bluuebunny/crossref_metadata_2025 huggingface dataset:
EMG Responses to Maintain Stance During Multidirectional Surface Translations
Authors: Henry Sharon M. , Fung Joyce , Horak Fay B.
Published: December 2017

Henry, Sharon M., Joyce Fung, and Fay B. Horak. EMG responses to maintain stance during multidirectional surface translations. J. Neurophysiol. 80: 1939–1950, 1998. To characterize muscle synergy organization underlying multidirectional control of stance posture, electromyographic activity was recorded from 11 lower limb and trunk muscles of 7 healthy subjects while they were subjected to horizontal surface translations in 12 different, randomly presented directions. The latency and amplitude of muscle responses were quantified for each perturbation direction. Tuning curves for each muscle were examined to relate the amplitude of the muscle response to the direction of surface translation. The latencies of responses for the shank and thigh muscles were constant, regardless of perturbation direction. In contrast, the latencies for another thigh [tensor fascia latae (TFL)] and two trunk muscles [rectus abdominis (RAB) and erector spinae (ESP)] were either early or late, depending on the perturbation direction. These three muscles with direction-specific latencies may play different roles in postural control as prime movers or as stabilizers for different translation directions, depending on the timing of recruitment. Most muscle tuning curves were within one quadrant, having one direction of maximal activity, generally in response to diagonal surface translations. Two trunk muscles (RAB and ESP) and two lower limb muscles (semimembranosus and peroneus longus) had bipolar tuning curves, with two different directions of maximal activity, suggesting that these muscle can play different roles as part of different synergies, depending on translation direction. Muscle tuning curves tended to group into one of three regions in response to 12 different directions of perturbations. Two muscles [rectus femoris (RFM) and TFL] were maximally active in response to lateral surface translations. The remaining muscles clustered into one of two diagonal regions. The diagonal regions corresponded to the two primary directions of active horizontal force vector responses. Two muscles (RFM and adductor longus) were maximally active orthogonal to their predicted direction of maximal activity based on anatomic orientation. Some of the muscles in each of the synergic regions were not anatomic synergists, suggesting a complex central organization for recruitment of muscles. The results suggest that neither a simple reflex mechanism nor a fixed muscle synergy organization is adequate to explain the muscle activation patterns observed in this postural control task. Our results are consistent with a centrally mediated pattern of muscle latencies combined with peripheral influence on muscle magnitude. We suggest that a flexible continuum of muscle synergies that are modifiable in a task-dependent manner be used for equilibrium control in stance.
Painful Stimuli Evoke Potentials Recorded From the Parasylvian Cortex in Humans
Authors: Lenz F. A. , Rios M. , Chau D. , Krauss G. L. , Zirh T. A. , Lesser R. P.
Published: December 2017

Lenz, F. A., M. Rios, D. Chau, G. L. Krauss, T. A. Zirh, and R. P. Lesser. Painful stimuli evoke potentials recorded from the parasylvian cortex in humans. J. Neurophysiol. 80: 2077–2088, 1998. Cutaneous stimulation of the face and hand with a CO2 laser in three awake patients evoked potentials (LEPs) recorded from the dominant left parasylvian cortex. These were recorded by means of a subdural grid of electrodes implanted for evaluation of epilepsy. Stimulation of the contralateral face resulted in waveforms consisting of a negative potential (N2, 162 ± 5 ms; mean ± SE) followed by a positive potential (P2, 340 ± 18 ms). Both waves occurred at longer latency after hand than after facial stimulation. N2 and P2 potentials recorded from the grid correspond well in morphology to those recorded from the scalp in four additional patients tested with the same stimulation paradigm. The N2 waves recorded from the subdural grid occurred at significantly shorter latencies than did those recorded from the scalp (184 ± 6 ms), but the P2 waves at the grid occurred at significantly longer latencies than did those recorded at the scalp (281 ± 13 ms). The amplitudes of the potentials recorded from the grid were maximal over the parietal operculum both for contralateral stimulation of the face or hand and for ipsilateral stimulation of the face. Potentials also were recorded in this area after stimulation of the ipsilateral hand. The cortical distributions of these potentials suggest that their generators are located in the parietal operculum or in the insula, or in both, consistent with previous PET, magnetoencephalographic, and scalp LEP source analyses. These previous analyses provide indirect evidence of nociceptive input to parasylvian cortex because the interpretation of each analysis incorporates multiple assumptions. The present results are the first direct evidence of nociceptive input to the human parasylvian cortex.
Who Discovered Insulin?
Authors: Bliss Michael
Published: December 2017

The discovery of insulin is commonly thought to be the result of a single brilliant idea of a young Canadian physician. The reality is far more complex, and careful historical research has revealed formidable scientific and human complications. Examination of relevant documents and laboratory notebooks has made it possible to reconstruct a complete history of the discovery, including the day-to-day experimental work with its progress and failures, and in the end to pinpoint the contributions that led to success. These events did not develop in peaceful harmony; there were incriminations and dramatic personality clashes.
Lithium Clearance: A New Research Area
Authors: Thomsen K , Schou M
Published: December 2017

It has been known for several decades that animal spermatozoa respond to substances associated with or produced by eggs and/or the female reproductive tract. Sperm motility and metabolism are affected, and, in addition, chemotaxis has been reported in various invertebrates and lower vertebrates. The mechanisms of communication begin to be understood, receptors on the sperm cell have been identified, and early biochemical events following receptor activation have been defined.
Why Milk?
Authors: Schmidt-Nielsen K
Published: December 2017

Most of us think of milk in terms of cow's milk, or perhaps of human milk, which is fairly similar. Some other mammals produce milk that is very different;some kinds may contain less than 1% protein, others more than 50% fat, and some virtually no carbohydrate. Why these vast differences?
Monosynaptic Transmission in the Spinal Cord
Authors: Redman SJ
Published: December 2017

The synaptic action of afferent fibers on motoneurons in the spinal cord is among the longest studied problems in the central nervous system but is still far from being fully understood. This article reports on the remarkable feat of recording from a single motoneuron activated by a single fiber, followed by labeling of both to identify unequivocally the relevant synapses.
Why Mammals Don't Regenerate—Or Do They?
Authors: Goss Richard J.
Published: December 2017

Even if warm-blooded animals could regenerate amputated legs, they would not be able to do so soon enough to avert starvation or capture. But this disadvantage for crippled mammals does not apply to appendages that are not vitally essential. Certain structures, such as deer antlers and the ears of rabbits, bats, and cats, are exceptions to the rule that mammals are not supposed to regenerate. How these structures do so may tell us why others do not.
Humans Can Acclimatize to Cold: A Lesson from Korean Women Divers
Authors: Hong Suk Ki , Rennie Donald W. , Park Yang Saeng
Published: December 2017

For over 2,000 years traditional Korean women divers have dived with little clothing, subjecting themselves daily to a severe cold stress that has caused alterations of several thermoregulatory functions. Since 1977 these divers have used wet suits that have eliminated the cold-water stress, and by 1982 their thermoregulatory functions had returned completely to control levels. This indicates that the traditional divers indeed developed cold acclimatization, a phenomenon that has been difficult to document in humans.
Changes in Brain Blood Flow and Oxidative Metabolism During Mental Activity
Authors: Roland PE
Published: December 2017

Until recently mental activity was regarded as too subtle to have any effect on energy metabolism of the brain. Recent measurements show that when subjects perform pure mental activity regional cerebral oxidative metabolism and regional cerebral blood flow (which are dynamically coupled) increase in several areas of the brain, including the cerebellum. Different types of mental activity cause such increases in different parts of the brain.
What Contributes to Freeze Tolerance?
Authors: Storey KB
Published: December 2017

Unique among vertebrates, some frogs withstand freezing of the whole body during overwintering. How can they tolerate complete stoppage of breathing, heartbeat, and blood flow when the animal freezes, to start again on thawing? They provide a fascinating view of life in a frozen state and offer a model system for possible medical use in organ cryopreservation.
Renal Function During Intrauterine Life
Authors: Lumbers ER
Published: December 2017

The fetal kidney is adapted to the intrauterine environment, particularly by providing relatively large volumes of dilute fluid to the amniotic compartment. There is an irregular pattern to the rate of maturation of tubular functions. Although the diluting ability of the fetal kidney is mature, its concentrating capacity is deficient, and tubular secretion is limited.
Scrambling Membrane Phospholipids and Local Control of Blood Clotting
Authors: Zwaal RFA
Published: December 2017

The membrane phospholipids of circulating blood platelets and red cells are asymmetrically arranged with virtually all phosphatidylserine on the inside. Stimulation of platelets by a variety of agents causes redistribution of the phospholipids with phosphatidylserine appearing on the outside. This contributes to a charged surface where local clotting reactions are greatly accelerated. Phospholipids breaking off from sickled red cells contribute similarly to intravascular clotting in the crisis phase of sickle cell disease.
Renal Reabsorption of Water. Are there Pores in Proximal Tubule Cells?
Authors: Whittembury G , Carpi-Medina P
Published: December 2017

Transcellular water movement occurs mainly through water channels where water molecules move in single file. These channels, which explain the large water permeability of the proximal tubule cells, are closed by mercurial sulfhydryl reagents. There are similarities between these channels and those of human red cells and those that appear in distal nephron segments and toad urinary bladder after antidiuretic hormone stimulation.
Molecular Absorption of Ultrasound in Biological Tissues
Authors: Kremkau FW
Published: December 2017

Attenuation of ultrasound in tissues is due primarily to macromolecular absorption. Biomacromolecules have higher absorptions than the constituent molecules of which they are made. Absorption dependencies on structure and solvation are probably interrelated. Underlying absorption processes are enhanced or new processes are added under conditions of high concentration, aggregation, or cross-linking.
Cell Membrane in Hypertension
Authors: Bohr DF
Published: December 2017

An increase in extracellular calcium concentration over a range of 0 to 5 mM causes membrane "stabilization". This stabilizing action of calcium is less effective in tissues from hypertensive animals, suggesting that less calcium is bound to the membrane of tissues from this source.
From Neuron to Mind
Authors: Bunge Mario
Published: December 2017

The main approaches to the study of mankind, and the corresponding models of man, are sketched and examined. The systemic model of man as a biopsychosocial entity is recommended. Likewise the multilevel approach is favored over the holistic, the analytic, and the synthetic approaches. Finally, the question of the reducibility of psychology to neurophysiology is discussed.
Multisensory Hypothalamic Neurons May Explain Interactions Among Regulatory Systems
Authors: Boulant JA , Silva NL
Published: December 2017

Homeostatic systems are controlled by hypothalamic neurons that sense endogenous factors, including temperature, osmolality, glucose, and reproductive hormones. The concept of "functional specificity" implies that each neuron senses only one factor, but in vitro studies show that a neuron can respond to multiple factors. This may explain many interactions observed between regulatory systems.
The Role of Early Signaling Events in the Mitogenic Response
Authors: Rozengurt E , Ober SS
Published: December 2017

Mitogenic agents such as polypeptide growth factors, regulatory peptides, hormones, and pharmacological agents produce a variety of early intracellular signaling events in quiescent fibroblast cell systems. The nature of these initial events is discussed in connection with the evidence for their synergistic roles in the cellular mitogenic response.
The Physiology of Heart-Lung Transplantation in Humans
Authors: Higenbottam T , Otulana BA , Wallwork J
Published: December 2017

Patients restored to a normal healthy life after heart-lung transplantation have grossly abnormal physiology. Review of recent pathophysiological observations in this group of patients has led to new ideas on the mechanism of bronchoconstriction and control of ventilation during exercise and question the role of vagal reflexes in regulation of breathing at rest.
Central Nervous System Integration of Pain Control and Autonomic Function
Authors: Lovick TA
Published: December 2017

Analgesia evoked by stimulation in the dorsal or ventrolateral part of the midbrain periaqueductal grey matter is accompanied by characteristic patterns of cardiovascular and motor change. These integrated responses may underlie some of the specific patterns of behavior that are evoked by different forms of stressful environmental stimuli.
Photochemical Damage to the Eye
Authors: van Norren D
Published: December 2017

From a simple model with two retinal photosensitizers, the shape of the threshold curve for light damage can be predicted. Because the action spectrum for light damage is also known, from this model the damage threshold can be calculated for an arbitrary light source.
Signaling Mechanisms in Erythropoiesis: New Insights
Authors: Porzig H
Published: December 2017

Erythropoietin is no longer considered the sole regulator of erythropoiesis. Many additional growth factors, mostly secreted by nonerythroid bone marrow cells, cooperate in stimulating growth and/or differentiation of erythroid precursor cells. In most cases their functional effects seem to be mediated by still-unknown second messenger signaling systems.
Perforated Patch Recordings in Physiology
Authors: Rae JL , Fernandez J
Published: December 2017

Perforated patch techniques allow measurement of cell voltages, currents, and capacitance without an electrode penetrating thy cytosol. Since intracellular messengers and regulators are not washed out, physiological processes run down slowly. In perforated outside-out vesicles, single-channel currents can be measured while their regulatory cascades remain intact.
Protein Kinase C: A Second E-C Coupling Pathway in Vascular Smooth Muscle?
Authors: Khalil RA , Morgan KG
Published: December 2017

Smooth muscle excitation-concentration (E-C) coupling cannot be easily explained by myosin phosphorylation-dephosphorylation alone. Protein kinase C (PKC) may function as a second signaling pathway. Experimental tools that modify PKC activity differ markedly in specificity and utility. Spatial distribution and possible physiological substrates of PKC are discussed.
The Ancient Origins and Causes of Ageing
Authors: Holliday Robin
Published: December 2017

The soma, or body, of animals is maintained for long periods by a variety of mechanisms. However, the evolved structure of the soma is not compatible with continued survival and ageing is due to failure of maintenance. The different lifespans of mammals may relate directly to their investment in maintenance.
Mobilization of Specific Neuropeptides by Peripheral Stimulation of Identified Frequencies
Authors: Han J-S , Wang Q
Published: December 2017

Three families of endogenous opioid peptides have been characterized in the CNS: enkephalins, endorphins and dynorphins. These can be mobilized by peripheral electrical stimulation. Stimulation at 2 Hz may accelerate the release of enkephalins and Beta-endorphin, whereas 100 Hz is most effective in releasing dynorphin.
Cholinergic Pontine Mechanisms Causing State-Dependent Respiratory Depression
Authors: Lydic R , Baghdoyan HA
Published: December 2017

Microinjecting cholinergic agonists into the pontine reticular formation causes a rapid-eye-movement (REM) sleeplike state. The ability to cause this state pharmacologically has encouraged causal hypothesis testing. This pharmacological model has shown that cholinergic pontine mechanism known to regulate REM sleep can also cause state-dependent respiratory depression.
Control of Turnover of Alveolar Surfactant
Authors: Nicholas TE
Published: December 2017

Surfactant is released from alveolar type II cells into a hypophase where it modifies surface tension and stabilizes alveoli. It is then taken back into the type II cell and reutilized. Although many secretagogues are suggested, the major release stimulus is probably distrotion of the type II cell.
Oscillations in Interacting Thalamic and Neocortical Neurons
Authors: Steriade M
Published: December 2017

Oscillations of brain electrical activity, constituting various rhythms of the electroencephalogram, emerge from synaptic activities in complex networks formed by interacting thalamic and neocortical neurons and are shaped by intrinsic properties of single cells.
A Role for K+ Channels in Cell Proliferation
Authors: Nilius B , Droogmans G
Published: December 2017

The expression of K+ channels modulates cell proliferation in a variety of tumor cells. Experimental evidence and three putative mechanisms of K+ channel action on cell Proliferation are discussed.
Neuropeptides in Sympathetic Nerves Affect Vagal Regulation of the Heart
Authors: Potter EK , Ulman LG
Published: December 2017

Until the last decade, autonomic neurotransmission at the heart has been described in terms of the classical transmitters acetylcholine and norepinephrine. Now modulation of this neurotransmission by neuropeptides colocalized with norepinephrine and acetylcholine sheds new light on an old story.
Resistance to Infection With Intracellular Parasites. Identification of a Candidate Gene
Authors: Vidal SM , Gros P
Published: December 2017

In the mouse, natural resistance to infection with unrelated intracellular parasites is controlled by the Bcg locus. With an positional cloning approach, a candidate gene for Bcg has been isolated. This gene encodes for a novel macrophage-specific transport protein, Nramp, which is altered in innately susceptible animals.
Spectral Analysis: A Tool for Study of Neonatal Sympathetic Systems
Authors: Gootman PM , Sica AL
Published: December 2017

Preference for statistical information from frequency domain rather than time domain analysis becomes apparent when applied to complex neural signals. Further, we demonstrate how power spectral methods reveal significant changes in neonatal sympathetic activity.
Calcium: A Trigger for Long-Term Depression and Potentiation in the Hippocampus
Authors: Debanne D , Thompson SM
Published: December 2017

Two opposing types of plasticity at excitatory synapses in the hippocampus, long-term potentiation and depression, require N-methyl-D-aspartate receptor activation and Ca2+ influx for their induction.The direction of the change in synaptic strength is determined by a balance between phosphorylation and dephosphorylation, as regulated by protein kinases and phosphatases that are activated selectively by different levels of intracellular Ca2+.
Adenosine Receptors in the Central Nervous System
Authors: Fredholm BB
Published: December 2017

Adenosine is present in the brain under physiological conditions and acts on G protein-coupled receptors. Adenosine regulates neurotransmitter release and neuronal firing rate, dopaminergic neurotransmission, glial cell function, and cerebral blood flow. Adenosine is implicated in sleep/wakefulness and protection against ischemic brain damage, epilepsy, and pain.
Sweet and Salty: Transduction in Taste
Authors: Lindemann B
Published: December 2017

Signal pathways in taste receptor cells reach from apical events, like binding of a tastant to a receptor, through intracellular processes and basolateral regenerative ion channel activity to the release of transmitter. The responses are now being investigated with patch clamping, monitoring of intracellular messengers including Ca2+, and molecular cloning.
Temperature and Proteins: Little Things Can Mean a Lot
Authors: Somero GN
Published: December 2017

Protein structures are highly sensitive to temperature because their net free energies of stabilization are low, about equal to energies associated with formation of a few noncovalent ("weak") bonds. Temperature-adaptive changes in protein stability and fucntion may result from minor changes in amino acid sequence at regions outside active sites and from accumulation of stabilizing solutes in the cell.
How Does the Fetus Cope With Thermal Challenges?
Authors: Laburn HP
Published: December 2017

The fetus produces much metabolic heat and loses it mainly via the placental circulation, across a fetomaternal temperature gradient of ~0.5�C. During maternal hyperthermia, the risk of noxious fetal hyperthermia is less than expected. The thermal protection appears to result from the fetus's own thermal inertia and consequences of maternal thermoregulatory strategies.
Role of Parvalbumin in Skeletal Muscle Relaxation
Authors: Rall JA
Published: December 2017

Parvalbumin, a soluble intracellular calcium buffer, is present in high concentrations in fast-contracting skeletal muscles across the animal kingdom. In frog skeletal muscle, pharmacological or low-temperature inhibition of the sarcoplasmic reticulum calcium pump reveals that parvalbumin sequesters calcium and promotes relaxation at a rate determined by magnesium dissociation from parvalbumin.
Mechanisms of Obesity-Induced Hypertension
Authors: Hall JE , Zappe DH , Alonso-Galicia M , Granger JP , Brands MW , Kassab SE
Published: December 2017

Obesity is a major cause of human essential hypertension. Recent studies point toward increased renal tubular reabsorption and abnormal renal pressure natriuresis in mediating obesity hypertension. The mechanisms for these renal changes appear to be multifactorial, including activation of the sympathetic nervous system and altered intrarenal histology, which compresses the renal medulla.
Intercellular Waves of Communication
Authors: Sanderson MJ
Published: December 2017

Intercellular Ca2+ waves may be propagated through multicellular systems by the diffusion, through gap junctions, of the second messenger inositol 1, 4, 5-trisphosphate (IP3). This intercellular IP3 signaling provides a mechanism by which cooperative cell activity may be coordinated.
Cardiovascular Effects of Endothelin
Authors: Grossman JD , Morgan JP
Published: December 2017

Endothelin is a potent vasoconstricting agent released by vascular endothelial cells. Endothelin affects multiple organ systems and occurs at high levels with heart disease. Changes in cellular calcium levels and Ca2+ sensitization of myofilaments mediate the endothelin pathway. The ability to modulate endothelin levels may lead to many effective therapies.
MAPK Cascades in Cell Growth and Death
Authors: Neary JT
Published: December 2017

Distinct signal transduction cascades comprised of at least three proteinkinases mediate cellular proliferation and differentiation, growth arrest, and programmed cell death. These cytosolic enzymes relay extracellular signals from cell surface to nucleus, leading to changes in gene expression. Signaling components of these cascades offer new possibilities for therapeutic strategies in tumorigenesis, inflammatory diseases, immunopotentiation, wound healing, and regeneration.
Structure and Function of Renal Organic Cation Transporters
Authors: Koepsell Hermann , Busch Andreas , Gorboulev Valentin , Arndt Petra
Published: December 2017

Polyspecific transport systems in the kidney mediate the excretion and reabsorption of organic cations. Electrogenic import systems and electroneutral export systems in the basolateral and luminal plasma membranes of proximal renal tubules are involved. Two subtypes of electrogenic import systems have been cloned from rats and humans and functionally characterized.
Transmission at Sympathetic Varicosities
Authors: Bennett Max R.
Published: December 2017

The development of techniques for recording the electrical signs of transmission at single sympathetic varicosities has revealed considerable heterogeneity in the properties of transmission at different varicosities. The origin of these heterogeneities is considered in this short review.
Calcium Channels Formed by Mammalian Trp Homologues
Authors: Zhu Xi , Birnbaumer Lutz
Published: December 2017

Homologues of Drosophila trp genes have been isolated from mammalian species in hope that they may constitute the molecular basis of capacitative Ca2+ entry. Expression of Trps suggests that they form Ca2+ influx channels regulated by either store depletion or a more upstream event. Store-operated Trp channels can be formed by heteromultimerization.
Information Networks in the Arterial Wall
Authors: Bény Jean-Louis
Published: December 2017

The main task of the arterial system is to secure an adequate supply of oxygen to organs. This fact implies the integration of multiple signals in the vascular wall. This review deals with the exchange of information between and among smooth muscle and endothelial cells through gap junctions in the vessel walls of arteries and arterioles.
An Integrated View of Insect Flight Muscle: Genes, Motor Molecules, and Motion
Authors: Maughan David W. , Vigoreaux Jim O.
Published: December 2017

Substituting an alanine for serine in the regulatory subunit of the motor protein myosin dramatically alters Drosophila's flight ability. Power output, at all levels of the flight system, is reduced. This example of deciphering a protein's function by producing malfunctions illustrates the broadening use of molecular genetics in integrative biology.
Advances in Parasympathetic Control of Heart Rate and Cardiac Function
Authors: Mendelowitz David
Published: December 2017

It is well known that the neuronal projections from the brain to the heart strongly influence cardiac function, and an abnormal activity has been implicated in diseases such as cardiac arrhythmia and sudden infant death syndrome. This short review describes recent advances focused on the neurobiology of cardiac vagal neurons, utilizing cellular techniques.
Archival Collections in Physiology
Authors: West John B.
Published: December 2017

Archival collections are important in preserving our historical heritage. An example of a new archival collection in high-altitude physiology and medicine is described. Physiologists should be more aware of the historical value of primary material and should be encouraged to offer their papers to an appropriate archival repository.
The Discovery of Renin 100 Years Ago
Authors: Phillips M. Ian , Schmidt-Ott K. M.
Published: December 2017

In 1898, Tigerstedt and Bergman published their observation that kidney extracts produce pressor effects. They characterized the substance and named it “renin.” Although this was the beginning of understanding the role of the kidney in hypertension and the renin-angiotensin system, their discovery lay dormant for nearly 40 years.
Measurement and Interpretation of Cytoplasmic [Ca2+] Signals From Calcium-Indicator Dyes
Authors: Baylor Stephen M. , Hollingworth Stephen
Published: December 2017

Ca2+-indicator dyes are widely used in biology yet difficult to characterize inside cells. Studies in skeletal muscle fibers provide important information about indicator behavior and about Ca2+ signaling within the cytoplasm.
Is the GI System Built For Exercise?
Authors: Gisolfi Carl V.
Published: December 2017

The gut usually meets the fluid, electrolyte, and nutrient requirements of mild to heavy exercise. Gastric emptying and intestinal absorption rates of beverages ingested during exercise equal sweat rates. However, strenuous or prolonged exercise under dehydrated conditions can produce gastrointestinal distress and tissue damage.
Isoform-Specific Regulation of the Na+-K+ Pump in Heart
Authors: Mathias R. T. , Cohen I. S. , Gao J. , Wang Y.
Published: December 2017

Guinea pig ventricular myocytes coexpress two isoforms of the Na+-K+ pump. These two isoforms respond differently to the physical environment and are coupled to autonomic input through different signal transduction cascades. The expression of different isoforms provides each cell type with a mechanism of programming specific responses to environmental changes.
Neuroprotection and Angiogenesis: Dual Role of Erythropoietin in Brain Ischemia
Authors: Marti Hugo H. , Bernaudin Myriam , Petit Edwige , Bauer Christian
Published: December 2017

Erythropoietin, originally defined as an erythroid growth factor, is upregulated in the brain under conditions of hypoxia. So far, two functions have been identified for this locally produced cytokine: a direct protective effect on neuronal cells during cerebral ischemia and an indirect protection of brain tissue that could be provided by promoting brain vessel growth.
Brain Glucose Transporters: Relationship to Local Energy Demand
Authors: Duelli Roman , Kuschinsky Wolfgang
Published: December 2017

Glucose, the major fuel in the brain, is transported across the cell membranes by facilitated diffusion mediated by glucose transporter proteins. Essentially two types of glucose transporters are localized in the membranes of brain endothelial cells, astrocytes, and neurons. Their densities are well adjusted to changes in local energy demand.
Small is Mighty: EmrE, a Multidrug Transporter as an Experimental Paradigm
Authors: Schuldiner Shimon , Granot Dorit , Mordoch Sonia Steiner , Ninio Shira , Rotem Dvir , Soskin Michael , Tate Christopher G. , Yerushalmi Hagit
Published: December 2017

EmrE is a multidrug transporter from Escherichia coli that functions as a homooligomer and is unique in its small size. In each monomer there are four tightly packed transmembrane segments and one membrane-embedded charged residue. This residue provides the basis for the coupling mechanism as part of a binding site “time shared” by substrates and protons.
ClC Chloride Channels in Epithelia: Recent Progress and Remaining Puzzles
Authors: Wills N. K. , Fong P.
Published: December 2017

ClC chloride channels are widely expressed in epithelia. Recent insights into the roles of specific ClC channels have emerged from molecular and immunolocalization studies, mouse knockout models, and the linkage of mutations of these channels to the human hereditary diseases Bartter's syndrome and Dent's disease.
Sex and Salt Hormones: Rapid Effects in Epithelia
Authors: Harvey Brian J. , Condliffe Steven , Doolan Christina M.
Published: December 2017

Recent evidence points to protein kinase C isoforms as highly specific receptors for aldosterone and estradiol in epithelia. The end targets of the kinase activation are Na+/H+exchange and K+and Ca2+channels. The physiological role of the nongenomic response is to increase electrolyte absorption and inhibit secretion in pluripotential epithelia.
Preeclampsia: Linking Placental Ischemia with Cardiovascular-Renal Dysfunction
Authors: Alexander Barbara T. , Bennett William A. , Khalil Raouf A. , Granger Joey P.
Published: December 2017

Placental ischemia during preeclampsia is thought to lead to widespread activation/dysfunction of the maternal vascular endothelium. This results in enhanced formation of endothelin and thromboxane and decreased formation of nitric oxide and prostacyclin. These endothelial abnormalities, in turn, cause hypertension by impairing renal pressure natriuresis and increasing total peripheral resistance.
pH Homeostasis of Cellular Organelles
Authors: Demaurex Nicolas
Published: December 2017

An optimal pH is maintained in each secretory and endocytic organelle by the balance between active H+ pumping and passive H+ efflux. The progressive acidification of secretory organelles does not reflect an increased proton pumping activity but rather the decreased conduction of a “proton leak” pathway resembling the recently cloned voltage-gated proton channels.
Understanding Key Mechanisms of Exercise-Induced Cardiac Protection to Mitigate Disease: Current Knowledge and Emerging Concepts
Authors: Bernardo Bianca C. , Ooi Jenny Y. Y. , Weeks Kate L. , Patterson Natalie L. , McMullen Julie R.
Published: December 2017

The benefits of exercise on the heart are well recognized, and clinical studies have demonstrated that exercise is an intervention that can improve cardiac function in heart failure patients. This has led to significant research into understanding the key mechanisms responsible for exercise-induced cardiac protection. Here, we summarize molecular mechanisms that regulate exercise-induced cardiac myocyte growth and proliferation. We discuss in detail the effects of exercise on other cardiac cells, organelles, and systems that have received less or little attention and require further investigation. This includes cardiac excitation and contraction, mitochondrial adaptations, cellular stress responses to promote survival (heat shock response, ubiquitin-proteasome system, autophagy-lysosomal system, endoplasmic reticulum unfolded protein response, DNA damage response), extracellular matrix, inflammatory response, and organ-to-organ crosstalk. We summarize therapeutic strategies targeting known regulators of exercise-induced protection and the challenges translating findings from bench to bedside. We conclude that technological advancements that allow for in-depth profiling of the genome, transcriptome, proteome and metabolome, combined with animal and human studies, provide new opportunities for comprehensively defining the signaling and regulatory aspects of cell/organelle functions that underpin the protective properties of exercise. This is likely to lead to the identification of novel biomarkers and therapeutic targets for heart disease.
Electrophysiology of mammalian gland cells
Authors: Petersen O. H.
Published: December 2017

The resting cell membrane potential varies from -40 to -70 mV according to type of gland cell and species. The RP depends mainly on the large transmembrane concentration gradient for K maintained by a pump mechanism extruding Na and accumulating K. Since the Na permeability (PNa) is much smaller than PK, the Na concentration gradient is less important. In addition to the dominant electrodiffusional control of RP the Na pump itself contributes since the active transport of Na (out) exceeds that of the active K uptake. Gland cells are generally electrically coupled--i.e., the junctional membrane resistance is much lower than the surface membrane resistance. The coupling may be widespread (e.g., liver) or confined to one acinus (e.g., salivary gland and pancreas). The specific surface cell membrane resistance may be about 2000 omega cm2. A number of neurotransmitters and hormones control cellular transport processes by their action on surface cell membrane receptors. Agonist-receptor interaction causes prominent changes in membrane potential and resistance, in many cases of a complex nature. Most gland cell membranes so far investigated in detail appear to be electrically inexcitable; i.e., stimulation does not cause the appearance of action potentials (e.g., salivary glands, exocrine pancreas, and liver) but prominent exceptions to this are the endocrine pancreas (beta-cells) and the adrenal cortex. The main importance of agonist-induced membrane permeability changes is to alter the intracellular ion activities. An increase in [Na+] seems to be important whenever stimulation results in fluid transport and an increase in [Ca2+] triggers exocytosis.
Functional adaptation to reduction in renal mass
Authors: Hayslett J. P.
Published: December 2017

As the population of nephrons diminishes, while the dietary intake and/or endogenous production of water and solutes is unchanged, there is a proportional increase in the excretion of water and solute by individual residual nephrons. This adaptive change, which preserves zero net balance in the early phase of renal insufficiency, involves a reduction in the fractional reabsorption of substances derived from the initial glomerular ultrafiltrate and an increase in the rate of secretion of solutes that are extracted by tubular epithelial cells from peritubular blood. These compensatory changes are adequate to maintain electrolyte and water homeostasis until severe renal failure ensures (GFR less than 20% of normal). After a moderate reduction in nephron population there is no evidence that the factors that modulate ion transport are qualitatively different from those that regulate renal function in the intact subject, when the excretory load of solute is varied by changes in intake or endogenous production. In severe renal insufficiency, however, it seems likely that several factors, not present in the subject with intact renal function, also play an important role in modifying the excretion of water and electrolytes. For example, an osmotic diuresis in severe renal failure apparently decreases the tubular reabsorption of sodium and divalent cations and that of water. Moreover, elaboration of a partially identified "natriuretic" substance may participate in the regulation of electrolyte excretion in severe renal insufficiency. The appearance of these factors in severe renal insufficiency probably complements mechanisms that normally regulate the transfer of water and ions across tubular epithelium, since even after a marked reduction in GFR the urinary excretion of solutes and water changes proportionally with intake, although within narrower limits than exist in normal subjects. Studies in experimental animals and in man with acquired renal disease demonstrate the important role of other factors in compensatory adaptation, in addition to changes in tubular transport. The marked increases in glomerular filtration rate and nephron blood flow, which occur at least in some conditions, increase the absolute amount of water and solute delivered to the various nephron segments in ultrafiltrate and peritubular blood. Moreover, the expansion of extracellular fluid in severe renal failure inhibits tubular reabsorption of filtered water and solute in the same qualitative way that has been demonstrated in subjects with intact renal function. Quantitatively the response to acute volume expansion is exaggerated compared with control. Concomitant changes in renal hypertrophy and hyperplasia probably play an important role in functional adaptation. The apparent marked capacity for compensatory growth in all nephron segments and even in portions of tubular segments in parenchymal renal disease increases the area for transport by tubular epithelia in residual nephrons, as the overall number of nephrons diminishes...
Effects on thermal stress and exercise on blood volume in humans
Authors: Harrison M. H.
Published: December 2017

The opening remarks of this review emphasize, somewhat pessimistically, the serious disagreements, going back over a hundred years, between different investigators regarding effects of exercise and thermal stress on intravascular volume. However, the concluding remarks may legitimately assume a more optimistic, positive aspect, and a certain degree of order and sense may be brought to what had superficially appeared to be the chaos and confusion of conflicting observations and conclusions. Krebs and Meyer's (162) "marked differences in findings between one investigator and another," and Senay's (245) comment 77 years later that "disagreements abound" can now be seen as an inevitable consequence of the widely differing experimental protocols and procedures that have been adopted. Of particular importance in this respect is the failure to standardize conditions before subjects are exposed to thermal stress or begin to exercise--notably in terms of posture and environmental temperature; both may profoundly influence blood volume responses, quantitatively and qualitatively. Then there is subject status; physical fitness, heat acclimatization, and dehydration are important factors contributing to the variability of individual responses to thermal stress and exercise. With the causes of disagreement at least identified, it is now possible to answer the question posed in section I: Is thermal- and exercise-induced hemoconcentration fact or fantasy? Undeniably it is fact, but only under certain circumstances. For example, in resting subjects reduction in blood volume is associated only with high environmental temperatures above the upper limit of the prescriptive zone; within the upper part of the zone, blood volume commonly increases. If heat exposure is preceded by a control period in a cool environment, transient hemodilution is generally observed, followed by hemoconcentration after entry into the heat as skin temperature rises, cutaneous blood flow increases, and sweating begins. Exercise too causes hemoconcentration, but only if the exercise is performed in a supine or seated, not in an upright (standing), position. Hence cycling is almost always associated with a reduction in plasma volume, as is arm exercise and swimming. Bench stepping, walking, and running, on the other hand, are associated with an extremely variable intravascular volume response. If allowance is made for the reduction in plasma volume that occurs when moving to an upright position from a supine or seated position, the initial rapid hemoconcentration seen at the onset of cycling exercise is absent with bench stepping, walking, and running.(ABSTRACT TRUNCATED AT 400 WORDS)
Physiology of cold tolerance in insects
Authors: Zachariassen K. E.
Published: December 2017

From the available experimental data a relatively clear picture can be established with regard to the physiological importance of some of the mechanisms involved in insect cold hardening. In freeze-avoiding insects, all potent ice-nucleating agents are removed or inactivated, leading to a depression of the supercooling points to about 20 degrees C. Accumulation of polyols causes a further depression with a magnitude of about twice the corresponding melting-point depression. Production of thermal hysteresis factors causes a stabilization of the supercooled state. In freeze-tolerant insects, potent ice-nucleating agents are produced in the extracellular body fluid, ensuring a protective extracellular freezing at a few degrees below zero. Accumulation of polyols causes a steep drop in the lethal temperature, due to a reduction of the amount of ice by a colligative mechanism. However, there is still much to be learned about the mechanisms by which ice-nucleating agents, polyols, and thermal hysteresis agents are acting. Furthermore, the regulatory mechanisms involved in the production and elimination of these components from the body fluid of the insects are not understood. Also, when it comes to the influence of environmental factors, like photoperiod and temperature, there is much to be learned. In addition to giving attention to these topics, future research should be focused on the possible role of other factors in cold hardening such as bound water, dehydration, low-molecular-weight solutes other than polyols, and the biochemical mechanisms forming the basis of the seasonal changes in the cold hardiness of insects.
Biochemical effects of corticosteroids on neural tissues
Authors: Meyer J. S.
Published: December 2017

Corticosteroids appear capable of exerting an impressive array of effects on the metabolism of neural tissues. The diversity of these effects is perhaps not surprising given the wide variety of biochemically and morphologically distinguishable cell types present in the combined central and peripheral nervous systems. In conclusion, it seems useful to summarize the state of knowledge in some of the most critical research areas discussed in this review and to predict what major advances are probably forthcoming in the next few years.
Inhibin
Authors: De Jong F. H.
Published: December 2017

Inhibin has been defined as a gonadal hormone that exerts a specific negative feedback action on the secretion of FSH from the gonadotropic cells of the pituitary gland. The existence of inhibin was postulated as early as 1923 (250). However, only after reliable and sensitive bioassay systems for the detection and estimation of inhibin had been developed and an ample source of inhibin was found in the form of ovarian follicular fluid has progress been made in the isolation and characterization of the hormone. It is apparent now that inhibin, which itself consists of a dimer of two different subunits, alpha and beta, is a member of a much larger family of (glyco)protein hormones and growth factors, which also includes Mullerian-inhibiting substance, transforming growth factor-beta, erythroid differentiation factor, an insect protein that plays an important role in differentiation, and the dimer of two inhibin beta-subunits, activin. The latter substance was reported to counteract the effects of inhibin in pituitary cells. Interactions between these regulatory substances will certainly be a field of major interest in the near future. Inhibin molecules, similar to those in the gonads, have been detected in placental tissue as well. The postulate of inhibin in seminal plasma, prostate, and gastric juice is apparently due to detection of substances that differ from gonadal inhibin. Most likely these substances, the amino acid sequences of which have been elucidated, have a biological function that differs from the suppression of peripheral levels of FSH in vivo. Inhibin is produced in the Sertoli cells in the testis and in the granulosa cells in the ovary. The production of inhibin is stimulated by FSH, but presently a lot of controversy exists about other factors that might play a role in the regulation of the production of inhibin. Because of the lack of reliable methods for estimation of peripheral levels of inhibin in humans and experimental animals, almost all evidence for the physiological importance of inhibin in the regulation of reproductive processes is derived from circumstantial evidence. From these indirect results, it appears likely that inhibin plays an important role in the feedback regulation of peripheral concentrations of FSH during the period in which Sertoli cells and granulosa cells, the target cells for FSH, divide, i.e., during puberty in male animals and during the development of ovarian follicles in female animals.(ABSTRACT TRUNCATED AT 400 WORDS)