bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid exchanges across the parietal peritoneal and pleural mesothelia
Authors: Negrini D. , del Fabbro M. , Venturoli D.
Published: December 2017

In 31 anesthetized rabbits, after removal of superficial tissues, glass micropipettes filled with 0.5 M NaCl solution and connected to an electrohydraulic servo-null system were used to measure extraperitoneal interstitial fluid pressure (Pi,per) and peritoneal liquid pressure (Pliq,per) at various heights. Linear regressions relating pressure to recording height (H) were Pi,per = 1.07 – 0.27H and Pliq,per = 0.9 – 0.64H, respectively. Protein concentration (Cp;g/dl) and colloid osmotic pressure (II; cmH2O) of plasma and of peritoneal and pleural liquids were 5.48 +/- 0.38 and 24.61 +/- 3.23, 3.07 +/- 0.5 and 13.29 +/- 1.87, and 1.76 +/- 0.42 and 8.45 +/- 2, respectively. The equation relating II to Cp was II = 4.64Cp + 0.0027Cp2. Tissue fluid samples were collected with saline-soaked wicks implanted in vivo or dry wicks inserted postmortem in extraperitoneal and extrapleural interstitial spaces. After 60 and 15 min, respectively, wicks were withdrawn and centrifuged; wick fluid was analyzed in colloid osmometer for small samples. Average extraperitoneal and extrapleural II values were 14.2 +/- 2.49 and 11.94 +/- 1.52 cmH2O, corresponding to Cp of 3.07 and 2.57 g/dl, respectively. The average net pressure gradient, assuming reflection coefficient and hydraulic conductivity (Negrini et al. J. Appl. Physiol. 69: 625–630, 1990; 71: 2543–2547, 1991), was 1.18 and 0.98 cmH2O for parietal peritoneal and pleural mesothelia, respectively, favoring filtration from the extraserosal interstitia into the serosal cavities. Total parietal peritoneal filtration was 1.49 ml.kg-1.h-1, approximately 15-fold higher than that for pleural mesothelium.
Lung retention of phosphatidylcholine and cholesterol from liposomes: effects of oxygen exposure and fasting
Authors: Smith L. J. , Anderson J.
Published: December 2017

Antioxidants such as glutathione may play a role in prevention and treatment of several lung diseases. Liposomes can be used to deliver antioxidants to the lung and increase their retention. In addition, liposomes alone may protect against oxidant-induced damage. In addition, liposomes alone may protect against oxidant-induced damage. This study was designed to characterize the retention and distribution of liposomes in the lung under normal circumstances and during either fasting, exposure to 100% oxygen, or a combination of the two. Positively charged liposomes, consisting of phosphatidylcholine (PC), cholesterol, and stearylamine plus either [14C]cholesterol or [3H]PC, were instilled intratracheally. Five minutes to 5 days later the lungs were removed and the radioactivity determined. Both [14C]cholesterol and [3H]PC labels had prolonged and equal retention in the lung, but their distribution within lung compartments differed. The cholesterol label increased in lung tissue over time, comprising 78% of the remaining label after 5 days, whereas the PC label persisted at high levels in lavage fluid and became equally distributed between lung tissue and bronchoalveolar lavage fluid. Fasting had little effect on the retention of the labels and no effect on their distribution within the lung. Exposure to 100% oxygen increased lung retention of both radiolabels and altered their distribution such that [14C]cholesterol label decreased and [3H]PC label increased in lung tissue. These results demonstrate the prolonged retention of intratracheally administered liposomes or their components in the lung and the effects of two clinically relevant conditions, fasting and hyperoxic exposure. Furthermore, they provide a basis for designing future studies using liposomes.
Influence of carbohydrate loading on fuel substrate turnover and oxidation during prolonged exercise
Authors: Bosch A. N. , Dennis S. C. , Noakes T. D.
Published: December 2017

This study compared liver glucose turnover, blood glucose oxidation, and muscle glycogen utilization in 15 male endurance-trained cyclists who rode for 180 min at 70% of maximal O2 consumption in either a carbohydrate-(CHO) loaded (CL) or a non-CHO-loaded (NL) state. Total CHO oxidation during exercise was similar in the CL and NL subjects (492 +/- 77 vs. 448 +/- 43 g, respectively), as were blood glucose oxidation (103 +/- 19 vs. 99 +/- 7 g, respectively) and liver glucose appearance (110 +/- 15 vs. 127 +/- 16 g, respectively). However, total muscle glycogen utilization was greater in CL than NL subjects (134 +/- 11 vs. 95 +/- 12 mmol/kg wet wt; P < 0.05), the former of which had higher muscle glycogen content at the start (194 +/- 4 vs. 124 +/- 7 mmol/kg wet wt; P < 0.05) and throughout the trial. Whereas high rates of muscle glycogen breakdown were maintained throughout the trial in CL subjects, rates of muscle glycogenolysis in NL subjects decreased to 26 mmol.kg wet wt-1.h-1 after 60 min of exercise (P < 0.05) when their muscle glycogen content had declined to 70 mmol/kg wet wt. Comparable rates of blood glucose and overall CHO oxidation in CL and NL subjects, despite a slowing of muscle glycogenolysis in the NL group, could be explained by an accelerated breakdown of glycogen in the nonworking muscles to redistribute CHO (lactate) to the working muscles for oxidation.(ABSTRACT TRUNCATED AT 250 WORDS)
Acid aspiration-induced acute lung injury causes leukocyte-dependent systemic organ injury
Authors: St John R. C. , Mizer L. A. , Kindt G. C. , Weisbrode S. E. , Moore S. A. , Dorinsky P. M.
Published: December 2017

The adult respiratory distress syndrome is a form of acute lung injury (ALI) that is frequently associated with systemic organ injury and often occurs in the setting of wide-spread inflammatory cell activation. However, whether conditions that lead to ALI result in systemic organ injury is unclear. This study was designed to test the hypothesis that ALI induced by acid aspiration will not result in systemic organ injury. Morphological alterations and lymph-to-plasma protein ratios were measured in autoperfused cat ileum preparations of four control animals and five animals with ALI produced by the endobronchial instillation of 0.1 N HCl (0.5 ml.kg-1.lung-1). After 2 h, the lymph-to-plasma protein ratio (a measure of microvascular permeability) was increased in the ilea of HCl-injured animals compared with control animals (0.234 +/- 0.03 vs. 0.121 +/- 0.005; P = 0.012) and was accompanied by extensive morphological alterations. Four additional HCl-injured animals were pretreated with an antileukocyte adherence antibody (anti-CD18, 2 mg/kg) that blocked the HCl-induced alterations in the ileum. This study provides evidence for significant systemic organ injury after acid aspiration-induced ALI and suggests that the neutrophil may be a key mediator.
NMR and analytic biochemical evaluation of CrP and nucleotides in the human calf during muscle contraction
Authors: Bangsbo J. , Johansen L. , Quistorff B. , Saltin B.
Published: December 2017

This study compared biochemical and 31P-nuclear magnetic resonance (NMR) determinations of energy metabolites during isometric contractions of the human calf muscle at various exercise intensities. Seven male subjects performed one-legged isometric contractions at a work load of 28, 64, and 90% of maximal voluntary contraction force (28-, 64-, and 90%-CON, respectively) for 3 min, 40 s, and 40 s, respectively, in a magnet and in an exact model of the magnet with an arrangement for rapid muscle biopsy sampling from the gastrocnemius. The decrease in phosphocreatine (CrP) determined by NMR was 20, 33, and 71% for 28%-, 64%-, and 90%-CON, respectively. These decreases were the same as those determined biochemically (25, 34, and 61%, respectively). Muscle CrP 1 min after 90%-CON was also found to be similar between NMR and biochemical determinations (88 and 74% of resting value, respectively). Although no significant change in muscle ATP was found by NMR, a decrease of 29% was observed biochemically at 90%-CON. The ratio between muscle CrP and ATP was the same between NMR and biochemical determinations except for 90%-CON (1.98 and 0.78, respectively). The increase in muscle ADP determined by NMR was two-, five-, and eightfold higher than that found biochemically for 28%-, 64%-, and 90%-CON, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
Muscle glucose uptake in the rat after suspension with single hindlimb weight bearing
Authors: Stump C. S. , Woodman C. R. , Fregosi R. F. , Tipton C. M.
Published: December 2017

This study was designed to examine the effect of non-weight-bearing conditions and the systemic influences of simulated microgravity on rat hindlimb muscles. For this purpose, rats were suspended (SUS) in a head-down position (45 degrees) with the left hindlimb non-weight bearing (NWB) and the right hindlimb bearing 20% of presuspension body mass (WB). Weight bearing by the SUS-WB limb was accomplished by using a platform connected to a rod in sleeve, cable, and pulley apparatus to which weight could be added. Rats (250–325 g) were assigned to SUS or cage control (CC) conditions for 14 days. The angle between the foot and leg for SUS-WB and CC remained similar (20–30 degrees) throughout the experiment while the SUS-NWB hindlimbs extended to approximately 140 degrees by day 12. On day 14, the soleus, plantaris, and gastrocnemius muscles from the SUS-NWB limbs exhibited significantly lower (P < or = 0.05) masses than presuspension mass values (29, 11, and 21%, respectively). Weight bearing by the SUS-WB limbs prevented the loss of mass by these muscles. In separate groups of SUS and CC rats, 2-deoxyglucose uptake during hindlimb perfusion was significantly higher in both SUS-NWB and SUS-WB hindlimbs at 24,000 microU/ml of insulin compared with CC for all the muscles examined (21–80%). In addition, extracellular space (ml/g) was significantly greater in the soleus muscles from both the SUS-NWB and SUS-WB hindlimbs (64%) compared with CC muscles.
Breath 13CO2 background enrichment during exercise: diet-related differences between Europe and America
Authors: Wagenmakers A. J. , Rehrer N. J. , Brouns F. , Saris W. H. , Halliday D.
Published: December 2017

A traditional North American diet contains a high percentage of carbohydrates (CHO) derived from C4 plants (maize, sugar cane), whereas a European diet contains primarily CHO derived from C3 plants (potato, sugar beet). The natural 13C enrichment of the first type of CHO is higher than that of the latter type. 13CO2 production from orally ingested C4 plant-derived CHO can, therefore, be used to quantify oxidation rates of orally ingested CHO at rest and during exercise. Recently it has been shown that oxidation rates assessed this way in North Americans should be corrected for an increase in breath background 13CO2 during exercise. We hypothesized that the indicated difference in metabolic origin of CHO would imply that no such correction is required for subjects on a European diet. We therefore studied changes from rest in breath 13CO2 enrichment in Dutch volunteers during cycle ergometry at 65% maximal work load (experiment 1, 2h, 6 subjects) and 70% maximal oxygen uptake (experiment 2, 90 min, 8 subjects) while ingesting water (experiments 1 and 2) and potato starch-derived glucose (experiment 2). Experiment 1 was done before and after careful instruction of the subjects to refrain from nutrient sources potentially containing CHO of C4 metabolic origin. No significant changes from rest 13CO2 enrichment were observed in tests with water and potato-derived glucose ingestion in subjects who excluded CHO of C4 metabolic origin from their diet.
Effects of insulin, glucose analogues, and pyruvate on vascular responses to anoxia in isolated ferret lungs
Authors: Wiener C. M. , Sylvester J. T.
Published: December 2017

In isolated ferret lungs, the vasopressor response to anoxia is characterized by an intense initial vasoconstriction, followed by marked vasodilation. This hypoxic pulmonary vasodilation (HPVD) is inhibited by perfusate glucose concentration > or = 15 mM. To determine whether this inhibition of HPVD was mediated by an effect of glucose transport or a product of glucose metabolism beyond pyruvate, we studied the effects of 5 mM glucose + insulin, transportable but nonmetabolizable analogues of glucose, and pyruvate on the pulmonary vascular response to anoxia. Isolated ferret lungs were ventilated with 28% O2 at constant flow. Perfusate glucose concentration was allowed to fall spontaneously. Thirty-minute anoxic exposures were performed at 60, 120, and 180 min of perfusion. Before the third anoxic exposure 15 mM glucose, 15 mM sucrose, 5 mM glucose (with 10 mM sucrose) + 10 mU/ml insulin, 15 mM 3-O-methylglucose (3-O-MG), or 15 mM alpha-methylglucose (alpha-MG) was added to the perfusate and vasomotor responses recorded. In another series of experiments, 15 mM pyruvate was added to the preparation at the beginning of perfusion. Peak vasoconstrictor responses were not different among groups. HPVD was greater in sucrose, insulin, 3-O-MG, alpha-MG, and pyruvate lungs than in high glucose lungs. These results suggest that glucose transport or a product of glucose metabolism beyond pyruvate was not responsible for inhibiting HPVD. We speculate that hyperglycemia inhibits HPVD by increasing production of ATP from the glycolytic pathway and that this ATP inhibits ATP-dependent K+ channels.
Nonlinear phenomena in respiratory mechanical measurements
Authors: Suki B.
Published: December 2017

The impact of nonlinearities on the assessment of respiratory mechanics was examined using a block-structured model (BSM) featuring both flow (V) and tidal volume (VT) nonlinearities. The model consists of an airway compartment (AC) in series with a tissue compartment (TC). The AC is a series connection of a resistance, an inertance, and a nonlinear V-dependent element. The TC is composed of a linear Kelvin body in cascade with a nonlinear polynomial system. Analytic results show that 1) the lack of VT dependence using sine waves does not mean that the system is linear and 2) the hysteresivity (J. J. Fredberg and D. Stamenovic. J. Appl. Physiol. 67:2408–2419, 1989) of a wide class of such tissue models is independent of VT, offering a simple mechanism for the coupling between resistance (R) and elastance (E). Furthermore, R from the step response of the TC was approximately 30% smaller than from sinusoids. Below 1 Hz, R and E of the BSM showed a negative VT dependence. Above 1 Hz, R increased with frequency and VT because of V dependence. Analysis of the response of the BSM to composite signals revealed how linear airway resistance can be overestimated because of V dependence and how tissue properties can be under-estimated because of harmonic distortion and cross talk induced by VT-associated nonlinearities.
Surface electromyogram power spectrum in human quadriceps muscle during incremental exercise
Authors: Gamet D. , Duchene J. , Garapon-Bar C. , Goubel F.
Published: December 2017

Spectral electromyographic (EMG) changes in human quadriceps muscles were studied to reinvestigate discrepant results concerning mean power frequency (MPF) changes during dynamic exercise. An incremental test consisting of a quasi-linear increase in mechanical power on a bicycle ergometer (for 20–100% of maximal aerobic power) was performed by forty subjects. During this test, surface EMGs from the quadriceps muscles showed that EMG total power (PEMG) increased with a curvilinear pattern for every subject, whereas MPF kinetics varied from one subject to another. PEMG changes had the same shape, which would lead to disappointing results in terms of discrimination between subjects. The ability of normalized MPF kinetics to define significant clusters of subjects was tested using a principal component analysis. This analysis led to the projection of all experiments onto a plane and revealed a relevant grouping of MPF profiles. Differences in MPF kinetics between clusters are interpreted in terms of various possibilities of balance between physiological events leading to an increase or a decrease in MPF.
Effect of aminophylline-Ca2+ blocker interaction on membrane potential of rat diaphragm fibers
Authors: Delbono O. , Kotsias B. A.
Published: December 2017

We studied the antagonism between aminophylline and two calcium channel blockers, nifedipine and verapamil, and its effect on the resting membrane potential of rat diaphragm fibers in vitro at 25 degrees C. Aminophylline hyperpolarizes the fibers in a dose-dependent manner, and the maximum effect is reached with 1 mM of the drug, approximately 9 mV compared with normal values. Both nifedipine and verapamil (1–5 microM) decreased the amount of hyperpolarization induced by aminophylline, and this is partially reversed when the xanthine concentration in the bath is increased. From the Hill equation we obtained a value of 2 for the slope, suggesting that two molecules of aminophylline bind to the receptor. Nifedipine modifies the affinity and the intrinsic activity of aminophylline, whereas verapamil reduces its intrinsic activity. The effect of nifedipine and verapamil is explained on the basis of the changed action of aminophylline on its site as a result of the interaction of the calcium channel blockers with their interdependent receptors.
Depletion of alveolar macrophages by liposome-encapsulated dichloromethylene diphosphonate
Authors: Berg J. T. , Lee S. T. , Thepen T. , Lee C. Y. , Tsan M. F.
Published: December 2017

Alveolar macrophages (AM) play an important role in lung biology. In this study, we demonstrated that tracheal insufflation of liposome-encapsulated dichloromethylene diphosphonate (Cl2MDP-liposome) selectively depleted AMs in rats. Insufflation of a single dose of Cl2MDP-liposomes (80 microliters containing 1.34 mumol of Cl2MDP) but not liposomes containing phosphate-buffered saline resulted in > 70% depletion of AMs starting within 1 day and lasting for > 5 days after insufflation. There was a slight but significant intraalveolar inflammatory response. Insufflation of Cl2MDP also resulted in depletion of AMs; however, it caused cytoplasmic edema of alveolar epithelial cells as well. Depletion of AMs by Cl2MDP-liposomes markedly reduced the endotoxin-induced neutrophil (polymorphonuclear lymphocyte) recruitment and the release of tumor necrosis factor into the alveolar space, suggesting that endotoxin-induced neutrophil recruitment and tumor necrosis factor release were dependent on AMs. This AM-depleted animal model will be useful for studying the in vivo functions of AMs and their role in various physiological and pathological conditions.
Responsiveness of and interactions between airways and tissue in guinea pigs during induced constriction
Authors: Nagase T. , Ito T. , Yanai M. , Martin J. G. , Ludwig M. S.
Published: December 2017

Mechanical interdependence between airways and tissues can modify the magnitude of induced bronchoconstriction. We questioned whether the guinea pig, an animal with abundant airway smooth muscle, would differ from other species in the relative responsiveness of and interactions between airways and tissues. Therefore we induced constriction with aerosolized methacholine (MCh) and partitioned responses into airway and tissue components. We measured tracheal and alveolar pressures using alveolar capsules in open-chest guinea pigs (n = 9) during mechanical ventilation [frequency = 1 Hz, tidal volume = 6 ml/kg, positive end-expiratory pressure (PEEP) = 5 cmH2O] and calculated the resistance of lung (RL), tissue (Rti), and airway (Raw) before and after administration of aerosols of MCh in progressively doubling concentrations (0.063–16 mg/ml). In separate animals (n = 10), measurements were made at 3–13 cmH2O PEEP. After aerosols of saline and MCh (0.125-32 mg/ml), measurements were repeated at 3, 7, and 11 cmH2O PEEP. At submaximal levels of constriction, the airways and lung tissues demonstrated similar responsiveness. Increasing PEEP increased RL and Rti and decreased Raw under baseline conditions. At low concentrations of MCh, increasing PEEP increased RL but decreased RL at the highest concentration. Increases in PEEP significantly increased Rti at all concentrations of MCh but decreased Raw only at 8 mg/ml of MCh. These observations demonstrate that, in guinea pigs, during submaximal constriction, airways and tissues behave similarly; moreover, airway-parenchymal interdependence is important in determining the level of bronchoconstriction.
Reflex cardiovascular effects of continuous prostacyclin administration into an isolated in situ lung in the dog
Authors: Allen D. A. , Schertel E. R. , Bailey J. E.
Published: December 2017

Bolus administration of prostacyclin (PGI2), an inflammatory product produced by the arachidonic acid cyclooxygenase pathway, into the pulmonary circulation is known to stimulate pulmonary C-fibers and to produce transient reflex cardiovascular depression. We used an isolated perfused in situ left lung preparation to examine the reflex cardiovascular effects of continuous administration of PGI2 into the isolated pulmonary circulation of dogs. PGI2 was infused for 30 min (5 micrograms.kg-1 x min-1) into the innervated isolated left pulmonary circulation in six dogs and into the denervated isolated circulation in seven dogs. Mean arterial pressure and cardiac output were significantly decreased from baseline values during the final 20 min of PGI2 infusion. There were no significant changes in maximum rate of change of left ventricular pressure during systole and in heart rate. All variables returned to baseline levels within 15 min of discontinuation of PGI2 infusion. PGI2 infusion produced no significant measured hemodynamic changes in the denervated group. Control experiments demonstrated that the observed response was not affected by duration of the preparation, lung denervation, or infusion vehicle. These findings suggest that continuous infusion of PGI2 into the isolated pulmonary circulation produces sustained cardiovascular depression via a vagal reflex mechanism that is probably mediated by pulmonary C-fibers.
Neuroendocrine and substrate responses to altered brain 5-HT activity during prolonged exercise to fatigue
Authors: Bailey S. P. , Davis J. M. , Ahlborn E. N.
Published: December 2017

Pharmacological manipulation of brain serotonergic [5-hydroxytryptamine (5-HT)] activity affects run time to exhaustion in the rat. These effects may be mediated by neurochemical, hormonal, or substrate mechanisms. Groups of rats were decapitated during rest, after 1 h of treadmill running (20 m/min, 5% grade), and at exhaustion. Immediately before exercise rats were injected intraperitoneally with 1 mg/kg of quipazine dimaleate (QD; a 5-HT agonist), 1.5 mg/kg of LY 53857 (LY; a 5-HT antagonist), or the vehicle (V; 0.9% saline). LY increased and QD decreased time to exhaustion (approximately 28 and 32%, respectively; P < 0.05). At fatigue, QD animals had greater plasma glucose, liver glycogen, and muscle glycogen concentrations but lower plasma free fatty acid concentration than did V and LY animals (P < 0.05). In general, plasma corticosterone and catecholamine levels during exercise in QD and LY rats were similar to those in V rats. Brain 5-HT and 5-hydroxyindole-3-acetic acid concentrations were higher at 1 h of exercise than at rest (P < 0.05), and the latter increased even further at fatigue in the midbrain and striatum (P < 0.05). Brain dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were higher at 1 h of exercise (P < 0.05) but were similar to resting levels at fatigue. QD appeared to block the increase in DA and DOPAC at 1 h of exercise, and LY prevented the decrease in DA and DOPAC at fatigue (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Oxidation of ethanol at rest and during prolonged exercise in men
Authors: Massicotte D. , Provencher S. , Adopo E. , Peronnet F. , Brisson G. , Hillaire-Marcel C.
Published: December 2017

The purpose of this study was to measure the oxidation of ethanol at rest and during prolonged moderate exercise with use of 13C labeling. Five healthy young males (22.4 +/- 2.7 yr; maximal O2 uptake = 56 +/- 6.6 ml.kg-1.min-1) performed three exercises (68.4 +/- 6.7% maximal O2 uptake; 90 min) on a cycle ergometer with ingestion of 0.4 (trial A) and 0.8 (trial B) g/kg body wt of [13C]ethanol (diluted in 770 +/- 72 ml of water) or water only (trial C). The subjects were also studied during a 90-min rest period after the ingestion of 0.8 g/kg body wt of [13C]ethanol (trial D). At rest, over the 90-min observation period, only 2.1 +/- 0.3 g of the 61.6 +/- 5.7 g of ethanol ingested were oxidized, providing 11.1 +/- 1.9% of the total energy expenditure. Over the 90 min of exercise, the amounts of ethanol oxidized were similar in trials A (9.5 +/- 2.0 g) and B (8.5 +/- 2.5 g). The contribution of ethanol represented 5.2 +/- 1.0% of the total energy expenditure, which is much lower than that previously reported for exogenous carbohydrates (8–18%) or medium-chain free fatty acids (7–14%). The small contribution of ethanol to energy metabolism did not significantly modify endogenous substrate oxidation.
Partitioning of pulmonary impedance: modeling vs. alveolar capsule approach
Authors: Petak F. , Hantos Z. , Adamicza A. , Daroczy B.
Published: December 2017

Pulmonary input impedance (ZL), transfer tissue impedances (Ztti), and transfer airway impedances (Ztaw) were measured in open-chest dogs and isolated canine lungs by means of small-amplitude pseudorandom oscillations between 0.2 and 21.1 Hz. In the determination of Ztti and Ztaw, local alveolar pressures (PA) sensed in alveolar capsules were used. The global impedances of the airways (Zaw) and tissues (Zti) were estimated by fitting to the ZL data between 0.2 and 4.9 Hz (open-chest dogs) and between 0.2 and 5.9 Hz (isolated lungs) two models based on Hildebrandt's formulations (Bull. Math. Biophys. 31: 651–667, 1969), the parameters of which included airway resistance (Raw) and inertance (Iaw) and tissue damping (GL) and elastance (HL). The tissue parameters of Ztti (Gti and Hti) were also obtained from model fitting, whereas the Ztaw data were evaluated in terms of resistance (Rtaw) and inertance (Itaw). Excellent agreement was found between HL and Hti in both experimental groups and between GL and Gti in the isolated lungs (r > or = 0.999). The damping coefficients were also closely related in the open-chest dogs (r = 0.95), but Gti overestimated GL slightly (by 9%). Raw was underestimated by Rtaw (by 3–33%) and Iaw by Itaw (by 2–16%), depending on the model type and, in the excised lungs, the number of punctures in the capsules. In the case of the airway parameters, the systematic differences were accompanied by lower r values (0.535–0.935), which are explained primarily by the regional variations in PA.(ABSTRACT TRUNCATED AT 250 WORDS)
Lung volume changes during relatively fluent speech in stutterers
Authors: Johnston S. J. , Watkin K. L. , Macklem P. T.
Published: December 2017

We investigated breathing patterns in stutterers during relatively fluent speech and compared these with normal subjects for similar speech tasks. Rib cage and abdominal displacements and esophageal, gastric, and transdiaphragmatic pressures provided indexes of diaphragmatic, rib cage, and abdominal muscle contraction. We found that stutterers spoke either at substantially higher or lower lung volumes than normal subjects, confining their speech to the inspiratory capacity or expiratory reserve volume. During spontaneous speech, stutterers did not cross functional residual capacity (FRC) for most breaths. In addition, stutterers used several different motion pathways from breath to breath. At high lung volumes stutterers used the diaphragm to provide inspiratory braking. At lung volumes below FRC stutterers recruited their abdominals. This contrasted with normal subjects who spoke in the middle part of the vital capacity and who recruited inspiratory and expiratory rib cage muscles above and below FRC, respectively. Breath sizes were log-normally distributed in stutterers compared with a gaussian distribution in normal subjects (P < 0.001). During reading, stutterers tended to cross FRC (P < 0.01), used very similar initiation lung volumes from breath to breath (P < 0.001), and used similar motion pathways to achieve deflation. We conclude that stutterers sustain fluency by speaking at abnormally high or low lung volumes and that this may account for the different muscle patterns observed in stutterers compared with normal subjects.
Exercise and glucocorticoid-induced diaphragmatic myopathy
Authors: Lieu F. K. , Powers S. K. , Herb R. A. , Criswell D. , Martin D. , Wood C. , Stainsby W. , Chen C. L.
Published: December 2017

We tested the hypothesis that a chronically active muscle, such as the rat diaphragm, would be more resistant to glucocorticoid-induced myopathy than a less active locomotor skeletal muscle (plantaris). Furthermore, we sought to determine whether endurance exercise could antagonize the glucocorticoid-induced atrophy in the diaphragm. Rats were assigned to one of seven experimental groups (n = 10 per group) and injected daily over a 10-day period with either a sham solution or prednisolone acetate: group 1: control; sedentary and sham injected; group 2: control; exercise trained and sham injected; group 3; sedentary; prednisolone (0.5 mg.kg-1 x day-1); group 4: sedentary; prednisolone (1.0 mg.kg-1 x day-1); group 5: sedentary; prednisolone (2.0 mg.kg-1 x day-1); group 6: sedentary; prednisolone (5.0 mg.kg-1 x day-1); group 7: exercise trained; prednisolone (5.0 mg.kg-1 x day-1). Slope differences in the dose-response curves suggest that prednisolone-induced muscle atrophy in the plantaris was more severe than that in the diaphragm. Furthermore, high doses of prednisolone resulted in a differential effect on muscle bioenergetic enzyme activities in the plantaris and diaphragm. Prednisolone treatment (> or = 2 mg.kg-1 x day-1) resulted in a significant reduction in phosphofructokinase activity (expressed as microM substrate.min-1 x mg protein-1) and an increase in 3-hydroxyacyl-CoA dehydrogenase activity in the plantaris muscle. In contrast, prednisolone treatment did not influence phosphofructokinase activity (P > 0.05) in the diaphragm but decreased (P < 0.05) relative citrate synthase activity. Finally, 90 min daily of endurance exercise did not antagonize prednisolone-induced myopathy in either the diaphragm or the plantaris.
Imaging the ovine heparin-protamine interaction with 111In-protamine
Authors: Montalescot G. , Fischman A. J. , Strauss H. W. , Wilkinson R. A. , Ahmad M. , Fitzgibbon C. , Robinson D. W. , Zapol W. M.
Published: December 2017

Protamine reversal of heparin anticoagulation occasionally induces the release of thromboxane into plasma with catastrophic pulmonary hypertension. To examine the site of neutralization, we labeled protamine sulfate with 111In and compared activity scans after administration of labeled protamine in unheparinized and heparin-anticoagulated sheep. Protamine administration in sheep without prior heparinization did not cause thromboxane release, pulmonary hypertension, or significant leukopenia, and 111In-protamine was rapidly cleared from the lungs (half time 0.48 +/- 0.08 min). Neutralization of heparin anticoagulation by labeled protamine produced elevated plasma thromboxane, pulmonary vasoconstriction, leukopenia, and prolonged pulmonary clearance of 111In-protamine (half time 3.32 +/- 0.43 min). In rats, protamine reversal of heparin anticoagulation did not induce either thromboxane synthesis or pulmonary hypertension, and 111In-protamine cleared rapidly from the lungs. Thus the ovine heparin-protamine reaction produces concomitant pulmonary sequestration of heparin-protamine complexes, thromboxane release, and pulmonary vasoconstriction; this did not occur in the rat. The lung specificity of the reaction and interspecies differences suggest that ovine pulmonary intravascular macrophages may be activated by heparin-protamine complexes to release thromboxane and provoke acute pulmonary vasoconstriction.
Effect of catheter flow direction on CO2 removal during tracheal gas insufflation in dogs
Authors: Nahum A. , Ravenscraft S. A. , Nakos G. , Adams A. B. , Burke W. C. , Marini J. J.
Published: December 2017

Tracheal gas insufflation (TGI) improves the efficiency of CO2 elimination by replacing CO2 in the anatomic dead space proximal to the catheter tip with fresh gas during expiration. Turbulence generated by gas exiting the catheter tip may also contribute to alveolar ventilation. To separate distal (turbulence-related) and proximal (washout of dead space) effects of TGI, we compared the efficacy of a straight and an inverted catheter during continuous and expiratory TGI in six mechanically ventilated dogs. We reasoned that the inverted catheter cannot improve CO2 elimination from more distal conducting airways. During continuous TGI with the straight catheter, arterial PCO2 (PaCO2) decreased significantly from baseline (without TGI) of 56 +/- 10 Torr to 38 +/- 8, 36 +/- 8, and 35 +/- 8 Torr at catheter flow rates (Vcath) of 5, 10, and 15 l/min, respectively. For the same conditions, PaCO2 was always higher (P < 0.001) with the inverted catheter (42 +/- 10, 41 +/- 10, and 41 +/- 10 Torr). PaCO2 was lower with the straight (40 +/- 9 Torr) than with the inverted catheter (44 +/- 10 Torr, P < 0.001) during TGI delivered only during expiration at a Vcath of 10 l/min. End-expiratory lung volume relative to baseline increased during continuous, but not during expiratory, TGI and was significantly greater with the straight than with the inverted catheter (P < 0.0001). Our data confirm that the primary mechanism of TGI is expiratory washout of the proximal anatomic dead space but also suggest a minor contribution of turbulence beyond the tip of the straight catheter.
Effect of asthma and ventilatory loading on arterial PCO2 of humans during submaximal exercise
Authors: Forster H. V. , Dunning M. B. , Lowry T. F. , Erickson B. K. , Forster M. A. , Pan L. G. , Brice A. G. , Effros R. M.
Published: December 2017

In humans, attenuating carotid chemoreceptor activity by hyperoxia does not alter arterial PCO2 (PaCO2) during submaximal exercise, yet a transient hypercapnia occurs in carotid chemoreceptor-resected (CBR) asthmatic subjects during submaximal exercise. We hypothesized that this difference was due to asthma and not CBR causing the abnormal response. Accordingly, we determined the temporal pattern of PaCO2 during mild and moderate exercise in chemoreceptor-intact asthmatic (n = 10) and nonasthmatic subjects (n = 10). We also hypothesized that hyperoxia alters PaCO2 during exercise if exercise already has disrupted PaCO2 homeostasis. Accordingly, we studied, during exercise, asthmatic subjects while hyperoxic; nonasthmatic subjects during loaded breathing of room air, which increased PaCO2; and nonasthmatic subjects during loaded breathing while hyperoxic. While breathing room air, neither asthmatic nor nonasthmatic subjects maintained arterial isocapnia during exercise. An increase in PaCO2 between rest and exercise and between mild exercise and 1st min of moderate exercise was greater in asthmatic than in nonasthmatic subjects (P < 0.05). In six asthmatic subjects that were hypercapnic breathing room air during exercise, hypercapnia was accentuated by hyperoxia. The ventilatory load in nonasthmatic subjects resulted in a work load-dependent hypercapnia (P < 0.01) accentuated (P < 0.01) by hyperoxia. We conclude that normally in humans the carotid chemoreceptors contribute minimally to the hyperpnea of submaximal exercise. However, when PaCO2 is increased from resting values during exercise, then the chemoreceptors serve to augment ventilation and thereby minimize the hypercapnia.
Effect of isoproterenol on peripheral airway pressure-diameter behavior
Authors: Olson L. E.
Published: December 2017

I radiographically evaluated the pressure-diameter relationships of peripheral airways (average diameter approximately 2 mm at total lung capacity) in a collaterally ventilating lung segment in 22 caudal dog lung lobes. Eleven lobes were studied when freshly excised, and 11 lobes were studied after being rinsed with 0.5% isoproterenol. Airways within the segment (intrasegmental) and a control region of similarly sized airways external to the segment were studied. Radiographs were taken when airway opening pressure (Pao) equaled pressure in the segment (Ps) (homogeneous case) and when Pao was 5, 10, or 15 cmH2O greater than Ps (nonhomogeneous case). Airway diameter was calculated as a fraction of the diameter at Pao = Ps = 25 cmH2O. The response of intrasegmental airways to increases in pressure in the homogeneous case (Ps = Pao) and nonhomogeneous case (Ps > Pao) differed between freshly excised and isoproterenol-rinsed lobes. I conclude that dilating peripheral airways by decreasing bronchomotor tone limits the extent to which they can respond to a regional increase in alveolar pressure.
O2 uptake kinetics above and below the lactic acidosis threshold during sinusoidal exercise
Authors: Haouzi P. , Fukuba Y. , Casaburi R. , Stringer W. , Wasserman K.
Published: December 2017

O2 uptake (VO2) kinetics at the onset of a constant work rate exercise are difficult to describe for work rates above the lactic acidosis threshold (LAT), because the steady-state level of VO2 response can usually not be identified. To describe the ability of the O2 transport system to deliver and the cells to utilize O2 above the LAT relative to that below the LAT, we applied a fluctuating (sinusoidal) variation of work rate. After 4 min of constant work at the midpoint of the sinusoidal work rate, a fluctuating work rate, at a period of 4 min, was applied below the LAT for the next 16 min. This was repeated in a range of work rates above the LAT with the same sine-wave amplitude. VO2 response appeared to follow a sinusoidal pattern similar to that of work rate for below- and above-LAT exercise. However, the amplitude of the VO2 response was significantly reduced (5.4 +/- 2.6 vs. 7.6 +/- 1.9 ml.min-1 x W-1, P < 0.01), and the phase lag increased above- compared with below-LAT work rate. VO2/heart rate fluctuations were dramatically reduced, whereas heart rate amplitude decreased and phase lag increased, for above-LAT sinusoidal work rate changes. These results suggest that VO2 kinetics are slowed in the work rate domain above the LAT relative to that below the LAT and that VO2 kinetics could be limited by the O2 transport mechanisms to the exercising muscle.
Adequacy of food rations in soldiers during an arctic exercise measured by doubly labeled water
Authors: Jones P. J. , Jacobs I. , Morris A. , Ducharme M. B.
Published: December 2017

To investigate the adequacy of food rations to supply energy needs in cold-temperature environments, caloric expenditure and intake and body composition changes were measured in a group of infantrymen during a 10-day field exercise in the Canadian Arctic. Energy expenditure was measured by the doubly labeled water method (n = 10), and caloric intake was measured by complete food intake records (n = 20). Body composition was determined by isotope dilution (n = 10) and bioelectrical impedence analysis (n = 20) on days 0 and 10. Baseline isotopic enrichment shifts due to geographical relocation were also monitored (n = 5). Mean body weight decreased 0.63 +/- 0.83 (SD) kg over the study period (P < 0.005), although fat-free and fat mass compartment changes were not significant. Baseline isotopic changes were -4.65 +/- 2.54 and -0.48 +/- 0.07 /1000/day for deuterium and 18O, respectively. Mean baseline corrected energy expenditure level was 4,317 +/- 927 kcal/day. Self-reported caloric intakes obtained from food records were 2,633 +/- 499 kcal/day (61.0% of expenditure). Rations packs contained 4,350 kcal/day. Results suggest that 1) food intake was significantly underreported and 2) the energy needs of most subjects were being met by rations and available supplements.
Dynamic multichannel near-infrared optical imaging of human brain activity
Authors: Hoshi Y. , Tamura M.
Published: December 2017

The present paper demonstrates functional brain mapping with an optical imaging technique by using tissue-transparent near-infrared light. With a maximal five-channel optical monitoring system, we succeeded in detecting region-specific changes in both the hemoglobin oxygenation state and blood volume during various mental tasks, in addition to visual and auditory stimulation. The time course of increases in blood supply varied with each brain region and depended on the type of internal operations occurring during the mental tasks. Changes in the hemoglobin oxygenation state were also different from region to region. This showed that there were regional variations of the oxygen delivery-oxygen utilization relationship during activation of brain activity. The usefulness of multichannel near-infrared functional imaging was well documented.
Wave propagation, input impedance, and wall mechanics of the calf trachea from 16 to 1,600 Hz
Authors: Suki B. , Habib R. H. , Jackson A. C.
Published: December 2017

Propagation of waves in the airways is important in flow limitation as well as in oscillation mechanics. In five excised calf tracheae, we measured phase propagation velocity (c) and input impedance with open (Zop) or closed end (Zcl) for frequencies (f) between 16 and 1,600 Hz at two axial tensions [nonstretched (TN) and stretched (TS); TS > TN]. From 16 to 64 Hz, c slightly increased because of the viscoelastic properties of the wall tissues. Between 64 and 200 Hz, c was relatively constant and less than the free-field speed of sound (c0 = 340 m/s), with values smaller at TS (140 +/- 39 m/s) than at TN (172 +/- 35 m/s). Above 200 Hz, c exceeded c0 and displayed two maxima at approximately 300 and approximately 700 Hz, with values of approximately 360 and approximately 550 m/s, respectively. For f > 1,400 Hz, c approached c0. We provide evidence that the two maxima in c were the result of the two-compartment behavior of the wall tissues, i.e., the separate cartilaginous and soft tissues. A nonrigid tube model with its wall impedance composed of two series resistance, compliance, and inertance pathways in parallel simultaneously fits c, Zop, and Zcl well and hence provides a link among these data. By use of the relationship between volumetric wall parameters and the tracheal geometry, separate material properties such as viscosity and Young's modulus of both the soft tissue (approximately 1 cmH2O.s and approximately 0.26 x 10(4) cmH2O, respectively) and the cartilage (approximately 3.7 cmH2O.s and approximately 2 x 10(4) cmH2O, respectively) were estimated. These results indicate that measures of c and Zop or Zcl data over these frequencies provide information about the dynamic mechanical properties of both the soft tissue and cartilage in the airway walls.
Vagally mediated volume-dependent modulation of inspiratory duration in the neonatal lamb
Authors: Webb B. , Hutchison A. A. , Davenport P. W.
Published: December 2017

Inspiratory mechanical loads elicit a reflex volume-timing response in human infants and experimental animals. In adult animals, this reflex has been shown to be mediated by vagal afferents. It was hypothesized that the volume-related regulation of inspiratory duration would also be vagally mediated in the newborn. Single-breath graded inspiratory loads were presented to 4-day-old anesthetized neonatal lambs breathing through a facemask, after tracheostomy, and after bilateral cervical vagotomy. Inspired volume decreased and inspiratory duration (TI) increased with increasing load magnitude. The increase in TI was greater with facemask loads than with loads presented after tracheostomy for equivalent changes in inspired volume. The volume-related prolongation of TI after tracheostomy was abolished after cervical bilateral vagotomy. The results demonstrate that the volume-timing reflex in neonatal lambs after tracheostomy is mediated by vagal afferents. However, in the intact lamb, there is also a significant contribution to this reflex by upper airway afferents.
Mild hemorrhagic shock does not enhance the risk of CD18 blockade to S. aureus skin inoculations
Authors: Sasaki S. S. , Sharar S. R. , Harlan J. M. , Rice C. L. , Winn R. K.
Published: December 2017

Monoclonal antibody (MAb) 60.3 recognizes the leukocyte CD18 glycoprotein and ameliorates much of the injury after hemorrhagic shock in rabbits and nonhuman primates. This MAb blocks neutrophil emigration and has been shown to increase the risk of infection after high-dose inoculation of Staphylococcus aureus into skin. Hemorrhagic shock might also cause an increased sensitivity to bacterial injections. Therefore, we examined changes in host sensitivity to subcutaneous injections of 10(5)–10(8) colony-forming units (CFU) of S. aureus just before shock. Cardiac output was lowered to 40–45% of baseline by phlebotomy for 1 h. Intravenous saline or MAb 60.3 (2 mg/kg) treatment immediately preceded resuscitation with the shed blood. Cefazolin was given intravenously for 3 days, and the animals were killed after 7 days for analysis of infectious risk by measuring the incidence and surface area of skin abscess/necrosis. Bacteria injection resulted in no infections at 10(5) or 10(6) CFU and one abscess/necrotic region at 10(7) CFU (7% incidence) in the MAb-treated group. However, injection of 10(8) CFU resulted in more abscesses/necrotic regions in the MAb- vs. saline-treated group (86 vs. 25%; P < 0.05). The average size of these lesions was also larger in the MAb-treated group (4.6 +/- 7.1 vs. 0.5 +/- 0.6 cm2; P < 0.001). These results were similar to previously published results without shock (Sharar et al., Surgery St. Louis 110:213–220, 1991). We conclude that mild hemorrhagic shock does not enhance the infectious risk of MAb 60.3 after subcutaneous S. aureus injection.
Role of high-frequency ventilation in surfactant-depleted lung injury as measured by granulocytes
Authors: Matsuoka T. , Kawano T. , Miyasaka K.
Published: December 2017

Granulocytes were collected from the lung lavage fluid of surfactant-depleted rabbits to assess the relationship between granulocyte-related lung injury and ventilatory mode. The number of lavaged granulocytes was determined after 2 and 4 h of conventional mechanical ventilation (2CMV and 4CMV, respectively) or high-frequency oscillatory ventilation (2HFO and 4HFO, respectively). Stimulated respiratory bursts were assayed by luminol-dependent chemiluminescence (LDCL) with N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulation in four groups of rabbits. The number of lavaged granulocytes significantly increased with ventilatory duration in the CMV mode but not in the HFO mode. Meanwhile, peak LDCL response value with FMLP stimulation in 4CMV was substantially lower than values in the other three groups. The decrease in the granulocyte LDCL response in 4CMV suggests oxygen metabolite exhaustion in the cells. CMV increasingly induced the accumulation of granulocytes with activated respiratory bursts in the alveolar spaces with ventilatory duration. HFO did not cause granulocyte accumulation, nor did it impair granulocyte function. The results suggest that HFO is useful for the prevention of lung injury related to activated granulocytes.