern understanding of cardiovascular disease and on the prevention and treatment not only of heart attack but also of stroke. During the 1960s, cigarette smoking, elevated cholesterol, hypertension, obesity, and lack of exercise were all statistically confirmed to be risk factors for heart attack. In the succeeding years, the s. has provided invaluable information on triglycerides, LDL cholesterol, mitral valve prolapse, heart failure, atrial fibrillation, stroke, diabetes, cardiovascular risk factors in ethnic minorities, and the role of estrogen in preventing heart attack in postmenopausal women. After a half-century, the s. continues to provide new clues to the causation and prevention of heart disease and other cardiovascular disorders. longitudinal s. a s. of the natural course of life or disorder in which a cohort of subjects is serially observed over a period of time and no assumptions need be made about the stability of the system. SYN: diachronic s.. multivariate studies the use of statistical techniques for the simultaneous investigations of the influence of several variables. synchronic s. SYN: cross-sectional s..
1. The extremity of a limb left after amputation. 2. The pedicle remaining after removal of the tumor attached to it. [M.e. stumpe]
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