Transport of small anionic and neutral solutes through chitosan membranes: Dependence on cross-linking and chelation of divalent cations

Chitosan membranes were prepared by solvent casting and cross-linked with glutaraldehyde at several ratios under homogeneous conditions. The cross-linking degree, varying from 0 to 20%, is defined as the ratio between the total aldehyde groups and the amine groups of chitosan. Permeability experiments were conducted using a side-by-side diffusion cell to determine the flux of small molecules of similar size but with different chemical moieties, either ionized (benzoic acid, salicylic acid, and phthalic acid) or neutral (2-phenylethanol) at physiological pH. The permeability of the different model molecules revealed to be dependent on the affinity of those structurally similar molecules to chitosan. The permeability of the salicylate anion was significantly enhanced by the presence of metal cations commonly present in biological fluids, such as calcium and magnesium, but remained unchanged for the neutral 2-phenylethanol. This effect could be explained by the chelation of metal cations on the amine groups of chitosan, which increased the partition coefficient. The cross-linking degree was also correlated with the permeability and partition coefficient. The change in the permeation properties of chitosan to anionic solutes in the presence of these metallic cations is an important result and should be taken into consideration when trying to make in vitro predictions of the drug release from chitosan-based controlled release systems

Systemic proteasome inhibition triggers neurodegeneration in a transgenic mouse model expressing human α-synuclein under oligodendrocyte promoter: implications for multiple system atrophy

Multiple system atrophy (MSA) is a progressive late onset neurodegenerative α-synucleinopathy with unclear pathogenesis. Recent genetic and pathological studies support a central role of α-synuclein (αSYN) in MSA pathogenesis. Oligodendroglial cytoplasmic inclusions of fibrillar αSYN and dysfunction of the ubiquitin–proteasome system are suggestive of proteolytic stress in this disorder. To address the possible pathogenic role of oligodendroglial αSYN accumulation and proteolytic failure in MSA we applied systemic proteasome inhibition (PSI) in transgenic mice with oligodendroglial human αSYN expression and determined the presence of MSA-like neurodegeneration in this model as compared to wild-type mice. PSI induced open field motor disability in transgenic αSYN mice but not in wild-type mice. The motor phenotype corresponded to progressive and selective neuronal loss in the striatonigral and olivopontocerebellar systems of PSI-treated transgenic αSYN mice. In contrast no neurodegeneration was detected in PSI-treated wild-type controls. PSI treatment of transgenic αSYN mice was associated with significant ultrastructural alterations including accumulation of fibrillar human αSYN in the cytoplasm of oligodendroglia, which resulted in myelin disruption and demyelination characterized by increased g-ratio. The oligodendroglial and myelin pathology was accompanied by axonal degeneration evidenced by signs of mitochondrial stress and dysfunctional axonal transport in the affected neurites. In summary, we provide new evidence supporting a primary role of proteolytic failure and suggesting a neurodegenerative pathomechanism related to disturbed oligodendroglial/myelin trophic support in the pathogenesis of MSA

Principles of Heating, Ventilating, and Air Conditioning

Principles of Heating, Ventilating, and Air Conditioning, Ninth Edition, is based on content from all four volumes of the ASHRAE Handbook, pulling heavily from the 2021 ASHRAE Handbook—Fundamentals. It contains the most current ASHRAE procedures and definitive yet easy-to-understand treatment of building HVAC systems, from basic principles through design and operation. This book is suitable both as a textbook and as a reference book for undergraduate engineering courses in the field of heating, ventilating, and air-conditioning; for similar courses at technical and vocational schools; for continuing education and refresher short courses for engineers; and for adult education courses for professionals other than engineers, especially when combined with the ASHRAE Handbook. Several significant changes have been made for this revised edition, including changes to chapter content and organization with the goal of ensuring the content is approachable and practical. For many chapters, a single example building is used to enhance consistency and further students’ understanding, and the removal of residential discussions and examples has given the book a more pointed focus on commercial calculations and applications. Specific changes include the following, among many others: The first chapter has been revised to provide not just history but also updated information regarding current trends and the possible future of the HVAC industry. The Thermodynamics and Psychrometrics chapter content has been reorganized, and additional materials on psychrometrics, including additional psychrometric charts covering low temperatures and higher elevations, have been included. The System Loads chapter reflects reorganization to better walk the user through the calculation process used by professionals. The Energy Estimating Methods chapter has been streamlined to better reflect the current processes used by today\u27s energy modelers and connects energy estimation with load calculations presented in the textbook. The Duct and Pipe Sizing chapter includes expanded information, tables, and charts used for hydronic pipe sizing with updated example problems, allowing for more thorough topic coverage. The Hydronic Heating and Cooling System Design chapter includes updated general content based on the latest design trends and requirements as well as expanded information on typical hydronic heating/cooling equipment and system types. In addition, several entire chapters have been removed from the print book but will be available online. The online materials include information on the following topics: Additional Psychrometric Charts Air-Processing Equipment Cogeneration and Heat Recovery Systems Economic Analyses and Life-Cycle Costs Heat Exchanger Equipment Heating Equipment Panel Heating and Cooling Systems Radiant Times Series (RTS) Method Refrigeration Equipment Systems Design Problemshttps://scholarworks.boisestate.edu/fac_books/1546/thumbnail.jp