Presence Of RBCs Research Articles

Effects of flowing red blood cells on the motion of a circulating tumour cell in the asymmetric bifurcated microvessel

ABSTRACT Asymmetric bifurcate are common in the vascular system, and circulating tumour cells (CTCs) tend to metastasize at these locations. In this study, the dissipative particle dynamics method is used to simulate the motion of a CTC in an asymmetric microvessel combined with a spring-based network model. Effects of flow rate, the presence of RBCs and haematocrit on the motion of the CTC are investigated. The results indicate that under higher flow rate, the CTC could not adhere to the microvessel and invariably migrated towards the branch exhibiting a higher flow rate. In the presence of RBCs, the initially attached CTC would disassociate from the parent vessel wall under the collisions with them, and it finally enters into the large branch. While at lower flow rates, the RBCs pass over the CTC that is rolling along the top wall of the parent vessel and overtake it, facilitating the CTC adhesion, it ultimately moves into the small branch. At a mediate flow rate, though the attached CTC detaches and enters into the large branch, it would touch the inner wall of the branch. With the haematocrit increasing up to 5.1%, the CTC retains rolling along the vessel wall and is ultimately captured in the small branch.

Crucial roles of red blood cells and platelets in whole blood thrombin generation

AbstractRed blood cells (RBCs) and platelets contribute to the coagulation capacity in bleeding and thrombotic disorders. The thrombin generation (TG) process is considered to reflect the interactions between plasma coagulation and the various blood cells. Using a new high-throughput method capturing the complete TG curve, we were able to compare TG in whole blood and autologous platelet-rich and platelet-poor plasma to redefine the blood cell contributions to the clotting process. We report a faster and initially higher generation of thrombin and shorter coagulation time in whole blood than in platelet-rich plasma upon low concentrations of coagulant triggers, including tissue factor, Russell viper venom factor X, factor Xa, factor XIa, and thrombin. The TG was accelerated with increased hematocrit and delayed after prior treatment of RBC with phosphatidylserine-blocking annexin A5. RBC treatment with ionomycin increased phosphatidylserine exposure, confirmed by flow cytometry, and increased the TG process. In reconstituted blood samples, the prior selective blockage of phosphatidylserine on RBC with annexin A5 enhanced glycoprotein VI–induced platelet procoagulant activity. For patients with anemia or erythrocytosis, cluster analysis revealed high or low whole-blood TG profiles in specific cases of anemia. The TG profiles lowered upon annexin A5 addition in the presence of RBCs and thus were determined by the extent of phosphatidylserine exposure of blood cells. Profiles for patients with polycythemia vera undergoing treatment were similar to that of control subjects. We concluded that RBC and platelets, in a phosphatidylserine-dependent way, contribute to the TG process. Determination of the whole-blood hypo- or hyper-coagulant activity may help to characterize a bleeding or thrombosis risk.

Simulation of a tumor cell flowing through a symmetric bifurcated microvessel.

Microvessel bifurcations serve as the major sites of tumor cell adhesion and further extravasation. In this study, the movement, deformation, and adhesion of a circulating tumor cell flowing in a symmetric microvessel with diverging and converging bifurcations were simulated by dissipative particle dynamics combined with a spring-based network model. Effects of the initial position of the CTC, externally-applied acceleration and the presence of RBCs on the motion of the CTC were investigated. The results demonstrated that the CTC released at the centerline of the parent vessel would attach to the vessel wall when arriving at the apex of diverging bifurcation and slide into the daughter branch determined by its centroid deflection and finally form firm adhesion at relatively lower flow rates. As the external acceleration increases, the increasing shear force enlarges the contact area for the adherent CTC on the one hand and reduces the residence time on the other hand. With the presence of RBCs in the bloodstream, the collision between the adherent tumor cell at the diverging bifurcation and flowing RBCs promotes the firm adhesion of CTC at lower flow rates.

Effect of Chitosan and Amphiphilic Polymers on the Photosensitizing and Spectral Properties of Rose Bengal.

The influence of chitosan (CS) and amphiphilic polymers (AP: pluronic F108 and polyvinylpyrrolidone (PVP)) on the photocatalytic activity of rose bengal (RB) in a model reaction of tryptophan photo-oxidation in phosphate-buffered saline (PBS) was studied. It was shown that in the presence of CS, the effective rate constant keff of tryptophan photo-oxidation catalyzed by RB in PBS solution decreases by a factor of two. This is due to the ionic interaction of the RB with the chitosan. Rose bengal in a slightly acidic environment (pH 4.5) passes into a neutral lactone form, which sharply reduces the photosensitizing properties of the dye. It was demonstrated that the introduction of AP into a solution containing RB and CS prevents direct interaction between RB and CS. This is evidenced by the presence of photocatalytic activity of the dye in the RB-AP-CS systems, as well as bathochromic shifts of the main absorption bands of the dye, and an increase in the optical density and luminescence intensity of the RB when AP is introduced into a buffer solution containing RB and chitosan. The presence of RB-CS and RB-AP interaction in aqueous and PBS media is confirmed by the increase in the degree of fluorescence anisotropy (r) of these binary systems. In an aqueous solution, the value of r for the RB-F108-CS system decreases by a factor of 3.5 (compared to the value of r for the RB-CS system), which is associated with the localization of the dye in pluronic micelles. In PBS, the fluorescence anisotropy is practically the same for all systems, which is related to the stability of the dye structure in this medium. The presence of interaction between RB and AP in aqueous solutions was confirmed by the proton NMR method. In addition, the formation of RB-F108 macromolecular complexes, which form associates during solution concentration (in particular, during evaporation), was shown by AFM. Such RB-AP-CS systems may be promising for practical application in the treatment of local foci of infections by aPDT.

Immersed boundary simulations of cell-cell interactions in whole blood

We present a new method for the geometric reconstruction of elastic surfaces simulated by the immersed boundary method with the goal of simulating the motion and interactions of cells in whole blood. Our method uses parameter-free radial basis functions for high-order meshless parametric reconstruction of point clouds and the elastic force computations required by the immersed boundary method. This numerical framework allows us to consider the effect of endothelial geometry and red blood cell motion on the motion of platelets. We find red blood cells to be crucial for understanding the motion of platelets, to the point that the geometry of the vessel wall has a negligible effect in the presence of RBCs. We describe certain interactions that force the platelets to remain near the endothelium for extended periods, including a novel platelet motion that can be seen only in 3-dimensional simulations that we term “unicycling.” We also observe red blood cell-mediated interactions between platelets and the endothelium for which the platelet has reduced speed. We suggest that these behaviors serve as mechanisms that allow platelets to better maintain vascular integrity.

Association of Preoperative Cerebrospinal Fluids Parameters With Early Shunt Obstruction in Patients With Post-hemorrhagic Hydrocephalus Treated by Lumboperitoneal Shunt.

Background: Early shunt obstruction (SO) remains the most common cause of lumboperitoneal shunt (LPS) failure. Although there is anecdotal evidence that the level of cerebrospinal fluid (CSF) parameters might affect shunt performance, its association with early LPS obstruction in adults with post-hemorrhagic hydrocephalus (PHH) is unclear.Methods: The retrospective study was performed by reviewing the adults with PHH treated by LPS from years 2014 to 2018. We included patients with CSF samples analyzed within 1 week prior to shunt insertion or at the time of shunt insertion. Baseline characteristics of each patient were collected. The primary outcomes were the incidence rate and associated factors of SO occurring within 3 months of shunt placement. The secondary outcomes included scores on the National Institute of Health Stroke Scale (NIHSS) and Evans Index at discharge.Results: A total of 76 eligible patients were analyzed, of whom 61 were obstruction-free and 15 were early SO. The overall rate of early SO was 15.6%. The RBCs count and nucleated cells count in preoperative CSF were actually higher in patients with early SO, compared to patients in the control group. Multivariate analysis identified RBC elevation (>0 × 106/L; OR: 10.629, 95% CI: 1.238–91.224, p = 0.031) as a dependent risk factor for early SO. NIHSS dramatically decreased at discharge while the alteration of ventricular size was not observed.Conclusions: This study suggested that the presence of RBCs in preoperative CSF was associated with early SO in patients with PHH treated by LPS.

Motion of a tumour cell under the blood flow at low Reynolds number in a curved microvessel

ABSTRACT Investigation of the flowing behaviours of circulating tumour cells (CTCs) under the blood flow is of fundamental importance for understanding haematogenous metastasis. In this study, the motion of a CTC at low flow rates in microvessels were simulated by dissipative particle dynamics combined with a spring-based network model to characterise cell deformation. The effects of vessel curvature, cell deformability and the presence of RBCs on the motion of an initially adherent tumour cell were investigated. The results suggested that at low Reynolds number, the viscous force plays a dominant role and the curved vessel would initiate the formation of more simultaneous bonds. And, the shear force acted on the softer tumour cell would induce large contact area and further stimulate the formation of more ligand–receptor bond numbers. Moreover, to investigate the non-Newtonian nature of the blood flow on tumour cell motion, the blood was regarded as a suspension of RBCs. With the presence of RBC suspensions, the collision between the tumour cell and RBCs increases the drag force and promotes the disassociation of the CTC from the vessel wall.

Red Blood Cells Elicit Platelet-Dependent Neutrophil Recruitment Into Lung Airspaces.

Hemolysis that occurs in intravascular hemolytic disorders, such as sickle cell disease and malaria, is associated with inflammation and platelet activation. Alveolar hemorrhage, for example following primary blast lung injury or acute respiratory distress syndrome, results in the escape of erythrocytes (RBCs) into alveolar spaces, where they subsequently lyse and release their intracellular contents. However, the inflammatory effects of RBCs in the airways are not fully understood. We hypothesized that RBCs in the airway induce an inflammatory response, associated with platelet activation. By instilling whole RBCs or lysed RBCs into the airways of mice, we have demonstrated that whole RBCs elicit macrophage accumulation in the lung. On the other hand, lysed RBCs induce significant inflammatory cell recruitment, particularly neutrophils and this was associated with a 50% increase in circulating platelet neutrophil complexes. Platelet depletion prior to lysed RBC exposure in the lung resulted in reduced neutrophil recruitment, suggesting that the presence of intracellular RBC components in the airways can elicit inflammation that is platelet dependent. To identify specific platelet-dependent signaling pathways involved in neutrophil recruitment, anti-P-selectin ligand and anti-PSGL1 blocking antibodies were tested; however, neither affected neutrophil recruitment. These findings implicate an involvement for other, as yet unidentified platelet-dependent signaling and adhesion mechanisms. Further understanding of how platelets contribute to lung inflammation induced by the presence of RBCs could offer novel therapeutic approaches to attenuate inflammation that occurs in conditions associated with alveolar hemorrhage.

Lack of cell movement impairs survival of peripheral blood IL-2-stimulated natural killer cells originating from solid cancer and promotes red blood cells to induce their switch toward a regulatory phenotype

BackgroundRed blood cells (RBCs) can have a modulatory effect on immune cells; so changes in their dynamism could considerably influence their physiology, and consequently the immune activities of neighbouring cells, like natural killer (NK) cells. Herein, we studied the effect of both RBCs and lack of cell movement on the proliferation, survival and regulation of peripheral IL-2-stimulated NK cells from normal and solid malignant conditions. MethodsExperiments were conducted on twelve cell culture groups, including NK cells from patients with solid malignant tumor or healthy controls, cultured alone or with autologous or nonautologous RBCs under shaking or no shaking conditions. ResultsNK cells from neoplastic patients behaved differently depending on the culture conditions including shaking and/or RBCs presence. Therefore, NK cells survival was downregulated in the absence of shaking; whereas, shaking have not only upregulated cell survival, but also downregulated the levels of p53-related apoptosis. Moreover, RBCs enhanced NK cells proliferation; while, this effect was modulated by shaking. Furthermore, RBCs can generate opposite effects on the production and modulation of protumoral or immunosuppressive cytokines, depending on the origin of NK cells, i.e., whether they derive from healthy or solid malignant tumor conditions. Finally, NK cells become able to express Foxp3 regulatory marker when combining three main conditions that include (i) treatment with high dose of IL-2, (ii) presence of RBCs, and (iii) absence of shaking. ConclusionsOur outcomes showed for the first time that cell stagnation would be markedly involved in peripheral NK cell apoptosis, as well as in switching toward a regulatory phenotype-induced Foxp3. Cell movement may be one of ex vivo potential approaches in boosting the activities and survival of such cells during solid cancer.

Investigation of the Relationship between Ultrasonographic Findings and Analyses of Bladder Contents in Cats

Background: Echoes are frequently observed in cat bladder contents through ultrasonography and often mentioned as incidental findings. No comprehensive study has been conducted so far on the precise echoes nature in the bladder contents ultrasonography in cats. OBJECTIVES: The purpose of this study is to provide an accurate description of the cat bladder contents echoes and to specify the relationship between ultrasonographic findings and urinalyses. METHODS: 30 adult DSH cats were investigated. Bladder ultrasonography was performed. The numbers of echoes in the bladder were qualitatively divided into four classes. At least 5 ml of urine was collected with cystocentesis. Urinalysis was performed on the urine sediment. The statistical analyses were done. RESULTS: Echoes were observed in 19 cases. The echoes were suspended in 17 of the cases, in those cases they were observed and clumped in 2 cases. Of the 19 cases where echoes had been observed in the bladder contents, 9 included oil droplets, 2 included struvite crystals and 4 included hematuria as reported in urinalysis. For 6 of the cats with echoes in the bladder contents, oil droplets, RBCs, and crystals were not reported in urinalysis. The number of echoes observed in the bladder in presence of RBCs, oil droplets, crystals, and leucocytes was not statistically significant (P>0.05). CONCLUSIONS: Based on this study, most of the echoes observed in the ultrasonography of cats’ bladder contents can be associated with the presence of oil droplets in the urine, which is in accordance with previous studies.

Sensing adhesion forces between erythrocytes and γ’ fibrinogen, modulating fibrin clot architecture and function

Plasma fibrinogen includes an alternatively spliced γ-chain variant (γ’), which mainly exists as a heterodimer (γAγ’) and has been associated with thrombosis. We tested γAγ’ fibrinogen-red blood cells (RBCs) interaction using atomic force microscopy-based force spectroscopy, magnetic tweezers, fibrin clot permeability, scanning electron microscopy and laser scanning confocal microscopy. Data reveal higher work necessary for RBC-RBC detachment in the presence of γAγ’ rather than γAγA fibrinogen. γAγ’ fibrinogen–RBCs interaction is followed by changes in fibrin network structure, which forms an heterogeneous clot structure with areas of denser and highly branched fibrin fibers. The presence of RBCs also increased the stiffness of γAγ’ fibrin clots, which are less permeable and more resistant to lysis than γAγA clots. The modifications on clots promoted by RBCs-γAγ’ fibrinogen interaction could alter the risk of thrombotic disorders.

Discovering Novel Antimicrobial Peptides using High-Throughput Screening in the Presence of Human Erythrocytes

Antimicrobial peptides (AMPs) have long been considered excellent candidates for development as antibiotic agents to combat the threat of drug resistant bacterial pathogens. Yet, the promise AMPs have displayed in the laboratory has not yielded correlative clinical success. We hypothesized that a major reason for the disparity between outcomes at the bench and in the clinic is AMP interaction with and toxicity towards host cells. Here, we validate this theory using human red blood cells as model eukaryotic cells. Indeed, the potency of several well-studied antimicrobial peptides decreases from minimum sterilizing concentrations (MSC) of 1-5 μM to >30 μM in the presence of RBCs at 1x109 cells/ml; equivalent to 20% of the human physiological concentration. To address this issue, we have developed a high-throughput method to screen a combinatorial peptide library for antimicrobial activity in the presence of concentrated human cells. The screen consists of assays that assess the effect of RBCs on antimicrobial activity as well as toxicity toward eukaryotic cells. We present data on peptides identified and characterized from the high-throughput library screen and show that these new peptides were not as effective as they initially appeared during the screen. We demonstrate that the difference between observed and expected results is due to unforeseen proteolytic activity sequestered within the cytosol of the red blood cells. Finally, we show that a library consensus sequence synthesized using all d-amino acids outperforms all library isolates as well as the template sequence in terms of microbicidal activity in the presence of RBCs. Ultimately, our results suggest that combining the power of combinatorial library screening with the nuance of rational sequence engineering is an effective approach to engineering novel antimicrobial peptides that retain activity under physiological conditions.

Red Blood Cells Interfere with the Activity of Antimicrobial Peptides

Antimicrobial peptides (AMPs) have long been considered excellent candidates for development as antibiotic agents to combat the imminent threat of drug-resistant bacterial pathogens. Yet, the promise that AMPs display in the laboratory has not yielded correlative clinical success. We hypothesized that a major reason for this disparity is AMP interaction with and toxicity towards host cells. Here, we validate this theory using human red blood cells as model eukaryotic cells. The potency of several well-studied antimicrobial peptides decreases from minimum sterilizing concentrations (MSC) of 1-6 μM in the absence of RBCs to >30 μM in the presence of RBCs at 1x109 cells/ml; equal to 20% of the concentration in whole blood. To circumvent this roadblock to clinical utility, we have adopted a high-throughput approach of screening a second-generation antimicrobial peptide library for activity in the presence of RBCs. We present data from preliminary screening that indicates our new library contains peptides that retain activity in the presence of RBCs; greatly outperforming the template peptide. Additionally, we show data on two peptides discovered in our preliminary screens that have been characterized and compared to the template sequence. Both of the peptides discovered show reduced antimicrobial potency as compared to the parent sequence when RBCs are not present, but increased efficacy in the presence of concentrated erythrocytes. As these peptides were discovered in a small screen of only 2000 library sequences, we believe the library contains peptides that will retain potent activity in the presence of RBCs. Finally, we present a revised screening approach that will be employed for a full-scale screen of the library with the intention of retaining the high antibiotic potency characteristic of the parent peptide while selecting for minimal interaction with and toxicity toward eukaryotic cells.

Conventional pap (papanicoloau) smear cytology in primary screening of cervical lesions & its comparison with manual liquid based cytology

Background: Conventional pap smear (CPS) examination has been the mainstay for early detection of cervical cancer. However, its widespread use has not been possible due to the inherent limitations, like presence of obscuring blood and inflammation, reducing its sensitivity considerably. Aims & Objectives: The study was performed to compare the efficacy of Manual Liquid based Cytology (MLBC) with CPS and to find out whether MLBC can be established for routine use in our laboratory setup. Materials & Methods: Cervical smears were collected by the gynaecologist using Ayre’s spatula and cytobrush for the conventional Pap smear method and are suspended in a liquid medium for manual liquid based cytology technique. In this study, cervical screening was performed in 481 cases, all were married women of reproductive age group who visited Department of Obstetrics and Gynaecology over a period of one year from July 2014 to June 2015. Slides were examined for cytomorphological parameters. The details regarding cell size, cytoplasmic and nuclear details were studied for making the diagnosis. Result: The sensitivity of CPS in detecting cervical lesions is 95% and by MLBC is 50% while the specificity was 86% with CPS technique and 69% by MLBC technique. Conclusion: The cellular features are better in MLBC as compared to CPS and also background is more clear in MLBC as there was no obscuration by RBCs or inflammatory cells while in CPS, the background is dirty due to the presence of RBCs, necrosis and inflammation. Keywords: Conventional Pap Smear, Manual Liquid based Cytology, Pap smear, Cervical cytology

The Interaction Between Collagen-Activated Platelets and Erythrocytes Selectively Increases the Release of Subsets of Platelet α-Granules Containing Pro-Angiogenic Substances

Activated platelets release a wide range of bioactive molecules including growth factors, cytokines, chemokines, coagulation factors etc., known to influence processes like haemostasis, thrombosis, inflammation, wound healing and angiogenesis. The interaction between activated platelets with intact erythrocytes (RBCs) increases dense (14C-serotonin) and alpha (β-thromboglobulin) platelet granule secretion (1, 2). Platelets have different sets of α-granules which are selectively released depending on the platelet agonist and signaling mechanism (3).Aims. to study a) if platelet-RBC interactions induce any differential regulation on the secretion of sets of platelet α-granules containing pro- or antiangiogenic compounds and b) the potential influence of aspirin on the release of these substances.Methods. Washed platelets alone (WP) or WP+RBCs from normal human subjects were incubated (10min, 37ºC) with aspirin (100µM) or solvent. Collagen (or its solvent) were added to samples, mixed (10 sec) and centrifuged (13,000xg, 1min) to obtain a cell-free releasate (1, 2). A semi-quantitative analysis of 43 pro- and anti-angiogenic substances in releasates was performed using antibody arrays (RayBiotech, Inc). In addition, the concentration of VEGF and ENA-78 (pro-angiogenics) and endostatin (anti-angiogenic) were quantified in the cell-free releasates by ELISA (R&D Systems) in 4 donors.Results. The array data demonstrated a striking selectivity in the effect of RBCs (hematocrit, 40%) for releasing the subset of α-granules containing pro-angiogenic substances. For instances, as compared to WP, RBCs increased the release of CXCL1 (7-fold), angiopoietin (30-fold) and MCP-1 (50-fold), while the release of anti-angiogenic substances such as TIMP-1 or endostatin were not modified by RBCs. Evaluating by ELISA the concentration of two angiogenic stimulators (VEGF and ENA-78) and of one anti-angiogenic compound, endostatin, we observed that RBCs increased the concentration of VEGF and ENA-78 in a hematocrit-dependent manner reaching a 18-fold and 10-fold increase, respectively with 40% hematocrit (p<0.05), while the endostatin release was not increased by RBCs. In samples not stimulated (collagen-solvent) no differences were noted between WP and WP+RBCs. Incubation of samples with aspirin did not modify the release in samples of WP but drastically reduced the collagen-induced VEGF and ENA-78 release in the presence of RBCs (>95% inhibition) while aspirin had a scarce effect on endostatin release.Conclusions. Cell-cell contact between collagen-activated platelets and RBCs is an important determinant for the specific release of subsets of platelet α-granules containing angiogenesis stimulators, which may play a role in patients with cancer. The aspirin down-regulation of the enhancing effect of RBCs on release of pro-angiogenic substances may be a contributory factor of the beneficial effect of aspirin observed in some patients with cancer.1.Santos MT et al J Clin Invest 1991;87:571-80; 2. Valles J et al. Blood 1991;78:154-62 ; 3. Italiano JE Blood 2008; 111:1227-33.Grant support: IIS Carlos III. Fondos FEDER PI13/00016; Red Cardiovascular [RD12/0042/0003] DisclosuresNo relevant conflicts of interest to declare.

Risk factors associated with calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States

Calcium oxalate urolithiasis results from the formation of aggregates of calcium salts in the urinary tract. Difficulties associated with effectively treating calcium oxalate urolithiasis and the proportional increase in the prevalence of calcium oxalate uroliths relative to other urolith types over the last 2 decades has increased the concern of clinicians about this disease. To determine factors associated with the development of calcium oxalate urolithiasis in dogs evaluated at general care veterinary hospitals in the United States, a retrospective case-control study was performed. A national electronic database of medical records of all dogs evaluated between October 1, 2007 and December 31, 2010 at 787 general care veterinary hospitals in the United States was reviewed. Dogs were selected as cases at the first-time diagnosis of a laboratory-confirmed urolith comprised of at least 70% calcium oxalate (n=452). Two sets of control dogs with no history of urolithiasis diagnosis were randomly selected after the medical records of all remaining dogs were reviewed: urinalysis examination was a requirement in the selection of one set (n=1808) but was not required in the other set (n=1808). Historical information extracted included urolith composition, dog's diet, age, sex, neuter status, breed size category, hospital location, date of diagnosis, and urinalysis results. Multivariable analysis showed that the odds of first-time diagnosis of calcium oxalate urolithiasis were significantly (P<0.05) greater for dogs<7 years, males (OR: 7.77, 95% CI: 4.93–12.26), neutered (OR: 2.58, 1.44–4.63), toy- vs. medium-sized breeds (OR: 3.15, 1.90–5.22), small- vs. medium-sized breeds (OR: 3.05, 1.83–5.08), large- vs. medium-sized breeds (OR: 0.05, 0.01–0.19), and those with a diagnosis of cystitis within the previous year (OR: 6.49, 4.14–10.16). Urinary factors significantly associated with first-time diagnosis of calcium oxalate urolithiasis were acidic vs. basic pH (OR: 1.94, 1.22–3.10), presence of RBCs (OR: 6.20, 3.91–9.83) or WBCs (OR: 1.62, 1.03–2.54), and protein concentration>30mg/dL (OR: 1.55, 1.04–2.30). Patient demographics and urinalysis results are important factors that can support risk assessment and early identification of canine oxalate urolithiasis. Therefore, periodic urolith screening and monitoring of urine parameters should be encouraged for dogs at risk of developing these uroliths.

The margination propensity of ellipsoidal micro/nanoparticles to the endothelium in human blood flow

Particle shape is becoming increasingly recognized as an important parameter for the development of vascular-targeted carriers (VTCs) for disease treatment and diagnosis. However, limited research exists that investigates how particle shape coupled with hemodynamics affects VTC margination (localization and adhesion). In this study, we investigate the effects of particle shape parameters (volume, aspect ratio, axis length) on the margination efficacy of targeted spheres and prolate ellipsoids (rods) to an inflamed endothelial wall from human blood flow in an in vitro model of human vasculature. Overall, particles with 2 μm equivalent spherical diameters (ESD) display higher margination than particles with either 1 μm or 500 nm ESDs. Interestingly, rod-shaped microparticles (1 μm or 2 μm ESD) with high aspect ratios display significantly improved margination compared to spheres of equal volume, particularly under high shear rates and disturbed flow profiles. Nanorods (500 nm ESD), even with high aspect ratio, do not display enhanced margination compared to that of equivalent spheres, which suggests that nanorods, like nanospheres, display minimal margination due to their inability to effectively localize to the vessel wall in the presence of RBCs.

Structural failures of the blood–gas barrier and the epithelial–epithelial cell connections in the different vascular regions of the lung of the domestic fowl, Gallus gallus variant domesticus, at rest and during exercise

SummaryStructural failure of blood–gas barrier (BGB) and epithelial–epithelial cell connections (EECCs) in different vascular regions of the exchange tissue of the lung was studied in rested and exercised chickens. The number of red blood cells (nRBCs) was counted and protein concentration (PC) measured after lavaging the respiratory system, and blood was sampled to determine the blood lactate levels (BLLs). The numbers of complete BGB breaks (nBGBBs) and those of the EECCs (nEECCBs) were counted in the different vascular territories of the lung. The nRBCs and the PCs increased with increasing exercise intensities but the rate of increase decreased at higher workloads. From rest to the fastest experimental treadmill speed of 2.95 m.sec−1, BLLs increased 4-fold. In all cases, the nEECCBs exceeded those of the BGB, showing that structurally the BGB is relatively weaker than the EECC. The increase in the number of breaks with increasing exercise can be attributed to increase in the pulmonary capillary blood pressure (PCBP) from faster heart rates and higher cardiac outputs, while the leveling out of the measurements made at higher workloads may have arisen from hemodynamic changes that initially ensued from exudation of blood plasma and then flow of blood into the air capillaries on failure of the BGB. The relative differences in the nBGBBs and the nEECCBs in the different vascular regions of the lung were ascribed to diameters of the branches and their points of origin and angles of bifurcation from the pulmonary artery. Presence of RBCs in the air capillaries of the lungs of rested chickens showed that failure of the BGB commonly occurs even in healthy and unstressed birds. Rapid repair and/or defense responses, which were observed, may explain how birds cope with mechanical injuries of the BGB.

Risk factors associated with struvite urolithiasis in dogs evaluated at general care veterinary hospitals in the United States

To identify factors associated with development of struvite urolithiasis in dogs evaluated at general care veterinary hospitals in the United States. Retrospective case-control study. 508 dogs with a first-time diagnosis of struvite urolithiasis and 7,135 control dogs. Electronic medical records of all dogs evaluated at 787 general care veterinary hospitals in the United States between October 2007 and December 2010 were reviewed to identify dogs that developed struvite urolithiasis and 2 groups of control dogs with no history of urolithiasis. Information extracted included diet, age, sex, neuter status, breed size category, hospital location, and date of diagnosis. Urinalysis results, urolith composition, and other disease conditions were recorded if applicable. Potential risk factors were assessed with univariable and multivariable regression analysis. Toy- or small-sized breeds had significantly greater odds of struvite urolithiasis, compared with medium- or large-sized breeds. Neutering significantly increased the odds of this outcome in females only; sexually intact females were more likely to develop struvite urolithiasis than were sexually intact males, but only up to 5 years of age. Urinary factors significantly associated with the outcome were basic (vs acidic) pH, presence of RBCs or WBCs, protein concentration > 30 mg/dL, and ketone concentration ≥ 5 mg/dL. Evaluation of demographic characteristics and urinalysis results may be useful in the early identification of struvite urolithiasis in dogs. Periodic urinalysis in dogs is recommended because of the potential health impact of a late diagnosis of urolithiasis.

Sphingosine‐1‐phosphate from erythrocytes modulates water and macromolecule permeability in rat microvessels

Exogenous sphingosine‐1‐phosphate (S1P) attenuates acute increases in vascular permeability acting through receptor S1P1 to stabilize the endothelial barrier. Recent evidence shows that S1P is synthesized, stored in and released from erythrocytes. This study directly evaluates the contribution of erythrocyte derived S1P to maintain basal permeability to serum albumin in intact individually perfused venular microvessels of rat mesentery. Permeability coefficients (Ps) to albumin, α‐lactalbumin and the hydraulic conductivity (Lp) of mesenteric venules were measured in the presence or absence of perfusates containing rat erythrocytes (RBCs) or RBC conditioned media. Under these conditions RBCs added to the perfusate were the principal source of S1P in the microvessel. Albumin Ps values were stable and within the range expected of blood perfused microvessels (mean 0.5 × 10−6 cm/sec) when RBCs or RBC conditioned media were present. When absent, Ps to albumin or α‐lactalbumin was increased up to 10 fold. The S1P1 receptor antagonist (W146) reversed the stabilizing action of RBCs and Ps increased to the same extent as in the absence of RBCs. W146 also increased Lp in the presence of RBCs used as flow markers. We conclude that erythrocytes are the primary source of S1P that maintains normal venular microvessel permeability. Disease states which reduce RBC derived S1P may increase basal permeability. Supp NIH HL28607