Device-based measures Dotaz Zobrazit nápovědu
We developed a simple low-cost cultivation-based microfluidic device from office-laminator foil and Parafilm for the determination of specific microorganisms in water samples. The main goal was to obtain a device that would be portable and cheap compared to common laboratory techniques testing microorganisms. This device needs only 10µL of a sample and can be easily used in terrain by a non-specialist. Moreover, we dealt with some technical aspects of the device fabrication such as low-cost lamination techniques and the use of different cultivation media.
- Klíčová slova
- Cultivation, Escherichia coli, Lamination, Low-cost microfluidics,
- MeSH
- analýza moči přístrojové vybavení MeSH
- Escherichia coli izolace a purifikace MeSH
- laboratoř na čipu ekonomika MeSH
- lidé MeSH
- moč mikrobiologie MeSH
- náklady a analýza nákladů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The key factor in the development of antibody-based assays is to find an antibody that has an appropriate affinity, high specificity, and low cross-reactivity. However, this task is not easy to carry out since the research antibodies on the market may suffer from low specificity and reproducibility. Here, we report on a palm-sized dot blot-based device, called the affiblot, that has a specially designed lid that allows simultaneous semi-quantitative comparison of up to five antibodies from different suppliers regarding their affinity/avidity, cross-reactivity, and batch-to-batch reliability. The only required peripheral equipment is a vacuum pump, a camera, and densitometry software. The affiblot device was tested for its functionality and its measurements were compared against those obtained by standard dot blot and ELISA. The benefit over these methods, when various antibodies are evaluated, is in its simplicity. It allows easy antigen deposition, fast application and the discarding of the solutions, a compact undivided membrane, and therefore significant decrease of labor. The device was tested with specific anti-ApoE, anti-EpCAM, anti-Salmonella, anti-E. coli, and anti-Listeria antibodies from different suppliers. Their properties were compared for their ability to interact specifically with antigen and/or non-target structures and the best-suited antibody for the intended application was identified.
- MeSH
- ELISA MeSH
- imunoblotting MeSH
- monoklonální protilátky * MeSH
- reprodukovatelnost výsledků MeSH
- zkřížené reakce MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- monoklonální protilátky * MeSH
This article deals with the time interval measurement device, which is based on a surface acoustic wave (SAW) filter as a time interpolator. The operating principle is based on the fact that a transversal SAW filter excited by a short pulse can generate a finite signal with highly suppressed spectra outside a narrow frequency band. If the responses to two excitations are sampled at clock ticks, they can be precisely reconstructed from a finite number of samples and then compared so as to determine the time interval between the two excitations. We have designed and constructed a two-channel time interval measurement device which allows independent timing of two events and evaluation of the time interval between them. The device has been constructed using commercially available components. The experimental results proved the concept. We have assessed the single-shot time interval measurement precision of 1.3 ps rms that corresponds to the time of arrival precision of 0.9 ps rms in each channel. The temperature drift of the measured time interval on temperature is lower than 0.5 ps/K, and the long term stability is better than +/-0.2 ps/h. These are to our knowledge the best values reported for the time interval measurement device. The results are in good agreement with the error budget based on the theoretical analysis.
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Dengue is one of the most rapidly spreading mosquito-borne viral diseases in the world. Differential diagnosis is a crucial step for the management of the disease and its epidemiology. Point-of-care testing of blood-borne dengue biomarkers provides an advantageous approach in many health care settings, and the ability to follow more than one biomarker at once could significantly improve the management of the disease. Bead-based multiplex technologies (suspension array) can measure multiple biomarker targets simultaneously by using recognition molecules immobilized on microsphere beads. The overarching objective of our work is to develop a portable detection device for the simultaneous measurement of multiple biomarkers important in dengue diagnosis, monitoring and treatment. Here, we present a bead-based assay for the detection of one of the four serotypes of dengue virus non-structural protein (DENV-NS1) as well as its cognate human IgG. In this system, the fluorescent microspheres containing the classification fluorophore and detection fluorophore are imaged through a microfluidic chip using an infinity-corrected microscope system. Calibration curves were plotted for median fluorescence intensity against known concentrations of DENV-NS1 protein and anti-NS1 human IgG. The limit of quantitation was 7.8 ng/mL and 15.6 ng/mL, respectively. The results of this study demonstrate the feasibility of the multiplex detection of dengue biomarkers and present its analytical performance parameters. The proposed imaging device holds potential for point-of-care testing of biomarkers on a highly portable system, and it may facilitate the diagnosis and prevention of dengue as well as other infectious diseases.
- Publikační typ
- časopisecké články MeSH
A transversal surface acoustic wave filter has been used as a time interpolator in a time interval measurement device. We are presenting the experiments and results of an analysis of the nonlinear effects in such a time interpolator. The analysis shows that the nonlinear distortion in the time interpolator circuits causes a deterministic measurement error which can be understood as the time interpolation nonlinearity. The dependence of this error on time of the measured events can be expressed as a sparse Fourier series thus it usually oscillates very quickly in comparison to the clock period. The theoretical model is in good agreement with experiments carried out on an experimental two-channel timing system. Using highly linear amplifiers in the time interpolator and adjusting the filter excitation level to the optimum, we have achieved the interpolation nonlinearity below 0.2 ps. The overall single-shot precision of the experimental timing device is 0.9 ps rms in each channel.
- Publikační typ
- časopisecké články MeSH
BACKGROUND: Device-based algorithms offer the potential for automated optimization of cardiac resynchronization therapy (CRT), but the process for accepting them into clinical use is currently still ad-hoc, rather than based on pre-clinical and clinical testing of specific features of validity. We investigated how the QuickOpt-guided VV delay (VVD) programming performs against the clinical and engineering heuristic of QRS complex shortening by CRT. METHODS: A prospective, 2-center study enrolled 37 consecutive patients with CRT. QRS complex duration (QRSd) was assessed during intrinsic atrioventricular conduction, synchronous biventricular pacing, and biventricular pacing with QuickOpt-proposed VVD. The measurements were done manually by electronic calipers in signal-averaged and magnified 12-lead QRS complexes. RESULTS: Native QRSd was 174 ± 22 ms. Biventricular pacing with empiric AVD and synchronous VVD resulted in QRSd 156 ± 20 ms, a significant narrowing from the baseline QRSd by 17 ± 27 ms, P = 0.0003. In 36 of 37 patients, the QuickOpt algorithm recommended left ventricular preexcitation with VVD of 42 ± 18 ms (median 40 ms; interquartile range 30-55 ms, P <0.00001). QRSd in biventricular pacing with QuickOpt-based VVD was significantly longer compared with synchronous biventricular pacing (168 ± 25 ms vs. 156 ± 20 ms; difference 12 ± 11ms; P <0.00001). This prolongation correlated with the absolute VVD value (R = 0.66, P <0.00001). CONCLUSIONS: QuickOpt algorithm systematically favours a left-preexcitation VVD which translates into a significant prolongation of the QRSd compared to synchronous biventricular pacing. There is no reason to believe that a manipulation that systematically widens QRSd should be considered to optimize physiology. Device-based CRT optimization algorithms should undergo systematic mechanistic pre-clinical evaluation in various scenarios before they are tested in large clinical studies.
AIMS: Physical activity (PA) is an important target for improving clinical outcomes in heart failure (HF) patients. Nonetheless, assessing the daily PA profile in this population is a challenging task, traditionally performed using self-report questionnaires such as the International PA Questionnaire Short Form (IPAQ-SF). This study aimed to evaluate the concurrent validity of the IPAQ-SF and accelerometer-assessed PA using six published cut-points in patients with HF and reduced or mildly reduced ejection fraction. METHODS AND RESULTS: The concordance between the IPAQ-SF and a hip-worn accelerometer regarding daily time spent performing moderate to vigorous PA in bouts of at least 10 min was assessed in 53 participants for seven consecutive days using six different cut-points (Barnett, Dibben, Mark, Sanders, Troiano, and Vaha-Ypya). Spearman's correlation and Bland-Altman plots were used to evaluate concurrent validity between methods. Regressions were used to study the association between patient variables, wear protocol (waking hour or 24 h), and absolute bias. The kappa index was used to evaluate the concordance between IPAQ-SF and accelerometry for classifying patients as active or non-active. All analyses were re-run using non-bouted metrics to investigate the effect of bouted versus non-bouted analysis. The IPAQ-SF and accelerometry showed low to negligible correlation (ρ = 0.12 to 0.37), depending on the cut-point used. The regression analysis showed that the absolute bias was higher in participants following the waking-hour protocol at all cut-points except Dibben's (P ≤ 0.007). The concordance between the two methods to classify patients as active and non-active was low when using Mark (κ = 0.23) and Barnett (κ = 0.34) cut-points and poor for the remaining cut-points (κ = 0.03 to 0.18). The results of the sensitivity analysis showed negligible to low correlation using non-bouted metrics (ρ = 0.27 to 0.33). CONCLUSIONS: Moderate to vigorous PA measures using IPAQ-SF and accelerometers are not equivalent, and we do not encourage researchers to use IPAQ-SF alone when assessing PA in HF patients. Moreover, applying personalized collection and processing criteria is important when assessing PA in HF patients. We recommend following the 24 h protocol and selecting cut-points calibrated in patients with cardiovascular diseases. Finally, it is necessary to develop a new tailored questionnaire that considers walking intensity and is adjusted to the current World Health Organisation recommendations, which use non-bouted metrics.
- Klíčová slova
- Activity monitor, Agreement, Device-based measures, HF, MVPA, Self-reported measures,
- MeSH
- akcelerometrie MeSH
- cvičení * MeSH
- lidé MeSH
- průzkumy a dotazníky MeSH
- srdeční selhání * diagnóza MeSH
- zpráva o sobě MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
INTRODUCTION: The administration of questionnaires presents an easy way of obtaining important knowledge about phobic patients. However, it is not well known how these subjective measurements correspond to the patient's objective condition. Our study aimed to compare scores on questionnaires and image evaluation to the objective measurements of the behavioral approach test (BAT) and the neurophysiological effect of spiders extracted from fMRI measurements. The objective was to explore how reliably subjective statements about spiders and physiological and behavioral parameters discriminate between phobics and non-phobics, and what are the best predictors of overall brain activation. METHODS: Based on a clinical interview, 165 subjects were assigned to either a "phobic" or low-fear "control" group. Finally, 30 arachnophobic and 32 healthy control subjects (with low fear of spiders) participated in this study. They completed several questionnaires (SPQ, SNAQ, DS-R) and underwent a behavioral approach test (BAT) with a live tarantula. Then, they were measured in fMRI while watching blocks of pictures including spiders and snakes. Finally, the respondents rated all the visual stimuli according to perceived fear. We proposed the Spider Fear Index (SFI) as a value characterizing the level of spider fear, computed based on the fMRI measurements. We then treated this variable as the "neurophysiological effect of spiders" and examined its contribution to the respondents' fear ratings of the stimuli seen during the fMRI using the redundancy analysis (RDA). RESULTS: The results for fear ranks revealed that the SFI, SNAQ, DS-R, and SPQ scores had a significant effect, while BAT and SPQ scores loaded in the same direction of the first multivariate axis. The SFI was strongly correlated with both SPQ and BAT scores in the pooled sample of arachnophobic and healthy control subjects. DISCUSSION: Both SPQ and BAT scores have a high informative value about the subject's fear of spiders and together with subjective emotional evaluation of picture stimuli can be reliable predictors of spider phobia. These parameters provide easy and non-expensive but reliable measurement wherever more expensive devices such as magnetic resonance are not available. However, SFI still reflects individual variability within the phobic group, identifying individuals with higher brain activation, which may relate to more severe phobic reactions or other sources of fMRI signal variability.
- Klíčová slova
- arachnophobia, behavioral approach test, fMRI, fear, snakes, spiders,
- Publikační typ
- časopisecké články MeSH
The properties of unsteady open-channel turbulent flow were theoretically and experimentally investigated in a circular cross section channel with fixed sediment deposits. Velocity and turbulence distribution data were obtained using an ultrasonic velocity profiler (UVP). Different uniform flow conditions and triangular-shaped hydrographs were analysed. The hydrograph analysis revealed a dynamic wave behaviour, where the time lags of mean cross section velocity, friction velocity, discharge and flow depth were all evident. The bottom shear stress dynamic behaviour was estimated using four different approaches. Measurements of the velocity distribution in the inner region of the turbulent layer and of the Reynolds stress distribution in the turbulent flow provided the analysed data sets of the bottom shear stress. Furthermore, based on the Saint Venant equation, the bottom shear stress time behaviour was studied using both the kinematic and the dynamic flow principles. The dynamic values of the bottom shear stress were compared with those for the steady flow conditions. It is evident that bottom shear stress varies along the generated flood hydrograph and its variation is the function of the flow unsteadiness. Moreover, the kinematic flow principle is not an adequate type of approximation for presented flow conditions.
Ultrasound power delivery can be considered a convenient technique for charging implantable medical devices. In this work, an intra-body system has been modeled to characterize the phenomenon of ultrasound power transmission. The proposed system comprises a Langevin transducer as transmitter and an AlN-based square piezoelectric micro-machined ultrasonic transducer as receiver. The medium layers, in which elastic waves propagate, were made by polydimethylsiloxane to mimic human tissue and stainless steel to replace the case of the implantable device. To characterize the behavior of the transducers, measurements of impedance and phase, velocity and displacement, and acoustic pressure field were carried out in the experimental activity. Then, voltage and power output were measured to analyze the performance of the ultrasound power delivery system. For a root mean square voltage input of approximately 35 V, the power density resulted in 21.6 µW cm-2. Such a result corresponds to the data obtained with simulation through a one-dimensional lumped parameter transmission line model. The methodology proposed to develop the ultrasound power delivery (UPD) system, as well as the use of non-toxic materials for the fabrication of the intra-body elements, are a valid design approach to raise awareness of using wireless power transfer techniques for charging implantable devices.
- Klíčová slova
- Langevin transducer, acoustic, energy transfer, implantable medical devices, lumped parameters model, pMUT, ultrasound,
- Publikační typ
- časopisecké články MeSH
