Indigenous Tibetan people have lived on the Tibetan Plateau for millennia. There is a long-standing question about the genetic basis of high-altitude adaptation in Tibetans. We conduct a genome-wide study of 7.3 million genotyped and imputed SNPs of 3,008 Tibetans and 7,287 non-Tibetan individuals of Eastern Asian ancestry. Using this large dataset, we detect signals of high-altitude adaptation at nine genomic loci, of which seven are unique. The alleles under natural selection at two of these loci [methylenetetrahydrofolate reductase (MTHFR) and EPAS1] are strongly associated with blood-related phenotypes, such as hemoglobin, homocysteine, and folate in Tibetans. The folate-increasing allele of rs1801133 at the MTHFR locus has an increased frequency in Tibetans more than expected under a drift model, which is probably a consequence of adaptation to high UV radiation. These findings provide important insights into understanding the genomic consequences of high-altitude adaptation in Tibetans.high-altitude adaptation | Tibetans | genome-wide association study | mixed linear model | polygenic selection G enetic adaptation to a novel environment is a fundamental process for the survival and adaptation of a species. In humans, one of the most recent examples is adaptation to high altitude, such as the Tibetan highlands. The Tibetan Plateau (TP; also known as the Qinghai-Tibet Plateau in China) has an average elevation of ∼4,000 m above sea level, where the oxygen concentration is ∼40% lower (1) and UV radiation is ∼30% stronger (2) than at sea level. The indigenous Tibetan people have developed a distinctive set of physiological characteristics to adapt to the extreme environmental conditions in the highlands (1). Previous population-based genetic studies have reported evidence that genetic variants at the EPAS1 and EGLN1 loci have been under positive natural selection (3-7). These genetic variants are associated with phenotypic variation of hemoglobin concentration (HGB) in Tibetans (3-5). The EPAS1 gene, which encodes the hypoxia inducible factor-2α (HIF-2α) subunit of HIF complex, is a transcription factor involved in body response to hypoxia (8, 9). EGLN1 encodes PHD2, which is a major oxygen-dependent negative regulator of HIFs (10, 11). Apart from these two known genes that have biological relevance to hypoxia adaptation (3-7, 12), several other candidate gene loci (e.g., PPARA and HBB) have been highlighted in recent studies (3,4,(13)(14)(15). Genetic adaptation to high altitude, however, is likely to be a complex process, with a large number of genes involved in response to not only hypoxia but also, other extreme environmental conditions, such as low temperature, high UV radiation, and insufficient food supply. If the strength of natural selection at these gene loci has been small to moderate, these loci would not be detected in previous studies (3-7) of small sample size (typically n < 150). In this study, we perform a largescale genome-wide study to detect genetic signals of high-altitude adaptation in 3...

The global tuberculosis crisis urgently demands new, efficacious, orally available drugs with the potential to shorten and simplify the long and complex treatments for drug-sensitive and drug-resistant disease. Clofazimine, a riminophenazine used for many years to treat leprosy, demonstrates efficacy in animal models of tuberculosis via a novel mode of action. However, clofazimine's physicochemical and pharmacokinetic properties contribute to side effects that limit its use; in particular, an extremely long half-life and propensity for tissue accumulation together with clofazimine's dye properties leads to unwelcome skin discoloration. We recently conducted a systematic structure-activity study of more than 500 riminophenazine analogs for antiMycobacterium tuberculosis activity. We describe here the characteristics of 12 prioritized compounds in more detail. The new riminophenazine analogs demonstrated enhanced in vitro activity compared to clofazimine against replicating M. tuberculosis H37Rv, as well as panels of drug-sensitive and drug-resistant clinical isolates. The new compounds demonstrate at least equivalent activity compared to clofazimine against intracellular M. tuberculosis and, in addition, most of them were active against nonreplicating M. tuberculosis. Eleven of these more water-soluble riminophenazine analogs possess shorter half-lives than clofazimine when dosed orally to mice, suggesting that they may accumulate less. Most importantly, the nine compounds that progressed to efficacy testing demonstrated inhibition of bacterial growth in the lungs that is superior to the activity of an equivalent dose of clofazimine when administered orally for 20 days in a murine model of acute tuberculosis. The efficacy of these compounds, along with their decreased potential for accumulation and therefore perhaps also for tissue discoloration, warrants further study. Despite global efforts, tuberculosis (TB) remains responsible for the second greatest number of deaths due to an infectious disease with 1.7 million deaths reported due to TB in 2009 (45). Of particular concern, the increasing prevalence of TB caused by multidrug-resistant (MDR) and extensively drugresistant (XDR) strains of Mycobacterium tuberculosis puts at risk hard-won gains to public health. MDR-TB treatment regimens, where available, comprise multiple expensive drugs with limited efficacy and significant toxicity that must be administered by both oral and parenteral routes for up to 24 months (30). Treatment of drug-sensitive TB is also long and complex, requiring at least 6 months of a four-drug regimen to achieve a stable cure. The first-line TB drugs are poorly tolerated, reducing compliance and increasing the risk of resistance development. New TB drugs that are safe, orally available, have novel modes of action and efficacy sufficient to simplify and shorten the regimen required to cure TB would impact both patients and TB control by providing improved treatment for drug-resistant TB and by providing a faster, more tolerable cure for dr...

Clofazimine (CFZ), a member of the riminophenazine class, has been studied in clinical trials for the treatment of multidrug-resistant tuberculosis (MDR-TB). CFZ has several side effects which can be attributed to its extremely high lipophilicity. A series of novel riminophenazine analogues bearing a C-2 pyridyl substituent was designed and synthesized with the goal of maintaining potent activity against Mycobacterium tuberculosis (M. tuberculosis) while improving upon its safety profile by lowering the lipophilicity. All compounds were evaluated for their in vitro activity and cytotoxicity. The results demonstrated that many new compounds had potent activity against M. tuberculosis with MICs of less than 0.03 μg/mL and low cytotoxicity with IC(50) values greater than 64 μg/mL. Some compounds were tested for in vivo efficacy against MDR-TB in an experimental mouse infection model. Two compounds demonstrated equivalent or better efficacy than CFZ in this model with significantly reduced skin discoloration potential.

BackgroundAn aptamer based biosensor (aptasensor) was developed and evaluated for rapid colorimetric detection of Escherichia coli (E. coli) O157:H7.Methodology/Principal FindingsThe aptasensor was assembled by modifying the truncated lipopolysaccharides (LPS)-binding aptamer on the surface of nanoscale polydiacetylene (PDA) vesicle using peptide bonding between the carboxyl group of the vesicle and the amine group of the aptamer. Molecular recognition between E. coli O157:H7 and aptamer at the interface of the vesicle lead to blue-red transition of PDA which was readily visible to the naked eyes and could be quantified by colorimetric responses (CR). Confocal laser scanning microscope (CLSM) and transmission electron microscopy (TEM) was used to confirm the specific interactions between the truncated aptamer and E. coli O157:H7. The aptasensor could detect cellular concentrations in a range of 104∼ 108 colony-forming units (CFU)/ml within 2 hours and its specificity was 100% for detection of E. coli O157:H7. Compared with the standard culture method, the correspondent rate was 98.5% for the detection of E. coli O157:H7 on 203 clinical fecal specimens with our aptasensor.ConclusionsThe new aptasensor represents a significant advancement in detection capabilities based on the combination of nucleic acid aptamer with PDA vesicle, and offers a specific and convenient screening method for the detection of pathogenic bacteria. This technic could also be applied in areas from clinical analysis to biological terrorism defense, especially in low-resource settings.

Th17 and regulatory T cells, involved in the pathogenesis of several autoimmune diseases, are new lineages of CD4+ T helper cells. However, the role of their imbalance in human leukocyte antigen B27-associated acute anterior uveitis has not been elucidated. In our study, the percentages of Th17 and Treg cells, their molecular markers and related factors in peripheral blood of patients and healthy controls were measured by flow cytometry, real-time RT-PCR and ELISA. We observed a remarkable increase of CD4+ and CD4+IL-17+ T cells in peripheral blood of patients compared to controls. The molecular markers and related factors of Th17 cell were also showed a distinct elevation. Interestingly, we observed an obvious decrease of CD4+CD25+Foxp3+ T cells and Foxp3 mRNA level in patients. The ratio of Th17/Treg in patients was dramatically higher than controls. Moreover, the ratio of Th17/Treg cells had a more significantly positive correlation with the disease activity score than Th17 cells whereas Treg cells had a negative correlation. Our findings demonstrated a distinct increase of Th17 cells and a significant decrease of Treg cells in patients compared to controls. The imbalance of Th17 and Treg cells may play a vital role in the pathogenesis of the disease.

Clofazimine, a member of the riminophenazine class of drugs, is the cornerstone agent for the treatment of leprosy. This agent is currently being studied in clinical trials for the treatment of multidrug-resistant tuberculosis to address the urgent need for new drugs that can overcome existing and emerging drug resistance. However, the use of clofazimine in tuberculosis treatment is hampered by its high lipophilicity and skin pigmentation side effects. To identify a new generation of riminophenazines that is less lipophilic and skin staining, while maintaining efficacy, we have performed a systematic structure-activity relationship (SAR) investigation by synthesizing a variety of analogs of clofazimine and evaluating their anti-tuberculosis activity. The study reveals that the central tricyclic phenazine system and the pendant aromatic rings are important for anti-tuberculosis activity. However, the phenyl groups attached to the C2 and N5 position of clofazimine can be replaced by a pyridyl group to provide analogs with improved physicochemical properties and pharmacokinetic characteristics. Replacement of the phenyl group attached to the C2 position by a pyridyl group has led to a promising new series of compounds with improved physicochemical properties, improved anti-tuberculosis potency, and reduced pigmentation potential.

As the COVID-19 pandemic spread globally, the consumption of antibiotics increased. However, no studies exist evaluating the effect of antibiotics use on the antibiotic resistance of intestinal flora in COVID-19 patients during the pandemic. To explore this issue, we collected 15 metagenomic data of fecal samples from healthy controls (HCs) with no use history of antibiotics, 23 metagenomic data of fecal samples from COVID-19 patients who received empirical antibiotics [COVID-19 (abx+)], 18 metagenomic data of fecal samples from antibiotics-naïve COVID-19 patients [COVID-19 (abx-)], and six metagenomic data of fecal samples from patients with community-acquired pneumonia [PC (abx+)] from the Sequence Read Archive database. A total of 513 antibiotic-resistant gene (ARG) subtypes of 18 ARG types were found. Antibiotic treatment resulted in a significant increase in the abundance of ARGs in intestinal flora of COVID-19 patients and markedly altered the composition of ARG profiles. Grouped comparisons of pairs of Bray-Curtis dissimilarity values demonstrated that the dissimilarity of the HC versus the COVID-19 (abx+) group was significantly higher than the dissimilarity of the HC versus the COVID-19 (abx-) group. The mexF , mexD , OXA_209 , major facilitator superfamily transporter, and EmrB_QacA family major facilitator transporter genes were the discriminative ARG subtypes for the COVID-19 (abx+) group. IS621, qacEdelta, transposase, and ISCR were significantly increased in COVID-19 (abx+) group; they greatly contributed toward explaining variation in the relative abundance of ARG types. Overall, our data provide important insights into the effect of antibiotics use on the antibiotic resistance of COVID-19 patients during the COVID-19 epidemic.

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