Background:Trachoma results from repeated episodes of conjunctival infection with Chlamydia trachomatis and is the leading infectious cause of blindness.To eliminate trachoma,control programmes use the SAFE strategy(S...Background:Trachoma results from repeated episodes of conjunctival infection with Chlamydia trachomatis and is the leading infectious cause of blindness.To eliminate trachoma,control programmes use the SAFE strategy(Surgery,Antibiotics,Face cleanliness,and Environmental improvement).The A component is designed to treat C trachomatis infection,and is initiated on the basis of the prevalence of the clinical sign trachomatous inflammation-follicular(TF).Unfortunately,TF correlates poorly with C trachomatis infection.We sought to assess a newly developed point-of-care(POC)assay compared with presence of TF for guiding the use of antibiotics for trachoma control.Methods:We compared performance outcomes of the POC assay and presence of TF using commercial PCR as a comparator in 664 children aged 1-9 years in remote,trachoma-endemic villages in Tanzania.Signs of trachoma were graded according to the WHO simplified trachoma grading system.Findings:Of 664 participants,128(19%)were positive for ocular C trachomatis infection by PCR.Presence of TF had a sensitivity of 64.1%(95% CI 55.8-72.4),specificity of 80.2%(76.8-83.6),and positive predictive value of 43.6%(36.5-50.7).By contrast,the POC assay had a sensitivity of 83.6%(77.2-90.0),specificity of 99.4%(98.8-100.0),and positive predictive value of 97.3%(94.2-100.3).Interagreements and intra-agreements between four novice operators were 0.988(0.973-1.000)and 0.950(0.894-1.000),respectively.Interpretation:The POC assay is substantially more accurate than TF prevalence in identifying the presence or absence of infection.Additional studies should assess the use of the assay in the planning and monitoring of trachoma control activities.展开更多
采用超快速气相电子鼻对超高温灭菌(ultra high temperature,UHT)全脂、低脂和脱脂牛奶共36种样品的挥发性风味成分进行定性、定量分析,并结合主成分分析和多层感知器神经网络,对UHT牛奶的香气特征进行分类预测。结果表明,UHT牛奶中含...采用超快速气相电子鼻对超高温灭菌(ultra high temperature,UHT)全脂、低脂和脱脂牛奶共36种样品的挥发性风味成分进行定性、定量分析,并结合主成分分析和多层感知器神经网络,对UHT牛奶的香气特征进行分类预测。结果表明,UHT牛奶中含有29种共同的挥发性风味成分,主要为丙酮、正丁醇和δ-癸内酯等,其中丙酮含量最高,癸醛含量最低。异丁醇、乙偶姻、1-戊醇、E-3-己烯醛和癸醛只在UHT全脂牛奶中存在;3-甲基庚烷、2,6-二甲基吡嗪、E-2-壬烯-1-醇是UHT低脂牛奶的特有成分;α-蒎烯、5-甲基糠醛、癸酸仅在UHT脱脂牛奶中被检出。UHT牛奶主要香气特征体现为蔬菜味、奶油味、草香味、水果味及麦芽味。其中蔬菜味、奶油味、麦芽味在UHT全脂牛奶中分布最广泛;水果味在UHT低脂牛奶中分布最广泛;青草味在UHT脱脂牛奶中分布最广泛。主成分分析显示不同品牌UHT牛奶之间存在显著差异;多层感知器神经网络对UHT牛奶种类的预测准确率高达98.6%。展开更多
文摘Background:Trachoma results from repeated episodes of conjunctival infection with Chlamydia trachomatis and is the leading infectious cause of blindness.To eliminate trachoma,control programmes use the SAFE strategy(Surgery,Antibiotics,Face cleanliness,and Environmental improvement).The A component is designed to treat C trachomatis infection,and is initiated on the basis of the prevalence of the clinical sign trachomatous inflammation-follicular(TF).Unfortunately,TF correlates poorly with C trachomatis infection.We sought to assess a newly developed point-of-care(POC)assay compared with presence of TF for guiding the use of antibiotics for trachoma control.Methods:We compared performance outcomes of the POC assay and presence of TF using commercial PCR as a comparator in 664 children aged 1-9 years in remote,trachoma-endemic villages in Tanzania.Signs of trachoma were graded according to the WHO simplified trachoma grading system.Findings:Of 664 participants,128(19%)were positive for ocular C trachomatis infection by PCR.Presence of TF had a sensitivity of 64.1%(95% CI 55.8-72.4),specificity of 80.2%(76.8-83.6),and positive predictive value of 43.6%(36.5-50.7).By contrast,the POC assay had a sensitivity of 83.6%(77.2-90.0),specificity of 99.4%(98.8-100.0),and positive predictive value of 97.3%(94.2-100.3).Interagreements and intra-agreements between four novice operators were 0.988(0.973-1.000)and 0.950(0.894-1.000),respectively.Interpretation:The POC assay is substantially more accurate than TF prevalence in identifying the presence or absence of infection.Additional studies should assess the use of the assay in the planning and monitoring of trachoma control activities.
文摘采用超快速气相电子鼻对超高温灭菌(ultra high temperature,UHT)全脂、低脂和脱脂牛奶共36种样品的挥发性风味成分进行定性、定量分析,并结合主成分分析和多层感知器神经网络,对UHT牛奶的香气特征进行分类预测。结果表明,UHT牛奶中含有29种共同的挥发性风味成分,主要为丙酮、正丁醇和δ-癸内酯等,其中丙酮含量最高,癸醛含量最低。异丁醇、乙偶姻、1-戊醇、E-3-己烯醛和癸醛只在UHT全脂牛奶中存在;3-甲基庚烷、2,6-二甲基吡嗪、E-2-壬烯-1-醇是UHT低脂牛奶的特有成分;α-蒎烯、5-甲基糠醛、癸酸仅在UHT脱脂牛奶中被检出。UHT牛奶主要香气特征体现为蔬菜味、奶油味、草香味、水果味及麦芽味。其中蔬菜味、奶油味、麦芽味在UHT全脂牛奶中分布最广泛;水果味在UHT低脂牛奶中分布最广泛;青草味在UHT脱脂牛奶中分布最广泛。主成分分析显示不同品牌UHT牛奶之间存在显著差异;多层感知器神经网络对UHT牛奶种类的预测准确率高达98.6%。
