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Although physiological changes are the most evident indicators of skin aging by alteration of the skin's structure and function, we question whether skin aging is also affected by the structure and assembly process of the skin microbiome. We analysed the skin microbiomes of 73 healthy Chinese women in two age groups (25-35 years old and 56-63 years old) using 16S rRNA gene amplicon sequencing; the overall microbiome structure was significantly different between the two age groups. An analysis using ecological theory to evaluate the process of microbial community assembly processes revealed that the microbiomes of the older group were formed under a greater influence of the niche-based process, with the network of microbes being more collapsed than that of the younger group. Inferred metagenomic functional pathways associated with replication and repair were relatively more predominant in the younger group whereas, among the various metabolism-related pathways, those associated with biodegradation were more predominant in the older group. Interestingly, we found two segregated sub-typing patterns in the younger group which were also observed in the skin microbiomes of young Chinese women living in four other cities in China. The results of our study highlights candidate microbes and functional pathways that are important for future research into preventing skin aging and which could lead to a comprehensive understanding of age-related skin microbiome characteristics.

Because healthcare workers (HCWs) are at high risk for tuberculosis (TB) infection, it is essential to research the prevalence of latent TB infection (LTBI) and to implement health interventions including early treatment of LTBI and TB infection control measures. The purpose of the study was to determine the prevalence and risk factors for LTBI using interferon-γ release assay (IGRA) among HCWs in South Korea. The cross-sectional study was carried in the National Health Insurance Service Ilsan Hospital, which is a 740-bed general hospital, South Korea. HCWs who participated in this survey were required to complete a questionnaire and IGRA was performed. Of the 1,655 HCWs, 271 results were positive and the prevalence of LTBI was 16% (95% CI; 15-18%). In the multivariate analysis, age (OR; 2.201, 95% CI; 1.911-2.536, P < 0.001), male sex (OR; 1.523, 95% CI; 1.133-2.046, P = 0.005), contact active TB patients (OR; 1.461, 95% CI; 1.061-2.010, P = 0.02) and diabetes (OR; 2.837, 95% CI; 1.001-8.044, P = 0.05) were significant risk factors for LTBI. LTBI among HCWs in Korea, although prevalent, might not exceed the background level of the general population. Because contact with active TB patients has been identified as a risk factor for LTBI, more effective TB infection control measures are essential in healthcare facilities and congregate settings.

Short-chain polyphosphate (polyP) is released from platelets upon platelet activation, but it is not clear if it contributes to thrombosis. PolyP has increased propensity to clot blood with increased polymer length and when localized onto particles, but it is unknown whether spatial localization of short-chain polyP can accelerate clotting of flowing blood. Here, numerical simulations predicted the effect of localization of polyP on clotting under flow, and this was tested in vitro using microfluidics. Synthetic polyP was more effective at triggering clotting of flowing blood plasma when localized on a surface than when solubilized in solution or when localized as nanoparticles, accelerating clotting at 10-200 fold lower concentrations, particularly at low to sub-physiological shear rates typical of where thrombosis occurs in large veins or valves. Thus, sub-micromolar concentrations of short-chain polyP can accelerate clotting of flowing blood plasma under flow at low to sub-physiological shear rates. However, a physiological mechanism for the localization of polyP to platelet or vascular surfaces remains unknown., Competing Interests: S.A.S., D.K., G.D.S., and J.H.M. are co-inventors on pending patent applications covering potential medical uses of SNP-polyP. A.J.D. and Y.L. are co-inventors on a pending patent application related to the therapeutic usage and delivery of NP-polyP. D.K., G.D.S., and J.H.M. declare competing financial interests in this work. The remaining authors declare no competing financial interests.

To elucidate the genes responsible for constitutive human skin color, we measured the extent of skin pigmentation in the buttock, representative of lifelong non-sun-exposed skin, and conducted a gene mapping study on skin color in an isolated Mongolian population composed of 344 individuals from 59 families who lived in Dashbalbar, Mongolia. The heritability of constitutive skin color was 0.82, indicating significant genetic association on this trait. Through the linkage analysis using 1,039 short tandem repeat (STR) microsatellite markers, we identified a novel genomic region regulating constitutive skin color on 11q24.2 with an logarithm of odds (LOD) score of 3.39. In addition, we also found other candidate regions on 17q23.2, 6q25.1, and 13q33.2 (LOD ≥ 2). Family-based association tests on these regions with suggestive linkage peaks revealed ten and two significant single nucleotide polymorphisms (SNPs) on the linkage regions of chromosome 11 and 17, respectively. We were able to discover four possible candidate genes that would be implicated to regulate human skin color: ETS1, UBASH3B, ASAM, and CLTC.