Search

Quantitative detection of tetracycline (TC) and nitrofurantoin (NFT) in food and water is of importance for food safety and environmental protection. Herein, Zn 2+ was introduced into a europium metal-organic framework Eu-bpdc (H 2 bpdc = 2,2'-bipyridyl-5,5'-dicarboxylic acid) to prepare a composite of Zn 2+ @Eu-bpdc, which was developed as a fluorescence sensor for TC and NFT. The fluorescence mechanism concerns with bpdc 2- ligand-to-Eu(III) charge transfer, and the detection mechanism is the inner filter effect. Zn 2+ @Eu-bpdc is a ratiometric fluorescence sensor for TC with the linear fitting equation of I 520 / I 618 = 1.94 × 10 4 M -1 C TC , whose limit of detection (LOD) is 0.148 μmol·L -1 (μM); it is also a fluorescence "turn-off" sensor for NFT with the fitting equation of ( I 0 - I )/ I = 3.62 × 10 4 M -1 C NFT and LOD = 0.0792 μM. Zn 2+ @Eu-bpdc can detect TC or NFT in lake water, honey, and milk with high accuracy. The emission color changes of paper-based Zn 2+ @Eu-bpdc depending on C TC or C NFT reveal the visualization detections of TC and NFT. With the red and green values as input signals, smartphone-assisted on-site detection is utilized to recognize the antibiotic residuals of TC and NFT by a self-programmed APP. Zn 2+ @Eu-bpdc is promising in a smartphone-assisted intelligent platform for on-site detection of TC and NFT.

The zoonosis caused by Nocardia is increasing seriously. But commonly used antibiotic drugs often lead to resistance. N. seriolae dUTPase ( Ns dUTPase) plays a key role in the proliferation of Nocardia , and was regarded as a potent drug target. However, there was little report about the Ns dUTPase inhibitors. In this study, we discovered a series of novel Ns dUTPase inhibitors to fight against Nocardia . The first crystal structure of Ns dUTPase was released, and a structure-based computational design was performed. Compounds 4b and 12b exhibited promising activities towards Ns dUTPase (IC 50  = 0.99 μM and 0.7 μM). In addition, they showed satisfied anti- Nocardia activity (MIC value ranges from 0.5 to 2 mg/L) and low cytotoxicity, which were better than approved drugs oxytetracycline and florfenicol. Molecular modelling study indicated that hydrophobic interaction might be the main contribution for ligand binding. Our results suggested that Ns dUTPase inhibitors might be a useful way to repress Nocardia .

To investigate the strain composition and drug resistance characteristics of G + (Gram positive cocci) cocci causing bloodstream infections in the People's Hospital of Inner Mongolia Autonomous Region in recent years and provide a basis for the empirical and rational use of drugs for the prevention and treatment of bloodstream infections caused by G + cocci. The strain composition and drug-resistant characteristics of G + cocci isolated from positive blood culture specimens sent to various departments of the Inner Mongolia Autonomous Region People's Hospital from January 2015 to December 2022 were retrospectively analyzed, and the higher detection rates of Staphylococcus hominis and Staphylococcus epidermidis, Enterococcus faecium and Enterococcus faecalis, and methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) were examined. MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) were comparatively analyzed for resistance. The resistance data were analyzed by Whonet 5.6 statistical software, the significance of difference was analyzed by SPSS 22.0 software, and the resistance rate was compared by χ 2 test. The results showed that 1 209 strains of G + cocci, in terms of the composition ratio, from high to low, were mainly human staphylococci (32.5%,393/1 209), Staphylococcus epidermidis (27.8%, 336/1 209), Staphylococcus aureus (14.9%,180/1 209) and Enterococcus faecalis (10.6%, 128/1 209). Among them, the detection rate of methicillin-resistant Staphylococcus aureus (MRSA) (42.8%, 77/180) was lower than that of methicillin-resistant coagulase-negative staphylococcus (MRCNS) (71.5%, 608/850); and among enterococci, the detection rate of Enterococcus faecalis (71.5%, 128/179) was much higher than that of Enterococcus faecalis (28.5%, 51/179). For drug resistance, the resistance rate to five commonly used antimicrobial drugs, ciprofloxacin, levofloxacin, moxifloxacin, clindamycin and tetracycline, was higher in Staphylococcus hominis than in Staphylococcus epidermidis ( χ 2 =7.152-64.080, P <0.05); however, for the aminoglycoside antimicrobial drug gentamicin, the rate of resistance in Staphylococcus humanus was lower than in Staphylococcus epidermidis, and the difference was statistically significant ( χ 2 =11.895, P< 0.05); no strains resistant to linezolid and vancomycin were found in both. Comparison of the resistance rates to seven antimicrobial drugs, gentamicin, rifampicin, ciprofloxacin, levofloxacin, moxifloxacin, clindamycin and tetracycline, was significantly higher in MRSA than in MSSA ( χ 2 =6.169-56.941, P <0.05); however, the resistance rate to cotrimoxazole, MRSA (15.6%, 12/77) was significantly lower than that of MSSA (35.3%, 36/102), and the difference was statistically significant ( χ 2 =5.155, P< 0.05); MRSA and MSSA resistant to linezolid and vancomycin were not found. The resistance rate of Enterococcus faecalis to penicillin G and ampicillin was much higher than that of Enterococcus faecalis, and the difference was statistically significant ( χ 2 =22.965, P <0.05), and vancomycin-resistant enterococci (VRE) were not found. In conclusion, for staphylococci, except for individual antibiotics, S.hominis and MRSA were more resistant to most antimicrobial drugs than S. epidermidis and MSSA, showing a multidrug-resistant pattern. For enterococci, except for penicillin G and ampicillin resistance rate, Enterococcus faecalis is much higher than Enterococcus faecalis, the rest of the antimicrobial drugs did not see a significant difference, in addition to vancomycin-resistant enterococci were not detected. Clinicians should pay great attention to the monitoring data of multidrug-resistant G + cocci isolated from blood cultures to provide a basis for empirical and rational use of drugs in the clinic, to effectively prevent and reduce the incidence of bloodstream infections caused by G + cocci.

The detection of antibiotic residues is of great significance in monitoring their overuse in healthcare, livestock and poultry farming, and agricultural production. Herein, EuCl 3 and 4,4'-dicarboxyl-diphenoxyethene (H 2 DPOE) ionothermally reacted in 1-methyl-3-butylimidazolium chloride to give a europium metal-organic framework (Eu-DPOE). Eu-DPOE shows different fluorescence quenching rates for sensing eight antibiotics under different excitation wavelengths. Eu-DPOE displays a fast response, high selectivity, and sensitivity in antibiotic detection by fluorescence quenching. Eu-DPOE can sensitively detect TCs (tetracyclines), NOR (norfloxacin), NFT (furazolidone), ODZ (ornidazole), SDZ (sulfadiazine), and CHL (chloramphenicol) with limits of detection below 0.5 μmol/L. It provides a convenient and rapid tool for sensing antibiotics in aqueous solution. The detection mechanism is a competition absorption between DPOE 2- and antibiotics with the supports from powder X-ray diffraction (PXRD), UV-vis spectra, and fluorescence lifetime. With a composite membrane of poly(vinylidene fluoride) (PVDF) matrix loading Eu-DPOE (Eu-DPOE@PVDF), Eu-DPOE@PVDF exhibits a visual fluorescence response to NOR under a 254 nm UV lamp and NFT and CTC under 365 nm. Eu-DPOE@PVDF is applied in the quantitative detection of CTC, NOR, and NFT in lake water with recovery rates ranging from 88.37 to 113.8%. Totally, fluorescence-quenched Eu-DPOE@PVDF exhibits a fast response, high selectivity, and sensitivity in sensing CTC, NOR, and NFT.

In order to discuss the response of soil nutrient content, stoichiometric ratio, and dynamic nutrient balance to the addition of multiple restrictive nutrients, the correlation between available nutrients and total nutrients in soil, as well as the indication of soil total and available stoichiometric characteristics, were studied in a desert grassland subjected to 4 years of nutrient addition treatments. The Ningxia desert grassland was used as the research object to carry out nitrogen (N) and phosphorus (P) addition experiments. The experiment included four treatments:control (CK), N addition[10 g·(m 2 ·a) -1 ], P addition[10 g·(m 2 ·a) -1 ], and NP co-addition (10 g·(m 2 ·a) -1 N+10 g·(m 2 ·a) -1 P). The results showed that:① in the fourth year of nutrient addition, soil total nitrogen (TN) content was significantly increased. The N:P ratio was significantly increased by N addition, and soil organic carbon (SOC) content was significantly increased by P addition and NP co-addition. In the third and fourth years of nutrient addition, the soil available N:P ratio (AN:AP) was significantly increased by N addition; N addition and NP co-addition significantly increased the content of ammonium nitrogen (NH 4 + -N) and nitrate nitrogen (NO 3 - -N) but significantly reduced the soil available C:N ratio. P addition and NP co-addition significantly increased total phosphorus (TP) and soil available phosphorus (AP), whereas it significantly reduced the soil total and available C:P and N:P ratios. ② The interaction between N addition and P addition had a combined effect on NH 4 + -N, AP, available C:N, and AN:AP ratio of desert grassland. ③ The soil C:N ratio was relatively stable in desert grassland, soil N:P ratio was mainly limited by soil TP content, and the soil available C:P and AN:AP ratios were mainly limited by soil AP content. ④ There were cumulative effects of N and P additions on soil N, SOC, and inorganic nitrogen. N limitation in desert grassland was alleviated by N addition, whereas it was aggravated by P addition and NP co-addition. The variation coefficients of soil available stoichiometric characteristics were higher than that of soil total stoichiometric characteristics. Soil available stoichiometry was more sensitive to N and P addition than soil total stoichiometry in desert grassland, which could better reflect the effects of N and P addition on soil ecological stoichiometry and as a rapid indicator of soil nutrient status in desert grassland.

Objective: The present study aimed at observing the profile of metabolites in sensitized acupoints induced by myocardial ischemia (MI) and the effect of acupuncture intervention on the changes of the metabolites so as to explore the material basis of acupoint sensitization., Methods: A total of 20 New Zealand rabbits were randomly and equally divided into a control group and a model group. The MI model was established by occlusion of the anterior descending branch of the left coronary artery with a controllable air balloon inflation method for 5 min/time, twice a day (4-hours' interval) for continuous 5 days (the first stage of MI). After one day's rest, another 5 days' occlusion was conducted again (the second stage of MI) in the same way. The rabbits of the control group were treated with the same procedures but without occlusion. Subcutaneous microdialysis fluid samples were collected from "Neiguan" (PC 6), "Shenmen" (HT 7), "Xinshu" (BL 15), and "Taixi" (KI 3) regions on day 8(after recovery from operation), 14 (the first stage of MI), and 20 (the second stage of MI), as well as collected from PC 6 region during and post-acupuncture stimulation of PC 6, respectively. Manual acupuncture stimulation was applied to the right PC 6 for 30 min. Partial least squares -linear discriminant analysis (PLS-DA) was used to identify different metabolism patterns of the microdialysis fluid sample between groups and at different time-points in the same one group, and the distinct metabolites as the potential markers between groups were weighted via the values of variable importance in the projection (VIP) in combination with t-test analysis. An area under the curve (AUC) >1.0 indicated a test exhibiting good discrimination between groups., Results: Six metabolites identified to be significantly different between the control and model groups were L-glutamic acid, phenylalanine and 3-hydroxyisobutyric acid (which were significantly increased relevant to the control group), and L-histidine, octadecanedioic acid and 9-keto palmitic acid (significantly decreased relevant to the control group) in the microdialysate of PC 6, HT 7 and BL 15 regions. In the microdialysate of PC 6, 4 metabolites including L-glutamic acid, octadecanedioic acid and 8-isohydroxy PGF 2 α (significantly increased), as well as L-histidine (markedly decreased) were identified to be considerably different between the model and control groups. After acupuncture for 30 min, the AUC level of L-glutamic acid was further significantly increased ( P <0.05), that of L-histidine obviously decreased, and those of octadecanedioic acid and 8-isohydroxy PGF 2 α turned back nearly to the level of pre-MI., Conclusion: L-glutamic acid, phenylalanine, 3-hydroxyisobutyric acid, L-histidine, octadecanedioic acid and 9-keto palmitic acid from PC 6, HT 7 and BL 15 regions may be used as the material biomarker for MI-induced sensitization of these acupoints. Manual acupuncture intervention of PC 6 induces a significant change of L-histidine and L-glutamic acid in the local subcutaneous tissues.

Objective: To develop an animal model suitable for the study of acupoint sensitization in myocardial ischemia(MI) animals by observing changes of the mechanical withdrawal threshold (pain threshold, PT)., Methods: Twenty New Zea-land rabbits were randomly divided into control and model groups ( n =10 in each group). The controllable MI model was set up by installing a balloon occluder at the left anterior descending branch of the left coronary artery. Air inflation of the balloon was given for 5 min/time, twice a day (4-hours' interval) for continuous 5 days (the first stage of MI), with one day's rest, then, another 5 days' air inflation was conducted again (2 nd stage of MI). Electrocardiogram (ECG) of the standard limb lead Ⅱ was recorded for assessing MI, and myocardial 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to verify the degree of ischemic myocardium. The PT of the skin areas of "Neiguan" (PC 6), "Shenmen" (HT 7),"Taixi"(KI 3),hind paw(HP)was detected under conscious conditions,before MI, on day 8(after recovery from MI), day 14 (the first stage of MI), and day 20 (the second stage of MI), respectively., Results: The controllable MI model was successful due to a marked elevation of ECG ST Ⅱ after inflation of the implanted balloon and a distinct recovery after balloon deflation ( P <0.05). The myocardial TTC staining showed that the area of the myocardial necrosis was about 10%. The PT values were significantly decreased in PC 6 area at the first stage of MI and in both PC 6 and HT 7 regions at the 2 nd stage of MI ( P <0.01), suggesting a close relationship between the acupoints of the Pericardium and Heart meridians and the heart in terms of the basic theory of Chinese medicine., Conclusions: MI may induce a reduction of PT of some related acupoints in MI rabbits, and the controllable MI model of the present study is helpful to the study of acupoint sensitization phenomenon after occurrence of visceral diseases.