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Showing papers in "Physiological Reviews in 2003"


Journal ArticleDOI
TL;DR: This review summarizes the results of expression studies that have been performed in rodents, pigs, and humans to localize growth factors and their receptors in skin wounds and reports on genetic studies addressing the functions of endogenous growth factors in the wound repair process.
Abstract: Werner, Sabine, and Richard Grose. Regulation of Wound Healing by Growth Factors and Cytokines. Physiol Rev 83: 835–870, 2003; 10.1152/physrev.00032.2002.—Cutaneous wound healing is a complex proce...

3,234 citations


Journal ArticleDOI
Darrell E Goll1, Valery F. Thompson1, Hongqi Li1, Wei Wei1, Jinyang Cong1 
TL;DR: How calpain activity is regulated in cells is still unclear, but the calpains ostensibly participate in a variety of cellular processes including remodeling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis.
Abstract: The calpain system originally comprised three molecules: two Ca2+-dependent proteases, mu-calpain and m-calpain, and a third polypeptide, calpastatin, whose only known function is to inhibit the two calpains. Both mu- and m-calpain are heterodimers containing an identical 28-kDa subunit and an 80-kDa subunit that shares 55-65% sequence homology between the two proteases. The crystallographic structure of m-calpain reveals six "domains" in the 80-kDa subunit: 1). a 19-amino acid NH2-terminal sequence; 2). and 3). two domains that constitute the active site, IIa and IIb; 4). domain III; 5). an 18-amino acid extended sequence linking domain III to domain IV; and 6). domain IV, which resembles the penta EF-hand family of polypeptides. The single calpastatin gene can produce eight or more calpastatin polypeptides ranging from 17 to 85 kDa by use of different promoters and alternative splicing events. The physiological significance of these different calpastatins is unclear, although all bind to three different places on the calpain molecule; binding to at least two of the sites is Ca2+ dependent. Since 1989, cDNA cloning has identified 12 additional mRNAs in mammals that encode polypeptides homologous to domains IIa and IIb of the 80-kDa subunit of mu- and m-calpain, and calpain-like mRNAs have been identified in other organisms. The molecules encoded by these mRNAs have not been isolated, so little is known about their properties. How calpain activity is regulated in cells is still unclear, but the calpains ostensibly participate in a variety of cellular processes including remodeling of cytoskeletal/membrane attachments, different signal transduction pathways, and apoptosis. Deregulated calpain activity following loss of Ca2+ homeostasis results in tissue damage in response to events such as myocardial infarcts, stroke, and brain trauma.

2,731 citations


Journal ArticleDOI
TL;DR: It is suggested that the RhoA/ROK pathway is constitutively active in a number of organs under physiological conditions; its aberrations play major roles in several disease states, particularly impacting on Ca2+ sensitization of smooth muscle in hypertension and possibly asthma and on cancer neoangiogenesis and cancer progression.
Abstract: Somlyo, Andrew P., and Avril V. Somlyo. Ca2+ Sensitivity of Smooth Muscle and Nonmuscle Myosin II: Modulated by G Proteins, Kinases, and Myosin Phosphatase. Physiol Rev 83: 1325-1358, 2003; 10.1152...

1,923 citations


Journal ArticleDOI
TL;DR: The goal of this review is to provide a comprehensive description of T-type currents, their distribution, regulation, pharmacology, and cloning.
Abstract: T-type Ca2+ channels were originally called low-voltage-activated (LVA) channels because they can be activated by small depolarizations of the plasma membrane. In many neurons Ca2+ influx through L...

1,620 citations


Journal ArticleDOI
TL;DR: The synthetic pathways of endocannabinoids are discussed, along with the putative mechanisms of their release, uptake, and degradation, and the fine-grain anatomical distribution of the neuronal cannabinoid receptor CB1 is described in most brain areas, emphasizing its general presynaptic localization and role in controlling neurotransmitter release.
Abstract: Research of cannabinoid actions was boosted in the 1990s by remarkable discoveries including identification of endogenous compounds with cannabimimetic activity (endocannabinoids) and the cloning of their molecular targets, the CB1 and CB2 receptors. Although the existence of an endogenous cannabinoid signaling system has been established for a decade, its physiological roles have just begun to unfold. In addition, the behavioral effects of exogenous cannabinoids such as delta-9-tetrahydrocannabinol, the major active compound of hashish and marijuana, await explanation at the cellular and network levels. Recent physiological, pharmacological, and high-resolution anatomical studies provided evidence that the major physiological effect of cannabinoids is the regulation of neurotransmitter release via activation of presynaptic CB1 receptors located on distinct types of axon terminals throughout the brain. Subsequent discoveries shed light on the functional consequences of this localization by demonstrating the involvement of endocannabinoids in retrograde signaling at GABAergic and glutamatergic synapses. In this review, we aim to synthesize recent progress in our understanding of the physiological roles of endocannabinoids in the brain. First, the synthetic pathways of endocannabinoids are discussed, along with the putative mechanisms of their release, uptake, and degradation. The fine-grain anatomical distribution of the neuronal cannabinoid receptor CB1 is described in most brain areas, emphasizing its general presynaptic localization and role in controlling neurotransmitter release. Finally, the possible functions of endocannabinoids as retrograde synaptic signal molecules are discussed in relation to synaptic plasticity and network activity patterns.

1,511 citations


Journal ArticleDOI
TL;DR: The anatomical and physiological substrates proposed to underlie amygdala function are examined, suggesting that long-term synaptic plasticity of inputs to the amygdala underlies the acquisition and perhaps storage of the fear memory.
Abstract: Sah, P., E. S. L. Faber, M. Lopez de Armentia, and J. Power. The Amygdaloid Complex: Anatomy and Physiology. Physiol Rev 83: 803–834, 2003; 10.1152/physrev.00002.2003.—A converging body of literatu...

1,474 citations


Journal ArticleDOI
TL;DR: This review integrates recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier with hereditary nephrotic syndromes identified over the last 2 years.
Abstract: Glomerular podocytes are highly specialized cells with a complex cytoarchitecture. Their most prominent features are interdigitated foot processes with filtration slits in between. These are bridged by the slit diaphragm, which plays a major role in establishing the selective permeability of the glomerular filtration barrier. Injury to podocytes leads to proteinuria, a hallmark of most glomerular diseases. New technical approaches have led to a considerable increase in our understanding of podocyte biology including protein inventory, composition and arrangement of the cytoskeleton, receptor equipment, and signaling pathways involved in the control of ultrafiltration. Moreover, disturbances of podocyte architecture resulting in the retraction of foot processes and proteinuria appear to be a common theme in the progression of acquired glomerular disease. In hereditary nephrotic syndromes identified over the last 2 years, all mutated gene products were localized in podocytes. This review integrates our recent physiological and molecular understanding of the role of podocytes during the maintenance and failure of the glomerular filtration barrier.

1,358 citations


Journal ArticleDOI
TL;DR: The physiological role of gap junctions in several tissues has been elucidated by the discovery of mutant connexins associated with genetic diseases and by the generation of mice with targeted ablation of specific connexin genes.
Abstract: Saez, Juan C., Viviana M. Berthoud, Maria C. Branes, Agustin D. Martinez, and Eric C. Beyer. Plasma Membrane Channels Formed by Connexins: Their Regulation and Functions. Physiol Rev 83: 1359-1400,...

1,099 citations


Journal ArticleDOI
TL;DR: The understanding of the mechanisms associated with preconditioning are unravelled can look forward to the development of new therapeutic agents with novel mechanisms of action that can supplement current treatment options for patients threatened with acute myocardial infarction.
Abstract: Yellon, Derek M., and James M. Downey. Preconditioning the Myocardium: From Cellular Physiology to Clinical Cardiology. Physiol Rev 83: 1113-1151, 2003; 10.1152/physrev.00009.2003.—The phenomenon o...

1,089 citations


Journal ArticleDOI
TL;DR: Several ABPs that regulate actin-driven assembly, i.e., movement that is independent of motor proteins, are selected that represent a family of related proteins in nature and are widely distributed in nature.
Abstract: The actin cytoskeleton is a complex structure that performs a wide range of cellular functions. In 2001, significant advances were made to our understanding of the structure and function of actin m...

1,038 citations


Journal ArticleDOI
TL;DR: Detailed understanding of hibernation from the molecular to organismal levels should enable the translation of this information to the development of a variety of hypothermic and hypometabolic strategies to improve outcomes for human and animal health.
Abstract: Carey, Hannah V., Matthew T. Andrews, and Sandra L. Martin. Mammalian Hibernation: Cellular and Molecular Responses to Depressed Metabolism and Low Temperature. Physiol Rev 83: 1153-1181, 2003; 10....

Journal ArticleDOI
TL;DR: This review is a comprehensive summary of current knowledge of the molecular characterization, function, and regulation of bile salt transporters in normal physiology and in cholestatic liver disease and liver regeneration.
Abstract: Molecular medicine has led to rapid advances in the characterization of hepatobiliary transport systems that determine the uptake and excretion of bile salts and other biliary constituents in the l...

Journal ArticleDOI
TL;DR: The wide range of cell types in which regulated secretory granule exocytosis occurs is described and the evidence for the expression of the conserved fusion machinery in these cells is assessed.
Abstract: Regulated exocytosis of secretory granules or dense-core granules has been examined in many well-characterized cell types including neurons, neuroendocrine, endocrine, exocrine, and hemopoietic cells and also in other less well-studied cell types. Secretory granule exocytosis occurs through mechanisms with many aspects in common with synaptic vesicle exocytosis and most likely uses the same basic protein components. Despite the widespread expression and conservation of a core exocytotic machinery, many variations occur in the control of secretory granule exocytosis that are related to the specialized physiological role of particular cell types. In this review we describe the wide range of cell types in which regulated secretory granule exocytosis occurs and assess the evidence for the expression of the conserved fusion machinery in these cells. The signals that trigger and regulate exocytosis are reviewed. Aspects of the control of exocytosis that are specific for secretory granules compared with synaptic vesicles or for particular cell types are described and compared to define the range of accessory control mechanisms that exert their effects on the core exocytotic machinery.

Journal ArticleDOI
TL;DR: The regulation of pH is a vital homeostatic function shared by all tissues, and mechanisms responsible for the regulation of intracellular pH in brain are similar to those of other tissues, but differences in the expression or efficacy of these mechanisms have been noted among the functionally and morphologically diverse neurons and glial cells that have been studied.
Abstract: Chesler, Mitchell. Regulation and Modulation of pH in the Brain. Physiol Rev 83: 1183-1221, 2003; 10.1152/physrev.00010.2003.—The regulation of pH is a vital homeostatic function shared by all tiss...

Journal ArticleDOI
TL;DR: The topographical arrangement of the distinct cardiac muscle cells in the forming heart explains the embryonic electrocardiogram (ECG), does not require the invention of nodes, and allows a logical transition from a peristaltic tubular heart to a synchronously contracting four-chambered heart.
Abstract: Concepts of cardiac development have greatly influenced the description of the formation of the four-chambered vertebrate heart. Traditionally, the embryonic tubular heart is considered to be a composite of serially arranged segments representing adult cardiac compartments. Conversion of such a serial arrangement into the parallel arrangement of the mammalian heart is difficult to understand. Logical integration of the development of the cardiac conduction system into the serial concept has remained puzzling as well. Therefore, the current description needed reconsideration, and we decided to evaluate the essentialities of cardiac design, its evolutionary and embryonic development, and the molecular pathways recruited to make the four-chambered mammalian heart. The three principal notions taken into consideration are as follows. 1) Both the ancestor chordate heart and the embryonic tubular heart of higher vertebrates consist of poorly developed and poorly coupled "pacemaker-like" cardiac muscle cells with the highest pacemaker activity at the venous pole, causing unidirectional peristaltic contraction waves. 2) From this heart tube, ventricular chambers differentiate ventrally and atrial chambers dorsally. The developing chambers display high proliferative activity and consist of structurally well-developed and well-coupled muscle cells with low pacemaker activity, which permits fast conduction of the impulse and efficacious contraction. The forming chambers remain flanked by slowly proliferating pacemaker-like myocardium that is temporally prevented from differentiating into chamber myocardium. 3) The trabecular myocardium proliferates slowly, consists of structurally poorly developed, but well-coupled, cells and contributes to the ventricular conduction system. The atrial and ventricular chambers of the formed heart are activated and interconnected by derivatives of embryonic myocardium. The topographical arrangement of the distinct cardiac muscle cells in the forming heart explains the embryonic electrocardiogram (ECG), does not require the invention of nodes, and allows a logical transition from a peristaltic tubular heart to a synchronously contracting four-chambered heart. This view on the development of cardiac design unfolds fascinating possibilities for future research.

Journal ArticleDOI
TL;DR: Voltage-gated proton channels represent a specific subset of proton channel that have voltage- and time-dependent gating like other ion channels, but differ from most ion channels in their extraordinarily high selectivity, tiny conductance, strong temperature and deuterium isotope effects on conductance and gating kinetics, and insensitivity to block by steric occlusion.
Abstract: Proton channels exist in a wide variety of membrane proteins where they transport protons rapidly and efficiently. Usually the proton pathway is formed mainly by water molecules present in the protein, but its function is regulated by titratable groups on critical amino acid residues in the pathway. All proton channels conduct protons by a hydrogen-bonded chain mechanism in which the proton hops from one water or titratable group to the next. Voltage-gated proton channels represent a specific subset of proton channels that have voltage- and time-dependent gating like other ion channels. However, they differ from most ion channels in their extraordinarily high selectivity, tiny conductance, strong temperature and deuterium isotope effects on conductance and gating kinetics, and insensitivity to block by steric occlusion. Gating of H+ channels is regulated tightly by pH and voltage, ensuring that they open only when the electrochemical gradient is outward. Thus they function to extrude acid from cells. H+ch...

Journal ArticleDOI
TL;DR: In relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated, and linkage of this blood- heart barrier to the various other endothelia-mediated signaling pathways or to the putative vascular endothelialium-derived hyperpolarizing factors remains to be determined.
Abstract: Experimental work during the past 15 years has demonstrated that endothelial cells in the heart play an obligatory role in regulating and maintaining cardiac function, in particular, at the endocardium and in the myocardial capillaries where endothelial cells directly interact with adjacent cardiomyocytes. The emerging field of targeted gene manipulation has led to the contention that cardiac endothelial-cardiomyocytal interaction is a prerequisite for normal cardiac development and growth. Some of the molecular mechanisms and cellular signals governing this interaction, such as neuregulin, vascular endothelial growth factor, and angiopoietin, continue to maintain phenotype and survival of cardiomyocytes in the adult heart. Cardiac endothelial cells, like vascular endothelial cells, also express and release a variety of auto- and paracrine agents, such as nitric oxide, endothelin, prostaglandin I(2), and angiotensin II, which directly influence cardiac metabolism, growth, contractile performance, and rhythmicity of the adult heart. The synthesis, secretion, and, most importantly, the activities of these endothelium-derived substances in the heart are closely linked, interrelated, and interactive. It may therefore be simplistic to try and define their properties independently from one another. Moreover, in relation specifically to the endocardial endothelium, an active transendothelial physicochemical gradient for various ions, or blood-heart barrier, has been demonstrated. Linkage of this blood-heart barrier to the various other endothelium-mediated signaling pathways or to the putative vascular endothelium-derived hyperpolarizing factors remains to be determined. At the early stages of cardiac failure, all major cardiovascular risk factors may cause cardiac endothelial activation as an adaptive response often followed by cardiac endothelial dysfunction. Because of the interdependency of all endothelial signaling pathways, activation or disturbance of any will necessarily affect the others leading to a disturbance of their normal balance, leading to further progression of cardiac failure.

Journal ArticleDOI
TL;DR: The authors' knowledge of the different cell types using transcytosis in vivo, the variety of cargo moved, and the diverse pathways for delivering that cargo are summarized.
Abstract: Transcytosis, the vesicular transport of macromolecules from one side of a cell to the other, is a strategy used by multicellular organisms to selectively move material between two environments without altering the unique compositions of those environments. In this review, we summarize our knowledge of the different cell types using transcytosis in vivo, the variety of cargo moved, and the diverse pathways for delivering that cargo. We evaluate in vitro models that are currently being used to study transcytosis. Caveolae-mediated transcytosis by endothelial cells that line the microvasculature and carry circulating plasma proteins to the interstitium is explained in more detail, as is clathrin-mediated transcytosis of IgA by epithelial cells of the digestive tract. The molecular basis of vesicle traffic is discussed, with emphasis on the gaps and uncertainties in our understanding of the molecules and mechanisms that regulate transcytosis. In our view there is still much to be learned about this fundamental process.

Journal ArticleDOI
TL;DR: Evidence is presented for and against both the participation of classic receptors, or proteins closely related to them, as well as for the involvement of yet poorly understood, novel membrane steroid receptors.
Abstract: Losel, Ralf M., Elisabeth Falkenstein, Martin Feuring, Armin Schultz, Hanns-Christian Tillmann, Karin Rossol-Haseroth, and Martin Wehling. Nongenomic Steroid Action: Controversies, Questions, and A...

Journal ArticleDOI
Torben Clausen1
TL;DR: The Na+-K+ pump is a central target for regulation of Na-k+ distribution and excitability, essential for second-to-second ongoing maintenance of excitability during work.
Abstract: In skeletal muscle, excitation may cause loss of K+, increased extracellular K+ ([K+]o), intracellular Na+ ([Na+]i), and depolarization. Since these events interfere with excitability, the processes of excitation can be self-limiting. During work, therefore, the impending loss of excitability has to be counterbalanced by prompt restoration of Na+-K+ gradients. Since this is the major function of the Na+-K+ pumps, it is crucial that their activity and capacity are adequate. This is achieved in two ways: 1) by acute activation of the Na+-K+ pumps and 2) by long-term regulation of Na+-K+ pump content or capacity. 1) Depending on frequency of stimulation, excitation may activate up to all of the Na+-K+ pumps available within 10 s, causing up to 22-fold increase in Na+ efflux. Activation of the Na+-K+ pumps by hormones is slower and less pronounced. When muscles are inhibited by high [K+]o or low [Na+]o, acute hormone- or excitation-induced activation of the Na+-K+ pumps can restore excitability and contractile force in 10-20 min. Conversely, inhibition of the Na+-K+ pumps by ouabain leads to progressive loss of contractility and endurance. 2) Na+-K+ pump content is upregulated by training, thyroid hormones, insulin, glucocorticoids, and K+ overload. Downregulation is seen during immobilization, K+ deficiency, hypoxia, heart failure, hypothyroidism, starvation, diabetes, alcoholism, myotonic dystrophy, and McArdle disease. Reduced Na+-K+ pump content leads to loss of contractility and endurance, possibly contributing to the fatigue associated with several of these conditions. Increasing excitation-induced Na+ influx by augmenting the open-time or the content of Na+ channels reduces contractile endurance. Excitability and contractility depend on the ratio between passive Na+-K+ leaks and Na+-K+ pump activity, the passive leaks often playing a dominant role. The Na+-K+ pump is a central target for regulation of Na+-K+ distribution and excitability, essential for second-to-second ongoing maintenance of excitability during work.

Journal ArticleDOI
TL;DR: The molecular analysis of invasion-associated cellular activities, namely, homotypic and heterotypic cell-cell adhesion, cell-matrix interactions and ectopic survival, migration, and proteolysis, reveal branching signal transduction pathways with extensive networks between individual pathways.
Abstract: Invasion causes cancer malignancy. We review recent data about cellular and molecular mechanisms of invasion, focusing on cross-talk between the invaders and the host. Cancer disturbs these cellular activities that maintain multicellular organisms, namely, growth, differentiation, apoptosis, and tissue integrity. Multiple alterations in the genome of cancer cells underlie tumor development. These genetic alterations occur in varying orders; many of them concomitantly influence invasion as well as the other cancer-related cellular activities. Examples discussed are genes encoding elements of the cadherin/catenin complex, the nonreceptor tyrosine kinase Src, the receptor tyrosine kinases c-Met and FGFR, the small GTPase Ras, and the dual phosphatase PTEN. In microorganisms, invasion genes belong to the class of virulence genes. There are numerous clinical and experimental observations showing that invasion results from the cross-talk between cancer cells and host cells, comprising myofibroblasts, endothelial cells, and leukocytes, all of which are themselves invasive. In bone metastases, host osteoclasts serve as targets for therapy. The molecular analysis of invasion-associated cellular activities, namely, homotypic and heterotypic cell-cell adhesion, cell-matrix interactions and ectopic survival, migration, and proteolysis, reveal branching signal transduction pathways with extensive networks between individual pathways. Cellular responses to invasion-stimulatory molecules such as scatter factor, chemokines, leptin, trefoil factors, and bile acids or inhibitory factors such as platelet activating factor and thrombin depend on activation of trimeric G proteins, phosphoinositide 3-kinase, and the Rac and Rho family of small GTPases. The role of proteolysis in invasion is not limited to breakdown of extracellular matrix but also causes cleavage of proinvasive fragments from cell surface glycoproteins.

Journal ArticleDOI
TL;DR: Oxygen gradients measured in the arteriolar wall provide evidence that this structure in vivo is a very large oxygen sink, and suggests a rate of oxygen consumption two orders of magnitude greater than seen in in vitro studies.
Abstract: Tsai, Amy G., Paul C. Johnson, and Marcos Intaglietta. Oxygen Gradients in the Microcirculation. Physiol Rev 83: 933–963, 2003; 10.1152/physrev.00034.2002.—As arterialized blood transits from the c...

Journal ArticleDOI
TL;DR: New data emerging from studies using transgenic animals have provided novel insights into many of the cellular interactions and signaling mechanisms involving monocytes/macrophages in the atherogenic processes, focusing on mechanisms for monocyte activation and the roles of adhesive molecules, chemokines, cytokines and growth factors.
Abstract: Osterud, Bjarne, and Eirik Bjorklid. Role of Monocytes in Atherogenesis. Physiol Rev 83: 1069-1112, 2003; 10.1152/physrev.00005.2003.—This review focuses on the role of monocytes in the early phase...

Journal ArticleDOI
TL;DR: The evidence that transport of L-arginine and glucose in endothelial and smooth muscle cells is modulated by bacterial endotoxin, proinflammatory cytokines, and atherogenic lipids is critically reviewed.
Abstract: While transport processes for amino acids and glucose have long been known to be expressed in the luminal and abluminal membranes of the endothelium comprising the blood-brain and blood-retinal bar...

Journal ArticleDOI
TL;DR: Present knowledge is collated on the strategies employed by mycoplasmas while interacting with their host eukaryotic cells to demonstrate an impressive capability of maintaining a dynamic surface architecture that is antigenically and functionally versatile.
Abstract: The mycoplasmas form a large group of prokaryotic microorganisms with over 190 species distinguished from ordinary bacteria by their small size, minute genome, and total lack of a cell wall. Owing to their limited biosynthetic capabilities, most mycoplasmas are parasites exhibiting strict host and tissue specificities. The aim of this review is to collate present knowledge on the strategies employed by mycoplasmas while interacting with their host eukaryotic cells. Prominant among these strategies is the adherence of mycoplasma to host cells, identifying the mycoplasmal adhesins as well as the mammalian membrane receptors; the invasion of mycoplasmas into host cells including studies on the role of mycoplasmal surface molecules and signaling mechanisms in the invasion; the fusion of mycoplasmas with host cells, a novel process that raises intriguing questions of how microinjection of mycoplasma components into eukaryotic cells subvert and damage the host cells. The observations of diverse interactions of mycoplasmas with cells of the immune system and their immunomodulatory effects and the discovery of genetic systems that enable mycoplasmas to rapidly change their surface antigenic composition have been important developments in mycoplasma research over the past decade, showing that mycoplasmas possess an impressive capability of maintaining a dynamic surface architecture that is antigenically and functionally versatile, contributing to the capability of the mycoplasmas to adapt to a large range of habitats and cause diseases that are often chronic in nature.

Journal ArticleDOI
TL;DR: Compelling evidence exists for unique cascades of biophysical, adhesive, stimulatory, and guidance factors that arrest neutrophils in theAlveolar capillary bed and direct their movement through the endothelium, interstitial space, and alveolar epithelium.
Abstract: Neutrophil emigration in the lung differs substantially from that in systemic vascular beds where extravasation occurs primarily through postcapillary venules. Migration into the alveolus occurs directly from alveolar capillaries and appears to progress through a sequence of steps uniquely influenced by the cellular anatomy and organization of the alveolar wall. The cascade of adhesive and stimulatory events so critical to the extravasation of neutrophils from postcapillary venules in many tissues is not evident in this setting. Compelling evidence exists for unique cascades of biophysical, adhesive, stimulatory, and guidance factors that arrest neutrophils in the alveolar capillary bed and direct their movement through the endothelium, interstitial space, and alveolar epithelium. A prominent path accessible to the neutrophil appears to be determined by the structural interactions of endothelial cells, interstitial fibroblasts, as well as type I and type II alveolar epithelial cells.

Journal ArticleDOI
TL;DR: A coherent framework that accounts for a large body of experimental data at the ion-channel, single-cell, and network levels is suggested and physiological roles for the highly synchronized oscillations of slow-wave sleep are suggested.
Abstract: Neurons of the central nervous system display a broad spectrum of intrinsic electrophysiological properties that are absent in the traditional "integrate-and-fire" model A network of neurons with these properties interacting through synaptic receptors with many time scales can produce complex patterns of activity that cannot be intuitively predicted Computational methods, tightly linked to experimental data, provide insights into the dynamics of neural networks We review this approach for the case of bursting neurons of the thalamus, with a focus on thalamic and thalamocortical slow-wave oscillations At the single-cell level, intrinsic bursting or oscillations can be explained by interactions between calcium- and voltage-dependent channels At the network level, the genesis of oscillations, their initiation, propagation, termination, and large-scale synchrony can be explained by interactions between neurons with a variety of intrinsic cellular properties through different types of synaptic receptors These interactions can be altered by neuromodulators, which can dramatically shift the large-scale behavior of the network, and can also be disrupted in many ways, resulting in pathological patterns of activity, such as seizures We suggest a coherent framework that accounts for a large body of experimental data at the ion-channel, single-cell, and network levels This framework suggests physiological roles for the highly synchronized oscillations of slow-wave sleep

Journal ArticleDOI
TL;DR: Focusing on the roles RPTPs play in the development of the central nervous system, this review discusses how the elucidation of RPTP crystal structures, the biochemical analysis of phosphatase enzyme catalysis, and the characterization of complex signal transduction cascades downstream of RP TPs have generated testable models ofRPTP structure and function.
Abstract: Receptor protein tyrosine phosphatases (RPTPs) are key regulators of neuronal morphogenesis in a variety of different vertebrate and invertebrate systems, yet the mechanisms by which these proteins regulate central nervous system development are poorly understood. In the past few years, studies have begun to outline possible models for RPTP function by demonstrating in vivo roles for RPTPs in axon outgrowth, guidance, and synaptogenesis. In addition, the crystal structures of several RPTPs have been solved, numerous downstream effectors of RPTP signaling have been identified, and a small number of RPTP ligands have been described. In this review, we focus on how RPTPs transduce signals from the extracellular environment to the cytoplasm, using a detailed comparative analysis of the different RPTP subfamilies. Focusing on the roles RPTPs play in the development of the central nervous system, we discuss how the elucidation of RPTP crystal structures, the biochemical analysis of phosphatase enzyme catalysis, and the characterization of complex signal transduction cascades downstream of RPTPs have generated testable models of RPTP structure and function.

Journal ArticleDOI
TL;DR: Roles for epithelial cells and epithelial integrins in lung development and in the regulation of lung inflammation, macrophage protease expression, pulmonary fibrosis, and the pulmonary edema that follows acute lung injury are identified.
Abstract: Sheppard, Dean. Functions of Pulmonary Epithelial Integrins: From Development to Disease. Physiol Rev 83: 673–686, 2003; 10.1152/physrev.00033.2002.—Signals from integrins are now known to play cri...

Journal ArticleDOI
TL;DR: This work has defined integrative physiology as the study of how gene products integrate into the function of whole tissues and intact organisms, and illustrates this approach with an epithelial model system, the Malpighian (renal) tubule of Drosophila melanogaster.
Abstract: Dow, Julian A. T, and Shireen A. Davies. Integrative Physiology and Functional Genomics of Epithelial Function in a Genetic Model Organism. Physiol Rev 83: 687–729, 2003; 10.1152/physrev.00035.2002...