Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 159
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Microcirculation ; 2019 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-31520425

RESUMO

OBJECTIVE: In this study, we examined the impact of gap junction blockade on chick chorioallantoic membrane microvessels. METHODS: Expression of Cx37, Cx40/42, and Cx43 in chick chorioallantoic membrane tissue was studied by PCR, Western blot, and confocal immunofluorescence microscopy. Vessel diameter changes occurring under gap junction blockade with carbenoxolone (175 µmol/L), palmitoleic acid (100 µmol/L), 43 GAP27 (1 mmol/L) were analyzed by intravital microscopy. To analyze vascular tone, chick chorioallantoic membrane vessels were exposed to a vasodilator cocktail consisting of acetylcholine (10 µmol/L), adenosine (100 µmol/L), papaverine (200 µmol/L), and sodium nitroprusside (10 µmol/L). RESULTS: In chick chorioallantoic membrane lysates, Western blot analysis revealed the expression of Cx40 and Cx43. Immunofluorescence in intact chick chorioallantoic membrane vasculature showed only Cx43, limited to arterial vessel walls. Upon gap junction blockade (3 hours) arterial and venous diameters decreased to 0.50 ± 0.03 and 0.36 ± 0.06 (carbenoxolone), 0.72 ± 0.08 and 0.63 ± 0.15 (palmitoleic acid) and 0.77 ± 0.004 and 0.58 ± 0.05 (GAP27), relative to initial values. Initially, diameter decrease was dominated by increasing vascular tone. After 6 hours, however, vessel tone was reduced, suggesting structural network remodeling. CONCLUSIONS: Our findings suggest a major role for connexins in mediating acute and chronic diameter changes in developing vascular networks.

2.
Anesthesiology ; 131(3): 693-715, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31408449

RESUMO

Transfusion-related acute lung injury is a leading cause of death associated with the use of blood products. Transfusion-related acute lung injury is a diagnosis of exclusion which can be difficult to identify during surgery amid the various physiologic and pathophysiologic changes associated with the perioperative period. As anesthesiologists supervise delivery of a large portion of inpatient prescribed blood products, and since the incidence of transfusion-related acute lung injury in the perioperative patient is higher than in nonsurgical patients, anesthesiologists need to consider transfusion-related acute lung injury in the perioperative setting, identify at-risk patients, recognize early signs of transfusion-related acute lung injury, and have established strategies for its prevention and treatment.

3.
Hypertension ; 74(2): 295-304, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31291149

RESUMO

Subendocardial damage is among the first cardiac manifestations of hypertension and is already present in asymptomatic disease states. Accordingly, markers of subendocardial impairment may facilitate early detection of cardiac damages and risk stratification under these conditions. This study aimed to investigate the impact of subendocardial damage on myocardial microstructure and function to elucidate early pathophysiologic processes and to identify corresponding diagnostic measures. Mice (n=38) were injected with isoproterenol to induce isolated subendocardial scarring or saline as corresponding control. Cardiac function and myocardial deformation were determined by high-frequency echocardiography. The cardiac stress response was assessed in a graded exercise test and during dobutamine stress echocardiography. Myocardial microstructure was studied ex vivo by 7 T diffusion tensor magnetic resonance imaging at a spatial resolution of 100×100×100 µm 3 . Results were correlated with histology and biomarker expression. Subendocardial fibrosis was accompanied by diastolic dysfunction, impaired longitudinal deformation (global peak longitudinal strain [LS]: -12.5±0.5% versus -15.6±0.5%; P<0.001) and elevated biomarker expression (ANP [atrial natriuretic peptide], Galectin-3, and ST2). Systolic function and cardiac stress response remained preserved. Diffusion tensor magnetic resonance imaging revealed a left-shift in helix angle towards lower values in isoproterenol-treated animals, which was mainly determined by subepicardial myofibers (mean helix angle: 2.2±0.8° versus 5.9±1.0°; P<0.01). Longitudinal strain and subepicardial helix angle were highly predictive for subendocardial fibrosis (sensitivity, 82%-92% and specificity, 89%-90%). The results indicate that circumscribed subendocardial damage alone can cause several hallmarks observed in cardiovascular high-risk patients. Microstructural remodeling under these conditions involves also remote regions, and corresponding changes in longitudinal strain and helix angle might serve as diagnostic markers.


Assuntos
Endocárdio/patologia , Interpretação de Imagem Assistida por Computador , Isoproterenol/efeitos adversos , Imagem Cinética por Ressonância Magnética/métodos , Disfunção Ventricular Esquerda/diagnóstico por imagem , Animais , Biópsia por Agulha , Modelos Animais de Doenças , Ecocardiografia/métodos , Endocárdio/diagnóstico por imagem , Endocárdio/lesões , Fibrose/diagnóstico por imagem , Fibrose/patologia , Alemanha , Humanos , Imuno-Histoquímica , Injeções Subcutâneas , Isoproterenol/administração & dosagem , Modelos Lineares , Camundongos , Camundongos Endogâmicos , Curva ROC , Distribuição Aleatória , Valores de Referência , Volume Sistólico/fisiologia , Análise de Sobrevida , Disfunção Ventricular Esquerda/patologia
4.
Microvasc Res ; 125: 103882, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31075242

RESUMO

Fractal dimension is a robust fractal parameter for estimating the morphology of vascular networks. It reflects the property of vascular networks that may vary and thus, differentiate between individual networks and/or identify physiological and pathological conditions. As such, fractal dimension differs also between arteriolar and venular compartments, yet the underlying reason is so far unclear. In order to understand the mechanisms behind these differences, we quantitatively analyzed the impacts of vessel attributes on the fractal dimension. Fractal dimension and vessel attributes given by vessel density (VD), vessel length density (VL), and diameter index (DI=VD/VL) were analyzed in three microvascular networks of the rat mesentery, which were reconstructed from experimental data. The results show that differences in diameter between arterioles and venules are primarily responsible for arterio-venous differences in fractal dimension. Moreover, multiple linear regression analysis demonstrates that the sensitivity of the variation of fractal dimension to vessel length and diameter varies with the type of the vessels. While the change of vessel length contributes 57.8 ±â€¯3.4% to the variation of arteriolar dimension, vessel diameter contributes 63.9 ±â€¯4.8% to the variation of venular dimension. The present study provides an explanation for the different fractal dimension and dimension variation in arteriolar and venular compartments. It highlights the importance of estimating the fractal dimensions of arterioles and venules separately, which will enhance the ability of feature extraction by fractal analysis in physiological and clinical application.

5.
Cardiovasc Ultrasound ; 17(1): 7, 2019 Apr 22.
Artigo em Inglês | MEDLINE | ID: mdl-31010431

RESUMO

Echocardiography is the most commonly applied technique for non-invasive assessment of cardiac function in small animals. Manual tracing of endocardial borders is time consuming and varies with operator experience. Therefore, we aimed to evaluate a novel automated two-dimensional software algorithm (Auto2DE) for small animals and compare it to the standard use of manual 2D-echocardiographic assessment (2DE). We hypothesized that novel Auto2DE will provide rapid and robust data sets, which are in agreement with manually assessed data of animals.2DE and Auto2DE were carried out using a high-resolution imaging-system for small animals. First, validation cohorts of mouse and rat cine loops were used to compare Auto2DE against 2DE. These data were stratified for image quality by a blinded expert in small animal imaging. Second, we evaluated 2DE and Auto2DE in four mouse models and four rat models with different cardiac pathologies.Automated assessment of LV function by 2DE was faster than conventional 2DE analysis and independent of operator experience levels. The accuracy of Auto2DE-assessed data in healthy mice was dependent on cine loop quality, with excellent agreement between Auto2DE and 2DE in cine loops with adequate quality. Auto2DE allowed for valid detection of impaired cardiac function in animal models with pronounced cardiac phenotypes, but yielded poor performance in diabetic animal models independent of image quality.Auto2DE represents a novel automated analysis tool for rapid assessment of LV function, which is suitable for data acquisition in studies with good and very good echocardiographic image quality, but presents systematic problems in specific pathologies.

7.
Curr Opin Pulm Med ; 25(3): 257-262, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30893107

RESUMO

PURPOSE OF REVIEW: In this brief review, we discuss the current epidemiological data and latest results from basic research on the cardiovascular sequelae after lower respiratory tract infection. RECENT FINDINGS: Novel epidemiological evidence substantiates the association between pneumonia and subsequent cardiovascular events (CVEs) in the short- and long-term after viral or bacterial acute infection. Biomarkers such as cardiac troponin or coronary artery calcium may represent useful predictive tools for the detection of cardiac involvement during and after pneumonia. Particularly, Streptococcus pneumoniae directly cause cardiac damage by invasion into the myocardium and formation of microscopic lesions finally leading to the development of cardiac scarring in rodents and nonhuman primates. In addition, a causal relationship between pulmonary inflammation and atherosclerotic plaque formation in systemic arteries has emerged that appears to involve a mechanistic role for neutrophil granulocytes. However, many key pathomechanisms by which pneumonia may trigger or promote subsequent CVEs still remain unclear. SUMMARY: Pneumonia may deleteriously impact cardiovascular function. Direct cardiomyocyte destruction by pathogens as well as host inflammatory response associated effects including atherosclerotic plaque development and/or rupture have been observed. Details of underlying mechanisms need to be further investigated to deliver future perspectives for the prevention of CVEs subsequent to pneumonia.

8.
Am J Physiol Lung Cell Mol Physiol ; 316(6): L977-L989, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-30892076

RESUMO

Both physiological homeostasis and pathological disease processes in the lung typically result from complex, yet coordinated multicellular responses that are synchronized via paracrine and endocrine intercellular communication pathways. Of late, extracellular vesicles have emerged as important information shuttles that can coordinate and disseminate homeostatic and disease signals. In parallel, extracellular vesicles in biological fluids such as sputum, mucus, epithelial lining fluid, edema fluid, the pulmonary circulation, pleural fluid, and lymphatics have emerged as promising candidate biomarkers for diagnosis and prognosis in lung disease. Extracellular vesicles are small, subcellular, membrane-bound vesicles containing cargos from parent cells such as lipids, proteins, genetic information, or entire organelles. These cargos endow extracellular vesicles with biologically active information or functions by which they can reprogram their respective target cells. Recent studies show that extracellular vesicles found in lung-associated biological fluids play key roles as biomarkers and effectors of disease. Conversely, administration of naïve or engineered extracellular vesicles with homeostatic or reparative effects may provide a promising novel protective and regenerative strategy to treat lung disease. To highlight this rapidly developing field, the American Journal of Physiology-Lung Cellular and Molecular Physiology is now launching a special Call for Papers on extracellular vesicles in lung health, disease, and therapy. This review aims to set the stage for this call by introducing extracellular vesicles and their emerging roles in lung physiology and pathobiology.

10.
13.
Int J Cardiol ; 2018 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-30314839

RESUMO

The European guidelines, which focus on clinical aspects of pulmonary hypertension (PH), provide only minimal information about the pathophysiological concepts of PH. Here, we review this topic in greater detail, focusing on specific aspects in the pathobiology, pathology and genetics, which include mechanisms of vascular inflammation, the role of transcription factors, ion channels/ion channel diseases, hypoxic pulmonary vasoconstriction, genetics/epigenetics, metabolic dysfunction, and the potential future role of histopathology of PH in the modern era of PH therapy. In addition to new insights in the pathobiology of this disease, this working group of the Cologne Consensus Conference also highlights novel concepts and potential new therapeutic targets to further improve the treatment options in PAH.

15.
J Physiol ; 2018 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-30015354

RESUMO

The pulmonary epithelial and vascular endothelial cell layers provide two sequential physical and immunological barriers that together form a semi-permeable interface and prevent alveolar and interstitial oedema formation. In this review, we focus specifically on the continuous endothelium of the pulmonary microvascular bed that warrants strict control of the exchange of gases, fluid, solutes and circulating cells between the plasma and the interstitial space. The present review provides an overview of emerging molecular mechanisms that permit constant transcellular exchange between the vascular and interstitial compartment, and cause, prevent or reverse lung endothelial barrier failure under experimental conditions, yet with a clinical perspective. Based on recent findings and at times seemingly conflicting results we discuss emerging paradigms of permeability regulation by altered ion transport as well as shifts in the homeostasis of sphingolipids, angiopoietins and prostaglandins.

16.
Cardiovasc Ultrasound ; 16(1): 10, 2018 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-29966517

RESUMO

BACKGROUND: The assessment of ventricular volumes using conventional echocardiography methods is limited with regards to the need of geometrical assumptions. In the present study, we aimed to evaluate a novel commercial system for three-dimensional echocardiography (3DE) in preclinical models by direct comparison with conventional 1D- and 2D-echocardiography (1DE; 2DE) and the gold-standard technique magnetic resonance imaging (MRI). Further, we provide a standard operating protocol for image acquisition and analysis with 3DE. METHODS: 3DE was carried out using a 30 MHz center frequency transducer coupled to a Vevo®3100 Imaging System. We evaluated under different experimental conditions: 1) in vitro phantom measurements served as controlled setting in which boundaries were clearly delineated; 2) a validation cohort composed of healthy C57BL/6 J mice and New Zealand Obese (NZO) mice was used in order to validate 3DE against cardiac MRI; 3) a standard mouse model of pressure overload induced-heart failure was investigated to estimate the value of 3DE. RESULTS: First, in vitro volumetry revealed good agreement between 3DE assessed volumes and the MRI-assessed volumes. Second, cardiac volume determination with 3DE showed smaller mean differences compared to cardiac MRI than conventional 1DE and 2DE. Third, 3DE was suitable to detect reduced ejection fractions in heart failure mice. Fourth, inter- and intra-observer variability of 3DE showed good to excellent agreement regarding absolute volumes in healthy mice, whereas agreement rates for the relative metrics ejection fraction and stroke volume demonstrated good to moderate observer variabilities. CONCLUSIONS: 3DE provides a novel method for accurate volumetry in small animals without the need for spatial assumptions, demonstrating a technique for an improved analysis of ventricular function. Further validation work and highly standardized image analyses are required to increase reproducibility of this approach.


Assuntos
Ecocardiografia Tridimensional , Insuficiência Cardíaca/diagnóstico por imagem , Volume Sistólico , Animais , Modelos Animais de Doenças , Ecocardiografia , Interpretação de Imagem Assistida por Computador , Processamento de Imagem Assistida por Computador , Imagem por Ressonância Magnética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Variações Dependentes do Observador , Reprodutibilidade dos Testes
17.
Am J Respir Crit Care Med ; 198(9): 1165-1176, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-29902384

RESUMO

RATIONALE: Ventilator management in acute respiratory distress syndrome usually focuses on setting parameters, but events occurring at ventilator disconnection are not well understood. OBJECTIVES: To determine if abrupt deflation after sustained inflation causes lung injury. METHODS: Male Sprague-Dawley rats were ventilated (low Vt, 6 ml/kg) and randomized to control (n = 6; positive end-expiratory pressure [PEEP], 3 cm H2O; 100 min) or intervention (n = 6; PEEP, 3-11 cm H2O over 70 min; abrupt deflation to zero PEEP; ventilation for 30 min). Lung function and injury was assessed, scanning electron microscopy performed, and microvascular leak timed by Evans blue dye (n = 4/group at 0, 2, 5, 10, and 20 min after deflation). Hemodynamic assessment included systemic arterial pressure (n = 6), echocardiography (n = 4), and right (n = 6) and left ventricular pressures (n = 6). MEASUREMENTS AND MAIN RESULTS: Abrupt deflation after sustained inflation (vs. control) caused acute lung dysfunction (compliance 0.48 ± 1.0 vs. 0.82 ± 0.2 m/cm H2O, oxygen saturation as measured by pulse oximetry 67 ± 23.5 vs. 91 ± 4.4%; P < 0.05) and injury (wet/dry ratio 6.1 ± 0.6 vs. 4.6 ± 0.4; P < 0.01). Vascular leak was absent before deflation and maximal 5-10 minutes thereafter; injury was predominantly endothelial. At deflation, left ventricular preload, systemic blood pressure, and left ventricular end-diastolic pressure increased precipitously in proportion to the degree of injury. Injury caused later right ventricular failure. Sodium nitroprusside prevented the increase in systemic blood pressure and left ventricular end-diastolic pressure associated with deflation, and prevented injury. Injury did not occur with gradual deflation. CONCLUSIONS: Abrupt deflation after sustained inflation can cause acute lung injury. It seems to be mediated by acute left ventricular decompensation (caused by increased left ventricular preload and afterload) that elevates pulmonary microvascular pressure; this directly injures the endothelium and causes edema, which is potentiated by the surge in pulmonary perfusion.

18.
Curr Pharm Des ; 24(25): 2893-2899, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29938611

RESUMO

BACKGROUND: Ischemic heart disease has long been considered to be exlusively caused by stenosis or occlusion. However, the coronary microcirculation too may play an important role in ischemic conditions. Also, the crucial role of microvessels in not only regulating blood flow on a local level but also mediating vascular permeability or inflammatory responses has been recognized. OBJECTIVE: To review important physiological and pathophysiological mechanisms of coronary microcirculatory control with focus on heterogeneity of local perfusion, microvascular permeability and inflammation. METHOD: Selective research of the literature. RESULTS: Heterogeneity is a characteristic of microvascular networks and affects structural and functional parameters such as vessel diameter, length, and connection pattern, flow velocity, wall shear stress, and oxygenation. Microvascular networks are optimized to meet the metabolic demand of all tissue compartments. This requires continuous vascular adaptation regulated by local hemodynamic and metabolic stimuli. Compromising this regulation results in functional arterio-venous shunting and tissue areas with either hyperperfusion or hypoxia in close proximity. In ischemia-reperfusion, increased microvascular permeability may aggravate tissue hypoxia by increasing extravascular pressure and seems to contribute to adverse myocardial remodeling. Transendothelial transport mechanisms and deterioration of the endothelial glycocalyx seem to be major contributors to tissue edema. Also in the context of ischemia-reperfusion, an inflammatory response mediated by venular endothelium expressing specific adhesion molecules contributes to tissue injury. However, anti-inflammatory therapies failed in clinical studies and a multi-targeted approach for cardiac protection is required. CONCLUSION: Disturbances of the coronary microcirculation are involved in different pathophysiological aspects of reperfusion injury.

19.
Am J Physiol Lung Cell Mol Physiol ; 315(4): L502-L516, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29877097

RESUMO

The following review summarizes the pro-con debate about current controversies regarding the pathogenesis of pulmonary arterial hypertension (PAH) that took place at the American Thoracic Society Conference in May 2017. Leaders in the field of PAH research discussed the importance of the immune system, the role of hemodynamic stress and endothelial apoptosis, as well as bone morphogenetic protein receptor-2 signaling in PAH pathogenesis. Whereas this summary does not intend to resolve obvious conflicts in opinion, we hope that the presented arguments entice further discussions and draw a new generation of enthusiastic researchers into this vibrant field of science to bridge existing gaps for a better understanding and therapy of this fatal disease.

20.
Microcirculation ; 25(5): e12458, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29729094

RESUMO

OBJECTIVE: PWV is the speed of pulse wave propagation through the circulatory system. mPWV emerges as a novel indicator of hypertension, yet it remains unclear how different vascular properties affect mPWV. We aim to identify the biomechanical determinants of mPWV. METHODS: A 1D model was used to simulate PWV in a rat mesenteric microvascular network and, for comparison, in a human macrovascular arterial network. Sensitivity analysis was performed to assess the relationship between PWV and vascular compliance and resistance. RESULTS: The 1D model enabled adequate simulation of PWV in both micro- and macrovascular networks. Simulated arterial PWV changed as a function of vascular compliance but not resistance, in that arterial PWV varied at a rate of 0.30 m/s and -6.18 × 10-3  m/s per 10% increase in vascular compliance and resistance, respectively. In contrast, mPWV depended on both vascular compliance and resistance, as it varied at a rate of 2.79 and -2.64 cm/s per 10% increase in the respective parameters. CONCLUSIONS: The present study identifies vascular compliance and resistance in microvascular networks as critical determinants of mPWV. We anticipate that mPWV can be utilized as an effective indicator for the assessment of microvascular biomechanical properties.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA