Noncovalent Tagging for Identifying Unknown Contaminants of Specific Bioactivity in Environmental Water.

Identifying contaminants of specific bioactivities from complicated environmental matrices remains costly and time-consuming, as it requires us to not only resolve their structures but also determine their bioactivities. Herein, a novel noncovalent tagging method is integrated in mass spectrometry for identifying unknown contaminants that target dopamine (DA) receptors. Via proteolysis of bovine serum albumin, a stereoselective hexapeptide (ACFAVE) is selected for noncovalently tagging the contaminants that possess the stereostructural characteristics of binding to DA receptors. The tagged contaminants can be readily distinguished from the coexisting species for subsequent structural analysis based on the tagging-induced shifts of the mass-to-charge ratios. Thus, both bioactivity evaluation and structure analysis are accomplished via mass spectrometry. By using this method, 1,3-diphenylguanidine (DPG), a widely used additive in rubber and plastics, is successfully identified out of 2495 features detected in the Pearl River water, with its concentration determined as only 9.8 µg L-1. Furthermore, DPG is confirmed as a potential disrupter to the DA receptors via a simulated docking experiment, which has not been reported before. The present noncovalent tagging method provides a cost-effective and time-efficient way of identifying bioactive molecules in complicated matrices. And proteolysis of proteins is promising for developing more taggants with other desired stereoselectivities in the future.

Hydrogen bond networks in gas-phase complex anions.

Hydrogen bond networks (HBNs) have piqued the interest of the scientific community due to their crucial roles in nature. However, HBNs that are isolated from complicated backgrounds for unraveling their characteristics are still scarce. Herein, we propose that HBNs exist in complex anions formed between α-cyclodextrin (α-CD) and four benzoic acids (RBAs) in the gas phase. The complex anions are facilely extracted from solutions via the electrospray ionization technique, and subsequently activated through collision for the investigation of their transition dynamics. It is revealed that the generation of deprotonated α-CD and neutral RBAs is the unexpected dominant dissociation pathway for all the four complex anions, and the complex anions formed from more acidic RBAs exhibit higher stabilities. These dissociation results are successfully explained by the cooperative stretching dynamics of the proposed HBNs that are formed involving the intramolecular HBN of α-CD and the intermolecular hydrogen bonds (HBs) between α-CD and RBAs. Furthermore, the rarely observed low barrier HBs (LBHBs) are suggested to be present in the HBNs. It is believed that the present complex anions can serve as a facilely accessible and informative model for studying HBNs in the future.

Genetic analysis of a SARS-CoV-2 Omicron variant from a Chinese traveller returning from overseas.

Since the SARS-CoV-2 Omicron variant was first reported from South Africa, it has rapidly spread in over 100 countries. Only two cases infected by the Omicron variant were recently identified in China. The one case in Guangzhou has a relatively long incubation time and mild symptoms. Analysis of the complete viral genome sequence shows three missing Omicron unique mutations and one additional mutation in the newly characterized genome. These unique mutations may be related to the clinical presentation in this case.

COVID-19 Outbreak Associated with Air Conditioning in Restaurant, Guangzhou, China, 2020.

During January 26-February 10, 2020, an outbreak of 2019 novel coronavirus disease in an air-conditioned restaurant in Guangzhou, China, involved 3 family clusters. The airflow direction was consistent with droplet transmission. To prevent the spread of the virus in restaurants, we recommend increasing the distance between tables and improving ventilation.

Direct thiocarbamation of imidazoheterocycles via dual C-H sulfurization.

A copper-catalyzed DTBP oxidative dual C-H sulfurization has been developed for the direct thiocarbamation of imidazopyridines using a combination of elemental sulfur and formamides as carbamothioyl surrogates. NBS (bromo succinimide) was found to promote the thiocarbamation in good yields. This dual C-H sulfurization strategy enables access to a wide range of carbamothioyl imidazoheterocycles without the use of highly toxic phosgene.

Iodine-promoted radical alkyl sulfuration of imidazopyridines with dialkyl azo compounds and elemental sulfur.

Dialkyl azo compounds were found to be effective alkyl radical sources for direct alkyl sulfuration with imidazopyridines using elemental sulfur under metal-free conditions. Iodine, an inexpensive and mild reagent, could promote alkyl sulfuration. A variety of quaternary cyanoalkyl radicals were successfully coupled with elemental sulfur. A subsequent C-H sulfuration of imidazopyridines afforded a diverse array of imidazopyridine derivatives bearing cyanoalkylthio groups. The cyano group could be modified and further underwent condensation with 2-aminothiazole to afford an interesting heterocyclic amide. Control experiments showed that iodine could greatly suppress the self-coupling of cyanoalkyl radicals, thus making the sulfuration proceed smoothly.

Role of sleep quality in mediating the relationship between sexual minority status and suicidal behavior among Chinese adolescents.

BACKGROUND: Studies suggest that sexual minority adolescents experience higher rates of sleep disturbance than their heterosexual peers, and disturbed sleep is a well-known risk factor for suicidality. This study aimed to explore whether sleep quality had mediating effects on the relationship between sexual minority status and suicidal behavior in Chinese adolescents. METHODS: We analyzed data collected from 7th to 12th graders from seven randomly selected provinces of People's Republic of China in the 2015 School-Based Chinese Adolescents Health Survey. The 123,459 students who completed questionnaires regarding sexual attraction, the Pittsburgh Sleep Quality Index, past-year suicidal ideation, and past-year suicide attempts were included in our study (response rate: 95.9%). RESULTS: After adjustment for covariates, sexual minority status was associated with suicidal ideation (adjusted odds ratio =1.82, 95% CI=1.69-1.95) and suicide attempts (adjusted odds ratio =2.16, 95% CI=1.82-2.56). Sleep quality partially mediated the effects of sexual minority status on suicidal ideation (standardized ß estimate=0.009, 95% CI=0.007-0.012) and suicide attempts (standardized ß estimate=0.004, 95% CI=0.003-0.005). CONCLUSION: Poor sleep quality partially explained the increased risk of suicidality for Chinese sexual minority adolescents. To prevent subsequent suicidality, suicide interventions targeting sexual minorities should be made, with a focus on their disparities in sleep disturbance and sleep health promotion.

Chinese Sexual Minority Male Adolescents' Suicidality and Body Mass Index.

Excess weight status may increase the risk of suicidality among sexual minority females, but few studies have examined this suicidality disparity in sexual minority males. This study examined the association between sexual minority status and suicide attempts in Chinese male adolescents and tested whether body mass index (BMI) had a moderating effect on that association. Data were collected from 7th to 12th graders from seven randomly selected provinces of China in the 2015 School-Based Chinese Adolescents Health Survey. In total, 72,409 male students completed the questionnaires regarding sexual attraction, self-reported weight and height, and suicide attempts. After adjustment for covariates, sexual minority status was associated with suicide attempts among male students (AOR = 1.74, 95% CI = 1.57⁻1.93). Stratification analyses showed that BMI category moderated this association; compared with the results before stratification analyses, sexual minority males who were obese had increased risk of suicide attempts (AOR = 2.15, 95% CI = 1.09⁻4.24), sexual minority males who were overweight had reduced odds of suicide attempts (AOR = 1.40, 95% CI = 1.01⁻1.92), and no significant association change was found in sexual minority males who were underweight (AOR = 1.82, 95% CI = 1.43⁻2.33). Our study indicated that BMI moderated the risk of suicide attempts in sexual minority males. Suicide prevention targeting sexual minority males should be focused on weight status disparity and the creation of a positive climate to reduce minority stressors due to body image.

Association between sexual minority status and suicidal behavior among Chinese adolescents: A moderated mediation model.

BACKGROUND: Evidence shows sexual minority adolescents have a higher risk of suicidality than their heterosexual peers due to minority stressors or lack of social support, but it remains unclear how the combined effects of these influence factors impact suicidality in this population. In this study, we examine whether school victimization mediates association between sexual minority status and suicidal behavior of adolescents and explore whether such mediation is moderated by interpersonal relationships. METHODS: We sampled a large nationally representative dataset comprising data collected from 7th to 12th graders (the 2015 School-based Chinese Adolescents Health Survey) using a multistage, stratified-cluster, random-sampling method. Our sample consisted of 123,459 students who completed questionnaires regarding their sexual minority status, suicidal ideation, suicide attempts, school victimization, classmate relations, and teacher-classmate relations. RESULTS: Using a moderated mediation model, we found that school victimization mediated the effects of sexual minority status on suicidal ideation (indirect effect = 0.0296, 95% confidence intervals (CI) = 0.0259-0.0333) and suicide attempts (indirect effect = 0.0086, 95% CI = 0.0074-0.0100). These indirect effects were moderated by interpersonal relationships, and a greater effect was seen among sexual minority students with poor classmate or teacher-classmate relations. LIMITATIONS: Our study sample included only students attending school, and interpretation of the direction of the observed associations is limited due to the cross-sectional design. CONCLUSIONS: Interpersonal relationships moderate the indirect effects of school victimization on association between sexual minority status and suicidal behavior. Early intervention addressing school violence combined with improving the quality of relationships with school peers would help prevent suicidality in sexual minority adolescents.