Where does plaque collide?

The atherosclerotic plaque is a raised patch of fat, immune cells, and fibrous tissue that builds up inside the wall of an artery and can narrow or block the flow of blood. Virchow (1858) characterised the arterial lesion as an inflammatory process of the vessel wall, and Ross (1999) set out the modern account of the plaque as a chronic inflammatory disease driven by injury to the lining of the artery. Here the referent is a physical mass of material laid down in living tissue, described by its size and composition, and it is not a clump in the brain, a cleared patch in a dish of cells, or a slice of a mathematical surface.[1][2]

Unit

One atheromatous lesion in an artery wall, by its size and composition

Recovery means

Plaques may stabilise or partly regress with lipid-lowering treatment, while advanced calcified lesions largely persist

Measured by

Assessed by imaging such as angiography, ultrasound, and CT, and by histology of the lesion's fatty core and fibrous cap

The amyloid or senile plaque is a dense clump of misfolded beta-amyloid protein that collects in the spaces between nerve cells in the brain and is a hallmark of Alzheimer's disease. Alzheimer (1907) described these deposits in the cortex of a patient with progressive dementia, and Glenner and Wong (1984) purified the beta-amyloid protein that forms their core. This referent is an aggregate of protein in brain tissue, counted by its density under the microscope, and it differs from the fatty lesion in an artery, the cleared patch in a virus assay, and the chart slice in geometry.[3][4]

Unit

One extracellular beta-amyloid deposit in the brain

Recovery means

Not applicable

Measured by

Counted by density on stained brain sections and, in living patients, detected by amyloid PET imaging and cerebrospinal fluid markers

In virology a plaque is a small clear zone in a sheet of cultured cells where virus particles have infected and killed the cells spreading out from one starting point. d'Hérelle (1917) first saw such clear patches produced by bacteriophage on a lawn of bacteria, and Dulbecco (1952) turned the pattern into a counting method for animal viruses grown in a single layer of cells. This referent is a visible gap of destroyed cells used to count infectious particles, the opposite of a deposit, and it has nothing to do with a lesion in an artery, a clump in the brain, or a piece of a mathematical surface.[5][6]

Unit

One clear plaque in a cell monolayer, taken to mark one infectious particle

Recovery means

Not applicable

Measured by

Counted by eye or by imaging as plaque-forming units per volume in a plaque assay on a cell monolayer

In the geometry of foliations, a plaque is one connected slice of a leaf as it appears inside a single local coordinate patch of a smooth space that has been split into stacked parallel layers. The study of such layered spaces was founded by Reeb (1952), and Camacho and Lins Neto (1985) give the standard definition in which each coordinate patch cuts the leaves into plaques that join up across patches to build a full leaf. This referent is an abstract piece of a mathematical surface, defined by coordinates rather than by any substance, and it shares only the word with a deposit in an artery, a clump in the brain, or a cleared patch of cells.[7][8]

Unit

One connected component of a leaf inside a foliation chart

Recovery means

Not applicable

Measured by

Defined within a foliation atlas as the level sets of the chart's transverse coordinates, not an empirical measurement

In dentistry, plaque refers to dental plaque, the microbial biofilm that forms on tooth surfaces. This meaning comes from Marsh (2004) in Caries Research.[9]

Unit

Recovery means

Measured by