| Transcriptomics | The study of the set of all RNA molecules, including messenger RNA (mRNA), ribosomal RNA (rRNA), transfer RNA (tRNA) and other non-coding RNA (ncRNA) such as microRNAs produced in a cell type or in a population of cells/tissues. |
| Non-coding RNAs (ncRNA) | A functional RNA molecule that is not translated into a protein. |
| Exon | A nucleic acid sequence that is represented in the mature form of an RNA molecule after portions of precursor RNA (introns) have either been removed by splicing or two or more sequences joined by splicing. |
| RNA sequencing (RNA-seq) | A recently developed approach to transcriptome profiling that uses deep-sequencing technologies (high-throughput next generation sequencing) to sequence cDNA with deep coverage and base-level resolution. This provides a far more precise measurement of levels of transcripts and, in addition, information on differently spliced transcripts and post-transcriptional editing. |
| Microarray | A DNA microarray is a collection of microscopic DNA spots attached to a solid surface. Each DNA spot contains a specific DNA sequence or probes that can hybridise a cDNA or cRNA target under high-stringency conditions. DNA microarrays are used to measure the expression levels of large numbers of genes simultaneously. |
| Proteomics | The study of the entire protein complement of an organism or system. |
| Electrophoresis | The movement of particles relative to a solution under the influence of a uniform electric field. |
| Lipid | Broadly defined as a hydrophobic or amphipathic small molecule that may originate entirely or in part by carbanion-based condensations of thioesters and/or by carbocation-based condensations of isoprene units. |
| Lipidomics | The large-scale study or acquisition of the lipid composition of a biological system. |
| Structural lipid | The amphipathic components of the cell membrane including: glycerophospholipids, sphingolipids and sterols (also known as molecular or membrane lipids). |
| Eicosanoid | Biologically active products of arachidonic acid including prostaglandins, thromboxanes, leukotrienes and other oxygenated derivatives (also known as signalling lipids or lipid mediators). |
| Oxylipin | Oxygenated compounds that are formed from fatty acids by pathways involving at least one step of dioxygen dependent oxidation (include the eicosanoids as well as analogous compounds derived from alternative fatty acid substrates). |
| Phospholipid | Lipids built on a glycerol backbone that contain a phosphate group, a head group and two fatty acyl/alkyl chains; commonly structural components of cell membranes as they can form bilayers. |
| Sphingosine-1-phosphate | A signalling phospholipid built on a sphingosine backbone, rather than glycerol. Sphingosine can be released from ceramide and subsequently phosphorylated to become bioactive, for instance, as a ligand for cell surface receptors. |
| Lysophosphatidic acid | A potent lipid mediator known to be involved in cell proliferation. Can be formed via a number of different biosynthetic pathways by the sequential action of phospholipase enzymes. |
| Lung surfactant | A complex mixture of lipids and proteins whose primary function is to reduce alveolar surface tension and allow lung compliance. |
| Metabolomics | The analysis of the whole of the metabolome under a given set of conditions. |
| Metabolome | Complete compliment of all of the low molecular weight molecules (<1500 amu) present in the biological compartment in a particular physiological state under a given set of environmental conditions. |
| Metabolite profiling | Targeted quantification of a predefined subset of metabolite components of the metabolome that usually are of related chemical structure and/or biological activity. |
| Breathomics | The large-scale study of exhaled metabolites [11]. |
| Breathcloud | Online internet database of eNose breathprints matching various diseases, which can be used for direct calculation of diagnostic probability all around the world. |
| Breathprint | Composite signature of an exhaled molecular mixture, as obtained by ’omics analysis. |
| eNose | Electronic nose; composed of a nano-sensor array capturing mixtures of volatile organic compounds. |
| Exhaled breath condensate | The fluid captured by cooling exhaled air, containing non-volatile metabolites. |
| VOCs | Volatile organic compounds; in exhaled air these represent metabolites from respiratory or systemic origin. |
| Multivariate statistics | A form of statistics encompassing the simultaneous observation and analysis of more than one statistical variable. These methods reduce the dimensionality of datasets, thereby improving the interpretation and visualisation of data. A common application is to separate the signal from the noise in data with many variables. |
| Pattern recognition algorithms | Mathematical recognition of consistency between complex datasets, e.g. between composite molecular mixtures from validation and training samples. This can be used for probabilistic diagnostic assessment (positive and negative predictive value for disease). |
| Systems biology | Research approach to understand and model the system behaviour as a whole, linking the highly complex interactions between its components to its emergent properties, based on perturbation of the system and measures of its response with large-scale experimental data (primarily obtained via ’omics techniques). |
| Biomarker | Trait or substance such as an exogenous chemical molecule, endogenous antibody, protein, transcript or even cells objectively detectable or measurable in the body, blood or tissue, that indicates a biological state, and in biomedical research that correlates with the risk or stage of a disease, with response to treatment or intervention, or with exposure to environmental factors. |
| Biomarker profile | Also known as molecular signature or fingerprint; expression profile comprised of clusters of differentially expressed genes, proteins and/or metabolites indicative of a biological process. |
| Molecular network | Graph representation of interactions (edges) between molecules (nodes) within a cell for molecular systems such as transcriptional regulation, protein–protein interactions, or metabolites and reactions, whose topology analysis for example enables identification of important elements. |
| Machine learning | Diverse set of computational and statistical tools used where human expertise does not exist or cannot be formulated to design algorithms for the identification of patterns in empirical datasets that can be generalised to improve prediction of features in previously unseen datasets. |