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1.
Inhal Toxicol ; 29(3): 126-136, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-28470141

RESUMEN

The use of electronic cigarettes (ECs) is rapidly increasing worldwide; however, scientific evidence regarding EC cytotoxicity is limited. The aim of this study was to evaluate the acute cytotoxicity of EC vapor extract (ECE) on airway-related cells in vitro. Cigarette smoke extract (CSE), vapor extract of fifteen brands/flavors of ECs and the extract from the E-vehicle (propylene glycol and glycerin) was collected. Extracts, in concentrations of 100-12.5%, were added to human bronchial epithelial (BEAS-2B, IB3-1 and C38), fibroblast (Wi-38) and macrophage (J774 and THP-1) cell lines. Viability was assessed after 24 h using a standard XTT assay. Viability of <70% of control (no extract) was considered cytotoxic according to UNI EN ISO 10993-5 standards. CSE displayed a concentration-dependent influence on cell viability across all four cell lines with 100% producing the most toxic effect, therefore validating the model and indicating higher cytotoxicity than in ECEs. ECEs did reduce viability although this was not correlated with nicotine content or the E-vehicle. However, several flavors proved cytotoxic, with variation between different brands and cell lines. These data indicate that not all ECs are the same and that use of a particular flavor or brand may have differing effects. The cell line used is also an important factor. More research is crucial to ascertain the health effects of different ECs before they can be accepted as a safe alternative to tobacco cigarettes.


Asunto(s)
Mezclas Complejas/toxicidad , Sistemas Electrónicos de Liberación de Nicotina , Aromatizantes/toxicidad , Humo , Bronquios/citología , Línea Celular , Supervivencia Celular/efectos de los fármacos , Humanos , Macrófagos/efectos de los fármacos , Nicotina/toxicidad , Nicotiana
2.
Artif Organs ; 37(3): 267-75, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23356400

RESUMEN

Cell exclusion is the phenomenon whereby the hematocrit and viscosity of blood decrease in areas of high stress. While this is well known in naturally occurring Poiseuille flow in the human body, it has never previously been shown in Couette flow, which occurs in implantable devices including blood pumps. The high-shear stresses that occur in the gap between the boundaries in Couette flow are known to cause hemolysis in erythrocytes. We propose to mitigate this damage by initiating cell exclusion through the use of a spiral-groove bearing (SGB) that will provide escape routes by which the cells may separate themselves from the plasma and the high stresses in the gap. The force between two bearings (one being the SGB) in Couette flow was measured. Stained erythrocytes, along with silver spheres of similar diameter to erythrocytes, were visualized across a transparent SGB at various gap heights. A reduction in the force across the bearing for human blood, compared with fluids of comparable viscosity, was found. This indicates a reduction in the viscosity of the fluid across the bearing due to a lowered hematocrit because of cell exclusion. The corresponding images clearly show both cells and spheres being excluded from the gap by entering the grooves. This is the first time the phenomenon of cell exclusion has been shown in Couette flow. It not only furthers our understanding of how blood responds to different flows but could also lead to improvements in the future design of medical devices.


Asunto(s)
Corazón Auxiliar , Hemólisis , Hemorreología , Velocidad del Flujo Sanguíneo , Viscosidad Sanguínea , Simulación por Computador , Diseño Asistido por Computadora , Glicerol/química , Hematócrito , Humanos , Modelos Cardiovasculares , Diseño de Prótesis , Estrés Mecánico , Viscosidad
3.
J Biomech ; 146: 111394, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36462474

RESUMEN

Cell exclusion in spiral groove bearing (SGB) excludes red blood cells from high shear regions in the bearing gaps and potentially reduce haemolysis in rotary blood pumps. However, this mechanobiological phenomenon has been observed in ultra-low blood haematocrit only, whether it can mitigate blood damage in a clinically-relevant blood haematocrit remains unknown. This study examined whether cell exclusion in a SGB alters haemolysis and/or high-molecular-weight von Willebrand factor (HMW vWF) multimer degradation. Citrated human blood was adjusted to 35 % haematocrit and exposed to a SGB (n = 6) and grooveless disc (n = 3, as a non-cell exclusion control) incorporated into a custom-built Couette test rig operating at 2000RPM for an hour; shearing gaps were 20, 30, and 40 µm. Haemolysis was assessed via spectrophotometry and HMW vWF multimer degradation was detected with gel electrophoresis and immunoblotting. Haemolysis caused by the SGB at gaps of 20, 30 and 40 µm were 10.6 ± 3.3, 9.6 ± 2.7 and 10.5 ± 3.9 mg/dL.hr compared to 23.3 ± 2.6, 12.8 ± 3.2, 9.8 ± 1.8 mg/dL.hr by grooveless disc. At the same shearing gap of 20 µm, there was a significant reduced in haemolysis (P = 0.0001) and better preserved in HMW vWF multimers (p < 0.05) when compared SGB to grooveless disc. The reduction in blood damage in the SGB compared to grooveless disc is indicative of cell exclusion occurred at the gap of 20 µm. This is the first experimental study to demonstrate that cell exclusion in a SGB mitigates the shear-induced blood damage in a clinically-relevant blood haematocrit of 35 %, which can be potentially utilised in future blood pump design.


Asunto(s)
Corazón Auxiliar , Factor de von Willebrand , Humanos , Factor de von Willebrand/análisis , Factor de von Willebrand/metabolismo , Hemólisis , Hematócrito , Eritrocitos/metabolismo
4.
Proc Inst Mech Eng H ; 236(9): 1253-1272, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35920401

RESUMEN

Metal and its alloys have been predominantly used in fracture fixation for centuries, but new materials such as composites and polymers have begun to see clinical use for fracture fixation during the past couple of decades. Along with the emerging of new materials, tribological issues, especially debris, have become a growing concern for fracture fixation plates. This article for the first time systematically reviews the most recent biomechanical research, with a focus on experimental testing, of those plates within ScienceDirect and PubMed databases. Based on the search criteria, a total of 5449 papers were retrieved, which were then further filtered to exclude nonrelevant, duplicate or non-accessible full article papers. In the end, a total of 83 papers were reviewed. In experimental testing plates, screws and simulated bones or cadaver bones are employed to build a fixation construct in order to test the strength and stability of different plate and screw configurations. The test set-up conditions and conclusions are well documented and summarised here, including fracture gap size, types of bones deployed, as well as the applied load, test speed and test ending criteria. However, research on long term plate usage was very limited. It is also discovered that there is very limited experimental research around the tribological behaviour particularly on the debris' generation, collection and characterisation. In addition, there is no identified standard studying debris of fracture fixation plate. Therefore, the authors suggested the generation of a suite of tribological testing standards on fracture fixation plate and screws in the aim to answer key questions around the debris from fracture fixation plate of new materials or new design and ultimately to provide an insight on how to reduce the risks of debris-related osteolysis, inflammation and aseptic loosening.


Asunto(s)
Tornillos Óseos , Fijación Interna de Fracturas , Fenómenos Biomecánicos , Placas Óseas , Cadáver , Fijación de Fractura , Humanos , Ensayo de Materiales
5.
Sci Rep ; 9(1): 6748, 2019 05 01.
Artículo en Inglés | MEDLINE | ID: mdl-31043640

RESUMEN

The airways of individuals with cystic fibrosis (CF) are abundantly colonised by Staphylococcus aureus and Pseudomonas aeruginosa. Co-infecting hypoxic regions of static mucus within CF airways, together with decreases in pulmonary function, mucus plugging and oxygen consumption by host neutrophils gives rise to regions of anoxia. This study determined the impact of anaerobiosis upon S. aureus-P. aeruginosa interactions in planktonic co-culture and mixed species biofilms in vitro. Whilst anoxia reduced the ability for P. aeruginosa CF isolates to dominate over S. aureus, this occurred in an isolate dependent manner. Investigations into the underlying mechanisms suggest that the anti-staphylococcal compound facilitating P. aeruginosa dominance under normoxia and anoxia is greater than 3 kDa in size and is heat-stable. Not all interspecies interactions studied were antagonistic, as S. aureus exoproducts were shown to restore and enhance P. aeruginosa motility under normoxia and anoxia in an isolate dependent manner. Collectively, this study suggests changes in oxygen availability within regions of the CF lung is likely to influence interspecies interactions and in turn, potentially influence disease progression.


Asunto(s)
Anaerobiosis , Fibrosis Quística/complicaciones , Interacciones Microbianas , Infecciones por Pseudomonas/etiología , Pseudomonas aeruginosa/aislamiento & purificación , Pseudomonas aeruginosa/metabolismo , Staphylococcus aureus/fisiología , Biopelículas , Técnicas de Cocultivo , Humanos , Hipoxia , Consumo de Oxígeno , Plancton , Pseudomonas aeruginosa/patogenicidad , Virulencia
6.
Toxicol In Vitro ; 52: 255-264, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-29940344

RESUMEN

Currently there is a lack of consensus on the possible adverse health effects of E-cigarettes (ECs). Important factors including cell model employed and exposure method determine the physiological relevance of EC studies. The present study aimed to evaluate EC cytotoxicity using a physiologically relevant in-vitro multicellular model of human airways. Human bronchial epithelial cells (CALU-3) and pulmonary fibroblasts (MRC-5) were co-cultured at air-liquid-interface for 11-14 days post which they were exposed to whole cigarette smoke (WCS) or EC vapour (ECV) at standard ISO-3308 regime for 7 m using a bespoke aerosol delivery system. ECV effects were further investigated at higher exposure times (1 h-6 h). Results showed that while WCS significantly reduced cell viability after 7 m, ECV decreased cell viability only at exposure times higher than 3 h. Furthermore, ECV caused elevated IL-6 and IL-8 production despite reduced cell viability. ECV exposure also produced a marked increase in oxidative stress. Finally, WCS but not ECV exposure induced caspase 3/7 activation, suggesting a caspase independent death of ECV exposed cells. Overall, our results indicate that prolonged ECV exposure (≥3 h) has a significant impact on pro-inflammatory mediators' production, oxidative stress and cell viability but not caspase 3/7 activity.


Asunto(s)
Sistemas Electrónicos de Liberación de Nicotina , Bronquios/citología , Línea Celular , Supervivencia Celular/efectos de los fármacos , Técnicas de Cocultivo , Células Epiteliales/efectos de los fármacos , Células Epiteliales/metabolismo , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Humanos , Pulmón/citología , Estrés Oxidativo/efectos de los fármacos
7.
Proc Inst Mech Eng H ; 232(6): 565-572, 2018 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29749792

RESUMEN

The majority of orthopaedic screws are designed, tested and manufactured by existing orthopaedics companies and are predominantly developed with healthy bone in mind. The timescales and costs involved in the development of a new screw design, for example, for osteoporotic bone, are high. In this study, standard wood screws were used to analyse the concept of using three-dimensional printing, or rapid prototyping, as a viable stage of development in the design of a new bone screw. Six wood screws were reverse engineered and printed in polymeric material using stereolithography. Three of the designs were also printed in Ti6Al4V using direct metal laser sintering; however, these were not of sufficient quality to test further. Both the original metal screws (metal) and polymeric rapid prototyping screws were then tested using standard pull-out tests from low-density polyurethane blocks (Sawbones). Results showed the highest pull-out strengths for screws with the longest thread length and the smallest inner diameter. Of the six screw designs tested, five showed no more than a 17% variance between the metal and rapid prototyping results. A similar pattern of results was shown between the screw designs for both the metal and rapid prototyping screws in five of the six cases. While not producing fully comparable pull-out results to orthopaedic screws, the results from this study do provide evidence of the potential usefulness and cost-effectiveness of rapid prototyping in the early stages of design and testing of orthopaedic screws.


Asunto(s)
Tornillos Óseos , Ensayo de Materiales/normas , Fenómenos Mecánicos , Procedimientos Ortopédicos/instrumentación , Impresión Tridimensional , Diseño de Equipo , Metales , Polímeros , Estándares de Referencia , Factores de Tiempo
8.
Proc Inst Mech Eng H ; 232(11): 1111-1116, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30284941

RESUMEN

Breast augmentation using implants is the most common aesthetic and reconstructive breast surgical procedure. Complications such as implant rupture maybe related to surgical technique and damage to the implant. Autologous fat transfer (lipofilling) using metallic cannulae has become a standard adjunctive, yet there is little evidence on lipofilling safety in the presence of implants. The aims of this study are to verify the effects of different cannulae and to quantify the forces applied by surgeons during lipofilling. Silicone gel-filled textured implants (200 mL), mounted on a specially constructed mould were ruptured with two different cannulae: type A (hole at tip: sharp) and type B (hole away from tip: blunt), driven at three speeds (10, 100 and 1000 mm/min), and the force at rupture was recorded. In addition, the maximum 10 forces over a 30-s period applied by 11 plastic surgeons against a breast implant in an in vitro environment were recorded using a load cell attached to a type-A cannula. Statistical analysis of comparative results was performed using t-tests, with p < 0.05 considered significant. Results showed that the implant ruptured at forces up to 25% lower when cannula A was used compared to cannula B. This supports current technique in lipofilling in the use of a blunt tipped cannula. There was a significant difference between some displacement rates only, due to the viscoelastic nature of the material. The tactile force that surgeons use during lipofilling was modelled in vitro and showed a range of maximum forces between 0.23 and 16.8 N, with a mean maximum value of 6.9 N. Limitation of this study is that it may not reflect in vivo behaviour of breast implants. More studies are needed to confirm the safety of breast lipofilling in the presence of implants using these data as a starting point.


Asunto(s)
Lipectomía/instrumentación , Fenómenos Mecánicos , Implantes de Mama , Cánula , Lipectomía/efectos adversos , Seguridad
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