Flow-time Curve Research Articles

Experimental study on overtopping failure of concrete face rockfill dam

With the frequent occurrence of natural disasters, the problem of dam failure with low probability and high risk has gradually attracted people's attention. This paper uses flume model tests to systematically analyze the overtopping failure mechanisms of concrete face rockfill dam (CFRD) and identify its failure modes. The tests reveal that the longitudinal erosion of the CFRD breach progress through stages of soil erosion, panel failures, and water flow stabilization. Meanwhile, the cross-section breach process involves the evolution of breach size in rockfill materials, including traceable erosion, lateral broadening, and breach morphology stabilization. The fracture characteristics of the water-blocking panel are primarily evident in the flow-time curve. By analyzing the breach morphology evolution processes in longitudinal and cross sections, the flow-time curve can be subdivided into stages of burst flow formation, breach expansion with flow increase, rapid increase of breach flow discharge due to panel failures, and stabilization of breach flow and size. The primary damage process of the CFRD occurs in a cyclical stage of breach expansion, flow increase, panel failure, and rapid discharge. The rigid face plate and granular body structure contribute to partial dam failure, showing a tendency for gradual expansion of the breach. The longitudinal section illustrates dam failure resulting from panel fracture and rockfill erosion interaction, while downstream slopes exhibit failure due to lateral intrusion of rockfill and cyclic instability. These research results can serve as a reference for constructing a concrete CFRD failure prediction model and conducting disaster risk assessments.

Validation of the fire dynamics simulator (FDS) model for fire scenarios with two liquid pool fires in multiple compartments

A validation study on the fire dynamics simulator (FDS) model for fire scenarios with multiple liquid pool fires occurring in multiple compartments was performed. For fire growth in the open simulation, the mass loss rate per unit area (MLRPUA) time curve obtained experimentally was used as the input. In the blind simulation, the pyrolysis model was used. For the ventilation flow rate curve, the supply/exhaust flow rate curve measured in the experiment was used as the input for the open simulation, whereas the quadratic fan curve model was used for the blind simulation. The time-averaged datasets of the output parameters from the FDS model and experiment were plotted as data points on scatter plots. In terms of bias factor and model standard deviation of output parameters, the scatter plots under the open simulation conditions were compared with those of NUREG-1824. Under blind simulation conditions, the bias factor and model standard deviation of output parameters increased significantly. A sensitivity analysis was performed on input parameters, such as the MLRPUA time curve, supply/exhaust flow time curve, compartment leak area, and maximum differential pressure in the compartment. Within the given ranges of the sensitivity input parameter values, only changing the MLRPAU time curve significantly affected the bias factor and model standard deviation of the output parameters.

Software Development for Thickness Optimization of Tile-Type Thermal Protection System

During the flight mission of hypersonic aircraft, severe aerodynamic heating will occur on the surface, so thermal protection system (TPS) is required to protect the load-bearing structure of the aircraft. The present paper develops an engineering software for automatic optimization of the thickness of tile-type TPS for reusable aircraft. For requirements on TPS of reusable aircraft in the reentry stage, the method of heat flow-time curve enveloping, automatic material selection, and one-dimensional unsteady heat transfer calculation for multilayer plates under thermal load conditions had been researched, an interactive engineering software had been developed. The software improves the calculation accuracy and calculation efficiency of TPS thickness optimization, and it is suitable for rapid design in the conceptual design stage of the aircraft. Finally, by an example, the function of the software is verified.

Cine phase-contrast magnetic resonance imaging evaluation of cerebrospinal fluid flow dynamics in healthy pediatric subjects.

ObjectiveTo evaluate cerebrospinal fluid dynamics, using cine phase-contrast magnetic resonance imaging (cine-PC MRI), in healthy pediatric subjects, determining the normal flow values in this population, as well as identifying differences related to age, sex, and body surface area.Materials and MethodsThis was a descriptive cross-sectional study involving 32 healthy children and adolescents, in whom the flow of cerebrospinal fluid through the cerebral aqueduct was evaluated quantitatively with cine-PC MRI. We used specialized software to analyze the images obtained with cine-PC MRI, drawing a region of interest on the aqueduct. A flow-time curve was obtained, as were automated measurements of the various parameters.ResultsThe following normal (mean) values were obtained: net flow, 1.10 ± 0.99 mL/m; stroke volume, 12.2 ± 10.1 µL/cycle; mean velocity, 0.72 ± 1.00 cm/s; peak systolic velocity, 5.28 ± 2.30 cm/s; peak diastolic velocity, 4.51 ± 1.77 cm/s. These values were not affected by age or sex. In addition, body surface area was not found to correlate significantly with mean velocity or stroke volume.ConclusionIn children and adolescents, the basic cerebrospinal fluid flow parameters, as determined by cine-PC MRI, appear to be independent of age and sex.

Four Truths of Mechanical Ventilation and the Ten-Fold Path to Enlightenment

The Four Truths 1. The truth of confusion 2. The truth of the origin of confusion 3. The truth of the cessation of confusion 4. The truth of the path leading to the cessation of confusion The 10-Fold Path 1. A breath is one cycle of positive flow (inspiration) and negative flow (expiration) defined in terms of the flow-time curve. 2. A breath is assisted if the ventilator does work on the patient. 3. A ventilator assists breathing using either pressure control or volume control based on the equation of motion for the respiratory system. 4. Breaths are classified by the criteria that trigger (start) and cycle (stop) inspiration 5. Trigger and cycle events can be initiated by the patient or the machine. 6. Breaths are classified as spontaneous or mandatory based on both the trigger and cycle events. 7. There are 3 breath sequences: Continuous mandatory ventilation (CMV), Intermittent Mandatory Ventilation (IMV), and Continuous Spontaneous Ventilation (CSV). 8. There are 5 basic ventilatory patterns: VC-CMV, VC-IMV, PC-CMV, PC-IMV, and PC-CSV: 9. Within each ventilatory pattern there are several variations that can be distinguished by their targeting scheme(s). 10. A mode of ventilation is classified according to its control variable, breath sequence, and targeting scheme(s). Keywords: Breath. Trigger, Cycle, Breath sequences, Ventilatory patterns, Mode of ventilation

Analysis of pressure-time and flow-time curve in ventilator

To better understand the significance of the pressure-time curve and flow-time curve from the perspective of PB840 ventilator working principle. (1) Mechanical principle: flow supply valves (air valve and oxygen valve) and exhalation valve in PB840 ventilator were controlled to achieve the ventilation target (volume or pressure) by the central processing unit according to the monitoring data from pressure sensors (P1 at the supply side, P2 at the exhalation side) and flow sensors (Q1 at the air side, Q2 at the oxygen side, Q3 at the exhalation side). (2) The essence of curve: each point means a value of pressure or flow at a certain time measured by the sensors or calculated by the system. (3) The respiratory process could be divided into inspiratory part, expiratory part, and the connection part from expiratory to inspiratory. The air running state and the respiratory mechanics relationship at the three parts could be inferred according to the form of curves. (1) Inspiratory process: at volume-controlled and constant flow ventilation: there should be a relationship "Pc-Pa = XR" between alveolar pressure (Pa) and circuit pressure (Pc) according to Ohm law. So, the Pc curve (pressure-time curve) could indirectly reflect the Pa curve with the flow (X) and resistance (R) being constant. At pressure-set ventilation: it is the goal of ventilator to maintain the Pc at the target level. So, the stability of the target pressure line in pressure-time curve reflects the matching ability of the flow supply valves and the exhalation valve. (2) Expiratory process: it could be divided into pre-expiratory [without basic flow (Ba) or bias flow (Bi)] and post-expiratory (with Ba or Bi), where Ba or Bi is equal to "Q1+Q2". So, the mathematical function are "X(t) = Q3t" in pre-part, and "X(t) = Q3t-(Q1t+Q2t)" in post-part. The relationship between pressure and flow at peak expiratory flow point: it could be found that there is an obvious time span and area formation under the curve from 0 to peak point (Fpeak) after stretching the abscissa axis of flow-time curve. It means that some gas have been discharged from the lung when it arrives at the peak point. So, the alveolar pressure should be lower than the platform pressure at the point (Pplat). The circuit pressure is significantly higher than positive end expiratory pressure (PEEP) at the point in the stretching axis diagram. So, it means that the formula "RE = (Pplat-PEEP)/Fpeak" to calculate the expiratory resistance (E) is unreasonable in the angle of Ohm law. (3) The process from exhalation to inspiratory: according to the difference of the starting point of the conversion, it could be divided into two cases: one is that the inspiratory started from the ending of exhalation. Here, the inhaling starting point is lying in the abscissa axis. The other is that the inspiratory started before the ending of exhalation (with endogenous positive end expiratory pressure). Here, the starting point is lying below the abscissa axis, and the slope of the following curve is obviously larger than the slope of natural expiratory curve. According to the difference of results from the starting point to the end of the inhalation triggering effort, it could be divided into two cases: one is that it reach the trigger point. Here, the expiratory curve extends upward from or below the horizontal axis until an effective air supply is triggered. The other is that it could not reach the trigger point. Here, the expiratory curve extends upward from or below the horizontal axis, but then runs downward (meaning exhaling). It is helpful to analyze the ventilation state, ventilation failure, and the causes of man-machine confrontation with understanding the ventilation principle and the air route map of the ventilator.

Weighted Polynomial Approximation for Automated Detection of Inspiratory Flow Limitation.

Inspiratory flow limitation (IFL) is a critical symptom of sleep breathing disorders. A characteristic flattened flow-time curve indicates the presence of highest resistance flow limitation. This study involved investigating a real-time algorithm for detecting IFL during sleep. Three categories of inspiratory flow shape were collected from previous studies for use as a development set. Of these, 16 cases were labeled as non-IFL and 78 as IFL which were further categorized into minor level (20 cases) and severe level (58 cases) of obstruction. In this study, algorithms using polynomial functions were proposed for extracting the features of IFL. Methods using first- to third-order polynomial approximations were applied to calculate the fitting curve to obtain the mean absolute error. The proposed algorithm is described by the weighted third-order (w.3rd-order) polynomial function. For validation, a total of 1,093 inspiratory breaths were acquired as a test set. The accuracy levels of the classifications produced by the presented feature detection methods were analyzed, and the performance levels were compared using a misclassification cobweb. According to the results, the algorithm using the w.3rd-order polynomial approximation achieved an accuracy of 94.14% for IFL classification. We concluded that this algorithm achieved effective automatic IFL detection during sleep.

Instrument and System for Evaluating Thermal Regulation Properties of Textiles

A test instrument was developed and the testing method was proposed to characterize the thermal regulation properties of textiles based on the mechanical device, microelectronics, sensors and control system. A series of indices were defined based on the typical heat flow-time curve and the raw data to characterize the thermal regulation performance of textiles. The measurement principle, the mechanical device and the evaluation method for the thermal regulation properties of textiles were introduced. Twelve types of fabrics made from different textile materials were tested. The one-way ANOVA analysis was conducted to identify the significance of the differences of the indices among the fabrics. The results show that each index is significantly different (P<0.05) among the different sample fabrics. DOI : http://dx.doi.org/10.11591/telkomnika.v12i6.5497 Full Text: PDF

Measurement Device and System for Temperature Regulation Properties Evaluation of Textile Fabrics

A new measurement system and the testing device was developed to characterize the temperature regulation properties of textile fabrics based on the mechanical device, microelectronics, sensors and control system. A series of indices were defined based on the typical heat flow-time curve and the raw data to characterize the temperature regulation performance of textile fabrics. The measurement principle, the mechanical device and the evaluation method for the temperature regulation properties of textile fabrics were introduced. Twelve types of fabrics made from different textile materials were tested. The one-way ANOVA analysis was conducted to identify the significance of the differences of the indices among the fabrics. The results show that each index is significantly different (P&lt;0.05) among the different sample fabrics.

Implications of carbon dioxide levels in capnography during anaesthesia

Editor, Anaesthesiologists interpret the patient state by obtaining useful information from a monitor screen. In particular, measurements of carbon dioxide levels related to artificial respiration greatly contribute to the safety of the anaesthetized patient.1,2 We present this report because special attention should be given to the interpretation of carbon dioxide waveforms on the monitor. Carbon dioxide curves provide much information on the patient state. On the basis of this information, anaesthesiologists can identify the presence of both artificial and spontaneous respiration. However, when an irregular carbon dioxide curve at the early recovery stage of anaesthesia changes into a regular one as anaesthesia recovery progresses as in Fig. 1, care must be taken to accurately assess the patient state. When carbon dioxide concentration is low at the initial anaesthesia recovery, it is estimated that ventilation is minimal. However, while spontaneous respiration resumes after slight anaesthesia recovery, the carbon dioxide curves sometimes appear in regular patterns and the value is high as in Fig. 1. At that time, tidal volume, that is, the flow rate, is not related to carbon dioxide value. For this reason, tidal volume is either extremely low as in Fig. 1(a) or rather high as in Fig. 1(b). The discrepancy between the carbon dioxide curve and the flow rate may be explained by the fact that the carbon dioxide curve does not represent the absolute value, but the ratio of carbon dioxide to the total expiratory gas. The irregular carbon dioxide basically originates from abrupt initiation of inspiration and expiration during early recovery, which also cause abrupt change of the ratio of carbon dioxide to the total expiration gas. Although tidal volume is relatively small as in Fig. 1(a), it can be presented as such regular patterns and high value if the patient breathes regularly and the ratio of carbon dioxide to the total expiratory gas is periodically changed. Likewise, if carbon dioxide concentration does not increase despite the fact that tidal volume increases from the value in Fig. 1(a) to that in Fig. 1(b), the carbon dioxide curve will be unchanged. In Fig. 1, the carbon dioxide curve indicates that expiratory gas contains approximately 4% (=35/760) carbon dioxide, but it gives little information on tidal volume. Therefore, after anaesthesia recovery progresses to some extent, we should evaluate tidal volume by the movement of the bellows or the patient chest as well as the flow-time curve displayed on a spirometre in an anaesthesia machine instead of the carbon dioxide curve.Fig. 1

Haptoglobin genotype and endothelial function in diabetes mellitus: a pilot study

Endothelial function (EnF) is impaired in patients with diabetes mellitus (DM) due in large part to an increase in oxidative stress. Haptoglobin (Hp) is a potent antioxidant protein which is encoded by two different alleles (1 and 2) with the Hp 1 protein being a superior antioxidant to the Hp 2 protein. We hypothesized that DM individuals with the Hp 2-2 genotype would have greater endothelial dysfunction as compared to DM individuals with the Hp 1-1 genotype. We studied EnF in 16 Hp 2-2, 14 Hp 1-1 DM individuals and 14 healthy subjects. DM patients' groups were matched in terms of age, cardiovascular risk factors and metabolic characteristics. EnF was assessed using post-ischemic reactive hyperemia and strain gauge plethysmography and expressed either as the maximal flow after the ischemic period or as the area under the flow-time curve (AUC). We showed that EnF indices, AUC and maximal flow, were also higher in the healthy and Hp 1-1 groups compared with Hp 2-2 genotype group (615 +/- 60 and 600 +/- 40 vs. 450 +/- 50 ml dl(-1), 29 +/- 2.6 and 25 +/- 3 vs. 14 +/- 1.8 ml min(-1) dl(-1), P < 0.003 and P < 0.05, for AUC and maximal flow, one-way ANOVA, respectively). We concluded that Hp 2-2 diabetic patients had a worse EnF than controls and Hp 1-1 diabetic subjects.

Penile and Systemic Endothelial Function in Men with and without Erectile Dysfunction

BackgroundAssessment of endothelial function can provide essential information about the mechanisms of cardiovascular disease. Emerging data show that erectile dysfunction (ED) can precede the symptoms of ischemic heart disease, and this suggests that endothelial dysfunction is the link between these two clinical entities. ObjectiveTo evaluate penile and systemic endothelial function in subjects with and without ED. Design, setting, and participantsFifty-nine subjects were enrolled in the study. According to their International Index of Erectile Function (IIEF) ED domain scores, they were divided into two groups: 40 patients with ED and 19 men without ED (control group). Hemodynamic measurements, penile endothelial function, and forearm endothelial function were assessed in all participants using veno-occlusive plethysmography. MeasurementsWe measured baseline blood flow in both the forearm and the penis and calculated the corresponding vascular resistances. Postischemic changes in blood flow were recorded serially in both organs for the evaluation of endothelial function. Area under the flow-time curve (AUC), and maximal blood flow after ischemia were considered to be the indices of endothelial function. Results and limitationsGeneral characteristics of the two groups of participants were comparable except for age (40.5±3.3 yr in the control group vs 53.3±2.3 yr in the ED group). Baseline forearm blood flow was similar in the two groups, but the penile blood flow was significantly lower in men with ED compared with that in the men without ED: 6.2±0.6 versus 8.6±0.6ml/min per 100ml of tissue (p=0.006). Penile vascular resistance was higher in the ED group compared with the control group. The indices of forearm endothelial function were comparable in both groups (p=0.70 for the AUCs). However, indices of penile endothelial function were significantly higher in the control group compared with those of the ED group (AUC: 950 units±130 vs 450±80 units, p=0.001). ConclusionsThe use of veno-occlusive plethysmography for evaluating penile endothelial function is simple and reliable and provides new information on the pathophysiology of ED at the level of penile vasculature. This is the first study that provides evidence of impaired penile endothelial function without the presence of a significant peripheral endothelial dysfunction. Furthermore, these results provide further support for the notion that the development of ED could predict the future onset of cardiovascular disease.

Experimental Model of Lower Limb Ischemia in Rats and the Effect of YM466, an Oral Direct Factor Xa Inhibitor

A simple, quantitative, and reproducible model of lower limb ischemia was developed. Vascular injury was induced by ferric chloride (FeCl(3)) solution to the rat iliac artery, after which blood flow in all of the lower limbs were continuously monitored using a scanning laser Doppler blood flowmeter. After FeCl(3) injury, a distinct decrease in blood flow in the ischemic lower limb was observed and blood flow did not recover during the 30 min after vascular injury. YM466, an oral direct factor Xa inhibitor, dose-dependently inhibited the reduction of peripheral blood flow. The area under the blood flow-time curve during 30 min after vascular injury improved dose-dependently, with significance at doses of 3 and 10 mg/kg. These results suggest that factor Xa inhibitors are effective in patients with peripheral arterial disease, and that this vascular injury model is a useful tool for the screening and evaluation of the efficacy of new antithrombotic agents.

A NEW CLINICAL METHOD FOR THE ASSESSMENT OF PENILE ENDOTHELIAL FUNCTION USING THE FLOW MEDIATED DILATION WITH PLETHYSMOGRAPHY TECHNIQUE

Penile endothelial function (EnF) is 1 of the major factors involved in the pathophysiology of erectile dysfunction. EnF assessment could offer crucial information on the etiology and degree of severity of cavernosal vascular pathology. In the present study we propose a new technique for the evaluation of penile EnF and test its applicability using strain gauge plethysmography. A total of 23 healthy subjects (13 younger and 10 older than 40 years) with no history of erectile dysfunction were studied. The flow mediated dilation technique was applied to the arm and penis in both age groups for the assessment of EnF. Baseline blood flow and the sequential flow recordings after rapid cessation of 5 minutes of ischemia were obtained in both organs. Baseline flow in the penis was significantly higher (approximately 3-fold) than that in the forearm and was not affected by age in either organ. Both measures of penile EnF, ie area under the flow-time curve (AUC) and maximal flow obtained after ischemia were significantly lower in the older group compared to the younger group (p <0.01 and p <0.02, respectively). Individual penile AUC and maximal flow were significantly correlated with age (r = 0.55, p <0.01 and r = 0.50, p <0.02, respectively). Finally a positive, significant correlation existed between penile and forearm AUC (p <0.05, r = 0.48). The implementation of the flow mediated dilation technique using mercury strain gauge plethysmography is simple and applicable for the assessment of penile EnF. Endothelial function parameters in the penis were found to correlate with those in the forearm, thus support for the validity of the technique is given. Further strength for the validity of this procedure in the penis comes from the comparison between the forearm and penis, and the relation to subject age.

Examination of the growth of probiotic culture combinations by the isoperibolic batch calorimetry

Probiotic (“intestinal friend”) foods, and probiotic dairy products in particular, have substantially increased in number recently. In the production of some of these products a problem is caused by the fact that the thermotolerant microbes that produce the probiotic effect do not generate an aroma; the taste of the product is given by aroma-producing mesophilic microbes. The growth optima of the two microbe groups do not coincide. Given that heat is released in the course of microbe reproduction, the isoperibolic calorimetry method appears the best and fastest for monitoring the process. During the experiments the thermotolerant Prebiolact, owned by the Hungarian Dairy Research Institute (HDRI) and clinically verified to be probiotic, and Hansen Company’s CHN-22 mesophilic butter culture were examined bred separately and together. The cultures were incubated at 30 °C, at which temperature prior studies had shown both lactic acid bacteria cultures were capable of growing. The cultures were injected into milk, then the microbe growth heat flow-time curve over 18 h was taken on the Setaram Micro DSC-II calorimeter at 30 °C under isothermic conditions. Analysis of the heat flow curves led to the following conclusions. Both lactic acid bacteria cultures grow well at the non-optimal temperature of 30 °C, thermotolerant Prebiolact somewhat faster and mesophilic CHN-22 slower. The two cultures do not impede each other in mixed cultures; the growth peaks of the two cultures were easily isolated on the power–time curve by a deconvolution program. In sum it can be stated that mixed cultures of the two cultures examined can be used to produce dairy products which are probiotic, but their taste character (e.g. aroma) is determined by the butter culture. To date we have elaborated production procedures for probiotic butter cream and heat-resistant sour cream using the two cultures in a mixed one.

Vasodilator prostanoids, but not nitric oxide, may account for skeletal muscle hyperaemia in Type I diabetes mellitus

We and others have previously documented increased resting and exercise-induced skeletal muscle blood flow in young subjects with Type I (insulin-dependent) diabetes mellitus compared with healthy controls. Both NO and prostanoids are important regulators of vascular tone and may therefore contribute to this hyperaemia. The aim of the present study was to determine the contribution of NO and vasodilator prostanoids to this skeletal muscle hyperaemia in diabetes. We assessed the effects of infusion into the intrabrachial artery of the cyclo-oxygenase inhibitor acetylsalicylic acid (ASA; aspirin) and of the L-arginine analogue N(G)-monomethyl-L-arginine (L-NMMA) on skeLetal muscle blood flow in subjects with Type I diabetes mellitus (DM subjects) and control subjects. Blood flow was measured by venous occlusion plethysmography. Isotonic forearm exercise involved 2 min of wrist flexion and extension. Resting flow (forearm blood flow; FBF) was augmented in DM subjects, as was peak exercise-related blood flow (PFBF) and the volume repaid to the forearm 5 min after exercise (AUC 5, where AUC is area under the flow-time curve) (P<0.05), even when accounting for differences in basal flow. Infusion of L-NMMA reduced resting flow by 48% in controls (P<0.005) and by 12% in DM subjects (not significant). L-NMMA reduced PFBF and AUC 5 by 29% (P<0.05) and 39% (P<0.0005) respectively in controls, but had no significant effect on these parameters in DM subjects. Infusion of ASA reduced FBF, PFBF and AUC 5 in both DM (P<0.05) and control (P<0.05) subjects, but the magnitude of this reduction was greater in DM than in control subjects (ANOVA, P<0.05), even when differences in resting FBF were accounted for. Indeed, ASA eliminated the differences in FBF, PFBF and AUC 5 between DM and control subjects. Thus increased release of vasodilator prostanoids, rather than of NO, appears to account for skeletal muscle hyperaemia in Type I diabetes.

Standard flow-time waveforms for testing of PEF meters.

The American Thoracic Society (ATS) has recommended the use of 24 volume-time waveforms for the testing of spirometers. Although these waveforms include values of peak expiratory flow (PEF), they were not originally intended to test PEF meters, but, rather, volume parameters for spirometers. In addition, the practice of using ATS volume-time Waveform 24 with varying multiplying factors does not provide the range of flow-time waveform shapes (rise times) needed to evaluate PEF meters. Accordingly, we have developed a set of 26 flow-time waveforms specifically selected to evaluate PEF meters. PEF and other flow parameters (rise time and time to PEF) can be directly measured from these flow-time waveforms. When PEF determined directly from the flow-time curve was compared with PEF determined indirectly from a volume-time curve (ATS-recommended algorithm with an 80 ms time segment), as much as a 10.7% difference between the two methods was observed using a waveform with a fast rise time. In contrast, there was very little difference between the various methods of deriving PEF for waveforms with slower rise times. These 26 flow-time waveforms provide a means of defining PEF for the testing of software algorithms and the testing of PEF meters with computer-driven mechanical pumps.

Differential effects of ATP- and 2-methylthioATP-induced relaxation in guinea pig coronary vasculature.

The Langendorff heart preparation was used to investigate the mechanism of action of vasodilatation evoked by ATP and its analogues in guinea pig coronary vasculature. The relative order of potency of ATP and its analogues in causing a reduction in perfusion pressure was 2-methylthioATP (2-meSATP) > ATP > beta, gamma-methyleneATP (beta,gamma-meATP) > or = alpha,beta-methyleneATP (alpha,beta-meATP), thus establishing the presence of P2y-purinoceptors in this preparation. L-NG-nitroarginine methyl ester (L-NAME, 3 x 10(-5) M) significantly attenuated both the area under the flow-time curve and the maximum decrease in perfusion pressure of the vasodilatation produced in response to 2-meSATP (5 x 10(-12)-5 x 10(-9) mol). However, for ATP (5 x 10(-7)-5 x 10(-10) mol), L-NAME 3 x 10(-5) M significantly attenuated the area under the flow-time curve of the response but did not reduce the maximum decrease in perfusion pressure except at one low dose (5 x 10(-10) mol). L-Arginine 1.5 x 10(-3) M significantly reversed inhibition of the area under the flow-time curve of the response to 2-meSATP 5 x 10(-10) mol and ATP 5 x 10(-8) mol by L-NAME 3 x 10(-5) M. The maximum decrease in perfusion pressure of the response to ATP 5 x 10(-10)-5 x 10(-7) mol was significantly attenuated in the presence of indomethacin 10(-6) M.(ABSTRACT TRUNCATED AT 250 WORDS)

The pattern of resting breathing in patients with upper airway obstruction

The flow-time curve of resting breathing was recorded in 14 patients (aged 36 +/- 16 yrs) with mild to moderate symptoms of upper airway obstruction (UawO) and compared to that of 28 matched, healthy controls (HC) in order to characterize the breathing pattern of such patients. The inspiratory time over total time (TI/Ttot) was higher in the patients (0.42; SD 0.04) than in HC (0.37; SD 0.04) (p less than 0.001), and tidal volume (VT) over TI was lower in patients (0.37; SD 0.07 l.s-1) than in HC (0.43; SD 0.09 l.s-1) (p less than 0.01). Inspiratory and expiratory peak flows at rest were also lower in the patients (p less than 0.001). In these, the mean to peak flow ratio of inspiration (0.74; SD 0.07) was higher than in HC (0.66; SD 0.04) (p less than 0.0005). This indicates a more rectangular wave of inspiration in the patients. All of these changes may be due to the increased inspiratory load. However, since the patients were breathing at rest with VT and flows far below their values on the maximal flow volume loop, the changes can also be interpreted as adaptive rather than imposed by absolute mechanical limitations.

Airway constriction in experimental asthma in dogs: tantalum bronchographic studies.

ArticleAirway constriction in experimental asthma in dogs: tantalum bronchographic studies.G F Kessler, J H Austin, P D Graf, G Gamsu, and W M GoldG F Kessler, J H Austin, P D Graf, G Gamsu, and W M GoldPublished Online:01 Nov 1973https://doi.org/10.1152/jappl.1973.35.5.703MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByAsthmaAsthmaAcute effects of ozone exposure on lung function in mice sensitized to ovalbuminToxicology, Vol. 172, No. 1Effects of Dexamethasone on Antigen-Induced Airway Eosinophilia and M 2 Receptor DysfunctionAmerican Journal of Respiratory and Critical Care Medicine, Vol. 163, No. 6Individual Canine Airways Responsiveness to Aerosol Histamine and Methacholine in VivoAmerican Journal of Respiratory and Critical Care Medicine, Vol. 157, No. 2Localization of the Bronchodilatory Effects of Isoproterenol and Aminophylline in Patients with Bronchial Asthma: An Investigation Using Selective Alveolobronchography25 June 2016 | Journal of International Medical Research, Vol. 25, No. 6Increased response to antigen and histamine release in smaller sensitized canine bronchiRespiration Physiology, Vol. 103, No. 3Morphologic Basis of Airflow ObstructionAerosol-derived airway dimensions of dog lungs in histamine-induced bronchoconstrictionJournal of Aerosol Science, Vol. 24, No. 5Assessment by Aerosol Recovery Technique of Site of Airway Constriction During Intravenous Histamine ChallengeReflexes Evoked from Tracheobronchial Tree and Lungs1 January 2011The Basenji-Greyhound Dog Model of AsthmaChest, Vol. 87, No. 5Anticholinergic drugs in the treatment of airways diseaseBritish Journal of Diseases of the Chest, Vol. 79Afferent vagal C fibre innervation of the lungs and airways and its functional significance21 June 2005Responsiveness of isolated tracheal smooth muscle in a canine model of asthmaLung, Vol. 160, No. 1The Basenji-Greyhound dog: Antigen-induced changes in lung volumesRespiration Physiology, Vol. 43, No. 3Moment analysis of the flow-time curve after breathing gases of different densities.Thorax, Vol. 36, No. 1Pathogenesis of Bronchial AsthmaComparative Bronchodilator Responses to Atropine and Terbutaline in Asthma and Chronic BronchitisChest, Vol. 72, No. 6Physiologic basis and interpretation of common indices of respiratory mechanical function.Environmental Health Perspectives, Vol. 16The effect of cholinergic agents on a canine model of allergic asthmaJournal of Allergy and Clinical Immunology, Vol. 58, No. 1Bronchial hyperreactivityBritish Journal of Diseases of the Chest, Vol. 69Antigen-induzierte Reflexbronchokonstriktion beim HundPneumonologie Pneumonology, Vol. 150, No. 2-4 More from this issue > Volume 35Issue 5November 1973Pages 703-8 https://doi.org/10.1152/jappl.1973.35.5.703PubMed4770354History Published online 1 November 1973 Published in print 1 November 1973 Metrics