The purpose of this paper was to discuss the achievements of in vitro modeling in terms of the blood–brain barrier [BBB] and to create a clear overview of this research area, which is useful in research planning. The text was divided into three main parts. The first part describes the BBB as a functional structure, its constitution, cellular and noncellular components, mechanisms of functioning and importance for the central nervous system, in terms of both protection and nourishment. The second part is an overview of parameters important in terms of establishing and maintaining a barrier phenotype that allows for formulating criteria of evaluation of the BBB in vitro models. The third and last part discusses certain techniques for developing the BBB in vitro models. It describes subsequent research approaches and models, as they underwent change alongside technological advancement. On the one hand, we discuss possibilities and limitations of different research approaches: primary cultures vs. cell lines and monocultures vs. multicultures. On the other hand, we review advantages and disadvantages of specific models, such as models-on-a-chip, 3D models or microfluidic models. We not only attempt to state the usefulness of specific models in different kinds of research on the BBB but also emphasize the significance of this area of research for advancement of neuroscience and the pharmaceutical industry.

The study included water samples from 10 test points located in the northern parts of Sanok and Lesko counties. The following analytical methods have been used: AAS (FAAS, CVAAS, HGAAS), ICP-MS, ICP-OES, Ion chromatography, Acid-base titration, argentometry, turbidimetry and also bacteriological tests. Two sources were identified as "natural mineral hard medium-mineralised waters" with low iron content. Four sulphide springs have been found. The Lesko source can be characterized as "a specific therapeutic sulphide water" with a content of divalent sulphur, determined iodometrically, above 1 mg • dm-3 and without any bacteriological concerns. Water from Lesko, apart from small amounts of metaboric and orthosilicic acid, is slightly alkaline with a strong negative ORP potential (-230 mV), which makes it healthy (an antioxidant that eliminates free radicals). In all waters the presence of heavy metals, arsenic, lithium, iron, manganese, alkali metals and alkaline earth metals has been indicated. The influence on the human body of analytically marked substances has been described.