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

Preyer test
a spectroscopic test for carbon monoxide in the blood.

prezygotic
(pre-zi-got´ik) occurring before completion of fertilization.

priapism
(pri´ә-piz″әm) persistent abnormal erection of the penis, accompanied by pain and tenderness. It is seen in diseases and injuries of the spinal cord, and may be caused by vesical calculus and certain injuries to the penis.

prickle cell
a dividing keratinocyte found in the stratum spinosum (prickle cell layer) of the epidermis; it has delicate radiating processes that connect with other similar cells.

prickle cell carcinoma
squamous cell carcinoma (def. 1).

prickle cell layer
stratum spinosum.

prilocaine
(pril´o-kān) a local anesthetic, used parenterally as the hydrochloride salt or topically, together with lidocaine, as the base.

primal therapy
psychotherapy in which the patient is encouraged to relive his early traumatic experiences and so relieve the painful emotions with which they are associated.

primaquine
(pri´mah-kwin) an antimalarial agent effective against the extraerythrocytic forms of Plasmodium vivax and P. ovale and the gametocytes of P. falciparum, used especially in the treatment of relapsing vivax malaria; used orally as the phosphate salt.

primary amenorrhea
failure of menstruation to occur at puberty or before age 18; it may be caused by underdevelopment or malformation of the reproductive organs or by endocrine disturbances.

primary amyloidosis
a systemic form in which the deposited fibrillar material is AL amyloid; it may be due to either aberrant synthesis or processing of immunoglobulin light chains. It is associated with tumors or dyscrasias of immunoglobulin-producing plasma cells and affects some combination of the skin and subcutaneous tissue, nerves, liv...

primary apnea
cessation of breathing resulting when a fetus or newborn infant is deprived of oxygen; exposure to oxygen and stimulation usually restore respiration.

primary areas
areas of the cerebral cortex comprising the motor and sensory regions.

primary atelectasis
congenital atelectasis in which the alveoli have never been expanded with air.

primary atypical pneumonia
any of numerous acute types of pneumonia, formerly referring to any type other than bacterial pneumonia. Causative organisms include Mycoplasma pneumoniae (see mycoplasmal pneumonia) and species of Rickettsia, and Chlamydia, as well as viruses (see viral pneumonia). All are marked by extensive but short-lived pulmonary infiltration, ...

primary biliary cirrhosis
a rare form of biliary cirrhosis of unknown etiology, occurring without obstruction or infection of the major bile ducts, sometimes developing after the administration of such drugs as chlorpromazine and arsenicals. Affecting chiefly middle-aged women, it is characterized by chronic cholestasis with pruritus, jaundice, an...

primary brain vesicles
the three earlier subdivisions of the embryonic neural tube, including the forebrain, midbrain, and hindbrain.

primary cardiomyopathy
that in which the basic pathologic process involves the myocardium itself and not other cardiac structures; the condition is of unknown etiology and not part of a disease affecting other organs.

primary care
the routine outpatient care that a patient receives at first contact with a health care system.

primary cataract
one that develops independently of any other disease.

primary ciliary dyskinesia
any of a group of hereditary syndromes characterized by delayed or absent mucociliary clearance from the airways; often there is also lack of motion of sperm. One variety is Kartagener syndrome.

primary complex
the combination of a parenchymal pulmonary lesion (Ghon focus) and a corresponding lymph node focus, occurring in primary tuberculosis, usually in children. Similar lesions may also be associated with other mycobacterial infections and with fungal infections. the primary cutaneous lesion at the site of infection i...

primary culture
a cell or tissue culture made by direct transfer from a natural source to an artificial medium.

primary cuticle
a film on the enamel of unerupted teeth, considered to be the final product of degenerating ameloblasts after completion of enamel formation. Called also enamel cuticle and Nasmyth membrane.

primary dysmenorrhea
painful menstruation with no detectable organic disease.

primary effusion lymphoma
a B-cell lymphoma associated with human herpesvirus 8 infection, characterized by effusions in body cavities that contain lymphoma cells but no solid tumor.

primary electrical disease
a condition characterized by serious ventricular tachycardia, and sometimes ventricular fibrillation, in the absence of recognizable structural heart disease.

primary host
definitive host.

primary impotence
impotence that persists throughout the patient's life; it is often psychogenic, but sometimes can have a physical cause such as trauma at a young age or an organic disorder.

primary intraosseous carcinoma
a rare epithelial odontogenic malignancy occurring in the mandible and maxilla, particularly of male adults, and believed to arise from odontogenic epithelial remnants.

primary irritant dermatitis
irritant dermatitis.

primary lesion
the original lesion manifesting a disease, such as chancre in syphilis or tuberculous chancre.

primary lobule of lung
the functional unit of the lung; terminal respiratory unit.

primary lymphedema
that not secondary to a known condition; it may be present at birth (congenital lymphedema), appear at adolescence (lymphedema praecox), or appear in adulthood (lymphedema tarda).

primary mental disorder
any of the mental disorders that are neither due to a general medical condition nor substance-induced.

primary optic atrophy
a form in which the optic disk is characterized by sharp margins, enlarged physiologic cup, enhanced visibility of the lamina cribrosa, and a white color.

primary ovarian follicles
immature ovarian follicles, each comprising an immature oocyte and the specialized epithelial cells (follicle cells) surrounding it.

primary polycythemia
polycythemia vera.

primary radiation
that coming directly from a source, such as a radioactive substance or an x-ray tube, without interactions with matter.

primary receiving areas
primary receptive areas the areas of the cerebral cortex that receive the thalamic projections of the primary sensory modalities such as vision, hearing, and smell. Called also receiving, receptive, or sensory areas.

primary sensory neuron
a sensory neuron that is the first in an afferent pathway, beginning at the receptor and ending at a synapse with a secondary sensory neuron; the synapses are often in nuclei in the central nervous system.

primary somatomotor area
an area in the posterior part of the frontal lobe just anterior to the central sulcus; different regions control motor activity of specific parts of the body. Called also precentral area and rolandic area.

primary suture
prompt surgical closure of a wound.

primary syphilis
the first stage of the disease, showing symptoms about a week after spirochetes have penetrated the skin or a mucous membrane. The first sign is a painless sore called a chancre that appears usually about three weeks after infection. It is normally firm or hard, resembling a blister, pimple, or ulcerated, open sore. In me...

primary teeth
deciduous teeth.

primary tuberculosis
pulmonary tuberculosis when a person is first infected, usually seen in children or immunocompromised adults. It is often without symptoms, simply diagnosed after a positive result on a tuberculin test.

primary vitreous
the earliest vitreous in the embryo, formed from a mass of ectodermal and mesodermal fibrils between the optic cup and the lens vesicle; it develops into parts of the retina, iris, and ciliary body.

primate
(pri´māt) an individual belonging to the Primates, an order of mammals that includes human beings, apes, monkeys, and lemurs.

prime mover
a muscle that acts directly to bring about a desired movement.

primidone
(prim´ĭ-dōn) an anticonvulsant used in the treatment of epilepsy; administered orally.

primigravida
(pri″mĭ-grav´ĭ-dә) a woman pregnant for the first time; gravida I.

primipara
(pri-mip´ә-rә) a woman who has had one pregnancy that resulted in a fetus that attained a weight of 500 g or a gestational age of 20 weeks, regardless of whether the infant was living at birth or whether it was a single or multiple birth. Also written para I or I-para. adj., primip´arous., adj.

primiparity
(pri″mĭ-par´ĭ-te) the state of being a primipara.

primitive
(prim´ĭ-tiv) first in point of time; existing in a simple or early form that shows little complexity.

primitive bone
woven bone.

primitive neuroectodermal tumor
(PNET) a heterogeneous group of tumors that are thought to derive from undifferentiated cells of the neural crest.

primitive neuroepithelial tumor
neuroepithelial tumor.

primitive node
a mass of cells at the cranial end of the primitive streak, related to the organization of an embryo.

primordial
(pri-mor´de-әl) original or primitive; of the simplest and most undeveloped character.

primordial germ cell
the earliest type of germ cell, originating elsewhere but migrating to the gonads early in embryonic development. Called also gonocyte.

primordial granulosa cells
prefollicle cells.

primordial ovarian follicle
an immature ovarian follicle that has not undergone recruitment and consists of an oocyte enclosed by a single layer of cells.

primordial wandering cell
a small mononuclear cell of the embryo that arises from the mesoderm and subsequently by differentiation gives rise to wandering cells of the body.

primordium
(pri-mor´de-әm) the first beginnings of an organ or part in the developing embryo.

princeps pollicis artery
origin, radial artery; branches, radialis indicis artery of index finger; distribution, each side and palmar aspect of thumb.

principal cells
chief cells (def. 3). the fundamental cells of an organ, which usually have a specific function. light-staining cells of the renal collecting tubules that transport water in response to antidiuretic hormone and sodium in response to aldosterone.

principal points
cardinal p's (def. 1).

principle
(prin´sĭ-pәl) a chemical component. a substance on which certain of the properties of a drug depend. an accepted or professed rule of action or conduct. active principle any constituent of a drug that helps to confer upon it a medicinal property. ...

Pringle disease
(pring´gәl) adenoma sebaceum (def. 2).

Prinzmetal angina
a variant of angina pectoris in which the attacks come during rest, the person does not lose the ability to exercise, and the electrocardiogram during an attack shows elevation of the ST segment. This typet is cyclic in nature and is believed to be caused by coronary artery spasm.

prion
(pri´on) (pre´on) any of several pathogenic, transmissible forms of the core of prion protein that cause a group of degenerative diseases of the nervous system known as prion diseases. Prions have a structure different from that of normal prion protein, lack detectable nucleic acid, and do not elicit an ...

prion disease
any of a group of fatal degenerative diseases of the nervous system caused by abnormalities in the metabolism of prion protein. These diseases are unique in that they may be transmitted genetically as an autosomal dominant trait, or by infection with abnormal forms of the protein (prions). Inherited forms result from mutations ...

prion protein
a protein of uncertain function, in humans coded for by a gene on the short arm of chromosome 20. The protease-resistant core is the functional, and perhaps only, component of prions; several abnormal forms have been identified and are responsible for prion disease.

prism
(priz´әm) a solid of glass, plastic, or a similar substance with a triangular or polygonal cross section, which splits up a ray of light into its constituent colors and turns or deflects light rays toward its base. Prisms are used to correct deviations of the eyes, since they alter the apparent situation of ...

prison fever
epidemic typhus.

private antigens
antigens of the low-frequency blood groups, so called because they are found only in members of a single kindred.

private nurse
private duty nurse one who attends an individual patient, usually on a fee-for-service basis, and who may specialize in a specific class of diseases.

PRK
photorefractive keratectomy.

PRL
Prl prolactin.

pro re nata
(p.r.n.) (pro re na´tә) Latin phrase meaning as needed. Used in prescription writing.

Pro-Banthine
(pro-ban-thīn´) trademark for preparations of propantheline bromide, an anticholinergic used to treat peptic ulcers.

pro-opiomelanocortin
(pro-o″pe-o-mel″ә-no-kor´tin) the prohormone that is the precursor of corticotropin, lipotropins, melanocyte-stimulating hormones, and endorphins.

pro-otic
(pro-ot´ik) preauricular.

proaccelerin
(pro″ak-sel´әr-in) factor V.

proactivator
(pro-ak´tĭ-va″tәr) a precursor of an activator; a factor that reacts with an enzyme to form an activator.

proarrhythmic effect
any new, more advanced form of arrhythmia caused by an antiarrhythmic agent, especially an effect producing hemodynamically important symptoms. These usually occur less than 30 days after initiation of treatment and do not include those caused by new events such as acute myocardial infarction or hypokalemia.

proatlas
(pro-at´lәs) a rudimentary vertebra that lies in front of the atlas in some animals; sometimes seen in humans as an anomaly in the lower posterior part of the skull.

probability
(prob″ә-bil´ĭ-te) the likelihood of occurrence of a specified event, which is often represented as a number between 0 (never) and 1 (always) that corresponds to the long-run frequency at which the event occurs in a sequence of random independent trials under identical conditions, as the number of ...

probability sample
random s.

proband
(pro´band) an affected person ascertained independently of relatives in a genetic study. Called also propositus.

probang
(pro´bang) a flexible rod with a ball, tuft, or sponge at the end; used to apply medications to or remove matter from the esophagus or larynx.

probe
(prōb) a long, slender instrument for exploring wounds, body cavities, passages, or periodontal pockets. a labeled (as by radioactivity or chemiluminescence) DNA or RNA fragment used to detect the presence of a complementary nucleic acid fragment. The labeled sequence is added to a specimen, where it ...

probenecid
(pro-ben´ә-sid) a compound used in treatment of gout to promote excretion of uric acid; also used to increase serum concentration of certain antibiotics and other drugs.

probiotic
(pro″bi-ot´ik) a preparation of nonpathogenic microorganisms introduced into the body for their health benefits, such as Lactobacillus acidophilus ingested to modify the intestinal microflora.

probucol
(pro´bu-kōl) a bis-phenol compound used as an anticholesteremic; taken orally.

procainamide
(pro-kān´ә-mīd) a cardiac depressant used as the hydrochloride salt in the treatment of cardiac arrhythmias, administered orally, intramuscularly, or intravenously.

procaine
(pro´kān) a local anesthetic; the hydrochloride salt is used for infiltration and spinal anesthesia and peripheral nerve block.

Procanbid
(pro´kan-bid″) trademark for a preparation of procainamide hydrochloride, a cardiac depressant.

procarbazine
(pro-kahr´bә-zēn) an antineoplastic agent used primarily in combination with mechlorethamine, vincristine, and prednisone in the regimen called MOPP for treatment of advanced Hodgkin disease; it also has activity against non-Hodgkin lymphomas and brain tumors.

procarboxypeptidase
(pro″kahr-bok″se-pep´tĭ-dās) the inactive precursor of carboxypeptidase, which is converted to the active enzyme by the action of trypsin.