Search results for "circulatory and respiratory physiology"
showing 10 items of 329 documents
Diminished Inhibition of Adhesion Molecule Expression in Prostacyclin Receptor Desensitized Human Platelets
1995
Long-term exposure of platelets to prostacyclin or iloprost (100nM, 3hr) results in receptor desensitization measured as decrease in 3H-iloprost binding sites by 47 +/- 14%. Desensitized platelets respond with an increased adhesion to endothelial cells. The mechanism of increased adhesiveness was studied by measuring the expression of the adhesion molecule CD62p (p-selectin; GMP140) on washed human platelets by flowcytometry. In thrombin stimulated platelets CD62p expression was dose-dependently reduced by iloprost. In receptor desensitized platelets IC50 for iloprost inhibition of thrombin-induced CD62p expression increased from 0.48 +/- 0.10 to 2.4 +/- 0.7 nM.
Heart failure with preserved ejection fraction infrequently evolves toward a reduced phenotype in long-term survivors: a long-term prospective longit…
2019
Background: Long-term trajectories of left ventricular ejection fraction (LVEF) in heart failure (HF) patients with preserved EF (HFpEF) remain unclear. Our objective was to assess long-term longitudinal trajectories in consecutive HFpEF patients and the prognostic impact of LVEF dynamic changes over time. Methods and Results: Consecutive ambulatory HFpEF patients admitted to a multidisciplinary HF Unit were prospectively evaluated by 2-dimensional echocardiography at baseline and at 1, 3, 5, 7, 9, and 11 years of follow-up. Exclusion criteria were patients having a previous known LVEF <50%, patients undergoing only 1 echocardiogram study, and those with a diagnosis of dilated, noncompa…
Fibrosis markers and CRIM1 increase in chronic heart failure of increasing severity.
2014
AbstractBackground: Fibrosis suppressors/activators in chronic heart failure (CHF) is a topic of investigation.Aim: To quantify serum levels of fibrosis regulators in CHF.Methods: ELISA tests were used to quantify fibrosis regulators, procollagen type-(PIP)I, (PIP)III, collagen-I, III, BMP1,2,3,7, SDF1α, CXCR4, fibulin 1,2,3, BMPER, CRIM1 and BAMBI in 66 CHF (NYHA class I, n = 9; II, n = 34; III n = 23), and in 14 controls.Results: In CHF, TGFβR2, PIPIII, SDF1α and CRIM1 were increased. PIPIII correlated with CRIM1.Conclusions: The BMPs inhibitor CRIM1 is increased and correlates with higher levels of serum PIPIII showing an imbalance in favor of pro-fibrotic mechanisms in CHF.
Tetrodotoxin slightly shortens action potential duration in ventricular but not in atrial heart muscle.
1988
Tetrodotoxin (TTX), at concentrations significantly decreasing maximal upstroke velocity (dV/dtmax) of the action potential, exerted variable effects on action potential duration (APD) in different myocardial preparations. APD was virtually unchanged by tetrodotoxin in the guinea pig atrium, but slightly shortened in the guinea pig ventricle at maximally effective concentrations. In the human ventricle, both dV/dtmax and APD were reduced in the same concentration range of TTX. These results suggest that a TTX-sensitive sodium current significantly contributes to the repolarization phase of the action potential in ventricular but not in atrial heart muscle.
Quantification of myocardial blood flow and blood flow reserve in the presence of arterial dispersion: A simulation study
2002
Myocardial blood flow (MBF) can be quantified using dynamic T1-weighted MRI of diffusible tracers and a mathematical model of underlying vasculature. Quantification of MBF by means of T1- weighted MRI requires knowledge of the arterial input function (AIF). The AIF can be estimated from the left ventricular (LV) cavity. However, dispersion may occur between the LV and the tissue of interest because of the laminar blood flow profiles, branching of venules, and because of stenosis. To evaluate the influence of dispersion on the results of MBF quantification, a simulation study was performed. The dispersion was described as a convolution of the AIF with an exponential residue function. Synthet…
Developmental activation and segment-specific co-expression of kininogen and bradykinin (BK) B2-receptors during rat nephrogenesis. • 2143
1996
Developmental activation and segment-specific co-expression of kininogen and bradykinin (BK) B 2 -receptors during rat nephrogenesis. • 2143
Mathematical simulation of Doppler changes in late-onset smallness; progression patterns of cerebral and umbilical anomalies define two types of late…
2019
To evaluate the progression of Doppler abnormalities in fetuses with late-onset fetal smallness (SGA) that become growth restricted (FGR).524 Doppler examinations of the umbilical and cerebral arteries systems, belonging to 442 late-onset SGA fetuses after week 34, were studied, evaluating by means of the statistical difference with the respective abnormal centiles, the pattern of progression into abnormal Doppler values and the distribution and cumulative sum of Doppler anomalies according to the interval to delivery.Only one third (33.5%,Two thirds of late-onset fetal smallness occurs without hemodynamic changes. In half of the remaining cases an initial cerebral vasodilation defines a gr…
Magnetic Resonance Assessment of Left Ventricular Ejection Fraction at Any Time Post-Infarction for Prediction of Subsequent Events in a Large Multic…
2021
Background Magnetic resonance imaging (MRI) is the most accurate imaging technique for left ventricular ejection fraction (LVEF) quantification, but as yet the prognostic value of LVEF assessment at any time after ST-segment elevation myocardial infarction (STEMI) for subsequent major adverse cardiac event (MACE) prediction is uncertain. Purpose To explore the prognostic impact of MRI-derived LVEF at any time post-STEMI to predict subsequent MACE (cardiovascular death or re-admission for acute heart failure). Study Type Prospective. Population One thousand thirteen STEMI patients were included in a multicenter registry. Field Strength/Sequence 1.5-T. Balanced steady-state free precession (c…
Quantitative myocardial perfusion magnetic resonance imaging: the impact of pulsatile flow on contrast agent bolus dispersion.
2011
Myocardial blood flow (MBF) can be quantified using T1-weighted first-pass magnetic resonance imaging (MRI) in combination with a tracer-kinetic model, like MMID4. This procedure requires the knowledge of an arterial input function which is usually estimated from the left ventricle (LV). Dispersion of the contrast agent bolus may occur between the LV and the tissue of interest. The aim of this study was to investigate the dispersion under conditions of physiological pulsatile blood flow, and to simulate its effect on MBF quantification. The dispersion was simulated in coronary arteries using a computational fluid dynamics (CFD) approach. Simulations were accomplished on straight vessels wit…
Expression and cellular localization of kininogens in the human kidney
1996
Expression and cellular localization of kininogens in the human kidney. Human high (H) and low (L) molecular weight kininogens are encoded by distinct mRNAs derived by alternative splicing from a single kininogen gene. Previous studies have demonstrated the presence of L-kininogen but not of H-kininogen in the distal nephron structures of the kidney. Using the highly sensitive reverse trancriptase-polymerase chain reaction (RT-PCR) we have been able to demonstrate the expression of both H-kininogen mRNA and L-kininogen mRNA in kidney and liver. The presence of H- and L-kininogen antigen was shown immunohistochemically by applying specific antibodies that discriminate between the two types o…