| ACNP | acute care nurse practitioner; American College of Nuclear Physicians |
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| ANA | acetylneuraminic acid; American Narcolepsy Association; American Neurological Association; American ... |
| B0 | constant magnetic field in nuclear magnetic resonance |
| B1 | induced field in magnetic resonance imaging; radiofrequency magnetic field in nuclear magnetic reson... |
| CIDNP | chemically induced dynamic nuclear polarization |
| annulus tendineus communis | A fibrous ring that surrounds the optic canal and the medial part of the superior orbital fissure; it gives origin to the four rectus muscles of the eye and is partially fused with the sheath of the optic nerve. Synonym: annulus tendineus communis, Zinn's ligament, Zinn's ring, Zinn's tendon. (05 Mar 2000) |
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| annulus tympanicus | In the foetus, a more or less complete bony ring at the medial end of the cartilaginous external acoustic meatus, to which is attached the tympanic membrane. Synonym: annulus tympanicus, tympanic bone. (05 Mar 2000) |
| annulus umbilicalis | An opening in the linea alba through which pass the umbilical vessels in the foetus; in young embryos it is relatively nearer to the pubis, but gradually ascends to the centre of the abdomen; it is closed in the adult, its site being indicated by the umbilicus or navel. Synonym: annulus umbilicalis, canalis umbilicalis. (05 Mar 2000) |
| annulus urethralis | The complete collar of smooth muscle cells of the neck of the urinary bladder which extend distally to surround the preprostatic sportion of the male urethra. There is not a comparable structure in the neck of the femoral bladder; the internal urethral sphincter may exist to prevent reflux of semen into bladder. Synonym: annulus urethralis, internal urethral sphincter, musculus sphincter vesicae, preprostate urethral sphincter, proximal urethral sphincter, sphincter muscle of urinary bladder. (05 Mar 2000) |
| Vieussens' annulus | A muscular ring surrounding the fossa ovalis in the wall of the right atrium of the heart. Synonym: annulus ovalis, margin of fossa ovalis, Vieussens' annulus, Vieussens' isthmus, Vieussens' limbus, Vieussens' ring. (05 Mar 2000) |
| periseptal annulus | Organelle associated with cell division in gram-negative bacteria. There are two circumferential zones of cell envelope in which membranous elements of the envelope are closely associated with murein. The annuli appear early in division and in the region between them, the periseptal compartment, the division septum is formed. (18 Nov 1997) |
| Haller's annulus | A doubling of the thoracic duct for part of its course through the thorax. Synonym: Haller's annulus. (05 Mar 2000) |
| receptors, cytoplasmic and nuclear | Proteins in the cytoplasm or nucleus that specifically bind signalling molecules and trigger changes which influence the behaviour of cells. The major groups are the steroid hormone receptors, which usually are found in the cytoplasm, and the thyroid hormone receptors, which usually are found in the nucleus. Receptors, unlike enzymes, generally do not catalyze chemical changes in their ligands. (12 Dec 1998) |
| Remak's nuclear division | <cell biology> An unusual form of nuclear division, in which the nucleus simply constricts, rather like a cell without chromosome condensation or spindle formation. Partitioning of daughter chromosomes is haphazard. Observed in some Protozoa. (18 Nov 1997) |
| Pelger-Huet nuclear anomaly | Congenital inhibition of lobulation in the nuclei of neutrophilic leukocytes; most cells present band or bilobulate appearance, and only an occasional cell is trilobed; it is not associated with disease, but may be confused with leukocyte "shift to left"; autosomal dominant inheritance. (05 Mar 2000) |
| ribonucleoproteins, small nuclear | Highly conserved nuclear RNA-protein complexes that function in RNA processing in the nucleus, including pre-mRNA splicing and pre-mRNA 3'-end processing in the nucleoplasm. The u3 snrnp is localised in the nucleolus, where it aligns into base pairs with the 28s rrna precursor in a still unidentified region and functions in pre-rrna processing. The u7 snrnp aligns into base pairs with a conserved sequence in the 3'-end of histone pre-mRNA and is an essential cofactor for the cleavage that creates the mature nonadenylated 3'-end. (12 Dec 1998) |
| RNA, heterogeneous nuclear | Nuclear nonribosomal RNA larger than about 1000 nucleotides, the mass of which is rapidly synthesised and degraded within the cell nucleus. Some heterogeneous nuclear RNA may be a precursor to mRNA. However, the great bulk of total hnrna hybridises with nuclear DNA rather than with mRNA. (12 Dec 1998) |
| RNA, nuclear | RNA molecules found in the nucleus either associated with chromosomes or in the nucleoplasm. (12 Dec 1998) |
| RNA, small nuclear | Short chains of RNA found in the nucleus. Their function is to remove the introns (nontranslated intervening sequences) from mRNA precursors, thereby bringing the two exons (coding segments) together into correct juxtaposition for enzymatic splicing at the correct point. The resulting mRNA is now ready to leave the nucleus. (12 Dec 1998) |
| rod nuclear cell | <pathology> Immature neutrophils released from the bone marrow reserve in response to acute demand. (18 Nov 1997) |