Where does arrest collide?

A halt in a cell's progression through the cell cycle, held at a checkpoint until a condition is met, so that a later event does not begin before an earlier one is complete. Hartwell and Weinert's 1989 Checkpoints: controls that ensure the order of cell cycle events described the control mechanisms that enforce this dependency, for example holding a cell before mitosis until DNA synthesis and repair are finished. The referent is a regulated pause in the division cycle of a living cell, released or made permanent by the state of that cell, and it is not a stopped heart, a person taken into custody, or a crack that has ceased to run.[1]

Unit

A halt in progression through the cell cycle, held at a checkpoint

Recovery means

The arrest is released and the cell resumes the cycle once the checkpoint condition is satisfied, or it is made permanent, as in senescence

Measured by

Inferred from the distribution of DNA content by flow cytometry and from checkpoint and cyclin markers that report the phase at which cells are held

The sudden cessation of effective cardiac mechanical activity, so that circulation stops and, absent intervention, the person loses consciousness and dies. Jacobs and colleagues' 2004 Cardiac arrest and cardiopulmonary resuscitation outcome reports, the updated Utstein reporting statement, defined the event and standardised how its occurrence and outcome are recorded. The referent is an acute clinical failure of the circulation, timed from collapse and confirmed at the bedside, and it is distinct from a paused cell cycle, a legal act of arrest, or the stopping of a crack.[2]

Unit

The sudden cessation of effective cardiac mechanical activity and of circulation

Recovery means

Circulation may be restored by early defibrillation, chest compressions, and advanced life support; without timely intervention the outcome is death

Measured by

Recognised clinically by unresponsiveness, absent or abnormal breathing, and no signs of circulation, and characterised by presenting rhythm and time to intervention

The stopping of a running crack in a stressed material, when the energy available to drive the crack falls below what the material demands to keep it propagating, so the crack halts rather than continuing to failure. Kanninen's 1974 A dynamic analysis of unstable crack propagation and arrest in the DCB test specimen analysed how a rapidly propagating crack decelerates and arrests, and how that behaviour is captured in a test geometry. The referent is a mechanical event in a fracturing solid, described by crack speed, length, and toughness, and it bears no relation to a cell held at a checkpoint, a stopped heart, or a person taken into custody.[3]

Unit

The halting of a propagating crack in a stressed material

Recovery means

Not applicable

Measured by

Characterised by crack-arrest toughness and by crack velocity and length recorded in test specimens such as the double-cantilever beam