Barriers And Fluids Of The Eye And Brain

This volume presents the latest findings regarding the control of the fluid environments of the eye and brain. The book is comprised of papers presented at a symposium honoring the 80th birthday of Professor Hugh Davson. The contributors are previous students of Hugh Davson who are now leading authorities in the fields of the eye and brain. The eye is considered from its many interfaces, including the role of prostaglandins, blood flow in diabetes, and the vitreous body. Other topics discussed include the role of carbonic anhydrase, cerebrospinal fluid and its drainage, and the development of the blood/brain barrier to macromolecules. The book also shows how recent findings about homologous molecules refute earlier studies with foreign tracers, and offers a fascinating glimpse into the future with a description of the latest imaging techniques used in neurological diagnosis.

The brain is the most complex organ in our body. Indeed, it is perhaps the most complex structure we have ever encountered in nature. Both structurally and functionally, there are many peculiarities that differentiate the brain from all other organs. The brain is our connection to the world around us and by governing nervous system and higher function, any disturbance induces severe neurological and psychiatric disorders that can have a devastating effect on quality of life. Our understanding of the physiology and biochemistry of the brain has improved dramatically in the last two decades. In particular, the critical role of cations, including magnesium, has become evident, even if incompletely understood at a mechanistic level. The exact role and regulation of magnesium, in particular, remains elusive, largely because intracellular levels are so difficult to routinely quantify. Nonetheless, the importance of magnesium to normal central nervous system activity is self-evident given the complicated homeostatic mechanisms that maintain the concentration of this cation within strict limits essential for normal physiology and metabolism. There is also considerable accumulating evidence to suggest alterations to some brain functions in both normal and pathological conditions may be linked to alterations in local magnesium concentration. This book, containing chapters written by some of the foremost experts in the field of magnesium research, brings together the latest in experimental and clinical magnesium research as it relates to the central nervous system. It offers a complete and updated view of magnesiums involvement in central nervous system function and in so doing, brings together two main pillars of contemporary neuroscience research, namely providing an explanation for the molecular mechanisms involved in brain function, and emphasizing the connections between the molecular changes and behavior. It is the untiring efforts of those magnesium researchers who have dedicated their lives to unraveling the mysteries of magnesiums role in biological systems that has inspired the collation of this volume of work.

The partition of fluid between the vascular and interstitial compartments is regulated by forces (hydrostatic and oncotic) operating across the microvascular walls and the surface areas of permeable structures comprising the endothelial barrier to fluid and solute exchange, as well as within the extracellular matrix and lymphatics. In addition to its role in the regulation of vascular volume, transcapillary fluid filtration also allows for continuous turnover of water bathing tissue cells, providing the medium for diffusional flux of oxygen and nutrients required for cellular metabolism and removal of metabolic byproducts. Transendothelial volume flow has also been shown to influence vascular smooth muscle tone in arterioles, hydraulic conductivity in capillaries, and neutrophil transmigration across postcapillary venules, while the flow of this filtrate through the interstitial spaces functions to modify the activities of parenchymal, resident tissue, and metastasizing tumor cells. Likewise, the flow of lymph, which is driven by capillary filtration, is important for the transport of immune and tumor cells, antigen delivery to lymph nodes, and for return of filtered fluid and extravasated proteins to the blood. Given this background, the aims of this treatise are to summarize our current understanding of the factors involved in the regulation of transcapillary fluid movement, how fluid movements across the endothelial barrier and through the interstitium and lymphatic vessels influence cell function and behavior, and the pathophysiology of edema formation. Table of Contents: Fluid Movement Across the Endothelial Barrier / The Interstitium / The Lymphatic Vasculature / Pathophysiology of Edema Formation

Understanding the structure and function of the blood-brain barrier (BBB) and recogniz ing its clinical relevance require a concert of scientific disciplines applied from a view point of integrative physiology rather than from only molecular or analytical approaches. It is this broad scope that is emphasized in this book. In my opinion, four original contributions define the field as it exists today. The first, a monograph by Broman,1 entitled The Permeability of the Cerebrospinal Vessels in Normal and Pathological Conditions, was the model for many subsequent clinical and 3 experimental studies on BBB pathology. Second, experiments by Davson, summarized in his book entitled Physiology of the Ocular and Cerebrospinal Fluids, indicated that passive entry of nonelectrolytes into brain from blood is governed largely by their lipid 4 solubility. This research supported the original suggestion by Gesell and Hertzman that cerebral membranes have the semipermeability properties of cell membranes. The modem era of the barrier was introduced with the 1965 paper by Crone,2 entitled "Facilitated transfer of glucose from blood to brain tissue. " This paper identified stereospecific, facilitated transport of glucose as part of a system of regulatory barrier properties at a time when only a barrier to passive diffusion had been contemplated. Finally, the 1967 paper by Reese and Kamovsky, 11 entitled "Fine structural localization of a blood-brain barrier to exogenous peroxidase," sited the barrier at the continuous layer of cerebrovascular endothelial cells, which are connected by tight junctions.

In the last ten years the pediatric neurosurgeon has witnessed a real revolution in the diagnosis and treatment of pediatric hydrocephalus, the most frequently encountered condition in everyday clinical practice. The evolution of MRI and the advent of neuroendoscopic surgery have resuscitated the interest in the classification, etiology and pathophysiology of hydrocephalus. The book offers an updated overview on the recent progress in this field, and a new approach to hydrocephalus: the reader will find in it a modern and new presentation of an old disease, where genetics, endoscopy, cost-effectiveness analyses and many other aspects of the various therapies are extensively discussed. The volume will be useful not only for neurosurgeons, but for all specialists interested in the various aspects of hydrocephalus: pediatricians, radiologists, endocrinologists, pathologists and geneticists.

This text/reference uses 574 figures and illustrations to help explain the relationships between blood and the cerebrospinal fluid (CSF) and central nervous system (CNS). The authors focus on the interaction of these fluids and the relative importance of the transport mechanisms of hormones from blood to nervous tissue. Carrier-mediated transport of many neuroactive peptides is discussed. Special aspects of the blood-brain barrier are covered in detail. An entire chapter is devoted to the comparative physiology of the CSF and the brain barriers. Physiologists in all fields will have an interest in the updated theories covered in this book.