The cerebrovasculature is more efficient at compensating for pharmacologically induced transient hypertension versus transient hypotension. Whether this phenomenon exists during nonpharmacologically ...induced hypertension and hypotension is currently unknown. We compared the percent change in mean velocity in the middle cerebral artery (MCAvmean) per percent change in mean arterial pressure (MAP) (%ΔMCAVmean/%ΔMAP) during transient hypertension and hypotension induced during squat-stand maneuvers performed at 0.05 Hz (20-s cycles) and 0.10 Hz (10-s cycles) in 58 male volunteers. %ΔMCAvmean/%ΔMAP was attenuated by 25% (
= 0.03, 0.05 Hz) and 47% (
< 0.0001, 0.10 Hz) during transient hypertension versus hypotension. Thus, these findings indicate that the brain in healthy men is better adapted to compensate for physiologically relevant transient hypertension than hypotension.
The novel finding of this study is that the change in middle cerebral artery mean flow velocity is attenuated during hypertension compared with hypotension physiologically induced by oscillations in blood pressure in men. These results support that the human brain is more effective at compensating for transient hypertension than hypotension.
Significance The shaping of tissues and organs relies on the ability of cells to adhere together and deform in a coordinated manner. It is, therefore, key to understand how cell-generated forces ...produce cell shape changes and how such forces transmit through a group of adhesive cells in vivo. In this context, we have developed an approach using laser manipulation to impose local forces on cell contacts in the early Drosophila embryo. Quantification of local and global shape changes using our approach can both provide direct measurements of the forces acting at cell contacts and delineate the time-dependent viscoelastic properties of the tissue. The latter provides an explicit relationship, the so-called constitutive law, between forces and deformations.
Cell-generated forces produce a variety of tissue movements and tissue shape changes. The cytoskeletal elements that underlie these dynamics act at cell–cell and cell–ECM contacts to apply local forces on adhesive structures. In epithelia, force imbalance at cell contacts induces cell shape changes, such as apical constriction or polarized junction remodeling, driving tissue morphogenesis. The dynamics of these processes are well-characterized; however, the mechanical basis of cell shape changes is largely unknown because of a lack of mechanical measurements in vivo. We have developed an approach combining optical tweezers with light-sheet microscopy to probe the mechanical properties of epithelial cell junctions in the early Drosophila embryo. We show that optical trapping can efficiently deform cell–cell interfaces and measure tension at cell junctions, which is on the order of 100 pN. We show that tension at cell junctions equilibrates over a few seconds, a short timescale compared with the contractile events that drive morphogenetic movements. We also show that tension increases along cell interfaces during early tissue morphogenesis and becomes anisotropic as cells intercalate during germ-band extension. By performing pull-and-release experiments, we identify time-dependent properties of junctional mechanics consistent with a simple viscoelastic model. Integrating this constitutive law into a tissue-scale model, we predict quantitatively how local deformations propagate throughout the tissue.
Type 2 diabetes (T2D) induces hyperglycemia, alters hemoglobin (Hb), red blood cell (RBC) deformability and impairs hemorheology. The question remains whether RBC breakdown and intravascular ...hemolysis (IVH) occur in T2D patients. We characterized RBC-degradation products and vesiculation in a case-control study of 109 T2D patients and 65 control subjects. We quantified heme-related absorbance by spectrophotometry and circulating extracellular vesicles (EV) by flow cytometry and electron microscopy. Heme-related absorbance was increased in T2D vs. control plasma (+57%) and further elevated in obese T2D plasma (+27%). However, large CD235a+ EV were not increased in T2D plasma. EV from T2D plasma, or shed by isolated T2D RBC, were notably smaller in diameter (-27%) and carried heme-related absorbance. In T2D plasma, higher heme-related absorbance (+30%) was associated to peripheral sensory neuropathy, and no other vascular complication. In vitro, T2D RBC-derived EV triggered endothelial stress and thrombin activation in a phosphatidylserine- and heme-dependent fashion. We concluded that T2D was associated with low-grade IVH. Plasma absorbance may constitute a novel biomarker of peripheral neuropathy in T2D, while flow cytometry focusing on large EV may be maladapted to characterize RBC EV in T2D. Moreover, therapeutics limiting IVH or neutralizing RBC breakdown products might bolster vasculoprotection in T2D.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
Sickle cell anaemia (SCA) is a monogenic disease with a highly variable clinical course. We aimed to investigate associations between microvascular function, haemolysis markers, blood ...viscosity and various types of SCA‐related organ damage in a multicentric sub‐Saharan African cohort of patients with SCA. In a cross‐sectional study, we selected seven groups of adult patients with SS phenotype in Dakar and Bamako based on the following complications: leg ulcer, priapism, osteonecrosis, retinopathy, high tricuspid regurgitant jet velocity (TRV), macro‐albuminuria or none. Clinical assessment, echocardiography, peripheral arterial tonometry, laboratory tests and blood viscosity measurement were performed. We explored statistical associations between the biological parameters and the six studied complications. Among 235 patients, 58 had high TRV, 46 osteonecrosis, 43 priapism, 33 leg ulcers, 31 retinopathy and 22 macroalbuminuria, whereas 36 had none of these complications. Multiple correspondence analysis revealed no cluster of complications. Lactate dehydrogenase levels were associated with high TRV, and blood viscosity was associated with retinopathy and the absence of macroalbuminuria. Despite extensive phenotyping of patients, no specific pattern of SCA‐related complications was identified. New biomarkers are needed to predict SCA clinical expression to adapt patient management, especially in Africa, where healthcare resources are scarce.
High-intensity interval training (HIIT) improves physical performance of endurance athletes, although studies examining its cardiovascular effects are sparse. We evaluated the impact of HIIT on blood ...pressure, heart rate, and cardiac cavities' size and function in endurance-trained adults. Seventeen endurance-trained men underwent 24-h ambulatory blood pressure monitoring and Doppler echocardiography at baseline and after 6 wk of HIIT. Participants were divided into 2 groups 85% maximal aerobic power (HIIT
),
= 8 and 115% maximal aerobic power (HIIT
),
= 9 to compare the impact of different HIIT intensities. Ambulatory blood pressure monitoring and cardiac chambers' size and function were similar between groups at baseline. HIIT reduced heart rate (55 ± 8 vs. 51 ± 7 beats/min;
= 0.003), systolic blood pressure (121 ± 11 vs. 118 ± 9 mmHg;
= 0.01), mean arterial pressure (90 ± 8 vs. 89 ± 6 mmHg;
= 0.03), and pulse pressure (52 ± 6 vs. 49 ± 5 mmHg;
= 0.01) irrespective of training intensity. Left atrium volumes increased after HIIT (maximal: 50 ± 14 vs. 54 ± 14 mL;
= 0.02; minimal: 15 ± 5 vs. 20 ± 8 mL;
= 0.01) in both groups. Right ventricle global longitudinal strain lowered after training in the HIIT
group only (20 ± 4 vs. 17 ± 3%,
= 0.04). In endurance-trained men, 6 wk of HIIT reduced systolic blood pressure and mean arterial pressure and increased left atrium volumes irrespective of training intensity, whereas submaximal HIIT deteriorated right ventricle systolic function.
The novel findings of this study are that 6 wk of high-intensity interval training increases left atrial volumes irrespective of training intensity (85 or 115% maximal aerobic power), whereas the submaximal training decreases right ventricular systolic function in endurance-trained men. These results may help identify the exercise threshold for potential toxicity of intense exercise training for at-risk individuals and ideal exercise training regimens conferring optimal cardiovascular protection and adapted endurance training for athletes.
In hemolytic diseases, such as sickle cell disease (SCD), intravascular hemolysis results in the release of hemoglobin, heme, and heme-loaded membrane microvesicles in the bloodstream. Intravascular ...hemolysis is thus associated with inflammation and organ injury. Complement system can be activated by heme in vitro. We investigated the mechanisms by which hemolysis and red blood cell (RBC) degradation products trigger complement activation in vivo. In kidney biopsies of SCD nephropathy patients and a mouse model with SCD, we detected tissue deposits of complement C3 and C5b-9. Moreover, drug-induced intravascular hemolysis or injection of heme or hemoglobin in mice triggered C3 deposition, primarily in kidneys. Renal injury markers (Kim-1, NGAL) were attenuated in C3-/- hemolytic mice. RBC degradation products, such as heme-loaded microvesicles and heme, induced alternative and terminal complement pathway activation in sera and on endothelial surfaces, in contrast to hemoglobin. Heme triggered rapid P selectin, C3aR, and C5aR expression and downregulated CD46 on endothelial cells. Importantly, complement deposition was attenuated in vivo and in vitro by heme scavenger hemopexin. In conclusion, we demonstrate that intravascular hemolysis triggers complement activation in vivo, encouraging further studies on its role in SCD nephropathy. Conversely, heme inhibition using hemopexin may provide a novel therapeutic opportunity to limit complement activation in hemolytic diseases.
Natural Capital Accounting (NCA) is becoming a reference tool for an increasing number of organizations transitioning towards environmental impact neutrality. However, one NCA technique applicable to ...all types of actors (individual, community, company, etc.) is missing because of the lack of consensus on how to quantify both their environmental impacts and dependencies on ecosystems. A coupled systematic and non-systematic review of the grey and scientific literature is performed here to (i) make an extensive review of state-of-the-art NCA methods, identifying their current utilization and limitations, and (ii) discern prospects about the challenges of integrating an Ecosystem Service Accounting in Life Cycle Assessment (ESA-LCA). While NCA methods can extensively evaluate the supply of ES, they tend to disregard the quantification of environmental impacts that imply a demand for ES. The ESA-LCA approach is identified as a robust solution to balance supply and demand of ecosystem services in NCA, allowing private and public actors to quantify their distance from impact neutrality targets. A novel definition of NC(A) in LCA is also formulated to support these future efforts, promoting a Mitigation Hierarchy-based strategy to avoid, minimize, restore, and offset impacts, and outlining a roadmap for practitioners to apply ESA-LCA across multiple economic sectors.
Intravascular erythrocyte destruction, accompanied by the release of pro-oxidative and pro-inflammatory components hemoglobin and heme, is a common event in the pathogenesis of numerous diseases with ...heterogeneous etiology and clinical features. A frequent adverse effect related to massive hemolysis is the renal injury and inflammation. Nevertheless, it is still unclear whether heme--a danger-associated molecular pattern--and ligand for TLR4 or upstream hemolysis-derived products are responsible for these effects. Well-characterized animal models of hemolysis with kidney impairment are needed to investigate how hemolysis drives kidney injury and to test novel therapeutic strategies. Here, we characterized the pathological processes leading to acute kidney injury and inflammation during massive intravascular hemolysis, using a mouse model of phenylhydrazine (PHZ)-triggered erythrocyte destruction. We observed profound changes in mRNA levels for markers of tubular damage (Kim-1, NGAL) and regeneration (indirect marker of tubular injury, Ki-67), and tissue and vascular inflammation (IL-6, E-selectin, P-selectin, ICAM-1) in kidneys of PHZ-treated mice, associated with ultrastructural signs of tubular injury. Moreover, mass spectrometry revealed presence of markers of tubular damage in urine, including meprin-α, cytoskeletal keratins, α-1-antitrypsin, and α-1-microglobulin. Signs of renal injury and inflammation rapidly resolved and the renal function was preserved, despite major changes in metabolic parameters of PHZ-injected animals. Mechanistically, renal alterations were largely heme-independent, since injection of free heme could not reproduce them, and scavenging heme with hemopexin in PHZ-administered mice could not prevent them. Reduced overall health status of the mice suggested multiorgan involvement. We detected amylasemia and amylasuria, two markers of acute pancreatitis. We also provide detailed characterization of renal manifestations associated with acute intravascular hemolysis, which may be mediated by hemolysis-derived products upstream of heme release. This analysis provides a platform for further investigations of hemolytic diseases and associated renal injury and the evaluation of novel therapeutic strategies that target intravascular hemolysis.
Patients with sickle cell disease suffer from painful crises associated with disseminated vaso-occlusions, increased circulating erythrocyte microparticles (MPs), and thrombospondin-1 (TSP1). MPs are ...submicron membrane vesicles shed by compromised or activated cells. We hypothesized that TSP1 mediates MP shedding and participates in vaso-occlusions. We injected TSP1 to transgenic SAD mice with sickle cell disease and characterized circulating phosphatidylserine+ MPs by FACS. TSP1 stimulated MPs in plasma and initiated vaso-occlusions within minutes. In vitro, TSP1 triggered rapid erythrocyte conversion into spicule-covered echinocytes, followed by MP shedding. MP shedding was recapitulated by peptides derived from the TSP1 carboxyterminus. We purified MPs shed by erythrocytes in vitro and administered them back to SAD mice. MPs triggered immediate renal vaso-occlusions. In vitro, MPs triggered the production of radical oxygen species by endothelial monolayers, favored erythrocyte adhesion, and induced endothelial apoptosis. MPs also compromised vasodilation in perfused microvessels. These effects were inhibited by saturating MP phosphatidylserine with annexin-V, or with inhibitors of endothelial ROS production. We conclude that TSP1 triggers erythrocyte MP shedding. These MPs induce endothelial injury and facilitate acute vaso-occlusive events in transgenic SAD mice. This work supports a novel concept that toxic erythrocyte MPs may connect sickle cell anemia to vascular disease.
Despite an increasing number of smartphone apps, such therapeutic tools have not yet consistently demonstrated their efficacy and many suffer from low retention rates. To ensure the development of ...efficient apps associated with high adherence, we aimed to identify, through a user-centred design approach, patient and physician expectations of a hypothetical app dedicated to depression.
We conducted semi-structured interviews with physicians (psychiatrists and general practitioners) and patients who had experienced a major depressive episode during the last 12 months using the focus group method. The interviews were audio recorded, transcribed and analysed using qualitative content analysis to define codes, categories and emergent themes.
A total of 26 physicians and 24 patients were included in the study. The focus groups showed balanced sex and age distributions. Most participants owned a smartphone (83.3% of patients, 96.1% of physicians) and were app users (79.2% of patients and 96.1% of physicians). The qualitative content analysis revealed 3 main themes: content, operating characteristics and barriers to the use of the app. Expected content included the data collected by the app, aiming to provide information about the patient, data provided by the app, gathering psychoeducation elements, therapeutic tools and functionalities to help with the management of daily life and features expected for this tool. The "operating characteristics" theme gathered aims considered for the app, its potential target users, considered modalities of use and considerations around its accessibility and security of use. Finally, barriers to the use of the app included concerns about potential app users, its accessibility, safety, side-effects, utility and functioning. All themes and categories were the same for patients and physicians.
Physician and patient expectations of a hypothetical smartphone app dedicated to depression are high and confirmed the important role it could play in depression care. The key points expected by the users for such a tool are an easy and intuitive use and a personalised content. They are also waiting for an app that gives information about depression, offers a self-monitoring functionality and helps them in case of emergency.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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