72,234 articles
Comparative anatomy of cnidarian classes
Comparative anatomy of cnidarian classes contrasts polyp-only Anthozoa with Medusozoa, about 3,700 species in four classes, from box jellyfish with 24 eyes to parasitic Myxozoa.
Comparative auditory physiology
Comparative auditory physiology studies how vertebrate ears detect and discriminate sound across species, using differences among fish, amphibians, reptiles, birds, and mammals to interpret human hearing.
Comparative phylogeography
Comparative phylogeography is the study of how evolutionary history and biogeography shape genetic variation in co-distributed species, testing concordant patterns for shared causes such as barriers or climate change.
Comparative properties of animal silks
Comparative properties of animal silks is a comparison of protein fibers across animals, chiefly spider dragline silk and silkworm cocoon silk, explaining why published measurements often disagree.
Comparison of birth control methods
Comparison of birth control methods (contraception): IUDs, implants, pills, patch, ring, injection, condoms, fertility awareness, sterilization, and emergency contraception, compared by typical use failure rates, duration, STI protection, reversibility, and user preferences.
Comparison of MD and DO in the United States
MD vs DO in the US: the two physician degree paths, allopathic MD and osteopathic DO, differ in philosophy, OMT training, and COMLEX vs USMLE exams, but outcome studies show similar patient care, and both match through the single ACGME accreditation system.
Comparison of the healthcare systems in Canada and the United States
Canada vs US healthcare: Canada runs tax-funded provincial single-payer Medicare with universal coverage and no cost sharing; the US uses multi-payer employer and public insurance, spends over 16% of GDP, and ranks last among 10 high-income countries.
Compartment syndrome
Compartment syndrome: raised pressure within a fascial muscle compartment causing ischemia; acute form is a trauma emergency treated by fasciotomy, chronic exertional form causes exercise-induced leg pain; delta pressure <30 mm Hg guides diagnosis.
Compartmental models (epidemiology)
Compartmental models in epidemiology divide a population into compartments such as SIR or SEIR states and use equations for movement between them. Founded on Kermack and McKendrick's 1927 work, they contrast with agent-based models and are widely used for outbreak forecasting and intervention analysis.
Compassion in World Farming
Compassion in World Farming (CIWF), founded 1967 by Peter and Anna Roberts in England, is a farm-animal welfare charity campaigning to end factory farming via corporate pledges, EggTrack, End the Cage Age, and the 2024 GB live export ban; HQ Godalming, UK, charity no. 1095050.
Compassion-focused therapy
Compassion-focused therapy (CFT) is a third-wave psychotherapy developed by Paul Gilbert around 2000 that trains clients in compassion skills to reduce shame and self-criticism, with trials showing reduced depression.
Compassionate use
Compassionate use, formally called expanded access in the United States, is a regulatory pathway that lets patients with serious or life-threatening conditions receive investigational drugs outside clinical trials.
Compatibility testing (transfusion medicine)
Compatibility testing, also called pretransfusion testing, is the set of laboratory procedures, including ABO and RhD typing, antibody screening, and crossmatch, that confirm a blood component is safe for a specific patient.
Compatible-solute biosynthesis in halophiles
Compatible-solute biosynthesis is how halophilic and halotolerant microbes make organic osmolytes like glycine betaine and ectoine to balance osmotic pressure instead of using the salt-in strategy.
Compatible-solute uptake and transport in halophilic archaea
Compatible-solute uptake and transport in halophilic archaea is the membrane transport by which salt-loving archaea import protective molecules like glycine betaine and ectoine, mostly through sodium-coupled symporters.
Compensatory emphysema
Compensatory emphysema (ICD-11 CB40.4, ICD-10 J98.3) is overinflation of normal lung tissue when another portion is destroyed or removed, as after pneumonectomy, pneumonia, pleural effusion, or pneumothorax; unlike true emphysema it involves no alveolar destruction.
COMPERA study
The COMPERA study is a European registry founded in Germany in 2007 documenting drug therapy and outcomes for pulmonary hypertension, with more than 13,000 patients enrolled across Europe.
Competence pheromone ComX, Bacillus-type
ComX, Bacillus-type: isoprenylated peptide quorum-sensing pheromone of Bacillus subtilis; 55-residue precursor cleaved by ComQ to a modified decapeptide that activates the ComP-ComA two-component system, with strain-specific pherotypes under diversifying selection.
Competence protein ComK
Competence protein ComK is the master regulator of natural competence in Bacillus subtilis, activating DNA uptake genes through an all-or-nothing switch active in only 5 to 10% of cells.
Competence protein D, Pasteurellaceae
Competence protein D (ComD) is a predicted component of the DNA uptake machinery of naturally competent Gram-negative Pasteurellaceae bacteria, encoded by comD in the comABCDE operon of Haemophilus influenzae.
Competence, DNA-entry nuclease inhibitor, ComJ
ComJ (nin, BSU03420, UniProt P12669) is the 18-kDa DNA-entry nuclease inhibitor of Bacillus subtilis competence; it binds and inactivates the ComI/NucA nuclease, allowing DNA uptake during natural transformation. PDB 4MQD, 2.16 Å.
Competent cells
Competent cells are bacterial cells, most commonly E. coli, treated chemically or by electroporation so their membranes admit foreign DNA, enabling laboratory transformation and cloning.
Competing endogenous RNA
Competing endogenous RNAs (ceRNAs): transcripts such as lncRNAs, circRNAs, pseudogenes, and mRNAs sharing microRNA response elements that compete for shared miRNAs, forming ceRNET regulatory networks; hypothesis proposed in 2011, with quantitative controversy over physiological scale.
Competition (biology)
Competition (biology): interaction between organisms requiring the same limited resource, lowering the weaker competitor's fitness. Covers interference, exploitation, and apparent competition, Lotka-Volterra theory, competitive exclusion, and climate change effects.
Competitive ELISA
Competitive ELISA, also called inhibition ELISA, is an immunoassay in which sample antigen competes with labeled antigen for antibody, so signal falls as concentration rises.
Competitive inhibition
Competitive inhibition: reversible enzyme inhibition where inhibitor and substrate binding are mutually exclusive, raising apparent Km with unchanged Vmax; Lineweaver-Burk lines intersect at (0, V^-1); the dominant inhibition type in metabolism.
Complement Activation
Complement activation: triggered enzymatic cascade of liver-derived plasma proteins via classical, lectin, and alternative pathways converging on C3 cleavage, producing opsonization, anaphylatoxins, and the C5b-9 membrane attack complex.
Complement component 3 deficiency
Complement component 3 deficiency (C3 deficiency, ORPHA:280133) is a rare autosomal recessive primary immunodeficiency causing severe recurrent encapsulated bacterial infections, glomerulonephritis, and SLE-like disease in childhood.
Complement factor B
Complement factor B is a serine protease proenzyme of the human complement system that supplies the catalytic activity of the alternative pathway convertases and is targeted by the drug iptacopan.
Complement Hemolytic Activity Assay
Complement Hemolytic Activity Assay (CH50, total hemolytic complement): functional blood test measuring total classical and terminal complement pathway activity by lysis of antibody-sensitized sheep red blood cells; used to screen complement deficiency and monitor lupus.