Long COVID Atlas
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Glossary

Long COVID Atlas glossary

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Gene/ProteinACE2A protein on the surface of many cells, including vessel-lining cells, that the virus uses as its doorway. DiagnosticAmbulatory blood pressure monitoringA cuff that records blood pressure around the clock, including during sleep. ImmunologyAutoantibodyAn antibody that mistakenly targets the body's own tissue instead of a germ. ProcessBaroreflexYour body's automatic system for keeping blood pressure steady second to second, using pressure sensors in your arteries. NeurologyBlood-brain barrierThe tight seal that normally keeps the bloodstream and the brain separated. DisorderBreathing pattern disorderBreathlessness that comes from how you are breathing, fast, shallow, and high in the chest, rather than from damaged lungs. MetricCirculating endothelial cellsVessel-lining cells that have broken off and are floating in the blood, where they can be counted. ManagementCompression garmentsSnug elastic garments worn on the legs and abdomen to stop blood pooling low on standing, easing POTS and orthostatic intolerance. DisorderDysautonomiaTrouble with the automatic controls of heart rate, blood pressure, temperature, and digestion. VirologyEBV reactivationA common dormant virus (Epstein-Barr) waking back up after COVID. MechanismEndothelial dysfunctionWhen the vessel lining stops working properly, so vessels constrict, leak, or signal inflammation when they should not. AnatomyEndotheliumThe thin, living layer of cells lining the inside of every blood vessel you have. MechanismFibrinaloid microclotsTiny abnormal clots, too small for routine tests, that can block the smallest vessels and starve tissue of oxygen. ProcessFibrinaloid microclotsTiny abnormal blood clots, too small to see on a normal scan, made of a misfolded form of the clotting protein fibrin. ProcessFibrinolysisThe body's normal process for dissolving blood clots once they are no longer needed. MetricFlow-mediated dilationA test of vessel-lining health: a cuff briefly blocks blood flow in the arm, then releases it, and a healthy artery widens a lot afterward. PhysiologyGas transfer (DLCO)How well oxygen crosses from the air sacs in your lungs into your blood. MechanismGPCR autoantibodiesAntibodies that mistakenly target the body's own receptors for controlling heart rate and blood pressure. MicrobiomeGut dysbiosisAn unhealthy shift in the mix of bacteria living in the gut. MetricHazard ratioA way of comparing risk between two groups. A hazard ratio of 1.63 means one group had about 63 percent higher risk. EndocrineHPA axisThe body's stress-hormone system that sets cortisol and your daily energy rhythm. MechanismHypercoagulabilityA state where the blood clots more readily than it should. MechanismImmune dysregulationAn immune system that stays switched on or misfires after the infection should be over. MechanismImpaired gas transferOxygen crossing from the air sacs into the blood less easily than it should, sometimes even when a CT scan and breathing test look normal. MicrobiomeIntestinal permeabilityHow easily the gut wall lets things pass; when it loosens, microbial bits leak into the blood. SymptomLabile blood pressureBlood pressure that swings suddenly and irregularly, sometimes surging high, sometimes dropping low. TreatmentLow-dose naltrexoneA familiar drug at a tiny fraction of its usual dose, used to calm inflammation. ImmunologyMast cell activationImmune cells that overreact and dump inflammatory chemicals like histamine. DisorderME/CFSA long-recognized post-viral illness that overlaps heavily with long COVID, including similar vascular impairment. PhysiologyMitochondriaThe tiny structures inside cells that turn fuel into usable energy. NeurologyNeuroinflammationInflammation inside the brain itself, driven by the brain's own immune cells. HormoneNitric oxideA tiny signal the vessel lining releases that tells blood vessels to relax and widen. AutonomicOrthostatic intoleranceFeeling dizzy, lightheaded, or foggy when you stand up or stay upright. ManagementPacingManaging activity so you stay within your current energy limit and avoid triggering a crash. SymptomPost-exertional malaiseA delayed, disproportionate worsening of symptoms after physical, mental, or emotional effort that used to be manageable. DisorderPOTSA form of orthostatic intolerance where the heart races on standing, often with dizziness and fog. MechanismPreload failureNot enough blood returning to fill the heart between beats, so a healthy pump is simply underfed during effort. HormoneSerotoninA signalling molecule, most of it made in the gut, that helps carry messages along the nerve route from gut to brain. ProcessShort-chain fatty acidsHelpful molecules that gut bacteria make when they ferment dietary fibre. NeurologySmall-fiber neuropathyDamage to the tiniest nerves that carry pain signals and run automatic functions. Gene/ProteinSpike proteinThe part of the virus that lets it enter cells. Some of it can linger in the body long after infection. TreatmentSynbioticA combination of helpful bacteria (probiotic) and the fibers that feed them (prebiotic). ImmunologyT-cell exhaustionA worn-out state of immune cells that have been activated for too long and stop working well. DiagnosticTilt-table testA test that tilts you upright on a table while tracking heart rate and blood pressure. ImmunologyTRPM3 channelA calcium gate on immune cells that appears to work poorly in post-viral illness. NeurologyVagus nerveThe long nerve that carries calming, automatic signals between the brain and the body. MechanismViral persistenceThe idea that pieces of the virus, or the whole virus, linger in the body long after the infection seems over. ProcessViral reservoirA small amount of virus that lingers in body tissue after the acute infection has cleared from the nose.