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Journal articles on the topic 'Diaphragm – Mechanical properties'
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1
Farkas, G. A., L. E. Gosselin, W. Z. Zhan, E. H. Schlenker, and G. C. Sieck. "Histochemical and mechanical properties of diaphragm muscle in morbidly obese Zucker rats." Journal of Applied Physiology 77, no. 5 (November 1, 1994): 2250–59. http://dx.doi.org/10.1152/jappl.1994.77.5.2250.
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The purpose of the present study was to evaluate the effects of chronic mass loading produced by obesity on the structural and functional characteristics of the diaphragm in lean and obese Zucker rats. The trapezius muscle served as an internal control. The studies were carried out on 17 lean (303 +/- 24 g) and 16 obese (698 +/- 79 g) Zucker rats. We observed that the diaphragms from obese animals were restructured such that the overall contribution of type I and IIa fibers was significantly increased. As a consequence of this remodeling, overall diaphragm thickness was selectively greater in obese animals. In small isolated diaphragm bundles studied in vitro, we also detected a reduction in specific force in obese animals that was not detected in the trapezius muscle. In vitro fatigue resistance, assessed by repeated stimulation, was similar in muscles of lean and obese animals. Diaphragm fiber oxidative capacity (succinate dehydrogenase activity) was also comparable in lean and obese animals. We conclude that in obesity the diaphragm undergoes modest remodeling that may be beneficial in enhancing force generation.
2
Yu, Bo Lin, and Fa Hong Yu. "The Study on Diaphragm's Mechanical Properties of Hot-Film Air Flow Sensor." Advanced Materials Research 774-776 (September 2013): 1577–81. http://dx.doi.org/10.4028/www.scientific.net/amr.774-776.1577.
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In this paper, the diaphragms Mechanical property of Hot-film air flow sensor is studied on the base of proposition of double-sided convection heat air flow sensor. This diaphragm consists of barrier layer, support layer and passivation layer. For Hot-film air flow sensor, the Diaphragms Mechanical property is mainly up to the support layer, and the support layer is composed of Si3N4. In this research, four types of air flow sensors with different thickness of the support layer is prepared and tested at different air flow velocity. On the same time, the stress analysis of the sensor diaphragm is simulated at the flow rate of 5m/s by the finite element software. A conclusion can be drawn that the thickness of support layer can not be less than 1000nm, when the air flow velocity is more than 5m/s.
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Sassoon, Catherine S. H., Vincent J. Caiozzo, Albana Manka, and Gary C. Sieck. "Altered diaphragm contractile properties with controlled mechanical ventilation." Journal of Applied Physiology 92, no. 6 (June 1, 2002): 2585–95. http://dx.doi.org/10.1152/japplphysiol.01213.2001.
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This study shows that, over time, diaphragm inactivity with controlled mechanical ventilation (CMV) decreases diaphragm force and produces myofibril damage contributing to the reduced force. We measured in vivo and in vitro diaphragm contractile and morphological properties in 30 sedated rabbits grouped ( n = 6) as follows: 1 or 3 days of CMV, 1 or 3 days of 0 cmH2O continuous positive airway pressure, and control. The CMV rate was set sufficient to suppress diaphragm electrical activity. Compared with the control group, phrenic-stimulated maximum transdiaphragmatic pressure did not decrease with continuous positive airway pressure but decreased to 63% after 1 day of CMV and to 49% after 3 days of CMV. The in vitro tetanic force decreased to 86% after 1 day of CMV and to 44% after 3 days of CMV. After 3 days of CMV, significant myofibril damage occurred in the diaphragm but not in the soleus. The decrease in tetanic force correlated with the volume density of abnormal myofibrils. We conclude that CMV had a detrimental effect on diaphragm contractile properties.
4
Guerrini, Gabriele, Christian Salvatori, Ilaria Senaldi, and Andrea Penna. "Experimental and Numerical Assessment of Seismic Retrofit Solutions for Stone Masonry Buildings." Geosciences 11, no. 6 (May 27, 2021): 230. http://dx.doi.org/10.3390/geosciences11060230.
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This paper presents an experimental and numerical study on different retrofit solutions for stone masonry buildings with timber diaphragms in earthquake-prone regions, aiming at enhancing wall-to-diaphragm connections, diaphragms’ stiffness, and masonry properties. The experimental results of incremental dynamic shake-table tests on three full-scale two-story buildings, complemented by material and component characterization tests, are initially summarized. The first building specimen was unstrengthened. The second one was retrofitted at the floor and roof levels with improved wall-to-diaphragm connections and a moderate increase in diaphragm stiffness. Connections were also improved in the third specimen together with a significant enhancement of diaphragm stiffness. The calibration of two numerical models, versus the experimental response of the retrofitted building specimens, is then presented. The models were further modified and reanalyzed to assess the effects of masonry mechanical upgrades, which could be achieved in practice through deep joint repointing or various types of jacketing. These solutions were simulated by applying correction coefficients to the masonry mechanical properties, as suggested by the Italian building code. The effectiveness of the experimentally implemented and numerically simulated interventions are discussed in terms of strength enhancement and failure modes.
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Boriek, Aladin M., Y. Capetanaki, Willy Hwang, Todd Officer, Muffasir Badshah, Joe Rodarte, and James G. Tidball. "Desmin integrates the three-dimensional mechanical properties of muscles." American Journal of Physiology-Cell Physiology 280, no. 1 (January 1, 2001): C46—C52. http://dx.doi.org/10.1152/ajpcell.2001.280.1.c46.
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Striated muscle is a linear motor whose properties have been defined in terms of uniaxial structures. The question addressed here is what contribution is made to the properties of this motor by extramyofilament cytoskeletal structures that are not aligned in parallel with the myofilaments. This question arose from observations that transverse loads increase muscle force production in diaphragm but not in the hindlimb muscle, thereby indicating the presence of structures that couple longitudinal and transverse properties of diaphragmatic muscle. Furthermore, we find that the diaphragms of null mutants for the cytoskeletal protein desmin show 1) significant reductions in coupling between the longitudinal and transverse properties, indicating for the first time a role for a specific protein in integrating the three-dimensional mechanical properties of muscle, 2) significant reductions in the stiffness and viscoelasticity of muscle, and 3) significant increases in tetanic force production. Thus desmin serves a complex mechanical function in diaphragm muscle by contributing both to passive stiffness and viscoelasticity and to modulation of active force production in a three-dimensional structural network. Our finding changes the paradigm of force transmission among cells by placing our understanding of the function of the cytoskeleton in the context of the structural and mechanical complexity of muscles.
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Mifuji, Shinichiro, Koji Adachi, Tatsunori Tsukioka, and Satomitsu Imai. "Thermal Driving Method and Displacement Properties of a Thin-Film Polyimide Diaphragm for a MEMS Actuator." Key Engineering Materials 523-524 (November 2012): 563–68. http://dx.doi.org/10.4028/www.scientific.net/kem.523-524.563.
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A thin-film polyimide diaphragm for a MEMS actuator was fabricated and its process and mechanical characteristics were investigated. Owing to its low elastic modulus and the thin-film process, a thin-film polyimide diaphragm has a merit in terms of producing a large displacement. Given that merit, spin coating was used for forming a thin film of polyamide, and deep-RIE (Bosch process) was used for fabricating the diaphragm section of the actuator. Thin-film polyimide diaphragms with micrometer-order thickness were fabricated. To drive the diaphragm as an actuator, the following two methods were applied: heat expansion by applying an electric current and volume expansion of a gas-liquid phase-change material confined in a cavity between polyimide diaphragms. As for the former method, an aluminum thin film is deposited on the diaphragm. As for the latter, paraffin (vaporized by heating) is used as the phase-change material. Displacement characteristics for each method were revealed by the experiments. In the case of both methods, displacements of tens of micrometers were outputted. Experiments of driving actuator confirmed that the proposed systems work as actuators. The actuators developed in this research are applicable to micro-pumps for medical and other uses.
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Lopez, M. A., U. Mayer, W. Hwang, T. Taylor, M. A. Hashmi, S. R. Jannapureddy, and Aladin M. Boriek. "Force transmission, compliance, and viscoelasticity are altered in the α7-integrin-null mouse diaphragm." American Journal of Physiology-Cell Physiology 288, no. 2 (February 2005): C282—C289. http://dx.doi.org/10.1152/ajpcell.00362.2003.
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α7β1 integrin is a transmembrane structural and receptor protein of skeletal muscles, and the absence of α7-integrin causes muscular dystrophy. We hypothesized that the absence of α7-integrin alters compliance and viscoelasticity and disrupts the mechanical coupling between passive transverse and axial contractile elements in the diaphragm. In vivo the diaphragm is loaded with pressure, and therefore axial and transverse length-tension relationships are important in assessing its function. We determined diaphragm passive length-tension relationships and the viscoelastic properties of its muscle in 1-month-old α7-integrin-null mice and age-matched controls. Furthermore, we measured the isometric contractile properties of the diaphragm from mutant and normal mice in the absence and presence of passive force applied in the transverse direction to fibers in 1-month-old and 5-month-old mutant mice. We found that compared with controls, the diaphragm direction of α7-integrin-null mutants showed 1) a significant decrease in muscle extensibility in 1-year-old mice, whereas muscle extensibility increased in the 1-month-old mice; 2) altered muscle viscoelasticity in the transverse direction of the muscle fibers of 1-month-old mice; 3) a significant increase in force-generating capacity in the diaphragms of 1-month-old mice, whereas in 5-month-old mice muscle contractility was depressed; and 4) significant reductions in mechanical coupling between longitudinal and transverse properties of the muscle fibers of 1-month-old mice. These findings suggest that α7-integrin serves an important mechanical function in the diaphragm by contributing to passive compliance, viscoelasticity, and modulation of its muscle contractile properties.
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Pardo, Patricia S., Michael A. Lopez, and Aladin M. Boriek. "FOXO transcription factors are mechanosensitive and their regulation is altered with aging in the respiratory pump." American Journal of Physiology-Cell Physiology 294, no. 4 (April 2008): C1056—C1066. http://dx.doi.org/10.1152/ajpcell.00270.2007.
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The mechanical regulation of the forkhead box O (FOXO) subclass of transcription factors in the respiratory pump and its implication in aging are completely unknown. We investigated the effects of diaphragm stretch on three FOXO isoforms, Foxo1, Foxo3a, and Foxo4, in normal mice at different ages. We tested the hypotheses that 1) FOXO activities are regulated in response to diaphragm stretch and 2) mechanical properties of aging diaphragm are altered, leading to altered regulation of FOXO with aging. Our results showed that stretch downregulated FOXO DNA-binding activity by a mechanism that required Akt and IKK activation in young mice but that these pathways lost their mechanosensitivity with age. This aberrant regulation of FOXO with aging was associated with altered viscoelasticity, compliance, and extensibility of the aged diaphragm. Curiously, the dramatic decrease of the nuclear content of Foxo1 and Foxo3a, the two isoforms associated with muscle atrophy, with aging correlated with higher basal activation of Akt and IKK signaling in diaphragms of old mice. In contrast, the stability of Foxo4 in the nucleus became dependent on JNK, which is strongly activated in aged diaphragm. This finding suggests that Foxo4 was responsible for the FOXO-dependent transcriptional activity in aging diaphragm. Our data support the hypothesis that aging alters the mechanical properties of the respiratory pump, leading to altered mechanical regulation of the stretch-induced signaling pathways controlling FOXO activities. Our study supports a mechanosensitive signaling mechanism that is responsible for regulation of the FOXO transcription factors by aging.
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Lopez, Michael A., Patricia S. Pardo, Gregory A. Cox, and Aladin M. Boriek. "Early mechanical dysfunction of the diaphragm in the muscular dystrophy with myositis (Ttnmdm) model." American Journal of Physiology-Cell Physiology 295, no. 5 (November 2008): C1092—C1102. http://dx.doi.org/10.1152/ajpcell.16.2008.
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A complex rearrangement mutation in the mouse titin gene leads to an in-frame 83-amino acid deletion in the N2A region of titin. Autosomal recessive inheritance of the titin muscular dystrophy with myositis ( Ttn mdm/mdm) mutation leads to a severe early-onset muscular dystrophy and premature death. We hypothesized that the N2A deletion would negatively impact the force-generating capacity and passive mechanical properties of the mdm diaphragm. We measured in vitro active isometric contractile and passive length-tension properties to assess muscle function at 2 and 6 wk of age. Micro-CT, myosin heavy chain Western blotting, and histology were used to assess diaphragm structure. Marked chest wall distortions began at 2 wk and progressively worsened until 5 wk. The percentage of myofibers with centrally located nuclei in mdm mice was significantly ( P < 0.01) increased at 2 and 6 wk by 4% and 17%, respectively, compared with controls. At 6 wk, mdm diaphragm twitch stress was significantly ( P < 0.01) reduced by 71%, time to peak twitch was significantly ( P < 0.05) reduced by 52%, and half-relaxation time was significantly ( P < 0.05) reduced by 57%. Isometric tetanic stress was significantly ( P < 0.05) depressed in 2- and 6-wk mdm diaphragms by as much as 64%. Length-tension relationships of the 2- and 6-wk mdm diaphragms showed significantly ( P < 0.05) decreased extensibility and increased stiffness. Slow myosin heavy chain expression was aberrantly favored in the mdm diaphragm at 6 wk. Our data strongly support early contractile and passive mechanical aberrations of the respiratory pump in mdm mice.
10
Ren, Juan, David Cheneler, Mike Ward, and Peter Kinnell. "The Mechanical Behaviour of Silicon Diaphragms for Micromachined Capacitive Pressure Sensor." Advances in Science and Technology 54 (September 2008): 422–27. http://dx.doi.org/10.4028/www.scientific.net/ast.54.422.
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Single crystal silicon diaphragms are widely used as pressure sensitive elements in micromachined pressure sensors. When designing such a sensor it is usual to assume that the silicon is an isotropic material and the average elastic constants are used. However, the mechanical properties of single crystal silicon are orthotropic, and this has an important effect on the mechanical behaviour of silicon diaphragms under pressure. In this work, the deflections of orthotropic silicon circular diaphragms which are orientated against the (100) and the (110) planes are presented. It is found that by assuming silicon is isotropic material, the maximum stress is underestimated by 9.4% for (110) orientated silicon diaphragms, while the maximum stress is underestimated by 8% for (100) orientated silicon diaphragms. Therefore, when a silicon diaphragm is used in a MEMS sensor, the orthotropic properties should be taken into account for accuracy. Finally, the performance of a capacitive sensor is predicted by using finite element method.
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Lopez, Michael A., Sherina Bontiff, Mary Adeyeye, Aziz I. Shaibani, Matthew S. Alexander, Shari Wynd, and Aladin M. Boriek. "Mechanics of dystrophin deficient skeletal muscles in very young mice and effects of age." American Journal of Physiology-Cell Physiology 321, no. 2 (August 1, 2021): C230—C246. http://dx.doi.org/10.1152/ajpcell.00155.2019.
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The MDX mouse is an animal model of Duchenne muscular dystrophy, a human disease marked by an absence of the cytoskeletal protein, dystrophin. We hypothesized that 1) dystrophin serves a complex mechanical role in skeletal muscles by contributing to passive compliance, viscoelastic properties, and contractile force production and 2) age is a modulator of passive mechanics of skeletal muscles of the MDX mouse. Using an in vitro biaxial mechanical testing apparatus, we measured passive length-tension relationships in the muscle fiber direction as well as transverse to the fibers, viscoelastic stress-relaxation curves, and isometric contractile properties. To avoid confounding secondary effects of muscle necrosis, inflammation, and fibrosis, we used very young 3-wk-old mice whose muscles reflected the prefibrotic and prenecrotic state. Compared with controls, 1) muscle extensibility and compliance were greater in both along fiber direction and transverse to fiber direction in MDX mice and 2) the relaxed elastic modulus was greater in dystrophin-deficient diaphragms. Furthermore, isometric contractile muscle stress was reduced in the presence and absence of transverse fiber passive stress. We also examined the effect of age on the diaphragm length-tension relationships and found that diaphragm muscles from 9-mo-old MDX mice were significantly less compliant and less extensible than those of muscles from very young MDX mice. Our data suggest that the age of the MDX mouse is a determinant of the passive mechanics of the diaphragm; in the prefibrotic/prenecrotic stage, muscle extensibility and compliance, as well as viscoelasticity, and muscle contractility are altered by loss of dystrophin.
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Fournier, M., and G. C. Sieck. "Mechanical properties of muscle units in the cat diaphragm." Journal of Neurophysiology 59, no. 3 (March 1, 1988): 1055–66. http://dx.doi.org/10.1152/jn.1988.59.3.1055.
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1. Muscle units in the right sternocostal region of the cat diaphragm (DIA) were isolated in situ by dissecting filaments of the C5 ventral root. Isometric contractile and fatigue properties of DIA units were then measured. Contractile properties included: twitch contraction time (CT), peak twitch tension (Pt), maximum tetanic tension (P0), and the frequency dependence of tension production. Muscle-unit fatigue resistance was estimated using a 2-min fatigue test. 2. DIA muscle units were classified as fast (F) or slow (S) based on the presence or absence of sag in their unfused tetanic force responses. Muscle-unit fatigue indices (FI) were used to further classify DIA units as slow-twitch fatigue-resistant (S), fast-twitch fatigue-resistant (FR) fast-twitch fatigue-intermediate (FInt), or fast-twitch fatigable (FF) types. 3. Based on a total of 47 completely characterized DIA muscle units, 21% were classified as S, 4% as FR, 28% as FInt, and 47% as FF. In contrast to the distribution of unit types in other mixed appendicular muscles, the DIA was composed of a very low proportion of FR units and a relatively high proportion of FInt units. An interval of FIs between 0.50 and 0.75 separated units into fatigue-resistant and fatigable groups. The distribution of FIs for FF and most FInt units was continuous, indicating that they formed a single fatigable group. Relatively few FF units in the DIA had FIs less than 0.10. 4. A wide range of contractile properties was observed for DIA muscle units. Type S units had longer CTs and lower Pt and P0 values than type F units. The mean Pt and P0 of FF and FInt units were comparable, whereas the mean Pt and P0 of the two FR units were lower. Type S units produced a greater proportion of their P0 at lower frequencies of activation than type F units. The lower P0S produced by type F units in the DIA indicated that they were smaller than similar units in appendicular muscles. It was concluded that in meeting most normal ventilatory requirements, adequate force could be generated by the recruitment of only type S and FR units. The recruitment of the more fatigable FF and FInt units may occur only during more forceful respiratory and nonrespiratory behaviors of the DIA.
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Strumpf, R. K., J. D. Humphrey, and F. C. Yin. "Biaxial mechanical properties of passive and tetanized canine diaphragm." American Journal of Physiology-Heart and Circulatory Physiology 265, no. 2 (August 1, 1993): H469—H475. http://dx.doi.org/10.1152/ajpheart.1993.265.2.h469.
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The architecture, vascular supply, and ease of tetanization make the diaphragm an ideal structure in which to assess multidimensional mechanical properties of active and passive striated muscle. We developed an isolated, perfused canine diaphragm preparation suitable for the assessment of biaxial stress-strain relations in both the resting state and during tetanization. Each of 33 specimens had a wide, flat region (approximately 3 x 3 cm) wherein there was a single predominant fiber direction. Simultaneous, equal stretchings were imposed in the fiber and perpendicular cross-fiber directions over the same strain ranges in both the passive state and during tetanic contraction. Highly nonlinear behavior was seen in the passive state with a limit of extensibility in both directions. The specimens were also markedly anisotropic, with the cross-fiber direction being stiffer than the fiber direction (slopes of the regression line for the stresses in each direction averaged 3.97). Moreover, 31 of the 33 specimens were stiffer in the cross-fiber direction, one was isotropic, and one was stiffer in the fiber direction. During tetanization, the extent and distribution of anisotropy were significantly altered (regression slope averaged 1.08, and 18 specimens were now either isotropic or stiffer in the fiber direction). Disrupting the membranes covering each surface increased extensibility and decreased the anisotropy, thereby suggesting that these membranes bear most of the passive load and contribute greatly to the cross-fiber stiffness and anisotropy of the intact diaphragm. Both before and after disruption of the surface membranes, there was still a consistent increase in cross-fiber stress during tetanization, implying active force generation perpendicular to the fiber direction.(ABSTRACT TRUNCATED AT 250 WORDS)
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Bellemare, F., B. Bigland-Ritchie, and J. J. Woods. "Contractile properties of the human diaphragm in vivo." Journal of Applied Physiology 61, no. 3 (September 1, 1986): 1153–61. http://dx.doi.org/10.1152/jappl.1986.61.3.1153.
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The mechanical properties of the human diaphragm have been studied at fractional residual capacity in normal seated subjects with closed glottis. The transdiaphragmatic pressure (Pdi) developed in response to single shocks or to trains of stimuli at increasing frequency was approximately 3 times greater during bilateral than unilateral stimulation. During unilateral phrenic nerve stimulation the Pdi twitches increased as the interval (0–200 ms) of a preceding conditioning stimulus to the contralateral phrenic nerve was decreased suggesting that the two hemidiaphragms are mechanically coupled in series. The contraction time and half-relaxation time of single bilateral twitches as well as the Pdi-frequency relationship (5–35 Hz) during bilateral tetanic stimulation indicate that the contractile properties of the human diaphragm are intermediate between those of fast- and slow-twitch muscle fibers. The results suggest that the contractile properties of the human diaphragm are well illustrated by single bilateral twitches recorded from the relaxed muscle, but that the responses to unilateral stimulation are misleading due to distortion by abnormal changes in the muscle geometry.
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Ermilov, Leonid G., Juan N. Pulido, Fawn W. Atchison, Wen-Zhi Zhan, Mark H. Ereth, Gary C. Sieck, and Carlos B. Mantilla. "Impairment of diaphragm muscle force and neuromuscular transmission after normothermic cardiopulmonary bypass: effect of low-dose inhaled CO." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 298, no. 3 (March 2010): R784—R789. http://dx.doi.org/10.1152/ajpregu.00737.2009.
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Cardiopulmonary bypass (CPB) is associated with significant postoperative morbidity, but its effects on the neuromuscular system are unclear. Recent studies indicate that even relatively short periods of mechanical ventilation result in significant neuromuscular effects. Carbon monoxide (CO) has gained recent attention as therapy to reduce the deleterious effects of CPB. We hypothesized that 1) CPB results in impaired neuromuscular transmission and reduced diaphragm force generation; and 2) CO treatment during CPB will mitigate these effects. In adult male Sprague-Dawley rats, diaphragm muscle-specific force and neuromuscular transmission properties were measured 90 min after weaning from normothermic CPB (1 h). During CPB, either low-dose inhaled CO (250 ppm) or air was administered. The short period of mechanical ventilation used in the present study (∼3 h) did not adversely affect diaphragm muscle contractile properties or neuromuscular transmission. CPB elicited a significant decrease in isometric diaphragm muscle-specific force compared with time-matched, mechanically ventilated rats (∼25% decline in both twitch and tetanic force). Diaphragm muscle fatigability to 40-Hz repetitive stimulation did not change significantly. Neuromuscular transmission failure during repetitive activation was 60 ± 2% in CPB animals compared with 76 ± 4% in mechanically ventilated rats ( P < 0.05). CO treatment during CPB abrogated the neuromuscular effects of CPB, such that diaphragm isometric twitch force and neuromuscular transmission were no longer significantly different from mechanically ventilated rats. Thus, CPB has important detrimental effects on diaphragm muscle contractility and neuromuscular transmission that are largely mitigated by CO treatment. Further studies are needed to ascertain the underlying mechanisms of CPB-induced neuromuscular dysfunction and to establish the potential role of CO therapy.
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Bruells, Christian S., Karen Maes, Rolf Rossaint, Debby Thomas, Nele Cielen, Ingmar Bergs, Christian Bleilevens, Joachim Weis, and Ghislaine Gayan-Ramirez. "Sedation Using Propofol Induces Similar Diaphragm Dysfunction and Atrophy during Spontaneous Breathing and Mechanical Ventilation in Rats." Anesthesiology 120, no. 3 (March 1, 2014): 665–72. http://dx.doi.org/10.1097/aln.0000000000000125.
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Abstract Background: Mechanical ventilation is crucial for patients with respiratory failure. The mechanical takeover of diaphragm function leads to diaphragm dysfunction and atrophy (ventilator-induced diaphragmatic dysfunction), with an increase in oxidative stress as a major contributor. In most patients, a sedative regimen has to be initiated to allow tube tolerance and ventilator synchrony. Clinical data imply a correlation between cumulative propofol dosage and diaphragm dysfunction, whereas laboratory investigations have revealed that propofol has some antioxidant properties. The authors hypothesized that propofol reduces markers of oxidative stress, atrophy, and contractile dysfunction in the diaphragm. Methods: Male Wistar rats (n = 8 per group) were subjected to either 24 h of mechanical ventilation or were undergone breathing spontaneously for 24 h under propofol sedation to test for drug effects. Another acutely sacrificed group served as controls. After sacrifice, diaphragm tissue was removed, and contractile properties, cross-sectional areas, oxidative stress, and proteolysis were examined. The gastrocnemius served as internal control. Results: Propofol did not protect against diaphragm atrophy, oxidative stress, and protease activation. The decrease in tetanic force compared with controls was similar in the spontaneous breathing group (31%) and in the ventilated group (34%), and both groups showed the same amount of muscle atrophy. The gastrocnemius muscle fibers did not show atrophy. Conclusions: Propofol does not protect against ventilator-induced diaphragmatic dysfunction or oxidative injury. Notably, spontaneous breathing under propofol sedation resulted in the same amount of diaphragm atrophy and dysfunction although diaphragm activation per se protects against ventilator-induced diaphragmatic dysfunction. This makes a drug effect of propofol likely.
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Smith, Lucas R., and Elisabeth R. Barton. "Collagen content does not alter the passive mechanical properties of fibrotic skeletal muscle inmdxmice." American Journal of Physiology-Cell Physiology 306, no. 10 (May 15, 2014): C889—C898. http://dx.doi.org/10.1152/ajpcell.00383.2013.
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Many skeletal muscle diseases are associated with progressive fibrosis leading to impaired muscle function. Collagen within the extracellular matrix is the primary structural protein providing a mechanical scaffold for cells within tissues. During fibrosis collagen not only increases in amount but also undergoes posttranslational changes that alter its organization that is thought to contribute to tissue stiffness. Little, however, is known about collagen organization in fibrotic muscle and its consequences for function. To investigate the relationship between collagen content and organization with muscle mechanical properties, we studied mdx mice, a model for Duchenne muscular dystrophy (DMD) that undergoes skeletal muscle fibrosis, and age-matched control mice. We determined collagen content both histologically, with picosirius red staining, and biochemically, with hydroxyproline quantification. Collagen content increased in the mdx soleus and diaphragm muscles, which was exacerbated by age in the diaphragm. Collagen packing density, a parameter of collagen organization, was determined using circularly polarized light microscopy of picosirius red-stained sections. Extensor digitorum longus (EDL) and soleus muscle had proportionally less dense collagen in mdx muscle, while the diaphragm did not change packing density. The mdx muscles had compromised strength as expected, yet only the EDL had a significantly increased elastic stiffness. The EDL and diaphragm had increased dynamic stiffness and a change in relative viscosity. Unexpectedly, passive stiffness did not correlate with collagen content and only weakly correlated with collagen organization. We conclude that muscle fibrosis does not lead to increased passive stiffness and that collagen content is not predictive of muscle stiffness.
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Thomas, Debby, Karen Maes, Anouk Agten, Leo Heunks, Richard Dekhuijzen, Marc Decramer, Hieronymus Van Hees, and Ghislaine Gayan-Ramirez. "Time course of diaphragm function recovery after controlled mechanical ventilation in rats." Journal of Applied Physiology 115, no. 6 (September 15, 2013): 775–84. http://dx.doi.org/10.1152/japplphysiol.00302.2012.
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Controlled mechanical ventilation (CMV) is known to result in rapid and severe diaphragmatic dysfunction, but the recovery response of the diaphragm to normal function after CMV is unknown. Therefore, we examined the time course of diaphragm function recovery in an animal model of CMV. Healthy rats were submitted to CMV for 24–27 h ( n = 16), or to 24-h CMV followed by either 1 h (CMV + 1 h SB, n = 9), 2 h (CMV + 2 h SB, n = 9), 3 h (CMV + 3 h SB, n = 9), or 4–7 h (CMV + 4–7 h SB, n = 9) of spontaneous breathing (SB). At the end of the experiment, the diaphragm muscle was excised for functional and biochemical analysis. The in vitro diaphragm force was significantly improved in the CMV + 3 h SB and CMV + 4–7 h SB groups compared with CMV (maximal tetanic force: +27%, P < 0.05, and +59%, P < 0.001, respectively). This was associated with an increase in the type IIx/b fiber dimensions ( P < 0.05). Neutrophil influx was increased in the CMV + 4–7 h SB group ( P < 0.05), while macrophage numbers remained unchanged. Markers of protein synthesis (phosphorylated Akt and eukaryotic initiation factor 4E binding protein 1) were significantly increased (±40%, P < 0.001, and ±52%, P < 0.01, respectively) in the CMV + 3 h SB and CMV + 4–7 h SB groups and were positively correlated with diaphragm force ( P < 0.05). Finally, also the maximal specific force generation of skinned single diaphragm fibers was increased in the CMV + 4–7 h SB group compared with CMV (+45%, P < 0.05). In rats, reloading the diaphragm for 3 h after CMV is sufficient to improve diaphragm function, while complete recovery occurs after longer periods of reloading. Enhanced muscle fiber dimensions, increased protein synthesis, and improved intrinsic contractile properties of diaphragm muscle fibers may have contributed to diaphragm function recovery.
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Picard, Martin, Ilan Azuelos, Boris Jung, Christian Giordano, Stefan Matecki, Sabah Hussain, Kathryn White, et al. "Mechanical ventilation triggers abnormal mitochondrial dynamics and morphology in the diaphragm." Journal of Applied Physiology 118, no. 9 (May 1, 2015): 1161–71. http://dx.doi.org/10.1152/japplphysiol.00873.2014.
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The diaphragm is a unique skeletal muscle designed to be rhythmically active throughout life, such that its sustained inactivation by the medical intervention of mechanical ventilation (MV) represents an unanticipated physiological state in evolutionary terms. Within a short period after initiating MV, the diaphragm develops muscle atrophy, damage, and diminished strength, and many of these features appear to arise from mitochondrial dysfunction. Notably, in response to metabolic perturbations, mitochondria fuse, divide, and interact with neighboring organelles to remodel their shape and functional properties—a process collectively known as mitochondrial dynamics. Using a quantitative electron microscopy approach, here we show that diaphragm contractile inactivity induced by 6 h of MV in mice leads to fragmentation of intermyofibrillar (IMF) but not subsarcolemmal (SS) mitochondria. Furthermore, physical interactions between adjacent organellar membranes were less abundant in IMF mitochondria during MV. The profusion proteins Mfn2 and OPA1 were unchanged, whereas abundance and activation status of the profission protein Drp1 were increased in the diaphragm following MV. Overall, our results suggest that mitochondrial morphological abnormalities characterized by excessive fission-fragmentation represent early events during MV, which could potentially contribute to the rapid onset of mitochondrial dysfunction, maladaptive signaling, and associated contractile dysfunction of the diaphragm.
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Li, Wen Hu, Da Long Ren, and Feng Hua Zhao. "Research on Diaphragm Reinforcement Design of Continuous Composite Girder Bridge with Corrugated Steel Webs." Applied Mechanics and Materials 438-439 (October 2013): 860–64. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.860.
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Diaphragm distributes lateral loads, and improves mechanical properties of bridge structure of prestressed concrete (PC) continuous wide girder bridge. The role of diaphragm is more prominent in composite wide girder bridge with corrugated steel webs, which stiffness is smaller compared with PC continuous bridge. Diaphragm is calculated and analyzed of composite box-girder bridge with corrugated steel webs, and reinforcement schemes are presented, aimed at diaphragm crack width overrun and insufficient bearing capacity. The reinforcement scheme is adding prestressed steel cables and special supports, stress and crack resistance are analyzed on reinforced diaphragm to verify the existing problems can be completely solved.
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Zocchi, L., N. Garzaniti, S. Newman, and P. T. Macklem. "Effect of hyperinflation and equalization of abdominal pressure on diaphragmatic action." Journal of Applied Physiology 62, no. 4 (April 1, 1987): 1655–64. http://dx.doi.org/10.1152/jappl.1987.62.4.1655.
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We tested the hypothesis that the mechanical arrangement of costal (COS) and crural (CRU) diaphragms can be changed from parallel to series when direct or indirect transmission of tension occurs. Ratio of rib cage to abdominal displacement (RC/AB) resulting from separate COS and CRU stimulations were used to measure RC expanding action. Hyperinflation in six dogs caused RC/AB with COS and CRU stimulations to change progressively from 0.53 +/- 0.07 (SE) and 0.03 +/- 0.05 at functional residual capacity (FRC) to -0.48 +/- 0.08 and -0.46 +/- 0.05 at 68% inspiratory capacity, respectively. Liquid substitution of abdominal contents in six other dogs equalized abdominal pressure swings (delta Pab), without changing chest wall elastic properties or geometry, or costal RC/AB (0.35 +/- 0.07 before and 0.33 +/- 0.06 after) but caused crural RC/AB to change from 0.01 +/- 0.05 to 0.31 +/- 0.01. We conclude that hyperinflation changes fiber orientation, allowing direct transmission of tension between COS and CRU, which become linked mechanically in series (the diaphragm acts as a unit with RC deflating action); and equalization of delta Pab causes indirect transmission of tension between COS and CRU, which become linked in series (the diaphragm acts as a unit with RC inflating action).
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Winter, M. D., M. L. Ball, J. D. Altringham, and D. L. Lee. "The effect of Trichinella spiralis and Trichinella pseudospiralis on the mechanical properties of mammalian diaphragm muscle." Parasitology 109, no. 1 (July 1994): 129–34. http://dx.doi.org/10.1017/s0031182000077830.
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SUMMARYThe isometric mechanical properties of diaphragm muscle were studied in mice infected with either Trichinella spiralis or Trichinella pseudospiralis. Measurements of muscle stress were taken at 15, 20, 30 and 40 days post-infection. Infected diaphragm muscle showed a significant (P < 0·001) reduction in muscle stress during both twitch and tetanic contractions when compared with muscle from control animals. T. spiralis caused a significant reduction in resistance to muscle fatigue. The consequences of these changes in muscle function to host pathology are discussed, and related to previous work on the effects of Trichinella on host biochemistry and the immune response.
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Patel, Nisha D., Suneal R. Jannapureddy, Willy Hwang, Imran Chaudhry, and Aladin M. Boriek. "Altered muscle force and stiffness of skeletal muscles in α-sarcoglycan-deficient mice." American Journal of Physiology-Cell Physiology 284, no. 4 (April 1, 2003): C962—C968. http://dx.doi.org/10.1152/ajpcell.00326.2002.
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α-Sarcoglycan (ASG) is a transmembrane protein of the dystrophin-associated complex, and absence of ASG causes limb-girdle muscular dystrophy. We hypothesize that disruption of the sarcoglycan complex may alter muscle extensibility and disrupt the coupling between passive transverse and axial contractile elements in the diaphragm. We determined the length-tension relationships of the diaphragm of young ASG-deficient mice and their controls during uniaxial and biaxial loading. We also determined the isometric contractile properties of the diaphragm muscles from mutant and normal mice in the absence and presence of passive transverse stress. We found that the diaphragm muscles of the null mutants for the protein ASG show 1) significant decrease in muscle extensibility in the directions of the muscle fibers and transverse to fibers, 2) significant reductions in force-generating capacity, and 3) significant reductions in coupling between longitudinal and transverse properties. Thus these findings suggest that the sarcoglycan complex serves a mechanical function in the diaphragm by contributing to muscle passive stiffness and to the modulation of the contractile properties of the muscle.
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Cui, Zhen, Qimin Li, and Jian Wang. "MECHANICAL PERFORMANCE OF COMPOSITE RETAINING AND PROTECTION STRUCTURE FOR SUPER LARGE AND DEEP FOUNDATION EXCAVATIONS." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 25, no. 5 (May 2, 2019): 431–40. http://dx.doi.org/10.3846/jcem.2019.9873.
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The reliable retaining methods and a good stress system are the key to the success of super large and deep excavation engineering. In this paper, the deepest foundation pit in Hainan province is taken as an example. The method of mutual verification between in-situ monitoring and numerical simulation is adopted. The mechanical performance of composite retaining structure composed of reinforced concrete cast-in-situ soldier pile wall, diaphragm wall and prestressed anchor cable are studied. The interaction between the reinforced concrete cast-in-situ pile retaining structure at the upper part and the diaphragm wall retaining structure at the lower part is revealed, and the variation of internal forces of the diaphragm wall retaining structure in the time and space is demonstrated. And then the influence of insertion ratio and rigidity on the mechanical properties of diaphragm wall is discussed. Research shows, the range of interaction between the upper and lower retaining structures is limited. During the excavation process, the maximum bending moment of the diaphragm wall is always near the excavation surface, and the curvature of the bending moment curve decreases gradually with the increase of excavation depth and axial tension of anchor. When the insertion ratio of diaphragm wall increases, the maximum bending moment moves upward. With the rigidity of the diaphragm wall increases moderately, the bending moment of the retaining structure increases, but the lateral displacement decreases. The research results can provide theoretical basis and practical experience for the composite retaining structure design of super large and deep foundation excavations.
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Luo, Yanbin, Zhou Shi, Jianxun Chen, Weiwei Liu, Yao Li, Yunfei Wu, and Haoyang Zhu. "Study of Deformation Behaviors and Mechanical Properties of Central Diaphragm in a Large-Span Loess Tunnel by the Upper Bench CD Method." Advances in Civil Engineering 2020 (July 21, 2020): 1–19. http://dx.doi.org/10.1155/2020/8887040.
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The central diaphragm is often used to reduce the span to maintain the stability and safety of structure in the construction of large-span loess tunnel due to the structure complexities. In this paper, relying on the field monitoring and measurement for Wangcun tunnel in Huangling-Yan’an expressway expansion project, the crown settlement and horizontal convergence of primary support steel rib and central diaphragm steel rib during the construction are analyzed by the upper bench CD method. According to the internal force transfer, deformation coordination, and arch foot displacement between the two structures, the support system is regarded as the arch-beam fixed structure with three times of statically indeterminate and movable abutment under the loads, and the mechanical calculation model of sidewall steel rib and the central diaphragm structure bearing loads and deformation together is established. Finally, through the mechanical model mentioned above, the deformation characteristics of central diaphragm structure and the horizontal convergence in the upper bench of tunnel are calculated and analyzed. The research shows the following: (1) the accumulated settlement of sidewall steel rib in Part I is greater than that of the sidewall steel rib in Part II, and the accumulated settlement of each part at the support structure during the tunnel excavation is less than the reserved deformation of 150 mm specified in the tunnel excavation; (2) the settlement located at the waist and maximum excavation line position of central diaphragm is mainly affected by the excavation of Parts I and II in upper bench; (3) during the whole excavation process, the excavation of Part I and Part II has the greatest influence on the convergence at arch waist and the maximum excavation line position in Part I, and the convergence at the above two positions all experienced four stages of “convergence-expansion-convergence-gradual stability”; and (4) the errors between the horizontal convergence and the deformation of central diaphragm obtained by the mechanical model and the field monitoring data are between 12.7% and 27.5%. The calculated results are in good agreement with the actual situation. The research can provide a theoretical basis for the study of deformation and mechanical properties for support structure in the construction of large-span loess tunnel by the upper bench CD method.
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Eddinger, T. J., and R. L. Moss. "Mechanical properties of skinned single fibers of identified types from rat diaphragm." American Journal of Physiology-Cell Physiology 253, no. 2 (August 1, 1987): C210—C218. http://dx.doi.org/10.1152/ajpcell.1987.253.2.c210.
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Maximum isometric tension (Po), maximum velocity of shortening (Vmax), and tension-pCa (i.e., -log[Ca2+]) relationships were determined in single skinned fibers from rat diaphragm. Histochemistry (myosin-ATPase) and sodium dodecyl sulfate (SDS) gel electrophoresis were performed on these same fibers to determine fiber type and protein composition. Physiologically fast fibers were found to have larger cross-sectional areas (CSA) and produced more tension per CSA and were less sensitive to [Ca2+] than physiologically slow fibers. Fast fibers were typed histochemically as type II and contained myosin heavy chains (MHC) and light chains (LC) of the fast type, whereas the slow fibers contained slow MHC and LC. There were also corresponding differences in the regulatory protein composition of these two fiber types. The histochemical sections confirmed a significant fiber size difference between the type IIa and IIb fibers. When fiber size was used to separate the fast fibers into two groups, type IIb fibers were found to have significantly greater Vmax and tension per CSA than the type IIa fibers. Although there were no noticeable differences in MHC composition between the type IIa and IIb fibers, there were some differences in the myosin LC and regulatory protein content.
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Jannapureddy, Suneal R., Nisha D. Patel, Willy Hwang, and Aladin M. Boriek. "Selected Contribution: Merosin deficiency leads to alterations in passive and active skeletal muscle mechanics." Journal of Applied Physiology 94, no. 6 (June 1, 2003): 2524–33. http://dx.doi.org/10.1152/japplphysiol.01078.2002.
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The role of extracellular elements on the mechanical properties of skeletal muscles is unknown. Merosin is an essential extracellular matrix protein that forms a mechanical junction between the sarcolemma and collagen. Therefore, it is possible that merosin plays a role in force transmission between muscle fibers and collagen. We hypothesized that deficiency in merosin may alter passive muscle stiffness, viscoelastic properties, and contractile muscle force in skeletal muscles. We used the dy/dy mouse, a merosin-deficient mouse model, to examine changes in passive and active muscle mechanics. After mice were anesthetized and the diaphragm or the biceps femoris hindlimb muscle was excised, passive length-tension relationships, stress-relaxation curves, or isometric contractile properties were determined with an in vitro biaxial mechanical testing apparatus. Compared with controls, extensibility was smaller in the muscle fiber direction and the transverse fiber direction of the mutant mice. The relaxed elastic modulus was smaller in merosin-deficient diaphragms compared with controls. Interestingly, maximal muscle tetanic stress was depressed in muscles from the mutant mice during uniaxial loading but not during biaxial loading. However, presence of transverse passive stretch increases maximal contractile stress in both the mutant and normal mice. Our data suggest that merosin contributes to muscle passive stiffness, viscoelasticity, and contractility and that the mechanism by which force is transmitted between adjacent myofibers via merosin possibly in shear.
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Wang, Lidong, Xiongqi Peng, and Mingrui Liu. "Development and application of hyperelastic model for diaphragm considering the influence of temperature." International Journal of Computational Materials Science and Engineering 08, no. 03 (September 2019): 1950010. http://dx.doi.org/10.1142/s2047684119500106.
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The basic mechanical properties of a diaphragm under various temperatures in hot diaphragm preforming of composites are obtained by uniaxial tensile tests. A constitutive model considering the influence of temperature is accordingly developed to characterize its large deformation behavior. Model parameters are obtained by nonlinear fitting experiment data. The constitutive model is implemented in ABAQUS through the user material subroutine UHYPER. The developed constitutive model is verified by simulating the covering deformation of the diaphragm over a C-type mold. Finally, as an application of the developed hyperelastic model, an optimal design of a support bar in the hot diaphragm preforming process is implemented. The constitutive model lays a solid foundation for the finite element simulation and process optimization of the hot diaphragm forming (HDF) of carbon composites.
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Reid, M. B., H. A. Feldman, and M. J. Miller. "Isometric contractile properties of diaphragm strips from alcoholic rats." Journal of Applied Physiology 63, no. 3 (September 1, 1987): 1156–64. http://dx.doi.org/10.1152/jappl.1987.63.3.1156.
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Chronic ethanol consumption alters the structure and function of human respiratory muscle. We have examined its effect on the active and passive mechanical properties of rat diaphragm strips in vitro. We conditioned eight rats using a liquid diet containing ethanol as 36% of calories. Eight control rats were pair-fed an isocaloric, ethanol-free liquid diet. Rats were killed after 23 wk. Two strips from the left hemidiaphragm were suspended in Krebs-Ringers solution at 25 degrees C, equilibrated with 5% CO2–95% O2. Isometric stresses were calculated from force transducer measurements. Strips were stimulated directly at supramaximal voltage. Twitch stress (Pt), measured at optimal length (Lo), was greater in ethanol-conditioned strips: 5.1 vs. 3.8 N/cm2. Times to peak Pt and twitch half-relaxation times were equal. Tetanic stress at Lo (Po) was also greater after ethanol conditioning: 17.2 vs. 12.8 N/cm2. Pt/Po ratios were equal. Expressed as %Po, tetanic stress-stimulation frequency curves and tetanic stress-length curves were identical. Ethanol-conditioned strips were marginally less compliant when passively stretched to lengths between Lo and 130% Lo. We postulate that ethanol may have increased active stress development by reducing intracellular free water.
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Harwood, C. L., I. S. Young, D. L. Lee, and J. D. Altringham. "The effect of Trichinella spiralis infection on the mechanical properties of the mammalian diaphragm." Parasitology 113, no. 6 (December 1996): 535–43. http://dx.doi.org/10.1017/s0031182000067585.
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SUMMARYTrichinella spiralis larvae infect and develop within skeletal muscle cells causing major changes to their mechanical properties. The aim of this investigation was to determine the effects of T. spiralis on the power output and fatigue resistance of the mammalian diaphragm under conditions simulating in vivo operation and to relate these to respiratory performance. Infection with T. spiralis leads to major reductions in mechanical stress, work, power output and fatigue resistance. These changes are associated with the number of larvae present in the muscle and the duration of infection. However, the initial decline in mechanical performance occurs during the onset of infection when there are few larvae observed within the muscle cells, indicating that T. spiralis may affect the properties of muscle before encapsulation. This may correspond to the host's inflammatory response and the effects of larval excretory/secretory products. The decline in mechanical performance will have a profound effect on respiration both at rest and during exertion. This must influence the behaviour of the host and increase its chance of capture by predators, which is likely to benefit the parasite by facilitating its transmission.
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Marsi, Noraini, Majlis Burhanuddin Yeop, Azrul Azlan Hamzah, and Faisal Mohd-Yasin. "Growth and Characterization of (100) and (111) 3C-SiC Thin Film for MEMS Capacitive Pressure Sensor for Extreme Environments." Advanced Materials Research 1024 (August 2014): 356–59. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.356.
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The (100) and (111) crystalline cubic silicon nitride (3C-SiC) thin films have been epitaxially deposited on (100) silicon substrate with the thickness of 0.5 µm and 1.0 µm. The effects of the different growth of 3C-SiC are considered as the most critical factor in determining the mechanical properties by comparing with bulk value such as Young’s modulus (~455 GPa) and hardness (~42 GPa). This paper evaluates the mechanical characteristic of the 3C-SiC-on-Si wafers to improve the 3C-SiC thin film quality. The aim is to employ the thin film as the flexible diaphragm in the MEMS capacitive pressure sensor for extreme environment. The surface morphology of thin layer of grown 3C-SiC wafers are characterized by X-ray diffraction (XRD), Infinite Focus Microscopy (IFM), scanning electron microscopy (SEM) and nano-indentation test. The results show the superior mechanical strengths of both (100) and (111) 3C-SiC thin films over (100) Si. To conclude, these results show that (100) and (111) 3C-SiC are indeed high quality thin film mechanically compare to (100) Si thin film, and is suitable to employed as the flexible diaphragm of the MEMS capacitive pressure sensor for extreme environments.
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Heldt, G. P., and M. B. McIlroy. "Distortion of chest wall and work of diaphragm in preterm infants." Journal of Applied Physiology 62, no. 1 (January 1, 1987): 164–69. http://dx.doi.org/10.1152/jappl.1987.62.1.164.
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Chest wall distortion is common in infants and is especially visible in preterm infants. It has been suggested that this distortion increases the volume displacement of the diaphragm during inspiration, which may be associated with muscular fatigue and apnea. We studied 10 preterm infants who had no evidence of lung disease, investigating the effect of chest wall distortion on the volume displacement and work of the diaphragm. The volume changes of the respiratory system were partitioned using an inductance plethysmograph. The minute volume displacement and the work of the diaphragm were calculated using the partitioned abdominal volume change and the gastric and esophageal pressures. The paradoxical movement of the chest wall lasted an average of 36% of inspiration. The minute volume displacement of the diaphragm ranged from 72 to 176% of the minute pulmonary ventilation, and diaphragmatic work ranged from 94 to 793% of that performed on the lungs. The amount of chest wall distortion, as reflected by the duration of the paradoxical chest wall movement, the minute volume excursion, or work of the diaphragm, was not related to the mechanical properties of the lungs. This estimated work load may represent a significant expenditure of calories in these infants and may contribute to the development of diaphragmatic fatigue, apnea, and a prolonged need for mechanical ventilation.
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Njeugna, E., C. M. Kopp, and J. L. Eichhorn. "Modal analysis of the diaphragm of the semicircular canal." Journal of Vestibular Research 11, no. 1 (February 1, 2001): 43–54. http://dx.doi.org/10.3233/ves-2001-11105.
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The aim of this paper is to determine the domain of validity of calculated quasi-static deformations of the cupula and of ciliar deflections on the crista ampullaris. Several three-dimensional models of the isolated ampullar diaphragm of the human semicircular canal and of that of the frog are studied theoretically by modal analysis. The four first modes of vibration are determined for each structure. Numerical simulations prove that for the first mode of vibration, the cupular deformation has the same shape as that obtained by applying a static pressure difference across the ampullar diaphragm. We studied also the effect of the mechanical properties (Young's modulus and Poisson's coefficient) of the components of the ampullar diaphragm on the vibration modes and their frequencies. The condition, which must be satisfied by the cupular internal viscosity, to have resonance near the natural frequency of the ampullar diaphragm is determined.
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Dick, T. E., and E. van Lunteren. "Fiber subtype distribution of pharyngeal dilator muscles and diaphragm in the cat." Journal of Applied Physiology 68, no. 5 (May 1, 1990): 2237–40. http://dx.doi.org/10.1152/jappl.1990.68.5.2237.
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In previous studies differences were frequently found between the pharyngeal dilator muscles and the thoracic respiratory muscles in their patterns of electrical and mechanical activity during the respiratory cycle, with both resting and stimulated breathing. However, little is known about the intrinsic properties of the pharyngeal muscles and how they relate to the intrinsic properties of the diaphragm. In the present study, the fiber subtype distributions of two pharyngeal dilator muscles, the geniohyoid and the sternohyoid, were ascertained histochemically in the cat. The geniohyoid and the sternohyoid muscles had a preponderance of fast glycolytic (FG) fibers (mean 48 and 55%, respectively), a smaller number of fast oxidative-glycolytic (FOG) fibers (mean 36 and 31%, respectively), and few slow oxidative (SO) fibers (mean 16 and 14%, respectively). The percentages of SO fibers of both hyoid muscles were significantly (P less than 0.01) lower than that of the costal diaphragm, and the percentages of FOG and FG fibers were significantly higher than that of the diaphragm. In conclusion, the geniohyoid and sternohyoid muscles have histochemical characteristics usually associated with fast contraction and intermediate endurance properties.
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Horn, Andrew Gary, Olivia Nicole Kunkel, Dryden Ray Baumfalk, Mikaela Elizabeth Simon, Kiana Marie Schulze, Christian S. Bruells, David C. Poole, and Bradley Jon Behnke. "The Effects of Prolonged Mechanical Ventilation on Structural and Material Properties of Diaphragm Arterioles." FASEB Journal 34, S1 (April 2020): 1. http://dx.doi.org/10.1096/fasebj.2020.34.s1.07354.
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Trabelsi, Hassen, Nicolas Zerbib, Jean-Michel Ville, and Félix Foucart. "Passive and active acoustic properties of a diaphragm at low Mach number." European Journal of Computational Mechanics 20, no. 1-4 (January 2011): 49–71. http://dx.doi.org/10.3166/ejcm.20.49-71.
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Wilson, T. A. "Mechanics of compartmental models of the chest wall." Journal of Applied Physiology 65, no. 5 (November 1, 1988): 2261–64. http://dx.doi.org/10.1152/jappl.1988.65.5.2261.
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Standard methods for describing the mechanical properties of a linear elastic system are applied to the two- and three-compartment models of the chest wall. The compliance matrix and the experiments required to determine the entries in this matrix and thereby to describe the mechanical properties of the relaxed chest wall are described. The effective forces exerted by external loads and muscle tension are defined. The formal theory is used to identify relations among variables. From the definition of effective force, it follows that the ratio of the forces exerted by the diaphragm on the rib cage and abdomen is the same as the ratio of the dependence of diaphragm length on rib cage and abdominal volumes. As an example of relations among variables that follow from the symmetry of the compliance matrix, it is shown that the change of gastric pressure caused by raising pleural pressure is related to the change in lung volume caused by changing stomach volume.
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Czopowska-Lewandowicz, Magdalena. "Concrete properties in diaphragm walls embedded in non-cohesive soils." MATEC Web of Conferences 174 (2018): 01007. http://dx.doi.org/10.1051/matecconf/201817401007.
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Although diaphragm walls are massive and responsible structures whose building history has many years' tradition, the discovery of a variety of material faults is still common throughout their exploitation. Some of the most common ones are associated with the occurrence of leaks along the wall surface. This paper reports on the results of a study conducted into concrete quality in an existing building structure. The issues identified in this case include the potential penetration of groundwater and particles suspended in non-cohesive soils into the bentonite suspension and into the concrete mixture. The scope of the analysis also involved the possible occurrence of a mixing zone of bentonite suspension with the concrete mixture. The solutions presented in this paper were practically tested using an existing structure and the results confirm that the adopted approach needs to be thoroughly researched. The laboratory specimens derived from an unreinforced diaphragm wall were subjected to the following tests: concrete bulk density in the air-dried state, water absorption by concrete, depth of water penetration under pressure, compressive strength and determination of the quantitative phase composition test using X-ray diffraction method. The results clearly demonstrate the decrease of the concrete quality applied in a monolithic diaphragm wall in comparison to the reference samples taken at the phase when it was built. Due to the fact that it was impossible to identify the impact of the particular variables on the investigated structure, this paper focuses on their descriptive assessment. This discussion is based on the analysis of the results defining the physical and mechanical properties of the examined concrete coupled with observations made by the author and insights derived from literature.
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Mehmood, Zahid, Ibraheem Haneef, and Florin Udrea. "Material selection for optimum design of MEMS pressure sensors." Microsystem Technologies 26, no. 9 (October 30, 2019): 2751–66. http://dx.doi.org/10.1007/s00542-019-04601-1.
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Abstract Choice of the most suitable material out of the universe of engineering materials available to the designers is a complex task. It often requires a compromise, involving conflicts between different design objectives. Materials selection for optimum design of a Micro-Electro-Mechanical-Systems (MEMS) pressure sensor is one such case. For optimum performance, simultaneous maximization of deflection of a MEMS pressure sensor diaphragm and maximization of its resonance frequency are two key but totally conflicting requirements. Another limitation in material selection of MEMS/Microsystems is the lack of availability of data containing accurate micro-scale properties of MEMS materials. This paper therefore, presents a material selection case study addressing these two challenges in optimum design of MEMS pressure sensors, individually as well as simultaneously, using Ashby’s method. First, data pertaining to micro-scale properties of MEMS materials has been consolidated and then the Performance and Material Indices that address the MEMS pressure sensor’s conflicting design requirements are formulated. Subsequently, by using the micro-scale materials properties data, candidate materials for optimum performance of MEMS pressure sensors have been determined. Manufacturability of pressure sensor diaphragm using the candidate materials, pointed out by this study, has been discussed with reference to the reported devices. Supported by the previous literature, our analysis re-emphasizes that silicon with 110 crystal orientation [Si (110)], which has been extensively used in a number of micro-scale devices and applications, is also a promising material for MEMS pressure sensor diaphragm. This paper hence identifies an unexplored opportunity to use Si (110) diaphragm to improve the performance of diaphragm based MEMS pressure sensors.
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Lee, Sang Joo, Seung Woo Han, Jae Hyun Kim, and Hak Joo Lee. "Measurement of Mechanical Properties for Thin Film Using Visual Image Tracing Method." Solid State Phenomena 124-126 (June 2007): 1701–4. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.1701.
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It is quite difficult to accurately measure the mechanical properties of thin films. Currently, there are several methods (or application) available for measuring mechanical properties of thin films. Their properties, however, have been determined by indirect methods such as cantilever beam test and diaphragm bulge test. This paper reports the efforts to develop a direct strain measurement system for micro/nano scale thin film materials. The proposed solution is the Visual Image Tracing (VIT) strain measurement system coupled with a micro tensile testing unit, which consists of a piezoelectric actuator, load cell, microscope and CCD cameras. The advantage of this system is the ability to monitor the real time images of specimen during the test in order to determine its Young’s modulus and Poisson’s ratio at the same time. Stress-strain curve, Young’s modulus, yield strength and Poisson’s ratio of copper thin film measured using VIT system are presented.
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Jiang, Shuyong, Lihong Zhao, and Guixiang Wu. "Prediction of mechanical properties of 50CrVA tempered steel strip for horn diaphragm based on BPANN." Journal of Wuhan University of Technology-Mater. Sci. Ed. 24, no. 5 (October 2009): 791–95. http://dx.doi.org/10.1007/s11595-009-5791-0.
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Chen, Dyi-Cheng, Ming-Fei Chen, Chih-Hsuan Pan, and Jun-Yan Pan. "Study of membrane restrictors in hydrostatic bearing." Advances in Mechanical Engineering 10, no. 9 (September 2018): 168781401879960. http://dx.doi.org/10.1177/1687814018799604.
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Hydrostatic guides or bearings are very important crucial components in precision mechanical system. First, the article selects the structural parameters of the standard design film restrictor with regard to hydrostatic bearing. Moreover, using COMSOL, the article performs the fluid–structure interaction analysis of the diaphragm to obtain pressure and stress field distribution, and the deformation of diaphragm in membrane restrictors. Then, fluid resistance and other related properties of the membrane restrictors are obtained, and the related parameters including oil pressure, restrictor gap, membrane thickness, and membrane restrictors to perform feedback action of different oils are explored. Finally, the simulation results and experimental measurements are compared to verify their feasibility. In this study, an oil pressure of 10 bar induced deformation of the membrane with consistent trend; however, oil pressures of 30 and 50 bar induced large error with the same trend.
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Zhu, Ercheng, Catherine S. H. Sassoon, Renee Nelson, H. Tony Pham, Lei Zhu, Michael J. Baker, and Vincent J. Caiozzo. "Early effects of mechanical ventilation on isotonic contractile properties and MAF-box gene expression in the diaphragm." Journal of Applied Physiology 99, no. 2 (August 2005): 747–56. http://dx.doi.org/10.1152/japplphysiol.00126.2005.
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This study aimed to determine the time-dependent effects of diaphragmatic inactivity on its maximum shortening velocity ( Vmax) and the muscle atrophy F-box (MAF-box, atrogin-1) gene expression during controlled mechanical ventilation (CMV). Twenty-four New Zealand White rabbits were grouped into 1 day, 2 days, and 3 days of CMV and controls in equal numbers. The in vitro isotonic contractile properties of the diaphragm were determined. In addition, myosin heavy chain protein and mRNA, myosin light chain, MAF-box mRNA, and volume density of abnormal myofibrils were measured. Tetanic force decreased, and Vmax increased from control of 6.4 to 6.6, 7.7, and 8.1 muscle lengths per second after 1, 2, and 3 days of CMV, respectively ( P < 0.02). The increased Vmax compensated for the decreased tetanic force; consequently, compared with the controls, maximum power output was unchanged after 3 days of CMV. Vmax correlated with the volume density of abnormal myofibrils [ y = 0.1 x + 5.7 ( r = 0.87, P < 0.01)]. In the diaphragm, MAF-box was overexpressed (355% of control) after 1 day of CMV, before the evidence of structural myofibril disarray. In conclusion, CMV produced a time-dependent increase in Vmax that was associated with the degree of myofibrillar disarray and independent of changes in myosin isoform expression. Furthermore, CMV produced an increase in MAF-box mRNA levels that may be partially or completely responsible for the degree of myofibrillar disarray resulting from CMV.
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Orliaguet, Gilles, Olivier Langeron, Belaid Bouhemad, Pierre Coriat, Yves LeCarpentier, and Bruno Riou. "Effects of postnatal maturation on energetics and cross-bridge properties in rat diaphragm." Journal of Applied Physiology 92, no. 3 (March 1, 2002): 1074–82. http://dx.doi.org/10.1152/japplphysiol.00613.2001.
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The effects of maturation on cross-bridge (CB) properties were studied in rat diaphragm strips obtained at postnatal days 3, 10, and 17 and in adults (10–12 wk old). Calculations of muscle energetics and characteristics of CBs were determined from standard Huxley equations. Maturation did not change the curvature of the force-velocity relationship or the peak of mechanical efficiency. There was a significant increase in the total number of CBs per cross-sectional area (m) with aging but not in single CB force. The turnover rate of myosin ATPase increased, the duration of the CB cycle decreased, and the velocity of CBs decreased significantly only after the first week postpartum. There was a linear relationship between maximum total force and m ( r = 0.969, P < 0.001), and between maximum unloaded shortening velocity and m ( r = 0.728, P < 0.001). When this study in the rat and previous study in the hamster are compared, it appears that there are few species differences in the postnatal maturation process of the diaphragm.
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Lee, Sung Hyuk, Seok Heo, Cheol Woong Kim, and Kwang Joon Yoon. "The Characteristic Analysis of a Piezoelectric Actuator for Valveless Micropumps." Key Engineering Materials 326-328 (December 2006): 1511–14. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.1511.
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The behavior of a circular piezoelectric actuator for volumetric micropump has been investigated by using theoretical and finite element analyses. A modified theoretical model was developed to predict the behavior of a piezoelectric actuator induced by the applied voltage. The theoretical results for the diaphragm deflection were in good agreement with the results from numerical simulation. Based on the theoretical analysis, the effects of several important parameters on actuation performance have been investigated. These parameters include the dimensions and mechanical properties of the piezoelectric disk, bonding layer and elastic diaphragm materials. Consequently, it is thought that above theoretical model might be employed as a tool for design and optimization of the piezoelectric actuator for micropump application.
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Zhiming, Ye, and Yeh Kaiyuan. "A Study of Belleville Spring and Diaphragm Spring in Engineering." Journal of Applied Mechanics 57, no. 4 (December 1, 1990): 1026–31. http://dx.doi.org/10.1115/1.2897621.
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This paper deals with the static response of a Belleville spring and a diaphragm spring by using the finite rotation and large deflection theories of a beam and conical shell, and an experimental method as well. The authors propose new mechanical analysis mathematical models. The exact solution of a variable width cantilever beam is obtained. By using the integral equation method and the iterative method to solve the simplified equations and Reissner’s equations of finite rotation and large deflection of a conical shell, this paper has calculated a great number of numerical results. The properties of loads, strains, stresses and displacements, and the distribution rules of strains and stresses of diaphragm springs are investigated in detail by means of the experimental method. The unreasonableness of several assumptions in traditional theories and calculating method is pointed out.
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HAYASHI, K., T. MATSUDA, H. TAKANO, M. UMEZU, Y. TAENAKA, and T. NAKAMURA. "Effects of implantation on the mechanical properties of the Polyurethane diaphragm of left ventricular assist devices." Biomaterials 6, no. 2 (March 1985): 82–88. http://dx.doi.org/10.1016/0142-9612(85)90068-7.
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Bruells, Christian S., Ashley J. Smuder, Lucy K. Reiss, Matthew B. Hudson, William Bradley Nelson, Michael P. Wiggs, Kurt J. Sollanek, Rolf Rossaint, Stefan Uhlig, and Scott K. Powers. "Negative Pressure Ventilation and Positive Pressure Ventilation Promote Comparable Levels of Ventilator-induced Diaphragmatic Dysfunction in Rats." Anesthesiology 119, no. 3 (September 1, 2013): 652–62. http://dx.doi.org/10.1097/aln.0b013e31829b3692.
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Abstract Background: Mechanical ventilation is a life-saving intervention for patients with respiratory failure. Unfortunately, a major complication associated with prolonged mechanical ventilation is ventilator-induced diaphragmatic atrophy and contractile dysfunction, termed ventilator-induced diaphragmatic dysfunction (VIDD). Emerging evidence suggests that positive pressure ventilation (PPV) promotes lung damage (ventilator-induced lung injury [VILI]), resulting in the release of signaling molecules that foster atrophic signaling in the diaphragm and the resultant VIDD. Although a recent report suggests that negative pressure ventilation (NPV) results in less VILI than PPV, it is unknown whether NPV can protect against VIDD. Therefore, the authors tested the hypothesis that compared with PPV, NPV will result in a lower level of VIDD. Methods: Adult rats were randomly assigned to one of three experimental groups (n = 8 each): (1) acutely anesthetized control (CON), (2) 12 h of PPV, and (3) 12 h of NPV. Dependent measures included indices of VILI, diaphragmatic muscle fiber cross-sectional area, diaphragm contractile properties, and the activity of key proteases in the diaphragm. Results: Our results reveal that no differences existed in the degree of VILI between PPV and NPV animals as evidenced by VILI histological scores (CON = 0.082 ± 0.001; PPV = 0.22 ± 0.04; NPV = 0.25 ± 0.02; mean ± SEM). Both PPV and NPV resulted in VIDD. Importantly, no differences existed between PPV and NPV animals in diaphragmatic fiber cross-sectional area, contractile properties, and the activation of proteases. Conclusion: These results demonstrate that NPV and PPV result in similar levels of VILI and that NPV and PPV promote comparable levels of VIDD in rats.
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Breuer, Thomas, Christian Bleilevens, Rolf Rossaint, Gernot Marx, Julian Gehrenkemper, Henning Dierksen, Antoine Delpierre, Joachim Weis, Ghislaine Gayan-Ramirez, and Christian S. Bruells. "Dexmedetomidine Impairs Diaphragm Function and Increases Oxidative Stress but Does Not Aggravate Diaphragmatic Atrophy in Mechanically Ventilated Rats." Anesthesiology 128, no. 4 (April 1, 2018): 784–95. http://dx.doi.org/10.1097/aln.0000000000002081.
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Abstract Background Anesthetics in ventilated patients are critical as any cofactor hampering diaphragmatic function may have a negative impact on the weaning progress and therefore on patients’ mortality. Dexmedetomidine may display antioxidant and antiproteolytic properties, but it also reduced glucose uptake by the muscle, which may impair diaphragm force production. This study tested the hypothesis that dexmedetomidine could inhibit ventilator-induced diaphragmatic dysfunction. Methods Twenty-four rats were separated into three groups (n = 8/group). Two groups were mechanically ventilated during either dexmedetomidine or pentobarbital exposure for 24 h, referred to as interventional groups. A third group of directly euthanized rats served as control. Force generation, fiber dimensions, proteolysis markers, protein oxidation and lipid peroxidation, calcium homeostasis markers, and glucose transporter–4 (Glut-4) translocation were measured in the diaphragm. Results Diaphragm force, corrected for cross-sectional area, was significantly decreased in both interventional groups compared to controls and was significantly lower with dexmedetomidine compared to pentobarbital (e.g., 100 Hz: –18%, P < 0.0001). In contrast to pentobarbital, dexmedetomidine did not lead to diaphragmatic atrophy, but it induced more protein oxidation (200% vs. 73% in pentobarbital, P = 0.0015), induced less upregulation of muscle atrophy F-box (149% vs. 374% in pentobarbital, P < 0.001) and impaired Glut-4 translocation (–73%, P < 0.0005). It activated autophagy, the calcium-dependent proteases, and caused lipid peroxidation similarly to pentobarbital. Conclusions Twenty-four hours of mechanical ventilation during dexmedetomidine sedation led to a worsening of ventilation-induced diaphragm dysfunction, possibly through impaired Glut-4 translocation. Although dexmedetomidine prevented diaphragmatic fiber atrophy, it did not inhibit oxidative stress and activation of the proteolytic pathways.
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Dias, Cristina Márcia, Caroline P. Pássaro, Viviane Ramos Cagido, Marcelo Einicker-Lamas, Jennifer Lowe, Elnara M. Negri, Vera L. Capelozzi, Walter A. Zin, and Patricia R. M. Rocco. "Effects of undernutrition on respiratory mechanics and lung parenchyma remodeling." Journal of Applied Physiology 97, no. 5 (November 2004): 1888–96. http://dx.doi.org/10.1152/japplphysiol.00091.2004.
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Undernutrition thwarts lung structure and function, but there are disagreements about the behavior of lung mechanics in malnourished animals. To clarify this issue, lung and chest wall mechanical properties were subdivided into their resistive, elastic, and viscoelastic properties in nutritionally deprived (ND) rats and correlated with the data gathered from histology (light and electron microscopy and elastic fiber content), and bronchoalveolar lavage fluid analysis (lipid and protein content). Twenty-four Wistar rats were assigned into two groups. In the control (Ctrl) group the animals received food ad libitum. In the ND group, rats received one-third of their usual daily food consumption until they lost 40% of their initial body weight. Lung static elastance, viscoelastic and resistive pressures (normalized by functional residual capacity), and chest wall pressures were higher in the ND group than in the Ctrl group. The ND group exhibited patchy atelectasis, areas of emphysema, interstitial edema, and reduced elastic fiber content. The amount of lipid and protein in bronchoalveolar lavage fluid was significantly reduced in the ND group. Electron microscopy showed 1) type II pneumocytes with a reduction in lamellar body content, multilamellated structures, membrane vesicles, granular debris, and structurally aberrant mitochondria; and 2) diaphragm and intercostals with atrophy, disarrangement of the myofibrils, and deposition of collagen type I fibers. In conclusion, undernutrition led to lung and chest wall mechanical changes that were the result from a balance among the following modifications: 1) distorted structure of diaphragm and intercostals, 2) surfactant content reduction, and 3) decrease in elastic fiber content.