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Seventh Framework Programme for Research and Technological Development (European Commission)

Seventh Framework Programme for Research and Technological Development (European Commission)

Side Effect

A side effect, or adverse reaction, is an unintended response to a medication. Side effects are generally regarded as being harmful, and may occur after a single dose or prolonged administration. They might result from the normal use of a medicine, or from the use of a medicine in a way unintended by the marketing authorisation holder (MAH) “ such as taking an overdose or from the combination of two or more medicines being taken at once.


A symptom is a manifestation of disease apparent to the patient himself, while a sign is a manifestation of disease that the physician perceives. The sign is objective evidence of disease; a symptom, subjective. (source:

Signalling Pathway

A signalling pathway is a sequence of steps involving several molecules in a cell or at its surface (receptors) that work together to control cell functions.

Signalling pathways are important in controlling many functions such as cell division, cell death, and the switching on or off of certain genes. They are directly linked to the cell's response. After the first molecule in a pathway receives a signal, it activates another molecule. This process is repeated until the last molecule is activated and the cell function is carried out. Abnormal activation or disruption of signalling pathways can lead to a variety of cell dysfunctions, among them cancer. Some cancer medicines have been developed to target these effects.


In a clinical trial, the significance is a description of how meaningful (valid) a trial result is. When evaluating the validity of a study, one must consider both the clinical and statistical significance of the findings. A study that claims clinical relevance may lack sufficient statistical significance to make a meaningful statement. Conversely, a study that shows a statistically significant difference in two treatment options may lack clinical relevance (if, for instance, an observed effect is very small but highly consistent).

Significance Level

The significance level (or О± level) is a threshold that determines whether a study result can be considered statistically significant after performing the planned statistical tests. The significance level is most often set to 5% (or 0.05), although other levels may be used depending on the study. This represents the probability of rejecting the null hypothesis when it is true. For example, a significance level of 0.05 indicates a 5% risk of concluding that a difference between the study results and the null hypothesis exists when there is no actual difference.

The significance level must be stated in the trial protocol as part of the statistics section. The probability of a result being due to chance rather than due to a medicine or other intervention being studied, if the null hypothesis is true (that is, if there is really no true difference), is known as the ˜p-value™. A result is then said to be statistically significant if it yields a p-value equal to or less than the significance level and thus will not be considered a chance occurrence. This is generally written as p ‰¤ 0.05.


Silencing refers to the ability of a cell to prevent the expression of a certain gene. Methods used to silence genes are increasingly being used in the laboratory to produce therapies against diseases, such as cancers, infectious diseases, and neurodegenerative disorders by selectively turning off specific genes in diseased tissues.

Single ascending dose study

A single ascending dose study (SAD study) is a type of Phase I trial. Single ascending dose studies are usually conducted in a small number of healthy volunteers (although some trials recruit patients). The aim is to find out the safe dose range, and to look for any side effects. The initial dose given will be very small and increased gradually (in a new group of volunteers) if no or only mild side effects are seen. Researchers will also take measurements to determine how the medicine is processed in the body.


Small interfering RNA (siRNA), sometimes known as silencing RNA, is a class of double-stranded RNA molecule that interferes with the expression of specific genes.

Site visit

A visit by agency officials, representatives of the sponsor, or consultants to the location of a research activity (e.g. a clinical trial site) to assess if the site is fully prepared for the protection of trial participants and the safe and successful conduct of the clinical trial.

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