bluuebunny/crossref_metadata_2025 huggingface dataset:
Biopsy coupled to quantitative immunofluorescence: a new method to study the human vascular endothelium
Authors: Colombo Paolo C. , Ashton Anthony W. , Celaj Sulejman , Talreja Ashok , Banchs Javier E. , Dubois Nicholas B. , Marinaccio Massimo , Malla Shailesh , Lachmann Justine , Ware J. Anthony , Le Jemtel Thierry H.
Published: March 2015

Limited availability of endothelial tissue is a major constraint when investigating the cellular mechanisms of endothelial dysfunction in patients with metabolic and cardiovascular diseases. We propose a novel approach that combines collection of 200–1,000 endothelial cells from a superficial forearm vein or the radial artery, with reliable measurements of protein expression by quantitative immunofluorescence analysis. This method was validated against immunoblot analysis in cultured endothelial cells. Levels of vascular endothelial cell activation, oxidative stress, and nitric oxide synthase expression were measured and compared in five patients with severe chronic heart failure and in four healthy age-matched subjects. In summary, vascular endothelial biopsy coupled with measurement of protein expression by quantitative immunofluorescence analysis provides a novel approach to the study of the vascular endothelium in humans.
Role of extracellular HSP72 in acute stress-induced potentiation of innate immunity in active rats
Authors: Campisi J. , Fleshner M.
Published: March 2015

Acute stress can compromise acquired, and potentiate innate, immunity. Recent evidence suggests that the impact of stress on measures of immunity can be modulated by the physical activity status of the organism and that extracellular heat shock protein 72 (eHSP72) contributes to the activation of innate immunity produced by stress. Therefore, this study investigated whether physical activity status would impact the immunologically enhancing effects of stressor exposure [inescapable tail-shock stress (IS)] on innate immunity and whether changes in eHSP72 responses could play a role. Adult, male Fischer 344 rats lived with mobile (physically active) or immobile (sedentary) running wheels. After 6 wk, rats were exposed to IS or to no stress. Immediately after IS, all rats were injected subcutaneously with live Escherichia coli. Inflammation was assessed daily, and plasma eHSP72 was measured at various time points. Rats exposed to IS resolved their inflammation faster than nonstressed rats, but the beneficial impact of stress on recovery was greater in physically active rats. All rats had equal increases in circulating eHSP72 after IS. Splenocytes harvested from a separate cohort of nonstressed rats were cultured with eHSP72, and nitric oxide and cytokines were measured. Physically active rats responded to eHSP72 stimulation in vitro with a greater nitric oxide and cytokine response than sedentary rats. Thus physically active rats both recover faster than sedentary rats after bacterial challenge + IS exposure and demonstrate potentiated cellular responses to eHSP72 activation that could be important for bacterial recovery.
S1P induces FA remodeling in human pulmonary endothelial cells: role of Rac, GIT1, FAK, and paxillin
Authors: Shikata Yasushi , Birukov Konstantin G. , Garcia Joe G. N.
Published: March 2015

Sphingosine 1-phosphate (S1P) enhances human pulmonary endothelial monolayer integrity via Rac GTPase-dependent formation of a cortical actin ring (Garcia et al. J Clin Invest 108: 689–701, 2001). The mechanisms underlying this response are not well understood but may involve rapid redistribution of focal adhesions (FA) as attachment sites for actin filaments. We evaluate the effects of S1P on the redistribution of paxillin, FA kinase (FAK), and the G protein-coupled receptor kinase-interacting proteins (GITs). S1P induced Rac GTPase activation and cortical actin ring formation at physiological concentrations (0.5 μM), whereas 5 μM S1P caused prominent stress fiber formation and activation of Rho and Rac GTPases. S1P (0.5 μM) stimulated the tyrosine phosphorylation of FAK Y576, and paxillin was linked to FA disruption and redistribution to the cell periphery. Furthermore, S1P induced a transient association of GIT1 with paxillin and redistribution of the GIT2-paxillin complex to the cell cortical area without affecting GIT2-paxillin association. These results suggest a role of FA rearrangement in S1P-mediated barrier enhancement via Rac- and GIT-mediated processes.
Evaluation of inotropic changes in ventricular function by NOGA mapping: comparison with echocardiography
Authors: Lessick Jonathan , Hayam Gal , Zaretsky Asaph , Reisner Shimon A. , Schwartz Yitzhak , Ben-Haim Shlomo A.
Published: March 2015

Assessment of left ventricular (LV) function in the catheterization laboratory is important to optimize treatment decisions and guide catheter-based local therapies. NOGA electromechanical mapping was developed to assess LV contraction during catheterization; however, quantitative analysis of its “local shortening” (LS) algorithm and direct comparison with conventional methods are lacking. We evaluated the accuracy of NOGA-based regional and global function by examining its ability to detect pharmacologically induced changes in contractility compared with echocardiography. Ten anesthetized pigs were paced to ensure a constant heart rate throughout the experiment. Electromechanical maps of the LV and short-axis echocardiograms were obtained 1) at baseline, 2) during intravenous dobutamine, and 3) after intravenous propranolol. NOGA LS and ejection fraction (EF) consistently increased under dobutamine and decreased after propranolol. NOGA LS and NOGA and echocardiography circumferential shortening correlated highly with one another ( r > 0.80), as did NOGA EF with echocardiography EF ( r = 0.92), although absolute values differed somewhat. Thus NOGA-based global and regional function correlates closely with echocardiography and is sensitive to changes in contractility, but, at the upper end of the scale, LV function is underestimated.
Assessment of functional series elastic stiffness of human dorsiflexors with fast controlled releases
Authors: De Zee Mark , Voigt Michael
Published: March 2015

The series elastic stiffness (SES) of the human dorsiflexors was investigated in vivo with the fast controlled release method in 8 subjects. The maximum moment of a voluntary contraction (66 ± 17 Nm) was significantly higher than the maximum moment with electrical stimulation of tibialis anterior (34 ± 16 Nm). At an ankle moment of 34 Nm produced with either voluntary or electrical stimulation, we found a significantly different SES of 219 ± 54 and 149 ± 54 Nm · rad−1, respectively. It is proposed that this is due to the fact that, during voluntary contraction, more elastic tissue parallel with each other is involved, because of coactivation of the extensor hallucis longus, extensor digitorum longus, and tibialis anterior. This shows that, for a functional assessment of the SES of the dorsiflexors, one has to include the toe extensors, which is possible with the fast controlled release method. Additionally, our results demonstrated that the SES of the human dorsiflexors at moment levels up to about isometric maximum did not reach an asymptote at which the stiffness is independent of moment, i.e., the series elastic component of the dorsiflexors is during daily activities loaded for the greatest part in the nonlinear part of the stress-strain function.
Expression of the bilateral deficit during reflexively evoked contractions
Authors: Khodiguian N. , Cornwell A. , Lares E. , DiCaprio P. A. , Hawkins S. A.
Published: March 2015

During maximal contractions, the sum of forces exerted by homonymous muscles unilaterally is typically larger than the sum of forces exerted by the same muscles bilaterally. This phenomenon is known as the bilateral deficit (BLD), and it is suggested that this deficit is due to neural inhibition. It remains unclear, however, whether such inhibition is mediated by supraspinal mechanisms or by reflex pathways at the level of spinal cord. To further study the origin of likely neural influences, we tested for the presence of BLD under the condition of reflexive force generation. Force output and integrated electromyogram (iEMG) (quadriceps femoris) were measured in 17 male participants after initiation of the myotatic patellar reflex under unilateral and bilateral conditions. A significant BLD of 9.26 ± 1.19 ( P = 0.004) and 16.76 ± 4.69% ( P = 0.001) was found for force and iEMG, respectively. However, because similar findings were not evident during maximal isometric knee extensions, it is difficult to predict the contribution of a spinal mechanism to the BLD under the condition of maximal voluntary activation.
Chronic hyperbaric exposure activates proinflammatory mediators in humans
Authors: Ersson Anders , Walles Maria , Ohlsson Kjell , Ekholm Anders
Published: March 2015

Decompression illness (DCI) is an illness affecting divers subjected to reductions in ambient pressure. Besides a mechanical explanation to DCI, an inflammatory mechanism has been suggested. In this study, levels of interleukin (IL)-8, IL-6, IL-1 receptor antagonist (IL-1ra), secretory leukocyte protease inhibitor (SLPI), and neutrophil gelatinase-associated lipocalcin (NGAL) were measured in divers before and after a 2-mo period of daily diving. The divers were military conscripts and completed their diving period with no clinical symptoms of DCI. We found no change in IL-6 and IL1-ra but did find an increase in IL-8 and NGAL together with a decrease in SLPI levels. The findings suggest an inflammatory activation. This activation is not severe because no changes in IL-6 or IL-1ra were found. The increase in NGAL and IL-8 levels were interpreted as a sign of leukocyte activation. The decreased SLPI levels suggest an influence on the inflammatory defense mechanism. All in all, the findings of this study show a compensated activation of the inflammatory defense mechanism without loss of homeostasis of the inflammatory system.
Size and blood flow of central and peripheral arteries in highly trained able-bodied and disabled athletes
Authors: Huonker M. , Schmid A. , Schmidt-Trucksäß A. , Grathwohl D. , Keul J.
Published: March 2015

In a cross-sectional study, central and peripheral arteries were investigated noninvasively in high-performance athletes and in untrained subjects. The diastolic inner vessel diameter (D) of the thoracic and abdominal aorta, the subclavian artery (Sub), and common femoral artery (Fem) were determined by duplex sonography in 18 able-bodied professional tennis players, 34 able-bodied elite road cyclist athletes, 26 athletes with paraplegia, 17 below-knee amputated athletes, and 30 able-bodied, untrained subjects. The vessel cross-sectional areas (CSA) were set in relation to body surface area (BSA), and the cross-section index (CS-index = CSA/BSA) was calculated. Volumetric blood flow was determined in Sub and Fem via a pulsed-wave Doppler system and was set in relation to heart rate to calculate the stroke flow. A significantly increased D of Sub was found in the racket arm of able-bodied tennis players compared with the opposite arm (19%). Fem of able-bodied road cyclist athletes and of the intact limb in below-knee amputated athletes showed similar increases. D of Fem was lower in athletes with paraplegia (37%) and in below-knee amputated athletes proximal to the lesion (21%) compared with able-bodied, untrained subjects; CS-indexes were reduced 57 and 31%, respectively. Athletes with paraplegia demonstrated a larger D (19%) and a larger CS-index in Sub (54%) than able-bodied, untrained subjects. No significant differences in D and CS-indexes of the thoracic and abdominal aorta were found between any of the groups. The changes measured in Sub and Fem were associated with corresponding alterations in blood flow and stroke flow in all groups. The study suggests that the size and blood flow volume of the proximal limb arteries are adjusted to the metabolic needs of the corresponding extremity musculature and underscore the impact of exercise training or disuse on the structure and the function of the arterial system.
Invited Review: Neural network plasticity in respiratory control
Authors: Morris K. F. , Baekey D. M. , Nuding S. C. , Dick T. E. , Shannon R. , Lindsey B. G.
Published: March 2015

Respiratory network plasticity is a modification in respiratory control that persists longer than the stimuli that evoke it or that changes the behavior produced by the network. Different durations and patterns of hypoxia can induce different types of respiratory memories. Lateral pontine neurons are required for decreases in respiratory frequency that follow brief hypoxia. Changes in synchrony and firing rates of ventrolateral and midline medullary neurons may contribute to the long-term facilitation of breathing after brief intermittent hypoxia. Long-term changes in central respiratory motor control may occur after spinal cord injury, and the brain stem network implicated in the production of the respiratory rhythm could be reconfigured to produce the cough motor pattern. Preliminary analysis suggests that elements of brain stem respiratory neural networks respond differently to hypoxia and hypercapnia and interact with areas involved in cardiovascular control. Plasticity or alterations in these networks may contribute to the chronic upregulation of sympathetic nerve activity and hypertension in sleep apnea syndrome and may also be involved in sudden infant death syndrome.
Nonlinear summation of force in cat tibialis anterior: a muscle with intrafascicularly terminating fibers
Authors: Sandercock Thomas G.
Published: March 2015

The complex connective tissue structure of muscle and tendon suggests that forces from two parts of a muscle may not summate linearly, particularly in muscles with intrafasciculary terminating fibers, such as cat tibialis anterior (TA). In four anesthetized cats, the TA was attached to a servomechanism to control muscle length and record force. The ventral roots were divided into two bundles, each innervating about half the TA, so the two parts could be stimulated alone or together. Nonlinear summation of force ( Fnl) was measured during isometric contractions. Fnlwas small and negative, indicating less than linear summation of the parts, which is consistent with the predicted Fnlof muscle fibers connected in series. Fnlwas more significant when smaller parts of the muscle were tested (21.8 vs. 8% for whole muscle). These data were fit to a model where both parts of the muscle were assumed to stretch a common elasticity. Compensatory movements of the servomechanism showed the common elasticity is very stiff, and the model cannot account for Fnlin cat TA.
Nasal contribution to breathing with exercise: effect of race and gender
Authors: Bennett William D. , Zeman Kirby L. , Jarabek Annie M.
Published: March 2015

Because the nose acts as a filter to prevent penetration of toxic particles and gases to the lower respiratory tract, the route of breathing, oral vs. nasal, may be an important determinant of toxicant dose to the lungs. Using respiratory inductance plethysmography and a nasal mask fitted with flowmeter, we measured the nasal contribution to breathing at rest and during exercise (to 60% maximum workload) in healthy young adults (men/women = 11/11 and Caucasian/African-American = 11/11). We found that the nasal contribution to breathing is less during submaximal exercise in the Caucasians vs. African-Americans (e.g., at 60% maximum workload, mean nasal-to-total ventilation ratio = 0.40 ± 0.21 and 0.65 ± 0.24, respectively, P < 0.05). This difference is likely due to the African-Americans' ability to achieve higher maximal inspiratory flows through their nose than the Caucasians. Men also had a lesser nasal contribution to breathing during exercise compared with women. This is likely due to greater minute ventilations at any given percentage of maximum workload in men vs. women.
Ascent rate, age, maximal oxygen uptake, adiposity, and circulating venous bubbles after diving
Authors: Carturan D. , Boussuges A. , Vanuxem P. , Bar-Hen A. , Burnet H. , Gardette B.
Published: March 2015

Decompression sickness in diving is recognized as a multifactorial phenomenon, depending on several factors, such as decompression rate and individual susceptibility. The Doppler ultrasonic detection of circulating venous bubbles after diving is considered a useful index for the safety of decompression because of the relationship between bubbles and decompression sickness risk. The aim of this study was to assess the effects of ascent rate, age, maximal oxygen uptake (V˙o 2 max), and percent body fat on the production of bubbles after diving. Fifty male recreational divers performed two dives at 35 m during 25 min and then ascended in one case at 9 m/min and in the other case at 17 m/min. They performed the same decompression stops in the two cases. Twenty-eight divers were Doppler monitored at 10-min intervals, until 60 min after surfacing, and the data were analyzed by Wilcoxon signed-rank test to compare the effect of ascent rate on the kinetics of bubbles. Twenty-two divers were monitored 60 min after surfacing. The effect on bubble production 60 min after surfacing of the four variables was studied in 47 divers. The data were analyzed by multinomial log-linear model. The analysis showed that the 17 m/min ascent produced more elevated grades of bubbles than the 9 m/min ascent ( P < 0.05), except at the 40-min interval, and showed relationships between grades of bubbles and ascent rate and age and interaction terms betweenV˙o 2 max and age, as well asV˙o 2 max and percent body fat. Younger, slimmer, or aerobically fitter divers produced fewer bubbles compared with older, fatter, or poorly physically fit divers. These findings and the conclusions of previous studies performed on animals and humans led us to support that ascent rate, age, aerobic fitness, and adiposity are factors of susceptibility for bubble formation after diving.
Factors influencing body composition in persons with spinal cord injury: a cross-sectional study
Authors: Spungen Ann M. , Adkins Rodney H. , Stewart Charles A. , Wang Jack , Pierson Richard N. , Waters Robert L. , Bauman William A.
Published: March 2015

To determine the body composition differences across age, 133 men with chronic spinal cord injury (SCI) (66 with tetraplegia, 67 with paraplegia) were compared with an age-, height-, and ethnicity-matched able-bodied male reference population ( n = 100) using two different dual-energy X-ray absorptiometry densitometers. The effects of duration of injury, level, and completeness of lesion were analyzed in the SCI population. Independent of age, total body and regional lean mass were lower and fat mass was higher in persons with SCI compared with controls. The SCI group was 13 ± 1% (means ± SE) fatter per unit of body mass index (kg/m2) compared with the control group ( P < 0.0001). Advancing age was strongly associated with less lean mass and greater adiposity in those with SCI, whereas it was mildly related in the controls. Total body and regional arm and trunk, but not leg, lean tissues were lower in subjects with SCI, across all ages, than in the controls. In summary, persons with SCI were fatter for any body mass index and demonstrated significantly less lean and more adipose tissues for any given age compared with controls.
Muscle oxygen extraction and perfusion heterogeneity during continuous and intermittent static exercise
Authors: Kalliokoski Kari K. , Laaksonen Marko S. , Takala Teemu O. , Knuuti Juhani , Nuutila Pirjo
Published: March 2015

The purpose of this study was to compare the effects of intermittent and continuous static exercise on muscle perfusion, perfusion heterogeneity, and oxygen extraction. Perfusion and oxygen uptake of quadriceps femoris muscle were measured in 10 healthy men by using positron emission tomography and [15O]H2O and [15O]O2 first during intermittent static exercise [10% of maximal static force (MSF)] and thereafter during continuous static exercise at the same tension-time level (5% static; 5% of MSF). In 4 of these subjects, perfusion was measured during continuous static exercise with 10% of MSF (10% continuous) instead of the second [15O]O2 measurement. Muscle oxygen consumption was similar during intermittent and 5% continuous, but muscle perfusion was significantly higher during 5% continuous. Consequently, muscle oxygen extraction fraction was lower during 5% continuous. Perfusion was also more heterogeneous during 5% continuous. When exercise intensity was doubled during continuous static exercise (from 5% continuous to 10% continuous), muscle perfusion increased markedly. These results suggest that continuous, low-intensity static exercise decreases muscle oxygen extraction and increases muscle perfusion and its heterogeneity compared with intermittent static exercise at the same relative exercise intensity.
Smaller muscle ATP reduction in women than in men by repeated bouts of sprint exercise
Authors: Esbjörnsson-Liljedahl Mona , Bodin Kristina , Jansson Eva
Published: March 2015

It was hypothesized that the reduction of high-energy phosphates in muscle after repeated sprints is smaller in women than in men. Fifteen healthy and physically active women and men with an average age of 25 yr (range of 19–42 yr) performed three 30-s cycle sprints (Wingate test) with 20 min of rest between sprints. Repeated blood and muscle samples were obtained. Freeze-dried pooled muscle fibers of types I and II were analyzed for high-energy phosphates and their breakdown products and for glycogen. Accumulation of plasma ATP breakdown products, plasma catecholamines, and blood lactate, as well as glycogen reduction in type I fibers, was all lower in women than in men during sprint exercise. Repeated sprints induced smaller reduction of ATP and smaller accumulation of IMP and inosine in women than in men in type II muscle fibers, with no gender differences in changes of ATP and its breakdown products during the bouts of exercise themselves. This indicates that the smaller ATP reduction in women than in men during repeated sprints was created during recovery periods between the sprint exercises and that women possess a faster recovery of ATP via reamination of IMP during these recovery periods.
Antioxidants attenuate the plasma cytokine response to exercise in humans
Authors: Vassilakopoulos Theodoros , Karatza Maria-Helena , Katsaounou Paraskevi , Kollintza Androniki , Zakynthinos Spyros , Roussos Charis
Published: March 2015

Exercise increases plasma TNF-α, IL-1β, and IL-6, yet the stimuli and sources of TNF-α and IL-1β remain largely unknown. We tested the role of oxidative stress and the potential contribution of monocytes in this cytokine (especially IL-1β) response in previously untrained individuals. Six healthy nonathletes performed two 45-min bicycle exercise sessions at 70% ofV˙o2 maxbefore and after a combination of antioxidants (vitamins E, A, and C for 60 days; allopurinol for 15 days; and N-acetylcysteine for 3 days). Blood was drawn at baseline, end-exercise, and 30 and 120 min postexercise. Plasma cytokines were determined by ELISA and monocyte intracellular cytokine level by flow cytometry. Before antioxidants, TNF-α increased by 60%, IL-1β by threefold, and IL-6 by sixfold secondary to exercise ( P < 0.05). After antioxidants, plasma IL-1β became undetectable, the TNF-α response to exercise was abolished, and the IL-6 response was significantly blunted ( P < 0.05). Exercise did not increase the percentage of monocytes producing the cytokines or their mean fluorescence intensity. We conclude that in untrained humans oxidative stress is a major stimulus for exercise-induced cytokine production and that monocytes play no role in this process.
Capillary supply of the tibialis anterior muscle in young, healthy, and moderately active men and women
Authors: Porter M. M. , Stuart S. , Boij M. , Lexell J.
Published: March 2015

Tibialis anterior muscle biopsies from moderately active men and women (21–30 yr; n= 30) were examined to determine potential gender differences in capillarization. The fiber type proportions [type I (T1) ∼73%] were unaffected by gender. The men (M) had significantly ( P < 0.001) larger fibers than the women (W), with a greater gender effect for type II (T2) fibers ( P < 0.001). The M and W had similar capillary densities (CD ∼390 capillaries/mm2), but the capillaries-to-fiber ratio (C/F) was higher in the M (M = 2.20 ± 0.35, W = 1.66 ± 0.32; P < 0.01). Capillary contacts (CC) were higher in T2 than T1 for the M ( P < 0.01), but not W, and M had greater CC ( P < 0.001). Both fiber area per capillary (FA/C) and fiber perimeter per capillary (FP/C) indicated that T1 fibers had greater capillarization than T2 fibers ( P < 0.001). There were no gender differences in T1 FA/C and T2 FA/C or T1 FP/C, but a gender difference existed for T2 FP/C (M = 60.5 ± 10.9, W = 70.6 ± 13.4; P < 0.01). The gender difference for C/F could be explained by fiber size; however, the physiological implications of the difference in T2 FP/C remains to be determined. In conclusion, despite gender differences for fiber size, overall, capillarization was similar between the men and women.
Colchicine attenuates left ventricular hypertrophy but preserves cardiac function of aortic-constricted rats
Authors: Scopacasa Beatriz S. , Teixeira Vicente P. A. , Franchini Kleber G.
Published: March 2015

To investigate the effects of colchicine on left ventricular (LV) function and hypertrophy (LVH) of rats subjected to constriction of transverse aorta (TAoC), we evaluated SO (sham operated, vehicle; n = 25), SO-T (sham operated, colchicine 0.4 mg/kg body wt ip daily; n = 38), TAoC (vehicle; n = 37), and TAoC-T (TAoC, colchicine; n = 34) on the 2nd, 6th, and 15th day after surgery. Colchicine attenuated LVH of TAoC-T compared with TAoC rats, as evaluated by ratio between LV mass (LVM) and right ventricular mass, LV wall thickness, and average diameter of cardiac myocytes. Systolic gradient across TAoC (∼45 mmHg), LV systolic pressure, LV end-diastolic pressure, and rate of LV pressure increase (+dP/d t) were comparable in TAoC-T and TAoC rats. However, the baseline and increases of LV systolic pressure-to-LVM and +dP/d t-to-LVMratios induced by phenylephrine infusion were greater in TAoC-T and SO-T compared with SO rats. Baseline and increases of +dP/d t-to-LVM ratio were reduced in TAoC compared with SO rats. TAoC rats increased polymerized fraction of tubulin compared with SO, SO-T, and TAoC-T rats. Our results indicate that colchicine treatment reduced LVH to pressure overload but preserved LV function.
Activation of the midbrain periaqueductal gray induces airway smooth muscle relaxation
Authors: Haxhiu Musa A. , Yamamoto Bryan K. , Dreshaj Ismail A. , Ferguson Donald G.
Published: March 2015

In this study, we examined effects of chemical stimulation of the ventrolateral region of the midbrain periaqueductal gray (vl PAG) on airway smooth muscle tone. We observed that in anesthetized, paralyzed, and artificially ventilated ferrets, vl PAG stimulation elicited airway smooth muscle relaxation. To clarify the mechanisms underlying this observation, we examined the GABA-GABAA receptor signaling pathway by 1) examining the expression of GABAA receptors on airway-related vagal preganglionic neurons (AVPNs) located in the rostral nucleus ambiguus region (rNA), by use of receptor immunochemistry and confocal microscopy; 2) measuring GABA release within the rNA by using microdialysis; and 3) performing physiological experiments to determine the effects of selective blockade of GABAA receptors expressed by AVPNs in the rNA region on vl PAG-induced airway relaxation, thereby defining the role of the GABAA receptor subtype in this process. We observed that AVPNs located in the rNA region do express the GABAA receptor β-subtype. In addition, we demonstrated that activation of vl PAG induced GABA release within the rNA region, and this release was associated with airway smooth muscle relaxation. Blockade of the GABAA receptor subtype expressed by AVPNs in the rNA by bicuculline diminished the inhibitory effects of vl PAG stimulation on airway smooth muscle tone. These data indicate, for the first time, that activation of vl PAG dilates the airways by a release of GABA and activation of GABAA receptors expressed by AVPNs.
Invited Review: Molecular genetic studies on sleep-wake regulation, with special emphasis on the prostaglandin D2system
Authors: Hayaishi Osamu
Published: March 2015

To elucidate the exact role of the PGD2system in sleep-wake regulation in vivo, the sleep behavior of knockout mice, generated in the author's and other laboratories, was examined for lipocalin-type PGD synthase (L-PGDS), PGD receptor, adenosine A2Areceptor, and histamine H1receptor; transgenic mice overexpressing the human L-PGDS gene, generated in the author's laboratory, were also examined. The circadian profiles of sleep patterns of wild-type and the genetically manipulated mice were essentially identical, indicating the possibility that the deficiency of one system may be effectively compensated by some other systems during development. Available evidence indicated that the PGD2system is involved in the homeostatic regulation of non-rapid eye movement sleep and that the arousal effect of orexin A is mediated by the histamine H1receptor system.
Chronic hypoxia alters the function of NOS nerves in cerebral arteries of near-term fetal and adult sheep
Authors: Mbaku Emmanuel M. , Zhang Lubo , Pearce William J. , Duckles Sue P. , Buchholz John
Published: March 2015

In addition to adrenergic innervation, cerebral arteries also contain neuronal nitric oxide synthase (nNOS)-expressing nerves that augment adrenergic nerve function. We examined the impact of development and chronic high-altitude hypoxia (3,820 m) on nNOS nerve function in near-term fetal and adult sheep middle cerebral arteries (MCA). Electrical stimulation-evoked release of norepinephrine (NE) was measured with HPLC and electrochemical detection, whereas nitric oxide (NO) release was measured by chemiluminescence. An inhibitor of NO synthase, N ω-nitro-l-arginine methyl ester (l-NAME), significantly inhibited stimulation-evoked NE release in MCA from normoxic fetal and adult sheep with no effect in MCA from hypoxic animals. Addition of the NO donor S-nitroso- N-acetyl-dl-penicillamine fully reversed the effect of l-NAME in MCA from normoxic animals with no effect in MCA from hypoxic animals. Electrical stimulation caused a significant increase in NO release in MCA from normoxic animals, an effect that was blocked by the neurotoxin tetrodotoxin, whereas there was no increase in NO release in MCA from hypoxic animals. Relative abundance of nNOS as measured by Western blot analysis was similar in normoxic fetal and adult MCA. However, after hypoxic acclimitization, nNOS levels dramatically declined in both fetal and adult MCA. These data suggest that the function of nNOS nerves declines during chronic high-altitude hypoxia, a functional change that may be related to a decline in nNOS protein levels.
Nonuniform strain of human soleus aponeurosis-tendon complex during submaximal voluntary contractions in vivo
Authors: Finni Taija , Hodgson John A. , Lai Alex M. , Edgerton V. Reggie , Sinha Shantanu
Published: March 2015

The distribution of strain along the soleus aponeurosis tendon was examined during voluntary contractions in vivo. Eight subjects performed cyclic isometric contractions (20 and 40% of maximal voluntary contraction). Displacement and strain in the apparent Achilles tendon and in the aponeurosis were calculated from cine phase-contrast magnetic resonance images acquired with a field of view of 32 cm. The apparent Achilles tendon lengthened 2.8 and 4.7% in 20 and 40% maximal voluntary contraction, respectively. The midregion of the aponeurosis, below the gastrocnemius insertion, lengthened 1.2 and 2.2%, but the distal aponeurosis shortened 2.1 and 2.5%, respectively. There was considerable variation in the three-dimensional anatomy of the aponeurosis and muscle-tendon junction. We suggest that the nonuniformity in aponeurosis strain within an individual was due to the presence of active and passive motor units along the length of the muscle, causing variable force along the measurement site. Force transmission along intrasoleus connective tissue may also be a significant source of nonuniform strain in the aponeurosis.
Increased surface tension decreases pulmonary capillary volume and compliance
Authors: Topulos George P. , Brown Richard E. , Butler James P.
Published: March 2015

Increased surface tension is an important component of several respiratory diseases, but its effects on pulmonary capillary mechanics are incompletely understood. We measured capillary volume and specific compliance before and after increasing surface tension with nebulized siloxane in excised dog lungs. The change in surface tension was sufficient to increase lung recoil 5 cmH2O at 50% total lung capacity. Increased surface tension decreased both capillary volume and specific compliance. The changes in capillary volume and compliance were greatest at the lung volumes at which the surface tension change was greatest. Near functional residual capacity, capillary volume postsiloxane was ∼30% of control. Presiloxane capillary specific compliance was ∼7%/cmH2O near functional residual capacity and ∼2.5%/cmH2O near total lung capacity. Postsiloxane capillary-specific compliance was 3%/cmH2O, and was independent of lung volume. We conclude that in addition to their well-known effects on lung mechanics, changes in surface tension also have important effects on capillary mechanics. We speculate that these changes may in turn affect ventilation and perfusion, worsen gas exchange, and alter leukocyte sequestration.
Modulations by dietary restriction on antioxidant enzymes and lipid peroxidation in developing mice
Authors: Wu Aiguo , Sun Xiufa , Wan Fada , Liu Yugu
Published: March 2015

The effects of dietary restriction (DR) on the activities of liver superoxide dismutase (SOD), catalase (Cat), and glutathione peroxidase (GPX) and the level of lipid peroxidation (LP) in developing mice were investigated in this study. Male and female Kunmin mice were fed a standard rodent diet ad libitum (AL), 80% of AL food intake (20% DR), or 65% of AL food intake (35% DR) for 12 or 24 wk. Both 12 and 24 wk of DR resulted in retarded body weight gain in male and female mice. The activities of SOD, Cat, and GPX and the content of LP in DR male and female mice were not different ( P > 0.05) from those in controls after 12 wk of DR. However, the SOD activity was increased at 24 wk in 20% DR ( P < 0.05) and 35% DR ( P < 0.01) male, but not in DR female, mice. The Cat activity was elevated at 24 wk in both DR male ( P < 0.05 for 20% DR, P < 0.01 for 35% DR) and female ( P < 0.01) mice with a greater increase in DR female ( P < 0.05) than in DR male animals. GPX activity was also increased at 24 wk in DR male ( P < 0.01) and female ( P < 0.01) mice with a greater elevation in DR females ( P < 0.05) than in DR males. Furthermore, LP was decreased at 24 wk in both DR male ( P < 0.01) and female ( P < 0.01) animals with a greater reduction in DR females ( P< 0.01) compared with DR males. These findings indicated that 24 wk, but not 12 wk, of DR led to differential effects on liver SOD, Cat, and GPX activities and LP content in male and female mice during development, suggesting sex-associated modulations of DR on antioxidant systems in developing animals.
Changes in [Ca2+]iinduced by several glucose transport-enhancing stimuli in rat epitrochlearis muscle
Authors: Terada Shin , Muraoka Isao , Tabata Izumi
Published: March 2015

The purpose of the present investigation was to establish a method for estimating intracellular Ca2+concentrations ([Ca2+]i) in isolated rat epitrochlearis muscles. Epitrochlearis muscles excised from 4-wk-old male Sprague-Dawley rats were loaded with a fluorescent Ca2+indicator, fura 2-AM, for 60–90 min at 35°C in oxygenated Krebs-Henseleit buffer. After fura 2 loading and subsequent 20-min incubation, the intensities of 500-nm fluorescence, induced by 340- and 380-nm excitation lights (Ftotal340 and Ftotal380), were measured. The fluorescences specific to fura-2 (Ffura 2340 and Ffura 2380) were calculated by subtracting the non-fura 2-specific component from Ftotal340 and Ftotal380, respectively. The ratio of Ffura 2340 to Ffura 2380 was calculated as R, and the change in the ratio from the baseline value (ΔR) was used as an index of the change in [Ca2+]i. In resting muscle, ΔR was stable for 60 min. Incubation for 20 min with caffeine (3–10 mM) significantly increased ΔR in a concentration-dependent manner. Incubation with hypoxic Krebs-Henseleit buffer for 10–60 min significantly elevated ΔR, depending on the duration of the incubation. Incubation with 50 μM N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide for 20 min significantly elevated ΔR ( P < 0.05). No significant increases in ΔR were observed during incubation for 20 min with 2 mM 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside or with 2 mU/ml insulin. These results demonstrated that, by using the fura 2-AM fluorescence method, the changes in [Ca2+]ican be monitored in the rat epitrochlearis muscle and suggest that the method can be utilized to observe quantitative information regarding [Ca2+]ithat may be involved in contraction- and hypoxia-stimulated glucose transport activity in skeletal muscle.
Extrajugular pathways of human cerebral venous blood drainage assessed by duplex ultrasound
Authors: Schreiber Stephan J. , Lürtzing Frank , Götze Rainer , Doepp Florian , Klingebiel Randolf , Valdueza José M.
Published: March 2015

Cerebral venous drainage in humans is thought to be ensured mainly via the internal jugular veins (IJVs). However, anatomic, angiographic, and ultrasound studies suggest that the vertebral venous system serves as an important alternative drainage route. We assessed venous blood volume flow in vertebral veins (VVs) and IJVs of 12 healthy volunteers using duplex ultrasound. Measurements were performed at rest and during a transient bilateral IJV and a circular neck compression. Total venous blood volume flow at rest was 766 ± 226 ml/min (IJVs: 720 ± 232, VVs: 47 ± 33 ml/min). During bilateral IJV compression, VV flow increased to 128 ± 64 ml/min. Circular neck compression, causing an additional deep cervical vein obstruction, led to a further rise in VV volume flow (186 ± 70 ml/min). As the observed flow increase did not compensate for IJV flow cessation, other parts of the vertebral venous system, like the intraspinal epidural veins and the deep cervical veins, have to be considered as additional alternative drainage pathways.
Cutaneous vasoconstrictor response to whole body skin cooling is altered by time of day
Authors: Aoki Ken , Stephens Dan P. , Saad Adham R. , Johnson John M.
Published: March 2015

To test for a diurnal difference in the vasoconstrictor control of the cutaneous circulation, we performed whole body skin cooling (water-perfused suits) at 0600 (AM) and 1600 (PM). After whole body skin temperature (Tsk) was controlled at 35°C for 10 min, it was progressively lowered to 32°C over 18–20 min. Skin blood flow (SkBF) was monitored by laser-Doppler flowmetry at three control sites and at a site that had been pretreated with bretylium by iontophoresis to block noradrenergic vasoconstriction. After whole body skin cooling, maximal cutaneous vascular conductance (CVC) was measured by locally warming the sites of SkBF measurement to 42°C for 30 min. Before whole body skin cooling, sublingual temperature (Tor) in the PM was significantly higher than that in the AM ( P < 0.05), but CVC, expressed as a percentage of maximal CVC (%CVCmax), was not statistically different between AM and PM. During whole body skin cooling, %CVCmax levels at bretylium-treated sites in AM or PM were not significantly reduced from baseline. In the PM, %CVCmax at control sites fell significantly at Tsk of 34.3 ± 0.01°C and lower ( P< 0.05). In contrast, in the AM %CVCmax at control sites was not significantly reduced from baseline until Tskreached 32.3 ± 0.01°C and lower ( P < 0.05). Furthermore, the decrease in %CVCmax in the PM was significantly greater than that in AM at Tsk of 33.3 ± 0.01°C and lower ( P < 0.05). Integrative analysis of the CVC response with respect to both Tor and Tsk showed that the cutaneous vasoconstrictor response was shifted to higher internal temperatures in the PM. These findings suggest that during whole body skin cooling the reflex control of the cutaneous vasoconstrictor system is shifted to a higher internal temperature in the PM. Furthermore, the slope of the relationship between CVC and Tsk is steeper in the PM compared with that in the AM.
Gene expression of adrenomedullin in failing myocardium: comparison to atrial natriuretic peptide
Authors: Bäumer Anselm T. , Schumann Christina , Cremers Bodo , Itter Gabi , Linz Wolfgang , Jockenhövel Friedrich , Böhm Michael
Published: March 2015

The expression of adrenomedullin (AM) and atrial natriuretic factor (ANF) were investigated in the myocardium of a rat model of chronic ischemic heart failure (CHF) compared with sham-operated controls. In addition, human myocardium of patients with end-stage heart failure due to idiopathic dilated cardiomyopathy compared with myocardium of normal subjects (NF) was studied. In CHF, similar AM levels but increased ANF expression were observed in left ventricular myocardium, as assessed by semiquantitative PCR. Functional experiments with freshly excised papillary muscles showed no influence of AM on myocardial contractility. In NF human myocardium, the expression of AM mRNA was threefold higher in atrial compared with ventricular tissue. In analogy, ANF mRNA was increased by ∼15-fold in atrial tissue. In dilated cardiomyopathy, the expression of AM was significantly increased in right and left ventricles compared with NF. In parallel, ventricular ANF expression was enhanced.
Granulocyte colony-stimulating factor enhances alpha-naphthylthiourea-induced pulmonary hypertension
Authors: Azoulay Élie , Eddahibi Saadia , Marcos Élisabeth , Levame Micheline , Harf Alain , Schlemmer Benoı̂t , Adnot Serge , Delclaux Christophe
Published: March 2015

Physiopathological discrepancies exist between the most widely used models of pulmonary hypertension (PH), namely monocrotaline- and hypoxia-induced PH. The development of a new model could help in the understanding of underlying mechanisms. Repeated alpha-naphthylthiourea (ANTU) injections (5 mg/kg weekly, 3 wk) induced pulmonary vascular remodeling, which was associated with development of PH and right ventricular hypertrophy. ANTU followed by granulocyte colony-stimulating factor (G-CSF; 25 μg · kg−1 · day−1subcutaneously, 3 days/wk) induced higher pulmonary arterial pressures and right ventricular hypertrophy than ANTU alone. Lidocaine, which inhibits neutrophil functions, inhibited PH exacerbation by G-CSF. Endothelial nitric oxide synthase expression, measured to assess ANTU-related endothelial toxicity, decreased significantly in ANTU-treated rats and fell even more sharply when G-CSF was given. This occurred despite a significant increase in vascular endothelial cell growth factor expression in lung and right ventricle in rats given ANTU alone and even more in rats given ANTU plus G-CSF. Repeated ANTU administration induces PH with vascular remodeling that can be further aggravated by the neutrophil activator G-CSF.
Hog barn dust extract stimulates IL-8 and IL-6 release in human bronchial epithelial cells via PKC activation
Authors: Romberger D. J. , Bodlak V. , Von Essen S. G. , Mathisen T. , Wyatt T. A.
Published: March 2015

Hog barn workers have an increased incidence of respiratory tract symptoms and demonstrate an increase in lung inflammatory mediators, including interleukin (IL)-8 and IL-6. Utilizing direct kinase assays for protein kinase C (PKC) activation, we demonstrated that dust from hog confinement facilities, or hog dust extract (HDE), augments PKC activity of human airway epithelial cells in vitro. A 5% dilution of HDE typically stimulates an approximately twofold increase in human bronchial epithelial cell (HBEC) PKC activity compared with control medium-treated cells. This increase in PKC is observed with 15 min of HDE treatment, and kinase activity reaches peak activity by 1–2 h of HDE treatment before returning to baseline PKC levels between 6 and 24 h. The classic PKC inhibitor, calphostin C, blocks HDE-stimulated PKC activity and associated IL-8 and IL-6 release. Desensitization to HDE stimulation of PKC activation does not appear to occur because subsequent exposures to HDE after an initial exposure result in further augmentation of PKC. Detoxification of HDE with polymyxin B to remove endotoxin did not change PKC activation or IL-8 release, suggesting that endotoxin is not solely responsible for HDE augmentation of PKC. These data support the hypothesis that HDE exposure augments HBEC IL-8 and IL-6 release via a PKC-dependent pathway.
Nitric oxide concentration increases in the cutaneous interstitial space during heat stress in humans
Authors: Kellogg D. L. , Zhao J. L. , Friel C. , Roman L. J.
Published: March 2015

To examine the role of nitric oxide (NO) in cutaneous active vasodilation, we measured the NO concentration from skin before and during whole body heat stress in nine healthy subjects. A forearm site was instrumented with a NO-selective, amperometric electrode and an adjacent intradermal microdialysis probe. Skin blood flow (SkBF) was monitored by laser-Doppler flowmetry (LDF). NO concentrations and LDF were measured in normothermia and heat stress. After heat stress, a solution of ACh was perfused through the microdialysis probe to pharmacologically generate NO and verify the electrode's function. During whole body warming, both SkBF and NO concentrations began to increase at the same internal temperature. Both SkBF and NO concentrations increased during heat stress (402 ± 76% change from LDF baseline, P < 0.05; 22 ± 5% change from NO baseline, P < 0.05). During a second baseline condition after heat stress, ACh perfusion led to increases in both SkBF and NO concentrations (496 ± 119% change from LDF baseline, P < 0.05; 16 ± 10% change from NO baseline, P < 0.05). We conclude that NO does increase in skin during heat stress in humans, attendant to active vasodilation. This result suggests that NO has a role beyond that of a permissive factor in the process; rather, NO may well be an effector of cutaneous vasodilation during heat stress.
Influence of hyperpnea on airway surface fluid volume and osmolarity in normal humans
Authors: Kotaru C. , Hejal Rana B. , Finigan J. H. , Coreno A. J. , Skowronski M. E. , Brianas L. J. , McFadden E. R.
Published: March 2015

To determine the effect of hyperpnea on the characteristics of periciliary liquid, we collected airway surface fluid (ASF) and measured its osmolarity in 11 normal people while they breathed dry, frigid air (−17 ± 1.2°C) at minute ventilations (V˙e) of 10, 40, and 80 l/min through a heat exchanger. The ASF was collected at the fifth tracheal ring by absorption onto filter paper pledgets inserted via fiber-optic bronchoscopy. Hyperpnea had no influence on the amount of ASF recovered (ASF volume at a V˙e of 10 l/min = 12.0 ± 2.0 μl; at 80 l/min = 8.8 ± 1.5 μl; P = 0.28) or its osmolarity (at a V˙e of 10, 40, and 80 l/min = 326 ± 15, 323 ± 11, and 337 ± 12 mosM, respectively; P = 0.65). These findings demonstrate that the tracheal mucosa of normal subjects does not desiccate during hyperpnea and that hypertonicity of the periciliary fluid does not develop even at high levels of ventilation.