RNA worldThe RNA world is a hypothetical stage in the evolutionary history of life on Earth, in which self-replicating RNA molecules proliferated before the evolution of DNA and proteins. The term also refers to the hypothesis that posits the existence of this stage. Alexander Rich first proposed the concept of the RNA world in 1962, and Walter Gilbert coined the term in 1986. Alternative chemical paths to life have been proposed, and RNA-based life may not have been the first life to exist.
RNA editingRNA editing (also RNA modification) is a molecular process through which some cells can make discrete changes to specific nucleotide sequences within an RNA molecule after it has been generated by RNA polymerase. It occurs in all living organisms and is one of the most evolutionarily conserved properties of RNAs. RNA editing may include the insertion, deletion, and base substitution of nucleotides within the RNA molecule. RNA editing is relatively rare, with common forms of RNA processing (e.g.
Ribosomal RNARibosomal ribonucleic acid (rRNA) is a type of non-coding RNA which is the primary component of ribosomes, essential to all cells. rRNA is a ribozyme which carries out protein synthesis in ribosomes. Ribosomal RNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. rRNA is the physical and mechanical factor of the ribosome that forces transfer RNA (tRNA) and messenger RNA (mRNA) to process and translate the latter into proteins.
LipopolysaccharideLipopolysaccharides (LPS) are large molecules consisting of a lipid and a polysaccharide that are bacterial toxins. They are composed of an O-antigen, an outer core, and an inner core all joined by covalent bonds, and are found in the outer membrane of Gram-negative bacteria. Today, the term endotoxin is often used synonymously with LPS, although there are a few endotoxins (in the original sense of toxins that are inside the bacterial cell that are released when the cell disintegrates) that are not related to LPS, such as the so-called delta endotoxin proteins produced by Bacillus thuringiensis.
RNA interferenceRNA interference (RNAi) is a biological process in which RNA molecules are involved in sequence-specific suppression of gene expression by double-stranded RNA, through translational or transcriptional repression. Historically, RNAi was known by other names, including co-suppression, post-transcriptional gene silencing (PTGS), and quelling. The detailed study of each of these seemingly different processes elucidated that the identity of these phenomena were all actually RNAi. Andrew Fire and Craig C.
Polyarteritis nodosaPolyarteritis nodosa (PAN) is a systemic necrotizing inflammation of blood vessels (vasculitis) affecting medium-sized muscular arteries, typically involving the arteries of the kidneys and other internal organs but generally sparing the lungs' circulation. Small aneurysms are strung like the beads of a rosary, therefore making this "rosary sign" an important diagnostic feature of the vasculitis. PAN is sometimes associated with infection by the hepatitis B or hepatitis C virus. The condition may be present in infants.
CryoglobulinemiaCryoglobulinemia is a medical condition in which the blood contains large amounts of pathological cold sensitive antibodies called cryoglobulins – proteins (mostly immunoglobulins themselves) that become insoluble at reduced temperatures. This should be contrasted with cold agglutinins, which cause agglutination of red blood cells. Cryoglobulins typically precipitate (clumps together) at temperatures below normal body temperature - - and will dissolve again if the blood is heated.
Weight lossWeight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other connective tissue). Weight loss can either occur unintentionally because of malnourishment or an underlying disease, or from a conscious effort to improve an actual or perceived overweight or obese state.
Fragment antigen-bindingThe fragment antigen-binding region (Fab region) is a region on an antibody that binds to antigens. It is composed of one constant and one variable domain of each of the heavy and the light chain. The variable domain contains the paratope (the antigen-binding site), comprising a set of complementarity-determining regions, at the amino terminal end of the monomer. Each arm of the Y thus binds an epitope on the antigen. In an experimental setting, Fc and Fab fragments can be generated in the laboratory.
Infectious causes of cancerEstimates place the worldwide risk of cancers from infectious causes at 16.1%. Viral infections are risk factors for cervical cancer, 80% of liver cancers, and 15–20% of the other cancers. This proportion varies in different regions of the world from a high of 32.7% in Sub-Saharan Africa to 3.3% in Australia and New Zealand. A virus that can cause cancer is called an oncovirus or tumor virus.
Overlapping geneAn overlapping gene (or OLG) is a gene whose expressible nucleotide sequence partially overlaps with the expressible nucleotide sequence of another gene. In this way, a nucleotide sequence may make a contribution to the function of one or more gene products. Overlapping genes are present and a fundamental feature of both cellular and viral genomes. The current definition of an overlapping gene varies significantly between eukaryotes, prokaryotes, and viruses.
Post-exposure prophylaxisPost-exposure prophylaxis, also known as post-exposure prevention (PEP), is any preventive medical treatment started after exposure to a pathogen in order to prevent the infection from occurring. In 2021, the FDA has approved bamlanivimab/etesevimab for post-exposure prophylaxis against COVID-19. PEP is commonly and very effectively used to prevent the onset of rabies after a bite by a suspected-rabid animal, since diagnostic tools are not available to detect rabies infection prior to the onset of the nearly always-fatal disease.
