A label-free ratiometric fluorescent aptasensor based on a peroxidase-mimetic multifunctional ZrFe-MOF for the determination of tetrodotoxin.

A Fe/Zr bimetal-organic framework (ZrFe-MOF) is utilized to establish a ratiometric fluorescent aptasensor for the determination of tetrodotoxin (TTX). The multifunctional ZrFe-MOF possesses inherent fluorescence at 445 nm wavelength, peroxidase-mimetic activity, and specific recognition and adsorption capabilities for aptamers, owing to its organic ligand, and Fe and Zr nodes. The peroxidation of o-phenylenediamine (OPD) substrate generates fluorescent 2,3-diaminophenazine (OPDox) at 555 nm wavelength, thus quenching the inherent fluorescence of ZrFe-MOF because of the fluorescence resonance energy transfer (FRET) effect. TTX aptamers, which are absorbed on the material surface without immobilization or fluorescent labeling, inhibit the peroxidase-mimetic activity of ZrFe-MOF. It causes the decreased OPDox fluorescence at 555 nm wavelength and the inverse restoration of ZrFe-MOF fluorescence at 445 nm wavelength. With TTX, the aptamers specifically bind to TTX, triggering rigid complex release from ZrFe-MOF surface and reactivating its peroxidase-mimetic activity. Consequently, the two fluorescence signals exhibit opposite changes. Employing this ratiometric strategy, the determination of TTX is achieved with a detection limit of 0.027 ng/mL and a linear range of 0.05-500 ng/mL. This aptasensor also successfully determines TTX concentrations in puffer fish and clam samples, demonstrating its promising application for monitoring trace TTX in food safety.

Ultrasensitive Detection of 17ß-Estradiol (E2) Based on Multistep Isothermal Amplification.

17ß-Estradiol (E2) can cause an adverse effect on the human endocrine system even at the nanomolar level. Measurements of very low levels of E2 remain a critical challenge due to insufficient sensitivity. In this study, a multistep isothermal amplification fluorescence strategy was constructed, which could realize the exponential amplification of target E2. Specifically, strand displacement reaction (SDA), rolling circle amplification (RCA), and multiprimed rolling circle amplification (MRCA) were combined in a series to quantify trace complementary strand of E2 (cDNA). The E2 aptamer and cDNA were hybridized and modified on the magnetic beads. E2 could bind to its aptamer and cause the release of the cDNA. Then, cDNA would combine with the template DNA, initiating the SDA-RCA-MRCA. The molecular beacons, possessing low background signal, whose fluorescence was quenched in the state of chain folding, could be specifically recognized by the long single-stranded DNA (L-ssDNA) generated by the multistep isothermal amplification triggered by cDNA, and then the fluorescence of the molecular beacons could be restored. Therefore, the E2 could be quantitatively detected by the recovery fluorescence intensity. The fluorescence value showed a good linear relationship with the concentration of E2 in the range of 0.001836-183.6 nM, and the limit of detection (LOD) was as low as 63.09 fM. In addition, the recovery rates of this method spiked in milk and water were 80.8-107.0%, respectively. This method has the advantage of multistep isothermal amplification to obtain abundant fluorescence signals, which may provide a new possibility for highly sensitive detection of other small-molecule targets.

Association between body mass index and burnout among nurses in China: a cross-sectional study.

OBJECTIVES: Body mass index (BMI) can affect an individual's health. The night shift is a characteristic of the nursing profession, which is associated with an abnormal BMI. However, few studies have investigated the association between BMI and burnout in Chinese nurses. This study examined the association between BMI and burnout among Chinese nurses. METHODS: A total of 1863 nurses from 12 tertiary hospitals in Shandong Province of China were selected. BMI was calculated as body weight divided by height squared. The Maslach Burnout Service Inventory General Survey (MBI-GS) was used to measure the level of burnout among nurses. Ordinal logistic regression was used to analyse the association between BMI and burnout. RESULTS: In this study, the prevalence of normal BMI, underweight, overweight, and obesity was 69.2%, 7.5%, 18.2%, and 5.2%, respectively. The prevalence of high emotional exhaustion, high cynicism, and low personal accomplishment among nurses was 26.1%, 38.7%, and 35.6%, respectively. Nurses who were obese were more likely to have high levels of emotional exhaustion (OR=1.493, 95% CI: 1.011 to 2.206) and cynicism (OR=1.511, 95% CI: 1.014 to 2.253), and nurses who were underweight were more likely to have high levels of cynicism (OR=1.593, 95% CI: 1.137 to 2.232) compared with those who were normal weight. CONCLUSIONS: Obesity was positively associated with emotional exhaustion and cynicism, and being underweight was only positively associated with cynicism among Chinese nurses. Hospital administrators should consider BMI when taking effective measures to reduce burnout among nurses.

Ultrasensitive Ochratoxin A Detection in Cereal Products Using a Fluorescent Aptasensor Based on RecJf Exonuclease-Assisted Target Recycling.

Ochratoxin A (OTA) is a mycotoxin widely found in foodstuffs such as cereal grains. It greatly threatens human health owing to its strong toxicity and high stability. Aptasensors have emerged as promising tools for the analysis of small molecule contaminants. Nucleic-acid-based signal amplification enables detectable signals to be obtained from aptasensors. However, this strategy often requires the use of complex primers or multiple enzymes, entailing problems such as complex system instability. Herein, we propose a fluorescent aptasensor for the ultrasensitive detection of OTA in cereal products, with signal amplification through RecJf exonuclease-assisted target recycling. The aptamer/fluorescein-labeled complementary DNA (cDNA-FAM) duplex was effectively used as the target-recognition unit as well as the potential substrate for RecJf exonuclease cleavage. When the target invaded the aptamer-cDNA-FAM duplex to release cDNA-FAM, RecJf exonuclease could cleave the aptamer bonded with the target and release the target. Thus, the target-triggered cleavage cycling would continuously generate cDNA-FAM as a signaling group, specifically amplifying the response signal. The proposed exonuclease-assisted fluorescent aptasensor exhibited a good linear relationship with OTA concentration in the range from 1 pg/mL to 10 ng/mL with an ultralow limit of detection (6.2 ng/kg of cereal). The analytical method showed that recoveries of the cereal samples ranged from 83.7 to 109.3% with a repeatability relative standard deviation below 8%. Importantly, the proposed strategy is expected to become a common detection model because it can be adapted for other targets by replacing the aptamer. Thus, this model can guide the development of facile approaches for point-of-care testing applications.

Mapping the Research on Health Policy and Services in the Last Decade (2009-2018): A Bibliometric Analysis.

Background: Health policy and services is a continuously evolving field of research that can inform prevention and control efforts for a variety of health conditions. The "Healthy China" strategy reflects the demand to formulate health policy that suits China's national needs and goals. Applying bibliometric analysis to grasp the general situation of health policy and services research globally will be conducive to informing China's designated health plans and initiatives. Method: A bibliometric analysis of 58,065 articles on "Health Policy and Services" topics was conducted. The document type was restricted to journal articles that were published in the Web of Science database between the time parameter of January 1, 2009 to December 31, 2018. Data was collected on indicators such as the annual number of publications in the field of health policy and services, the country where the publication is issued, the publication organization, the source journal, the frequency of citations, research hotspots, and academic areas. Results: The overall number of articles published in Web of Science on health policy and services research has increased over time. The United States has the largest number of articles in the field. The institution with the highest number of citations in the field is Harvard University and the journal with the most published articles in the field is Health Affairs. Research hotspots in the health policy and services field include topics such as "HIV Infections," "Primary Health Care," "Delivery of Health Care," and "Health Services Accessibility." Conclusion: Experts in the field of health policy and services globally are dedicated to researching the most effective ways to improve people's health and living standards. There is a certain gap in the depth of health policy and services research between China and developed countries and regions such as Europe or America. China must learn from foreign experience to conduct meaningful and informative research that can aid in the formulation of multi-dimensional health policies in specific areas such as environmental infectious diseases, where attention is needed in areas beyond the medical and health system.

Out-Of-Pocket Expenditure Associated with Physical Inactivity, Excessive Weight, and Obesity in China: Quantile Regression Approach.

INTRODUCTION: Previous studies exploring associations of physical inactivity, obesity, and out-of-pocket expenditure (OOPE) mainly used traditional linear regression, and little is known about the effect of both physical inactivity and obesity on OOPE across the percentile distribution. This study aims to assess the effects of physical inactivity and obesity on OOPE in China using a quantile regression approach. METHODS: Study participants included 10,687 respondents aged 45 years and older from the recent wave of the China Health and Retirement Longitudinal Study in 2015. Linear regression and quantile regression models were used to examine the association of physical activity, body weight with annual OOPE. RESULTS: Overall, the proportion of overweight and obesity was 33.2% and 5.8%, respectively. The proportion of individuals performing high-level, moderate-level, and low-level physical activity was 55.2%, 12.7%, and 32.1%, respectively. The effects of low-level physical activity on annual OOPE were small at the bottom quantiles but more pronounced at higher quantiles. Respondents with low-level activity had an increased annual OOPE of 26.9 USD, 150.3 USD, and 1,534.4 USD, at the 10th, 50th, and 90th percentiles, respectively, compared with those with high-level activity. The effects of overweight and obesity on OOPE were also small at the bottom quantiles but more pronounced at higher quantiles. CONCLUSION: Interventions that improve the lifestyles and unhealthy behaviors among people with obesity and physical inactivity are likely to yield substantial financial gains for the individual and health systems in China.