Glossary

Flow Cytometry Terms

animal model – an animal similar to humans in its anatomy or physiology used in research in order to obtain information that can be used to estimate how humans may respond

CD8+ T-cells –- a type of lymphocyte that matures in the thymus. When activated, these cells develop into cytotoxic T lymphocytes (CTL) that are capable of directly killing tumor cells, virus infected cells and some parasites.

CD4+ T cells –- a type of lymphocyte that matures in the thymus. These cells are also called "helper" T cells because they produce factors that help other cells of the immune system to carry out their functions.

cytotoxic T lymphocytes (CTLs) – a specific type of T lymphocyte that destroys mutated or tumor cells.

dioxin – a general name for a large group of chemical compounds with similar structure. These compounds are made up of carbon, oxygen, hydrogen and chlorine atoms.

flow cytometer – an instrument used in medical and scientific research settings that can make rapid measurements and counts of cell samples

fluorescent marker - a substance that attaches to a specific type of protein on the interior or exterior of cell surfaces and contain a fluorochrome

fluorochrome – a fluorescent chemical that emits a specific color of light when illuminated by light

forward scatter – light reflected by cells at small angles (less than 90 degrees) and provides information about the size of the cell

granularity – the amount of granules within a cell

granule – particles in cells which contain chemicals used to destroy foreign substances and cells

granulocytes – immune system cells which contain granules

histogram – a graph representing the data produced by the flow cytometer. Both x- and y-axes indicate increasing brightness of fluorescence of the markers attached to the cells.

Human Immunodeficiency Virus (HIV) – a class of viruses that infect and destroy helper T cells of the immune system

immune system – the system that protects the body from foreign substances, cells, and tissues

immunotoxicant – a chemical that is harmful to the immune system

immunotoxicology – the study of substances that are harmful to the immune system

leukocytes – white blood cells

lupus – a disease caused by the mistaken attack of healthy body cells by the immune system

lymphocyte – a type of immune system cell associated with the lymph node system

macrophage – a type immune system cells which engulfs harmful foreign cells and substances

monocytes – a type of white blood cell which matures into a macrophage

mutate – undergo a significant change; with cells, DNA mutations often result in changes of protein production

non-immune control – mice that have not been exposed to dioxin or injected with tumor cells.

side scatter –- light reflected by cells at right angles (90 degrees) and provides information about the granularity of the cells

TCDD – 2,3,7,8-tetrachlorodibenzo-p-dioxin, the most potent chemical of the dioxin family of chemicals

thymus – a gland in the body that is involved with the development of the immune system; located in the upper torso area

vehicle control – mice that were injected with tumor cells but were not treated with dioxin. Instead they are injected with the liquid that dioxin was dissolved in (called the ‘vehicle’)

GCMS and Environmental Chemistry Terms

accelerated solvent extractor – a device which uses high temperature and pressure to dissolve and remove compounds that are stuck onto the air sampling resin and filters

column – a very small and thin tube through which a chemical mixture flows and is separated by gas chromatography.

chromatography – a process in which a chemical mixture, carried by a liquid or gas, is separated into components

computer model – predicted outcome made by using a computer to calculate mathematical equations used estimate patterns such as weather or wind direction

DDT- dichlorodiphenyldichloroethylene; an insecticide historically used in the United States to control mosquitoes and the spread of the disease malaria. DDT has been banned in the US since 1972 because of its persistence in the environment. However, DDT is still allowed for use internationally to control mosquitoes and malaria.

environmental chemistry – the study of the fate and transformation of chemicals in the environment

fragment ion – an ion which is only a fragment of the whole molecule after passing through the ion source of the mass spectrometer

GCMS – Gas Chromatography - Mass Spectometry

ion – a charged atom or molecule, can be positive or negatively charged

mass spectrum –the range ions separated according to their mass; the data output from the GCMS

microliter – one-millionth of a liter, 0.000001 liter

molecular ion – an ion which has not broken into fragments after it passed through the ion source in the mass spectrometer. This molecular ion reflects the molecular mass of the original compound as it passed through the GCMS.

organic compound – a chemical containing carbon and hydrogen

retene – an organic compound that is often created by the burning of plant material

retention time – the time it takes for a compound to travel through the gas chromatography column

solvent – usually liquid substance capable of dissolving one or more other substances

standard – a known amount, used to calibrate an instrument

troposphere – the lowest part of the earth's atmosphere which extends from the surface of the earth to the bottom of the stratosphere, approximately 5-9 miles high

volatile – readily evaporates to the gas phase at a relatively low temperature

Microarray and Developmental Toxicology Terms

animal models – animals with biology similar to humans.  Animal models are used to study the effects of toxic substances, diseases, or treatments because they respond similar to humans. 

control treatment –  in an experiment, the control treatment undergoes the exact same conditions as the experimental treatment except for the one factor being tested.

developmental biology – the study of the processes by which organisms grow and develop from a fertilized egg to a mature adult.

developmental toxicology – the study of substances that disrupt or disturb an organism’s development.

developmental toxin – a substance that harms an organism’s development.

DNA – deoxyribonucleic acid – a double-stranded helix structure, usually found in the cell nucleus, that contains hereditary material and instructions for cell and organism structure and function.

experimental treatment – in an experiment, the experimental treatment is exposed to one factor.  Any differences between the experimental treatment and the control treatment are likely to be caused by factor that was tested.

gene – a section of DNA that contains instructions for a structure (protein) or process in an organism.

gene expression – a combination of genes that are turned off or turned on in response to a specific condition.

microarray - A two-dimensional grid of DNA genes or gene fragment spots, usually arranged on a glass slide or silicone wafer.  A typical microarray contains 10,000-200,000 microscopic DNA spots.

mRNA – messenger ribonucleic acid – a single-stranded structure which carries the instructions from DNA to ribosomes (protein making structures) in cells

vertebrate – an animal with a spinal column

zebrafish - Danio rerio, tropical freshwater fish originally found in slow moving streams and rice paddies in India