bluuebunny/crossref_metadata_2025 huggingface dataset:
Selected Contribution: Variation in acute hypoxic ventilatory response is linked to mouse chromosome 9
Authors: Tankersley Clarke G.
Published: December 2017

Genetic determinants confer variation among inbred mouse strains with respect to the magnitude and pattern of breathing during acute hypoxic challenge. Specifically, inheritance patterns derived from C3H/HeJ (C3) and C57BL/6J (B6) parental strains suggest that differences in hypoxic ventilatory response (HVR) are controlled by as few as two genes. The present study demonstrates that at least one genetic determinant is located on mouse chromosome 9. This genotype-phenotype association was established by phenotyping 52 B6C3F2(F2) offspring for HVR characteristics. A genome-wide screen was performed using microsatellite DNA markers ( n = 176) polymorphic between C3 and B6 mice. By computing log-likelihood values (LOD scores), linkage analysis compared marker genotypes with minute ventilation (V˙e), tidal volume (Vt), and mean inspiratory flow (Vt/Ti, where Ti is inspiratory time) during acute hypoxic challenge (inspired O2fraction = 0.10, inspired CO2fraction = 0.03 in N2). A putative quantitative trait locus (QTL) positioned in the vicinity of D9Mit207 was significantly associated with hypoxic V˙e (LOD = 4.5), Vt (LOD = 4.0), and Vt/Ti (LOD = 5.1). For each of the three HVR characteristics, the putative QTL explained more than 30% of the phenotypic variation among F2offspring. In conclusion, this genetic model of differential HVR characteristics demonstrates that a locus ∼33 centimorgans from the centromere on mouse chromosome 9 confers a substantial proportion of the variance inV˙e, Vt, and Vt/Tiduring acute hypoxic challenge.
Effect of combined recompression and air, oxygen, or heliox breathing on air bubbles in rat tissues
Authors: Hyldegaard O. , Kerem D. , Melamed Y.
Published: December 2017

The fate of bubbles formed in tissues during the ascent from a real or simulated air dive and subjected to therapeutic recompression has only been indirectly inferred from theoretical modeling and clinical observations. We visually followed the resolution of micro air bubbles injected into adipose tissue, spinal white matter, muscle, and tendon of anesthetized rats recompressed to and held at 284 kPa while rats breathed air, oxygen, heliox 80:20, or heliox 50:50. The rats underwent a prolonged hyperbaric air exposure before bubble injection and recompression. In all tissues, bubbles disappeared faster during breathing of oxygen or heliox mixtures than during air breathing. In some of the experiments, oxygen breathing caused a transient growth of the bubbles. In spinal white matter, heliox 50:50 or oxygen breathing resulted in significantly faster bubble resolution than did heliox 80:20 breathing. In conclusion, air bubbles in lipid and aqueous tissues shrink and disappear faster during recompression during breathing of heliox mixtures or oxygen compared with air breathing. The clinical implication of these findings might be that heliox 50:50 is the mixture of choice for the treatment of decompression sickness.
Oxidation of [13C]glycerol ingested along with glucose during prolonged exercise
Authors: Burelle Y. , Massicotte D. , Lussier M. , Lavoie C. , Hillaire-Marcel C. , Péronnet F.
Published: December 2017

The respective oxidation of glycerol and glucose (0.36 g/kg each) ingested simultaneously immediately before exercise (120 min at 68 ± 2% maximal oxygen uptake) was measured in six subjects using 13C labeling. Indirect respiratory calorimetry corrected for protein and glycerol oxidation was used to evaluate the effect of glucose + glycerol ingestion on the oxidation of glucose and fat. Over the last 80 min of exercise, 10.0 ± 0.8 g of exogenous glycerol were oxidized (43% of the load), while exogenous glucose oxidation was 21% higher (12.1 ± 0.7 g or 52% of the load). However, because the energy potential of glycerol is 18% higher than that of glucose (4.57 vs. 3.87 kcal/g), the contribution of both exogenous substrates to the energy yield was similar (4.0–4.1%). Total glucose and fat oxidation were similar in the placebo (144.4 ± 13.0 and 60.5 ± 4.2 g, respectively) and the glucose + glycerol (135.2 ± 12.0 and 59.4 ± 6.5 g, respectively) trials, whereas endogenous glucose oxidation was significantly lower than in the placebo trial (123.7 ± 11.7 vs. 144.4 ± 13.0 g). These results indicate that exogenous glycerol can be oxidized during prolonged exercise, presumably following conversion into glucose in the liver, although direct oxidation in peripheral tissues cannot be ruled out.
Effect of diaphragm fatigue on neural respiratory drive
Authors: Luo Y. M. , Hart N. , Mustfa N. , Lyall R. A. , Polkey M. I. , Moxham J.
Published: December 2017

To test the hypothesis that diaphragm fatigue leads to an increase in neural respiratory drive, we measured the esophageal diaphragm electromyogram (EMG) during CO2rebreathing before and after diaphragm fatigue in six normal subjects. The electrode catheter was positioned on the basis of the amplitude and polarity of the diaphragm compound muscle action potential recorded simultaneously from four pairs of electrodes during bilateral anterior magnetic phrenic nerve stimulation (BAMPS) at functional residual capacity. Two minutes of maximum isocapnic voluntary ventilation (MIVV) were performed in six subjects to induce diaphragm fatigue. A maximal voluntary breathing against an inspiratory resistive loading (IRL) was also performed in four subjects. The reduction of transdiaphragmatic pressure elicited by BAMPS was 22% (range 13–27%) after 2 min of MIVV and was similar, 20% (range 13–26%), after IRL. There was a linear relationship between minute ventilation (V˙e) and the root mean square (RMS) of the EMG during CO2rebreathing before and after fatigue. The mean slope of the linear regression of RMS on V˙e was similar before and after diaphragm fatigue: 2.80 ± 1.31 vs. 3.29 ± 1.40 for MIVV and 1.51 ± 0.31 vs 1.55 ± 0.31 for IRL, respectively. We conclude that the esophageal diaphragm EMG can be used to assess neural drive and that diaphragm fatigue of the intensity observed in this study does not affect respiratory drive.
GABAergic modulation of ventilation and peak oxygen consumption in obese Zucker rats
Authors: Lee Shin-Da , Nakano Hitoshi , Farkas Gaspar A.
Published: December 2017

Obesity is often associated with a reduced ventilatory response and a decreased maximal exercise capacity. GABA is a major inhibitory neurotransmitter in the mammalian central nervous system. Altered GABAergic mechanisms have been detected in obese Zucker rats and implicated in their hyperphagic response. Whether altered GABAergic mechanisms also contribute to regulate ventilation and influence exercise capacity in obese Zucker rats is unknown and formed the basis of the present study. Eight lean [317 ± 18 (SD) g] and eight obese (450 ± 27 g) Zucker rats were studied at 12 wk of age. Ventilation at rest and ventilation during hypoxic (10% O2) and hypercapnic (4% CO2) challenges were measured by the barometric method. Peak O2consumption (V˙o2 peak) in response to a progressive treadmill test to exhaustion was measured in a metabolic treadmill. Ventilation and V˙o2 peakwere assessed after administration of equal volumes of DMSO (vehicle) and the GABAAreceptor antagonist bicuculline (1 mg/kg). In lean animals, bicuculline administration had no effect on ventilation andV˙o2 peak. In obese rats, bicuculline administration significantly ( P < 0.05) increased resting ventilation (465 ± 53 and 542 ± 72 ml · kg−1· min−1for control and bicuculline, respectively), ventilation during exposure to hypoxia (899 ± 148 and 1,038 ± 83 ml · kg−1· min−1for control and bicuculline, respectively), andV˙o2 peak(62 ± 3.7 and 67 ± 3.5 ml · kg−0.75· min−1for control and bicuculline, respectively). However, in obese Zucker rats, ventilation in response to hypercapnia did not change after bicuculline administration (608 ± 96 vs. 580 ± 69 ml · kg−1· min−1). Our findings indicate that endogenous GABA depresses ventilation and limits exercise performance in obese Zucker rats.
Exaggerated muscle mechanoreflex control of reflex renal vasoconstriction in heart failure
Authors: Middlekauff Holly R. , Nitzsche Egbert U. , Hoh Carl K. , Hamilton Michele A. , Fonarow Gregg C. , Hage Antoine , Moriguchi Jaime D.
Published: December 2017

In heart failure (HF) patients, reflex renal vasoconstriction during exercise is exaggerated. We hypothesized that muscle mechanoreceptor control of renal vasoconstriction is exaggerated in HF. Nineteen HF patients and nineteen controls were enrolled in two exercise protocols: 1) low-level rhythmic handgrip (mechanoreceptors and central command) and 2) involuntary biceps contractions (mechanoreceptors). Renal cortical blood flow was measured by positron emission tomography, and renal cortical vascular resistance (RCVR) was calculated. During rhythmic handgrip, peak RCVR was greater in HF patients compared with controls (37 ± 1 vs. 27 ± 1 units; P < 0.01). Change in (Δ) RCVR tended to be greater as well but did not reach statistical significance (10 ± 1 vs. 7 ± 0.9 units; P = 0.13). RCVR was returned to baseline at 2–3 min postexercise in controls but remained significantly elevated in HF patients. During involuntary muscle contractions, peak RCVR was greater in HF patients compared with controls (36 ± 0.7 vs. 24 ± 0.5 units; P < 0.0001). The Δ RCVR was also significantly greater in HF patients compared with controls (6 ± 1 vs. 4 ± 0.6 units; P = 0.05). The data suggest that reflex renal vasoconstriction is exaggerated in both magnitude and duration during dynamic exercise in HF patients. Given that the exaggerated response was elicited in both the presence and absence of central command, it is clear that intact muscle mechanoreceptor sensitivity contributes to this augmented reflex renal vasoconstriction.
Sprint training shortens prolonged action potential duration in postinfarction rat myocyte: mechanisms
Authors: Zhang Xue-Qian , Zhang Lian-Qin , Palmer Bradley M. , Ng Yuk-Chow , Musch Timothy I. , Moore Russell L. , Cheung Joseph Y.
Published: December 2017

Two electrophysiological manifestations of myocardial infarction (MI)-induced myocyte hypertrophy are prolongation of action potential duration (APD) and reduction of transient outward current ( I to) density. Because high-intensity sprint training (HIST) ameliorated myocyte hypertrophy and improved myocyte Ca2+ homeostasis and contractility after MI, the present study evaluated whether 6–8 wk of HIST would shorten the prolonged APD and improve the depressed I to in post-MI myocytes. There were no differences in resting membrane potential and action potential amplitude (APA) measured in myocytes isolated from sham-sedentary (Sed), MI-Sed, and MI-HIST groups. Times required for repolarization to 50 and 90% APA were significantly ( P < 0.001) prolonged in MI-Sed myocytes. HIST reduced times required for repolarization to 50 and 90% APA to values observed in Sham-Sed myocytes. The fast and slow components of I towere significantly ( P < 0.0001) reduced in MI-Sed myocytes. HIST significantly ( P < 0.001) enhanced the fast and slow components of I to in MI myocytes, although not to levels observed in Sham-Sed myocytes. There were no significant differences in steady-state I toinactivation and activation parameters among Sham-Sed, MI-Sed, and MI-HIST myocytes. Likewise, recovery from time-dependent inactivation was also similar among the three groups. We suggest that normalization of APD after MI by HIST may be mediated by restoration of I to toward normal levels.
Carbon dioxide pressure-concentration relationship in arterial and mixed venous blood during exercise
Authors: Sun Xing-Guo , Hansen James E. , Stringer William W. , Ting Hua , Wasserman Karlman
Published: December 2017

To calculate cardiac output by the indirect Fick principle, CO2concentrations (Cco2) of mixed venous (Cv̄CO2) and arterial blood are commonly estimated from Pco2, based on the assumption that the CO2pressure-concentration relationship (Pco2-Cco2) is influenced more by changes in Hb concentration and blood oxyhemoglobin saturation than by changes in pH. The purpose of the study was to measure and assess the relative importance of these variables, both in arterial and mixed venous blood, during rest and increasing levels of exercise to maximum (Max) in five healthy men. Although the mean mixed venous Pco2rose from 47 Torr at rest to 59 Torr at the lactic acidosis threshold (LAT) and further to 78 Torr at Max, the Cv̄CO2rose from 22.8 mM at rest to 25.5 mM at LAT but then fell to 23.9 mM at Max. Meanwhile, the mixed venous pH fell from 7.36 at rest to 7.30 at LAT and to 7.13 at Max. Thus, as work rate increases above the LAT , changes in pH, reflecting changes in buffer base, account for the major changes in the Pco2-Cco2relationship, causing Cv̄CO2to decrease, despite increasing mixed venous Pco2. Furthermore, whereas the increase in the arteriovenous Cco2difference of 2.2 mM below LAT is mainly due to the increase in Cv̄CO2, the further increase in the arteriovenous Cco2difference of 4.6 mM above LAT is due to a striking fall in arterial Cco2from 21.4 to 15.2 mM. We conclude that changes in buffer base and pH dominate the Pco2-Cco2relationship during exercise, with changes in Hb and blood oxyhemoglobin saturation exerting much less influence.
Placental compliance during fetal extracorporeal circulation
Authors: Assad R. S. , Lee F. Y. , Hanley F. L.
Published: December 2017

The fetus requires large amounts of volume when weaning from cardiac bypass. This suggests that placental vasculature can act as a large capacitor in the fetal circulation. To assess placental compliance of fetal lambs, seven isolated in situ lamb placentas were placed on extracorporeal circulation. Umbilical artery blood flow was varied from 0 to 350 ml · min−1· kg fetal wt−1. Because the extracorporeal circuit is a closed system, volume changes in the placenta induced by umbilical artery pressure changes were measured from reciprocal volume changes in the reservoir. There was a wide range of change in absolute volume of blood within the fetal placental compartment (216.4 ± 29.3 ml). Placental compliance was linear over the entire range of pressure changes exerted on the placental vasculature ( r2= 0.83, P = 0.0001). This indicates that the placenta is a unique and sensitive capacitor in the fetal circulation. This information is important clinically because it establishes that aggressive resuscitation of the fetus using volume may be necessary when weaning the fetus from cardiac bypass.
Intracellular signaling specificity in skeletal muscle in response to different modes of exercise
Authors: Nader Gustavo A. , Esser Karyn A.
Published: December 2017

The aim of this study was to understand better the specific signaling events resulting from different modes of exercise. Three different exercise protocols were employed based on their well-characterized, long-term training effects on either muscle hypertrophy or endurance phenotypes. Rats were subjected to a single bout of either a high-frequency electrical stimulation, a low-frequency electrical stimulation, or a running exercise protocol. Postexercise intracellular signaling was analyzed in the tibialis anterior and soleus muscles at 0, 3, and 6 h. A prolonged increase in p70S6kand a transient increase in protein kinase B phosphorylation were only observed in response to a growth-inducing stimulus (e.g., tibialis anterior in high-frequency electrical stimulation). In contrast, extracellular regulated kinase and 38-kDa stress-activated protein kinase were activated in response to all forms of exercise at 0 h, but only extracellular regulated kinase phosphorylation was found significantly elevated at 6 h after running exercise. These results demonstrate that different exercise protocols resulted in the selective activation of specific intracellular signaling pathways, which may determine the specific adaptations induced by different forms of exercise.
Individualized model of human thermoregulation for the simulation of heat stress response
Authors: Havenith George
Published: December 2017

A population-based dynamic model of human thermoregulation was expanded with control equations incorporating the individual person's characteristics (body surface area, mass, fat%, maximal O2 uptake, acclimation). These affect both the passive (heat capacity, insulation) and active systems (sweating and skin blood flow function). Model parameters were estimated from literature data. Other data, collected for the study of individual differences {working at relative or absolute workloads in hot-dry [45°C, 20% relative humidity (rh)], warm-humid [35°C, 80% rh], and cool [21°C, 50% rh] environments}, were used for validation. The individualized model provides an improved prediction [mean core temperature error, −0.21 → −0.07°C ( P< 0.001); mean squared error, 0.40 → 0.16°C, ( P < 0.001)]. The magnitude of improvement varies substantially with the climate and work type. Relative to an empirical multiple-regression model derived from these specific data sets, the analytical simulation model has between 54 and 89% of its predictive power, except for the cool climate, in which this ratio is zero. In conclusion, individualization of the model allows improved prediction of heat strain, although a substantial error remains.
A rat lung model of instilled liquid transport in the pulmonary airways
Authors: Cassidy K. J. , Bull J. L. , Glucksberg M. R. , Dawson C. A. , Haworth S. T. , Hirschl R. , Gavriely N. , Grotberg J. B.
Published: December 2017

When a liquid is instilled in the pulmonary airways during medical therapy, the method of instillation affects the liquid distribution throughout the lung. To investigate the fluid transport dynamics, exogenous surfactant (Survanta) mixed with a radiopaque tracer is instilled into tracheae of vertical, excised rat lungs (ventilation 40 breaths/min, 4 ml tidal volume). Two methods are compared: For case A, the liquid drains by gravity into the upper airways followed by inspiration; for case B, the liquid initially forms a plug in the trachea, followed by inspiration. Experiments are continuously recorded using a microfocal X-ray source and an image-intensifier, charge-coupled device image train. Video images recorded at 30 images/s are digitized and analyzed. Transport dynamics during the first few breaths are quantified statistically and follow trends for liquid plug propagation theory. A plug of liquid driven by forced air can reach alveolar regions within the first few breaths. Homogeneity of distribution measured at end inspiration for several breaths demonstrates that case B is twice as homogeneous as case A. The formation of a liquid plug in the trachea, before inspiration, is important in creating a more uniform liquid distribution throughout the lungs.
Threshold levels of maternal nicotine impairing protective responses of newborn rats to intermittent hypoxia
Authors: Fewell James E. , Smith Francine G. , Ng Vienna K. Y.
Published: December 2017

Experiments were carried out to determine the threshold level of maternal nicotine that impairs protective responses of rat pups to hypoxia. From days 6 or 7 of gestation, pregnant rats received either vehicle or nicotine (1.50, 3.00, or 6.00 mg of nicotine tartrate · kg body wt−1· day−1) or vehicle continuously via a subcutaneous osmotic minipump. On postnatal days 5 or 6, pups were exposed to a single period of hypoxia produced by breathing an anoxic gas mixture (97% N2or 3% CO2) and their time to last gasp was determined, or they were exposed to intermittent hypoxia and their ability to autoresuscitate from hypoxic-induced primary apnea was determined. Perinatal exposure to nicotine did not alter the time to last gasp or the total number of gasps when the pups were exposed to a single period of hypoxia. The number of successful autoresuscitations on repeated exposure to hypoxia was, however, decreased in pups whose dams had received either 3.00 or 6.00 mg of nicotine tartrate/kg body wt; these dosage regimens produced maternal serum nicotine concentrations of 19 ± 6 and 35 ± 8 ng/ml, respectively. Thus our experiments define the threshold level of maternal nicotine that significantly impairs protective responses of 5- to 6-day-old rat pups to intermittent hypoxia such as may occur in human infants during episodes of prolonged sleep apnea or positional asphyxia.
Selected Contribution: Phrenic long-term facilitation requires 5-HT receptor activation during but not following episodic hypoxia
Authors: Fuller D. D. , Zabka A. G. , Baker T. L. , Mitchell G. S.
Published: December 2017

Episodic hypoxia evokes a sustained augmentation of respiratory motor output known as long-term facilitation (LTF). Phrenic LTF is prevented by pretreatment with the 5-hydroxytryptamine (5-HT) receptor antagonist ketanserin. We tested the hypothesis that 5-HT receptor activation is necessary for the induction but not maintenance of phrenic LTF. Peak integrated phrenic nerve activity (∫Phr) was monitored for 1 h after three 5-min episodes of isocapnic hypoxia (arterial Po 2 = 40 ± 2 Torr; 5-min hyperoxic intervals) in four groups of anesthetized, vagotomized, paralyzed, and ventilated Sprague-Dawley rats [ 1) control ( n = 11), 2) ketanserin pretreatment (2 mg/kg iv; n = 7), and ketanserin treatment 0 and 45 min after episodic hypoxia ( n = 7 each)]. Ketanserin transiently decreased ∫Phr, but it returned to baseline levels within 10 min. One hour after episodic hypoxia, ∫Phr was significantly elevated from baseline in control and in the 0- and 45-min posthypoxia ketanserin groups. Conversely, ketanserin pretreatment abolished phrenic LTF. We conclude that 5-HT receptor activation is necessary to initiate (during hypoxia) but not maintain (following hypoxia) phrenic LTF.
Invited Review: Identifying new mouse models of cardiovascular disease: a review of high-throughput screens of mutagenized and inbred strains
Authors: Svenson Karen L. , Bogue Molly A. , Peters Luanne L.
Published: December 2017

The mouse is a proven model for studying human disease. Many strains exist that exhibit either natural or engineered genetic variation and thereby enable the elucidation of pathways involved in the development of cardiovascular disease. Although those mouse models have been fundamental to advancing our knowledge base, we are still at an early stage in understanding how genes contribute to complex disorders. There remains a need for new animal models that closely represent human disease. To expedite their development, we have established the Center for New Mouse Models of Heart, Lung, Blood, and Sleep Disorders at The Jackson Laboratory. We are using a phenotype-driven approach to identify mutations leading to atherosclerosis, hypertension, obesity, blood disorders, lung dysfunction, thrombosis, and disordered sleep. Our high-throughput, comprehensive phenotyping draws from two sources for new models: 1) the natural variation among over 40 inbred mouse strains and 2) chemically induced, whole-genome mutagenized mice. Here, we review our cardiovascular screens and present some hypertensive, obese, and cardiovascular models identified with this approach.
Functional genomics: technological challenges and opportunities
Authors: STRAUSBERG ROBERT L. , AUSTIN M. J. FINLEY
Published: December 2017

Strausberg, Robert L., and M. J. Finley Austin. Functional genomics: technological challenges and opportunities. Physiol. Genomics 1: 25–32, 1999.—In April, the Merck Genome Research Institute and the National Cancer Institute's Cancer Genome Anatomy Project, both supporters of functional genomics technology development and research, brought together a group of 27 scientists working at the forefront of this new field. Here we report on the presentations, discussions, and outcomes from this highly interactive and stimulating meeting held at the Banbury Center.
Genetic analysis of modifying loci on mouse chromosome 1 that affect disease severity in a model of recessive PKD
Authors: IAKOUBOVA OLGA , DUSHKIN HOLLY , PACELLA LISA , BEIER DAVID R.
Published: December 2017

Iakoubova, Olga, Holly Dushkin, Lisa Pacella, and David R. Beier. Genetic analysis of modifying loci on mouse chromosome 1 that affect disease severity in a model of recessive PKD. Physiol. Genomics: 101–105, 1999.—Using a cross between C57BL/6J and FVB/N mice, we have confirmed the localization on chromosome 1 of a modifying locus that affects the severity of polycystic kidney disease (PKD) in the juvenile cystic kidney ( jck) mouse. Despite the highly significant contribution of this locus in F2 progeny of a cross between C57BL/6J and DBA/2J mice ( 4 ), a series of congenic strains carrying regions of chromosome 1 on a DBA/2J background did not show a severe disease phenotype. One possible explanation for these results is that this phenotype is caused by two linked loci, which have been separated in the congenic lines that were generated. This hypothesis is supported by the demonstration that severe PKD occurs in mice carrying a large congenic interval.
Cloning and analysis of unique human glutaminase isoforms generated by tissue-specific alternative splicing
Authors: ELGADI KHALED M. , MEGUID ROBERT A. , QIAN MING , SOUBA WILEY W. , ABCOUWER STEVE F.
Published: December 2017

Elgadi, Khaled M., Robert A. Meguid, Ming Qian, Wiley W. Souba, and Steve F. Abcouwer. Cloning and analysis of unique human glutaminase isoforms generated by tissue-specific alternative splicing. Physiol. Genomics 1: 51–62, 1999.—Three human glutaminase (hGA) isoforms were identified, two of which represent isoforms previously unidentified in any species. One isoform contains an open reading frame with high homology with the rat kidney-type glutaminase, suggesting that this isoform represents the human kidney-type glutaminase, hKGA. A second isoform, termed hGAC, contains an open reading frame that matches hKGA except for a unique COOH-terminal amino acid sequence. In addition, a third human glutaminase isoform was identified from a computer search and on further analysis was found to represent an additional unique isoform, hGAM. hKGA is expressed predominantly in brain and kidney but not in liver, hGAC is expressed principally in cardiac muscle and pancreas but not in liver or brain, and hGAM is expressed solely in cardiac and skeletal muscle. hGAC is the predominant isoform expressed by a human breast cancer cell line that exhibits a high rate of glutamine utilization and glutaminase activity. Genomic Southern analysis as well as isolation and analysis of five glutaminase genomic clones suggested that all three hGA isoforms originate from the same locus and therefore represent mRNA species that are produced by tissue-specific alternative splicing of a single pre-mRNA. Furthermore, an RT-PCR assay was developed that can be used to easily differentiate between hKGA and hGAC mRNA species.
Cholesteryl ester hydrolase in human monocyte/macrophage: cloning, sequencing, and expression of full-length cDNA
Authors: GHOSH SHOBHA
Published: December 2017

Ghosh, Shobha. Cholesteryl ester hydrolase in human monocyte/macrophage: cloning, sequencing, and expression of full-length cDNA. Physiol. Genomics 2: 1–8, 2000.—The sensitive technique of RT-PCR was used to identify cholesteryl ester hydrolase (CEH) expressed in human macrophages. This enzyme is thought to regulate the availability of intracellular free cholesterol for efflux. The expected 667-bp product was obtained starting with RNA from human peripheral blood and THP-1 monocytes and macrophages. The cDNA for human macrophage CEH was then cloned by PCR-based screening of a λ-gt11 cDNA library. The full-length cDNA was sequenced and found to exhibit 76% homology (at the nucleotide and conceptually translated protein level) to hepatic CEH, an enzyme shown to be involved in hepatic cholesterol homeostasis and regulated by cholesterol at the transcription level via sterol response elements in the proximal promoter. Identification of the conserved catalytic triad (Ser221, His468, and Glu354) and the SEDCLY motif places human macrophage CEH in the family of carboxylesterases. A greater than 20-fold increase in CEH activity was observed when COS-1 and COS-7 cells were transiently transfected with an eukaryotic expression vector, pcDNA3.1/V5/His-TOPO, containing the cDNA for human macrophage CEH. Using this full-length cDNA as a probe, a 2.2-kb transcript was identified by Northern blot analysis of total RNA from human peripheral blood and THP-1 macrophages. Overexpression of human macrophage CEH resulted in an impairment of upregulation of low-density lipoprotein (LDL) receptor mRNA in Chinese hamster ovary (CHO-K1) cells grown in cholesterol-deficient environment. These data identify the human macrophage CEH, demonstrate its expression in human peripheral blood macrophage and human macrophage cell line, THP-1, and suggest its role in the intracellular cholesteryl ester metabolism.
Realizing the potential of zebrafish as a model for human disease
Authors: BARUT BRUCE A. , ZON LEONARD I.
Published: December 2017

Barut, Bruce A., and Leonard I. Zon. Realizing the potential of zebrafish as a model for human disease. Physiol Genomics 2: 49–51, 2000.—The value of the zebrafish ( Danio rerio) as a model for human disease has been substantiated by a number of recently published papers. Several zebrafish mutants with “human” diseases have been found, spanning a variety of human pathologies. These successful studies utilizing the zebrafish have been made possible by the development of key reagents such as YAC, PAC, and BAC libraries, as well as radiation hybrid panels. With the further establishment of new tools and access to the newly generated resources, the zebrafish is poised to serve as a novel model for human disease.
Targeting theHprtlocus in mice reveals differential regulation ofTie2gene expression in the endothelium
Authors: EVANS VALERIE , HATZOPOULOS ANTONIS , AIRD WILLIAM C. , RAYBURN HELEN B. , ROSENBERG ROBERT D. , KUIVENHOVEN JAN ALBERT
Published: December 2017

Evans, Valerie, Antonis Hatzopoulos, William C. Aird, Helen B. Rayburn, Robert D. Rosenberg, and Jan Albert Kuivenhoven. Targeting the Hprt locus in mice reveals differential regulation of Tie2 gene expression in the endothelium. Physiol Genomics 2: 67–75, 2000.—To study the in vivo expression of the murine Tie2 gene, we have targeted the hypoxanthine phosphoribosyltransferase ( Hprt) gene locus to generate two single-copy transgenic mice: T1, containing the 2,100-bp Tie2 promoter upstream from the β-galactosidase ( LacZ) gene, and T5, which also included an enhancing element originating from the first intron of the Tie2 gene. Comparing T1 and T5 embryos at day E10.5 revealed differential endothelial cell-specific expression of LacZ, whereas colocalization analyses showed that the expression was confined to endothelial cells. Moderate reporter gene activity was observed in the brain and kidney of T1 adults, whereas extensive LacZ gene expression was seen in the vasculature of most organs of the T5 adults. This study demonstrates the feasibility of targeting the Hprt locus with endothelial cell-specific sequences to analyze the spatial-temporal expression of transgenes. Of particular importance is the observation that the analysis of a single transgene copy in a defined locus allows for an accurate and rapid comparison of transcriptional activity among regulatory DNA sequences.
Regulation of leptin by agouti
Authors: CLAYCOMBE KATE J. , XUE BING ZHONG , MYNATT RANDALL L. , ZEMEL MICHAEL B. , MOUSTAID-MOUSSA NAIMA
Published: December 2017

Claycombe, Kate J., Bing Zhong Xue, Randall L. Mynatt, Michael B. Zemel, and Naïma Moustaïd-Moussa. Regulation of leptin by agouti. Physiol Genomics 2: 101–105, 2000.—Dominant mutations at the mouse Agouti locus lead to ectopic expression of the Agouti gene and exhibit diabetes, obesity, and yellow coat color. Obese yellow mice are hyperinsulinemic and hyperleptinemic, and we hypothesized that Agouti directly induces leptin secretion. Accordingly, we used transgenic mice expressing agouti in adipocytes (under the control of aP2 promoter, aP212) to examine changes in leptin levels. Agouti expression in adipose tissue did not significantly alter food intake, weight gain, fat pad weight, or insulinemia; however, the transgenic mice were hyperglycemic. We demonstrated that plasma leptin levels are approximately twofold higher in aP212 transgenic mice compared with their respective controls, whereas ubiquitous expression of agouti (under the control of β-actin promoter, BAP20) led to a sixfold increase in leptin. Insulin treatment of aP212 mice increased adipocyte leptin content without affecting plasma leptin levels. These findings were further confirmed in vitro in 3T3-L1 adipocytes treated with recombinant Agouti protein and/or insulin. Agouti but not insulin significantly increased leptin secretion, indicating that insulin enhances leptin synthesis but not secretion while Agouti increases both leptin synthesis and secretion. This increased leptin synthesis and secretion was due to increased leptin mRNA levels by Agouti. Interestingly, agouti regulation of leptin was not mediated by melanocortin receptor 4, previously implicated in agouti regulation of food intake. These results suggest that increased leptin secretion by agouti may serve to limit agouti-induced obesity, independent of melanocortin receptor antagonism, and indicate that interaction between obesity genes may play a key role in obesity.
Adeno-associated virus vector transduction of vascular smooth muscle cells in vivo
Authors: RICHTER MATTHIAS , IWATA AKIKO , NYHUIS JOHN , NITTA YOSHIO , MILLER A. DUSTY , HALBERT CHRISTINE L. , ALLEN MARGARET D.
Published: December 2017

Richter, Matthias, Akiko Iwata, John Nyhuis, Yoshio Nitta, A. Dusty Miller, Christine L. Halbert, and Margaret D. Allen. Adeno-associated virus vector transduction of vascular smooth muscle cells in vivo. Physiol Genomics 2: 117–127, 2000.—Adeno-associated virus (AAV) vectors might offer solutions for restenosis and angiogenesis by transducing nondividing cells and providing long-term gene expression. We investigated the feasibility of vascular cell transduction by AAV vectors in an in vivo rabbit carotid artery model. Time course of gene expression, inflammatory reaction to the vector, and effects of varying viral titer, exposure time, and intraluminal pressures on gene expression were examined. Recombinant AAV vectors with an Rous sarcoma virus promoter and alkaline phosphatase reporter gene were injected intraluminally into transiently isolated carotid segments. Following transduction, gene expression increased significantly over 14 days and then remained stable to 28 days, the last time point examined. Medial vascular smooth muscle cells were the main cell type transduced even with an intact endothelial layer. Increasing the viral titer and intraluminal pressure both enhanced transduction efficiency to achieve a mean of 34 ± 7% of the subintimal layer of smooth muscle cells expressing gene product. A mild inflammatory reaction, composed of T cells with only rare macrophages, with minimal intimal thickening was demonstrated in 40% of transduced vessels; inflammatory cells were not detected in sham-operated control arteries. These findings demonstrate that AAV is a promising vector for intravascular applications in coronary and peripheral vascular diseases.
Inactivation of one copy of the mouse neurotrophin-3 gene induces cardiac sympathetic deficits
Authors: STORY GINA M. , DICARLO STEPHEN E. , RODENBAUGH DAVID W. , DLUZEN DEAN E. , KUCERA JAN , MARON MICHAEL B. , WALRO JON M.
Published: December 2017

Story, Gina M., Stephen E. DiCarlo, David W. Rodenbaugh, Dean E. Dluzen, Jan Kucera, Michael B. Maron, and Jon M. Walro. Inactivation of one copy of the mouse neurotrophin-3 gene induces cardiac sympathetic deficits. Physiol Genomics 2: 129–136, 2000.—Whether two copies of the neurotrophin-3 (NT3) gene are necessary for proper development of cardiac sympathetic innervation was investigated in mice carrying a targeted inactivation of the NT3 gene. Heterozygous (+/−) and null (−/−) mutant mice had fewer stellate ganglion neurons than did wild-type (+/+) mice at postnatal day 0 ( P0 or birth), and this deficit was maintained between adult ( P60) +/− and +/+ mice. The sympathetic innervation of the heart matured postnatally in +/+ and +/− mice. Tyrosine hydroxylase (TH)-positive axons were restricted largely to the epicardium at P0, were concentrated around large blood vessels in the myocardium at P21, and were present among cardiac myocytes at P60. Cardiac norepinephrine (NE) concentrations paralleled the growth of the sympathetic axons into the heart. NE concentrations were equivalent among +/+, +/−, and −/− mice at birth, but differences between +/− and +/+ mice increased with age. Adult +/− mice also exhibited lower resting heart rates and sympathetic tonus than +/+ mice. Thus deletion of one copy of the NT3 gene translates into anatomical, biochemical, and functional deficits in cardiac sympathetic innervation of postnatal mice, thereby indicating a gene-dosage effect for the NT3 gene.
Comparison of human adult and fetal expression and identification of 535 housekeeping/maintenance genes
Authors: WARRINGTON JANET A. , NAIR ARCHANA , MAHADEVAPPA MAMATHA , TSYGANSKAYA MAYA
Published: December 2017

Warrington, Janet A., Archana Nair, Mamatha Mahadevappa, and Maya Tsyganskaya. Comparison of human adult and fetal expression and identification of 535 housekeeping/maintenance genes. Physiol Genomics 2: 143–147, 2000.—Gene expression levels of about 7,000 genes were measured in 11 different human adult and fetal tissues using high-density oligonucleotide arrays to identify genes involved in cellular maintenance. The tissues share a set of 535 transcripts that are turned on early in fetal development and stay on throughout adulthood. Because our goal was to identify genes that are involved in maintaining cellular function in normal individuals, we minimized the effect of individual variation by screening mRNA pooled from many individuals. This information is useful for establishing average expression levels in normal individuals. Additionally, we identified transcripts uniquely expressed in each of the 11 tissues.
Gene expression profile in mouse myocardium after ischemia
Authors: LYN DEBORAH , LIU XIAOWEI , BENNETT NICOLE A. , EMMETT NERIMIAH L.
Published: December 2017

Lyn, Deborah, Xiaowei Liu, Nicole A. Bennett, and Nerimiah L. Emmett. Gene expression profile in mouse myocardium after ischemia. Physiol Genomics 2: 93–100, 2000.—This study was designed to elaborate a molecular profile of expressed genes during ischemic injury to the mouse heart after surgical constriction of the left coronary artery without reperfusion. A mouse cDNA array containing 588 known genes was used to compare gene expression in heart RNA after 24-h ischemia with control tissue. Alterations in gene expression on the array were supported by relative reverse transcription-polymerase chain reaction analysis after timed periods of ischemia. Decreased levels of the cell cycle regulator p18ink4 and the oxidative responsive gene glutathione S-transferase were accompanied by an upregulation of the genes associated with cardiac muscle development, α-myosin heavy chain and fetal myosin alkali light chain. Other stress responses elicited by cardiac injury included an induction of Egr-1 and Egr-3 transcription factors, as well as the apoptotic regulator Bax. Altogether, these findings indicate that expression of genes associated with a fetal transcription program may be involved with the post ischemic remodeling process in heart ventricles.
Identification of three human renin mRNA isoforms from alternative tissue-specific transcriptional initiation
Authors: SINN PATRICK L. , SIGMUND CURT D.
Published: December 2017

Sinn, Patrick L., and Curt D. Sigmund. Identification of three human renin mRNA isoforms from alternative tissue-specific transcriptional initiation. Physiol Genomics 3: 25–31, 2000.—We have reported that mice transgenic for 140- and 160-kb P1 phage artificial chromosomes (PACs) containing the human renin gene express the gene in a highly tissue-restricted and regulated manner. Herein, we demonstrate that the transgene is also expressed appropriately throughout development. In the course of this investigation, we identified the existence of three transcriptional isoforms of human renin mRNA derived from the utilization of alternative transcription start sites. The first isoform is the kidney-specific isoform, which utilizes the classic renin promoter. The second is a brain-specific isoform, which when previously identified in rats and mice was due to a transcription initiation site within intron A. However, the start site in the human gene resides ∼1,325 bp upstream of the classic promoter and encodes a new exon 1 (termed exon 1b) that splices directly to exon 2. The third isoform is lung specific and is due to transcriptional initiation 79 bp directly upstream of exon 2, fusing additional DNA within intron A (termed exon 1c) directly to exon 2 without splicing. Importantly, the alternative first exons observed in the PAC transgenic mice were identical to those used to transcribe renin in human fetal kidney, brain, and lung, suggesting these sites are bona fide isoforms of human renin mRNA and not artifacts of transgenesis. Moreover, the subtle differences in tissue-specific transcriptional initiation observed in the renin gene of rats and humans can be faithfully and accurately emulated in a transgenic model.
Cloning a chloride conductance mediator from the apical membrane of porcine ileal enterocytes
Authors: GASPAR K. J. , RACETTE K. J. , GORDON J. R. , LOEWEN M. E. , FORSYTH G. W.
Published: December 2017

Gaspar, K. J., K. J. Racette, J. R. Gordon, M. E. Loewen, and G. W. Forsyth. Cloning a chloride conductance mediator from the apical membrane of porcine ileal enterocytes. Physiol Genomics 3: 101–111, 2000.—Attempts to attribute ileal brush-border chloride conductance to specific proteins were pursued by screening a porcine intestinal cDNA library. A 0.94-kb clone was identified on expression screening with a monoclonal antibody that inhibited enterocyte brush-border chloride conductance. Further screening approaches led to the isolation of a 3.1-kb full-length sequence called pCLCA1, consistent with the identification of a 2.9-kb transcript through Northern analysis. This sequence had significant homology to the CLCA gene family of calcium-regulated chloride channels, especially to hCLCA1. However, a strong A-kinase consensus phosphorylation site in a predicted cytoplasmic loop of the protein was a notable difference from the hCLCA1 gene product. Several porcine exocrine epithelial tissues, including ileum, trachea, and the major salivary glands express pCLCA1 mRNA. In situ hybridization studies localized the expression of pCLCA1 mRNA to the crypt and villus epithelia of porcine ileum, whereas tracheal expression was observed in both surface epithelium and submucosal glands. In situ expression of pCLCA1 in mouse 3T3 cells induces an ionomycin-dependent chloride conductance activity in these cells.
BradykininB2null mice are prone to renal dysplasia: gene-environment interactions in kidney development
Authors: EL-DAHR SAMIR S. , HARRISON-BERNARD LISA M. , DIPP SUSANA , YOSIPIV IGOR V. , MELEG-SMITH SUZANNE
Published: December 2017

El-Dahr, Samir S., Lisa M. Harrison-Bernard, Susana Dipp, Igor V. Yosipiv, and Suzanne Meleg-Smith. Bradykinin B2null mice are prone to renal dysplasia: gene-environment interactions in kidney development. Physiol Genomics 3: 121–131, 2000.—Congenital abnormalities of the kidney and urinary tract are a common cause of end-stage renal disease in children. Host and environment factors are implicated in the pathogenesis of aberrant renal development. However, direct evidence linking gene-environment interactions with congenital renal disease is lacking. We report an animal model of renal dysgenesis that is dependent on a defined genetic defect and specific embryonic stressor. Specifically, mice that are deficient in the bradykinin type 2 receptor gene ( B2) and salt loaded during embryogenesis acquire an aberrant kidney phenotype and die shortly after birth. In contrast, B2mutant mice maintained on normal sodium intake or salt-loaded wild-type mice do not develop kidney abnormalities. The kidney abnormality is evident histologically on embryonic day 16, shortly after the onset of metanephric B2gene expression, and consists of distorted renal architecture, foci of tubular dysgenesis, and cyst formation. The dysplastic tubules are of distal nephron origin [ Dolichos biflorus agglutinin (DBA)- and aquaporin-2 (AQP2) positive, and angiotensinogen negative]. Neonatal antihypertensive therapy fails to ameliorate the renal abnormalities, arguing against the possibility that the nephropathy is a consequence of early hypertension. Moreover, the nephropathy is intrinsic to the embryo, because B2homozygous offspring from heterozygous parents exhibit the same renal phenotype as offspring from homozygous null parents. Further characterization of the renal phenotype revealed an important genetic background effect since the penetrance of the congenital nephropathy is increased substantially upon backcrossing of 129/BL6 B2mutants to a uniform C57BL/6J. We conclude that the type 2 bradykinin receptor is required for the maintenance of metanephric structure and epithelial integrity in the presence of fetal stress. This study provides a “proof-of-principle” that defined gene-environment interactions are a cause of congenital renal disease.
Differential effects of dystrophin and utrophin gene transfer in immunocompetent muscular dystrophy (mdx) mice
Authors: EBIHARA SATORU , GUIBINGA GHIABE-HENRI , GILBERT RENALD , NALBANTOGLU JOSEPHINE , MASSIE BERNARD , KARPATI GEORGE , PETROF BASIL J.
Published: December 2017

Ebihara, Satoru, Ghiabe-Henri Guibinga, Renald Gilbert, Josephine Nalbantoglu, Bernard Massie, George Karpati, and Basil J. Petrof. Differential effects of dystrophin and utrophin gene transfer in immunocompetent muscular dystrophy (mdx) mice. Physiol Genomics 3: 133–144, 2000.—Duchenne muscular dystrophy (DMD) is a fatal disease caused by defects in the gene encoding dystrophin. Dystrophin is a cytoskeletal protein, which together with its associated protein complex, helps to protect the sarcolemma from mechanical stresses associated with muscle contraction. Gene therapy efforts aimed at supplying a normal dystrophin gene to DMD muscles could be hampered by host immune system recognition of dystrophin as a “foreign” protein. In contrast, a closely related protein called utrophin is not foreign to DMD patients and is able to compensate for dystrophin deficiency when overexpressed throughout development in transgenic mice. However, the issue of which of the two candidate molecules is superior for DMD therapy has remained an open question. In this study, dystrophin and utrophin gene transfer effects on dystrophic muscle function were directly compared in the murine (mdx) model of DMD using E1/E3-deleted adenovirus vectors containing either a dystrophin (AdV-Dys) or a utrophin (AdV-Utr) transgene. In immunologically immature neonatal animals, AdV-Dys and AdV-Utr improved tibialis anterior muscle histopathology, force-generating capacity, and the ability to resist injury caused by high-stress contractions to an equivalent degree. By contrast, only AdV-Utr was able to achieve significant improvement in force generation and the ability to resist stress-induced injury in the soleus muscle of immunocompetent mature mdx animals. In addition, in mature mdx mice, there was significantly greater transgene persistence and reduced inflammation with utrophin compared to dystrophin gene transfer. We conclude that dystrophin and utrophin are largely equivalent in their intrinsic abilities to prevent the development of muscle necrosis and weakness when expressed in neonatal mdx animals with an immature immune system. However, because immunity against dystrophin places an important limitation on the efficacy of dystrophin gene replacement in an immunocompetent mature host, the use of utrophin as an alternative to dystrophin gene transfer in this setting appears to offer a significant therapeutic advantage.