Relative density Health Dictionary

One of a group of proteins that transport lipids in the blood. High levels of high density lipoprotein can help protect against atherosclerosis. (See also fats and oils; low density lipoprotein.)... high density lipoprotein

One of a group of proteins that are combined with lipids in the plasma. Low density lipoproteins (LDLs) are involved in the transport of

cholesterol in the bloodstream. An excess of LDLs (see hyperlipidaemias) is associated with atherosclerosis. (See also high density lipoprotein.)... low density lipoprotein

The ratio of the number of new cases of the disease and the amount of population-time of follow-up (e.g. person-year) of the disease-free population.... average incidence density

The number of malaria parasites in a specified volume of blood.... parasite density

The ratio of the risk of disease or death among the exposed to the risk among the unexposed; this usage is synonymous with risk ratio.... relative risk

The number of a given vector species present. It may be expressed in relative terms (e.g., the biting density in relation to the human host) or in absolute numbers (e.g., the number present in a room, cattle-shed or artificial shelter).... vector density

The compactness of bone tissue in relation to its volume. A decrease in bone density is a normal part of aging. However, in some people, excessive loss of density (see osteoporosis) can lead to fractures. Less commonly, an increase in bone density (see osteosclerosis) occurs in certain disorders (see osteopetrosis; Paget’s disease). Bone density can be measured by a technique known as densitometry, which uses low-dose X-rays.... bone density

The “compactness” of a substance, defined as its mass per unit volume. In radiology, the term relates to the amount of radiation absorbed by the structure being X-rayed. Bone, which absorbs radiation well, appears white on X-ray film. A lung, which contains mostly air, absorbs little radiation and is dark on film. The same holds true in CT scanning and MRI. (See also specific gravity.)... density

a sedation technique, used particularly in dentistry, in which a mixture of *nitrous oxide and oxygen (‘gas and air’) is given. The patient remains conscious throughout; the technique is used to supplement local anaesthesia for nervous patients.... relative analgesia

(VLDL) a *lipoprotein that is the precursor of *low-density lipoprotein (LDL). Containing triglycerides and cholesterol, it is produced in the liver and circulates in the bloodstream, where its triglycerides are hydrolysed to free fatty acids by *lipoprotein lipase. The remaining lipoprotein becomes progressively denser and richer in cholesterol to form LDL.... very low-density lipoprotein