A type of pigmented naevus. (See also molar pregnancy.)
(1) A term used to describe the common pigmented spots which occur on human SKIN. It arises from a collection of abnormal melanocytes (see MELANOCYTE) in the dermis adjacent to the epidermodermal junction. Moles are usually not present at birth, and appear in childhood or adolescence. Most moles are less than 5 mm in diameter and are macular at ?rst, becoming raised later. Rarely, moles are present at birth and may occasionally be massive. There is a substantial risk of future malignancy (see MALIGNANT) in massive congenital moles and prophylactic surgical removal is advised if feasible. All humans have moles, but their number varies from ten or fewer to 100 or more. The members of some families are genetically predisposed to large numbers of moles, some of which may be large and irregular in shape and colour. This ‘atypical mole syndrome’ is associated with an increased risk of future malignant MELANOMA.
(2) An internationally agreed unit (see SI UNITS) for measuring the quantity of a substance at molecular level.
The smallest possible amount of a substance comprising two or more linked atoms which retains the chemical characteristics of that substance. Molecules vary greatly in their size and complexity, ranging from oxygen (two linked oxygen atoms) and water (two hydrogen atoms and one oxygen) to large complex molecules such as deoxyribonucleic acid (DNA) comprising thousands of atoms of carbon, hydrogen, oxygen, nitrogen and phosphorus that form the double-helix structure which helps to form GENES, the basic building blocks of the hereditary material of living things.... molecule
molecules on the surface of cell membranes that are responsible for most cellular functions directly related to their immediate environment. Many have very precise functions of adhesion (see adhesion molecules), metabolic exchange, hormone reception, respiration, and immune reactions. Cell-to-cell exchanges involve specialized surface structures (junctions), which form a communicating nexus.... cell-surface molecules
a type of *heparin that is more readily absorbed and requires less frequent administration than standard heparin preparations used as *parenteral anticoagulant therapy to prevent and treat deep vein thrombosis following surgery or during kidney dialysis. Preparations in use include, dalteparin sodium, enoxaparin sodium, and tinzaparin sodium.... low-molecular-weight heparin
an emerging area of imaging that exploits recent developments of molecular and cell biology to create new markers. Most molecular imaging uses versions of these markers labelled with radioactive isotopes, which – after administration – are localized in the body and can be detected using such techniques as *positron emission tomography, *SPECT scanning, *magnetic resonance imaging, and optical imaging.... molecular imaging