bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation imbalances in lumbar spine muscles in the presence of chronic low back pain
Authors: Oddsson Lars I. E. , De Luca Carlo J.
Published: March 2015

Paraspinal electromyographic (EMG) activity was recorded bilaterally from three lumbar levels during 30-s isometric trunk extensions [40 and 80% of maximum voluntary contraction (MVC)] in 20 healthy men and 14 chronic low back pain patients in pain. EMG parameters indicating neuromuscular fatigue and contralateral imbalances in EMG root-mean-square amplitude and median frequency were analyzed. Patients in pain showed less fatigue than controls at both contraction levels and produced only 55% of their MVC. Patients in pain likely did not produce a “true” maximum effort. A low MVC estimate would mean lower absolute contraction levels and less neuromuscular fatigue, thus explaining lower scores in the patients. Contralateral root-mean-square amplitude imbalances were present in both categories of subjects although such imbalances, when averaged across lumbar levels, were significantly larger in patients. Median frequency imbalances were significantly larger in the patients, at segmental as well as across lumbar levels. These results suggest that the presence of pain in these patients caused a redistribution of the activation behavior between synergistic muscles of the lumbar back.
Alterations in EEG activity and sleep after influenza viral infection in GHRH receptor-deficient mice
Authors: Alt Jeremy A. , Obal Ferenc , Traynor T. R. , Gardi Janos , Majde Jeannine A. , Krueger James M.
Published: March 2015

Viral infections induce excess non-rapid eye movement sleep (NREMS) in mice. Growth hormone-releasing hormone receptor (GHRH receptor) was previously identified as a candidate gene responsible for NREMS responses to influenza challenge in mice. The dwarf lit/lit mouse with a nonfunctional GHRH receptor was used to assess the role of the GHRH receptor in viral-induced NREMS. After influenza A virus infection the duration and intensity [electroencephalogram (EEG) delta power] of NREMS increased in heterozygous mice with the normal phenotype, whereas NREMS and EEG delta power decreased in homozygous lit/lit mice. Lit/lit mice developed a pathological state with EEG slow waves and enhanced muscle tone. Other influenza-induced responses (decreases in rapid eye movement sleep, changes in the EEG high-frequency bands during the various stages of vigilance, hypothermia, and decreased motor activity) did not differ between the heterozygous and lit/lit mice. GH replacement failed to normalize the NREMS responses in the lit/lit mice after influenza inoculation. Decreases in NREMS paralleled hypothermia in the lit/lit mice. Lung virus levels were similar in the two mouse strains. Lit/lit mice had a higher death rate after influenza challenge than the heterozygotes. In conclusion, GHRH signaling is involved in the NREMS response to influenza infection.
Involuntary leg movements affect interstitial nutrient gradients and blood flow in rat skeletal muscle
Authors: Holmäng Agneta , Mimura Kazuo , Lönnroth Peter
Published: March 2015

To evaluate the effect of passive muscle shortening and lengthening (PSL) on the transcapillary exchange of glucose, lactate, and insulin in the insulin-stimulated state, microdialysis was performed in rat quadriceps muscle. Electrical pulsatile stimulation (0.1 ms, 0.3–0.6 V, 1 Hz) was performed on the sciatic nerve in one leg to induce passive tension on the quadriceps during a hyperinsulinemic-euglycemic clamp (10 mU · kg−1 · min−1). In the non-insulin-stimulated (basal) state, the muscle arterial-interstitial (A-I) concentration difference of glucose was 1.6 ± 0.3 mM ( P < 0.01). During insulin infusion, it remained unaltered in resting muscle (1.3 ± 0.3 mM) but diminished during PSL. In the basal state there was no A-I concentration difference of lactate, whereas in the insulin infusion state it increased significantly and was significantly greater in moving (2.8 ± 0.5 mM, P < 0.01) than in resting muscle (0.7 ± 0.4 mM). The A-I concentration difference of insulin was equal in resting and moving muscle: 86 ± 7 and 100 ± 8 μU/ml, respectively. Muscle blood flow estimated by use of radiolabeled microspheres increased during PSL from 17 ± 4 to 34 ± 6 ml · 100 g−1 · min−1( P < 0.05). These results confirm that diffusion over the capillary wall is partly rate limiting for the exchange of insulin and glucose and lactate in resting muscle. PSL, in addition to insulin stimulation, increases blood flow and capillary permeability and, as a result, diminishes the A-I concentration gradient of glucose but not that of insulin or lactate.
Phosphatidylcholine metabolism of rat trachea in relation to lung parenchyma and surfactant
Authors: Rau Gunnar A. , Dombrowsky Heike , Gebert Andreas , Thole Hubert H. , von der Hardt Horst , Freihorst Joachim , Bernhard Wolfgang
Published: March 2015

Pulmonary surfactant prevents alveolar collapse and contributes to airway patency by reducing surface tension. Although alveolar surfactant, consisting mainly of phospholipids (PL) together with neutral lipids and surfactant-specific proteins, originates from type II pneumocytes, the contribution of airway epithelia to the PL fraction of conductive airway surfactant is still debated. We, therefore, analyzed the composition, synthesis, and release of phosphatidylcholine (PC) molecular species as the main surfactant PL of the rat trachea compared with the lung. Analyses of individual PC molecular species with HPLC and electrospray ionization mass spectrometry revealed that the rat trachea contained and synthesized much more palmitoyloleoyl-PC, palmitoyllinoleoyl-PC, and palmitoylarachidonoyl-PC, together with increased amounts of alkylacyl-PC, and less surfactant-specific species such as dipalmitoyl-PC than the lung. Organ cultures with [ methyl-3H]choline as precursor of PC revealed that, in the trachea, synthesized PC was retained in the tissue, rather than secreted. [ Methyl-3H]choline-labeled dipalmitoyl-PC was a negligible component in the trachea, and, in contrast to the lungs, palmitoyloleoyl-PC was enriched in tracheal secretions. We conclude that the surfactant fraction in the airways does not originate from the airways but is produced in the alveolar space and transported upward.
Invited Review: Effects of acute exercise and exercise training on insulin resistance
Authors: Henriksen Erik J.
Published: March 2015

Insulin resistance of skeletal muscle glucose transport is a key defect in the development of impaired glucose tolerance and Type 2 diabetes. It is well established that both an acute bout of exercise and chronic endurance exercise training can have beneficial effects on insulin action in insulin-resistant states. This review summarizes the present state of knowledge regarding these effects in the obese Zucker rat, a widely used rodent model of obesity-associated insulin resistance, and in insulin-resistant humans with impaired glucose tolerance or Type 2 diabetes. A single bout of prolonged aerobic exercise (30–60 min at ∼60–70% of maximal oxygen consumption) can significantly lower plasma glucose levels, owing to normal contraction-induced stimulation of GLUT-4 glucose transporter translocation and glucose transport activity in insulin-resistant skeletal muscle. However, little is currently known about the effects of acute exercise on muscle insulin signaling in the postexercise state in insulin-resistant individuals. A well-established adaptive response to exercise training in conditions of insulin resistance is improved glucose tolerance and enhanced skeletal muscle insulin sensitivity of glucose transport. This training-induced enhancement of insulin action is associated with upregulation of specific components of the glucose transport system in insulin-resistant muscle and includes increased protein expression of GLUT-4 and insulin receptor substrate-1. It is clear that further investigations are needed to further elucidate the specific molecular mechanisms underlying the beneficial effects of acute exercise and exercise training on the glucose transport system in insulin-resistant mammalian skeletal muscle.
Effects of exercise training on acclimatization to hypoxia: systemic O2 transport during maximal exercise
Authors: Favret Fabrice , Henderson Kyle K. , Richalet Jean-Paul , Gonzalez Norberto C.
Published: March 2015

Acclimatization to hypoxia has minimal effect on maximal O2 uptake (V̇o2 max). Prolonged hypoxia shows reductions in cardiac output (Q̇), maximal heart rate (HR-max), myocardial β-adrenoceptor (β-AR) density, and chronotropic response to isoproterenol. This study tested the hypothesis that exercise training (ET), which attenuates β-AR downregulation, would increase HRmax and Q̇ of acclimatization and result in higher V̇o2 max. After 3 wk of ET, rats lived at an inspired Po2 of 70 Torr for 10 days (acclimatized trained rats) or remained in normoxia, while both groups continued to train in normoxia. Controls were sedentary acclimatized and nonacclimatized rats. All rats exercised maximally in normoxia and hypoxia (inspired Po2 of 70 Torr). Myocardial β-AR density and the chronotropic response to isoproterenol were reduced, and myocardial cholinergic receptor density was increased after acclimatization; all of these receptor changes were reversed by ET. Normoxic V̇o2 max (in ml·min-1·kg-1) was 95.8 ± 1.0 in acclimatized trained ( n = 6), 87.7 ± 1.7 in nonacclimatized trained ( P < 0.05, n = 6), 74.2 ± 1.4 in acclimatized sedentary ( n = 6, P < 0.05), and 72.5 ± 1.2 in nonacclimatized sedentary ( n = 8; P > 0.05 acclimatized sedentary vs. nonacclimatized sedentary). A similar distribution of V̇o2 max values occurred in hypoxic exercise. Q̇ was highest in trained acclimatized and nonacclimatized, intermediate in nonacclimatized sedentary, and lowest in acclimatized sedentary groups. ET preserved Q̇ in acclimatized rats thanks to maintenance of HRmax as well as of maximal stroke volume. Q̇ preservation, coupled with a higher arterial O2 content, resulted in the acclimatized trained rats having the highest convective O2 transport and V̇o2 max. These results show that ET attenuates β-AR downregulation and preserves Q̇ and V̇o2 max after acclimatization, and support the idea that β-AR downregulation partially contributes to the limitation of V̇o2 max after acclimatization in rats.
Mechanism of expiratory muscle activation during lower thoracic spinal cord stimulation
Authors: DiMarco A. F. , Kowalski K. E. , Supinski G. , Romaniuk J. R.
Published: March 2015

Lower thoracic spinal cord stimulation (SCS) may be a useful method to restore an effective cough mechanism. In dogs, two groups of studies were performed to evaluate the mechanism of the expiratory muscle activation during stimulation at the T9-T10 level, which results in the greatest changes in airway pressure. In one group, expiratory muscle activation was monitored by evoked muscle compound action potentials (CAPs) from the internal intercostal muscles in the 10th, 11th, and 12th interspaces and from portions of the external oblique innervated by the L1 and L2 motor roots. SCS, applied with single shocks, resulted in short-latency CAPs at T10 but not at more caudal levels. SCS resulted in long-latency CAPs at each of the more caudal caudal recording sites. Bilateral dorsal column sectioning, just below the T11 spinal cord level, did not affect the short-latency CAPs but abolished the long-latency CAPs and also resulted in a fall in airway pressure generation. In the second group, sequential spinal root sectioning was performed to assess their individual mechanical contribution to pressure generation. Section of the ventral roots from T8 through T10 resulted in negligible changes, whereas section of more caudal roots resulted in a progressive reduction in pressure generation. We conclude that 1) SCS at the T9-T10 level results in direct activation of spinal cord roots within two to three segments of the stimulating electrode and activation of more distal roots via spinal cord pathways, and 2) pathway activation of motor roots makes a substantial contribution to pressure generation.
Scientific contributions of A. V. Hill: exercise physiology pioneer
Authors: Bassett David R.
Published: March 2015

Beginning in 1910, A. V. Hill performed careful experiments on the time course of heat production in isolated frog muscle. His research paralleled that of the German biochemist Otto Meyerhof, who measured the changes in muscle glycogen and lactate during contractions and recovery. For their work in discovering the distinction between aerobic and anaerobic metabolism, Hill and Meyerhof were jointly awarded the 1922 Nobel Prize for Physiology or Medicine. Because of Hill's interest in athletics, he sought to apply the concepts discovered in isolated frog muscle to the exercising human. Hill and his colleagues made measurements of O2 consumption on themselves and other subjects running around an 85-m grass track. In the process of this work, they defined the terms “maximum O2 intake,” “O2requirement,” and “steady state of exercise.” Other contributions of Hill include his discoveries of heat production in nerve, the series elastic component, and the force-velocity equation in muscle. Around the time of World War II, Hill was a leading figure in the Academic Assistance Council, which helped Jewish scientists fleeing Nazi Germany to relocate in the West. He served as a member of the British Parliament from 1940 to 1945 and as a scientific advisor to India. Hill's vision and enthusiasm attracted many scientists to the field of exercise physiology, and he pointed the way toward many of the physiological adaptations that occur with physical training.
Autonomic cardiovascular function in high-altitude Andean natives with chronic mountain sickness
Authors: Keyl C. , Schneider A. , Gamboa A. , Spicuzza L. , Casiraghi N. , Mori A. , Ramirez R. Tapia , León-Velarde F. , Bernardi L.
Published: March 2015

We evaluated autonomic cardiovascular regulation in subjects with polycythemia and chronic mountain sickness (CMS) and tested the hypothesis that an increase in arterial oxygen saturation has a beneficial effect on arterial baroreflex sensitivity in these subjects. Ten Andean natives with a Hct >65% and 10 natives with a Hct <60%, all living permanently at an altitude of 4,300 m, were included in the study. Cardiovascular autonomic regulation was evaluated by spectral analysis of hemodynamic parameters, while subjects breathed spontaneously or frequency controlled at 0.1 and 0.25 Hz, respectively. The recordings were repeated after a 1-h administration of supplemental oxygen and after frequency-controlled breathing at 6 breaths/min for 1 h, respectively. Subjects with Hct >65% showed an increased incidence of CMS compared with subjects with Hct <60%. Spontaneous baroreflex sensitivity was significantly lower in subjects with high Hct compared with the control group. The effects of supplemental oxygen or modification of the breathing pattern on autonomic function were as follows: 1) heart rate decreased significantly after both maneuvers in both groups, and 2) spontaneous baroreflex sensitivity increased significantly in subjects with high Hct and did not differ from subjects with low Hct. Temporary slow-frequency breathing may provide a beneficial effect on the autonomic cardiovascular function in high-altitude natives with CMS.
Invited Review: Regulation of skeletal muscle GLUT-4 expression by exercise
Authors: Dohm G. Lynis
Published: March 2015

The amount of GLUT-4 protein is a primary factor in determining the maximal rate of glucose transport into skeletal muscle. Therefore, it is important that we understand how exercise regulates GLUT-4 expression so that therapeutic strategies can be designed to increase muscle glucose disposal as a treatment for diabetes. Muscle contraction increases the rates of GLUT-4 transcription and translation. Transcriptional control likely requires at least two DNA binding proteins, myocyte enhancer factor-2 and GLUT-4 enhancer factor, which bind to the promoter. Increased GLUT-4 expression may be mediated by the enzyme AMP-activated kinase, which is activated during exercise and has been demonstrated to increase GLUT-4 transcription. Further research needs to be done to investigate whether AMP-activated kinase activates myocyte enhancer factor-2 and GLUT-4 enhancer factor to increase transcription of the GLUT-4 gene.
Transport of Xenobiotics Across the Blood-Brain Barrier
Authors: Hagenbuch Bruno , Gao Bo , Meier Peter. J.
Published: March 2015

Distinct transport proteins regulate the movement of waste products and xenobiotics across the blood-brain barrier (BBB). Members of the drug transporter families MDR, MRP, and OATP have been identified in the BBB, and a detailed characterization of the involved proteins is now required to target drugs more efficiently to the brain.
Dysfunction of Wild-Type Huntingtin in Huntington disease
Authors: Cattaneo Elena
Published: March 2015

Huntingtin is the protein involved in Huntington disease (HD), an inherited neurodegenerative disease. Research activities have focused on the abnormal functions of mutant huntingtin. However, recent results indicate that wild-type huntingtin has important activities in brain neurons, suggesting that loss of these activities may play a role in HD.
Is Survival Possible Without Arachidonate Metabolites in the Brain During Systemic Infection?
Authors: Zhang Ji , Rivest Serge
Published: March 2015

The central nervous system mediates a coordinated set of biological responses during systemic immune stimuli. These responses are essential for the organism to eliminate invading pathogens and restore health. Coincidentally, centrally produced prostaglandins play a determinant role in activating the neuronal circuits involved in the control of autonomic functions.
Angiogenesis and Vascular Remodeling by Intussusception: From Form to Function
Authors: Kurz Haymo , Burri Peter H. , Djonov Valentin G.
Published: March 2015

During most instances of angiogenesis, not only are the capillaries or terminal vessels generated and modified, but the supplying vascular system is subjected to remodeling as well. Intussusception, i.e., transluminal pillar formation, is one essential mechanism for growth, arborization, bifurcation remodeling, and pruning. Complex and efficient vascular beds can thus be generated by local interactions between vascular cells and hemodynamic conditions.
Alveolar Flooding at High Altitude: Failure of Reabsorption?
Authors: Höschele Sabine , Mairbäurl Heimo
Published: March 2015

Na-driven fluid reabsorption prevents alveolar fluid accumulation. Hypoxia augments fluid filtration by hemodynamic effects and inhibits Na reabsorption in cultured cells. A combination of both effects in vivo causes alveolar flooding, edema, thickening of the diffusion barrier for oxygen, and hypoxemia, a life-threatening situation for mountaineers in remote high-altitude mountain ranges.
Annexin 1: An Endogenous Anti-Inflammatory Protein
Authors: Perretti Mauro , Gavins Felicity N. E.
Published: March 2015

A hallmark of inflammation is the mobilization of blood-borne leukocytes across microvessels to kill and remove the invading pathogen. For its damaging potential, leukocyte movement is finely regulated, and endogenous pathways exist to ensure the time dependency of this process. Annexin 1 and its receptor(s) are one example of these pathways.
Functional Modulation of the Sodium Pump: The Regulatory Proteins “Fixit”
Authors: Cornelius Flemming , Mahmmoud Yasser A.
Published: March 2015

Proteins of the FXYD family act as tissue-specific regulators of the Na-K-ATPase. They are small hydrophobic type I proteins with a single-transmembrane span containing an extracellular invariant FXYD sequence. FXYD proteins are not an integral part of the Na-K-ATPase but function to modulate its catalytic properties by molecular interactions with specific Na-K-ATPase domains.
Neuropeptide Y: Neurotransmitter or Trophic Factor in the Heart?
Authors: Protas Lev , Qu Jihong , Robinson Richard B.
Published: March 2015

Neuropeptide Y (NPY) is released from sympathetic neurons and exerts short-term (acute) effects on prejunctional nerve terminals and postjunctional cardiac ion channels. However, NPY also exerts long-term (trophic) effects on angiogenesis, cardiac hypertrophy, autonomic signaling, and cardiac ion channels, including effects on L-type Ca2+ and pacemaker channels.
Tubuloglomerular Feedback and the Control of Glomerular Filtration Rate
Authors: Vallon Volker
Published: March 2015

In every nephron the glomerular filtration rate is adapted to changes in the salt concentration of early distal tubular fluid through the mechanism of tubuloglomerular feedback. Recent studies indicate that adenosine and possibly ATP mediate this mechanism and demonstrate its role in glomerular hemodynamic alterations in the early diabetic kidney.
Long-Term Adaptation Mechanisms in Extremity Veins Supporting Orthostatic Tolerance
Authors: Monos Emil , Lóránt Miklós , Dörnyei Gabriella , Bérczi Viktor , Nádasy György
Published: March 2015

Several long-term antigravity defense mechanisms are activated in the lower extremity veins and microvessels when an organism is exposed to chronic orthostatic load. These mechanisms involve acute pressure-induced myogenic response, counterregulatory K+channels, functional and structural remodeling of sympathetic innervation, and vascular network properties.
Language in the Right Cerebral Hemisphere: Contributions from Reading Studies
Authors: Taylor Kirsten I. , Regard Marianne
Published: March 2015

Evidence for a right hemispheric involvement in language processing, in particular at the level of word meaning, has emerged within the last half century. Hemispheric functional specializations are dynamic; right hemispheric language participation significantly increases under certain conditions, such as during an epileptic seizure and during recovery from stroke. Interhemispheric connections via the corpus callosum critically mediate these and other higher cortical functions.
Role of Calcium Sensitivity Modulation in Skeletal Muscle Performance
Authors: MacIntosh Brian R.
Published: March 2015

A common mechanism affecting Ca2+sensitivity in skeletal muscle is the proximity of myosin heads with actin filaments, a function of myofilament lattice spacing and myosin head mobility with respect to the myosin filament. This is an important mechanism of pCa2+50modulation by length, pH, regulatory light-chain phosphorylation, and temperature.
Transfer of theRf-1region from FHH onto the ACI background increases susceptibility to renal impairment
Authors: Provoost Abraham P. , Shiozawa Masahide , Van Dokkum Richard P. E. , Jacob Howard J.
Published: March 2015

The genetically hypertensive fawn-hooded (FHH/Eur) rat is characterized by the early presence of systolic and glomerular hypertension, progressive proteinuria (UPV), and albuminuria (UAV), and focal glomerulosclerosis, resulting in premature death from renal failure. Previous studies showed that at least five genetic loci ( Rf-1 to Rf-5) were linked to the development of renal impairment. Of these five, Rf-1 appears to play a major role. To study the impact of Rf-1 in the absence of the other loci, we transferred the Rf-1 region of chromosome 1, between the markers D1Mit34 and D1Rat156, Rf-1B for short, onto the genomic background of the normotensive August × Copenhagen Irish (ACI) rat. In this congenic strain, named ACI.FHH- D1Mit34/ Rat156 or ACI.FHH- Rf1B, we challenged the renal hemodynamic function of these animals by studying the effects of unilateral nephrectomy (UNX) alone, or combined with NG-nitro-l-arginine methyl ester (l-NAME)-induced hypertension. Following UNX, the congenic strain developed significantly more UPV and UAV than the ACI progenitor. The differences were even more pronounced when UNX was combined with an l-NAME-induced rise in systolic blood pressure to about 150 mmHg, i.e., the level of hypertension present in the parental FHH strain. These findings indicate that the Rf-1B region of the FHH rat contains at least one gene affecting the susceptibility to progressive renal failure, especially in the presence of an increase in blood pressure.
A compendium of gene expression in normal human tissues
Authors: HSIAO LI-LI , DANGOND FERNANDO , YOSHIDA TAKUMI , HONG ROBERT , JENSEN RODERICK V. , MISRA JATIN , DILLON WILLIAM , LEE KAILIN F. , CLARK KATHRYN E. , HAVERTY PETER , WENG ZHIPING , MUTTER GEORGE L. , FROSCH MATTHEW P. , MacDONALD MARCY E. , MILFORD EDGAR L. , CRUM CHRISTOPHER P. , BUENO RAPHAEL , PRATT RICHARD E. , MAHADEVAPPA MAMATHA , WARRINGTON JANET A. , STEPHANOPOULOS GREGORY , STEPHANOPOULOS GEORGE , GULLANS STEVEN R.
Published: March 2015

This study creates a compendium of gene expression in normal human tissues suitable as a reference for defining basic organ systems biology. Using oligonucleotide microarrays, we analyze 59 samples representing 19 distinct tissue types. Of ∼7,000 genes analyzed, 451 genes are expressed in all tissue types and designated as housekeeping genes. These genes display significant variation in expression levels among tissues and are sufficient for discerning tissue-specific expression signatures, indicative of fundamental differences in biochemical processes. In addition, subsets of tissue-selective genes are identified that define key biological processes characterizing each organ. This compendium highlights similarities and differences among organ systems and different individuals and also provides a publicly available resource (Human Gene Expression Index, the HuGE Index, http://www.hugeindex.org ) for future studies of pathophysiology.
Sex dependence and temporal dependence of the left ventricular genomic response to pressure overload
Authors: Weinberg Ellen O. , Mirotsou Maria , Gannon Joseph , Dzau Victor J. , Lee Richard T. , Pratt Richard E.
Published: March 2015

To characterize responses of the left ventricle (LV) to pressure overload at the genomic level, we performed high-density microarray analysis on individual mouse LVs. Male and female mice underwent transverse aortic constriction. At 1 day and 30 wk, the LV free wall was harvested and RNA isolated from 27 individual ventricles was analyzed on Mu74Av2 GeneChips, which contain ∼12,483 distinct genes. Interestingly, a greater number of genes was regulated in response to acute overload than in response to chronic overload. Hierarchical cluster analysis revealed the presence of several distinct expression profiles. Of these clusters, the majority contained genes that were regulated either in response to acute overload or both acute and chronic overload. In addition, clusters revealing sex-specific responses to overload were detected. In summary, the acute and chronic genomic responses to pressure overload are distinct. Moreover, sex modifies these responses. Furthermore, these studies have uncovered several novel and potentially important genes that are regulated in response to overload and may open unrecognized avenues for further functional analysis.
Analysis of the sheep genome
Authors: COCKETT N. E. , SHAY T. L. , SMIT M.
Published: March 2015

The identification of genes controlling several traits of interest in sheep has been accomplished by positional candidate cloning. In these studies, the trait is first mapped to a specific chromosomal region by linkage analysis, which requires families that are segregating for the trait and for polymorphic markers. Microsatellite markers are usually used for these analyses because of their extensive genetic variability. Once the location of a trait is determined by linkage to the markers, possible candidate genes controlling the trait can be inferred because of their proximity to linked markers. It is not necessary to map all possible genes in sheep for this strategy to be effective. Rather, a subset of genes that are mapped in humans and mice have also been mapped in sheep; these genes serve as “anchors” across the comparative maps of the different species. Further study of these positional candidates has revealed naturally occurring mutations that produce phenotypes that are unique to sheep. Thus the genetic analysis of sheep traits advances knowledge not only in this species but provides critical information for understanding biological pathways in mammalian species.
Individual variation of adipose gene expression and identification of covariated genes by cDNA microarrays
Authors: Boeuf Stéphane , Keijer Jaap , Franssen-Van Hal Nicole L. W. , Klaus Susanne
Published: March 2015

Gene expression profiling through the application of microarrays provides comprehensive assessment of gene expression levels in a given tissue or cell population, as well as information on changes of gene expression in altered physiological or pathological situations. Microarrays are particularly suited to study interactions in the regulation of large numbers of different genes, since their expression is analyzed simultaneously. For improved understanding of the physiology of adipose tissue, and consequently obesity and diabetes, identification of covariability in gene expression was attempted by analysis of the individual variability of gene expression in subcutaneous white and brown fat of the Siberian dwarf hamster using microarrays containing ∼300 cDNA fragments of adipose genes. No sex-dependant variability in gene expression could be found, and overall individual variability was rather low, with more than 80% of clones showing a coefficient of variation lower than 30%. Uncoupling protein 1 (UCP1) displayed a high variability of gene expression in brown fat, which was negatively correlated with the gene expression of complement factor B (FactB), implying a possible functional relationship.
Microarray comparison of normal andW/Wvmice in the gastric fundus indicates a supersensitive phenotype
Authors: Sergeant Gerard P. , Large Roddy J. , Beckett Elizabeth A. H. , McGeough Cathrine M. , Ward Sean M. , Horowitz Burton
Published: March 2015

Interstitial cells of Cajal (ICC) have been identified in specific areas throughout the smooth musculature of the gastrointestinal (GI) tract. Located within the circular and longitudinal muscle layers of the gastric fundus lies a specific type of ICC, termed “intramuscular” ICC or IC-IM. The principal function of this cell type is to act as “mediators of excitatory and inhibitory enteric neurotransmission.” The functional role of these cells has been investigated using W/ Wvmutant mice that specifically lack IC-IM, resulting in disrupted enteric neurotransmission. The aim of the present study was to investigate differential gene expression in W/ Wvmutant mice, from the tunica muscularis of the gastric fundus using a mouse cDNA microarray containing 1,081 known genes. Verification of the microarray data was attained using real-time “quantitative” PCR (qPCR). Of the 1,081 arrayed genes, 36 demonstrated differential expression by >2-fold in the W/ Wvmice. An agreement rate of 50% (7 of 14 tested) was obtained using qPCR. Of the seven confirmed changes in expression, several were indicative of a supersensitive phenotype, observed in denervation models. Expression of several putative neurotransmitter receptors including P2Y, the receptor for the inhibitory neurotransmitter ATP, was upregulated. The functional role of the P2Y receptor was also investigated using electrophysiological recordings. These results offer a new insight into the molecular changes that occur in W/ Wvfundic smooth muscle and may also provide novel information with regard to the importance of IC-IM in enteric neurotransmission.
Early onset albuminuria in Dahl rats is a polygenetic trait that is independent from salt loading
Authors: Poyan Mehr Ali , Siegel Anja-Kristin , Kossmehl Peter , Schulz Angela , Plehm Ralph , de Bruijn Jan A. , de Heer Emile , Kreutz Reinhold
Published: March 2015

The aim of the study was to characterize the genetic basis for the early onset of increased urinary albumin excretion (UAE) observed in the salt-sensitive Dahl rat (SS). We first characterized blood pressures and UAE values in adult SS compared with the spontaneously hypertensive rat (SHR) strain. Blood pressure measurements by radiotelemetry at 14 wk demonstrated similar spontaneous hypertension in both strains on a low-sodium diet containing 0.2% NaCl by weight, whereas UAE was markedly increased in SS compared with SHR (253.07 ± 68.39 vs. 1.65 ± 1.09 mg/24 h, P < 0.0001). Analysis of UAE in young animals of both strains fed a low-sodium diet demonstrated that UAE is elevated in SS as early as 4 wk of age ( P < 0.0001), when ultrastructural evaluation of glomeruli by electron microscopy appears still normal. At 8 wk SS demonstrated a 280-fold elevated UAE compared with SHR ( P < 0.0001). Consequently, to identify quantitative trait loci (QTLs) contributing to salt-independent early manifestation of increased UAE in the SS rat, we performed genome-wide linkage and QTL mapping analysis in a young F2population derived from the two contrasting strains. UAE was determined in 539 F2animals at 8 wk. We identified seven suggestive or significant UAE QTLs on rat chromosomes (RNO) RNO2, RNO6, RNO8, RNO9, RNO10, RNO11, and RNO19, accounting together for 34% of the overall variance of UAE in this F2population. Thus early onset albuminuria in the SS rat is under polygenetic influence and independent from salt loading.
Identification of temporal patterns of gene expression in the uteri of immature, ovariectomized mice following exposure to ethynylestradiol
Authors: Fertuck K. C. , Eckel J. E. , Gennings C. , Zacharewski T. R.
Published: March 2015

Estrogen induction of uterine wet weight provides an excellent model to investigate relationships between changes in global gene expression and well-characterized physiological responses. In this study, time course microarray GeneChip data were analyzed using a novel approach to identify temporal changes in uterine gene expression following treatment of immature ovariectomized C57BL/6 mice with 0.1 mg/kg 17α-ethynylestradiol. Functional gene annotation information from public databases facilitated the association of changes in gene expression with physiological outcomes, which allowed detailed mechanistic inferences to be drawn regarding cell cycle control and proliferation, transcription and translation, structural tissue remodeling, and immunologic responses. These systematic approaches confirm previously established responses, identify novel estrogen-regulated transcriptional effects, and disclose the coordinated activation of multiple modes of action that support the uterotrophic response elicited by estrogen. In particular, it was possible to elucidate the physiological significance of the dramatic induction of arginase, a classic estrogenic response, by elucidating its mechanistic relevance and delineating the role of arginine and ornithine utilization in the estrogen-stimulated induction of uterine wet weight.
Effects of creatine supplementation on housekeeping genes in human skeletal muscle using real-time RT-PCR
Authors: Murphy R. M. , Watt K. K. O. , Cameron-Smith D. , Gibbons C. J. , Snow R. J.
Published: March 2015

The present study examined the validity and reliability of measuring the expression of various genes in human skeletal muscle using quantitative real-time RT-PCR on a GeneAmp 5700 sequence detection system with SYBR Green 1 chemistry. In addition, the validity of using some of these genes as endogenous controls (i.e., housekeeping genes) when human skeletal muscle was exposed to elevated total creatine levels and exercise was also examined. For all except 28S, linear relationships between the logarithm of the starting RNA concentrations and the cycle threshold (CT) values were established for β-actin, β2-microglobulin (β2M), cyclophilin (CYC), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). We found a linear response between CT values and the logarithm of a given amount of starting cDNA for all the genes tested. The overall intra-assay coefficient of variance for these genes was 1.3% and 21% for raw CT values and the linear value of 2−CT, respectively. Interassay variability was 2.3% for raw CT values and 34% for the linear value of 2−CT. We also examined the expression of various housekeeping genes in human skeletal muscle at days 0, 1, and 5 following oral supplementation with either creatine or a placebo employing a double-blind crossover study design. Treatments were separated by a 5-wk washout period. Immediately following each muscle sampling, subjects performed two 30-s all-out bouts on a cycle ergometer. Creatine supplementation increased ( P < 0.05) muscle total creatine content above placebo levels; however, there were no changes ( P > 0.05) in CT values across the supplementation periods for any of the genes. Nevertheless, 95% confidence intervals showed that GAPDH was variable, whereas β-actin, β2M, and CYC were the least varying genes. Normalization of the data to these housekeeping genes revealed variable behavior for β2M with more stable expressions for both β-actin and CYC. We conclude that, using real-time RT-PCR, β-actin or CYC may be used as housekeeping genes to study gene expression in human muscle in experiments employing short-term creatine supplementation combined with high-intensity exercise.
Evolutionary relationships of the Tas2r receptor gene families in mouse and human
Authors: Conte Caroline , Ebeling Martin , Marcuz Anne , Nef Patrick , Andres-Barquin Pedro J.
Published: March 2015

The early molecular events in the perception of bitter taste start with the binding of specific water-soluble molecules to G protein-coupled receptors (GPCRs) encoded by the Tas2r family of taste receptor genes. The identification of the complete TAS2R receptor family repertoire in mouse and a comparative study of the Tas2r gene families in mouse and human might help to better understand bitter taste perception. We have identified, cloned, and characterized 13 new mouse Tas2r sequences, 9 of which encode putative functional bitter taste receptors. The encoded proteins are between 293 and 333 amino acids long and share between 18% and 54% sequence identity with other mouse TAS2R proteins. Including the 13 sequences identified, the mouse Tas2r family contains ∼30% more genes and 60% fewer pseudogenes than the human TAS2R family. Sequence and phylogenetic analyses of the proteins encoded by all mouse and human Tas2r genes indicate that TAS2R proteins present a lower degree of sequence conservation in mouse than in human and suggest a classification in five groups that may reflect a specialization in their functional activity to detect bitter compounds. Tas2r genes are organized in clusters in both mouse and human genomes, and an analysis of these clusters and phylogenetic analyses indicates that the five TAS2R protein groups were present prior to the divergence of the primate and rodent lineages. However, differences in subsequent evolutionary processes, including local duplications, interchromosomal duplications, divergence, and deletions, gave rise to species-specific sequences and shaped the diversity of the current TAS2R receptor families during mouse and human evolution.
Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization
Authors: BRAR ANOOP K. , HANDWERGER STUART , KESSLER CHERIE A. , ARONOW BRUCE J.
Published: March 2015

Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization. Physiol Genomics 7: 135–148, 2001. First published September 21, 2001; 10.1152/physiolgenomics.00061.2001.—Human decidual fibroblasts undergo a differentiative commitment to the acquisition of endocrine, metabolic, and structural cell functions in a process known as decidualization. Decidualization is critical for embryo implantation and placental function. We characterized gene expression pattern kinetics during decidual fibroblast differentiation by microarray analysis. Of 6,918 genes analyzed, 121 genes were induced by more than twofold, 110 were downregulated, and 50 showed biphasic behavior. Dynamically regulated genes were could be fit into nine K-means algorithm-based kinetic pattern groups, and by biologic classification, into five categories: cell and tissue function, cell and tissue structure, regulation of gene expression, expressed sequence tag (EST), and “function unknown.” Reprogramming of genes within specific functional groups and gene families was a prominent feature that consisted of simultaneous induction and downregulation of a set of genes with related function. We previously observed a conceptually similar process during fetal trophoblast differentiation, in which the same phenomena applied to different genes. Of the 569 dynamically regulated genes regulated by either model, only 81 of these were in common. These results suggest that reprogramming of gene expression within focused functional categories represents a fundamental aspect of cellular differentiation.
Array analysis of gene expression in connexin-43 null astrocytes
Authors: Iacobas Dumitru A. , Urban-Maldonado Marcia , Iacobas Sanda , Scemes Eliana , Spray David C.
Published: March 2015

Connexin-43 (Cx43) is the most abundant gap junction protein in brain, where it is found primarily between astrocytes. Although the morphology of astrocytes from Cx43-null (knockout, KO) mice is similar to that of wild-type (WT) astrocytes, KO astrocytes exhibit reduced growth rate in culture. To evaluate the impact of deletion of Cx43 on other genes, including those encoding cell cycle proteins, we used DNA arrays to determine expression patterns in cultured astrocytes from sibling Cx43-null and WT mice. RNA samples extracted from astrocytes cultured from WT and Cx43-null neonatal mice were dye labeled and individually cohybridized with a reference of labeled cDNAs pooled from a variety of tissues on 8 gene arrays containing 8,975 mouse DNA sequences. Normal variability in expression of each gene was evaluated and incorporated into “expression scores” to statistically compare expression levels between WT and KO samples. In Cx43-null astrocytes, 4.1% of the 4,998 adequately quantifiable spots were found to have significantly ( P < 0.05) decreased hybridization compared with controls, and 9.4% of the spots showed significantly higher hybridization. The significantly different spots corresponded to RNAs encoding 252 known proteins, many not previously linked to gap junctions, including transcription factors, channels and transporters, cell growth and death signals, enzymes and cell adhesion molecules. These data indicate a surprisingly high degree of impact of deletion of Cx43 on other astrocyte genes, implying that gap junction gene expression alters numerous processes in addition to intercellular communication.
Discovery of molecular mechanisms of neuroprotection using cell-based bioassays and oligonucleotide arrays
Authors: Sarang Satinder S. , Yoshida Takumi , Cadet Rodolphe , Valeras Andrew S. , Jensen Roderick V. , Gullans Steven R.
Published: March 2015

Oxidative injury and the resulting death of neurons is a major pathological factor involved in numerous neurodegenerative diseases. However, the development of drugs that target this mechanism remains limited. The goal of this study was to test a compound library of approved Food and Drug Administration drugs against a hydrogen peroxide-induced oxidant injury model in neuroblastoma cells. We identified 26 neuroprotective compounds, of which megestrol, meclizine, verapamil, methazolamide, sulindac, and retinol were examined in greater detail. Using large-scale oligonucleotide microarray analysis, we identified genes modulated by these drugs that might underlie the cytoprotection. Five key genes were either uniformly upregulated or downregulated by all six drug treatments, namely, tissue inhibitor of matrix metalloproteinase (TIMP1), ret-proto-oncogene, clusterin, galanin, and growth associated protein (GAP43). Exogenous addition of the neuropeptide galanin alone conferred survival to oxidant-stressed cells, comparable to that seen with the drugs. Our approach, which we term “interventional profiling,” represents a general and powerful strategy for identifying new bioactive agents for any biological process, as well as identifying key downstream genes and pathways that are involved.
A knockout approach indicates a minor vasoconstrictor role for vascular α 1B-adrenoceptors in mouse
Authors: Daly Craig J. , Deighan Clare , McGee Ann , Mennie Dawson , Ali Zeeshan , McBride Melissa , McGrath John C.
Published: March 2015

Pharmacological analysis alone has failed to clarify the role of the three α1-adrenoceptor subtypes in modulating vascular tone, due to a lack of sufficiently selective antagonists, particularly for the α 1B-adrenoceptor, and the complexity when three receptor subtypes are potentially activated by the same agonist. We adopted a combined genetics/ pharmacology strategy based on the α1B-adrenoceptor knockout (KO) mouse. The potency of three α1-adrenoceptor antagonists vs. phenylephrine was tested in aorta, carotid, mesenteric, and caudal isolated arteries from KO and wild-type (WT) mice. In the KO mouse the pharmacology became straightforward, showing α1D in two major conducting arteries (aorta and carotid) and α1A in two distributing arteries (mesenteric and caudal). By combining antagonist pharmacology and genetics, we provide a simplified analysis of α1-mediated vasoconstriction, demonstrating that α1D and α1A are the major subtypes involved in vasoconstriction, with a minor but definite contribution from α1B in every vessel.
Reciprocal rat chromosome 2 congenic strains reveal contrasting blood pressure and heart rate QTL
Authors: Alemayehu Adamu , Breen Laura , Krenova Drahomira , Printz Morton P.
Published: March 2015

Evidence exists implying multiple blood pressure quantitative trait loci (QTL) on rat chromosome 2. To examine this possibility, four congenic strains and nine substrains were developed with varying size chromosome segments introgressed from the spontaneously hypertensive rat (SHR/lj) and normotensive Wistar-Kyoto rat (WKY/lj) onto the reciprocal genetic background. Cardiovascular phenotyping was conducted with telemetry over extended periods during standard salt (0.7%) and high-salt (8%) diets. Our results are consistent with at least three independent pressor QTL: transfer of SHR/lj alleles to WKY/lj reveals pressor QTL within D2Rat21-D2Rat27 and D2Mgh10-D2Rat62, whereas transfer of WKY/lj D2Rat161-D2Mit8 to SHR/lj reveals a depressor locus. Our results also suggest a depressor QTL in SHR/lj located within D2Rat161-D2Mgh10. Introgressed WKY/lj segments also reveal a heart rate QTL within D2Rat40-D2Rat50 which abolished salt-induced bradycardia, dependent upon adjoining SHR/lj alleles. This study confirms the presence of multiple blood pressure QTL on chromosome 2. Taken together with our other studies, we conclude that rat chromosome 2 is rich in alleles for cardiovascular and behavioral traits and for coordinated coupling between behavior and cardiovascular responses.