Abstract. This study investigates the chemical composition of
PM2.5 collected at a central location in Beijing, China, during winter
2016 and summer 2017. The samples were characterised using direct-infusion
negative-nano-electrospray-ionisation ultrahigh-resolution mass spectrometry
to elucidate the composition and the potential primary and secondary sources
of the organic fraction. The samples from the two seasons were compared with
those from a road-tunnel site and an urban background site in Birmingham,
UK, analysed in the course of an earlier study using the same method. There
were strong differences in aerosol particle composition between the seasons,
particularly regarding (poly-)aromatic compounds, which were strongly
enhanced in winter, likely due to increased fossil fuel and biomass burning
for heating. In addition to the seasonal differences, compositional
differences between high- and low-pollution conditions were observed, with
the contribution of sulfur-containing organic compounds strongly enhanced
under high-pollution conditions. There was a correlation of the number of
sulfur-containing molecular formulae with the concentration of particulate
sulfate, consistent with a particle-phase formation process.
MicroRNAs (miRNAs) are single-stranded, non-coding RNA molecules that regulate gene expression post-transcriptionally by binding to messenger RNAs. miRNAs are important regulators of gene expression, and their dysregulation is implicated in many human and canine diseases. Most cancers tested to date have been shown to express altered miRNA levels, which indicates their potential importance in the oncogenic process. Based on this evidence, numerous miRNAs have been suggested as potential cancer biomarkers for both diagnosis and prognosis. miRNA-based therapies have also been tested in different cancers and have provided measurable clinical benefits to patients. In addition, understanding miRNA biogenesis and regulatory mechanisms in cancer can provide important knowledge about resistance to chemotherapies, leading to more personalized cancer treatment. In this review, we comprehensively summarized the importance of miRNA in human and canine cancer research. We discussed the current state of development and potential for the miRNA as both a diagnostic marker and a therapeutic target.
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