| giant hives | A vascular reaction involving the deep dermis or subcutaneous or submucal tissues, representing localised oedema caused by dilatation and increased permeability of the capillaries and characterised by development of giant wheals. (18 Nov 1997) |
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| giant hypertrophy of gastric mucosa | Gastric mucosal hyperplasia, either mucoid or glandular; the latter type may be associated with the Zollinger-Ellison syndrome. Synonym: giant hypertrophy of gastric mucosa, hypertrophic gastritis, Menetrier's syndrome. (05 Mar 2000) |
| giant lymph node hyperplasia | Large benign, hyperplastic lymph nodes. The more common hyaline vascular subtype is characterised by small hyaline vascular follicles and interfollicular capillary proliferations. Plasma cells are often present and represent another subtype with the plasma cells containing IgM and IgA. (12 Dec 1998) |
| giant melanosome | A large spherical melanosome (1 to 6 u in diameter) formed in the cytoplasm of melanocytes in cafe-au-lait spots and other melanocytic disorders. Synonym: macromelanosome. (05 Mar 2000) |
| giant osteoid osteoma | A benign, painful, tumour of bone characterised by the formation of osteoid tissue, primitive bone and calcified tissue. It occurs frequently in the spine of young persons. (12 Dec 1998) |
| giant pigmented nevus | These large pigmented (often hairy) congenital nevi are important because of their increased risk (10 to 15%) of conversion into malignant melanoma. A biopsy can confirm if cells have turned malignant. Any change in a pre-existing nevus should prompt a physician evaluation. (27 Sep 1997) |
| giant urticaria | A vascular reaction involving the deep dermis or subcutaneous or submucal tissues, representing localised oedema caused by dilatation and increased permeability of the capillaries and characterised by development of giant wheals. (18 Nov 1997) |
| redox potential | <chemistry> The reducing/oxidizing power of a system measured by the potential at a hydrogen electrode. (18 Nov 1997) |
| reduction potential | The inherent tendency of a compound to act as an electron donor or an electron acceptor. Measured in volts. (09 Oct 1997) |
| visual evoked potential | Voltage fluctuations that may be recorded from the occipital area of the scalp as the result of retinal stimulation by a light flashing at 1/4-second intervals; commonly summated and averaged by computer. (05 Mar 2000) |
| cell potential | <cell biology, physiology> The voltage of an electrochemical cell, the larger the cell potential, the greater the extent of reaction when equilibrium is reached. (26 Mar 1998) |
| reparative giant cell granuloma | <dermatology, oncology> A non-neoplastic lesion characterised by a proliferation of granulation tissue containing numerous multinucleated giant cells. It occurs on the gingiva and alveolar mucosa (occasionally on other soft tissues) where it presents as a soft red-blue haemorrhagic nodular swelling. It also occurs within the mandible or maxilla as a unilocular or multilocular radiolucency. Peripheral giant cell granuloma refers to the gingiva (giant cell epulis), central refers to the jaw. Microscopically similar lesions occur in the tubular bones of the hands and feet, are considered neoplastic, and may have a malignant course. Identical bony lesions may be seen in hyperparathyroidism and cherubism. See: giant cell tumour of bone. Synonym: giant cell epulis. (05 Mar 2000) |
| resting potential | <physiology> The electrical potential of the inside of a cell, relative to its surroundings. Almost all animal cells are negative inside, resting potentials are in the range 20 to 100mV, 70mV typical. Resting potentials reflect the action of the sodium pump only indirectly, they are mainly caused by the subsequent diffusion of potassium out of the cell through potassium leak channels. The resting potential is thus close to the Nernst potential for potassium. See: action potential. (10 Mar 1998) |
| membrane potential | <physiology> More correctly, transmembrane potential difference: the electrical potential difference across a plasma membrane. See: resting potential, action potential. (18 Nov 1997) |
| chemical potential | <chemistry> The work required (in j mol 1) to bring a molecule from a standard state (usually infinitely separated in a vacuum) to a specified concentration. More usually employed as chemical potential difference, the work required to bring one mole of a substance from a solution at one concentration to another at a different concentration, __ = RT.In (c2/cl). This definition is useful in studies of active transport, note that, for charged molecules, the electrical potential difference must also be considered (see electrochemical potential). (18 Nov 1997) |