Purpose: Demodex folliculorum is a transparent mite, 0.3 - 0.4 mm long, which asymptomatically parasitizes the human pilosebaceous follicles. D. folliculorum is observed in normal skin with a prevalence of 100% and a ...Purpose: Demodex folliculorum is a transparent mite, 0.3 - 0.4 mm long, which asymptomatically parasitizes the human pilosebaceous follicles. D. folliculorum is observed in normal skin with a prevalence of 100% and a density of ≤ 5 D/cm2 in the adult population. Materials and Methods: This study evaluated the differences in pH on the five facial sites between the two populations with and without D. folliculorum. The relationship between pH and skin surface oil was analyzed in populations with and without Demodex mites. Mongolian 750 subjects (370 males and 380 females) aged 16 - 84 years, who lived in Ulaanbaatar city, were enrolled in this study. The eligibility criteria included a minimum age of 16 and no physical and dermatologic illness, no cosmetic. Results: Skin surface oil among the five facial areas differed significantly in both subjects with and without Demodex folliculorum (P < 0.001). When the skin surface oil on the T-zone, U-zone was compared, those on the T-zone were significantly higher than those of the U-zone (P < 0.001) in both populations (P< 0.01). The pH levels on the five facial sites, and U-zone, T-zone and MFpH differed significantly in among both subjects with and without Demodex folliculorum (P < 0.001). In both groups, the pH levels of the U-zone were significantly lower than the pH of the T-zone (P Conclusions: Among the five facial sites in subjects with Demodex folliculorum, there were significant negative correlations between skin surface oil and pH on the forehead (p < 0.001, r = 652), cheek (P < 0.001, r = 0.656), nose (P < 0.001, r = 0.754), chin (P < 0.001, r = 0.679), and T-zone (P < 0.001, r = 0.698), MFSE-MFpH (P < 0.001, r = 0.483). In contrast, among the five sites in subjects without Demodex folliculorum, a significant negative correlation between skin surface oil and pH was observed on the forehead (p < 0.001, r = 766), cheek (P < 0.001, r = 0.798), nose (P < 0.001, r = 0.706), chin (P < 0.001, r = 0.823), and T-zone (P < 0.001, r = 0.602), U-zone (P < 0.001, r = -0.550)展开更多
For a long time,classification of Demodex mites has been based mainly on their hosts and phenotypic characteristics.A new subspecies of Demodex folliculorum has been proposed,but not confirmed.Here,cox1 partial sequen...For a long time,classification of Demodex mites has been based mainly on their hosts and phenotypic characteristics.A new subspecies of Demodex folliculorum has been proposed,but not confirmed.Here,cox1 partial sequences of nine isolates of three Demodex species from two geographical sources(China and Spain) were studied to conduct molecular identification of D.folliculorum.Sequencing showed that the mitochondrial cox1 fragments of five D.folliculorum isolates from the facial skin of Chinese individuals were 429 bp long and that their sequence identity was 97.4%.The average sequence divergence was 1.24% among the five Chinese isolates,0.94% between the two geographical isolate groups(China(5) and Spain(1)),and 2.15% between the two facial tissue sources(facial skin(6) and eyelids(1)).The genetic distance and rate of third-position nucleotide transition/transversion were 0.0125,2.7(3/1) among the five Chinese isolates,0.0094,3.1(3/1) between the two geographical isolate groups,and 0.0217,4.4(3/1) between the two facial tissue sources.Phylogenetic trees showed that D.folliculorum from the two geographical isolate groups did not form sister clades,while those from different facial tissue sources did.According to the molecular characteristics,it appears that subspecies differentiation might not have occurred and that D.folliculorum isolates from the two geographical sources are of the same population.However,population differentiation might be occurring between isolates from facial skin and eyelids.展开更多
文摘Purpose: Demodex folliculorum is a transparent mite, 0.3 - 0.4 mm long, which asymptomatically parasitizes the human pilosebaceous follicles. D. folliculorum is observed in normal skin with a prevalence of 100% and a density of ≤ 5 D/cm2 in the adult population. Materials and Methods: This study evaluated the differences in pH on the five facial sites between the two populations with and without D. folliculorum. The relationship between pH and skin surface oil was analyzed in populations with and without Demodex mites. Mongolian 750 subjects (370 males and 380 females) aged 16 - 84 years, who lived in Ulaanbaatar city, were enrolled in this study. The eligibility criteria included a minimum age of 16 and no physical and dermatologic illness, no cosmetic. Results: Skin surface oil among the five facial areas differed significantly in both subjects with and without Demodex folliculorum (P < 0.001). When the skin surface oil on the T-zone, U-zone was compared, those on the T-zone were significantly higher than those of the U-zone (P < 0.001) in both populations (P< 0.01). The pH levels on the five facial sites, and U-zone, T-zone and MFpH differed significantly in among both subjects with and without Demodex folliculorum (P < 0.001). In both groups, the pH levels of the U-zone were significantly lower than the pH of the T-zone (P Conclusions: Among the five facial sites in subjects with Demodex folliculorum, there were significant negative correlations between skin surface oil and pH on the forehead (p < 0.001, r = 652), cheek (P < 0.001, r = 0.656), nose (P < 0.001, r = 0.754), chin (P < 0.001, r = 0.679), and T-zone (P < 0.001, r = 0.698), MFSE-MFpH (P < 0.001, r = 0.483). In contrast, among the five sites in subjects without Demodex folliculorum, a significant negative correlation between skin surface oil and pH was observed on the forehead (p < 0.001, r = 766), cheek (P < 0.001, r = 0.798), nose (P < 0.001, r = 0.706), chin (P < 0.001, r = 0.823), and T-zone (P < 0.001, r = 0.602), U-zone (P < 0.001, r = -0.550)
基金Project(No. 81271856)supported by the National Natural Science Foundation of China
文摘For a long time,classification of Demodex mites has been based mainly on their hosts and phenotypic characteristics.A new subspecies of Demodex folliculorum has been proposed,but not confirmed.Here,cox1 partial sequences of nine isolates of three Demodex species from two geographical sources(China and Spain) were studied to conduct molecular identification of D.folliculorum.Sequencing showed that the mitochondrial cox1 fragments of five D.folliculorum isolates from the facial skin of Chinese individuals were 429 bp long and that their sequence identity was 97.4%.The average sequence divergence was 1.24% among the five Chinese isolates,0.94% between the two geographical isolate groups(China(5) and Spain(1)),and 2.15% between the two facial tissue sources(facial skin(6) and eyelids(1)).The genetic distance and rate of third-position nucleotide transition/transversion were 0.0125,2.7(3/1) among the five Chinese isolates,0.0094,3.1(3/1) between the two geographical isolate groups,and 0.0217,4.4(3/1) between the two facial tissue sources.Phylogenetic trees showed that D.folliculorum from the two geographical isolate groups did not form sister clades,while those from different facial tissue sources did.According to the molecular characteristics,it appears that subspecies differentiation might not have occurred and that D.folliculorum isolates from the two geographical sources are of the same population.However,population differentiation might be occurring between isolates from facial skin and eyelids.
