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1
Chen, Xiaoxiao, Javier A. Sala-Mercado, Robert L. Hammond, Masashi Ichinose, Soroor Soltani, Ramakrishna Mukkamala, and Donal S. O'Leary. "Dynamic control of maximal ventricular elastance via the baroreflex and force-frequency relation in awake dogs before and after pacing-induced heart failure." American Journal of Physiology-Heart and Circulatory Physiology 299, no. 1 (July 2010): H62—H69. http://dx.doi.org/10.1152/ajpheart.00922.2009.
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We investigated to what extent maximal ventricular elastance ( Emax) is dynamically controlled by the arterial baroreflex and force-frequency relation in conscious dogs and to what extent these mechanisms are attenuated after the induction of heart failure (HF). We mathematically analyzed spontaneous beat-to-beat hemodynamic variability. First, we estimated Emax for each beat during a baseline period using the ventricular unstressed volume determined with the traditional multiple beat method during vena cava occlusion. We then jointly identified the transfer functions (system gain value and time delay per frequency) relating beat-to-beat fluctuations in arterial blood pressure (ABP) to Emax (ABP→ Emax) and beat-to-beat fluctuations in heart rate (HR) to Emax (HR→ Emax) to characterize the dynamic properties of the arterial baroreflex and force-frequency relation, respectively. During the control condition, the ABP→ Emax transfer function revealed that ABP perturbations caused opposite direction Emax changes with a gain value of −0.023 ± 0.012 ml−1, whereas the HR→ Emax transfer function indicated that HR alterations caused same direction Emax changes with a gain value of 0.013 ± 0.005 mmHg·ml−1·(beats/min)−1. Both transfer functions behaved as low-pass filters. However, the ABP→ Emax transfer function was more sluggish than the HR→ Emax transfer function with overall time constants (indicator of full system response time to a sudden input change) of 11.2 ± 2.8 and 1.7 ± 0.5 s ( P < 0.05), respectively. During the HF condition, the ABP→ Emax and HR→ Emax transfer functions were markedly depressed with gain values reduced to −0.0002 ± 0.007 ml−1 and −0.001 ± 0.004 mmHg·ml−1·(beats/min)−1 ( P < 0.1). Emax is rapidly and significantly controlled at rest, but this modulation is virtually abolished in HF.
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Igarashi, Y., Y. Goto, O. Yamada, T. Ishii, and H. Suga. "Transient vs. steady end-systolic pressure-volume relation in dog left ventricle." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 5 (May 1, 1987): H998—H1004. http://dx.doi.org/10.1152/ajpheart.1987.252.5.h998.
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We compared transient slope of end-systolic pressure-volume line (T-Emax) with steady Emax (S-Emax) in isolated cross-circulated canine left ventricles. T-Emax is the slope of the end-systolic pressure-volume line (ESPVL) determined from the last steady-state ejecting contraction (SEC) and the first transient isovolumic contraction produced by end-diastolic volume clamp. S-Emax is the slope of ESPVL determined from five steady-state contractions by linear regression analysis. We obtained three T-Emax values in the same contractile state by changing ejection fraction (EF) of SEC to three levels (range 14-58%) from the same end-diastolic volume. T-Emax variably increased with EF in any contractile state. The ratios of the three T-Emax values to the same S-Emax value was 1.08 +/- 0.04 (11 ventricles, means +/- SE) for high EF, 0.87 +/- 0.06 for middle EF, and 0.69 +/- 0.07 for low EF in control contractile state. These ratios decreased under epinephrine and increased under propranolol. We conclude that T-Emax depends not only on EF but also on contractile state in isolated dog left ventricles.
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Tanaka, N., Y. Yasumura, T. Nozawa, S. Futaki, M. Uenishi, K. Hiramori, and H. Suga. "Optimal contractility and minimal oxygen consumption for constant external work of heart." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 254, no. 6 (June 1, 1988): R933—R943. http://dx.doi.org/10.1152/ajpregu.1988.254.6.r933.
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We theoretically considered the relation between left ventricular O2 consumption (MVO2) and a contractility index (Emax), searching for an optimal Emax that minimizes MVO2 for a given external mechanical work. We used one equation relating Emax with ventricular pressure and volume and another equation relating MVO2 with pressure-volume area (PVA). PVA is theoretically and experimentally a good predictor of MVO2 with Emax as a parameter. Then we could theoretically show the existence of the optimal Emax. For example, MVO2 was minimized to 8.9 ml O2.min-1.100 g-1 at an Emax of 6.3 mmHg.ml-1.100 g when cardiac output was 1.2 l/min, afterload pressure was 100 mmHg, and heart rate was 150 beats/min. These values can be observed experimentally in a 10- to 15-kg dog. Optimal Emax values for a wide range of external work fall in the middle of the normal working range of Emax. Thus our MVO2-PVA-Emax relationship supports the contemporary concept of the optimal contractility that MVO2 for a given cardiac external work is minimum at a middle level of ventricular contractility.
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Winn, M. J., B. Vallet, N. K. Asante, S. E. Curtis, and S. M. Cain. "Effects of NG-substituted arginines on coronary vascular function after endotoxin." Journal of Applied Physiology 75, no. 1 (July 1, 1993): 424–31. http://dx.doi.org/10.1152/jappl.1993.75.1.424.
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We investigated the responses of canine coronary rings to endothelium-derived relaxing factor-nitric oxide- (EDRF-NO) dependent agonists and NO synthase (NOS) inhibitors 3 h after endotoxic shock was induced in dogs by lipopolysaccharide infusion (LPS; 2 mg/kg). EDRF-NO-dependent relaxation to thrombin [control maximum response produced after administration of thrombin (Emax) was -85.2 +/- 7.0% of the constrictor response produced by the thromboxane analogue U-46619], acetylcholine (control Emax -88.4 +/- 3.4%), or bradykinin (control Emax -80.5 +/- 2.2%) was not inhibited by LPS (Emax thrombin -75.9 +/- 9.5%; Emax acetylcholine -90.2 +/- 2.4%; Emax bradykinin -91.6 +/- 3.4%). The NOS inhibitor NG-monomethyl-L-arginine (L-NMMA) (10(-6)-3 x 10(-4) M) caused constriction of rings with endothelium (Emax 36.3 +/- 5.6%), an effect that was greater after LPS (Emax 59.2 +/- 4.1%; P < 0.05). D-NMMA had no effect in control, but it increased tension after LPS (Emax 20.8 +/- 9.7%). Contrary to expectations, L- and D-NMMA relaxed endothelium-denuded rings (-30.4 +/- 8.7% L-NMMA; -45.1 +/- 11.7% D-NMMA; P < 0.05). However, neither agent caused relaxation after in vivo LPS (10.2 +/- 3.4% L-NMMA; 8.9 +/- 5.2% D-NMMA). N omega-nitro-L-arginine-methylester (L-NAME) and nitro-L-arginine (10(-6)-3 x 10(-4) M) increased tension (Emax 82.3 +/- 23.9 and 73.1 +/- 8.8%, respectively) but only when endothelium was present, and the increases were no greater in LPS-treated groups than in controls (with LPS: Emax L-NAME 87.3 +/- 16.5%; Emax nitro-L-arginine 65.7 +/- 3.3%).(ABSTRACT TRUNCATED AT 250 WORDS)
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Suthiwong, Jittra, Kampeebhorn Boonloh, Veerapol Kukongviriyapan, and Chavi Yenjai. "Cytotoxicity against Cholangiocarcinoma and HepG2 Cell Lines of Lignans from Hernandia nymphaeifolia." Natural Product Communications 13, no. 1 (January 2018): 1934578X1801300. http://dx.doi.org/10.1177/1934578x1801300118.
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Eleven lignans (1-11) were isolated from the seed of Hernandia nymphaeifolia. Most of the lignans exhibited strong to moderate cytotoxicity against cholangiocarcinoma KKU-M156 and HepG2 cell lines. Compounds 4 and 8 showed cytotoxicity against the KKU-M156 cell line with IC50 values of 5.2 μ M (Emax 96%) and 5.4 (Emax 59%) μM, respectively. In the cases of cytotoxicity against the HepG2 cell line, compounds 2, 3, 4, and 8 showed cytotoxicity with IC50 values of 1.7 M (Emax 84%), 4.1 μM (Emax 74%), 4.5 μM (Emax 68%), and 5.2 μM (Emax 78%), respectively.
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Sánchez-Recillas, Amanda, Ana Ly Arroyo-Herrera, Jesús Alfredo Araujo-León, Emanuel Hernández Núñez, and Rolffy Ortiz Andrade. "Spasmolytic and Antibacterial Activity of TwoCitrus sinensisOsbeck Varieties Cultivated in Mexico." Evidence-Based Complementary and Alternative Medicine 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/3960837.
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Antibacterial activity on ATCC strains ofEscherichia coli,Salmonella enterica,Salmonella enteritidis,andSalmonella choleraesuisand spasmolytic effect on contraction on rat ileum trips were determinate. Eight organic extracts (hexanic and methanolic) of albedo (mesocarp) and flavedo (pericarp) of two varieties (Valencian and National) ofCitrus sinensis(L.) Osbeck of Yucatán, México, were studied. Additionally, chromatographic fingerprints were obtained and correlated with their pharmacological effects. MAN, MAV, and HFN extract caused inhibition againstS. choleraesuis(MIC: 1000 µg/mL) andS. enteritidis(MIC: 1000µg/mL). Regarding the spasmolytic effect, the Valencian extracts variety was more efficient on spontaneous contraction, HAV (Emax=51.98±1.98%), MAV (Emax=35.98±1.42%), HFV (Emax=68.91±4.14%), and MFV (Emax=51.28±2.59%), versus National variety, HAN (Emax=43.80±6.32%), MAN (Emax=14.62±1.69%), HFN (Emax= 64.87 ± 3.04%), and MFN (Emax=31.01±3.92%). Chromatographic fingerprints of HFV and HFN were found to have some similar signals that belong to monoterpenes, whereas for HAN and HAV similar signals were found belonging to fatty acids and triterpenoids. Methanolic extracts showed signals of (1) furfural, (2) furfural acetone (3) furfuraldehyde and (4)β–sitosterol compounds. Flavedo portion ofC. sinensispossessed spasmolytic effect on rat ileum strips and antibacterial activity againstSalmonellastrains. This species is source for obtaining bioactive compounds with therapeutic potential in the treatment of infectious diarrhea.
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Sala-Mercado, Javier A., Mohsen Moslehpour, Robert L. Hammond, Masashi Ichinose, Xiaoxiao Chen, Sell Evan, Donal S. O'Leary, and Ramakrishna Mukkamala. "Stimulation of the cardiopulmonary baroreflex enhances ventricular contractility in awake dogs: a mathematical analysis study." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 307, no. 4 (August 15, 2014): R455—R464. http://dx.doi.org/10.1152/ajpregu.00510.2013.
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The cardiopulmonary baroreflex responds to an increase in central venous pressure (CVP) by decreasing total peripheral resistance and increasing heart rate (HR) in dogs. However, the direction of ventricular contractility change is not well understood. The aim was to elucidate the cardiopulmonary baroreflex control of ventricular contractility during normal physiological conditions via a mathematical analysis. Spontaneous beat-to-beat fluctuations in maximal ventricular elastance ( Emax), which is perhaps the best available index of ventricular contractility, CVP, arterial blood pressure (ABP), and HR were measured from awake dogs at rest before and after β-adrenergic receptor blockade. An autoregressive exogenous input model was employed to jointly identify the three causal transfer functions relating beat-to-beat fluctuations in CVP to Emax (CVP → Emax), which characterizes the cardiopulmonary baroreflex control of ventricular contractility, ABP to Emax, which characterizes the arterial baroreflex control of ventricular contractility, and HR to Emax, which characterizes the force-frequency relation. The CVP → Emax transfer function showed a static gain of 0.037 ± 0.010 ml−1 (different from zero; P < 0.05) and an overall time constant of 3.2 ± 1.2 s. Hence, Emax would increase and reach steady state in ∼16 s in response to a step increase in CVP, without any change to ABP or HR, due to the cardiopulmonary baroreflex. Following β-adrenergic receptor blockade, the CVP → Emax transfer function showed a static gain of 0.0007 ± 0.0113 ml−1 (different from control; P < 0.10). Hence, Emax would change little in steady state in response to a step increase in CVP. Stimulation of the cardiopulmonary baroreflex increases ventricular contractility through β-adrenergic receptor system mediation.
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Araki, Junichi, Satoshi Mohri, Gentaro Iribe, Juichiro Shimizu, and Hiroyuki Suga. "Total Ca2+ handling for E-C coupling in the whole heart: An integrative analysis." Canadian Journal of Physiology and Pharmacology 79, no. 1 (January 1, 2001): 87–92. http://dx.doi.org/10.1139/y00-112.
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We assessed total Ca2+ handling (transport, flux) in excitation-contraction (E-C) coupling in a beating left ventricle (LV). We developed a new integrative analysis method that utilizes the internal Ca2+ recirculation fraction (RF), O2 consumption ([Formula: see text]o2) for Ca2+ handling, and O2 cost of Emax (contractility index) of the LV. We obtained the RF from the beat constant of the exponential decay component of the postextrasystolic potentiation, and the O2 cost of Emax from [Formula: see text]o2measured at different Emax. Our equation calculated the unknown total Ca2+ handling, futile Ca2+ cycling, and Ca2+ reactivity of Emax from the RF and Ca2+ handling [Formula: see text]o2. The calculated total Ca2+ handling fell between 30 and 110 µmol/kg, depending on Emax and pathological conditions. Our method also allowed an assessment of futile Ca2+ cycling and Ca2+ reactivity of Emax in a beating LV. These data are not available using conventional methods. Our method can be used to better understand the pathophysiology of total Ca2+ handling in a beating heart.Key words: excitation-contraction coupling, myocardial Ca2+, contractility, cardiac O2 consumption.
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Oktay, Tugrul, Metin Uzun, and Ozturk Ozdemir Kanat. "Maximum lift/drag ratio improvement of TUAVs via small aerodynamic modifications." Aircraft Engineering and Aerospace Technology 90, no. 9 (November 14, 2018): 1438–44. http://dx.doi.org/10.1108/aeat-07-2017-0175.
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Purpose The purpose of this study is to increase maximum lift/drag ratio (Emax) of tactical unmanned aerial vehicles (TUAVs) via applying novel small aerodynamic modifications. Design methodology/approach A TUAV is manufactured in Erciyes University, Faculty of Aeronautics and Astronautics, Model Aircraft Laboratory. It has both passive and active morphing capabilities. Its nosecone and tailcone shapes are redesigned to improve Emax. Moreover, active flow control is also built on its wing for improving Emax. Findings Using these novel small aerodynamic modifications, considerable improvement on Emax is obtained. Research limitations/implications Permission of Directorate General of Civil Aviation in Turkey is required for testing TUAVs in real-time applications. Practical implications Small aerodynamic modifications such as nosecone-tailcone shape modifications and building active flow control on wing are very beneficial for improving Emax of TUAVs. Social implications Small aerodynamic modifications satisfy confidence, high performance and easy utility demands of TUAV users. Originality/value The study will enable the creation of novel approaches to improve Emax value and therefore aerodynamic performance of TUAVs.
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Ohgoshi, Y., Y. Goto, S. Futaki, H. Yaku, and H. Suga. "Sensitivities of cardiac O2 consumption and contractility to catecholamines in dogs." American Journal of Physiology-Heart and Circulatory Physiology 261, no. 1 (July 1, 1991): H196—H205. http://dx.doi.org/10.1152/ajpheart.1991.261.1.h196.
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We studied the effects of plasma catecholamines from the adrenal gland on systolic pressure-volume area (PVA)-independent O2 consumption (VO2) and contractility index (Emax) in the left ventricle of excised cross-circulated dog hearts. PVA is a measure of the total mechanical energy of contraction. Under baseline conditions, the PVA-independent VO2 correlated with plasma catecholamine level in the hearts (r = 0.84). Plasma epinephrine and norepinephrine levels increased gradually from 0.3 and 0.4 ng/ml to 10.3 and 2.7 ng/ml on average during adrenal sympathetic nerve stimulation of support dogs. Simultaneously, Emax and PVA-independent VO2 increased by 240 +/- 127 (SD) and 75 +/- 24%. Although their increases were monotonic in a given heart, their sensitivities to catecholamines were considerably variable among hearts. However, these two sensitivities were correlated (r = 0.96) with each other in the hearts, and the interheart variation of the sensitivity of the PVA-independent VO2 to Emax (i.e., oxygen cost of Emax) was smaller. We conclude that the oxygen cost of Emax is less variable among hearts despite large interheart variations of Emax and VO2 responses to plasma catecholamines.
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Beyar, R., and S. Sideman. "Relating left ventricular dimension to maximum elastance by fiber mechanics." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 251, no. 3 (September 1, 1986): R627—R635. http://dx.doi.org/10.1152/ajpregu.1986.251.3.r627.
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The dependence of the pressure-volume slope, which defines the maximum elastance (Emax) and the zero pressure-volume intercept (Vd) on the size and dimensions of the left ventricle (LV), is theoretically studied, and a normalizing parameter for Emax is suggested for normal and hypertrophied hearts. The study is based on our earlier model of the mechanics of the LV contraction, which assumes a nested-shell spheroidal shape, Streeter's fiber angle distribution, given stress-length and stress-strain rate functions of the sarcomeres, a radial propagation of the electrical activation front, and a windkessel arterial model. The study shows that Emax is linearly related to the maximum force that the optimal length sarcomeres can develop (sigma o), which is a characteristic measure of the contractility. Emax decreases and Vd increases with an increase in ventricular size, at a constant end-diastolic ratio (h/b)ed, where h is the wall thickness, and b is the semiminor axis of the prolate spheroidal LV. When the reference unstressed volume (V0) is held constant and the wall thickness increases, as in pure concentric hypertrophy, Emax decreases slightly and shifts to the left to a lower Vd value. In pure eccentric hypertrophy, wherein chamber size increases while the wall thickness remains constant, Emax decreases and Vd increases. A good index for myocardial function at constant configuration ratio (h/b)ed is obtained by multiplying Emax with the LV muscle volume (Vm). (h/b)ed is constant (= 0.45) for the normal heart but increases for concentric hypertrophy.(ABSTRACT TRUNCATED AT 250 WORDS)
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Yoo, Myung Hi, Hye Jeong Kim, In Ho Choi, Suyeon Park, Sumi Yun, Hyeong Kyu Park, Dong Won Byun, and Kyoil Suh. "Efficacy of Differential Diagnosis of Thyroid Nodules by Shear Wave Elastography, the Stiffness Map." Journal of the Endocrine Society 5, Supplement_1 (May 1, 2021): A860—A861. http://dx.doi.org/10.1210/jendso/bvab048.1757.
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Abstract Background: Fine-needle aspiration (FNA) is the first step in the differential diagnosis of thyroid nodules. However, malignancy rate of the indeterminate FNA is reported as 20-50 %. We aimed to evaluate the efficacy of shear wave elastography (SWE), the map of stiffness in the differential diagnosis of the histopathology of thyroid nodules. Methods: We retrospectively reviewed the medical records of 258 consecutive patients who visited the thyroid clinic for thyroid nodules and who underwent SWE before ultrasound-guided FNA and/or core-needle biopsy. We analyzed the EI using the total nodular region of interest method by the Q-Box Trace program. Thyroid nodules were divided in to 4 categoies according to maximum elasticity (EMax) and nodule depth/width (D/W) ratio; Category 1 (EMax ≥42.6 kPa & D/W<0.9), Category 2 (EMax <42.6 kPa & D/W<0.9), Category 3 (EMax ≥42.6 kPa & D/W≥ 0.9) and Category 4 (EMax<46.2 kPa & D/W≥ 0.9). The cutoff value of EMax was set using ROC curve analysis to predict follicular neoplasm (FN) from nodular hyperplasia (NH). Cutoff value for nodule D/W ratio was set using ROC curve analysis to differentiate malignant nodule. Results: FN showed the lowest EMax among all pathologies and lower EMax than NH (p<0.05). FN was distributed mostly in the category 2 (70%) and NH was distributed mainly in the category 1 (73.9%). CLT belonged mostly to the category 1 (57.1%). PTC belonged in majority to the category 3 (58.9%) and the rest.to the category 1 (25%). So NH was the most frequent pathology group in category 1.FN was the most frequent pathology group in the category 2 and PTC was the most frequent pathology group in the category 3. Conclusion: SWE showed characteristic patterns of various pathology groups reflecting the degree of fibrosis and the information of EMax and nodule depth/width (D/W) ratio determining the category was useful to predict the pathology of thyroid nodules along with the advantage of noninvasiveness.
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Nozawa, T., Y. Yasumura, S. Futaki, N. Tanaka, Y. Igarashi, Y. Goto, and H. Suga. "Relation between oxygen consumption and pressure-volume area of in situ dog heart." American Journal of Physiology-Heart and Circulatory Physiology 253, no. 1 (July 1, 1987): H31—H40. http://dx.doi.org/10.1152/ajpheart.1987.253.1.h31.
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We studied the relation between O2 consumption (VO2) and the systolic pressure-volume area (PVA) in the left ventricle of open-chest dogs. PVA and the slope (Emax) of the end-systolic pressure-volume line were determined by an abrupt occlusion of the ascending aorta. VO2 linearly correlated with PVA in control contractile state, where Emax was 15.8 +/- 4.4 (SD) mmHg/ml with intact reflexes and 11.5 +/- 1.2 mmHg/ml with blocked reflexes. Emax and the VO2 axis intercept of the VO2-PVA line were greater in the in situ heart than in the excised cross-circulated dog heart in our previous study. Enhancement of contractile state by dobutamine increased Emax by 60–80% and shifted the VO2-PVA line upward, increasing the VO2 axis intercept by 38% with intact reflexes and by 79% with blocked reflexes. The slope had a tendency to increase with dobutamine, but the increase was statistically insignificant. We conclude that PVA and Emax obtained by the aortic-occlusion method can account for changes in VO2 with changes in loading conditions and contractility in an in situ dog heart.
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Bogen, D. K., Y. Ariel, T. A. McMahon, and W. H. Gaasch. "Measurement of peak systolic elastance in intact canine circulation with servo pump." American Journal of Physiology-Heart and Circulatory Physiology 249, no. 3 (September 1, 1985): H585—H593. http://dx.doi.org/10.1152/ajpheart.1985.249.3.h585.
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Peak systolic elastance (Emax) was measured in the intact canine circulation by means of a new experimental technique. In this technique the heart is isolated from the circulation during a single systole and subjected to controlled ventricular loads. An electropneumatic aortic occluder is used to isolate the ventricle, and a servo-controlled syringe pump is used to control the ventricular load. Because the experimental load is applied for a single heartbeat only, ventricular function can be measured without the interference of regulatory feedback mechanisms. In eight dogs, weighing 17-42 kg, the relationship between changes in endsystolic pressure and volume was determined from the single-beat application of purely compliant loads. The end-systolic relations were linear, and their slope, Emax, was inversely related to weight. The observed relation between Emax and body weight allows comparisons to be made between different preparations in which Emax has been determined. Values of Emax obtained from the single-beat preparation were found to be 27-74% above those reported in isolated heart preparations and nearly identical to those reported for in vivo or denervated in situ preparations.
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Sun, Yi-Hui, Todd J. Anderson, Kim H. Parker, and John V. Tyberg. "Effects of left ventricular contractility and coronary vascular resistance on coronary dynamics." American Journal of Physiology-Heart and Circulatory Physiology 286, no. 4 (April 2004): H1590—H1595. http://dx.doi.org/10.1152/ajpheart.01100.2001.
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Wave-intensity analysis, which separates upstream from downstream events and defines their interaction, has been used to study the effects of changes in left ventricular (LV) contractility ( Emax) and left circumflex coronary artery resistance ( RLCx) on the coronary systolic flow impediment (CSFI). In 10 anesthetized, open-chest dogs, we measured coronary, aortic, and LV pressures, coronary velocity (Flowire), and flow. Emax was increased by paired pacing and RLCx was modulated by intracoronary infusions of vasodilators (adenosine and nitroglycerin) and a vasoconstrictor (phenylephrine). When both Emax and RLCx were varied, CSFI and the energy of the backward-going compression wave ( IW–) were greatest at the highest levels of Emax and the lowest levels of RLCx. IW– was proportional to the CSFI. We conclude that contractility and coronary resistance change CSFI by modulating the backward-going compression wave.
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Yeih, Dong-Feng, Hung-I. Yeh, Ho-Tsung Hsin, Lian-Yu Lin, Fu-Tien Chiang, Chuen-Den Tseng, Shu-Hsun Chu, and Yung-Zu Tseng. "Dimethylthiourea normalizes velocity-dependent, but not force-dependent, index of ventricular performance in diabetic rats: role of myosin heavy chain isozyme." American Journal of Physiology-Heart and Circulatory Physiology 297, no. 4 (October 2009): H1411—H1420. http://dx.doi.org/10.1152/ajpheart.01269.2008.
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Hydroxyl radicals and hydrogen peroxide are involved in the pathogenesis of systolic dysfunction in diabetic rats, but the precise mechanisms and the effect of antioxidant therapy in diabetic subjects have not been elucidated. We aimed to evaluate the effects of dimethylthiourea (DMTU), a potent hydroxyl radical scavenger, on both force-dependent and velocity-dependent indexes of cardiac contractility in streptozotocin (STZ)-induced early and chronic diabetic rats. Seventy-two hours and 8 wk after STZ (55 mg/kg) injection, diabetic rats were randomized to either DMTU (50 mg·kg−1·day−1 ip) or vehicle treatment for 6 and 12 wk, respectively. All rats were then subjected to invasive hemodynamic studies. Maximal systolic elastance (Emax) and maximum theoretical flow (Qmax) were assessed by curve-fitting techniques in terms of the elastance-resistance model. Both normalized Emax (Emaxn) and afterload-adjusted Qmax (Qmaxad) were depressed in diabetic rats, concomitant with altered myosin heavy chain (MHC) isoform composition and its upstream regulators, such as myocyte enhancer factor-2 (MEF-2) and heart autonomic nervous system and neural crest derivatives (HAND). In chronic diabetic rats, DMTU markedly attenuated the impairment in Qmaxad and normalized the expression of MEF-2 and eHAND and MHC isoform composition but exerted an insignificant benefit on Emaxn. Regarding preventive treatment, DMTU significantly ameliorated both Emaxn and Qmaxad in early diabetic rats. In conclusion, our study shows that DMTU has disparate effects on Qmaxad and Emaxn in chronic diabetic rats. The advantage of DMTU in chronic diabetic rats might involve normalization of MEF-2 and eHAND, as well as reversal of MHC isoform switch.
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Taiba, Abdellah Cherif, Youcef Mahmoudi, Wiebke Baille, Torsten Wichtmann, and Mostefa Belkhatir. "Threshold silt content dependency on particle morphology (shape and size) of granular materials: review with new evidence." Acta Geotechnica Slovenica 18, no. 1 (2021): 28–40. http://dx.doi.org/10.18690/actageotechslov.18.1.28-40.2021.
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The threshold silt content is well known as a key parameter affecting the mechanical response of binary granular assemblies considering particle characteristics (size and shape). In this context, the threshold silt content (TSC) is determined from different laboratory tests based on packing density response (emax and emin versus silt content «Sc») and theoretical approaches proposed by several researchers in the specialized published literature using the characteristics of host sand and silt [emax(sand), emin(sand) , emax(silt) , emin(silt) , Gs , Gf and x]. The analysis of the recorded data indicates that the TSC derived from the (emax) curve appears more reliable than that obtained from the (emin) one. Moreover, it is found that the proposed analytical methods are suitable to quantify the threshold silt content (TSC) than that determined experimentally using the packing density (emax and emin). In addition, the test results show that the new introduced ratios [(D50s×As)/(D50f×Af)] and [(Cus×As)/(Cuf×Af)] determined based on particle characteristics (shape and size) appear as appropriate parameters for predicting the threshold silt content (TSC) of sand-silt mixture of the compiled data from the published literature as well as that of the present research related to Chlef sand, Fontainebleau sand and Hostun sand mixed with Chlef silt.
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Myhre, E. S., A. Johansen, and H. Piene. "Optimal matching between canine left ventricle and afterload." American Journal of Physiology-Heart and Circulatory Physiology 254, no. 6 (June 1, 1988): H1051—H1058. http://dx.doi.org/10.1152/ajpheart.1988.254.6.h1051.
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A parabolic relationship exists between ventricular external work and arterial load at given preload and contractility. Previous data indicate that the working point falls close to the parabola optimum. By combining the left ventricular (LV) end-systolic pressure-volume relationship (ESPVR) and an equation describing external stroke work, optimum values of stroke volume (SV), the slope (Emax) of the ESPVR, and arterial resistance (Rp) corresponding with the optimum (i.e., mSV, mEmax, mRp) were obtained. Experiments in anesthetized dogs were performed to test whether mSV, mEmax, and mRp also correspond to observed SV, Emax, and Rp at three different levels of volume load (right atrial pressure, RAP) before and after acute depression of LV contractility. Comparisons of observed and optimal values of SV, Emax, and Rp were made before and after LV depression. Before embolization, the ratios were SV/mSV 1.10–1.20 (RAP 5–15 mmHg); Emax/mEmax 1.21–1.41; and Rp/mRp 0.84–0.69. After LV depression, SV/mSV was 0.80–0.83, Emax/mEmax was 0.78–0.71, and Rp/mRp was 1.56–1.46. The ratios were all significantly changed (P less than 0.01) by the induced LV depression. The present analysis may offer a new tool to detect nonoptimal relations between cardiac and arterial functions.
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Kim, Hye Jeong, In Ho Choi, So-Young Jin, Hyeong Kyu Park, Dong Won Byun, Kyoil Suh, and Myung Hi Yoo. "Efficacy of Shear-Wave Elastography for Detecting Postoperative Cervical Lymph Node Metastasis in Papillary Thyroid Carcinoma." International Journal of Endocrinology 2018 (September 4, 2018): 1–6. http://dx.doi.org/10.1155/2018/9382649.
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Aims. To evaluate shear-wave elastography (SWE) as a tool to detect postoperative cervical lymph node (LN) metastasis in patients with papillary thyroid carcinoma (PTC). Methods. Forty-three LNs of 43 patients with PTC undergoing ultrasound (US) and SWE before ultrasound-guided fine-needle aspiration (FNA) for the evaluation of postoperative cervical LN recurrences were analyzed. The mean (EMean), minimum (EMin), maximum (EMax), and standard deviation (ESD) of SWE elasticity indices were measured. Results. Among 43 indeterminate or suspicious LNs, 12 were malignant and 31 were benign. The EMean, EMin, EMax, and ESD values were significantly higher in malignant LNs than in benign LNs (EMean: 37.1 kPa in malignant versus 11.8 kPa in benign LNs, P<0.001; EMin: 11.3 kPa versus 5.1 kPa, P=0.046; EMax: 50.5 kPa versus 23.7 kPa, P<0.001; and ESD: 7.8 kPa versus 4.1 kPa, P=0.006). EMax had the highest accuracy (93.0%) when applied with a cut-off value of 37.5 kPa. It had a positive likelihood ratio of 25.83 and a diagnostic odds ratio of 150.0. Conclusions. The shear elasticity index of EMax, with higher likelihood ratios for malignant LNs, may help identify postoperative cervical LN metastasis in PTC patients with indeterminate or suspicious LNs.
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Reid, A. W., B. J. Anderson, M. E. Futter, and N. H. G. Holford. "Relationship of Muscle Strength to Potassium Concentration in a Hypokalaemic Infant." Anaesthesia and Intensive Care 25, no. 5 (October 1997): 525–27. http://dx.doi.org/10.1177/0310057x9702500511.
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A nine-month infant, weighing 9.8 kg, presented with hypotonia secondary to acute hypokalaemia (1.0 mmol/l). Muscle strength improved as the serum potassium was increased. Muscle strength was assessed by the pressure generated inside a saline-filled endotracheal tube cuff during a grasp reflex. Potassium concentration and hand grip strength were related using a sigmoidal Emax model. Zero effect was assumed when the potassium concentration was zero. The Emax, EC50 and Hill coefficient values were determined by non-linear regression using the MKMODEL program. Parameter estimates (SE) were EC50 1.79 (0.15) mmol/l, Hill coefficient 3.79 (0.92), Emax 114.4 (8.9) mmHg.
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Habib, Syed Rashid, Abdulaziz Saud Al Rashoud, Turki Ali Safhi, Abdulrahman Hamad Almajed, Hamad Ali Alnafisah, Salwa Omar Bajunaid, Abdulaziz S. Alqahtani, and Mohammed Alqahtani. "Variations in the Shades of Contemporary Dental Ceramics: An In Vitro Analysis." Crystals 11, no. 11 (October 24, 2021): 1288. http://dx.doi.org/10.3390/cryst11111288.
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Background: To identify and compare the shade variations of various commonly used esthetic dental ceramics by calculating their total-color-difference (ΔE) and translucency parameter (TP) using a spectrophotometer. Methods: In total, 165 disc specimens from three shades (A1, B1, and C1) of five ceramic materials (N = 55/shade; n = 11/ceramic material group) were prepared (Metal-ceramic (MC), IPS e.max press (Emax-P), IPS e.max layer (Emax-L), Layered Zirconia (Zr-L) and Monolithic zirconia (Zr-M)). With a spectrophotometer, the L* a* b* values were obtained. Total color differences (ΔE = [(ΔL*)2 + (Δa*)2 + (Δb*)2]1/2) and translucency parameter (TP = [(L*B − L*W)2 + (a*B − a*W)2 + (b*B – b*W)2]1/2) were calculated. The statistical tests included ANOVA and Post hoc Tukey’s analysis (p < 0.05). Results: Significant differences (p = 0.000) were found between the groups for ΔE. Highest ΔE (A1) were found for Zr-L (80.18 ± 20) and lowest for Zr-M (62.97 ± 1.28). For B1, highest ΔE values were noted for MC (76.85 + 0.78) and lowest for the Emax-L (62.13 ± 1.49). For C1, highest ΔE values were found for the MC group (73.96 ± 0 67) and lowest for Emax-P (55.09 ± 1.76). Translucency variations between tested ceramics were revealed (p < 0.05). Highest TP values (A1) were found for Emax-L (2.99 ± 1.64) and lowest for Zr-L (0.35 ± 0.16). For B1, highest TP values were noted for Emax-P (3.50 ± 1.74) and lowest for MC (0.57 ± 0.40). For C1, highest TP values were found for Emax-P (4.46 ± 2.42) and lowest for MC (0.58 ± 0 48). Conclusions: Significant differences in ΔE and TP were found for tested ceramic groups. The color differences of the tested materials varied according to clinical acceptability, even with the selection of same color/shade. The color/shades of the various dental ceramics do not match with the vita shade guide tabs, to which they are compared most often. Shade differences are present between different lots of ceramic materials from the same or different brands.
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Chang, Kuo-Chu, Huey-Ming Lo, and Yung-Zu Tseng. "Systolic Elastance and Resistance in the Regulation of Cardiac Pumping Function in Early Streptozotocin-Diabetic Rats." Experimental Biology and Medicine 227, no. 4 (April 2002): 251–59. http://dx.doi.org/10.1177/153537020222700405.
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We determined the roles of maximal systolic elastance (Emax) and theoretical maximum flow (Qmax) in the regulation of cardiac pumping function in early streptozotocin (STZ)-diabetic fats. Physically, Emax can reflect the intrinsic contractility of the myocardium as an intact heart, and Qmax has an inverse relation to the systolic resistance of the left ventricle. Rats given STZ 65 mg/kg l.v. (n = 17) were divided into two groups, 1 week and 4 weeks after induction of diabetes, and compared with untreated age-matched controls (n = 15). Left ventricular (LV) pressure and ascending aortic flow signals were recorded to calculate Emax and Qmax, using the elastance-resistance model. After 1 or 4 weeks, STZ-diabetic animals show an increase in effective LV end-diastolic volume (Veed), no significant change in peak iso-volumic pressure (Pisomax), and a decline in effective arterial volume elastance (Ea). The maximal systolic elastance Emax is reduced from 751.5 ± 23.1 mmHg/ml in controls to 514.1 ± 22.4 mmHg/ml in 1- and 538.4 ± 33.8 mmHg/ml in 4-week diabetic rats. Since Emax equals PisomaxVeed, an increase in Veed with unaltered Pisomax may primarily act to diminish Emax so that the intrinsic contractility of the diabetic heart is impaired. By contrast, STZ-diabetic rats have higher theoretical maximum flow Qmax (40.9 ± 2.8 ml/s in 1- and 44.5 ± 3.8 ml/s in 4-week diabetic rats) than do controls (30.7 ± 1.7 ml/s). There exists an inverse relation between Qmax and Ea when a linear regression of Qmax on Ea is performed over all animals studied (r= 0.65, p < 0.01). The enhanced Qmax is indicative of the decline in systolic resistance of the diabetic rat heart. The opposing effects of enhanced Qmax and reduced Emax may negate each other, and then the cardiac pumping function of the early STZ-diabetic rat heart could be preserved before cardiac failure occurs.
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Matsumoto, Shinnosuke, and Shunsuke Yonai. "EVALUATION OF NEUTRON AMBIENT DOSE EQUIVALENT IN CARBON-ION RADIOTHERAPY WITH ENERGY SCANNING." Radiation Protection Dosimetry 191, no. 3 (September 2020): 310–18. http://dx.doi.org/10.1093/rpd/ncaa166.
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Abstract In carbon-ion radiotherapy (CIRT), secondary neutrons are produced by nuclear interactions in the beamline devices or patient. Herein, the characteristics of secondary neutrons in CIRT with energy scanning (ES) were evaluated. Neutron ambient dose equivalents (H*(10)) were measured using WENDI-II. The neutron energy spectrum was calculated using the Monte Carlo simulation. Measurement and calculation were performed under realistic case scenarios using maximum beam energies (Emax) of 290, 350 and 400 MeV u −1. Moreover, H*(10) in ES was compared with H*(10) in range-shifter scanning (RS) and hybrid scanning (HS). H*(10) in Emax = 290 MeV u−1 was 65% less than that in Emax = 400 MeV u−1. At Emax = 350 MeV u−1, H*(10) in ES at θ = 120 was 42% of that at θ = 60. The neutron dose in ES CIRT decreased to approximately 60 and 70% of that in RS and HS CIRT, respectively, at 50-cm distance from the beam axis.
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Anjos, Paulo J. C., Aline O. Lima, Patrícia S. Cunha, Damião P. De Sousa, Alexandre S. C. Onofre, Thais P. Ribeiro, Isac A. Medeiros, Ângelo R. Antoniolli, Lucindo J. Quintans-Júnior, and Márcio R. V. Santos. "Cardiovascular Effects Induced by Linalool in Normotensive and Hypertensive Rats." Zeitschrift für Naturforschung C 68, no. 5-6 (June 1, 2013): 181–90. http://dx.doi.org/10.1515/znc-2013-5-603.
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Linalool is a monoterpene alcohol and constituent of several Brazilian aromatic medicinal plants, popularly used against hypertension. Cardiovascular effects induced by linalool were evaluated. In normotensive rats, (±)-linalool [1, 5, 10, and 20 mg/kg body weight (BW); intravenous (i.v.)]-induced hypotension was associated with tachycardia, which was attenuated by atropine (2 mg/kg BW) and NG-nitro-L-arginine methyl ester (20 mg/kg BW), but was not modified after indomethacin (5 mg/kg BW) administration. In hypertensive rats, linalool [200 mg/kg BW; oral (v.o.)] reduced blood pressure without changing the heart rate. In intact rings of rat mesenteric artery precontracted with 10 μM phenylephrine, linalool (from 6.4 · 10 - 6 to 6.4 · 10 - 3 M) induced relaxations in a concentration-dependent manner [Emax = (115 ± 13)%] that were not changed after atropine administration [Emax = (105 ± 2)%], and were not different from those obtained in endothelium-denuded rings precontracted with phenylephrine [Emax = (108 ± 7)%] or 80 mM KCl [Emax = (113 ± 7)%] or tetraethylammonium incubation [Emax = (105 ± 12)%]. Linalool (1.9 · 10- 3 M) antagonized the contractions induced by CaCl2 (3 · 10 - 6 - 10 - 2 M) (maximal inhibition, 81%). Furthermore, linalool inhibited the contractions induced by 10 μM phenylephrine or 20 mM caffeine. In conclusion, these results demonstrate that linalool reduces blood pressure probably due to a direct effect on the vascular smooth muscle leading to vasodilation.
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Hata, K., Y. Goto, O. Kawaguchi, T. Takasago, A. Saeki, T. Nishioka, and H. Suga. "Hypercapnic acidosis increases oxygen cost of contractility in the dog left ventricle." American Journal of Physiology-Heart and Circulatory Physiology 266, no. 2 (February 1, 1994): H730—H740. http://dx.doi.org/10.1152/ajpheart.1994.266.2.h730.
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The effect of acidosis on left ventricular (LV) mechanoenergetics was assessed in seven excised, cross-circulated dog hearts with the use of the frameworks of the contractility index (Emax) and the relationship between myocardial oxygen consumption (VO2) and pressure-volume area (PVA; a measure of the LV total mechanical energy). Acidosis was stably maintained without hypoxia by appropriately mixing CO2 and air in a membrane oxygenator in the coronary arterial perfusion circuit. Acidosis [pH: 6.98 +/- 0.09 (SD), PCO2: 91 +/- 25 mmHg in the coronary arterial blood] decreased Emax by 45 +/- 12% (P < 0.01) and PVA by 47 +/- 12% (P < 0.01) at a fixed LV volume. When the preacidosis Emax level was restored by Ca2+ infusion during acidosis, unloaded VO2 (the VO2 intercept of the VO2-PVA relation) exceeded the control value by 19 +/- 17% (P < 0.05), indicating that acidosis required higher VO2 for nonmechanical activities at a matched Emax. Moreover, the oxygen cost of enhanced contractility (the incremental ratio of unloaded VO2 to Emax) was 1.53 +/- 0.40 times higher (P < 0.01) during acidosis than preacidosis. We conclude that acidosis results in LV contractile dysfunction accompanied by an increased oxygen cost of contractility. This increased energy cost of the excitation-contraction coupling can be accounted for by a decreased Ca2+ sensitivity of the contractile proteins during acidosis.
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Gonzalez, Richard R., Samuel N. Cheuvront, Brett R. Ely, Daniel S. Moran, Amir Hadid, Thomas L. Endrusick, and Michael N. Sawka. "Sweat rate prediction equations for outdoor exercise with transient solar radiation." Journal of Applied Physiology 112, no. 8 (April 15, 2012): 1300–1310. http://dx.doi.org/10.1152/japplphysiol.01056.2011.
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We investigated the validity of employing a fuzzy piecewise prediction equation (PW) [Gonzalez et al. J Appl Physiol 107: 379–388, 2009] defined by sweat rate (msw, g·m−2·h−1) = 147 + 1.527·(Ereq) − 0.87·(Emax), which integrates evaporation required (Ereq) and the maximum evaporative capacity of the environment (Emax). Heat exchange and physiological responses were determined throughout the trials. Environmental conditions were ambient temperature (Ta) = 16–26°C, relative humidity (RH) = 51–55%, and wind speed ( V) = 0.5–1.5 m/s. Volunteers wore military fatigues [clothing evaporative potential (im/clo) = 0.33] and carried loads (15–31 kg) while marching 14–37 km over variable terrains either at night ( N = 77, trials 1–5) or night with increasing daylight ( N = 33, trials 6 and 7). PW was modified ( Ṗw,sol) for transient solar radiation (Rsol, W) determined from measured solar loads and verified in trials 6 and 7. PW provided a valid msw prediction during night trials ( 1–5) matching previous laboratory values and verified by bootstrap correlation (rbs of 0.81, SE ± 0.014, SEE = ± 69.2 g·m−2·h−1). For trials 6 and 7, Ereq and Emax components included Rsol applying a modified equation Ṗw,sol, in which msw = 147 + 1.527·(Ereq,sol) − 0.87·(Emax). Linear prediction of msw = 0.72· Ṗw,sol + 135 ( N = 33) was validated ( R2 = 0.92; SEE = ±33.8 g·m−2·h−1) with PW β-coefficients unaltered during field marches between 16°C and 26°C Ta for msw ≤ 700 g·m−2·h−1. PW was additionally derived for cool laboratory/night conditions (Ta < 20°C) in which Ereq is low but Emax is high, as: PW,cool (g·m−2·h−1) = 350 + 1.527·Ereq − 0.87·Emax. These sweat prediction equations allow valid tools for civilian, sports, and military medicine communities to predict water needs during a variety of heat stress/exercise conditions.
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Suga, H., Y. Goto, H. Yaku, S. Futaki, Y. Ohgoshi, and O. Kawaguchi. "Simulation of mechanoenergetics of asynchronously contracting ventricle." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 259, no. 5 (November 1, 1990): R1075—R1082. http://dx.doi.org/10.1152/ajpregu.1990.259.5.r1075.
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We simulated mechanoenergetics of ventricular asynchronous contraction using a model comprising two compartmentalized asynchronous time-varying elastic elements, E1 and E2. Their elastances [e1(t) and e2(t)] waxed and waned cyclically with a variable time lag (tau). The pressure-volume area (PVA1 or PVA2) circumscribed by the maximum (emax) and minimum e1(t) or e2(t) lines and the contracting pressure-volume trajectory of E1 or E2 quantifies the mechanical energy generated by a contraction of E1 or E2. Similarly, the PVA circumscribed by the resultant Emax (ventricular contractility index) line, the end-diastolic pressure-volume (P-V) line, and the systolic P-V trajectory quantifies the mechanical energy of the entire ventricle. PVA of the ventricle is equal to the sum of PVA1 and PVA2. We found that Emax decreased with increases in tau despite constant emax, and hence ventricular PVA decreased with increases in tau. This simulation helps us to better understand the mechanism of decreased oxygen consumption with increasing ventricular asynchrony reported in the literature.
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Mikane, Takeshi, Junichi Araki, Shunsuke Suzuki, Ju Mizuno, Juichiro Shimizu, Satoshi Mohri, Hiromi Matsubara, Masahisa Hirakawa, Tohru Ohe, and Hiroyuki Suga. "O2cost of contractility but not of mechanical energy increases with temperature in canine left ventricle." American Journal of Physiology-Heart and Circulatory Physiology 277, no. 1 (July 1, 1999): H65—H73. http://dx.doi.org/10.1152/ajpheart.1999.277.1.h65.
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We investigated the effects of myocardial temperature on left ventricular (LV) mechanoenergetics in the excised, cross-circulated canine heart. We used the framework of the LV contractility ( Emax)-pressure-volume area (PVA; a measure of total mechanical energy)-myocardial oxygen consumption (Vo2) relationship. We have shown this framework to be useful to integrative analysis of the mechanoenergetics of a beating heart. In isovolumic contractions at a constant pacing rate, increasing myocardial temperature from 30 to 40°C depressed Emaxand increased the oxygen cost of Emax, which was enhanced by dobutamine, in a linear manner. However, the slope of the Vo2-PVA relation (reciprocal of contractile efficiency) and its Vo2intercept remained constant. Q10values of Emax, the oxygen cost of Emax, and the oxygen cost of PVA were 0.4, 2.1 and 1.0, respectively, around normothermia. We conclude that the temperature-dependent processes of cross-bridge cycling and Ca2+handling integratively depress Emaxand augment its oxygen cost without affecting the oxygen cost of PVA as myocardial temperature increases by 10°C around normothermia.
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Mohri, Satoshi, Juichiro Shimizu, Gentaro Iribe, Haruo Ito, Terumasa Morita, Hiroki Yamaguchi, Shunji Sano, Fumihiko Kajiya, and Hiroyuki Suga. "Normal distribution of ventricular pressure-volume area of arrhythmic beats under atrial fibrillation in canine heart." American Journal of Physiology-Heart and Circulatory Physiology 288, no. 4 (April 2005): H1740—H1746. http://dx.doi.org/10.1152/ajpheart.00584.2004.
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We previously found the frequency distribution of the left ventricular (LV) effective afterload elastance (Ea) of arrhythmic beats to be nonnormal or non-Gaussian in contrast to the normal distribution of the LV end-systolic elastance (Emax) in canine in situ LVs during electrically induced atrial fibrillation (AF). These two mechanical variables determine the total mechanical energy [systolic pressure-volume area (PVA)] generated by LV contraction when the LV end-diastolic volume is given on a per-beat basis. PVA and Emax are the two key determinants of the LV O2 consumption per beat. In the present study, we analyzed the frequency distribution of PVA during AF by its χ2, significance level, skewness, and kurtosis and compared them with those of other major cardiodynamic variables including Ea and Emax. We assumed the volume intercept (V0) of the end-systolic pressure-volume relation needed for Emax determination to be stable during arrhythmia. We found that PVA distributed much more normally than Ea and slightly more so than Emax during AF. We compared the χ2, significance level, skewness, and kurtosis of all the complex terms of the PVA formula. We found that the complexity of the PVA formula attenuated the effect of the considerably nonnormal distribution of Ea on the distribution of PVA along the central limit theorem. We conclude that mean (SD) of PVA can reliably characterize the distribution of PVA of arrhythmic beats during AF, at least in canine hearts.
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Belcher, P., L. E. Boerboom, and G. N. Olinger. "Standardization of end-systolic pressure-volume relation in the dog." American Journal of Physiology-Heart and Circulatory Physiology 249, no. 3 (September 1, 1985): H547—H553. http://dx.doi.org/10.1152/ajpheart.1985.249.3.h547.
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Left ventricular (LV) volume elastance (Emax) and its volume intercept (Vo) are subject to considerable intersubject and interspecies variation. In humans, indexing with body surface area does not decrease variance. Because these are volume indexes, it was considered they would better standardize against body or LV weight. Fifteen open-chest mongrel dogs (mean wt 25.9 +/- 8.0 kg, range 15.6-42.5) were studied under 1% halothane anesthesia. Emax, derived by caval occlusion, averaged 9.0 +/- 4.4 mmHg X ml-1 (range 4.1-16.1) with a coefficient of variation (CV) of 48%. Average Vo was 19.6 +/- 10.5 ml (range 8.3-40.3) with a CV of 53%. LV weight was 110 +/- 21 g (range 78-147). Vo correlated best with LV weight: Y = 0.47 X - 31.78, r = 0.93, and adjustment of Vo by regression reduced CV to 20%. Emax was closely correlated with either 1/dog wt [Y = 313.02 (1/X) - 4.16, r = 0.88, CV = 23% after adjustment by regression] or 1/LV wt [Y = 2088.63 (1/X) - 10.72, r = 0.86, CV = 25% after adjustment]. Indexing of Emax by dog weight (CV = 29%) or LV weight (CV = 35%) reduced variation but by less than adjustment by regression. A subset of eight dogs had inotropic state varied, which had no effect on the relation between Vo and LV weight, but which resulted in an appropriate change (P less than 0.025) in the relation between Emax and 1/LV wt.(ABSTRACT TRUNCATED AT 250 WORDS)
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Araki, J., M. Takaki, T. Namba, M. Mori, and H. Suga. "Ca(2+)-free, high-Ca2+ coronary perfusion suppresses contractility and excitation-contraction coupling energy." American Journal of Physiology-Heart and Circulatory Physiology 268, no. 3 (March 1, 1995): H1061—H1070. http://dx.doi.org/10.1152/ajpheart.1995.268.3.h1061.
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We studied the mechanoenergetic effects of a short-term Ca(2+)-free, high-Ca2+ Tyrode solution coronary perfusion in eight excised, cross-circulated canine hearts. The perfusion protocol consisted of coronary perfusion with Ca(2+)-free Tyrode solution for 10 min followed by high-Ca2+ (16 mM) Tyrode solution for 5 min. This new protocol successfully induced acute contractile failure in seven hearts, without myocardial ultrastructural changes. We studied the end-systolic pressure-volume relation (slope = Emax, a contractility index) and the relation between oxygen consumption per beat (VO2) and systolic pressure-volume area (PVA) in these failing hearts. These hearts had no increase in end-diastolic pressure at a given volume, a 40% decrease in Emax and a proportional decrease in the PVA-independent VO2 for 1–4 h, but no decrease in the oxygen cost of PVA, defined as the slope of the VO2-PVA relation. The oxygen cost of Emax for Ca2+ handling, defined as the slope of the relation between PVA-independent VO2 and Emax, was unchanged in the failing hearts. We conclude that the present protocol induced left ventricular contractile failure, primarily involving the suppression of Ca2+ handling energy for excitation-contraction coupling.
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Pelin, Marco, Gabriele Stocco, Chiara Florio, Silvio Sosa, and Aurelia Tubaro. "In Vitro Cell Sensitivity to Palytoxin Correlates with High Gene Expression of the Na+/K+-ATPase β2 Subunit Isoform." International Journal of Molecular Sciences 21, no. 16 (August 14, 2020): 5833. http://dx.doi.org/10.3390/ijms21165833.
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The marine polyether palytoxin (PLTX) is one of the most toxic natural compounds, and is involved in human poisonings after oral, inhalation, skin and/or ocular exposure. Epidemiological and molecular evidence suggest different inter-individual sensitivities to its toxic effects, possibly related to genetic-dependent differences in the expression of Na+/K+-ATPase, its molecular target. To identify Na+/K+-ATPase subunits, isoforms correlated with in vitro PLTX cytotoxic potency, sensitivity parameters (EC50: PLTX concentration reducing cell viability by 50%; Emax: maximum effect induced by the highest toxin concentration; 10−7 M) were assessed in 60 healthy donors’ monocytes by the MTT (methylthiazolyl tetrazolium) assay. Sensitivity parameters, not correlated with donors’ demographic variables (gender, age and blood group), demonstrated a high inter-individual variability (median EC50 = 2.7 × 10−10 M, interquartile range: 0.4–13.2 × 10−10 M; median Emax = 92.0%, interquartile range: 87.5–94.4%). Spearman’s analysis showed significant positive correlations between the β2-encoding ATP1B2 gene expression and Emax values (rho = 0.30; p = 0.025) and between Emax and the ATP1B2/ATP1B3 expression ratio (rho = 0.38; p = 0.004), as well as a significant negative correlation between Emax and the ATP1B1/ATP1B2 expression ratio (rho = −0.30; p = 0.026). This toxicogenetic study represents the first approach to define genetic risk factors that may influence the onset of adverse effects in human PLTX poisonings, suggesting that individuals with high gene expression pattern of the Na+/K+-ATPase β2 subunit (alone or as β2/β1 and/or β2/β3 ratio) could be highly sensitive to PLTX toxic effects.
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Moon, Jin Hee, Ji-Young Hwang, Jeong Seon Park, Sung Hye Koh, and Sun-Young Park. "Impact of region of interest (ROI) size on the diagnostic performance of shear wave elastography in differentiating solid breast lesions." Acta Radiologica 59, no. 6 (September 12, 2017): 657–63. http://dx.doi.org/10.1177/0284185117732097.
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Background Shear wave elastography (SWE) using a region of interest (ROI) can demonstrate the quantitative elasticity of breast lesions. Purpose To prospectively evaluate the impact of two different ROI sizes on the diagnostic performance of SWE for differentiating benign and malignant breast lesions. Material and Methods A total of 154 breast lesions were included. Two types of ROIs were investigated: one involving an approximately 2-mm diameter, small round ROIs placed over the stiffest area of the lesion, as determined by SWE (ROI-S); and another ROI drawn along the margin of the lesion using a touch pen or track ball to encompass the entire lesion (ROI-M). Maximum elasticity (Emax), mean elasticity (Emean), minimum elasticity (Emin), and standard deviation (SD) were measured for the two ROIs. The area under the receiver operating characteristic curve (AUC) as well as the sensitivity and specificity of each elasticity value were determined. Results The AUCs for ROI-S were higher than those for ROI-M when differentiating benign and malignant breast solid lesions. The Emax, Emean, Emin, and SD of the elasticity values for ROI-S were 0.865, 0.857, 0.816, and 0.849, respectively, and for ROI-M were 0.820, 0.780, 0.724, and 0.837, respectively. However, only Emax ( P = 0.0024) and Emean ( P = 0.0015) showed statistically significant differences. For ROI-S, the sensitivity and specificity of Emax were 78.8% and 84.3%, respectively, and those for Emean were 80.8% and 81.4%, respectively. Conclusion Using ROI-S with Emax and Emean has better diagnostic performance than ROI-M for differentiating between benign and malignant breast lesions.
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Jimenez-Toro, Ivone, Carlos A. Rodriguez, Andres F. Zuluaga, Julian D. Otalvaro, and Omar Vesga. "A new pharmacodynamic approach to study antibiotic combinations against enterococci in vivo: Application to ampicillin plus ceftriaxone." PLOS ONE 15, no. 12 (December 8, 2020): e0243365. http://dx.doi.org/10.1371/journal.pone.0243365.
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The combination of ampicillin (AMP) and ceftriaxone (CRO) is considered synergistic against Enterococcus faecalis based on in vitro tests and the rabbit endocarditis model, however, in vitro assays are limited by the use of fixed antibiotic concentrations and the rabbit model by poor bacterial growth, high variability, and the use of point dose-effect estimations, that may lead to inaccurate assessment of antibiotic combinations and hinder optimal translation. Here, we tested AMP+CRO against two strains of E. faecalis and one of E. faecium in an optimized mouse thigh infection model that yields high bacterial growth and allows to define the complete dose-response relationship. By fitting Hill’s sigmoid model and estimating the parameters maximal effect (Emax) and effective dose 50 (ED50), the following interactions were defined: synergism (Emax increase ≥2 log10 CFU/g), antagonism (Emax reduction ≥1 log10 CFU/g) and potentiation (ED50 reduction ≥50% without changes in Emax). AMP monotherapy was effective against the three strains, yielding valid dose-response curves in terms of dose and the index fT>MIC. CRO monotherapy showed no effect. The combination AMP+CRO against E. faecalis led to potentiation (59–81% ED50 reduction) and not synergism (no changes in Emax). Against E. faecium, the combination was indifferent. The optimized mouse infection model allowed to obtain the complete dose-response curve of AMP+CRO and to define its interaction based on pharmacodynamic parameter changes. Integrating these results with the pharmacokinetics will allow to derive the PK/PD index bound to the activity of the combination, essential for proper translation to the clinic.
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Sala-Mercado, Javier A., Robert L. Hammond, Jong-Kyung Kim, Phillip J. McDonald, Larry W. Stephenson, and Donal S. O'Leary. "Heart failure attenuates muscle metaboreflex control of ventricular contractility during dynamic exercise." American Journal of Physiology-Heart and Circulatory Physiology 292, no. 5 (May 2007): H2159—H2166. http://dx.doi.org/10.1152/ajpheart.01240.2006.
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Underperfusion of active skeletal muscle elicits a reflex pressor response termed the muscle metaboreflex (MMR). In normal dogs during mild exercise, MMR activation causes large increases in cardiac output (CO) and mean arterial pressure (MAP); however, in heart failure (HF) although MAP increases, the rise in CO is virtually abolished, which may be due to an impaired ability to increase left ventricular contractility (LVC). The objective of the present study was to determine whether the increases in LVC seen with MMR activation during dynamic exercise in normal animals are abolished in HF. Conscious dogs were chronically instrumented to measure CO, MAP, and left ventricular (LV) pressure and volume. LVC was calculated from pressure-volume loop analysis [LV maximal elastance ( Emax) and preload-recruitable stroke work (PRSW)] at rest and during mild and moderate exercise under free-flow conditions and with MMR activation (via partial occlusion of hindlimb blood flow) before and after rapid ventricular pacing-induced HF. In control experiments, MMR activation at both workloads [mild exercise (3.2 km/h) and moderate exercise (6.4 km/h at 10% grade)] significantly increased CO, Emax, and PRSW. In contrast, after HF was induced, CO, Emax, and PRSW were significantly lower at rest. Although CO increased significantly from rest to exercise, Emax and PRSW did not change. In addition, MMR activation caused no significant change in CO, Emax, or PRSW at either workload. We conclude that MMR causes large increases in LVC in normal animals but that this ability is abolished in HF.
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Oktay, Tugrul, Seda Arik, Ilke Turkmen, Metin Uzun, and Harun Celik. "Neural network based redesign of morphing UAV for simultaneous improvement of roll stability and maximum lift/drag ratio." Aircraft Engineering and Aerospace Technology 90, no. 8 (November 5, 2018): 1203–12. http://dx.doi.org/10.1108/aeat-06-2017-0157.
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Purpose The aim of this paper is to redesign of morphing unmanned aerial vehicle (UAV) using neural network for simultaneous improvement of roll stability coefficient and maximum lift/drag ratio. Design/methodology/approach Redesign of a morphing our UAV manufactured in Faculty of Aeronautics and Astronautics, Erciyes University is performed with using artificial intelligence techniques. For this purpose, an objective function based on artificial neural network (ANN) is obtained to get optimum values of roll stability coefficient (Clβ) and maximum lift/drag ratio (Emax). The aim here is to save time and obtain satisfactory errors in the optimization process in which the ANN trained with the selected data is used as the objective function. First, dihedral angle (φ) and taper ratio (λ) are selected as input parameters, C*lβ and Emax are selected as output parameters for ANN. Then, ANN is trained with selected input and output data sets. Training of the ANN is possible by adjusting ANN weights. Here, ANN weights are adjusted with artificial bee colony (ABC) algorithm. After adjusting process, the objective function based on ANN is optimized with ABC algorithm to get better Clβ and Emax, i.e. the ABC algorithm is used for two different purposes. Findings By using artificial intelligence methods for redesigning of morphing UAV, the objective function consisting of C*lβ and Emax is maximized. Research limitations/implications It takes quite a long time for Emax data to be obtained realistically by using the computational fluid dynamics approach. Practical implications Neural network incorporation with the optimization method idea is beneficial for improving Clβ and Emax. By using this approach, low cost, time saving and practicality in applications are achieved. Social implications This method based on artificial intelligence methods can be useful for better aircraft design and production. Originality/value It is creating a novel method in order to redesign of morphing UAV and improving UAV performance.
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Jin, Bo, and Kerry B. Barker. "Equivalence Test for Two Emax Response Curves." Statistics in Biopharmaceutical Research 8, no. 3 (July 2, 2016): 307–15. http://dx.doi.org/10.1080/19466315.2016.1194772.
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Anderson, Brian J., Nicholas H. G. Holford, Gerald A. Woollard, Suchitra Kanagasundaram, and Murali Mahadevan. "Perioperative Pharmacodynamics of Acetaminophen Analgesia in Children." Anesthesiology 90, no. 2 (February 1, 1999): 411–21. http://dx.doi.org/10.1097/00000542-199902000-00014.
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Background There are no adequate pharmacodynamic data relating concentrations of acetaminophen in serum to analgesia. Methods Children undergoing outpatient tonsillectomy were administered acetaminophen either orally, 0.5-1.0 h preoperatively (n = 20), or per rectum at induction of anesthesia (n = 100). No other analgesic agents were administered. Individual concentrations of acetaminophen in serum and pain scores (0-10) measured over a 4-h postoperative period were analyzed using a nonlinear mixed-effects model (NONMEM). Results Mean (% CV) estimates of population pharmacokinetic parameters with percent coefficient of variation, standardized to a 70-kg person, for a one-compartment model with first-order input, lag time, and first order-elimination were a volume of distribution of 60 (21) 1 and a clearance of 13.5 (46) 1/h. Rectally administered acetaminophen had an absorption half-life of 35 (63) min with a lag time of 40 min. The absorption half-life for the oral preparation was 4.5 (63) min without a detectable lag time. The relative bioavailability of the rectal compared with the oral formulation was 0.54. The equilibration half-time of an effect compartment was 1.6 (131) h. Pharmacodynamic population parameter estimates (percent coefficient of variation) for a fractional sigmoidal Emax model, in which the greatest possible pain relief equates to an Emax of 1, were Emax = 1, EC50 (the concentration producing 50% of Emax) = 3.4 (94) mg/l, and Hill coefficient = 0.54 (42). Conclusions The pharmacodynamics of acetaminophen can be described using a sigmoidal Emax model with a low Hill coefficient. To achieve a mean posttonsillectomy pain score of 3.6 of 10, an effect compartment concentration of 10 mg/l is necessary.
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Xu, Hui, Gregory D. Fink, and James J. Galligan. "Increased sympathetic venoconstriction and reactivity to norepinephrine in mesenteric veins in anesthetized DOCA-salt hypertensive rats." American Journal of Physiology-Heart and Circulatory Physiology 293, no. 1 (July 2007): H160—H168. http://dx.doi.org/10.1152/ajpheart.01414.2006.
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Increased sympathetic nervous activity (SNA) elevates venomotor tone in deoxycorticosterone acetate (DOCA)-salt hypertension. We studied the mechanisms by which the SNA increases venomotor tone in DOCA-salt hypertension by making in situ intracellular recordings of venous smooth muscle cell (VSMC) membrane potential ( Em) and measurement of outside diameter (OD) in mesenteric veins (MV) and mesenteric arteries (MA) of anesthetized rats. We also studied norepinephrine (NE)- and endothelin-1 (ET-1)-induced increases in MA or MV perfusion pressure (PP) in vitro. Em in DOCA-salt MV was depolarized compared with sham MV. Prazosin hyperpolarized VSMC Em in DOCA-salt but not in sham MV. NE concentration-response curves (CRCs) for OD decreases in MV from DOCA-salt rats were left-shifted with an increased maximum response ( Emax) compared with sham MV. NE CRCs for OD decreases in MA were right-shifted with reduced Emax in DOCA-salt compared with sham rats. ET-1 CRCs were similar in DOCA-salt and sham MV but were right-shifted with reduced Emax in DOCA-salt MA. NE CRCs for MAPP increases were left-shifted without a change in Emax in DOCA-salt rats. NE did not change MVPP. MAPP and MVPP for ET-1 CRCs were similar in sham and DOCA-salt rats, but Emax for MAPP was reduced in DOCA-salt rats. Hematoxylin staining revealed hypertrophy in DOCA-salt MA but not in MV. We conclude that there is increased reactivity to NE released from the sympathetic nervous system in DOCA-salt MV that causes VSMC depolarization and increased venomotor tone. In DOCA-salt rats, in vivo ET-1 reactivity is maintained in MV, but reduced in MA.
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Basri, Kasbi, Adnan Zainorabidin, Mohd Khaidir Abu Talib, and Norhaliza Wahab. "Estimating the Small Strain Stiffness of Peat Soil Using Geophysical Methods." International Journal of Engineering Technology and Sciences 7, no. 1 (February 10, 2021): 44–54. http://dx.doi.org/10.15282/http://dx.doi.org/10.15282/ijets.7.1.2020.1005.
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Geotechnical design commonly requires that the in-situ stiffness, strength and permeability of the ground be obtained. Laboratory based investigation often related with risk of sample disturbance and difficulties to replicate the in-situ stress condition which results in overestimation or underestimation. Application of geophysical methods in geotechnical investigation previously was limited to targeting and dimensioning sub-surface features due to lack of resolution. However, rapid developments of geophysical methods result in the application of these methods in providing geotechnical design parameters. Multichannel analysis of surface waves (MASW) and seismic refraction were among the geophysical methods capable of obtaining stiffness parameters including the maximum shear modulus (Gmax) and maximum elastic modulus (Emax). The study revealed the efficiency of these methods to measure the small strain stiffness of peat soil with high accuracy as the results obtained were found to be similar to those obtained by previous researchers. Overall, the Gmax and Emax values of peat soil obtained range from 0.49 to 1.72 MPa and 1.46 to 5.15 MPa respectively. The Gmax and Emax values obtained shows significant increase with depth governed primarily by the effective stress. Other parameters such as degree of decomposition and peat thickness also shows potential influence on the Gmax and Emax values obtained.
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Bulum, Antonio, Gordana Ivanac, Eugen Divjak, Iva Biondić Špoljar, Martina Džoić Dominković, Kristina Bojanić, Marko Lucijanić, and Boris Brkljačić. "Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size." Diagnostics 11, no. 6 (June 1, 2021): 1015. http://dx.doi.org/10.3390/diagnostics11061015.
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Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.
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Gao, Yujia, Yi Zhao, Sunyoung Choi, Anjalee Chaurasia, Hao Ding, Athar Haroon, Simon Wan, and Sola Adeleke. "Evaluating Different Quantitative Shear Wave Parameters of Ultrasound Elastography in the Diagnosis of Lymph Node Malignancies: A Systematic Review and Meta-Analysis." Cancers 14, no. 22 (November 13, 2022): 5568. http://dx.doi.org/10.3390/cancers14225568.
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Shear wave elastography (SWE) has shown promise in distinguishing lymph node malignancies. However, the diagnostic accuracies of various SWE parameters that quantify tissue stiffness are yet to be demonstrated. To evaluate the pooled diagnostic accuracy of different SWE parameters for differentiating lymph node malignancies, we conducted a systematic screening of four databases using the PRISMA guidelines. Lymph node biopsy was adopted as the reference standard. Emax (maximum stiffness), Emean (mean stiffness), Emin (minimum stiffness), and Esd (standard deviation) SWE parameters were subjected to separate meta-analyses. A sub-group analysis comparing the use of Emax in cervical (including thyroid) and axillary lymph node malignancies was also conducted. Sixteen studies were included in this meta-analysis. Emax and Esd demonstrated the highest pooled sensitivity (0.78 (95% CI: 0.69–0.87); 0.78 (95% CI: 0.68–0.87)), while Emean demonstrated the highest pooled specificity (0.93 (95% CI: 0.88–0.98)). From the sub-group analysis, the diagnostic performance did not differ significantly in cervical and axillary LN malignancies. In conclusion, SWE is a promising adjunct imaging technique to conventional ultrasonography in the diagnosis of lymph node malignancy. SWE parameters of Emax and Esd have been identified as better choices of parameters for screening clinical purposes.
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Wong, Emily S. W., Ricky Y. K. Man, Kwok F. J. Ng, Susan W. S. Leung, and Paul M. Vanhoutte. "L-arginine and Arginase Products Potentiate Dexmedetomidine-induced Contractions in the Rat Aorta." Anesthesiology 128, no. 3 (March 1, 2018): 564–73. http://dx.doi.org/10.1097/aln.0000000000002032.
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Abstract Background The α2-adrenergic sedative/anesthetic agent dexmedetomidine exerts biphasic effects on isolated arteries, causing endothelium-dependent relaxations at concentrations at or below 30 nM, followed by contractions at higher concentrations. l-arginine is a common substrate of endothelial nitric oxide synthase and arginases. This study was designed to investigate the role of l-arginine in modulating the overall vascular response to dexmedetomidine. Methods Isometric tension was measured in isolated aortic rings of Sprague Dawley rats. Cumulative concentrations of dexmedetomidine (10 nM to 10 μM) were added to quiescent rings (with and without endothelium) after previous incubation with vehicle, Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME; nitric oxide synthase inhibitor), prazosin (α1-adrenergic antagonist), rauwolscine (α2-adrenergic antagonist), l-arginine, (S)-(2-boronethyl)-l-cysteine hydrochloride (arginase inhibitor), NG-hydroxy-l-arginine (arginase inhibitor), urea and/or ornithine. In some preparations, immunofluorescent staining, immunoblotting, or measurement of urea content were performed. Results Dexmedetomidine did not contract control rings with endothelium but evoked concentration-dependent increases in tension in such rings treated with l-NAME (Emax 50 ± 4%) or after endothelium-removal (Emax 74 ± 5%; N = 7 to 12). Exogenous l-arginine augmented the dexmedetomidine-induced contractions in the presence of l-NAME (Emax 75 ± 3%). This potentiation was abolished by (S)-(2-boronethyl)-l-cysteine hydrochloride (Emax 16 ± 4%) and NG-hydroxy-l-arginine (Emax 18 ± 4%). Either urea or ornithine, the downstream arginase products, had a similar potentiating effect as l-arginine. Immunoassay measurements demonstrated an upregulation of arginase I by l-arginine treatment in the presence of l-NAME (N = 4). Conclusions These results suggest that when vascular nitric oxide homeostasis is impaired, the potentiation of the vasoconstrictor effect of dexmedetomidine by l-arginine depends on arginase activity and the production of urea and ornithine.
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Baciu, Sorana, Cristian Berece, Adrian Florea, Alexandru Victor Burde, Anda Munteanu, Toni Andor Cigu, Tiberiu Hosszu, Camelia Szuhanek, Marius Manole, and Cosmin Sinescu. "Three-dimensional Marginal Evaluation of Two Pressed Materials Using Micro-CT Technology." Revista de Chimie 68, no. 3 (April 15, 2017): 615–18. http://dx.doi.org/10.37358/rc.17.3.5514.
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The main goal of the present study is to compare the marginal fit of two different kind of pressed materials: a partially crystalline thermoplastic resin reinforced with ceramic particles (BioHPP) and lithium disilicate (EMax), through the use of the microCT technique. After extraction of four caries-free mandibular first molars, first class inlay cavities were prepared. For each tooth two inlays were manufactured- one by using BioHPP thermoplastic resin (n=4) and one by using Emax Press lithium disilicate (n=4). The marginal gap was analyzed circumferentially at the occlusal margin using a Bruker micro CT, by measuring the distance at the occlusal limit of the cavities, between the restoration and the tooth in several points for every surface of each tooth before cementing. Data were analyzed statistically using the Mann-Whitney U test and the Pearson�s correlation coefficient (a=0.05). A significant statistical difference was found between the marginal gap size obtained for BioHPP and Emax inlays (p[0.001). For the Emax inlays the marginal gap had an average of 72mm, while for BioHPP the average was 94 �m. Both types of used materials offer a good marginal adaptation. By summing up the gathered data we can conclude that the pressed ceramics shows a better marginal fit than the pressed resin, probably because of the different processing methods: sintering versus polymerizing with different shrinkage values.
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Goto, Y., B. K. Slinker, and M. M. LeWinter. "Effects of amrinone and isoproterenol on mechanoenergetics of blood-perfused rabbit heart." American Journal of Physiology-Heart and Circulatory Physiology 262, no. 3 (March 1, 1992): H719—H727. http://dx.doi.org/10.1152/ajpheart.1992.262.3.h719.
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To compare the effects of amrinone (AMR) and isoproterenol (Iso) on left ventricular contractility and energetics, we assessed Emax (ventricular contractility index) and the relation between oxygen consumption per beat (VO2) and systolic pressure-volume area (PVA, a measure of left ventricular total mechanical energy) in isolated cross-circulated (blood-perfused) rabbit hearts during infusion of AMR or Iso in either a constant-flow (CF) or constant-pressure (CP) perfusion mode. Both Emax and the VO2 intercept of the linear VO2-PVA relation increased significantly during AMRCP (increase in Emax 15% and increase in VO2 intercept 11%), ISOCF (49 and 43%), and ISOCP (55 and 54%) but not during AMRCF. However, neither drug changed the slope of the VO2-PVA relation (reciprocal of contractile efficiency) in either perfusion mode. Furthermore, with both drugs the relation between increases in Emax and the VO2 intercept fell on a single regression line (r = 0.92). We conclude that 1) although the mechanism of action and inotropic potency of the two drugs differ, their effects on cardiac energetic cost are essentially the same, i.e., both drugs increase the nonmechanical oxygen cost in proportion to the increase in contractility without changing contractile efficiency, and 2) a significant portion of the inotropic effect of AMR in the whole ventricle is likely due to increased coronary blood flow, i.e., Gregg's phenomenon.
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Nishioka, T., Y. Goto, K. Hata, T. Takasago, A. Saeki, T. W. Taylor, and H. Suga. "Mechanoenergetics of negative inotropism of ventricular wall vibration in dog heart." American Journal of Physiology-Heart and Circulatory Physiology 270, no. 2 (February 1, 1996): H583—H593. http://dx.doi.org/10.1152/ajpheart.1996.270.2.h583.
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Mechanical vibration depresses cardiac contractility. We studied the mechanoenergetic effects of this negative inotropism in the left ventricle (LV) of an isolated, cross-circulated dog heart preparation. We took full advantage of the mechanoenergetic relationship among the LV end-systolic elastance (Emax, contractility index), systolic pressure-volume area (PVA), and myocardial oxygen consumption (VO2). PVA is a measure of the total mechanical energy that cardiac contraction generates. PVA correlates closely with VO2. The VO2 intercept of the VO2-PVA relation reflects the VO2 component for excitation-contraction (E-C) coupling plus basal metabolism (PVA-independent VO2). VO2 above the PVA-independent VO2 reflects the VO2 component for mechanical contraction (PVA-dependent VO2). When we applied 70-Hz vibration of 2-mm amplitude to a LV wall region, it instantly decreased Emax and PVA by 20%, followed by a 10% decrease in VO2 at a fixed volume. However, the vibration neither lowered the VO2-PVA relation obtained at different LV volumes, unlike ordinary negative inotropism, nor changed its slope (1.88 +/- 0.23 vs. 1.86 +/- 0.23 x 10(-5) ml O2.mmHg-1.ml-1). The virtually zero delta PVA-independent VO2/delta Emax with vibration indicates a much smaller O2 cost of Emax than that seen with calcium and propranolol inotropism. These mechanoenergetics support the hypothesis that mechanical vibration primarily suppresses cardiac contractility without suppressing E-C coupling.
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Janák, Karel, and Jaroslav Janák. "Preparation and properties of epoxided Separon-based ion exchangers with bonded 8-hydroxyquinoline." Collection of Czechoslovak Chemical Communications 51, no. 3 (1986): 650–56. http://dx.doi.org/10.1135/cccc19860650.
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The direct fixation of copper(II) 5-(4-hydroxyphenylazo)-8-quinolinate and the indirect fixation of 8-hydroxyquinoline to Separon H 40Emax and Separon H 1000 Emax were compared from the point of view of the practical sorption capacities of the resulting ion exchangers. For the ion exchanger obtained by indirect fixation of the reagent to Separon H 40 Emax, the rate of Cu2+ ions, and the stability were determined and compared with those of a G-gel-based ion exchanger.
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Nilsson, T., and L. Edvinsson. "Neuropeptide Y stimulates DNA synthesis in human vascular smooth muscle cells through neuropeptide Y Y1 receptors." Canadian Journal of Physiology and Pharmacology 78, no. 3 (March 1, 2000): 256–59. http://dx.doi.org/10.1139/y99-147.
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We investigated the mitogenic effect, measured as [3H]thymidine incorporation, of neuropeptide Y (NPY) on smooth muscle cells (SMCs) from human subcutaneous arteries (diameter: 0.4 mm). NPY stimulated DNA synthesis in a concentration-dependent manner, Emax 32 ± 5% relative to control. The effect was potently antagonised by the NPY Y1 receptor antagonist BIBP3226 ((R)-N2-(diphenylacetyl)-N-[(4-hydroxy-phenyl)methyl]-D-arginine-amide), indicating the effect to be mediated via the NPY Y1 receptor. Noradrenaline (NA) also induced mitogenesis, Emax 35 ± 10% relative to control. When added together, NPY and NA potentiated the [3H]thymidine incorporation, Emax 109 ± 38% relative to control. Also, this effect seems to be mediated by the NPY Y1 receptor, since BIBP3226 blocked the effect (44 ± 9% relative to control). The mitogenic effect of NPY and NA, two important transmitters of the sympathetic nervous system, might have clinical consequences on conditions with elevated sympathetic nerve activity.Key words: BIBP3226, mitogenesis, neuropeptide Y, vascular smooth muscle cells.
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Igarashi, Y., and H. Suga. "Assessment of slope of end-systolic pressure-volume line of in situ dog heart." American Journal of Physiology-Heart and Circulatory Physiology 250, no. 4 (April 1, 1986): H685—H692. http://dx.doi.org/10.1152/ajpheart.1986.250.4.h685.
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The purpose of this study was to establish a new method of assessment of the slope (Emax) of the end-systolic pressure-volume line (ESPVL) of the in situ heart. In anesthetized open-chest dogs, an isovolumic contraction was produced by an aortic occlusion after steady-state ejecting contractions in the left ventricle. We plotted ventricular pressure measured with a catheter-tip manometer against time integral of aortic flow measured with an electromagnetic flowmeter of the last ejecting and the first isovolumic contraction, assuming the same end-diastolic volume. ESPVL was drawn from the peak isovolumic pressure-volume point tangential to the left upper corner of the +/- 3.0 (SE) mmHg/ml (n = 9 dogs) in control run and was increased by 59 +/- 19% under isoproterenol and decreased by 47 +/- 9% after propranolol. Emax was little changed by atrial pacing. We conclude that Emax by this aortic occlusion method is useful for assessment of left ventricular contractility of the in situ dog heart.
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ARAKI, JUNICHI, JUICHIRO SHIMIZU, GENTARO IRIBE, SATOSHI MOHRI, TAKAHIKO KIYOOKA, YU OSIMA, WASO FUJINAKA, YUMIKO DOI, and HIROYUKI SUGA. "ASSESMENT OF TOTAL CA2+ HANDLING FOR EXCITATION-CONTRACTION COUPLING IN BEATING LEFT VENTRICLE." Journal of Mechanics in Medicine and Biology 01, no. 02 (October 2001): 123–38. http://dx.doi.org/10.1142/s0219519401000180.
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We have aimed to assess total Ca 2+ handling in excitation-contraction coupling in a beating left ventricle (LV). Our newly developed integrative analysis method utilizes the internal Ca 2+ recirculation fraction (RF), O2 consumption ( Vo 2) for Ca2+ handling, and O 2 cost of Emax (contractility index) of the LV. We have obtained the O 2 cost of Emax from Vo 2 measured at different contractility levels, and have combined the cost with RF calculated from the beat-constant of the exponential decay component of the postextrasystolic potentiation. Our method calculates the unknown total Ca2+ handling from the RF and the " Ca 2+ handling Vo 2". The calculated total Ca 2+ handling fell between 30 and 110 μmol/kg, depending on contractility and pathological conditions. The present method also enable's reasonable assessment of futile Ca 2+ cycling and of the Ca 2+ reactivity of Emax. Our method seems useful to better understanding of the pathophysiology of total Ca 2+ handling in a beating heart.