Following red blood cells in a pulmonary capillary

The red blood cells or erythrocytes are biconcave shaped cells and consist mostly in a membrane delimiting a cytosol with a high concentration in hemoglobin. This membrane is highly deformable and allows the cells to go through narrow passages like the capillaries which diameters can be much smaller than red blood cells one. They carry oxygen thanks to hemoglobin, a complex molecule that have very high affinity for oxygen. The capacity of erythrocytes to load and unload oxygen is thus a determinant factor in their efficacy. In this paper, we will focus on the pulmonary capillary where red blood cells capture oxygen. We propose a camera method in order to numerically study the behavior of the red blood cell along a whole capillary. Our goal is to understand how erythrocytes geometrical changes along the capillary can affect its capacity to capture oxygen. The first part of this document presents the model chosen for the red blood cells along with the numerical method used to determine and follow their shapes along the capillary. The membrane of the red blood cell is complex and has been modelled by an hyper-elastic approach coming from Mills et al (2004). This camera method is then validated and confronted with a standard ALE method. Some geometrical properties of the red blood cells observed in our simulations are then studied and discussed. The second part of this paper deals with the modeling of oxygen and hemoglobin chemistry in the geometries obtained in the first part. We have implemented a full complex hemoglobin behavior with allosteric states inspired from Czerlinski et al (1999).Comment: 17 page

Rare-cell enrichment by a rapid, label-free, ultrasonic isopycnic technique for medical diagnostics

One significant challenge in medical diagnostics lies in the development of label-free methods to separate different cells within complex biological samples. Here we demonstrate a generic, low-power ultrasonic separation technique, able to enrich different cell types based upon their physical properties. For malaria, we differentiate between infected and non-infected red blood cells in a fingerprick-sized drop of blood. We are able to achieve an enrichment of circulating cells infected by the ring stage of the parasite over nonparasitized red blood cells by between two and three orders of magnitude in less than 3 seconds (enabling detection at parasitemia levels as low as 0.0005 %). In a second example, we also show that our methods can be used to enrich different cell types, concentrating Trypanosoma in blood at very low levels of infection, on disposable, low-cost chips

Label-free microfluidic enrichment of ring-stage Plasmodium falciparum-infected red blood cells using non-inertial hydrodynamic lift

<b>Background</b> Understanding of malaria pathogenesis caused by Plasmodium falciparum has been greatly deepened since the introduction of in vitro culture system, but the lack of a method to enrich ring-stage parasites remains a technical challenge. Here, a novel way to enrich red blood cells containing parasites in the early ring stage is described and demonstrated.<p></p> <b>Methods</b> A simple, straight polydimethylsiloxane microchannel connected to two syringe pumps for sample injection and two height reservoirs for sample collection is used to enrich red blood cells containing parasites in the early ring stage (8-10 h p.i.). The separation is based on the non-inertial hydrodynamic lift effect, a repulsive cell-wall interaction that enables continuous and label-free separation with deformability as intrinsic marker.<p></p> <b>Results</b> The possibility to enrich red blood cells containing P. falciparum parasites at ring stage with a throughput of ~12,000 cells per hour and an average enrichment factor of 4.3 ± 0.5 is demonstrated.<p></p> <b>Conclusion</b> The method allows for the enrichment of red blood cells early after the invasion by P. falciparumparasites continuously and without any need to label the cells. The approach promises new possibilities to increase the sensitivity of downstream analyses like genomic- or diagnostic tests. The device can be produced as a cheap, disposable chip with mass production technologies and works without expensive peripheral equipment. This makes the approach interesting for the development of new devices for field use in resource poor settings and environments, e.g. with the aim to increase the sensitivity of microscope malaria diagnosis.<p></p&gt

Blood Flow in silico: From Single Cells to Blood Rheology

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Mesoscale hydrodynamics simulations of red blood cells under flow have provided much new insight into their shapes and dynamics in microchannel flow. The presented results range from the behavior of single cells in confinement and the shape changes in sedimentation, to the clustering and arrangement of many cells in microchannels and the viscosity of red blood cell suspensions under shear flow. The interaction of red blood cells with other particles and cells, such as white blood cells, platelets, and drug carriers, shows an essential role of red blood cells in the margination of other blood components

Tratamento Endovascular de Aneurismas da Aorta e Transfusão de Sangue. O que Precisamos?

INTRODUCTION: Comparatively to open repair, endovascular aneurysm repair has reduced transfusion rates but thereâs no recommendation about number of red blood cells units to be crossmatched preoperatively. Our aim is contribute to the analysis of red blood cells units needs in endovascular and hybrid aortic aneurysm repair and developing a protocol for maximum surgical blood orders schedule. MATERIAL AND METHODS: We retrospectively analyzed our prospective database of elective endovascular aneurysm repair from 2001 to 2012. We analyzed patients' age, gender, ASA classification, maximum surgical blood orders schedule, red blood cells units transfused and timings, types of endoprosthesis, red blood cells units consumption/endoprosthesis' type ratio, crossmatch to transfusion ratio, conversion to open repair, hemoglobin concentrations before surgery and discharge. RESULTS: We selected 187 patients, 90% men, mean age 73.1, ASA mode III. The endoprosthesis were aorto-bi-iliac in 71%, aorto-uni-iliac in 23% and thoracic in 6%. Of these, 72,6% of the patients did not require blood transfusion. We transfused 171 red blood cells units. Crossmatch to transfusion ratio was 10.1 until 2010 and 7.3 after. The ratio of red blood cells units consumption/endoprosthesis in the first 24 hours was 0.21 red blood cells units/aorto-bi-iliac, 0.46 red blood cells units/aorto-uni-iliac, 0.8 red blood cells units/thoracic, 1.3 red blood cells units/hybrid-thoracic and 2 red blood cells units/hybrid-aorto-bi-iliac. A statistical correlation was observed between red blood cells units transfused postoperatively and type of endoprosthesis (p < 0.001) and between ASA classification and red blood cells units transfused after 24 hours (p < 0.01). DISCUSSION: Guidelines from the British Society of Haematology are based on a crossmatch to transfusion ratio of 2:1. Our crossmatch to transfusion ratio was 10.1 until 2010 and 7.3 from 2011 to 2012. CONCLUSION: These results changed our policy of maximum surgical blood orders schedule for endovascular aneurysm repair. We now type and screen aorto-bi-iliac and aorto-uni-iliac. We crossmatch two red blood cells units for thoracic, three red blood cells units for hybrid thoracic and four red blood cells units for hybrid abdominal procedures. This may lead to financial savings, improved efficiency and reduce workload in hematology department.info:eu-repo/semantics/publishedVersio

Transfusion-related acute lung injury in multiple traumatized patients

Background: Many of the multiple traumatized patients who refer to the hospital need transfusion. Transfusion-related acute lung injury (TRALI) is a serious clinical syndrome associated with the transfusion of plasma-containing blood components. In the article, we present a case of TRALI following transfusion of packed red blood cells Case Presentation: A 24 year old male referred to Shahid Beheshti Hospital due to multiple trauma with left femoral and humerus fractures. Due to severe anemia he received 3 units of packed red blood cells. The symptoms of TRALI began 2 hours after transfusion. He was transferred to intensive care unit (ICU) due to metabolic acidosis and severe hypoxia. The TRALI was confirmed after ruling out the other probable pulmonary diseases. He recovered and was discharged. Conclusion: Transfusion related acute lung injury should be considered in any case receiving transfusion of plasma containing blood components

Drugs for preventing red blood cell dehydration in people with sickle cell disease.

BACKGROUND: Sickle cell disease is an inherited disorder of hemoglobin, resulting in abnormal red blood cells. These are rigid and may block blood vessels leading to acute painful crises and other complications. Recent research has focused on therapies to rehydrate the sickled cells by reducing the loss of water and ions from them. Little is known about the effectiveness and safety of such drugs. This is an updated version of a previously published review. OBJECTIVES: To assess the relative risks and benefits of drugs to rehydrate sickled red blood cells. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group\u27s Haemoglobinopathies Trials Register.Last search of the Group\u27s Trials Register: 28 November 2015. SELECTION CRITERIA: Randomized or quasi-randomized controlled trials of drugs to rehydrate sickled red blood cells compared to placebo or an alternative treatment. DATA COLLECTION AND ANALYSIS: Both authors independently selected studies for inclusion, assessed study quality and extracted data. MAIN RESULTS: Of the 51 studies identified, three met the inclusion criteria. The first study tested the effectiveness of zinc sulphate to prevent sickle cell-related crises in a total of 145 participants and showed a significant reduction in painful crises over one and a half years, mean difference -2.83 (95% confidence interval -3.51 to -2.15). However, analysis was restricted due to limited statistical data. Changes to red cell parameters and blood counts were inconsistent. No serious adverse events were noted in the study.The second study was a Phase II dose-finding study of senicapoc (a Gardos channel blocker) compared to placebo. Compared to the placebo group the high dose senicapoc showed significant improvement in change in hemoglobin level, number and proportion of dense red blood cells, red blood cell count and indices and hematocrit. The results with low-dose senicapoc were similar to the high-dose senicapoc group but of lesser magnitude. There was no difference in the frequency of painful crises between the three groups. A subsequent Phase III study of senicapoc was terminated early since there was no difference observed between the treatment and control groups in the primary end point of painful crises. AUTHORS\u27 CONCLUSIONS: While the results of zinc for reducing sickle-related crises are encouraging, larger and longer-term multicenter studies are needed to evaluate the effectiveness of this therapy for people with sickle cell disease.While the Phase II and the prematurely terminated phase III studies of senicapoc showed that the drug improved red cell survival (depending on dose), this did not lead to fewer painful crises.We will continue to run searches to identify any potentially relevant trials; however, we do not plan to update other sections of the review until new trials are published