Report LIFE 98

Key words

17-ethynylestradiol: synthetic estrogen present in female oral contraceptives.

Activin: protein secreted by the cells of Sertoli stimulating the release of FSH by the pituitary.

Additivity: The phenomenon whereby the biological activity of a combination of two compounds equals that what can be theoretically predicted from the separate activities of the compounds in the mixture.

Alkylphenols (e.g. octylphenol, nonylphenol): chemicals present in plastics as plasticizers, or formed as metabolites from alkylphenolic polyethoxylate detergent molecules.

Androgens: endocrine steroidal hormones that are found in high concentrations in the male where they mainly regulate reproduction.

Anthropogenic: man-made.

Atrazin: herbicide used in corn crop.

Autocrine effect: effect of a molecule on the same cell by which it is produced.

Binding proteins: molecules in the blood that bind hormones. Only free hormones are biologically active.

Bioaccumulation: phenomenon whereby the concentration of a persistent compound in the body of an organism (usually in the fatty tissues) rises as it feeds itself with organisms that are positioned on a lower level of the food chain (e.g. for pesticides: water (bioaccumulation factor (BF) 1) plankton (BF 200), small fish (BF 500), predator fish (BF 7500), fish eating birds (BF 80.000).

Bisphenol A or 4,4'-isopropylidenediphenol: monomer and plasticizer used in plastics.

C18: octadecyl; hydrophobic molecule consisting of a linear branch of 18 carbon atoms, usually covalently coupled to silica particles.

Carbaryl: 1-naphthyl N-methylcarbamate, carbamate insecticide.

Conception: fertilization.

Coumestrol: phytoestrogen (coumestan class), present in clover.

Cryptorchidism: where the testis fails to descend into its normal position in the scrotum by the age of 12 months.

Cytosol: crude cell extract obtained after cell lysis and subsequent ultracentrifugation.

Daidzein: phytoestrogen (isoflavon class) present in soy rich food products.

DDE: metabolite of DDT, found in human blood and environmental matrices.

DDT: persistent organochlorine insecticide.

Dicofol: 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethanol, acaricide.

Dihydrotestosterone: hydrated metabolite of testosterone, and the most powerful androgen in the male.

Endocrine system: endocrine refers to the internal secretion of biological active compounds by the body, in contrast to external or exocrine secretion (e.g. sweat).

Endometriosis: disease of the endometrium.

Endometrium: tissue that covers the inside of the uterus.

Endosulfan: organochlorine insecticide and wood preservative.

Enterolacton: phytoestrogen derived from lignans present in cereals, fruits and vegetables.

Estradiol (17-): most active estrogen.

Estrogens: endocrine steroidal hormones that are found in high concentrations in the female where they mainly regulate reproduction. Also found in the male, but to a lesser extent.

Explant: piece of tissue taken from an organism and kept in culture in laboratory conditions.

Follicle Stimulating Hormone: hormone synthesized by the anterior pituitary, necessary for the processes of meiosis and mitosis during gametogenesis.

Gametogenesis: the development of gametes (spermatozoa and oocyte).

Genistein: phytoestrogen (isoflavon class) present in soy rich food products.

Germ cell: mother cell of spermatozoa or egg cells.

Gestation: pregnancy.

GnRH: Gonadotropine Releasing Hormone. Stimulates the synthesis and secretion of LH and FSH in the pituitary.

Gonad: sex gland: ovary and testes.

Homeostasis: body condition whereby all biological functions are in balance.

Hormones: natural substances which are produced by the body and are normally effective at very low concentrations. They act as chemical messengers, travelling in the blood and sending signals to cells to provide a means of communication between different parts of the body.

Hydrophobic: fat soluble.

Hydrophylic: water soluble.

Hydroxylation: chemical process in the body whereby an alcohol function is introduced on a certain organic molecule.

Hypospadias: abnormal opening (ending) of the urinary duct at the base of the penis.

Hypothalamus: part of the brain regulating the endocrine system through the production of non steroidal hormones of which a part directly go to the pituitary to regulate the latters function.

In utero: in the womb or uterus.

In vitro research: research on tissues, cells or molecules.

In vivo research: research on living animals.

Incidence: the number of new cases per year of a certain disease.

InhibinB: a hormone (glycoprotein), synthesized by the cells of Sertoli, inhibiting the secretion of FSH by the anterior pituitary.

Kozak sequence: small piece of code on mRNA enabling the efficient docking of ribosomes and thus the translation of a protein.

Lactation: milk production, breast feeding.

Leydig cells: cells present in the testicle, at the periphery of the seminal tubules, secreting testosterone (interstitial cells).

Luteinising Hormone: hormone, secreted by the pituitary, under stimulus of the pulsatile release of GnRH by the hypothalamus, and responsible in the male for the descent of the testicles and the regulation of the functioning of the Leydig cells.

Mestranol: derivative of estradiol, component of combined oral contraceptives.

Metabolism: all the processes that determine the concentration of a compound in the body: synthesis, transformation or natural breakdown and elimination. Also (for an organism): energy allocation, protein synthesis etc.

Methoxychlor or 1,1,1-trichloro-2,2-bis(4-methoxyphenyl)ethane: insecticide.

Morphology: the shape and structure of a cell, tissue or organism.

Multigeneration study: experiment whereby laboratory animals are exposed to chemicals during several generations (mother, child, child’s child etc.).

Naringenin: phytoestrogen (flavonoid) present in hops.

No Observed Adverse Effect Level: The maximal concentration of a chemical that does not result in a certain negative effect in an experimental animal.

Nonylphenol: see alkylphenols.

Octylphenol: see alkylphenols.

Organogenesis: the development of organs.

Paracrine: paracrine effect: effect of a molecule on cells in the immediate proximity of the cells that produce the molecule.

Persistent compounds: Compound that has a long half-life in tissues or environmental matrices.

Phthalates: a group of synthetic chemicals used as plasticizers in plastic, but also found in paints, lacquers, glue... One of the most omnipresent chemicals nowadays.

Phytoestrogens: Plant compounds with an estrogenic potential.

Pituitary: endocrine gland that is in close (physical) contact with the hypothalamus and that secretes hormones regulating the function of tissues or other glands such as the gonads.

Placenta: tissue formed during pregnancy through which the foetus receives from the mother’s blood the necessary products to develop.

Prevalence: the total number of cases of a certain disease.

Promotor: DNA sequence, upstream of a certain gene, controling the latter’s transcription.

QSAR: study whereby the biological activity of a compound is estimated through its chemical structural resemblance with another compound whose activity is known.

Receptor: molecule in the cell or on the surface of the cell, upon which the hormone binds in a very selective way. This binding is an essential part of the signal transduction from certain tissues to others and results in very specific physiological processes in the cell that has received the signal.

Restriction enzyme: enzyme that cuts DNA at a specific place defined by a well defined sequence of nucleic acids.

Sertoli cell: are present in the seminal tubules of the testis. Sertoli cells are regarded as the "nurse cells" of the developing spermatozoa and thus play an important role in spermatogenesis.

Sex Hormone Binding Globuline: protein binding and transporting sex steroids in the blood.

Spermatogenesis: formation and development of spermatozoa from germ cells through a number of divisions and transformations.

Steroids: organical molecules with a well-defined chemical 4-ring structure, like androgens, oestrogens and progestagens.

Synergism: phenomenon whereby the activity of a mixture of compounds is higher than what can be theoretically predicted from the separate activities of the compounds in the mixture.

Testosteron: most important male (masculinizing) hormone (androgen), produced by the Leydig cells in the testes.

Transdermal: through the skin.

Triazines: group of herbicides: e.g. atrazine and simazine.

Urethra: urinary duct.

Vertebrates: animals with a spinal cord.

Xenoestrogens: every synthetic or natural compound interacting with the body through binding to receptors or influencing metabolism or secretion or transport or activity of hormones, resulting in an effect in the body similar to the one observed with 17-estradiol.