Copy of `Dorland's Medical Dictionary`

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Dorland's Medical Dictionary Category: Health and Medicine > Medical Dictionary Date & country: 31/12/2010, USA Words: 39128

sickle cell disorders
any blood disorders associated with the presence of hemoglobin S, including the sickle cell diseases and sickle cell trait.

sickle cell trait
the condition, usually asymptomatic, of being heterozygous for hemoglobin S.

sickle cell–thalassemia
a hereditary anemia involving simultaneous heterozygosity for hemoglobin S and thalassemia.

sicklemia
(sik-le´me-ә) sickle cell anemia.

sickling
(sik´ling) the development of sickle cells in the blood.

sickling test
a method of demonstrationg hemoglobin S and the sickling phenomenon in red blood cells, done by reducing the oxygen concentration to which the red cells are exposed.

sickness
(sik´nis) disease.

sickness rate
morbidity r.

side
(sīd) the lateral (right or left) portion or aspect of the body, a part, or a structure. See also latus (2). dominant side the half of the body in which a person is stronger; writing and eating are usually done with the hand on the dominant side. See also handedness and late...

side chain
a group of atoms attached to a larger chain or to a ring.

side effect
a consequence other than that for which an agent is used, especially an adverse effect on another organ system.

sideroachrestic anemia
sideroblastic anemia any of a heterogenous group of acquired and hereditary anemias with diverse clinical manifestations, commonly characterized by large numbers of sideroblasts in the bone marrow, ineffective erythropoiesis, variable proportions of hypochromic erythrocytes in the peripheral blood, and usually increased le...

sideroblast
(sid´әr-o-blast″) an erythroblast containing ferritin granules in its cytoplasm. adj., sideroblas´tic., adj. ringed sideroblast an abnormal sideroblast containing many iron granules in its mitochondria in a ring shape around the periphery of the nucleus, as s...

siderocyte
(sid´әr-o-sīt″) a red blood cell containing nonhemoglobin iron.

sideroderma
(sid″әr-o-dur´mә) bronzed coloration of the skin due to disordered iron metabolism.

siderofibrosis
(sid″әr-o-fi-bro´sis) fibrosis associated with deposits of iron. adj., siderofibrot´ic., adj.

sideromycin
(sid″әr-o-mi´sin) any of a class of antibiotics that are synthesized by certain actinomycetes and inhibit bacterial growth by interfering with iron uptake.

sideropenia
(sid″әr-o-pe´ne-ә) iron deficiency. adj., siderope´nic., adj.

sideropenic anemia
any of a group of anemias characterized by low levels of iron in the plasma; it includes iron deficiency anemia and the anemias of chronic disorders.

siderophil
(sid´әr-o-fil″) siderophilous. a cell or tissue that has an affinity for iron.

siderophilous
(sid″әr-of´ĭ-lәs) tending to absorb iron.

siderophore
(sid´әr-o-for″) a macrophage containing hemosiderin.

siderosilicosis
(sid″әr-o-sil″ĭ-ko´sis) siderosis with silicosis, a type of pneumoconiosis due to the inhalation of dust containing particles of iron ore and silica. Called also silicosiderosis.

siderosis
(sid″әr-o´sis) a mild type of pneumoconiosis due to the inhalation of iron particles. hyperferremia. the deposit of iron in the tissues; see also hemochromatosis and hemosiderosis. hepatic siderosis hepatic hemosiderosis. urinary side...

siderotic splenomegaly
splenomegaly characterized by marked fibrosis with deposit of iron and calcium (Gamna nodules); called also Gandy-Nanta disease.

SIDS
sudden infant death syndrome.

Siegert sign
in Down syndrome, the little fingers are short and curved inward.

siemens
(S) (se´mәnz) the SI unit of conductance; it is the conductance of one ampere per volt in a body with one ohm resistance.

sieve graft
a skin graft from which tiny circular islands of skin are removed so that a larger denuded area can be covered, the sievelike portion being placed over one area, and the individual islands over surrounding or other denuded areas.

sievert
(se´vәrt) the SI unit of radiation absorbed dose equivalent, defined as that producing the same biologic effect in a specified tissue as 1 gray of high-energy x-rays; 1 sievert equals 100 rem.

sig.
abbreviation for Latin sig´na (mark). Used in prescription writing.

sigh
(si) a long, audible exhalation. an intermittent inflation of the lungs with a large volume from a mechanical ventilator; this is essentially a deep breath that is incorporated into the ventilation cycle. The use of large tidal volumes has replaced the use of the sigh in many settings.

sight
(sīt) vision. a thing seen. far sight hyperopia. near sight myopia. night sight hemeralopia.

sigmatism
(sig´mә-tiz-әm) faulty enunciation or too frequent use of s sounds; see also lisping.

sigmoid
(sig´moid) shaped like the letter C or S. sigmoid colon.

sigmoid arteries
origin, inferior mesenteric artery; branches, none; distribution, sigmoid colon.

sigmoid colon
the final, S-shaped part of the colon, which lies in the pelvis and extends from the pelvic inlet to the third segment of the sacrum. At its proximal end it is an extension of the descending colon, and it ends at the rectum.

sigmoid flexure
sigmoid colon.

sigmoid sinus
either of two venous sinuses of the dura mater, one on either side, continuous with the straight sinus and draining into the internal jugular vein of the same side.

sigmoid veins
veins from the sigmoid colon that empty into the inferior mesenteric vein.

sigmoidectomy
(sig″moi-dek´tә-me) surgical removal of the sigmoid colon.

sigmoidopexy
(sig-moi´do-pek″se) fixation of the sigmoid colon, as for rectal prolapse.

sigmoidoproctostomy
(sig-moi″do-prok-tos´tә-me) surgical anastomosis of the sigmoid colon to the rectum.

sigmoidorectostomy
(sig-moi″do-rәk-tos´tә-me) sigmoidoproctostomy.

sigmoidoscope
(sig-moi´do-skōp) an endoscope for use in sigmoidoscopy.

sigmoidoscopy
(sig″moi-dos´kә-pe) direct examination of the interior of the sigmoid colon.

sigmoidosigmoidostomy
(sig-moi″do-sig-moi-dos´tә-me) anastomosis of two previously remote portions of the sigmoid colon.

sigmoidostomy
(sig″moi-dos´tә-me) surgical creation of an opening from the surface of the body into the sigmoid colon.

sigmoidotomy
(sig″moi-dot´ә-me) incision of the sigmoid colon.

sigmoidovesical
(sig-moi″do-ves´ĭ-kәl) pertaining to or communicating with the sigmoid colon and the urinary bladder.

sign
(sīn) any objective evidence of disease or dysfunction. an observable physical phenomenon so frequently associated with a given condition as to be considered indicative of that condition.

sign test
a nonparametric statistical test based on a null hypothesis that by chance the experimental group should outperform the control group for half the outcome variables and vice versa. Results are scored as a series of pluses and minuses awarded to the experimental group depending on its performance relative to that of the co...

signa
(sig´nә) Latin word meaning write or make a mark; abbreviated S. or sig.. It is used in writing prescriptions and is followed by the signature.

signal node
an enlarged supraclavicular lymph node, often the first sign of a malignant abdominal tumor.

signal symptom
a sensation, aura, or other subjective experience indicative of an impending epileptic or other seizure.

signal-to-noise ratio
the ratio between the amplitude of a signal being measured and that of the noise.

signature
(sig´nә-chәr) the part of a drug prescription that gives directions to be followed by the patient in taking the medicine.

signed rank test
a nonparametric statistical test for ordinal data, comparing two populations of data by examining the differences between matched pairs in the two populations. It is based on the signed rank statistic, calculated by arranging all samples in order without regard to which population they are drawn from, identifying pairs, a...

signet ring cell
a cell whose nucleus has been pressed to one side by an accumulation of mucin in the cytoplasm, such as in a Krukenberg tumor or signet ring cell carcinoma.

signet ring cell carcinoma
a highly malignant mucus-secreting tumor in which the cells are anaplastic, with nuclei displaced to one side by a globule of mucus (signet ring cells).

signet ring sign
in diagnostic imaging, a ring-shaped appearance caused by a pathologic process, such as that seen on radiographs of the wrist in scapholunate dislocation or that caused by a dilated bronchus on computed tomography of the lung. See also cortical ring sign.

signing
(sīn´ing) communication between individuals, especially the deaf, using a system of signs made with the hands and fingers. Called also dactylology.

Silastic
(sĭ-las´tik) trademark for polymeric silicone substances that have the properties of rubber but are biologically inert; used in surgical prostheses.

sildenafil
(sil-den´ә-fil″) an agent that relaxes the smooth muscle of the penis, facilitating blood flow to the corpus cavernosum; used as the citrate salt to treat erectile dysfunction.

silence
(si´lәns) absence of noise; a state of producing no detectable signs or symptoms. electrical silence in electroencephalography and electromyography, absence of measurable electrical activity in tissue.

silencing
(si´lәn-sing) the process of making or keeping something silent. gene silencing negative regulation of gene expression; it includes processes that inhibit transcription of genes, such as DNA methylation, and posttranscriptional processes, such as the degradation of messenger RNA.

silent allele
one that codes for a nonfunctional or undetectable product.

silent area
an area of the brain in which pathologic conditions may occur without producing symptoms.

silent gene
a mutant gene having no detectable phenotypic effect or producing no product.

silent mutation
one that does not affect function or production of the gene product. a more specific use of the term, denoting a change in the DNA sequence of a gene that does not change the amino acid sequence of the protein product, and so does not affect the phenotype.

silent myocardial infarction
a myocardial infarction that happens without pain or other symptoms; this type is often detected only by electrographic or postmortem examination.

Silex sign
furrows radiating from the mouth in congenital syphilis.

Silfverskiöld syndrome
(sil´vәr-shәrld) a form of eccentro-osteochondrodysplasia in which the skeletal changes are chiefly in the extremities and which is inherited as a dominant character.

silica
(sil´ĭ-kә) silicon dioxide, which occurs in nature as agate, amethyst, sand, quartz, chalcedony, cristobalite, and flint; it is one of the major constituents of dental porcelain, and in granular form serves as a dental abrasive and polishing agent. See also silicosis.

silicate
(sil´ĭ-kāt) a salt containing the group Si(OH)4.

silicatosis
(sil″ĭ-kә-to´sis) pneumoconiosis caused by the inhalation of the dust of silicates, particularly aluminum silicate or magnesium silicate (such as in asbestos, kaolin, mica, or talc).

silicoanthracosis
(sil″ĭ-ko-an″thrә-ko´sis) anthracosilicosis.

silicon
(Si) (sil´ĭ-kon) a chemical element, atomic number 14, atomic weight 28.086. silicon dioxide silica.

silicone
(sil´ĭ-kōn) any of a large group of organic compounds comprising alternating silicon and oxygen atoms linked to organic radicals; uses have included wetting agents and surfactants, sealants, coolants, contact lenses, and surgical membranes and implants.

silicone oil
any of various long-chain fluid silicone polymers. Various silicone oils, are injected into the vitreous body to serve as a vitreous substitute during or after vitreoretinal surgery, such as to maintain retinal tamponade in the management of complicated retinal detachment.

silicoproteinosis
(sil″ĭ-ko-pro″tēn-o´sis) a rapidly fatal pneumoconiosis occurring several weeks to months after massive exposure to silica dust, characterized by the presence of proteinaceous fluid in the air spaces.

silicosiderosis
(sil″ĭ-ko-sid″әr-o´sis) siderosilicosis.

silicosis
(sil″ĭ-ko´sis) pneumoconiosis caused by the prolonged breathing in of silica dust, usually occurring as an occupational disease. Nowadays it is most likely to be contracted in such industrial jobs as sandblasting in tunnels and hardrock mining, but it can occur in anyone who is habitually exposed to the dust ...

Silicote
(sil´ĭ-kōt) trademark for preparations of dimethicone, a skin protective.

silicotuberculosis
(sil″ĭ-ko-too-ber″ku-lo´sis) silicosis complicated by pulmonary tuberculosis; called also tuberculosilicosis.

silk
(silk) the protein filament produced by the larvae of various insects; silk obtained from the cocoons of the silkworm Bombyx mori is washed to remove the gum and braided for use as a nonabsorbable suture material. Silk from which the gum has not been removed, known as virgin silk, is used for extremely fine sutures in o...

silo-filler's disease
pulmonary inflammation, often with acute pulmonary edema, due to inhalation of the irritant gases (especially oxides of nitrogen) that collect in recently filled silos.

silver
(Ag) (sil´vәr) a chemical element, atomic number 47, atomic weight 107.870. It is used in medicine for its caustic, astringent, and antiseptic effects. It is also used in dentistry in alloys, in soldering, and as cones to obliterate the root canal. silver nitrate ...

silver cone
silver point.

silver finisher's lung
siderosis in silver finishers, caused by inhalation of iron oxide (from jeweler's rouge) and silver particles. The iron oxide particles are phagocytized and the elastic tissue is stained black by the silver; fibrosis does not occur and pulmonary function is not impaired.

silver fork deformity
the wrist deformity seen in Colles fracture, caused by displacement of the lower fragment of bone.

silver fork fracture
Colles fracture

Silver operation
resection of the medial prominence of the first metatarsal head, medial capsulorrhaphy of the first metatarsophalangeal joint, and sectioning of the adductor tendon; done for hallux valgus.

silver point
in root canal therapy, a tapered and elongated silver plug that is cemented into the canal as a filling. Called also silver cone.

Silver syndrome
(sil´vәr) Silver-Russell syndrome (sil´vәr rus´әl) a syndrome consisting of low birth weight despite normal length of gestation, short stature, lateral asymmetry, and slight to moderate increase in excretion of gonadotropins, which may be associated with incurved fifth fingers, café-au-...

Silverman needle
a biopsy needle for taking tissue specimens, consisting of an outer cannula and an inner split needle with a longitudinal groove in which tissue is retained when the needle is withdrawn.

Silverman syndrome
(sil´vәr-mәn) Currarino-Silverman syndrome.

Silverman-Andersen score
(sil´ver-man an´der-sen) a system for evaluating the breathing of a premature infant, consisting of observing how the baby retracts various chest structures while breathing in, whether or not the nostrils flare, and whether he or she grunts while breathing in.

Silvestrini-Corda syndrome
(sil-vәs-tre´ne kor´dah) a rare syndrome seen in certain persons with cirrhosis, consisting of eunuchoid body type, loss of body hair, decreased libido, and sterility; affected males have atrophy of the testes and gynecomastia, and affected females have menstrual disorders such as menorrhagia or amenorrhea. It res...

Simbu virus
a virus of the genus Bunyavirus isolated from a species of mosquitoes (Aedes circumluteolis) in Africa; serologically related species infect humans and other animals.