This study was aimed at investigating the effectiveness of various host nucleic acid removal and non-specific amplifica-tion techniques in animal tissue samples,to increase the accuracy of pathogen identification in tissue samples.Simulated samples were prepared with a mixture of mouse lung tissue homogenates and Klebsiella pneumoniae fluids,and processed with six host nucleic acid removal kits and three non-specific amplification techniques.The effectiveness of each method in removing host DNA and enriching nucleic acids of pathogenic microorganisms was evaluated through real-time fluorescence quantitative PCR and high-throughput se-quencing.For host nucleic acid removal techniques,the method of selective cleavage and quantitative degradation of host DNA(Com-plete5 kit)effectively decreased the host nucleic acid content in tissue samples and increased the relative abundance of pathogen nucleic acids.In contrast,the magnetic bead method for host DNA removal(Next microbiome DNA enrichment Kit kit)was less effec-tive.At lower pathogen concentrations(77 CFU/mL),the Vazyme kit was more effective than the other kits in removing host nucleic acids.Non-specific amplification techniques(MALBAC whole genome amplification,MDA isothermal amplification,and random primer amplification)were not applicable to tissue samples and were not effective in increasing the relative abundance of pathogen nucleic acids.Selective lysis and quantitative degradation of host DNA were suitable for processing tissue samples with high host back-ground and low pathogenic microorganism levels,whereas non-specific amplification methods were not applicable to tissue samples for pre-processing of macro-genome high-throughput sequencing.

This study was aimed at investigating the effectiveness of various host nucleic acid removal and non-specific amplifica-tion techniques in animal tissue samples,to increase the accuracy of pathogen identification in tissue samples.Simulated samples were prepared with a mixture of mouse lung tissue homogenates and Klebsiella pneumoniae fluids,and processed with six host nucleic acid removal kits and three non-specific amplification techniques.The effectiveness of each method in removing host DNA and enriching nucleic acids of pathogenic microorganisms was evaluated through real-time fluorescence quantitative PCR and high-throughput se-quencing.For host nucleic acid removal techniques,the method of selective cleavage and quantitative degradation of host DNA(Com-plete5 kit)effectively decreased the host nucleic acid content in tissue samples and increased the relative abundance of pathogen nucleic acids.In contrast,the magnetic bead method for host DNA removal(Next microbiome DNA enrichment Kit kit)was less effec-tive.At lower pathogen concentrations(77 CFU/mL),the Vazyme kit was more effective than the other kits in removing host nucleic acids.Non-specific amplification techniques(MALBAC whole genome amplification,MDA isothermal amplification,and random primer amplification)were not applicable to tissue samples and were not effective in increasing the relative abundance of pathogen nucleic acids.Selective lysis and quantitative degradation of host DNA were suitable for processing tissue samples with high host back-ground and low pathogenic microorganism levels,whereas non-specific amplification methods were not applicable to tissue samples for pre-processing of macro-genome high-throughput sequencing.

Objective To investigate the prevalence of fluorosis and related control measures on drinking water type of endemic fluorosis in China.Methods According to the national program"Surveillance Scheme of Drinking-Water-Borne Endemic Fluorosis",136 counties were selected in 29 provinces,autonomous regions and municipalities.Three epidemic villages were randomly selected as fixed monitoring sites in each county.Dental fluorosis of all the children aged 8-12 living in the villages under the monitoring program,was identified under the ariteria from "Diagnosis of dental fluorosis"(WS/T 208-2011).Operating conditions and contents of fluoride in all the'water-improved projects' were investigated.Contents of fluoride in drinking water were tested in villages without the 'water-improved projects'."Standard Test Method for Drinking Water" (GB/T 5750.5-2006) was used to detect the water fluoride.Results The overall prevalence of dental fluorosis among children aged 8-12 in all the villages under monitor program,was 28.58％ (7 950/27 817),with the dental fluorosis index (DFI) as 0.58.Among them,the prevalence was 22.28％ (3 917/17 583) and DFI was 0.44 in the' water-improved projects' villages that under normal operation and with qualified fluoride contents.The prevalence appeared as 38.74％ (1 926/4 971) with DFI as 0.84 in those villages with 'water-improved projects' but mal-operated or with excessive fluoride.The prevalence was 40.03％ (2 107/5 263),and DFI was 0.81 in those villages without'water-improved projects'.The prevalence rates of dental fluorosis in children from the three types of endemic areas were significantly different.For 'water-improved projects',the normal opration rate was 93.77％ (286/305) and the qualification rate of fluoride content was 76.77％ (228/297).Conclusions Dental fluorosis in children living in the drinking-water-born endemic fluorosis areas was on the edge of epidemics in China.Effective improvement on the quality of drinking water can significantly reduce the severity of dental fluorosis in children.The rate of proper operation on 'water-improved projects' was near to 95％ in the endemic area.However,rate that met the criteria on qualified fluoride contents of these projects was still below 80％.

Objective To investigate the implementation effects of control measures and the dynamic prevalence of drinking-water-borne endemic fluorosis,in order to provide a scientific basis for developing control measures against the disease.Methods According to the Surveillance Scheme of Drinking-Water-Borne Endemic Fluorosis,137 counties were selected as monitoring counties in national 27 provinces (autonomous regions,municipalities) and Xin Jiang Production and Construction Corps.Three epidemic villages were selected as fixed monitoring villages in each county.The operating condition and the fluoride level of water improvement projects were investigated in the villages with water improvement projects.The fluoride level of drinking water was tested in the villages without water improvement projects.The fluoride content in drinking water was detected by the Standard Test Method for Drinking Water (GB/T 5750.5-2006).The preyalence of dental fluorosis of all children aged 8-12 were surveyed,and dental fluorosis was diagnosed by Clinical Diagnostic Criteria of Dental Fluorosis (WS/T 208-2011).Results ①427 villages were surveyed in 2012,among which the villages with water improvement projects accounted for 75.88％ (324/427).② 299 water improvement projects were investigated.Normal operation rates of those were 89.30％ (267/299).The qualified rate of fluoride content was 75.78％ (219/289).Totally 103 villages without water improvement projects were monitored.Villages with fluoride level ＞ 1.2-2.0 mg/L,＞ 2.0-4.0 mg/L and ＞ 4.0 mg/L accounted for 48.54％ (50/103),29.13％ (30/103) and 9.71％ (10/103),respectively.(③The national detection rate of dental fluorosis and community fluorosis index (CFI) in children aged 8-12 were 31.24％ (8 677/27 773) and 0.66.The detection rate and CFI of the villages with normal operation projects and the qualified fluoride content were 24.04％ (3 999/16 634) and 0.51.The detection rate and CFI of the villages with water improvement projects under abnormal operation or excessive fluoride were 40.77％ (1 654/4 057) and 0.91.The rate and CFI of the villages without water improvement projects were 42.70％ (3 024/7 082) and 0.86.Conclusions The rate of water improvement projects of the whole country is lower.The national normal operation rate of water defluoridation improvement projects is below 90％,and the qualified rate of fluoride content in drinking water is below 80％.The prevalence of dental fluorosis in children aged 8-12 is very mild.

Anti-Bacterial Agents ; pharmacology ; Bacterial Infections ; therapy ; Bacteriophages ; physiology ; Drug Resistance, Bacterial ; drug effects ; Humans ; Probiotics ; pharmacology ; therapeutic use