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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >>Asymmetric PCR Augmented Histamine Test
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Asphyxia Suffocation due to interruption of gaseous exchange in the lungs.
Assay 1. To test or evaluate. 2. The method for measuring the quantity of a given substance in a sample (chemically or by other means).
Assembly 1. The process of joining individual DNA fragments to yield long contigs.
2. The conversion of a second-level programming language into machine code.
3. Compilation of overlapping sequences from one or more related genes that have been clustered together based on their degree or sequence identify or similarity. Sequence assembly is used to put together shotgun sequencing fragments based upon overlapping restriction enzyme digests, and to identify and index novel genes from single-pass cDNA sequencing efforts.
Association constant See affinity constant.
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AST See aspartate transaminase.
Aster Star-shaped system of microtubules that emerges from a centrosome or from a pole of a mitotic spindle.
Asthma Chronic inflammatory disease of the airways, characterised by obstruction of airflow.
Astral microtubule Microtubules that radiate from the aster in a mitotic spindle and which are not attached to a kinetochore of a chromosome.
Asymmetric carbon A carbon that is covalently linked to four different groups. As a result the carbon atom can exist in two different tetrahedral configurations.
Asymmetric cell division Cell division that gives rise to two daughter cells that differ in size or in the presence or absence of some cytoplasmic constituents.
Asymmetric PCR A modified PCR technique that enables generation of single strand DNA for sequencing. It involves use of a large excess of one of the primers. In the initial cycles, double-stranded DNA is produced in an exponential manner. Later, as the concentration of one of the primers decreases, single-stranded DNA accumulates.
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Asynapsis The failure (complete or partial) in the pairing of homologous chromosomes during meiotic prophase.
AT content The fraction of the total nucleotides in a DNA molecule that are either adenine or thymine residues. The AT content is usually given as a percentage.
Ataxia Lack of muscular co-ordination.
Ataxia telangiectasia (AT) A rare fetal human disease associated with a defect in DNA repair. It is characterised by a defective immune system, premature ageing and predisposition to certain cancers. Individuals with only one copy of the ATM gene do not exhibit the disease but are sensitive to DNA-damaging X-rays or chemicals and susceptible to developing cancer.
Atelocentric A monocentric chromosome with a nonterminal centromere.
Atherosclerosis A type of arterial sclerosis in which plaques of lipoid material are deposited in the intima and media of the arteries.
Athetosis Repetitive involuntary movements.
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Atomic abosorption flame photometry A type of flame photometric technique which measures the absorption of a beam of monochromatic light by atoms in a flame.
Atomic weight The mass of an atom relative to the mass a hydrogen atom. It is equal to the number of protons plus neutrons.
Atopy A term used to describe lgE-mediated anaphylactic responses in humans, that is generally genetically determined.
ATP See adenosine triphosphate.
ATPase An enzyme that catalyses the hydrolysis of ATP, by the cleavage of either one phosphate group with the formation of ADP and inorganic phosphate, or of two phosphate groups, with the formation of AMP and pyrophosphate. This reaction is generally coupled to some energy requiring process.
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ATP synthase An enzyme complex that catalyses the synthesis of ATP from ADP and Pi during oxidative phosphorylation in the inner mitochondrial membrane or the bacterial plasma membrane and photophosphorylation in chloroplasts.
Atractyloside An inhibitor of oxidative phosphorylation. It prevents ADP-ATP exchange across the mitochondrial membrane catalysed by ADP-ATP translocase.
Atresia Congenital absence or closure of a tubular structure or body opening.
Atria (Singular: atrium) The two upper chambers of the heart that receive blood from the veins and contract to force that blood into the ventricles.
Atrial fibrillation Cardiac arrhythmia characterised by rapid, uncoordinated beating of the atria, resulting in ineffective atrial contractions.
Atrial natriuretic factor A peptide containing 28 amino acid residues secreted from the right atrial wall in response to excess atrial stretch following a rise in atrial pressure. It increases sodium excretion (natriuresis) by i) increasing glomerular filtration rate ii) decreasing rennin activity iii) inhibiting the activity of angiotensin coverting enzyme, iv) inhibiting the actions of angiotensin II and norepinephrine.
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Atrophic gastritis Chronic inflammation of the mucosal lining of the stomach that eventually progresses to loss of gastric glands (atrophy) and decreased HCl production.
Atrophy Wasting of a cell, tissue, organ or the entire body.
Att sites The loci of recombination present on phage and bacterial chromosome. These are the sites at which recombination integrates the phage into, or excises it from, the bacterial chromosome.
Attachment A file that is sent appended to an email message.
Attenuated vaccine A virulent organism that has been modified to a less virulent form that still retains the ability to elicit an immune response.
Attenuation 1. A mechanism for regulating gene expression in prokaryotes that involves premature termination of transcription. 2. A decrease in virulence of a pathogen.
Attenuator A nucleotide sequence in the 5’ region of a prokaryotic gene or RNA that causes premature termination of transcription.
Attributes Description of entitites in a database.
Augmented histamine test A gastric function test using a larger dose of histamine (0.04 mg histamine acid phosphate/kg body weight) which provides a more reliable proof of achlorhydria. The resting contents are withdrawn after an overnight fast and the gastric contents are aspirated for 1 hour. Halfway through the collection, intramuscular injection of 100 mg mepyramine maleate (Anthisan), an antihistamine is administered subcutaneously. The gastric contents are aspirated every twenty minutes for one hour. The acid concentration in the prehistamine specimens is 10 mEq/L and 10-25 mEq/L in the combined post-histamine specimens. In duodenal ulcer, values are greater than 100 mEq/L. If the pH is less than 3.5, free hydrochloric acid is present. In pernicious anaemia, the pH of the resting contents is usually ≥7.0 and there is a further rise following histamine administration.
Authentic protein A recombinant protein exhibiting all the properties of its naturally occurring counterpart including posttranslational modifications.
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