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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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π, upper case Π
  • pi, the 16th letter of the Greek alphabet
  • ratio of the circumference of a circle to its diameter, approximately 3.14159
  • osmotic pressure (Π)
φ, upper case Φ
  • phi, 21st letter of the Greek alphabet
  • phenyl
  • quantum yield (π).
ψ, upper case Ψ
  • psi, 23rd letter of the Greek alphabet
  • pseudouridine
  • psychology.
P
  • parental
  • part
  • percentile
  • peta-
  • pharmacopoeia
  • phosphoric residue (in nucleic acid terminology)
  • phosphorus
  • pint
  • pole
  • population
  • position
  • positive
  • posterior
  • pressure
  • partial pressure
  • proline
  • product
  • poise
  • power
  • location and/or chemical species
  • plasma concentration of a substance indicated, by subscript
  • permeability constant
  • blood group designation
  • probability
  • a test statistic, e.g., a chi-square test, gives a result unlikely to occur by chance
  • pulse
  • pupil
p
  • pupil
  • optic papilla
  • phosphoric ester
  • phosphate
  • pico-
  • negative decadic logarathm
  • proton
  • protein
  • momentum
  • the short arm of a chromosome
P wave
deflection in an electrocardiographic tracing that represents atrial activity of the heart

p-
para-, e.g., p-dichlorobenzene

Po2, pO2
partial pressure (tension) of oxygen

p-aminobenzoic acid (PABA)
A factor in the vitamin B complex, a part of all folic acids and required for its formation; neutralizes the bacteriostatic effects of the sulfonamides since it furnishes an essential growth factor for bacteria, with the utilization of which the sulfonamides interfere; used as an ultraviolet screen in lotions and creams. It is produced in a test of pancreatic function. SYN: paraaminobenzoic acid, vitamin Bx.

p-aminohippuric acid (PAH) (a-me′no-hi-pur′ik)
Used in renal function tests to measure renal plasma flow; actively secreted (and filtered) by the kidney. p-aminohippuric acid synthase an enzyme in the liver that catalyzes the synthesis of p-aminohippuric acid from p-aminobenzoic acid (or the CoA derivative) and glycine. It may be identical with glycine acyltransferase.

p-aminopropiophenone (PAPP) (a-me′no-pro-pe-o-fe′non)
An antidote for cyanide poisoning.

p-aminosalicylic acid (PAS, PASA) (am′i-no-sal-i-sil′ik)
A bacteriostatic agent against tubercle bacilli, used as a second-line agent; potassium, sodium, and calcium salts have the same use.

p-chloral
SYN: m-chloral.

p-chloromercuribenzoate (PCMB, pCMB, p-CMB) (klor′o-mer′cur-e-ben′zo-at)
Organic mercury compound that reacts with &cbond;SH groups of proteins; an inhibitor of action of those proteins (enzymes) that depend on &cbond;SH reactivity. SEE ALSO: p.mercuribenzoate.

p-chlorophenol
SYN: parachlorophenol.

p-CMB
Abbreviation for p.chloromercuribenzoate.

p-dichlorobenzene
paradichlorobenzene, a white crystalline compound C6H4Cl2 made by chlorinating benzene and used chiefly as a moth repellent and deodorizer, aka PDB

p,p′-dichlorodiphenyl methyl carbinol (DMC) (di-chlor′o-di-fen′il)
A synthetic compound found effective as a miticide.

p-hydroxymercuribenzoate (hi-drok′se-mer′ku-re-ben′zo-at)
An organic mercurial formed spontaneously by hydrolysis of p.chloromercuribenzoate. SEE ALSO: p.mercuribenzoate.

p-hydroxyphenylacetate (hi-droks′e-fen′il-as′e-tat)
A minor side product of l-tyrosine degradation that is elevated in the urine in cases of neonatal tyrosinemia and in Richner-Hanhart syndrome.

p-hydroxyphenyllactate (hi-droks′e-fen′il-lak′tat)
A metabolite in tyrosine degradation that is elevated in individuals with Richner-Hanhart syndrome.

p-hydroxyphenylpyruvate (hi-droks′e-fen′il-pi′roo-vat)
A metabolite formed by the transamination of tyrosine; elevated in the urine of individuals with tyrosinemia.

p-mercuribenzoate (mer-kur-i-ben′zo-at)
A commonly used enzyme inhibitor because of its reaction with sulfhydryl groups; usually p.chloromercuribenzoate or p.hydroxymercuribenzoate is used.

P-170
SYN: P-glycoprotein.

Pco2, pCO2
Symbol for partial pressure (tension) of carbon dioxide. See partial pressure.

Pi
Symbol for inorganic orthophosphate (should not be used when covalently linked to another moiety).

P1
Abbreviation for parental generation.

32P
Symbol for phosphorus-32.

33P
Symbol for phosphorus-33.

P700
The pigment in chloroplasts bleached by light of wavelengths about 700 nm.

PB
Symbol for barometric pressure.

p53
A tumor suppressor gene located on the short arm of chromosome 17 that encodes a nucleophosphoprotein that binds DNA and negatively regulates cell division; frequently measured as a marker of malignant diseases.

p870
The pigment in bacterial chromatophores bleached by light of wavelengths about 870 nm.

p-
Abbreviation for para- (4).

P.A.
Abbreviation for physician assistant.

Pa
Symbol for pascal; protactinium.

Paas
H.R., German physician, *1900. See P. disease.

PABA
Abbreviation for p-aminobenzoic acid.

pablum (pab′lum)
A precooked infant food, a mixture of wheat, oat, and corn meals, wheat embryo, alfalfa leaves, brewers' yeast, iron, and sodium chloride. [L. pabulum, nourishment, fr. pasco, to nourish]

pabular (pab′u-lar)
Relating to, or of the nature of, pabulum.

pabulum (pab′u-lum)
Food or nutriment. [L.]

Pacchioni
Antonio, Italian anatomist, 1665–1726. See pacchionian bodies, under body, pacchionian corpuscles, under corpuscle, pacchionian depressions, under depression, pacchionian glands, under gland, pacchionian granulations, under granulation.

pacchionian (pak-e-o′ne-an)
Attributed to or described by Antonio Pacchioni (1665–1726).

pacefollower (pas′fawl-o-er)
Any cell in excitable tissue that responds to stimuli from a pacemaker.

pacemaker (pas′ma-ker)
  • Biologically, any rhythmic center that establishes a pace of activity
  • An artificial regulator of rate activity.
  • In chemistry, the substance of which the rate of reaction sets the pace for a series of chain reactions; the rate-limiting reaction itself; e.g., in a metabolic pathway, the enzyme catalyzing the slowest or rate-limiting reaction in that pathway. [L. passus, step, pace]
  • artificial p. :any device that substitutes for the normal p. and controls the rhythm of the organ; especially an electronic cardiac p., which may be implanted in the chest, with electrodes attached to the external cardiac surface, or passed through the venous circulation into the right side of the heart (pervenous p.).
  • demand p.: a form of artificial p. usually implanted into cardiac tissue because its output of electrical stimuli can be inhibited by endogenous cardiac electrical activity.
  • diaphragmatic p.: a device that paces the diaphragm, used in patients with chronic ventilatory insufficiency resulting from quadriplegia or certain types of phrenic nerve malfunction.
  • ectopic p.: any p. other than the sinus node.
  • electric cardiac p.: an electric device that can substitute for the normal cardiac p., controlling the heart's rhythm by artificial electric discharges. SYN: electronic p..
  • electronic p.: electric cardiac p..
  • external p.: an artificial cardiac p. of which the electrodes for delivering rhythmic electric stimuli to the heart are placed on the chest wall. SYN: transthoracic p..
  • fixed-rate p.: an artificial p. that emits electrical stimuli at a constant frequency.
  • nuclear p.: a nuclear-powered unit used to generate the electrical current for artificially pacing the heart; replaced by units using long-life nickel-cadmium and other power sources.
  • pervenous p.: an artificial p. passed through the venous circulation into the right side of the heart.
  • runaway p.: rapid heart rates over 140/min caused by electronic circuit instability in an implanted pulse generator.
  • shifting p.: wandering p..
  • subsidiary atrial p.: secondary source for rhythmic control of the heart, available for controlling cardiac activity if the sinoatrial p. fails; usually located within the crista terminalis and atrial free wall near the inferior vena cava.
  • transthoracic p.: external p..
  • wandering p.: a disturbance of the normal cardiac rhythm in which the site of the controlling p. shifts from beat to beat, usually between the sinus and AV nodes, often with gradual sequential changes in P waves between upright and inverted in a given ECG lead. SYN: shifting p..
pachometer (pa-kom′e-ter)
SYN: pachymeter.

Pachon
Michel V., French physiologist, 1867–1938. See P. method, P. test.

pachy-
Thick. [G. pachys, thick]

pachyblepharon (pak′e-blef′a-ron)
Thickening of the tarsal border of the eyelid. SYN: tylosis ciliaris. [pachy- + G. blepharon, eyelid]

pachycephalia (pak′e-se-fa′le-a)
SYN: pachycephaly.

pachycephalic, pachycephalous (pak′e-se-fal′ik, -sef′a-lus)
Relating to or marked by pachycephaly.

pachycephaly (pak-i-sef′a-le)
Abnormal thickness of the skull. SYN: pachycephalia. [pachy- + G. kephale, head]

pachycheilia, pachychilia (pak-i-ki′le-a)
Swelling or abnormal thickness of the lips. [pachy- + G. cheilos, lip]

pachycholia (pak-i-ko′le-a)
Inspissation of the bile. [pachy- + G. chole, bile]

pachychromatic (pak′e-kro-mat′ik)
Having a coarse chromatin reticulum.

pachychymia (pak-i-ki′me-a)
Inspissation of the chyme. [pachy- + G. chymos, juice]

pachydactylia (pak′e-dak-til′e-a)
SYN: pachydactyly.

pachydactylous (pak-i-dak′ti-lus)
Relating to or characterized by pachydactyly.

pachydactyly (pak-i-dak′ti-le)
Enlargement of the fingers or toes, especially extremities; often seen in neurofibromatosis. SYN: pachydactylia. [pachy- + G. daktylos, finger or toe]

pachyderma (pak-i-der′ma)
Abnormally thick skin. SEE ALSO: elephantiasis. SYN: pachydermatosis. [pachy- + G. derma, skin] p. laryngis a circumscribed epithelial hyperplasia at the posterior commissure of the larynx. p. lymphangiectatica elephantiasis due to lymph stasis. p. verrucosa chronic wartlike elephantiasis. p. vesicae elephantiasis with nodules composed of lymph vesicles on the skin surface.

pachydermatosis (pak′i-der′ma-to′sis)
SYN: pachyderma.

pachydermodactyly
Digital swelling due to diffuse fibromatosis occurring on the proximal interphalangeal joints of the index, middle, and ring fingers (sometimes involving the fifth finger, rarely the thumb); a familial form exists [MIM 600356].

pachydermoperiostosis (pak-i-der′mo-per′e-os-to′sis) [MIM*167100]
A syndrome of clubbing of the digits, periosteal new bone formation, especially over the distal ends of the long bones (idiopathic hypertrophic osteoarthropathy), and coarsening of the facial features with thickening, furrowing, and oiliness of the skin of the face and forehead (cutis verticis gyrata); there is seborrheic hyperplasia with open sebaceous pores filled with plugs of sebum; often of autosomal dominant inheritance, usually more severe in males. SYN: acropachyderma. [pachy- + G. derma, skin, + periostosis]

pachyglossia (pak-i-glos′e-a)
An enlarged, thick tongue. [pachy- + G. glossa, tongue]

pachygnathous (pa-kig′nath-us)
Characterized by a large or thick jaw. [pachy- + G. gnathos, jaw]

pachygyria (pak-i-ji′re-a)
Condition in which the convolutions of the cerebral cortex are abnormally large; there are fewer sulci than normal and in some cases the amount of brain substance is somewhat increased. SYN: macrogyria. [pachy- + G. gyros, circle]

pachyleptomeningitis (pak′i-lep′to-men-in-ji′tis)
Inflammation of all the membranes of the brain or spinal cord. [G. pachys, thick, + leptos, thin, + meninx (mening-), membrane, + -itis, inflammation]

pachymeningitis (pak′i-men′in-ji′tis)
Inflammation of the dura mater. SYN: perimeningitis. [pachy- + G. meninx, membrane, + -itis, inflammation] p. externa inflammation of the outer surface of the dura mater. SYN: epidural meningitis, external meningitis. hemorrhagic p. subdural hemorrhage associated with p.. SEE ALSO: subdural hemorrhage. hypertrophic cervical p. a fibrotic and inflammatory thickening of spinal pachymeninges, particularly in the cervical region, resulting in spinal nerve radiculopathy; believed to be of syphilitic etiology. p. interna inflammation of the inner surface of the dura mater. SYN: internal meningitis. pyogenic p. suppurative inflammation of the dura, often spreading from a neighboring osteomyelitis.

pachymeningopathy (pak′e-me-ning-gop′a-the)
Disease of the dura mater. [pachy- + G. meninx (mening-), membrane, + pathos, disease]




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