A preliminary attempt to understand compatibility of photoplethysmographic pulse rate variability with electrocardiogramic heart rate variability

We investigated the difference between heart rate variability (HRV) derived from electrocardiogramic (ECG) signals and pulse rate variability (PRV) derived from photoplethysmographic (PPG) signals. Ten-minute recordings of finger and ear photoplethysmogram (PPG) and Lead I electrocardiogram (ECG) were collected in fourteen healthy subjects. In this study, analyses accounting for time and frequency domain, agreement, correlation coefficient and geometrical distribution were utilized to process the ear pulse rate variability (ePRV) and finger pulse rate variability (fPRV). The agreement analysis showed high degree of agreement (Bland-Altman ratio < 0.1) between ePRV or fPRV of PPG and HRV of ECG for all the parameters except the normal-to-normal (NN) range with a moderate agreement (0.1 < Bland-Altman ratio < 0.2). Highly significant (p < 0.001) correlations (0.97 < r <1) were found between HRV and ePRV or fPRV parameters except in the NN range, where the r values were 0.92 and 0.85, respectively. Also, the experimental results indicated that the frequency-domain parameters appeared inadequate in statistical analysis. Both fPRV and ePRV were acceptable surrogates for time-domain HRV study, especially when the ECG recording was unavailable and inconvenient. Photolethysmography could offer a simple and robust means to fulfill the requirements of rhythmical pulsation assessment

MiR-494-3p mediates oxaliplatin resistance of colorectal cancer cells via PTEN/AKT pathway

Purpose: To unravel the influence of miR-494-3p on the insensitivity of colorectal cancer (CRC) cells to oxaliplatin.Methods: The mRNA level of miR-494-3p in oxaliplatin-resistant HT-29 cells was evaluated with reverse transcript-polymerase chain reaction (RT-PCR). The cells were treated with miR-494-3p suppressor or mimic, and then apoptotic changes were determined flow cytometrically. Resistancerelated gene expressions were measured using RT-PCR and western blotting. In addition, in vivo mouse experiments were conducted.Results: MiR-494-3p expression in oxaliplatin-resistant HT-29 cells was much higher than that in parental HT-29 cells, accompanied by increased levels of MRP, P-gp, and AKT phosphorylation (p-AKT), and decreased phosphatase and tensin homolog (PTEN) (p &lt; 0.001). The miR-494-3p mimic suppressed oxaliplatin-induced parental HT-29 cell apoptosis, while miR-494-3p inhibitor promoted oxaliplatin-resistant HT-29 cell apoptosis and decreased the levels of p-AKT, MRP and P-gp, while upregulating PTEN (p &lt; 0.001). Furthermore, AKT inhibitor had similar effects as miR-494-3p inhibitor (p &lt; 0.001). Experiments using nude mice demonstrated that inhibition of miR-494-3p accentuated the sensitivity of oxaliplatin-resistant HT-29 cells to oxaliplatin (p &lt; 0.05).Conclusion: Suppression of miR-494-3p attenuates oxaliplatin insensitivity to CRC cells via a mechanism which may involve PTEN/AKT pathway. Therefore, miR-494-3p may be an effective target for overcoming drug resistance of CRC

Effectiveness of Dynamic Compaction on Liquefied Foundation in Highway Practice

In this paper, the in-situ dynamic compaction tests with different values of single-drop-compaction energy are performed on a liquefiable ground encountered in highway engineering practice. Excess pore pressure, total surface settlement and lateral deformation under dynamic compaction impact are measured and analyzed at different conditions, such as single drop-compaction-energy, drop numbers, depth of soil layer etc. The standard penetration test (SPT) is used for investigating the compaction effectiveness. The investigation results indicate dynamic compaction technique is an effective way for improving liquefiable ground in highway engineering practice. Relatively small single-drop-compaction energy and relatively more drop numbers should be adopted for improving natural sedimentary liquefiable ground with dynamic compaction. The in-situ dynamic compaction tests show that the effective effect range by dynamic compaction impact depends on the single-drop-compaction energy. It is also found that the measured maximum lateral deformation has a good linear relationship with the total vertical surface settlement

Motion-compensated noncontact imaging photoplethysmography to monitor cardiorespiratory status during exercise

With the advance of computer and photonics technology, imaging photoplethysmography [(PPG), iPPG] can provide comfortable and comprehensive assessment over a wide range of anatomical locations. However, motion artifact is a major drawback in current iPPG systems, particularly in the context of clinical assessment. To overcome this issue, a new artifact-reduction method consisting of planar motion compensation and blind source separation is introduced in this study. The performance of the iPPG system was evaluated through the measurement of cardiac pulse in the hand from 12 subjects before and after 5 min of cycling exercise. Also, a 12-min continuous recording protocol consisting of repeated exercises was taken from a single volunteer. The physiological parameters (i.e., heart rate, respiration rate), derived from the images captured by the iPPG system, exhibit functional characteristics comparable to conventional contact PPG sensors. Continuous recordings from the iPPG system reveal that heart and respiration rates can be successfully tracked with the artifact reduction method even in high-intensity physical exercise situations. The outcome from this study thereby leads to a new avenue for noncontact sensing of vital signs and remote physiological assessment, with clear applications in triage and sports training

Development of a remote photoplethysmographic technique for human biometrics

Non-contact reflection photoplethysmography (NRPPG) is being developed to trace pulse features for comparison with contact photoplethysmography (CPPG). Simultaneous recordings of CPPG and NRPPG signals from 22 healthy subjects were studied. The power spectrum of PPG signals were analysed and compared between NRPPG and CPPG. The recurrence plot (RP) was used as a graphical tool to visualize the time dependent behaviour of the dynamics of the pulse signals. The agreement between NRPPG and CPPG for physiological monitoring, i.e. HRV parameters, was determined by means of the Bland-Altman plot and Pearson’s correlation coefficient. The results indicated that NRPPG could be used for the assessment of cardio-physiological signals

Up-regulation of Grb2-associated binder 1 promotes hepatocyte growth factor-induced endothelial progenitor cell proliferation and migration

Objectives Grb2-associated binder 1 (Gab1), a scaffolding adaptor protein, plays an important role in transmitting key signals that control cell growth, migration, and function from multiple tyrosine kinase receptors. This study was designed to investigate the influence of upregulation of Gab1 in endothelial progenitor cells (EPCs) stimulated with hepatocyte growth factor (HGF), and the underlying molecular mechanisms. Materials and Methods Endothelial progenitor cells isolated from human umbilical cord blood were identified and divided into four groups. EPCs in the Control group were cultured normally; those in the Control+HGF group were treated with HGF stimulation; those in the AD-Gab1 group were transfected with adenovirus containing the Gab1 gene but not treated with HGF stimulation; and, those in the AD-Gab1+HGF group were treated with both HGF stimulation and transfection with adenovirus containing the Gab1 gene. Subsequently, Gab1 expression and proliferation and migration ability were compared for EPCs grown under different conditions. Furthermore, we measured phosphorylation levels of three key proteins Gab1, SHP2, and ERK1/2. Results The AD-Gab1+HGF group had the highest expression of Gab1 and higher proliferation and migration than the other three groups. Conclusions Upregulation of Gab1 promoted HGF-induced EPC proliferation and migration. Mechanistically, HGF stimulated Gab1 tyrosine phosphorylation in EPCs, thus leading to activation of extracellular regulated MAP kinase 1/2, which is involved in proliferation and migration signaling

Detection of physiological changes after exercise via a remote optophysiological imaging system

A study of blood perfusion mapping was performed with a remote opto-physiological imaging (OPI) system coupling a sensitive CMOS camera and a custom-built resonant cavity light emitting diode (RCLED) ringlight. The setup is suitable for the remote assessment of blood perfusion in tissue over a wide range of anatomical locations. The purpose of this study is to evaluate the reliability and stability of the OPI system when measuring a cardiovascular variable of clinical interest, in this case, heart rate. To this end, the non-contact and contact photoplethysmographic (PPG) signals obtained from the OPI system and conventional PPG sensor were recorded simultaneously from each of 12 subjects before and after 5-min of cycling exercise. The time-frequency representation (TFR) method was used to visualize the timedependent behavior of the signal frequency. The physiological parameters derived from the images captured by the OPI system exhibit comparable functional characteristics to those taken from conventional contact PPG pulse waveform measurements in both the time and frequency domains. Finally and more importantly, a previously developed optophysiological model was employed to provide a 3-D representation of blood perfusion in human tissue which could provide a new insight into clinical assessment and diagnosis of circulatory pathology in various tissue segments

Non-contact reflection photoplethysmography towards effective human physiological monitoring

A non-contact reflection photoplethysmography (NRPPG) with its engineering model was created to access human physiological information. The NRPPG engineering setup with a vertical cavity surface emitting laser (VCSEL) as a light source and a high-speed PiN photodiode as a photodetector was configured based upon the principles of light-tissue interaction and Beer-Lambert’s law. In this paper, we present three aspects of the NRPPG performance: (1) photonics engineering work to capture photoplethysmographic signals with a non-contact manner in an optimal setup of the NRPPG; (2) a 5-minute protocol with 22 participants to determine a good agreement between NRPPG and contact photoplethysmography (CPPG) by means of Bland-Altman statistical analysis and Pearson’s correlation coefficient; and (3) a physiological experiment designed for cardiac-physiological monitoring utilizing NRPPG. The experimental results suggest that clean PPG signal can be obtained between 30-110 mm. The outcome from agreement study indicates that the performance of NRPPG is compatible with CPPG. The NRPPG technique has great potential in cardiac-physiological assessment in a required clinical circumstance

Spin-phonon scattering-induced low thermal conductivity in a van der Waals layered ferromagnet Cr2_2Si2_2Te6_6

Layered van der Waals (vdW) magnets are prominent playgrounds for developing magnetoelectric, magneto-optic and spintronic devices. In spintronics, particularly in spincaloritronic applications, low thermal conductivity ($\kappa$) is highly desired. Here, by combining thermal transport measurements with density functional theory calculations, we demonstrate low $\kappa$ down to 1 W m$^{-1}$ K$^{-1}$ in a typical vdW ferromagnet Cr$_2$Si$_2$Te$_6$. In the paramagnetic state, development of magnetic fluctuations way above $T_\mathrm{c}=$ 33 K strongly reduces $\kappa$ via spin-phonon scattering, leading to low $\kappa \sim$ 1 W m$^{-1}$ K$^{-1}$ over a wide temperature range, in comparable to that of amorphous silica. In the magnetically ordered state, emergence of resonant magnon-phonon scattering limits $\kappa$ below $\sim$ 2 W m$^{-1}$ K$^{-1}$, which would be three times larger if magnetic scatterings were absent. Application of magnetic fields strongly suppresses the spin-phonon scattering, giving rise to large enhancements of $\kappa$. Our calculations well capture these complex behaviours of $\kappa$ by taking the temperature- and magnetic-field-dependent spin-phonon scattering into account. Realization of low $\kappa$ which is easily tunable by magnetic fields in Cr$_2$Si$_2$Te$_6$, may further promote spincaloritronic applications of vdW magnets. Our theoretical approach may also provide a generic understanding of spin-phonon scattering, which appears to play important roles in various systems.Comment: 14 pages, 6 figures, accepted for publication in Advanced Functional Material