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Pressure Response (pressure + response)
Kinds of Pressure Response Selected AbstractsHeritability of the Blood Pressure Response to Acute Ethanol Exposure in Five Inbred Strains of MiceALCOHOLISM, Issue 10 2000Daniel C. Hatton Background: Chronic alcohol consumption is a major risk factor for hypertension. There is evidence in humans that the susceptibility to alcohol-related hypertension may vary based on genotype. As a first step in investigating the genetic basis for alcohol-related hypertension, the current study was designed to assess the heritability of the blood pressure response to acute ethanol exposure by using AKR/J (AK), C57BL/6J (B6), DBA/2J (D2), Balb/cJ (Balb), and A/J (A) mice. Methods: Mean arterial pressure (MAP) was recorded continuously for 24 hr in freely moving mice from an indwelling femoral catheter before we tested the effects of saline or ethanol (2 g/kg ip) on blood pressure. Results: Relative to saline, ethanol caused a pressor response that peaked within 10 min, followed by a decline in MAP. Strain A mice had a significantly greater pressor response to ethanol than other strains and did not show a decline in MAP below baseline. All other strains showed a progressive fall in blood pressure below baseline across the 60 min measurement interval. Heritability was estimated to be 0.62 for the pressor response and 0.64 for the maximal depressor response. Repeated doses of ethanol at 1 hr intervals in A and B6 mice (0,2,1.5,1.5,1.5 g/kg ip) resulted in a dose-dependent increase in MAP in A mice for the first three doses and a dose-dependent decrease in MAP in B6 mice that was independent of blood ethanol concentrations. Conclusion: The results indicate that there is a significant genetic component to the acute blood pressure response to ethanol. [source] High Pressure Response of Rutile Polymorphs and Its Significance for Indicating the Subduction Depth of Continental CrustACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 2 2008MENG Dawei Abstract: ,-PbO2 -type TiO2 (TiO2 -II) is an important index mineral for ultrahigh-pressure metamorphism. After the discovery of a natural high-pressure phase of titanium oxide with ,-PbO2 -structure in omphacite from coesite-bearing eclogite at Shima in the Dabie Mountains, China, a nano-scale (<2 nm) ,-PbO2 -type TiO2 has been identified through electron diffraction and high-resolution transmission electron microscopy in coesite-bearing jadeite quartzite at Shuanghe in the Dabie Mountains. The crystal structure is orthorhombic with lattice parameters a = 4.58times10,1 nm, b = 5.42times10,1 nm, c = 4.96times10,1 nm and space group Pbcn. The analysis results reveal that rutile {011}R twin interface is a basic structural unit of ,-PbO2 -type TiO2. Nucleation of ,-PbO2 -type TiO2 lamellae is caused by the displacement of one half of the titanium cations within the {011}R twin slab. This displacement reduces the Ti-O-Ti distance and is favored by high pressure. The identification of ,-PbO2 -type TiO2 in coesite-bearing jadeite quartzite from Shuanghe, Dabie Mountains, provides a new and powerful evidence of ultrahigh-pressure metamorphism at 4,7 GPa, 850°C-900°C, and implies a burial of continental crustal rocks to 130,200 kilometers depth or deeper. The ,-PbO2 -type TiO2 may be a useful indicator of the pressure and temperature in the diamond stability field. [source] Blood Pressure Response to the ImpedanceThreshold Device in Hypotensive Emergency Department PatientsACADEMIC EMERGENCY MEDICINE, Issue 2008Samuel Luber Background:, An impedance threshold device (ITD) has been found to enhance circulation during CPR by increasing cardiac preload. Additionally, in the spontaneously breathing patient, the ITD has been found to create a small degree of inspiratory resistance (-6 cm H2O at flow rate of 20L/min). Hypothesis: We sought to determine the effects of the ITD on awake patients with hypotension presenting to the emergency department. We hypothesized that the ITD would improve blood pressure when compared to standard therapy. The main outcome measure was the systolic blood pressure (SBP) change during 10 minutes of ITD use. Methods:, A convenience sample of patients with SBPs <95 mmHg were randomized in double-blind fashion to active or sham ITDs. Patients were enrolled if they were between the ages of 18 and 70 and their hypotension was felt to be due to non-traumatic blood loss or dehydration by the treating physician. Patients were excluded if they were experiencing shortness of breath, chest pain, failed the abbreviated mini-mental status exam, or had predefined cardiac/pulmonary history criteria. After consent and baseline measurements, patients spontaneously breathed through a mouthpiece attached to an active or sham ITD for a 10 minute period during which vital signs and patient status were recorded. Results:, 12 patients were enrolled (5 randomized to the active device, 7 to the sham device). Mean baseline SBPs were similar between groups with the active and sham devices having baseline SBPs of 84.5 mmHg (SD 5.45) and 83.67 mmHg (SD 10.02), respectively. The active ITD produced a statistically significant (p = 0.03) increase in SBP of 13.0 mmHg (SD 4.69) compared to the sham ITD, 2.33 mmHg (SD 0.58). Conclusions:, In spontaneously breathing hypotensive ED patients, the ITD was well-tolerated and increased the SBP. If these results are validated with a larger sample, the ITD may be a useful adjunct in the treatment of hypotension due to volume loss in the ED. [source] 2,2,-Nitrophenylisatogen potentiates P2X1 receptor mediated vascular contraction and blood pressure elevationDRUG DEVELOPMENT RESEARCH, Issue 1 2003Anna-Karin Wihlborg Abstract The objective of this research was to examine the effects of chemical compounds with possible P2 receptor modulating effects and to characterize the potentiating effects of 2,2,-nitrophenylisatogen (NPI) on P2X1 receptors in vitro and in vivo. Chemical compounds were tested in an in vitro pharmacological assay using vascular segments from the rat mesenteric artery stimulated by P2 receptor-specific agonists. Contractions were expressed as a percentage of 60 mM K+ -induced contractions. Blood pressure was evaluated in pithed rats. NPI (30 ,M) added 15 min before addition of the P2X1 receptor-specific agonist ,,-MeATP increased the maximum vasoconstriction from 23% to 49% (an increase of 113%). Furthermore, NPI prevented the desensitization of repeated ,,-MeATP contractions. Related compounds were examined, and 2-(3-methoxy-phenyl)-1-oxy-indol-3-one (MPI) had similar effects as NPI, but several others lacked effect. NPI had no effect on ADP,S (P2Y1) or acetylcholine-mediated vasodilatation, nor on UTP (P2Y2/4), UDP (P2Y6), or noradrenaline-mediated contractions. In pithed rats, the blood pressure response to 50 nmol/kg-infusion of ,,-MeATP was increased from 50±6 to 63±5 mmHg (P<0.05), but had no effect on basal blood pressure or on the cardiovascular response to preganglionic nerve stimulation. In conclusion, NPI and MPI potentiates P2X1 receptor vascular contractions in vitro and (NPI) blood pressure effects in vivo. It is possible that the effect is mediated by an inhibition of P2X1 receptor desensitization. Drug Dev. Res. 59:82,87, 2003. © 2003 Wiley-Liss, Inc. [source] Premotor sympathetic neurons of conditioned fear in the ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2008Pascal Carrive Abstract Conditioned fear to context, a pure form of psychological stress, is associated with sympathetically mediated changes including a marked hypertension. To identify the possible premotor sympathetic neurons mediating these changes, we conducted double-immunolabelling experiments combining fear-induced Fos with retrograde tracing from the thoracic cord (T2-L1). Presympathetic groups showing the greatest increase in the proportion of spinally projecting cells double-labelled with Fos compared with resting controls were the perifornical area (PeF; 22.7% vs. 0.4%) and paraventricular nucleus (Pa; 10.5% vs. 0.2%) in the hypothalamus, and the A5 noradrenergic group (33.6% vs. 0.2%) in the pons. In contrast, there was only a small increase in the presympathetic groups of the rostral ventral medulla, including the lateral paragigantocellular group (LPGi; 4.3% vs. 0.5%), raphe magnus and pallidus (1.1% vs. 0.6% and 1.8% vs. 0.5%), and the vasopressor group of the rostral ventrolateral medulla (RVLM; 1.9% vs. 0.8%). PeF, Pa, A5 and LPGi accounted for 21, 15, 16 and 6% of all the double-labelled cells, respectively, and RVLM for only 1%. Double-immunolabelling of Fos and tyrosine hydroxylase confirmed that many A5 neurons were activated (19%) and that practically no C1 neurons in RVLM were (1.3%). The results suggest that the main premotor sympathetic drive of the fear response comes from hypothalamic (PeF and Pa) and A5 neurons that project directly to the thoracic cord and bypass medullary presympathetic groups, and that the vasopressor premotor sympathetic neurons of the RVLM are unlikely to mediate the hypertensive pressure response of contextual fear. [source] The baroreflex is counteracted by autoregulation, thereby preventing circulatory instabilityEXPERIMENTAL PHYSIOLOGY, Issue 4 2004Roberto Burattini The aims of this study were (a) to apply in the animal with intact baroreflex a two-point method for estimation of overall, effective open-loop gain, G0e, which results from the combined action of baroregulation and total systemic autoregulation on peripheral resistance; (b) to predict specific baroreflex gain by correcting the effective gain for the autoregulation gain; and (c) to discuss why the effective gain is usually as low as 1,2 units. G0e was estimated from two measurements of both cardiac output, Q, and mean systemic arterial pressure, P: one in the reference state (set-point) and the other in a steady-state reached 1,3 min after a small cardiac output perturbation. In anaesthetized cats and dogs a cardiac output perturbation was accomplished by partial occlusion of the inferior vena cava and by cardiac pacing, respectively. Average (±s.e.m.) estimates of G0e were 1.4 ± 0.2 (n= 8) in the cat and 1.5 ± 0.4 (n= 5) in the dog. The specific baroreflex open-loop gain, G0b, found after correction for total systemic autoregulation, was 3.3 ± 0.4 in the cat and 2.8 ± 0.8 in the dog. A model-based analysis showed that, with G0e as low as 1.4, the closed-loop response of P to a stepwise perturbation in Q results in damped oscillations that disappear in about 1 min. The amplitude and duration of these oscillations, which have a frequency of about 0.1 Hz, increase with increasing G0e and cause instability when G0e is about 3. We conclude that autoregulation reduces the effectiveness of baroreflex gain by about 55%, thereby preventing instability of blood pressure response. [source] Hydraulic observations from a 1 year fluid production test in the 4000 m deep KTB pilot boreholeGEOFLUIDS (ELECTRONIC), Issue 1 2006W. GRÄSLE Abstract A long-term pump test was conducted in the KTB pilot borehole (KTB-VB), located in the Oberpfalz area, Germany. It produced 22 300 m3 of formation fluid. Initially, fluid production rate was 29 l min,1 for 4 months, but was then raised to an average of 57 l min,1 for eight more months. The aim of this study was to examine the fluid parameters and hydraulic properties of fractured, crystalline crusts as part of the new KTB programme ,Energy and Fluid Transport in Continental Fault Systems'. KTB-VB has an open-hole section from 3850 to 4000 m depth that is in hydraulic contact with a prominent continental fault system in the area, called SE2. Salinity and temperature of the fluid inside the borehole, and consequently hydrostatic pressure, changed significantly throughout the test. Influence of these quantities on variations in fluid density had to be taken into account for interpretation of the pump test. Modelling of the pressure response related to the pumping was achieved assuming the validity of linear Darcy flow and permeability to be independent of the flow rate. Following the principle ,minimum in model dimension', we first examined whether the pressure response can be explained by an equivalent model where rock properties around the borehole are axially symmetric. Calculations show that the observed pressure data in KTB-VB can in fact be reproduced through such a configuration. For the period of high pumping rate (57 l min,1) and the following recovery phase, the resulting parameters are 2.4 × 10,13 m3 in hydraulic transmissivity and 3.7 × 10,9 m Pa,1 in storativity for radial distances up to 187 m, and 4.7 × 10,14 m3 and 6.0 × 10,9 m Pa,1, respectively, for radial distances between 187 and 1200 m. The former pair of values mainly reflect the hydraulic properties of the fault zone SE2. For a more realistic hydraulic study on a greater scale, program FEFLOW was used. Parameter values were obtained by matching the calculated induced pressure signal to fluid-level variations observed in the KTB main hole (KTB-HB) located at 200 m radial distance from KTB-VB. KTB-HB is uncased from 9031 to 9100 m and shows indications of leakage in the casing at depths 5200,5600 m. Analysis of the pressure record and hydraulic modelling suggest the existence of a weak hydraulic communication between the two boreholes, probably at depths around the leakage. Hydraulic modelling of a major slug-test in KTB-HB that was run during the pumping in KTB-VB reveals the effective transmissivity of the connected formation to be 1 to 2 orders of magnitude lower than the one determined for the SE2 fault zone. [source] The Mandel,Cryer effect in chemoporoelasticityINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2010A. P. Bunger Abstract Chemoporoelastic theory is an extension of classical Biot poroelasticity that accounts for coupling with the presence and the transport of ions in the pore fluid. The impact of this extra level of coupling can be both substantial and complex. This paper relies on the two variations of Mandel's classical problem, which has become a canonical illustration of the complexity that poromechanical coupling can bring to an otherwise straightforward system. To this end, solutions for a chemoporoelastic shale cylinder and a spherical shale ball are derived. These solutions are then used to demonstrate that chemoporoelastic coupling leads to a coupled pore pressure response that is not only non-monotonic, as in Mandel's classical case, but also demonstrates the consequences of the semi-permeable membrane-like nature of the shale and of the problem's two diffusion-related timescales. This paper concludes with a discussion of the implications of these results for experimentation and modeling of so-called reactive shales using chemoporoelastic theory. Copyright © 2009 John Wiley & Sons, Ltd. [source] Identifying Early Cardiovascular Disease to Target Candidates for TreatmentJOURNAL OF CLINICAL HYPERTENSION, Issue 3 2008Daniel A. Duprez MD Most attempts to identify individuals at risk for cardiovascular morbid events have involved screening for risk factors. These traditional risk factors do not identify the underlying atherosclerotic disease nor assess the severity of disease in individual patients. The goal for identifying a marker or markers for early cardiovascular disease that could serve as a surrogate for disease progression and ultimate morbid events is to improve the precision for early detection and treatment. The authors utilize a variety of techniques, which consist of 7 vascular tests (large and small artery elasticity, resting blood pressure and exercise blood pressure response, optic fundus photography, carotid intimal-media thickness, and microalbuminuria) and 3 cardiac tests (electrocardiography, [N-terminal pro-] B-type natriuretic peptide, and left ventricular ultrasonography). Each test is individually scored, and the total disease score is the sum of all the test scores. A study is ongoing to compare the new disease score vs the classical Framingham risk estimate in the prediction of cardiovascular events. [source] Physical activity and exercise performance predict long-term prognosis in middle-aged women surviving acute coronary syndromeJOURNAL OF INTERNAL MEDICINE, Issue 2 2007F. Al-Khalili Abstract. Aim., To evaluate the importance of exercise testing (ET) parameters and leisure time physical activity in predicting long-term prognosis in middle-aged women hospitalized for acute coronary syndrome (ACS). Methods and results., Women aged <66 years recently hospitalized for ACS in the Greater Stockholm area in Sweden were recruited. All underwent baseline clinical examinations including ET and then were followed up for 9 years. Nonparticipation in ET had a hazard ratio of 4.26 (95% confidence interval 2.02,8.95) for total mortality and 3.03 (1.03,8.91) for cardiovascular mortality. All ET parameters were significantly different between survivors than nonsurvivors, except for chest pain and ST-segment depression during ET. Sedentary lifestyle and ET parameters were related to total mortality and cardiovascular mortality in a multivariate analysis adjusting for potential confounders. Predictors of total mortality were sedentary lifestyle 2.94 (1.31,6.62), exercise time 1.75 (1.07,2.87) and inadequate haemodynamic responses: low increase in pulse rate 2.04 (1.16,3.60) and systolic blood pressure (SBP) 1.88 (1.19,2.95) from rest to peak exercise. Parameters that predicted cardiovascular mortality were sedentary lifestyle 3.15 (1.13,8.74) and poor increase in SBP 2.76 (1.30,5.86) from rest to peak exercise. The relation of sedentary lifestyle to survival was substantially weakened when exercise parameters were added to the multivariate analysis model. Conclusion., In female patients <66 years surviving ACS, important independent predictors of long-term all-cause mortality were sedentary lifestyle, low physical fitness and inadequate pulse rate and SBP increase during exercise. Predictors of cardiovascular mortality were sedentary lifestyle and inadequate blood pressure response during exercise. [source] Heritability of the Blood Pressure Response to Acute Ethanol Exposure in Five Inbred Strains of MiceALCOHOLISM, Issue 10 2000Daniel C. Hatton Background: Chronic alcohol consumption is a major risk factor for hypertension. There is evidence in humans that the susceptibility to alcohol-related hypertension may vary based on genotype. As a first step in investigating the genetic basis for alcohol-related hypertension, the current study was designed to assess the heritability of the blood pressure response to acute ethanol exposure by using AKR/J (AK), C57BL/6J (B6), DBA/2J (D2), Balb/cJ (Balb), and A/J (A) mice. Methods: Mean arterial pressure (MAP) was recorded continuously for 24 hr in freely moving mice from an indwelling femoral catheter before we tested the effects of saline or ethanol (2 g/kg ip) on blood pressure. Results: Relative to saline, ethanol caused a pressor response that peaked within 10 min, followed by a decline in MAP. Strain A mice had a significantly greater pressor response to ethanol than other strains and did not show a decline in MAP below baseline. All other strains showed a progressive fall in blood pressure below baseline across the 60 min measurement interval. Heritability was estimated to be 0.62 for the pressor response and 0.64 for the maximal depressor response. Repeated doses of ethanol at 1 hr intervals in A and B6 mice (0,2,1.5,1.5,1.5 g/kg ip) resulted in a dose-dependent increase in MAP in A mice for the first three doses and a dose-dependent decrease in MAP in B6 mice that was independent of blood ethanol concentrations. Conclusion: The results indicate that there is a significant genetic component to the acute blood pressure response to ethanol. [source] Vagal dysfunction in irritable bowel syndrome assessed by rectal distension and baroreceptor sensitivityNEUROGASTROENTEROLOGY & MOTILITY, Issue 4 2008R. Spaziani Abstract, Autonomic nervous system dysfunction has been implicated in the pathophysiology of irritable bowel syndrome (IBS). This study characterized the autonomic response to rectal distension in IBS using baroreceptor sensitivity (BRS), a measure of autonomic function. Rectal bag pressure, discomfort, pain, ECG, blood pressure and BRS were continuously measured before, during and after rectal distension in 98 healthy volunteers (34 ± 12 years old, 52 females) and 39 IBS patients (39 ± 11 years old, 35 females). In comparison with the healthy volunteers, IBS patients experienced significantly more discomfort (69 ± 2.2% vs 56 ± 3.6%; P < 0.05), but not pain (9 ± 1.4% vs 6 ± 2.4%; ns) with rectal distension despite similar distension pressures (51 ± 1.4 vs 54 ± 2.4 mmHg; ns) and volumes (394 ± 10.9 vs 398 ± 21.5 mL; ns). With rectal distension, heart rate increased in both healthy volunteers (66 ± 1 to 71 ± 1 bpm; P < 0.05) and IBS patients (66 ± 2 to 74 ± 3 bpm; P < 0.05). Systolic blood pressure also increased in both healthy volunteers (121 ± 2 to 143 ± 2 mmHg; P < 0.05) and patients (126 ± 3 to 153 ± 4 mmHg (P < 0.05) as did diastolic blood pressure, 66 ± 2 to 80 ± 2 mmHg (P < 0.05), compared with 68 ± 3 to 84 ± 3 mmHg (P < 0.05) in IBS patients. The systolic blood pressure increase observed in IBS patients was greater than that seen in healthy volunteers and remained elevated in the post distension period (139 ± 3 mmHg vs 129 ± 2 mmHg; P < 0.05). IBS patients had lower BRS (7.85 ± 0.4 ms mmHg,1) compared with healthy volunteers (9.4 ± 0.3; P < 0.05) at rest and throughout rectal distension. Greater systolic blood pressure response to rectal distension and associated diminished BRS suggests a compromise of the autonomic nervous system in IBS patients. [source] Vasopressin in the treatment of vasodilatory shock in childrenPEDIATRICS INTERNATIONAL, Issue 2 2005Satoshi Masutani Abstract,Background:,Many recent studies suggest that vasopressin deficiency is an important cause of catecholamine-resistant hypotension with vasodilation in adults, but little is known about vasopressin deficiency in children. Methods:,To clarify the usefulness of vasopressin administration in pediatric cathecolamine-resistant hypotension with preserved ventricular contractility, urinary output and blood pressure response to vasopressin were retrospectively analyzed in 12 consecutive patients (15 instances) who were treated with vasopressin. The causes of vasodilation were central nervous system disturbance (n = 5), side-effect of drug (n = 5), and infection (n = 5). Plasma vasopressin concentration was measured six times before vasopressin administration and five times during vasopressin administration. Results:,Patients were divided into four groups according to their response to vasopressin administration. In group 1 (n = 5), urinary output increased to > 3 mL/kg per h within 3 h after vasopressin administration. In group 2 (n = 4), urinary output increased to > 3 mL/kg per h from 3 to 5 h after vasopressin administration. In group 3 (n = 4), urinary output did not increase to > 3 mL/kg per min within 5 h after vasopressin administration, but systolic blood pressure increased to > 120% of the level at the time of vasopressin administration. All remaining patients were classified into group 4 (n = 3). Plasma vasopressin concentration were low considering the markedly hypotensive state in all six instances. Plasma vasopressin concentration during vasopressin administration were significantly increased compared with before administration (P < 0.05). No apparent side-effects were observed in this series. Conclusion:,Vasopressin deficiency may occur in catecholamine-resistant hypotension of pediatric patients due to various causes including central nervous system disturbance, drug induced hypotension and sepsis. Small doses of vasopressin administration seems to be very effective in such conditions by increasing blood pressure and urinary output. [source] High pressure Raman study of carotene-encapsulating single-wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2009J. Arvanitidis Abstract The pressure response of carotene-encapsulating single-wall carbon nanotubes is investigated by means of Raman spectroscopy. The pressure evolution of the tangential G band frequencies of the carbon nanotubes is linear without any specific features. On the other hand, the pressure response of the carotene's ,1 mode frequency is quite distinct, having a smaller low pressure slope than that reported in the literature for the molecule. This behaviour is compatible with the pressure screening effect in the interior of carbon nanotubes. For pressure higher than 2 GPa, the pressure slope becomes even smaller, an effect which can be attributed to the theoretically predicted cross-section deformation of the encapsulating tubes. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High pressure studies of the radial breathing modes in double-wall carbon nanotubesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 1 2007J. Arvanitidis Abstract This work focuses on the high pressure Raman study of the radial breathing modes (RBMs) of bundled double-wall carbon nanotubes (DWCNTs) using different excitation energies. The detailed examination of the Raman peaks attributed to the RBMs of the inner and outer tubes comprising the DWCNTs as a function of pressure provides a wealth of information concerning the pressure response of individual nanotubes as well as the inner-outer tube (intratube) interactions. The outer tube acts as a protection shield for the inner tube whereas the latter increase the structural stability of the externals upon pressure application. More importantly, the pressure response of the inner tubes, expressed by the normalized pressure slopes ,i = (1/,i) (,,i /,P) vs. frequency of their RBMs, shows a remarkable grouping in quasi-linear distributions wherein ,i increases with ,. This behavior is explained by assuming that the pressure response of an internal tube is crucially dependent on the intratube spacing and thus the structural characteristics of the encapsulating tube. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comparative proteome approach to characterize the high-pressure stress response of Lactobacillus sanfranciscensis DSM 20451TPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 6 2006Sebastian Hörmann Abstract High hydrostatic pressure (HHP) exerts diverse effects on microorganisms, leading to stress response and cell death. While inactivation of microorganisms by lethal HHP is well investigated in the context of food preservation and the hygienic safety of minimal food processes, sublethal HHP stress response and its effect on adaptation and cross-protection is less understood. In this study, the HHP stress response of Lactobacillus sanfranciscensis was characterized and compared with cold, heat, salt, acid and starvation stress at the proteome level by using 2-DE so as to provide insight into general versus specific stress responses. Sixteen proteins were found to be affected by HHP and were identified by using N-terminal amino acid sequencing and MS. Only one slightly increased protein was specific to the HHP response and showed homology to a clp protease. The other proteins were influenced by most of the investigated stresses in a similar way as HHP. The highest similarity in the HHP proteome was found to be with cold- and NaCl-stressed cells, with 11,overlapping proteins. At the proteome level, L.,sanfranciscensis appears to use overlapping subsets of stress-inducible proteins rather than stereotype responses. Our data suggest that a specific pressure response does not exist in this bacteria. [source] Steady-state field-scale gas permeability estimation and pore-gas velocity calculation in a domain open to the atmosphereREMEDIATION, Issue 4 2000Dominic C. Digiulio Field-scale estimation of gas permeability and subsequent computation of pore-gas velocity profiles are critical elements of sound soil venting design. It has been our experience, however, in U.S. Environmental Protection Agency's (EPA's) technical assistance program, provided by the Office of Research and Development in support EPA regional offices, that many venting practitioners are unaware of equations and data interpretation methods appropriate for gas permeability estimation and pore-gas velocity computation. To ameliorate this situation, we use data collected at a U.S. Coast Guard Station in Traverse City, Michigan, to demonstrate gets permeability estimation and pore-gas velocity calculation for steady-state, axisymmetric, two-dimensional gas flow in a domain open to the atmosphere. For gas permeability estimation, we use random guesses constrained with decreasing intervals of radial and vertical permeabilityand analysis of root mean square errors to ensure attainment of a global versus local minimum. We demonstrate confidence in permeability estimation by providing plots of observed versus simulated pressure response. Finally, we illustrate how plots of pore-gas velocity as a function of distance and flow rate can be helpful in venting design. [source] ST Segment "Hump" during Exercise Testing and the Risk of Sudden Cardiac Death in Patients with Hypertrophic CardiomyopathyANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2009Andreas P. Michaelides M.D., F.A.C.C., F.E.S.C. Background: The appearance of a discrete upward deflection of the ST segment termed "the ST hump sign" (STHS) during exercise testing has been associated with resting hypertension and exaggerated blood pressure response to exercise. Objective: We investigated the prevalence and clinical significance of this sign in a population of patients with hypertrophic cardiomyopathy. Methods: Eighty-one patients with hypertrophic cardiomyopathy (HCM) who underwent cardiopulmonary exercise testing were followed in a retrospective cohort study for a mean period of 5.3 years. Results: The appearance of the STHS at the peak of exercise testing was observed in 42 patients (52%), particularly in the inferior and the lateral leads. Patients with the STHS had higher fractional shortening and maximum left ventricular wall thickness and exhibited more frequently outflow tract gradient >30 mmHg at rest. Furthermore, the presence of STHS was a strong independent predictor of the risk of sudden cardiac death (SCD), as the latter occurred in eight of the patients with this sign (8/42, 19%) and in none of the patients without it (0/39, 0%) (P < 0.001). Conclusion: The appearance of a "hump" at the ST segment during exercise testing appears to be a risk factor for SCD in patients with HCM. However, further studies are necessary to validate this finding in larger populations and to elucidate the mechanism of the appearance of the "hump." [source] Anandamide mediates hyperdynamic circulation in cirrhotic rats via CB1 and VR1 receptorsBRITISH JOURNAL OF PHARMACOLOGY, Issue 7 2006L Moezi Background and purpose: Hyperdynamic circulation and mesenteric hyperaemia are found in cirrhosis. To delineate the role of endocannabinoids in these changes, we examined the cardiovascular effects of anandamide, AM251 (CB1 antagonist), AM630 (CB2 antagonist) and capsazepine (VR1 antagonist), in a rat model of cirrhosis. Experimental approach: Cirrhosis was induced by bile duct ligation. Controls underwent sham operation. Four weeks later, diameters of mesenteric arteriole and venule (intravital microscopy), arterial pressure, cardiac output, systemic vascular resistance and superior mesenteric artery (SMA) flow were measured after anandamide, AM251 (with or without anandamide), AM630 and capsazepine administration. CB1, CB2 and VR1 receptor expression in SMA was assessed by western blot and RT-PCR. Key results: Anandamide increased mesenteric vessel diameter and flow, and cardiac output in cirrhotic rats, but did not affect controls. Anandamide induced a triphasic arterial pressure response in controls, but this pattern differed markedly in cirrhotic rats. Pre-administration of AM251 blocked the effects of anandamide. AM251 (without anandamide) increased arterial pressure and systemic vascular resistance, constricted mesenteric arterioles, decreased SMA flow and changed cardiac output in a time-dependent fashion in cirrhotic rats. Capsazepine decreased cardiac output and mesenteric arteriolar diameter and flow, and increased systemic vascular resistance in cirrhotic rats, but lacked effect in controls. Expression of CB1 and VR1 receptor proteins were increased in cirrhotic rats. AM630 did not affect any cardiovascular parameter in either group. Conclusions and implications: These data suggest that endocannabinoids contribute to hyperdynamic circulation and mesenteric hyperaemia in cirrhosis, via CB1 - and VR1-mediated mechanisms. British Journal of Pharmacology (2006) 149, 898,908. doi:10.1038/sj.bjp.0706928 [source] Non-invasive assessment of cardioregulatory autonomic functions in children with epilepsyACTA NEUROLOGICA SCANDINAVICA, Issue 6 2007H. L. El-Sayed Objectives ,, We aimed to evaluate the interictal cardiovascular autonomic functions in pediatric patients with idiopathic epilepsy, both partial and generalized. Materials and methods ,, The study included 25 patients with idiopathic epilepsy and 50 control subjects. Patients underwent five standardized clinical cardiovascular reflex autonomic tests [resting heart rate (HR), HR response to deep breathing and to Valsalva maneuver, the 30:15 ratio of HR response to standing, and blood pressure response to standing], as well as a 12 lead surface electrocardiogram. Heart rate variability (HRV) was tested via 24-h Holter monitoring and the time domain parameters (SDNN, PNN50, rMSDD) were assessed. Excretion of vanillyl mandelic acid and metanephrine was measured in 24-h urine collection. Results ,, Clinical reflex autonomic tests showed mild dysfunction in 8%, moderate dysfunction in 44% and severe dysfunction in 4% of patients. The HRV parameter, SDNN, was reduced in all age groups, while rMSDD and PNN50 were reduced only in the older age group. Metanephrine levels were significantly reduced in the patients group. Patients with uncontrolled epilepsy had a significantly higher frequency of autonomic dysfunction as assessed by clinical scoring. Conclusion ,, Cardiac autonomic dysfunction is not uncommon in pediatric patients with epilepsy. Altered cardiovascular regulation seems to be related to the epilepsy itself rather than to the characteristics of the disorder. [source] TRANSLATIONAL RESEARCH GOES BOTH WAYS: LESSONS FROM CLINICAL STUDIESCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2008John W Funder SUMMARY 1It is currently assumed that translational research goes from benchtop to bedside; that aldosterone elevates blood pressure via its effects on salt and water homeostasis; that mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) share a common immediate ancestor; and that aldosterone plays a deleterious role in essential hypertension and heart failure. 2Meta-analysis of clinical trials in essential hypertension, in which eplerenone was dose-titrated to attain diastolic blood pressure < 90 mmHg, showed no relationship between blood pressure response and electrolyte effects, as judged by change in plasma (K). 3Reexamination of sequence data, and insights from the S810L MR mutant gene causing juvenile hypertension exacerbated by pregnancy, suggest that MR were the first to branch off the primordial ancestor for MR, GR, androgen receptors (AR) and progesterone receptors (PR). 4In clinical trials of MR blockade in heart failure and essential hypertension baseline aldosterone levels are in the low to normal range and sodium status unremarkable. Under such circumstances cortisol appears to be responsible for MR activation, thus exculpating aldosterone in these conditions. 5On the basis of these clinical studies, there is need to revisit the basic biology of aldosterone and MR as translational research very clearly goes both ways. [source] Normal values of pulmonary capillary wedge pressure and the blood pressure response to the Valsalva manoeuvre in healthy elderly subjectsCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2005Jaap J. Remmen Summary The blood pressure response to the Valsalva manoeuvre is related to pulmonary capillary wedge pressure (PCWP) and can be used to diagnose heart failure. However, this has never been studied specifically in the elderly, in whom the prevalence of heart failure is highest. Furthermore, normal values of the Valsalva manoeuvre are lacking. We aimed to obtain normal values of PCWP and the blood pressure response to the Valsalva manoeuvre in elderly subjects. Therefore, 28 healthy subjects, aged 70 ± 4 years, performed Valsalva manoeuvres before and after anti-G garment inflation, which was used for temporary increase of PCWP. Before inflation, PCWP was 9·8 ± 1·9 mmHg in supine and 8·9 ± 2·1 in semi-recumbent position. From the blood pressure response, measured with Finapres, the systolic blood pressure ratio (SBPR), pulse pressure ratio (PPR), stroke volume ratio (SVR) and heart rate ratio (HRR) were calculated. In supine position, SBPR was 0·76 ± 0·11, PPR 0·51 ± 0·16, SVR 0·42 ± 0·11, and HRR 1·17 ± 0·12. Semi-recumbently, SBPR was 0·74 ± 0·10, PPR 0·46 ± 0·14, SVR 0·41 ± 0·10, and HRR 1·24 ± 0·23. After inflation of the anti-G garment, the areas under the Receiver Operator Characteristics curves of SBPR, PPR and SVR for elevated (,15 mmHg) PCWP were >0·85 in supine position. In conclusion, this is the first study to obtain normal values of the blood pressure response to the Valsalva manoeuvre and PCWP in healthy elderly subjects, which is essential for the interpretation of patient data. The Valsalva manoeuvre showed significant discriminatory power in the detection of elevated PCWP, which underscores its potential in the non-invasive diagnosis of heart failure. [source] Influence of neurohumoral blockade on heart rate and blood pressure responses to haemorrhage in isoflurane anaesthetized ratsACTA PHYSIOLOGICA, Issue 3 2000UllmanArticle first published online: 24 DEC 200 Four groups of Sprague,Dawley rats were anaesthetized with isoflurane (ISO) (1.7% end-tidal concentration) in 40% oxygen, and mechanically ventilated. The animals were bled 15 mL kg,1 b.w. from the femoral vein over 10 min, followed by an observation period of 30 min. Ten minutes before haemorrhage each group of animals was pre-treated with intravenous injection/infusion of either: isotonic saline (Group B; CON; n=7), vasopressin V1 -receptor antagonist [d(CH2)5Tyr(Me)AVP; 10 ,g kg,1] (Group C; AVP-a; n=7), the non-selective angiotensin II receptor antagonist saralasin (10 ,g kg,1 min,1) (Group D; SAR; n=7) or hexamethonium (10 mg kg,1) (Group E; HEX; n=7). A separate group of conscious animals were pre-treated with isotonic NaCl and subjected to the same haemorrhage protocol (Group A; AW; n=7). Mean arterial pressure (MAP), heart rate (HR) and blood gases were observed during the experiments. Only pre-treatment with SAR and HEX reduced MAP significantly. The pre-haemorrhage HR was only affected by HEX, which caused a reduction by 17%. The HR was significantly lower at the end of haemorrhage compared with pre-haemorrhage levels in all groups except that group treated with HEX. In that group the HR changed in the opposite direction. The ability to maintain MAP during haemorrhage, and the post-haemorrhage period, was significantly impaired in the groups treated with AVP-a, SAR or HEX compared with the group receiving NaCl. It is concluded that autonomic nervous activity is of major importance for the maintenance of MAP during isoflurane anaesthesia, whereas circulating angiotensin II and vasopressin levels contribute to a much smaller degree in this regard. General anaesthesia in combination with different degrees of neurohumoral blockade impairs the haemodynamic responses to blood loss, seen in conscious individuals. The impairment involves both the early and late phases during haemorrhage, as well as the post-bleeding recovery period. All three neurohumoral systems (autonomic nervous activity, angiotensin II and vasopressin) are of importance for regulating MAP during and after haemorrhage, although the autonomic nervous outflow appears to contribute to a larger extent. [source] Cardiovascular responses to pacifier experience and feeding in newborn infantsDEVELOPMENTAL PSYCHOBIOLOGY, Issue 1 2001Morris Cohen Abstract This study examined the effects of sucking on a pacifier immediately before feeding on cardiovascular responses to feeding. Twenty-eight bottle-feeding infants were studied at 12 to 40 hr of age. Blood pressure and heart rate measurements were made during three periods: Period 1,while infants rested in their cribs before a regularly scheduled feeding, Period 2,while being held by the feeder immediately before feeding, and Period 3,during the first 3 to 5 min of feeding. Half of the infants were given a pacifier during Period 2. Blood pressures and heart rates increased across the periods; however, increases in systolic blood pressure during feeding were reduced for the group of infants given a pacifier prior to feeding. We suggest that cardiovascular responses to feeding in infants are comprised of multiple elements. Most of the systolic blood pressure responses to feeding are elicited by sucking whereas the heart rate response is dependent on both sucking and nutrient intake. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 34,39, 2001 [source] Amiodarone or Procainamide for the Termination of Sustained Stable Ventricular Tachycardia: An Historical Multicenter ComparisonACADEMIC EMERGENCY MEDICINE, Issue 3 2010Keith A. Marill MD Abstract Objectives:, The objective was to compare the effectiveness of intravenous (IV) procainamide and amiodarone for the termination of spontaneous stable sustained ventricular tachycardia (VT). Methods:, A historical cohort study of consecutive adult patients with stable sustained VT treated with IV amiodarone or procainamide was performed at four urban hospitals. Patients were identified for enrollment by admissions for VT and treatment with the study agents in the emergency department (ED) from 1993 to 2008. The primary measured outcome was VT termination within 20 minutes of onset of study medicine infusion. A secondary effectiveness outcome was the ultimate need for electrical therapy to terminate the VT episode. Major adverse effects were tabulated, and blood pressure responses to medication infusions were compared. Results:, There were 97 infusions of amiodarone or procainamide in 90 patients with VT, but the primary outcome was unknown after 14 infusions due to administration of another antidysrhythmic during the 20-minute observation period. The rates of VT termination were 25% (13/53) and 30% (9/30) for amiodarone and procainamide, respectively. The adjusted odds of termination with procainamide compared to amiodarone was 1.2 (95% confidence interval [CI] = 0.4 to 3.9). Ultimately, 35/66 amiodarone patients (53%, 95% CI = 40 to 65%) and 13/31 procainamide patients (42%, 95% CI = 25 to 61%) required electrical therapy for VT termination. Hypotension led to cessation of medicine infusion or immediate direct current cardioversion (DCCV) in 4/66 (6%, 95% CI = 2 to 15%) and 6/31 (19%, 95% CI = 7 to 37%) patients who received amiodarone and procainamide, respectively. Conclusions:, Procainamide was not more effective than amiodarone for the termination of sustained VT, but the ability to detect a significant difference was limited by the study design and potential confounding. As used in practice, both agents were relatively ineffective and associated with clinically important proportions of patients with decreased blood pressure. ACADEMIC EMERGENCY MEDICINE 2010; 17:297,306 © 2010 by the Society for Academic Emergency Medicine [source] Heart rate and blood pressure responses to a competitive role-playing gameAGGRESSIVE BEHAVIOR, Issue 5 2001J. Ricarte Abstract The effects of the outcome of competitive encounters on physiological parameters have been studied, especially testosterone levels, but hardly on other systems that, however, present a high sensitivity to stress. This study assessed the effect of a competitive game on heart rate (HR) and blood pressure (BP) in a sample of university students. In addition, the influence of anxiety and attributions of the outcome was also explored. Only winners significantly showed a rise in HR during the competition followed by a decrease along the posttask phase in addition to more internal attributions. On the contrary, the average HR for losers during the competition was lower compared with their baseline values. No differences depending on the outcome were found in BP. The cardiovascular response as well as the subjective interpretation of the outcome suggest a more active strategy employed by winners vs. a more passive strategy of losers. Future studies should specifically investigate the importance of coping strategies for psychophysiological adaptation to contests and for the outcome reached. This would permit an advance in the understanding of the role of individual differences in the processes of stress and in associated diseases. Aggr. Behav. 27:351,359, 2001. © 2001 Wiley-Liss, Inc. [source] Chronic fatigue syndrome: assessment of increased oxidative stress and altered muscle excitability in response to incremental exerciseJOURNAL OF INTERNAL MEDICINE, Issue 3 2005Y. JAMMES Abstract. Objectives., Because the muscle response to incremental exercise is not well documented in patients suffering from chronic fatigue syndrome (CFS), we combined electrophysiological (compound-evoked muscle action potential, M wave), and biochemical (lactic acid production, oxidative stress) measurements to assess any muscle dysfunction in response to a routine cycling exercise. Design., This case,control study compared 15 CFS patients to a gender-, age- and weight-matched control group (n = 11) of healthy subjects. Interventions., All subjects performed an incre-mental cycling exercise continued until exhaustion. Main outcome measures., We measured the oxygen uptake (Vo2), heart rate (HR), systemic blood pressure, percutaneous O2 saturation (SpO2), M-wave recording from vastus lateralis, and venous blood sampling allowing measurements of pH (pHv), PO2 (PvO2), lactic acid (LA), and three markers of the oxidative stress (thiobarbituric acid-reactive substances, TBARS, reduced glutathione, GSH, and ascorbic acid, RAA). Results., Compared with control, in CFS patients (i) the slope of Vo2 versus work load relationship did not differ from control subjects and there was a tendency for an accentuated PvO2 fall at the same exercise intensity, indicating an increased oxygen uptake by the exercising muscles; (ii) the HR and blood pressure responses to exercise did not vary; (iii) the anaerobic pathways were not accentuated; (iv) the exercise-induced oxidative stress was enhanced with early changes in TBARS and RAA and enhanced maximal RAA consumption; and (v) the M-wave duration markedly increased during the recovery period. Conclusions., The response of CFS patients to incremental exercise associates a lengthened and accentuated oxidative stress together with marked alterations of the muscle membrane excitability. These two objective signs of muscle dysfunction are sufficient to explain muscle pain and postexertional malaise reported by our patients. [source] Direct Evidence for Imidazoline (I1) Receptor Modulation of Ethanol Action on Norepinephrine-Containing Neurons in the Rostral Ventrolateral Medulla in Conscious Spontaneously Hypertensive RatsALCOHOLISM, Issue 4 2007Guichu Li Background: Enhancement of the rostral ventrolateral medulla (RVLM) presympathetic (norepinephrine, NE) neuronal activity represents a neurochemical mechanism for the pressor effect of ethanol. In this study, we tested the hypothesis that ethanol action on RVLM presympathetic neurons is selectively influenced by the signaling of the local imidazoline (I1) receptor. To support a neuroanatomical and an I1 -signaling selectivity of ethanol, and to circumvent the confounding effects of anesthesia, the dose-related neurochemical and blood pressure effects of ethanol were investigated in the presence of selective pharmacological interventions that cause reduction in the activity of RVLM or nucleus tractus solitarius (NTS) NE neurons via local activation of the I1 or the ,2 -adrenergic receptor in conscious spontaneously hypertensive rats. Results: Local activation of the I1 receptor by rilmenidine (40 nmol) or by the I1/,2 receptor mixed agonist clonidine (1 nmol), and local activation of the ,2 -adrenergic receptor (,2AR) by the pure ,2AR agonist , -methylnorepinephrine (, -MNE, 10 nmol) caused reductions in RVLM NE, and blood pressure. Intra-RVLM ethanol (1, 5, or 10 ,g), microinjected at the nadir of the neurochemical and hypotensive responses, elicited dose-dependent increments in RVLM NE and blood pressure in the presence of local I1,but not ,2 -receptor activation. Only intra-NTS , -MNE, but not rilmenidine or clonidine, elicited reductions in local NE and blood pressure; ethanol failed to elicit any neurochemical or blood pressure responses in the presence of local activation of the ,2AR within the NTS. Conclusion: The findings support the neuroanatomical selectivity of ethanol, and support the hypothesis that the neurochemical (RVLM NE), and the subsequent cardiovascular, effects of ethanol are selectively modulated by I1 receptor signaling in the RVLM. [source] Immediate blood pressure-lowering effects of aerobic exercise among patients with chronic kidney diseaseNEPHROLOGY, Issue 7 2008SAMUEL A HEADLEY SUMMARY: Aim: The current study was designed to determine the effect of moderate-intensity aerobic exercise on blood pressure responses within the laboratory for 60 min post exercise and in the subsequent 24 h period in patients with chronic kidney disease. Methods: Twenty-four subjects with stages 2,4 chronic kidney disease (age = 54.5 ± 15.2 years, body mass index = 32.0 ± 5.9 kg/m2) on antihypertensive medication completed this study. In random counterbalanced order, subjects were asked to either walk for 40 min at 50,60% VO2peak (oxygen consumption) or, on a separate day, to sit quietly in the laboratory for the same length of time. Following exercise or the non-exercise period, blood pressure was taken at 10 min intervals for 60 min. Subjects then wore an ambulatory blood pressure monitor for the next 24 h. Results: Systolic blood pressure (mmHg) was reduced by 6.5 ± 10.8 compared with the pre-exercise baseline value (130.3 ± 21.1) in the laboratory after exercise and this was greater than after the control period (0.73 ± 10.3, P < 0.05). Diastolic blood pressure (mmHg) was reduced following exercise (2.5 ± 6.4) compared with the control period (2.1 ± 4.9, P < 0.05). The mean 24 h readings did not differ between exercise or non-exercise days. Conclusion: Acute aerobic exercise leads to reduced blood pressure for at least 60 min within the laboratory in chronic kidney disease patients. [source] Stability of individual differences in cellular immune responses to two different laboratory tasksPSYCHOPHYSIOLOGY, Issue 6 2002Anna L. Marsland To explore the stability of immune reactivity across laboratory tasks, we correlated enumerative and functional lymphocyte responses to a speech task and a mental arithmetic task, delivered on the same occasion of testing in 31 healthy undergraduates. Both tasks were associated with an increase in peripheral CD8+ and CD56+ cell populations, and a decrease in proliferative response to phytohemagglutinin (PHA) and ratio of CD4:CD8 cells. Intertask correlations were significant for the magnitude of change in proliferative responses at two different concentrations of PHA, r= 0.76, p < .0001 and r= 0.46, p < .05, and in numbers of circulating CD56+ cells, r= 0.46, p < .005. Concomitant heart rate and systolic blood pressure responses also correlated significantly over the two experimental tasks (heart rate: r= 0.52 and systolic blood pressure: r= 0.58. ps < .0005). These data provide initial evidence that interindividual variability of some cellular immune responses is moderately reproducible across different stimulus conditions, providing further evidence that it may denote a stable individual difference. [source] | ||||||||||||||||||||||||||||||||||