Tandem Repeat Sequences: multiple copies of the same base sequence on a chromosome; used as markers in physical mapping. See also -- physical map.
Target Income: a specified income which a provider is assumed to aim for.
Targeted Mutagenesis: deliberate change in the genetic structure directed at a specific site on the chromosome. Used in research to determine the targeted region's function. See also -- mutation, polymorphism.
Technology Transfer: the process of transferring scientific findings from research laboratories to the commercial sector.
Telomerase: the enzyme that directs the replication of telomeres.
Telomere: the end of a chromosome. This specialized structure is involved in the replication and stability of linear DNA molecules. See also -- DNA replication.
Temporal Sample: a non-probability sampling technique that involves recruiting subjects over a specified period of time.
Teratogenic: substances such as chemicals or radiation that cause abnormal development of an embryo. See also -- mutatgen.
Teratogenicity: the ability to cause defects in a developing fetus—a potential side-effect of many drugs.
Term: from 37 completed weeks to less than 42 completed weeks (259 to 293 days) of gestation.
Term Pregnancy: from 37 to 42 completed weeks of gestation since the first day of the last menstrual period.
Tertiary Health Care: refers to medical and related services of high complexity and usually high cost.
Third-Party Payer: Any organization, public or private, that pays or insures health care expenses for beneficiaries at the time at which they are patients.
Threshold Traits: traits that are not manifested until a certain threshold of liability are exceeded.
Thrombophilia: a tendency to the occurrence of thrombosis, the presence or development of an aggregation of blood factors frequently causing vascular obstruction.
Thymine (T): a nitrogenous base, one member of the base pair AT (adenine-thymine). See also -- base pair, nucleotide.
Time-Motion Studies: studies that involve highly-structured observation of activity patterns; researchers closely follow subjects while documenting each discreet activity.
T Lymphocyte (T Cells): lymphocytes that have matured and differentiated under thymic influence, termed thymus-dependent lymphocytes. These cells are involved primarily in the mediation of cellular immunity as well as in tissue and organ graft rejection.
Tolerance: antigen-specific turnoff or unresponsiveness of B or T cells; usually produced as a result of contact with that antigen under non-immunizing conditions.
Toolkit: the term toolkit is generally held to mean an information resource including, for example, routinely available data which may be required for quantifying potential health impacts, a compilation of literature on health determinants or a template for organizing a HIA or parts of the HIA process such as a workshop for key stakeholders.
Topical: when a medication (e.g., cream, ointment) is applied to a specific site or location, usually on the skin or external mucosa.
Topoisomerase: an enzyme that controls conformational changes in DNA and aids in orderly progression of DNA replication, gene transcription, and separation of daughter chromosomes by cell division.
Total Expenditure on Health: total (or national) expenditure on health is based on the following identity and functional boundaries of medical care: Personal health care services + Medical goods dispensed to outpatients = Total personal expenditure on health + Services of prevention and public health + Health administration and health insurance = Total current expenditure on health + Investment into medical facilities = Total expenditure on health.
Total Fertility Rate: the expected average number of children that would be born to a woman in her lifetime, if she were to pass through her childbearing years experiencing the age-specific fertility rates prevailing in a given year/period, for a given country, territory, or geographic area.
Totipotent: able to differentiate alone any line; the capacity of a cell or group of cells to produce all of the products of conception -- the extra-embryonic membrane and tissue, the embryo, and subsequently the fetus.
Toxicogenomics: the study of how genomes respond to environmental stressors or toxicants. Combines genome-wide mRNA expression profiling with protein expression patterns using bioinformatics to understand the role of gene-environment interactions in disease and dysfunction.
Tp53 Gene: a tumor suppressor gene that encodes a nuclear phosphoprotein that arrests cells from entering the S-phase of the cell cycle. Located on chromosome 17(pl13), Tp53 is postulated to contribute to diverse tumorigenesis.
Transaction Costs: the costs which are incurred by the process of negotiating between buyer (= third-party payer/ purchaser) and seller (= provider).
Transcervical procedure: any procedure that requires passage of an instrument or device through the cervix into the uterus (e.g. IUD insertion, MVA, endometrial biopsy).
Transcription: the process of RNA synthesis from a DNA template that is directed by RNA polymerase. The synthesis of an RNA copy from a sequence of DNA (a gene); the first step in gene expression. The process of converting the DNA code into a complementary mRNA segment. Transfer of genetic code information from one kind of nucleic acid to another. See also -- translation.
Transcription Factor: a protein that binds to regulatory regions and helps control gene expression.
Transcriptome: the full complement of activated genes, mRNAs, or transcripts in a particular tissue at a particular time.
Transfection: the introduction of foreign DNA into a host cell. See also -- cloning vector, gene therapy.
Transfer Factor: a heat-liable, dialyzable extract of human lymphocytes (a lymphokine) that is capable of conferring specific antigen reactivity to the donor.
Transfer RNA (tRNA): a class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code carried by mRNA.
Transformation: a process by which the genetic material carried by an individual cell is altered by incorporation of exogenous DNA into its genome.
Transgenic: an experimentally produced organism in which DNA has been artificially introduced and incorporated into the organism's germ line. See also -- cell, DNA, gene, nucleus, germ line.
Transient (acute) Urinary Incontinence: temporary episodes of urinary incontinence that is reversible once the cause or causes of the episode(s) are identified and treated.
Transinstitutionalization: the transfer of patients from one type of institutional setting to another, usually from long-stay psychiatric wards to some form of nursing home.
Transitional Economy: term used to describe economies which used to be run on command lines, but which are now giving an increased role to market forces.
Translation: the process in which the genetic code carried by mRNA directs the synthesis of proteins from amino acids. The process by which specific amino acids are incorporated into a protein as dictated by the sequence of the mRNA template. See also -- transcription.
Translocation: a mutation in which a large segment of one chromosome breaks off and attaches to another chromosome. Non-homologous recombination. See also -- mutation.
Transmission: passage of disease-causing microorganisms from one person to another.
Transposable Element: a class of DNA sequences that can move from one chromosomal site to another.
Trial Phase: biomedical clinical trials of experimental drug, treatment, device or behavioral intervention may proceed through four phases (from NIH):
- Clinical trials test a new biomedical intervention in a small group of people (e.g., 20-80) for the first time to evaluate safety (e.g., to determine a safe dosage range and to identify side effects).
- Clinical trials study the biomedical or behavioral intervention in a larger group of people (several hundred) to determine efficacy and to further evaluate its safety.
- Studies investigate the efficacy of the biomedical or behavioral intervention in large groups of human subjects (from several hundred to several thousand) by comparing the intervention to other standard or experimental interventions as well as to monitor adverse effects, and to collect information that will allow the intervention to be used safely.
- Studies are conducted after the intervention has been marketed. These studies are designed to monitor effectiveness of the approved intervention in the general population and to collect information about any adverse effects associated with widespread use.
Trial Registration Data Set: the minimum amount of trial information that must appear in a register in order for a given trial to be considered fully registered.
Trial Results Database: a trial results database provides the results of completed studies, and should be accompanied by methodological details to place the results in context. The results may or may not have been peer reviewed. A results database may be separate from a trial register. Thus, a trial may be registered in one register and have its results reported in a different results database.
Trial Site: the location(s) where trial-related activities are actually conducted. (from ICH E6).
Trigone: triangle-shaped muscle that extends up from the urethra to the posterior bladder wall and to the urethral openings. The trigone is the most sensitive area of the bladder muscle because of its high concentration of nerves.
Triplet Repeat Expansion: (see Hereditary Unstable DNA).
Trinucleotide Repeat Analysis (Repeats): unstable DNA sequences found in several human genes. Normally the triplets are repeated in tandem 5-50 times. When the number rises above the normal range, mutant disease syndromes appear.
Trisomy: possessing three copies of a particular chromosome instead of the normal two copies. See also -- cell, gene, gene expression, chromosome.
Trophectoderm: peripheral cells of the balstocyst that form the membrane sac surrounding the embryo.
Tuberculosis Incidence: the number of new cases registered from tuberculosis in a specific year, expressed per 100,000 population, for a given country, territory, or geographic area.
Tumor Angiogenesis Factor: represents the induction of the growth of blood vessels caused by this stimulant released by tumor cells. The growth of a tumor appears to parallel the development of new blood vessels.
Tumor Necrosis Factor (TNF): a family of cytokines produced by activated monocytes and lymphocytes that can induce hemorrhagic necrosis and regression of tumors.
Tumor Suppressor Gene: a gene that suppresses cellular growth and proliferation. Therefore, when its protein products are absent, it contributes to tumor development or progression. Also known as antioncogenes, these normal cellular genes encode proteins that are thought to normally regulate growth in a negative fashion.
Two-tail Test: a test to determine any difference between the variable; for example, if either drug A or drug B is superior to the other. It is usually considered that in a two-tail test more trust can be placed in the statistically significant results than with a one-tail test. When in doubt, the two-tail test is preferred.
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