Numerical Model for the Determination of Erythrocyte Mechanical Properties and Wall Shear Stress in vivo From Intravital Microscopy.

The mechanical properties and deformability of Red Blood Cells (RBCs) are important determinants of blood rheology and microvascular hemodynamics. The objective of this study is to quantify the mechanical properties and wall shear stress experienced by the RBC membrane during capillary plug flow in vivo utilizing high speed video recording from intravital microscopy, biomechanical modeling, and computational methods. Capillaries were imaged in the rat cremaster muscle pre- and post-RBC transfusion of stored RBCs for 2-weeks. RBC membrane contours were extracted utilizing image processing and parametrized. RBC parameterizations were used to determine updated deformation gradient and Lagrangian Green strain tensors for each point along the parametrization and for each frame during plug flow. The updated Lagrangian Green strain and Displacement Gradient tensors were numerically fit to the Navier-Lame equations along the parameterized boundary to determined Lame's constants. Mechanical properties and wall shear stress were determined before and transfusion, were grouped in three populations of erythrocytes: native cells (NC) or circulating cells before transfusion, and two distinct population of cells after transfusion with stored cells (SC1 and SC2). The distinction, between the heterogeneous populations of cells present after the transfusion, SC1 and SC2, was obtained through principle component analysis (PCA) of the mechanical properties along the membrane. Cells with the first two principle components within 3 standard deviations of the mean, were labeled as SC1, and those with the first two principle components greater than 3 standard deviations from the mean were labeled as SC2. The calculated shear modulus average was 1.1±0.2, 0.90±0.15, and 12 ± 8 MPa for NC, SC1, and SC2, respectively. The calculated young's modulus average was 3.3±0.6, 2.6±0.4, and 32±20 MPa for NC, SC1, and SC2, respectively. o our knowledge, the methods presented here are the first estimation of the erythrocyte mechanical properties and shear stress in vivo during capillary plug flow. In summary, the methods introduced in this study may provide a new avenue of investigation of erythrocyte mechanics in the context of hematologic conditions that adversely affect erythrocyte mechanical properties

Sıcaklığa Duyarlı PNIPAM Hidrojellerde Çapraz Bağlayıcı ve Başlatıcı Sisteminin Karşılaştırılması

Thermoresponsive hydrogels are three-dimensional polymer networks which undergo conformational changes in aqueous media depending on the external temperature. As the lower critical temperature (LCST) is close to the body temperature, poly(N-isopropylacrylamide) (PNIPAM) is the main thermoresponsive hydrogel used for biomedical applications. Below LCST, PNIPAM hydrogels swell in aqueous media, above LCST they become insoluble and shrink. This behavior makes it possible to design drug release systems controlled by external temperature. Swelling/shrinking response of PNIPAM hydrogel depends on several factors such as crosslinker type, crosslinking density, hydrophobic/hydrophilic balance and initiator type. In this study, the effects of the initiation system and the crosslinker type on different thermoresponsive hydrogels were compared. For this purpose, thermoresponsive hydrogels were synthesized by using ethylene glycol dimethylacrylate (EGDMA) and N,N′-ethylene bisacrylamide (EBAM) as crosslinkers via photo and thermal initiation systems. The hydrogels were characterized by FTIR spectroscopy and scanning electron microscope (SEM). Effects of the initiation system and the crosslinker type on the release, swelling behavior, morphology and the biocompatibility behavior of the hydrogels were investigated. The hydrogels synthesized with EBAM demonstrated more promising results compared to the one synthesized EGDMA. It was concluded that poly(EBAM-co-NIPAM)-P has the highest swelling ratio and poly(EBAM-co-NIPAM)-T is the most biocompatible hydrogel. In terms of release characteristics, there was not a significant difference between the hydrogels, even though their swelling characteristics differ

Bringing Packed Red Blood Cells to the Point of Combat Injury: Are We There Yet?

INTRODUCTION: Hemorrhage is the leading cause of injury related pre-hospital mortality. We investigated worst case scenarios and possible requirements of Turkish Military. As we plan to use blood resources during casualty transport, the impact of transport related mechanical stress on PRBC (packed red blood cell) were analyzed. MATERIAL AND METHODS: The in vitro experiment was performed in the environmental test laboratories of ASELSAN(R). Operational vibrations of potential casualty transport mediums such as Sikorsky Helicopters, Kirpi(R) Armoured Vehicle and NATO vibration standardsoftware MIL-STD-810G were recorded. The most powerful mechanical stress, which was created by the NATO standard, was applied to 15 units of fresh (7 day) PRBC in a blood cooler box. The vibrations were simulated by TDS v895 Medium-Force Shaker Device. On site blood samples were analyzed at 0, 6th and 24th hours for biochemical and biomechanical analyses. RESULTS: The mean age of fresh and old PRBCs was 4.9 (SD +/- 2.2) and 32.8 (SD +/- 11.8) days, respectively. Six-hour mechanical damage of fresh PRBC was demonstrated by increased erythrocyte fragmentation rates (p=0.015), hemolysis rates (p=0.003), supernatant potassium levels (p=0.003) and decreased hematocrit levels (p=0.015). Old PRBC hemolysis rates (p=0.015), supernatant potassium levels (p=0.015), supernatant Hb (p=0.015) were increased and Htc levels were decreased (p=0.015) within 6 hours. Two (%13) units of fresh and none of the old PRBC were eligible for transfusion after 6 hours of mechanical stress. CONCLUSION: When the austere combat environment was simulated for 24 hours, fresh and old PRBC hemolysis rates were above the quality criteria. Currently, a technology to overcome this mechanical damage does not seem to exist. In the light of the above data, a new national project is being performed

Correction of Angular Deformities with Ilizarov External Fixator in Dogs

In this study, ten dogs with different breed, ages and genders were used for treathment of angular deformities. The limb deformities were discovered from the mediolateral and craniocaulal images of the preoperative radiographs. Apex of the deformity and the deformity plane were determined using graphical methods. Following ulnar ostectomy, rings were fixed to the distal and proximal segment of radius mall cases. After fixation of the wires to the ring. radial osteotomy was performed. Deformations were corrected immediately in two case and progressively in eight cases. Latency period ranged from 3-7 days (in immature dogs 3-5 days, mature dogs 5-7 days). A distraction rate of 1 mm day(-1) was used in all dogs. Distraction was performed twice daily in all dogs. Minor wire track inflamation occured in eight dogs with three dogs also having wire track infection. No post-operative neurological impairment was observed in any dogs. Follow-up evalution by clinical and radiological examination ranged from 95-150 days. Limb functions were assessed to be excellent in four dogs, good in four dogs and fair in two dogs

Detecting the interferences in adrenocorticotropic hormone measurement - three cases reinforcing the efficiency of the complementary clinical and laboratory audit

Highlights Comparing test results to clinical data enhances the identification of interferences Misinterpretation of ACTH as a result of interference may lead to unnecessary testing Despite the interference, ACTH concentration can be in the reference interval Accurate measurement of adrenocorticotropic hormone (ACTH) is crucial in the evaluation of pituitary and adrenal disorders. Although great progress has been achieved in ACTH measurement with immunometric assays, interference may occur and adversely affect the clinical management. The report contributes to compiling the evidence on the clinical challenges with the management of the interferences in the ACTH measurement by presenting three cases: two with clinically overt hypercortisolism and discrepant ACTH concentrations within the reference interval; the third case describes the falsely elevated ACTH in a patient with secondary adrenal insufficiency. In all patients, the results obtained with the two immunometric platforms, chemiluminescence (CLIA) immunoassay (Siemens, Immulite) and electrochemiluminescence (ECLIA) immunoassay (Roche, Cobas), were discordant. Serial dilution of plasma samples revealed nonlinearity. After polyethylene glycol (PEG) precipitation recoveries were less than 22%, 26%, and 3%, respectively, supporting interference. Moreover, a decrease in ACTH concentration after incubation in a heterophile antibody-blocking tube was observed in the second case. In the first case, misinterpretation of ACTH led to inferior petrosal sinus sampling (IPSS), whereas timely detection of assay interference prevented further investigations in other cases. Increasing awareness regarding ACTH interference and comprehensive approach in evaluation could allow timely detection, helping to prevent unnecessary testing and perplexing clinical outcomes

Contraception counselling during gynecology visit — does a questionnaire help?

Objectives: Women are at risk of unplanned pregnancy and inappropriate choice of contraception if not given effectivecontraception counselling. We aimed to understand the contraceptive needs of women, improve effective contraceptioncounselling promoting modern contraception methods during gynecology outpatient visit using a contraception counsellingquestionnaire.Material and methods: All reproductive-age women over 18 were given Contraception Counselling Project Form to fill inwhile in the waiting room. The form consisted of 15 questions evaluating patients’ characteristics and contraceptive methodused. Physicians evaluated these forms during the examination and an appropriate method was chosen. Forms of pregnant,postmenopausal and sexually inactive patients as well as forms with more than one answer missing were excluded.Results: 778 questionnaires were accepted for evaluation. 340 women (43.8%) used modern contraception, 112 (14.4%)used interrupted coitus, 3 (0.4%) used calendar method. 738 women could be given adequate contraception counsellingby the physicians. 215 women among 323 women (66.5%) who did not use modern contraception and did not desirepregnancy, were convinced to use modern contraception and 103 (91.9%) among 112 women who used interruptedcoitus for contraception were convinced to use modern contraception. There was a significant relationship between age,education, working state, parity, number and type of delivery, previous OCP usage, resources of contraception and thepreferred contraception method.Conclusions: More than half the women preferred to use modern contraception methods by means of contraceptioncounselling questionnaire. Women’s backgrounds significantly affected their choice of contraception method

A preliminary study of phosphodiesterases and adenylyl cyclase signaling pathway on red blood cell deformability of sickle cell patients

Sickle cell disease (SCD) is an inherited hemoglobinopathy characterized by chronic anemia, intravascular hemolysis, and the occurrence of vaso-occlusive crises due to the mechanical obstruction of the microcirculation by poorly deformable red blood cells (RBCs). RBC deformability is a key factor in the pathogenesis of SCD, and is affected by various factors. In this study, we investigated the effects of adenylyl cyclase (AC) signaling pathway modulation and different phosphodiesterase (PDE) modulatory molecules on the deformability and mechanical stress responses of RBC from SCD patients (HbSS genotype) by applying 5 Pa shear stress with an ektacytometer (LORRCA). We evaluated RBC deformability before and after the application of shear stress. AC stimulation with Forskolin had distinct effects on RBC deformability depending on the application of 5 Pa shear stress. RBC deformability was increased by Forskolin before shear stress application but decreased after 5 Pa shear stress. AC inhibition with SQ22536 and protein kinase A (PKA) inhibition with H89 increased RBC deformability before and after the shear stress application. Non-selective PDE inhibition with Pentoxifylline increased RBC deformability. However, modulation of the different PDE types had distinct effects on RBC deformability, with PDE1 inhibition by Vinpocetine increasing deformability while PDE4 inhibition by Rolipram decreased RBC deformability after the shear stress application. The effects of the drugs varied greatly between patients suggesting some could benefit from one drug while others not. Developing drugs targeting the AC signaling pathway could have clinical applications for SCD, but more researches with larger patient cohorts are needed to identify the differences in the responses of sickle RBCs

From METS to malaria: RRx-001, a multi-faceted anticancer agent with activity in cerebral malaria

BACKGROUND: The survival of malaria parasites, under substantial haem-induced oxidative stress in the red blood cells (RBCs) is dependent on the pentose phosphate pathway (PPP). The PPP is the only source of NADPH in the RBC, essential for the production of reduced glutathione (GSH) and for protection from oxidative stress. Glucose-6-phosphate dehydrogenase (G6PD) deficiency, therefore, increases the vulnerability of erythrocytes to oxidative stress. In Plasmodium, G6PD is combined with the second enzyme of the PPP to create a unique bifunctional enzyme, named glucose-6-phosphate dehydrogenase–6-phosphogluconolactonase (G6PD-6PGL). RRx-001 is a novel, systemically non-toxic, epigenetic anticancer agent currently in Phase 2 clinical development for multiple tumour types, with activity mediated through increased nitric oxide (NO) production and PPP inhibition. The inhibition of G6PD and NO overproduction induced by RRx-001 suggested its application in cerebral malaria (CM). METHODS: Plasmodium berghei ANKA (PbA) infection in C57BL/6 mice is an experimental model of cerebral malaria (ECM) with several similar pathological features to human CM. This study uses intravital microscopy methods with a closed cranial window model to quantify cerebral haemodynamic changes and leukocyte adhesion to endothelial cells in ECM. RESULTS: RRx-001 had both single agent anti-parasitic activity and significantly increased the efficacy of artemether. In addition, RRx-001 preserved cerebral perfusion and reduced inflammation alone or combined with artemether. RRx-001’s effects were associated with inhibition of PPP (G6PD and G6PD-6PGL) and by improvements in microcirculatory flow, which may be related to the NO donating properties of RRx-001. CONCLUSION: The results indicate that RRx-001 could be used to potentiate the anti-malarial action of artemisinin, particularly on resistant strains, and to prevent infection

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis