bluuebunny/crossref_metadata_2025 huggingface dataset:
Structure and function of small arteries
Authors: Mulvany M. J. , Aalkjaer C.
Published: December 2017

The small arteries (prearteriolar vessels with lumen diameter less than approximately 500 microns) contribute importantly to and participate actively in the regulation of the peripheral resistance. New techniques, building on the classic histological and hemodynamic techniques, have enabled detailed in vitro investigation of small arteries. At present, research in small arteries is in its infancy, and our understanding of the heterogeneity of small arteries within vascular beds, between vascular beds, and between species is extremely limited. This review attempts to describe the current status of the field. New techniques, based primarily on a wire myograph (where the vessels are mounted as ring preparations) and a pressure myograph (where vessels are cannulated and pressure-lumen relations are determined), have allowed in vitro investigations of small arteries. The more physiological arrangement of the pressure myograph allows, for example, investigation of the vasoconstrictor response to raised intravascular pressure (the Bayliss response), whereas the less-sophisticated wire myograph is similar to use and may be more useful in certain situations where particular mechanisms are being investigated. Both techniques allow simultaneous measurements of vessel tone and a variety of parameters (e.g., membrane potential and intracellular ion activities) and thus allow precise determination of the relation between small artery structure and function. The vessels appear to remain fully viable with regard to the contractility of their smooth muscle cells as well as to the function of their perivascular nerves and their endothelium. The evidence suggests that the monovalent transport mechanisms in the plasma membrane, in particular potassium channels, play an important role in the determination of the membrane potential in small arteries, although the relation is more complex than indicated by the Goldman equation. Confirmation of these findings requires, however, simultaneous determinations of ion transport and vascular tone under conditions where vessels are subjected to mechanical loading. The membrane potential, through its effect on potential-dependent calcium channels, plays an important role in the determination of vascular tone. With regard to calcium homeostasis, current knowledge is hampered by the lack of direct measurements of the relation between cytoplasmic calcium and vascular tone. The evidence, however, suggests that besides potential-dependent calcium channels, receptor-operated calcium channels are present in the plasma membrane, although this still requires confirmation. The role of the sarcoplasmic reticulum is not clarified.(ABSTRACT TRUNCATED AT 400 WORDS)
Quantitative analysis of amino acid oxidation and related gluconeogenesis in humans
Authors: Jungas R. L. , Halperin M. L. , Brosnan J. T.
Published: December 2017

Significant gaps remain in our knowledge of the pathways of amino acid catabolism in humans. Further quantitative data describing amino acid metabolism in the kidney are especially needed as are further details concerning the pathways utilized for certain amino acids in liver. Sufficient data do exist to allow a broad picture of the overall process of amino acid oxidation to be developed along with approximate quantitative assessments of the role played by liver, muscle, kidney, and small intestine. Our analysis indicates that amino acids are the major fuel of liver, i.e., their oxidative conversion to glucose accounts for about one-half of the daily oxygen consumption of the liver, and no other fuel contributes nearly so importantly. The daily supply of amino acids provided in the diet cannot be totally oxidized to CO2 in the liver because such a process would provide far more ATP than the liver could utilize. Instead, most amino acids are oxidatively converted to glucose. This results in an overall ATP production during amino acid oxidation very nearly equal to the ATP required to convert amino acid carbon to glucose. Thus gluconeogenesis occurs without either a need for ATP from other fuels or an excessive ATP production that could limit the maximal rate of the process. The net effect of the oxidation of amino acids to glucose in the liver is to make nearly two-thirds of the total energy available from the oxidation of amino acids accessible to peripheral tissues, without necessitating that peripheral tissues synthesize the complex array of enzymes needed to support direct amino acid oxidation. As a balanced mixture of amino acids is oxidized in the liver, nearly all carbon from glucogenic amino acids flows into the mitochondrial aspartate pool and is actively transported out of the mitochondria via the aspartate-glutamate antiport linked to proton entry. In the cytoplasm the aspartate is converted to fumarate utilizing urea cycle enzymes; the fumarate flows via oxaloacetate to PEP and on to glucose. Thus carbon flow through the urea cycle is normally interlinked with gluconeogenic carbon flow because these metabolic pathways share a common step. Liver mitochondria experience a severe nonvolatile acid load during amino acid oxidation. It is suggested that this acid load is alleviated mainly by the respiratory chain proton pump in a form of uncoupled respiration.(ABSTRACT TRUNCATED AT 400 WORDS)
Protein serine/threonine phosphatases: structure, regulation, and functions in cell growth
Authors: Mumby M. C. , Walter G.
Published: December 2017

It is clear that much remains to be discovered regarding the roles of protein phosphatases in mitogenic signaling pathways. The ability of okadaic acid to activate MAPK/ERKs demonstrates that alteration in serine/threonine dephosphorylation can have significant effects on common steps in growth stimulation induced by different types of mitogens. As in the case of cell cycle control, protein serine/threonine phosphatase plays a central role in the reentry of quiescent cells into the cycle. Because the only known targets of okadaic acid are the catalytic subunits PP1 and PP2A, these enzymes are crucial components of two basic functions carried out by cells: growth and division. Important and obligatory roles for PP2B, PP2C, and newly discovered serine/threonine phosphatases are also likely. However, the limited tissue distribution, unique regulatory properties, and limited substrate specificities of these forms suggest more specialized functions in restricted cell types. The available information on the specific functions of different forms of protein serine/threonine phosphatases, let alone their individual isoforms and different multimeric holoenzymes, is still severely limited. Years of biochemical characterization and cDNA cloning have left us with far more forms than functions. This has led to the gratifying situation, at least for the biochemists, in which genetics and cell biology identify protein phosphatases for which a wealth of biochemical information is already available. The appreciation of the importance of these enzymes in the coming years can only increase as the functions for individual forms are discovered.
Gastroduodenal mucosal protection
Authors: Allen A. , Flemstrom G. , Garner A. , Kivilaakso E.
Published: December 2017

The barrier that protects the undamaged gastroduodenal mucosa from autodigestion by gastric juice is a dynamic multicomponent system. The major elements of this barrier are the adherent mucus gel layer, which is percolated by the HCO3- secretion from the underlying epithelial cells; the epithelial layer itself, which provides a permeability barrier and can rapidly repair superficial damage by a process of cell migration referred to as reepithelization or restitution; and a specially adapted vasculature, which provides a supply of HCO3- for transcellular transport and/or diffusion into the mucus layer. Passive diffusion of intestinal HCO3- into the lumen is particularly important when there is superficial damage resulting in increased leakiness of the mucosal epithelium. The process of reepithelization occurs by the migration of performed cells from gastric pits or duodenal crypts. This process is quite distinct from the wound healing and associated inflammatory response that accompany more severe injury or chronic damage. The adherent mucus gel acts as a physical barrier against luminal pepsin and provides a stable unstirred layer that supports surface neutralization of acid by mucosal HCO3-. Surface neutralization by mucosal HCO3- provides a major mechanism of protection against acid in the proximal duodenum. In the stomach, where luminal acidity can fall to around pH 1, other mechanisms of protection must exist, since the surface pH gradient is reported to collapse when luminal H+ exceeds approximately 10 mM. This collapse of the surface pH gradients may reflect, at least in part, that such studies have been mostly performed on non-acid-secreting mucosa where the supply of HCO3- to the interstitium from the parietal cells will be reduced. However, because the gastric mucosa can withstand prolonged exposure to acid without apparent damage, this implies an intrinsic resistance of the epithelial apical surface. This is amply illustrated within the gastric glands that do not secrete mucus and HCO3- yet are exposed to undiluted pepsin and an isotonic solution of HCl. Bicarbonate and mucus secretions together with mucosal blood flow are under paracrine, endocrine, and neural control. The rate of reepithelialization will depend on local chemotactic factors, adhesion mechanisms, and the creation of an acid/pepsin/irritant-free environment under a protective gelatinous or mucoid cap. If optimal conditions are met, then the rate of reepithelialization appears to depend primarily on the intrinsic properties of the migrating cells themselves rather than control by exogenous mediators.(ABSTRACT TRUNCATED AT 400 WORDS)
Regulation of gene expression by insulin
Authors: O'Brien R. M. , Granner D. K.
Published: December 2017

While insulin has long been known to modulate intracellular metabolism by altering the activity or intracellular location of various enzymes, it is only in the past 10 years that the regulation of gene expression by insulin has been recognized as a major action of this hormone. This review principally focuses on the regulation of gene transcription by insulin, although recent progress in the understanding of insulin-regulated mRNA stability and translation is also summarized. The identification of cis-acting elements and associated trans-acting factors through which insulin either increases or decreases the transcription of specific genes is reviewed in detail. Recent advances in the understanding of the mechanisms of insulin signaling are discussed in the context of insulin-regulated gene transcription, and emphasis is placed on the gaps that remain between the upstream signaling molecules and the downstream trans-acting factors whose binding/transactivation potential is ultimately regulated. Finally, potential gene expression defects that may contribute to the pathophysiology of non-insulin-dependent diabetes mellitus and hypertriglyceridemia are considered.
Hormonal regulation in insects: facts, gaps, and future directions
Authors: Gade G. , Hoffmann K. H. , Spring J. H.
Published: December 2017

There are two main classes of hormones in insects: 1) the true hormones produced by epithelial glands and belonging to the ecdysteroids or juvenile hormones and 2) the neuropeptide hormones produced by neurosecretory cells. Members of these classes regulate physiological, developmental, and behavioral events in insects. Detailed accounts are given on isolation, identification, structure-activity relationships, mode of action, biological function, biosynthesis, inactivation, metabolism, and feedback for hormones involved in 1) metabolic regulation such as the adipokinetic/hypertrehalosemic peptides and the diuretic and antidiuretic peptides; 2) stimulation or inhibition of muscle activity such as the myotropic peptides; 3) control of reproduction, growth, and development such as allatotropins, allatostatins, juvenile hormones, ecdysteroids, folliculostimulins and folliculostatins, ecdysis-triggering and eclosion hormones, pheromone biosynthesis activating neuropeptides, and diapause hormones; and 4) regulation of tanning and of color change. Because of the improvements in techniques for isolation and structure elucidation, there has been rapid progress in our knowledge of the chemistry of certain neuropeptide families. With the employment of molecular biological techniques, the genes of some neuropeptides have been successfully characterized. There are, however, areas that are still quite underdeveloped. These are, for example, 1) receptor studies, which are still in their infancy; 2) the hormonal status of certain sequenced peptides is not clarified; and 3) functional studies are lacking even for established hormones. The authors plead for a concerted effort to continue research in this field, which will also advance our knowledge into the use of insect hormones as safer and species-specific molecules for insect pest management.
Functional Significance of Cell Volume Regulatory Mechanisms
Authors: LANG FLORIAN , BUSCH GILLIAN L. , RITTER MARKUS , VÖLKL HARALD , WALDEGGER SIEGFRIED , GULBINS ERICH , HÄUSSINGER DIETER
Published: December 2017

Lang, Florian, Gillian L. Busch, Markus Ritter, Harald Völkl, Siegfried Waldegger, Erich Gulbins, and Dieter Häussinger. Functional Significance of Cell Volume Regulatory Mechanisms. Physiol. Rev. 78: 247–306, 1998. — To survive, cells have to avoid excessive alterations of cell volume that jeopardize structural integrity and constancy of intracellular milieu. The function of cellular proteins seems specifically sensitive to dilution and concentration, determining the extent of macromolecular crowding. Even at constant extracellular osmolarity, volume constancy of any mammalian cell is permanently challenged by transport of osmotically active substances across the cell membrane and formation or disappearance of cellular osmolarity by metabolism. Thus cell volume constancy requires the continued operation of cell volume regulatory mechanisms, including ion transport across the cell membrane as well as accumulation or disposal of organic osmolytes and metabolites. The various cell volume regulatory mechanisms are triggered by a multitude of intracellular signaling events including alterations of cell membrane potential and of intracellular ion composition, various second messenger cascades, phosphorylation of diverse target proteins, and altered gene expression. Hormones and mediators have been shown to exploit the volume regulatory machinery to exert their effects. Thus cell volume may be considered a second message in the transmission of hormonal signals. Accordingly, alterations of cell volume and volume regulatory mechanisms participate in a wide variety of cellular functions including epithelial transport, metabolism, excitation, hormone release, migration, cell proliferation, and cell death.
The Filament Lattice of Striated Muscle
Authors: MILLMAN BARRY M.
Published: December 2017

Millman, Barry M. The Filament Lattice of Striated Muscle. Physiol. Rev. 78: 359–391, 1998. — The filament lattice of striated muscle is an overlapping hexagonal array of thick and thin filaments within which muscle contraction takes place. Its structure can be studied by electron microscopy or X-ray diffraction. With the latter technique, structural changes can be monitored during contraction and other physiological conditions. The lattice of intact muscle fibers can change size through osmotic swelling or shrinking or by changing the sarcomere length of the muscle. Similarly, muscle fibers that have been chemically or mechanically skinned can be compressed with bathing solutions containing very large inert polymeric molecules. The effects of lattice change on muscle contraction in vertebrate skeletal and cardiac muscle and in invertebrate striated muscle are reviewed. The force developed, the speed of shortening, and stiffness are compared with structural changes occurring within the lattice. Radial forces between the filaments in the lattice, which can include electrostatic, Van der Waals, entropic, structural, and cross bridge, are assessed for their contributions to lattice stability and to the contraction process.
Transduction Mechanisms in Vertebrate Olfactory Receptor Cells
Authors: SCHILD DETLEV , RESTREPO DIEGO
Published: December 2017

Schild, Detlev, and Diego Restrepo. Transduction Mechanisms in Vertebrate Olfactory Receptor Cells. Physiol. Rev. 78: 429–466, 1998. — Considerable progress has been made in the understanding of transduction mechanisms in olfactory receptor neurons (ORNs) over the last decade. Odorants pass through a mucus interface before binding to odorant receptors (ORs). The molecular structure of many ORs is now known. They belong to the large class of G protein-coupled receptors with seven transmembrane domains. Binding of an odorant to an OR triggers the activation of second messenger cascades. One second messenger pathway in particular has been extensively studied; the receptor activates, via the G protein Golf, an adenylyl cyclase, resulting in an increase in adenosine 3′,5′-cyclic monophosphate (cAMP), which elicits opening of cation channels directly gated by cAMP. Under physiological conditions, Ca2+has the highest permeability through this channel, and the increase in intracellular Ca2+concentration activates a Cl−current which, owing to an elevated reversal potential for Cl−, depolarizes the olfactory neuron. The receptor potential finally leads to the generation of action potentials conveying the chemosensory information to the olfactory bulb. Although much less studied, other transduction pathways appear to exist, some of which seem to involve the odorant-induced formation of inositol polyphosphates as well as Ca2+and/or inositol polyphosphate-activated cation channels. In addition, there is evidence for odorant-modulated K+and Cl−conductances. Finally, in some species, ORNs can be inhibited by certain odorants. This paper presents a comprehensive review of the biophysical and electrophysiological evidence regarding the transduction processes as well as subsequent signal processing and spike generation in ORNs.
Glomerular Mesangial Cells: Electrophysiology and Regulation of Contraction
Authors: STOCKAND JAMES D. , SANSOM STEVEN C.
Published: December 2017

Stockand, James D., and Steven C. Sansom. Glomerular Mesangial Cells: Electrophysiology and Regulation of Contraction. Physiol. Rev. 78: 723–744, 1998. — Mesangial cells are smooth muscle-like pericytes that abut and surround the filtration capillaries within the glomerulus. Studies of the fine ultrastructure of the glomerulus show that the mesangial cell and the capillary basement membrane form a biomechanical unit capable of regulating filtration surface area as well as intraglomerular blood volume. Structural and functional studies suggest that mesangial cells regulate filtration rate in both a static and dynamic fashion. Mesangial excitability enables a homeostatic intraglomerular stretch reflex that integrates an increase in filtration pressure with a reduction in capillary surface area. In addition, mesangial tone is regulated by diverse vasoactive hormones. Agonists, such as angiotensin II, contract mesangial cells through a signal transduction pathway that releases intracellular stores of Ca2+, which subsequently activate nonselective cation channels and Cl−channels to depolarize the plasma membrane. The change in membrane potential activates voltage-gated Ca2+channels, allowing Ca2+cell entry and further activation of depolarizing conductances. Contraction and entry of cell Ca2+are inhibited only when Ca2+-activated K+channels (BKCa) are activated and the membrane is hyperpolarized toward the K+equilibrium potential. The mesangial BKCais a weak regulator of contraction in unstimulated cells; however, the gain of the feedback is increased by atrial natriuretic peptide, nitric oxide, and the second messenger cGMP, which activates protein kinase G and decreases both the voltage and Ca2+activation thresholds of BKCaindependent of sensitivity. This enables BKCato more effectively counter membrane depolarization and voltage-gated Ca2+influx. After hyperpolarizing the membrane, BKCarapidly inactivates because of dephosphorylation by protein phosphatase 2A. Regulation of ion channels has been linked casually to hyperfiltration during early stages of diabetes mellitus. Determining the signaling pathways controlling the electrophysiology of glomerular mesangial cells is important for understanding how glomerular filtration rate is regulated in health and disease.
Understanding Adipocyte Differentiation
Authors: GREGOIRE FRANCINE M. , SMAS CYNTHIA M. , SUL HEI SOOK
Published: December 2017

Gregoire, Francine M., Cynthia M. Smas, and Hei Sook Sul. Understanding Adipocyte Differentiation. Physiol. Rev. 78: 783–809, 1998. — The adipocyte plays a critical role in energy balance. Adipose tissue growth involves an increase in adipocyte size and the formation of new adipocytes from precursor cells. For the last 20 years, the cellular and molecular mechanisms of adipocyte differentiation have been extensively studied using preadipocyte culture systems. Committed preadipocytes undergo growth arrest and subsequent terminal differentiation into adipocytes. This is accompanied by a dramatic increase in expression of adipocyte genes including adipocyte fatty acid binding protein and lipid-metabolizing enzymes. Characterization of regulatory regions of adipose-specific genes has led to the identification of the transcription factors peroxisome proliferator-activated receptor-γ (PPAR-γ) and CCAAT/enhancer binding protein (C/EBP), which play a key role in the complex transcriptional cascade during adipocyte differentiation. Growth and differentiation of preadipocytes is controlled by communication between individual cells or between cells and the extracellular environment. Various hormones and growth factors that affect adipocyte differentiation in a positive or negative manner have been identified. In addition, components involved in cell-cell or cell-matrix interactions such as preadipocyte factor-1 and extracellular matrix proteins are also pivotal in regulating the differentiation process. Identification of these molecules has yielded clues to the biochemical pathways that ultimately result in transcriptional activation via PPAR-γ and C/EBP. Studies on the regulation of the these transcription factors and the mode of action of various agents that influence adipocyte differentiation will reveal the physiological and pathophysiological mechanisms underlying adipose tissue development.
Current Understanding of the Molecular Actions of Vitamin D
Authors: JONES GLENVILLE , STRUGNELL STEPHEN A. , DeLUCA HECTOR F.
Published: December 2017

Jones, Glenville, Stephen A. Strugnell, and Hector F. DeLuca. Current Understanding of the Molecular Actions of Vitamin D. Physiol. Rev. 78: 1193–1231, 1998. — The important reactions that occur to the vitamin D molecule and the important reactions involved in the expression of the final active form of vitamin D are reviewed in a critical manner. After an overview of the metabolism of vitamin D to its active form and to its metabolic degradation products, the molecular understanding of the 1α-hydroxylation reaction and the 24-hydroxylation reaction of the vitamin D hormone is presented. Furthermore, the role of vitamin D in maintenance of serum calcium is reviewed at the physiological level and at the molecular level whenever possible. Of particular importance is the regulation of the parathyroid gland by the vitamin D hormone. A third section describes the known molecular events involved in the action of 1α,25-dihydroxyvitamin D3on its target cells. This includes reviewing what is now known concerning the overall mechanism of transcriptional regulation by vitamin D. It describes the vitamin D receptors that have been cloned and identified and describes the coactivators and retinoid X receptors required for the function of vitamin D in its genomic actions. The presence of receptor in previously uncharted target organs of vitamin D action has led to a study of the possible function of vitamin D in these organs. A good example of a new function described for 1α,25-dihydroxyvitamin D3is that found in the parathyroid gland. This is also true for the role of vitamin D hormone in skin, the immune system, a possible role in the pancreas, i.e., in the islet cells, and a possible role in female reproduction. This review also raises the intriguing question of whether vitamin D plays an important role in embryonic development, since vitamin D deficiency does not prohibit development, nor does vitamin D receptor knockout. The final section reviews some interesting analogs of the vitamin D hormone and their possible uses. The review ends with possible ideas with regard to future directions of vitamin D drug design.
Molecular Biology of Mammalian Plasma Membrane Amino Acid Transporters
Authors: PALACÍN MANUEL , ESTÉVEZ RAÚL , BERTRAN JOAN , ZORZANO ANTONIO
Published: December 2017

Palacı́n, Manuel, Raúl Estévez, Joan Bertran, and Antonio Zorzano. Molecular Biology of Mammalian Plasma Membrane Amino Acid Transporters. Physiol. Rev. 78: 969–1054, 1998. — Molecular biology entered the field of mammalian amino acid transporters in 1990–1991 with the cloning of the first GABA and cationic amino acid transporters. Since then, cDNA have been isolated for more than 20 mammalian amino acid transporters. All of them belong to four protein families. Here we describe the tissue expression, transport characteristics, structure-function relationship, and the putative physiological roles of these transporters. Wherever possible, the ascription of these transporters to known amino acid transport systems is suggested. Significant contributions have been made to the molecular biology of amino acid transport in mammals in the last 3 years, such as the construction of knockouts for the CAT-1 cationic amino acid transporter and the EAAT2 and EAAT3 glutamate transporters, as well as a growing number of studies aimed to elucidate the structure-function relationship of the amino acid transporter. In addition, the first gene ( rBAT) responsible for an inherited disease of amino acid transport (cystinuria) has been identified. Identifying the molecular structure of amino acid transport systems of high physiological relevance (e.g., system A, L, N, and x−c) and of the genes responsible for other aminoacidurias as well as revealing the key molecular mechanisms of the amino acid transporters are the main challenges of the future in this field.
Physiological Regulation of G Protein-Linked Signaling
Authors: Morris Andrew J. , Malbon Craig C.
Published: December 2017

Heterotrimeric G proteins in vertebrates constitute a family molecular switches that transduce the activation of a populous group of cell-surface receptors to a group of diverse effector units. The receptors include the photopigments such as rhodopsin and prominent families such as the adrenergic, muscarinic acetylcholine, and chemokine receptors involved in regulating a broad spectrum of responses in humans. Signals from receptors are sensed by heterotrimeric G proteins and transduced to effectors such as adenylyl cyclases, phospholipases, and various ion channels. Physiological regulation of G protein-linked receptors allows for integration of signals that directly or indirectly effect the signaling from receptor→G protein→effector(s). Steroid hormones can regulate signaling via transcriptional control of the activities of the genes encoding members of G protein-linked pathways. Posttranscriptional mechanisms are under physiological control, altering the stability of preexisting mRNA and affording an additional level for regulation. Protein phosphorylation, protein prenylation, and proteolysis constitute major posttranslational mechanisms employed in the physiological regulation of G protein-linked signaling. Drawing upon mechanisms at all three levels, physiological regulation permits integration of demands placed on G protein-linked signaling.
Genetic Analysis of Inherited Hypertension in the Rat
Authors: Rapp John P.
Published: December 2017

Blood pressure is a quantitative trait that has a strong genetic component in humans and rats. Several selectively bred strains of rats with divergent blood pressures serve as an animal model for genetic dissection of the causes of inherited hypertension. The goal is to identify the genetic loci controlling blood pressure, i.e., the so-called quantitative trait loci (QTL). The theoretical basis for such genetic dissection and recent progress in understanding genetic hypertension are reviewed. The usual paradigm is to produce segregating populations derived from a hypertensive and normotensive strain and to seek linkage of blood pressure to genetic markers using recently developed statistical techniques for QTL analysis. This has yielded candidate QTL regions on almost every rat chromosome, and also some interactions between QTL have been defined. These statistically defined QTL regions are much too large to practice positional cloning to identify the genes involved. Most investigators are, therefore, fine mapping the QTL using congenic strains to substitute small segments of chromosome from one strain into another. Although impressive progress has been made, this process is slow due to the extensive breeding that is required. At this point, no blood pressure QTL have met stringent criteria for identification, but this should be an attainable goal given the recently developed genomic resources for the rat. Similar experiments are ongoing to look for genes that influence cardiac hypertrophy, stroke, and renal failure and that are independent of the genes for hypertension.
Architecture of the Optic Chiasm and the Mechanisms That Sculpt Its Development
Authors: Jeffery Glen
Published: December 2017

At the optic chiasm the two optic nerves fuse, and fibers from each eye cross the midline or turn back and remain uncrossed. Having adopted their pathways the fibers separate to form the two optic tracts. Research into the architecture and development of the chiasm has become an area of increasing interest. Many of its mature features are complex and vary between different animal types. It is probable that numerous factors sculpt its development. The separate ganglion cell classes cross the midline at different locations along the length of the chiasm, reflecting their distinct periods of production as the chiasm develops in a caudo-rostral direction. In some mammals, uncrossed axons are mixed with crossed axons in each hemi-chiasm, whereas in others they remain segregated. These configurations are the product of different developmental mechanisms. The morphology of the chiasm changes significantly during development. Neurons, glia, and the signals they produce play a role in pathway selection. In some animals fiber-fiber interactions are also critical, but only where crossed and uncrossed pathways are mixed in each hemi-chiasm. The importance of the temporal dimension in chiasm development is emphasized by the fact that in some animals uncrossed ganglion cells are generated abnormally early in relation to their retinal location. Furthermore, in albinos, where many cells do not exit the cell cycle at normal times, there are systematic chiasmatic abnormalities in ganglion cell projections.
Ion Channels and Their Functional Role in Vascular Endothelium
Authors: Nilius Bernd , Droogmans Guy
Published: December 2017

Endothelial cells (EC) form a unique signal-transducing surface in the vascular system. The abundance of ion channels in the plasma membrane of these nonexcitable cells has raised questions about their functional role. This review presents evidence for the involvement of ion channels in endothelial cell functions controlled by intracellular Ca2+signals, such as the production and release of many vasoactive factors, e.g., nitric oxide and PGI2. In addition, ion channels may be involved in the regulation of the traffic of macromolecules by endocytosis, transcytosis, the biosynthetic-secretory pathway, and exocytosis, e.g., tissue factor pathway inhibitor, von Willebrand factor, and tissue plasminogen activator. Ion channels are also involved in controlling intercellular permeability, EC proliferation, and angiogenesis. These functions are supported or triggered via ion channels, which either provide Ca2+-entry pathways or stabilize the driving force for Ca2+influx through these pathways. These Ca2+-entry pathways comprise agonist-activated nonselective Ca2+-permeable cation channels, cyclic nucleotide-activated nonselective cation channels, and store-operated Ca2+channels or capacitative Ca2+entry. At least some of these channels appear to be expressed by genes of the trp family. The driving force for Ca2+entry is mainly controlled by large-conductance Ca2+-dependent BKCachannels ( slo), inwardly rectifying K+channels (Kir2.1), and at least two types of Cl−channels, i.e., the Ca2+-activated Cl−channel and the housekeeping, volume-regulated anion channel (VRAC). In addition to their essential function in Ca2+signaling, VRAC channels are multifunctional, operate as a transport pathway for amino acids and organic osmolytes, and are possibly involved in endothelial cell proliferation and angiogenesis. Finally, we have also highlighted the role of ion channels as mechanosensors in EC. Plasmalemmal ion channels may signal rapid changes in hemodynamic forces, such as shear stress and biaxial tensile stress, but also changes in cell shape and cell volume to the cytoskeleton and the intracellular machinery for metabolite traffic and gene expression.
Selection of the Optimal Algorithm for Real-Time Estimation of Beta Band Power during DBS Surgeries in Patients with Parkinson’s Disease
Authors: Tepper Ángeles , Henrich Mauricio Carlos , Schiaffino Luciano , Rosado Muñoz Alfredo , Gutiérrez Antonio , Guerrero Martínez Juan
Published: December 2017

Deep Brain Stimulation (DBS) is a surgical procedure for the treatment of motor disorders in patients with Parkinson’s Disease (PD). DBS involves the application of controlled electrical stimuli to a given brain structure. The implantation of the electrodes for DBS is performed by a minimally invasive stereotactic surgery where neuroimaging and microelectrode recordings (MER) are used to locate the target brain structure. The Subthalamic Nucleus (STN) is often chosen for the implantation of stimulation electrodes in DBS therapy. During the surgery, an intraoperative validation is performed to locate the dorsolateral region of STN. Patients with PD reveal a high power in the β band (frequencies between 13 Hz and 35 Hz) in MER signal, mainly in the dorsolateral region of STN. In this work, different power spectrum density methods were analyzed with the aim of selecting one that minimizes the calculation time to be used in real time during DBS surgery. In particular, the results of three nonparametric and one parametric methods were compared, each with different sets of parameters. It was concluded that the optimum method to perform the real-time spectral estimation of beta band from MER signal is Welch with Hamming windows of 1.5 seconds and 50% overlap.
Finite-Time Stability and Controller Design of Continuous-Time Polynomial Fuzzy Systems
Authors: Chen Xiaoxing , Hu Manfeng
Published: December 2017

Finite-time stability and stabilization problem is first investigated for continuous-time polynomial fuzzy systems. The concept of finite-time stability and stabilization is given for polynomial fuzzy systems based on the idea of classical references. A sum-of-squares- (SOS-) based approach is used to obtain the finite-time stability and stabilization conditions, which include some classical results as special cases. The proposed conditions can be solved with the help of powerful Matlab toolbox SOSTOOLS and a semidefinite-program (SDP) solver. Finally, two numerical examples and one practical example are employed to illustrate the validity and effectiveness of the provided conditions.
Efficient Data Forwarding for Machine Type Communications in Internet of Things Networks
Authors: Lim Yujin , Park Jaesung
Published: December 2017

The MTC (Machine Type Communications) system is one of the most promising technologies to provide IoT (Internet of Things) applications. The MTC system suffers from congestion due to limited data transmission capacity and burst traffic. The congestion disturbs data delivery, results in an increase of energy consumption due to data retransmission, and finally poses a threat to the providers of IoT applications. In this paper, we focus on the congestion problem and present an efficient data forwarding mechanism to regulate the burst channel access from a large number of MTC devices. To regulate the communication channel access from the devices, we predict the number of devices by separating traffic load into the prediction of the number of devices that newly attempt to have access and the prediction of the number of devices that retry to access the channel. Through simulations, we show that our mechanism improves access success probability and reduces collision probability and access delay.
Etiology and Long‐Term Outcome of Patients Undergoing Pericardiocentesis
Authors: Strobbe Alexander , Adriaenssens Tom , Bennett Johan , Dubois Christophe , Desmet Walter , McCutcheon Keir , Van Cleemput Johan , Sinnaeve Peter R
Published: December 2017

Background

Pericardial effusions can be caused by a variety of disorders. The frequency of the underlying diseases varies with patient population; therefore, previously reported series are not necessarily representative of other populations. Our purpose was to examine the etiology of pericardial effusions and the survival of patients requiring pericardiocentesis at a tertiary center.

Methods and Results

We performed a retrospective observational study of 269 consecutive patients who underwent percutaneous pericardiocentesis at our university hospital between 2006 and 2016 and had prospective follow‐up for up to 10 years. The most frequent etiologies were idiopathic (26%), malignancy (25%), and iatrogenicity (20%), whereas bacterial causes were very rare. The most frequent malignancies originated from the lung (53%) or breast (18%). A new cancer was diagnosed with malignant pericardial effusion as the presenting complaint for 9% of patients, whereas the pericardium was the first metastatic site of a known malignancy in 4% of patients. Survival was significantly poorer in malignancy‐related versus non–malignancy‐related effusions (
P
<0.001) and in cytology‐positive versus cytology‐negative effusions in the overall cohort (
P
<0.001). Among cancer‐only patients, however, there was no significant difference in long‐term survival between cytology‐positive and ‐negative effusions.

Conclusions

In this contemporary tertiary‐center cohort, pericardial effusions often represent the primary instance of a new malignancy, underscoring the importance of cytological analyses of noniatrogenic effusions in patients without known cancer, as survival is significantly worse. In cancer patients, however, the presence of pericardial malignant cytology does not appear to affect outcome significantly.
Advice for festive drinkers
Authors: Hadis Mohammed A , Palin William M , Perryer D Giles , Burke FJ Trevor
Published: December 2017

Abstract: The incidence of tooth wear is rising, worldwide, with extrinsic and intrinsic erosion being involved in many cases. A variety of drinks have been considered to be implicated, for example, fresh fruit juices, carbonated beverages, alcoholic drinks and energy/sports drinks. However, there are a number of beverages which do not appear to have been tested, such as sparkling wines and various types of champagne and sparkling fruit juice, these being drinks that are typically consumed at times of celebration such as religious festivals, birthdays, etc. It is therefore the purpose of this paper to test the acidity of these festive drinks and to provide advice to consumers thereof.

CPD/Clinical Relevance: Some sparkling alcoholic and non-alcoholic drinks may be erosive to patients' teeth, depending upon the volume consumed.
Implementing IBD Registry audit tools in a nurse-led inflammatory bowel disease service at a district general hospital
Authors: Avery Pearl , Wilson Rosetta , Munro Claire
Published: December 2017

Inflammatory bowel disease (IBD) is a chronic condition with no known cure. Continual auditing of patients is an important part of developing and refining therapies, including biologics, for inducing and maintaining remission. Between 2006 and 2016, the IBD National Audit gathered data that showed how services should improve standards to meet patient needs. This was followed by the IBD Registry, a multi-agency initiative to enable local teams to electronically record clinical data at the point of care to benefit patients, clinicians, commissioners and managers. The service integrates with existing hospital systems and uses a patient management system (PMS), a web tool for real-time data collection and a data visualisation tool for biologics. As of 2017, there were 99 participating sites, with data from 31 614 patients. A district general hospital successfully implemented the registry auditing tools, despite initial administrative challenges; the IBD team have used the data to demonstrate the value of the specialist nursing service, expanding it by recruiting another 0.6 whole-time equivalent nurse. The PMS offered more robust tools for monitoring complex, high-cost treatments, such as biologics.
The effects of Panafil when using topical negative pressure to heal an infected sternal wound
Authors: Melano E. , Rodriguez H.L. , Carillo R. , Dillon L.
Published: December 2017

This case report describes the use of Panafil (Healthpoint, Fort Worth, Texas, USA) alongside topical negative pressure (TNP) therapy in the treatment of a patient with an infected sternal wound. The wound resulted from an infection sustained following coronary artery bypass graft (CABG) surgery. The patient had diabetes mellitus type 2, and thus was predisposed to slower wound healing, an increased risk of infection and other concomitant comorbidities such as neuropathies, vision impairments, kidney dysfunction and cardiac complications.
Control of abortion in sheep: a risk-based approach
Authors: Crilly James Patrick , Gascoigne Emily
Published: December 2017

Abortion is a significant cost to the British sheep industry, outbreaks can severely affect flock productivity and many agents pose a zoonotic risk. As such, effective control measures are a vital part of flock health planning. This article outlines a risk-based approach to the control of ovine abortion.
Book Review and Reflection
Authors: Zotte Jennifer Le
Published: December 2017

From Goodwill to Grunge: A History of Secondhand Styles and Alternative Economies, Jennifer Le Zotte (2017, first edition) Chapel Hill: North Carolina University Press, 336 pp., ISBN: 9781469631905, Paperback, $27.95
Las evaluaciones internas del sistema nacional de investigadores de México a través de un análisis clúster
Authors: Reyes Ruiz Gerardo
Published: December 2017

El Sistema Nacional de Investigadores de México (SNI) evalúa, selecciona y reconoce, mediante un estímulo económico, el capital humano nacional que realiza investigación de calidad. Esta logística puede ser considerada como una selección de proyectos, la cual conlleva, obligatoriamente, a la elección de capital humano especializado. En este artículo se utiliza la técnica de análisis y agrupamiento de datos conocida como clustering (k Means) para profundizar sobre los criterios seguidos por el SNI en cuanto a dicha elección de investigadores. Una vez que se conoce el perfil productivo de cada nombramiento definido por el SNI, y a través de la distancia de Hamming, se realiza un análisis comparativo entre los datos estimados y reales asociados a cada nombramiento. Las estimaciones permitieron concluir que no se justifica la actual clasificación en cuatro agrupaciones (nombramientos), tal vez ello se deba a que los evaluadores del SNI utilizan información no recolectada en las variables reportadas por las solicitudes. Además, se demuestra la necesidad de mejorar la información estadística utilizada como base de datos para la evaluación; se señalan las diferencias en las clasificaciones estimadas para las siete áreas del conocimiento definidas por el SNI y se recomiendan algunos de los resultados para complementar las evaluaciones por pares, realizadas actualmente, siempre que se mejore la cantidad y calidad de la información disponible. Sin duda, ello debe de servir para hacer más eficiente la futura selección de proyectos de investigación y desarrollo concernientes a un programa de la política pública de investigación en México.
Análisis de la dependencia de la acreditación institucional: Un estudio comparativo de universidades en Chile
Authors: Huerta-Riveros Patricia Carolina , Gaete-Feres Héctor Guillermo
Published: December 2017

El presente artículo tiene como objetivo analizar la dependencia organizacional de la unidad encargada del proceso de acreditación institucional en las universidades chilenas. Para ello, se realizó un análisis cuantitativo y descriptivo de las universidades chilenas acreditadas del Consejo de Rectores y de las Universidades Privadas al año 2015. Lo anterior, a partir de información obtenida de la Comisión Nacional de Acreditación, de las páginas web e información telefónica de las universidades. Los análisis estadísticos incluyeron estadísticas descriptivas, tablas de contingencias y análisis de correspondencias múltiples. Los resultados del estudio evidencian que en las universidades del Consejo de Rectores de las Universidades Chilenas (CRUCH), el 72% de las unidades encargadas de la acreditación institucional dependen de rectoría, a diferencia de las universidades privadas que representan un 58%. Mediante la aplicación de un análisis de correspondencias múltiples comparativo entre ambos tipos de universidad, se descubre, principalmente, una asociación entre aquellas universidades cuya unidad encargada del proceso de acreditación depende de una rectoría y presenta 4 o 5 años y 3 o 4 áreas de acreditación. De igual manera, el estudio evidencia una asociación entre las universidades que obtienen 5 áreas y 6 o 7 años, sin ser relevante, en estos casos, el tipo de universidad. Por lo tanto, se concluye que la naturaleza jurídica de una institución, sea del CRUCH o privada, no se asocia necesariamente con una mejor calidad. En definitiva, los resultados permiten confirmar la hipótesis bajo estudio, es decir, no existe asociación significativa entre la dependencia organizacional y los resultados obtenidos en el proceso de acreditación.
Los Juegos cooperativos y el acceso a la información desde la extensión Universitaria
Authors: Calvo Sánchez Loirette
Published: December 2017

Desde el proyecto de extensión conocimiento paz y gestión social se desarrolló un taller en la comunidad de Guararí de Heredia, titulado cada pollo con su rollo en el que participaron 12 mujeres en edades entre 12 y 18 años, 6 varones en edades de 10 a 17. Donde se uso el juego cooperativo como metodología participativa, con el propósito de dar acceso a la información y a procesos de alfabetización informacional en materia de derechos humanos usando un lenguaje sencillo que pudiera ser comprendido  por los participantes.
A la luz de una candela: aportes de Ricardo Chinchilla a la narrativa costarricense.
Authors: Vargas Vargas José Ángel
Published: December 2017

Las motivaciones de Ricardo Chinchilla al escribir su libro A la luz de una candela, publicado en el 2016. En una entrevista que le realicé a este autor el 3 de marzo de 2017, él manifestó que los cuentos de este libro los escribió en una primera versión cuando estaba en el colegio, hace aproximadamente treinta años y habían permanecido inalterados hasta que se propuso publicarlos con el fin de preservar un patrimonio, colocarlos en una dimensión educativa y con ello plasmar su trabajo como escritor. Para él, escribir estos cuentos ha sido una experiencia de placer, placer por transmitir unas historias, por sacarlas de su interior.