Enrichment analysis of differentially expressed genes in chronic heart failure.

BACKGROUND: The study explores the differentially expressed genes in the heart tissue of patients with chronic heart failure (CHF) and normal heart tissue, thus providing information for further research on the pathogenesis of CHF. METHODS: The Gene Expression Omnibus (GEO) database was used to download the whole transcriptome sequencing results of CHF patients (GSE2656, n=49). Transcriptome sequencing results of 44 normal left ventricular tissues were randomly screened and downloaded using the Genotype-Tissue Expression (GTEX) database (n=44). We explored the differentially expressed genes between CHF tissue and normal heart tissue. Gene Ontology (GO) functional enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis were performed for differentially expressed genes. Growth hormone-releasing hormone (GHRH) was used as a representative differential gene for serological sample verification by the enzyme linked immunosorbent assay (ELISA). RESULTS: A total of 902 differentially expressed genes between CHF and normal heart tissues were screened, including 354 up-regulated genes and 548 down-regulated genes. GO enrichment analysis showed that the differentially expressed genes were significantly enriched in the extracellular and sequence-specific DNA binding domains. KEGG enrichment demonstrated that the differential genes were enriched in neuroactive ligand-receptor interaction, the calcium signaling pathway, vascular smooth muscle contraction, and other signaling pathways. ELISA results showed that the expression level of GHRH in patients with heart failure was significantly higher than that in healthy subjects (P<0.05). CONCLUSIONS: A total of 902 differentially expressed genes were found in CHF tissues compared with normal heart tissues. Signaling pathways such as neuroactive ligand-receptor interaction, the calcium ion signaling pathway, and vascular smooth muscle contraction may be related to the pathogenesis of CHF.

Highly precise stabilization of intracavity prism-based Er:fiber frequency comb using optical-microwave phase detector.

In this Letter, we demonstrate a fully stabilized Er:fiber frequency comb by using a fiber-based, high-precision optical-microwave phase detector. To achieve high-precision and long-term phase locking of the repetition rate to a microwave reference, frequency control techniques (tuning pump power and cavity length) are combined together as its feedback. Since the pump power has been used for stabilization of the repetition rate, we introduce a pair of intracavity prisms as a regulator for carrier-envelope offset frequency, thereby phase locking one mode of the comb to the rubidium saturated absorption transition line. The stabilized comb performs the same high stability as the reference for the repetition rate and provides a residual frequency instability of 3.6×10(-13) for each comb mode. The demonstrated stabilization scheme could provide a high-precision comb for optical communication, direct frequency comb spectroscopy.

Erbium fiber laser-based direct frequency comb spectroscopy of Rb two-photon transitions.

We demonstrate the direct frequency comb spectroscopy of Rb 5S→5D two-photon transitions directly excited by an optical frequency comb (OFC) in 1.5 µm fiber communication bands. A chain of comb spectral manipulation and quantum coherence control is implemented to enhance the efficiency of second harmonic OFC generation and eliminate the Doppler-broadening background. The direct frequency comb spectroscopy with clearly resolved transition lines is obtained. Our scheme provides a potential approach to realize the OFC at ~1.5 µm with high stability and accuracy.