Accurate automated detection of P waves in ECG allows to provide fast correct diagnosis of various cardiac arrhythmias and select suitable strategy for patients' treatment. However, P waves detection is a still challenging task, especially in long-term ECGs with manifested cardiac pathologies. Software tools used in medical practice usually fail to detect P waves under pathological conditions. Most of recently published approaches have not been tested on such the signals at all. Here we introduce a novel method for accurate and reliable P wave detection, which is success in both normal and pathological cases. Our method uses phasor transform of ECG and innovative decision rules in order to improve P waves detection in pathological signals. The rules are based on a deep knowledge of heart manifestation during various arrhythmias, such as atrial fibrillation, premature ventricular contraction, etc. By involving the rules into the decision process, we are able to find the P wave in the correct location or, alternatively, not to search for it at all. In contrast to another studies, we use three, highly variable annotated ECG databases, which contain both normal and pathological records, to objectively validate our algorithm. The results for physiological records are Se = 98.56% and PP = 99.82% for MIT-BIH Arrhythmia Database (MITDP, with MITDB P-Wave Annotations) and Se = 99.23% and PP = 99.12% for QT database. These results are comparable with other published methods. For pathological signals, the proposed method reaches Se = 96.40% and PP = 91.56% for MITDB and Se = 93.07% and PP = 88.60% for Brno University of Technology ECG Signal Database with Annotations of P wave (BUT PDB). In these signals, the proposed detector greatly outperforms other methods and, thus, represents a huge step towards effective use of fully automated ECG analysis in a real medical practice.
Czech physiologist Penaz tried to overcome limitations of invasive pulse-contour methods (PCM) in clinical applications by a non-invasive method (finger mounted BP cuff) for continuous arterial waveform detection and beat-to-beat analysis. This discovery resulted in significant interest in human physiology and non-invasive examination of hemodynamic parameters, however has limitations because of the distal BP recording using a volume-clamp method. Thus, we propose a validation of beat-to-beat signal analysis acquired by novel a brachial occlusion-cuff (suprasystolic) principle and signal obtained from Finapres during a forced expiratory effort against an obstructed airway (Valsalva maneuver). Twelve healthy adult subjects [2 females, age = (27.2 ± 5.1) years] were in the upright siting position, breathe through the mouthpiece (simultaneously acquisition by brachial blood pressure monitor and Finapres) and at a defined time were asked to generate positive mouth pressure for 20 s (Valsalva). For the purpose of signal analysis, we proposed parameter a "Occlusion Cuff Index" (OCCI). The assumption about similarities between measured signals (suprasystolic brachial pulse waves amplitudes and Finapres's MAP) were proved by averaged Pearson's correlation coefficient (r- = 0.60, p < 0.001). The averaged Pearson's correlation coefficient for the comparative analysis of OCCI between methods was r- = 0.88, p < 0.001. The average percent change of OCCI during maneuver: 8% increase, 19% decrease and percent change of max/min ratio is 35%. The investigation of brachial pulse waves measured by novel brachial blood pressure monitor shows positive correlation with Finapres and the parameter OCCI shows promise as an index, which could describe changes during beat-to-beat cardiac cycles.
- MeSH
- Pulse Wave Analysis * MeSH
- Brachial Artery * physiology MeSH
- Adult MeSH
- Blood Pressure physiology MeSH
- Humans MeSH
- Blood Pressure Determination methods MeSH
- Young Adult MeSH
- Fingers MeSH
- Heart Rate MeSH
- Feasibility Studies MeSH
- Check Tag
- Adult MeSH
- Humans MeSH
- Young Adult MeSH
- Female MeSH
- Publication type
- Journal Article MeSH
Reliable P wave detection is necessary for accurate and automatic electrocardiogram (ECG) analysis. Currently, methods for P wave detection in physiological conditions are well-described and efficient. However, methods for P wave detection during pathology are not generally found in the literature, or their performance is insufficient. This work introduces a novel method, based on a phasor transform, as well as innovative rules that improve P wave detection during pathology. These rules are based on the extraction of a heartbeats' morphological features and knowledge of heart manifestation during both physiological and pathological conditions. To properly evaluate the performance of the proposed algorithm in pathological conditions, a standard database with a sufficient number of reference P wave positions is needed. However, such a database did not exist. Thus, ECG experts annotated 12 chosen pathological records from the MIT-BIH Arrhythmia Database. These annotations are publicly available via Physionet. The algorithm performance was also validated using physiological records from the MIT-BIH Arrhythmia and QT databases. The results for physiological signals were Se = 98.42% and PP = 99.98%, which is comparable to other methods. For pathological signals, the proposed method reached Se = 96.40% and PP = 85.84%, which greatly outperforms other methods. This improvement represents a huge step towards fully automated analysis systems being respected by ECG experts. These systems are necessary, particularly in the area of long-term monitoring.
The pungency of chili peppers, the most popular hot spice used worldwide, is caused by capsaicinoids (CPDs), the content of which can vary greatly due to varietal differences and growing conditions. For the first time, a novel simple method for the fast determination of CPDs in chili peppers and chili products was developed based on adsorptive transfer cyclic square-wave voltammetry (AdTCSWV), using adsorption of lipophilic CPDs on an unmodified glassy carbon electrode surface from methanolic extracts of chili pepper samples. The CSWV is based on short oxidation of adsorbed CPDs to quinoid products, and their subsequent reduction and re-oxidation to provide specific analytical signals with a linear range from 0.05 to 1.00 mg L-1. This principle was also implemented in tandem coulometric and amperometric detection of CPDs after HPLC separation. The two-step electrochemical detection provides increased selectivity for CPDs in case of CPDs co-elution with other electrochemically oxidizable components that cannot be reversibly reduced.
Electrochemical behavior of folic acid (FA) was studied by cyclic voltammetry. An irreversible oxidation peak of FA was obtained at +0,85 V (Ag/AgCl, pH 5.0). The current dependence for square-wave voltammetry was linear at 1.0·10–7 – 17·10–4 M FA with a low detection limit of 3.0·10–8 M and good repeatability (RSD 2.8 %, n = 10). The method was used in analysis of tablets with recoveries 101.5 and 103.1 % and the determined values outside the confidence interval P = 95 %. The method is an alternative to widely used chromatographic methods.
- Keywords
- square-wave voltampérometrie, borem dopovaná diamantová elektroda,
- MeSH
- Boron MeSH
- Electrochemical Techniques * methods statistics & numerical data methods statistics & numerical data MeSH
- Electrodes MeSH
- Folic Acid * analysis chemistry MeSH
- Pharmaceutical Preparations analysis chemistry MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
The fast and efficient detection of foodborne pathogens is a societal priority, given the large number of food-poisoning outbreaks, and a scientific and technological challenge, given the need to detect as little as 1 viable cell in 25 gr of food. Here, we present the first approach that achieves the above goal, thanks to the use of a micro/nano-technology and the detection capability of acoustic wave sensors. Starting from 1 Salmonella cell in 25 ml of milk, we employ immuno-magnetic beads to capture cells after only 3 h of pre-enrichment and subsequently demonstrate efficient DNA amplification using the Loop Mediated Isothermal Amplification method (LAMP) and acoustic detection in an integrated platform, within an additional ½ h. The demonstrated 4 h sample-to-analysis time comes as a huge improvement to the current need of few days to obtain the same result. In addition, the work presents the first reported Lab-on-Chip platform that comprises an acoustic device as the sensing element, exhibiting impressive analytical features, namely, an acoustic limit of detection of 2 cells/μl or 3 aM of the DNA target and ability to detect in a label-free manner dsDNA amplicons in impure samples. The use of food samples together with the incorporation of the necessary pre-enrichment step and ability for multiple analysis with an internal control, make the proposed methodology highly relevant to real-world applications. Moreover, the work suggests that acoustic wave devices can be used as an attractive alternative to electrochemical sensors in integrated platforms for applications in food safety and the point-of-care diagnostics.
- MeSH
- Acoustics instrumentation MeSH
- Food Analysis instrumentation MeSH
- Biosensing Techniques instrumentation MeSH
- Equipment Design MeSH
- DNA, Bacterial analysis genetics MeSH
- Food Contamination analysis MeSH
- Lab-On-A-Chip Devices MeSH
- Humans MeSH
- Limit of Detection MeSH
- Milk microbiology MeSH
- Foodborne Diseases microbiology MeSH
- Food Microbiology MeSH
- Salmonella genetics isolation & purification MeSH
- Salmonella Infections microbiology MeSH
- Animals MeSH
- Sound MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Evaluation Study MeSH
Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the readout of immunochemical assays utilizing indirect detection of labels (Tag-LIBS), typically based on nanoparticles. We have previously demonstrated that Tag-LIBS immunoassay employing yttrium-based photon-upconversion nanoparticles (UCNPs) can reach sensitivity similar to commonly used enzyme and fluorescence immunoassays. In this study, we report on further increasing the sensitivity of UCNP-based Tag-LIBS immunoassay by employing magnetic microbeads (MBs) as the solid phase in the determination of cancer biomarker prostate-specific antigen. Due to the possibility of analyte preconcentration, MBs enabled achieving a limit of detection (LOD) of 4.0 pg·mL-1, representing two orders of magnitude improvement compared with equivalent microtiter plate-based assay (LOD of 460 pg·mL-1). In addition, utilizing MBs opens up the possibility of an internal standardization of the LIBS readout by employing iron spectral lines, which improves the assay robustness by compensating for LIBS signal fluctuations and bead-bound immunocomplexes lost throughout the washing steps. Finally, the practical applicability of the technique was confirmed by the successful analysis of clinical samples, showing a strong correlation with the standard electrochemiluminescence immunoassay. Overall, MB-based Tag-LIBS was confirmed as a promising immunoassay approach, combining fast readout, multiplexing possibilities, and high sensitivity approaching upconversion luminescence scanning while avoiding the requirement of luminescence properties of labels.
- MeSH
- Immunoassay methods MeSH
- Lasers * MeSH
- Humans MeSH
- Limit of Detection * MeSH
- Microspheres MeSH
- Prostate-Specific Antigen * analysis immunology blood MeSH
- Spectrum Analysis methods MeSH
- Yttrium chemistry radiation effects MeSH
- Check Tag
- Humans MeSH
- Male MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- MeSH
- Electroencephalography MeSH
- Evoked Potentials MeSH
- Humans MeSH
- Visual Perception MeSH
- Check Tag
- Humans MeSH
