| pi | 1. 16th Letter of the Greek alphabet. 2. (Π). Symbol for osmotic pressure; in mathematics, symbol for the product of a series. 3. (π). Symbol for the ratio of the circumference of a circle to its diameter (approximately 3.14159265). 4. Symbol for inorganic orthophosphate (should not be used when covalently linked to another moiety). 5. The pH value for the isoelectric point of a given substance. 6. <abbreviation> Periodontal Index. (05 Mar 2000) |
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| pi bond | <chemistry> A bond formed from the overlap of two parallel p-orbitals. (09 Jan 1998) |
| pi cone monochromatism | Impaired, but not absent, colour vision with less severely reduced visual acuity than in complete achromatopsia; inherited as an autosomal recessive or as an X-linked disorder (blue cone monochromism; pi cone monochromatism ). (05 Mar 2000) |
| pi helix | A rare right-handed helix found only in small portions of certain proteins. Stabilised by similar hydrogen bonds as in an a helix; there are 4.3 amino acid residues per turn of the helix. (05 Mar 2000) |
| pi protein | <protein> Polypeptide (35 kD) that is required for the initiation of DNA replication in the R6K antibiotic resistance plasmid, of which there are 12-18 copy equivalents in the E. Coli chromosome. (18 Nov 1997) |
| PI3 kinase | Class IV viruses, with a single positive strand of RNA and an icosahedral capsid. There are two main classes: enteroviruses, which infect the gut and include poliovirus and the rhinoviruses that infect the upper respiratory tract (common cold virus, Coxsackie A and B, Foot and Mouth disease virus and hepatitis A). (18 Nov 1997) |
| pia | Synonym: pia mater. Origin: L. Fem. Of pius, tender (05 Mar 2000) |
| pia mater | <anatomy> The delicate and highly vascular membrane immediately investing the brain and spinal cord. Origin: NL, fr. L. Pia (fem. Of pius tender, kind) + mater mother. Source: Websters Dictionary (01 Mar 1998) |
| pia-arachnitis | <medicine> Inflammation of the pia mater or of the arachnoid membrane. Origin: NL, fr. Gr. Small + meningitis. Source: Websters Dictionary (01 Mar 1998) |
| pia-arachnoid | The two delicate layers of the meninges, the arachnoid mater and pia mater (vs. The tough pachymeninx or dura mater), considered together; by this concept, the arachnoid and pia are two parts of a single layer, much like the parietal and visceral layers of a serous membrane or bursa; although separated by the subarachnoid space they are connected via the arachnoid trabeculae and become continuous where the nerves and filum terminale exit the subarachnoid space (the cerebrospinal fluid-filled space bounded by the leptomeninges). See: arachnoid, pia mater. Synonym: meninx tenuis, pia-arachnoid, piarachnoid. Origin: Lepto-+ G. Meninx, pl. Meninges, membrane (05 Mar 2000) |
| pial | <anatomy> Pertaining to the pia mater. Source: Websters Dictionary (01 Mar 1998) |
| pial funnel | The pia-lined channel in which each blood vessel entering the brain lies suspended; essentially, the pial funnel's are perivascular extensions of the subarachnoid space. (05 Mar 2000) |
| pial-glial membrane | The dual outer lining of the brain and spinal cord, composed of the glial limiting membrane and the pia mater. (05 Mar 2000) |
| pian | <medicine> The yaws. See Yaws. Origin: Pg. Pian, epian, or. Sp. Pian; from the native name in South America: cf. F. Pian. Source: Websters Dictionary (01 Mar 1998) |
| pian bois | A form of New World cutaneous leishmaniasis caused by Leishmania braziliensis guyanensis in the Amazon delta; a small proportion of cases are said to metastasize to the nasal mucosa with espundia-like involvement. Synonym: bosch yaws, bush yaws, forest yaws. (05 Mar 2000) |