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Sample records for platelet adhesion tests

  1. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films

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    Chou, Chia-Man [Department of Surgery, Taichung Veterans General Hospital, Taiwan, ROC (China); National Yang-Ming University, Taipei, Taiwan, ROC (China); Yeh, Chou-Ming, E-mail: cmchou4301@gmail.com [Taichung Hospital, Department of Health, Executive Yuan, Taiwan, ROC (China); Chung, Chi-Jen [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taiwan, ROC (China); He, Ju-Liang [Department of Materials Science and Engineering, Feng Chia University, Taiwan, ROC (China)

    2013-09-01

    Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ω{sub p}) and para-xylene monomer flow rate (f{sub p}). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ω{sub p} or high f{sub p}, in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ω{sub p} and f{sub p}. PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.

  2. In vitro cell culture, platelet adhesion tests and in vivo implant tests of plasma-polymerized para-xylene films

    Science.gov (United States)

    Chou, Chia-Man; Yeh, Chou-Ming; Chung, Chi-Jen; He, Ju-Liang

    2013-09-01

    Plasma-polymerized para-xylene (PPX) was developed in a previous study by adjusting the process parameters: pulse frequency of the power supply (ωp) and para-xylene monomer flow rate (fp). All the obtained PPX films exhibit an amorphous structure and present hydrophobicity (water contact angle ranging from 98.5° to 121.1°), higher film growth rate and good fibroblast cell proliferation. In this study, in vitro tests (fibroblast cell compatibility and platelet adhesion) and an in vivo animal study were performed by using PPX deposited industrial-grade silicone sheets (IGS) and compared with medical-grade silicone ones (MS), which were commonly manufactured into catheters or drainage tubes in clinical use. The results reveal that PPX deposited at high ωp or high fp, in comparison with MS, exhibit better cell proliferation and clearly shows less cell adhesion regardless of ωp and fp. PPX also exhibit a comparatively lower level of platelet adhesion than MS. In the animal study, PPX-coated IGS result in similar local tissue responses at 3, 7 and 28 days (short-term) and 84 days (long-term) after subcutaneous implantation the abdominal wall of rodents compared with respective responses to MS. These results suggest that PPX-coated industrial-grade silicone is one alternative to high cost medical-grade silicone.

  3. Image analysis of blood platelets adhesion.

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    Krízová, P; Rysavá, J; Vanícková, M; Cieslar, P; Dyr, J E

    2003-01-01

    Adhesion of blood platelets is one of the major events in haemostatic and thrombotic processes. We studied adhesion of blood platelets on fibrinogen and fibrin dimer sorbed on solid support material (glass, polystyrene). Adhesion was carried on under static and dynamic conditions and measured as percentage of the surface covered with platelets. Within a range of platelet counts in normal and in thrombocytopenic blood we observed a very significant decrease in platelet adhesion on fibrin dimer with bounded active thrombin with decreasing platelet count. Our results show the imperative use of platelet poor blood preparations as control samples in experiments with thrombocytopenic blood. Experiments carried on adhesive surfaces sorbed on polystyrene showed lower relative inaccuracy than on glass. Markedly different behaviour of platelets adhered on the same adhesive surface, which differed only in support material (glass or polystyrene) suggest that adhesion and mainly spreading of platelets depends on physical quality of the surface. While on polystyrene there were no significant differences between fibrin dimer and fibrinogen, adhesion measured on glass support material markedly differed between fibrin dimer and fibrinogen. We compared two methods of thresholding in image analysis of adhered platelets. Results obtained by image analysis of spreaded platelets showed higher relative inaccuracy than results obtained by image analysis of platelets centres and aggregates.

  4. Enhanced platelet adhesion in essential thrombocythemia after in vitro activation

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    Andreas C. Eriksson

    2010-06-01

    Full Text Available Objective: Essential thrombocythemia (ET is a chronic myeloproliferative disorder characterized by elevated platelet counts and increased risk of thrombosis. Ex vivo data suggest increased platelet reactivity in agreement with the increased thrombosis risk, while in vitro tests often detect decreased platelet activity. The present study aimed to investigate adhesion of ET-platelets in vitro, which is an aspect of platelet function that has been addressed in only a few studies on ET patients. Material and Methods: The study included 30 ET patients and 14 healthy controls. Platelet adhesion was measured with a static platelet adhesion assay. Results: The main finding was that ET-platelets were more readily activated by adhesion-inducing stimuli in vitro than control platelets. This was particularly evident in elderly patients and when using multiple stimuli, such as surfaces of collagen or fibrinogen combined with addition of adenosine 5’-diphosphate or ristocetin. Such multiple stimuli resulted in adhesion above the control mean +2 standard deviations for approximately 50% of the patients.Conclusion: The results are in accordance with the concept of increased platelet activity in ET, but opposite to most other in vitro studies. We suggest that the conditions in the adhesion assay might mimic the in vivo situation regarding the presence of chronic platelet activation.

  5. Platelet Function Tests

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    ... be limited. Home Visit Global Sites Search Help? Platelet Function Tests Share this page: Was this page helpful? ... their patients by ordering one or more platelet function tests. Platelet function testing may include one or more of ...

  6. Effect of platelet age on adhesiveness to collagen and platelet surface charge

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    Castellan, R.M.; Steiner, M.

    1976-11-30

    Adhesion to collagen was investigated as a function of platelet age in rat platelets. Platelet adherence was measured using EDTA-containing platelet- rich plasma which was added to preparations of collagen fibers clamped between magnetic stirrers by recording changes in light transmission. The plot of light transmission versus logarithm of time was linear and allowed calculation of a slope factor which related to the rate of adherence. Neither the amount of collagen nor the platelet count were limiting in the test. Young platelet populations (less than or equal to 1 day old) were obtained during the recovery phase from immune induced thrombocytopenia. Old platelet populations were prepared by blocking thrombopoiesis with cyclophosphamide. Young platelets did not differ significantly from randomly aged platelets in this function. The electrophoretic mobility of platelets was not affected by their age.

  7. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

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    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA) State Univ. of New York, Buffalo (USA))

    1987-11-01

    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of ({sup 3}H)serotonin, or alter the dose-responsive binding of {sup 125}I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF.

  8. The expression levels of platelet adhesive receptors in PRP derived platelet concentrates during storage

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    Fatemeh Nassaji

    2016-04-01

    Full Text Available Background: Major platelet adhesive receptors that contribute significantly to thrombus formation include platelet receptor glycoprotein Ibα (GPIbα of the GPIb-IX-V complex and platelet glycoprotein VI (GPVI. GPIbα plays a crucial role in platelet tethering to sub-endothelial matrix, which initiates thrombus formation at arterial shear rates, whereas GPVI is critically involved in platelets firm adhesion to the site of injury regardless of shear condition. During storage, platelets experience some changes that deleteriously affect the expression levels of platelet receptors, which in turn can alter platelet functional behaviors. Considering the important roles of GPIbα and GPVI in platelet adhesion, it seems that any dramatic changes in the expression levels of these receptors can influence adhesive function of transfused platelets. Thereby examining GPIbα and GPVI expression during the storage of platelet concentrates may provide some useful information about the functional quality of these products after transfusion. Methods: In our experimental study, 5 PRP-platelet concentrates were randomly obtained from Iranian Blood Transfusion Organization (IBTO. All the platelet products met the standard quality assessment based on AABB (American Association of Blood Banks guidelines. Washed platelets were subjected to flowcytometry analysis for the evaluation of GPIbα and GPVI receptor expression in day 1, 3 and 5 after storage. Data were presented as mean fluorescence intensity (MFI and analyzed by Kruskal-Wallis test with Dunn’s multiple comparison test. Results: The GPIbα expression on first day (MFI=86±5.9 was reduced three days after storage (MFI= 69±6.9. The expression levels continued to reduce until day 5 in which GPIbα expression was markedly decreased to (MFI= 61±7.7 (P= 0.0094. GPVI expression on the days 1, 3 and 5 after storage were 20.6±3.3, 24±2.5 and 14±4.9, respectively. The results showed a significant decrease of

  9. 血小板黏附的检测方法及临床应用%The Testing Method and Its Clinical Application of Platelet Adhesion

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    杜丽

    2014-01-01

    对血小板检测中血小板黏附试验的方法及检测方法及临床资料进行分析。黏附率增高见于高凝状态和血栓性疾病,黏附率降低见于 vWD、巨大血小板(BBS)综合征、血小板无力症、尿毒症、肝硬化及服用阿司匹林、双嘧达莫(潘生丁)、保泰松等药物以后,做好血小板黏附质量控制,对异常结果应结合临床资料进行分析。%The testing method and its clinical application of platelet adhesion to be investigated. Adhesion rate increasing is to be seen in hypercroagulable state and thrombotic diseases,while,reduced adhesion rate is to be seen in vWD,and Soulier(BBS) syndrome,Glanzmann’s disease, uremia,liver cirrhosis and after-taking aspirin,dipyridamole (dipyridamole),phenylbutazone. It is suggested to keep platelet quality in good and analyze the abnormal results combined with analyzing clinical treatment data.

  10. Platelet Function Tests in Bleeding Disorders.

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    Lassila, Riitta

    2016-04-01

    Functional disorders of platelets can involve any aspect of platelet physiology, with many different effects or outcomes. These include platelet numbers (thrombocytosis or thrombocytopenia); changes in platelet production or destruction, or capture to the liver (Ashwell receptor); altered adhesion to vascular injury sites and/or influence on hemostasis and wound healing; and altered activation or receptor functions, shape change, spreading and release reactions, procoagulant and antifibrinolytic activity. Procoagulant membrane alterations, and generation of thrombin and fibrin, also affect platelet aggregation. The above parameters can all be studied, but standardization and quality control of assay methods have been limited despite several efforts. Only after a comprehensive clinical bleeding assessment, including family history, information on drug use affecting platelets, and exclusion of coagulation factor, and tissue deficits, should platelet function testing be undertaken to confirm an abnormality. Current diagnostic tools include blood cell counts, platelet characteristics according to the cell counter parameters, peripheral blood smear, exclusion of pseudothrombocytopenia, whole blood aggregometry (WBA) or light transmission aggregometry (LTA) in platelet-rich plasma, luminescence, platelet function analysis (PFA-100) for platelet adhesion and deposition to collagen cartridges under blood flow, and finally transmission electron microscopy to exclude rare structural defects leading to functional deficits. The most validated test panels are included in WBA, LTA, and PFA. Because platelets are isolated from their natural environment, many simplifications occur, as circulating blood and interaction with vascular wall are omitted in these assays. The target to reach a highly specific platelet disorder diagnosis in routine clinical management can be exhaustive, unless needed for genetic counseling. The elective overall assessment of platelet function disorder

  11. Characterization of canine platelet adhesion to extracellular matrix proteins.

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    Pelagalli, Alessandra; Pero, Maria Elena; Mastellone, Vincenzo; Cestaro, Anna; Signoriello, Simona; Lombardi, Pietro; Avallone, Luigi

    2011-07-01

    Canine platelets have been extensively studied but little is known about specific aspects such as adhesion. Platelet adhesion is a critical step during haemostasis and thrombosis as well as during inflammatory and immunopathogenic responses. The aim of this study was to evaluate the adhesive properties of canine platelets using fibrinogen and collagen as substrates immobilized on plates. Adhesion was monitored for 120 min and the effect of adenosine 5'-diphosphate (ADP) was assayed. The results showed that canine platelets displayed good adhesion activity that was significantly time-dependent. Moreover, ADP was able to enhance platelet adhesion in a dose-dependent manner. The findings aid knowledge of the adhesion process and suggest a specific role of surface platelet receptors in mediating the interaction with extracellular matrix proteins.

  12. Platelet function tests: a comparative review

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    Paniccia R

    2015-02-01

    Full Text Available Rita Paniccia,1,2 Raffaella Priora,1,2 Agatina Alessandrello Liotta,2 Rosanna Abbate1,2 1Department of Experimental and Clinical Medicine, Thrombosis Center, University of Florence, Florence, Italy; 2Department of Heart and Vessels, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy Abstract: In physiological hemostasis a prompt recruitment of platelets on the vessel damage prevents the bleeding by the rapid formation of a platelet plug. Qualitative and/or quantitative platelet defects promote bleeding, whereas the high residual reactivity of platelets in patients on antiplatelet therapies moves forward thromboembolic complications. The biochemical mechanisms of the different phases of platelet activation – adhesion, shape change, release reaction, and aggregation – have been well delineated, whereas their complete translation into laboratory assays has not been so fulfilled. Laboratory tests of platelet function, such as bleeding time, light transmission platelet aggregation, lumiaggregometry, impedance aggregometry on whole blood, and platelet activation investigated by flow cytometry, are traditionally utilized for diagnosing hemostatic disorders and managing patients with platelet and hemostatic defects, but their use is still limited to specialized laboratories. To date, a point-of-care testing (POCT dedicated to platelet function, using pertinent devices much simpler to use, has now become available (ie, PFA-100, VerifyNow System, Multiplate Electrode Aggregometry [MEA]. POCT includes new methodologies which may be used in critical clinical settings and also in general laboratories because they are rapid and easy to use, employing whole blood without the necessity of sample processing. Actually, these different platelet methodologies for the evaluation of inherited and acquired bleeding disorders and/or for monitoring antiplatelet therapies are spreading and the study of platelet function is strengthening. In this review, well

  13. A novel dynamic layer-by-layer assembled nano-scale biointerface: functionality tests with platelet adhesion and aggregate morphology influenced by adenosine diphosphate.

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    Watson, Melanie G; Lopez, Juan M; Paun, Mihaela; Jones, Steven A

    2013-11-01

    An improved biointerface was developed, dynamic layer-by-layer self-assembly surface (d-LbL), and utilized as a biologically-active substrate for platelet adhesion and aggregation. Possible clinical applications for this research include improved anti-coagulation surfaces. This work demonstrated the functionality of d-LbL biointerfaces in the presence of platelet-rich-plasma (PRP) with the addition of 20 μM adenosine diphosphate (ADP), a thrombus activator. The surface morphology of the experimental control, plain PRP, was compared to PRP containing additional ADP (PRP + ADP) and resulted in an expected increase of platelet adhesions along the fibrinogen d-LbL substrate. The d-LbL process was used to coat glass slides with fibrinogen, Poly (sodium 4-styrene-sulfonate), and Poly (diallydimethlyammonium chloride). Slides were exposed to PRP under flow and static conditions with and without 20 μM of ADP. Fluorescence microscopy (FM), phase contrast microscopy (PCM), atomic force microscopy (AFM), and field emission-scanning electron microscopy (FE-SEM) were used to evaluate platelet adhesions under the influence of varied shear conditions. PCM images illustrated differences between the standard LbL and d-LbL substrates. FM images provided percent surface coverage values. For high-shear conditions, percent surface coverage values increased when using ADP whereas plain PRP exposure displayed no significant increase. AFM scans also displayed higher mean peak height values and unique surface characteristics for PRP + ADP as opposed to plain PRP. FE-SEM images revealed platelet adhesions along the biointerface and unique characteristics of the d-LbL surface. In conclusion, PRP + ADP was more effective at increasing platelet aggregation, especially under high shear conditions, providing further validation of the improved biointerface.

  14. PLATELET ADHESION TO POLYURETHANE UREA UNDER PULSATILE FLOW CONDITIONS

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    Navitsky, Michael A.; Taylor, Joshua O.; Smith, Alexander B.; Slattery, Margaret J.; Deutsch, Steven; Siedlecki, Christopher A.; Manning, Keefe B.

    2014-01-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s−1. The aim of the current work is to determine platelet adhesion properties to the polyurethane urea surface as a function of time varying shear exposure. A rotating disk system is used to study the influence of steady and pulsatile flow conditions (e.g. cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments retain the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk is rotated in platelet rich bovine plasma for two hours with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow is found to exponentially decay with increasing shear rate. Adhesion levels are found to depend upon peak platelet flux and shear rate regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices. PMID:24721222

  15. Platelet adhesion to polyurethane urea under pulsatile flow conditions.

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    Navitsky, Michael A; Taylor, Joshua O; Smith, Alexander B; Slattery, Margaret J; Deutsch, Steven; Siedlecki, Christopher A; Manning, Keefe B

    2014-12-01

    Platelet adhesion to a polyurethane urea surface is a precursor to thrombus formation within blood-contacting cardiovascular devices, and platelets have been found to adhere strongly to polyurethane surfaces below a shear rate of approximately 500 s(-1). The aim of the current work is to determine the properties of platelet adhesion to the polyurethane urea surface as a function of time-varying shear exposure. A rotating disk system was used to study the influence of steady and pulsatile flow conditions (e.g., cardiac inflow and sawtooth waveforms) for platelet adhesion to the biomaterial surface. All experiments were conducted with the same root mean square angular rotation velocity (29.63 rad/s) and waveform period. The disk was rotated in platelet-rich bovine plasma for 2 h, with adhesion quantified by confocal microscopy measurements of immunofluorescently labeled bovine platelets. Platelet adhesion under pulsating flow was found to decay exponentially with increasing shear rate. Adhesion levels were found to depend upon peak platelet flux and shear rate, regardless of rotational waveform. In combination with flow measurements, these results may be useful for predicting regions susceptible to thrombus formation within ventricular assist devices.

  16. Platelet adhesion studies on dipyridamole coated polyurethane surfaces

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    Aldenhoff Y. B.J.

    2003-06-01

    Full Text Available Surface modification of polyurethanes (PUs by covalent attachment of dipyridamole (Persantinregistered is known to reduce adherence of blood platelets upon exposure to human platelet rich plasma (PRP. This effect was investigated in further detail. First platelet adhesion under static conditions was studied with four different biomaterial surfaces: untreated PU, PU immobilised with conjugate molecule 1, PU immobilised with conjugate molecule 2, and PU immobilised with conjugate molecule 3. In PU immobilised with 1 dipyridamole is directly linked to the surface, in PU immobilised with 2 there is a short hydrophilic spacer chain in between the surface and the dipyridamole, while conjugate molecule 3 is merely the spacer chain. Scanning electron microscopy (SEM was used to characterise platelet adhesion from human PRP under static conditions, and fluorescence imaging microscopy was used to study platelet adhesion from whole blood under flow. SEM experiments encompassed both density measurements and analysis of the morphology of adherent platelets. In the static experiments the surface immobilised with 2 showed the lowest platelet adherence. No difference between the three modified surfaces emerged from the flow experiments. The surfaces were also incubated with washed blood platelets and labeled with Oregon-Green Annexin V. No capture of Oregon-Green Annexin V was seen, implying that the adhered platelets did not expose any phosphatidyl serine at their exteriour surface.

  17. Heparanase expression upregulates platelet adhesion activity and thrombogenicity

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    Österholm, Cecilia; Zhang, Xiao; Hedin, Ulf; Vlodavsky, Israel; Li, Jin-Ping

    2016-01-01

    Heparanase is an endo-glucuronidase that specifically cleaves heparan sulfate (HS) and heparin polysaccharides. The enzyme is expressed at low levels in normal tissues, but is often upregulated under pathological conditions such as cancer and inflammation. Normal human platelets express exceptionally high levels of heparanase, but the functional consequences of this feature remain unknown. We investigated functional roles of heparanase by comparing the properties of platelets expressing high (Hpa-tg) or low (Ctr) levels of heparanase. Upon activation, Hpa-tg platelets exhibited a much stronger adhesion activity as compared to Ctr platelets, likely contributing to a higher thrombotic activity in a carotid thrombosis model. Furthermore, we found concomitant upregulated expression of both heparanase and CD62P (P-selectin) upon activation of mouse and human platelets. As platelets play important roles in tumor metastasis, these findings indicate contribution of the platelet heparanase to hyper-thrombotic conditions often seen in patients with metastatic cancer. PMID:27129145

  18. Platelet adhesion onto segmented polyurethane surfaces modified by carboxybetaine.

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    Yuan, J; Zhang, J; Zhou, J; Yuan, Y L; Shen, J; Lin, S C

    2003-01-01

    Polyurethanes are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for more demanding applications. Surface modification is an effective way to improve the hemocompatibility for biomaterials. The purpose of present study was to synthesize a novel nonthrombogenic biomaterial by modifying the surface of polyurethane with Zwitterions of carboxybetaine monomer. The films of polyurethane were grafted with two kinds of carboxybetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-FT-IR spectra: a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of N,N-dimethylethylethanolamine (DMEA) or 4-dimethylamino-1-butanol (DMBA) was allowed to react in toluene with isocyanate groups bound on surface. In the third step, carboxybetaines were formed in the surface through the ring-opening reaction between tertiary amine of DMEA or DMBA and beta-propiolactone (PL). It was characterized by ATR-FT-IR and XPS that the grafted surfaces were composed of carboxybetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. Platelet adhesion tests showed that films grafted carboxybetaine have good blood compatibility, as featured by the low platelet adhesion.

  19. A factor VIII-derived peptide enables von Willebrand factor (VWF)-binding of artificial platelet nanoconstructs without interfering with VWF-adhesion of natural platelets.

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    Haji-Valizadeh, Hassan; Modery-Pawlowski, Christa L; Sen Gupta, Anirban

    2014-05-01

    There is substantial clinical interest in synthetic platelet analogs for potential application in transfusion medicine. To this end, our research is focused on self-assembled peptide-lipid nanoconstructs that can undergo injury site-selective adhesion and subsequently promote site-directed active platelet aggregation, thus mimicking platelet's primary hemostatic actions. For injury site-selective adhesion, we have utilized a coagulation factor FVIII-derived VWF-binding peptide (VBP). FVIII binds to VWF's D'-D3 domain while natural platelet GPIbα binds to VWF's A1 domain. Therefore, we hypothesized that the VBP-decorated nanoconstructs will adhere to VWF without mutual competition with natural platelets. We further hypothesized that the adherent VBP-decorated constructs can enhance platelet aggregation when co-decorated with a fibrinogen-mimetic peptide (FMP). To test these hypotheses, we used glycocalicin to selectively block VWF's A1 domain and, using fluorescence microscopy, studied the binding of fluorescently labeled VBP-decorated nanoconstructs versus platelets to ristocetin-treated VWF. Subsequently, we co-decorated the nanoconstructs with VBP and FMP and incubated them with human platelets to study construct-mediated enhancement of platelet aggregation. Decoration with VBP resulted in substantial construct adhesion to ristocetin-treated VWF even if the A1-domain was blocked by glycocalicin. In comparison, such A1-blocking resulted in significant reduction of platelet adhesion. Without A1-blocking, the VBP-decorated constructs and natural platelets could adhere to VWF concomitantly. Furthermore, the constructs co-decorated with VBP and FMP enhanced active platelet aggregation. The results indicate significant promise in utilizing the FVIII-derived VBP in developing synthetic platelet analogs that do not interfere with VWF-binding of natural platelets but allow site-directed enhancement of platelet aggregation when combined with FMP.

  20. In vitro short-term platelet adhesion on various metals.

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    Tanaka, Yuta; Kurashima, Kazuya; Saito, Haruka; Nagai, Akiko; Tsutsumi, Yusuke; Doi, Hisashi; Nomura, Naoyuki; Hanawa, Takao

    2009-01-01

    The in vitro short-term platelet adhesion on various metals, as accelerated by the addition of Ca(2+), was evaluated in this study. Metals used for medical devices [an austenitic stainless steel, a cobalt (Co)-chromium (Cr)-molybdenum (Mo) alloy, a titanium (Ti)-6 aluminum (Al)-4 vanadium (V) alloy, a Ti-6Al-7 niobium (Nb) alloy, a Tinickel (Ni) alloy, and commercially pure Ti] were immersed into a platelet-rich plasma solution for 5 or 20 min, and platelet adhesion and aggregation on the surfaces were observed using a scanning electron microscope. The platelet adhesion level on each metal after 5 min of immersion in a platelet-rich plasma solution was the smallest in this order: stainless steel alloy alloy alloy alloy = Ti. The levels after 5 min of immersion were almost the same as those after 20 min of immersion. Platelet adhesion was minimal on stainless steel and Co-Cr-Mo alloy, which have a Cr(2)O(3)-containing passive surface oxide film, but was accelerated on Ti and Ti alloys having a TiO(2)-containing film. A Cr(2)O(3)-containing oxide film has a lower relative permittivity than a TiO(2)-containing film; it thus supports a larger electrostatic force than the latter, adsorbs more albumins, which work as inhibitory proteins, and inhibits platelet aggregation. Therefore, platelet adhesion and aggregation are controlled by the composition of the surface oxide film on a metal due to the relative permittivity of the metal, which influences the amount of adsorbed proteins.

  1. Role of dystrophins and utrophins in platelet adhesion process.

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    Cerecedo, Doris; Mondragón, Ricardo; Cisneros, Bulmaro; Martínez-Pérez, Francisco; Martínez-Rojas, Dalila; Rendón, Alvaro

    2006-07-01

    Platelets are crucial at the site of vascular injury, adhering to the sub-endothelial matrix through receptors on their surface, leading to cell activation and aggregation to form a haemostatic plug. Platelets display focal adhesions as well as stress fibres to contract and facilitate expulsion of growth and pro-coagulant factors contained in the granules and to constrict the clot. The interaction of F-actin with different actin-binding proteins determines the properties and composition of the focal adhesions. Recently, we demonstrated the presence of dystrophin-associated protein complex corresponding to short dystrophin isoforms (Dp71d and Dp71) and the uthophin gene family (Up400 and Up71), which promote shape change, adhesion, aggregation, and granule centralisation. To elucidate participation of both complexes during the platelet adhesion process, their potential association with integrin beta-1 fraction and the focal adhesion system (alpha-actinin, vinculin and talin) was evaluated by immunofluorescence and immunoprecipitation assays. It was shown that the short dystrophin-associated protein complex participated in stress fibre assembly and in centralisation of cytoplasmic granules, while the utrophin-associated protein complex assembled and regulated focal adhesions. The simultaneous presence of dystrophin and utrophin complexes indicates complementary structural and signalling mechanisms to the actin network, improving the platelet haemostatic role.

  2. Quantitative analysis of human platelet adhesions under a small-scale flow device.

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    Furukawa, Katsuko S; Nakamura, Keigo; Onimura, Yuji; Uchida, Masaki; Ito, Atsuo; Yamane, Takashi; Tamaki, Tamotsu; Ushida, Takashi; Tateishi, Tetsuya

    2010-04-01

    To realize real-time evaluation of human platelet adhesions onto material surfaces with small volumes of human platelet suspensions, we developed an apparatus consisting of a modified cone and plate-type viscometer, combined with an upright epi-fluorescence microscope. The apparatus allowed real-time evaluation of platelet-material interactions and the initial event of thrombus formation, using small platelet suspension volumes (7.5 microL) under shear flow conditions. To study the dynamic behavior of platelet-material interaction, we chose five representative opaque and transparent materials: acrylate resin (AC), polytetrafluoroethylene (PTFE), polyvynylchrolide (PVC), glass, and a monolayer of human normal umbilical cord vein endothelial cells (EC) on glass under shear flow conditions. The values of adhesiveness of human platelets to the test materials in descending order were as follows: AC > PTFE > PVC > glass > human EC. Under this new small-scale flow system, we could obtain highly reproducible data, which were comparable with results from a previously developed large-scale flow system. Therefore, the newly developed cone and plate-type rheometer is a useful instrument for testing and screening materials, and allows precise quantitative evaluation of human platelet adhesion.

  3. A physical description of the adhesion and aggregation of platelets

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    Chopard, Bastien; Latt, Jonas; Dubois, Frank; Yourassowsky, Catherine; Van Antwerpen, Pierre; Eker, Omer; Vanhamme, Luc; Perez-Morga, David; Courbebaisse, Guy; Boudjeltia, Karim Zouaoui

    2015-01-01

    The early stages of clot formation in blood vessels involve platelets adhesion-aggregation. Although these mechanisms have been extensively studied, gaps in their understanding still persist. We have performed detailed in-vitro experiments and developed a numerical model to better describe and understand this phenomenon. Unlike previous studies, we took into account both activated and non-activated platelets, as well as the 3D nature of the aggregation process. Our investigation reveals that blood albumin is a major parameter limiting platelet adhesion and aggregation. Our results also show that the well accepted Zydney-Colton shear-induced diffusivity is much too low to explain the observed deposition rate. Simulations are in very good agreement with observations and provide quantitative estimates of the adhesion and aggregation rates that are hard to measure experimentally.

  4. The Platelet and Platelet Function Testing in Liver Disease

    NARCIS (Netherlands)

    Hugenholtz, Greg G. C.; Porte, Robert J.; Lisman, Ton

    2009-01-01

    Patients who have liver disease commonly present with alterations in platelet number and function. Recent data have questioned the contribution of these changes to bleeding complications in these patients. Modern tests of platelet function revealed compensatory mechanisms for the decreased platelet

  5. Extracts from Tribulus species may modulate platelet adhesion by interfering with arachidonic acid metabolism.

    Science.gov (United States)

    Olas, Beata; Hamed, Arafa I; Oleszek, Wieslaw; Stochmal, Anna

    2015-01-01

    The present work was designed to study the effects of crude extracts from Tribulus pterocarpus, T. pentandrus and T. parvispinus on selected biological functions of human blood platelets in vitro. Platelet suspensions were pre-incubated with extracts from aerial parts of T. pterocarpus, T. pentandrus and T. parvispinus, at the final concentrations of 0.5, 5 and 50 µg/ml. Then, for platelet activation thrombin, was used. The effects of crude extracts from T. pterocarpus, T. pentandrus and T. parvispinus on adhesion of blood platelets to collagen were determined by method according to Tuszynski and Murphy. Arachidonic acid metabolism was measured by the level of thiobarbituric acid reactive substances (TBARS). In these studies we also compared the action of tested crude plant extracts with the effects of the polyphenolic fraction isolated from aerial parts of T. pterocarpus, which has antiplatelet and antioxidative properties. The performed assays demonstrated that the tested crude extract from T. pterocarpus and the phenolic fraction from T. pterocarpus might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of this tested extract and its phenolic fraction on adhesion of resting platelets and thrombin - stimulated platelets to collagen was found. We also observed that the crude extract from T. pterocarpus, like the polyphenolic fraction from T. pterocarpus reduced TBARS production in blood platelets. In the comparative studies, the tested crude extract from T. pterocarpus was not found to be more effective antiplatelet factor, than the polyphenolic fraction from this plant. The results obtained suggest that T. pterocarpus may be a promising source of natural compounds, valuable in the prevention of the enhanced activity of blood platelets in numerous cardiovascular diseases.

  6. Epinephrine enhances platelet-neutrophil adhesion in whole blood in vitro.

    NARCIS (Netherlands)

    Horn, N.A.; Anastase, D.M.; Hecker, K.E.; Baumert, J.H.; Robitzsch, T.; Rossaint, R.

    2005-01-01

    Previous studies showed that alpha- or beta-adrenoceptor stimulation by catecholamines influenced neutrophil function, cytokine liberation, and platelet aggregability. We investigated whether adrenergic stimulation with epinephrine also alters platelet-neutrophil adhesion. This might be of specific

  7. Epinephrine enhances platelet-neutrophil adhesion in whole blood in vitro.

    NARCIS (Netherlands)

    Horn, N.A.; Anastase, D.M.; Hecker, K.E.; Baumert, J.H.; Robitzsch, T.; Rossaint, R.

    2005-01-01

    Previous studies showed that alpha- or beta-adrenoceptor stimulation by catecholamines influenced neutrophil function, cytokine liberation, and platelet aggregability. We investigated whether adrenergic stimulation with epinephrine also alters platelet-neutrophil adhesion. This might be of specific

  8. Alcohol and polyphenolic grape extract inhibit platelet adhesion in flowing blood

    NARCIS (Netherlands)

    de Lange, DW; Scholman, WLG; Kraaijenhagen, RJ; Akkerman, JWN; van de Wiel, A

    2004-01-01

    Background Moderate and prolonged alcohol consumption has been associated with decreased cardiovascular morbidity and mortality. Inhibition of platelet function in suspension attributes to these effects. Whether alcohol, red wine, or polyphenolic grape extracts (PGE) inhibit platelet adhesion is not

  9. Homocysteine and its thiolactone-mediated modification of fibrinogen affect blood platelet adhesion.

    Science.gov (United States)

    Malinowska, Joanna; Olas, Beata

    2012-01-01

    Homocysteine (Hcys) and homocysteine thiolactone (HTL) concentrations in organism are correlated with a number of serious pathologies. In the literature, there are few papers describing studies on the effects of homocysteine on proteins that participate in blood coagulation and fibrinolysis in human. However, mechanisms involved in the relationship between hyperhomocysteinemia and hemostatic process are still unclear. The role of N- or S-homocysteinylation (induced by Hcys and its derivatives) of different hemostatic proteins, including fibrinogen is also still poorly known. The aim of this study was to establish the functional changes of the fibrinogen molecule induced by Hcys (at final doses of 10-100 µM) and the most reactive form of Hcys - its cyclic thioester, homocysteine thiolactone (0.1-1 µM), and to examine the effects of these changes on the capability of fibrinogen to interact with human blood platelets (by measuring the platelet adhesion). Our present results demonstrated that Hcys-treated fibrinogen in comparison with native molecule had a distinct capability to mediate platelet adhesion. Both, unstimulated and thrombin-activated platelets showed a reduced ability to adhere to Hcys-mediated fibrinogen. HTL (at all tested concentrations) had similar properties when we used thrombin-activated platelets. In conclusion, the results reported in this study could be useful for a better understanding of changes in hemostasis during hyperhomocysteinemia.

  10. Laboratory testing for platelet function disorders.

    Science.gov (United States)

    Israels, S J

    2015-05-01

    Platelet function testing is both complex and labor intensive. A stepwise approach to the evaluation of patients with suspected platelet disorders will optimize the use of laboratory resources, beginning with an appropriate clinical evaluation to determine whether the bleeding is consistent with a defect of primary hemostasis. Bleeding assessment tools, evaluation of platelet counts, and review of peripheral blood cell morphology can aid the initial assessment. For patients requiring further laboratory testing, platelet aggregometry, secretion assays, and von Willebrand factor assays are the most useful next steps and will direct further specialized testing including flow cytometry, electron microscopy, and molecular diagnostics. Guidelines and recommendations for standardizing platelet function testing, with a particular focus on light transmission aggregometry, are available and can provide a template for clinical laboratories in establishing procedures that will optimize diagnosis and assure quality results. This review outlines an approach to platelet function testing and reviews testing methods available to clinical laboratories.

  11. Mesoscopic Modeling of Blood Clotting: Coagulation Cascade and Platelets Adhesion

    Science.gov (United States)

    Yazdani, Alireza; Li, Zhen; Karniadakis, George

    2015-11-01

    The process of clot formation and growth at a site on a blood vessel wall involve a number of multi-scale simultaneous processes including: multiple chemical reactions in the coagulation cascade, species transport and flow. To model these processes we have incorporated advection-diffusion-reaction (ADR) of multiple species into an extended version of Dissipative Particle Dynamics (DPD) method which is considered as a coarse-grained Molecular Dynamics method. At the continuum level this is equivalent to the Navier-Stokes equation plus one advection-diffusion equation for each specie. The chemistry of clot formation is now understood to be determined by mechanisms involving reactions among many species in dilute solution, where reaction rate constants and species diffusion coefficients in plasma are known. The role of blood particulates, i.e. red cells and platelets, in the clotting process is studied by including them separately and together in the simulations. An agonist-induced platelet activation mechanism is presented, while platelets adhesive dynamics based on a stochastic bond formation/dissociation process is included in the model.

  12. Inhibition of blood platelet adhesion and secretion by different phenolics from Yucca schidigera Roezl. bark.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara; Stochmal, Anna; Oleszek, Wieslaw

    2005-02-01

    Yucca schidigera is a plant that grows in Mexico, and it has a very high level of saponins and phenolic compounds with antioxidant action. The products of Y. schidigera are used as food additives and have a generally recognized as safe label. This study investigated the antiplatelet mechanisms of four phenolic compounds. We investigated antiplatelet mechanisms of the phenolic compounds trans-3,4',5-trihydroxystilbene (trans-resveratrol), trans-3,3',5,5'-tetrahydroxy-4'-methoxystilbene, and yuccaols A and C that had been isolated from the bark of Y. schidigera by studying their effects on the first step of platelet activation, i.e., platelet adhesion to collagen and fibrinogen. The effects of these compounds on the release of adenine nucleotides, proteins, and beta-N-acetyl-glycosaminidase (a marker of lysosomal secretion) from blood platelets activated by thrombin were also studied. These different phenolic compounds (1 to 25 microg/mL) and their extracts decreased platelet adhesion and secretion. Resveratrol and yucca extract were more reactive in decreasing these processes than were other tested phenolic compounds.

  13. Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study

    Directory of Open Access Journals (Sweden)

    Hedbäck Bo

    2009-06-01

    Full Text Available Abstract Background Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effects of ASA and clopidogrel. The adhesion assay measures several aspects of platelet adhesion simultaneously, which increases the probability of finding conditions sensitive for anti-platelet treatment. Methods With a randomised cross-over design we evaluated the anti-platelet effects of ASA combined with clopidogrel as well as monotherapy with either drug alone in 29 patients with a recent acute coronary syndrome. Also, 29 matched healthy controls were included to evaluate intra-individual variability over time. Platelet function was measured by flow cytometry, serum thromboxane B2 (TXB2-levels and by static platelet adhesion to different protein surfaces. The results were subjected to Principal Component Analysis followed by ANOVA, t-tests and linear regression analysis. Results The majority of platelet adhesion measures were reproducible in controls over time denoting that the assay can monitor platelet activity. Adenosine 5'-diphosphate (ADP-induced platelet adhesion decreased significantly upon treatment with clopidogrel compared to ASA. Flow cytometric measurements showed the same pattern (r2 = 0.49. In opposite, TXB2-levels decreased with ASA compared to clopidogrel. Serum TXB2 and ADP-induced platelet activation could both be regarded as direct measures of the pharmacodynamic effects of ASA and clopidogrel respectively. Indirect pharmacodynamic measures such as adhesion to albumin induced by various soluble activators as well as SFLLRN

  14. Platelet Endothelial Cell Adhesion Molecule 1 (PECAM-1/CD31): A Multifunctional Vascular Cell Adhesion Molecule.

    Science.gov (United States)

    Delisser, H M; Baldwin, H S; Albelda, S M

    1997-08-01

    PECAM-1/CD31 is a member of the immunoglobulin gene superfamily found on platelets, leukocytes, and endothelial cells, where it concentrates at cell-cell borders. It has been shown to both mediate cell-cell adhesion through homophilic and heterophilic interactions and to transduce intracellular signals that upregulate the function of integrins on leukocytes. Its cellular distribution and ability to mediate adhesive and signaling phenomena suggested that PECAM-1 was a multifunctional vascular cell adhesion molecule involved in leukocyte-endothelial and endothelial-endothelial interactions. These initial suggestions have been largely confirmed as recent studies have implicated PECAM-1 in the inflammatory process and in the formation of blood vessels. As our understanding of the molecular and functional properties of PECAM-1 grows, new insights will be gained that may have therapeutic implications for cardiovascular development and disease. (Trends Cardiovasc Med 1997;7:203-210). © 1997, Elsevier Science Inc.

  15. Platelet and endothelial adhesion on fluorosurfactant polymers designed for vascular graft modification.

    Science.gov (United States)

    Tang, Chad; Kligman, Faina; Larsen, Coby C; Kottke-Marchant, Kandice; Marchant, Roger E

    2009-02-01

    A prominent failure mechanism of small diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts is platelet-mediated thrombosis. We have designed a surface modification for ePTFE consisting of a self-assembling fluorosurfactant polymer (FSP) bearing biologically active ligands, including adhesive peptides and polysaccharide moieties. The goal of this biomimetic construct is to improve graft hemocompatibility by promoting rapid surface endothelialization, whereas minimizing platelet adhesion. Here we present a direct comparison of platelet and endothelial cell (EC) adhesion to FSPs containing one of three cell-adhesion peptides: cyclic Arg-Gly-Asp-D-Phe-Glu (cRGD), cyclic *Cys-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys* (cRRE, *denotes disulfide bond cyclization), linear Gly-Arg-Gly-Asp-Ser-Pro-Ala (RGD), or a polysaccharide moiety: oligomaltose (M-7), later designed to prevent nonspecific protein adhesion. Measurements of soluble peptide-integrin binding indicated that cRRE exhibits very low affinity for the alpha(IIb)beta(3) platelet fibrinogen receptor. Static and dynamic adhesion of washed, activated platelets on FSP-modified surfaces revealed that M-7 and cRRE promote significantly less platelet adhesion compared to RGD and cRGD FSPs, whereas EC adhesion was similar on all peptide FSPs and minimal on M-7 FSP. These results illustrate the potential for ligands presented in a FSP surface modification to selectively adhere ECs with limited platelet attachment.

  16. Platelet adhesion from shear blood flow is controlled by near-wall rebounding collisions with erythrocytes.

    Science.gov (United States)

    Tokarev, A A; Butylin, A A; Ataullakhanov, F I

    2011-02-16

    The efficacy of platelet adhesion in shear flow is known to be substantially modulated by the physical presence of red blood cells (RBCs). The mechanisms of this regulation remain obscure due to the complicated character of platelet interactions with RBCs and vascular walls. To investigate this problem, we have created a mathematical model that takes into account shear-induced transport of platelets across the flow, platelet expulsion by the RBCs from the near-wall layer of the flow onto the wall, and reversible capture of platelets by the wall and their firm adhesion to it. This model analysis allowed us to obtain, for the first time to our knowledge, an analytical determination of the platelet adhesion rate constant as a function of the wall shear rate, hematocrit, and average sizes of platelets and RBCs. This formula provided a quantitative description of the results of previous in vitro adhesion experiments in perfusion chambers. The results of the simulations suggest that under a wide range of shear rates and hematocrit values, the rate of platelet adhesion from the blood flow is mainly limited by the frequency of their near-wall rebounding collisions with RBCs. This finding reveals the mechanism by which erythrocytes physically control platelet hemostasis.

  17. The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors

    Directory of Open Access Journals (Sweden)

    Gianni Francesco Guidetti

    2012-01-01

    Full Text Available Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.

  18. Extracts from Trifolium pallidum and Trifolium scabrum aerial parts as modulators of blood platelet adhesion and aggregation.

    Science.gov (United States)

    Kolodziejczyk-Czepas, Joanna; Olas, Beata; Malinowska, Joanna; Wachowicz, Barbara; Szajwaj, Barbara; Kowalska, Iwona; Oleszek, Wieslaw; Stochmal, Anna

    2013-01-01

    A growing number of reports indicate that some species of clover (Trifolium) may have remarkable medical importance; however, the effects of these plants on blood platelets and hemostasis are inadequately recognized. This work was designed to study the effects of Trifolium pallidum and Trifolium scabrum extracts on the functions of human blood platelets in vitro. Platelet suspensions were preincubated with extracts from aerial parts of T. pallidum (phenolic fraction and clovamide fraction) and T. scabrum (phenolic fraction) at the final concentrations of 12.5, 25, and 50 µg/ml. Then, for platelet activation thrombin (0.1 U/ml), thrombin receptor activating peptide (TRAP; 20 µM), or adenosine diphosphate (ADP; 1 µM) were used. The effects of Trifolium extracts on adhesion of blood platelets to fibrinogen and collagen were determined by enzyme-linked immunosorbent assay (ELISA) method. Platelet aggregation was monitored on a dual-channel Chronolog aggregometer. In these studies, we also compared the action of tested plant extracts with the effects of another antiplatelet plant-derived compound - resveratrol (3,4',5-trihydroxystilbene). The performed assays demonstrated that the tested extracts might influence the platelet functions in vitro. The inhibitory, concentration-dependent effects of all tested extracts on adhesion of thrombin-stimulated platelets to collagen was found. Both extracts from T. pallidum and from T. scabrum reduced the thrombin-induced platelet adhesion to fibrinogen. Furthermore, in the presence of all three extracts, the platelet aggregation induced by thrombin was slightly inhibited. Our results also indicate that the tested plant extracts (at the highest concentrations used of 50 µg/ml), similar to purified resveratrol, inhibit selected steps of platelet activation stimulated by both proteolytic (thrombin) and nonproteolytic agonists (TRAP or ADP). In the comparative studies, T. pallidum and T. scabrum extracts was not found

  19. Biodegradable electrospun nanofibers coated with platelet-rich plasma for cell adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Diaz-Gomez, Luis [Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15872 Santiago de Compostela (Spain); Instituto de Ortopedia y Banco de Tejidos Musculoesqueléticos, Universidad de Santiago de Compostela, 15872 Santiago de Compostela (Spain); Alvarez-Lorenzo, Carmen, E-mail: carmen.alvarez.lorenzo@usc.es [Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15872 Santiago de Compostela (Spain); Concheiro, Angel [Departamento de Farmacia y Tecnología Farmacéutica, Facultad de Farmacia, Universidad de Santiago de Compostela, 15872 Santiago de Compostela (Spain); Silva, Maite [Instituto de Ortopedia y Banco de Tejidos Musculoesqueléticos, Universidad de Santiago de Compostela, 15872 Santiago de Compostela (Spain); Dominguez, Fernando [Fundación Publica Galega de Medicina Xenómica, Santiago de Compostela (Spain); Sheikh, Faheem A.; Cantu, Travis; Desai, Raj; Garcia, Vanessa L. [Department of Chemistry, University of Texas Pan American, Edinburg, TX 78541 (United States); Macossay, Javier, E-mail: jmacossay@utpa.edu [Department of Chemistry, University of Texas Pan American, Edinburg, TX 78541 (United States)

    2014-07-01

    Biodegradable electrospun poly(ε-caprolactone) (PCL) scaffolds were coated with platelet-rich plasma (PRP) to improve cell adhesion and proliferation. PRP was obtained from human buffy coat, and tested on human adipose-derived mesenchymal stem cells (MSCs) to confirm cell proliferation and cytocompatibility. Then, PRP was adsorbed on the PCL scaffolds via lyophilization, which resulted in a uniform sponge-like coating of 2.85 (S.D. 0.14) mg/mg. The scaffolds were evaluated regarding mechanical properties (Young's modulus, tensile stress and tensile strain), sustained release of total protein and growth factors (PDGF-BB, TGF-β1 and VEGF), and hemocompatibility. MSC seeded on the PRP–PCL nanofibers showed an increased adhesion and proliferation compared to pristine PCL fibers. Moreover, the adsorbed PRP enabled angiogenesis features observed as neovascularization in a chicken chorioallantoic membrane (CAM) model. Overall, these results suggest that PRP–PCL scaffolds hold promise for tissue regeneration applications. - Highlights: • Platelet-rich plasma (PRP) can be adsorbed on electrospun fibers via lyophilization. • PRP coating enhanced mesenchymal stem cell adhesion and proliferation on scaffolds. • PRP-coated scaffolds showed sustained release of growth factors. • Adsorbed PRP provided angiogenic features. • PRP-poly(ε-caprolactone) scaffolds hold promise for tissue regeneration applications.

  20. P-selectin-mediated platelet adhesion promotes the metastasis of murine melanoma cells.

    Science.gov (United States)

    Qi, Cui-Ling; Wei, Bo; Ye, Jie; Yang, Yang; Li, Bin; Zhang, Qian-Qian; Li, Jiang-Chao; He, Xiao-Dong; Lan, Tian; Wang, Li-Jing

    2014-01-01

    Studies have indicated that the aggregation of activated platelets with cancer cells facilitates tumor metastasis; the adhesion molecule P-selectin may be an important mediator of this process, but the detailed mechanism is unclear. In the current study, we established a B16F10 (B16) cell metastatic model in P-selectin knockout (P-sel-/-) mice to determine the effect of P-selectin-mediated platelet adhesion on metastasis. Compared with C57 mice, P-sel-/- mice developed fewer metastatic foci, and cell proliferation within the metastatic tumors was inhibited by P-selectin deficiency. The platelet refusion assay demonstrated that mice with P-sel-/- platelets developed fewer lung metastatic foci (PP-selectin deficiency inhibited the metastasis of B16 cells and that wild-type platelet refusion reversed this inhibition. The P-selectin-mediated interaction between platelets and B16 cells promoted angiogenesis by up-regulating VEGF.

  1. Blood flow simulation on a role for red blood cells in platelet adhesion

    Science.gov (United States)

    Shimizu, Kazuya; Sugiyama, Kazuyasu; Takagi, Shu

    2016-11-01

    Large-scale blood flow simulations were conducted and a role for red blood cells in platelet adhesion was discussed. The flow conditions and hematocrit values were set to the same as corresponding experiments, and the numerical results were compared with the measurements. Numerical results show the number of platelets adhered on the wall is increased with the increase in hematocrit values. The number of adhered platelets estimated from the simulation was approximately 28 (per 0.01 square millimeter per minute) for the hematocrit value of 20%. These results agree well with the experimental results qualitatively and quantitatively, which proves the validity of the present numerical model including the interaction between fluid and many elastic bodies and the modeling of platelet adhesion. Numerical simulation also reproduces the behavior of red blood cells in the blood flow and their role in platelet adhesion. Red blood cells deform to a flat shape and move towards channel center region. In contrast, platelets are pushed out and have many chances to contact with the wall. As a result, the large number of adhered platelets is observed as hematocrit values becomes high. This result indicates the presence of red blood cells plays a crucial role in platelet adhesion.

  2. Platelet adhesion studies on nanostructured poly(lactic-co-glycolic-acid)-carbon nanotube composite.

    Science.gov (United States)

    Koh, Li Buay; Rodriguez, Isabel; Zhou, Jijie

    2008-08-01

    Design of blood-compatible surfaces is required to minimize platelet-surface interactions and increase the thromboresistance of foreign surfaces. Poly(lactic-co-glycolic-acid)-carbon nanotube (PLGA-CNT) composite is studied as a building material to fabricate artificial blood prostheses. This nanocomposite-based biomaterial is prepared by an electrostatic Layer-by-Layer (LbL) deposition technique, in which layers of CNTs are adsorbed onto a PLGA film. Before incubation in nonstimulated platelet-rich plasma (PRP) for platelet studies, fibrinogen is immobilized on PLGA-CNT composite. Interactions between the plasma proteins, e.g. fibrinogen and PRP, are investigated on the prepared PLGA-CNT composite. Contact angle measurements on the PLGA-CNT composite displayed a good resistance of platelets adhesion on a hydrophilic surface with an angle of 64.94 degrees as compared to pristine PLGA control with an angle of 93.43 degrees . A significant reduction of adhesion is observed on the PLGA-CNT composite, as well as the absence of platelet activation. On the contrary, both platelet adhesion and activation are observed on control samples. We inferred this suppression in secretion of granule contents in the platelet by the presence of the CNTs that resulted in the absence of platelet activation and its subsequent inhibition in the release of adhesive membrane receptors on the PLGA-CNT composite.

  3. Platelet Adhesion to Podoplanin Under Flow is Mediated by the Receptor CLEC-2 and Stabilised by Src/Syk-Dependent Platelet Signalling

    Science.gov (United States)

    Pollitt, Alice Y.; Lowe, Kate; Latif, Arusa; Nash, Gerard B.

    2015-01-01

    Summary Platelet-specific deletion of CLEC-2, which signals through Src and Syk kinases, or global deletion of its ligand podoplanin results in blood-filled lymphatics during mouse development. Platelet-specific Syk deficiency phenocopies this defect, indicating that platelet activation is required for lymphatic development. In the present study, we investigated whether CLEC-2-podoplanin interactions could support platelet arrest from blood flow and whether platelet signalling is required for stable platelet adhesion to lymphatic endothelial cells (LECs) and recombinant podoplanin under flow. Perfusion of human or mouse blood over human LEC monolayers led to platelet adhesion and aggregation. Following αIIbβ3 blockade, individual platelets still adhered. Platelet binding occurred at venous but not arterial shear rates. There was no adhesion using CLEC-2-deficient blood or to vascular endothelial cells (which lack podoplanin). Perfusion of human blood over human Fc-podoplanin (hFcPDPN) in the presence of monoclonal antibody IV.3 to block FcγRIIA receptors led to platelet arrest at similar shear rates to those used on LECs. Src and Syk inhibitors significantly reduced global adhesion of human or mouse platelets to LECs and hFcPDPN. A similar result was seen using Syk-deficient mouse platelets. Reduced platelet adhesion was due to a decrease in the stability of binding. In conclusion, our data reveal that CLEC-2 is an adhesive receptor that supports platelet arrest to podoplanin under venous shear. Src/Syk-dependent signalling stabilises platelet adhesion to podoplanin, providing a possible molecular mechanism contributing to the lymphatic defects of Syk-deficient mice. PMID:25694214

  4. Platelet adhesion onto wettability gradient surfaces in the absence and presence of plasma proteins.

    Science.gov (United States)

    Lee, J H; Lee, H B

    1998-08-01

    A wettability gradient was prepared on lowdensity polyethylene (PE) sheets by treating them in air with a corona from a knife-type electrode the power of which increased gradually along the sample length. The PE surfaces oxidized gradually with the increasing corona power and a wettability gradient was created on the surfaces, as evidenced by the measurement of water contact angles, Fourier transform infrared spectroscopy in the attenuated total reflectance mode, and electron spectroscopy for chemical analysis. The wettability gradient surfaces prepared were used to investigate the adhesion behavior of platelets in the absence and presence of plasma proteins in terms of the surface hydrophilicity/hydrophobicity of polymeric materials. The platelets adhered to the wettability gradient surfaces along the sample length were counted and examined by scanning electron microscopy (SEM). It was observed that the platelet adhesion in the absence of plasma proteins increased gradually as the surface wettability increased along the sample length. The platelets adhered to the hydrophilic positions of the gradient surface also were more activated (possessed more pseudo pods as examined by SEM) than on the more hydrophobic ones. However, platelet adhesion in the presence of plasma proteins decreased gradually with the increasing surface wettability; the platelets adhered to the surface also were more activated on the hydrophobic positions of the gradient surface. This result is closely related to plasma protein adsorption on the surface. Plasma protein adsorption on the wettability gradient surface increased with the increasing surface wettability. More plasma protein adsorption on the hydrophilic positions of the gradient surface caused less platelet adhesion, probably due to platelet adhesion inhibiting proteins, such as high-molecular-weight kininogen, which preferably adsorbs onto the surface by the so-called Vroman effect. It seems that both the presence of plasma proteins

  5. P-selectin-mediated platelet adhesion promotes tumor growth.

    Science.gov (United States)

    Qi, Cuiling; Wei, Bo; Zhou, Weijie; Yang, Yang; Li, Bin; Guo, Simei; Li, Jialin; Ye, Jie; Li, Jiangchao; Zhang, Qianqian; Lan, Tian; He, Xiaodong; Cao, Liu; Zhou, Jia; Geng, Jianguo; Wang, Lijing

    2015-03-30

    Blood platelets foster carcinogenesis. We found that platelets are accumulated in human tumors. P-selectin deficiency and soluble P-selectin abolish platelet deposition within tumors, decreasing secretion of vascular endothelial growth factor and angiogenesis, thereby suppressing tumor growth. Binding of the P-selectin cytoplasmic tail to talin1 triggers the talin1 N-terminal head to interact with the β3 cytoplasmic tail. This activates αIIbβ3 and recruits platelets into tumors. Platelet infiltration into solid tumors occurs through a P-selectin-dependent mechanism.

  6. Ice Adhesion Testing Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Uses Evaluate and compare the relative performance of materials and surfcae coating based on their ability to aid in ice removal Test the effectiveness of de-icing...

  7. Influenza Virus Infection Induces Platelet-Endothelial Adhesion Which Contributes to Lung Injury.

    Science.gov (United States)

    Sugiyama, Michael G; Gamage, Asela; Zyla, Roman; Armstrong, Susan M; Advani, Suzanne; Advani, Andrew; Wang, Changsen; Lee, Warren L

    2015-12-04

    Lung injury after influenza infection is characterized by increased permeability of the lung microvasculature, culminating in acute respiratory failure. Platelets interact with activated endothelial cells and have been implicated in the pathogenesis of some forms of acute lung injury. Autopsy studies have revealed pulmonary microthrombi after influenza infection, and epidemiological studies suggest that influenza vaccination is protective against pulmonary thromboembolism; however, the effect of influenza infection on platelet-endothelial interactions is unclear. We demonstrate that endothelial infection with both laboratory and clinical strains of influenza virus increased the adhesion of human platelets to primary human lung microvascular endothelial cells. Platelets adhered to infected cells as well as to neighboring cells, suggesting a paracrine effect. Influenza infection caused the upregulation of von Willebrand factor and ICAM-1, but blocking these receptors did not prevent platelet-endothelial adhesion. Instead, platelet adhesion was inhibited by both RGDS peptide and a blocking antibody to platelet integrin α5β1, implicating endothelial fibronectin. Concordantly, lung histology from infected mice revealed viral dose-dependent colocalization of viral nucleoprotein and the endothelial marker PECAM-1, while platelet adhesion and fibronectin deposition also were observed in the lungs of influenza-infected mice. Inhibition of platelets using acetylsalicylic acid significantly improved survival, a finding confirmed using a second antiplatelet agent. Thus, influenza infection induces platelet-lung endothelial adhesion via fibronectin, contributing to mortality from acute lung injury. The inhibition of platelets may constitute a practical adjunctive strategy to the treatment of severe infections with influenza.IMPORTANCE There is growing appreciation of the involvement of the lung endothelium in the pathogenesis of severe infections with influenza virus. We have

  8. P-selectin-mediated platelet adhesion promotes the metastasis of murine melanoma cells.

    Directory of Open Access Journals (Sweden)

    Cui-Ling Qi

    Full Text Available Studies have indicated that the aggregation of activated platelets with cancer cells facilitates tumor metastasis; the adhesion molecule P-selectin may be an important mediator of this process, but the detailed mechanism is unclear. In the current study, we established a B16F10 (B16 cell metastatic model in P-selectin knockout (P-sel-/- mice to determine the effect of P-selectin-mediated platelet adhesion on metastasis. Compared with C57 mice, P-sel-/- mice developed fewer metastatic foci, and cell proliferation within the metastatic tumors was inhibited by P-selectin deficiency. The platelet refusion assay demonstrated that mice with P-sel-/- platelets developed fewer lung metastatic foci (P<0.01 with a lower microvascular density (MVD than mice with wild-type platelets. A co-culture model of platelets and B16 cells was utilized to determine the difference in VEGF concentration in the supernatants. The results demonstrated that the supernatant from the P-sel-/- platelet/B16 co-culture had a lower concentration of VEGF. Therefore, our findings indicated that P-selectin deficiency inhibited the metastasis of B16 cells and that wild-type platelet refusion reversed this inhibition. The P-selectin-mediated interaction between platelets and B16 cells promoted angiogenesis by up-regulating VEGF.

  9. Effect of curcumin on the adhesion of platelets to brain microvascular endothelial cells in vitro

    Institute of Scientific and Technical Information of China (English)

    Li ZHANG; Zhen-lun GU; Zheng-hong QIN; Zhong-qin LIANG

    2008-01-01

    Aim: To determine whether curcumin prevents the adhesion of platelets to brain microvascular endothelial cells (BMECs) cultured in vitro. Methods: [3H]Ad-chine-labeled platelets were incubated with BMECs to investigate the role of curcumin in the adhesion of platelets to BMECs. The number of platelets adher-ing to the BMECs monolayer was determined by liquid scintillation spectroscopy. The thrombin-induced expression of platelets P-selectin, glycoprotein Ⅱb (GPⅡb), and glycoprotein Ⅲa (GPⅢa) on the cell surface, was measured by flow cytometry. P-selectin mRNA levels of BMECs were determined by RT-PCR. The TNF-α-induced expressions of P-selectin and E-selectin on the surface of BMECs were determined by Western blotting. Results: The adhesion between thrombin-acti-vated platelets and normal BMECs, and that of TNF-α-activated BMECs and normal platelets were significantly increased, and this increase could be inhibited by curcumin (30-240 μmol/L) in a concentration-dependant manner. The platelets activated with thrombin and BMECs stimulated by TNF-α demonstrated an upregulated expressions of P-selectin and E-selectin, and this increase, when pretreated with curcumin for 30 min, could be restrained dose dependently. Curcumin also inhibited the increase of the GPⅡb/GPⅢa expression of thrombin-activated platelets in a concentration-dependent manner. Conclusion: Curcumin can inhibit the platelets to BMECs. This effect may be related to the decreased expressions of P-selectin, E-selectin, and GPⅡb/GPⅢa on platelets and BMECs.

  10. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress

    Science.gov (United States)

    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  11. The modulation of platelet adhesion and activation by chitosan through plasma and extracellular matrix proteins.

    Science.gov (United States)

    Lord, Megan S; Cheng, Bill; McCarthy, Simon J; Jung, MoonSun; Whitelock, John M

    2011-10-01

    Chitosan has been shown to promote initial wound closure events to prevent blood loss. Platelet adhesion and activation are crucial early events in these processes after traumatic bleeding leading to thrombus formation. Platelet adhesion to chitosan was found to be enhanced in the presence of adsorbed plasma and extracellular matrix proteins and was found to be primarily mediated by α(IIb)β(3) integrins, while α(2)β(1) integrins were found to be involved in platelet adhesion to collagen and perlecan. Platelets were found to be activated by chitosan, as shown by an increase in the expression of α(IIb)β(3) integrins and P-selectin, while the extent of activation was modulated by the presence of proteins including perlecan and fibrinogen. Collagen-coated chitosan was found to activate platelets to the same extent as either chitosan or collagen alone. These data support the role of plasma and extracellular matrix proteins in promoting chitosan mediated platelet adhesion and activation supporting the hypothesis that chitosan promotes wound healing via these interactions.

  12. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

    Science.gov (United States)

    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  13. Multiple integrin-ligand interactions synergize in shear-resistant platelet adhesion at sites of arterial injury in vivo

    DEFF Research Database (Denmark)

    Grüner, Sabine; Prostredna, Miroslava; Schulte, Valerie

    2003-01-01

    and alphaIIbbeta3. These were identified to be alpha5beta1 and/or alpha6beta1 as alphaIIbbeta3 inhibition abrogated platelet adhesion in beta1-null mice. We conclude that shear-resistant platelet adhesion on the injured vessel wall in vivo is a highly integrated process involving multiple integrin......Damage to the integrity of the vessel wall results in exposure of the subendothelial extracellular matrix (ECM), which triggers integrin-dependent adhesion and aggregation of platelets. The role of platelet beta1 integrins in these processes remains mostly undefined. Here, we demonstrate...... integrin on platelets in wild-type mice blocked aggregate formation and reduced platelet adhesion by 60.0%. Strikingly, alphaIIbbeta3 inhibition had a comparable effect in alpha2-null mice, demonstrating that other receptors mediate shear-resistant adhesion in the absence of functional alpha2beta1...

  14. Platelet and endothelial adhesion on fluorosurfactant polymers designed for vascular graft modification

    OpenAIRE

    Tang, Chad; Kligman, Faina; Larsen, Coby C.; KOTTKE-MARCHANT, KANDICE; Marchant, Roger E.

    2009-01-01

    A prominent failure mechanism of small-diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts is platelet-mediated thrombosis. We have designed surface modification for ePTFE consisting of a self-assembling fluorosurfactant polymer (FSP) bearing biologically active ligands, including adhesive peptides and polysaccharide moieties. The goal of this biomimetic construct is to improve graft hemocompatibility by promoting rapid surface endothelialization, while minimizing platelet adhes...

  15. P-Selectin-Mediated Adhesion between Platelets and Tumor Cells Promotes Intestinal Tumorigenesis in Apc(Min/+) Mice.

    Science.gov (United States)

    Qi, Cuiling; Li, Bin; Guo, Simei; Wei, Bo; Shao, Chunkui; Li, Jialin; Yang, Yang; Zhang, Qianqian; Li, Jiangchao; He, Xiaodong; Wang, Lijing; Zhang, Yajie

    2015-01-01

    Studies have indicated that platelets play an important role in tumorigenesis, and an abundance of platelets accumulate in the ovarian tumor microenvironment outside the vasculature. However, whether cancer cells recruit platelets within intestinal tumors and how they signal adherent platelets to enter intestinal tumor tissues remain unknown. Here, we unexpectedly found that large numbers of platelets were deposited within human colorectal tumor specimens using immunohistochemical staining, and these platelets were fully associated with tumor development. We further report the robust adhesion of platelet aggregates to tumor cells within intestinal tumors, which occurs via a mechanism that is dependent on P-selectin (CD62P), a cell adhesion molecule that is abundantly expressed on activated platelets. Using spontaneous intestinal tumor mouse models, we determined that the genetic deletion of P-selectin suppressed intestinal tumor growth, which was rescued by the infusion of wild-type platelets but not P-selectin(-/-) platelets. Mechanistically, platelet adhesion to tumor cells induced the secretion of vascular endothelial growth factor (VEGF) to promote angiogenesis and accelerate intestinal tumor cell proliferation. Our results indicate that the adherence of platelets to tumor cells could promote tumor growth and metastasis. By targeting this platelet-tumor cell interaction, recombinant soluble P-selectin may have therapeutic value for the treatment of intestinal tumors.

  16. Deposition of fibrinogen on the surface of in vitro thrombi prevents platelet adhesion.

    Science.gov (United States)

    Owaynat, Hadil; Yermolenko, Ivan S; Turaga, Ramya; Lishko, Valeryi K; Sheller, Michael R; Ugarova, Tatiana P

    2015-12-01

    The initial accumulation of platelets after vessel injury is followed by thrombin-mediated generation of fibrin which is deposited around the plug. While numerous in vitro studies have shown that fibrin is highly adhesive for platelets, the surface of experimental thrombi in vivo contains very few platelets suggesting the existence of natural anti-adhesive mechanisms protecting stabilized thrombi from platelet accumulation and continuous thrombus propagation. We previously showed that adsorption of fibrinogen on pure fibrin clots results in the formation of a nonadhesive matrix, highlighting a possible role of this process in surface-mediated control of thrombus growth. However, the deposition of fibrinogen on the surface of blood clots has not been examined. In this study, we investigated the presence of intact fibrinogen on the surface of fibrin-rich thrombi generated from flowing blood and determined whether deposited fibrinogen is nonadhesive for platelets. Stabilized fibrin-rich thrombi were generated using a flow chamber and the time that platelets spend on the surface of thrombi was determined by video recording. The presence of fibrinogen and fibrin on the surface of thrombi was analyzed by confocal microscopy using specific antibodies. Examination of the spatial distribution of two proteins revealed the presence of intact fibrinogen on the surface of stabilized thrombi. By manipulating the surface of thrombi to display either fibrin or intact fibrinogen, we found that platelets adhere to fibrin- but not to fibrinogen-coated thrombi. These results indicate that the fibrinogen matrix assembled on the outer layer of stabilized in vitro thrombi protects them from platelet adhesion.

  17. Surface characterization and platelet adhesion studies on fluorocarbons prepared by plasma-induced graft polymerization.

    Science.gov (United States)

    Lin, J C; Tiong, S L; Chen, C Y

    2000-01-01

    It is believed that the interactions between the biological environment and biomaterial surface are the key factors influencing its biocompatibility. Therefore, plasma processing, which can vary the surface properties without altering the bulk properties, has been considered as one of the important techniques for improving a materials' biocompatibility. In this investigation, plasma-induced grafting polymerization of vinylidene fluoride (VDF) and chlorotrifluoroethylene (CTFE), instead of direct plasma polymerization, was attempted with an aim to improve the substrate blood compatibility. Contact angle measurement indicated both fluorocarbon-grafted Pdyethylenes (PEs) are hydrophobic. Due to the additional fluorine and chlorine atoms on the CTFE chain, the PCTFE-grafted PE exhibited a higher hydrophobicity than the PVDF-grafted one. ESCA analysis has revealed that these two plasma-induced fluorocarbon deposits contain almost no CFx (x > 2) binding on the surface layer, indicating the grafting polymerization mainly follows the free radical mechanism instead of the molecule-highly-fragmented reaction steps commonly seen in the direct plasma polymerization treatment. In addition, ATR-FTIR has shown the surface chemical configuration of these PVDF- and PCTFE-grafted PEs to be very similar to those of the bulk samples of PVDF and PCTFE. The surface roughness decreased after oxygen plasma treatment and was further reduced by VDF and CTFE grafting polymerization. In vitro platelet adhesion testing indicated these two fluorocarbon grafted PEs are less platelet-activating than the nontreated PE control and oxygen plasma activated one.

  18. Chemical graft polymerization of sulfobetaine monomer on polyurethane surface for reduction in platelet adhesion.

    Science.gov (United States)

    Yuan, Jiang; Chen, Li; Jiang, Xuefeng; Shen, Jian; Lin, Sicong

    2004-11-25

    Surface modification is an effective way to improve the hemocompatibility and remain bulk properties of biomaterials. Recently, polymer tailored with zwitterions was found having good blood compatibility. In this study, the zwitterionic monomer of sulfobetaine was graft polymerized onto polyurethane (PU) surface in a three-step heterogenous system through the vinyl bonds of acrylic acid (AA) or hydroxyethyl methacrylate (HEMA), which was immobilized with hexamethylene diisocyanate (HDI) beforehand. First, PU was activated with isocyanate groups using HDI as coupling agent. Second, AA or HEMA was introduced through reaction of AA or HEMA with NCO groups bonded on PU surface. Last, zwitterionic monomer of sulfobetain was graft polymerized with vinyl group of AA or HEMA using AIBN as polymerization initiator. The reaction process was monitored with ATR-IR spectra and XPS spectra. Variation of graft yield with temperature and monomer feed concentration was investigated and feasible conditions were optimized. The wettability of films was investigated by water contact angle measurement and water absorbance. Platelet adhesion experiment was conducted as a preliminary test to confirm the improved blood compatibility of PU. The number of platelets adhering to PU decreased greatly comparing with the originals after 1 and 3 h of contact with human plate-rich plasma (PRP).

  19. Gelatin use impairs platelet adhesion during cardiac surgery

    NARCIS (Netherlands)

    Tabuchi, N; deHaan, J; Huet, RCGG; Boonstra, PW; vanOeveren, W

    1995-01-01

    Artificial colloids based on gelatin are used as plasma expander to replace donor blood products. In laboratory experiments, gelatin reduced both the velocity and extend of platelet agglutination by ristocetin, and only the agglutination velocity by polybrene (p These negative effects of gelatin on

  20. Antithrombin significantly influences platelet adhesion onto immobilized fibrinogen in an in-vitro system simulating low flow

    Directory of Open Access Journals (Sweden)

    Scharf Rüdiger E

    2006-10-01

    Full Text Available Abstract Background Adhesion of platelets onto immobilized fibrinogen is of importance in initiation and development of thrombosis. According to a recent increase in evidence of a multiple biological property of antithrombin, we evaluated the influence of antithrombin on platelet adhesion onto immobilized fibrinogen using an in-vitro flow system. Methods Platelets in anticoagulated whole blood (29 healthy blood donors were labelled with fluorescence dye and perfused through a rectangular flow chamber (shear rates of 13 s-1 to 1500 s-1. Platelet adhesion onto fibrinogen-coated slips was assessed using a fluorescence laser-scan microscope and compared to the plasma antithrombin activity. Additionally the effect of supraphysiological AT supplementation on platelets adhesion rate was evaluated. Results Within a first minute of perfusion, an inverse correlation between platelet adhesion and plasma antithrombin were observed at 13 s-1 and 50 s-1 (r = -0.48 and r = -0.7, p -1, within first minute have been found. An in-vitro supplementation of whole blood with antithrombin increased the antithrombin activity up to 280% and platelet adhesion rate reached about 65% related to the adhesion rate in a non-supplemented blood (1.25 ± 0.17 vs. 1.95 ± 0.4 p = 0.008, respectively. Conclusion It appears that antithrombin in a low flow system suppresses platelet adhesion onto immobilized fibrinogen independently from its antithrombin activity. A supraphysiological substitution of blood with antithrombin significantly reduces platelet adhesion rate. This inhibitory effect might be of clinical relevance.

  1. Calpain-controlled detachment of major glycoproteins from the cytoskeleton regulates adhesive properties of activated phosphatidylserine-positive platelets.

    Science.gov (United States)

    Artemenko, Elena O; Yakimenko, Alena O; Pichugin, Alexey V; Ataullakhanov, Fazly I; Panteleev, Mikhail A

    2016-02-15

    In resting platelets, adhesive membrane glycoproteins are attached to the cytoskeleton. On strong activation, phosphatidylserine(PS)-positive and -negative platelet subpopulations are formed. Platelet activation is accompanied by cytoskeletal rearrangement, although the glycoprotein attachment status in these two subpopulations is not clear. We developed a new, flow cytometry-based, single-cell approach to investigate attachment of membrane glycoproteins to the cytoskeleton in cell subpopulations. In PS-negative platelets, adhesive glycoproteins integrin αIIbβ3, glycoprotein Ib and, as shown for the first time, P-selectin were associated with the cytoskeleton. In contrast, this attachment was disrupted in PS-positive platelets; it was retained to some extent only in the small convex regions or 'caps'. It correlated with the degradation of talin and filamin observed only in PS-positive platelets. Calpain inhibitors essentially prevented the disruption of membrane glycoprotein attachment in PS-positive platelets, as well as talin and filamin degradation. With the suggestion that detachment of glycoproteins from the cytoskeleton may affect platelet adhesive properties, we investigated the ability of PS-positive platelets to resist shear-induced breakaway from the immobilized fibrinogen. Shear rates of 500/s caused PS-positive platelet breakaway, but their adhesion stability increased more than 10-fold after pretreatment of the platelets with calpain inhibitor. In contrast, the ability of PS-positive platelets to adhere to immobilized von Willebrand's factor at 100/s was low, but this was not affected by the preincubation of platelets with a calpain inhibitor. Our data suggest that calpain-controlled detachment of membrane glycoproteins is a new mechanism that is responsible for the loss of ability of the procoagulant platelets to resist detachment from thrombi by high shear stress.

  2. High Fat Diet Induces Adhesion of Platelets to Endothelium in Two Models of Dyslipidemia

    Directory of Open Access Journals (Sweden)

    Jaime Gonzalez

    2014-01-01

    Full Text Available Cardiovascular diseases (CVD represent about 30% of all global deaths. It is currently accepted that, in the atherogenic process, platelets play an important role, contributing to endothelial activation and modulation of the inflammatory phenomenon, promoting the beginning and formation of lesions and their subsequent thrombotic complications. The objective of the present work was to study using immunohistochemistry, the presence of platelets, monocytes/macrophages, and cell adhesion molecules (CD61, CD163, and CD54, in two stages of the atheromatous process. CF-1 mice fed a fat diet were used to obtain early stages of atheromatous process, denominated early stage of atherosclerosis, and ApoE−/− mice fed a fat diet were used to observe advanced stages of atherosclerosis. The CF-1 mice model presented immunostaining on endothelial surface for all three markers studied; the advanced atherosclerosis model in ApoE−/− mice also presented granular immunostaining on lesion thickness, for the same markers. These results suggest that platelets participate in atheromatous process from early stages to advance d stages. High fat diet induces adhesion of platelets to endothelial cells in vivo. These findings support studying the participation of platelets in the formation of atheromatous plate.

  3. High Fat Diet Induces Adhesion of Platelets to Endothelium in Two Models of Dyslipidemia

    Science.gov (United States)

    Gonzalez, Jaime; Donoso, Wendy; Díaz, Natalia; Albornoz, María Eliana; Huilcaman, Ricardo; Morales, Erik

    2014-01-01

    Cardiovascular diseases (CVD) represent about 30% of all global deaths. It is currently accepted that, in the atherogenic process, platelets play an important role, contributing to endothelial activation and modulation of the inflammatory phenomenon, promoting the beginning and formation of lesions and their subsequent thrombotic complications. The objective of the present work was to study using immunohistochemistry, the presence of platelets, monocytes/macrophages, and cell adhesion molecules (CD61, CD163, and CD54), in two stages of the atheromatous process. CF-1 mice fed a fat diet were used to obtain early stages of atheromatous process, denominated early stage of atherosclerosis, and ApoE−/− mice fed a fat diet were used to observe advanced stages of atherosclerosis. The CF-1 mice model presented immunostaining on endothelial surface for all three markers studied; the advanced atherosclerosis model in ApoE−/− mice also presented granular immunostaining on lesion thickness, for the same markers. These results suggest that platelets participate in atheromatous process from early stages to advance d stages. High fat diet induces adhesion of platelets to endothelial cells in vivo. These findings support studying the participation of platelets in the formation of atheromatous plate. PMID:25328689

  4. Development of a New Method for Platelet Function Test and Its Shearing Condition in Microfludic System

    Science.gov (United States)

    Lee, Hoyoon; Kim, Gyehyu; Choi, Seawhan; Shin, Sehyun; Korea University Department of Mechanical Engineering Team

    2015-11-01

    Platelet is a crucial blood cell on hemostasis. As platelet exposed to high shear stress, it can be activated showing morphological and functional changes to stop bleeding. When platelet is abnormal, there is high risk of cardiovascular diseases. Thus, quick and precise assay for platelet function is important in clinical treatment. In this study, we design a microfluidic system, which can test platelet function exposed with the stimulation of shear and agonists. The microfluidic system consists of three parts: 1) a shear mechanism with rotating stirrer; 2) multiple microchannels to flow samples and to stop; 3) camera-interfaced migration distance(MD) analyzing system. When sheared blood is driven by pressure through the microchannel, shear-activated platelets adhere to a collagen-coated surface, causing blood flow to significantly slow and eventually stop. As the micro-stirrer speed increases, MD decreases exponentially at first, but it increases beyond a critical rpm after all. These results are coincident with data measured by FACS flowcytometry. These results imply that the present system could quantitatively measure the degree of activation, aggregation and adhesion of platelets and that blood MD is potent index for measuring the shear-dependence of platelet function.

  5. Platelet adhesion and plasma protein adsorption control of collagen surfaces by He{sup +} ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Kurotobi, K. E-mail: kurotobi@postman.riken.go.jp; Suzuki, Y.; Nakajima, H.; Suzuki, H.; Iwaki, M

    2003-05-01

    He{sup +} ion implanted collagen-coated tubes with a fluence of 1 x 10{sup 14} ions/cm{sup 2} were exhibited antithrombogenicity. To investigate the mechanisms of antithrombogenicity of these samples, plasma protein adsorption assay and platelet adhesion experiments were performed. The adsorption of fibrinogen (Fg) and von Willebrand factor (vWf) was minimum on the He{sup +} ion implanted collagen with a fluence of 1 x 10{sup 14} ions/cm{sup 2}. Platelet adhesion (using platelet rich plasma) was inhibited on the He{sup +} ion implanted collagen with a fluence of 1 x 10{sup 14} ions/cm{sup 2} and was accelerated on the untreated collagen and ion implanted collagen with fluences of 1 x 10{sup 13}, 1 x 10{sup 15} and 1 x 10{sup 16} ions/cm{sup 2}. Platelet activation with washed platelets was observed on untreated collagen and He{sup +} ion implanted collagen with a fluence of 1 x 10{sup 14} ions/cm{sup 2} and was inhibited with fluences of 1 x 10{sup 13}, 1 x 10{sup 15} and 1 x 10{sup 16} ions/cm{sup 2}. Generally, platelets can react with a specific ligand inside the collagen (GFOGER sequence). The results of platelets adhesion experiments using washed platelets indicated that there were no ligands such as GFOGER on the He{sup +} ion implanted collagen over a fluence of 1 x 10{sup 13} ions/cm{sup 2}. On the 1 x 10{sup 14} ions/cm{sup 2} implanted collagen, no platelet activation was observed due to the influence of plasma proteins. >From the above, it is concluded that the decrease of adsorbed Fg and vWf caused the antithrombogenicity of He{sup +} ion implanted collagen with a fluence of 1 x 10{sup 14} ions/cm{sup 2} and that plasma protein adsorption took an important role repairing the graft surface.

  6. Platelet adhesive resistance of polyurethane surface grafted with zwitterions of sulfobetaine.

    Science.gov (United States)

    Jiang, Yuan; Qingfeng, Hou; Baolei, Liu; Jian, Shen; Sicong, Lin

    2004-07-01

    A possible approach to improve the blood compatibility of poly(etherurethane)s (PU) involves the covalent attachment of key molecular on its surface. Recently, polymer tailed with zwitterions was found having good blood compatibility. The purpose of present study was to design and synthesis a novel nonthrombogenic biomaterial by modifying the surface of poly(etherurethane) with zwitterions of sulfobetaine via HDI spacer. The films of polyurethane were grafted with sulfobetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate(DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra; a maximum number of free NCO group was obtained after a reaction time of 2.5 h. In the second step, the primary amine group of N,N-diethylethylenediamine (DEA) or N,N-dimethylethylenediamine (DMA) was allowed to react in toluene with isocyanate groups bound on surface. In the third step, two kinds of sulfobetaines were formed in the surface through the ring-opening reaction between tertiary amine of DMA or DEA and 1,3- propanesultone (PS). The reaction process was monitored with ATR-IR spectra and XPS spectra. The wettability of films was investigated by water contact angle measurement. A platelet adhesion experiment was conducted as a preliminary test to confirm the improved blood compatibility of PU. The number of platelets adhering to PU decreased greatly compared to original after 1 h and 3 h of contact with human plate-rich plasma.

  7. Platelet Function Tests: A Review of Progresses in Clinical Application

    Directory of Open Access Journals (Sweden)

    Jae-Lim Choi

    2014-01-01

    Full Text Available The major goal of traditional platelet function tests has been to screen and diagnose patients who present with bleeding problems. However, as the central role of platelets implicated in the etiology of arterial thrombotic diseases such as myocardial infarction and stroke became widely known, platelet function tests are now being promoted to monitor the efficacy of antiplatelet drugs and also to potentially identify patients at increased risk of thrombosis. Beyond hemostasis and thrombosis, an increasing number of studies indicate that platelets play an integral role in intercellular communication, are mediators of inflammation, and have immunomodulatory activity. As new potential biomarkers and technologies arrive at the horizon, platelet functions testing appears to take on a new aspect. This review article discusses currently available clinical application of platelet function tests, placing emphasis on essential characteristics.

  8. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  9. Platelet function testing: methods of assessment and clinical utility.

    LENUS (Irish Health Repository)

    Mylotte, Darren

    2012-02-01

    Platelets play a central role in the regulation of both thrombosis and haemostasis yet tests of platelet function have, until recently, been exclusively used in the diagnosis and management of bleeding disorders. Recent advances have demonstrated the clinical utility of platelet function testing in patients with cardiovascular disease. The ex vivo measurement of response to antiplatelet therapies (aspirin and clopidogrel), by an ever-increasing array of platelet function tests, is with some assays, predictive of adverse clinical events and thus, represents an emerging area of interest for both the clinician and basic scientist. This review article will describe the advantages and disadvantages of the currently available methods of measuring platelet function and discuss both the limitations and emerging data supporting the role of platelet function studies in clinical practice.

  10. Platelet function testing: methods of assessment and clinical utility.

    LENUS (Irish Health Repository)

    Mylotte, Darren

    2011-01-01

    Platelets play a central role in the regulation of both thrombosis and haemostasis yet tests of platelet function have, until recently, been exclusively used in the diagnosis and management of bleeding disorders. Recent advances have demonstrated the clinical utility of platelet function testing in patients with cardiovascular disease. The ex vivo measurement of response to antiplatelet therapies (aspirin and clopidogrel), by an ever-increasing array of platelet function tests, is with some assays, predictive of adverse clinical events and thus, represents an emerging area of interest for both the clinician and basic scientist. This review article will describe the advantages and disadvantages of the currently available methods of measuring platelet function and discuss both the limitations and emerging data supporting the role of platelet function studies in clinical practice.

  11. Losartan inhibits the adhesion of rat platelets to fibrillar collagen--a potential role of nitric oxide and prostanoids.

    Science.gov (United States)

    Matys, T; Chabielska, E; Pawlak, R; Kucharewicz, I; Buczko, W

    2000-12-01

    The aim of the study was to evaluate the effect of losartan on rat platelet adhesion to fibrillar collagen. Washed platelets were counted before and after 15 minutes incubation with collagen (50 microg/ml) and the percentage of adhering platelets was calculated as the index of their adhesion. When the platelets were incubated with collagen 40.8 +/- 0.3% of the platelets adhered. Losartan produced a dose dependent decrease in a number of adhering platelets both when the drug was administered to the animals ex vivo at doses of 3, 10 and 30 mg/kg (p < 0.01-0.001) or was added to the preparation of washed platelets in vitro in concentrations of 10(-8)-10(-5) M (p < 0.01-0.001). In the next step of the study we assessed the influence of L-NAME (10 mg/kg ex vivo, 30 microM in vitro) and indomethacin (2.5 mg/kg ex vivo, 30 microM in vitro) on the antiadhesive effect of losartan (10 mg/kg ex vivo, 10(-6) M in vitro). Blockade of nitric oxide synthase with L-NAME partially reversed the antiadhesive effect of losartan both ex vivo and in vitro. Indomethacin diminished the inhibitory effect of losartan on platelet adhesion when administered ex vivo, but it failed to modify this parameter when added to the suspension of platelets in vitro. In conclusion, losartan reduces platelet adhesion to fibrillar collagen in a dose-dependent manner. The observed action of losartan seems to be mediated mainly by endothelium- and platelet-derived nitric oxide.

  12. Platelet adhesion and degranulation induce pro-survival and pro-angiogenic signalling in ovarian cancer cells.

    Directory of Open Access Journals (Sweden)

    Karl Egan

    Full Text Available Thrombosis is common in ovarian cancer. However, the interaction of platelets with ovarian cancer cells has not been critically examined. To address this, we investigated platelet interactions in a range of ovarian cancer cell lines with different metastatic potentials [HIO-80, 59M, SK-OV-3, A2780, A2780cis]. Platelets adhered to ovarian cancer cells with the most significant adhesion to the 59M cell line. Ovarian cancer cells induced platelet activation [P-selectin expression] in a dose dependent manner, with the most significant activation seen in response to the 59M cell line. The platelet antagonists [cangrelor, MRS2179, and apyrase] inhibited 59M cell induced activation suggesting a P2Y12 and P2Y1 receptor mediated mechanism of platelet activation dependent on the release of ADP by 59M cells. A2780 and 59M cells potentiated PAR-1, PAR-4, and TxA2 receptor mediated platelet activation, but had no effect on ADP, epinephrine, or collagen induced activation. Analysis of gene expression changes in ovarian cancer cells following treatment with washed platelets or platelet releasate showed a subtle but valid upregulation of anti-apoptotic, anti-autophagy pro-angiogenic, pro-cell cycle and metabolic genes. Thus, ovarian cancer cells with different metastatic potential adhere and activate platelets differentially while both platelets and platelet releasate mediate pro-survival and pro-angiogenic signals in ovarian cancer cells.

  13. Association of membrane/lipid rafts with the platelet cytoskeleton and the caveolin PY14: participation in the adhesion process.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Maldonado-García, Deneb; Hernández-González, Enrique; Winder, Steve J

    2015-11-01

    Platelets are the most prominent elements of blood tissue involved in hemostasis at sites of blood vessel injury. Platelet cytoskeleton is responsible for their shape modifications observed during activation and adhesion to the substratum; therefore the interactions between cytoskeleton and plasma membrane are critical to modulate blood platelet functions. Several cytoskeletal components and binding partners, as well as enzymes that regulate the cytoskeleton, localize to membrane/lipid rafts (MLR) and regulate lateral diffusion of membrane proteins and lipids. Resting, thrombin-activated, and adherent human platelets were processed for biochemical studies including western-blot and immunprecipitation assays and confocal analysis were performed to characterize the interaction of MLR with the main cytoskeleton elements and β-dystroglycan as well as with the association of caveolin-1 PY14 with focal adhesion proteins. We transfected a megakaryoblast cell line (Meg-01) to deplete β-dystroglycan, subsequent to their differentiation to the platelet progenitors. Our data showed a direct interaction of the MLR with cytoskeleton to regulate platelet shape, while an association of caveolin-1 PY14 with vinculin is needed to establish focal adhesions, which are modulated for β-dystroglycan. In conclusion, caveolin-1 PY14 in association with platelet cytoskeleton participate in focal adhesions dynamics.

  14. Platelet adhesion and protein adsorption on silicone rubber surface by ozone-induced grafted polymerization with carboxybetaine monomer.

    Science.gov (United States)

    Zhou, Jun; Yuan, Jiang; Zang, Xiaopeng; Shen, Jian; Lin, Sicong

    2005-03-10

    Platelet adhesion and protein adsorption on the silicone rubber film grafted with N,N'-dimethyl-N-methacryloyloxyethyl-N-(2-carboxyethyl) ammonium (DMMCA) was studied. The grafting was carried out by means of ozone-induced method and was confirmed by ATR-FTIR and XPS investigations. The grafted films possessed relatively hydrophilic surface revealed by contact angle measurement. The blood compatibility of the grafted film was evaluated in vitro by platelet adhesion in platelet-rich plasma (PRP) and protein absorption in bovine fibrinogen (BFG) using silicone film as the reference. No substantial platelet adhesion was observed for the grafted films incubated in PRP for 60 and 180 min. The protein absorption was also significantly reduced after incubated in bovine fibrinogen for 60 min. Both the results indicated that the blood compatibility of silicone rubber was greatly improved by ozone-induced grafting of carboxybetaine zwitterionic polymer onto its surface.

  15. Experimental simulation of model platelet adhesion to a semi-permeable wall exposed to flow disturbance

    Institute of Scientific and Technical Information of China (English)

    DENG Xiaoyan; WANG Guixue; YANG Yang

    2003-01-01

    A sudden tubular expansion with a semi- permeable wall was constructed from a tubular dialysis membrane to investigate the effects of filtration flow and flow disturbance on particle deposition. The expansion was perfused with a dilute, neutrally buoyant suspension of 1.10 ?m diameter polystyrene latex spheres (as models of platelets) in Tris buffer solution containing 10% Dextran T70 and 2% bovine serum albumin. The results showed that adhesion of particles correlated positively with the filtration rate and inversely with the wall shear rate. In the vortex flow region distal to the expansion, particle adhesion was significantly elevated with a maximum at the reattachment point where the wall shear rate was the lowest and particles were constantly carried toward the vessel wall along the curved streamlines. In conclusion, filtration flow has a profound impact on the interaction of blood cells such as platelets with blood vessel walls, and the disturbed flow with a low wall shear rate can enhance the deposits of platelet thrombi to the vessel wall.

  16. Glycoprotein Ib-IX-V Complex Transmits Cytoskeletal Forces That Enhance Platelet Adhesion.

    Science.gov (United States)

    Feghhi, Shirin; Munday, Adam D; Tooley, Wes W; Rajsekar, Shreya; Fura, Adriane M; Kulman, John D; López, Jose A; Sniadecki, Nathan J

    2016-08-09

    Platelets bind to exposed vascular matrix at a wound site through a highly specialized surface receptor, glycoprotein (GP) Ib-IX-V complex, which recognizes von Willebrand factor (VWF) in the matrix. GPIb-IX-V is a catch bond for it becomes more stable as force is applied to it. After attaching to the wound site, platelets generate cytoskeletal forces to compact and reinforce the hemostatic plug. Here, we evaluated the role of the GPIb-IX-V complex in the transmission of cytoskeletal forces. We used arrays of flexible, silicone nanoposts to measure the contractility of individual platelets on VWF. We found that a significant proportion of cytoskeletal forces were transmitted to VWF through GPIb-IX-V, an unexpected finding given the widely held notion that platelet forces are transmitted exclusively through its integrins. In particular, we found that the interaction between GPIbα and the A1 domain of VWF mediates this force transmission. We also demonstrate that the binding interaction between GPIbα and filamin A is involved in force transmission. Furthermore, our studies suggest that cytoskeletal forces acting through GPIbα are involved in maintaining platelet adhesion when external forces are absent. Thus, the GPIb-IX-V/VWF bond is able to transmit force, and uses this force to strengthen the bond through a catch-bond mechanism. This finding expands our understanding of how platelets attach to sites of vascular injury, describing a new, to the best of our knowledge, mechanism in which the catch bonds of GPIb-IX-V/VWF can be supported by internal forces produced by cytoskeletal tension.

  17. Surface modification with poly(sulfobetaine methacrylate-co-acrylic acid) to reduce fibrinogen adsorption, platelet adhesion, and plasma coagulation.

    Science.gov (United States)

    Kuo, Wei-Hsuan; Wang, Meng-Jiy; Chien, Hsiu-Wen; Wei, Ta-Chin; Lee, Chiapyng; Tsai, Wei-Bor

    2011-12-12

    Zwitterionic sulfobetaine methacrylate (SBMA) polymers were known to possess excellent antifouling properties due to high hydration capacity and neutral charge surface. In this study, copolymers of SBMA and acrylic acid (AA) with a variety of compositions were synthesized and were immobilized onto polymeric substrates with layer-by-layer polyelectrolyte films via electrostatic interaction. The amounts of platelet adhesion and fibrinogen adsorption were determined to evaluate hemocompatibility of poly(SBMA-co-AA)-modified substrates. Among various deposition conditions by modulating SBMA ratio in the copolymers and pH of the deposition solution, poly(SBMA(56)-co-AA(44)) deposited at pH 3.0 possessed the best hemocompatibility. This work demonstrated that poly(SBMA-co-AA) copolymers adsorbed on polyelectrolyte-base films via electrostatic interaction improve hemocompatibility effectively and are applicable for various substrates including TCPS, PU, and PDMS. Furthermore, poly(SBMA-co-AA)-coated substrate possesses great durability under rigorous conditions. The preliminary hemocompatibility tests regarding platelet adhesion, fibrinogen adsorption, and plasma coagulation suggest the potential of this technique for the application to blood-contacting biomedical devices.

  18. Platelet adhesiveness and aggregation in congenital afibrinogenemia. An investigation of three patients with post-transfusion, cross-correction studies between two of them.

    Science.gov (United States)

    Girolami, A; De Marco, L; Virgolini, L; Peruffo, R; Fabris, F

    1975-02-01

    Platelet adhesiveness and aggregation were studied in three patients with congenital afibrinogenemia. The results obtained may be summarized as follows: The retention of platelets to a glass-bead filter determined with the Salzman method was significantly decreased; it was normal after fibrinogen infusion. With a modification of the Hellem test the values obtained were slightly decreased. Adrenalin-induced aggregation was absent whereas ADP-and collagen-induced aggregation was near normal or slightly decreased. Thrombofax aggregation was absent in citrated plasma. The abnormalities of platelet aggregation were corrected after fibrinogen infusion or after addition in vitro of fibrinogen, hemofilia A plasma and PPP obtained from an afibrinogenemic patient after fibrinogen infusion. The abnormalities of platelet aggregation were corrected well by ADP, collagen and Thrombofax in heparinized blood, but only a slight correction of adrenalin-induced aggregation was noted. Thrombin aggregation proved to be normal with the higher concentrations, whereas it was defective with the lower ones. Ristocetin aggregation was normal in citrated plasma at the concentration of 1.5 mg per ml but it was absent at the lower concentration (1.0 mg per ml). Ristocetin aggregation was, on the other hand absent in heparinized blood regardless of the concentration. These findings are in agreement with the presence of a prolonged bleeding time in congenital afibrinogenemia and suggest that fibrinogen plays an important role in platelet aggregation and adhesiveness.

  19. Reduced platelet adhesion and improved corrosion resistance of superhydrophobic TiO₂-nanotube-coated 316L stainless steel.

    Science.gov (United States)

    Huang, Qiaoling; Yang, Yun; Hu, Ronggang; Lin, Changjian; Sun, Lan; Vogler, Erwin A

    2015-01-01

    Superhydrophilic and superhydrophobic TiO2 nanotube (TNT) arrays were fabricated on 316L stainless steel (SS) to improve corrosion resistance and hemocompatibility of SS. Vertically-aligned superhydrophilic amorphous TNTs were fabricated on SS by electrochemical anodization of Ti films deposited on SS. Calcination was carried out to induce anatase phase (superhydrophilic), and fluorosilanization was used to convert superhydrophilicity to superhydrophobicity. The morphology, structure and surface wettability of the samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle goniometry. The effects of surface wettability on corrosion resistance and platelet adhesion were investigated. The results showed that crystalline phase (anatase vs. amorphous) and wettability strongly affected corrosion resistance and platelet adhesion. The superhydrophilic amorphous TNTs failed to protect SS from corrosion whereas superhydrophobic amorphous TNTs slightly improved corrosion resistance of SS. Both superhydrophilic and superhydrophobic anatase TNTs significantly improved corrosion resistance of SS. The superhydrophilic amorphous TNTs minimized platelet adhesion and activation whereas superhydrophilic anatase TNTs activated the formation of fibrin network. On the contrary, both superhydrophobic TNTs (superhydrophobic amorphous TNTs and superhydrophobic anatase TNTs) reduced platelet adhesion significantly and improved corrosion resistance regardless of crystalline phase. Superhydrophobic anatase TNTs coating on SS surface offers the opportunity for the application of SS as a promising permanent biomaterial in blood contacting biomedical devices, where both reducing platelets adhesion/activation and improving corrosion resistance can be effectively combined.

  20. Functional platelet defects in children with severe chronic ITP as tested with 2 novel assays applicable for low platelet counts.

    Science.gov (United States)

    van Bladel, Esther R; Laarhoven, Annemieke G; van der Heijden, Laila B; Heitink-Pollé, Katja M; Porcelijn, Leendert; van der Schoot, C Ellen; de Haas, Masja; Roest, Mark; Vidarsson, Gestur; de Groot, Philip G; Bruin, Marrie C A

    2014-03-06

    Immune thrombocytopenia (ITP) is an autoimmune disease with a complex heterogeneous pathogenesis and a bleeding phenotype that is not necessarily correlated to platelet count. In this study, the platelet function was assessed in a well-defined cohort of 33 pediatric chronic ITP patients. Because regular platelet function test cannot be performed in patients with low platelet counts, 2 new assays were developed to determine platelet function: first, the microaggregation test, measuring in platelets isolated from 10 mL of whole blood the platelet potential to form microaggregates in response to an agonist; second, the platelet reactivity assay, measuring platelet reactivity to adenosine diphosphate (ADP), convulxin (CVX), and thrombin receptor activator peptide in only 150 μL of unprocessed whole blood. Patients with a severe bleeding phenotype demonstrated a decreased aggregation potential upon phorbol myristate acetate stimulation, decreased platelet degranulation following ADP stimulation, and a higher concentration of ADP and CVX needed to activate the glycoprotein IIbIIIa complex compared with patients with a mild bleeding phenotype. In conclusion, here we have established 2 functional tests that allow for evaluation of platelet function in patients with extremely low platelet counts (platelet function is related to bleeding phenotype in chronic ITP.

  1. An improved layer-by-layer self-assembly technique to generate biointerfaces for platelet adhesion studies: Dynamic LbL

    Science.gov (United States)

    Lopez, Juan Manuel

    Layer-by-layer self-assembly (LbL) is a technique that generates engineered nano-scale films, coatings, and particles. These nanoscale films have recently been used in multiple biomedical applications. Concurrently, microfabrication methods and advances in microfluidics are being developed and combined to create "Lab-on-a-Chip" technologies. The potential to perform complex biological assays in vitro as a first-line screening technique before moving on to animal models has made the concept of lab on a chip a valuable research tool. Prior studies in the Biofluids Laboratory at Louisiana Tech have used layer-by-layer and in vitro biological assays to study thrombogenesis in a controlled, repeatable, engineered environment. The reliability of these previously established techniques was unsatisfactory for more complex cases such as chemical and shear stress interactions. The work presented in this dissertation was performed to test the principal assumptions behind the established laboratory methodologies, suggest improvements where needed, and test the impact of these improvements on accuracy and repeatability. The assumptions to be tested were: (1) The fluorescence microscopy (FM) images of acridine orange-tagged platelets accurately provide a measure of percent area of surface covered by platelets; (2) fibrinogen coatings can be accurately controlled, interact with platelets, and do not interfere with the ability to quantify platelet adhesion; and (3) the dependence of platelet adhesion on chemical agents, as measured with the modified methods, generally agrees with results obtained from our previous methods and with known responses of platelets that have been documented in the literature. The distribution of fibrinogen on the final LbL surface generated with the standard, static process (s-LbL) was imaged by tagging the fibrinogen with an anti-fibrinogen antibody bound to fluorescein isothiocyanate (FITC). FITC FM images and acridine orange FM images were taken

  2. A biomimetic peptide fluorosurfactant polymer for endothelialization of ePTFE with limited platelet adhesion.

    Science.gov (United States)

    Larsen, Coby C; Kligman, Faina; Tang, Chad; Kottke-Marchant, Kandice; Marchant, Roger E

    2007-08-01

    Endothelialization of expanded polytetrafluoroethylene (ePTFE) has the potential to improve long-term patency for small-diameter vascular grafts. Successful endothelialization requires ePTFE surface modification to permit cell attachment to this otherwise non-adhesive substrate. We report here on a peptide fluorosurfactant polymer (FSP) biomimetic construct that promotes endothelial cell (EC)-selective attachment, growth, shear stability, and function on ePTFE. The peptide FSP consists of a flexible poly(vinyl amine) backbone with EC-selective peptide ligands for specific cell adhesion and pendant fluorocarbon branches for stable anchorage to underlying ePTFE. The EC-selective peptide (primary sequence: Cys-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys, CRRETAWAC) has demonstrated high binding affinity for the alpha(5)beta(1) integrin found on ECs. Here, we demonstrate low affinity of CRRETAWAC for platelets and platelet integrins, thus providing it with EC-selectivity. This EC-selectivity could potentially facilitate rapid in vivo endothelialization and healing without thrombosis for small-diameter ePTFE vascular grafts.

  3. Platelets

    Science.gov (United States)

    ... tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding. Red blood cells are ... forming a long string. This illustrates the basic function of platelets, to stick to any foreign surface and then ...

  4. Reduced platelet adhesion on the surface of polyurethane bearing structure of sulfobetaine.

    Science.gov (United States)

    Yuan, J; Zhang, J; Zhu, J; Shen, J; Lin, S C; Zhu, W; Fang, J L

    2003-10-01

    Poly(etherurethane)s are widely used as blood-contacting biomaterials due to their good biocompatibility and mechanical properties. Nevertheless, their blood compatibility is still not adequate for the more demanding applications. Surface modification is an effective way to improve the blood compatibility and retain the bulk properties of biomaterials. The purpose of present study was to design and synthesize a novel nonthrombogenic biomaterial by modifying the surface of poly(etherurethane) with zwitterionic monomer. Films of polyurethane were grafted with sulfobetaine by a three-step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50 degrees C in the presence of di-n-butyl tin dilaurate (DBTDL) as a catalyst. The extent of the reaction was measured by ATR-IR spectra; a maximum number of free NCO group was obtained after a reaction time of 90 min. In the second step, the hydroxyl group of 4-dimethylamino-1-butanol (DMAB) was allowed to react in toluene with isocyanate groups bound on the surface. In the third step, sulfobetaine was formed on the surface through the ring-opening reaction between tertiary amine of DMAB and 1,3- propane-sultone (PS). It was characterized by ATR-IR, XPS. The data showed that the grafted surfaces were composed of sulfobetaine. The results of the contact angle measurements showed that they were strongly hydrophilic. The state of platelet adhesion and shape variation for the attached platelets was described. The modified surface shows excellent blood compatibility feature by the low platelet adhesion.

  5. Venous levels of shear support neutrophil-platelet adhesion and neutrophil aggregation in blood via P-selectin and beta2-integrin

    Science.gov (United States)

    Konstantopoulos, K.; Neelamegham, S.; Burns, A. R.; Hentzen, E.; Kansas, G. S.; Snapp, K. R.; Berg, E. L.; Hellums, J. D.; Smith, C. W.; McIntire, L. V.; Simon, S. I.

    1998-01-01

    BACKGROUND: After activation, platelets adhere to neutrophils via P-selectin and beta2-integrin. The molecular mechanisms and adhesion events in whole blood exposed to venous levels of hydrodynamic shear in the absence of exogenous activation remain unknown. METHODS AND RESULTS: Whole blood was sheared at approximately 100 s(-1). The kinetics of neutrophil-platelet adhesion and neutrophil aggregation were measured in real time by flow cytometry. P-selectin was upregulated to the platelet surface in response to shear and was the primary factor mediating neutrophil-platelet adhesion. The extent of neutrophil aggregation increased linearly with platelet adhesion to neutrophils. Blocking either P-selectin, its glycoprotein ligand PSGL-1, or both simultaneously by preincubation with a monoclonal antibody resulted in equivalent inhibition of neutrophil-platelet adhesion (approximately 30%) and neutrophil aggregation (approximately 70%). The residual amount of neutrophil adhesion was blocked with anti-CD11b/CD18. Treatment of blood with prostacyclin analogue ZK36374, which raises cAMP levels in platelets, blocked P-selectin upregulation and neutrophil aggregation to baseline. Complete abrogation of platelet-neutrophil adhesion required both ZK36374 and anti-CD18. Electron microscopic observations of fixed blood specimens revealed that platelets augmented neutrophil aggregation both by forming bridges between neutrophils and through contact-mediated activation. CONCLUSIONS: The results are consistent with a model in which venous levels of shear support platelet adherence to neutrophils via P-selectin binding PSGL-1. This interaction alone is sufficient to mediate neutrophil aggregation. Abrogation of platelet adhesion and aggregation requires blocking Mac-1 in addition to PSGL-1 or P-selectin. The described mechanisms are likely of key importance in the pathogenesis and progression of thrombotic disorders that are exacerbated by leukocyte-platelet aggregation.

  6. Influence of nitriding atmosphere on the modification of surface titanium with focus on the behavior of blood platelets adhesion; Influencia da atmosfera nitretante na modificacao de superficies de titanio com enfase no comportamento de adesao de plaquetas sanguineas

    Energy Technology Data Exchange (ETDEWEB)

    Vitoriano, J.O.; Alves, C. [Universidade Federal Rural do Semi-Arido (UFERSA), RN (Brazil); Braz, D.C.; Camara, R.B.G.; Rocha, H.A.O., E-mail: clodomiro.jr@hotmail.com [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil)

    2014-07-01

    The present study aimed to analyze the influence of surface modification of titanium on the adhesion of blood platelets, through techniques of adhesion and morphological analyzes. Discs of titanium grade II received different surface treatments with plasma of Ar + N{sub 2} + H{sub 2} and Ar + H{sub 2}, forming two experimental groups including only polished samples used as standard. Before and after treatment the samples were characterized according to topography, crystalline structure and wettability, using atomic force microscopy, X-ray diffraction, Raman spectroscopy and testing of sessile drop, respectively. Platelet rich plasma (PRP) was applied on the modified surfaces in a culture plates. Images obtained by electron microscopy of adhered platelets were analyzed to verify the behavior of platelets in the different experimental conditions. (author)

  7. Influence of platelet activating factor on expression of adhesion molecules in experimental pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Hua Zhao; Ji-Wei Chen; Ya-Kui Zhou; Xue-Feng Zhou; Pei-Yun Li

    2003-01-01

    AIM: To determine whether Platelet activating factor (PAF)has a regulation role in the expression of adhesion moleculesand accumulation of neutrophils in a murine model of acutepancreatitis.METHODS: One hundred twenty-eight Kunming mice weredivided into four groups. Group 1 received 0.1 mi saline s.c.every hour for three hours (sham). Group 2 received cerulein(50 μg/kg dose s.c.) every hour for three hours. Group 3received AP and additional challenge of PAF (50 rg/kg inabsolute ethanol) (AP/PAF). Group 4 received AP, plustherapeutic treatment with GAB (25 mg dose i.p.) immediatelyafter the first challenge of cerulein (AP/GAB). Animals weresacrificed at 12 h after the first challenge of saline or cerulein.Adhesion molecules of pancreas were semi-quantified bySP methods. Standard assays were performed for serumamylase and myeloperoxidase activity (MPO) of pancreas.Histology of pancreas was scored in a blind manner. Watercontent of pancreas was also measured at the same time.RESULTS: Control pancreata showed negligible adhesionmolecule expression and neutrophil accumulation. Therewere evident adhesion molecules expression and neutrophilaccumulation in AP and AP/PAF compared with sham (P<0.05).AP/GAB had a lower level of adhesion molecules, neutrophils,and water content versus AP and AP/PAF (P<0.05). Histologyshowed a trend toward improvement in AP/GAB, but didnot reach statistical significance.CONCLUSION: PAF can induce the expression of adhesionmolecules that mediate neutrophil accumulation. The PAFantagonist reduces the expression of adhesion moleculesand the severity of inflammation when given immediatelyafter the induction of mild AP in mice. These results suggestthat PAF antagonism may be useful in the treatment of mildpancreatitis after its clinical onset.

  8. Application of the Blister Test in Study of Epoxy Adhesive

    Institute of Scientific and Technical Information of China (English)

    Fei Xiong; Ingegerd Annergren

    2000-01-01

    Shaft-loaded blister test technique is used as an effective quantitative tool to measure adhesion strength. Investigation on conductive adhesive was done by modified blister test. It is found that shaftloaded blister test can be a good solution for the debonding of thin film adhesion. The intrinsic stable interface debonding process has been proved an attractive alternative to the conventional adhesion measurement techniques. In our study, epoxy matrix adhesive was studied using blister test technique in comparison with the traditional test-lap shear test. Adhesion strength was studied as a function of surface treatment and the metallization of substrate. It was found that surface conditions of substrate have significant impact on adhesion behaviour. The oxidation of surface is responsible for the poor adhesion. Activating chemical treatment and Plasma cleaning on substrate surface has been found to be a way of dreamatically improving adhesion strength of electronic conductive adhesive.

  9. Adhesion of blood platelets under flow to wettability gradient polyethylene surfaces made in a shielded gas plasma

    NARCIS (Netherlands)

    Spijker, HT; Busscher, HJ; Graaff, R; van Oeveren, W; Bos, R.R.M.

    2002-01-01

    Adhesion and activation of platelets are important steps in the thrombosis of blood after contact with a biomaterial surface and are governed, in part, by the wettability of the surface. Since most implanted devices are in contact with blood under flow conditions, it is important to study the effect

  10. Micro-structuring of polycarbonate-urethane surfaces in order to reduce platelet activation and adhesion.

    Science.gov (United States)

    Clauser, Johanna; Gester, Kathrin; Roggenkamp, Jan; Mager, Ilona; Maas, Judith; Jansen, Sebastian V; Steinseifer, Ulrich

    2014-01-01

    In the development of new hemocompatible biomaterials, surface modification appears to be a suitable method in order to reduce the thrombogenetic potential of such materials. In this study, polycarbonate-urethane (PCU) tubes with different surface microstructures to be used for aortic heart valve models were investigated with regard to the thrombogenicity. The surface structures were produced by using a centrifugal casting process for manufacturing PCU tubes with defined casting mold surfaces which are conferred to the PCU surface during the process. Tubes with different structures defined by altering groove widths were cut into films and investigated under dynamic flow conditions in contact with porcine blood. The analysis was carried out by laser scanning microscopy which allowed for counting various morphological types of platelets with regard to the grade of activation. The comparison between plain and shaped PCU samples showed that the surface topography led to a decline of the activation of the coagulation cascade and thus to the reduction of the fibrin synthesis. Comparing different types of structures revealed that smooth structures with a small groove width (d ~ 3 μm) showed less platelet activation as well as less adhesion in contrast to a distinct wave structure (d ~ 90 μm). These results prove surface modification of polymer biomaterials to be a suitable method for reducing thrombogenicity and hence give reason for further alterations and improvements.

  11. Megakaryocytic cells synthesize and platelets secrete alpha5-laminins, and the endothelial laminin isoform laminin 10 (alpha5beta1gamma1) strongly promotes adhesion but not activation of platelets.

    Science.gov (United States)

    Nigatu, Ayele; Sime, Wondossen; Gorfu, Gezahegn; Geberhiwot, Tarekegn; Andurén, Ingegerd; Ingerpuu, Sulev; Doi, Masayuki; Tryggvason, Karl; Hjemdahl, Paul; Patarroyo, Manuel

    2006-01-01

    Following vascular injury, basement membrane (BM) components of the blood vessels are exposed to circulating cells and may contribute to hemostasis and/or thrombosis. Laminins 8 (LN-8) (alpha4beta1gamma1) and 10 (LN-10) (alpha5beta1gamma1) are major laminin isoforms of the endothelial BM, and LN-8 is also secreted by activated platelets. In the present study, we demonstrate synthesis of alpha5-laminins LN-10 and LN-11 (alpha5beta2gamma1) by megakaryocytic cells, and intracellular expression of these laminin isoforms in blood platelets. In contrast to platelet LN alpha4 chain that had an apparent molecular weight of 180 kDa and associated mostly to LNbeta1 chain, platelet LNalpha5 consisted of 300/350 kDa polypeptides and associated mainly to LNbeta2. Both alpha4- and alpha5-laminins were secreted by platelets following stimulation. When compared to recombinant human (rh) LN-8, rhLN-10 was much more adhesive to platelets, though adhesion to both proteins was largely mediated via alpha6beta1 integrin. In spite of their adhesive properties, rhLN-8 and rhLN-10 induced neither P-selectin expression nor cell aggregation, two signs of platelet activation. This study demonstrates synthesis/expression of heterotrimeric alpha5-laminins in hematopoietic/blood cells, and provides evidence for the adhesive, but not activating, role of endothelial laminin isoforms in platelet biology.

  12. Amphiphilic macromolecule nanoassemblies suppress smooth muscle cell proliferation and platelet adhesion.

    Science.gov (United States)

    Chan, Jennifer W; Lewis, Daniel R; Petersen, Latrisha K; Moghe, Prabhas V; Uhrich, Kathryn E

    2016-04-01

    While the development of second- and third-generation drug-eluting stents (DES) have significantly improved patient outcomes by reducing smooth muscle cell (SMC) proliferation, DES have also been associated with an increased risk of late-stent thrombosis due to delayed re-endothelialization and hypersensitivity reactions from the drug-polymer coating. Furthermore, DES anti-proliferative agents do not counteract the upstream oxidative stress that triggers the SMC proliferation cascade. In this study, we investigate biocompatible amphiphilic macromolecules (AMs) that address high oxidative lipoprotein microenvironments by competitively binding oxidized lipid receptors and suppressing SMC proliferation with minimal cytotoxicity. To determine the influence of nanoscale assembly on proliferation, micelles and nanoparticles were fabricated from AM unimers containing a phosphonate or carboxylate end-group, a sugar-based hydrophobic domain, and a hydrophilic poly(ethylene glycol) domain. The results indicate that when SMCs are exposed to high levels of oxidized lipid stimuli, nanotherapeutics inhibit lipid uptake, downregulate scavenger receptor expression, and attenuate scavenger receptor gene transcription in SMCs, and thus significantly suppress proliferation. Although both functional end-groups were similarly efficacious, nanoparticles suppressed oxidized lipid uptake and scavenger receptor expression more effectively compared to micelles, indicating the relative importance of formulation characteristics (e.g., higher localized AM concentrations and nanotherapeutic stability) in scavenger receptor binding as compared to AM end-group functionality. Furthermore, AM coatings significantly prevented platelet adhesion to metal, demonstrating its potential as an anti-platelet therapy to treat thrombosis. Thus, AM micelles and NPs can effectively repress early stage SMC proliferation and thrombosis through non-cytotoxic mechanisms, highlighting the promise of nanomedicine for

  13. 76 FR 77833 - Scientific Information Request on CYP2C19 Variants and Platelet Reactivity Tests

    Science.gov (United States)

    2011-12-14

    ... Variants and Platelet Reactivity Tests AGENCY: Agency for Healthcare Research and Quality (AHRQ), HHS... platelet reactivity tests. Scientific information is being solicited to inform our Comparative... for studies that report on CYP2C19 variants and platelet reactivity tests, including those...

  14. [Effect of lovastatin on adhesive and aggregation function of platelets in patients with arterial hypertension and dislipidemia].

    Science.gov (United States)

    Medvedev, I N; Skoriatina, I A

    2010-01-01

    The aim of the study was to evaluate efficiency of correction of lipid profile disturbances and platelet dysfunction by lovastatin in patients with arterial hypertension and dyslipidemia. Lovastatin was given to 29 patients for 4 months. The main parameters measured included dynamics of blood lipid profile, lipid peroxidation in plasma and platelets, antioxidative protection of blood fluid and platelets, platelet activity. t-Students test was used to assess statistical significance of the results. It was shown that lovastatin has beneficial effect on dyslipoproteidemia and peroxidation syndrome. Moreover, it normalizes intraplatelet regulatory mechanisms and inhibits enhanced platelet activity. Effects of lovastatin in patients with arterial hypertension and dyslipidemia persist under conditions of long-term therapy.

  15. Platelet adhesion, contact phase coagulation activation, and C5a generation of polyethylene glycol acid-grafted high flux cellulosic membrane with varieties of grafting amounts.

    Science.gov (United States)

    Fushimi, F; Nakayama, M; Nishimura, K; Hiyoshi, T

    1998-10-01

    Grafting of polyethylene glycol chains onto cellulosic membrane can be expected to reduce the interaction between blood (plasma protein and cells) and the membrane surface. Alkylether carboxylic acid (PEG acid) grafted high flux cellulosic membranes for hemodialysis, in which the polyethylene glycol chain bears an alkyl group at one side and a carboxyl group at the other side, have been developed and evaluated. PEG acid-grafted high flux cellulosic membranes with various grafting amounts have been compared with respect to platelet adhesion, the contact phase of blood coagulation, and complement activation in vitro. A new method of quantitating platelet adhesion on hollow-fiber membrane surfaces has been developed, which is based on the determination of lactate dehydrogenase (LDH) activity after lysis of the adhered platelets. PEG acid-grafted high flux cellulosic membranes showed reduced platelet adhesion and complement activation effects in grafting amounts of 200 ppm or higher without detecting adverse effects up to grafting amounts of 850 ppm. The platelet adhesion of a PEG acid-grafted cellulosic membrane depends on both the flux and grafting amounts of the membrane. It is concluded that the grafting of PEG acid onto a cellulosic membrane improves its biocompatibility as evaluated in terms of platelet adhesion, complement activation, and thrombogenicity.

  16. What’s new in using platelet research? To unravel thrombopathies and other human disorders

    OpenAIRE

    Freson, Kathleen; Labarque, Veerle; Thys, Chantal; Wittevrongel, Christine; Van Geet, Chris

    2007-01-01

    This review on platelet research focuses on defects of adhesion, cytoskeletal organisation, signal transduction and secretion. Platelet defects can be studied by different laboratory platelet functional assays and morphological studies. Easy bruising or a suspected platelet-based bleeding disorder is of course the most obvious reason to test the platelet function in a patient. However, nowadays platelet research also contributes to our understanding of human pathology in other disciplines suc...

  17. Utilization of star-shaped polymer architecture in the creation of high-density polymer brush coatings for the prevention of platelet and bacteria adhesion

    Science.gov (United States)

    Totani, Masayasu; Terada, Kayo; Terashima, Takaya; Kim, Ill Yong; Ohtsuki, Chikara; Xi, Chuanwu; Tanihara, Masao

    2014-01-01

    We demonstrate utilization of star-shaped polymers as high-density polymer brush coatings and their effectiveness to inhibit the adhesion of platelets and bacteria. Star polymers consisting of poly(2-hydroxyethyl methacrylate) (PHEMA) and/or poly(methyl methacrylate) (PMMA), were synthesized using living radical polymerization with a ruthenium catalyst. The polymer coatings were prepared by simple drop casting of the polymer solution onto poly(ethylene terephthalate) (PET) surfaces and then dried. Among the star polymers prepared in this study, the PHEMA star polymer (star-PHEMA) and the PHEMA/PMMA (mol. ratio of 71/29) heteroarm star polymer (star-H71M29) coatings showed the highest percentage of inhibition against platelet adhesion (78–88% relative to noncoated PET surface) and Escherichia coli (94–97%). These coatings also showed anti-adhesion activity against platelets after incubation in Dulbecco's phosphate buffered saline or surfactant solution for 7 days. In addition, the PMMA component of the star polymers increased the scratch resistance of the coating. These results indicate that the star-polymer architecture provides high polymer chain density on PET surfaces to prevent adhesion of platelets and bacteria, as well as coating stability and physical durability to prevent exposure of bare PET surfaces. The star polymers provide a simple and effective approach to preparing anti-adhesion polymer coatings on biomedical materials against the adhesion of platelets and bacteria. PMID:25485105

  18. Hodgkin lymphoma cell lines bind to platelets. Incubation with platelets induces CD15 and P-selectin dependent adhesion of the cell lines to Human Umbilical Vein Endothelial cells (HUVEC).

    Science.gov (United States)

    Ohana, Ofra Malka; Ozer, Janet; Prinsloo, Isebrand; Benharroch, Daniel; Gopas, Jacob

    2015-01-01

    Hodgkin's lymphoma is believed to spread in an orderly fashion within the lymphatic compartment. In a minority of cases, after reaching the spleen, the neoplasm disseminates, reminiscent of metastasis. In the spleen, the Hodgkin-Reed-Sternberg tumor cells come across platelets in the blood vessels and mainly in the splenic red pulp. Based on this knowledge, we investigated the possibility of platelets inducing cell adhesion in Hodgkin's lymphoma cell lines. We showed that L428 and KMH-2 cells strongly adhere to thrombin-activated platelets. Cell adhesion to platelets is partially dependent on CD15 antigens (Lewis(X)), mainly sialyl-CD15, and P-selectin. KMH-2, as compared to L428 cells, showed increased binding due to its differential high expression of the sialyl-CD15. As a consequence of incubation with platelets, KMH-2 cells also produced increased amounts of tumor necrosis factors α (TNFα) followed by enhanced binding to human vascular endothelial cells (HUVEC). Incubation of both cell lines with activated platelets also induced activation of AP-1 transcription complex. Our findings are consistent with the concept that platelets play a critical role in the dissemination of HRS cells in HL, predominantly in the spleen, by increasing cell adhesion and thus promoting their proliferative and migratory properties beyond the lymphatic system.

  19. Control of Integrin αIIbβ3 Outside-In Signaling and Platelet Adhesion by Sensing the Physical Properties of Fibrin(ogen) Substrates†

    OpenAIRE

    Podolnikova, Nataly P.; Yermolenko, Ivan S.; Fuhrmann, Alexander; Lishko, Valeryi K.; Magonov, Sergei; Bowen, Benjamin; Enderlein, Joerg; Podolnikov, Andriy V.; Ros, Robert; Ugarova, Tatiana P.

    2010-01-01

    The physical properties of substrates are known to control cell adhesion via integrin-mediated signaling. Fibrin and fibrinogen, the principal components of hemostatic and pathological thrombi, may represent biologically relevant substrates whose variable physical properties control adhesion of leukocytes and platelets. In our previous work, we have shown that binding of fibrinogen to the surface of fibrin clot prevents cell adhesion by creating an antiadhesive fibrinogen layer. Furthermore, ...

  20. Shuttle active thermal control system development testing. Volume 7: Improved radiator coating adhesive tests

    Science.gov (United States)

    Reed, M. W.

    1973-01-01

    Silver/Teflon thermal control coatings have been tested on a modular radiator system projected for use on the space shuttle. Seven candidate adhesives have been evaluated in a thermal vacuum test on radiator panels similar to the anticipated flight hardware configuration. Several classes of adhesives based on polyester, silicone, and urethane resin systems were tested. These included contact adhesives, heat cured adhesives, heat and pressure cured adhesives, pressure sensitive adhesives, and two part paint on or spray on adhesives. The coatings attached with four of the adhesives, two silicones and two urethanes, had no changes develop during the thermal vacuum test. The two silicone adhesives, both of which were applied to the silver/Teflon as transfer laminates to form a tape, offered the most promise based on application process and thermal performance. Each of the successful silicone adhesives required a heat and pressure cure to adhere during the cryogenic temperature excursion of the thermal-vacuum test.

  1. Test method to assess interface adhesion in composite bonding

    OpenAIRE

    2015-01-01

    This paper introduces a new type of peel tests dedicated to composite bonding: Composite Peel Tests. This test is inspired on the standard floating roller peel test widely used for metal bonding. The aim of this study is to investigate the potential of the Composite Peel Test to assess interface adhesion in composite bonded structures. To this end, peel tests were performed with nine different types of adhesives and at two environmental temperatures, room temperature and +80°C. The results we...

  2. Influence of abciximab on the adhesion of platelets on a shielded plasma gradient prepared on polyethylene

    NARCIS (Netherlands)

    Spijker, HT; Busscher, HJ; van Oeveren, W

    2002-01-01

    Introduction: Thrombotic effects of biomaterial implants are mediated merely through activation of the platelet glycoprotein IIb-Illa (GpIIb-IIIa) receptor. Consequently, platelet GpIIb-IIIa receptor inhibitors are successfully used during stent implantation procedures to prevent thrombosis. However

  3. HPA-1 polymorphism of αIIbβ3 modulates platelet adhesion onto immobilized fibrinogen in an in-vitro flow system

    Directory of Open Access Journals (Sweden)

    Mihalj Mario

    2007-02-01

    Full Text Available Abstract Background Platelet adhesion and subsequent thrombus formation on a subendothelial matrix at the site of vascular damage play a crucial role in the arrest of posttraumatic bleeding but also in different pathological thrombotic events, such as acute coronary syndrome and stroke. Recently published studies have clearly demonstrated that platelet integri αIIbβ3 is intimately involved in the occlusive thrombus formation at the site of endothelial damage. Therefore, any genetic variation in the expression of this receptor may lead to an excessive bleeding or excessive thrombus formation. In this study, we evaluated the influence of HPA-1 polymorphism of integrin αIIbβ3 on platelet adhesion onto immobilized fibrinogen using an in vitro system simulating blood flow. Methods Platelets in anticoagulated whole blood [49 healthy previously genotyped blood donors were labelled with fluorescence dye and perfused through a rectangular flow chamber (shear rates of 50 s-1, 500 s-1 and 1500 s-1. A fluorescence laser-scan microscope was used for visualisation and quantification of platelet adhesion at 15 sec, 1 and 5 minutes after start of perfusion. Results During perfusion, the platelet adhesion linearly increased with regard to exposition time and shear rate. Perfusion of blood preincubated with Abciximab over fibrinogen-coated cover-slips showed reduced platelet adherence (absolute fluorescence: 168 ± 35 U vs. 53000 ± 19000 at control experiments, p Conclusion Our data support the contention that genetically determined variants of platelet integrins αIIbβ3 could play a role in arterial thrombogenesis and thus confirm the hypothesis derived from epidemiological studies.

  4. Platelet Endothelial Cell Adhesion Molecule-1 Gene Polymorphisms are Associated with Coronary Artery Lesions in the Chronic Stage of Kawasaki Disease.

    Science.gov (United States)

    Lu, Wen-Hsien; Huang, Sin-Jhih; Yuh, Yeong-Seng; Hsieh, Kai-Sheng; Tang, Chia-Wan; Liou, Huei-Han; Ger, Luo-Ping

    2017-05-01

    Kawasaki disease is the most common cause of pediatric acquired heart disease. The role of platelet endothelial cell adhesion molecule-1 in the inflammatory process has been documented. To date, no report has investigated the relationship between coronary artery lesions of Kawasaki disease and platelet endothelial cell adhesion molecule-1 polymorphisms. A total of 114 Kawasaki disease children with coronary artery lesions and 185 Kawasaki disease children without coronary artery lesions were recruited in this study. The TaqMan assay was conducted to identify the genotype in this case-control study. In three single nucleotide polymorphisms (Leu125Val, Ser563Asn, and Arg670Gly) of platelet endothelial cell adhesion molecule-1, we found that the Leu-Ser-Arg haplotype was associated with a significantly increased risk for coronary artery lesions in the chronic stage (odds ratio 3.05, 95% confidence interval 1.06-8.80, p = 0.039), but not for coronary artery lesions in the acute stage. Analysis based on the diplotypes of platelet endothelial cell adhesion molecule-1 also showed that Kawasaki disease with one or two alleles of Leu-Ser-Arg had a significantly increased risk of chronic coronary artery lesions (odds ratio 3.38, 95% confidence interval 1.11-10.28, p = 0.032) and had increased platelet counts after Kawasaki disease was diagnosed, as compared to those with other diplotypes. The haplotype of platelet endothelial cell adhesion molecule-1 Leu-Ser-Arg might be associated with the increased platelet counts and the following risk of chronic coronary artery lesions in a dominant manner in Kawasaki disease.

  5. Anti-platelet Therapy Resistance – Concept, Mechanisms and Platelet Function Tests in Intensive Care Facilities

    Directory of Open Access Journals (Sweden)

    Mărginean Alina

    2016-01-01

    Full Text Available It is well known that critically ill patients require special attention and additional consideration during their treatment and management. The multiple systems and organ dysfunctions, typical of the critical patient, often results in different patterns of enteral absorption in these patients. Anti-platelet drugs are the cornerstone in treating patients with coronary and cerebrovascular disease. Dual anti-platelet therapy with aspirin and clopidogrel is the treatment of choice in patients undergoing elective percutaneous coronary interventions and is still widely used in patients with acute coronary syndromes. However, despite the use of dual anti-platelet therapy, some patients continue to experience cardiovascular ischemic events. Recurrence of ischemic events is partly attributed to the fact that some patients have poor inhibition of platelet reactivity despite treatment. These patients are considered low- or nonresponders to therapy. The underlying mechanisms leading to resistance are not yet fully elucidated and are probably multifactorial, cellular, genetic and clinical factors being implicated. Several methods have been developed to asses platelet function and can be used to identify patients with persistent platelet reactivity, which have an increased risk of thrombosis. In this paper, the concept of anti-platelet therapy resistance, the underlying mechanisms and the methods used to identify patients with low responsiveness to anti-platelet therapy will be highlighted with a focus on aspirin and clopidogrel therapy and addressing especially critically ill patients.

  6. Testing Interconnections using Conductive Adhesives for Application in PV Modules

    Energy Technology Data Exchange (ETDEWEB)

    Broek, K.M.; De Jong, P.C.; Kloos, M.J.H. [ECN Solar Energy, Petten (Netherlands); Van den Nieuwenhof, M.A.C.J.; Bots, T.L.; Meuwissen, M.H.H.; Steijvers, H.L.A.H. [TNO Science and Industry, Eindhoven (Netherlands)

    2006-09-15

    In current module production the electrical interconnections are soldered to the solar cells. For current modules with thin cells and new module concepts with back contact cells, the replacement of solder by conductive adhesives can be advantageous. However, the current IEC tests were developed for soldered interconnections, which have other failure mechanisms. Therefore, three additional tests have been developed for the testing of conductive adhesives to be used in solar modules. In combination with computer simulation techniques developed in the same project, the tests will contribute to a better understanding of failure mechanisms of PV modules with conductive adhesives.

  7. TOPICAL REVIEW: Recent advances in the fabrication and adhesion testing of biomimetic dry adhesives

    Science.gov (United States)

    Sameoto, D.; Menon, C.

    2010-10-01

    In the past two years, there have been a large number of publications on the topic of biomimetic dry adhesives from modeling, fabrication and testing perspectives. We review and compare the most recent advances in fabrication and testing of these materials. While there is increased convergence and consensus as to what makes a good dry adhesive, the fabrication of these materials is still challenging, particularly for anisotropic or hierarchal designs. Although qualitative comparisons between different adhesive designs can be made, quantifying the exact performance and rating each design is significantly hampered by the lack of standardized testing methods. Manufacturing dry adhesives, which can reliably adhere to rough surfaces, show directional and self-cleaning behavior and are relatively simple to manufacture, is still very challenging—great strides by multiple research groups have however made these goals appear achievable within the next few years.

  8. The use of platelet reactivity testing in patients on antiplatelet therapy for prediction of bleeding events after cardiac surgery.

    Science.gov (United States)

    Leunissen, Tesse C; Janssen, Paul W A; Ten Berg, Jurriën M; Moll, Frans L; Korporaal, Suzanne J A; de Borst, Gert Jan; Pasterkamp, Gerard; Urbanus, Rolf T

    2016-02-01

    Many patients are treated with platelet inhibitors such as aspirin and clopidogrel for prevention of thrombotic cardiovascular events. However, the inhibitory effect of antiplatelet therapy is variable between patients; in some, the platelets are hardly inhibited, while in others, the platelets are excessively inhibited. The newer and more potent platelet inhibitors, prasugrel and ticagrelor, often lead to low platelet reactivity, which potentially leads to bleeding events. Preoperative measurement of platelet reactivity in patients receiving platelet inhibitors who undergo cardiac surgery, could be useful to identify those with low platelet reactivity and thus have an increased risk of bleeding during or after surgery. In this review, we discuss the most commonly used platelet inhibitors and platelet function tests. Furthermore, we will provide an overview of the evidence for the prediction of post-operative bleeding at the operation site with preoperative platelet reactivity testing in patients undergoing cardiac surgery. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Functional groups grafted nonwoven fabrics for blood filtration-The effects of functional groups and wettability on the adhesion of leukocyte and platelet

    Energy Technology Data Exchange (ETDEWEB)

    Yang Chao [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Cao Ye [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China); Sun Kang, E-mail: ksun@sjtu.edu.cn [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Liu Jiaxin; Wang Hong [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China)

    2011-01-15

    In this work, the effects of grafted functional groups and surface wettability on the adhesion of leukocyte and platelet were investigated by the method of blood filtration. The filter materials, poly(butylene terephthalate) nonwoven fabrics bearing different functional groups including hydroxyl (OH), carboxyl (COOH), sulfonic acid group (SO{sub 3}H) and zwitterionic sulfobetaine group ({sup +}N((CH{sub 3}){sub 2})(CH{sub 2}){sub 3}SO{sub 3}{sup Circled-Minus }) with controllable wettability were prepared by UV radiation grafting vinyl monomers with these functional groups. Our results emphasized that both surface functional groups and surface wettability had significant effects on the adhesion of leukocyte and platelet. In the case of filter materials with the same wettability, leukocytes adhering to filter materials decreased in the order: the surface bearing OH only > the surface bearing both OH and COOH > the surface bearing sulfobetaine group > the surface bearing SO{sub 3}H, while platelets adhering to filter materials decreased as the following order: the surface bearing SO{sub 3}H > the surface bearing both OH and COOH > the surface bearing OH only > the surface bearing sulfobetaine group. As the wettability of filter materials increased, both leukocyte and platelet adhesion to filter materials declined, except that leukocyte adhesion to the surface bearing OH only remained unchanged.

  10. Modification of gold surface by grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion.

    Science.gov (United States)

    Zhang, F; Kang, E T; Neoh, K G; Huang, W

    2001-01-01

    Gold surfaces were first treated in an alkanethiol solution to form self-assembled monolayers (SAMs). The thiolated Au surface was then subjected to Ar plasma pretreatment, followed by air exposure and UV-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA) macromonomer. In comparison with the 3-mercaptopropionic acid-2-ethylhexyl ester (MPAEE) SAM, the (3-mercaptoproply)trimethoxysilane (MPTMS) SAM on Au exhibited higher stability under the conditions of Ar plasma pretreatment. The graft concentration of the PEGMA polymer on SAM-modified Au surface increased with increasing PEGMA macromonomer concentration and UV-graft polymerization time. The modified-Au surfaces were characterized by X-ray spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle measurement. The Au surface with a high concentration of grafted PEGMA polymer could completely repel protein adsorption and platelet adhesion.

  11. Analysis of Adhesively Bonded Ceramics Using an Asymmetric Wedge Test

    Science.gov (United States)

    2008-12-01

    moisture durability of adhesive bonding of ceramics is dental applications (12–14). The adhesive bonding of ceramic orthodontic inserts presents unique...sample sets. Environmental exposure is often limited to mechanical testing on the millimeter scale of bonded ceramic blocks or extracted human...Dressler, K. B.; Grenadier, M. R. Direct Bonding of Orthodontic Brackets to Esthetic Restorative Materials Using a Silane. Am. J. Orthodontics and

  12. Lap Shear Testing of Candidate Radiator Panel Adhesives

    Science.gov (United States)

    Ellis, David; Briggs, Maxwell; McGowan, Randy

    2013-01-01

    During testing of a subscale radiator section used to develop manufacturing techniques for a full-scale radiator panel, the adhesive bonds between the titanium heat pipes and the aluminum face sheets failed during installation and operation. Analysis revealed that the thermal expansion mismatch between the two metals resulted in relatively large shear stresses being developed even when operating the radiator at moderate temperatures. Lap shear testing of the adhesive used in the original joints demonstrated that the two-part epoxy adhesive fell far short of the strength required. A literature review resulted in several candidate adhesives being selected for lap shear joint testing at room temperature and 398 K, the nominal radiator operating temperature. The results showed that two-part epoxies cured at room and elevated temperatures generally did not perform well. Epoxy film adhesives cured at elevated temperatures, on the other hand, did very well with most being sufficiently strong to cause yielding in the titanium sheet used for the joints. The use of an epoxy primer generally improved the strength of the joint. Based upon these results, a new adhesive was selected for the second subscale radiator section.

  13. The feasibility of bench tests for disposable ECG electrode adhesiveness.

    Science.gov (United States)

    Baker, C D; Schoenberg, A A; Booth, H E

    1979-01-01

    The feasibility of recommending one standard bench test that adequately qualifies electrode adhesives for clinical use was examined by UBTL. Small strips, cut from whole, commercially available disposable ECG electrodes, were attached to three types of surfaces, and samples of each type of electrode were peel tested at 15 minutes, 8 hours, and 48 hours after attachment. A program was developed to average, display, and calculate peel strength parameters. Analysis of the data showed that (a) the peel strength of electrodes varied by more than a factor of 10 when measured on human skin, and by more than a factor of 3 when measured on bench test surfaces, and (b) the peel strength of the electrode adhesive strips did not correlate with intact electrode loss on ambulatory subjects. Therefore, UBTL could not recommend one bench test that would measure adhesion performance for all electrode types appropriate for inclusion in an AAMI ECG electrode standard.

  14. Mechanism of Collaborative Enhancement of Binding of Paired Antibodies to Distinct Epitopes of Platelet Endothelial Cell Adhesion Molecule-1.

    Science.gov (United States)

    Kiseleva, Raisa; Greineder, Colin F; Villa, Carlos H; Hood, Elizabeth D; Shuvaev, Vladimir V; Sun, Jing; Chacko, Ann-Marie; Abraham, Valsamma; DeLisser, Horace M; Muzykantov, Vladimir R

    2017-01-01

    Monoclonal antibodies (mAbs) directed to extracellular epitopes of human and mouse Platelet Endothelial Cell Adhesion Molecule-1 (CD31 or PECAM-1) stimulate binding of other mAbs to distinct adjacent PECAM-1 epitopes. This effect, dubbed Collaborative Enhancement of Paired Affinity Ligands, or CEPAL, has been shown to enhance delivery of mAb-targeted drugs and nanoparticles to the vascular endothelium. Here we report new insights into the mechanism underlying this effect, which demonstrates equivalent amplitude in the following models: i) cells expressing a full length PECAM-1 and mutant form of PECAM-1 unable to form homodimers; ii) isolated fractions of cellular membranes; and, iii) immobilized recombinant PECAM-1. These results indicate that CEPAL is mediated not by interference in cellular functions or homophilic PECAM-1 interactions, but rather by conformational changes within the cell adhesion molecule induced by ligand binding. This mechanism, mediated by exposure of partially occult epitopes, is likely to occur in molecules other than PECAM-1 and may represent a generalizable phenomenon with valuable practical applications.

  15. Platelet adhesion: structural and functional diversity of short dystrophin and utrophins in the formation of dystrophin-associated-protein complexes related to actin dynamics.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Rojas, Dalila; Chávez, Oscar; Martínez-Pérez, Francisco; García-Sierra, Francisco; Rendon, Alvaro; Mornet, Dominique; Mondragón, Ricardo

    2005-12-01

    Platelets are dynamic cell fragments that modify their shape during activation. Utrophin and dystrophins are minor actin-binding proteins present in muscle and non-muscle cytoskeleton. In the present study, we characterised the pattern of Dp71 isoforms and utrophin gene products by immunoblot in human platelets. Two new dystrophin isoforms were found, Dp71f and Dp71 d, as well as the Up71 isoform and the dystrophin-associated proteins, alpha and beta -dystrobrevins. Distribution of Dp71d/Dp71delta110m, Up400/Up71 and dystrophin-associated proteins in relation to the actin cytoskeleton was evaluated by confocal microscopy in both resting and platelets adhered on glass. Formation of two dystrophin-associated protein complexes (Dp71d/Dp71delta110m approximately DAPC and Up400/Up71 approximately DAPC) was demonstrated by co-immunoprecipitation and their distribution in relation to the actin cytoskeleton was characterised during platelet adhesion. The Dp71d/Dp71delta100m approximately DAPC is maintained mainly at the granulomere and is associated with dynamic structures during activation by adhesion to thrombin-coated surfaces. Participation of both Dp71d/Dp71delta110m approximately DAPC and Up400/Up71 approximately DAPC in the biological roles of the platelets is discussed.

  16. Quantitative Glycoproteomic Analysis Identifies Platelet-Induced Increase of Monocyte Adhesion via the Up-Regulation of Very Late Antigen 5.

    Science.gov (United States)

    Huang, Jiqing; Kast, Juergen

    2015-08-07

    Physiological stimuli, such as thrombin, or pathological stimuli, such as lysophosphatidic acid (LPA), activate platelets circulating in blood. Once activated, platelets bind to monocytes via P-selectin-PSGL-1 interactions but also release the stored contents of their granules. These platelet releasates, in addition to direct platelet binding, activate monocytes and facilitate their recruitment to atherosclerotic sites. Consequently, understanding the changes platelet releasates induce in monocyte membrane proteins is critical. We studied the glyco-proteome changes of THP-1 monocytic cells affected by LPA- or thrombin-induced platelet releasates. We employed lectin affinity chromatography combined with filter aided sample preparation to achieve high glyco- and membrane protein and protein sequence coverage. Using stable isotope labeling by amino acids in cell culture, we quantified 1715 proteins, including 852 membrane and 500 glycoproteins, identifying the up-regulation of multiple proteins involved in monocyte extracellular matrix binding and transendothelial migration. Flow cytometry indicated expression changes of integrin α5, integrin β1, PECAM-1, and PSGL-1. The observed increase in monocyte adhesion to fibronectin was determined to be mediated by the up-regulation of very late antigen 5 via a P-selectin-PSGL-1 independent mechanism. This novel aspect could be validated on CD14+ human primary monocytes, highlighting the benefits of the improved enrichment method regarding high membrane protein coverage and reliable quantification.

  17. External quality assessment of platelet disorder investigations: results of international surveys on diagnostic tests for dense granule deficiency and platelet aggregometry interpretation.

    Science.gov (United States)

    Hayward, Catherine P M; Moffat, Karen A; Plumhoff, Elizabeth; Timleck, Marnie; Hoffman, Suzanne; Spitzer, Ernie; Van Cott, Elizabeth M; Meijer, Piet

    2012-09-01

    The quality of platelet aggregation and dense granule deficiency testing is important for diagnosing platelet function disorders. After a successful pilot exercise on diagnosing platelet dense granule deficiency by electron microscopy (EM), the North American Specialized Coagulation Laboratory Association (NASCOLA) has launched regular external quality assurance (EQA) for dense granule EM, as well as for the interpretation of platelet aggregation findings. EQA records were analyzed to assess performance. For EM EQA, between 2009 and 2011, there was excellent performance in distinguishing normal from dense granule-deficient samples and good (>70%) agreement on classifying most electron dense structures in platelets. For aggregation EQA, some normal variants were misclassified and overall case interpretations were more acceptable for rare disorders than for common findings. NASCOLA experiences with these EQAs indicate that there is a need to improve the quality of platelet disorder evaluations. For aggregometry interpretations, deficits in performance could be addressed by translating guideline recommendations into practice.

  18. A biomimetic peptide fluorosurfactant polymer for endothelialization of ePTFE with limited platelet adhesion

    OpenAIRE

    Larsen, Coby C.; Kligman, Faina; Tang, Chad; KOTTKE-MARCHANT, KANDICE; Marchant, Roger E.

    2007-01-01

    Endothelialization of expanded polytetrafluoroethylene (ePTFE) has the potential to improve long-term patency for small-diameter vascular grafts. Successful endothelialization requires ePTFE surface modification to permit cell attachment to this otherwise non-adhesive substrate. We report here on a peptide fluorosurfactant polymer (FSP) biomimetic construct that promotes endothelial cell (EC)-selective attachment, growth, shear stability, and function on ePTFE. The peptide FSP consists of a f...

  19. Analysis of the nonlinear behavior of adhesives in bonded assemblies - Comparison of TAST and Arcan tests

    OpenAIRE

    Cognard, J; Creac' Hcadec, R; Sohier, L; Davies, Peter

    2008-01-01

    This paper describes a study in which the shear behavior of a structural epoxy adhesive has been measured using the standard thick adherend shear test (TAST) specimen and a modified Arcan test A. numerical study of the TAST test taking into account the nonlinear behavior of the adhesive and the finite deformations of the adhesive joint, shows that there is a localization of plastic zones close to the adhesive-substrate interface near the free edge of the adhesive. Experimental tests carried o...

  20. The effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative peritoneal adhesion formation in rats.

    Science.gov (United States)

    Makarchian, Hamid Reza; Kasraianfard, Amir; Ghaderzadeh, Pezhman; Javadi, Seyed Mohammad Reza; Ghorbanpoor, Manoochehr

    2017-01-01

    To assess the effectiveness of heparin, platelet-rich plasma (PRP), and silver nanoparticles on prevention of postoperative adhesion in animal models. Sixty males Albino Wistar rats aged 5 to 6 weeks were classified into five groups receiving none, heparin, PRP, silver nanoparticles, PRP plus silver nanoparticles intraperitoneally. After 2 weeks, the animals underwent laparotomy and the damaged site was assessed for peritoneal adhesions severity. The mean severity scores were 2.5 ± 0.9, 2.16 ± 0.7, 1.5 ± 0.5, 2.66 ± 0.88, and 2.25 ± 0.62 in the control, heparin, PRP, silver and PRP plus silver groups, respectively with significant intergroup difference (p = 0.004). The highest effective material for preventing adhesion formation was PRP followed by heparin and PRP plus silver. Moreover, compared to the controls, only use of PRP was significantly effective, in terms of adhesion severity (p = 0.01) . Platelet-rich plasma alone may have the highest efficacy for preventing postoperative peritoneal adhesions in comparison with heparin, silver nanoparticles and PRP plus silver nanoparticles.

  1. Shear and Thermal Testing of Adhesives for VELO Upgrade

    CERN Document Server

    De Capua, Stefano; Klaver, Suzanne; Parkes, Chris; Rodriguez Perez, Pablo; Shtipliyski, Antoni; Stelmasiak, Guy James

    2016-01-01

    As part of the R&D process of the LHCb VELO Upgrade, a study has been performed on the thermal and mechanical performance of the adhesives Stycast 2850FT, 3M 9461P, and Araldite 2011. One or more of these adhesives could be used to attach the ASICs and hybrids to the microchannel cooling substrate. Samples were irradiated at up to the maximum dose expected at the upgrade. Shear tests of the samples were made and a suitable performance obtained from all glues. Some failures were encountered with Stycast 2850FT glued samples and this is attributed to the sample preparation. The relative thermal conductivities of the adhesives were also determined by measuring the relative temperature difference across a glued joint while one side is heated.

  2. New aliphatic glycerophosphoryl-containing polyurethanes: synthesis, platelet adhesion and elution cytotoxicity studies.

    Science.gov (United States)

    Acetti, Daniela; D'Arrigo, Paola; Giordano, Carmen; Macchi, Piero; Servi, Stefano; Tessaro, Davide

    2009-04-01

    in this study new poly(ether)urethanes (PeUs) based on aliphatic diisocyanates were synthesized with phospholipid-like residues as chain extenders. The primary objective was to prepare new polyurethanes from diisocyanates that are less toxic than the aromatic ones widely used in medical-grade polyurethanes, in order to investigate the effect of the different aromatic or aliphatic hard segment content on the final properties of the materials. Some glycerophospho residues were simultaneously introduced to enhance the hemocompatibility of these materials. Polymers were prepared by a conventional two-step solution polymerization procedure using hexamethylene diisocyanate (HDi) and dodecametilendiisocyanate (DDi) and poly(1,4-butanediol) with molecular weight 1000 to form prepolymers, which were subsequently polymerized with 1-glycerophosphorylcholine (1-GPC) or glycerophosphorylserine (GPS) to act as chain extenders. The reference polymers bearing 1,4-butandiol (BD) were also synthesized. The polymers obtained were characterized by fourier transform infrared spectroscopy (fT-iR), nuclear magnetic resonance (1H nmR), and differential scanning calorimetry (DSC). The hemocompatibility of synthesized segmented polyurethanes was preliminarily investigated by platelet-rich plasma contact studies and related scanning electron microscopy (Sem) photographs as well as by cell viability assay after cell exposure to material elutions to assess the effect of any toxic leachables coming out from the samples. Two of the polymers gave interesting results, suggesting the desirability of further investigation into their possible use in biomedical devices.

  3. Staphylococcal SSL5 Binding to Human Leukemia Cells Inhibits Cell Adhesion to Endothelial Cells and Platelets

    Directory of Open Access Journals (Sweden)

    Annemiek M. E. Walenkamp

    2010-01-01

    Full Text Available Bacterial proteins provide promising tools for novel anticancer therapies. Staphylococcal superantigen-like 5 (SSL5 was recently described to bind P-selectin glycoprotein ligand-1 (PSGL-1 on leukocytes and to inhibit neutrophil rolling on a P-selectin surface. As leukocytes and tumor cells share many characteristics in migration and dissemination, we explored the potential of SSL5 as an antagonist of malignant cell behavior. Previously, it was demonstrated that rolling of human HL-60 leukemia cells on activated endothelial cells was mediated by P-selectin. In this study, we show that SSL5 targets HL-60 cells. Binding of SSL5 was rapid and without observed toxicity. Competition of SSL5 with the binding of three anti-PSGL-1 antibodies and P-selectin to HL-60 cells identified PSGL-1 as the ligand on HL-60 cells. Presence of sialyl Lewis x epitopes on PSGL-1 was crucial for its interaction with SSL5. Importantly, SSL5 not only inhibited the interaction of HL-60 cells with activated endothelial cells but also with platelets, which both play an important role in growth and metastasis of cancers. These data support the concept that SSL5 could be a lead in the search for novel strategies against hematological malignancies.

  4. The Schwickerath adhesion test: A fracture mechanics analysis.

    Science.gov (United States)

    Schneider, G A; Swain, M V

    2015-08-01

    The Schwickerath three point bending adhesion test is the basis of the International Standard ISO 9693:1999 procedure for assessing porcelain bonding to metals [1]. It has also been used to evaluate the adhesion of porcelain to zirconia. The purpose of this paper is a fracture mechanics analysis of this test, which allows determination of the crack-length load-displacement and toughness dependence of cracks extending along or near the interface. Linear elastic mechanics is used to develop expressions for the strain energy and compliance of Schwickerath geometry specimens as a function of crack extension along or near the interface. From the derivative of the compliance as a function of crack growth the strain energy release rate (G, N/m) is determined. The energy release rate for interface crack extension of Schwickerath geometry specimens is determined. It is found that a simple relationship between the minima of the force-displacement response and the strain energy release rate G exists. Further development enables the predicted force-displacement response as a function of crack length to be derived for different values of G. Experimental results of porcelain bonded to zirconia with and without notches of various lengths machined along the interface verify the expressions and analysis developed. With the fracture mechanics analysis developed in this paper it is possible to determine the quality of adhesion in Schwickerath specimens by the interface toughness in addition to the nominal interface shear bond strength. As the toughness of brittle materials has much less scatter than its strength, the interface toughness characterization of the adhesion should allow for a better distinction between the adhesion quality of bonding. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  5. Surface modification of CoCr alloy using varying concentrations of phosphoric and phosphonoacetic acids: albumin and fibrinogen adsorption, platelet adhesion, activation, and aggregation studies.

    Science.gov (United States)

    Thiruppathi, Eagappanath; Larson, Mark K; Mani, Gopinath

    2015-01-01

    CoCr alloy is commonly used in various cardiovascular medical devices for its excellent physical and mechanical properties. However, the formation of blood clots on the alloy surfaces is a serious concern. This research is focused on the surface modification of CoCr alloy using varying concentrations (1, 25, 50, 75, and 100 mM) of phosphoric acid (PA) and phosphonoacetic acid (PAA) to generate various surfaces with different wettability, chemistry, and roughness. Then, the adsorption of blood plasma proteins such as albumin and fibrinogen and the adhesion, activation, and aggregation of platelets with the various surfaces generated were investigated. Contact angle analysis showed PA and PAA coatings on CoCr provided a gradient of hydrophilic surfaces. FTIR showed PA and PAA were covalently bound to CoCr surface and formed different bonding configurations depending on the concentrations of coating solutions used. AFM showed the formation of homogeneous PA and PAA coatings on CoCr. The single and dual protein adsorption studies showed that the amount of albumin and fibrinogen adsorbed on the alloy surfaces strongly depend on the type of PA and PAA coatings prepared by different concentrations of coating solutions. All PA coated CoCr showed reduced platelet adhesion and activation when compared to control CoCr. Also, 75 and 100 mM PA-CoCr showed reduced platelet aggregation. For PAA coated CoCr, no significant difference in platelet adhesion and activation was observed between PAA coated CoCr and control CoCr. Thus, this study demonstrated that CoCr can be surface modified using PA for potentially reducing the formation of blood clots and improving the blood compatibility of the alloy.

  6. Determination of carbon fiber adhesion to thermoplastic polymers using the single fiber/matrix tensile test

    Science.gov (United States)

    Bascom, W. D.; Cordner, L. W.; Hinkley, J. L.; Johnston, N. J.

    1986-01-01

    The single fiber adhesion shear test has been adapted to testing the adhesion between carbon fiber and thermoplastic polymers. Tests of three thermoplastics, polycarbonate, polyphenylene oxide and polyetherimide indicate the shear adhesion strength is significantly less than of an epoxy polymer to the same carbon fiber.

  7. The clinical usefulness of the platelet aggregation test for the diagnosis of heparin-induced thrombocytopenia

    NARCIS (Netherlands)

    Chong, B H; Burgess, J; Ismail, F

    1993-01-01

    The platelet aggregation test is widely used for the diagnosis of heparin-induced thrombocytopenia (HIT), a potentially serious complication of heparin therapy. We have evaluated its sensitivity and specificity in comparison with those of the 14C-serotonin release test. The sensitivity of the platel

  8. What's new in using platelet research? To unravel thrombopathies and other human disorders.

    Science.gov (United States)

    Freson, Kathleen; Labarque, Veerle; Thys, Chantal; Wittevrongel, Christine; Geet, Chris Van

    2007-12-01

    This review on platelet research focuses on defects of adhesion, cytoskeletal organisation, signal transduction and secretion. Platelet defects can be studied by different laboratory platelet functional assays and morphological studies. Easy bruising or a suspected platelet-based bleeding disorder is of course the most obvious reason to test the platelet function in a patient. However, nowadays platelet research also contributes to our understanding of human pathology in other disciplines such as neurology, nephrology, endocrinology and metabolic diseases. Apart from a discussion on classical thrombopathies, this review will also deal with the less commonly known relation between platelet research and disorders with a broader clinical phenotype. Classical thrombopathies involve disorders of platelet adhesion such as Glanzmann thrombastenia and Bernard-Soulier syndrome, defective G protein signalling diseases with impaired phospholipase C activation, and abnormal platelet granule secretion disorders such as gray platelet disorder and delta-storage pool disease. Other clinical symptoms besides a bleeding tendency have been described in MYH9-related disorders and Duchenne muscular dystrophy due to adhesion defects, and also in disorders of impaired Gs signalling, in Hermansky Pudlack disease and Chediak Higashi disease with abnormal secretion. Finally, platelet research can also be used to unravel novel mechanisms involved in many neurological disorders such as depression and autism with only a subclinical platelet defect.

  9. What’s new in using platelet research? To unravel thrombopathies and other human disorders

    Science.gov (United States)

    Labarque, Veerle; Thys, Chantal; Wittevrongel, Christine; Geet, Chris Van

    2007-01-01

    This review on platelet research focuses on defects of adhesion, cytoskeletal organisation, signal transduction and secretion. Platelet defects can be studied by different laboratory platelet functional assays and morphological studies. Easy bruising or a suspected platelet-based bleeding disorder is of course the most obvious reason to test the platelet function in a patient. However, nowadays platelet research also contributes to our understanding of human pathology in other disciplines such as neurology, nephrology, endocrinology and metabolic diseases. Apart from a discussion on classical thrombopathies, this review will also deal with the less commonly known relation between platelet research and disorders with a broader clinical phenotype. Classical thrombopathies involve disorders of platelet adhesion such as Glanzmann thrombastenia and Bernard-Soulier syndrome, defective G protein signalling diseases with impaired phospholipase C activation, and abnormal platelet granule secretion disorders such as gray platelet disorder and delta-storage pool disease. Other clinical symptoms besides a bleeding tendency have been described in MYH9-related disorders and Duchenne muscular dystrophy due to adhesion defects, and also in disorders of impaired Gs signalling, in Hermansky Pudlack disease and Chediak Higashi disease with abnormal secretion. Finally, platelet research can also be used to unravel novel mechanisms involved in many neurological disorders such as depression and autism with only a subclinical platelet defect. PMID:17619901

  10. Gender, Race, and Diet Affect Platelet Function Tests in Normal Subjects Contributing to a High Rate of Abnormal Results

    OpenAIRE

    Miller, Connie H.; Rice, Anne S.; Garrett, Katherine; Stein, Sidney F.

    2014-01-01

    To assess sources of variability in platelet function tests in normal subjects, 64 healthy young adults were tested on 2–6 occasions at 2 week intervals using 4 methods: platelet aggregation (AGG) in platelet-rich plasma (PRP) in the Bio/Data PAP-4 Aggregometer (BD) and Chrono-Log Lumi-Aggregometer (CL); and AGG in whole blood (WB) in the CL and Multiplate Platelet Function Analyzer (MP), with ATP release (REL) in CL-PRP and CL-WB. Food and medication exposures were recorded prospectively for...

  11. Scalability Test of multiscale fluid-platelet model for three top supercomputers

    Science.gov (United States)

    Zhang, Peng; Zhang, Na; Gao, Chao; Zhang, Li; Gao, Yuxiang; Deng, Yuefan; Bluestein, Danny

    2016-07-01

    We have tested the scalability of three supercomputers: the Tianhe-2, Stampede and CS-Storm with multiscale fluid-platelet simulations, in which a highly-resolved and efficient numerical model for nanoscale biophysics of platelets in microscale viscous biofluids is considered. Three experiments involving varying problem sizes were performed: Exp-S: 680,718-particle single-platelet; Exp-M: 2,722,872-particle 4-platelet; and Exp-L: 10,891,488-particle 16-platelet. Our implementations of multiple time-stepping (MTS) algorithm improved the performance of single time-stepping (STS) in all experiments. Using MTS, our model achieved the following simulation rates: 12.5, 25.0, 35.5 μs/day for Exp-S and 9.09, 6.25, 14.29 μs/day for Exp-M on Tianhe-2, CS-Storm 16-K80 and Stampede K20. The best rate for Exp-L was 6.25 μs/day for Stampede. Utilizing current advanced HPC resources, the simulation rates achieved by our algorithms bring within reach performing complex multiscale simulations for solving vexing problems at the interface of biology and engineering, such as thrombosis in blood flow which combines millisecond-scale hematology with microscale blood flow at resolutions of micro-to-nanoscale cellular components of platelets. This study of testing the performance characteristics of supercomputers with advanced computational algorithms that offer optimal trade-off to achieve enhanced computational performance serves to demonstrate that such simulations are feasible with currently available HPC resources.

  12. Crosstalk between Protease-activated Receptor 1 and Platelet-activating Factor Receptor Regulates Melanoma Cell Adhesion Molecule (MCAM/MUC18) Expression and Melanoma Metastasis*

    Science.gov (United States)

    Melnikova, Vladislava O.; Balasubramanian, Krishnakumar; Villares, Gabriel J.; Dobroff, Andrey S.; Zigler, Maya; Wang, Hua; Petersson, Frederik; Price, Janet E.; Schroit, Alan; Prieto, Victor G.; Hung, Mien-Chie; Bar-Eli, Menashe

    2009-01-01

    The cellular and molecular pathways that regulate platelet activation, blood coagulation, and inflammation are emerging as critical players in cancer progression and metastasis. Here, we demonstrate a novel signaling mechanism whereby protease-activated receptor 1 (PAR1) mediates expression of melanoma cell adhesion molecule MCAM/MUC18 (MUC18), a critical marker of melanoma metastasis, via activation of platelet-activating factor receptor (PAFR) and cAMP-responsive element-binding protein (CREB). We found that PAR1 silencing with small hairpin RNA inhibits MUC18 expression in metastatic melanoma cells by inhibiting CREB phosphorylation, activity, and binding to the MUC18 promoter. We further demonstrate that the PAF/PAFR pathway mediates MUC18 expression downstream of PAR1. Indeed, PAR1 silencing down-regulates PAFR expression and PAF production, PAFR silencing blocks MUC18 expression, and re-expression of PAFR in PAR1-silenced cells rescues MUC18 expression. We further demonstrate that the PAR1-PAFR-MUC18 pathway mediates melanoma cell adhesion to microvascular endothelial cells, transendothelial migration, and metastatic retention in the lungs. Rescuing PAFR expression in PAR1-silenced cells fully restores metastatic phenotype of melanoma, indicating that PAFR plays critical role in the molecular mechanism of PAR1 action. Our results link the two pro-inflammatory G-protein-coupled receptors, PAR1 and PAFR, with the metastatic dissemination of melanoma and suggest that PAR1, PAFR, and MUC18 are attractive therapeutic targets for preventing melanoma metastasis. PMID:19703903

  13. Towards Personalized Medicine Based on Platelet Function Testing for Stent Thrombosis Patients

    Directory of Open Access Journals (Sweden)

    Thea Cornelia Godschalk

    2012-01-01

    Full Text Available Stent thrombosis (ST is a severe and feared complication of coronary stenting. Patients who have suffered from ST are usually treated according to the “one-size-fits-all” dosing regimen of aspirin and clopidogrel. Many ST patients show high on-treatment platelet reactivity (HPR despite this antiplatelet therapy (APT. It has been shown that HPR is a risk factor for major adverse cardiac events. Therefore, ST patients with HPR are at a high risk for recurrent atherothrombotic events. New insights into the variable response to clopidogrel and the advent of stronger P2Y12 inhibitors prasugrel and ticagrelor have changed the attention from a fixed APT treatment strategy towards “personalized APT strategies.” Strategies can be based on platelet function testing, which gives insight into the overall response of a patient to APT. At our outpatient ST clinic, we practice personalized APT based on platelet function testing to guide the cardiologist to a presumed optimal antiplatelet treatment of ST patients. Beside results of platelet function testing, comedication, clinical characteristics, and genetics have to be considered to decide on personalized APT. Ongoing studies have yet to reveal the optimal personalized APT strategy for cardiologists to prevent their patients from atherothrombotic and bleeding events.

  14. Blister Test for Measurements of Adhesion and Adhesion Degradation of Organic Polymers on AA2024-T3

    Science.gov (United States)

    Rincon Troconis, Brendy Carolina

    A key parameter for the performance of corrosion protective coatings applied to metals is adhesion. Surface preparation prior to coating application is known to be critical, but there is a lack of understanding of what controls adhesion. Numerous techniques have been developed in the last decades to measure the adhesion strength of coatings to metals. Nonetheless, they are generally non-quantitative, non-reproducible, performed in dry conditions, or overestimate adhesion. In this study, a quantitative and reproducible technique, the Blister Test (BT), is used. The BT offers the ability to study the effects of a range of parameters, including the presence or absence of a wetting liquid, and simulates the stress situation in the coating/substrate interface. The effects of roughness and surface topography were studied by the BT and Optical Profilometry, using AA2024-T3 substrates coated with polyvinyl butyral (PVB). Random abrasion generated a surface with lower average roughness than aligned abrasion due to the continual cross abrasion of the grooves. The BT could discern the effects of different mechanical treatments. An adhesion strength indicator was defined and found to be a useful parameter. The effectiveness of standard adhesion techniques such as ASTM D4541 (Pull-off Test) and ASTM D3359 (Tape Test) was compared to the BT. Also, different attempts to measure adhesion and adhesion degradation of organic polymers to AA2024-T3 were tested. The pull-off test does not produce adhesive failure across the entire interface, while the tape test is a very qualitative technique and does not discern between the effects of different coating systems on the adhesion performance. The BT produces adhesive failure of the primer studied, is very reproducible, and is able to rank different coating systems. Therefore, it was found to be superior to the others. The approaches tested for adhesion degradation were not aggressive enough to have a measurable effect. The effects of

  15. A comparison of six major platelet functional tests to assess the impact of carbon nanomaterials on platelet function: a practical guide.

    Science.gov (United States)

    Laloy, Julie; Mullier, François; Alpan, Lutfiye; Mejia, Jorge; Lucas, Stéphane; Chatelain, Bernard; Toussaint, Olivier; Masereel, Bernard; Rolin, Stéphanie; Dogné, Jean-Michel

    2014-03-01

    The study of the haemocompatibility of nanomaterials that could be in contact with blood (e.g. nanoparticle (NP)-based drug-delivery system) is of major importance. The primary objective of this study was to compare the ability of six platelet functional tests to assess the impact of NPs on platelet function. The secondary objective was to determine an accurate and reliable screening test to measure the potential impact of NPs on primary haemostasis whatever their physicochemical properties. Four types of carbon NPs (carbon black, fullerenes, single-walled carbon nanotubes and multi-walled carbon nanotubes) were investigated on six platelet function tests: light transmission aggregometry, whole-blood impedance aggregometry, platelet function analyser-100 (PFA-100®) and Cone-and-Plate(let) analyser (Impact-R®), transmission- and field emission gun scanning electron microscopy (FEG-SEM). We considered that Impact-R® supported by FEG-SEM is the reference method to investigate the potential impact of NPs on platelet function.

  16. A Study of Platelet Inhibition, Using a 'Point of Care' Platelet Function Test, following Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction [PINPOINT-PPCI].

    Directory of Open Access Journals (Sweden)

    Thomas W Johnson

    Full Text Available Rapid coronary recanalization following ST-elevation myocardial infarction (STEMI requires effective anti-platelet and anti-thrombotic therapies. This study tested the impact of door to end of procedure ('door-to-end' time and baseline platelet activity on platelet inhibition within 24hours post-STEMI.108 patients, treated with prasugrel and procedural bivalirudin, underwent Multiplate® platelet function testing at baseline, 0, 1, 2 and 24hours post-procedure. Major adverse cardiac events (MACE, bleeding and stent thrombosis (ST were recorded. Baseline ADP activity was high (88.3U [71.8-109.0], procedural time and consequently bivalirudin infusion duration were short (median door-to-end time 55minutes [40-70] and infusion duration 30minutes [20-42]. Baseline ADP was observed to influence all subsequent measurements of ADP activity, whereas door-to-end time only influenced ADP immediately post-procedure. High residual platelet reactivity (HRPR ADP>46.8U was observed in 75% of patients immediately post-procedure and persisted in 24% of patients at 2hours. Five patients suffered in-hospital MACE (4.6%. Acute ST occurred in 4 patients, all were <120mins post-procedure and had HRPR. No significant bleeding was observed. In a post-hoc analysis, pre-procedural morphine use was associated with significantly higher ADP activity following intervention.Baseline platelet function, time to STEMI treatment and opiate use all significantly influence immediate post-procedural platelet activity.

  17. Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives.

    Science.gov (United States)

    Kozowyk, P R B; Langejans, G H J; Poulis, J A

    2016-01-01

    The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony) and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives.

  18. Lap Shear and Impact Testing of Ochre and Beeswax in Experimental Middle Stone Age Compound Adhesives.

    Directory of Open Access Journals (Sweden)

    P R B Kozowyk

    Full Text Available The production of compound adhesives using disparate ingredients is seen as some of the best evidence of advanced cognition outside of the use of symbolism. Previous field and laboratory testing of adhesives has shown the complexities involved in creating an effective Middle Stone Age glue using Acacia gum. However, it is currently unclear how efficient different adhesive recipes are, how much specific ingredients influence their performance, and how difficult it may have been for those ingredients to be combined to maximum effect. We conducted a series of laboratory-based lap shear and impact tests, following modern adhesion testing standards, to determine the efficacy of compound adhesives, with particular regard to the ingredient ratios. We tested rosin (colophony and gum adhesives, containing additives of beeswax and ochre in varying ratios. During both lap shear and impact tests compound rosin adhesives performed better than single component rosin adhesives, and pure acacia gum was the strongest. The large difference in performance between each base adhesive and the significant changes in performance that occur due to relatively small changes in ingredient ratios lend further support to the notion that high levels of skill and knowledge were required to consistently produce the most effective adhesives.

  19. Expression, purification, and analysis of three recombinant ECD disintegrins (r-colombistatins) from P-III class snake venom metalloproteinases affecting platelet aggregation and SK-MEL-28 cell adhesion.

    Science.gov (United States)

    Suntravat, Montamas; Helmke, Thomas J; Atphaisit, Chairat; Cuevas, Esteban; Lucena, Sara E; Uzcátegui, Nestor L; Sánchez, Elda E; Rodriguez-Acosta, Alexis

    2016-11-01

    Crotalid venoms are rich sources of components that affect the hemostatic system. Snake venom metalloproteinases are zinc-dependent enzymes responsible for hemorrhage that also interfere with hemostasis. The disintegrin domain is a part of snake venom metalloproteinases, which involves the binding of integrin receptors. Integrins play an essential role in cancer survival and invasion, and they have been major targets for drug development and design. Both native and recombinant disintegrins have been widely investigated for their anti-cancer activities in biological systems as well as in vitro and in vivo systems. Here, three new cDNAs encoding ECD disintegrin-like domains of metalloproteinase precursor sequences obtained from a Venezuelan mapanare (Bothrops colombiensis) venom gland cDNA library have been cloned. Three different N- and C-terminal truncated ECD disintegrin-like domains of metalloproteinases named colombistatins 2, 3, and 4 were amplified by PCR, cloned into a pGEX-4T-1 vector, expressed in Escherichia coli BL21, and tested for inhibition of platelet aggregation and inhibition of adhesion of human skin melanoma (SK-Mel-28) cancer cell lines on collagen I. Purified recombinant colombistatins 2, 3, and 4 were able to inhibit ristocetin- and collagen-induced platelet aggregation. r-Colombistatins 2 showed the most potent inhibiting SK-Mel-28 cancer cells adhesion to collagen. These results suggest that colombistatins may have utility in the development of therapeutic tools in the treatment of melanoma cancers and also thrombotic diseases. Copyright © 2016. Published by Elsevier Ltd.

  20. Detection and characterization of immune complexes by the platelet aggregation test. II. Circulating complexes

    Science.gov (United States)

    Myllylä, G.; Vaheri, A.; Penttinen, K.

    1971-01-01

    Model experiments with preformed antigen–antibody complexes have shown that the platelet aggregation test can be used to characterize immune complexes. The platelet aggregating activity of four sera behaved like antigen–antibody complexes with respect to the effect of added antigen, added antibody and sedimentation in density gradient centrifugation. Two of the sera were from patients with fever of unknown origin. The findings suggest that the two sera contained circulating immune complexes which had both measles hyperimmunization induced and normal specificities. The serum of a patient with fatal subacute hepatitis seemed to contain immune complexes with Australia antigen. It was also positive in many of the autoimmunity tests. One of the sera was from a patient with haemorrhagic varicella in the acute phase of the disease. The patient had received large amounts of γ-globulin. The results suggested the transient presence of circulating immune complexes with varicella specificity. PMID:4102701

  1. Nondestructive testing of adhesive bonds by nuclear quadrupole resonance method

    Science.gov (United States)

    Hewitt, R. R.

    1971-01-01

    Inert, strain sensitive tracer, cuprous oxide, added to polymeric adhesive ensures sufficiently large signal to noise ratio in NQR system output. Method is successful, provided that RF-transparent structural materials are used between modified adhesive and probe of NQR spectrometer.

  2. Preparation and testing of plant seed meal-based wood adhesives.

    Science.gov (United States)

    He, Zhongqi; Chapital, Dorselyn C

    2015-01-01

    Recently, the interest in plant seed meal-based products as wood adhesives has steadily increased, as these plant raw materials are considered renewable and environment-friendly. These natural products may serve as alternatives to petroleum-based adhesives to ease environmental and sustainability concerns. This work demonstrates the preparation and testing of the plant seed-based wood adhesives using cottonseed and soy meal as raw materials. In addition to untreated meals, water washed meals and protein isolates are prepared and tested. Adhesive slurries are prepared by mixing a freeze-dried meal product with deionized water (3:25 w/w) for 2 hr. Each adhesive preparation is applied to one end of 2 wood veneer strips using a brush. The tacky adhesive coated areas of the wood veneer strips are lapped and glued by hot-pressing. Adhesive strength is reported as the shear strength of the bonded wood specimen at break. Water resistance of the adhesives is measured by the change in shear strength of the bonded wood specimens at break after water soaking. This protocol allows one to assess plant seed-based agricultural products as suitable candidates for substitution of synthetic-based wood adhesives. Adjustments to the adhesive formulation with or without additives and bonding conditions could optimize their adhesive properties for various practical applications.

  3. Mode i testing of adhesive joints: Experimental part

    Energy Technology Data Exchange (ETDEWEB)

    Noekkentved, A. [Risoe National Lab., Materials Research Dept., Roskilde (Denmark)

    2006-07-01

    The J integral approach for adhesive bonded joints is particularly attractive for modelling failure process zones. The J integral can be established by a general approach and experimental measurements. By this method, the cohesive law of the adhesive in question can be obtained. Polymer joints with different mechanical properties and geometries are considered in order to study the effect of plasticity within the bond of ductile adhesives, since this can enhance their fracture toughness. The cohesive laws established will be implemented in numerical models - more in part 2. The objective of the project is to establish and demonstrate methods for modelling the mechanical behaviour of adhesively bonded joints in polymer matrix composite materials. Fracture mechanics will assist to establish the relevant framework for their mechanical performance. The main results from this study are expected to be part in a set of recommendations regarding production parameters, design, inspection and control of adhesively bonded joints. (au)

  4. Role of focal adhesion tyrosine kinases in GPVI-dependent platelet activation and reactive oxygen species formation.

    Directory of Open Access Journals (Sweden)

    Naadiya Carrim

    Full Text Available We have previously shown the presence of a TRAF4/p47phox/Hic5/Pyk2 complex associated with the platelet collagen receptor, GPVI, consistent with a potential role of this complex in GPVI-dependent ROS formation. In other cell systems, NOX-dependent ROS formation is facilitated by Pyk2, which along with its closely related homologue FAK are known to be activated and phosphorylated downstream of ligand binding to GPVI.To evaluate the relative roles of Pyk2 and FAK in GPVI-dependent ROS formation and to determine their location within the GPVI signaling pathway.Human and mouse washed platelets (from WT or Pyk2 KO mice were pre-treated with pharmacological inhibitors targeting FAK or Pyk2 (PF-228 and Tyrphostin A9, respectively and stimulated with the GPVI-specific agonist, CRP. FAK, but not Pyk2, was found to be essential for GPVI-dependent ROS production and aggregation. Subsequent human platelet studies with PF-228 confirmed FAK is essential for GPVI-mediated phosphatidylserine exposure, α-granule secretion (P-selectin (CD62P surface expression and integrin αIIbβ3 activation. To determine the precise location of FAK within the GPVI pathway, we analyzed the effect of PF-228 inhibition in CRP-stimulated platelets in conjunction with immunoprecipitation and pulldown analysis to show that FAK is downstream of Lyn, Spleen tyrosine kinase (Syk, PI3-K and Bruton's tyrosine kinase (Btk and upstream of Rac1, PLCγ2, Ca2+ release, PKC, Hic-5, NOX1 and αIIbβ3 activation.Overall, these data suggest a novel role for FAK in GPVI-dependent ROS formation and platelet activation and elucidate a proximal signaling role for FAK within the GPVI pathway.

  5. Development of North American consensus guidelines for medical laboratories that perform and interpret platelet function testing using light transmission aggregometry.

    Science.gov (United States)

    Hayward, Catherine P M; Moffat, Karen A; Raby, Anne; Israels, Sara; Plumhoff, Elizabeth; Flynn, Greg; Zehnder, James L

    2010-12-01

    Platelet function testing is important for the diagnostic evaluation of common and rare bleeding disorders. Our study goals were to promote best practices and reduce unnecessary testing variances by developing North American guidelines on platelet function testing. Guidelines were developed by consensus for expert recommendations (minimum level for approval, 70%) that included recommendations on the evaluation and interpretation of light transmission platelet aggregometry (LTA). To assess consensus, medical opinions on recommendations were gathered from diagnostic laboratories that perform LTA, in collaboration with the Quality Management Program-Laboratory Services (QMP-LS) in Ontario, Canada (10 laboratories), and the North American Specialized Coagulation Laboratory Association (NASCOLA; 47 laboratories, 5 overlapping the QMP-LS group). Adequate consensus was achieved for all and 89% of recommendations for the QMP-LS and NASCOLA groups, respectively. The recommendations adopted provide North American laboratories with additional guidance on platelet function testing, including how to interpret LTA abnormalities.

  6. Adhesion, activation, and aggregation of blood platelets and biofilm formation on the surfaces of titanium alloys Ti6Al4V and Ti6Al7Nb.

    Science.gov (United States)

    Walkowiak-Przybyło, M; Klimek, L; Okrój, W; Jakubowski, W; Chwiłka, M; Czajka, A; Walkowiak, B

    2012-03-01

    Titanium alloys are still on the top list of fundamental materials intended for dental, orthopedics, neurological, and cardiovascular implantations. Recently, a special attention has been paid to vanadium-free titanium alloy, Ti6Al7Nb, that seems to represent higher biocompatibility than traditional Ti6Al4V alloy. Surprisingly, these data are not thoroughly elaborated in the literature; particularly there is a lack of comparative experiments conducted simultaneously and at the same conditions. Our study fills these shortcomings in the field of blood contact and microbiological colonization. To observe platelets adhesion and biofilm formation on the surfaces of compared titanium alloys, fluorescence microscope Olympus GX71 and scanning electron microscope HITACHI S-3000N were used. Additionally, flow cytometry analysis of platelets aggregation and activation in the whole blood after contact with sample surface, as an essential tool for biomaterial thrombocompatibility assessment, was proposed. As a result of our study it was demonstrated that polished surfaces of Ti6Al7Nb and Ti6Al4V alloys after contact with whole citrated blood and E. coli bacterial cells exhibit a considerable difference. Overall, it was established that Ti6Al4V has distinct tendency to higher thrombogenicity, more excessive bacterial biofilm formation and notable cytotoxic properties in comparison to Ti6Al7Nb. However, we suggest these studies should be extended for other types of cells and biological objects.

  7. A method for predicting critical load evaluating adhesion of coatings in scratch testing

    Institute of Scientific and Technical Information of China (English)

    CHEN Xi-fang(陈溪芳); YAN Mi(严密); YANG De-ren(杨德人); HIROSE Yukio

    2003-01-01

    In this paper based on the experiment principle of evaluating adhesion property by scratch testing, the peeling mechanism of thin films is discussed by applying contact theory and surface physics theory. A mathematical model predicting the critical load is proposed for calculating critical load as determined by scratch testing. The factors for correctly evaluating adhesion of coatings according to the experimental data are discussed.

  8. Flow cytometry-based platelet function testing is predictive of symptom burden in a cohort of bleeders.

    Science.gov (United States)

    Boknäs, Niklas; Ramström, Sofia; Faxälv, Lars; Lindahl, Tomas L

    2017-09-12

    Platelet function disorders (PFDs) are common in patients with mild bleeding disorders (MBDs), yet the significance of laboratory findings suggestive of a PFD remain unclear due to the lack of evidence for a clinical correlation between the test results and the patient phenotype. Herein, we present the results from a study evaluating the potential utility of platelet function testing using whole-blood flow cytometry in a cohort of 105 patients undergoing investigation for MBD. Subjects were evaluated with a test panel comprising two different activation markers (fibrinogen binding and P-selectin exposure) and four physiologically relevant platelet agonists (ADP, PAR1-AP, PAR4-AP, and CRP-XL). Abnormal test results were identified by comparison with reference ranges constructed from 24 healthy controls or with the fifth percentile of the entire patient cohort. We found that the abnormal test results are predictive of bleeding symptom severity, and that the greatest predictive strength was achieved using a subset of the panel, comparing measurements of fibrinogen binding after activation with all four agonists with the fifth percentile of the patient cohort (p = 0.00008, hazard ratio 8.7; 95% CI 2.5-40). Our results suggest that whole-blood flow cytometry-based platelet function testing could become a feasible alternative for the investigation of MBDs. We also show that platelet function testing using whole-blood flow cytometry could provide a clinically relevant quantitative assessment of platelet-related hemostasis.

  9. Gender, Race, and Diet Affect Platelet Function Tests in Normal Subjects Contributing to a High Rate of Abnormal Results

    Science.gov (United States)

    Miller, Connie H.; Rice, Anne S.; Garrett, Katherine; Stein, Sidney F.

    2015-01-01

    Summary To assess sources of variability in platelet function tests in normal subjects, 64 healthy young adults were tested on 2–6 occasions at 2 week intervals using 4 methods: platelet aggregation (AGG) in platelet-rich plasma (PRP) in the Bio/Data PAP-4 Aggregometer (BD) and Chrono-Log Lumi-Aggregometer (CL); and AGG in whole blood (WB) in the CL and Multiplate Platelet Function Analyzer (MP), with ATP release (REL) in CL-PRP and CL-WB. Food and medication exposures were recorded prospectively for 2 weeks prior to each blood draw. At least one AGG abnormality was seen in 21% of 81 drug-free specimens with CL-PRP, 15% with CL-WB, 13% with BD-PRP, and 6% with MP-WB, increasing with inclusion of REL to 28% for CL-PRP and 30% for CL-WB. Epinephrine AGG and REL were significantly reduced in males (P<0.0001). Ristocetin AGG and collagen and thrombin REL were significantly reduced in Blacks (P<0.0001). One-third of specimens drawn following flavonoid-rich food exposures had aberrant results, compared to 8.5% of specimens without such exposures (P=0.0035). PRP tests had less intra-individual variation than WB tests. Gender, race, diet, and test system affected results of platelet function testing in healthy subjects, suggesting caution when interpreting the results of platelet function testing in patients. PMID:24617520

  10. Adhesion scratch testing - A round-robin experiment

    Science.gov (United States)

    Perry, A. J.; Valli, J.; Steinmann, P. A.

    1988-01-01

    Six sets of samples, TiN coated by chemical or physical vapor deposition methods (CVD or PVD) onto cemented carbide or high-speed steel (HSS), and TiC coated by CVD onto cemented carbide have been scratch tested using three types of commercially available scratch adhesion tester. With exception of one cemented carbide set, the reproducibility of the critical loads for any given set with a given stylus is excellent, about + or - 5 percent, and is about + or - 20 percent for different styli. Any differences in critical loads recorded for any given sample set can be attributed to the condition of the stylus (clean, new, etc.), the instrument used, the stylus itself (friction coefficient, etc.), and the sample set itself. One CVD set showed remarkably large differences in critical loads for different styli, which is thought to be related to a mechanical interaction between stylus and coating which is enhanced by a plastic deformability in the film related to the coating microstructure. The critical load for TiN on HSS increases with coating thickness, and differences in frictional conditions led to a systematic variation in the critical loads depending on the stylus used.

  11. Platelet-reactivity tests identify patients at risk of secondary cardiovascular events: a systematic review and meta-analysis.

    Science.gov (United States)

    Wisman, P P; Roest, M; Asselbergs, F W; de Groot, P G; Moll, F L; van der Graaf, Y; de Borst, G J

    2014-05-01

    Antiplatelet therapy is the standard treatment for the prevention of cardiovascular events (CVEs). High on-treatment platelet reactivity (HPR) is a risk factor for secondary CVEs in patients prescribed aspirin and/or clopidogrel. The present review and meta-analysis was aimed at assessing the ability of individual platelet-function tests to reliably identify patients at risk of developing secondary CVEs. A systematic literature search was conducted to identify studies on platelet-reactivity measurements and CVEs. The main inclusion criteria were: (i) prospective study design; (ii) study medication, including aspirin and/or clopidogrel; and (iii) a platelet-function test being performed at baseline, before follow-up started. Of 3882 identified studies, 102 (2.6%; reporting on 44 098 patients) were included in the meta-analysis. With regard to high on-aspirin platelet reactivity (HAPR), 22 different tests were discussed in 55 studies (22 441 patients). Pooled analysis showed that HAPR was diagnosed in 22.2% of patients, and was associated with an increased CVE risk (relative risk [RR] 2.09; 95% confidence interval [CI] 1.77-2.47). Eleven HAPR tests independently showed a significantly increased CVE risk in patients with HAPR as compared with those with normal on-aspirin platelet reactivity. As regards high on-clopidogrel platelet reactivity (HCPR), 59 studies (34 776 patients) discussed 15 different tests, and reported that HCPR was present in 40.4% of patients and was associated with an increased CVE risk (RR 2.80; 95% CI 2.40-3.27). Ten tests showed a significantly increased CVE risk. Patients with HPR are suboptimally protected against future cardiovascular complications. Furthermore, not all of the numerous platelet tests proved to be able to identify patients at increased cardiovascular risk. © 2014 International Society on Thrombosis and Haemostasis.

  12. Alkali treatment of microrough titanium surfaces affects macrophage/monocyte adhesion, platelet activation and architecture of blood clot formation

    Directory of Open Access Journals (Sweden)

    V Milleret

    2011-05-01

    Full Text Available Titanium implants are most commonly used for bone augmentation and replacement due to their favorable osseointegration properties. Here, hyperhydrophilic sand-blasted and acid-etched (SBA titanium surfaces were produced by alkali treatment and their responses to partially heparinized whole human blood were analyzed. Blood clot formation, platelet activation and activation of the complement system was analyzed revealing that exposure time between blood and the material surface is crucial as increasing exposure time results in higher amount of activated platelets, more blood clots formed and stronger complement activation. In contrast, the number of macrophages/monocytes found on alkali-treated surfaces was significantly reduced as compared to untreated SBA Ti surfaces. Interestingly, when comparing untreated to modified SBA Ti surfaces very different blood clots formed on their surfaces. On untreated Ti surfaces blood clots remain thin (below 15 mm, patchy and non-structured lacking large fibrin fiber networks whereas blood clots on differentiated surfaces assemble in an organized and layered architecture of more than 30 mm thickness. Close to the material surface most nucleated cells adhere, above large amounts of non-nucleated platelets remain entrapped within a dense fibrin fiber network providing a continuous cover of the entire surface. These findings might indicate that, combined with findings of previous in vivo studies demonstrating that alkali-treated SBA Ti surfaces perform better in terms of osseointegration, a continuous and structured layer of blood components on the blood-facing surface supports later tissue integration of an endosseous implant.

  13. Octadecyl Chains Immobilized onto Hyaluronic Acid Coatings by Thiol-ene "Click Chemistry" Increase the Surface Antimicrobial Properties and Prevent Platelet Adhesion and Activation to Polyurethane.

    Science.gov (United States)

    Felgueiras, Helena P; Wang, L M; Ren, K F; Querido, M M; Jin, Q; Barbosa, M A; Ji, J; Martins, M C L

    2017-03-08

    Infection and thrombus formation are still the biggest challenges for the success of blood contact medical devices. This work aims the development of an antimicrobial and hemocompatible biomaterial coating through which selective binding of albumin (passivant protein) from the bloodstream is promoted and, thus, adsorption of other proteins responsible for bacterial adhesion and thrombus formation can be prevented. Polyurethane (PU) films were coated with hyaluronic acid, an antifouling agent, that was previously modified with thiol groups (HA-SH), using polydopamine as the binding agent. Octadecyl acrylate (C18) was used to attract albumin since it resembles the circulating free fatty acids and albumin is a fatty acid transporter. Thiol-ene "click chemistry" was explored for C18 immobilization on HA-SH through a covalent bond between the thiol groups from the HA and the alkene groups from the C18 chains. Surfaces were prepared with different C18 concentrations (0, 5, 10, and 20%) and successful immobilization was demonstrated by scanning electron microscopy (SEM), water contact angle determinations, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The ability of surfaces to bind albumin selectively was determined by quartz crystal microbalance with dissipation (QCM-D). Albumin adsorption increased in response to the hydrophobic nature of the surfaces, which augmented with C18 saturation. HA-SH coating reduced albumin adsorption to PU. C18 immobilized onto HA-SH at 5% promoted selective binding of albumin, decreased Staphylococcus aureus adhesion and prevented platelet adhesion and activation to PU in the presence of human plasma. C18/HA-SH coating was established as an innovative and promising strategy to improve the antimicrobial properties and hemocompatibility of any blood contact medical device.

  14. Comparative anti-platelet and antioxidant properties of polyphenol-rich extracts from: berries of Aronia melanocarpa, seeds of grape and bark of Yucca schidigera in vitro.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara; Tomczak, Anna; Erler, Joachim; Stochmal, Anna; Oleszek, Wieslaw

    2008-02-01

    The aim of the present study was to investigate and compare the anti-platelet action of extracts from three different plants: bark of Yucca schidigera, seeds of grape and berries of Aronia melanocarpa (chokeberry). Anti-platelet action of tested extracts was compared with action of well characterized antioxidative and anti-platelet commercial monomeric polyphenol-resveratrol. The effects of extracts on platelet adhesion to collagen, collagen-induced platelet aggregation and on the production of O2-* in resting platelets and platelets stimulated by a strong platelet agonist-thrombin were studied. The in vitro experiments have shown that all three tested extracts (5-50 microg/ml) rich in polyphenols reduce platelet adhesion, aggregation and generation of O2-* in blood platelets. Comparative studies indicate that all three plant extracts were found to be more reactive in reduction of platelet processes than the solution of pure resveratrol. The tested extracts due to their anti-platelet effects may play an important role as components of human diet in prevention of cardiovascular or inflammatory diseases, where blood platelets are involved.

  15. New Experimental Sample for Shear Testing of Adhesively Bonded Assemblies

    Science.gov (United States)

    Challita, Georges; Othman, Ramzi; Guegan, Pierrick; Khalil, Khalid; Poitou, Arnaud

    In this paper, Split Hopkinson Bar technique was used to investigate the shear behaviour of adhesively bonded assemblies at high rates of loading. New sample geometry was adopted so that the compressive wave is transformed in a shear loading in the sample. Samples are conditioned at 20°C and 50% of hygrometry to eliminate any interference with temperature and humidity effects. The new technique is applied to an assembly built with a cyanoacrylate based adhesive and a metallic (Steel) adherent. They are found to be highly rate sensitive.

  16. SPECIFIC ASPECTS OF INTERACTION OF PLATELETS WITH THE HEPARINIZED MATERIALS

    Directory of Open Access Journals (Sweden)

    E.A. Nemets

    2012-01-01

    Full Text Available Comparative analysis of anticoagulant nature on medical materials testing was done. It was found that change of citrate by heparin is accompanied by significant changes in platelet adhesion and activation. This results allowed us to arrive at a conclusion about reasonability of heparin usage as anticoagulant in in vitro testing

  17. Leakage Testing for Different Adhesive Systems and Composites to ...

    African Journals Online (AJOL)

    2015-11-16

    Nov 16, 2015 ... Therefore, manufacturers declared several adhesives including a variety of ... The time required layering procedures with customary resin composites can .... measured and data were collected with Auto CAD 2000 software (Autodesk Inc., San .... International Organization for Standardization ISO TR 11405,.

  18. Prophylactic strategies for acute hemolysis secondary to plasma-incompatible platelet transfusions: correlation between qualitative hemolysin test and isohemagglutinin titration

    Directory of Open Access Journals (Sweden)

    Cinthia Silvestre Landim

    2015-08-01

    Full Text Available OBJECTIVE: Brazilian legislation has recently suggested the use of the qualitative hemolysin test instead of isohemagglutinin titers as prophylaxis for acute hemolysis related to plasma-incompatible platelet transfusions. The efficacy of this test in preventing hemolytic reactions has never been evaluated while isohemagglutinin titers have been extensively studied. The main objective of this study was to evaluate the correlation between the results of these two tests. The impact of each type of prophylaxis on the platelet inventory management and the ability of the qualitative hemolysin test to prevent red cell sensitization after the transfusion of incompatible units were also studied.METHODS: A total of 246 donor blood samples were evaluated using both isohemagglutinin titers and the qualitative hemolysin test, and the results were statistically compared. Subsequently, 600 platelet units were tested using the hemolysin assay and the percentage of units unsuitable for transfusion was compared to historical data using isohemagglutinin titers (cut-off: 100. Moreover, ten patients who received units with minor ABO incompatibilities that were negative for hemolysis according to the qualitative hemolysin test were evaluated regarding the development of hemolysis and red cell sensitization (anti-A or anti-B.RESULTS: Isohemagglutinin titration and the results of qualitative hemolysin test did not correlate. The routine implementation of the qualitative hemolysin test significantly increased the percentage of platelet units found unsuitable for transfusions (15-65%; p-value <0.001. Furthermore the qualitative hemolysin test did not prevent red blood cell sensitization in a small exploratory analysis.CONCLUSION: Qualitative hemolysin test results do not correlate to those of isohemagglutinin titers and its implementation as the prophylaxis of choice for hemolysis associated with plasma-incompatible platelet transfusions lacks clinical support of safety

  19. Surface modification of ultrahigh molecular weight polyethylene by the poly(ethylene glycol)-grafted method and its effect on the adsorption of proteins and the adhesion of blood platelets.

    Science.gov (United States)

    Xia, Bing; Xie, Meiju; Yang, Bangcheng

    2013-01-01

    With the help of a silane coupling agent, poly(ethylene glycol) (PEG), a well-biocompatable agent, was grafted onto the surface of ultrahigh molecular weight polyethylene (UHMWPE) by ultraviolet initiation. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis proved the success of PEG grafting. Water contact angle measurement showed that the modified UHMWPE was obviously improved in surface hydrophilicity and thermogravimetric analysis result showed that its thermostability did not decline even it was pretreated by strong acids. Then, the protein adsorption of the modified UHMWPE was investigated using three model proteins including bovine serum albumin, lysozyme, and fibrinogen. Rabbit blood was used to study the platelet adhesion on the surface of modified UHMWPE. The results indicated that the quantity of protein adsorption on the modified UHMWPE grafted PEG reduced apparently for all the model proteins while there was some specific differences or exceptions among them. It was ascribed to the changed surface chemical composition, surface hydrophilicity and surface topography after modification. The adhesive ability of blood platelets on the modified surface of UHMWPE decreased after PEG grafting. Owing to the improved resistance to fibrinogen adsorption and platelet adhesion, the surface modification might endow the UHWMPE surface better anticoagulation ability according to clotting mechanism.

  20. Modification of Si(100) surface by the grafting of poly(ethylene glycol) for reduction in protein adsorption and platelet adhesion.

    Science.gov (United States)

    Zhang, F; Kang, E T; Neoh, K G; Wang, P; Tan, K L

    2001-09-05

    The modification of argon plasma-pretreated single-crystal Si(100) wafer surfaces via the UV-induced graft polymerization of poly(ethylene glycol) methacrylate (PEGMA) macromonomer (molecular weight approximately 340) for biomaterials applications was explored. The modified Si(100) surfaces were characterized by X-ray photoelectron spectroscopy and atomic force microscopy. Surface peroxide concentrations resulting from the argon plasma treatment and subsequent atmospheric exposure were determined by a coupling reaction with diphenylpicrylhydrazyl. The results suggested that a short plasma treatment time of 10 s and brief air exposure were sufficient for generating an optimum amount of peroxides and hydroperoxides for the subsequent UV-induced graft polymerization. The graft concentration of the PEGMA polymer increased with increasing PEGMA macromonomer concentration for the graft polymerization and with increasing UV graft polymerization time. The PEGMA graft-polymerized silicon surface with a high poly(ethylene glycol) graft concentration was very effective in preventing protein adsorption and platelet adhesion. The grafted PEGMA polymer layer on the Si(100) surface exhibited fairly good stability during storage in a buffer solution.

  1. Association of G+1688A Polymorphism of Platelet Endothelial Cell Adhesion Molecule-1 Gene with Myocardial Infarction in the Chinese Han Population

    Institute of Scientific and Technical Information of China (English)

    YANG Ying; CHENG Longxian; Ripen Nsenga; HE Meian; CHANG Zhitang; WU Tangchun

    2007-01-01

    In order to investigate the association of G+1688A (Ser563Asn) polymorphism of platelet endothelial cell adhesion molecule-1 (PECAM-1) gene with myocardial infarction (MI) in the Chi- nese Han population, the G+1688A polymorphism in PECAM-1 gene was detected by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) method among 502 subjects, including 218 patients with MI and 284 controls. The results showed that there was significant dif-ference in AA frequencies of genotype G+1688A polymorphism between case and control groups (39% vs 24%, P<0.001). A similar trend was observed on the allele frequencies (A/G: 62% vs 49%, P<0.001). Among the subjects with high serum total cholesterol level or high systolic blood pressure level, the variant AA genotype was associated with high risk of MI (adjusted OR, 2.13; 95% CI, 1.08-4.41 and adjusted OR, 2.53; 95%CI, 1.63-3.63). The single nucleotide polymorphism (SNP) at position +1688 in the exon 8 of PECAM-1 gene was associated with MI and the allele A might be a risk factor for MI in the Chinese Han population.

  2. Platelet binding to monocytes increases the adhesive properties of monocytes by up-regulating the expression and functionality of beta(1) and B-2 integrins

    NARCIS (Netherlands)

    P.A.D.C. Martins; J.M. van Gils; A. Mol; P.L. Hordijk; J.J. Zwaginga

    2006-01-01

    Human monocytes adhere to activated platelets, resulting in the formation of platelet-monocyte complexes (PMC). Complex formation depends on the interaction between platelet-displayed P-selectin and the specific ligand for P-selectin on leukocytes, P-selectin glycoprotein ligand-1 (PSGL-1). We have

  3. Adhesion mechanisms of bituminous crack sealant to aggregate and laboratory test development

    Science.gov (United States)

    Hajialiakbari Fini, Elham

    Crack sealing is a common pavement maintenance treatment because it extends pavement service life. However, crack sealant often fails prematurely due to a loss of adhesion. Since current test methods are mostly empirical and only provide a qualitative measure of bond strength, they cannot predict sealant adhesive failure accurately. Hence, there is an urgent need for test methods based on bituminous sealant rheology that can better predict sealant field performance. This study introduces three laboratory tests aimed to assess the bond property of hot-poured crack sealant to pavement crack walls. The three tests are designed to serve the respective needs of producers, engineers, and researchers. The first test implements the principle of surface energy to measure the thermodynamic work of adhesion, which is the energy spent in separating the two materials at the interface. The work of adhesion is reported as a measure of material compatibility at an interface. The second test is a direct adhesion test, a mechanical test which is designed to closely resemble both the installation process and the crack expansion due to thermal loading. This test uses the Direct Tension Test (DTT) device. The principle of the test is to apply a tensile force to detach the sealant from its aggregate counterpart. The maximum load, Pmax, and the energy to separation, E, are calculated and reported to indicate interface bonding. The third test implements the principles of fracture mechanics in a pressurized circular blister test. The apparatus is specifically designed to conduct the test for bituminous crack sealant, asphalt binder, or other bitumen-based materials. In this test, a fluid is injected at a constant rate at the interface between the substrate (aggregate or a standard material) and the adhesive (crack sealant) to create a blister. The fluid pressure and blister height are measured as functions of time; the data is used to calculate Interfacial Fracture Energy (IFE), which is a

  4. New Insights into Nanoindentation-Based Adhesion Testing

    Science.gov (United States)

    Kleinbichler, A.; Pfeifenberger, M. J.; Zechner, J.; Moody, N. R.; Bahr, D. F.; Cordill, M. J.

    2017-08-01

    Nanoindentation, or instrumented indentation, is a versatile technique that is most often used to measure the elastic modulus and hardness of thin film systems. It can also be employed to measure thin film adhesion energies by producing well-defined areas of delamination. When combined with the proper mechanics-based model and characterization of the failing interfaces, nanoindentation-induced delamination is a powerful tool to quantify interfacial fracture. This article highlights new improvements to the technique that build off the work of Marshall and Evans in the 1980s. Indentation-induced delamination in systems with brittle films or substrates can be a balance between causing delamination and causing through-thickness or bulk fracture. Focused ion beam cross-sectioning and confocal laser scanning microscopy were used to characterize failing interfaces, additional fracture events were observed in the load-displacement curves, and the adhesion energy was determined using not only symmetric, ideally shaped buckles, but also irregular-shaped and half-delaminated buckles.

  5. Coracoid pain test: a new clinical sign of shoulder adhesive capsulitis

    OpenAIRE

    2009-01-01

    Patients with adhesive capsulitis were clinically evaluated to establish whether pain elicited by pressure on the coracoid area may be considered a pathognomonic sign of this condition. The study group included 85 patients with primary adhesive capsulitis, 465 with rotator cuff tear, 48 with calcifying tendonitis, 16 with glenohumeral arthritis, 66 with acromioclavicular arthropathy and 150 asymptomatic subjects. The test was considered positive when pain on the coracoid region was more sever...

  6. Development of a laboratory test for characterization of asphalt-aggregate adhesion

    OpenAIRE

    Pais, Jorge C.; Silva, Hugo Manuel Ribeiro Dias da; Pereira, Paulo A. A.

    2002-01-01

    The mechanical properties of bituminous mixtures depend on the adhesion between mastic and aggregate, as well as on the cohesion within the mastic. These properties vary as a function of the composition of the bituminous mixture, of the chemical and physical features of the aggregate and bitumen and of the condition under which the mixing is carried out. It is thus fundamental to develop an adhesion test, which is of easy execution and, at the same time, represents correctly the bituminous mi...

  7. Examination of a Junction-Box Adhesion Test for Use in Photovoltaic Module Qualification (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D. C.; Wohlgemuth, J. H.

    2012-08-01

    Engineering robust adhesion of the junction-box (j-box) is a hurdle typically encountered by photovoltaic (PV) module manufacturers during product development. There are historical incidences of adverse effects (e.g., fires) caused when the j-box/adhesive/module system has failed in the field. The addition of a weight to the j-box during the 'damp heat' IEC qualification test is proposed to verify the basic robustness of its adhesion system. The details of the proposed test will be described, in addition to the preliminary results obtained using representative materials and components. The described discovery experiments examine moisture-cured silicone, foam tape, and hot-melt adhesives used in conjunction with PET or glass module 'substrates.' To be able to interpret the results, a set of material-level characterizations was performed, including thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. PV j-boxes were adhered to a substrate, loaded with a prescribed weight, and then placed inside an environmental chamber (at 85C, 85% relative humidity). Some systems did not remain attached through the discovery experiments. Observed failure modes include delamination (at the j-box/adhesive or adhesive/substrate interface) and phase change/creep. The results are discussed in the context of the application requirements, in addition to the plan for the formal experiment supporting the proposed modification to the qualification test.

  8. Examination of a Junction-Box Adhesion Test for Use in Photovoltaic Module Qualification: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Miller, D. C.; Wohlgemuth, J. H.

    2012-08-01

    Engineering robust adhesion of the junction-box (j-box) is a hurdle typically encountered by photovoltaic (PV) module manufacturers during product development. There are historical incidences of adverse effects (e.g., fires) caused when the j-box/adhesive/module system has failed in the field. The addition of a weight to the j-box during the 'damp heat' IEC qualification test is proposed to verify the basic robustness of its adhesion system. The details of the proposed test will be described, in addition to the preliminary results obtained using representative materials and components. The described discovery experiments examine moisture-cured silicone, foam tape, and hot-melt adhesives used in conjunction with PET or glass module 'substrates.' To be able to interpret the results, a set of material-level characterizations was performed, including thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. PV j-boxes were adhered to a substrate, loaded with a prescribed weight, and then placed inside an environmental chamber (at 85C, 85% relative humidity). Some systems did not remain attached through the discovery experiments. Observed failure modes include delamination (at the j-box/adhesive or adhesive/substrate interface) and phase change/creep. The results are discussed in the context of the application requirements, in addition to the plan for the formal experiment supporting the proposed modification to the qualification test.

  9. Test method to assess interface adhesion in composite bonding

    NARCIS (Netherlands)

    Teixeira de Freitas, S.; Sinke, J.

    2015-01-01

    This paper introduces a new type of peel tests dedicated to composite bonding: Composite Peel Tests. This test is inspired on the standard floating roller peel test widely used for metal bonding. The aim of this study is to investigate the potential of the Composite Peel Test to assess interface ad

  10. Provision of HPA-1a (PlA1)-negative platelets for neonatal alloimmune thrombocytopenia: screening, testing, and transfusion protocol.

    Science.gov (United States)

    Munizza, M; Nance, S; Keashen-Schnell, M A; Sherwood, W; Murphy, S

    1999-01-01

    HPA-1a-negative platelet products are not routinely available for newborns with alloimmune thrombocytopenia. In this article we describe a program established to identify normal pheresis donors who are HPA-1a-negative and to organize their future donations so that our regional blood center would always have an HPA-1a-negative platelet product available. The solid phase red cell adherence assay was used for initial screening of platelet pheresis products. HPA-1a-negative donors were confirmed with the platelet suspension immunofluorescence test using three anti-HPA-1a sera. Screening of 2600 plateletpheresis donor samples identified 40 HPA-1a-negative donors. Of these, 36 are active and are coded for recognition on the daily pheresis inventory sheet. Theoretically, assuming four donations per year and donors' cooperation with scheduling, these 36 donors would enable us to have at least one HPA-1a-negative product available every day. In addition, a decision tree for patient management using platelet serology and availability of HPA-1a-negative products was developed. The GTI-PAK trade mark 12 is the major technique used for serologic screening of mothers of patients thought to have neonatal alloimmune thrombocytopenia. By screening pheresis donors and developing a clinical decision tree, HPA-1a-negative products, a rare resource, can be fully utilized.

  11. Expression of platelet-endothelial cell adhesion molecule-1 in human umbilical vein endothelial cells by exposure to advanced glycosylation end products and inflammatory mediators

    Institute of Scientific and Technical Information of China (English)

    孟丹; 刘乃丰

    2003-01-01

    Objective To determine whether advanced glycosylation end products modified bovine serum albumin (AGEs-BSA) affects endothelial cell lateral junction protein, platelet-endothelial cell adhesion molecule-1 (PECAM-1) in the presence or absence of inflammatory mediators.Methods Cultured human umbilical vein endothelial cells (HUVECs) were exposed to AGEs-BSA for 6, 12, 24, and 36 hours, and exposed to AGEs-BSA glycosylated with different concentrations of glucose, tumor necrosis factord-α (TNF-α), interferon (IFN-γ), TNF-α+IFN-γ and AGEs-BSA+TNF-α for 24 hours, respectively. Expression of PECAM-1 mRNA was measured by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) with β-actin as an internal standard, and sequencing of RT-PCR products was performed to confirm the specificity of amplification for PECAM-1 gene. The endothelial cell surface expression of PECAM-1 was determined by flow cytometry (FCM).Results There were no significant changes in the expression of PECAM-1 mRNA and protein when the cells were exposed to AGEs-BSA with different concentrations or periods (P> 0.05). However, PECAM-1 expression was reduced in the cells treated with TNF-α, IFN-γ, TNF-α+IFN-γ and AGEs-BSA+TNF-α. The level of PECAM-1 treated with AGEs-BSA+TNF-α was lower than that of TNF-α treated alone (P<0.01).Conclusions AGEs-BSA had no effect on the expression of PECAM-1 mRNA and protein in cultured HUVEC. With the presence of inflammatory mediator TNF-α, AGEs-BSA decreased the level of PECAM-1, which might reduce the adhesion interaction between adjacent endothelial cells, enhance the permeability of endothelial cells, and might be implicated in the endothelial dysfunction and pathogenesis of atherosclerosis in patients with diabetes mellitus. The significance of this phenomenon in intracellular signal transduction remains to be determined.

  12. Adhesion to tooth structure: a critical review of "micro" bond strength test methods.

    Science.gov (United States)

    Armstrong, Steve; Geraldeli, Saulo; Maia, Rodrigo; Raposo, Luís Henrique Araújo; Soares, Carlos José; Yamagawa, Junichiro

    2010-02-01

    The objective of this paper is to critically review the literature regarding the mechanics, geometry, load application and other testing parameters of "micro" shear and tensile adhesion tests, and to outline their advantages and limitations. The testing of multiple specimens from a single tooth conserves teeth and allows research designs not possible using conventional 'macro' methods. Specimen fabrication, gripping and load application methods, in addition to material properties of the various components comprising the resin-tooth adhesive bond, will influence the stress distribution and consequently, the nominal bond strength and failure mode. These issues must be understood; as should the limitations inherent to strength-based testing of a complicated adhesive bond joining dissimilar substrates, for proper test selection, conduct and interpretation. Finite element analysis and comprehensive reporting of test conduct and results will further our efforts towards a standardization of test procedures. For the foreseeable future, both "micro" and "macro" bond strength tests will, as well as various morphological and spectroscopic investigative techniques, continue to be important tools for improving resin-tooth adhesion to increase the service life of dental resin-based composite restorations.

  13. Measurement of platelet aggregation, independently of patient platelet count

    DEFF Research Database (Denmark)

    Vinholt, P. J.; Frederiksen, H.; Hvas, A.M.

    2017-01-01

    platelet aggregation ruled out bleeding tendency in thrombocytopenic patients. Summary: Background: Methods for testing platelet aggregation in thrombocytopenia are lacking. Objective: To establish a flow-cytometric test of in vitro platelet aggregation independently of the patient's platelet count......, and examine the association of aggregation with a bleeding history in thrombocytopenic patients. Patients/methods: We established a flow-cytometric assay of platelet aggregation, and measured samples from healthy individuals preincubated with antiplatelet drugs, and samples from two patients with inherited...... platelets at platelet counts of > 10 × 109 L-1; otherwise, platelet isolation was required. The platelet aggregation percentage decreased with increasing antiplatelet drug concentration. Platelet aggregation in patients was reduced as compared with healthy individuals: 42% (interquartile range [IQR] 27...

  14. Evaluation of cytotoxic effects of six self-etching adhesives with direct and indirect contact tests.

    Science.gov (United States)

    Kusdemir, Mahmut; Gunal, Solen; Ozer, Fusun; Imazato, Satoshi; Izutani, Naomi; Ebisu, Shigeyuki; Blatz, Markus B

    2011-01-01

    This study evaluated the cytotoxicity of self-etching primers/adhesives by direct contact and dentin barrier tests. The three two-step self-etching systems Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Prime&Bond NT/NRC (PB) and one-step self-etching systems Reactmer Bond (RB), Clearfil Tri-S Bond (CTS), and Adper Prompt L-Pop (AP) were examined. In direct contact tests, L929 cells were cultured in the presence of diluted solutions (50, 20, 10, and 1%) of primer/conditioner of adhesive systems. For dentin barrier tests, each system was applied onto 0.5 or 1.5 mm thick human dentin assembled in a simple pulp chamber device and incubated for 24 h at 37°C to make the diffusive components contact the L929 cells placed at the bottom of the chamber. The cytotoxic effects were assessed by MTT assay. Cell culture without application of any primers/adhesives served as the control for both tests. One-way ANOVA and Tukey HSD tests were used for statistical analyses. The direct contact tests demonstrated that CSE and CPB were less toxic than the other materials at all dilutions. In the dentin barrier tests, toxic effects of materials were reduced with an increase in thickness of intervening dentin. CSE and CPB showed less cytotoxicity than the other adhesives (padhesives.

  15. Molecular Basis Linking Platelet to Inflammation

    Institute of Scientific and Technical Information of China (English)

    马丽萍

    2010-01-01

    @@ Introduction Blood platelets not only play an important role in hemostasis and thrombosis,but increasing evidence show that they participate in the induction of inflammation.Firstly,platelets contain and release cytokines and immune mediators.And platelets are able to modulate and regulate the function of surrounding cells by adhesion molecules or by the release of various factors.

  16. Testing adhesion of direct restoratives to dental hard tissue - a review.

    Science.gov (United States)

    Salz, Ulrich; Bock, Thorsten

    2010-10-01

    This articles concerns itself with the testing of adhesion between direct restoratives and dental hard tissue, ie, enamel and dentin. The aim is to survey available methods for adhesion testing and influential parameters affecting experimental outcome. The testing of adhesion to indirect restorative materials, eg, ceramics and metals, is beyond the scope of this article and shall be discussed elsewhere. The longevity and success of modern dental restorations very often relies on potent dental adhesives to provide durable bonds between the dental hard substance and the restorative composite. To predict the clinical outcome of such restorative treatment, a large variety of in vitro laboratory tests and clinical in vivo experiments have been devised, analyzed, and published. The purpose of this review is to provide a current overview of bond strength testing methods and their applicability to the characterization of dental adhesives. Regardless of the method employed, subtle variations in sample preparation may already severely impact test results, usually necessitating at least co-testing of a well-known internal reference to allow conclusive interpretation. This article attempts to list and discuss the most influential parameters, such as substrate nature, age, health status, storage, clinically relevant pre-treatment, and sample preparation. Special attention is devoted to the last aspect, as numerous publications have stressed the tremendous influence of preparatory parameters on the validity and scope of obtained data. Added to the large variety of such factors, an equally large diversity of load-applying procedures exists to actually quantify adhesion between composites and dental hard substance. This article summarizes the basics of macro and micro approaches to shear and tensile bond strength testing, as well as push- and pull-out tests. The strengths and weaknesses inherent to each method and influential test parameters are reviewed and methods for

  17. Defining Platelet Function During Polytrauma

    Science.gov (United States)

    2013-02-01

    using calibrated automated thrombography ( CAT ). 3. Platelet-induced clot contraction and using viscoelastic measures such as TEG with Platelet Mapping...using calibrated automated thrombography ( CAT ) in platelet-rich plasma. 3. Platelet-induced clot contraction and effect on clot structure by platelet...if injury with stable vital signs on initial evaluation.  Pregnancy (confirmed with urine pregnancy testing)  Documented do not resuscitate order

  18. Salvianolic Acid B inhibits platelet adhesion under conditions of flow by a mechanism involving the collagen receptor alpha 2 beta 1

    NARCIS (Netherlands)

    Wu, Ya Ping; Zhao, Xiao Min; Pan, Shao Dong; Guo, De An; Wei, Ran; Han, Ji Ju; Kainoh, Mie; Xia, Zuo Li; de Groot, Philip G.; Lisman, Ton

    2008-01-01

    Salvianolic acid B (SAB) is a component of Danshen, a herb widely used in Chinese medicine, and was previously shown to exert a number of biological activities including inhibition of platelet function, but the exact mechanisms involved are unclear. SAB dose-dependently inhibited platelet deposition

  19. Adhesion characteristics of silver tracks screen-printed on polyimide with an environmental reliability test.

    Science.gov (United States)

    Kim, Kwang-Seok; Myung, Woo-Ram; Jung, Seung-Boo

    2012-07-01

    Printable and flexible electronics are increasingly being used in numerous applications that are miniaturized, multi-functional and lightweight. Simultaneously, reliability issues of the printed and flexible electronic devices are getting more attention. The adhesion of screen-printed silver (Ag) tracks on a polyimide (PI) film was investigated after two kinds of the environmental reliability test: a constant-temperature storage test, and a steady-state temperature and humidity storage test. Atmospheric-pressure plasma (APP) was adopted on the PI film surface to improve the poor adhesion derived from the inherent hydrophobicity. The Ag tracks constructed via screen printing were sintered at 250 degrees C for 30 min in air using a box-type muffle furnace. Some samples were exposed under 85 degrees C and 85% relative humidity (RH) for various durations (24, 72, 168 and 500 h), and others were aged at 85 degrees C with same durations to compare the influence of moisture on the adhesion. The adhesion of the screen-printed Ag tracks was evaluated by a roll-type 90 degrees peel test. The peel strength of the screen-printed Ag tracks decreased by 76.74% and 69.88% after 500 h run of the 85 degrees C/85% RH test, and the aging test, respectively. The weakest adhesion was 4.98 gf/mm after the 500 h run of the 85 degrees C/85% RH test. To demonstrate these experimental results, the microstructural evolution and chemical bonding states of the interfacial surfaces were characterized using a field emission scanning electron microscope (FE-SEM), and X-ray photoelectron spectroscope (XPS), respectively.

  20. A blister-test apparatus for studies on the adhesion of materials used for neural electrodes.

    Science.gov (United States)

    Ordonez, Juan; Boehler, Christian; Schuettler, Martin; Stieglitz, Thomas

    2011-01-01

    A blister test apparatus has been developed, which allows a quantitative adhesion analysis of thin-film metallizations on polymers manufactured in cleanroom conditions suitable for micromachining of neural electrode arrays. The device is capable of pressurizing metallic membranes at wafer level, monitoring the pressure and the height of the developing blister while detecting the moment of delamination, allowing the calculation of the adhesion energy between metal film and polymer. The machine is designed for quantitative long-term studies of materials used in neural microelectrode arrays.

  1. Investigation of a Wedge Adhesion Test for Edge Seals

    Energy Technology Data Exchange (ETDEWEB)

    Kempe, Michael; Wohlgemuth, John; Miller, David; Postak, Lori; Booth, Dennis; Phillips, Nancy

    2016-09-26

    Many photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB) based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25-year life of a module; but to do so, they must remain well-adhered and free of cracks. This work focuses on adapting the Boeing Wedge test for use with edge seals laminated using glass substrates as part of a strategy to assess the long-term durability of edge seals. The advantage of this method is that it duplicates the residual stresses and strains that a glass/glass module may have when the lamination process results in some residual glass bending that puts the perimeter in tension. Additionally, this method allows one to simultaneously expose the material to thermal stress, humidity, mechanical stress, and ultraviolet radiation. The disadvantage of this method generally is that we are limited by the fracture toughness of the glass substrates that the edge seal is adhered to. However, the low toughness of typical uncrosslinked or sparsely crosslinked PIB makes them suitable for this technique. We present data obtained during the development of the wedge test for use with PV edge seal materials. This includes development of the measuring techniques and evaluation of the test method with relevant materials. We find consistent data within a given experiment, along with the theoretical independence of fracture toughness measurements with wedge thickness. This indicates that the test methodology is reproducible. However, even though individual experimental sets are consistent, the reproducibility between experimental sets is poor. We believe this may be

  2. Investigation of a wedge adhesion test for edge seals

    Science.gov (United States)

    Kempe, Michael; Wohlgemuth, John; Miller, David; Postak, Lori; Booth, Dennis; Phillips, Nancy

    2016-09-01

    Many photovoltaic (PV) technologies have been found to be sensitive to moisture that diffuses into a PV package. Even with the use of impermeable frontsheets and backsheets, moisture can penetrate from the edges of a module. To limit this moisture ingress pathway from occurring, manufacturers often use a low permeability polyisobutylene (PIB) based edge seal filled with desiccant to further restrict moisture ingress. Moisture ingress studies have shown that these materials are capable of blocking moisture for the 25-year life of a module; but to do so, they must remain well-adhered and free of cracks. This work focuses on adapting the Boeing Wedge test for use with edge seals laminated using glass substrates as part of a strategy to assess the long-term durability of edge seals. The advantage of this method is that it duplicates the residual stresses and strains that a glass/glass module may have when the lamination process results in some residual glass bending that puts the perimeter in tension. Additionally, this method allows one to simultaneously expose the material to thermal stress, humidity, mechanical stress, and ultraviolet radiation. The disadvantage of this method generally is that we are limited by the fracture toughness of the glass substrates that the edge seal is adhered to. However, the low toughness of typical uncrosslinked or sparsely crosslinked PIB makes them suitable for this technique. We present data obtained during the development of the wedge test for use with PV edge seal materials. This includes development of the measuring techniques and evaluation of the test method with relevant materials. We find consistent data within a given experiment, along with the theoretical independence of fracture toughness measurements with wedge thickness. This indicates that the test methodology is reproducible. However, even though individual experimental sets are consistent, the reproducibility between experimental sets is poor. We believe this may be

  3. A measurement system analysis with design of experiments: Investigation of the adhesion performance of a pressure sensitive adhesive with the probe tack test.

    Science.gov (United States)

    Michaelis, Marc; Leopold, Claudia S

    2015-12-30

    The tack of a pressure sensitive adhesive (PSA) is not an inherent material property and strongly depends on the measurement conditions. Following the concept of a measurement system analysis (MSA), influencing factors of the probe tack test were investigated by a design of experiments (DoE) approach. A response surface design with 38 runs was built to evaluate the influence of detachment speed, dwell time, contact force, adhesive film thickness and API content on tack, determined as the maximum of the stress strain curve (σmax). It could be shown that all investigated factors have a significant effect on the response and that the DoE approach allowed to detect two-factorial interactions between the dwell time, the contact force, the adhesive film thickness and the API content. Surprisingly, it was found that tack increases with decreasing and not with increasing adhesive film thickness.

  4. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

  5. Moisture sensitivity examination of asphalt mixtures using thermodynamic, direct adhesion peel and compacted mixture mechanical tests

    OpenAIRE

    Zhang, Jizhe; AIREY, Gordon D; Grenfell, James; Apeagyei, Alex K.

    2016-01-01

    Moisture damage in asphalt mixtures is a complicated mode of pavement distress that results in the loss of stiffness and structural strength of the asphalt pavement layers. This paper evaluated the moisture sensitivity of different aggregate–bitumen combinations through three different approaches: surface energy, peel adhesion and the Saturation Ageing Tensile Stiffness (SATS) tests. In addition, the results obtained from these three tests were compared so as to characterise the relationship ...

  6. A high-throughput sequencing test for diagnosing inherited bleeding, thrombotic, and platelet disorders

    Science.gov (United States)

    Simeoni, Ilenia; Stephens, Jonathan C.; Hu, Fengyuan; Deevi, Sri V. V.; Megy, Karyn; Bariana, Tadbir K.; Lentaigne, Claire; Schulman, Sol; Sivapalaratnam, Suthesh; Vries, Minka J. A.; Westbury, Sarah K.; Greene, Daniel; Papadia, Sofia; Alessi, Marie-Christine; Attwood, Antony P.; Ballmaier, Matthias; Baynam, Gareth; Bermejo, Emilse; Bertoli, Marta; Bray, Paul F.; Bury, Loredana; Cattaneo, Marco; Collins, Peter; Daugherty, Louise C.; Favier, Rémi; French, Deborah L.; Furie, Bruce; Gattens, Michael; Germeshausen, Manuela; Ghevaert, Cedric; Goodeve, Anne C.; Guerrero, Jose A.; Hampshire, Daniel J.; Hart, Daniel P.; Heemskerk, Johan W. M.; Henskens, Yvonne M. C.; Hill, Marian; Hogg, Nancy; Jolley, Jennifer D.; Kahr, Walter H.; Kelly, Anne M.; Kerr, Ron; Kostadima, Myrto; Kunishima, Shinji; Lambert, Michele P.; Liesner, Ri; López, José A.; Mapeta, Rutendo P.; Mathias, Mary; Millar, Carolyn M.; Nathwani, Amit; Neerman-Arbez, Marguerite; Nurden, Alan T.; Nurden, Paquita; Othman, Maha; Peerlinck, Kathelijne; Perry, David J.; Poudel, Pawan; Reitsma, Pieter; Rondina, Matthew T.; Smethurst, Peter A.; Stevenson, William; Szkotak, Artur; Tuna, Salih; van Geet, Christel; Whitehorn, Deborah; Wilcox, David A.; Zhang, Bin; Revel-Vilk, Shoshana; Gresele, Paolo; Bellissimo, Daniel B.; Penkett, Christopher J.; Laffan, Michael A.; Mumford, Andrew D.; Rendon, Augusto; Freson, Kathleen; Ouwehand, Willem H.; Turro, Ernest

    2016-01-01

    Inherited bleeding, thrombotic, and platelet disorders (BPDs) are diseases that affect ∼300 individuals per million births. With the exception of hemophilia and von Willebrand disease patients, a molecular analysis for patients with a BPD is often unavailable. Many specialized tests are usually required to reach a putative diagnosis and they are typically performed in a step-wise manner to control costs. This approach causes delays and a conclusive molecular diagnosis is often never reached, which can compromise treatment and impede rapid identification of affected relatives. To address this unmet diagnostic need, we designed a high-throughput sequencing platform targeting 63 genes relevant for BPDs. The platform can call single nucleotide variants, short insertions/deletions, and large copy number variants (though not inversions) which are subjected to automated filtering for diagnostic prioritization, resulting in an average of 5.34 candidate variants per individual. We sequenced 159 and 137 samples, respectively, from cases with and without previously known causal variants. Among the latter group, 61 cases had clinical and laboratory phenotypes indicative of a particular molecular etiology, whereas the remainder had an a priori highly uncertain etiology. All previously detected variants were recapitulated and, when the etiology was suspected but unknown or uncertain, a molecular diagnosis was reached in 56 of 61 and only 8 of 76 cases, respectively. The latter category highlights the need for further research into novel causes of BPDs. The ThromboGenomics platform thus provides an affordable DNA-based test to diagnose patients suspected of having a known inherited BPD. PMID:27084890

  7. A New Testing Method to Evaluate Adhesion Strength of Ceramic Top Coat in TBCs

    Science.gov (United States)

    Okazaki, Masakazu; Yamagishi, Satoshi; Osakabe, Masakazu; Fukanuma, Hirotaka

    A new testing method to evaluate adhesion strength of ceramic top coat has been proposed, employing a ring shape of TBC specimen specifically designed. It was shown by the experiments that a delamination behavior of the top coat was successfully reproduced in the proposed method, associating with a buckling mode; a similar mode frequently observed in actual gas turbine components. A method to quantitatively evaluate a resistance to delamination was also introduced, based on an energy release rate criterion. The experiments demonstrated that the testing method provided reasonable adhesion strength in terms of energy criterion, that almost agreed with the values measured by other researchers employing different type of testing method. It was also shown that the present method has many advantages, compared with the traditional methods.

  8. Lactodifucotetraose, a human milk oligosaccharide, attenuates platelet function and inflammatory cytokine release.

    Science.gov (United States)

    Newburg, David S; Tanritanir, Ayse C; Chakrabarti, Subrata

    2016-07-01

    Human milk strongly quenches inflammatory processes in vitro, and breastfed infants have lower incidence of inflammatory diseases than those fed artificially. Platelets from neonates, in contrast to those from adults, are less responsive to platelet agonists such as collagen, thrombin, ADP, and epinephrine. Breastfed infants absorb oligosaccharides intact from the human milk in their gut to the circulation. This study was to determine whether these oligosaccharides can attenuate platelet function and platelet secretion of pro-inflammatory proteins, and to identify the active component. The natural mixture of oligosaccharides from human milk and pure individual human milk oligosaccharides were tested for their ability to modulate responses of platelets isolated from human blood following exposure to thrombin, ADP, and collagen. Human milk and the natural mixture of human milk oligosaccharides inhibited platelet release of inflammatory proteins. Of the purified human milk oligosaccharides tested, only lactodifucotetraose (LDFT) significantly inhibited thrombin induced release of the pro-inflammatory proteins RANTES and sCD40L. LDFT also inhibited platelet adhesion to a collagen-coated surface, as well as platelet aggregation induced by ADP or collagen. These data indicate that LDFT may help modulate hemostasis by suppressing platelet-induced inflammatory processes in breastfed infants. This activity suggests further study of LDFT for its potential as a therapeutic agent in infants and adults.

  9. Adhesion to tooth structure: a critical review of "macro" test methods.

    Science.gov (United States)

    Braga, Roberto R; Meira, Josete B C; Boaro, Leticia C C; Xavier, Tathy A

    2010-02-01

    Bond strength between adhesive systems and the tooth structure is influenced by a large number of variables, which makes the comparison among studies virtually impossible. Also, failure often times propagates into the dental substrate or the composite, deeming the results questionable at best. In spite of the increased popularity gained by micro-tensile and micro-shear tests, in vitro evaluations using specimens with relatively large bonding areas remain frequent. This review focuses on aspects related to specimen geometry and test mechanics of "macro" shear and tensile bond strength tests. Besides information drawn from the literature, the effect of some parameters on stress distribution at the bonded interface was assessed using finite element analysis (FEA). Bond strength tends to increase with smaller bonding areas and with the use of high elastic modulus composites. Stress concentration at the bonded interface is much more severe in shear compared to tension. Among shear methods, the use of the chisel shows the highest stress concentration. Within the limits suggested by the ISO/TS 11405, crosshead speed does not seem to influence bond strength values. Pooled data from currently available adhesives tested in either shear or tension showed 44% of adhesive failures, 31% mixed and 25% cohesive in the substrate (tooth or composite). A comparative bond strength study involving three adhesive systems revealed similarities between "macro" and "micro" counterparts regarding material ranking, whereas "macro" tests presented a higher incidence of cohesive failures. Simplicity warrants "macro" bond strength tests an enduring popularity, in spite of their evident limitations. From a mechanical standpoint, knowing the stress distribution at the bonded interface and how it is affected by the materials and loading method used is key to explain the results. Copyright 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. Head to Head Comparison of Two Point-of-care Platelet Function Tests Used for Assessment of On-clopidogrel Platelet Reactivity in Chinese Acute Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention

    Institute of Scientific and Technical Information of China (English)

    Yi Yao; Jia-Hui Zhang; Xiao-Fang Tang; Chen He; Yuan-Liang Ma; Jing-Jing Xu; Ying Song

    2016-01-01

    Background:Platelet function tests are widely used in clinical practice to guide personalized antiplatelet therapy.In China,the thromboelastography (TEG) test has been well accepted in clinics,whereas VerifyNow,mainly used for scientific research,has not been used in routine clinical practice.The aim of the current study was to compare these two point-of-care platelet function tests and to analyze the consistency between the two tests for evaluating on-clopidogrel platelet reactivity in Chinese acute myocardial infarction patients undergoing percutaneous coronary intervention (PCI).Methods:A total of 184 patients admitted to Fuwai Hospital between August 2014 and May 2015 were enrolled in the study.On-clopidogrel platelet reactivity was assessed 3 days after PCI by TEG and VerifyNow using adenosine diphosphate as an agonist.Based on the previous reports,an inhibition of platelet aggregation (IPA) <30% for TEG or a P2Y12 reaction unit (PRU) >230 for VerifyNow was defined as high on-clopidogrel platelet reactivity (HPR).An IPA >70% or a PRU <178 was defined as low on-clopidogrel platelet reactivity (LPR).Correlation and agreement between the two methods were analyzed using the Spearman correlation coefficient (r) and kappa value (κ),respectively.Results:Our results showed that VerifyNow and TEG had a moderate but significant correlation in evaluating platelet reactivity (r =-0.511).A significant although poor agreement (κ =0.225) in identifying HPR and a significantly moderate agreement in identifying LPR (κ =0.412) were observed between TEG and VerifyNow.By using TEG as the reference for comparison,the cutoffvalues of VerifyNow for the Chinese patients in this study were identified as PRU >205 for HPR and PRU <169 for LPR.Conclusions:By comparing VerifyNow to TEG which has been widely used in clinics,VerifyNow could be an attractive alternative to TEG for monitoring on-clopidogrel platelet reactivity in Chinese patients.

  11. Coracoid pain test: a new clinical sign of shoulder adhesive capsulitis.

    Science.gov (United States)

    Carbone, S; Gumina, S; Vestri, A R; Postacchini, R

    2010-03-01

    Patients with adhesive capsulitis were clinically evaluated to establish whether pain elicited by pressure on the coracoid area may be considered a pathognomonic sign of this condition. The study group included 85 patients with primary adhesive capsulitis, 465 with rotator cuff tear, 48 with calcifying tendonitis, 16 with glenohumeral arthritis, 66 with acromioclavicular arthropathy and 150 asymptomatic subjects. The test was considered positive when pain on the coracoid region was more severe than 3 points (VAS scale) with respect to the acromioclavicular joint and the anterolateral subacromial area. The test was positive in 96.4% of patients with adhesive capsulitis and in 11.1%, 14.5%, 6.2% and 10.6% of patients with the other four conditions, respectively. A positive result was obtained in 3/150 normal subjects (2%). With respect to the other four diseases, the test had a sensitivity of 0.96 and a specificity ranging from 0.87 to 0.89. With respect to controls, the sensitivity and specificity were 0.99 and 0.98, respectively. The coracoid pain test could be considered as a pathognomonic sign in physical examination of patients with stiff and painful shoulder.

  12. Thermal and tensile strength testing of thermally-conductive adhesives and carbon foam

    Science.gov (United States)

    Chertok, M.; Fu, M.; Irving, M.; Neher, C.; Shi, M.; Tolfa, K.; Tripathi, M.; Vinson, Y.; Wang, R.; Zheng, G.

    2017-01-01

    Future collider detectors, including silicon tracking detectors planned for the High Luminosity LHC, will require components and mechanical structures providing unprecedented strength-to-mass ratios, thermal conductivity, and radiation tolerance. This paper studies carbon foam used in conjunction with thermally conductive epoxy and thermally conductive tape for such applications. Thermal performance and tensile strength measurements of aluminum-carbon foam-adhesive stacks are reported, along with initial radiation damage test results.

  13. Adhesion determination of dental porcelain to zirconia using the Schwickerath test: strength vs. fracture energy approach.

    Science.gov (United States)

    Kosyfaki, P; Swain, M V

    2014-11-01

    Two approaches to measure the fracture energy to delaminate four different porcelains from zirconia substrates are compared using Schwickerath adhesion strength test specimens. In all instances it was possible to stably extend the crack along or adjacent to the porcelain-zirconia interface. The fracture energy expended to delaminate the porcelain was found by determining the work of fracture upon loading to 12 N and then unloading. Additional tests were undertaken on specimens notched along the interface, which enabled the compliance of the cracked Schwickerath specimens to be calibrated. The strain energy and deflection of the Schwickerath specimen as a function of crack length were derived. On this basis a simple expression was determined for the strain energy release rate or interfacial fracture toughness from the minima in the force-displacement curves. Consequently two measures of the adhesion energy were determined, the work of fracture and the strain energy release rate. It was found that the ranking for the four porcelains bonded to zirconia differed depending upon the approach. The work of fracture was substantially different from the strain energy release rate for three of the porcelain-zirconia systems and appears to be directly related to the residual stresses present in the bonded structures. The relative merits of the strain energy release rate, work of fracture vs. the stress to initiate cracking in the case of the Schwickerath adhesion test, are discussed. The advantage of this test is that it enables three estimates of the adhesion for porcelain veneers bonded to zirconia. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  14. Inherited platelet disorders and oral health.

    Science.gov (United States)

    Valera, Marie-Cécile; Kemoun, Philippe; Cousty, Sarah; Sie, Pierre; Payrastre, Bernard

    2013-02-01

    Platelets play a key role in thrombosis and hemostasis. Accumulation of platelets at the site of vascular injury is the first step in the formation of hemostatic plugs, which play a pivotal role in preventing blood loss after injury. Platelet adhesion at sites of injury results in spreading, secretion, recruitment of additional platelets, and formation of platelet aggregates. Inherited platelet disorders are rare causes of bleeding syndromes, ranging from mild bruising to severe hemorrhage. The defects can reflect deficiency or dysfunction of platelet surface glycoproteins, granule contents, cytoskeletal proteins, platelet pro-coagulant function, and signaling pathways. For instance, Bernard-Soulier syndrome and Glanzmann thrombasthenia are attributed to deficiencies of glycoprotein Ib/IX/V and GPIIb/IIIa, respectively, and are rare but severe platelet disorders. Inherited defects that impair platelet secretion and/or signal transduction are among the most common forms of mild platelet disorders and include gray platelet syndrome, Hermansky-Pudlak syndrome, and Chediak-Higashi syndrome. When necessary, desmopressin, antifibrinolytic agents, and transfusion of platelets remain the most common treatment of inherited platelet disorders. Alternative therapies such as recombinant activated factor VII are also available for a limited number of situations. In this review, we will discuss the management of patients with inherited platelet disorders in various clinical situations related to dental cares, including surgical intervention. © 2012 John Wiley & Sons A/S.

  15. The influence of conjugates isolated from Matricaria chamomilla L. on platelets activity and cytotoxicity.

    Science.gov (United States)

    Bijak, Michał; Saluk, Joanna; Tsirigotis-Maniecka, Marta; Komorowska, Halina; Wachowicz, Barbara; Zaczyńska, Ewa; Czarny, Anna; Czechowski, Franciszek; Nowak, Paweł; Pawlaczyk, Izabela

    2013-10-01

    Cardiovascular diseases (CVD) remain the principal cause of death in both advanced and developing countries of the world. Blood platelets are involved in the pathogenesis of atherosclerosis and thrombosis. Platelet adhesion and aggregation are critical events that occur in unstable coronary syndromes. The current research is focused on the role of polysaccharide-polyphenolic conjugates isolated from chamomile (Matricaria chamomilla L.) at concentrations of 10, 25, 50 and 100 μg/mL on blood platelets (obtained from healthy donors and from patients received combined anti-platelet therapy complex with clopidogrel and acetylsalicylic acid) aggregation and experimentally induced cell toxicity. The treatment of PRP obtained from healthy donors with polyphenolic-polysaccharide conjugates from M. chamomilla (L.) (MC) resulted in a dose-dependent, decrease of platelet aggregation induced by multiple agonists (ADP, collagen and arachidonic acid). In this study we also observed that the MC reduced platelet aggregation in PRP obtained from patients with cardiovascular disorders. The result of testing the MC on human blood platelets, mouse fibroblast cultures L929 and human lung cells A549 did not show any cytotoxicity effects. Compounds obtained from M. chamomilla L. are potential composite to the development of a new anti-platelet agent, which could be an alternative to the currently used anti-platelet drugs.

  16. Effect of ionizing radiation on platelet function in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kalovidouris, A.E.; Papayannis, A.G. (Evangelismos Hospital, Athens (Greece))

    1981-01-01

    The effect of ionizing radiation on platelet function was investigated in vitro. Platelet-rich plasma (300x10/sup 9//l) was irradiated with doses of 1, 4, 10, 20 and 50 Gy. Platelet function tests were performed on both irradiated and control (non-irradiated) platelet samples. The platelet function tests were (1) platelet aggregation by ADP (1, 2, 4 ..mu..mol final concentration), adrenaline and collagen, (2) ADP-release from platelets, (3) clot retraction and (4) platelet factor-3 availability. It was found that roentgen irradiation of platelets in vitro did not affect these platelet function tests.

  17. 不同改性处理钛表面对血小板黏附行为影响的比较%Comparison of platelet adhesion behavior on pure titanium surfaces modified by different techniques

    Institute of Scientific and Technical Information of China (English)

    张璐; 宁成云; 滕伟; 王焱

    2015-01-01

    目的 评估不同改性钛表面的血小板黏附能力,分析表面性能对血小板黏附的影响,以期获得利于成骨的钛表面特征信息.方法 分别制备机械抛光、双酸酸蚀、喷砂酸蚀、微弧氧化和TiO2纳米管钛试件各21个,检测试件表面性能.在各组试件表面孵育血小板,检测血小板黏附量及黏附活性,观察血小板黏附分布和形态.结果 各组试件表面形貌差异明显,机械抛光、双酸酸蚀、喷砂酸蚀和微弧氧化组表面呈微米级形貌,TiO2纳米管组表面呈纳米级形貌,纳米管直径为(80.46±0.35)nm.微弧氧化组表面粗糙度最大;TiO2纳米管组表面粗糙度最小,表面接触角(13.55°±0.96°)最小;TiO2纳米管组表面血小板黏附量最大[(300 729±8 325)个/μl],血小板活性最高(A450值为2.14±0.05),血小板在纳米管表面密集分布,伸出伪足相互形成连接.结论 钛表面性能可影响血小板黏附能力;纳米形貌可显著改善血小板黏附行为;增加表面粗糙度、改善表面亲水性均利于血小板黏附.%Objective To evaluate the platelet adhesion ability on pure titanium surfaces modified with different techniques.Methods Pure titanium specimens were treated with 5 different surface modification techniques,including machine polish(MP),dual acid-etch(DAE),sandblast-large grit and acidetch(SLA),micro-arc oxidation(MAO) and anodized titania nanotube(TNT).The surface topographies of specimens were observed by scanning electron microscopy(SEM).Chemical compositions,surface roughness and static water contact angle of specimens were detected by energy dispersive spectrometer(EDS),laser scanning confocal microscope(LSCM) and contact angle analyzer respectively.Platelets were cultured on specimen surfaces for 30 min.The amount and viability of adhered platelets adhered were evaluated.Platelet distribution and morphology were observed by LSCM and SEM.Results Surface topographies of the five groups of specimens

  18. Investigation of adhesive properties of dental composite materials using an improved tensile test procedure and scanning electron microscopy.

    Science.gov (United States)

    Rider, M; Tanner, A N; Kenny, B

    1977-04-01

    A standardized tension test was used to evaluate the adhesive properties of several composite materials when used on both dentin and enamel specimens. The nature of the test surfaces was examined by roughness tests using a Talysurf machine and also in more detail by means of a scanning electron microscope. Poor results were obtained for the adhesion of composite materials to dentin whereas good retention to enamel was obtained.

  19. Mechanisms of xenogeneic baboon platelet aggregation and phagocytosis by porcine liver sinusoidal endothelial cells.

    Directory of Open Access Journals (Sweden)

    Qiang Peng

    Full Text Available BACKGROUND: Baboons receiving xenogeneic livers from wild type and transgenic pigs survive less than 10 days. One of the major issues is the early development of profound thrombocytopenia that results in fatal hemorrhage. Histological examination of xenotransplanted livers has shown baboon platelet activation, phagocytosis and sequestration within the sinusoids. In order to study the mechanisms of platelet consumption in liver xenotransplantation, we have developed an in vitro system to examine the interaction between pig endothelial cells with baboon platelets and to thereby identify molecular mechanisms and therapies. METHODS: Fresh pig hepatocytes, liver sinusoidal and aortic endothelial cells were isolated by collagenase digestion of livers and processing of aortae from GTKO and Gal+ MGH-miniature swine. These primary cell cultures were then tested for the differential ability to induce baboon or pig platelet aggregation. Phagocytosis was evaluated by direct observation of CFSE labeled-platelets, which are incubated with endothelial cells under confocal light microscopy. Aurintricarboxylic acid (GpIb antagonist blocking interactions with von Willebrand factor/vWF, eptifibatide (Gp IIb/IIIa antagonist, and anti-Mac-1 Ab (anti-α(Mβ(2 integrin Ab were tested for the ability to inhibit phagocytosis. RESULTS: None of the pig cells induced aggregation or phagocytosis of porcine platelets. However, pig hepatocytes, liver sinusoidal and aortic endothelial cells (GTKO and Gal+ all induced moderate aggregation of baboon platelets. Importantly, pig liver sinusoidal endothelial cells efficiently phagocytosed baboon platelets, while pig aortic endothelial cells and hepatocytes had minimal effects on platelet numbers. Anti-MAC-1 Ab, aurintricarboxylic acid or eptifibatide, significantly decreased baboon platelet phagocytosis by pig liver endothelial cells (P<0.01. CONCLUSIONS: Although pig hepatocytes and aortic endothelial cells directly caused

  20. Adhesion failure behavior of sputtered calcium phosphate thin film coatings evaluated using microscratch testing.

    Science.gov (United States)

    Toque, J A; Herliansyah, M K; Hamdi, M; Ide-Ektessabi, A; Sopyan, I

    2010-05-01

    It is generally accepted that calcium phosphate (CaP) is one of the most important biomaterials in implant coating applications mainly because of its excellent bioactivity. However, its relatively poor mechanical properties limits its application. This entails that a better understanding of the mechanical properties of a CaP coating is a must especially its behavior and the mechanisms involved when subjected to stresses which eventually lead to failure. The mechanical properties of the coating may be evaluated in terms of its adhesion strength. In this study, a radio frequency-magnetron (RF-MS) sputtering technique was used to deposit CaP thin films on 316L stainless steel (SS). The coatings were subjected to series of microscratch tests, taking careful note of its behavior as the load is applied. The adhesion behavior of the coatings showed varying responses. It was revealed that several coating process-related factors such as thickness, post-heat treatment and deposition parameters, to name a few, affect its scratching behavior. Scratch testing-related factors (i.e. loading rate, scratch speed, scratch load, etc.) were also shown to influence the mechanisms involved in the coating adhesion failure. Evaluation of the load-displacement graph combined with optical inspection of the scratch confirmed that several modes of failure occurred during the scratching process. These include trackside cracking, tensile cracking, radial cracking, buckling, delamination and combinations of one or more modes.

  1. A study on affecting factors by using dolly in coating adhesion test

    Energy Technology Data Exchange (ETDEWEB)

    Baek, Yun-Ho; Son, Seong-Mo; Park, Chung-Seo [Industrial Technology Institute, Hyundai Heavy Industries, Ulsan (Korea, Republic of)

    2014-10-15

    Establishment of adhesion strength measurement procedure for marine epoxy coatings was conducted in order to ensure reliability of the test results. It was found that (1) the increase in thickness of the substrates would induce increase of pull-off strength. Especially, the increase in adhesion strength with the substrate thickness increment was attributed to the transition of stress mode to the pure tensile mode excluding bending effect. (2) The longer curing time, the higher pull-off strength. It may be due to higher cross-linking density of the coating (3) The pull-off strength increases as coating thickness increases due to the diminishment of bending effect (4) The longer drying time after water immersion, the higher pull-off strength. It may be due to the evaporation of water molecule at the coating-substrate interface.

  2. A platelet P-selectin test predicts adverse cardiovascular events in patients with acute coronary syndromes treated with aspirin and clopidogrel.

    Science.gov (United States)

    Thomas, Mark R; Wijeyeratne, Yanushi D; May, Jane A; Johnson, Andrew; Heptinstall, Stan; Fox, Susan C

    2014-01-01

    There is wide variation in response to antiplatelet therapy and high on-treatment platelet reactivity is associated with adverse cardiovascular events. The objective here was to determine whether the results of a novel strategy for assessing platelet reactivity (based on P-selectin measurement) are associated with clinical outcomes in patients with acute coronary syndromes (ACS). This was a prospective cohort study of 100 ACS patients taking aspirin and clopidogrel. P-selectin tests designed to assess response to P2Y12 antagonists or aspirin were performed alongside light transmission aggregometry. For the P2Y12 P-selectin test, an optimal cutoff for high platelet reactivity was determined by receiver operating characteristic (ROC) curve analysis. Patients were divided into two cohorts based on this value: patients with (n = 42) or without (n = 58) high platelet reactivity. The primary endpoint was defined as the composite of cardiovascular death, myocardial infarction and stent thrombosis. After 12 months, the primary endpoint occurred in 12 patients. ROC curve analysis determined that the P2Y12 P-selectin test results were predictive of the primary endpoint (area under curve = 0.69, p = 0.046). The primary endpoint occurred more frequently in patients with high on-treatment platelet reactivity compared to those without (21.4% vs. 5.2%; hazard ratio (HR) 4.14; p = 0.026). The P2Y12 P-selectin test results correlated with light transmission aggregometry (Spearman p P-selectin test, only two patients demonstrated high on-treatment platelet reactivity. This study suggests that a P2Y12 P-selectin test is capable of detecting high on-treatment platelet reactivity, which is associated with subsequent cardiovascular events.

  3. Process Sensitivity, Performance, and Direct Verification Testing of Adhesive Locking Features

    Science.gov (United States)

    Golden, Johnny L.; Leatherwood, Michael D.; Montoya, Michael D.; Kato, Ken A.; Akers, Ed

    2012-01-01

    Phase I: The use of adhesive locking features or liquid locking compounds (LLCs) (e.g., Loctite) as a means of providing a secondary locking feature has been used on NASA programs since the Apollo program. In many cases Loctite was used as a last resort when (a) self-locking fasteners were no longer functioning per their respective drawing specification, (b) access was limited for removal & replacement, or (c) replacement could not be accomplished without severe impact to schedule. Long-term use of Loctite became inevitable in cases where removal and replacement of worn hardware was not cost effective and Loctite was assumed to be fully cured and working. The NASA Engineering & Safety Center (NESC) and United Space Alliance (USA) recognized the need for more extensive testing of Loctite grades to better understand their capabilities and limitations as a secondary locking feature. These tests, identified as Phase I, were designed to identify processing sensitivities, to determine proper cure time, the correct primer to use on aerospace nutplate, insert and bolt materials such as A286 and MP35N, and the minimum amount of Loctite that is required to achieve optimum breakaway torque values. The .1900-32 was the fastener size tested, due to wide usage in the aerospace industry. Three different grades of Loctite were tested. Results indicate that, with proper controls, adhesive locking features can be successfully used in the repair of locking features and should be considered for design. Phase II: Threaded fastening systems used in aerospace programs typically have a requirement for a redundant locking feature. The primary locking method is the fastener preload and the traditional redundant locking feature is a self-locking mechanical device that may include deformed threads, non-metallic inserts, split beam features, or other methods that impede movement between threaded members. The self-locking resistance of traditional locking features can be directly verified

  4. Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

    OpenAIRE

    Kilpi, Lauri; Ylivaara, Oili M.E.; Vaajoki, Antti; Malm, Jari; Sintonen, Sakari; Tuominen, Marko; Puurunen, Riikka L.; Ronkainen, Helena

    2016-01-01

    The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as LCSi1, LCSi2, LCALD1, and LCALD2, representing the failure p...

  5. In vitro viability effects on apheresis and buffy-coat derived platelets administered through infusion pumps

    Directory of Open Access Journals (Sweden)

    Sandgren P

    2014-12-01

    Full Text Available Per Sandgren,1,2 Veronica Berggren,3 Carl Westling,1,2 Viveka Stiller1 1Department of Clinical Immunology and Transfusion Medicine, Karolinska University Hospital, 2Department of Laboratory Medicine, Karolinska Institutet, 3Department of Neonatology, Karolinska University Hospital, Stockholm, SwedenBackground: Different infusion pump systems as well as gravity infusion have been widely used in neonatal transfusion. However, the limited number of published studies describing the use of infusion pumps on platelets illustrates the necessity for more robust data.Methods: To evaluate the potential in vitro effects on the cellular, metabolic, functional and phenotypic properties of platelets, we set up a four-arm paired study simultaneously comparing the use of different infusion pumps (Alaris® CC/GP with unexposed platelets. The platelet units (n=8 were either produced by the apheresis technique and suspended in 100% plasma or derived from buffy coats to yield platelet units stored in approximately 30% plasma and 70% SSP+. Fresh and 5-day old platelets were tested.Results: Regardless of the production system or storage time used, no significant differences were observed in glucose and lactate concentration, pH, adenosine triphosphate levels, response to extent of shape change, hypotonic shock response reactivity, and CD62P expression. Similarly, no differences were observed in expression of the conformational epitope on glycoprotein IIb/IIIa, determined using procaspase-activating compound 1, or in the expression of CD42b and platelet-endothelial cell adhesion molecule-1 in a comparison between platelets administered through infusion pumps versus unexposed platelets.Conclusion: Using Alaris CC/GP infusion pumps had no influence on the cellular, functional, and phenotypic in vitro properties of platelets. This fact seems not to be affected by different production systems or storage time.Keywords: platelets, neonatal platelet transfusion

  6. Platelet mimicry

    DEFF Research Database (Denmark)

    Moghimi, Seyed Moein; Hunter, Alan Christy; Peer, Dan

    2016-01-01

    Here we critically examine whether coating of nanoparticles with platelet membranes can truly disguise them against recognition by elements of the innate immune system. We further assess whether the "cloaking technology" can sufficiently equip nanoparticles with platelet-mimicking functionalities...

  7. Platelet Count

    Science.gov (United States)

    ... their spleen removed surgically Use of birth control pills (oral contraceptives) Some conditions may cause a temporary (transitory) increased ... increased platelet counts include estrogen and birth control pills (oral contraceptives). Mildly decreased platelet counts may be seen in ...

  8. On-ground testing of the role of adhesion in the LISA-Pathfinder test mass injection phase

    Science.gov (United States)

    Bortoluzzi, D.; Zanoni, C.; Conklin, J. W.

    2017-05-01

    Many space missions share the need to fly a free-falling body inside the spacecraft, as a reference for navigation and/or as a probe for the local gravitational field. When a mechanism is required to cage such an object during the launch phase, the need arises to release it to free-fall once the operational phase must be initiated in orbit. The criticality of this phase increases when the mechanical interfaces between the body and the mechanism are affected by adhesion and the actuation authority of the control system on the free-falling body is limited. Both conditions are realized in the LISA Pathfinder mission, which aims at injecting a gold-coated 2 kg cubic test mass into a nearly perfect geodesic trajectory to demonstrate the readiness of the developed technology for in-space gravity wave detection. The criticality of adhesion is widely recognized in space technology, because it can affect and jeopardize the functionality of mechanisms, when arising between moving parts. In the LISA Pathfinder case, metallic adhesion potentially plays a relevant role, mainly for two reasons. First, thanks to its properties (ductility, high surface energy) the gold coating on the proof mass easily produces cold weldings, especially in vacuum conditions. Second, the detachment of the proof mass from the releasing device occurs abruptly and a relevant influence of the separation velocity is expected on the strength of the welding. This can produce an excessive velocity of the proof mass at the retraction of the releasing device for the following capture and centring phase on behalf of the control system. A testing activity is performed to characterize the dynamic behaviour of the adhesive bonds between the proof mass and the releasing device, which can be used to predict their contribution on the residual velocity of the proof mass after in-flight release. The study of such a dynamic phenomenon sets some challenging requirements on the measurement technique, both on the

  9. The use of platelet reactivity testing in patients on antiplatelet therapy for prediction of bleeding events after cardiac surgery

    NARCIS (Netherlands)

    Leunissen, Tesse C; Janssen, Paul; Ten Berg, Jur; Moll, Frans L; Korporaal, Suzanne J A; de Borst, Gert Jan; Pasterkamp, Gerard; Urbanus, Rolf T

    Many patients are treated with platelet inhibitors such as aspirin and clopidogrel for prevention of thrombotic cardiovascular events. However, the inhibitory effect of antiplatelet therapy is variable between patients; in some, the platelets are hardly inhibited, while in others, the platelets are

  10. Thermal and tensile strength testing of thermally-conductive adhesives and carbon foam

    CERN Document Server

    Chertok, Maxwell; Irving, Michael; Neher, Christian; Shi, Mengyao; Tolfa, Kirk; Tripathi, Mani; Vinson, Yasmeen; Wang, Ruby; Zheng, Gayle

    2016-01-01

    Future collider detectors, including silicon tracking detectors planned for the High Luminosity LHC, will require components and mechanical structures providing unprecedented strength-to-mass ratios, thermal conductivity, and radiation tolerance. This paper studies carbon foam used in conjunction with thermally conductive epoxy and thermally conductive tape for such applications. Thermal conductivity and tensile strength measurements of aluminum-carbon foam-adhesive stacks are reported. Initial radiation damage tests are also presented. These results can inform bonding method choices for future tracking detectors.

  11. Platelets: bridging hemostasis, inflammation, and immunity.

    Science.gov (United States)

    Jenne, C N; Urrutia, R; Kubes, P

    2013-06-01

    Although the function of platelets in the maintenance of hemostasis has been studied in great detail, more recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Platelets by virtue of their large numbers and their ability to rapidly release a broad spectrum of immunomodulatory cytokines, chemokines, and other mediators act as circulating sentinels. Upon detection of a pathogen, platelets quickly activate and begin to drive the ensuing inflammatory response. Platelets have the ability to directly modulate the activity of neutrophils (phagocytosis, oxidative burst), endothelium (adhesion molecule and chemokine expression), and lymphocytes. Due to their diverse array of adhesion molecules and preformed chemokines, platelets are able to adhere to leukocytes and facilitate their recruitment to sites of tissue damage or infection. Furthermore, platelets directly participate in the capture and sequestration of pathogens within the vasculature. Platelet-neutrophil interactions are known to induce the release of neutrophil extracellular traps (NETs) in response to either bacterial or viral infection, and platelets have been shown to internalize pathogens, sequestering them in engulfment vacuoles. Finally, emerging data indicate that platelets also participate in the host immune response by directly killing infected cells. This review will highlight the central role platelets play in the initiation and modulation of the host inflammatory and immune responses.

  12. Performance and durability tests of smart icephobic coatings to reduce ice adhesion

    Science.gov (United States)

    Janjua, Zaid A.; Turnbull, Barbara; Choy, Kwang-Leong; Pandis, Christos; Liu, Junpeng; Hou, Xianghui; Choi, Kwing-So

    2017-06-01

    The accretion of ice can cause damage in applications ranging from power lines and shipping decks, to wind turbines and rail infrastructure. In particular on aircraft, it can change aerodynamic characteristics, greatly affecting the flight safety. Commercial aircraft are therefore required to be equipped with de-icing devices, such as heating mats over the wings. The application of icephobic coatings near the leading edge of a wing can in theory reduce the high power requirements of heating mats, which melt ice that forms there. Such coatings are effective in preventing the accretion of runback ice, formed from airborne supercooled droplets, or the water that the heating mats generate as it is sheared back over the wing's upper surface. However, the durability and the practicality of applying them over a large wing surface have been prohibitive factors in deploying this technology so far. Here, we evaluated the ice adhesion strength of four non-conductive coatings and seven thermally conductive coatings by shearing ice samples from coated plates by spinning them in a centrifuge device. The durability of the coating performance was also assessed by repeating the tests, each time regrowing ice samples on the previously-used coatings. Contact angle parameters of each coating were tested for each test to determine influence on ice adhesion strength. The results indicate that contact angle hysteresis is a crucial parameter in determining icephobicity of a coating and hydrophobicity is not necessarily linked to icephobicity.

  13. Influence of red algal sulfated polysaccharides on blood coagulation and platelets activation in vitro.

    Science.gov (United States)

    Sokolova, Ekaterina V; Byankina, Anna O; Kalitnik, Alexandra A; Kim, Yong H; Bogdanovich, Larisa N; Solov'eva, Tamara F; Yermak, Irina M

    2014-05-01

    The influence of sulfated polysaccharides (λ-, κ-, and κ/β-carrageenan and porphyran) - on platelet activation was studied. Carrageenans were much weaker inhibitors of a coagulation process than heparin, while porphyran had not that effect. Results of the aPTT and PT assays suppose that carrageenans affected mostly intrinsic pathway of coagulation, while their effect on the extrinsic pathway is extremely low (λ and κ/β) or absent (κ, LMW derivative of κ-carrageenan). λ-Carrageenan was the most potent anticoagulant agent in TT, aPTT, PT, and anti-factor Xa activity. This sample was also the strongest inhibitor of collagen-induced platelet aggregation in PRP. Generally, the correlation of anticoagulant and antithrombotic action in PRP is preserved for carrageenans but not for heparin. Carrageenans and porphyran affected platelet adhesion to collagen by influencing glycoprotein VI. Low molecular weight κ-carrageenan had a similar effect on platelet adhesion mediated with both major collagen receptors: integrin α2 β1 and glycoprotein VI as native polysaccharide had. Carrageenans resulted in activation of platelets under platelet adhesion mediated by integrin αIIb β3 with less degree than heparin. The least sulfated κ/β-carrageenan that possessed an inhibiting effect on thrombin- and collagen-induced aggregation of washed platelets and on the PT test but it had no significant effect on TT was the weakest promoter of integrin αIIb β3 mediated platelet activation. In summary, our study showed that the polysaccharide action was complex, since it depended on its molecular mass, sulfation degree, and monosaccharide contents (3,6-anhydrogalactose).

  14. The effects of Lonomin V, a toxin from the caterpillar (Lonomia achelous), on hemostasis parameters as measured by platelet function.

    Science.gov (United States)

    Guerrero, Belsy; Arocha-Piñango, Carmen L; Salazar, Ana M; Gil, Amparo; Sánchez, Elda E; Rodríguez-Acosta, Alexis; Lucena, Sara

    2011-09-15

    Platelets play a central role in hemostasis during vascular injury. Patients affected with the hemorrhagic syndrome caused by contact with Lonomia achelous caterpillars (Lac) Lepidoptera distributed in various South American countries, show digestive, pulmonary and intraperitoneal bleeding in combination with hematomas and echymosis. In the present study, we have evaluated the effects of Lonomin V (serine protease isolated from Lac hemolymph) on some functional properties of platelets, evaluating its importance in primary hemostasis. Platelet adhesion to fibrinogen was reduced by 19, 20, 36, and 37% after pre-treated with 0.2, 2, 20 and 40 nM of Lonomin V, respectively. Pre-incubation of the platelets with 408 nM of Lonomin V, for 4 min at 37 °C, resulted in complete inhibition of the collagen-induced platelet aggregation, in contrast to 56% inhibition of the ADP - induced platelet aggregation. Lonomin V also inhibited anti-α(IIb)β(3) integrin binding to platelets by 56, 57, 52 and 54% at concentrations of 0.2, 2, 20 and 40 nM respectively. Additionally, Lonomin V inhibited anti-P-selectin binding to platelets by 28, 37, 33 and 33% at the same concentrations. The platelets tested with Lonomin V did not modify their viability. In summary, Lonomin V inhibited platelet aggregation, probably caused by the degradation of collagen. The anti-platelet activity of Lonomin V has been shown to be unique and a potentially useful tool for investigating cell-matrix and cell-cell interactions and for the development of antithrombotic agents in terms of their anti-adhesive activities.

  15. Flight Testing Surfaces Engineered for Mitigating Insect Adhesion on a Falcon HU-25C

    Science.gov (United States)

    Shanahan, Michelle; Wohl, Chris J.; Smith, Joseph G., Jr.; Connell, John W.; Siochi, Emilie J.; Doss, Jereme R.; Penner, Ronald K.

    2015-01-01

    Insect residue contamination on aircraft wings can decrease fuel efficiency in aircraft designed for natural laminar flow. Insect residues can cause a premature transition to turbulent flow, increasing fuel burn and making the aircraft less environmentally friendly. Surfaces, designed to minimize insect residue adhesion, were evaluated through flight testing on a Falcon HU-25C aircraft flown along the coast of Virginia and North Carolina. The surfaces were affixed to the wing leading edge and the aircraft remained at altitudes lower than 1000 feet throughout the flight to assure high insect density. The number of strikes on the engineered surfaces was compared to, and found to be lower than, untreated aluminum control surfaces flown concurrently. Optical profilometry was used to determine insect residue height and areal coverage. Differences in results between flight and laboratory tests suggest the importance of testing in realistic use environments to evaluate the effectiveness of engineered surface designs.

  16. Adhesive strength of CVD diamond thin films quantitatively measured by means of the bulge and blister test

    Institute of Scientific and Technical Information of China (English)

    Daohui Xiang; Ming Chen; Yuping Ma; Fanghong Sun

    2008-01-01

    Large advancement has been made in understanding the nucleation and growth of chemical vapor deposition (CVD) diamond, but the adhesion of CVD diamond to substrates is poor and there is no good method for quantitative evaluation of the adhesive strength. The blister test is a potentially powerful tool for characterizing the mechanical properties of diamond films. In this test, pressure was applied on a thin membrane and the out-of-plane deflection of the membrane center was measured. The Young's modulus, residual stress, and adhesive strength were simultaneously determined using the load-deflection behavior of a membrane. The free-standing window sample of diamond thin films was fabricated by means of photolithography and anisotropic wet etching. The research indicates that the adhesive strength of diamond thin films is 4.28±0.37J/m2. This method uses a simple apparatus, and the fabrication of samples is very easy.

  17. Experimental Antithrombotic Effect of Garlic Varieties Measured by a Global In Vitro Test of Platelet Reactivity and Spontaneous Thrombolytic Activity

    Directory of Open Access Journals (Sweden)

    Yoshinobu Ijiri

    2016-06-01

    Full Text Available Prevention of arterial thrombotic diseases has high priority over treatment in developed countries. Unsuitable life style such as inappropriate quality and quantity of daily diet is known to increase the risk for acute thrombotic events, while a regular diet with proven antithrombotic effects might be beneficial in preventing the disease. The present study was undertaken as a part of a series of research in screening vegetables, fruits and medicinal herbs for antithrombotic activity by animal models of thrombosis. In the present study the effects of fifteen garlic varieties (accessions on platelet reactivity and spontaneous (endogenous thrombolytic activity were measured ex vivo from saline-diluted rat blood by the Global Thrombosis Test (GTT. All accessions showed antithrombotic activity but the activity varied between accessions. The heat stable antithrombotic activity was dominantly due to inhibition of platelet reactivity to high shear stress while the spontaneous thrombolytic activity was not affected. These findings suggest that daily intake of garlic as part of an antithrombotic diet may be beneficial for the prevention of arterial thrombotic disorders.

  18. Antimicrobial/anti-biofilm activity of expired blood platelets and their released products 

    Directory of Open Access Journals (Sweden)

    Marcin I. Różalski

    2013-04-01

    Full Text Available Introduction. Although platelets are not part of the classical immune system, they have many features that indicate their role in the anti-infective host defense. They come into interactions with microorganisms, which results in co-aggregation and co-adhesion or destruction of themicrobes due to the action of antimicrobial peptides released from platelets.The aim of this study was to evaluate the killing effect of platelets against planktonic and biofilm cultures of Staphylococcus aureus and to test their synergy with antibiotics. Materials and Methods. S. aureus ATCC 29213; platelet rich plasma (1-3 days post shelf life. Evaluation of bactericidal activity of platelets or their lysates against planktonic cultures of S. aureus – CFU calculation after 4- and 24-hour co-incubation. Assessment of S. aureus biofilm viability under the influence of platelets – Live/Dead® BacLightTM Bacterial Viability Kit. Determination of minimum inhibitory concentrations (MICs (oxacillin, vancomycin, linezolid and estimation of the synergistic action of antibiotics and platelet lysates – a gradient-diffusion test strip. Results. Microbicidal activity of “expired” platelets and their lysates has been shown as a significant reduction in the population of staphylococci in their planktonic cultures by 56-87�0and a decrease in metabolic activity of biofilm formation by 7-38�20These activities were enhanced after activation with ADP. Platelet lysates showed a synergistic effect with β-lactam antibiotic (oxacillin and glycopeptide (vancomycin but not with oxazolidinone (linezolid. Conclusions and Discussion. In summary, platelets even after the medical expiry date are still a good source of antimicrobial low molecular weight proteins (PMPs. Testing of bacterialresistance to PMPs may be advisable as a predictive indicator of susceptibility to treatment of infections such as infective endocarditis and other local infections of biofilm nature.

  19. Platelet-Rich Plasma for Frozen Shoulder: A Case Report

    Directory of Open Access Journals (Sweden)

    Hamidreza Aslani

    2016-01-01

    Full Text Available Frozen shoulder is a glenohumeral joint disorder that perturbs movement because of adhesion and the existence of fibrosis in the shoulder capsule. Platelet-rich plasma can produce collagen and growth factors, which increases stem cells and consequently enhances the healing. To date, there is no evidence regarding the effectiveness of platelet-rich plasma in frozen shoulder. A 45-year-old man with shoulder adhesive capsulitis volunteered for this treatment. He underwent two consecutive platelet-rich plasma injections at the seventh and eighth month after initiation of symptoms. We measured pain, function, and ROM by the visual analogue scale (VAS, and scores from the Disabilities of the Arm, Shoulder and Hand (DASH questionnaire and goniometer; respectively. After the first injection, the patient reported 60% improvement regarding diurnal shoulder pain, and no night pains. Also, two-fold improvement for ROM and more than 70% improvement for function were reported. This study suggests the use of platelet-rich plasma in frozen shoulder to be tested in randomized trials.

  20. Investigation of Adhesion and Fracture Toughness of Thermally Grown Oxide Scales by Interface Indentation Test

    Institute of Scientific and Technical Information of China (English)

    QI Yu-hong; p. Bruckel; P. Lours; ZHANG Zhan-ping

    2004-01-01

    The adhesion and the fracture toughness of thermally grown oxide scales for pure nickel were investigated using Vickers indentation technique. The nickel samples were oxidised at 1200℃ for 100h-600h. The crack length induced by Vickers indentation test at NiO/Ni interface increases linearly with the incresing of the applied load in a logarithmic scale for each oxide thickness. There is a critical load Pc, when the applied load P>Pc, the crack is produced at the oxide/metal interface. The critical load Pc decreases with the increasing of the oxide thickness. Therefore, the relation between the critical load Pc and the oxide thickness ho may be used as describing the adhesion of of thermally grown oxide scales. For pure nickel, the Pc-ho relation can be represented by the equation Pc = 761439e-0.0695h. The fracture toughness in oxide and at the interface decrease with the increasing of the oxide thickness in equation Ko = -1.0214Ln(ho) + 7.3382 (in oxide) and Ki = 529.71ho-0.9424 (at the interface). And there is a higher fracture toughness at the NiO/Ni interface. Therefore,for pure nickel, the oxide/metal interface is stronger than the oxide.

  1. Investigation of Adhesion and Fracture Toughness of Thermally Grown Oxide Scales by Interface Indentation Test

    Institute of Scientific and Technical Information of China (English)

    QIYu-hong; P.Bruckel; P.Lours; ZHANGZhan-ping

    2004-01-01

    The adhesion and the fracture toughness of thermally grown oxide scales for pure nickel were investigated using Vickers indentation technique. The nickel samples were oxidised at 1200℃ for 100h-600h. The crack length induced by Vickers indentation test at NiO/Ni interface increases linearly with the incresing of the applied load in a logarithmic scale for each oxide thickness. There is a critical load Pc, when the applied load P>Pc, the crack is produced at the oxide/metal interface. The critical load Pc decreases with the increasing of the oxide thickness. Therefore, the relation between the critical load Pc and the oxide thickness ho may be used as describing the adhesion of of thermally grown oxide scales. For pure nickel, the Pc-ho relation can be represented by the equatiun Pc=761439e-0.0695k, The fracture toughness in oxide and at the interlace decrease with the increasing of the oxide thickness in equation Ko=-1.0214Ln(h0)+7.3382 (in oxide) and Ki=529.71h-0.5424 (at the interface). And there is a higher fracture toughness at the NiO/Ni interlace. Theretore, for pure nickel, the oxide/metal interface is stronger than the oxide.

  2. PFA-100 test in the detection of platelet dysfunction and monitoring DDAVP in a patient with liver cirrhosis undergoing inguinal hernia repair

    Directory of Open Access Journals (Sweden)

    Vučelić Dragica

    2012-01-01

    Full Text Available Introduction. Hemostatic abnormalities in liver cirrhosis are complex and multifactorial and may predispose to prolonged hemorrhage following invasive procedures. Due to increased perioperative bleeding risks, patients with cirrhosis should undergo elective surgery after making medical preparations. It has been shown that 1-deamino-8-D-arginine vasopressin (DDAVP, desmopressin, can be used as a safe and effective remedy in preventing and treating bleeding in cirrhotics. However, there is still scarce information of adequate test(s for assessing effects of DDAVP in platelet dysfunction. The use of platelet function analyzer-100 (PFA-100 allows more reliable assessment of impaired primary hemostasis as well as follow-up of hemostatic changes induced by DDAVP effects. Case Outline. In a 49-year-old male with ethylic liver cirrhosis and prolonged bleeding time scheduled for elective left side inguinal hernia repair, we carried out PFA-100 testing to investigate the patient’s platelet functional status. Results were affirmative for the presence of platelet functional problems. By standard coagulation tests the patient was also identified as having secondary hemostasis. Preoperatively, PFA-100 was used to test the patient’s response to a standard dose of DDAVP, which was favorable. The patient was operated after medical preparations with DDAVP and vitamin K. Neither bleeding complications nor side effects of DDAVP were recorded in the perioperative period. Conclusion. The PFA-100 is a simple and reliable test for the assessment of primary hemostasis as well as in monitoring of DDAVP therapy.

  3. Gangliosides regulate tumor cell adhesion to collagen.

    Science.gov (United States)

    Kazarian, Tamara; Jabbar, Adnan A; Wen, Fei-Qui; Patel, Dharmesh A; Valentino, Leonard A

    2003-01-01

    The ability of tumor cells to adhere to extracellular matrix proteins is critical for migration and invasion. The factors that regulate tumor cell adhesion are poorly characterized. Gangliosides promote platelet adhesion and may also play a role in the adhesion of other cell types. We hypothesized that pharmacological depletion of membrane gangliosides from adherent cells would abrogate adhesion to collagen and promote migration and invasion. To test these hypotheses, LA-N1 neuroblastoma cells, which avidly adhere to collagen and are rich with membrane gangliosides (43.69 nmol/10(8) cells), were cultured in the presence of D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol-HCl. Endogenous gangliosides were reduced by 98% (0.76 nmol/10(8) cells) and adhesion to collagen decreased by 67%. There were no changes in cell morphology, viability, proliferation rate or apoptosis. Pre-incubation of ganglioside-depleted cells in conditioned medium from control cells restored adhesion to collagen (0.45 +/- 0.002), comparable to that of control cells (0.49 +/- 0.035). Similarly, pre-incubation of ganglioside-depleted cells with purified GD2 completely restored adhesion in a concentration-dependent manner. When LA-N1 cells were cultured with retinoic acid, a biological response modifier known to increase endogenous gangliosides, adhesion to collagen increased. Next, we questioned whether changes in adhesion would be reflected as changes in migration and invasion. Cells depleted of endogenous cellular gangliosides migrated more than control cells. Finally, control cells replete with their endogenous gangliosides demonstrated less invasive potential than control cells. The data demonstrate that endogenous tumor gangliosides increase neuroblastoma cell adhesion to collagen and reduce migration and invasion in vitro.

  4. 血小板内皮细胞黏附分子-1(PECAM-1)与肿瘤关系研究进展%Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1) and Tumor

    Institute of Scientific and Technical Information of China (English)

    袁梅琴; 钟海均

    2016-01-01

    Platelet endothelial cell adhesion molecule-1 ( PECAM-1 ) is one of the immunoglobulin superfamily cell adhesion molecules, and is the key factor involved in platelet adhesion and aggregation.The gene and protein structure of PECAM-1 has been already studied.The studies have found that adhesion effect mediated by PECAM-1 including cells and cells,cells and extracellular matrix is closely related to a variety of physiological reaction;and PE-CAM-1 also have the vital significance in inflammation,wound healing and angiogenesis and so on;A variety of disea-ses,especially cardiovascular diseases such as atherosclerosis disease,are closely related to PECAM-1,and PECAM-1 gene polymorphism may affect the function of PECAM-1.Further studies indicate that PECAM-1 plays an important role in tumor growth as an adhesion factor,but its roles in different tumors,the methods and mechanisms of PECAM-1 are still not clear,and need further exploration.Treatments of anti-PECAM-1 have greatly inspired us.In this pa-per,the relationships between PECAM-1 and tumors,and associated research progress have been reviewed as follows.%血小板内皮细胞粘附分子-1(PECAM-1)是免疫球蛋白超家族细胞粘附分子中的一种,是参与血小板黏附和聚集的关键因子,对其基因及蛋白质结构已进行了较为深入的研究。研究发现,PECAM-1所介导的细胞与细胞、细胞与细胞外基质间黏附作用与多种生理反应密切相关;也在炎症反应、创伤愈合及血管生成等多方面均具有重要的意义;多种疾病尤其是心血管疾病如动脉粥样硬化等的发病与 PECAM-1也密切相关,且PECAM-1的基因多态性也会影响PECAM-1的功能。近期越来越多的研究已表明PECAM-1作为黏附因子在肿瘤生长中起着重要作用,但对其在不同肿瘤中的作用、作用方式及机制仍未明确,需要进一步探索。而抗 PECAM-1治疗的情况也很大程度上鼓舞了我们。本文就 PECAM

  5. Platelet proteomics.

    Science.gov (United States)

    Zufferey, Anne; Fontana, Pierre; Reny, Jean-Luc; Nolli, Severine; Sanchez, Jean-Charles

    2012-01-01

    Platelets are small cell fragments, produced by megakaryocytes, in the bone marrow. They play an important role in hemostasis and diverse thrombotic disorders. They are therefore primary targets of antithrombotic therapies. They are implicated in several pathophysiological pathways, such as inflammation or wound repair. In blood circulation, platelets are activated by several pathways including subendothelial matrix and thrombin, triggering the formation of the platelet plug. Studying their proteome is a powerful approach to understand their biology and function. However, particular attention must be paid to different experimental parameters, such as platelet quality and purity. Several technologies are involved during the platelet proteome processing, yielding information on protein identification, characterization, localization, and quantification. Recent technical improvements in proteomics combined with inter-disciplinary strategies, such as metabolomic, transcriptomics, and bioinformatics, will help to understand platelets biological mechanisms. Therefore, a comprehensive analysis of the platelet proteome under different environmental conditions may contribute to elucidate complex processes relevant to platelet function regarding bleeding disorders or platelet hyperreactivity and identify new targets for antiplatelet therapy.

  6. Efficacy of microtensile versus microshear bond testing for evaluation of bond strength of dental adhesive systems to enamel

    NARCIS (Netherlands)

    El Zohairy, A.A.; Saber, M.H.; Abdalla, A.I.; Feilzer, A.J.

    2010-01-01

    Objective The aim of the study was to evaluate the efficacy of the microtensile bond test (μTBS) and the microshear bond test (μSBS) in ranking four dental adhesives according to bond strength to enamel and identify the modes of failure involved. Materials and methods Forty-four caries-free human

  7. An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Hvas, Anne-Mette; Nybo, Mads

    2014-01-01

    in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone and Plate[let] analyser™ predict bleeding in selected thrombocytopenic populations...

  8. Restoration of non-carious cervical lesions with ceramic inlays: A possible model for clinical testing of adhesive cements

    Directory of Open Access Journals (Sweden)

    Michal Staninec

    2012-01-01

    Full Text Available Introduction: There are many luting cements coming to market which claim to be adhesive, but there is no clinical protocol currently for testing these claims. There is a standardized protocol for testing direct restorations bonded to dentin and it is used extensively. Case Report: We describe a clinical procedure for restoring a non-carious cervical lesion (NCCL with a ceramic inlay using Computer-Aided Design and Computer-Aided Manufacturing (CAD-CAM technology and an adhesive resin cement.The procedure was straightforward and the result was good at one month. Discussion: NCCL′s can be restored with CAD-CAM technology in one appointment. This technique can be used to clinically test adhesion of luting cements to dentin, similarly to the current standard for direct restorations.

  9. Distension test in passive external rotation: Validation of a new clinical test for the early diagnosis of shoulder adhesive capsulitis.

    Science.gov (United States)

    Noboa, E; López-Graña, G; Barco, R; Antuña, S

    2015-01-01

    The aim of this study is to evaluate the internal validity of a clinical test for the early diagnosis of shoulder adhesive capsulitis, called the Distension Test in Passive External Rotation (DTPER). The DTPER is performed with the patient standing up, the arm adducted, and the elbow bent at 90°. From this position, a smooth passive external rotation is started, the affected arm being supporting at the wrist with one hand of the examiner and the other maintaining the adducted elbow until the maximum painless point of the rotation is reached. From this point of maximum external rotation with the arm in adduction and with no pain, an abrupt distension movement is made, increasing the external rotation, causing pain in the shoulder if the test is positive. This term was performed on a group of patients with shoulder pain of many origins, in order to analyse the predictive values, sensitivity, specificity, and the likelihood ratio. The DTPER showed a sensitivity of 100% (95% CI; 91.8 to 100%) and a specificity of 90% (95% CI; 82.4 to 94.8%). The positive predictive value was 0.62 and a likelihood ratio of 10.22 (95% CI; 5.5 to 19.01). False positives were only found in patients with subscapular tendinopathies or glenohumeral arthrosis. The DTPER has a high sensitivity for the diagnosis of adhesive capsulitis, and is excluded when it is practically negative. False positives can easily be identified if there is external rotation with no limits (subscapular tendinopathy) or with a simple shoulder X-ray (glenohumeral arthrosis). Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  10. Use of Acoustic Emission During Scratch Testing for Understanding Adhesion Behavior of Aluminum Nitride Coatings

    Science.gov (United States)

    Choudhary, R. K.; Mishra, P.

    2016-06-01

    In this work, acoustic emission during scratch testing of the aluminum nitride coatings formed on stainless steel substrate by reactive magnetron sputtering was analyzed to assess the coating failure. The AlN coatings were formed under the variation of substrate temperature, substrate bias potential, and discharge power. The coatings deposited in the temperature range of 100 to 400 °C showed peak acoustic emission less than 1.5%, indicating ductile nature of the coating. However, for coatings formed with substrate negative bias potential of 20 to 50 V, numerous sharp acoustic bursts with maximum emission approaching 80% were observed, indicating brittle nature of the coatings with large number of defects present. The shift in the intensity of the first major acoustic peak toward higher load, with the increasing bias potential, confirmed improved adhesion of the coating. Also, the higher discharge power resulted in increased acoustic emission.

  11. Determination of residual 4'-aminomethyl-4,5',8-trimethylpsoralen and mutagenicity testing following psoralen plus UVA treatment of platelet suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, S.J.; Robinette, D.; Dodd, R.Y. (American Red Cross Blood Services, Rockville, MD (United States). Jerome H. Holland Lab. for Biomedical Sciences); White, R.; Wolf, L.; Chapman, J. (Baxter Biotech, Round Lake, IL (United States). Fenwal Labs.); Lawlor, T.E. (Hazleton Labs., Vienna, VA (United States). Molecular and Cellular Toxicology)

    1993-05-01

    Psoralens and UVa light have been used in the laboratory to study the inactivation of viruses that may be infrequently present in platelet concentrates prepared for transfusion. In order to evaluate safety aspects of the treatment of platelet suspensions with 4'-aminomethyl-4,5'8-trimethylpsoralen (AMT), the authors have investigated the residual levels and mutagenic potential of AMT after UVA phototreatment. The results suggest that residual available AMT is mutagenic in the AMES test and that the observed frameshift mutations may be caused by binding of AMt or its metabolites to nucleic acids in the absence of UVA light. (Author).

  12. Microscratch testing method for systematic evaluation of the adhesion of atomic layer deposited thin films on silicon

    Energy Technology Data Exchange (ETDEWEB)

    Kilpi, Lauri, E-mail: Lauri.Kilpi@vtt.fi; Ylivaara, Oili M. E.; Vaajoki, Antti; Puurunen, Riikka L.; Ronkainen, Helena [VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT (Finland); Malm, Jari [Department of Physics, University of Jyväskylä, P.O. Box 35, Jyväskylä 40014 (Finland); Sintonen, Sakari [Department of Micro- and Nanosciences, Aalto University School of Electrical Engineering, P.O. Box 13500, FI-00076 AALTO (Finland); Tuominen, Marko [ASM Microchemistry Oy, Pietari Kalmin katu 1 F 2, FIN-00560 Helsinki (Finland)

    2016-01-15

    The scratch test method is widely used for adhesion evaluation of thin films and coatings. Usual critical load criteria designed for scratch testing of coatings were not applicable to thin atomic layer deposition (ALD) films on silicon wafers. Thus, the bases for critical load evaluation were established and the critical loads suitable for ALD coating adhesion evaluation on silicon wafers were determined in this paper as L{sub CSi1}, L{sub CSi2}, L{sub CALD1}, and L{sub CALD2}, representing the failure points of the silicon substrate and the coating delamination points of the ALD coating. The adhesion performance of the ALD Al{sub 2}O{sub 3}, TiO{sub 2}, TiN, and TaCN+Ru coatings with a thickness range between 20 and 600 nm and deposition temperature between 30 and 410 °C on silicon wafers was investigated. In addition, the impact of the annealing process after deposition on adhesion was evaluated for selected cases. The tests carried out using scratch and Scotch tape test showed that the coating deposition and annealing temperature, thickness of the coating, and surface pretreatments of the Si wafer had an impact on the adhesion performance of the ALD coatings on the silicon wafer. There was also an improved load carrying capacity due to Al{sub 2}O{sub 3}, the magnitude of which depended on the coating thickness and the deposition temperature. The tape tests were carried out for selected coatings as a comparison. The results show that the scratch test is a useful and applicable tool for adhesion evaluation of ALD coatings, even when carried out for thin (20 nm thick) coatings.

  13. Superhydrophobic and adhesive properties of surfaces: testing the quality by an elaborated scanning electron microscopy method.

    Science.gov (United States)

    Ensikat, Hans J; Mayser, Matthias; Barthlott, Wilhelm

    2012-10-09

    In contrast to advancements in the fabrication of new superhydrophobic materials, the characterization of their water repellency and quality is often coarse and unsatisfactory. In view of the problems and inaccuracies, particularly in the measurement of very high contact angles, we developed alternative methods for the characterization of superhydrophobic surfaces. It was found that adhering water remnants after immersion are a useful criterion in determining the repellency quality. In this study, we introduce microscopy methods to detect traces of water-resembling test liquids on superhydrophobic surfaces by scanning electron microscopy (SEM) or fluorescence light microscopy (FLM). Diverse plant surfaces and some artificial superhydrophobic samples were examined. Instead of pure water, we used aqueous solutions containing a detectable stain and glycerol in order to prevent immediate evaporation of the microdroplets. For the SEM examinations, aqueous solutions of lead acetate were used, which could be detected in a frozen state at -90 °C with high sensitivity using a backscattered electron detector. For fluorescence microscopy, aqueous solutions of auramine were used. On different species of superhydrophobic plants, varying patterns of remaining microdroplets were found on their leaves. On some species, drop remnants occurred only on surface defects such as damaged epicuticular waxes. On others, microdroplets regularly decorated the locations of increased adhesion, particularly on hierarchically structured surfaces. Furthermore, it is demonstrated that the method is suitable for testing the limits of repellency under harsh conditions, such as drop impact or long-enduring contact. The supplementation of the visualization method by the measurement of the pull-off force between a water drop and the sample allowed us to determine the adhesive properties of superhydrophobic surfaces quantitatively. The results were in good agreement with former studies of the water

  14. Platelet lipidomic.

    Science.gov (United States)

    Dolegowska, B; Lubkowska, A; De Girolamo, L

    2012-01-01

    Lipids account for 16-19 percent dry platelet matter and includes 65 percent phospholipids, 25 percent neutral lipids and about 8 percent glycosphingolipids. The cell membrane that surrounds platelets is a bilayer that contains different types phospholipids symmetrically distributed in resting platelets, such as phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine, and sphingomyelin. The collapse of lipid asymmetry is exposure of phosphatidylserine in the external leaflet of the plasma bilayer, where it is known to serve at least two major functions: providing a platform for development of the blood coagulation cascade and presenting the signal that induces phagocytosis of apoptotic cells. During activation, this asymmetrical distribution becomes disrupted, and PS and PE become exposed on the cell surface. The transbilayer movement of phosphatidylserine is responsible for the platelet procoagulant activity. Exposure of phosphatidylserine is a flag for macrophage recognition and clearance from the circulation. Platelets, stored at room temperature for transfusion for more than 5 days, undergo changes collectively known as platelet storage lesions. Thus, the platelet lipid composition and its possible modifications over time are crucial for efficacy of platelet rich plasma therapy. Moreover, a number of substances derived from lipids are contained into platelets. Eicosanoids are lipid signaling mediators generated by the action of lipoxygenase and include prostaglandins, thromboxane A2, 12-hydroxyeicosatetraenoic acid. Isoprostanes have a chemical structure similar to this of prostanoids, but are differently produced into the particle, and are ligands for prostaglandins receptors, exhibiting biological activity like thromboxane A2. Endocannabinoids are derivatives from arachidonic acid which could reduce local pain. Phospholipids growth factors (sphingolipids, lysophosphatidic acid, platelet-activating factor) are involved in tissue

  15. Study of change in dispersion and orientation of clay platelets in a polymer nanocomposite during tensile test by variostage small-angle X-ray scattering

    CSIR Research Space (South Africa)

    Bandyopadhyay, J

    2012-04-01

    Full Text Available To understand the change in dispersion and orientation of clay platelets in three-dimensional space during tensile test, neat polymer and its nanocomposite samples were studied by small- and wide-angle X-ray scattering (SWAXS). The samples after...

  16. Overview of platelet physiology and laboratory evaluation of platelet function.

    Science.gov (United States)

    Rodgers, G M

    1999-06-01

    Appropriate laboratory testing for the platelet-type bleeding disorders hinges on an adequate assessment in the history and physical examination. Patients with histories and screening laboratory results consistent with coagulation disorders (hemophilia, disseminated intravascular coagulation) are not appropriate candidates for platelet function testing. In contrast, patients with a lifelong history of platelet-type bleeding symptoms and perhaps a positive family history of bleeding would be appropriate for testing. Figure 6 depicts one strategy to evaluate these patients. Platelet morphology can easily be evaluated to screen for two uncommon qualitative platelet disorders: Bernard-Soulier syndrome (associated with giant platelets) and gray platelet syndrome, a subtype of storage pool disorder in which platelet granulation is morphologically abnormal by light microscopy. If the bleeding disorder occurred later in life (no bleeding with surgery or trauma early in life), the focus should be on acquired disorders of platelet function. For those patients thought to have an inherited disorder, testing for vWD should be done initially because approximately 1% of the population has vWD. The complete vWD panel (factor VIII coagulant activity, vWf antigen, ristocetin cofactor activity) should be performed because many patients will have abnormalities of only one particular panel component. Patients diagnosed with vWD should be classified using multimeric analysis to identify the type 1 vWD patients likely to respond to DDAVP. If vWD studies are normal, platelet aggregation testing should be performed, ensuring that no antiplatelet medications have been ingested at least 1 week before testing. If platelet aggregation tests are normal and if suspicion for an inherited disorder remains high, vWD testing should be repeated. The evaluation of thrombocytopenia may require bone marrow examination to exclude primary hematologic disorders. If future studies with thrombopoietin assays

  17. Porcine E. coli: virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method.

    Science.gov (United States)

    Schierack, Peter; Rödiger, Stefan; Kuhl, Christoph; Hiemann, Rico; Roggenbuck, Dirk; Li, Ganwu; Weinreich, Jörg; Berger, Enrico; Nolan, Lisa K; Nicholson, Bryon; Römer, Antje; Frömmel, Ulrike; Wieler, Lothar H; Schröder, Christian

    2013-01-01

    We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars.

  18. Porcine E. coli: virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method.

    Directory of Open Access Journals (Sweden)

    Peter Schierack

    Full Text Available We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2 and their probiotic activity against infection by enteropathogenic E. coli (EPEC. 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars.

  19. Blood platelets in the progression of Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Nina S Gowert

    Full Text Available Alzheimer's disease (AD is characterized by neurotoxic amyloid-ß plaque formation in brain parenchyma and cerebral blood vessels known as cerebral amyloid angiopathy (CAA. Besides CAA, AD is strongly related to vascular diseases such as stroke and atherosclerosis. Cerebrovascular dysfunction occurs in AD patients leading to alterations in blood flow that might play an important role in AD pathology with neuronal loss and memory deficits. Platelets are the major players in hemostasis and thrombosis, but are also involved in neuroinflammatory diseases like AD. For many years, platelets were accepted as peripheral model to study the pathophysiology of AD because platelets display the enzymatic activities to generate amyloid-ß (Aß peptides. In addition, platelets are considered to be a biomarker for early diagnosis of AD. Effects of Aß peptides on platelets and the impact of platelets in the progression of AD remained, however, ill-defined. The present study explored the cellular mechanisms triggered by Aß in platelets. Treatment of platelets with Aß led to platelet activation and enhanced generation of reactive oxygen species (ROS and membrane scrambling, suggesting enhanced platelet apoptosis. More important, platelets modulate soluble Aß into fibrillar structures that were absorbed by apoptotic but not vital platelets. This together with enhanced platelet adhesion under flow ex vivo and in vivo and platelet accumulation at amyloid deposits of cerebral vessels of AD transgenic mice suggested that platelets are major contributors of CAA inducing platelet thrombus formation at vascular amyloid plaques leading to vessel occlusion critical for cerebrovascular events like stroke.

  20. [Murine models of platelet diseases].

    Science.gov (United States)

    Lanza, F

    2007-05-01

    Platelet-related diseases correspond to functional defects or abnormal production (thrombopoiesis) of hereditary and immunological origins. Recent progress in the manipulation of the mouse genome (transgenesis, gene inactivation or insertion) has resulted in the generation of numerous strains exhibiting defective platelet function or production. Some strains reproduce known hereditary diseases affecting haemostasis (Glanzmann thrombasthenia, Bernard-Soulier syndrome (BSS) or thrombopoiesis (Wiscott-Aldrich or May-Hegglin syndrome). More often the mutated strains have no human equivalent and represent useful models to study: (i) the role of adhesive or signalling receptors or of signalling proteins in platelet-dependent haemostasis and thrombosis or; (ii) to study the poorly characterized mechanisms of thrombopoiesis, which implicate transcription factors (GATA, Fli1), growth factors and receptors (TPO, cMPL), and cytoskeletal or contractile proteins (tubulin, myosin). Additional mouse strains result from the selection of spontaneous mutants many of which affect intracellular platelet granules, representing models of storage pool diseases (SPD) such as the Gray platelet syndrome (alphaSPD) or Hermansky-Pudlack syndrome (deltaSPD). More recently, a systematic chemical mutagenesis approach has also identified genes involved in thrombopoiesis and platelet survival. Finally, mouse models of auto- or allo-immune thrombocytopenia have been developed to study the mechanisms of platelet destruction or removal.

  1. Calpain Activator Dibucaine Induces Platelet Apoptosis

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2011-03-01

    Full Text Available Calcium-dependent calpains are a family of cysteine proteases that have been demonstrated to play key roles in both platelet glycoprotein Ibα shedding and platelet activation and altered calpain activity is associated with thrombotic thrombocytopenic purpura. Calpain activators induce apoptosis in several types of nucleated cells. However, it is not clear whether calpain activators induce platelet apoptosis. Here we show that the calpain activator dibucaine induced several platelet apoptotic events including depolarization of the mitochondrial inner transmembrane potential, up-regulation of Bax and Bak, down-regulation of Bcl-2 and Bcl-XL, caspase-3 activation and phosphatidylserine exposure. Platelet apoptosis elicited by dibucaine was not affected by the broad spectrum metalloproteinase inhibitor GM6001. Furthermore, dibucaine did not induce platelet activation as detected by P-selectin expression and PAC-1 binding. However, platelet aggregation induced by ristocetin or α-thrombin, platelet adhesion and spreading on von Willebrand factor were significantly inhibited in platelets treated with dibucaine. Taken together, these data indicate that dibucaine induces platelet apoptosis and platelet dysfunction.

  2. Inhibition of platelet aggregation by polyaspartoyl L-arginine and its mechanism

    Institute of Scientific and Technical Information of China (English)

    Yin-ye WANG; Zhi-yu TANG; Min DONG; Xiao-yan LIU; Shi-qi PENG

    2004-01-01

    AIM: To observe the oral anti-platelet efficacy and the potential action mechanism of polyaspartoyl L-arginine (PDR), a new L-arginine rich compound. METHODS: Platelet aggregation was conducted by Born's method;bleeding time was determined using tail's bleeding time in mice; platelet adhesion was carried out with glass bottle method; nitric oxide (NO) was tested with Griess' method; and cAMP, thromboxane B2 (TXB2) and 6-keto-PGF1a were assessed with commercial kits. RESULTS: The inhibition by PDR (15-60 mg/kg ig or 10 mg/kg iv) of platelet aggregation induced by adenosine diphosphate (ADP), collagen or thrombin at 1 h after oral administration or at 20 min after iv injection for rats (P<0.01), and its (15 mg/kg, ig) inhibition of ADP-induced platelet aggregation for rabbits during 6 h after administration were observed. PDR (15-60 mg/kg) prolonged the bleeding time of mice (P<0.05) and (30 mg/kg) increased NO concentration in plasma. On the other hand PDR did not change the contents of cAMP in platelet and TXB2 or 6-keto-PGF1a in plasma. CONCLUSION: PDR is a novel, oral effective platelet aggregation inhibitor and its action mechanism possibly related to increasing NO generation.

  3. The Toxicity of a Chemically Synthesized Peptide Derived from Non-Integrin Platelet Collagen Receptors

    Directory of Open Access Journals (Sweden)

    Thomas M. Chiang

    2008-01-01

    Full Text Available A chemically synthesized peptide derived from platelet non-integrin collagen receptor has been shown to be an effective agent for inhibiting collagen-induced platelet aggregation and adhesion of washed radiolabeled platelets onto natural matrices and collagen coated microtiter plates. In order to be a therapeutic agent, we have used a cell culturing system and an animal model to test its cytotoxicities. In cell culture experiments, the peptide is not toxic to MEG-01, a megakaryoblastic cell line. Prior to performing experiments in rats, the existence of both platelet type I and type III collagen receptors and its functional roles in rat platelets had to be established. In this investigation, we report that rat platelets contain both receptors and the cHyB peptide inhibits both type I and type III collagen-induced rat platelet aggregation. In addition, analysis of the rat sera collected at various time intervals following an injection of cHyB into the rat-tail vein, did not show an increase in the activity of key enzymes which indicate tissue and/or organ damage. These results suggest that the cHyB peptide is safe and its development into a potential therapeutic agent for inhibiting thrombi formation is possible.

  4. The Toxicity of a Chemically Synthesized Peptide Derived from Non-Integrin Platelet Collagen Receptors

    Directory of Open Access Journals (Sweden)

    Thomas M. Chiang

    2008-08-01

    Full Text Available A chemically synthesized peptide derived from platelet non-integrin collagen receptor has been shown to be an effective agent for inhibiting collagen-induced platelet aggregation and adhesion of washed radiolabeled platelets onto natural matrices and collagen coated microtiter plates. In order to be a therapeutic agent, we have used a cell culturing system and an animal model to test its cytotoxicities. In cell culture experiments, the peptide is not toxic to MEG-01, a megakaryoblastic cell line. Prior to performing experiments in rats, the existence of both platelet type I and type III collagen receptors and its functional roles in rat platelets had to be established. In this investigation, we report that rat platelets contain both receptors and the cHyB peptide inhibits both type I and type III collagen-induced rat platelet aggregation. In addition, analysis of the rat sera collected at various time intervals following an injection of cHyB into the rat-tail vein, did not show an increase in the activity of key enzymes which indicate tissue and/or organ damage. These results suggest that the cHyB peptide is safe and its development into a potential therapeutic agent for inhibiting thrombi formation is possible.

  5. Single-step separation of platelets from whole blood coupled with digital quantification by interfacial platelet cytometry (iPC).

    Science.gov (United States)

    Basabe-Desmonts, L; Ramstrom, S; Meade, G; O'Neill, S; Riaz, A; Lee, L P; Ricco, A J; Kenny, D

    2010-09-21

    We report the efficient single-step separation of individual platelets from unprocessed whole blood, enabling digital quantification of platelet function using interfacial platelet cytometry (iPC) on a chip. iPC is accomplished by the precision micropatterning of platelet-specific protein surfaces on solid substrates. By separating platelets from whole blood using specific binding to protein spots of a defined size, iPC implements a simple incubate-and-rinse approach, without sample preparation, that enables (1) the study of platelets in the physiological situation of interaction with a protein surface, (2) the choice of the number of platelets bound on each protein spot, from one to many, (3) control of the platelet-platelet distance, including the possibility to study noninteracting single platelets, (4) digital quantification (counting) of platelet adhesion to selected protein matrices, enabling statistical characterization of platelet subpopulations from meaningfully large numbers of single platelets, (5) the study of platelet receptor expression and spatial distribution, and (6) a detailed study of the morphology of isolated single platelets at activation levels that can be manipulated. To date, we have demonstrated 1-4 of the above list. Platelets were separated from whole blood using iPC with fibrinogen, von Willebrand factor (VWF), and anti-CD42b antibody printed "spots" ranging from a fraction of one to several platelet diameters (2-24 μm). The number of platelets captured per spot depends strongly on the protein matrix and the surface area of the spot, together with the platelet volume, morphology, and activation state. Blood samples from healthy donors, a May-Hegglin-anomaly patient, and a Glanzmann's Thrombasthenia patient were analyzed via iPC to confirm the specificity of the interaction between protein matrices and platelets. For example, the results indicate that platelets interact with fibrinogen spots only through the fibrinogen receptor (

  6. Shock adhesion test for composite bonded assembly using a high pulsed power generator

    Science.gov (United States)

    Gay, E.; Berthe, L.; Buzaud, E.; Boustie, M.; Arrigoni, M.

    2013-07-01

    In a context of the rising use of composite assemblies in aeronautic or defense fields, the assessment of their strength is a key issue. The method developed in this study attempts to provide solutions. A shock adhesion test based on short compressive loads, obtained by a high pulsed power generator, is proposed as a proof test to ensure the quality of composite bonded assemblies. A calibrated load induces a local tensile stress able to damage the bond interface. The high pulsed power source is the GEnerateur de Pression Isentropique device (Isentropic Pressure Generator), used to generate the required stresses, with a 450 ns pulse duration to test assemblies above the mm thickness range. The understanding of the mechanisms of wave propagation and tensile stress generation within these multilayer assemblies are scientific challenges. The ability of the technique to induce a tensile stress able to disbond the laminates and the assemblies is demonstrated. This paper details the response of carbon epoxy laminates and their bonded assemblies to a shock loading near the damage threshold.

  7. Individualized dual antiplatelet therapy based on platelet function testing in patients undergoing percutaneous coronary intervention: a meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Zhou, Yijiang; Wang, Yanwei; Wu, Yutao; Huang, Chaoyang; Yan, Hui; Zhu, Weiguo; Xu, Weiwei; Zhang, Li; Zhu, Jianhua

    2017-06-15

    High on-treatment platelet reactivity (HPR) represents a strong risk factor for thrombotic events after PCI. We aim to evaluate the efficacy and safety of individualizing intensified dual antiplatelet therapy (DAPT) in PCI-treated patients with HPR based on platelet function testing (PFT). Electronic databases were searched for randomized control trials that reported the clinical outcomes of using an intensified antiplatelet protocol with P2Y12 receptor inhibitor comparing with standard maintenance dose of clopidogrel on the basis of platelet function testing. Clinical endpoints were assessed. From 2005 to 2016, thirteen clinical studies comprising 7290 patients were included for analysis. Compared with standard antiplatelet therapy with clopidogrel, the intensified protocol based on platelet function testing was associated with a significant reduction in major adverse cardiovascular events (RR:0.55, 95% CI: 0.36-0.84, p = 0.005), cardiovascular death (RR:0.60, 95% CI: 0.38-0.96, p = 0.03), stent thrombosis (RR:0.58, 95% CI: 0.36-0.93, p = 0.02) and target vessel revascularization (RR:0.33, 95% CI: 0.14-0.76, p = 0.009). No significant difference was found in the rate of bleeding events between intensified and standard protocol. Compared with standard clopidogrel therapy, individualized intensified antiplatelet therapy on the basis of platelet reactivity testing reduces the incidence of cardiovascular events in patient undergoing PCI, without increasing the risk of bleeding.

  8. PREGNANCY WITH PLATELET FUNCTION DISORDER

    Directory of Open Access Journals (Sweden)

    Sheila K

    2014-01-01

    Full Text Available latelets play a vital role in haemostasis . Antenatal patients with platelet function disorders should be managed in tertiary care centres that are well equipped to tackle any obstetric haemorrhage that can ensue during labour and delivery . Primi gravida was admitted for safe confinement . She had been evaluated earlier for complaints of multiple episodes of mucosal bleeding . On evaluation she had nor mal platelet counts and coagulation factor assay was normal . Platelet aggregometry revealed mild disorder of platelet aggregation . She was planned for induction of labour after arranging enough blood and blood products . She got into active labour and was p ut on syntocinon augmentation . She had emergency Caesarean section for foetal distress . Oxytocics were given proactively . Intraoperatively platelet transfusions and tranexamic acid infusion were given . Complete haemostasis was achieved . She had an uneventf ul postoperative period . Patients with functional platelet disorders can be successfully managed with local application of antifibrinolytic agents like tranexamic acid , in case of minor bleeds . Platelet transfusions are very effective in tackling major ble eds , especially during surgeries and for obstetric indications . If a patient has the history of clinically significant bleeding suggestive of platelet dysfunction , appropriate platelet function tests should be obtained so that the risk of bleeding can be adequately assessed and therapy chosen more rationally . . In obstetric practice the response of such patients to platelet transfusions has been excellent

  9. Analysis on Adhesively-Bonded Joints of FRP-steel Composite Bridge under Combined Loading: Arcan Test Study and Numerical Modeling

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2016-01-01

    Full Text Available The research presented in this paper is an experimental study and numerical analysis on mechanical behavior of the adhesively-bonded joint between FRP sandwich bridge deck and steel girder. Generally, there are three typical stress states in the adhesively-bonded joint: shear stress, tensile stress, and combination of both. To realize these stress states in the adhesively-bonded joint during tests, a specific loading device is developed with the capacity of providing six different loading angles, which are 0°(pure tension, 18°, 36°, 54°, 72° and 90°(pure shear. Failure modes of adhesively-bonded joints are investigated. It indicates that, for the pure shear loading, the failure mode is the cohesive failure (near the interface between the adhesive layer and the steel support in the adhesive layer. For the pure tensile and combined loading conditions, the failure mode is the combination of fiber breaking, FRP delamination and interfacial adhesion failure between the FRP sandwich deck and the adhesive layer. The load-bearing capacities of adhesive joints under combined loading are much lower than those of the pure tensile and pure shear loading conditions. According to the test results of six angle loading conditions, a tensile/shear failure criterion of the adhesively-bonded joint is obtained. By using Finite Element (FE modeling method, linear elastic simulations are performed to characterize the stress distribution throughout the adhesively-bonded joint.

  10. In vitro microtensile bond strength of four adhesives tested at the gingival and pulpal walls of class II restorations

    Science.gov (United States)

    Purk, John H.; Healy, Matthew; Dusevich, Vladimir; Glaros, Alan; Eick, J. David

    2007-01-01

    Background The authors compared the microtensile bond strength of teeth restored with four adhesives at the gingival and pulpal cavity walls of Class II resin-based composite restorations. Methods Five pairs of extracted third molars received two Class II preparations/restorations in each tooth. The authors randomly assigned each preparation to one of four adhesive groups: Adper Scotchbond Multipurpose Dental Adhesive (SBMP) (3M ESPE, St. Paul, Minn.), Clearfil SE Bond (CFSE) (Kuraray America, New York City), Prime & Bond NT (PBNT) (Dentsply Caulk, Milford, Del.) and PQ1 (Ultradent, South Jordan, Utah). They restored the teeth and obtained microtensile specimens from each cavity wall. Specimens were tested on a testing machine until they failed. Results The mean (± standard deviation) bond strengths (in megapascals) were as follows: SBMP (pulpal), 36.4 (17.2); SBMP (gingival), 29.7 (15.3); CFSE (pulpal), 50.8 (13.6); CFSE (gingival), 50.2 (14.0); PBNT (pulpal), 38.3 (19.2); PBNT (gingival), 38.9 (17.7); PQ1 (pulpal), 58.7 (8.7); and PQ1 (gingival), 54.5 (18.5). A two-way analysis of variance found an adhesive effect (P .05). Conclusions PQ1 and CFSE performed the best. The results showed no significant difference in microtensile bond strength at the gingival wall versus the pulpal wall. Clinical Implications Under in vitro conditions, a total-etch ethanol-based adhesive (PQ1) failed cohesively more often than did the other adhesives tested. PMID:17012721

  11. Evaluation of interface adhesion of hot-dipped zinc coating on TRIP steel with tensile testing and finite element calculation

    NARCIS (Netherlands)

    Song, G.M.; De Hosson, J.T.M.; Sloof, W.G.; Pei, Y.T.

    In this work, a methodology for the determination of the interface adhesion strength of zinc coating on TRIP steel is present. This method consists of a conventional tensile test in combination with finite element calculation. The relation between the average interface crack length and the applied

  12. Foam Core Particleboards with Intumescent FRT Veneer: Cone Calorimeter Testing With Varying Adhesives, Surface Layer Thicknesses, and Processing Conditions

    Science.gov (United States)

    Mark A. Dietenberger; Johannes Welling; Ali Shalbafan

    2014-01-01

    Intumescent FRT Veneers adhered to the surface of foam core particleboard to provide adequate fire protection were evaluated by means of cone calorimeter tests (ASTM E1354). The foam core particleboards were prepared with variations in surface layer treatment, adhesives, surface layer thicknesses, and processing conditions. Ignitability, heat release rate profile, peak...

  13. Platelets alter gene expression profile in human brain endothelial cells in an in vitro model of cerebral malaria.

    Directory of Open Access Journals (Sweden)

    Mathieu Barbier

    Full Text Available Platelet adhesion to the brain microvasculature has been associated with cerebral malaria (CM in humans, suggesting that platelets play a role in the pathogenesis of this syndrome. In vitro co-cultures have shown that platelets can act as a bridge between Plasmodium falciparum-infected red blood cells (pRBC and human brain microvascular endothelial cells (HBEC and potentiate HBEC apoptosis. Using cDNA microarray technology, we analyzed transcriptional changes of HBEC in response to platelets in the presence or the absence of tumor necrosis factor (TNF and pRBC, which have been reported to alter gene expression in endothelial cells. Using a rigorous statistical approach with multiple test corrections, we showed a significant effect of platelets on gene expression in HBEC. We also detected a strong effect of TNF, whereas there was no transcriptional change induced specifically by pRBC. Nevertheless, a global ANOVA and a two-way ANOVA suggested that pRBC acted in interaction with platelets and TNF to alter gene expression in HBEC. The expression of selected genes was validated by RT-qPCR. The analysis of gene functional annotation indicated that platelets induce the expression of genes involved in inflammation and apoptosis, such as genes involved in chemokine-, TREM1-, cytokine-, IL10-, TGFβ-, death-receptor-, and apoptosis-signaling. Overall, our results support the hypothesis that platelets play a pathogenic role in CM.

  14. Tribological Testing of Anti-Adhesive coatings for Cold Rolling Mill Rolls—Application to TiN-Coated Rolls

    Science.gov (United States)

    Ould, Choumad; Gachon, Yves; Montmitonnet, Pierre; Badiche, Xavier

    2011-05-01

    Roll life is a major issue in cold strip rolling. Roll wear may result either in too low roll roughness, bringing friction below the minimum requested for strip entrainment; or it may degrade strip surface quality. On the contrary, adhesive wear and transfer ("roll coating", "pick up") may form a thick metallic deposits on the roll which increases friction excessively and degrades strip surface again [1]. The roll surface, with the help of a materials-adapted lubricant, must therefore possess anti-wear and anti-adhesive properties. Thus, High Speed Steeel (HSS) rolls show superior properties compared with standard Cr-steel rolls due to their high carbide surface coverage. Another way to improve wear and adhesion properties of surfaces is to apply hard metallic (hard-Cr) or ceramic coatings. Chromium is renowned for its excellent anti-wear and anti-adhesive properties and may serve as a reference. Here, as a first step towards alternative, optimised coatings, a PVD TiN coating has been deposited on tool steels, as previous attempts have proved TiN to be rather successful in cold rolling experiments [2,3]. Different tribological tests are reported here, giving insight in both anti-adhesive properties and fatigue life improvement.

  15. Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis.

    Science.gov (United States)

    Koupenova, Milka; Vitseva, Olga; MacKay, Christopher R; Beaulieu, Lea M; Benjamin, Emelia J; Mick, Eric; Kurt-Jones, Evelyn A; Ravid, Katya; Freedman, Jane E

    2014-07-31

    Viral infections have been associated with reduced platelet counts, the biological significance of which has remained elusive. Here, we show that infection with encephalomyocarditis virus (EMCV) rapidly reduces platelet count, and this response is attributed to platelet Toll-like receptor 7 (TLR7). Platelet-TLR7 stimulation mediates formation of large platelet-neutrophil aggregates, both in mouse and human blood. Intriguingly, this process results in internalization of platelet CD41-fragments by neutrophils, as assessed biochemically and visualized by microscopy, with no influence on platelet prothrombotic properties. The mechanism includes TLR7-mediated platelet granule release, translocation of P-selectin to the cell surface, and a consequent increase in platelet-neutrophil adhesion. Viral infection of platelet-depleted mice also led to increased mortality. Transfusion of wild-type, TLR7-expressing platelets into TLR7-deficient mice caused a drop in platelet count and increased survival post EMCV infection. Thus, this study identifies a new link between platelets and their response to single-stranded RNA viruses that involves activation of TLR7. Finally, platelet-TLR7 stimulation is independent of thrombosis and has implications to the host immune response and survival.

  16. Acquired platelet function defect

    Science.gov (United States)

    Acquired qualitative platelet disorders; Acquired disorders of platelet function ... blood clotting. Disorders that can cause problems in platelet function include: Idiopathic thrombocytopenic purpura Chronic myelogenous leukemia Multiple ...

  17. Platelet Donation

    Science.gov (United States)

    ... of gratitude that washed over me when I saw those platelets going into my husband’s body. I ... Needles LGBTQ+ Donors Blood Donor Community SleevesUp Games Facebook Avatars and Badges Banners eCards Red Cross Information ...

  18. Understanding platelet function through signal transduction.

    Science.gov (United States)

    Lazarus, Alan H; Song, Seng; Crow, Andrew R

    2003-01-01

    Platelets are activated by a number of stimuli resulting in the expression and/or activation of surface receptors, secretion of vasoactive substances, adhesion, aggregation, and finally thrombus formation. These events are propagated by a process known as transmembrane signaling, which relays the activating signal from the platelet membrane (eg, von Willebrand Factor binding to glycoprotein Ib) to the inside of the platelet which then serves to activate the platelet via a cascade of biochemical interactions. Inhibition of these transmembrane signaling molecules with a variety of available inhibitors or antagonists can in many cases prevent the platelet from becoming activated. An awareness of the mechanisms involved in platelet transmembrane signaling and the recent availability of new reagents to inhibit signaling may provide us with additional means to prevent platelet activation and perhaps even ameliorate the platelet storage lesion. This review will provide an introduction to the field of platelet transmembrane signaling and give an overview of some of the platelet signaling mechanisms that are relevant to transfusion medicine. Copyright 2003, Elsevier Science (USA). All rights reserved.

  19. Clopidogrel Resistance by P2Y12 Platelet Function Testing in Patients Undergoing Neuroendovascular Procedures: Incidence of Ischemic and Hemorrhagic Complications.

    Science.gov (United States)

    Nordeen, Jerah D; Patel, Alden V; Darracott, Robert M; Johns, Gretchen S; Taussky, Philipp; Tawk, Rabih G; Miller, David A; Freeman, William D; Hanel, Ricardo A

    2013-06-01

    The purpose of the study was to assess clopidogrel resistance and whether "intensified" antiplatelet therapy guided by platelet inhibition tests during neuroendovascular procedures would reduce ischemic complications. We conducted a retrospective review of patients at Mayo Clinic in Jacksonville, Florida, who underwent neuroendovascular (NV) procedures and had P2Y12 platelet function testing from October 1, 2009, to September 30, 2010. The primary end-point was to determine P2Y12 resistance to antiplatelet therapy in patients who underwent NV procedures. Secondary objectives included incidence of hemorrhagic and ischemic events and a correlation between resistance and genetic CYP2C19 testing. 160 patients underwent P2Y12 platelet function tests. Eighty-one patients (81/160, 50.6%) met inclusion criteria. Platelet function tests identified 64 patients (79%) as non-resistant (≥20% P2Y12 inhibition) and 17 (21%) as resistant (Pharmaceuticals, Princeton, NJ, USA) VerifyNow® (Accumetrics Inc., San Diego, CA, USA) Ticlopidine (Ticlid®) (Roche Laboratories, Basel, Switzerland) Prasugrel (Effient®) (Eli Lilly & Co., Indianapolis, IN, USA) Eptifibatide (Integrilin®) (Merck & Co., Inc., Whitehouse Station, NJ, USA) Abciximab (Reopro®) (Janssen Pharmaceuticals, Inc., Titusville, NJ, USA) Tirofiban (Aggrastat®) (MGI Pharma, Inc., Bloomington, MN, USA) Pantoprazole (Protonix®) (Pfizer Inc., New York, NY, USA) Omeprazole (Prilosec®) (Procter and Gamble Pharmaceuticals, Mason, OH, USA) Famotidine (Pepcid®) (McNeil Consumer & Specialty Pharmaceuticals, Fort Washington, PA, USA) Ticagrelor (Brilinta®) (AstraZeneca Pharmaceuticals, Wilmington, NC, USA).

  20. Thrombin Increases Expression of Fibronectin Antigen on the Platelet Surface

    Science.gov (United States)

    Ginsberg, Mark H.; Painter, Richard G.; Forsyth, Jane; Birdwell, Charles; Plow, Edward F.

    1980-02-01

    Fibronectins (fn) are adhesive glycoproteins which bind to collagen and to fibrin and appear to be important in cellular adhesion to other cells or surfaces. Fn-related antigen is present in human platelets, suggesting a possible role for fn in the adhesive properties of platelets. We have studied the localization of fn in resting and thrombin-stimulated platelets by immunofluorescence and quantitative binding of radiolabeled antibody. In resting fixed platelets, variable light surface staining for fn was observed. When these cells were made permeable to antibody with detergent, staining for fn was markedly enhanced and was present in a punctate distribution, suggesting intracellular localization. Stimulation with thrombin, which is associated with increased platelet adhesiveness, resulted in increased staining for fn antigen on intact platelets. These stimulated cells did not leak 51Cr nor did they stain for F-actin, thus documenting that the increased fn staining was not due to loss of plasma membrane integrity. The thrombin-induced increase in accessible platelet fn antigen was confirmed by quantitative antibody binding studies in which thrombin-stimulated platelets specifically bound 15 times as much radiolabeled F(ab')2 anti-fn as did resting cells. Thus, thrombin stimulation results in increased expression of fn antigen on the platelet surface. Here it may participate in interactions with fibrin, connective tissue, or other cells.

  1. Roll, adhere, spread and contract: structural mechanics of platelet function.

    Science.gov (United States)

    Sorrentino, Simona; Studt, Jan-Dirk; Medalia, Ohad; Tanuj Sapra, K

    2015-01-01

    Platelets are involved in life-sustaining processes such as hemostasis, wound healing, atherothrombosis and angiogenesis. Mechanical trauma to blood vessels causes platelet activation resulting in their adherence and clot formation at the damaged site, culminating in clot retraction and tissue repair. Two of the major players underlying this process are the cytoskeleton, i.e., actin and microtubules, and the membrane integrin receptors. Rare congenital bleeding disorders such as Glanzmann thrombasthenia and Bernard-Soulier syndrome are associated with genetic alterations of platelet surface receptors, also affecting the platelet cytoskeletal structure. In this review, we summarize the current knowledge about platelet structure and adhesion, and delve into the mechanical aspects of platelet function. Platelets lack a nucleus, and can thus provide a minimal model of a biological cell. New biophysical tools may help to scrutinize platelets anew and to extend the existing knowledge on cell biology.

  2. The Role of Platelets in Cardiovascular Disease: Molecular Mechanisms.

    Science.gov (United States)

    Papapanagiotou, Angeliki; Daskalakis, Georgios; Siasos, Gerasimos; Gargalionis, Antonios; Papavassiliou, Athanasios G

    2016-01-01

    The role of platelets in atherosclerotic process and subsequently in the pathophysiology of cardiovascular disease is essential as platelets in addition to their contribution to thrombosis and hemostasis modulating inflammatory reactions and immune response. Platelets after adhesion on the injured vascular endothelium and activation release a wide range of molecules stored in platelets granules such as chemokines, proinflammatory molecules and other biological response modulators accelerating interaction among platelets, endothelial cells and leukocytes. These interactions establish a localized inflammatory response that promotes the atherosclerotic process. Moreover, activated platelets give rise to microparticles another active participant within the blood stream. The purpose of this review is to present the role of platelets in the above mechanisms giving an emphasis on the nature of the platelet derived- molecules and their contribution to the atherosclerotic process.

  3. Platelet dynamics in three-dimensional simulation of whole blood.

    Science.gov (United States)

    Vahidkhah, Koohyar; Diamond, Scott L; Bagchi, Prosenjit

    2014-06-03

    A high-fidelity computational model using a 3D immersed boundary method is used to study platelet dynamics in whole blood. We focus on the 3D effects of the platelet-red blood cell (RBC) interaction on platelet margination and near-wall dynamics in a shear flow. We find that the RBC distribution in whole blood becomes naturally anisotropic and creates local clusters and cavities. A platelet can enter a cavity and use it as an express lane for a fast margination toward the wall. Once near the wall, the 3D nature of the platelet-RBC interaction results in a significant platelet movement in the transverse (vorticity) direction and leads to anisotropic platelet diffusion within the RBC-depleted zone or cell-free layer (CFL). We find that the anisotropy in platelet motion further leads to the formation of platelet clusters, even in the absence of any platelet-platelet adhesion. The transverse motion, and the size and number of the platelet clusters are observed to increase with decreasing CFL thickness. The 3D nature of the platelet-RBC collision also induces fluctuations in off-shear plane orientation and, hence, a rotational diffusion of the platelets. Although most marginated platelets are observed to tumble just outside the RBC-rich zone, platelets further inside the CFL are observed to flow with an intermittent dynamics that alters between sliding and tumbling, as a result of the off-shear plane rotational diffusion, bringing them even closer to the wall. To our knowledge, these new findings are based on the fundamentally 3D nature of the platelet-RBC interaction, and they underscore the importance of using cellular-scale 3D models of whole blood to understand platelet margination and near-wall platelet dynamics.

  4. Smooth muscle hyperplasia due to loss of smooth muscle α-actin is driven by activation of focal adhesion kinase, altered p53 localization and increased levels of platelet-derived growth factor receptor-β.

    Science.gov (United States)

    Papke, Christina L; Cao, Jiumei; Kwartler, Callie S; Villamizar, Carlos; Byanova, Katerina L; Lim, Soon-Mi; Sreenivasappa, Harini; Fischer, Grant; Pham, John; Rees, Meredith; Wang, Miranda; Chaponnier, Christine; Gabbiani, Giulio; Khakoo, Aarif Y; Chandra, Joya; Trache, Andreea; Zimmer, Warren; Milewicz, Dianna M

    2013-08-01

    Mutations in ACTA2, encoding the smooth muscle cell (SMC)-specific isoform of α-actin (α-SMA), cause thoracic aortic aneurysms and dissections and occlusive vascular diseases, including early onset coronary artery disease and stroke. We have shown that occlusive arterial lesions in patients with heterozygous ACTA2 missense mutations show increased numbers of medial or neointimal SMCs. The contribution of SMC hyperplasia to these vascular diseases and the pathways responsible for linking disruption of α-SMA filaments to hyperplasia are unknown. Here, we show that the loss of Acta2 in mice recapitulates the SMC hyperplasia observed in ACTA2 mutant SMCs and determine the cellular pathways responsible for SMC hyperplasia. Acta2(-/-) mice showed increased neointimal formation following vascular injury in vivo, and SMCs explanted from these mice demonstrated increased proliferation and migration. Loss of α-SMA induced hyperplasia through focal adhesion (FA) rearrangement, FA kinase activation, re-localization of p53 from the nucleus to the cytoplasm and increased expression and ligand-independent activation of platelet-derived growth factor receptor beta (Pdgfr-β). Disruption of α-SMA in wild-type SMCs also induced similar cellular changes. Imatinib mesylate inhibited Pdgfr-β activation and Acta2(-/-) SMC proliferation in vitro and neointimal formation with vascular injury in vivo. Loss of α-SMA leads to SMC hyperplasia in vivo and in vitro through a mechanism involving FAK, p53 and Pdgfr-β, supporting the hypothesis that SMC hyperplasia contributes to occlusive lesions in patients with ACTA2 missense mutations.

  5. Fabricating bio-inspired micro/nano-particles by polydopamine coating and surface interactions with blood platelets

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Wei [Jiangsu Provincial Key Lab for Interventional Medical Devices, Huaiyin Institute of Technology, Huaian 223003 (China); State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Shi, Qiang, E-mail: shiqiang@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Hou, Jianwen; Gao, Jian; Li, Chunming; Jin, Jing; Shi, Hengchong [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Yin, Jinghua, E-mail: yinjh@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2015-10-01

    Graphical abstract: The particles or particle aggregations activate the blood platelets and provide the physical adhesive sites for platelets adhesion. - Highlights: • Particles with varied sizes and surface properties were fabricated by facile polydopamine (PDA) coating on polystyrene microsphere. • The direct interaction between PDA particles and blood platelets was qualitatively investigated. • The knowledge on platelet–particle interactions provided the basic principle to select biocompatible micro/nano-particles in biomedical field. - Abstract: Although bio-inspired polydopamine (PDA) micro/nano-particles show great promise for biomedical applications, the knowledge on the interactions between micro/nano-particles and platelets is still lacking. Here, we fabricate PDA-coated micro/nano-particles and investigate the platelet–particle surface interactions. Our strategy takes the advantage of facile PDA coating on polystyrene (PS) microsphere to fabricate particles with varied sizes and surface properties, and the chemical reactivity of PDA layers to immobilize fibrinogen and bovine serum albumin to manipulate platelet activation and adhesion. We demonstrate that PS particles activate the platelets in the size-dependent manner, but PDA nanoparticles have slight effect on platelet activation; PS particles promote platelet adhesion while PDA particles reduce platelet adhesion on the patterned surface; Particles interact with platelets through activating the glycoprotein integrin receptor of platelets and providing physical sites for initial platelet adhesion. Our work sheds new light on the interaction between platelets and particles, which provides the basic principle to select biocompatible micro/nano-particles in biomedical field.

  6. [Glycoproteins, inherited diseases of platelets, and the role of platelets in wound healing].

    Science.gov (United States)

    Nurden, Alan T; Nurden, Paquita

    2013-02-01

    Recognition that platelets have a glycocalyx rich in membrane glycoproteins prompted the discovery in France that inherited bleeding syndromes due to defects of platelet adhesion and aggregation were caused by deficiencies in major receptors at the platelet surface. Identification of the alpha IIb beta3 integrin prompted the development of powerful anti-thrombotic drugs that have gained worldwide use. Since these discoveries, the genetic causes of many other defects of platelet function and production have been elucidated, with the identification of an ADP receptor, P2 Y12, another widespread target for anti-thrombotic drugs. Discovery of the molecular basis of a rare disease of storage of biologically active proteins in platelet alpha-granules has been accompanied by the recognition of the roles of platelets in inflammation, the innate immune system and tissue repair, opening new avenues for therapeutic advances.

  7. Fabrication, testing and analysis of steel/composite DLS adhesive joints

    DEFF Research Database (Denmark)

    Hashim, S.; Berggreen, Christian; Tsouvalis, N.;

    2011-01-01

    This paper describes experimental and numerical techniques to study the structural design of double lap shear joints that are based on thick-adherend steel/steel and steel/composite, with epoxy adhesive. A standard practical fabrication method was used to produce specimens of various dimensions...... the importance of modelling the composite layers adjacent to the adhesive bondline in order to account for the critical local stresses. The FEA results also showed that overall shear stress distributions can be used to characterise joint failure. The paper presents the experimental and numerical details with key...

  8. Platelet aggregation and quality control of platelet concentrates produced in the Amazon Blood Bank

    Directory of Open Access Journals (Sweden)

    Maria José Dantas Coêlho

    2011-01-01

    Full Text Available BACKGROUND: The study of platelet aggregation is essential to assess in vitro platelet function by different platelet activation pathways. OBJECTIVE: To assess aggregation and biochemical parameters of random platelet concentrates produced at the Fundação HEMOAM using the quality control tests defined by law. METHODS: Whole blood samples from 80 donors and the respective platelet concentrate units were tested. Platelet concentrates were tested (platelet count, aggregation and pH on days 1, 3 and 5 of storage. Additionally a leukocyte count was done only on day 1 and microbiological tests on day 5 of storage. Collagen and adenosine diphosphate were used as inducing agonists for platelet aggregation testing. RESULTS: Donor whole blood had normal aggregation (aggregation with adenosine diphosphate = 67% and with collagen = 78%. The median aggregation in platelet concentrates with adenosine diphosphate was low throughout storage (18% on day 1, 7% on day 3 and 6% on day 5 and the median aggregation with collagen was normal only on day 1 and low thereafter (54.4% on day 1, 20.5% on day 3 and 9% on day 5. CONCLUSION: Although the results were within the norms required by law, platelet concentrates had low aggregation rates. We suggest the inclusion of a functional assessment test for the quality control of platelet concentrates for a more effective response to platelet replacement therapy.

  9. Adhesive bond testing of carbon-epoxy composites by laser shockwave

    NARCIS (Netherlands)

    Perton, Mathieu; Blouin, Alain; Monchalin, Jean-Pierre

    2011-01-01

    Adhesive bonding, particularly of composite laminates, presents many practical advantages when compared with other joining methods but its use is limited, since there is presently no non-destructive inspection technique to ensure the quality of the bond. We are developing a technique based on the

  10. Function of eltrombopag-induced platelets compared to platelets from control patients with immune thrombocytopenia.

    Science.gov (United States)

    Haselboeck, Johanna; Kaider, Alexandra; Pabinger, Ingrid; Panzer, Simon

    2013-04-01

    Data on the in vivo function of platelets induced by the thrombopoietin receptor agonist eltrombopag are scarce. To assess a possible influence of eltrombopag we compared platelet function of eltrombopag-treated immune thrombocytopenia (ITP) patients (group 1; n=10) after treatment response to that from control ITP patients (group 2; n=12). We further analysed platelet function at baseline and after one, three, and four weeks of eltrombopag treatment and estimated daily changes of platelet function during the eltrombopag-induced platelet rise. The formation of platelet-monocyte aggregates (PMA), P-selectin expression [MFI], and platelet adhesion under high shear conditions (surface coverage, SC) in vivo and after in vitro addition of agonists (ADP, TRAP-6, Collagen) were similar between both groups after response to eltrombopag treatment. Only TRAP-6 induced a lower SC in the eltrombopag group (p=0.03). All platelet function parameters except for Collagen-induced P-selectin expression changed significantly during treatment with eltrombopag. PMA, naïve and after addition of ADP or TRAP-6 increased with increasing platelet counts. P-selectin expression decreased, when measured without and upon addition of ADP, increased in the presence of TRAP-6, and remained unchanged after addition of Collagen. SC increased during the eltrombopag-induced platelet rise. All significant changes of platelet function correlated to changes in platelet counts. Two patients developed venous thromboses during eltrombopag treatment, but no association with any distinct single platelet function parameter or combinations thereof was identifiable. Thus, eltrombopag-induced platelets function similar to those from control ITP patients without discernible increased hyper-reactivity.

  11. Plasma functionalization of titanium surface for repulsion of blood platelets

    OpenAIRE

    Cvelbar, Uros; Modic, Martina; Kovac, J.; Lazovic, S; Filipic, G; Vujosevic, D; Junkar, Ita; Elersic, Kristina; Brühl, S.P.; Canal Barnils, Cristina; Belmonte, Thierry; Mozetic, Miran

    2012-01-01

    Thrombosis and restenosis are the most common problems during insertion of biocompatible implants like titanium stents into human blood, due to aggregation of platelets on their surfaces. Because of this reason, we studied the response of blood platelets to a plasma treated titanium surface. The aim was to design a functionalized surface which would repel blood platelets or prevent their adhesion. Therefore, we functionalized surfaces with low-temperature inductively coupled oxygen plasma tre...

  12. Platelet membrane glycoproteins and their function: an overview.

    Science.gov (United States)

    Kunicki, T J

    1989-07-01

    The membrane glycoproteins (GP) of human platelets act as receptors that mediate two important functions, adhesion to the subendothelial matrix and platelet-platelet cohesion, or aggregation. Many of these glycoprotein receptors exist as noncovalently linked heterodimers, including those that belong to the supergene family of adhesion receptors called the integrins. Human platelets contain at least five members of this integrin family, including a collagen receptor (GP Ia-IIa; alpha 2, beta 1), a fibronectin receptor (GP Ic-IIa; alpha 5, beta 1), a laminin receptor (GP Ic'-IIa; alpha 6, beta 1), a vitronectin receptor (VnR; alpha v, beta 3), and a promiscuous, activation-dependent receptor that is thought to be the receptor most responsible for fibrinogen-dependent, platelet-platelet cohesion (GP IIb-IIIa; alpha IIb, beta 3). Some, but not all, of the integrins bind to a tripeptide sequence, arginine-glycine-aspartic acid (RGD), on the adhesive proteins. In addition to the integrins, platelets contain other membrane glyco-proteins: GP Ib-IX, a receptor for von Willebrand factor, which is thought to be the receptor most responsible for platelet adhesion to the subendothelial matrix in a flowing system; GP V, which may be associated with GP Ib-IX and whose function remains unknown; and GP IV (GP IIIb), which functions as a receptor for thrombospondin and collagen.

  13. Platelets Inhibit Migration of Canine Osteosarcoma Cells.

    Science.gov (United States)

    Bulla, S C; Badial, P R; Silva, R C; Lunsford, K; Bulla, C

    2017-01-01

    The interaction between platelets and tumour cells is important for tumour growth and metastasis. Thrombocytopenia or antiplatelet treatment negatively impact on cancer metastasis, demonstrating potentially important roles for platelets in tumour progression. To our knowledge, there is no information regarding the role of platelets in cancer progression in dogs. This study was designed to test whether canine platelets affected the migratory behaviour of three canine osteosarcoma cell lines and to give insights of molecular mechanisms. Intact platelets, platelet lysate and platelet releasate inhibited the migration of canine osteosarcoma cell lines. Addition of blood leucocytes to the platelet samples did not alter the inhibitory effect on migration. Platelet treatment also significantly downregulated the transcriptional levels of SNAI2 and TWIST1 genes. The interaction between canine platelets or molecules released during platelet activation and these tumour cell lines inhibits their migration, which suggests that canine platelets might antagonize metastasis of canine osteosarcoma. This effect is probably due to, at least in part, downregulation of genes related to epithelial-mesenchymal transition. Copyright © 2016. Published by Elsevier Ltd.

  14. 比浊法血小板聚集试验的影响因素研究%Analysis of influencing factors of turbidimetry for platelet agglutination test

    Institute of Scientific and Technical Information of China (English)

    石红婷; 周伯荣; 王融; 邓燕华; 关海涛; 刘子凡

    2012-01-01

    目的 在不同的实验条件下,观察影响比浊法血小板聚集试验的因素.方法 选择30例健康对照组和204例病例组,观察不同的血小板计数及诱导剂浓度对糖尿病患者餐前与餐后、采血后的检测时间、诱导剂的种类互补等不同试验条件下的血小板聚集率.结果 随着血小板计数的减少或增加,血小板聚集率相应的减少或增加;二磷酸腺苷(ADP)、胶原(COL)、花生四烯酸(AA)浓度增加,血小板最大聚集率增大,相应的阿司匹林抵抗(AR)或氯吡格雷抵抗(CR)的检出率增高;服用不同的抗血小板药物,糖尿病患者对以ADP、COL、AA为诱导剂测定的血小板聚集率,其影响不同;未空腹及检测时间超过3 h重复性较差;服药2周后,COL、AA诱导的血小板聚集率下降不明的患者,随着时间的延长,6个月后易重新出现CR.结论 血小板计数、诱导剂浓度、糖尿病疾病、空腹状态、检测时间与比浊法检测血小板聚集率相关,以ADP、COL、AA作诱导剂检测血小板聚集率较单一的ADP更全面、准确.%Objective To investigate the influencing factors of turbidimetry for platelet agglutination test under different experi -mental conditions .Methods 30 cases of healthy subjects and 204 cases of patents were enrolled . The rate of platelet aggregation (RPA ) was detected under different conditions , including platelet counts ,inducer concentration and types , diabetes mellitus (DM ), fasting state and detection time .Results With the increase or decrease of platelet counts , RPA varied correspondingly . With the increase of the concentration of adenosine diphosphate(ADP), collagen (COL) and arachidonic acid(AA), the maxim RPA and the detection rate of aspirin resistance (AR) or clopidogre resistance(CR) increased . For patients with DM , taking different antiplatelet drugs (aspirin or clopidogrel), inducers of ADP, COL and AA were with different influence on RPA . None-fasting and

  15. Comparison of fluoride release protocols for in-vitro testing of 3 orthodontic adhesives.

    Science.gov (United States)

    Wheeler, Arthur W; Foley, Timothy F; Mamandras, Antonios

    2002-03-01

    The objective of this study was to compare the fluoride release of 3 orthodontic adhesives using disks and bracketed teeth with different storage protocols. The adhesives used were a resin-modified glass ionomer (RMGI) (Fuji Ortho LC; GC America, Aslip, Ill), a polyacid-modified composite resin (PMCR)(Assure; Reliance Orthodontic Products, Itasca, Ill), and a composite control, Transbond XT (3M Unitek, Monrovia, Calif). Metal brackets were bonded to the buccal and lingual surfaces of 120 extracted human premolars. Five plastic containers holding 4 teeth (8 brackets) were used for each adhesive protocol. The samples were stored in containers holding 4 mL of deionized water at 37 degrees C for 28 and 84 days for the brackets and disks, respectively. The bracketed samples released larger initial amounts of fluoride compared with the disk samples during the first 5 to 6 days for both fluoride-releasing adhesives. The PMCR (Assure) released more fluoride (mg/cm(2)/day) than did the RMGI (Fuji Ortho LC) in all protocols with the exception of daily protocols when values diminished below the RMGI values near the 24th day and between the 56th and the 70th days for the bracketed and disk samples, respectively. Inconsistent values for fluoride release were noted in the bracket and disk samples when compared with daily versus cumulative water changes. Daily water changes revealed higher fluoride release levels (brackets), but this trend was not evident in the disk samples. Daily water changes may yield more clinically relevant data on fluoride release.

  16. Evaluation of the Wedge Cleavage Test for Assessment of Durability of Adhesive Bonded Joints.

    Science.gov (United States)

    1980-07-01

    applied to the adherends. Exposures of hundreds or thousands of hours are necessary to discriminate between pretreatments if conventional lap shear or peel ...was preceded by additional degreasing in a conventional non- caustic proprietary alkaline cleaning solution. Pickling was for 30 minutes at 62-65°C in...consistent with the lower peel strength given by anodised surfaces5 (c) Adhesive FMIOOO Crack lengths are shown in Table 3 and Fig 5. Fracture energies were

  17. Poly(acrylic acid) grafted montmorillonite as novel fillers for dental adhesives: synthesis, characterization and properties of the adhesive.

    Science.gov (United States)

    Solhi, Laleh; Atai, Mohammad; Nodehi, Azizollah; Imani, Mohammad; Ghaemi, Azadeh; Khosravi, Kazem

    2012-04-01

    This work investigates the graft polymerization of acrylic acid onto nanoclay platelets to be utilized as reinforcing fillers in an experimental dental adhesive. Physical and mechanical properties of the adhesive and its shear bond strength to dentin are studied. The effect of the modification on the stability of the nanoparticle dispersion in the dilute adhesive is also investigated. Poly(acrylic acid) (PAA) was grafted onto the pristine Na-MMT nanoclay (Cloisite(®) Na(+)) through the free radical polymerization of acylic acid in an aqueous media. The resulting PAA-g-nanoclay was characterized using FTIR, TGA and X-ray diffraction (XRD). The modified nanoclays were added to an experimental dental adhesive in different concentrations and the morphology of the nanoclay layers in the photocured adhesive matrix was studied using TEM and XRD. Shear bond strength of the adhesives containing different filler contents was tested on the human premolar teeth. The stability of nanoclay dispersion in the dilute adhesive was also studied using a separation analyzer. The results were then statistically analyzed and compared. The results confirmed the grafting reaction and revealed a partially exfoliated structure for the PAA-g-nanoclay. Incorporation of 0.2 wt.% of the modified nanoclay into the experimental adhesive provided higher shear bond strength. The dispersion stability of the modified nanoparticles in the dilute adhesive was also enhanced more than 25 times. Incorporation of the modified particles as reinforcing fillers into the adhesive resulted in higher mechanical properties. The nanofiller containing bonding agent also showed higher shear bond strength due to the probable interaction of the carboxylic acid functional groups on the surface of the modified particles with hydroxyapatite of dentin. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  18. Pneumococcal association to platelets is mediated by soluble fibrin and supported by thrombospondin-1.

    Science.gov (United States)

    Niemann, Silke; Kehrel, Beate E; Heilmann, Christine; Rennemeier, Claudia; Peters, Georg; Hammerschmidt, Sven

    2009-10-01

    Platelets and coagulation are involved in bacterial colonisation of the host. Streptocococcus pneumoniae (pneumococcus) are important etiologic agents of respiratory tract infections in humans. The formation of pneumococci-platelet associations may facilitate haematogenous dissemination of pneumococci by providing an adhesive surface on damaged endothelium. However, the formation of platelet-pneumococci associations and the factors involved in this process have not been described so far. The formation of platelet-pneumococci associates was analysed and quantified using flow cytometry. Binding of pneumococci to platelets was significantly increased after activation of platelets with thrombin, while platelet activation by ADP or collagen did not promote formation of platelet-pneumococci associates. In addition to be a platelet agonist, thrombin cleaves fibrinogen, which results in the generation of fibrin. The simultaneous formation of fibrin and activation of platelets was shown to be a prerequisite for a high number of platelet-pneumococci associates. Moreover, exogenously added human thrombospondin-1 (TSP-1) significantly enhanced the association of pneumococci with activated platelets. Soluble fibrin and TSP-1 are key co-factors of platelet-pneumococci-association. Similar results were recently demonstrated for S. aureus-platelet adhesion. Consequently, we hypothesise that the described mechanism of platelet-bacteria-association might represent a general and important strategy of Gram-positive bacteria during development of invasive diseases.

  19. Microtensile bond strength test and failure analysis to assess bonding characteristics of different adhesion approaches to ground versus unground enamel.

    Science.gov (United States)

    Hipólito, Vinicius Di; Alonso, Roberta Caroline Bruschi; Carrilho, Marcela Rocha de Oliveira; Anauate Netto, Camillo; Sinhoreti, Mário Alexandre Coelho; Goes, Mario Fernando de

    2011-01-01

    This study evaluated the bonding characteristics to ground and unground enamel obtained with different strategies. For this purpose, 24 sound third-molars were bisected mesiodistally to obtain tooth halves. A flat enamel area was delimited in the tooth sections, which were randomly distributed into 8 groups (n=6), according to the enamel condition (ground and unground) and adhesive system (Adper Single Bond 2 - SB2; Adper Prompt L-Pop - PLP; Adper Prompt - AD; Clearfil SE Bond - SE). Each system was applied according manufacturers' instructions and a 6-mm-high resin composite "crown" was incrementally built up on bonded surfaces. Hourglass-shaped specimens with 0.8 mm(2) cross-section were produced. Microtensile bond strength (μTBS) was recorded and the failure patterns were classified. Results were analyzed by two-way ANOVA and Tukey's test (α=0.05). There were no statistically significant differences among the μTBS values of SB2, PLP and AD (p>0.05). SE values were significantly lower (p0.05). There was prevalence of cohesive failure within enamel, adhesive system and resin composite for SB2. The self-etch systems produced higher incidence of cohesive failures in the adhesive system. Enamel condition did not determine significant differences on bonding characteristics for the same bonding system. In conclusion, the bonding systems evaluated in this study resulted in specific μTBS and failure patterns due to the particular interaction with enamel.

  20. Real-Time Visualization of Platelet Interaction With Micro Structured Surfaces.

    Science.gov (United States)

    Gester, Kathrin; Birtel, Stephan; Clauser, Johanna; Steinseifer, Ulrich; Sonntag, Simon Johannes

    2016-02-01

    Improving the hemocompatibility of artificial implants by micro structuring their surfaces has shown promising results, but the mechanisms which lead to this improvement are not yet understood. Therefore, we built a test setup for real-time visualization of platelet interaction with a plain and two micro structured surfaces. The micro structures, defined by the distance of the plain surface area between the structures, were chosen to be 3 and 30 μm, representing a positive and a negative effect on the hemocompatibility. The main part of the test setup was a flow chamber containing films of low density polyethylene (LDPE) with the differently structured surfaces. For different wall shear stresses, no considerable differences were observed in the platelet-surface interaction for all surface types. Whereas, major differences in flow behavior were observed when comparing the surfaces to each other. The platelets "rolled" along the smooth surface, being in constant contact with the surface material. Although the platelets "rolled" over the surface with small structures as well, they were only in contact with the tips of the structure and therefore had less surface contact with the foreign material. The increased distance and height of the structures of the last surface led to a trapping of platelets between the structures. This resulted in a longer contact time with the foreign material as well as a larger contact area, which both increase the risk of platelet activation, adhesion, and finally clotting. Our results showed the mechanisms which lead to these effects and thus revealed why micro structuring of surfaces impacts the hemocompatibility. Furthermore, we established a test setup which can be used for future investigations on the platelet-structure interactions.

  1. Normal Platelet Integrin Function in Mice Lacking Hydrogen Peroxide-Induced Clone-5 (Hic-5.

    Directory of Open Access Journals (Sweden)

    Michael Popp

    Full Text Available Integrin αIIbβ3 plays a central role in the adhesion and aggregation of platelets and thus is essential for hemostasis and thrombosis. Integrin activation requires the transmission of a signal from the small cytoplasmic tails of the α or β subunit to the large extracellular domains resulting in conformational changes of the extracellular domains to enable ligand binding. Hydrogen peroxide-inducible clone-5 (Hic-5, a member of the paxillin family, serves as a focal adhesion adaptor protein associated with αIIbβ3 at its cytoplasmic tails. Previous studies suggested Hic-5 as a novel regulator of integrin αIIbβ3 activation and platelet aggregation in mice. To assess this in more detail, we generated Hic-5-null mice and analyzed activation and aggregation of their platelets in vitro and in vivo. Surprisingly, lack of Hic-5 had no detectable effect on platelet integrin activation and function in vitro and in vivo under all tested conditions. These results indicate that Hic-5 is dispensable for integrin αIIbβ3 activation and consequently for arterial thrombosis and hemostasis in mice.

  2. Migration distance-based platelet function analysis in a microfluidic system

    OpenAIRE

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-01-01

    Aggregation and adhesion of platelets to the vascular wall are shear-dependent processes that play critical roles in hemostasis and thrombosis at vascular injury sites. In this study, we designed a simple and rapid assay of platelet aggregation and adhesion in a microfluidic system. A shearing mechanism using a rotating stirrer provided adjustable shear rate and shearing time and induced platelet activation. When sheared blood was driven through the microchannel under vacuum pressure, shear-a...

  3. Hereditary sideroblastic anemia with associated platelet abnormalities.

    Science.gov (United States)

    Soslau, G; Brodsky, I

    1989-12-01

    A 62 year old male (R.H.) presented with a mild anemia (Hb 11-12 gm%) and a history of multiple hemorrhagic episodes. The marrow had 40-50% sideroblasts. Marrow chromosomes were normal. His wife was hematologically normal, while one daughter, age 30 years, had a sideroblastic anemia (Hb 11-12 gm%) with 40-50% sideroblasts in the marrow. Her anemia was first noted at age 15 years. Administration of vitamin B6 did not correct the anemia in either the father or daughter. Platelet abnormalities inherited jointly with this disorder are described for the first time. Both R.H. and his daughter had prolonged bleeding times, with normal PTT, PT times, fVIII:C, fVIII:Ag levels, and vWF multimers, which may rule out a von Willebrand's disease. They have normal platelet numbers but abnormally low platelet adhesiveness and greatly depressed ADP, collagen, and epinephrine responsiveness. Response to ristocetin was in the low normal range, and aggregation with thrombin was normal. While desmopressin completely normalized R.H.'s bleeding time, none of these platelet parameters were improved. No differences in the SDS PAGE protein patterns of RH platelets could be detected in comparison to normal samples. His platelets took up and released serotonin (5HT) normally, and electron micrographs defined no morphological abnormalities. However, no ATP was released from platelets activated with collagen, and when followed by thrombin about fourfold greater ATP was released by control platelets as compared to RH platelets. The dense granule fraction derived from RH platelets contained about 20% the level of ATP, 40% the level of ADP, and 50% the level of 5HT detected in a normal sample. The results indicate that the bleeding disorder is related to a non-classical heritable storage pool defect. The connection between the inherited sideroblastic anemia and platelet defects is obscure.

  4. Development of a new test for the easy characterization of the adhesion at the interface of bilayer tablets: proof-of-concept study by experimental design.

    Science.gov (United States)

    Busignies, Virginie; Mazel, Vincent; Diarra, Harona; Tchoreloff, Pierre

    2014-12-30

    Although, adhesion at the interface of bilayer tablets is critical for their design it is difficult to characterize this adhesion between layers. In view of this, a new test with an easy implementation was proposed for the characterization of the interface of bilayer tablets. This work is presented as a proof-of-concept study to investigate the reliability of this new test with regard to the effects of some critical process parameters (e.g., compaction pressure applied on each layer) and material attributes (e.g., elasticity of the layered materials) on the interfacial adhesion of bilayer tablets. This was investigated using a design of experiment approach and the results obtained were in good accordance with those obtained with other tests and thus, confirms the potential of such a method for the measurement of the interfacial adhesion of bilayer tablets. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Life-threatening postpartum hemolysis, elevated liver functions tests, low platelets syndrome versus thrombocytopenic purpura - Therapeutic plasma exchange is the answer

    Directory of Open Access Journals (Sweden)

    Prashant Nasa

    2011-01-01

    Full Text Available The differential diagnosis of life-threatening microangiopathic disorders in a postpartum female includes severe preeclampsia-eclampsia, hemolysis, elevated liver functions tests, low platelets syndrome and thrombotic thrombocytopenic purpura. There is considerable overlapping in the clinical and laboratory findings between these conditions, and hence an exact diagnosis may not be always possible. However, there is considerable maternal mortality and morbidity associated with these disorders. This case underlines the complexity of pregnancy-related microangiopathies regarding their differential diagnosis, multiple organ dysfunction and role of therapeutic plasma exchange in their management.

  6. Interaction of platelets with poly(vinylidene fluoride-co-hexafluoropropylene) electrospun surfaces.

    Science.gov (United States)

    Ahmed, Furqan; Choudhury, Namita Roy; Dutta, Naba K; Brito e Abreu, Susana; Zannettino, Andrew; Duncan, Elizabeth

    2014-03-10

    Platelets are the major contributors in the process of thrombosis and in the failure of biomedical implants. A number of factors influence the platelet interaction with foreign surfaces such as surface morphology, surface chemistry, and adsorbed proteins. This study examined the effect of surface topography and chemistry of pristine and fibrinogen-adsorbed solvent cast (SC) and electrospun (ES) samples of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) on platelet adhesion, activation, and aggregation. Qualitative and quantitative studies of fibrinogen adsorption were performed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), while SEM, aggregometry, and liquid scintillation analyses were performed to evaluate platelet adhesion, aggregation, and serotonin release. While little or no platelet adhesion was observed on pristine ES surfaces, considerable adhesion, and measurable aggregation and serotonin release were observed on pristine SC surfaces. Notably, increased adhesion of platelets was observed following fibrinogen adsorption on SC surface with considerable aggregation and serotonin release compared with ES samples, where limited aggregation and platelet adhesion was observed. A further comparison of platelet adhesion, aggregation, and serotonin release was performed with plasma-adsorbed SC and ES surfaces. SC surfaces showed enhanced platelet adhesion, aggregation, and serotonin release compared to ES surfaces. This study shows that the morphology of samples plays a critical role on the biocompatibility of samples by altering the adsorption and adhesion of biomolecules and cells. The low level of adhesion, low aggregation, and serotonin release of platelets, even in the presence of fibrinogen and plasma-derived proteins, suggested that ES samples have the least thrombogenicity.

  7. Thrombopoietin induces p-selectin expression on platelets and subsequent platelet/leukocyte interactions.

    Science.gov (United States)

    Tibbles, Heather E; Navara, Christopher S; Hupke, Michael A; Vassilev, Alexei O; Uckun, Fatih M

    2002-04-12

    Ligation of thrombopoietin (TPO) to the platelet c-Mpl receptor induces numerous biochemical pathways in the absence of aggregation. Two forms of recombinant TPO are currently in clinical trials for the treatment of thrombocytopenia. This study focuses on the effects of the full-length recombinant human TPO (rhTPO) on platelets in a whole blood system. Platelet-leukocyte associations (PLAs) were visualized following rhTPO stimulation as CD42b/CD 45 double positive clusters by FACS analysis. Treatment of washed platelets with rhTPO induced granule release and expression of the leukocyte adhesion receptor P-selectin (CD 62P) in the absence of aggregation and calcium mobilization. RhTPO also induced platelet-leukocyte interactions in whole blood. Following stimulation, leukocytes were recruited by platelets through P-selectin in a calcium-dependent manner. rhTPO stimulates platelet-leukocyte associations in whole blood through expression of platelet P-selectin. To our knowledge, this is the first report that identifies TPO as a promoter of platelet-leukocyte interactions.

  8. In vitro bond strength and fatigue stress test evaluation of different adhesive cements used for fixed space maintainer cementation

    OpenAIRE

    Cantekin, Kenan; Delikan, Ebru; Cetin, Secil

    2014-01-01

    Objective: The purposes of this research were to (1) compare the shear-peel bond strength (SPBS) of a band of a fixed space maintainer (SM) cemented with five different adhesive cements; and (2) compare the survival time of bands of SM with each cement type after simulating mechanical fatigue stress. Materials and Methods: Seventy-five teeth were used to assess retentive strength and another 50 teeth were used to assess the fatigue survival time. SPBS was determined with a universal testing m...

  9. Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading Rate Applications - History and Rationale

    Science.gov (United States)

    2017-04-20

    NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Research Laboratory ATTN: RDRL-WMM-C Aberdeen Proving Ground, MD 21005-5069...8. PERFORMING ORGANIZATION REPORT NUMBER ARL-SR-0371 ARL-ADHES-QA-001.02 Rev 1.0 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10...provides the development history and rationale for the standard process description ARL-ADHES-QA-001.00 Rev 1.0, Adhesives: Test Method, Group

  10. Platelet-Leukocyte Interaction and Thrombosis

    Institute of Scientific and Technical Information of China (English)

    贺石林; 范金茹

    2007-01-01

    @@ Cerebrocardiac thrombotic disease such as acute myocardial infarction and acute ischemic stroke cause signifieant morbidity and mortality.Present therapies for these diseases besides anticoagulation and fibrinolysis mainly aim toward limiting platelet adhesion and aggregation processes.However,their incomplete effectiveness suggests that other mechanisms may be important.

  11. Congenital platelet function defects

    Science.gov (United States)

    ... storage pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... Congenital platelet function defects are bleeding disorders that ... function, even though there are normal platelet numbers. Most ...

  12. CYP2C19*2 and Other Allelic Variants Affecting Platelet Response to Clopidogrel Tested by Thrombelastography in Patients with Acute Coronary Syndrome

    Institute of Scientific and Technical Information of China (English)

    Jian Liu; Xiao-Yan Nie; Yong Zhang; Yun Lu; Lu-Wen Shi; Wei-Min Wang

    2015-01-01

    Background:To investigate the contributions ofCYP2C 19 polymorphisms to the various clopidogrel responses tested by thrombelastography (TEG) in Chinese patients with the acute coronary syndrome (ACS).Methods:Patients were screened prospectively with ACS diagnose and were treated with clopidogrel and aspirin dual antiplatelet therapy.CYP2C 19 loss of function (LOF) and gain of function (GOF) genotype,adenosine 5'-diphosphate (ADP)-channel platelet inhibition rate (PIR) tested by TEG and the occurrence of 3-month major adverse cardiovascular events and ischemic events were assessed in 116 patients.Results:High on-treatment platelet reactivity (HTPR) prevalence defined by PIR <30% by TEG in ADP-channel was 32.76% (38/116).With respect to the normal wild type,CYP2C 19*2,and *3 LOF alleles,and * 17 GOF alleles,patients were classified into three metabolism phenotypes:41.38% were extensive metabolizers (EMs),56.90% were intermediate metabolizers (IMs),and 1.72% were poor metabolizers (PMs).Of the enrolled patients,31.47%,5.17%,and 0.43%,respectively,were carriers of *2,*3,and * 17 alleles.The HTPR incidence differed significantly according to CYP2C 19 genotypes,accounting for 18.75%,41.54%,and 100.00% in EMs,IMs,and PMs,respectively.Eighteen (17.24%) ischemic events occurred during the 3-month follow-up,and there was a significant difference in ischemic events between HTPR group and nonhigh on-treatment platelet reactivity group.Conclusions:Genetic CYP2C 19 polymorphisms are relative to the inferior,the antiplatelet activity after clopidogrel admission and may increase the incidence of ischemic events in patients with ACS.

  13. Platelet receptor polymorphisms do not influence Staphylococcus aureus-platelet interactions or infective endocarditis.

    Science.gov (United States)

    Daga, Shruti; Shepherd, James G; Callaghan, J Garreth S; Hung, Rachel K Y; Dawson, Dana K; Padfield, Gareth J; Hey, Shi Y; Cartwright, Robyn A; Newby, David E; Fitzgerald, J Ross

    2011-03-01

    Cardiac vegetations result from bacterium-platelet adherence, activation and aggregation, and are associated with increased morbidity and mortality in infective endocarditis. The GPIIb/IIIa and FcγRIIa platelet receptors play a central role in platelet adhesion, activation and aggregation induced by endocarditis pathogens such as Staphylococcus aureus, but the influence of known polymorphisms of these receptors on the pathogenesis of infective endocarditis is unknown. We determined the GPIIIa platelet antigen Pl(A1/A2) and FcγRIIa H131R genotype of healthy volunteers (n = 160) and patients with infective endocarditis (n = 40), and investigated the influence of these polymorphisms on clinical outcome in infective endocarditis and S. aureus-platelet interactions in vitro. Platelet receptor genotype did not correlate with development of infective endocarditis, vegetation characteristics on echocardiogram or the composite clinical end-point of embolism, heart failure, need for surgery or mortality (P > 0.05 for all), even though patients with the GPIIIa Pl(A1/A1) genotype had increased in vivo platelet activation (P = 0.001). Furthermore, neither GPIIIa Pl(A1/A2) nor FcγRIIa H131R genotype influenced S. aureus-induced platelet adhesion, activation or aggregation in vitro (P > 0.05). Taken together, our data suggest that the GPIIIa and FcγRIIa platelet receptor polymorphisms do not influence S. aureus-platelet interactions in vitro or the clinical course of infective endocarditis.

  14. Platelet receptor polymorphisms do not influence Staphylococcus aureus–platelet interactions or infective endocarditis

    Science.gov (United States)

    Daga, Shruti; Shepherd, James G.; Callaghan, J. Garreth S.; Hung, Rachel K.Y.; Dawson, Dana K.; Padfield, Gareth J.; Hey, Shi Y.; Cartwright, Robyn A.; Newby, David E.; Fitzgerald, J. Ross

    2011-01-01

    Cardiac vegetations result from bacterium–platelet adherence, activation and aggregation, and are associated with increased morbidity and mortality in infective endocarditis. The GPIIb/IIIa and FcγRIIa platelet receptors play a central role in platelet adhesion, activation and aggregation induced by endocarditis pathogens such as Staphylococcus aureus, but the influence of known polymorphisms of these receptors on the pathogenesis of infective endocarditis is unknown. We determined the GPIIIa platelet antigen PlA1/A2 and FcγRIIa H131R genotype of healthy volunteers (n = 160) and patients with infective endocarditis (n = 40), and investigated the influence of these polymorphisms on clinical outcome in infective endocarditis and S. aureus–platelet interactions in vitro. Platelet receptor genotype did not correlate with development of infective endocarditis, vegetation characteristics on echocardiogram or the composite clinical end-point of embolism, heart failure, need for surgery or mortality (P > 0.05 for all), even though patients with the GPIIIa PlA1/A1 genotype had increased in vivo platelet activation (P = 0.001). Furthermore, neither GPIIIa PlA1/A2 nor FcγRIIa H131R genotype influenced S. aureus-induced platelet adhesion, activation or aggregation in vitro (P > 0.05). Taken together, our data suggest that the GPIIIa and FcγRIIa platelet receptor polymorphisms do not influence S. aureus–platelet interactions in vitro or the clinical course of infective endocarditis. PMID:21044892

  15. Disabled-2 modulates homotypic and heterotypic platelet interactions by binding to sulfatides.

    Science.gov (United States)

    Welsh, John D; Charonko, John J; Salmanzadeh, Alireza; Drahos, Karen E; Shafiee, Hadi; Stremler, Mark A; Davalos, Rafael V; Capelluto, Daniel G S; Vlachos, Pavlos P; Finkielstein, Carla V

    2011-07-01

    Disabled-2 (Dab2) inhibits platelet aggregation by competing with fibrinogen for binding to the α(IIb) β(3) integrin receptor, an interaction that is modulated by Dab2 binding to sulfatides at the outer leaflet of the platelet plasma membrane. The disaggregatory function of Dab2 has been mapped to its N-terminus phosphotyrosine-binding (N-PTB) domain. Our data show that the surface levels of P-selectin, a platelet transmembrane protein known to bind sulfatides and promote cell-cell interactions, are reduced by Dab2 N-PTB, an event that is reversed in the presence of a mutant form of the protein that is deficient in sulfatide but not in integrin binding. Importantly, Dab2 N-PTB, but not its sulfatide binding-deficient form, was able to prevent sulfatide-induced platelet aggregation when tested under haemodynamic conditions in microfluidic devices at flow rates with shear stress levels corresponding to those found in vein microcirculation. Moreover, the regulatory role of Dab2 N-PTB extends to platelet-leucocyte adhesion and aggregation events, suggesting a multi-target role for Dab2 in haemostasis.

  16. Evaluation of tensile strength of tissue adhesives and sutures for clear corneal incisions using porcine and bovine eyes, with a novel standardized testing platform

    Directory of Open Access Journals (Sweden)

    Kaja S

    2012-02-01

    Full Text Available Simon Kaja, Daryl L Goad, Fatima Ali, Ashley Abraham, R Luke Rebenitsch, Savak Teymoorian, Rohit Krishna, Peter KoulenVision Research Center and Department of Ophthalmology, University of Missouri-Kansas City, School of Medicine, Kansas City, MO, USABackground: Tissue adhesives for ophthalmologic applications were proposed almost 50 years ago, yet to date no adequate tissue glues have been identified that combine strong sealing properties with adequate safety and absence of postsurgical side effects. In recent years, cataract surgeries and Descemet's stripping with endothelial keratoplasty procedures have significantly increased the number of clear corneal incisions performed. One of the obstacles to discovery and development of novel tissue adhesives has been the result of nonstandardized testing of potential tissue glues.Methods: We developed an instrument capable of controlling intraocular pressure in explanted porcine and bovine eyes in order to evaluate sealants, adhesives, and surgical closure methods used in ophthalmic surgery in a controlled, repeatable, and validated fashion. We herein developed and validated our instrument by testing the adhesive properties of cyanoacrylate glue in both porcine and bovine explant eyes.Results: The instrument applied and maintained intraocular pressure through a broad range of physiological intraocular pressures. Cyanoacrylate-based glues showed significantly enhanced sealing properties of clear corneal incisions compared with sutured wounds.Conclusion: This study shows the feasibility of our instrument for reliable and standardized testing of tissue adhesive for ophthalmological surgery.Keywords: manometer, intraocular pressure, applanation tonometry, clear corneal incision, tissue adhesive, ocular surgery

  17. Pre-analytical effects of pneumatic tube system transport on routine haematology and coagulation tests, global coagulation assays and platelet function assays.

    Science.gov (United States)

    Le Quellec, Sandra; Paris, Mickaël; Nougier, Christophe; Sobas, Frédéric; Rugeri, Lucia; Girard, Sandrine; Bordet, Jean-Claude; Négrier, Claude; Dargaud, Yesim

    2017-05-01

    Pneumatic tube system (PTS) in hospitals is commonly used for the transport of blood samples to clinical laboratories, as it is rapid and cost-effective. The aim was to compare the effects on haematology samples of a newly acquired ~2km-long PTS that links 2 hospitals with usual transport (non-pneumatic tube system, NPTS). Complete blood cell count, routine coagulation assays, platelet function tests (PFT) with light-transmission aggregometry and global coagulation assays including ROTEM® and thrombin generation assay (TGA) were performed on blood samples from 30 healthy volunteers and 9 healthy volunteers who agreed to take aspirin prior to blood sampling. The turnaround time was reduced by 31% (p<0.001) with the use of PTS. No statistically significant difference was observed for most routine haematology assays including PFT, and ROTEM® analysis. A statistically significant, but not clinically relevant, shortening of the APTT after sample transport by PTS was found (mean±SD: 30s±1.8 vs. 29.5s±2.1 for NPTS). D-dimer levels were 7.4% higher after transport through PTS but were not discordant. A statistically significant increase of thrombin generation was found in both platelet poor- and platelet rich- plasma samples after PTS transport compared to NPTS transport. PTS is suitable for the transport of samples prior to routine haematology assays including PFT, but should not be used for samples intended for thrombin generation measurement. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Head to Head Comparison of Two Point-of-care Platelet Function Tests Used for Assessment of On-clopidogrel Platelet Reactivity in Chinese Acute Myocardial Infarction Patients Undergoing Percutaneous Coronary Intervention

    Directory of Open Access Journals (Sweden)

    Yi Yao

    2016-01-01

    Conclusions: By comparing VerifyNow to TEG which has been widely used in clinics, VerifyNow could be an attractive alternative to TEG for monitoring on-clopidogrel platelet reactivity in Chinese patients.

  19. Platelet MicroRNAs: An Overview.

    Science.gov (United States)

    Dahiya, Neetu; Sarachana, Tewarit; Vu, Long; Becker, Kevin G; Wood, William H; Zhang, Yongqing; Atreya, Chintamani D

    2015-10-01

    MicroRNAs (miRNAs) are short ~22-nucleotide noncoding RNA that have been found to influence the expression of many genes and cellular processes by either repressing translation or degrading messenger RNA transcripts. Platelet miRNA expression has been shown to be perturbed during ex vivo storage of platelets and in platelet-associated disorders. Although bioinformatics-based miRNA target predictions have been established, direct experimental validation of the role of miRNAs in platelet biology has been rather slow. Target prediction studies are, nonetheless, valuable in directing the design of appropriate experiments to test specific miRNA:messenger RNA interactions relevant to the underlying mechanisms of platelet function in general and in disease as well as in ex vivo storage-associated "storage lesions," a collective term used to include physiologic, biochemical, and morphologic changes that occur in stored platelets. This brief review will focus on emerging human platelet miRNA studies to emphasize their potential role relevant to transfusion medicine field in terms of regulating platelet signaling pathways, markers of platelet associated disorders, and remote impactors of gene expression (intercellular biomodulators) as well as potential platelet quality markers of storage and pathogen reduction treatments.

  20. Magnetic field switchable dry adhesives.

    Science.gov (United States)

    Krahn, Jeffrey; Bovero, Enrico; Menon, Carlo

    2015-02-01

    A magnetic field controllable dry adhesive device is manufactured. The normal adhesion force can be increased or decreased depending on the presence of an applied magnetic field. If the magnetic field is present during the entire normal adhesion test cycle which includes both applying a preloading force and measuring the pulloff pressure, a decrease in adhesion is observed when compared to when there is no applied magnetic field. Similarly, if the magnetic field is present only during the preload portion of the normal adhesion test cycle, a decrease in adhesion is observed because of an increased stiffness of the magnetically controlled dry adhesive device. When the applied magnetic field is present during only the pulloff portion of the normal adhesion test cycle, either an increase or a decrease in normal adhesion is observed depending on the direction of the applied magnetic field.

  1. In-vitro model for the ultrastructural study of the formation of thrombi in human platelets.

    Science.gov (United States)

    Cerecedo, Doris; González, Sirenia; Mondragón, Mónica; Reyes, Elba; Mondragón, Ricardo

    2006-03-01

    Platelets are cell fragments with dynamic properties involved in clot formation after tissue damage. Platelet activation causes a change in shape, secretion of intracellular granules and aggregation with each other through the cytoskeleton components and biochemical changes. Platelet adhesion, considered as the major event in haemostasis, has been studied in several in-vitro and in-vivo models to evaluate the feasible thrombogenicity of some materials, the dynamics of specific receptors, as well as the effect of different buffers and inhibitors in this process. In spite of the numerous reports about platelet activation, to date there is no information available about the fine structure of the platelet-platelet and platelet-substrate interactions. In the present report we describe an in-vitro system that allows the visualization of these interactions: platelets are adhered to an inert substrate, and interactions with suspended platelets as a process to initiate the formation of thrombi was followed by ultramicrotomy and transmission electron microscopy.

  2. Interaction of platelets with collagen substrate: role of platelet prostaglandin endoperoxides and thromboxane A/sub 2/

    Energy Technology Data Exchange (ETDEWEB)

    Mazurov, A.B.; Leitin, V.L.; Repin, V.S.

    1985-04-01

    In this investigation, the role of PG-endoperoxides and TA/sub 2/ in interaction of platelets and a collagen-coated surface was studied. For this purpose, the effects of exogenous AA, of U46619, a stable analog of PG endoperoxides, which simulates the action of PG endoperoxides and TA/sub 2/ on platelets at the receptor level, and of aspirin, a cyclooxygenase inhibitor, on platelet-surface interaction were investigated. The quantity of TA/sub 2/ synthesized in the platelets was determined by measuring accumulation of its stable product TB/sub 2/. After adhesion of the platelets the incubation medium was removed, nonadherent platelets were destroyed by freezing and thawing, and TB/sub 2/ was determined by radioimmunoassay.

  3. 组织因子途径抑制因子对生物材料表面血小板粘附的影响%Effect of Tissue Factor Pathway Inhibitor on the Adhesion of Platelet onto Polyethylene and Polyvinylchloride Membranes

    Institute of Scientific and Technical Information of China (English)

    冷希岗; 王传华; 宋丽萍; 王彭延

    2001-01-01

    Tissue factor pathway inhibitor(TFPI) is the majo rinhibitor of the extrinsic pathway of the blood coagulation cascade. Our previous study showed that TFPI could obviously prolong the blood coagulation time on the surface of polyethelene(PE) and polyvinylchloride(PVC) membranes in vitro and decrease the generation of thrombus on Dacron membrane in vivo. In the pressent sutdy, the effect of TFPI on the adhesion of platelet onto PE and PVC membr anes was investigated. PE or PVC membrane was cut into small pieces and incubated in 96-well culture plate with GST or GST-TFPI fusion protein at 4℃ over night. Freshly collected rabbit blood was mixed with 3.8% sodium citrate. Platelet-rich plasma was separated by centrifugation and then incubated with the treated membranes at 37℃ for 30 minutes. The membranes were then washed, fixed, and freeze-dehydrated Adhesion of platelet was observed through scanning electronic microscope. The result showed that GST-TFPI treatment significantly decrea sed the number of platelet adhered on the membrane when compared with the GST and control group,and it suggested that TFPI might have a great potential to be used as an anticoagulant for improving the hemocompatibility of biomaterials.%组织因子途径抑制因子(tissue factor pathway in hibitor, TFPI)是组织因子凝血途径的主要抑制因子,具有抑制组织因子、凝血因子VIIa、 和Xa的功能。我们以前的研究显示TFPI在体外可以明显延长被修饰材料表面的凝血时间,在 体内显著减少材料表面的血栓形成。本文观察了TFPI包被对聚乙烯和聚氯乙烯材料表面血小 板粘附的影响。结果显示,通过TFPI处理后,上述两种材料表面的血小板粘附数目较对照组 明显减少,提示TFPI可通过抑制血小板在材料表面的粘附起到改善生物材料血液相容性的作用。

  4. Platelet matching for alloimmunized patients

    Institute of Scientific and Technical Information of China (English)

    S H.Hsu

    2010-01-01

    @@ Platelets play an essential role in blood coagulation,hemostasis and maintenance of vascular integrity.Platelets are utilized primarily to prevent or treat bleeding in thrombocytopenic patients and patients with impaired platelet production in the bone marrow and/or with dysfunctional platelets.In current practice,platelet transfusion begins with randomly selected platelet products:either pooled platelets prepared from whole blood derived platelets; or single donor platelets prepared by apheresis procedures.

  5. A platelet monoclonal antibody inhibition assay for detection of glycoprotein IIb/IIIa-related platelet alloantibodies.

    Science.gov (United States)

    Reiner, A P; Teramura, G; Nelson, K A; Slichter, S J

    1995-08-18

    Post-transfusion purpura (PTP) and neonatal alloimmune thrombocytopenia (NAT) result from formation of alloantibodies to platelet membrane glycoprotein-associated antigens. The detection and identification of platelet-specific alloantibodies in patient sera is often complicated by the presence of co-existing HLA antibodies and/or more than one platelet specificity in the same serum. We describe a solid phase assay that specifically detects antibodies to platelet membrane associated alloantigens by measuring the ability of patient antisera to inhibit the binding of glycoprotein GPIIb or GPIIIa monoclonal antibodies to intact platelets. When tested in the GPIIIa assay against a panel of random platelet donors, the reactivities of two known PLAI antisera that also contained different HLA antibodies were highly correlated (r = 0.99) and allowed PLA phenotyping of the population. A standard direct binding platelet ELISA, on the other hand, was unable to accurately PLA phenotype the same population. The reactivities of two known Baka antisera (one containing additional anti-PLA2 and the other anti-Brb specificities) were highly correlated (r = 0.95) in the GPIIb assay, and Bak phenotype determination was similarly accomplished for a random platelet panel. Furthermore, a comparison of platelet phenotype results (using the monoclonal inhibition assay) and genotype results (using DNA analysis) for the PLA and Bak systems showed a concordance of 98% for 146 alleles tested. In conclusion, the platelet monoclonal antibody inhibition assay: (1) allows determination of platelet-specific alloantibodies in the presence of contaminating HLA antibodies and/or in sera containing multiple platelet alloantibodies; (2) allows accurate platelet phenotyping for the GPIIIa-associated PLA and GPIIb-associated Bak antigen systems; and (3) may be applicable to the detection of other known or even novel platelet glycoprotein-associated antigens.

  6. Analysis of aggregation of platelets in thrombosis

    Science.gov (United States)

    Ahuja, Suresh

    Platelets are key players in thrombus formation by first rolling over collagen bound von Willebrand factor followed by formation of a stable interaction with collagen. The first adhered platelets bind additional platelets until the whole injury is sealed off by a platelet aggregate. The coagulation system stabilizes the formed platelet plug by creating a tight fibrin network, and then wound contraction takes place because of morphological changes in platelets. Coagulation takes place by platelet activation and aggregation mainly through fibrinogen polymerization into fibrin fibers. The process includes multiple factors, such as thrombin, plasmin, and local shear-rate which regulate and control the process. Coagulation can be divided into two pathways: the intrinsic pathway and the extrinsic pathway. The intrinsic pathway is initiated by the exposure of a negatively charged. It is able to activate factor XII, using a complex reaction that includes prekallikrein and high-molecular-weight kininogen as cofactors.. Thrombin is the final enzyme that is needed to convert fibrinogen into fibrin. The extrinsic pathway starts with the exposure of tissue factor to the circulating blood, which is the major initiator of coagulation. There are several feedback loops that reinforce the coagulation cascade, resulting in large amounts of thrombin. It is dependent on the presence of pro-coagulant surfaces of cells expressing negatively charged phospholipids--which include phosphatidylserine (PS)--on their outer membrane. PS-bearing surfaces are able to increase the efficiency of the reactions by concentrating and co-localizing coagulation factors.. Aggregation of platelets are analyzed and compared to adhesion of platelet to erythrocyte and to endothelial cells. This abstract is replacing MAR16-2015-020003.

  7. [Platelet allo-antibodies identification strategies for preventing and managing platelet refractoriness].

    Science.gov (United States)

    Basire, A; Picard, C

    2014-11-01

    Platelet refractoriness is a serious complication for patients receiving recurrent platelet transfusions, which can be explained by non-immune and immune causes. Human Leukocyte Antigens (HLA) allo-immunization, especially against HLA class I, is the major cause for immune platelet refractoriness. To a lesser extent, allo-antibodies against specific Human Platelet Antigen (HPA) are also involved. Pregnancy, transplantation and previous transfusions can lead to allo-immune reaction against platelet antigens. After transfusion, platelet count is decreased by accelerated platelet destruction related to antibodies fixation on incompatible platelet antigens. New laboratory tests for allo-antibodies identification were developed to improve sensibility and specificity, especially with the LUMINEX(®) technology. The good use and interpretation of these antibodies assays can improve strategies for platelet refractoriness prevention and management with a patient adapted response. Compatible platelets units can be selected according to their identity with recipient typing or immune compatibility regarding HLA or HPA antibodies or HLA epitope compatibility. Prospective studies are needed to further confirm the clinical benefit of new allo-antibodies identification methods and consensus strategies for immune platelet refractoriness management.

  8. 正确认识血小板功能检测在急性冠状动脉综合征患者抗血小板治疗中的价值%Deciphering the platelet function test inacute coronary syndrome patients subjected to anti-platelet therapy

    Institute of Scientific and Technical Information of China (English)

    张真路; 张李涛

    2016-01-01

    抗血小板治疗是急性冠脉综合征( ACS)治疗的基石,血小板功能检测可以评估抗血小板治疗的效果,而关于血小板功能检测是否能用于指导ACS抗血小板治疗依然存在争论。另外血小板功能检测的方法众多,常见用于抗血小板治疗监测的检测方法各有优缺点。根据近年循证资料、指南共识和临床经验,对ACS疾病中,血小板功能检测的目标人群、药物、检测方法、质量保证及结果解释进行综述,希望能有助于检验人员和临床医生正确理解血小板功能检测在ACS患者抗血小板治疗中的意义。(中华检验医学杂志,2016,39:743-746)%Anti-platelet therapy plays a key role in acute coronary syndrome ( ACS ) treatments.Platelet function tests could monitor the effect of anti-platelet drugs′, however, it is still under debate that whether platelet function monitoring could be used to adjust antiplatelet therapy.Additionally, there are a number of platelet function assays, and each of them has specifically advantages and disadvantages.This article reviewed evidence-based information, guidelines, consensus and clinical experience about platelet function monitoring in ACS patients, which was intend to help laboratory technicians and clinicians understanding the value of platelet function tests in monitoring anti-platelet therapy.

  9. The functional role of platelets in the regulation of angiogenesis.

    Science.gov (United States)

    Walsh, Tony G; Metharom, Pat; Berndt, Michael C

    2015-01-01

    Functionally, platelets are primarily recognized as key regulators of thrombosis and hemostasis. Upon vessel injury, the typically quiescent platelet interacts with subendothelial matrix to regulate platelet adhesion, activation and aggregation, with subsequent induction of the coagulation cascade forming a thrombus. Recently, however, newly described roles for platelets in the regulation of angiogenesis have emerged. Platelets possess an armory of pro- and anti-angiogenic proteins, which are actively sequestered and highly organized in α-granule populations. Platelet activation facilitates their release, eliciting potent angiogenic responses through mechanisms that appear to be tightly regulated. In conjunction, the release of platelet-derived phospholipids and microparticles has also earned merit as synergistic regulators of angiogenesis. Consequently, platelets have been functionally implicated in a range of angiogenesis-dependent processes, including physiological roles in wound healing, vascular development and blood/lymphatic vessel separation, whilst facilitating aberrant angiogenesis in a range of diseases including cancer, atherosclerosis and diabetic retinopathy. Whilst the underlying mechanisms are only starting to be elucidated, significant insights have been established, suggesting that platelets represent a promising therapeutic strategy in diseases requiring angiogenic modulation. Moreover, anti-platelet therapies targeting thrombotic complications also exert protective effects in disorders characterized by persistent angiogenesis.

  10. Effects of bemiparin and heparin on blood pressure, renal and liver function tests and platelet indices of salt-loaded uninephrectomized rats

    Directory of Open Access Journals (Sweden)

    K. Dizaye

    2011-01-01

    Full Text Available Low-molecular-weight Heparins (LMWHs are being preferred to unfractionated Heparin (UFH because of their superior convenience and comparable or slightly better toxicity profile. This study was designed to investigate and compare the effects of LMWH (Bemiparin and Heparin on hemodynamic parameters, liver and renal function tests and platelet indices of salt-loaded uninephrectomized hypertensive rats. The experimental rats divided into two groups. The first group included 18 hypertensive rats. Hypertension induced by unilateral nephrectomy and high NaCl loading with 4% NaCl in diet for 4 weeks. The rat models were subdivided into three groups, each subgroup consists of six rats. The first subgroup served as a positive control. The second subgroup received a daily intraperitoneal (I.P injection (250 unit/kg of Bemiparin for thirty days. The third sub group received daily I.P injection (250 unit/kg of Heparin for thirty days. The second group included six rats underwent sham operated surgery and served as a control group. Blood pressure was recorded in conscious rats by the tail-cuff plethmography method. At the end of the experiments, blood samples were collected from the rats for determination of serum creatinine, blood urea nitrogen, serum total bilirubin, serum sodium, potassium, calcium, aspartate aminotransferase (AST, alanine aminotransferase (ALT, alkaline phosphatase (ALP concentrations and platelet indices. Compared to sham control rats, Systolic blood pressure in uninephrectomized loaded with a high salt was significantly reduced by administration of both Bemiparin and Heparin. Serum K+ and Na+ levels of hypertensive rats were significantly increased. Bemiparin significantly lowered serum K+ and Na+ levels of uninephrectomized rats, while Heparin did not change serum K+ and Na+ levels. The rise in both blood urea and serum creatinine of salt-loaded uninephrectomized hypertensive rats were significantly (P<0.05 reduced by Bemiparin and

  11. Performance evaluation of PL-11 platelet analyzer

    Institute of Scientific and Technical Information of China (English)

    张有涛

    2013-01-01

    Objective To evaluate and report the performance of PL-11 platelet analyzer. Methods Intravenous blood sam-ples anticoagulated with EDTA-K2 and sodium citrate were tested by the PL-11 platelet analyzer to evaluate the intra-assay and interassay coefficient of variation(CV),

  12. Adhesives: Test Method, Group Assignment, and Categorization Guide for High-Loading-Rate Applications

    Science.gov (United States)

    2014-06-01

    D5229M-12 (Standard Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials),10 ASTM D1151...Test Method for Moisture Absorption Properties and Equilibrium Conditioning of Polymer Matrix Composite Materials." ASTM International, West

  13. Identification of platelet refractoriness in oncohematologic patients

    Directory of Open Access Journals (Sweden)

    Aline Aparecida Ferreira

    2011-01-01

    Full Text Available OBJECTIVES: To identify the occurrence and the causes of platelet refractoriness in oncohematologic patients. INTRODUCTION: Platelet refractoriness (unsatisfactory post-transfusion platelet increment is a severe problem that impairs the treatment of oncohematologic patients and is not routinely investigated in most Brazilian services. METHODS: Forty-four episodes of platelet concentrate transfusion were evaluated in 16 patients according to the following parameters: corrected count increment, clinical conditions and detection of anti-platelet antibodies by the platelet immunofluorescence test (PIFT and panel reactive antibodies against human leukocyte antigen class I (PRA-HLA. RESULTS: Of the 16 patients evaluated (median age: 53 years, nine (56% were women, seven of them with a history of pregnancy. An unsatisfactory increment was observed in 43% of the transfusion events, being more frequent in transfusions of random platelet concentrates (54%. Platelet refractoriness was confirmed in three patients (19%, who presented immunologic and non-immunologic causes. Alloantibodies were identified in eight patients (50% by the PIFT and in three (19% by the PRA-HLA. Among alloimmunized patients, nine (64% had a history of transfusion, and three as a result of pregnancy (43%. Of the former, two were refractory (29%. No significant differences were observed, probably as a result of the small sample size. CONCLUSION: The high rate of unsatisfactory platelet increment, refractoriness and alloimmunization observed support the need to set up protocols for the investigation of this complication in all chronically transfused patients, a fundamental requirement for the guarantee of adequate management.

  14. Platelets, acting in part via P-selectin, mediate cytomegalovirus-induced microvascular dysfunction.

    Science.gov (United States)

    Khoretonenko, Mikhail V; Brunson, Jerry L; Senchenkov, Evgeny; Leskov, Igor L; Marks, Christian R; Stokes, Karen Y

    2014-12-15

    Cytomegalovirus (CMV) infects a majority of the population worldwide. It has been implicated in cardiovascular disease, induces microvascular dysfunction, and synergizes with hypercholesterolemia to promote leukocyte and platelet recruitment in venules. Although platelets and platelet-associated P-selectin contribute to cardiovascular disease inflammation, their role in CMV-induced vascular responses is unknown. We assessed the role of platelets in CMV-induced microvascular dysfunction by depleting platelets and developing bone marrow chimeric mice deficient in platelet P-selectin. Wild-type and chimeric mice received mock or murine (m)CMV intraperitoneally. Five weeks later, some mice were switched to a high-cholesterol diet (HC) to investigate the synergism between mCMV and HC. Arteriolar vasodilation and recruitment of leukocytes and donor platelets in venules were measured at 11wk. mCMV with or without HC caused significant endothelial dysfunction in arterioles. Platelet depletion restored normal vasodilation in mCMV-HC but not mCMV-ND mice, whereas protection was seen in both groups for platelet P-selectin chimeras. Only mCMV + HC elevated leukocyte and platelet recruitment in venules. Leukocyte adhesion was reduced to mock levels by acute platelet depletion but was only partially decreased in platelet P-selectin chimeras. Platelets from mCMV-HC mice and, to a lesser extent, mCMV-ND but not mock-HC mice showed significant adhesion in mCMV-HC recipients. Our findings implicate a role for platelets, acting through P-selectin, in CMV-induced arteriolar dysfunction and suggest that the addition of HC leads to a platelet-dependent, inflammatory infiltrate that is only partly platelet P-selectin dependent. CMV appeared to have a stronger activating influence than HC on platelets and may represent an additional therapeutic target in vulnerable patients.

  15. Effect of different adhesion strategies on fiber post cementation: Push-out test and scanning electron microscopy analysis.

    Science.gov (United States)

    Saraiva, Letícia Oliveria; Aguiar, Thaiane Rodrigues; Costa, Leonardo; Correr-Sobrinho, Lourenço; Muniz, Leonardo; Mathias, Paula

    2013-10-01

    The aim of this study was to investigate the effect of phosphoric acid etching and the dentin pre-treatment with sodium hypochlorite (NaOCl) on the push-out bond strength between fiber post and root canal dentin. Root canals of 48 human incisors were selected, post spaces were prepared and assigned to four groups: G1-37% phosphoric acid (15 s); G2-5.25% NaOCl (2 min) +37% phosphoric acid (15 s); G3-37% phosphoric acid (60 s); and G4-5.25% NaOCl (2 min) +37% phosphoric acid (60 s). Fiber post cementation was performed with two-step etch-and-rinse adhesive system/dual-cured resin cement according to the manufacturer's recommendation. After 24 h, each root was sectioned transversally into three slices (cervical, middle and apical) and the bond strength of each section was determined using a push-out bond strength test. Morphology analysis of the bonded interface was evaluated using a scanning electron microscopy. Push-out strength data (MPa) were analyzed by Analysis of Variance and Tukey-Kramer (α = 0.05). Considering the NaOCl pre-treatment, no statistically significant differences were observed among groups; however, when the phosphoric acid was applied during 60 s in the apical portion without NaOCl pre-treatment, the bond strength was statistically significant increased. The NaOCl pre-treatment did not improve the bond strength of adhesive luting cement to root canal dentin. The findings suggest that the use of 37% phosphoric acid for 60 s may have a beneficial effect on bond strength in the apical root third.

  16. Effect of different adhesion strategies on fiber post cementation: Push-out test and scanning electron microscopy analysis

    Directory of Open Access Journals (Sweden)

    Letícia Oliveria Saraiva

    2013-01-01

    Full Text Available Aim: The aim of this study was to investigate the effect of phosphoric acid etching and the dentin pre-treatment with sodium hypochlorite (NaOCl on the push-out bond strength between fiber post and root canal dentin. Materials and Methods: Root canals of 48 human incisors were selected, post spaces were prepared and assigned to four groups: G1-37% phosphoric acid (15 s; G2-5.25% NaOCl (2 min +37% phosphoric acid (15 s; G3-37% phosphoric acid (60 s; and G4-5.25% NaOCl (2 min +37% phosphoric acid (60 s. Fiber post cementation was performed with two-step etch-and-rinse adhesive system/dual-cured resin cement according to the manufacturer′s recommendation. After 24 h, each root was sectioned transversally into three slices (cervical, middle and apical and the bond strength of each section was determined using a push-out bond strength test. Morphology analysis of the bonded interface was evaluated using a scanning electron microscopy. Push-out strength data (MPa were analyzed by Analysis of Variance and Tukey-Kramer (α = 0.05. Results: Considering the NaOCl pre-treatment, no statistically significant differences were observed among groups; however, when the phosphoric acid was applied during 60 s in the apical portion without NaOCl pre-treatment, the bond strength was statistically significant increased. Conclusion: The NaOCl pre-treatment did not improve the bond strength of adhesive luting cement to root canal dentin. The findings suggest that the use of 37% phosphoric acid for 60 s may have a beneficial effect on bond strength in the apical root third.

  17. Migration distance-based platelet function analysis in a microfluidic system.

    Science.gov (United States)

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-01-01

    Aggregation and adhesion of platelets to the vascular wall are shear-dependent processes that play critical roles in hemostasis and thrombosis at vascular injury sites. In this study, we designed a simple and rapid assay of platelet aggregation and adhesion in a microfluidic system. A shearing mechanism using a rotating stirrer provided adjustable shear rate and shearing time and induced platelet activation. When sheared blood was driven through the microchannel under vacuum pressure, shear-activated platelets adhered to a collagen-coated surface, causing blood flow to significantly slow and eventually stop. To measure platelet adhesion and aggregation, the migration distance (MD) of blood through the microchannel was monitored. As the microstirrer speed increased, MD initially decreased exponentially but then increased beyond a critical rpm. For platelet-excluded blood samples, there were no changes in MD with increasing stirrer speed. These findings imply that the stirrer provided sufficiently high shear to activate platelets and that blood MD is a potentially valuable index for measuring the shear-dependence of platelet activation. Our microfluidic system is quick and simple, while providing a precise assay to measure the effects of shear on platelet aggregation and adhesion.

  18. Platelet size and density affect shear-induced thrombus formation in tortuous arterioles

    Science.gov (United States)

    Chesnutt, Jennifer K. W.; Han, Hai-Chao

    2013-10-01

    Thrombosis accounts for 80% of deaths in patients with diabetes mellitus. Diabetic patients demonstrate tortuous microvessels and larger than normal platelets. Large platelets are associated with increased platelet activation and thrombosis, but the physical effects of large platelets in the microscale processes of thrombus formation are not clear. Therefore, the objective of this study was to determine the physical effects of mean platelet volume (MPV), mean platelet density (MPD) and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A computational model of the transport, shear-induced activation, collision, adhesion and aggregation of individual platelets was used to simulate platelet interactions and thrombus formation in tortuous arterioles. Our results showed that an increase in MPV resulted in a larger number of activated platelets, though MPD and level of tortuosity made little difference on platelet activation. Platelets with normal MPD yielded the lowest amount of mural thrombus. With platelets of normal MPD, the amount of mural thrombus decreased with increasing level of tortuosity but did not have a simple monotonic relationship with MPV. The physical mechanisms associated with MPV, MPD and arteriole tortuosity play important roles in platelet activation and thrombus formation.

  19. 阿司匹林和氯吡格雷对体外血小板黏附内皮细胞基质活性的影响及其机制研究%Ettects ot Aspirin and Clopidogrel on the Adhesion Activity ot Platelet to Endothelial Cell Matrix in Vitro and Its Mechanism

    Institute of Scientific and Technical Information of China (English)

    朱晋坤; 毛华; 尹扬光; 董文; 杜峰; 鲁玉明; 熊宗华; 邓梦扬

    2015-01-01

    200μl 血小板黏附内皮细胞基质活性分别低于对照组、阿司匹林组和氯吡格雷组(P ﹤0.05)。蛋白质免疫印迹法显示,阿司匹林和氯吡格雷均能抑制由 ox - LDL 引起的 TM 表达的减少。ox - LDL 能明显诱导血管内皮细胞 LOX -1表达,阿司匹林能明显抑制由 ox - LDL 引起的 LOX -1和 IL -6的表达;而氯吡格雷则能明显抑制内皮细胞 CD40的表达。结论阿司匹林和氯吡格雷均能从上调 TM 和抑制炎性因子两方面降低血小板对内皮细胞基质的黏附作用。但两者联合更能抑制由 ox - LDL引起的炎性因子的表达,降低血小板对内皮细胞基质的黏附。%Objective To study the effects of aspirin and clopidogrel on the adhesion activity of platelet to endothelial cell matrix in vitro and its mechanism, and to find the reasons why combination use of two drugs is better than monotherapy. Methods A total of 42 healthy female SD rats were bought from the animal centre of Third Military Medical University. By using random number table method,SD rats were divided into aspirin group(8 rats),clopidogrel group(8 rats),aspirin and clopidogrel(combination)group(8 rats),control group(8 rats),the other 10 rats were used for primary isolation and culture of cells. The isolated and cultured primary rat vascular endothelial cells were treated with ox - LDL to establish damaged vascular endothelial cell model. 100 mg/ kg aspirin,10 mg/ kg clopidogrel,combination of 100 mg/ kg aspirin and 10 mg/ kg clopidogrel,and 200 μl castor oil were used respectively to prepare endothelial cell matrix plate. 3 days before the separation and preparation of platelet from plasma,rats in aspirin group were fed with 100 mg·kg - 1 ·d - 1 aspirin,rats in clopidogrel group were fed with 10 mg·kg - 1 ·d - 1 clopidogrel,rats in aspirin and clopidogrel group were fed with 100 mg·kg - 1 ·d - 1 aspirin and 10 mg·kg - 1 ·d - 1 clopidogrel,rats in control group were fed with

  20. A novel inflammatory role for platelets in sickle cell disease.

    Science.gov (United States)

    Davila, Jennifer; Manwani, Deepa; Vasovic, Ljiljana; Avanzi, Mauro; Uehlinger, Joan; Ireland, Karen; Mitchell, W Beau

    2015-01-01

    The severe pain, ischemia and organ damage that characterizes sickle cell disease (SCD) is caused by vaso-occlusion, which is the blockage of blood vessels by heterotypic aggregates of sickled erythrocytes and other cells. Vaso-occlusion is also a vasculopathy involving endothelial cell dysfunction, leukocyte activation, platelet activation and chronic inflammation resulting in the multiple adhesive interactions between cellular elements. Since platelets mediate inflammation as well as thrombosis via release of pro- and anti-inflammatory molecules, we hypothesized that platelets may play an active inflammatory role in SCD by secreting increased amounts of cytokines. Since platelets have been shown to contain mRNA and actively produce proteins, we also hypothesized that SCD platelets may contain increased cytokine mRNA. In this cross-sectional study, we sought to compare both the quantity of cytokines secreted and the cytokine mRNA content, between SCD and control platelets. We measured the secretion of Th1, Th2, and Th17-related cytokines from platelets in a cohort of SCD patients. We simultaneously measured platelet mRNA levels of those cytokines. Platelets from SCD patients secreted increased quantities of IL-1β, sCD40L, and IL-6 compared to controls. Secretion was increased in patients with alloantibodies. Additionally, mRNA of those cytokines was increased in SCD platelets. Platelets from sickle cell patients secrete increased amounts of inflammatory cytokines, and contain increased cytokine mRNA. These findings suggest a novel immunological role for platelets in SCD vasculopathy, in addition to their thrombotic role, and strengthen the rationale for the use of anti-platelet therapy in SCD.

  1. Defining predictive values using three different platelet function tests for CYP2C19 phenotype status on maintenance dual antiplatelet therapy after PCI.

    Science.gov (United States)

    Zhang, Hong-Zhe; Kim, Moo Hyun; Han, Jin-Yeong; Jeong, Young-Hoon

    2014-01-01

    Published data suggests that the presence of CYP2C19*2 or *3 loss of function (LOF) alleles is indicative of increased platelet aggregation and a higher risk of adverse cardiovascular events after clopidogrel administration. We sought to determine cut-off values using three different assays for prediction of the CYP2C19 phenotype in Korean percutaneous coronary intervention (PCI) patients. We enrolled 244 patients with drug-eluting stent implantation who were receiving clopidogrel and aspirin maintenance therapy for one month or more. Platelet reactivity was assessed with light transmittance aggregometry (LTA), multiple electrode aggregometry (MEA) and the VerifyNow P2Y12 assay (VN). The CYP2C19 genotype was analyzed by polymerase chain reaction (PCR) and snapshot method. The frequency of CYP2C19 LOF allele carriers was 58.6%. The cut-off values from LTA, MEA and VerifyNow for the identification of LOF allele carriers were as follows: 10 µM ADP-induced LTA ≥ 48 %, VN>242 PRU and MEA ≥ 37 U. Between the three tests, correlation was higher between LTA vs. VN assays (r=0.69) and LTA vs. MEA (r=0.56), with moderate agreement (κ=0.46 and κ=0.46), but between VN assay and MEA, both devices using whole blood showed a lower correlation (r=0.42) and agreement (κ=0.3). Our results provide guidance regarding cut-off levels for LTA, VerifyNow and MEA assays to detect the CYP2C19 LOF allele in patients during dual antiplatelet maintenance therapy.

  2. Dengue virus binding and replication by platelets.

    Science.gov (United States)

    Simon, Ayo Y; Sutherland, Michael R; Pryzdial, Edward L G

    2015-07-16

    Dengue virus (DENV) infection causes ∼200 million cases of severe flulike illness annually, escalating to life-threatening hemorrhagic fever or shock syndrome in ∼500,000. Although thrombocytopenia is typical of both mild and severe diseases, the mechanism triggering platelet reduction is incompletely understood. As a probable initiating event, direct purified DENV-platelet binding was followed in the current study by quantitative reverse transcription-polymerase chain reaction and confirmed antigenically. Approximately 800 viruses specifically bound per platelet at 37°C. Fewer sites were observed at 25°C, the blood bank storage temperature (∼350 sites), or 4°C, known to attenuate virus cell entry (∼200 sites). Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and heparan sulfate proteoglycan were implicated as coreceptors because only the combination of anti-DC-SIGN and low-molecular-weight heparin prevented binding. Interestingly, at 37°C and 25°C, platelets replicated the positive sense single-stranded RNA genome of DENV by up to ∼4-fold over 7 days. Further time course experiments demonstrated production of viral NS1 protein, which is known to be highly antigenic in patient serum. The infectivity of DENV intrinsically decayed in vitro, which was moderated by platelet-mediated generation of viable progeny. This was shown using a transcription inhibitor and confirmed by freeze-denatured platelets being incapable of replicating the DENV genome. For the first time, these data demonstrate that platelets directly bind DENV saturably and produce infectious virus. Thus, expression of antigen encoded by DENV is a novel consideration in the pathogen-induced thrombocytopenia mechanism. These results furthermore draw attention to the possibility that platelets may produce permissive RNA viruses in addition to DENV.

  3. Electro-dry-adhesion.

    Science.gov (United States)

    Krahn, Jeffrey; Menon, Carlo

    2012-03-27

    This work presents novel conductive bioinspired dry adhesives with mushroom caps that enable the use of a synergistic combination of electrostatic and van der Waals forces (electro-dry-adhesion). An increase in shear adhesion bond strength of up to 2046% on a wide range of materials is measured when a maximum electrical field of 36.4 V μm(-1) is applied. A suction effect, due to the shape of the dry adhesive fibers, on overall adhesion was not noted for electro-dry-adhesives when testing was performed at both atmospheric and reduced pressure. Utilization of electrostatics to apply a preloading force to dry adhesive fiber arrays allows increased adhesion even after electrostatic force generation has been halted by ensuring the close contact necessary for van der Waals forces to be effective. A comparison is made between self-preloading of the electro-dry-adhesives and the direct application of a normal preloading pressure resulting in nearly the same shear bond strength with an applied voltage of 3.33 kV on the same sample.

  4. Adhesive Categories

    DEFF Research Database (Denmark)

    Lack, Stephen; Sobocinski, Pawel

    2003-01-01

    We introduce adhesive categories, which are categories with structure ensuring that pushouts along monomorphisms are well-behaved. Many types of graphical structures used in computer science are shown to be examples of adhesive categories. Double-pushout graph rewriting generalises well...... to rewriting on arbitrary adhesive categories....

  5. Quantitative characterization of the interfacial adhesion of Ni thin film on steel substrate: A compression-induced buckling delamination test

    Science.gov (United States)

    Zhu, W.; Zhou, Y. C.; Guo, J. W.; Yang, L.; Lu, C.

    2015-01-01

    A compression-induced buckling delamination test is employed to quantitatively characterize the interfacial adhesion of Ni thin film on steel substrate. It is shown that buckles initiate from edge flaws and surface morphologies exhibit symmetric, half-penny shapes. Taking the elastoplasticity of film and substrate into account, a three-dimensional finite element model for an edge flaw with the finite size is established to simulate the evolution of energy release rates and phase angles in the process of interfacial buckling-driven delamination. The results show that delamination propagates along both the straight side and curved front. The mode II delamination plays a dominant role in the process with a straight side whilst the curved front experiences almost the pure mode I. Based on the results of finite element analysis, a numerical model is developed to evaluate the interfacial energy release rate, which is in the range of 250-315 J/m2 with the corresponding phase angle from -41° to -66°. These results are in agreement with the available values determined by other testing methods, which confirms the effectiveness of the numerical model.

  6. F-111 Adhesively Bonded Repair Assessment Program (FABRAP) - Phase 1 Testing, Preliminary Results

    Science.gov (United States)

    2011-08-01

    UNCLASSIFIED 4 UNCLASSIFED DSTO-TN-1024  aircraft that have been reserved for other use such as museum displays. Negotiations are underway to test...additional hazards when used outside of a fume cupboard/booth. Citrasafe is a non-toxic low volatile plant extract solvent which has been shown to be...work during hayfever seasons may expose workers to pollen allergens. Staff with known allergies will be advised to prepare by using

  7. Laboratory Test for Measurement of Adhesion Strength of Spray Ice to Coated Flat Plates

    Science.gov (United States)

    1990-05-01

    became trapped within the ice. After the by test group 612 during icing due to nozzle freezeup sprayer was turned off, the unfrozen water became and the...indicated if and when nozzle freezeup occurred. Short and the push block increased as the block moved for- duration peaks in the nozzle temperature occurred...either nozzle freezeup and conse- bond strength of each sample. Notice, in Figure 2 1. the quent efforts to thaw, the application of more insulation

  8. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical Univ. Lubeck, Lubeck (DE))

    1990-01-01

    This book presents papers on the clinical applications of radiolabelled platelets. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection.

  9. Platelet antibody detection by flow cytometry: an effective method to evaluate and give transfusional support in platelet refractoriness

    Directory of Open Access Journals (Sweden)

    Carolina Bonet Bub

    2013-01-01

    Full Text Available BACKGROUND: Immune platelet refractoriness is mainly caused by human leukocyte antigen antibodies (80-90% of cases and, to a lesser extent, by human platelet antigen antibodies. Refractoriness can be diagnosed by laboratory tests and patients should receive compatible platelet transfusions. A fast, effective and low cost antibody-screening method which detects platelet human leukocyte/platelet antigen antibodies is essential in the management of immune platelet refractoriness. OBJECTIVE: The aim of this study was to evaluate the efficiency of the flow cytometry platelet immunofluorescence test to screen for immune platelet refractoriness. METHODS: A group of prospective hematologic patients with clinically suspected platelet refractoriness treated in a referral center in Campinas, SP during July 2006 and July 2011 was enrolled in this study. Platelet antibodies were screened using the flow cytometry platelet immunofluorescence test. Anti-human leukocyte antigen antibodies were detected by commercially available methods. The sensitivity, specificity and predictive values of the immunofluorescence test were determined taking into account that the majority of antiplatelet antibodies presented human leukocyte antigen specificity. RESULTS: Seventy-six samples from 32 female and 38 male patients with a median age of 43.5 years (range: 5-84 years were analyzed. The sensitivity of the test was 86.11% and specificity 75.00% with a positive predictive value of 75.61% and a negative predictive value of 85.71%. The accuracy of the method was 80.26%. CONCLUSION: This study shows that the flow cytometry platelet immunofluorescence test has a high correlation with the anti-human leukocyte antigen antibodies. Despite a few limitations, the method seems to be efficient, fast and feasible as the initial screening for platelet antibody detection and a useful tool to crossmatch platelets for the transfusional support of patients with immune platelet refractoriness.

  10. Platelet satellitism in infectious disease?

    Science.gov (United States)

    Laskaj, Renata; Sikiric, Dubravka; Skerk, Visnja

    2015-01-01

    Background Platelet satellitism is a phenomenon of unknown etiology of aggregating platelets around polymorphonuclear neutrophils and other blood cells which causes pseudothrombocytopenia, visible by microscopic examination of blood smears. It has been observed so far in about a hundred cases in the world. Case subject and methods Our case involves a 73-year-old female patient with a urinary infection. Biochemical serum analysis (CRP, glucose, AST, ALT, ALP, GGT, bilirubin, sodium, potassium, chloride, urea, creatinine) and blood cell count were performed with standard methods on autoanalyzers. Serum protein fractions were examined by electrophoresis and urinalysis with standard methods on autoanalyzer together with microscopic examination of urine sediment. Erythrocyte sedimentation rate, blood culture and urine culture tests were performed with standard methods. Results Due to typical pathological values for bacterial urinary infection, the patient was admitted to the hospital. Blood smear examination revealed phenomenon, which has persisted for three weeks after the disease has been cured. Blood smears with EDTA as an anticoagulant had platelet satellitism whereas the phenomenon was not observed in tubes with different anticoagulants (Na, Li-heparin) and capillary blood. Discussion We hypothesize that satellitism was induced by some immunological mechanism through formation of antibodies which have mediated platelets binding to neutrophil membranes and vice versa. Unfortunately we were unable to determine the putative trigger for this phenomenon. To our knowledge this is the second case of platelet satellitism ever described in Croatia. PMID:26110042

  11. Lightning protection guidelines and test data for adhesively bonded aircraft structures

    Science.gov (United States)

    Pryzby, J. E.; Plumer, J. A.

    1984-01-01

    The highly competitive marketplace and increasing cost of energy has motivated manufacturers of general aviation aircraft to utilize composite materials and metal-to-metal bonding in place of conventional fasteners and rivets to reduce weight, obtain smoother outside surfaces and reduce drag. The purpose of this program is protection of these new structures from hazardous lightning effects. The program began with a survey of advance-technology materials and fabrication methods under consideration for future designs. Sub-element specimens were subjected to simulated lightning voltages and currents. Measurements of bond line voltages, electrical sparking, and mechanical strength degradation were made to comprise a data base of electrical properties for new technology materials and basic structural configurations. The second hase of the program involved tests on full scale wing structures which contained integral fuel tanks and which were representative of examples of new technology structures and fuel systems. The purpose of these tests was to provide a comparison between full scale structural measurements and those obtained from the sub-element specimens.

  12. Regulation of the genetic code in megakaryocytes and platelets.

    Science.gov (United States)

    Rondina, M T; Weyrich, A S

    2015-06-01

    Platelets are generated from nucleated precursors referred to as megakaryocytes. The formation of platelets is one of the most elegant and unique developmental processes in eukaryotes. Because they enter the circulation without nuclei, platelets are often considered simple, non-complex cells that have limited functions beyond halting blood flow. However, emerging evidence over the past decade demonstrates that platelets are more sophisticated than previously considered. Platelets carry a rich repertoire of messenger RNAs (mRNAs), microRNAs (miRNAs), and proteins that contribute to primary (adhesion, aggregation, secretion) and alternative (immune regulation, RNA transfer, translation) functions. It is also becoming increasingly clear that the 'genetic code' of platelets changes with race, genetic disorders, or disease. Changes in the 'genetic code' can occur at multiple points including megakaryocyte development, platelet formation, or in circulating platelets. This review focuses on regulation of the 'genetic code' in megakaryocytes and platelets and its potential contribution to health and disease. © 2015 International Society on Thrombosis and Haemostasis.

  13. Multiwavelength UV/visible spectroscopy for the quantitative investigation of platelet quality

    Science.gov (United States)

    Mattley, Yvette D.; Leparc, German F.; Potter, Robert L.; Garcia-Rubio, Luis H.

    1998-04-01

    The quality of platelets transfused is vital to the effectiveness of the transfusion. Freshly prepared, discoid platelets are the most effective treatment for preventing spontaneous hemorrhage or for stopping an abnormal bleeding event. Current methodology for the routine testing of platelet quality involves random pH testing of platelet rich plasma and visual inspection of platelet rich plasma for a swirling pattern indicative of the discoid shape of the cells. The drawback to these methods is that they do not provide a quantitative and objective assay for platelet functionality that can be used on each platelet unit prior to transfusion. As part of a larger project aimed at characterizing whole blood and blood components with multiwavelength UV/vis spectroscopy, isolated platelets and platelet in platelet rich plasma have been investigated. Models based on Mie theory have been developed which allow for the extraction of quantitative information on platelet size, number and quality from multi-wavelength UV/vis spectra. These models have been used to quantify changes in platelet rich plasma during storage. The overall goal of this work is to develop a simple, rapid quantitative assay for platelet quality that can be used prior to platelet transfusion to ensure the effectiveness of the treatment. As a result of this work, the optical properties for isolated platelets, platelet rich plasma and leukodepleted platelet rich plasma have been determined.

  14. Glycoprotein VI but not alpha2beta1 integrin is essential for platelet interaction with collagen

    DEFF Research Database (Denmark)

    Nieswandt, B; Brakebusch, C; Bergmeier, W

    2001-01-01

    Platelet adhesion on and activation by components of the extracellular matrix are crucial to arrest post-traumatic bleeding, but can also harm tissue by occluding diseased vessels. Integrin alpha2beta1 is thought to be essential for platelet adhesion to subendothelial collagens, facilitating...... subsequent interactions with the activating platelet collagen receptor, glycoprotein VI (GPVI). Here we show that Cre/loxP-mediated loss of beta1 integrin on platelets has no significant effect on the bleeding time in mice. Aggregation of beta1-null platelets to native fibrillar collagen is delayed......, but not reduced, whereas aggregation to enzymatically digested soluble collagen is abolished. Furthermore, beta1-null platelets adhere to fibrillar, but not soluble collagen under static as well as low (150 s(-1)) and high (1000 s(-1)) shear flow conditions, probably through binding of alphaIIbbeta3 to von...

  15. p38 mitogen-activated protein kinase activation during platelet storage: consequences for platelet recovery and hemostatic function in vivo.

    Science.gov (United States)

    Canault, Matthias; Duerschmied, Daniel; Brill, Alexander; Stefanini, Lucia; Schatzberg, Daphne; Cifuni, Stephen M; Bergmeier, Wolfgang; Wagner, Denisa D

    2010-03-01

    Platelets undergo several modifications during storage that reduce their posttransfusion survival and functionality. One important feature of these changes, which are known as platelet storage lesion, is the shedding of the surface glycoproteins GPIb-alpha and GPV. We recently demonstrated that tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) mediates mitochondrial injury-induced shedding of adhesion receptors and that TACE activity correlates with reduced posttransfusion survival of these cells. We now confirm that TACE mediates receptor shedding and clearance of platelets stored for 16 hours at 37 degrees C or 22 degrees C. We further demonstrate that both storage and mitochondrial injury lead to the phosphorylation of p38 mitogen-activated kinase (MAPK) in platelets and that TACE-mediated receptor shedding from mouse and human platelets requires p38 MAP kinase signaling. Protein kinase C, extracellular regulated-signal kinase MAPK, and caspases were not involved in TACE activation. Both inhibition of p38 MAPK and inactivation of TACE during platelet storage led to a markedly improved posttransfusion recovery and hemostatic function of platelets in mice. p38 MAPK inhibitors had only minor effects on the aggregation of fresh platelets under static or flow conditions in vitro. In summary, our data suggest that inhibition of p38 MAPK or TACE during storage may significantly improve the quality of stored platelets.

  16. The effect of centrifugation speed and time on pre-analytical platelet activation

    DEFF Research Database (Denmark)

    Söderström, Anna Cecilia; Nybo, Mads; Nielsen, Christian

    2016-01-01

    . METHODS: Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean...... platelet volume (MPV), immature platelet fraction (IPF), and platelet distribution width (PDW) were measured. Platelet aggregation in platelet-rich plasma induced by arachidonic acid (AA), ADP or thrombin receptor activator peptide-6 (TRAP) was tested by 96-well aggregometry. RESULTS: The median percentage...... of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), p...

  17. Short-term adhesion and long-term biofouling testing of polydopamine and poly(ethylene glycol) surface modifications of membranes and feed spacers for biofouling control

    KAUST Repository

    Miller, Daniel J.

    2012-08-01

    Ultrafiltration, nanofiltration membranes and feed spacers were hydrophilized with polydopamine and polydopamine- g-poly(ethylene glycol) surface coatings. The fouling propensity of modified and unmodified membranes was evaluated by short-term batch protein and bacterial adhesion tests. The fouling propensity of modified and unmodified membranes and spacers was evaluated by continuous biofouling experiments in a membrane fouling simulator. The goals of the study were: 1) to determine the effectiveness of polydopamine and polydopamine- g-poly(ethylene glycol) membrane coatings for biofouling control and 2) to compare techniques commonly used in assessment of membrane biofouling propensity with biofouling experiments under practical conditions. Short-term adhesion tests were carried out under static, no-flow conditions for 1 h using bovine serum albumin, a common model globular protein, and Pseudomonas aeruginosa, a common model Gram-negative bacterium. Biofouling tests were performed in a membrane fouling simulator (MFS) for several days under flow conditions similar to those encountered in industrial modules with the autochthonous drinking water population and acetate dosage as organic substrate. Polydopamine- and polydopamine- g-poly(ethylene glycol)-modified membranes showed significantly reduced adhesion of bovine serum albumin and P. aeruginosa in the short-term adhesion tests, but no reduction of biofouling was observed during longer biofouling experiments with modified membranes and spacers. These results demonstrate that short-term batch adhesion experiments using model proteins or bacteria under static conditions are not indicative of biofouling, while continuous biofouling experiments showed that membrane surface modification by polydopamine and polydopamine- g-poly(ethylene glycol) is not effective for biofouling control. © 2012 Elsevier Ltd.

  18. Short-term adhesion and long-term biofouling testing of polydopamine and poly(ethylene glycol) surface modifications of membranes and feed spacers for biofouling control.

    Science.gov (United States)

    Miller, Daniel J; Araújo, Paula A; Correia, Patricia B; Ramsey, Matthew M; Kruithof, Joop C; van Loosdrecht, Mark C M; Freeman, Benny D; Paul, Donald R; Whiteley, Marvin; Vrouwenvelder, Johannes S

    2012-08-01

    Ultrafiltration, nanofiltration membranes and feed spacers were hydrophilized with polydopamine and polydopamine-g-poly(ethylene glycol) surface coatings. The fouling propensity of modified and unmodified membranes was evaluated by short-term batch protein and bacterial adhesion tests. The fouling propensity of modified and unmodified membranes and spacers was evaluated by continuous biofouling experiments in a membrane fouling simulator. The goals of the study were: 1) to determine the effectiveness of polydopamine and polydopamine-g-poly(ethylene glycol) membrane coatings for biofouling control and 2) to compare techniques commonly used in assessment of membrane biofouling propensity with biofouling experiments under practical conditions. Short-term adhesion tests were carried out under static, no-flow conditions for 1 h using bovine serum albumin, a common model globular protein, and Pseudomonas aeruginosa, a common model Gram-negative bacterium. Biofouling tests were performed in a membrane fouling simulator (MFS) for several days under flow conditions similar to those encountered in industrial modules with the autochthonous drinking water population and acetate dosage as organic substrate. Polydopamine- and polydopamine-g-poly(ethylene glycol)-modified membranes showed significantly reduced adhesion of bovine serum albumin and P. aeruginosa in the short-term adhesion tests, but no reduction of biofouling was observed during longer biofouling experiments with modified membranes and spacers. These results demonstrate that short-term batch adhesion experiments using model proteins or bacteria under static conditions are not indicative of biofouling, while continuous biofouling experiments showed that membrane surface modification by polydopamine and polydopamine-g-poly(ethylene glycol) is not effective for biofouling control. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Fractal and Euclidean descriptors of platelet shape.

    Science.gov (United States)

    Kraus, Max-Joseph; Neeb, Heiko; Strasser, Erwin F

    2014-01-01

    Platelet shape change is a dynamic membrane surface process that exhibits remarkable morphological heterogeneity. Once the outline of an irregular shape is identified and segmented from a digital image, several mathematical descriptors can be applied to numerical characterize the irregularity of the shapes surface. 13072 platelet outlines (PLO) were segmented automatically from 1928 microscopic images using a newly developed algorithm for the software product Matlab R2012b. The fractal dimension (FD), circularity, eccentricity, area and perimeter of each PLO were determined. 972 PLO were randomly assigned for computer-assisted manual measurement of platelet diameter as well as number, width and length of filopodia per platelet. FD can be used as a surrogate parameter for determining the roughness of the PLO and circularity can be used as a surrogate to estimate the number and length of filopodia. The relationship between FD and perimeter of the PLO reveals the existence of distinct groups of platelets with significant structural differences which may be caused by platelet activation. This new method allows for the standardized continuous numerical classification of platelet shape and its dynamic change, which is useful for the analysis of altered platelet activity (e.g. inflammatory diseases, contact activation, drug testing).

  20. Platelet affinity for burro aorta collagen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.D.

    1977-10-01

    Despite ingenious concepts, there are no unequivocal clues as to what, when, and how some undefined biochemical factor(s) or constituent(s) that localizes in the arterial wall can precipitate a thromboatheromatous lesion or arterial disease. The present study focused on the extraction, partial purification, and characterization of a collagen-active platelet stimulator from the aortas of aged burros. The aggregator moiety in the aorta extracts invariably had a higher affinity for platelets in citrated platelet-rich plasma of human beings than for platelets of homologous burros. The platelet-aggregating factor(s) in the aorta extract was retained by incubation with ..cap alpha..-chymotrypsin. Platelet-aggregating activity was rapidly abolished after incubation with collagenase, as determined by platelet-aggregometry tests. Evidence based on light microscope and polysaccharide histochemical reactions indicates a probability that the intracellular amorphous matrix (PAS-positive) and filamentous components (PTAH-positive) expelled from smooth muscle cells disrupted during homogenization of the aorta may be a principal source of a precursor collagen species which is a potent inducer of platelet aggregation.

  1. The prognostic utility of tests of platelet function for the detection of 'aspirin resistance' in patients with established cardiovascular or cerebrovascular disease: a systematic review and economic evaluation.

    Science.gov (United States)

    Dretzke, Janine; Riley, Richard D; Lordkipanidzé, Marie; Jowett, Susan; O'Donnell, Jennifer; Ensor, Joie; Moloney, Eoin; Price, Malcolm; Raichand, Smriti; Hodgkinson, James; Bayliss, Susan; Fitzmaurice, David; Moore, David

    2015-01-01

    BACKGROUND The use of aspirin is well established for secondary prevention of cardiovascular disease. However, a proportion of patients suffer repeat cardiovascular events despite being prescribed aspirin treatment. It is uncertain whether or not this is due to an inherent inability of aspirin to sufficiently modify platelet activity. This report aims to investigate whether or not insufficient platelet function inhibition by aspirin ('aspirin resistance'), as defined using platelet function tests (PFTs), is linked to the occurrence of adverse clinical outcomes, and further, whether or not patients at risk of future adverse clinical events can be identified through PFTs. OBJECTIVES To review systematically the clinical effectiveness and cost-effectiveness evidence regarding the association between PFT designation of 'aspirin resistance' and the risk of adverse clinical outcome(s) in patients prescribed aspirin therapy. To undertake exploratory model-based cost-effectiveness analysis on the use of PFTs. DATA SOURCES Bibliographic databases (e.g. MEDLINE from inception and EMBASE from 1980), conference proceedings and ongoing trial registries up to April 2012. METHODS Standard systematic review methods were used for identifying clinical and cost studies. A risk-of-bias assessment tool was adapted from checklists for prognostic and diagnostic studies. (Un)adjusted odds and hazard ratios for the association between 'aspirin resistance', for different PFTs, and clinical outcomes are presented; however, heterogeneity between studies precluded pooling of results. A speculative economic model of a PFT and change of therapy strategy was developed. RESULTS One hundred and eight relevant studies using a variety of PFTs, 58 in patients on aspirin monotherapy, were analysed in detail. Results indicated that some PFTs may have some prognostic utility, i.e. a trend for more clinical events to be associated with groups classified as 'aspirin resistant'. Methodological and clinical

  2. Mice lacking the SLAM family member CD84 display unaltered platelet function in hemostasis and thrombosis.

    Directory of Open Access Journals (Sweden)

    Sebastian Hofmann

    Full Text Available BACKGROUND: Platelets are anuclear cell fragments derived from bone marrow megakaryocytes that safeguard vascular integrity by forming thrombi at sites of vascular injury. Although the early events of thrombus formation--platelet adhesion and aggregation--have been intensively studied, less is known about the mechanisms and receptors that stabilize platelet-platelet interactions once a thrombus has formed. One receptor that has been implicated in this process is the signaling lymphocyte activation molecule (SLAM family member CD84, which can undergo homophilic interactions and becomes phosphorylated upon platelet aggregation. OBJECTIVE: The role of CD84 in platelet physiology and thrombus formation was investigated in CD84-deficient mice. METHODS AND RESULTS: We generated CD84-deficient mice and analyzed their platelets in vitro and in vivo. Cd84(-/- platelets exhibited normal activation and aggregation responses to classical platelet agonists. Furthermore, CD84 deficiency did not affect integrin-mediated clot retraction and spreading of activated platelets on fibrinogen. Notably, also the formation of stable three-dimensional thrombi on collagen-coated surfaces under flow ex vivo was unaltered in the blood of Cd84(-/- mice. In vivo, Cd84(-/- mice exhibited unaltered hemostatic function and arterial thrombus formation. CONCLUSION: These results show that CD84 is dispensable for thrombus formation and stabilization, indicating that its deficiency may be functionally compensated by other receptors or that it may be important for platelet functions different from platelet-platelet interactions.

  3. Platelet-derived HMGB1 is a critical mediator of thrombosis.

    Science.gov (United States)

    Vogel, Sebastian; Bodenstein, Rebecca; Chen, Qiwei; Feil, Susanne; Feil, Robert; Rheinlaender, Johannes; Schäffer, Tilman E; Bohn, Erwin; Frick, Julia-Stefanie; Borst, Oliver; Münzer, Patrick; Walker, Britta; Markel, Justin; Csanyi, Gabor; Pagano, Patrick J; Loughran, Patricia; Jessup, Morgan E; Watkins, Simon C; Bullock, Grant C; Sperry, Jason L; Zuckerbraun, Brian S; Billiar, Timothy R; Lotze, Michael T; Gawaz, Meinrad; Neal, Matthew D

    2015-12-01

    Thrombosis and inflammation are intricately linked in several major clinical disorders, including disseminated intravascular coagulation and acute ischemic events. The damage-associated molecular pattern molecule high-mobility group box 1 (HMGB1) is upregulated by activated platelets in multiple inflammatory diseases; however, the contribution of platelet-derived HMGB1 in thrombosis remains unexplored. Here, we generated transgenic mice with platelet-specific ablation of HMGB1 and determined that platelet-derived HMGB1 is a critical mediator of thrombosis. Mice lacking HMGB1 in platelets exhibited increased bleeding times as well as reduced thrombus formation, platelet aggregation, inflammation, and organ damage during experimental trauma/hemorrhagic shock. Platelets were the major source of HMGB1 within thrombi. In trauma patients, HMGB1 expression on the surface of circulating platelets was markedly upregulated. Moreover, evaluation of isolated platelets revealed that HMGB1 is critical for regulating platelet activation, granule secretion, adhesion, and spreading. These effects were mediated via TLR4- and MyD88-dependent recruitment of platelet guanylyl cyclase (GC) toward the plasma membrane, followed by MyD88/GC complex formation and activation of the cGMP-dependent protein kinase I (cGKI). Thus, we establish platelet-derived HMGB1 as an important mediator of thrombosis and identify a HMGB1-driven link between MyD88 and GC/cGKI in platelets. Additionally, these findings suggest a potential therapeutic target for patients sustaining trauma and other inflammatory disorders associated with abnormal coagulation.

  4. Platelets enhance neutrophil transendothelial migration via P-selectin glycoprotein ligand-1

    Science.gov (United States)

    Platelets are increasingly recognized as important for inflammation in addition to thrombosis. Platelets promote the adhesion of neutrophils [polymorphonuclear neutrophils (PMNs)] to the endothelium; P-selectin and P-selectin glycoprotein ligand (PSGL)-1 have been suggested to participate in these i...

  5. IVBT-documented platelet function correlates with flow cytometric data.

    Science.gov (United States)

    Hoffmann, J; Bonacker, G; Kretschmer, V; Schulzki, T; Heimanns, J

    1996-12-01

    Thrombocytopenic patients with identical platelet counts often show different bleeding tendencies owing to significant differences in the platelet function. This could be demonstrated by the in vitro bleeding test (IVBT). Using flow cytometry, we tried to find characteristics of platelet antigen expression in order to explain these differences in function. Thirty patients with bone marrow hypoplasia receiving 65 platelet transfusions (mainly from a cell separator) were observed for 3 to 29 days. Size, granulation and fluorescence of platelet-rich plasma (n = 522 samples) were evaluated using monoclonal antibodies against GP IIIb (collagen receptor), GP IIb/IIIa (fibrinogen receptor) and GP Ib (thrombin receptor). We defined separate gates for each antibody using the results from 50 normals and by laying an orthograde cross over the gate to divide the gate into four equal quadrants. The platelet populations were divided into four different groups according to the occlusion time (OT) of the IVBT and the Simplate time (ST). The thrombocytes with the most impaired function (OT > or = 485 s/ST > 30 min) had significantly less platelet fluorescence when marked with antibodies against GP IIIb and GP Ib than those with short OT and ST (OT platelet fluorescence when marked with anti-GP IIIb and anti-GP Ib than thrombocytopenic patients, who had a spontaneous platelet rise beyond 30,000 platelets/microliters a few days later. One day after platelet transfusion, significantly more platelets with high GP IIIb and Ib expression could be found. We were also able to document better transfusion efficacy of platelet concentrates with high GP IIIb and Ib expression. Finally, patients with high bleeding scores showed less GP Ib expression on the platelets than patients with low bleeding scores. In summary, the IVBT-documented platelet function clearly corresponded to an increased expression of the collagen receptor and the thrombin receptor of platelets.

  6. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev

    2014-09-01

    Full Text Available Platelets are anuclear cell fragments playing important role in hemostasis, termination of bleeding after damage, as well as in pathological thrombus formation. The main action of platelets is the formation of aggregates, overlapping the injury. They obtained the ability to aggregate by the transition process called activation. Despite the relatively simple and definite function platelet structure is very difficult: they have almost a full set of organelles, including the endoplasmic reticulum, mitochondria and other entities. When activated platelets secrete various granules interact with plasma proteins and red blood cells and other tissues. Their activation is controlled by multiple receptors and complex signaling cascades. In this review platelet structure, mechanisms of its functioning in health and disease, diagnostic methods of platelet function and approaches to their correction were considered. Particular attention will be given to those areas of the science of platelets, which still lay hidden mysteries.

  7. Human platelet antigen genotyping of platelet donors in southern Brazil.

    Science.gov (United States)

    Merzoni, J; Fagundes, I S; Lunardi, L W; Lindenau, J D-R; Gil, B C; Jobim, M; Dias, V G; Merzoni, L; Sekine, L; Onsten, T G H; Jobim, L F

    2015-10-01

    Human platelet antigens (HPA) are immunogenic structures that result from single nucleotide polymorphisms (SNPs) leading to single amino acid substitutions. This study sought to determine the allele and genotype frequencies of HPA-1, HPA-2, HPA-3, HPA-4, HPA-5 and HPA-15 in platelet donors from the state of Rio Grande do Sul (RS), Brazil, and compare their allele frequencies to those observed in other populations. HPA genotyping was performed by PCR-SSP method. The study sample comprised 201 platelet donors (167 Caucasians and 34 non-Caucasians). Allele 'a' was that most commonly found for HPA-1 to 5 in both groups. The HPA-15ab genotype predominated over homozygous genotypes of this system. Fisher's exact test revealed statistically significant differences for the HPA-5 system, with a greater prevalence of the HPA-5b allele in non-Caucasians. The neighbour-joining method and principal components analysis revealed genetic proximity between our Caucasian group and European populations. We conclude that the allele frequencies of HPA-1 to 5 and HPA-15 found in our Caucasian sample are similar to those reported for European populations. These findings corroborate the ethnic makeup of the population of RS. The higher frequency of the HPA-5b allele found in the non-Caucasian group of our sample suggests the possibility of allosensitization in patients who receive platelet transfusions from genetically incompatible donors.

  8. Assessment of quality of platelets preserved in plasma and platelet additive solution: A Malaysian experience

    Directory of Open Access Journals (Sweden)

    Munirah Binti Mokhtar

    2016-01-01

    Full Text Available Background: A use of platelet additives solution (PAS improves storage conditions so as to give increased shelf life to platelets and to maintain hemostatic function. Objective: The present study was aimed to compare in vitro quality of platelet rich plasma (PRP-derived platelet concentrate (PC during extended period of storage in plasma and in additive solution (Composol PS and Fresenius. Study Design: Randomized 19 PCs each were used in the study for plasma and PAS as the storage medium. The measurement parameters, including pH, total white blood cell (WBC count, total platelet count, and platelet activation rate, were studied on day 1, day 5, and day 8 of the storage period. The sterility test was carried out on the eighth day of storage. Results: pH of PC suspended in PAS was significantly lower as compared to that in plasma (P < 0.001 for all the three days of sampling. The WBC count, both in plasma and in PAS, showed an acceptable values of being <0.2 Χ 10 9 /unit during the storage period. Platelet count in PAS was higher as compared to that in plasma, though it was not statistically significant. While both the groups showed increased platelet activation rate during the storage, the PCs suspended in PAS showed significantly higher platelet activation rate (p0.001. Results from sterility test showed no bacterial growth in the PCs in both the groups. Conclusion: Most parameters studied on platelet storage in suspending medium of native plasma and PAS remained well within the acceptable limits. However, the pH values and platelet activation rate significantly differed in PAS as compared with plasma.

  9. The critical roles of cyclic AMP/cyclic AMP-dependent protein kinase in platelet physiology

    Institute of Scientific and Technical Information of China (English)

    Rong YAN; Suping LI; Kesheng DAI

    2009-01-01

    Platelets are the primary players in both thrombosis and hemostasis.Cyclic AMP (cAMP) and cAMP-dependent protein kinase (PKA) are important signaling molecules in the regulation of platelet function,such as adhesion,aggregation,and secretion.Elevation of intracellular cAMP,which induces the activation of PKA,results in the inhibition of platelet function.Thus,tight control of the intracellular cAMP/PKA signaling pathway has great implications for platelet-dependent hemostasis and effective cardiovascular therapy.In this review,we summarize the PKA substrates and their contributions to platelet function,especially the advancing understanding of the cAMP/PKA-dependent signaling pathway in platelet physiology.In addition,we suggest the possibility that cAMP/PKA is involved in the platelet procoagulant process and receptor ectodomain shedding.

  10. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets.

    Science.gov (United States)

    Etulain, Julia; Negrotto, Soledad; Carestia, Agostina; Pozner, Roberto Gabriel; Romaniuk, María Albertina; D'Atri, Lina Paola; Klement, Giannoula Lakka; Schattner, Mirta

    2012-01-01

    Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.

  11. Adhesive Categories

    DEFF Research Database (Denmark)

    Lack, Stephen; Sobocinski, Pawel

    2004-01-01

    We introduce adhesive categories, which are categories with structure ensuring that pushouts along monomorphisms are well-behaved. Many types of graphical structures used in computer science are shown to be examples of adhesive categories. Double-pushout graph rewriting generalises well to rewrit...

  12. Platelet Content of Nitric Oxide Synthase 3 Phosphorylated At Serine1177 Is Associated with the Functional Response of Platelets to Aspirin

    Science.gov (United States)

    Modrego, Javier; Azcona, Luis; Martín-Palacios, Naiara; Zamorano-León, José J.; Segura, Antonio; Rodríguez, Pablo; Guerra, Reddy; Tamargo, Juan; Macaya, Carlos; López-Farré, Antonio J.

    2013-01-01

    Objective To analyse if platelet responsiveness to aspirin (ASA) may be associated with a different ability of platelets to generate nitric oxide (NO). Patients/Methods Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26) and ASA-resistant (n = 24) using a platelet functionality test (PFA-100). Results ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate) than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3) was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2) isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position −786 (T−786→C) in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser)1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018) of NOS3 phosphorylation at Ser1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. Conclusions Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser1177. PMID:24376548

  13. Platelet content of nitric oxide synthase 3 phosphorylated at Serine 1177 is associated with the functional response of platelets to aspirin.

    Directory of Open Access Journals (Sweden)

    Javier Modrego

    Full Text Available OBJECTIVE: To analyse if platelet responsiveness to aspirin (ASA may be associated with a different ability of platelets to generate nitric oxide (NO. PATIENTS/METHODS: Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26 and ASA-resistant (n = 24 using a platelet functionality test (PFA-100. RESULTS: ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3 was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2 isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position -786 (T(-786 → C in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser(1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser(1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018 of NOS3 phosphorylation at Ser(1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser(1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. CONCLUSIONS: Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser(1177.

  14. Activation of haem-oxidized soluble guanylyl cyclase with BAY 60-2770 in human platelets lead to overstimulation of the cyclic GMP signaling pathway.

    Directory of Open Access Journals (Sweden)

    Camila B Mendes-Silverio

    Full Text Available BACKGROUND AND AIMS: Nitric oxide-independent soluble guanylyl cyclase (sGC activators reactivate the haem-oxidized enzyme in vascular diseases. This study was undertaken to investigate the anti-platelet mechanisms of the haem-independent sGC activator BAY 60-2770 in human washed platelets. The hypothesis that sGC oxidation potentiates the anti-platelet activities of BAY 60-2770 has been tested. METHODS: Human washed platelet aggregation and adhesion assays, as well as flow cytometry for α(IIbβ(3 integrin activation and Western blot for α1 and β1 sGC subunits were performed. Intracellular calcium levels were monitored in platelets loaded with a fluorogenic calcium-binding dye (FluoForte. RESULTS: BAY 60-2770 (0.001-10 µM produced significant inhibition of collagen (2 µg/ml- and thrombin (0.1 U/ml-induced platelet aggregation that was markedly potentiated by the sGC inhibitor ODQ (10 µM. In fibrinogen-coated plates, BAY 60-2770 significantly inhibited platelet adhesion, an effect potentiated by ODQ. BAY 60-2770 increased the cGMP levels and reduced the intracellular Ca(2+ levels, both of which were potentiated by ODQ. The cell-permeable cGMP analogue 8-Br-cGMP (100 µM inhibited platelet aggregation and Ca(2+ levels in an ODQ-insensitive manner. The cAMP levels remained unchanged by BAY 60-2770. Collagen- and thrombin-induced α(IIbβ(3 activation was markedly inhibited by BAY 60-2770 that was further inhibited by ODQ. The effects of sodium nitroprusside (3 µM were all prevented by ODQ. Incubation with ODQ (10 µM significantly reduced the protein levels of α1 and β1 sGC subunits, which were prevented by BAY 60-2770. CONCLUSION: The inhibitory effects of BAY 60-2770 on aggregation, adhesion, intracellular Ca(2+ levels and α(IIbβ(3 activation are all potentiated in haem-oxidizing conditions. BAY 60-2770 prevents ODQ-induced decrease in sGC protein levels. BAY 60-2770 could be of therapeutic interest in cardiovascular diseases

  15. Study on the effect of platelet rich fibrin on the growth, production of acid and adhesion of Streptococcus%富血小板纤维蛋白对变形链球菌影响的研究

    Institute of Scientific and Technical Information of China (English)

    齐鹏鹏; 王景云; 孟粼; 于士洋; 李雨珊; 王红红

    2016-01-01

    目的 研究富血小板纤维蛋白(platelet-rich ibrin,PRF)对变形链球菌生长、产酸和粘附的影响.方法 选用变形链球菌标准菌株UA 159,制备PRF膜片及PRF浸出液(Platelet-rich fibrin extract,PRFe),将变形链球菌标准菌株UA159菌悬液接种于含有不同数量PRF膜片的BHI液体培养基中,培养48小时后,观察PRF对变形链球茵生长、产酸影响;用含有不同浓度PRF浸出液的BHI培养液培养变形链球菌48小时后,观察PRF对变形链球菌粘附性的影响.结果 PRF对UA159生长、产酸和粘附均有抑制作用,且随着PRF膜片数量的增加或PRF浸出液浓度的增高抑制作用逐渐增强.结论 PRF能抑制变形链球茵生长、产酸和粘附,并且随着PRF膜片量数的增加或PRF浸出液浓度的增高,抑制作用增强.

  16. Haemostatic role of intermediate filaments in adhered platelets: importance of the membranous system stability.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Mondragón, Ricardo; Mondragón, Mónica; González, Sirenia; Galván, Iván J

    2013-09-01

    The role of platelets in coagulation and the haemostatic process was initially suggested two centuries ago, and under appropriate physiological stimuli, these undergo abrupt morphological changes, attaching and spreading on damaged endothelium, preventing bleeding. During the adhesion process, platelet cytoskeleton reorganizes generating compartments in which actin filaments, microtubules, and associated proteins are arranged in characteristic patterns mediating crucial events, such as centralization of their organelles, secretion of granule contents, aggregation with one another to form a haemostatic plug, and retraction of these aggregates. However, the role of Intermediate filaments during the platelet adhesion process has not been explored. J. Cell. Biochem. 114: 2050-2060, 2013. © 2013 Wiley Periodicals, Inc.

  17. Pooled platelet concentrates: an alternative to single donor apheresis platelets?

    Science.gov (United States)

    Pietersz, R N I

    2009-10-01

    Three types of platelet concentrates (PC) are compared: PC either processed with the platelet-rich plasma (PRP) or the Buffy coat (BC) method from whole blood units and PC obtained by apheresis. Leuko-reduction (LR) pre-storage is advocated to improve quality of the PC during storage and reduce adverse reactions in recipients. Standardization of methods allow preparation of PC with comparable yields of approximately 400 x 10(9) platelets in pooled non-LR-PRP, approximately 370 x 10(9) in pooled LR-BC-PC and in LR apheresis PC the number of platelets can be targeted on 350 x 10(9) or more with devices of various manufacturers. While viral transmission can be prevented by outstanding laboratory tests, the risk of bacterial contamination should be reduced by improved arm disinfection, deviation of the first 20-30 ml of blood and culture or rapid detection assays of the PC pre-issue. In a large prospective multicenter trial no significant difference was observed between cultures of apheresis PC (n = 15,198): 0.09% confirmed positive units versus 0.06% in pooled BC-PC (n = 37,045), respectively. Though platelet activation as measured by CD62 expression may differ in vitro in PC obtained with various apheresis equipment, and also between PC processed with the two whole blood methods there is scarce literature about the clinical impact of these findings. In conclusion the final products of LR-PC derived from whole blood or obtained by apheresis can be comparable, provided the critical steps of the processing method are identified and covered and the process is in control.

  18. Mechanobiology of Platelets: Techniques to Study the Role of Fluid Flow and Platelet Retraction Forces at the Micro- and Nano-Scale

    Directory of Open Access Journals (Sweden)

    Nathan J. Sniadecki

    2011-12-01

    Full Text Available Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.

  19. Mechanobiology of platelets: techniques to study the role of fluid flow and platelet retraction forces at the micro- and nano-scale.

    Science.gov (United States)

    Feghhi, Shirin; Sniadecki, Nathan J

    2011-01-01

    Coagulation involves a complex set of events that are important in maintaining hemostasis. Biochemical interactions are classically known to regulate the hemostatic process, but recent evidence has revealed that mechanical interactions between platelets and their surroundings can also play a substantial role. Investigations into platelet mechanobiology have been challenging however, due to the small dimensions of platelets and their glycoprotein receptors. Platelet researchers have recently turned to microfabricated devices to control these physical, nanometer-scale interactions with a higher degree of precision. These approaches have enabled exciting, new insights into the molecular and biomechanical factors that affect platelets in clot formation. In this review, we highlight the new tools used to understand platelet mechanobiology and the roles of adhesion, shear flow, and retraction forces in clot formation.

  20. Pathogen-Reduced, Platelet Additive Solution, Extended Stored Platelets (PREPS)

    Science.gov (United States)

    2015-10-01

    associated sepsis remains the principal lethal risk associated with platelet transfusion. Cold storage (4°C) is known to reduce post transfusion...and no residual radiation is detectable . *P-selectin samples will be prepped on end of storage day and batch tested. **Bacterial Culture sample...temperature controlled room until such time as they have no detectable residual radiation. This is generally about 3-4 months. At that point they are

  1. Skin regeneration stimulation: the role of PCL-platelet gel nanofibrous scaffold.

    Science.gov (United States)

    Ranjbarvan, Parviz; Soleimani, Masoud; Samadi Kuchaksaraei, Ali; Ai, Jafar; Faridi Majidi, Reza; Verdi, Javad

    2017-05-01

    Skin is the largest organ of the human body. Thus far, tissue engineering of skin has developed rapidly and has used many types of growth factors and nanofibrous scaffolds. In this study, we differentiated neonate keratinocytes for epithelialization on the polycaprolactone-Platelet gel (PCL-PG) scaffold. Fabricated PCL nanofibers prepared by electrospinning technology and coated by platelet gel. Subsequently, the structure of the scaffold was evaluated by SEM, FTIR-ATR, contact angle and tensile test assays. After seeding the neonate keratinocytes on neat PCL and PCL-PG scaffolds, the epidermal maturation was tested by detecting cytokeratin 10 and loricrin determinants by immunocytochemistry; moreover, keratinocyte genes such as keratin 14, keratin 10, and Involucrin were investigated by real-time PCR. The results of MTT assay indicated an increase in cell viability and cell proliferation of neonate keratinocytes on PCL-PG nanofiber scaffolds compared with PCL. RT-PCR and immunocytochemical analysis showed better cell differentiation on the PCL-PG scaffolds than neat PCL. Furthermore, SEM microscopy images demonstrated that neo-keratinocytes enhance adhesion and proliferation on PCL-PG nanofiber scaffolds. We found that PG increases biocompatibility and wettability of scaffold, cell adhesion, and expression of keratinocyte markers. Overall, this procedure is recommended to be employed in skin tissue engineering and wounds healing. © 2016 Wiley Periodicals, Inc.

  2. β1 integrin-mediated signals are required for platelet granule secretion and hemostasis in mouse.

    Science.gov (United States)

    Petzold, Tobias; Ruppert, Raphael; Pandey, Dharmendra; Barocke, Verena; Meyer, Hannelore; Lorenz, Michael; Zhang, Lin; Siess, Wolfgang; Massberg, Steffen; Moser, Markus

    2013-10-10

    Integrins are critical for platelet adhesion and aggregation during arterial thrombosis and hemostasis. Although the platelet-specific αIIbβ3 integrin is known to be crucial for these processes, the in vivo role of β1 integrins is a matter of debate. Here we demonstrate that mice expressing reduced levels of β1 integrins or an activation-deficient β1 integrin show strongly reduced platelet adhesion to collagen in vitro and in a carotis ligation model in vivo. Interestingly, hypomorphic mice expressing only 3% of β1 integrins on platelets show normal bleeding times despite reduced platelet adhesion. The residual 3% of β1 integrins are able to trigger intracellular signals driving Rac-1-dependent granule release required for platelet aggregation and hemostasis. Our findings support a model, in which platelet β1 integrins serve as an important signaling receptor rather than an adhesion receptor in vivo and therefore promote β1 integrins as a promising and so far clinically unemployed antithrombotic target.

  3. Utrophins compensate for Dp71 absence in mdx3cv in adhered platelets.

    Science.gov (United States)

    Cerecedo, Doris; Mondragón, Ricardo; Candelario, Aurora; García-Sierra, Francisco; Mornet, Dominique; Rendón, Alvaro; Martínez-Rojas, Dalila

    2008-01-01

    Platelet adhesion is a critical step due to its hemostatic role in stopping bleeding after vascular damage. Short dystrophins are the most abundant dmd gene products in nonmuscle tissues, and in association with cytoskeleton proteins contribute to their intrinsic function; while utrophins are dystrophin-homologous related family proteins with structural and functional similarities. We previously demonstrated the presence of Dp71 isoforms, utrophins, and various dystrophin-associated proteins and their participation in cytoskeleton re-organization, filopodia and lamellipodia extension, and in centralizing cytoplasmic granules during the adhesion process of human platelets. To evaluate the morphologic changes and actin-based structures of mdx(3cv) platelets during the adhesion process, we compared the topographic distribution of Dp71d/Dp71Delta110(m) and dystrophin-associated protein in adhered platelets from dystrophic mdx(3cv) mouse. By confocal microscopy, we showed that absence of Dp71 isoforms in platelets from this animal model disrupted dystrophin-associated protein expression and distribution without modifying the platelet morphology displayed during the glass-adhesion process. By immunoprecipitation assays, we proved that up-regulated utrophins were associated with dystrophin-associated proteins to conform the dystrophin-associated protein complex corresponding to utrophins, which might compensate for Dp71 absence in mdx(3cv) platelets.

  4. Leukocyte accumulation promoting fibrin deposition is mediated in vivo by P-selectin on adherent platelets

    Science.gov (United States)

    Palabrica, Theresa; Lobb, Roy; Furie, Barbara C.; Aronovitz, Mark; Benjamin, Christopher; Hsu, Yen-Ming; Sajer, Susan A.; Furie, Bruce

    1992-10-01

    THE glycoprotein P-selectin is a cell adhesion molecule of stimulated platelets and endothelial cells, which mediates the interaction of these cells with neutrophils and monocytes1,2. It is a membrane component of cell storage granules3-6, and is a member of the selectin family which includes E-selectin and L-selectin7,8. P-selectin recognizes both lineage-specific carbohydrate ligands on monocytes and neutrophils, including the Lewis x antigen, sialic acid, and a protein component9-12. In inflammation and thrombosis, P-selectin may mediate the interaction of leukocytes with platelets bound in the region of tissue injury and with stimulated endothelium1,2. To evaluate the role of P-selectin in platelet-leukocyte adhesion in vivo, the accumulation of leukocytes within an experimental thrombus was explored in an arteriovenous shunt model in baboons13. A Dacron graft implanted within an arteriovenous shunt is thrombogenic, accumulating platelets and fibrin within its lumen. These bound platelets express P-selectin14. Here we show that antibody inhibition of leukocyte binding to P-selectin expressed on platelets immobilized on the graft blocks leukocyte accumulation and inhibits the deposition of fibrin within the thrombus. These results indicate that P-selectin is an important adhesion molecule on platelets, mediating platelet-leukocyte binding in vivo, that the presence of leukocytes in thrombi is mediated by P-selectin, and that these leukocytes promote fibrin deposition.

  5. A novel role for the fibrinogen Asn-Gly-Arg (NGR) motif in platelet function.

    Science.gov (United States)

    Moriarty, Róisín; McManus, Ciara A; Lambert, Matthew; Tilley, Thea; Devocelle, Marc; Brennan, Marian; Kerrigan, Steven W; Cox, Dermot

    2015-02-01

    The integrin αIIbβ3 on resting platelets can bind to immobilised fibrinogen resulting in platelet spreading and activation but requires activation to bind to soluble fibrinogen. αIIbβ3 is known to interact with the general integrin-recognition motif RGD (arginine-glycine-aspartate) as well as the fibrinogen-specific γ-chain dodecapeptide; however, it is not known how fibrinogen binding triggers platelet activation. NGR (asparagine-glycine-arginine) is another integrin-recognition sequence present in fibrinogen and this study aims to determine if it plays a role in the interaction between fibrinogen and αIIbβ3. NGR-containing peptides inhibited resting platelet adhesion to fibrinogen with an IC50 of 175 µM but failed to inhibit the adhesion of activated platelets to fibrinogen (IC50> 500 µM). Resting platelet adhesion to mutant fibrinogens lacking the NGR sequences was reduced compared to normal fibrinogen under both static and shear conditions (200 s⁻¹). However, pre-activated platelets were able to fully spread on all types of fibrinogen. Thus, the NGR motif in fibrinogen is the site that is primarily responsible for the interaction with resting αIIbβ3 and is responsible for triggering platelet activation.

  6. 水性胶粘剂中丙烯酰胺单体含量的测定%Testing acrylamide monomer contents in waterborne adhesives

    Institute of Scientific and Technical Information of China (English)

    孙行; 戴双燕

    2012-01-01

    To establish testing method for remaining AM (acrylamide) monomer in waterborne adhesives, namely , the AM monomer contents in extracted sample were tested by capillary column separation method, GC-FID(gas chromatography-hydrogen flameionization detector) method when the trichloromethane as good solvent could effectively extracte AM monomer in waterborne adhesives samples. The results showed that the reproducibility of testing AM contents in waterborne adhesive was good by above methods because its relative standard deviation was 0.3-2.8 mg/L when the concentration of standard sample was 5.0-80.0 mg/L. With construction-adhesive and white latex as example,the results of testing AM contents in adhesive samples by above methods were more reliable because the recovery rates of two samples(added between 93%—107%) were all good.%建立了水性胶粘剂口残留AM(丙烯酰胺)单体的检测方法,即首先利用良溶剂三氯甲烷有效提取水性胶粘剂样品中的AM单体,然后采用毛细管柱分离法、GC-FID(气相色谱-氢火焰离子化检测)法测定提出液中的AM含量.结果表明:当标准样品的浓度为5.0~80.0mg/L时,采用上述方法测定水性胶粘剂中AM含量时,其重复性良好(相对标准偏差为0.3~2.8mg/L);以某厂生产的建筑胶粘剂和白胶为例,采用上述方法测定胶样中的AM含量,两者的加标回收率为93%~107%,说明两种样品的回收率良好,其测试结果较为可靠.

  7. Hybrid transparent conductive electrodes with copper nanowires embedded in a zinc oxide matrix and protected by reduced graphene oxide platelets

    Science.gov (United States)

    Zhu, Zhaozhao; Mankowski, Trent; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine A.; Mansuripur, Masud; Falco, Charles M.

    2016-02-01

    Transparent conductive electrodes (TCE) were fabricated by combining three emerging nano-materials: copper nanowires (CuNWs), zinc oxide (ZnO) nano-particulate thin films, and reduced graphene oxide (rGO) platelets. Whereas CuNWs are responsible for essentially all of the electrical conductivity of our thin-film TCEs, the ZnO matrix embeds and strengthens the CuNW network in its adhesion to the substrate, while the rGO platelets provide a protective overcoat for the composite electrode, thereby improving its stability in hot and humid environments. Our CuNW/ZnO/rGO hybrid electrodes deposited on glass substrates have low sheet resistance (Rs ˜ 20 Ω/sq) and fairly high optical transmittance (T550 ˜ 79%). In addition, our hybrid TCEs are mechanically strong and able to withstand multiple scotch-tape peel tests. Finally, these TCEs can be fabricated on rigid glass as well as flexible plastic substrates.

  8. A model-based analysis of the clinical and economic impact of personalising P2Y12-receptor inhibition with platelet function testing in acute coronary syndrome patients.

    Science.gov (United States)

    Straub, Niels; Beivers, Andreas; Lenk, Ekaterina; Aradi, Daniel; Sibbing, Dirk

    2014-02-01

    Although some observational studies reported that the measured level of P2Y12-inhibition is predictive for thrombotic events, the clinical and economic benefit of incorporating PFT to personalize P2Y12-receptor directed antiplatelet treatment is unknown. Here, we assessed the clinical impact and cost-effectiveness of selecting P2Y12-inhibitors based on platelet function testing (PFT) in acute coronary syndrome (ACS) patients undergoing PCI. A decision model was developed to analyse the health economic effects of different strategies. PFT-guided treatment was compared with the three options of general clopidogrel, prasugrel or ticagrelor treatment. In the PFT arm, low responders to clopidogrel received prasugrel, while normal responders carried on with clopidogrel. The associated endpoints in the model were cardiovascular death, stent thrombosis and major bleeding. With a simulated cohort of 10,000 patients treated for one year, there were 93 less events in the PFT arm compared to general clopidogrel. In prasugrel and ticagrelor arms, 110 and 86 events were prevented compared to clopidogrel treatment, respectively. The total expected costs (including event costs, drug costs and PFT costs) for generic clopidogrel therapy were US$ 1,059/patient. In the PFT arm, total costs were US$ 1,494, while in the prasugrel and ticagrelor branches they were US$ 3,102 and US$ 3,771, respectively. The incremental-cost-effectiveness-ratio (ICER) was US$ 46,770 for PFT-guided therapy, US$ 185,783 for prasugrel and US$ 315,360 for ticagrelor. In this model-based analysis, a PFT-guided therapy may have fewer adverse outcomes than general treatment with clopidogrel and may be more cost-effective than prasugrel or ticagrelor treatment in ACS patients undergoing PCI.

  9. Influence of chirality on catalytic generation of nitric oxide and platelet behavior on selenocystine immobilized TiO2 films.

    Science.gov (United States)

    Fan, Yonghong; Pan, Xiaxin; Wang, Ke; Wu, Sisi; Han, Honghong; Yang, Ping; Luo, Rifang; Wang, Hong; Huang, Nan; Tan, Wei; Weng, Yajun

    2016-09-01

    As nitric oxide (NO) plays vital roles in the cardiovascular system, incorporating this molecule into cardiovascular stents is considered as an effective method. In the present study, selenocystine with different chirality (i.e., l- and d-selenocystine) was used as the catalytic molecule immobilized on TiO2 films for decomposing endogenous NO donor. The influences of surface chirality on NO release and platelet behavior were evaluated. Results show that although the amount of immobilized l-selenocystine on the surface was nearly the same as that of immobilized d-selenocystine, in vitro catalytic NO release tests showed that l-selenocystine immobilized surfaces were more capable of catalyzing the decomposition of S-nitrosoglutathione and thus generating more NO. Accordingly, l-selenocystine immobilized surfaces demonstrated significantly increased inhibiting effects on the platelet adhesion and activation, when compared to d-selenocystine immobilized ones. Measurement of the cGMP concentration of platelets further confirmed that surface chirality played an important role in regulating NO generation and platelet behaviors. Additionally, using bovine serum albumin and fibrinogen as model proteins, the protein adsorption determined with quartz crystal microbalance showed that the l-selenocystine immobilized surface enhanced protein adsorption. In conclusion, surface chirality significantly influences protein adsorption and NO release, which may have significant implications in the design of NO-generating cardiovascular stents.

  10. Nucleation of platelets with blood-borne pathogens on Kupffer cells precedes other innate immunity and contributes to bacterial clearance.

    Science.gov (United States)

    Wong, Connie H Y; Jenne, Craig N; Petri, Björn; Chrobok, Navina L; Kubes, Paul

    2013-08-01

    Through the use of intravital imaging of the liver, we demonstrate a collaborative role for platelets with Kupffer cells (KCs) in eradicating blood-borne bacterial infection. Under basal conditions, platelets, via the platelet-adhesion receptor GPIb, formed transient 'touch-and-go' interactions with von Willebrand factor (vWF) constitutively expressed on KCs. Bacteria such as Bacillus cereus and methicillin-resistant Staphylococcus aureus (MRSA) were rapidly caught by KCs and triggered platelets to switch from 'touch-and-go' adhesion to sustained GPIIb-mediated adhesion on the KC surface to encase the bacterium. Infected GPIbα-deficient mice had more endothelial and KC damage than did their wild-type counterparts, which led to more fluid leakage, substantial polycythemia and rapid mortality. Our study identifies a previously unknown surveillance mechanism by which platelets survey macrophages that rapidly converts to a critical host response to blood-borne bacteria.

  11. Thioredoxin Inhibitors Attenuate Platelet Function and Thrombus Formation

    Science.gov (United States)

    Metcalfe, Clive; Ramasubramoni, Anjana; Pula, Giordano; Harper, Matthew T.; Mundell, Stuart J.; Coxon, Carmen H.

    2016-01-01

    Thioredoxin (Trx) is an oxidoreductase with important physiological function. Imbalances in the NADPH/thioredoxin reductase/thioredoxin system are associated with a number of pathologies, particularly cancer, and a number of clinical trials for thioredoxin and thioredoxin reductase inhibitors have been carried out or are underway. Due to the emerging role and importance of oxidoreductases for haemostasis and the current interest in developing inhibitors for clinical use, we thought it pertinent to assess whether inhibition of the NADPH/thioredoxin reductase/thioredoxin system affects platelet function and thrombosis. We used small molecule inhibitors of Trx (PMX 464 and PX-12) to determine whether Trx activity influences platelet function, as well as an unbiased proteomics approach to identify potential Trx substrates on the surface of platelets that might contribute to platelet reactivity and function. Using LC-MS/MS we found that PMX 464 and PX-12 affected the oxidation state of thiols in a number of cell surface proteins. Key surface receptors for platelet adhesion and activation were affected, including the collagen receptor GPVI and the von Willebrand factor receptor, GPIb. To experimentally validate these findings we assessed platelet function in the presence of PMX 464, PX-12, and rutin (a selective inhibitor of the related protein disulphide isomerase). In agreement with the proteomics data, small molecule inhibitors of thioredoxin selectively inhibited GPVI-mediated platelet activation, and attenuated ristocetin-induced GPIb-vWF-mediated platelet agglutination, thus validating the findings of the proteomics study. These data reveal a novel role for thioredoxin in regulating platelet reactivity via proteins required for early platelet responses at sites of vessel injury (GPVI and GPIb). This work also highlights a potential opportunity for repurposing of PMX 464 and PX-12 as antiplatelet agents. PMID:27716777

  12. Platelet alloimmunization after transfusion

    DEFF Research Database (Denmark)

    Taaning, E; Simonsen, A C; Hjelms, E;

    1997-01-01

    BACKGROUND AND OBJECTIVES: The frequency of platelet-specific antibodies after one series of blood transfusions has not been reported, and in multiply transfused patients is controversial. MATERIALS AND METHODS: We studied the frequency of alloimmunization against platelet antigens in 117 patient...

  13. Flavanols and Platelet Reactivity

    Directory of Open Access Journals (Sweden)

    Debra A. Pearson

    2005-01-01

    Full Text Available Platelet activity and platelet-endothelial cell interactions are important in the acute development of thrombosis, as well as in the pathogenesis of cardiovascular disease. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of flavanol-rich foods, including, grape juice, cocoa and chocolate, suggests that these foods may provide some protection against thrombosis. In the present report, we review a series of in vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa inhibited several measures of platelet activity including, epinephrine- and ADP-induced glycoprotein (GP IIb/IIIa and P-Selectin expression, platelet microparticle formation, and epinephrine-collagen and ADP-collagen induced primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and primary hemostasis were similar to, though less robust than those associated with the use of low dose (81 mg aspirin. These data, coupled with information from other studies, support the concept that flavanols present in cocoa and chocolate can modulate platelet function through a multitude of pathways.

  14. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  15. Gasotransmitters and platelets.

    Science.gov (United States)

    Truss, Nicola J; Warner, Timothy D

    2011-11-01

    Platelets are essential to prevent blood loss and promote wound healing. Their activation comprises of several complex steps which are regulated by a range of mediators. Over the last few decades there has been intense interest in a group of gaseous mediators known as gasotransmitters; currently comprising nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S). Here we consider the action of gasotransmitters on platelet activity. NO is a well established platelet inhibitor which mediates its effects predominantly through activation of soluble guanylyl cyclase leading to a decrease in intraplatelet calcium. More recently CO has been identified as a gasotransmitter with inhibitory actions on platelets; CO acts through the same mechanism as NO but is less potent. The in vivo and platelet functions of the most recently identified gasotransmitter, H(2)S, are still the subject of investigations, but they appear generally inhibitory. Whilst there is evidence for the individual action of these mediators, it is also likely that combinations of these mediators are more relevant regulators of platelets. Furthermore, current evidence suggests that these mediators in combination alter the production of each other, and so modify the circulating levels of gasotransmitters. The use of gasotransmitters as therapeutic agents is also being explored for a range of indications. In conclusion, the importance of NO in the regulation of vascular tone and platelet activity has long been understood. Other gasotransmitters are now establishing themselves as mediators of vascular tone, and recent evidence suggests that these other gasotransmitters may also modulate platelet function.

  16. 根据生物学变异度确定血液学检测下限的研究%Use biological variation to value the lower detect limit of hematology and platelet aggregation test

    Institute of Scientific and Technical Information of China (English)

    吴俊; 赵洁; 宋英; 赵磊; 赵京忠

    2013-01-01

    目的 确定血常规分析,血小板聚集检验最低检测下限范围.方法 Sysmex2100血液分析仪检测血常规,将标本倍比稀释后重复检测10次样本,计算变异系数CV值,做曲线及计算方程,以1/2生物变异度规定为允许CV值,该CV值代入方程为检测低限.对于血小板聚集,稀释后检测血小板聚集,在低于平台区的范围定位检测下限.结果 白细胞检测下限为0.11×109/l,红细胞检测下限为0.14×1012/l,红细胞压积检测下限3.03%,血小板检测下限为15.31×109/l.血小板聚集需要最低的血小板数量为200×109/l.结论 以生物变异度为基础的CV来确认仪器检测下限,方法可行,且与临床实际情况相符合.可作为确定仪器检测下限的方法.%Objective To detect the lower limit of hematology,platelet aggregation. Methods we use sysmex 2100 hematology analyzer blood cell account;Chrono-log platelet function instrument test platelet aggregation rate. After di luting samples,we retest the sample 10 times, plot X-axis with concentration, Y-axis with CV%, calculated the equa tion. We set 1/2 biological variation as standard CV to get the lower limit of detection. As for platelet aggregation, the concentration below the plateau is the lower limit concentration. Results Low limit detection of white blood cell, red blood cell,hematocrit,platelet is 0.11 ×109/1,0.14 × 1012/1,3.03% ,15.31 × 109/1, respectivly. The low concentration of platelet aggregation is 200×109/1. Conclusion Use biological variation to set the lower limit of detection is practica ble. It fit with clinical situation. The 1/2 biological variation could be the standard of lower limit of detection evaluation.

  17. Mapuche herbal medicine inhibits blood platelet aggregation.

    Science.gov (United States)

    Falkenberg, Susan Skanderup; Tarnow, Inge; Guzman, Alfonso; Mølgaard, Per; Simonsen, Henrik Toft

    2012-01-01

    12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM) and collagen- (2.0 μg/mL) induced aggregations in human blood. These four species in respective extracts (in brackets) were Blechnum chilense (MeOH), Luma apiculata (H(2)O), Amomyrtus luma (DCM : MeOH 1 : 1) and Cestrum parqui (DCM : MeOH 1 : 1). The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1), and L. apiculata (H(2)O) were substantial and confirmed by inhibition of platelet surface activation markers.

  18. Mapuche Herbal Medicine Inhibits Blood Platelet Aggregation

    Directory of Open Access Journals (Sweden)

    Susan Skanderup Falkenberg

    2012-01-01

    Full Text Available 12 plant species traditionally used by the Mapuche people in Chile to treat wounds and inflammations have been evaluated for their direct blood platelet inhibition. Seven of the 12 tested plant species showed platelet inhibitory effect in sheep blood, and four of these were also able to inhibit the ADP- (5.0 μM and collagen- (2.0 μg/mL induced aggregations in human blood. These four species in respective extracts (in brackets were Blechnum chilense (MeOH, Luma apiculata (H2O, Amomyrtus luma (DCM : MeOH 1 : 1 and Cestrum parqui (DCM : MeOH 1 : 1. The platelet aggregating inhibitory effects of A. luma (DCM : MeOH 1 : 1, and L. apiculata (H2O were substantial and confirmed by inhibition of platelet surface activation markers.

  19. Effects of drugs on platelet function.

    Science.gov (United States)

    Morse, E E

    1977-01-01

    Numerous drugs and chemicals affect the function of human blood platelets. The mechanism of action of some medications is partly understood. Aspirin is the most frequently involved drug. It appears to interfere with the platelet release reaction by acetylation of a platelet membrane protein which may be involved in the synthesis of prostaglandins. Other anti-inflammatory drugs, including indomethacin, phenylbutazone, ibuprophen (Motrin) and clonixin, also interfere with the release reaction but have a shorter acting course than aspirin. Some drugs stimulate adenylcyclase (gliclazide) or block phosphodiesterase, (dipyridamole, caffeine) both of which actions lead to an increase in adenosine cyclic 3':5' monophosphate (cAMP) and decrease aggregation by adenosine diphosphate (ADP). These interactions should be known to clinical scientists since patients using these medicaments may manifest abnormal platelet function tests in the laboratory and mild hemorrhagic syndromes in the clinic.

  20. Alloimmune refractoriness to platelet transfusions.

    Science.gov (United States)

    Sandler, S G

    1997-11-01

    Patients who are transfused on multiple occasions with red cells or platelets may develop platelet-reactive alloantibodies and experience decreased clinical responsiveness to platelet transfusion. This situation, conventionally described as "refractoriness to platelet transfusions," is defined by an unsatisfactory low post-transfusion platelet count increment. If antibodies to HLAs are detected, improved clinical outcomes may result from transfusions of HLA-matched or donor-recipient cross-matched platelets. Because refractoriness is an expected, frequently occurring phenomenon, prevention of HLA alloimmunization is an important management strategy. Prevention strategies include efforts to decrease the number of transfusions, filtration of cellular components to reduce the number of HLA-bearing leukocytes, or pretransfusion ultraviolet B irradiation of cellular components to decrease their immunogenicity. Other investigational approaches include reducing the expression of HLAs on transfused platelets, inducing a transient reticuloendothelial system blockade by infusions of specialized immunoglobulin products, or transfusing semisynthetic platelet substitutes (thromboerythrocytes, thrombospheres) or modified platelets (infusible platelet membranes, lyophilized platelets).

  1. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.

    2007-01-01

    Cairn Terriers, 10 Boxers, and 11 Labrador Retrievers) were included in the study. Platelet function was assessed by whole-blood aggregation with ADP (1, 5, 10, and 20 µM) as agonist and by PFA-100 using collagen and epinephrine (Col + Epi) and Cpæ + ADP as agonists. Plasma thromboxane B2 concentration......Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...

  2. Cisplatin triggers platelet activation.

    Science.gov (United States)

    Togna, G I; Togna, A R; Franconi, M; Caprino, L

    2000-09-01

    Clinical observations suggest that anticancer drugs could contribute to the thrombotic complications of malignancy in treated patients. Thrombotic microangiopathy, myocardial infarction, and cerebrovascular thrombotic events have been reported for cisplatin, a drug widely used in the treatment of many solid tumours. The aim of this study is to explore in vitro cisplatin effect on human platelet reactivity in order to define the potentially active role of platelets in the pathogenesis of cisplatin-induced thrombotic complications. Our results demonstrate that cisplatin increases human platelet reactivity (onset of platelet aggregation wave and thromboxane production) to non-aggregating concentrations of the agonists involving arachidonic acid metabolism. Direct or indirect activation of platelet phospholipase A(2) appears to be implicated. This finding contributes to a better understanding of the pathogenesis of thrombotic complications occurring during cisplatin-based chemotherapy.

  3. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.

    2007-01-01

    Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...... applied. However, the importance of these breed differences remains to be investigated. The PFA-100 method with Col + Epi as agonists, and ADP-induced platelet aggregation appear to be sensitive to ASA in dogs....

  4. Development and First Results of the Width-Tapered Beam Method for Adhesion Testing of Photovoltaic Material Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bosco, Nick; Tracy, Jared; Dauskardt, Reinhold; Kurtz, Sarah

    2016-11-21

    A fracture mechanics based approach for quantifying adhesion at every interface within the PV module laminate is presented. The common requirements of monitoring crack length and specimen compliance are circumvented through development of a width-tapered cantilever beam method. This technique may be applied at both the module and coupon level to yield a similar, quantitative, measurement. Details of module and sample preparation are described and first results on field-exposed modules deployed for over 27 years presented.

  5. Platelet activation in the postoperative period after lung transplantation

    Science.gov (United States)

    Sternberg, David I.; Shimbo, Daichi; Kawut, Steven M.; Sarkar, Joydeep; Hurlitz, Georg; D’Ovidio, Frank; Lederer, David J.; Wilt, Jessie S.; Arcasoy, Selim M.; Pinsky, David J.; D’Armiento, Jeanine M.; Sonett, Joshua R.

    2010-01-01

    Objective During lung transplantation, cells in the pulmonary parenchyma are subjected to ischemia, hypothermic storage, and reperfusion injury. Platelets, whose granular contents include adhesion receptors, chemokines, and coactivating substances that activate inflammatory and coagulant cascades, likely play a critical role in the lung allograft response to ischemia and reperfusion. The platelet response to the pulmonary allograft, however, has never been studied. Here we report significant platelet activation immediately after lung transplantation. Methods We performed a prospective cohort study comparing markers of platelet activation in patients undergoing lung transplantation and patients undergoing nontransplant thoracotomy. Plasma levels of soluble P-selectin, soluble CD40 ligand, and platelet–leukocyte conjugates were measured before surgery, after skin closure, and at 6 postoperative hours. Results Both soluble P-selectin and soluble CD40 ligand levels increased significantly after lung transplantation but not after thoracotomy. Additionally, platelet–monocyte conjugate fluorescence was significantly higher after lung transplantation than after thoracotomy alone. Conclusion These findings suggest that platelet activation is significantly increased after lung transplantation beyond that expected from the postoperative state. The increase in circulating platelet–monocyte conjugates suggests an important interaction between platelets and inflammatory cells. Further research should examine whether platelet activation affects early graft function after lung transplantation. PMID:18329493

  6. Low-power laser irradiation of blood inhibits platelet function: role of cyclic GMP

    Science.gov (United States)

    Brill, Alexander G.; Brill, Gregory E.; Shenkman, Boris; Tamarin, Ilya; Dardik, Rima; Varon, David; Savion, Naphtali

    1998-12-01

    The aim of the present work was to investigate effect of low power laser irradiation (LPLI) on platelet function in vitro. He-Ne laser (Optronix, USA; (lambda) - 632.8 nm, output power - 7 mW) was employed. Platelet adhesion and aggregation in whole blood (WB) under defined shear conditions were assayed by a Cone and Plate(let) Analyzer. Platelet activation was evaluated by flow cytometry. Level of platelet cGMP was estimated by immunoenzyme assay. Experiments performed showed that LPLI of WB resulted in decrease of platelet deposition on extracellular matrix at high shear rate (1300 s-1). Similar results were obtained using surfaces precoated with either collagen type I or von Willebrand factor. LPLI inhibited fibrinogen binding as well as P-selectin expression on the platelet membrane, induced by thrombin analogue. It was found out that primary acceptor of laser energy responsible for the effect on platelets was located in platelets themselves and not in blood plasma or in other blood cells. LPLI of gel- filtered platelets resulted in increase of intracellular level of cGMP both in the absence and in presence of izobutylmethylxantine (phosphodiesterase inhibitor) suggesting stimulation of synthesis rather than destruction of cGMP under the influence of LPLI. It is suggested that guanylate cyclase and/or NO-synthase might serve as primary acceptors of He-Ne laser light in platelets.

  7. Platelet Hyperactivity in TNFSF14/LIGHT Knockout Mouse Model of Impaired Healing.

    Science.gov (United States)

    Dhall, Sandeep; Karim, Zubair A; Khasawneh, Fadi T; Martins-Green, Manuela

    2016-10-01

    Objective: Impaired and chronic wounds occur due to defects in one or more of the overlapping stages of healing. However, problems related to the vascular system are critical for nonhealing, and chronic wounds in humans often show the presence of fibrin cuffs/clots. We hypothesized that these clots are due to alterations in platelet function; hence, we have investigated whether alterations in platelet function are present during impaired healing. Approach: Platelets were subjected to different agonists to determine the rate of aggregation and evaluate the molecules involved in adhesion and aggregation that could lead to faster thrombosis and potentially contribute to impaired wound healing. Results: We show that wounding of TNFSF14/LIGHT(-/-) mice, which have impaired healing, leads to an enhanced response in platelet aggregation and a faster time to blood vessel occlusion (thrombosis). In addition, after wounding, platelets from these mice have increased levels of P-selectin, integrin αIIbβ3, and phosphatidylserine, molecules that contribute to platelet adhesion. They also have more extensive open canalicular system than platelets of control mice, suggesting increased surface area for interactions upon activation. Innovation: These results show a novel function for TNFSF14/LIGHT during wound healing. Conclusion: The absence of TNFSF14/LIGHT from the cell surface of platelets causes rapid platelet aggregation and thrombus formation that may contribute to impaired healing by reducing the ability of the blood vessels to transport nutrients and oxygen and other molecules needed for proper healing.

  8. Prostaglandin A1 inhibits increases in intracellular calcium concentration, TXA2 production and platelet activation

    Institute of Scientific and Technical Information of China (English)

    Yi ZHU; Zhen-lun GU; Zhong-qin LIANG; Hui-lin ZHANG; Zheng-hong QIN

    2006-01-01

    Aim: In our previous studies we found that cyclopentenane prostaglandin A1 (PGA1) had neuroprotective effects in a rodent ischemic model. In the present study we aimed to investigate the inhibitory effect of PGA1 on platelet function. Method: The rate of aggregation of human platelets was measured by using turbidimetry. The rate of adhesion of platelets to cultured endothelial cells was determined by using [3H]-adenine labeled platelets. 5-Hydroxytryptamine release from platelets was measured with O-phthaldialdehyde fluorospectrophotometry. The levels of TXB2, a stable metabolite of TXA2, were determined by radioimmunoassay. Alternations in platelet morphology were observed using an electron microscope, and the intraplatelet free calcium concentrations were measured with Fluo-3/AM FCM assay. Results: PGA1 significantly inhibited thrombin-collagen-and ADP-induced aggregation and adhesion of platelets. The morphological changes of platelets induced by thrombin were blocked by PGA1. PGA1 inhibited the release of 5-hydroxytyptamine from dense granules and the synthesis of TXA2. Conclusion: PGA1 inhibits the activation of platelets probably through blocking increases in intracellular calcium concentration and TXA2 synthesis.

  9. Preanalytical requirements for flow cytometric evaluation of platelet activation: choice of anticoagulant.

    Science.gov (United States)

    Mody, M; Lazarus, A H; Semple, J W; Freedman, J

    1999-06-01

    Accurate assessment of in vivo or in vitro platelet activation requires optimal preanalytical conditions to prevent artefactual in vitro activation of the platelets. The choice of anticoagulant is one of the critical preanalytical conditions as anticoagulants exert different effects on the activation of platelets ex vivo. We tested the effectiveness of Diatube-H (also known as CTAD; sodium citrate, theophylline, adenosine and dipyridamole) and citrate vacutainer tubes in preventing artefactual activation of platelets and preserving functional reserve. Platelet surface expression of the CD62P (reflecting alpha granule release), CD63 (reflecting lysosomal release) and modulation of normal platelet membrane glycoproteins CD41a and CD42b, were measured in whole blood and in isolated platelets immediately after collection and at 6, 24 and 48 h after venipuncture. Samples taken into Diatube-H showed less spontaneous platelet activation than did those taken into citrate. To measure in vitro platelet functional reserve, thrombin was added as agonist to blood stored for varying periods up to 48 h. Although Diatube-H suppressed in vitro platelet activation for up to 4 h, in samples kept for 6-24 h before thrombin addition, the inhibitory effect was lost and platelets responded fully to agonist activation. Hence, Diatube-H preserved platelets and allowed for measurement of in vivo platelet activation as well as thrombin-induced in vitro platelet activation after 6-24 h, in both whole blood and isolated platelets.

  10. Grafting of abciximab to a microbubble-based ultrasound contrast agent for targeting to platelets expressing GP IIb/IIIa - characterization and in vitro testing.

    Science.gov (United States)

    Della Martina, A; Allémann, E; Bettinger, T; Bussat, P; Lassus, A; Pochon, S; Schneider, M

    2008-03-01

    Abciximab-grafted ultrasound sensitive microbubbles were developed for the diagnosis of stroke. The antibody fragment abciximab, which binds to the GP IIb/IIIa and alpha v beta 3 receptors expressed by activated platelets, was chosen because most ischemic strokes are due to arterial thrombi that are mainly composed of platelets. The abciximab antibody fragment was activated by reduction of the disulfide bond for grafting on the microbubbles. The suspension was freeze-dried after the grafting was performed directly on the formed microbubbles. Quantification of the amounts of abciximab present on the surface of the microbubbles was assessed semi-quantitatively by flow cytometry, and quantitatively using radio-labeled abciximab. A protocol for human and rat platelets deposition and fixation was implemented and the expression of the GP IIb/IIIa receptor was validated by immunostaining. The abciximab-grafted microbubbles showed high static and dynamic binding to fixed platelets. Detection by ultrasonography of microbubbles bound on white and red clots gave higher signals compared to Sono Vue microbubbles.

  11. Patients with previous definite stent thrombosis have a larger fraction of immature platelets and a reduced antiplatelet effect of aspirin

    DEFF Research Database (Denmark)

    Würtz, Morten; Grove, Erik; Wulff, Lise Nielsen;

    turnover. Key Words: aspirin; immature platelets; platelet aggregation; platelet function tests; stent thrombosis Abbreviations: ARU, aspirin reaction units; AU, aggregation units; BMS, bare-metal stent(s); DES, drug-eluting stent(s); IPF, immature platelet fraction; MEA, multiple electrode aggregometry...

  12. Triplatin, a platelet aggregation inhibitor from the salivary gland of the triatomine vector of Chagas disease, binds to TXA(2) but does not interact with glycoprotein PVI.

    Science.gov (United States)

    Ma, Dongying; Assumpção, Teresa C F; Li, Yuan; Andersen, John F; Ribeiro, José; Francischetti, Ivo M B

    2012-01-01

    Salivary glands from haematophagous animals express a notable diversity of negative modulators of platelet function. Triplatin is an inhibitor of collagen-induced platelet aggregation which has been described as an antagonist of glycoprotein VI (GPVI). Because triplatin displays sequence homology to members of the lipocalin family of proteins, we investigated whether triplatin mechanism of action could be explained by interaction with pro-haemostatic prostaglandins. Our results demonstrate that triplatin inhibits platelet aggregation induced by low doses of collagen, thromboxane A2 (TXA(2)) mimetic (U46619), and arachidonic acid (AA). On the other hand, it does not inhibit platelet aggregation by convulxin, PMA, or low-dose ADP. Isothermal titration calorimetry (ITC) revealed that triplatin binds AA, cTXA(2), TXB(2), U46619 or prostaglandin (PG)H(2) mimetic (U51605). Consistent with its ligand specificity, triplatin induces relaxation of rat aorta contracted with U46619. Triplatin also interacts with PGF(2α) and PGJ(2), but not with leukotrienes, AA or biogenic amines. Surface plasmon resonance experiments failed to demonstrate interaction of triplatin with GPVI; it also did to inhibit platelet adhesion to fibrillar or soluble collagen. Because triplatin displays sequence similarity to apolipoprotein D (ApoD) - a lipocalin associated with high-density lipoprotein, ApoD was tested as a putative TXA(2)-binding molecule. ITC failed to demonstrate binding of ApoD to all prostanoids described above, or to AA. Furthermore, ApoD was devoid of inhibitory properties towards platelets activation by AA, collagen, or U46619. In conclusion, triplatin mechanism of action has been elucidated without ambiguity as a novel TXA(2)- and PGF(2α)- binding protein. It conceivably blocks platelet aggregation and vasoconstriction, thus contributing to successful blood feeding at the vector-host interface.

  13. Platelet Rich Plasma and Knee Surgery

    Directory of Open Access Journals (Sweden)

    Mikel Sánchez

    2014-01-01

    Full Text Available In orthopaedic surgery and sports medicine, the knee joint has traditionally been considered the workhorse. The reconstruction of every damaged element in this joint is crucial in achieving the surgeon’s goal to restore the knee function and prevent degeneration towards osteoarthritis. In the last fifteen years, the field of regenerative medicine is witnessing a boost of autologous blood-derived platelet rich plasma products (PRPs application to effectively mimic and accelerate the tissue healing process. The scientific rationale behind PRPs is the delivery of growth factors, cytokines, and adhesive proteins present in platelets and plasma, as well as other biologically active proteins conveyed by the plasma such as fibrinogen, prothrombin, and fibronectin; with this biological engineering approach, new perspectives in knee surgery were opened. This work describes the use of PRP to construct and repair every single anatomical structure involved in knee surgery, detailing the process conducted in ligament, meniscal, and chondral surgery.

  14. Platelet microvesicles in health and disease.

    Science.gov (United States)

    Melki, Imene; Tessandier, Nicolas; Zufferey, Anne; Boilard, Eric

    2017-05-01

    Interest in cell-derived extracellular vesicles and their physiological and pathological implications is constantly growing. Microvesicles, also known as microparticles, are small extracellular vesicles released by cells in response to activation or apoptosis. Among the different microvesicles present in the blood of healthy individuals, platelet-derived microvesicles (PMVs) are the most abundant. Their characterization has revealed a heterogeneous cargo that includes a set of adhesion molecules. Similarly to platelets, PMVs are also involved in thrombosis through support of the coagulation cascade. The levels of circulatory PMVs are altered during several disease manifestations such as coagulation disorders, rheumatoid arthritis, systemic lupus erythematosus, cancers, cardiovascular diseases, and infections, pointing to their potential contribution to disease and their development as a biomarker. This review highlights recent findings in the field of PMV research and addresses their contribution to both healthy and diseased states.

  15. Platelets of patients with chronic kidney disease demonstrate deficient platelet reactivity in vitro

    Directory of Open Access Journals (Sweden)

    van Bladel Esther R

    2012-09-01

    Full Text Available Abstract Background In patients with chronic kidney disease studies focusing on platelet function and properties often are non-conclusive whereas only few studies use functional platelet tests. In this study we evaluated a recently developed functional flow cytometry based assay for the analysis of platelet function in chronic kidney disease. Methods Platelet reactivity was measured using flow cytometric analysis. Platelets in whole blood were triggered with different concentrations of agonists (TRAP, ADP, CRP. Platelet activation was quantified with staining for P-selectin, measuring the mean fluorescence intensity. Area under the curve and the concentration of half-maximal response were determined. Results We studied 23 patients with chronic kidney disease (9 patients with cardiorenal failure and 14 patients with end stage renal disease and 19 healthy controls. Expression of P-selectin on the platelet surface measured as mean fluorescence intensity was significantly less in chronic kidney disease patients compared to controls after maximal stimulation with TRAP (9.7 (7.9-10.8 vs. 11.4 (9.2-12.2, P = 0.032, ADP (1.6 (1.2-2.1 vs. 2.6 (1.9-3.5, P = 0.002 and CRP (9.2 (8.5-10.8 vs. 11.5 (9.5-12.9, P = 0.004. Also the area under the curve was significantly different. There was no significant difference in half-maximal response between both groups. Conclusion In this study we found that patients with chronic kidney disease show reduced platelet reactivity in response of ADP, TRAP and CRP compared to controls. These results contribute to our understanding of the aberrant platelet function observed in patients with chronic kidney disease and emphasize the significance of using functional whole blood platelet activation assays.

  16. Platelet integrin α6β1 controls lung metastasis through direct binding to cancer cell–derived ADAM9

    Science.gov (United States)

    Mammadova-Bach, Elmina; Zigrino, Paola; Brucker, Camille; Bourdon, Catherine; Freund, Monique; Abrams, Scott I.; Orend, Gertaud; Gachet, Christian

    2016-01-01

    Metastatic dissemination of cancer cells, which accounts for 90% of cancer mortality, is the ultimate hallmark of malignancy. Growing evidence suggests that blood platelets have a predominant role in tumor metastasis; however, the molecular mechanisms involved remain elusive. Here, we demonstrate that genetic deficiency of integrin α6β1 on platelets markedly decreases experimental and spontaneous lung metastasis. In vitro and in vivo assays reveal that human and mouse platelet α6β1 supports platelet adhesion to various types of cancer cells. Using a knockdown approach, we identified ADAM9 as the major counter receptor of α6β1 on both human and mouse tumor cells. Static and flow-based adhesion assays of platelets binding to DC-9, a recombinant protein covering the disintegrin-cysteine domain of ADAM9, demonstrated that this receptor directly binds to platelet α6β1. In vivo studies showed that the interplay between platelet α6β1 and tumor cell–expressed ADAM9 promotes efficient lung metastasis. The integrin α6β1–dependent platelet-tumor cell interaction induces platelet activation and favors the extravasation process of tumor cells. Finally, we demonstrate that a pharmacological approach targeting α6β1 efficiently impairs tumor metastasis through a platelet-dependent mechanism. Our study reveals a mechanism by which platelets promote tumor metastasis and suggests that integrin α6β1 represents a promising target for antimetastatic therapies. PMID:27699237

  17. Analysis on reasons of unqualified blood test results on apheresis platelets donors%机采血小板献血者血液检测不合格原因分析

    Institute of Scientific and Technical Information of China (English)

    邹韬; 杨松; 陈臻

    2015-01-01

    ObjectiveTo analyze the reasons of unqualified blood test results on apheresis platelets donors in Nanchong; to improve the recruitment strategy and pre-donor screening program.MethodsBlood test results on apheresis platelets donors in Nanchong from 2010 to 2014 were analyzed and counted.ResultsTotal unqualified rate of blood test on platelet from 2010 to 2014 was 2.09%, wherein unqualified rate of new donors was 5.51% and that of repeated donors was 1.36%. Unqualified rates of ALT, HBsAg, anti-HCV, anti-HIV, and anti-TP were 0.87%, 0.51%, 0.13%, 0.21% and 0.44%.ConclusionsApheresis platelets donors are recruited from stationary voluntary unpaid donors. Strengthening blood screening of blood donors can decrease unqualified rate of platelet detection.%目的:分析南充市机采血小板血液检测不合格原因,改进招募策略和献血前筛查方案。方法:对本市2010-2014年机采血小板血液检测结果进行分析统计。结果:2010-2014年血小板血液检测总不合格率为2.09%,其中首次献血者的不合格率为5.51%,重复献血者的不合格率为1.36%,不合格原因中ALT、HBsAg、抗-HCV、抗-HIV、抗-TP的不合格率分别为0.87%、0.51%、0.13%、0.21%、0.44%。结论:从固定自愿无偿献血者中招募机采血小板献血者、加强献血者血液筛查可降低机采血小板检测不合格率。

  18. Platelet concentration in platelet concentrates and periodontal regeneration-unscrambling the ambiguity

    Directory of Open Access Journals (Sweden)

    A Suchetha

    2015-01-01

    Full Text Available Context: Platelet-rich-plasma (PRP and Platelet-rich-fibrin (PRF are extensively used autologous platelet concentrates in periodontal regeneration, and PRF has a better efficacy as compared to PRP. The rationale for this difference has often been attributed to the difference in the structure of the fibrin matrix. However, the effect of concentration of platelets on the regenerative potential of these concentrates is obscure. Aims: The study was conducted to evaluate and compare, clinically and radiographically, the efficacy of PRF and PRP in the treatment of periodontal endosseous defects and to assess the effect of platelet concentration on periodontal regeneration. Materials and Methods: Twenty intrabony defects were selected and divided into two groups randomly by the coin toss method. Group I received PRP and Group II subjects were treated with PRF. The platelet counts in PRP and PRF were analyzed. Clinical and radiological parameters were assessed at baseline and 3, 6, and 9 months postoperatively. Statistical Analysis: Kruskal–Wallis Chi-square test, Wilcoxon signed rank test, t-test, and Spearman's rank correlation were used for statistical analysis of data. Results: There was statistically significant improvement in all the parameters in the two groups except in relation to gingival recession. There was a statistically significant difference between the platelet count in Group I and Group II (P = 0.002. Conclusion: PRP and PRF appear to have nearly comparable effects in terms of periodontal regeneration. The concentration of platelets appears to play a paradoxical role in regeneration. The regenerative potential of platelets appears to be optimal within a limited range.

  19. Platelet concentration in platelet concentrates and periodontal regeneration-unscrambling the ambiguity

    Science.gov (United States)

    Suchetha, A.; Lakshmi, P.; Bhat, Divya; Mundinamane, Darshan B.; Soorya, K. V.; Bharwani, G. Ashit

    2015-01-01

    Context: Platelet-rich-plasma (PRP) and Platelet-rich-fibrin (PRF) are extensively used autologous platelet concentrates in periodontal regeneration, and PRF has a better efficacy as compared to PRP. The rationale for this difference has often been attributed to the difference in the structure of the fibrin matrix. However, the effect of concentration of platelets on the regenerative potential of these concentrates is obscure. Aims: The study was conducted to evaluate and compare, clinically and radiographically, the efficacy of PRF and PRP in the treatment of periodontal endosseous defects and to assess the effect of platelet concentration on periodontal regeneration. Materials and Methods: Twenty intrabony defects were selected and divided into two groups randomly by the coin toss method. Group I received PRP and Group II subjects were treated with PRF. The platelet counts in PRP and PRF were analyzed. Clinical and radiological parameters were assessed at baseline and 3, 6, and 9 months postoperatively. Statistical Analysis: Kruskal–Wallis Chi-square test, Wilcoxon signed rank test, t-test, and Spearman's rank correlation were used for statistical analysis of data. Results: There was statistically significant improvement in all the parameters in the two groups except in relation to gingival recession. There was a statistically significant difference between the platelet count in Group I and Group II (P = 0.002). Conclusion: PRP and PRF appear to have nearly comparable effects in terms of periodontal regeneration. The concentration of platelets appears to play a paradoxical role in regeneration. The regenerative potential of platelets appears to be optimal within a limited range. PMID:26681857

  20. 血小板功能检测及其在多种疾病中的研究进展%Research progress on platelet function testing and its application in a variety of diseases

    Institute of Scientific and Technical Information of China (English)

    蔡玉婵; 李智

    2015-01-01

    Abnormal platelet quantity and quality are important factors leading to bleeding and thrombotic diseases. Meanwhile,they are also involved in the pathological process of some diseases,such as diabetic complications, angiocardiopathy,tumor and inflammatory.Platelet function testing,particularly for aggregation function and activation function of platelets,can provide a approach for the prevention and diagnosis of clinical diseases,especially for the treatment and monitoring of diseases.%血小板数量与质量异常是导致出血性和血栓性疾病发生的重要原因。同时,它们还参与一些疾病的病理过程,如糖尿病并发症的产生、心血管疾病、肿瘤及炎症反应。检测血小板功能,尤其是血小板的聚集功能和活化功能,可为临床疾病的预防与诊断提供更好的途径,对疾病的治疗及监测的研究尤为重要。

  1. MECHANISM OF PRESERVING EFFECT OF APROTININ ON PLATELET FUNCTION DURING CARDIOPULMONARY BYPASS

    Institute of Scientific and Technical Information of China (English)

    黄惠民; 丁文祥; 苏肇伉; 张伟忠

    1992-01-01

    The deficiency of platelet function is the main defect of hemostatic mechanism during cardiopulmonary bypass (CPB), which attributed to the postoperative bleeding complication to a great extent. The proteinase inhibitor aprotinin was reported to have preserving effect on platelet adhesion during CPB. In this clinical reserch we found that CPB caused plasma alpha 2-antiplasmin decreasing, indicating the fibrinolytic system activation. Meanwhile, the ristocetin-induced aggregation declined to 39.6% and platelet GPIb decreased to 50% of preoperative value. However, by treatment with aprotinin, the plasma alpha 2-antiplasmin during CPB did not change, platelet aggregation was improved and platelet GPIb was preserved, and consequently resulted in a 46% lower blood loss postoperatively. These results confirmed that aprotinin could inhibit the fibrinolysis during CPB, and thus relieve the platelet damage and improve the postoperative hemostatic mechanism.

  2. Lotus-leaf-like structured chitosan–polyvinyl pyrrolidone films as an anti-adhesion barrier

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jin Ik; Kang, Min Ji; Lee, Woo-Kul, E-mail: leewo@dankook.ac.kr

    2014-11-30

    Highlights: • Improved mechanical properties by hydrogen bond between chitosan and PVP chains. • Improved anti-adhesion effect by lotus-leaf-like structured chitosan–PVP (L-chitosan–PVP) film. • L-Chitosan–PVP film as a blood/tissue anti-adhesion barrier for post-surgical treatment. - Abstract: For postsurgical anti-adhesion barrier applications, lotus-leaf-like structured chitosan–PVP films were prepared using a solution casting method with dodecyltrichloro-immobilized SiO{sub 2} nanoparticles. We evaluated whether the lotus-leaf-like structured chitosan–PVP films (L-chitosan–PVP) could be applied as postsurgical anti-adhesion barriers. A recovery test using a tensile strength testing machine and measurement of crystallinity using X-ray diffraction indicated that films with 75% PVP were the optimal composition of the chitosan–PVP films. Also, dodecyltrichloro-immobilized SiO{sub 2} nanoparticles were synthesized and sprayed on the film after pretreatment with the instant bio-glue. Analysis of cell adhesion, proliferation, and anti-thrombus efficiency were performed via a WST assay, field emission scanning electron microscopy, and hemacytometry. The contact angle with the lotus-leaf-like surface was of approximately 150°. Furthermore, the L-chitosan–PVP film yielded a lower cell and platelet adhesion rate (around less than 4%) than that yielded by the untreated film. These results indicate that the lotus-leaf-like structure has a unique property and that this novel L-chitosan–PVP film can be applied as a blood/tissue-compatible, biodegradable material for implantable medical devices that need an anti-adhesion barrier.

  3. [Indications and surveillance of platelet transfusions in surgery].

    Science.gov (United States)

    Coffe, C; Bardiaux, L; Couteret, Y; Devillers, M; Leroy, M; Morel, P; Pouthier-Stein, F; Hervé, P

    1995-01-01

    Surgery, after hematology, is the biggest consumer of homologous platelet concentrates. Platelet transfusion is indicated to prevent or control bleeding associated with deficiencies in platelet number or function. In surgery, general patterns (in function of pre-surgery platelet count) can be adopted in most of the indications for platelets. In emergency situations, and in some particular cases (related to the patient, the type of operation, etc.), the transfusion procedure depends on the team's experience, the results of the available clinical and biological tests, and the drugs. Strict monitoring is required during the transfusion procedure. The efficacy of the transfusion must be controlled 1 h and 24 hours after the transfusion, and a number of factors must be assessed, namely the immunological impact of the transfusion (on red blood cells, leukocytes and platelets) and the occurrence of infectious diseases transmitted via transfusion. In addition, for a possible future transfusion, a strategy must be proposed.

  4. Monitoring aspirin therapy with the Platelet Function Analyzer-100

    DEFF Research Database (Denmark)

    Mortensen, Jette; Poulsen, Tina Svenstrup; Grove, Erik Lerkevang;

    2008-01-01

    OBJECTIVE: Low platelet response to aspirin has been reported to be associated with a high incidence of vascular events. The reported prevalence of aspirin low-responsiveness varies, which may be explained by poor reproducibility of the methods used to evaluate aspirin response and low compliance....... The Platelet Function Analyzer-100 (PFA-100) is a commonly used platelet function test. We aimed to assess the reproducibility of the PFA-100 and the agreement with optical platelet aggregometry (OPA) in healthy volunteers and in patients with coronary artery disease (CAD) treated with low-dose aspirin....... MATERIAL AND METHODS: Twenty-one healthy volunteers and 43 patients with CAD took part in the study. During treatment with aspirin 75 mg daily, all participants had platelet function assessed in duplicate with the PFA-100 and OPA on 4 consecutive days. Additionally, platelet function was assessed before...

  5. Comparison of VerifyNow-P2Y12 test and Flow Cytometry for monitoring individual platelet response to clopidogrel. What is the cut-off value for identifying patients who are low responders to clopidogrel therapy?

    Directory of Open Access Journals (Sweden)

    Castelli Alfredo

    2009-05-01

    Full Text Available Abstract Background Dual anti-platelet therapy with aspirin and a thienopyridine (DAT is used to prevent stent thrombosis after percutaneous coronary intervention (PCI. Low response to clopidogrel therapy (LR occurs, but laboratory tests have a controversial role in the identification of this condition. Methods We studied LR in patients with stable angina undergoing elective PCI, all on DAT for at least 7 days, by comparing: 1 Flow cytometry (FC to measure platelet membrane expression of P-selectin (CD62P and PAC-1 binding following double stimulation with ADP and collagen type I either in the presence of prostaglandin (PG E1; 2 VerifyNow-P2Y12 test, in which results are reported as absolute P2Y12-Reaction-Units (PRU or % of inhibition (% inhibition. Results Thirty controls and 52 patients were analyzed. The median percentage of platelets exhibiting CD62P expression and PAC-1 binding by FC evaluation after stimulation in the presence of PG E1 was 25.4% (IQR: 21.4–33.1% and 3.5% (1.7–9.4%, respectively. Only 6 patients receiving DAT (11.5% had both values above the 1st quartile of controls, and were defined as LR. Evaluation of the same patients with the VerifyNow-P2Y12 test revealed that the area under the receiver-operating-characteristic (ROC curve was 0.94 (95% CI: 0.84–0.98, p 213 PRU gave the maximum accuracy for the detection of patients defined as having LR by FC. Conclusion In conclusion our findings show that a cut-off value of ≤ 15% inhibition or > 213 PRU in the VerifyNow-P2Y12 test may provide the best accuracy for the identification of patients with LR.

  6. The Influence of Low Platelet Count on Whole Blood Aggregometry Assessed by Multiplate

    DEFF Research Database (Denmark)

    Stissing, Trine; Dridi, Nadia P; Ostrowski, Sisse R;

    2011-01-01

    The Multiplate, a whole blood (WB) platelet function test, has shown promising results identifying patients on antiplatelet therapy at increased risk of rethrombosis. In the present study, the influence of low platelet count on platelet aggregation was analyzed and compared with aggregation results...... in an artificial matrix, platelet-rich plasma (PRP). Heparinized and citrated blood was diluted with autologous plasma to platelet concentrations 200 to 25 × 10(9)/L in WB samples (n = 10) and 200 to 100 × 10(9)/L in PRP samples (n = 7). The platelet aggregation was investigated by the ADP-, ASPI-, COL-, and TRAP...

  7. beta-Dystroglycan modulates the interplay between actin and microtubules in human-adhered platelets.

    Science.gov (United States)

    Cerecedo, Doris; Cisneros, Bulmaro; Suárez-Sánchez, Rocío; Hernández-González, Enrique; Galván, Iván

    2008-05-01

    To maintain the continuity of an injured blood vessel, platelets change shape, secrete granule contents, adhere, aggregate, and retract in a haemostatic plug. Ordered arrays of microtubules, microfilaments, and associated proteins are responsible for these platelet responses. In full-spread platelets, microfilament bundles in association with other cytoskeleton proteins are anchored in focal contacts. Recent studies in migrating cells suggest that co-ordination and direct physical interaction of microtubules and actin network modulate adhesion development. In platelets, we have proposed a feasible association between these two cytoskeletal systems, as well as the participation of the dystrophin-associated protein complex, as part of the focal adhesion complex. The present study analysed the participation of microtubules and actin during the platelet adhesion process. Confocal microscopy, fluorescence resonance transfer energy and immunoprecipitation assays were used to provide evidence of a cross-talk between these two cytoskeletal systems. Interestingly, beta-dystroglycan was found to act as an interplay protein between actin and microtubules and an additional communication between these two cytoskeleton networks was maintained through proteins of focal adhesion complex. Altogether our data are indicative of a dynamic co-participation of actin filaments and microtubules in modulating focal contacts to achieve platelet function.

  8. Matrix metalloproteinase-2 enhances platelet deposition on collagen under flow conditions.

    Science.gov (United States)

    Guglielmini, Giuseppe; Appolloni, Viviana; Momi, Stefania; De Groot, Philip G; Battiston, Monica; De Marco, Luigi; Falcinelli, Emanuela; Gresele, Paolo

    2016-01-01

    Platelets contain and release matrix metalloproteinase-2 (MMP-2) that in turn potentiates platelet aggregation. Platelet deposition on a damaged vascular wall is the first, crucial, step leading to thrombosis. Little is known about the effects of MMP-2 on platelet activation and adhesion under flow conditions. We studied the effect of MMP-2 on shear-dependent platelet activation using the O'Brien filtration system, and on platelet deposition using a parallel-plate perfusion chamber. Preincubation of human whole blood with active MMP-2 (50 ng/ml, i.e. 0.78 nM) shortened filter closure time (from 51.8 ± 3.6 sec to 40 ± 2.7 sec, pMMP-2 inhibitor. High shear stress induced the release of MMP-2 from platelets, while TIMP-2 levels were not significantly reduced, therefore, the MMP-2/TIMP-2 ratio increased significantly showing enhanced MMP-2 activity. Preincubation of whole blood with active MMP-2 (0.5 to 50 ng/ml, i.e 0.0078 to 0.78 nM) increased dose-dependently human platelet deposition on collagen under high shear-rate flow conditions (3000 sec⁻¹) (maximum +47.0 ± 11.9%, pMMP-2 inhibitor reduced platelet deposition. In real-time microscopy studies, increased deposition of platelets on collagen induced by MMP-2 started 85 sec from the beginning of perfusion, and was abolished by a GPIIb/IIIa antagonist, while MMP-2 had no effect on platelet deposition on fibrinogen or VWF. Confocal microscopy showed that MMP-2 enhances thrombus volume (+20.0 ± 3.0% vs control) rather than adhesion. In conclusion, we show that MMP-2 potentiates shear-induced platelet activation by enhancing thrombus formation.

  9. Adhesion of Antireflective Coatings in Multijunction Photovoltaics

    Energy Technology Data Exchange (ETDEWEB)

    Brock, Ryan; Miller, David C.; Dauskardt, Reinhold H.

    2016-11-21

    The development of a new composite dual cantilever beam (cDCB) thin-film adhesion testing method is reported, which allows the measurement of adhesion on the fragile thin substrates used in multijunction photovoltaics. We address the adhesion of several antireflective coating systems on multijunction cells. By varying interface chemistry and morphology, we demonstrate the ensuing effects on adhesion and help to develop an understanding of how high adhesion can be achieved, as adhesion values ranging from 0.5 J/m2 to 10 J/m2 were measured. Damp Heat (85 degrees C/85% RH) was used to invoke degradation of interfacial adhesion. We show that even with germanium substrates that fracture easily, quantitative measurements of adhesion can still be made at high test yield. The cDCB test is discussed as an important new methodology, which can be broadly applied to any system that makes use of thin, brittle, or otherwise fragile substrates.

  10. The detection of platelet isoantibodies by membrane immunofluorescence.

    Science.gov (United States)

    van der Schans, G S; Veenhoven, W A; Snijder, J A; Nieweg, H O

    1977-07-01

    A membrane ummunofluorescence test for the detection of platelet isoantibodies is described. Gel filtration of the incubation mixture was incorporated in the procedure and proved effective for the removal of serum proteins from the platelet suspension. With this technique isoantibodies were found in the serum of 13 out of a group of 16 patients who had received multiple transfusions. The results were checked by measuring the uptake of 125I-labeled anti-IgG fraction by gel-filtered platelets. Subsequently the membrane immunofluorescence method was also compared with established techniques described for the detection of isoantibodies such as the microtest for lymphocytotoxicity and a complement-fixation method and the procedures based on the release of labeled serotonin, the phagocytosis of chromium-tagged platelets, the increase of platelet factor 3 activity, and on platelet aggregation. We had the opportunity to investigate the serum of one patient for the presence of isoantibodies against platelets from HLA identical siblings both before and after the administration of their platelets. On the basis of this experience it is concluded that the membrane immunofluorescence test for platelet isoantibodies is a relatively simple method with a high degree of specificity and adequate sensitivity.

  11. Beyond the platelet count: immature platelet fraction and thromboelastometry correlate with bleeding in patients with immune thrombocytopenia.

    Science.gov (United States)

    Greene, Lindsey A; Chen, Siqi; Seery, Caroline; Imahiyerobo, Allison M; Bussel, James B

    2014-08-01

    Platelet counts (PC) estimate bleeding risk in Immune Thrombocytopenia (ITP). We investigated whether measures of thromboelastometry and absolute immature platelet fraction (A-IPF) would correlate better with acute bleeding score (ABS) than PC or mean platelet volume (MPV). Simultaneous determination of ABS, complete blood count and thromboelastometry was performed in 141 ITP patients; 112 underwent A-IPF testing. Subgroup analyses were performed for paediatric subjects, PC children with PC children and children with PC platelet function, contribute to ITP bleeding pathophysiology. Thromboelastometry, A-IPF and ABS can be incorporated into routine or acute visits.

  12. Effect of adhesive thickness on adhesively bonded T-joint

    Science.gov (United States)

    Abdullah, A. R.; Afendi, Mohd; Majid, M. S. Abdul

    2013-12-01

    The aim of this work is to analyze the effect of adhesive thickness on tensile strength of adhesively bonded stainless steel T-joint. Specimens were made from SUS 304 Stainless Steel plate and SUS 304 Stainless Steel perforated plate. Four T-joint specimens with different adhesive thicknesses (0.5, 1.0, 1.5 and 2.0 mm) were made. Experiment result shows T-joint specimen with adhesive thickness of 1.0 mm yield highest maximum load. Identical T-joint specimen jointed by spot welding was also tested. Tensile test shows welded T-Joint had eight times higher tensile load than adhesively bonded T-joint. However, in low pressure application such as urea granulator chamber, high tensile strength is not mandatory. This work is useful for designer in fertilizer industry and others who are searching for alternative to spot welding.

  13. Bacterial Adhesion & Blocking Bacterial Adhesion

    DEFF Research Database (Denmark)

    Vejborg, Rebecca Munk

    2008-01-01

    tract to the microbial flocs in waste water treatment facilities. Microbial biofilms may however also cause a wide range of industrial and medical problems, and have been implicated in a wide range of persistent infectious diseases, including implantassociated microbial infections. Bacterial adhesion...... is the first committing step in biofilm formation, and has therefore been intensely scrutinized. Much however, still remains elusive. Bacterial adhesion is a highly complex process, which is influenced by a variety of factors. In this thesis, a range of physico-chemical, molecular and environmental parameters......, which influence the transition from a planktonic lifestyle to a sessile lifestyle, have been studied. Protein conditioning film formation was found to influence bacterial adhesion and subsequent biofilm formation considerable, and an aqueous extract of fish muscle tissue was shown to significantly...

  14. Crosstalk between Platelets and the Immune System: Old Systems with New Discoveries

    Directory of Open Access Journals (Sweden)

    Conglei Li

    2012-01-01

    Full Text Available Platelets are small anucleate cells circulating in the blood. It has been recognized for more than 100 years that platelet adhesion and aggregation at the site of vascular injury are critical events in hemostasis and thrombosis; however, recent studies demonstrated that, in addition to these classic roles, platelets also have important functions in inflammation and the immune response. Platelets contain many proinflammatory molecules and cytokines (e.g., P-selectin, CD40L, IL-1β, etc., which support leukocyte trafficking, modulate immunoglobulin class switch, and germinal center formation. Platelets express several functional Toll-like receptors (TLRs, such as TLR-2, TLR-4, and TLR-9, which may potentially link innate immunity with thrombosis. Interestingly, platelets also contain multiple anti-inflammatory molecules and cytokines (e.g., transforming growth factor-β and thrombospondin-1. Emerging evidence also suggests that platelets are involved in lymphatic vessel development by directly interacting with lymphatic endothelial cells through C-type lectin-like receptor 2. Besides the active contributions of platelets to the immune system, platelets are passively targeted in several immune-mediated diseases, such as autoimmune thrombocytopenia, infection-associated thrombocytopenia, and fetal and neonatal alloimmune thrombocytopenia. These data suggest that platelets are important immune cells and may contribute to innate and adaptive immunity under both physiological and pathological conditions.

  15. Platelets and white blood cells in acute coronary syndromes

    NARCIS (Netherlands)

    Smit, Jaap Jan Johannes

    2008-01-01

    In this thesis, we have studied the role of leukocytes and platelets as methods to measure platelets aggregation, in the clinical management of presenting with acute coronary syndromes. We have tried to incidence and to identify predictors of adverse cardiac events with function tests or inflammator

  16. Platelet function in brown bear (Ursus arctos compared to man

    Directory of Open Access Journals (Sweden)

    Särndahl Eva

    2010-06-01

    Full Text Available Abstract Background Information on hemostasis and platelet function in brown bear (Ursus arctos is of importance for understanding the physiological, protective changes during hibernation. Objective The study objective was to document platelet activity values in brown bears shortly after leaving the den and compare them to platelet function in healthy humans. Methods Blood was drawn from immobilized wild brown bears 7-10 days after leaving the den in mid April. Blood samples from healthy human adults before and after clopidogrel and acetylsalicylic acid administration served as control. We analyzed blood samples by standard blood testing and platelet aggregation was quantified after stimulation with various agonists using multiple electrode aggregometry within 3 hours of sampling. Results Blood samples were collected from 6 bears (3 females between 1 and 16 years old and from 10 healthy humans. Results of adenosine diphosphate, aspirin, and thrombin receptor activating peptide tests in bears were all half or less of those in humans. Platelet and white blood cell counts did not differ between species but brown bears had more and smaller red blood cells compared with humans. Conclusion Using three different tests, we conclude that platelet function is lower in brown bears compared to humans. Our findings represent the first descriptive study on platelet function in brown bears and may contribute to explain how bears can endure denning without obvious thrombus building. However, the possibility that our findings reflect test-dependent and not true biological variations in platelet reactivity needs further studies.

  17. Beyond hemostasis: the role of platelets in inflammation, malignancy and infection.

    Science.gov (United States)

    McNicol, Archibald; Israels, Sara J

    2008-06-01

    Platelets play a complex role in hemostasis and thrombosis. The expression of multiple membrane receptors, both constitutive and activation-dependent, mediates platelet adhesion and aggregation at sites of vascular lesion. Platelet activation leads to exocytosis of granular constituents, release of newly synthesized mediators, and discharge of membrane-bound transcellular signaling molecules. Many of the same mechanisms that play a role in hemostasis and thrombosis facilitate platelet participation in other physiological or pathological processes including inflammation, malignancy and the immune response. Platelet receptors such as GPIb/IX/V, P-selectin, P-selectin glycoprotein ligand 1, CD40 and the alphaIIbbeta3 integrin, crucial to hemostasis, have been implicated in the progression of such inflammatory conditions as atherosclerosis, rheumatoid arthritis and inflammatory bowel disease, in the progression and metastatic spread of malignancies, and in the immune response to bacterial challenge. The release of platelet granular contents, including adhesive proteins, growth factors and chemokines/cytokines, that serve to facilitate hemostasis and wound repair, also function in acute and chronic inflammatory disease and in tumor cell activation and growth. Platelets contribute to host defence as they recognise bacteria, recruit traditional immune cells to the site of infection and secrete bactericidal mediators. The primary focus of this review is the "non-haemostatic" functions of platelets in physiological and pathological states.

  18. Interaction of platelets, fibrinogen and endothelial cells with plasma deposited PEO-like films

    Science.gov (United States)

    Yang, Zhilu; Wang, Jin; Li, Xin; Tu, Qiufen; Sun, Hong; Huang, Nan

    2012-02-01

    For blood-contacting biomedical implants like retrievable vena cava filters, surface-based diagnostic devices or in vivo sensors, limiting thrombosis and cell adhesion is paramount, due to a decrease even failure in performance. Plasma deposited PEO-like films were investigated as surface modifications. In this work, mixed gas composed of tetraethylene glycol dimethyl ether (tetraglyme) vapor and oxygen was used as precursor. It was revealed that plasma polymerization under high ratio of oxygen/tetraglyme led to deposition of the films that had high content of ether groups. This kind of PEO-like films had good stability in phosphate buffer solution. In vitro hemocompatibility and endothelial cell (EC) adhesion revealed low platelet adhesion, platelet activation, fibrinogen adhesion, EC adhesion and proliferation on such plasma deposited PEO-like films. This made it a potential candidate for the applications in anti-fouling surfaces of blood-contacting biomedical devices.

  19. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical University Luebeck (Federal Republic of Germany). Department of Neurology); Hardeman, M.R. (Amsterdam Univ. (Netherlands). Academisch Ziekenhuis); Henningsen, H. (Heidelberg Univ. (Germany, F.R.). Neurologische Klinik); Petrovici, J.-N. (Cologne-Merheim Hospital (Federal Republic of Germany). Department of Neurology) (eds.)

    1990-01-01

    The increasing number of therapeutic modalities available for the management of patients with thromboembolic complications, such as fibrinolytic treatment or vascular surgery, require the development of new imaging techniques to provide more information on the xtent, age and activity of the thromboembolic material causing clinical symptoms. Since the introduction of radiolabelling of platelets with indium-111, platelet scintigraphy (PSC) has been used as a tool in the diagnosis of various thromboembolic diseases. During the International Symposium on Radiolabelled Platelets scientists from a variety of medical backgrounds presented their results on the clinical applictions of radiolabelled platelets. The papers presented there have been updated to take account of the latest results before publication in this volume. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection. refs.; figs.; tabs.

  20. Platelet preservation: agitation and containers.

    Science.gov (United States)

    van der Meer, Pieter F; de Korte, Dirk

    2011-06-01

    For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted.

  1. PLATELET RICH FIBRIN: A PROMISING INNOVATION IN REGENERATIVE THERAPY

    Directory of Open Access Journals (Sweden)

    Arun

    2015-04-01

    Full Text Available Platelets can play a crucial role in regenerative therapy as they are reservoirs of growth factors and cytokines which are the key factors for regeneration of the bone and maturation of the soft tissue. Platelet - rich fibr in (PRF was first described by Choukroun et al. in France. It has been referred to as a second - generation platelet concentrate, which has been shown to have several advantages over traditionally prepared PRP. Platelet - rich fibrin (PRF is autologous plate let concentrates prepared from patient’s own blood. It is a natural fibrin - based biomaterial prepared from an anticoagulant - free blood harvest without any artificial biochemical modification that allows obtaining fibrin membranes enriched with platelets a nd growth factors. Evidence from the literature suggests the potential role of PRF in regeneration and tissue engineering. The slow polymerisation during centrifugation and fibrin - based structure makes PRF a better healing biomaterial than PRP and other fi brin adhesives. The purpose of this review article is to describe the novel second - generation platelet concentrate PRF, which is an improvement over the traditionally prepared PRP for use in regenerative dentistry.

  2. The role of platelets in the pathophysiology of asthma.

    Science.gov (United States)

    Kornerup, K N; Page, C P

    2007-08-01

    The incidence of asthma is on the increase worldwide, yet the pathogenesis of this disease is still not fully understood. Many recent drug trials have had disappointing results, thus fuelling the need for more research to be undertaken in this area. Substantial evidence suggests an important role for platelets in various inflammatory diseases, including atherosclerosis, rheumatoid arthritis, eczema, allergic rhinitis and asthma. In asthma, platelets have been found to actively participate in most of its main features, including bronchial hyperresponsiveness, bronchoconstriction, airway inflammation and airway remodelling. It has recently become clear that platelet-release products, as well as the expression of adhesion molecules on the platelet surface and the ability to undergo chemotaxis, are all involved in these processes. This review focuses on both experimental and clinical studies available to date that have investigated the role of platelets in the pathophysiology of asthma. Taken together, the evidence points toward platelets being an attractive new target in the area of asthma research; a target with much-needed novel therapeutic potential.

  3. /sup 111/In-oxine platelet survivals in thrombocytopenic infants

    Energy Technology Data Exchange (ETDEWEB)

    Castle, V.; Coates, G.; Kelton, J.G.; Andrew, M.

    1987-09-01

    Thrombocytopenia is a common occurrence (20%) in sick neonates, but the causes have not been well studied. In this report we demonstrate that thrombocytopenia in the neonate is characterized by increased platelet destruction as shown by shortened homologous /sup 111/In-oxine-labeled platelet life spans. Thirty-one prospectively studied thrombocytopenic neonates were investigated by measuring the /sup 111/In-labeled platelet life span, platelet-associated IgG (PAIgG), and coagulation screening tests. In every infant, the thrombocytopenia was shown to have a destructive component since the mean platelet life span was significantly shortened to 65 +/- 6 (mean +/- SEM) hours with a range of one to 128 hours compared with adult values (212 +/- 8; range, 140 to 260; gamma function analysis). The platelet survival was directly related to the lowest platelet count and inversely related to both the highest mean platelet volume and duration of the thrombocytopenia. In 22 infants the percent recovery of the radiolabeled platelets was less than 50%, which suggested that increased sequestration also contributed to the thrombocytopenia. Infants with laboratory evidence of disseminated intravascular coagulation (n = 8) or immune platelet destruction evidenced by elevated levels of PAIgG (n = 13) had even shorter platelet survivals and a more severe thrombocytopenia compared with the ten infants in whom an underlying cause for the thrombocytopenia was not apparent. Full-body scintigraphic images obtained in 11 infants showed an increased uptake in the spleen and liver, with a spleen-to-liver ratio of 3:1. This study indicates that thrombocytopenia in sick neonates is primarily destructive, with a subgroup having evidence of increased platelet sequestration.

  4. In vitro model of platelet aggregation in stenotic arteries

    Energy Technology Data Exchange (ETDEWEB)

    Morley, D.; Santamore, W.P.

    1988-07-01

    Clinical and experimental evidence suggest a strong relationship between arterial stenosis, platelet aggregation, and subsequent thrombus formation. To facilitate the study of platelet accumulation in stenotic arteries, we developed an in vitro preparation. Arterial segments were perfused with whole citrated blood. A stenosis was created by applying an external plastic constrictor to the artery. Platelet accumulation within the stenosis was assessed by scanning electron microscopy and by radioactive counts from Indium-111 labeled platelets. Utilizing this preparation, 30 carotid arterial segments from 10 mongrel dogs were perfused at 100 mmHg for 15 min. In 10 arteries without a stenosis, scanning electron microscopy and radioactive counts demonstrated little platelet accumulation. In contrast, extensive platelet aggregation was observed in 10 arteries with stenoses. Moreover, in 10 stenotic arteries exposed to the thromboxane mimetic, U46619 (Upjohn Diagnostic Group), scanning electron microscopy and radioactive counts demonstrated a significant increase in platelet deposition. Conversely, we demonstrated a dimunition of platelet accumulation in stenosed arterial segments exposed to the prostacyclin analogue platelet inhibitor, Iloprost. The in vitro preparation allows precise control of hemodynamic variables and makes it possible to perform multiple tests on segments of the same vessel from the same animal.

  5. High doses of recombinant erythropoietin stimulate platelet production in mice

    Energy Technology Data Exchange (ETDEWEB)

    McDonald, T.P.; Cottrell, M.B.; Clift, R.E.; Cullen, W.C.; Lin, F.K.

    1987-07-01

    Previously, recombinant erythropoietin (rEpo) was shown to increase the number and size of megakaryocytic colonies in vitro, and in vivo it elevates the number of megakaryocytes in mouse spleens. To test the hypothesis that rEpo would stimulate platelet production in mice, both normal mice and mice in rebound-thrombocytosis were injected with rEpo and the %35S incorporation into platelets was measured. A thrombocytopoiesis-stimulating factor (TSF or thrombopoietin) was used as a positive control. rEpo increased isotopic incorporation into platelets of both normal mice and mice in rebound-thrombocytosis, as did TSF, but required large doses (15 U rEpo/mouse). In other mice, hematocrits, platelet counts, platelet sizes, and 24-hr %35S incorporation into platelets were measured 2 days after injection of two equally divided doses of either rEpo or TSF. Significant increases in both platelet sizes and %35S incorporation into platelets were found after injections of 15 U rEpo/mouse or 2.3 U TSF/mouse. These data indicate that rEpo, at high doses, will stimulate platelet production in mice, and may suggest molecular similarities between rEpo and TSF and their ability to compete for common receptor sites on megakaryocytes and their progenitor cells.

  6. Regulation of cadherin-mediated adhesion in morphogenesis.

    Science.gov (United States)

    Gumbiner, Barry M

    2005-08-01

    Cadherin cell-adhesion proteins mediate many facets of tissue morphogenesis. The dynamic regulation of cadherins in response to various extracellular signals controls cell sorting, cell rearrangements and cell movements. Cadherins are regulated at the cell surface by an inside-out signalling mechanism that is analogous to the integrins in platelets and leukocytes. Signal-transduction pathways impinge on the catenins (cytoplasmic cadherin-associated proteins), which transduce changes across the membrane to alter the state of the cadherin adhesive bond.

  7. Effect of platelet orientation on the properties of alumina platelet zirconia matrix composites

    DEFF Research Database (Denmark)

    Toft Sørensen, O.; Li, W.-Y.

    1996-01-01

    Platelet alignment in Al2O3pl - TZ3YS composites formed by injection moulding, slip casting, and tape casting, has been examined. Mechanical properties have been determined in terms of flexural strength and fracture toughness, with respect to materials formed by different techniques......, and to the platelet orientation. Materials produced by injection moulding exhibited fewer and smaller internal defects, compared to the slip casting and tape casting, thus giving rise to the maximum average strength. The fracture toughness showed more increase for samples with stronger textures, ie. platelet...... alignment. The results also indicated that there was a trend of higher K-IC value when cracks were propagating parallel to the platelet surface (nor delamination). Thermal shock resistance of the injection moulded composite has been characterized by water quench test. Delta T-c for the composite was between...

  8. 间接稀释法在EDTA依赖性假性血小板减少症中的临床应用%Clinical application of indirect platelet suspension immunofluorescence tests in EDTA-dependent pseudo-thrombocytopenia

    Institute of Scientific and Technical Information of China (English)

    陈宇; 王琳; 沈涌海; 丁成国

    2015-01-01

    Objective Taking manual ammonium oxalate method for quality evaluation to check thereliability of indirect platelet suspension immunofluorescence tests with automated hematology analyser for EDTA-dependent pseudo-thrombocytopenia detection,and provide basis for the laboratory examinations.Methods The blood samples of 50 EDTA-dependent pseudothrombocyopenia were tested at 0-5,10,20,30,60 and 120 minute by automated hematology analyser in whole blood mode and indirect dilution modeand manual ammonium oxalate method.The platelet counts were rechecked by microscope.Results The results of platelet counts in 0-5 minute by three methods were basically identical (P > 0.05).In 10,20,30,60 and 120 minute after the collection of blood,there was no significant difference in the platelet counts between by indirect dilution mode and handcraft method(P > 0.05),was significant between whole blood modeandhandcraft method(P < 0.05).Conclusion The indirect platelet suspension immunofluorescence test is suitable for the platelet counts for the EDTA-dependent pseudo-thrombocytopenia samples,which can reduce the patients' pain,decrease the cost of laboratory,and improve the quality of medical.It can be used as one of the methods for detecting EDTA-PTCP at present.%目的 以手工草酸铵法为质量评价,分析EDTA依赖性假性血小板减少症(EDTA-PTCP)的样本在全自动血细胞分析仪间接稀释模式下的检测结果,为实验室提供简便、可靠的方法依据.方法 采集50例EDTA依赖性假性血小板减少症患者的全血样本,结合显微镜复检规则,应用全血细胞分析法、仪器间接稀释法、手工草酸铵法在0~5 min、10 min、20 min、30 min、60 min、120 min同时对EDTA-PTCP样本进行检测.结果 患者标本采集0 ~5 min内,3种方法测定的血小板数值基本一致(P>0.05);采血后10 min、20 min、30 min、60 min、120 min时仪器间接稀释法与手工草酸铵法对血小板检测值基本一致(P>0

  9. Effective estimation of correct platelet counts in pseudothrombocytopenia using an alternative anticoagulant based on magnesium salt

    OpenAIRE

    2013-01-01

    Pseudothrombocytopenia remains a challenge in the haematological laboratory. The pre-analytical problem that platelets tend to easily aggregate in vitro, giving rise to lower platelet counts, has been known since ethylenediamine-tetra acetic acid EDTA and automated platelet counting procedures were introduced in the haematological laboratory. Different approaches to avoid the time and temperature dependent in vitro aggregation of platelets in the presence of EDTA were tested, but none of them...

  10. Biochemical lesions of platelets stored as concentrates in PVC bags.

    Science.gov (United States)

    Krishnan, L K; Mathai, J; Sulochana, P V; Jacob, J; Sivakumar, R

    1997-02-01

    Acid-base status of platelet suspension during storage is a measure of the gas permeability of the bag material. To assess the efficacy of the bags available in our market to store platelets, we compared biochemical lesions of platelets stored in an Indian polyvinyl chloride (PVC) triple bag against a Japanese PVC bag standardized for 5 days platelet storage. Platelet concentrates prepared in both control and test PVC bags were stored for 72 h. Two ml samples were drawn 1 h after preparation, and then at 24 h intervals, for analysis. Our data show that the mean pH value in the test bags was maintained above 6.5. However, the CO2 tension was high and O2 tension was low. We also analyzed malondialdehyde (MDA) formation which is a measure of arachidonic acid metabolism, and seemed to be unaffected in stored platelets. Lactate dehydrogenase (LDH) was not released into the plasma excessively and hence significant platelet lysis was absent during storage. Hypotonic shock response (HSR) of platelets stored in both test and control bags was comparable, indicating the possibility of satisfactory post-transfusion recovery.

  11. Cleaning properties of dry adhesives

    Institute of Scientific and Technical Information of China (English)

    J.; P.; DíAZ; TéLLEZ; D.; SAMEOTO; C.; MENON

    2010-01-01

    In this paper we present a study into the cleaning properties of synthetic dry adhesives. We have manufactured the adhesive micro-fibres through a low-cost, high yield fabrication method using Sylgard 184 Polydimethylsiloxane (PDMS) as the structural material. We deliberately contaminated the adhesive samples with different sized particles in the micro and macro scales and tested different cleaning methods for their efficacy with respect to each particle size. We investigated different cleaning methods, which included the use of wax moulding, vibration and pressure sensitive adhesives. For adhesion testing we used a custom system with a linear stage and a force sensor indenting a hemispherical probe into the adhesive surface and measuring the pull-off force. To characterize the cleaning efficacy we visually inspected each sample in a microscope and weighed the samples with a microgram-accuracy analytical balance. Results showed that the moulding method induced adhesion recovery in a greater percentage than the other cleaning methods and even helped with the recovery of collapsed posts in some cases. On the other hand pressure sensitive adhesives seem to have the upper hand with regards to certain particle sizes that can potentially pose problems with the moulding method.

  12. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong

    2010-12-01

    Full Text Available Sudden cardiac death remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g. serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products.

  13. Effect of construction of TiO2 nanotubes on platelet behaviors: Structure-property relationships.

    Science.gov (United States)

    Huang, Qiaoling; Yang, Yun; Zheng, Dajiang; Song, Ran; Zhang, Yanmei; Jiang, Pinliang; Vogler, Erwin A; Lin, Changjian

    2017-03-15

    Blood compatibility of TiO2 nanotubes (TNTs) has been assessed in rabbit platelet-rich plasma (PRP), which combines activation of both blood plasma coagulation and platelets. We find that (i) amorphous TiO2 nanotubes (TNTs) with relatively larger outer diameters led to reduced platelet adhesion/activation, (ii) TNTs with relatively smaller outer diameters in a predominately rutile phase also inhibited platelet adhesion and activation, and (iii) a pervasive fibrin network formed on larger outer diameter TNTs in a predominately anatase phase. Thus, this study suggests that combined effect of crystalline phase and surface chemistry controls blood-contact behavior of TNTs. A more comprehensive mechanism is proposed for understanding hemocompatibility of TiO2 which might prove helpful as a guide to prospective design of TiO2-based biomaterials.

  14. Effects of argon laser on in vitro aggregation of platelets in platelet rich plasma and whole blood

    Energy Technology Data Exchange (ETDEWEB)

    Doerger, P.T.; Glueck, H.I.; McGill, M.

    1988-06-01

    The effects of an Argon laser on platelet aggregation were studied, since platelets may be exposed to laser energy when used intravascularly. Various preparations of platelets in platelet rich plasma (PRP) and whole blood, with or without aspirin, were tested with the aggregating agents ADP, collagen, thrombin, and epinephrine. Simultaneous release of ATP was also measured in PRP. At relatively low levels of irradiation, platelet aggregation was potentiated. Enhancement was evidenced by an increase in percent aggregation, earlier onset of the reaction, and reduction in the amount of aggregating agent required. In PRP, the mechanism of laser potentiation appeared to be the release of endogenous ATP from platelets. At relatively high levels of irradiation, platelets were destroyed and aggregation abolished. In whole blood, the mechanism was somewhat more complicated since release of ATP occurred from RBCs as well as platelets. Spontaneous aggregation following laser treatment occurred in isolated instances in PRP and in every trial in whole blood preparations. Aspirin ingestion inhibited the laser's effects in PRP but not in whole blood. These results may have important clinical implications for laser angioplasty, and the potentiated aggregation response may prove useful in laboratory studies of platelet function.

  15. Selective inhibition of the platelet phosphoinositide 3-kinase p110beta as promising new strategy for platelet protection during extracorporeal circulation.

    Science.gov (United States)

    Straub, Andreas; Wendel, Hans Peter; Dietz, Klaus; Schiebold, Daniela; Peter, Karlheinz; Schoenwaelder, Simone M; Ziemer, Gerhard

    2008-03-01

    Extracorporeal circulation (ECC) is used in cardiac surgery for cardiopulmonary bypass as well as in ventricular assist devices and for extracorporeal membrane oxygenation. Blood contact with the artificial surface and shear stress of ECC activates platelets and leukocytes resulting in a coagulopathy and proinflammatory events. Blockers of the platelet glycoprotein (GP) IIb/IIIa (CD41/CD61) can protect platelet function during ECC, a phenomenon called "platelet anaesthesia", but may be involved in post-ECC bleeding. We hypothesized that the new selective phosphoinositide 3-kinase p110beta inhibitor TGX-221 that inhibits shear-induced platelet activation without prolonging the bleeding time in vivo may also protect platelet function during ECC. Heparinized blood of healthy volunteers (n = 6) was treated in vitro with either the GP IIb/IIIa blocker tirofiban, TGX-221 or as control and circulated in an ECC model. Before and after 30 minutes circulation CD41 expression on the ECC-tubing as measure for platelet-ECC binding and generation of the platelet activation marker beta-thromboglobulin were determined using ELISA. Platelet aggregation and platelet-granulocyte binding were analysed in flow cytometry. After log-transforming the data statistical evaluation was performed using multifactor ANOVA in combination with Tukey's HSD test (global alpha = 5%). Tirofiban and TGX-221 inhibited platelet-ECC interaction, platelet aggregation and platelet-granulocyte binding. Tirofiban also inhibited ECC-induced beta-thromboglobulin release. The observed inhibition of platelet-ECC interaction and platelet activation by tirofiban contributes to explain the mechanism of "platelet anaesthesia". TGX-221 represents a promising alternative to GP IIb/IIIa blockade and should be further investigated for use during ECC in vivo.

  16. Improved Adhesion and Compliancy of Hierarchical Fibrillar Adhesives.

    Science.gov (United States)

    Li, Yasong; Gates, Byron D; Menon, Carlo

    2015-08-01

    The gecko relies on van der Waals forces to cling onto surfaces with a variety of topography and composition. The hierarchical fibrillar structures on their climbing feet, ranging from mesoscale to nanoscale, are hypothesized to be key elements for the animal to conquer both smooth and rough surfaces. An epoxy-based artificial hierarchical fibrillar adhesive was prepared to study the influence of the hierarchical structures on the properties of a dry adhesive. The presented experiments highlight the advantages of a hierarchical structure despite a reduction of overall density and aspect ratio of nanofibrils. In contrast to an adhesive containing only nanometer-size fibrils, the hierarchical fibrillar adhesives exhibited a higher adhesion force and better compliancy when tested on an identical substrate.

  17. Stretchable, adhesion-tunable dry adhesive by surface wrinkling.

    Science.gov (United States)

    Jeong, Hoon Eui; Kwak, Moon Kyu; Suh, Kahp Y

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (approximately 10.8 N/cm(2)) and shear adhesion (approximately 14.7 N/cm(2)) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of approximately 3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of approximately 0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment.

  18. Stretchable, Adhesion-Tunable Dry Adhesive by Surface Wrinkling

    KAUST Repository

    Jeong, Hoon Eui

    2010-02-16

    We introduce a simple yet robust method of fabricating a stretchable, adhesion-tunable dry adhesive by combining replica molding and surface wrinkling. By utilizing a thin, wrinkled polydimethyl siloxane (PDMS) sheet with a thickness of 1 mm with built-in micropillars, active, dynamic control of normal and shear adhesion was achieved. Relatively strong normal (∼10.8 N/cm2) and shear adhesion (∼14.7 N/cm2) forces could be obtained for a fully extended (strained) PDMS sheet (prestrain of∼3%), whereas the forces could be rapidly reduced to nearly zero once the prestrain was released (prestrain of ∼0.5%). Moreover, durability tests demonstrated that the adhesion strength in both the normal and shear directions was maintained over more than 100 cycles of attachment and detachment. © 2010 American Chemical Society.

  19. Changes in albumin/platelet interaction with an artificial surface--due to a antibiotics, pyridoxal phosphate, and lymphocytes

    Energy Technology Data Exchange (ETDEWEB)

    Chandy, T.; Sharma, C.P.

    1988-04-01

    Protein adsorption and platelet adhesion are two important biological processes arising at the blood prosthetic interface. The effect of certain antibiotics, namely, neomycin, gentamicin, ampicillin, penicillin-G, and streptomycin to modulate the albumin polycarbonate surface interaction was investigated using /sup 125/I albumin from a protein mixture in the presence and absence of isolated calf lymphocytes. This study also demonstrated the changes in platelet-surface adhesion with these antibiotics. The effect of pyridoxal phosphate to modulate the red blood cell-mediated platelet-surface attachment was also attempted. It appears from pyridoxal phosphate studies that pyridoxal 5'-phosphate (PLP) could modify the surface-platelet attachment. It also inhibited the fibrinogen-induced platelet adhesion. It seems, the addition of antibiotics to the polymerprotein system increased the level of surface-bound albumin variably whereas lymphocytes incubated in the medium did not affect the surface-albumin concentration with time course. These antibiotics also inhibited the surface-induced platelet adhesion to variable degrees. Our earlier studies have indicated that certain antibiotics or antiplatelet drugs can inhibit the fibrinogen binding to an artificial surface. Therefore, it may be possible that the enhanced albumin-surface concentration or reduced fibrinogen-surface binding, in the presence of these antibiotics, may itself be one of the parameter for a reduced platelet-surface attachment, which may also improve the blood compatibility of the substrate. A better understanding of the mechanism of antibiotics is needed in in vivo conditions to correlate these findings.

  20. Adhesive plasters

    Science.gov (United States)

    Holcombe, Jr., Cressie E.; Swain, Ronald L.; Banker, John G.; Edwards, Charlene C.

    1978-01-01

    Adhesive plaster compositions are provided by treating particles of Y.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Gd.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 with dilute acid solutions. The resulting compositions have been found to spontaneously harden into rigid reticulated masses resembling plaster of Paris. Upon heating, the hardened material is decomposed into the oxide, yet retains the reticulated rigid structure.

  1. Effect of swirling flow on platelet concentration distribution in small-caliber artificial grafts and end-to-end anastomoses

    Institute of Scientific and Technical Information of China (English)

    Fan Zhan; Yu-Bo Fan; Xiao-Yan Deng

    2011-01-01

    Platelet concentration near the blood vessel wall is one of the major factors in the adhesion of platelets to the wall.In our previous studies,it was found that swirling flows could suppress platelet adhesion in small-caliber artificial grafts and end-to-end anastomoses.In order to better understand the beneficial effect of the swirling flow,we numerically analyzed the near-wall concentration distribution of platelets in a straight tube and a sudden tubular expansion tube under both swirling flow and normal flow conditions.The numerical models were created based on our previous experimental studies.The simulation results revealed that when compared with the normal flow,the swirling flow could significantly reduce the near-wall concentration of platelets in both the straight tube and the expansion tube.The present numerical study therefore indicates that the reduction in platelet adhesion under swirling flow conditions in small-caliber arterial grafts,or in end-to-end anastomoses as observed in our previous experimental study,was possibly through a mechanism of platelet transport,in which the swirling flow reduced the near-wall concentration of platelets.

  2. Investigation of platelet function and platelet disorders using flow cytometry.

    Science.gov (United States)

    Rubak, Peter; Nissen, Peter H; Kristensen, Steen D; Hvas, Anne-Mette

    2016-01-01

    Patients with thrombocytopenia or platelet disorders are at risk of severe bleeding. We report the development and validation of flow cytometry assays to diagnose platelet disorders and to assess platelet function independently of platelet count. The assays were developed to measure glycoprotein levels (panel 1) and platelet function (panel 2) in sodium citrated blood. Twenty healthy volunteers and five patients diagnosed with different platelet disorders were included. Glycoprotein expression levels of the receptors Ia, Ib, IIb, IIIa and IX were measured and normalised with forward scatter (FS) as a measurement of platelet size. Platelet function was assessed by CD63, P-selectin and bound fibrinogen in response to arachidonic acid, adenosine diphosphate (ADP), collagen-related peptide, ristocetin and thrombin receptor-activation peptide-6. All patients except one with suspected δ-granule defect showed aberrant levels of glycoproteins in panel 1. Glanzmann's thrombasthenia and genetically verified Bernard-Soulier syndrome could be diagnosed using panel 1. All patients showed reduced platelet function according to at least one agonist. Using panel 2 it was possible to diagnose Bernard-Soulier syndrome, δ-granule defect and GPVI disorder. By combining the two assays, we were able to diagnose different platelet disorders and investigate platelet function independent of platelet count.

  3. Reproducibility of Manual Platelet Estimation Following Automated Low Platelet Counts

    Directory of Open Access Journals (Sweden)

    Zainab S Al-Hosni

    2016-11-01

    Full Text Available Objectives: Manual platelet estimation is one of the methods used when automated platelet estimates are very low. However, the reproducibility of manual platelet estimation has not been adequately studied. We sought to assess the reproducibility of manual platelet estimation following automated low platelet counts and to evaluate the impact of the level of experience of the person counting on the reproducibility of manual platelet estimates. Methods: In this cross-sectional study, peripheral blood films of patients with platelet counts less than 100 × 109/L were retrieved and given to four raters to perform manual platelet estimation independently using a predefined method (average of platelet counts in 10 fields using 100× objective multiplied by 20. Data were analyzed using intraclass correlation coefficient (ICC as a method of reproducibility assessment. Results: The ICC across the four raters was 0.840, indicating excellent agreement. The median difference of the two most experienced raters was 0 (range: -64 to 78. The level of platelet estimate by the least-experienced rater predicted the disagreement (p = 0.037. When assessing the difference between pairs of raters, there was no significant difference in the ICC (p = 0.420. Conclusions: The agreement between different raters using manual platelet estimation was excellent. Further confirmation is necessary, with a prospective study using a gold standard method of platelet counts.

  4. 吸附垫仿生研究及其性能测试%Biomimtic Research and Property Test of Adhesive Pads

    Institute of Scientific and Technical Information of China (English)

    周群; 盛莉; 袁贵彬

    2011-01-01

    Adhesion system on animal pads can be divided into setae pads and smooth pads.Relative to setae pads, there are less research on morphology of the smooth pads and its wet adhesion.Katydids were chosen here to be tested, there were smooth adhesive pads on katydid's feet.Depending on the pads and hooks on the pads'terminal, katydids can climb on vertical walls.In order to uncover construction and mechanical properties of the pads, atomic fore microscope was used to observe morphology of the pads, and Nano Indenter was also used to test modulus of elasticity.The results showed that there were specially designed hexagonal patterns, which were the same as tree frogs's pads.The pad is very soft and elastic, just likes silicon rubber.Characteristics of the pad is important for sufficient friction and adhesion.The results can provide information for biomimetic adhesive feet on robots.%动物足掌的吸附系统可分为刚毛型和光滑表皮垫型.相叶于刚毛型,对光滑型足垫的形态学以及与湿吸机制有关的功能的研究非常少.以螽斯为研究对象,螽斯足上拥有光滑的吸附垫,靠足垫和足末端的钩子螽斯可以在竖直壁面爬行.为揭开足垫的构造及其力学特性,用原子力显微镜观察其表面的微观形貌,并用纳米压痕仪测试足垫的弹性模量.结果:表明螽斯足垫表面和树蛙一样拥有特殊设计的五边形和六边形花纹,花纹之间有相通的细沟槽,沟槽内的黏液腺产生分泌液,从而在接触表面产生湿吸力.足垫非常柔软有弹性,足垫表面的弹性模量大小分布比较均匀,平均有效弹性模量为87KPa,类似于硅橡胶.足垫的这些特点对产生较大的摩擦力和吸附力是非常重要的.研究结果可为机器人仿生吸附垫的研制提供参考.

  5. [Effects of two trypanosomicide drugs, gention violet and WR6026, on platelet concentrates preservation].

    Science.gov (United States)

    Soares, Sheila; Moraes-Souza, Hélio; Tostes, Maria Aparecida Vieira; Lourenço, Dayse Maria

    2004-01-01

    In order to verify the viability of platelet concentrate during its preservation period when added with two trypanosomicidal chemical substances, gentian violet and quinoline WR6026, we tested these concentrates and verified the following parameters: number of platelets, pH and platelet aggregation test with a pair of agonists. Significant alterations were observed in the platelet concentrate treated with gentian violet suggesting important damage to the platelet viability. With WR6026 similar values to the controls were observed, opening new perspectives for the utilization of this salt for the chemoprophylaxis of transfusional Chagas' disease in highly endemic regions.

  6. Differential proteomic analysis of platelets suggested possible signal cascades network in platelets treated with salvianolic acid B.

    Directory of Open Access Journals (Sweden)

    Chao Ma

    Full Text Available BACKGROUND: Salvianolic acid B (SB is an active component isolated from Danshen, a traditional Chinese medicine widely used for the treatment of cardiovascular disorders. Previous study suggested that SB might inhibit adhesion as well as aggregation of platelets by a mechanism involving the integrin α2β1. But, the signal cascades in platelets after SB binding are still not clear. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, a differential proteomic analysis (two-dimensional electrophoresis was conducted to check the protein expression profiles of rat platelets with or without treatment of SB. Proteins altered in level after SB exposure were identified by MALDI-TOF MS/MS. Treatment of SB caused regulation of 20 proteins such as heat shock-related 70 kDa protein 2 (hsp70, LIM domain protein CLP-36, copine I, peroxiredoxin-2, coronin-1 B and cytoplasmic dynein intermediate chain 2C. The regulation of SB on protein levels was confirmed by Western blotting. The signal cascades network induced by SB after its binding with integrin α2β1 was predicted. To certify the predicted network, binding affinity of SB to integrin α2β1 was checked in vitro and ex vivo in platelets. Furthermore, the effects of SB on protein levels of hsp70, coronin-1B and intracellular levels of Ca²+ and reactive oxygen species (ROS were checked with or without pre-treatment of platelets using antibody against integrin α2β1. Electron microscopy study confirmed that SB affected cytoskeleton structure of platelets. CONCLUSIONS/SIGNIFICANCE: Integrin α2β1 might be one of the direct target proteins of SB in platelets. The signal cascades network of SB after binding with integrin α2β1 might include regulation of intracellular Ca²+ level, cytoskeleton-related proteins such as coronin-1B and cytoskeleton structure of platelets.

  7. Differential Proteomic Analysis of Platelets Suggested Possible Signal Cascades Network in Platelets Treated with Salvianolic Acid B

    Science.gov (United States)

    Ma, Chao; Yao, Yan; Yue, Qing-Xi; Zhou, Xin-Wen; Yang, Peng-Yuan; Wu, Wan-Ying; Guan, Shu-Hong; Jiang, Bao-Hong; Yang, Min; Liu, Xuan; Guo, De-An

    2011-01-01

    Background Salvianolic acid B (SB) is an active component isolated from Danshen, a traditional Chinese medicine widely used for the treatment of cardiovascular disorders. Previous study suggested that SB might inhibit adhesion as well as aggregation of platelets by a mechanism involving the integrin α2β1. But, the signal cascades in platelets after SB binding are still not clear. Methodology/Principal Findings In the present study, a differential proteomic analysis (two-dimensional electrophoresis) was conducted to check the protein expression profiles of rat platelets with or without treatment of SB. Proteins altered in level after SB exposure were identified by MALDI-TOF MS/MS. Treatment of SB caused regulation of 20 proteins such as heat shock-related 70 kDa protein 2 (hsp70), LIM domain protein CLP-36, copine I, peroxiredoxin-2, coronin-1 B and cytoplasmic dynein intermediate chain 2C. The regulation of SB on protein levels was confirmed by Western blotting. The signal cascades network induced by SB after its binding with integrin α2β1 was predicted. To certify the predicted network, binding affinity of SB to integrin α2β1 was checked in vitro and ex vivo in platelets. Furthermore, the effects of SB on protein levels of hsp70, coronin-1B and intracellular levels of Ca(2+) and reactive oxygen species (ROS) were checked with or without pre-treatment of platelets using antibody against integrin α2β1. Electron microscopy study confirmed that SB affected cytoskeleton structure of platelets. Conclusions/Significance Integrin α2β1 might be one of the direct target proteins of SB in platelets. The signal cascades network of SB after binding with integrin α2β1 might include regulation of intracellular Ca(2+) level, cytoskeleton-related proteins such as coronin-1B and cytoskeleton structure of platelets. PMID:21379382

  8. Detection of platelet deposition at the site of peripheral balloon angioplasty using indium-111 platelet scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Pope, C.F.; Ezekowitz, M.D.; Smith, E.O.; Rapoport, S.; Glickman, M.; Sostman, H.D.; Zaret, B.L.

    1985-02-01

    Restenosis after balloon angioplasty may be mediated through platelet deposition at the site of arterial dilatation. The purpose of this study was to determine whether platelet deposition at the site of dilatation could be detected using indium-111 platelet scintigraphy. Fifteen patients, aged 60 +/- 9 years, with iliac or femoral (n . 12), renal artery (n . 2) or distal aortic (n . 1) stenoses were studied. All patients received intravenous heparin at the time of dilatation. Labeled platelets containing 471 +/- 65 muCi indium-111 were injected 0.25 to 4 hours after dilatation and 1 to 24 hours after imaging. In 11 of 12 patients with iliac and femoral dilatations, focal uptake was demonstrated at the angioplasty site. In 4 patients (2 patients with renal, 1 patient with iliofemoral, and 1 with distal aortic stenoses), uptake at the dilatation sites was not detected. This preliminary study indicates that despite intravenous heparin, platelets accumulate at sites of balloon dilatation. Platelet scintigraphy may be useful in predicting sites of future narrowing after angioplasty and may be used to test the efficacy of antiplatelet therapy in retarding restenosis.

  9. Inherited platelet disorders: Insight from platelet genomics using next-generation sequencing.

    Science.gov (United States)

    Maclachlan, Annabel; Watson, Steve P; Morgan, Neil V

    2017-01-01

    Inherited platelet disorders (IPDs) are a heterogeneous group of disorders associated with normal or reduced platelet counts and bleeding diatheses of varying severities. The identification of the underlying cause of IPDs is clinically challenging due to the absence of a gold-standard platelet test, and is often based on a clinical presentation and normal values in other hematology assays. As a consequence, a DNA-based approach has a potentially important role in the investigation of these patients. Next-generation sequencing (NGS) technologies are allowing the rapid analysis of genes that have been previously implicated in IPDs or that are known to have a key role in platelet regulation, as well as novel genes that have not been previously implicated in platelet dysfunction. The potential limitations of NGS arise with the interpretation of the sheer volume of genetic information obtained from whole exome sequencing (WES) or whole genome sequencing (WGS) in order to identify function-disrupting variants. Following on from bioinformatic analysis, a number of candidate genetic variants usually remain, therefore adding to the difficulty of phenotype-genotype segregation verification. Linking genetic changes to an underlying bleeding disorder is an ongoing challenge and may not always be feasible due to the multifactorial nature of IPDs. Nevertheless, NGS will play a key role in our understanding of the mechanisms of platelet function and the genetics involved.

  10. Functional display of platelet-binding VWF fragments on filamentous bacteriophage.

    Directory of Open Access Journals (Sweden)

    Andrew Yee

    Full Text Available von Willebrand factor (VWF tethers platelets to sites of vascular injury via interaction with the platelet surface receptor, GPIb. To further define the VWF sequences required for VWF-platelet interaction, a phage library displaying random VWF protein fragments was screened against formalin-fixed platelets. After 3 rounds of affinity selection, DNA sequencing of platelet-bound clones identified VWF peptides mapping exclusively to the A1 domain. Aligning these sequences defined a minimal, overlapping segment spanning P1254-A1461, which encompasses the C1272-C1458 cystine loop. Analysis of phage carrying a mutated A1 segment (C1272/1458A confirmed the requirement of the cystine loop for optimal binding. Four rounds of affinity maturation of a randomly mutagenized A1 phage library identified 10 and 14 unique mutants associated with enhanced platelet binding in the presence and absence of botrocetin, respectively, with 2 mutants (S1370G and I1372V common to both conditions. These results demonstrate the utility of filamentous phage for studying VWF protein structure-function and identify a minimal, contiguous peptide that bind to formalin-fixed platelets, confirming the importance of the VWF A1 domain with no evidence for another independently platelet-binding segment within VWF. These findings also point to key structural elements within the A1 domain that regulate VWF-platelet adhesion.

  11. Surface modification of tantalum pentoxide coatings deposited by magnetron sputtering and correlation with cell adhesion and proliferation in in vitro tests

    Science.gov (United States)

    Zykova, A.; Safonov, V.; Goltsev, A.; Dubrava, T.; Rossokha, I.; Donkov, N.; Yakovin, S.; Kolesnikov, D.; Goncharov, I.; Georgieva, V.

    2016-03-01

    The effect was analyzed of surface treatment by argon ions on the surface properties of tantalum pentoxide coatings deposited by reactive magnetron sputtering. The structural parameters of the as-deposited coatings were investigated by means of transmission electron microscopy, atomic force microscopy and scanning electron microscopy. X-ray diffraction profiles and X-ray photoelectron spectra were also acquired. The total surface free energy (SFE), the polar, dispersion parts and fractional polarities, were estimated by the Owens-Wendt-Rabel-Kaeble method. The adhesive and proliferative potentials of bone marrow cells were evaluated for both Ta2O5 coatings and Ta2O5 coatings deposited by simultaneous bombardment by argon ions in in vitro tests.

  12. Preliminary reliability test of lateral-current-injection GaInAsP/InP membrane distributed feedback laser on Si substrate fabricated by adhesive wafer bonding

    Science.gov (United States)

    Fukuda, Kai; Inoue, Daisuke; Hiratani, Takuo; Amemiya, Tomohiro; Nishiyama, Nobuhiko; Arai, Shigehisa

    2017-02-01

    A preliminary reliability test was performed for lateral-current-injection GaInAsP/InP membrane Distributed Feedback (DFB) lasers fabricated by multi-regrowth and adhesive wafer bonding. The measurement was conducted for lasers with two different types of p-side electrode: Ti/Au and Au/Zn/Au. The device with the Au/Zn/Au electrode, which had better current-voltage (I-V) characteristics, showed no degradation of differential quantum efficiency and threshold current after continuous aging for 310 h at a bias current density of 5 kA/cm2. This result indicates that the multi-regrowth and bonding process for the GaInAsP/InP membrane DFB laser will not impact the initial reliability.

  13. Assessment of the correlation of platelet morphology with in vivo recovery and survival.

    Science.gov (United States)

    Mintz, Paul D; Anderson, Garth; Avery, Nancy; Clark, Pamela; Bonner, Robert F

    2005-08-01

    There is continuing interest in the development of in vitro tests evaluating the in vivo function, recovery, and survival of platelets stored for transfusion. A recent forum concluded that no completely reliable test exists, although discoid morphology indicates a platelet's good health. We evaluated a novel device, the NAPSAC (Noninvasive Assessment of Platelet Shape and Concentration), designed to determine noninvasively the proportion of discoid platelets in a stored concentrate, as well as platelet concentration. Twenty-eight plateletapheresis concentrates stored 24 hours in PL-146 were evaluated. Percent discoid platelet results were correlated with radiolabeled autologous recovery and survival performed using 111Indium oxyquinoline and calculated using linear (L) and multiple-hit (M) models. pH of 8 concentrates was raised at the end of storage with 6N NaOH. Platelet concentration measured by NAPSAC and Coulter Thrombocounter C was compared in 256 plateletapheresis products. Percent discoid platelets at 24 hours did not correlate significantly with platelet recovery or survival (recovery L = 0.29, M = 0.28; survival L = 0.16, M = 0.03). Raising the pH (mean 6.38 to 6.94) resulted in a significant increase in percent discoid platelets (21% to 41%). Platelet concentration values for both methods studied were linearly correlated with a slope of 1.01 +/- 0.03, r = 0.81. Percent discoid platelets was not predictive of posttransfusion platelet recovery or survival. The results suggest that non-discoid platelets may survive posttransfusion and even revert to discoid shape, since raising the pH approximately doubled the percent of discoid platelets. The NAPSAC was shown to be a reliable instrument for noninvasively determining platelet concentration in PL-146 concentrates.

  14. Platelet P2 receptors: from curiosity to clinical targets.

    Science.gov (United States)

    Cusack, N J; Hourani, S M

    2000-07-01

    Adenosine 5'-diphosphate (ADP) is a paracrine mediator that activates human blood platelets, causing them to become adhesive and thereby contributing to their role in hemostasis. The actions of ADP were initially thought to be mediated by a unique ADP receptor termed P2(T) found only on platelets and antagonized by ATP, but it appears that at least two P2Y receptor subtypes are involved, a P2Y(1) receptor linked in some way to control of intracellular-free calcium levels and another P2Y receptor linked via an inhibitory G protein to adenylate cyclase. In addition, the presence of excitatory P2X(1) receptors that mediate the influx of monovalent and divalent cations in response to both ADP and ATP has been demonstrated. The precise contribution that each of these P2 receptors make to the overall phenomena associated with platelet aggregation, adhesion and hemostasis is yet to be defined. Antithrombotic agents that interfere with the actions of ADP are marketed, and P2 receptor antagonists are entering clinical trials for acute treatments of thrombosis. This review seeks to summarize the present state of knowledge of platelet P2 receptor pharmacology and therapeutics.

  15. Equid herpesvirus type 1 activates platelets.

    Directory of Open Access Journals (Sweden)

    Tracy Stokol

    Full Text Available Equid herpesvirus type 1 (EHV-1 causes outbreaks of abortion and neurological disease in horses. One of the main causes of these clinical syndromes is thrombosis in placental and spinal cord vessels, however the mechanism for thrombus formation is unknown. Platelets form part of the thrombus and amplify and propagate thrombin generation. Here, we tested the hypothesis that EHV-1 activates platelets. We found that two EHV-1 strains, RacL11 and Ab4 at 0.5 or higher plaque forming unit/cell, activate platelets within 10 minutes, causing α-granule secretion (surface P-selectin expression and platelet microvesiculation (increased small events double positive for CD41 and Annexin V. Microvesiculation was more pronounced with the RacL11 strain. Virus-induced P-selectin expression required plasma and 1.0 mM exogenous calcium. P-selectin expression was abolished and microvesiculation was significantly reduced in factor VII- or X-deficient human plasma. Both P-selectin expression and microvesiculation were re-established in factor VII-deficient human plasma with added purified human factor VIIa (1 nM. A glycoprotein C-deficient mutant of the Ab4 strain activated platelets as effectively as non-mutated Ab4. P-selectin expression was abolished and microvesiculation was significantly reduced by preincubation of virus with a goat polyclonal anti-rabbit tissue factor antibody. Infectious virus could be retrieved from washed EHV-1-exposed platelets, suggesting a direct platelet-virus interaction. Our results indicate that EHV-1 activates equine platelets and that α-granule secretion is a consequence of virus-associated tissue factor triggering factor X activation and thrombin generation. Microvesiculation was only partly tissue factor and thrombin-dependent, suggesting the virus causes microvesiculation through other mechanisms, potentially through direct binding. These findings suggest that EHV-1-induced platelet activation could contribute to the thrombosis

  16. Investigation of scale effects and directionality dependence on friction and adhesion of human hair using AFM and macroscale friction test apparatus.

    Science.gov (United States)

    LaTorre, Carmen; Bhushan, Bharat

    2006-01-01

    Macroscale testing of human hair tribological properties has been widely used to aid in the development of better shampoos and conditioners. Recently, literature has focused on using the atomic force microscope (AFM) to study surface roughness, coefficient of friction, adhesive force, and wear (tribological properties) on the nanoscale in order to increase understanding about how shampoos and conditioners interact with the hair cuticle. Since there are both similarities and differences when comparing the tribological trends at both scales, it is thus recognized that scale effects are an important aspect of studying the tribology of hair. However, no microscale tribological data for hair exists in literature. This is unfortunate because many interactions between hair-skin, hair-comb, and hair-hair contact takes place at microasperities ranging from a few mum to hundreds of mum. Thus, to bridge the gap between the macro- and nanoscale data, as well as to gain a full understanding of the mechanisms behind the trends, it is now worthwhile to look at hair tribology on the microscale. Presented in this paper are coefficient of friction and adhesive force data on various scales for virgin and chemically damaged hair, both with and without conditioner treatment. Macroscale coefficient of friction was determined using a traditional friction test apparatus. Microscale and nanoscale tribological characterization was performed with AFM tips of various radii. The nano-, micro-, and macroscale trends are compared and the mechanisms behind the scale effects are discussed. Since the coefficient of friction changes drastically (on any scale) depending on whether the direction of motion is along or against the cuticle scales, the directionality dependence and responsible mechanisms are discussed.

  17. Investigation of scale effects and directionality dependence on friction and adhesion of human hair using AFM and macroscale friction test apparatus

    Energy Technology Data Exchange (ETDEWEB)

    LaTorre, Carmen [Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), Ohio State University, Suite 255, 650 Ackerman Road, Columbus, OH 43202 (United States); Bhushan, Bharat [Nanotribology Laboratory for Information Storage and MEMS/NEMS (NLIM), Ohio State University, Suite 255, 650 Ackerman Road, Columbus, OH 43202 (United States)]. E-mail: bhushan.2@osu.edu

    2006-06-15

    Macroscale testing of human hair tribological properties has been widely used to aid in the development of better shampoos and conditioners. Recently, literature has focused on using the atomic force microscope (AFM) to study surface roughness, coefficient of friction, adhesive force, and wear (tribological properties) on the nanoscale in order to increase understanding about how shampoos and conditioners interact with the hair cuticle. Since there are both similarities and differences when comparing the tribological trends at both scales, it is thus recognized that scale effects are an important aspect of studying the tribology of hair. However, no microscale tribological data for hair exists in literature. This is unfortunate because many interactions between hair-skin, hair-comb, and hair-hair contact takes place at microasperities ranging from a few {mu}m to hundreds of {mu}m. Thus, to bridge the gap between the macro- and nanoscale data, as well as to gain a full understanding of the mechanisms behind the trends, it is now worthwhile to look at hair tribology on the microscale. Presented in this paper are coefficient of friction and adhesive force data on various scales for virgin and chemically damaged hair, both with and without conditioner treatment. Macroscale coefficient of friction was determined using a traditional friction test apparatus. Microscale and nanoscale tribological characterization was performed with AFM tips of various radii. The nano-, micro-, and macroscale trends are compared and the mechanisms behind the scale effects are discussed. Since the coefficient of friction changes drastically (on any scale) depending on whether the direction of motion is along or against the cuticle scales, the directionality dependence and responsible mechanisms are discussed.

  18. Caspase-9 mediates the apoptotic death of megakaryocytes and platelets, but is dispensable for their generation and function.

    Science.gov (United States)

    White, Michael J; Schoenwaelder, Simone M; Josefsson, Emma C; Jarman, Kate E; Henley, Katya J; James, Chloé; Debrincat, Marlyse A; Jackson, Shaun P; Huang, David C S; Kile, Benjamin T

    2012-05-03

    Apoptotic caspases, including caspase-9, are thought to facilitate platelet shedding by megakaryocytes. They are known to be activated during platelet apoptosis, and have also been implicated in platelet hemostatic responses. However, the precise requirement for, and the regulation of, apoptotic caspases have never been defined in either megakaryocytes or platelets. To establish the role of caspases in platelet production and function, we generated mice lacking caspase-9 in their hematopoietic system. We demonstrate that both megakaryocytes and platelets possess a functional apoptotic caspase cascade downstream of Bcl-2 family-mediated mitochondrial damage. Caspase-9 is the initiator caspase, and its loss blocks