Glossary of Terms

Glossary of Terms Acceptable Daily Intake or Allowed Daily Intake (ADI) → Dose- Response Relationship/Curve Allergen The allergen is a material which triggers an allergic reaction. Allopathy The term allopathy was created by Christian Friedrich Samuel Hahnemann (1755– 1843) (from the Greek prefix άλλος, állos, “other”, “different” and the suffix πάϑος, páthos, “suffering”) in order to distinguish his technique (homeopathy) from the traditional medicine of his age. Today, allopathy means a medicine based on the principles of modern pharmacology. Anaphylactic shock Anaphylaxis (or an anaphylactic shock) is a whole-body, rapidly developing allergic reaction, which may lead to lethal respiratory and circulatory failure. Antibody Antibodies are proteins produced by the immune system to neutralize exogenous (external) substances. Chromatography, chromatogram Chromatography is the common name of different techniques used to separate mix- tures of compounds. HPLC stands for high-performance liquid chromatography. A chromatogram is the pattern of separated substances obtained by chromatography. Colloidal sol A colloidal sol is a suspension of very small solid particles in a continuous liquid medium. Colloidal sols are quite stable and show the Tyndall effect (light scatter- ing by particles in a colloid). They can be quite stable. Examples include blood, pigmented ink, and paint. Colloidal sols can change their viscosity quickly if they © Springer International Publishing Switzerland 2014 311 L. Kovács et al., 100 Chemical Myths, DOI 10.1007/978-3-319-08419-0 312 Glossary of Terms are thixotropic. Examples include quicksand and paint, both of which become more fluid under pressure. Concentrations: parts per notations In British/American practice, the parts-per notation is a set of pseudo-units to de- scribe concentrations smaller than thousandths: 1 ppm (parts per million, 10−6 parts) One out of 1 million, e.g. mg/kg or one drop of water in 50 l or approximately 30 s in 1 year 1 ppb (parts per billion, 10−9 parts) One out of 1 billion, e.g. μg/kg or one drop of water in 50 m3 or approximately 3 s in a century 1 ppt (parts per trillion, 10−12 parts) One out of 1 trillion, e.g. ng/kg or one drop of water in 50,000 m3 (which is the volume of water in 20 Olympic swimming-pools) or approximately 3 s in 100,000 years Contact dermatitis Contact dermatitis is an allergic disease causing dry skin, redness and itching, which develops as a result of delayed-type hypersensitivity reaction. Dose-response relationship/curve The physiological effects of various materials depend on the amount (concentration) applied in a specific way (known as dose-response curve). At low doses, usually there is no measurable effect. Then, the effect begins to grow more and more steeply with increasing concentration, finally reaching a saturation value at maximum impact (curve A). The different sections of these so-called sigmoid curves contain important information about the different stages. The maximum effect of a drug is difficult to measure accurately because of the saturation characteristic, so the comparisons are mainly made based on the amount required for 50 % of efficiency that is the median effective dose ( ED50 ). For direct comparison, the dosages in each case are calculated to a unit of body weight, for example, in milligrams/ kilogram of body weight (mg/kg of body weight). The healing effect is always associated with the toxic effects, but the latter (hope- fully) belongs to significantly higher concentrations (curve B). The toxic effect is also characterized by a sigmoid curve, the amount required for 50 % of the effect is called the median lethal dose ( LD50), which is the amount of drug that will kill half of the sample population of a specific test animal within 24 h. The LD50 of a substance strongly depends on the species of the test animal and the route of entry (swallowed, dermal, inhalation etc). For humans, such data are usually unavailable for obvious reasons. Available human LD50 data are often gained from the identifi- able death of a famous person. Further human values can be estimated from animal tests. However, these values are rather uncertain because of the extrapolation pro- cesses used. Relative classification of poisons varies from time to time, materials with an LD50 less than 25 mg/kg of body weight (in rats, by ingestion) are usually considered very strong poisons. Glossary of Terms 313 Fig. 1 The dose-response curve For toxic gases, the product of the median lethal concentration ( LC50) and the 3 exposure time ( t) is given as LCt50 (expressed in mg × min/m units) instead of LD50. The ratio of the median lethal dose ( LD50) and the median effective dose ( ED50) gives the therapeutic index ( TI = LD50/ED50), which expresses how safe it is to use the drug the higher the therapeutic index of a material is, the safer it is. In the case of diazepam (a common sedative), this value is around 100, while for digoxin (a cardiac glycoside), the TI is only 2–3, so the latter must be used very carefully. The actress Judy Garland died in 1969, at the age of 47, because she took too much Seconal, a sedative with small therapeutic index. The slope of the dose-response curves is also an important characteristic, because it shows the development of the impact as a function of the increase of the dose: the steeper the curve, the faster the therapeutic or toxic effects are reached. Another feature of the toxic effect is the foot point of the curve, the highest concentration where there was no toxic effect observed yet: this is the level of the non-observable adverse effect level (or NOAEL: no adverse effect level). The NOAEL values are directly influenced by the slopes of the curves: materials with the same LD50 values can yield very different NOAEL values (see the NOAEL values belonging to curves in B and C). Sometimes, the so-called non-observable effect level (or NOEL: no effect level) value is given, at which absolutely no impact can be measured. This is obviously smaller than the NOAEL value. The determination of the NOEL is usually very inaccurate. 314 Glossary of Terms The NOAEL value is especially important for non-medicinal applications (e.g. food additives, household materials, workplace safety values) as an upper limit which must be adopted when exposure limits are determined. Even moderately toxic materials may be used for certain purposes if a large safety factor is applied. This safety factor is usually close to a hundred (sometimes even a thousand), i.e. the acceptable or allowed or tolerable daily intake ( ADI or TDI) is calculated as follows: ADI = NOAEL/safety factor. Long-term occupational exposure is determined in a similar process: these have various names in the various countries (US: threshold limit value, TLV; Great Britain: workplace exposure limit, WEL; Germany: Arbeitsplatzgrenzwert, AGW, formerly Maximale Arbeitsplatz-Konzentration, MAK; France: valeur limite d’exposition professionnelle (VLEP); Spain: límite de exposición profesional; Italy: valore limite di soglia; Holland: Maximaal Aanvaarde Concentratie, MAC-waarde; European Union: indicative occupational exposure limit value, IOELV; Russia: преде́льно допусти́ мая концентра́ ция, ПДК) and define the same maximum al- lowable air pollution value of a hazardous substance in the workplace, expressed as a concentration. In some cases, e.g. for carcinogenic materials, trace elements and vitamins, the dose-response curves are more complex. Double blind study A double blind study is the most be suitable method to test the efficiency of a medicine objectively. Randomization, i.e. the random classification into groups excludes the distortion of results caused by inhomogeneities. A double blind design ensures that neither the physician nor the patient knows whether the patient receives the test drug or a placebo. For this reason, expectations on the treatment do not interfere with the results. Drug Drug is a word of Germanic origin. Its meaning was ‘dry, dried’. In the Middle Ages, the word drug was also used to refer to medicine (and poison), which can be explained by the fact that most medicines were made of dried herbs in those times. From the nineteenth century, drug also means narcotic. Epidemiological study An epidemiological study is the study of health status in a given population and the analysis of factors influencing it. Ergotism Ergotism is the effect of long-term ergot poisoning, traditionally due to the con- sumption of the alkaloids produced by the Claviceps purpurea fungus that infects rye and other cereals. It is also known as ergotoxicosis, ergot poisoning or Saint Anthony’s Fire or Holy Fire. Ergot poisoning is a proposed explanation of bewitch- ment. The symptoms of ergot poisoning include convulsive symptoms (painful sei- zures and spasms, diarrhea, paresthesias, itching, mental effects including mania or Glossary of Terms 315 psychosis, headaches, nausea and vomiting) and gangrenous symptoms of the fin- gers and toes (desquamation or peeling, weak peripheral pulses, loss of peripheral sensation, edema and ultimately the death and loss of affected tissues). Esters Esters are the products of condensation reactions between acids and alcohols. The other product of such reactions is water. Fruit esters are volatile compounds found in fruits. One class of lipids (triglycerides) are esters formed in the reaction between glycerol and various fatty acids. Flavonoids Flavonoids are plant pigments belonging to the class of polyphenolic compounds. Chemically, they are 2-phenyl-1,4-benzopyrone derivatives. Glycemic index The glycemic index characterizes how much a carbohydrate-containing food in- creases the blood glucose concentration. It shows how certain foods increase the blood glucose levels after eating, using glucose as a reference. Its value is influenced by numerous factors, such as the fiber content of the given food, the food preparation procedures, and the consistency of the food.

Load more