Visfatin is a highly conserved protein expressed by visceral fat tissues that previously identified as pre B cell colony-enchancing factor (PBEF). Visfatin is a 52 ku cytokine and has been shown to exert multiple distinct biological activities. By interacting with insulin receptors, visfatin exhibits insulin mimicking or antagonizing effects under different circumstances. In addition, it possesses an nicotinamide phosphoribosyl transferase (Nampt) activity inside the cells, which functions at the rate-limiting step along the pathway of nicotinamide adenine dinucleotide (NAD) biosyntheses. And finally, as an extracellular cytokine, visfatin is able to induce the expression of inflammatory cytokines, such as TNF?, IL-1? and IL-6. Visfatin has drawn increasing attentions to researchers for its close association with a variety of human metabolic and acute/chronic inflammatory diseases or disorders, including diabetes, obesity, acute lung injury, rheumatoid arthritis, sepsis, myocardial infarction and inflammatory bowel disease. Recently, the SNP (single nucleotide polymorphism) analyses of visfatin and its promoter regions have provided more in-depth understandings of its roles in disease pathogenesis. A discussion in the current knowledge of the structure and diversified functions of visfatin, as well as its connections with a variety of common diseases was given.

Objective:To evaluate the performance of the influenza surveillance network and compare the epidemic intensity of influenza during 2014-2020 in Shanghai.Methods:Based on the weekly reports of influenza-like illness (ILI) and laboratory-confirmed influenza cases from January 1, 2014 to December 31, 2020. This study first evaluated the data reporting and specimen collection of ILI cases for each sentinel hospital, and then calculated the percentage of ILI (ILI%), the proportion of specimens tested positive for influenza, and the incidence of influenza among all ILI outpatient and emergency visits to measure the epidemic intensity of influenza. Finally, seasonal autoregressive integrated moving average (ARIMA) model was applied to quantify the changes in epidemic intensity of influenza in 2020.Results:The proportion of influenza surveillance sentinel hospitals with a score of less than 5 in the evaluation of ILI data reporting and samples collection were 9.68% and 21.05% in 2020 in Shanghai, respectively. ILI% was estimated to be 1.51% (95% CI: 1.50%-1.51%) and 2.31% (95% CI: 2.30%-2.32%), respectively for 2014-2019 and 2020; the proportion of specimens tested positive was 24.27% (95% CI: 24.02%- 24.51%) and 7.15% (95% CI: 6.78%-7.54%), respectively; and the incidence of influenza was 3.66‰ (95% CI: 3.62‰-3.70‰) and 1.65‰ (95% CI: 1.57‰-1.74‰), respectively. ARIMA model showed that ILI% was increased by 45.25% in 2020 in Shanghai, and the proportion of specimens tested positive and the incidence of influenza were reduced by 78.45% and 51.80%, respectively. Conclusions:In 2020, the performance of influenza surveillance system has changed, ILI% has increased, the proportion of specimens tested positive and the incidence of influenza has decreased in Shanghai. The change in the quality of influenza surveillance is also a potential factor affecting the epidemic intensity of influenza. In the future, the quality control of influenza surveillance network still needs to be further strengthened.