A brief comment on the current methods of detecting QRS complexes from ECG(electrocardiogram) including the wavelet transform method is given, and the shortcomings of those methods are discussed. A simple and effective new approach for detecting QRS complexes based on histogram is developed and presented in this paper with a description of the theory of histogram and the match principle for detecting QRS complexes. This new method is checked up on the data from the MIT/BIH ECG database and that from the Beijing Polytechnic University Hospital.
Algorithms ; Electrocardiography ; methods ; Heart ; physiology ; Humans ; Nonlinear Dynamics ; Signal Processing, Computer-Assisted

ObjectiveTo investigate the effect and mechanism of salvianolic acid B combined with puerarin in protecting the SH-SY5Y cells from the damage by oxygen-glucose deprivation/reoxygenation （OGD/R） based on pyroptosis. MethodSH-SY5Y cells were used to establish the model of OGD/R， and cells were classified into the control， OGD/R， 10 μmol·L^-1 salvianolic acid B， 100 μmol·L^-1 puerarin， 10 μmol·L^-1 salvianolic acid B + 100 μmol·L^-1 puerarin， and 10 μmol·L^-1 NOD-like receptor protein 3 （NLRP3） inhibitor MCC950 groups. Except the control group， other groups were rapidly reoxygenated for 12 h after 6 h OGD for modeling. The cell survival rate was determined by the methyl thiazolyl tetrazolium （MTT） assay. An optical microscope was used to observe the cell morphology. A spectrophotometer was used to determine the content of lactic dehydrogenase （LDH） in culture supernatant. Cell damage was measured by Hoechst/PI staining. The mRNA levels of NLRP3， cysteinyl aspartate specific proteinase-1 （Caspase-1）， gasdermin D （GSDMD）， apoptosis-associated speck-like protein （ASC）， and interleukin-1β （IL-1β） were determined by real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）. The protein activation of Caspase-1 and NLRP3 was detected by immunofluorescence. Western blot was employed to determine the protein levels of IL-1β， ASC， NLRP3， Caspase-1， and cleaved Caspase-1. ResultCompared with the control group， the OGD/R group showed decreased cell survival rate （P<0.01）， damaged cell morphology， increased leakage rate of LDH （P<0.01）， up-regulated mRNA levels of NLRP3， Caspase-1， GSDMD， ASC， and IL-1β （P<0.01）， and up-regulated protein levels of IL-1β， ASC， NLRP3， Caspase-1， and cleaved Caspase-1 （P<0.01）. Compared with the OGD/R group， salvianolic acid B， puerarin， and salvianolic acid B combined with puerarin improved cell survival rate （P<0.01）， and the combined treatment group outperformed salvianolic acid B and puerarin used alone （P<0.01）. Salvianolic acid B combined with puerarin and MCC950 both improved cell morphology， reduced the leakage of LDH （P<0.01）， alleviated cell damage， and down-regulated the mRNA levels of NLRP3， Caspase-1， GSDMD， ASC， and IL-1β （P<0.05， P<0.01） and also the protein levels of IL-1β， ASC， NLRP3， Caspase-1， and cleaved Caspase-1 （P<0.05， P<0.01）. ConclusionThe results indicated that salvianolic acid B combined with puerarin can alleviate the OGD/R-induced damage of SH-SY5Y cells by inhibiting pyroptosis.

ObjectiveTo explore the protective effect of Salviae Miltiorrhizae Radix et Rhizoma and Puerariae Lobatae Radix （SP） extract on oxygen-glucose deprivation/reoxygenation （OGD/R）-injured SH-SY5Y cells based on oxidative stress and apoptosis. MethodThe extracts of the two medicinal materials mixed in different ratios were prepared. Human neuroblastoma SH-SY5Y cells were cultured in vitro and the injury was induced by OGD/R. Cell counting kit-8 （CCK-8） assay was used to screen the optimal ratio of the two medicinals and then the extract was used for further experiment. SH-SY5Y cells were classified into normal control group， OGD/R group， and low-， medium-， and high-dose SP （2∶1） extract groups （10， 30， 100 mg·L^-1， respectively）. Cells in the groups， except the normal control group， were rapidly reoxygenated for 12 h after 4 h OGD for modeling. Then cell viability was detected by CCK-8 and cell morphology was observed under the microscope. The release rate of lactate dehydrogenase （LDH）， superoxide dismutase （SOD） activity， and content of glutathione （GSH） and malondialdehyde （MDA） were determined by spectrophotometry. The level of reactive oxygen species （ROS） was detected with 2，7-dichlorodihydrofluorescein diacetate （DCFH-DA） and mitochondrial membrane potential with JC-1 assay. The nuclear morphology was observed based on Hoechst 33342 staining， and apoptosis was examined by flow cytometry combined with Annexin V-FITC/PI staining. ResultThe viability of the cells was highest in the presence of the extract of the two medicinals mixed at the ratio of 2∶1. Compared with normal control group， OGD/R group showed damaged cell morphology， high release rate of LDH and levels of ROS and MDA （P<0.01）， low SOD activity and GSH level （P<0.01）， low mitochondrial membrane potential， and high apoptosis rate （P<0.01）. Compared with OGD/R group， SP extract improved cell viability and cell morphology and reduce cell LDH release rate in a concentration-dependent manner （P<0.01）. In addition， SP extract at 30， 100 mg·L^-1 reduced the level of intracellular ROS and increased SOD activity and GSH level （P<0.05， P<0.01）， and SP extract at 100 mg·L^-1 decreased the content of MDA （P <0.05）. Moreover， SP extract increased mitochondrial membrane potential， and SP extract at 30， 100 mg·L^-1 lowered the apoptosis rate （P<0.01）. ConclusionThe extract of Salvia miltiorrhiza Bunge and Radix Puerariae mixed at 2∶1 shows better protective effect on OGD/R-injured SH-SY5Y cells. The mechanism is the likelihood that it alleviates oxidative damage of cells and inhibits cell apoptosis.