Brain Barrier Systems [antikvár]

PrefaceIn recent years, many important developments have occurred in many research disciplines that are directly related to brain permeability. In morphological fields, the fine resolution provided by electron microscopy has resulted in new concepts of membrane structure. Electron microscopy, combined with autoradiography, have contributed significant information concerning dynamic events occurring in and around such membranes. Permeability measurements with drugs have led to new theories of the physical and chemical requirements which determine the penetration of drugs into the central nervous system. Measurements of permeability during development and in later more mature stages of life have resulted in theories that relate brain permeability and function and, as in senescence, brain permeability and pathology. Recent work with normal metabolites in the brain has shown complex active transport mechanisms to be present in the walls of the various cell types making up the nervous system. Cerebral transport phenomena have been shown to have a considerable degree of selectivity and specificity and seem highly significant in controlling the mechanisms of brain metabolism. Inasmuch as these membranes and transport systems sometimes appear to restrict entry of materials into the brain, it is apparent that they represent, in part at least, what has been termed the "Blood-Brain Barrier". Thus, the brain-barrier system may determine which metabolites can gain access to the brain, may determine the level of these metabolites available to various brain parts and brain cells, and may determine the rate of supply and the rate of elimination. It has also been suggested that specific transport processes may be interfered with in pathological states {i.e. amino acidurias, and phenylketonuria), and therefore that alterations of permeability can be involved in altered mental function.It is obvious from this very brief survey that great advances have been made recently on a number of fronts, in such areas as anatomy, physiology, neurochemistry, and pharmacology.Despite these advances, however, it is not uncommon to attend meetings and learn that the failure of almost any compound to enter the brain is due to the Blood-Brain Barrier, or that the only amino acid capable of penetrating the brain is glutamine. Most textbooks of neuroanatomy treat the concept of "Brain-Barrier" as being too complicated for discussion or provide some very structural rigid concept for restricting entry of most compounds.Although a number of conferences have been planned to consider these important advances in cerebral permeability, barriers or transport, none has taken place in recent years. Thus it was the purpose of the conference held in Amsterdam from September 26 to 30, entitled "Brain Barrier Systems" to gather together leading investigators from America and Europe who have been working on the various anatomico-bio-