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  • Article
    Monfredi O, Maltseva LA, Spurgeon HA, Boyett MR, Lakatta EG, Maltsev VA.
    PLoS One. 2013;8(6):e67247.
    UNLABELLED: Spontaneous, submembrane local Ca(2+) releases (LCRs) generated by the sarcoplasmic reticulum in sinoatrial nodal cells, the cells of the primary cardiac pacemaker, activate inward Na(+)/Ca(2+)-exchange current to accelerate the diastolic depolarization rate, and therefore to impact on cycle length. Since LCRs are generated by Ca(2+) release channel (i.e. ryanodine receptor) openings, they exhibit a degree of stochastic behavior, manifested as notable cycle-to-cycle variations in the time of their occurrence.
    AIM: The present study tested whether variation in LCR periodicity contributes to intrinsic (beat-to-beat) cycle length variability in single sinoatrial nodal cells.
    METHODS: We imaged single rabbit sinoatrial nodal cells using a 2D-camera to capture LCRs over the entire cell, and, in selected cells, simultaneously measured action potentials by perforated patch clamp.
    RESULTS: LCRs begin to occur on the descending part of the action potential-induced whole-cell Ca(2+) transient, at about the time of the maximum diastolic potential. Shortly after the maximum diastolic potential (mean 54±7.7 ms, n = 14), the ensemble of waxing LCR activity converts the decay of the global Ca(2+) transient into a rise, resulting in a late, whole-cell diastolic Ca(2+) elevation, accompanied by a notable acceleration in diastolic depolarization rate. On average, cells (n = 9) generate 13.2±3.7 LCRs per cycle (mean±SEM), varying in size (7.1±4.2 µm) and duration (44.2±27.1 ms), with both size and duration being greater for later-occurring LCRs. While the timing of each LCR occurrence also varies, the LCR period (i.e. the time from the preceding Ca(2+) transient peak to an LCR's subsequent occurrence) averaged for all LCRs in a given cycle closely predicts the time of occurrence of the next action potential, i.e. the cycle length.
    CONCLUSION: Intrinsic cycle length variability in single sinoatrial nodal cells is linked to beat-to-beat variations in the average period of individual LCRs each cycle.
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  • Article
    Wang Y, Qian P, Li D, Chen H, Zhou X.
    Environ Sci Pollut Res Int. 2021 Dec;28(47):67234-67247.
    Heavy metal contamination in ground dust presents potential environmental and human health threats. However, the heavy metal contamination status of ground dust in the vicinity of public point utilities remains poorly explored. Therefore, this study has been designed to analyze the heavy metal contaminations in the ground dust collected monthly near a public bronze sculpture in an urban campus of Nantong, China, using geo-accumulation indexes (Igeo), enrichment factors (EF), potential ecological risk indexes (RI), and health risks (noncarcinogenic risks (HI) and carcinogenic risks (CR)). This study revealed that the maximum Cr, Cu, Mn, Ni, Pb, and Zn concentrations in ground dust samples were 156.2, 708.8, 869.8, 140.8, 180.5, and 1089.7 mg kg-1, respectively, in which the mean Cu and Zn concentrations were 9 and 7 times higher than the background level in the soil. Temporally speaking, for the majority of heavy metals (with the exception of Ni), the high-concentration seasons tend to be mainly summer and autumn. It was observed that Cu and Zn exhibited significant enrichment (EF = 11.7 and 8.4, respectively), moderate-to-strong pollution (Igeo = 2.4 and 2.0, respectively), and moderate- and low-potential ecological risks ([Formula: see text] = 45.6 and 6.6, respectively). The noncarcinogenic risks which adults exposed to the heavy metal concentrations suffered were found to be insignificant. However, the carcinogenic risks related to Ni (1.3E-04) had exceeded the acceptable level. Based on principal component analysis (PCA) and correlation analysis, the heavy metal concentrations in the ground dust of urban campuses could be related to public point utilities, traffic-related exhaust sources, and industrial activities. This study's findings demonstrated that urban public utilities require more attention due to their significant enrichment, ecological risk factors, and the significant carcinogenic risks to the population.
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  • Book
    Emily W. Nowak, Renee Colsch.
    Summary: "Brown's Evidence-Based Nursing: The Research-Practice Connection, Fifth Edition introduces students to research methods and evidence-based practice. Evidence-based practice is a multi-step approach to healthcare delivery. It requires the ability to assess, interpret, and integrate current research to apply to day-to-day clinical problems"-- Provided by publisher.

    Contents:
    The Research-Practice Connection
    Research Evidence
    Reading Research Articles
    Qualitative Research
    Quantitative Descriptive Research
    Correlational Research
    Experimental Research
    Cohort Research
    Systematic Reviews
    Evidence-Based Clinical Practice Guidelines
    Asking Clinical Questions
    Searching for Research Evidence
    Appraising Research Evidence
    Appraising Recommendations of Clinical Practice Guidelines
    Appraising Conclusions of Systematic Reviews with Narrative Synthesis
    Appraising Findings of Original Studies
    Evidence-Based Practice Strategies
    Evidence-Based Practice Participation
    Point-of-Care Adaptations.
    Digital Access R2Library [2024], ©2024