Yili Yan

Wavelet analysis of acute effects of static magnetic field on resting skin blood flow at the nail wall in young men

Whether static magnetic field (SMF) can affect microcirculation and microvasculature in human is still ambiguous. In this study, laser Doppler flowmetry (LDF) combined with spectral analysis by wavelet transform was applied to investigate acute SMF-related effects on resting skin blood flow (SBF) at the nail walls. 18 healthy young male volunteers were randomly categorized into two groups: (1) intervention group (INT; n=9) and (2) control group (CTL; n=9). In each group, three 30-minute intervals (pre-exposure, exposure and post-exposure intervals) of continuous LDF recording were taken to evaluate the baseline, SMF effects and its deferred effects. During the exposure interval in the INT group, a neodymium-iron-boron magnet was laid under the middle finger prominence while a sham was used in the CTL group. The effective flux density range of SMF along the axis of the magnet was about 46 to 223 mT between the sites of SBF measurement and the magnet. No intervention existed during other 30-minute intervals in either group. Thereafter, analysis of variance with repeated-measures combined with Bonferronis multiple comparison tests was adopted to analyze the SBF value and its spectral variants obtained by wavelet transform. The major finding of this study was that SMF exposure induced significant increases in the absolute amplitudes of frequency band III and V (aIII and aV), which indicated intrinsic myogenic and endothelial related activities (P<0.05) respectively while the mean amplitude of SBF flux still maintain on the basal level (P>0.05). Furthermore, after removal of the SMF, variations of rhythmic flow motion of SBF in SMF exposure interval vanished gradually, which suggest the limitations of the deferred-effect of SMF on SBF.

The role of oxygen-increased respirator in humans ascending to high altitude

BackgroundAcute mountain sickness (AMS) is common for people who live in low altitude areas ascending to the high altitude. Many instruments have been developed to treat mild cases of AMS. However, long-lasting and portable anti-hypoxia equipment for individual is not yet available.MethodsOxygen-increased respirator (OIR) has been designed to reduce the risk of acute mountain sickness in acute exposure to low air pressure. It can increase the density of oxygen by increasing total atmospheric pressure in a mask. Male subjects were screened, and eighty-eight were qualified to perform the experiments. The subjects were divided into 5 groups and were involved in some of the tests at 4 different altitudes (Group 1, 2: 3700 m; Group 3,4,5: 4000 m, 4700 m, 5380 m) with and without OIR. These tests include heart rate, saturation of peripheral oxygen (SpO2), malondialdehyde (MDA), superoxide dismutase (SOD), blood lactate (BLA) and PWC (physical work capacity) -170.ResultsThe results showed that higher SpO2, lower heart rate (except during exercise) and better recovery of heart rate were observed from all the subjects ’with OIR’ compared with ’without OIR’ (P<0.05). Moreover, compared with ’without OIR’, subjects ’with OIR’ in Group 1 had lower concentrations of MDA and BLA, and a higher concentration of SOD (P<0.05), while subjects ’with OIR’ in Group 2 showed better physical capacity (measured by the PWC-170) (P<0.05). The additional experiment conducted in a hypobaric chamber (simulating 4,000 m) showed that the partial pressure of oxygen in blood and arterial oxygen saturation were higher ’with OIR’ than ’without OIR’ (P<0.05).ConclusionsWe suggested that OIR may play a useful role in protecting people ascending to high altitude before acclimatization.

Screening of osteoprotegerin-related feature genes in osteoporosis and functional analysis with DNA microarray

BackgroundOsteoporosis affects 200 million people worldwide and places an enormous economic burden on society. We aim to identify the feature genes that are related to osteoprotegerin in osteoporosis and to perform function analysis with DNA microarray from human bone marrow.MethodsWe downloaded the gene expression profile GSE35957 from Gene Expression Omnibus database including nine gene chips from bone marrow mesenchymal stem cells of five osteoporotic and four non-osteoporotic subjects. The differentially expressed genes between normal and disease samples were identified by LIMMA package in R language. The interactions among the osteoprotegerin gene (OPG) and differentially expressed genes were searched and visualized by Cytoscape. MCODE and Bingo were used to perform module analysis. Finally, GENECODIS was used to obtain enriched pathways of genes in an interaction network.ResultsA total of 656 genes were identified as differentially expressed genes between osteoporotic and non-osteoporotic samples. IL17RC, COL1A1, and ESR1 were identified to interact with OPG directly from the protein-protein interaction network. A module containing ERS1 was screened out, and this module was most significantly enriched in organ development. Pathway enrichment analysis suggested genes in the interaction network were related to focal adhesion.ConclusionsThe expression pattern of IL17RC, COL1A1, and ESR1 can be useful in osteoporosis detection, which may help in identifying those populations at high risk for osteoporosis, and in directing treatment of osteoporosis.

Cascaded interpolation-filter-delay-decimation algorithm without additional delay

Accurate time delay is indispensable for many sorts of signal processing applications particular in the field of communication and detection. Traditionally, due to easy operation, interpolation-filter-delay-decimation (IFDD) algorithm was regarded as an intuitive and straightforward way to delay specific signals. However, the computational complexity of this approach will increase sharply with the increase of interpolation factor. In addition, the IFDD algorithm will also induce a fixed additional delay in the delayed signal, limiting its widespread application. To solve these issues, this study presented a cascaded IFDD algorithm without additional delay (C-IFDD-WAD) by decomposing the large interpolation factor into several small interpolation factors. The authors obtained the expression of C-IFDD-WAD algorithm and analysed the spectrum characteristics of C-IFDD-WAD algorithm in this study. Their theoretical analysis combined with the simulation results show that the computation cost of C-IFDD-WAD significantly decreased in the form of cascade based on their present new method. Moreover, the additional delay of traditional IFDD algorithm was also eliminated using the present method.

Application of Wavelet Transform to Analysis of Human Skin Blood Flux Signal

The traditional parameters to evaluate human microcirculation such as mean values of skin blood flux (SBF) and velocity of skin blood flow measured by laser Doppler flowmetry (LDF) failed to find the biological effects of magnetic field (MF) on human microcirculation according to numerous researches. Although this inefficacy of MF indicated by these traditional parameters, other potential parameters were seldom investigated. Therefore, this study aimed to find other potential parameters by using time-frequency analysis as indicators to investigate whether MF affects human microcirculation in future studies. Continuous wavelet transform which has superior frequency resolution in low frequency band was applied in present study to convert two dimensional data of flux signal with low frequency band into three dimensional data involving the temporal and frequency information of the original signal. Six characteristic peaks identified relating to microvascular mechanism were recognized in the frequency interval between 0.005 and 2 Hz and the amplitude of each peak varied with time. This method may provide a new idea and method for the analysis and processing human SBF signal and lay a foundation for future study of MF effects on human microcirculation. However, more studies are needed to demonstrate the interesting and encouraging effects of MF on untraditional parameters such as wavelet coefficients of SBF signal and to explain the precise action mechanism of MF on human microcirculation.

Role of Velocity Perception on Place Field Size and Density of Hippocampal Place Cells

Place field size is stable for a given neuron in a familiar environment, yet increases along the septotemporal axis of hippocampal CA1. It is suggested that place cell assemblies are velocity controlled oscillators (VCO), i.e., the place cell’s oscillation frequency is positively correlated with the running velocity. The VCO model has the potential assumption that the velocity is correctly perceived. However, the perception of velocity may not be faithful to the actual physical velocity in some pathological and behavioral conditions. In this study, we examine the scenario in which perceived velocity deviates from the actual value. Place field size and distribution density change with the precision of perceived velocity. Simulation studies verify that this model is in accordance with previous studies. Testable predictions are also proposed.