7 research outputs found

    Ebola Hemorrhagic Fever as a Public Health Emergency of International Concern; a Review Article

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    Ebola hemorrhagic fever (EHF) was first reported in 1976 with two concurrent outbreaks of acute viral hemorrhagic fever centered in Yambuku (near the Ebola River), Democratic Republic of Congo, and also in Nzara, Sudan. The current outbreak of the Ebola Virus was started by reporting the first case in March 2014 in the forest regions of southeastern Guinea. Due to raising infection rates of over 13,000% within a 6-month period, now is considered as a global public health emergency and in August 8, 2014 the World Health Organization (WHO) has declared the epidemic to be a Public Health Emergency of International Concern. With more than 5000 involved cases and also nearly 3000 deaths, this event has turned to the largest and most dangerous Ebola virus outbreak in all around the world. Based on above mentioned, the present article aimed to review the virologic characteristics, transmission, clinical manifestation, diagnosis, treatment, and prevention of Ebola virus disease

    The Risk of Venous Thromboembolism with Different Generation of Oral Contraceptives; a Systematic Review and Meta-Analysis

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    Introduction: Oral contraceptives (OCs) are considered as one of the most common risk factor of venous thromboembolism (VTE) in child bearing age. Some of the recent researches indicate that the odds of VTE may be even higher with newer generations of OCs. The present meta-analysis was designed to evaluate the effect of different generation of OCs on the occurrence of VTE. Methods: Two researchers independently ran a thorough search in Pubmed, ISI Web of Science, EMBASE, CINAHL and Scopus databases regarding study keywords including thromboembolic event, thromboembolism, embolism, thromboembolic, thrombotic and thrombosis, combined with oral contraceptive. The outcomes were the incidence of diagnosed thromboembolism, such as deep vein thrombosis, pulmonary embolism and cerebral venous thrombosis. Based on the heterogeneity of the studies, random effect model was used and pooled odds ratio was reported. Results: Three cohort and 17 case-control studies with 13,265,228 subjects were entered into meta-analysis. Analysis showed that the odds of VTE in women taking OCs are more than three-fold (OR=3.13; 95% CI: 2.61-3.65). The risk of VTE in women taking first-, second- and third-generation OCs are 3.5 fold (OR=3.48; 95% CI: 2.01-4.94), 3 fold (OR=3.08; 95% CI: 2.43-3.74) and 4.3 fold (OR=4.35; CI: 3.69‚Äí5.01), respectively. Conclusion: It seems that the risk of VTE is not same between different generations of OCs, so that third-generation has highest risk. Taking second and third-generation OCs increases the risk of VTE up to 3 and 4.3 fold, respectively. The researchers of the present study suggest that more clinical trials be designed in relation to the effect of newer generations of OCs in different communities.

    Time dependent flow of biolubricant and suspended particles behavior within total hip replacement

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    Total hip replacement (THR) has been one of the most successful surgeries in the 21st century. Ultra-high-molecular-weight-polyethylene (UHMWPE) shows favorable mechanical and tribological properties when used as a bearing surface material in THR. However, produced UHMWPE wear particles challenge increasing the THR lifetimes. Bone loss (osteolysis) initiated by these wear particles is a major cause of total joint arthroplasty failure in both hip and knee prosthesis. In addition to improving the wear resistance of bearing surfaces to reduce wear, wear debris distribution mechanisms within the joint gap must also be thoroughly investigated. These particles distribute within lubricant and across the implant gap. Synovial fluid (SF) lubricates natural joints which is a viscoelastic non-Newtonian shear thinning fluid. The non-Newtonian behavior of SF is attributed to its hyaluronic acid (HA) content which is a linear biopolymer. The distribution patterns of wear particles within total joint replacement are affected by the special rheological behaviors of the SF, geometrical parameters, particle size and shape distribution and particle-fluid interactions. Therefore, understanding wear particles distribution pattern is pivotal to understand the mechanism and eventually minimizing third-body wear of the UHMWPE acetabular liner in THR. According to fluid mechanics forces, the size and density of wear particles suggests that wear particles follow lubricant movements. However, over a matter of hours, such particles show specific behaviors within viscoelastic fluid (not visible in Newtonian fluid) such as particle migration and string formation along the flow direction. The main aim of this project was to develop and validate an experimental method for assessing characteristics of HA and artificial SF solutions and behaviors of wear particles in a viscoelastic fluid flow. The effects of different parameters such as HA concentration, protein content, fluid flow types (steady, unsteady, etc.) and gap shapes on fluid behavior were quantified to fully understand such mechanisms. In this project, micro particle image velocimetry (micro-PIV) was applied as the quantitative flow visualization method. Pin-on-disk tribo-measurement was performed as a complimentary study to investigate the tribological behaviors of a UHMWPE pin rotating against a cobalt chromium molybdenum (CoCrMo) disk in the presence of HA solutions of various concentrations. This study was conducted to understand the effects of dynamic loading on lubricant performance relative to those of static loading. The results showed that under oscillatory flow conditions, strain levels, rates, and distributions are important parameters that affect the flow behaviors of HA solutions. Particle migration and alignment were affected by channel sizes, HA concentrations, flow types and the elastic instability of the solution. The tribological study results suggested that in the presence of HA, sinusoidal dynamic loading does not affect the frictional behaviors of UHMWPE moving against CoCrMo in comparison with static loading

    Bio-lubricant Behavior under Reciprocating Motion in Mini-Channel

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    Synovial fluid (SF) is articular joint lubrication. It contains a linear biopolymer called Hyaluronic acid(HA), which causes the viscoelastic behavior. Several studies on viscoelasticity of synovial fluid orHA solutions with different concentration and molecular weight have been carried out withrheometers. However, there are very few studies on the effect of viscoelasticity on HA solutionsmovement and velocity distribution inside the joint gap. Therefore, in this study, HA solutions withdifferent concentrations were studied under a sinusoidal reciprocating movement inside a rectangularmini-channel. This study focuses on deriving velocity distribution along channel width with MicroParticle Image Velocimetry (micro-PIV). Very high viscosity of the HA solutions suggests a quasisteadybehavior for this solution under investigated sinusoidal movement. However, the resultsindicated that the steady state laws are not applicable for estimating the HA behavior because ofspecial polymeric behavior of the HA chains inside the solutions.Godkänd; 2016; 20160722 (alasaf)</p

    Viscoelasticity and shear-thinning effects on bio-polymer solution and suspended particle behaviours under oscillatory curve Couette flow conditions

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    Formation of wear particles within total hip replacement is one of the main causes of its failure. In addition to improving the lubrication and wear resistance of materials used as bearing surfaces, understanding of wear particle distribution patterns within lubricants inside an implant gap could be used to improve design parameters and implants’ lifespan. In this study, the behaviours of biolubricants (with compositions similar to human joint synovial fluid) and suspended particles were investigated by micro-particle image velocimetry in curved mini channels under oscillatory Couette flow conditions. The studied biolubricants had shear-thinning viscoelastic characteristics. The authors found that increasing shear-thinning, elasticity or motion frequency levels did not affect the trend behaviours of biolubricant flows due to the low strain values of the experimental conditions applied. However, suspended particles formed strings along flow directions and exhibited cross-stream migration to channel walls. Motion frequency, fluid shear thinning and elasticity characteristics and channel dimensions strongly affected particle behaviours.Validerad;2018;Nivå 1;2018-08-16 (andbra)</p

    Hyperkalemia-induced complete heart block

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    Background: Potassium, as an extracellular ion, plays an important role in the electrophysiologic function of the myocardium and any change in extracellular concentration of this ion might have a marked impression upon myocyte electrophysiologic gain. High serum potassium levels are thought to impair pulse conduction in Purkinje fibers and ventricles more than that in the Atrioventricular (AV) node. Therefore, although complete AV block can occur, it is a rare initial presentation. Case Report: We describe a 62-year-old man with a history of diabetes mellitus, ischemic heart disease and previous Coronary Artery Bypass Graft (CABG), who came to our emergency department due to generalized weakness starting 2 days before admission. The patient also had decreased force in lower limbs, exacerbating from the morning, and was finally diagnosed as a hyperkalemia-induced Complete Heart Block (CHB). It should also be noted that the patient responded dramatically to the administration of 10 mL of 10% calcium gluconate along with external pacing until potassium level correction became effective. Conclusion: In spite of the fact that Hyperkalemia can be associated with frequent Electrocardiogram (ECG) abnormality, advanced heart blocks (second- and third-degree AV blocks) are usually found only in patients with pre-existing heart failure, conduction abnormalities, or other cardiac diseases. Institution of effective treatment rapidly and forgiveness of traditional non-effective, time consumptive and sometimes risking full-adjustment modalities, such as sodium bicarbonate infusion or exchange resins that prevent their use in the emergent phase, can help minimize patient morbidity and mortality

    Effect of dynamic loading versus static loading on the frictional behavior of a UHMWPE pin in artificial biolubricants

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    To obtain reliable results from in vitro measurements on the tribological behavior of joint implant materials, the parameters of the measurements must simulate in vivo conditions. Although the nature of the load in human joints is dynamic, most of the studies using simple pin-on-disk tribometers were performed with a constant load. The current study focused on investigating the effect of dynamic loading in comparison with static loading in the tribological behavior of ultra-high-molecular-weight polyethylene (UHMWPE) sliding against a cobalt chromium molybdenum (CoCrMo) counter surface with different lubricants, where the effects of hyaluronic acid (HA) and protein content in the lubricants were also investigated. The results suggested that although the dynamic loading did not affect the friction evolution for any of the lubricants, the friction value decreased for the lubricants that did not contain HA. The results showed that higher protein content in the lubricant increased the friction coefficient, however, it provided the highest protection against wear for sliding surfaces
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