NAS preparation, a kind of Chinese herbal medicine found by the Yunnan Eco-agricultural Research Institute, has potential antiviral activity. In this paper, the inhibiting effect of NAS preparation on H9N2 subtype Avian influenza virus (AIV) was investigated in vivo. Chickens infected with H9N2 virus were treated with NAS preparation for 4 days. The virus was then detected by hemoagglutination (HA) test and reverse transcription polymerase chain reaction (RT-PCR). The results showed that no H9N2 virus could be detected at the 7th day when the chickens were treated with 0.2g/kg/d or 0.1g/kg/d of NAS preparation. However the virus could be detected in other chickens without NAS preparation treatment. This result suggested that NAS preparation may be a potential drug candidate to control infection of H9N2 subtype AIV in chickens.

Objective:To study the relationship between the relevant chemical elements in the original surface drinking water sources and the prevalence of dental fluorosis in Bijie City, Guizhou Province, and to provide a scientific basis for further studying the distribution of dental fluorosis patients, clarifying the mechanism of endemic fluorosis, and scientifically adjusting relevant prevention and treatment policies.Methods:From August 2021 to March 2022, based on the local census data of endemic fluorosis in Guizhou Province, 385 samples of original surface drinking water sources were collected in 214 townships (towns) of Bijie City. The pH value, and contents of fluorine (F), calcium (Ca), magnesium (Mg), aluminum (Al), titanium (Ti), manganese (Mn), copper (Cu), zinc (Zn), nickel (Ni), arsenic (As), molybdenum (Mo), cadmium (Cd), barium (Ba), lead (Pb), chromium (Cr), iron (Fe), and selenium (Se) in the drinking water were determined. Taking the dental fluorosis index representing the prevalence of dental fluorosis as the dependent variable, a principal component multiple regression model was constructed based on the above chemical elements of drinking water to study the related factors affecting the prevalence of dental fluorosis, and its contribution rate was calculated.Results:The median of dental fluorosis index in 214 townships (towns) of Bijie City was 1.460. The average of pH values and contents of F, Ca, Mg, Al, Ti, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Ba and Pb of 385 drinking water samples were 6.369, and 0.209, 179.706, 16.198, 0.163, 0.987, 0.015, 0.073, 0.176, 0.027, 0.014, 0.191, 0.007, 0.005, 0.003, 0.001, 0.155, 0.005 mg/L, respectively. Six principal components ( F1 - F6) were extracted by principal component regression analysis, and the cumulative contribution rate was 72.05%. After multiple linear regression analysis, the chemical elements in drinking water were positively correlated with the prevalence of dental fluorosis in the order of Se, Fe, Cr, Mn, Ni, Cd and Cu, and negatively correlated with the prevalence of dental fluorosis in the order of Ba, F, Ti, Mo, Zn, Al, Pb, Ca, As and Mg. Conclusions:The chemical properties in drinking water of endemic fluorosis areas in Bijie City have obvious synergistic or antagonistic effects on the occurrence and prevalence of dental fluorosis in this area. The F in the drinking water may not play a decisive role in the occurrence and prevalence of local dental fluorosis.