1,721,069 research outputs found
Valutazione del sistema Capillarys 2 Flex Piercing per la misura dell'emoglobina A1c = Evaluation of the Capillarys 2 Flex Piercing system for the determination of hemoglobin A1c (HbA1c)
No full textThe Capillarys HbA1c kit implemented on the Capillarys 2 Flex Piercing platform uses capillary electrophoresis to separate
and quantify HbA1c in human blood. We performed an evaluation of this system by checking imprecision, relative bias
and robustness respect to the analysis of samples with variable total hemoglobin concentrations. Intra-assay CVs were
between 1.1% and 2.8% for HbA1c values between 35.8 mmol/mol and 96.4 mmol/mol. Inter-assay CVs, evaluated on
control materials, were 2.0% and 2.4 % for high (68.6 mmol/mol) and low (36.8 mmol/mol) control levels, respectively.
Results in three blood samples with various concentrations of HbA1c (36, 60 and 87 mmol/mol) were not affected by
variation in total hemoglobin concentrations (between 40 to 180 g/L). Only at very low total hemoglobin concentration,
the imprecision was slightly higher (CV 3.1%). The results obtained by capillary electrophoresis (y-method) were well
correlated with those obtained by the HPLC Tosoh G8 (x-method) (y = 0.73 + 0.978x, r=0.998, n=100)
Standardizzazione dell’emoglobina glicata nell’ambito dello studio DAI
No full textThe results obtained from 85 antidiabetic centers enrolled in the DAI study are presented with regard to the external quality assessment scheme for glycohemoglobin. The materials have been prepared by a laboratory of the network of reference laboratories of the International Federation of Clinical Chemistry (IFCC). To each control a Diabetes Control and Complications Trial (DCCT) traceable target value was assigned. The High-Performance Liquid Chromatography (HPLC) methods for glycohemoglobin are used in 75% of the centers, the immunochemical techniques in 21% and less than 5% is using affinity chromatography based methods. The data collected from the laboratories who completed the set of measurements show that 64% of the centers are well aligned to the DCCT system. The reproducibility of the methods varied between 3.7 and 5.8% (as CV, %) and has to be improved
I "microarray" a proteine per una medicina personalizzata
No full textOver the last 10 years, DNA microarrays have achieved a robust analytical performance, enabling their use for analyzing the whole transcriptome or for screening thousands of single-nucleotide polymorphisms in a single experiment. DNA microarrays allow scientists to correlate gene expression signatures with disease progression, to screen for disease-specific mutations, and to treat patients according to their individual genetic profiles; however, the real key is proteins and their manifold functions. It is necessary to achieve a greater understanding of not only protein function and abundance but also their role in the development of diseases. Protein concentrations have been shown to reflect the physiological and pathologic state of an organ, tissue, or cells far more directly than DNA, and proteins can be profiled effectively with protein microarrays, which require only a small amount of sample material. Protein microarrays have become well-established tools in basic and applied research, and the first products have already entered the in vitro diagnostics market. This review focuses on protein microarray applications for biomarker discovery and validation, disease diagnosis, and use within the area of personalized medicine. Protein microarrays have proved to be reliable research tools in screening for a multitude of parameters with only a minimal quantity of sample and have enormous potential in applications for diagnostic and personalized medicine. Copyright original
Analysis of red cell membrane proteins by capillary gel electrophoresis
No full textBackground. Several hereditary hemolytic anemias associated with the abnormal red cell shapes, such as hereditary spherocytosis (HS) and elliptocytosis (HE) are caused by defects of red cell membrane proteins. The detection of these abnormalities is usually performed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) (1), a time-consuming and lab-intensive technique. Therefore, aim of this study was to set up a method based on SDS-capillary gel electrophoresis (SDS-CGE) for the separation and quantification of major erythrocyte membrane proteins.
Methods. Twenty whole blood samples in EDTA without any apparent sign of hemolysis were collected from the laboratory routine and processed within 2 days. Erythrocytes were separated from platelets and leukocytes and then subjected to a hypotonic treatment (2) in order to prepare red cell ghosts. The analyses of red cell membrane proteins were carried out with a Beckman Coulter ProteomeLab PA800 capillary electrophoresis apparatus equipped with a diode array detector set at 220 nm. The SDS-MW Analysis Kit (Beckman Coulter Inc.), including molecular mass standard proteins, was used. The abundances of the main membrane proteins were quantified by expressing their relative concentrations respect to band 5 (actin).
Results. Seven major erythrocyte membrane proteins were separated and identified: α- and β-spectrin, and bands 3, 4.1, 4.2, 5 and 6. The molecular weights of all these proteins were in good agreement with those reported in literature (3). Reproducibility (expressed as CV, %) of the migration times were between 0.1 % and 0.2 %. Reproducibility of the relative abundances of the main red cell membrane proteins were between 4.5 % (band 4.1/band 5) and 16.4 % (band 6/band 5).
Conclusions. The preliminary results obtained in our investigation prove that SDS-CGE may be an alternative approach to standard SDS-PAGE for the identification of red cell membrane disorders
Performance evaluation of Arkray HA-8190V system for measuring glycated hemoglobin
No full textIntroduction: the new fully automated HPLC ion-exchange system ADAMS A1c HA-8190V analyzer, developed by ARKRAY Inc., running in two different modes (Variant and Fast) has been evaluated.
Methods: reproducibility was evaluated according to the EP-15A3 standard. Method comparison was performed on 122 fresh blood samples, according to the EP-9 standard. The system was compared to 3 other HPLC analyzers, based on ion-exchange (Tosoh G11 and Bio-Rad D-100) and boronate affinity chromatography (Trinity Biotech Premier Hb9210). Usability was evaluated by using to a score evaluation system.
Results: reproducibility proved to be very good at normal and high HbA1c concentration, with total CVs always <0.7 %, when HbA1c was expressed in mmol/mol as well as in % units. The HA-8190V system was well correlated to the other HPLC analyzers, with a mean bias not clinically relevant. Finally, the usability of the system was evaluated and proved to be well acceptable.
Conclusions: the ARKRAY HA-8190 V system was found to be a reliable and suitable method for routine HbA1c measurement in clinical chemistry laboratories
Applicazioni dell'elettroforesi capillare all'analisi delle proteine della membrana eritrocitaria
No full textAnalytical goals for the determination of HbA2
No full textBackground: We present a study aimed to define the analytical goals for the determination of hemoglobin A2 , a minor hemoglobin present in human blood normally accounting from 2.5 % to 3.3 % of total hemoglobin, and typically increased up to 6 % - 7 % in subjects carriers of β -thalassemia. Methods: The analytical goals have been derived using two approaches, the first one based on biologic variation, and the second one based on the opinion of experts. Results: The data obtained by studying 17 adult non-carrier healthy subjects, from whom we took blood samples every 2 weeks for 2.0 months, indicated a small intraindividual biologic variation (CVI of 0.7 % ), with respect to a larger between-subject variation (CVG of 7.7 % ). The minimum levels for imprecision, bias and total error derived from the analysis of these data were: 0.5 % , 2.9 % and 4.5 % , respectively. The limits derived from the opinion of experts were based on a questionnaire with three clinical cases, which was circulated among two teams of international experts, and on a discussion about the clinical needs. The average total error derived from such surveys ranged between 7.0 % and 9.5 % . Conclusions: The various methods to derive analytical performance goals gave different limits, thus indicating the need for an increased communication between clinicians and laboratory professionals on this matter
DEALING WITH NEXT-GENERATION MALWARE
Full text linkMalicious programs are a serious problem that threatens the security of billions of Internet users. Today's malware authors are motivated by the easy financial gain they can obtain by selling on the underground market the information stolen from the infected hosts. To maximize their profit, miscreants continuously improve their creations to make them more and more resilient against anti-malware solutions. This increasing sophistication in malicious code led to next-generation malware, a new class of threats that exploit the limitations of state-of-the-art anti-malware products to bypass security protections and eventually evade detection. Unfortunately, current anti-malware technologies are inadequate to face next-generation malware. For this reason, in this dissertation we propose novel techniques to address the shortcomings of defensive technologies and to enhance current state-of-the-art security solutions.
Dynamic behavior-based analysis is a very promising approach to automatically understand the behaviors a malicious program may exhibit at run-time. However, behavior-based solutions still present several limitations. First of all, these techniques may give incomplete results because the execution environments in which they are applied are synthetic and do not faithfully resemble the environments of end-users, the intended targets of the malicious activities. To overcome this problem, we present a new framework for improving behavior-based analysis of suspicious programs, that allows an end-user to delegate security labs the execution and the analysis of a program and to force the program to behave as if it were executed directly in the environment of the former. Our evaluation demonstrated that the proposed framework allows security labs to improve the completeness of the analysis, by analyzing a piece of malware on behalf of multiple end-users simultaneously, while performing a fine-grained analysis of the behavior of the program with no computational cost for the end-users.
Another drawback of state-of-the-art defensive solutions is non-transparency: malicious programs are often able to determine that their execution is being monitored, and thus they can tamper with the analysis to avoid detection, or simply behave innocuously to mislead the anti-malware tool. At this aim, we propose a generic framework to perform complex dynamic system-level analyses of deployed production systems. By leveraging hardware support for virtualization available nowadays on all commodity machines, our framework is completely transparent to the system under analysis and it guarantees isolation of the analysis tools running on top of it. The internals of the kernel of the running system need not to be modified and the whole platform runs unaware of the framework. Once the framework has been installed, even kernel-level malware cannot detect it or affect its execution. This is accomplished by installing a minimalistic virtual machine monitor and migrating the system, as it runs, into a virtual machine. To demonstrate the potentials of our framework we developed an interactive kernel debugger, named HyperDbg. As HyperDbg can be used to monitor any critical system component, it is suitable to analyze even malicious programs that include kernel-level modules.
Despite all the progress anti-malware technologies can make, perfect malware detection remains an undecidable problem. When it is not possible to prevent a malicious threat from infecting a system, post-infection remediation remains the only viable possibility. However, if the machine has already been compromised, the execution of the remediation tool could be tampered by the malware that is running on the system. To address this problem we present Conqueror, a software-based attestation scheme for tamper-proof code execution on untrusted legacy systems. Besides providing load-time attestation of a piece of code, Conqueror also ensures run-time integrity. Conqueror constitutes a valid alternative to trusted computing platforms, for systems lacking specialized hardware for attestation. We implemented a prototype, specific for the Intel x86 architecture, and evaluated the proposed scheme. Our evaluation showed that, compared to competitors, Conqueror is resistant to both static and dynamic attacks.
We believe Conqueror and our transparent dynamic analysis framework constitute important building blocks for creating new security applications. To demonstrate this claim, we leverage the aforementioned solutions to realize HyperSleuth, an infrastructure to securely perform live forensic analysis of potentially compromised production systems. HyperSleuth provides a trusted execution environment that guarantees an attacker controlling the system cannot interfere with the analysis and cannot tamper with the results. The framework can be installed as the system runs, without a reboot and without loosing any volatile data. Moreover, the analysis can be periodically and safely interrupted to resume normal execution of the system. On top of HyperSleuth we implemented three forensic analysis tools: a lazy physical memory dumper, a lie detector, and a system call tracer. The experimental evaluation we conducted demonstrated that even time consuming analyses, such as the dump of the content of the physical memory, can be securely performed without interrupting the services offered by the system
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