SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Vein

282

We explore whether the number of null results in large National Heart Lung, and Blood Institute (NHLBI) funded trials has increased over time.

Concepts: Null result, Clinical trial, Pulmonary artery, ClinicalTrials.gov, Effectiveness, Vein, Avicenna, Heart

198

Slow deep breathing improves blood oxygenation (Sp(O2)) and affects hemodynamics in hypoxic patients. We investigated the ventilatory and hemodynamic effects of slow deep breathing in normal subjects at high altitude. We collected data in healthy lowlanders staying either at 4559 m for 2-3 days (Study A; N = 39) or at 5400 m for 12-16 days (Study B; N = 28). Study variables, including Sp(O2) and systemic and pulmonary arterial pressure, were assessed before, during and after 15 minutes of breathing at 6 breaths/min. At the end of slow breathing, an increase in Sp(O2) (Study A: from 80.2±7.7% to 89.5±8.2%; Study B: from 81.0±4.2% to 88.6±4.5; both p<0.001) and significant reductions in systemic and pulmonary arterial pressure occurred. This was associated with increased tidal volume and no changes in minute ventilation or pulmonary CO diffusion. Slow deep breathing improves ventilation efficiency for oxygen as shown by blood oxygenation increase, and it reduces systemic and pulmonary blood pressure at high altitude but does not change pulmonary gas diffusion.

Concepts: Pulse oximetry, Oxygen, Blood pressure, Respiratory physiology, Heart, Blood, Artery, Vein

182

During embryonic development, vascular networks remodel to meet the increasing demand of growing tissues for oxygen and nutrients. This is achieved by the pruning of redundant blood vessel segments, which then allows more efficient blood flow patterns. Because of the lack of an in vivo system suitable for high-resolution live imaging, the dynamics of the pruning process have not been described in detail. Here, we present the subintestinal vein (SIV) plexus of the zebrafish embryo as a novel model to study pruning at the cellular level. We show that blood vessel regression is a coordinated process of cell rearrangements involving lumen collapse and cell-cell contact resolution. Interestingly, the cellular rearrangements during pruning resemble endothelial cell behavior during vessel fusion in a reversed order. In pruning segments, endothelial cells first migrate toward opposing sides where they join the parental vascular branches, thus remodeling the multicellular segment into a unicellular connection. Often, the lumen is maintained throughout this process, and transient unicellular tubes form through cell self-fusion. In a second step, the unicellular connection is resolved unilaterally, and the pruning cell rejoins the opposing branch. Thus, we show for the first time that various cellular activities are coordinated to achieve blood vessel pruning and define two different morphogenetic pathways, which are selected by the flow environment.

Concepts: Tissues, Inflammation, Atherosclerosis, Vein, Capillary, Endothelium, Heart, Blood vessel

178

Particulate air pollution has been associated with increased risk of cardiopulmonary diseases. However, the underlying mechanisms are not fully understood. We have previously demonstrated that single dose exposure to diesel exhaust particle (DEP) causes lung inflammation and peripheral thrombotic events. Here, we exposed mice with repeated doses of DEP (15 µg/animal) every 2(nd) day for 6 days (a total of 4 exposures), and measured several cardiopulmonary endpoints 48 h after the end of the treatments. Moreover, the potential protective effect of curcumin (the yellow pigment isolated from turmeric) on DEP-induced cardiopulmonary toxicity was assessed. DEP exposure increased macrophage and neutrophil numbers, tumor necrosis factor α (TNF α) in the bronchoalveolar lavage (BAL) fluid, and enhanced airway resistance to methacoline measured invasively using Flexivent. DEP also significantly increased plasma C-reactive protein (CRP) and TNF α concentrations, systolic blood pressure (SBP) as well as the pial arteriolar thrombosis. It also significantly enhanced the plasma D-dimer and plasminogen activator inhibitor-1 (PAI-1). Pretreatment with curcumin by oral gavage (45 mg/kg) 1 h before exposure to DEP significantly prevented the influx of inflammatory cells and the increase of TNF α in BAL, and the increased airway resistance caused by DEP. Likewise, curcumin prevented the increase of SBP, CRP, TNF α, D-dimer and PAI-1. The thrombosis was partially but significantly mitigated. In conclusion, repeated exposure to DEP induced lung and systemic inflammation characterized by TNFα release, increased SBP, and accelerated coagulation. Our findings indicate that curcumin is a potent anti-inflammatory agent that prevents the release of TNFα and protects against the pulmonary and cardiovascular effects of DEP.

Concepts: Heart, Air pollution, C-reactive protein, Vein, Anti-inflammatory, Blood, Tumor necrosis factor-alpha, Inflammation

169

Effective treatment of venous thromboembolism (VTE) strikes a balance between prevention of recurrence and bleeding complications. The current standard of care is heparin followed by a vitamin K antagonist such as warfarin. However, this option is not without its limitations, as the anticoagulant effect of warfarin is associated with high inter- and intra-patient variability and patients must be regularly monitored to ensure that anticoagulation is within the narrow target therapeutic range. Several novel oral anticoagulant agents are in the advanced stages of development for VTE treatment, some of which are given after an initial period of heparin treatment, in line with current practice, while others switch from high to low doses after the initial phase of treatment. In this review we assess the critical considerations for treating VTE in light of emerging clinical data for new oral agents and discuss the merits of novel treatment regimens for patients who have experienced an episode of deep vein thrombosis or pulmonary embolism.

Concepts: Deep vein thrombosis, Low molecular weight heparin, Stroke, Vein, Pulmonary embolism, Thrombosis, Warfarin, Anticoagulant

167

To synthesise current evidence for the effects of exenatide and liraglutide on heart rate, blood pressure and body weight.

Concepts: Ventricle, Vein, Evidence-based medicine, Pulse, Blood, Artery, Meta-analysis, Systematic review

167

Abstract Objective. We studied the relationship between systolic blood pressure and hemodynamics using impedance cardiography in elderly Han residents in order to evaluate how different hemodynamic variables are altered with normal aging and with hypertension superimposed on aging. Methods. A total of 670 subjects, aged 60-93 years, were evaluated with impedance cardiography for non-invasive hemodynamic variables. The subjects were categorized as hypertensives or normotensives, and then they were also divided into six subgroups according to actual systolic blood pressure values. Results. Hypertensive patients had significantly lower values of cardiac output (4.4 ± 1.5 L/min) and cardiac index (2.6 ± 1.0 L/min/m(2)) than those in the normotensive group (4.7 ± 1.5 L/min, and 2.8 ± 0.8 L/min/m(2), respectively; P < 0.05 for both). Compared to the normotensive group, stroke volume and stroke index values were also lower and systemic vascular resistance and systemic vascular resistance index were higher in the hypertensive group. There were no significant differences in left ventricular stroke work and left ventricular stroke work index between the two groups. When all 670 subjects were stratified to actual blood pressure, cardiac output of group 6 patients (systolic blood pressure ≥180 mmHg) was 19% lower than that of group 1 subjects (SBP <140 mmHg; P < 0.05). Similarly, systemic vascular resistance of group 6 patients was 56% higher than that of group 1 subjects (P < 0.05). Conclusion. With aging, arterial systolic blood pressure is elevated as a result of increased arterial stiffness and increased systemic vascular resistance. With hypertension, these values are further elevated. Non-invasive impedance cardiography helps to characterize the hemodynamic mechanisms, which can improve hypertension management.

Concepts: Total peripheral resistance, Vein, Myocardial infarction, Hypertension, Blood, Cardiology, Artery, Blood pressure

166

To evaluate the safety and feasibility of percutaneous transsplenic portal vein catheterization (PTSPC) by retrospective review of its use in patients with portal vein (PV) occlusion.

Concepts: Computer program, Hepatic portal vein, Vein, Portal venous system

165

Paradoxical embolism (PDE) occurs after embolic material passes from the venous to the arterial circulation through a right-to-left shunt, which is frequently a patent foramen ovale (PFO). We describe the case of a patient with deep venous thrombosis and an intracardiac thrombus straddling a PFO and who was successfully treated with an emergency surgery.

Concepts: Pulmonary embolism, Foramen ovale, Atrial septal defect, Embolism, Blood vessel, Hematology, Vein, Stroke

164

Arterial spin labeling (ASL) techniques are gaining popularity for visualizing and quantifying cerebral blood flow (CBF) in a range of patient groups. However, most ASL methods lack vessel-selective information, which is important for the assessment of collateral flow and the arterial supply to lesions. In this study, we explored the use of vessel-encoded pseudocontinuous ASL (VEPCASL) with multiple postlabeling delays to obtain individual quantitative CBF and bolus arrival time maps for each of the four main brain-feeding arteries and compared the results against those obtained with conventional pseudocontinuous ASL (PCASL) using matched scan time. Simulations showed that PCASL systematically underestimated CBF by up to 37% in voxels supplied by two arteries, whereas VEPCASL maintained CBF accuracy since each vascular component is treated separately. Experimental results in healthy volunteers showed that there is no systematic bias in the CBF estimates produced by VEPCASL and that the signal-to-noise ratio of the two techniques is comparable. Although more complex acquisition and image processing is required and the potential for motion sensitivity is increased, VEPCASL provides comparable data to PCASL but with the added benefit of vessel-selective information. This could lead to more accurate CBF estimates in patients with a significant collateral flow.Journal of Cerebral Blood Flow & Metabolism advance online publication, 7 August 2013; doi:10.1038/jcbfm.2013.129.

Concepts: Hematology, Measurement, Blood vessel, Vein, Myocardial infarction, Heart, Blood, Artery