To identify sociodemographic characteristics and risk factor of Demodex infestation,756 students aged 13-22 years in Xi'an,China were sampled for the school-based cross-sectional study.Demodex was examined using t...To identify sociodemographic characteristics and risk factor of Demodex infestation,756 students aged 13-22 years in Xi'an,China were sampled for the school-based cross-sectional study.Demodex was examined using the cellophane tape method(CTP).The results showed that the total detection rate of Demodex was 67.6%.Logistic regression analysis revealed that five variables(gender,residence,sharing sanitary ware,frequency of face-wash per day,and use of facial cleanser) were found to be uncorrelated with Demodex infestation,whereas three variables(age,skin type,and skin disease) were found to be independent correlates.Students aged over 18 years had 22.1 times higher odds of Demodex infestation compared to those under 16 years and students aged 16-18 years also had 2.1 times higher odds compared to those aged 13-15 years.Odds of having a Demodex infestation for oily or mixed skin were 2.1 times those for dry or neutral skin.Students with a facial skin disease had 3.0 times higher odds of being infested with Demodex compared to those without.The inception rate of students with facial dermatoses increased in parallel with increasing mite count.The inception rates were 21.3%,40.7%,59.2%,and 67.7% in the negative,mild,moderate,and severe infestation groups,respectively(χ2=60.6,P<0.001).Specifically,the amount of infested mites and inception rate of acne vulgaris were positively correlated(R2=0.57,moderate infestation odds ratio(OR)=7.1,severe infestation OR=10.3).It was concluded that Demodex prevalence increases with age,and Demodex presents in nearly all adult human.Sebaceous hyperplasia with oily or mixed skin seems to favour Demodex proliferation.Demodex infestation could be associated with acne vulgaris.The CTP is a good sampling method for studies of Demodex prevalence.展开更多
Background： Preterm premature rapture of membrane （PPROM） can lead to serious consequences such as intrauterine infection, prolapse of the umbilical cord, and neonatal respiratory distress syndrome. Genital infecti...Background： Preterm premature rapture of membrane （PPROM） can lead to serious consequences such as intrauterine infection, prolapse of the umbilical cord, and neonatal respiratory distress syndrome. Genital infection is a very important risk which closely related with PPROM. The preliminary study only made qualitative research on genital infection, but there was no deep and clear judgment about the effects of pathogenic bacteria. This study was to analyze the association of in fections with PPROM in pregnant women in Shaanxi, China, and to establish Bayesian stepwise discriminant analysis to predict the incidence of PPROM. Methods： In training group, the 112 pregnant women with PPROM were enrolled in the case subgroup, and 108 normal pregnant women in the control subgroup using an unmatched case-control method. The sociodemographic characteristics of these participants were collected by face-to-face interviews. Vaginal excretions fiom each participant were sampled at 28 36-6 weeks of pregnancy using a sterile swab. DNA corresponding to Chlamrdia trachomalix （CT）, Ureaplasma urealyticwn （UU）, Candida albicans, group B streptococci （GBS）, herpes simplex virus- 1 （HSV-1）, and HSV-2 were detected in each participant by real-time polymerase chain reaction. A model of Bayesian discriminant analysis was established and then verified by a mull）center validation group that included 500 participants in the case subgroup and 5（10 participants in the control subgroup from five different hospitals in the Shaanxi province, respectively. Results： The sociological characteristics were not significantly different between the case and control subgroups in both training and validation groups （all P 〉 0.05）. In training group, the infection rates of UU （11.6% vs. 3.7%）, CT （17.0% vs. 5.6%）, and GBS （22.3% vs. 6.5%） showed statistically different between the case and control subgroups （all P 〈 0.05）, Iog-transfomacd quantification of UU, CE GBS, and HSV-2 showed statistically different between the case and control subgroups （P 〈 0.05）. All etiological agents were introduced into the Bayesian stepwise discriminant model showed that UU, CT, and GBS infections were the main contributors to PPROM, with coe｜＇ficients of 0.441,3.347, and 4.126, respectively. The accuracy rates of the Bayesian stepwise discriminant analysis between the case and control subgroup were 84.1% and 86.8% in the training and validation groups, respectively. Conclusions： This study established a Bayesian stepwise discriminant model to predict the incidence of PPROM. The UU, CT, and GBS infections were discriminant factors for PPROM according to a Bayesian stepwise discriminant analysis. This model could provide a new method for the early predicting of PPROM in pregnant women.展开更多
To our knowledge,few reports on Demodex studied at the molecular level are available at present.In this study our group,for the first time,cloned,sequenced and analyzed the chitin synthase(CHS) gene fragments of Demod...To our knowledge,few reports on Demodex studied at the molecular level are available at present.In this study our group,for the first time,cloned,sequenced and analyzed the chitin synthase(CHS) gene fragments of Demodex folliculorum,Demodex brevis,and Demodex canis(three isolates from each species) from Xi'an China,by designing specific primers based on the only partial sequence of the CHS gene of D.canis from Japan,retrieved from GenBank.Results show that amplification was successful only in three D.canis isolates and one D.brevis isolate out of the nine Demodex isolates.The obtained fragments were sequenced to be 339 bp for D.canis and 338 bp for D.brevis.The CHS gene sequence similarities between the three Xi'an D.canis isolates and one Japanese D.canis isolate ranged from 99.7% to 100.0%,and those between four D.canis isolates and one D.brevis isolate were 99.1%-99.4%.Phylogenetic trees based on maximum parsimony(MP) and maximum likelihood(ML) methods shared the same clusters,according with the traditional classification.Two open reading frames(ORFs) were identified in each CHS gene sequenced,and their corresponding amino acid sequences were located at the catalytic domain.The relatively conserved sequences could be deduced to be a CHS class A gene,which is associated with chitin synthesis in the integument of Demodex mites.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30872199)the Natural Science Foundation of Shaanxi Province (No. 2006C247),China
文摘To identify sociodemographic characteristics and risk factor of Demodex infestation,756 students aged 13-22 years in Xi'an,China were sampled for the school-based cross-sectional study.Demodex was examined using the cellophane tape method(CTP).The results showed that the total detection rate of Demodex was 67.6%.Logistic regression analysis revealed that five variables(gender,residence,sharing sanitary ware,frequency of face-wash per day,and use of facial cleanser) were found to be uncorrelated with Demodex infestation,whereas three variables(age,skin type,and skin disease) were found to be independent correlates.Students aged over 18 years had 22.1 times higher odds of Demodex infestation compared to those under 16 years and students aged 16-18 years also had 2.1 times higher odds compared to those aged 13-15 years.Odds of having a Demodex infestation for oily or mixed skin were 2.1 times those for dry or neutral skin.Students with a facial skin disease had 3.0 times higher odds of being infested with Demodex compared to those without.The inception rate of students with facial dermatoses increased in parallel with increasing mite count.The inception rates were 21.3%,40.7%,59.2%,and 67.7% in the negative,mild,moderate,and severe infestation groups,respectively(χ2=60.6,P<0.001).Specifically,the amount of infested mites and inception rate of acne vulgaris were positively correlated(R2=0.57,moderate infestation odds ratio(OR)=7.1,severe infestation OR=10.3).It was concluded that Demodex prevalence increases with age,and Demodex presents in nearly all adult human.Sebaceous hyperplasia with oily or mixed skin seems to favour Demodex proliferation.Demodex infestation could be associated with acne vulgaris.The CTP is a good sampling method for studies of Demodex prevalence.
文摘Background： Preterm premature rapture of membrane （PPROM） can lead to serious consequences such as intrauterine infection, prolapse of the umbilical cord, and neonatal respiratory distress syndrome. Genital infection is a very important risk which closely related with PPROM. The preliminary study only made qualitative research on genital infection, but there was no deep and clear judgment about the effects of pathogenic bacteria. This study was to analyze the association of in fections with PPROM in pregnant women in Shaanxi, China, and to establish Bayesian stepwise discriminant analysis to predict the incidence of PPROM. Methods： In training group, the 112 pregnant women with PPROM were enrolled in the case subgroup, and 108 normal pregnant women in the control subgroup using an unmatched case-control method. The sociodemographic characteristics of these participants were collected by face-to-face interviews. Vaginal excretions fiom each participant were sampled at 28 36-6 weeks of pregnancy using a sterile swab. DNA corresponding to Chlamrdia trachomalix （CT）, Ureaplasma urealyticwn （UU）, Candida albicans, group B streptococci （GBS）, herpes simplex virus- 1 （HSV-1）, and HSV-2 were detected in each participant by real-time polymerase chain reaction. A model of Bayesian discriminant analysis was established and then verified by a mull）center validation group that included 500 participants in the case subgroup and 5（10 participants in the control subgroup from five different hospitals in the Shaanxi province, respectively. Results： The sociological characteristics were not significantly different between the case and control subgroups in both training and validation groups （all P 〉 0.05）. In training group, the infection rates of UU （11.6% vs. 3.7%）, CT （17.0% vs. 5.6%）, and GBS （22.3% vs. 6.5%） showed statistically different between the case and control subgroups （all P 〈 0.05）, Iog-transfomacd quantification of UU, CE GBS, and HSV-2 showed statistically different between the case and control subgroups （P 〈 0.05）. All etiological agents were introduced into the Bayesian stepwise discriminant model showed that UU, CT, and GBS infections were the main contributors to PPROM, with coe｜＇ficients of 0.441,3.347, and 4.126, respectively. The accuracy rates of the Bayesian stepwise discriminant analysis between the case and control subgroup were 84.1% and 86.8% in the training and validation groups, respectively. Conclusions： This study established a Bayesian stepwise discriminant model to predict the incidence of PPROM. The UU, CT, and GBS infections were discriminant factors for PPROM according to a Bayesian stepwise discriminant analysis. This model could provide a new method for the early predicting of PPROM in pregnant women.
基金Project supported by the National Natural Science Foundation of China (No. 81271856)the National College of Innovative Experimental Projects of China (No. 101069819)
文摘To our knowledge,few reports on Demodex studied at the molecular level are available at present.In this study our group,for the first time,cloned,sequenced and analyzed the chitin synthase(CHS) gene fragments of Demodex folliculorum,Demodex brevis,and Demodex canis(three isolates from each species) from Xi'an China,by designing specific primers based on the only partial sequence of the CHS gene of D.canis from Japan,retrieved from GenBank.Results show that amplification was successful only in three D.canis isolates and one D.brevis isolate out of the nine Demodex isolates.The obtained fragments were sequenced to be 339 bp for D.canis and 338 bp for D.brevis.The CHS gene sequence similarities between the three Xi'an D.canis isolates and one Japanese D.canis isolate ranged from 99.7% to 100.0%,and those between four D.canis isolates and one D.brevis isolate were 99.1%-99.4%.Phylogenetic trees based on maximum parsimony(MP) and maximum likelihood(ML) methods shared the same clusters,according with the traditional classification.Two open reading frames(ORFs) were identified in each CHS gene sequenced,and their corresponding amino acid sequences were located at the catalytic domain.The relatively conserved sequences could be deduced to be a CHS class A gene,which is associated with chitin synthesis in the integument of Demodex mites.
