Genome-wide analysis of in vivo-evolved Candida auris reveals multidrug-resistance mechanisms.

Candida auris, an emerging and multidrug-resistant fungal pathogen, has led to numerous outbreaks in China. While the resistance mechanisms against azole and amphotericin B have been studied, the development of drug resistance in this pathogen remains poorly understood, particularly in in vivo-generated drug-resistant strains. This study employed pathogen whole-genome sequencing to investigate the epidemiology and drug-resistance mutations of C. auris using 16 strains isolated from two patients. Identification was conducted through Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and antimicrobial susceptibilities were assessed using broth microdilution and Sensititre YeastOne YO10. Whole-genome sequencing revealed that all isolates belonged to the South Asian lineage, displaying genetic heterogeneity. Despite low genetic variability among patient isolates, notable mutations were identified, including Y132F in ERG11 and A585S in TAC1b, likely linked to increased fluconazole resistance. Strains from patient B also carried F214L in TAC1b, resulting in a consistent voriconazole minimum inhibitory concentration of 4 µg/mL across all isolates. Furthermore, a novel frameshift mutation in the SNG1 gene was observed in amphotericin B-resistant isolates compared to susceptible ones. Our findings suggest the potential transmission of C. auris and emphasize the need to explore variations related to antifungal resistance. This involves analyzing genomic mutations and karyotypes, especially in vivo, to compare sensitive and resistant strains. Further monitoring and validation efforts are crucial for a comprehensive understanding of the mechanisms of drug resistance in C. auris.

High-throughput screening and quantification of pesticides in Lilii Bulbus using ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry.

Lilii Bulbus is a notable flower in Chinese cuisine, and has also been used as a Chinese herbal medicine for over 2000 years. This work presents an analytical method for rapidly screening multiple pesticide residues in Lilii Bulbus using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). For sample pre-treatment, the QuEChERS method is employed, and targeted MS/MS is adopted for data acquisition. Moreover, a database containing 515 pesticides with accurate mass database and a high-resolution fragment ion spectrum library is established in this work. In addition, the qualitative and quantitative results of the screening method are validated. The results show that within the linear concentration range of 2 to 200 µg L-1, for each pesticide, 89.3% of the pesticides exhibit linear correlation coefficients R2 equal to or exceeding 0.990. The limit of quantification for all pesticides is below 50 µg kg-1. With a recovery of 70% to 120% and RSD ≤ 20% as the satisfactory standards, 387 (75.0%), 411 (79.7%) and 420 (81.4%) pesticides meet the standards at the three addition levels of 10 µg kg-1, 20 µg kg-1, and 100 µg kg-1, respectively. By utilizing the proposed method, pesticide residues in 100 samples are investigated, providing scientific data to ensure the safety of pesticide residues and demonstrating the general applicability of the method for routine monitoring of pesticide residues in Lilii Bulbus.

A liquid chromatography-time-of-flight/mass spectrometry method for analysis of pesticides and transfer behavior in Radix Codonopsis and Angelica sinensis decoctions.

The safety of traditional Chinese medicine (TCM) has garnered considerable interest worldwide. In this study, a high-throughput method for the determination of 255 pesticide residues in decoctions of Radix Codonopsis and Angelica sinensis was developed using liquid chromatography-time-of-flight/mass spectrometry. The methodological verification demonstrated the accuracy and reliability of this method. The frequently detected pesticides in Radix Codonopsis and Angelica sinensis were determined to build a correlation between pesticide properties and the transfer rate of pesticide residues in their decoctions. Water solubility (WS) with a higher correlation coefficient (R) made a significant contribution to the accuracy of the transfer rate prediction model. The regression equations for Radix Codonopsis and Angelica sinensis were T = 13.64 log WS + 10.56 with a correlation coefficient (R) of 0.8617 and T = 10.66 log WS + 25.48 with a correlation coefficient (R) of 0.8072, respectively. This study provides preliminary data on the potential risk of exposure to pesticide residues in Radix Codonopsis and Angelica sinensis decoctions. Furthermore, as a case study on root TCM, this approach may serve as a model for other TCMs.

Automated QuEChERS for the determination of 482 pesticide residues in Radix codonopsis by GC-Q-TOF/MS and LC-Q-TOF/MS.

A rapid procedure for the determination of 482 pesticide residues in Chinese Materia Medica by GC-Q-TOF/MS and LC-Q-TOF/MS (379 pesticides for LC, 327 pesticides for GC, and 226 pesticides for both) was developed. Radix codonopsis was chosen as the matrix for verification, and a comparative study on the QuEChERS sample preparation was carried out, between a fully automated workstation and manual operation, in terms of limits of quantitation, recovery rate and RSD at 3 spiked levels of 10 µg kg-1, 20 µg kg-1 and 100 µg kg-1. In the linear range of each pesticide in a concentration range of 5-100 µg L-1, the linear correlation coefficients R2 of 85% of the pesticides for GC and 88% for LC were equal to or greater than 0.990. Taking recovery 70-120% and RSD ≤ 20% as the satisfactory standard, the automated workstation performed better at 10 µg kg-1 and 20 µg kg-1 than manual operation, and the numbers of satisfactory pesticides of GC & LC were 401 and 418 for the automated approach, and 378 and 400 for manual, while the two approaches were almost even at 100 µg kg-1, 421 vs. 424. Besides, the automated workstation presented lower RSD (more pesticides ≤10%) and better recovery quality (more pesticides within 90-110%). Following the method verification, 50 Radix codonopsis samples purchased from local markets were prepared with the automated workstation and analyzed by GC and LC-Q-TOF/MS. 18 pesticides were detected in 38 samples, one of which was a highly toxic pesticide. The automated QuEChERS workstation can handle 40 samples in one cycle within 6 hours, and realize whole-process automation covering from samples after "weighing" to "injection into vials". The batch-to-batch, day-to-day, and lab-to-lab consistency and 24 × 7 workability of the automated solution have demonstrated a promising and ideal replacement for manual operation in sample preparation.

Proton radiation effects on carrier transport in diamond radiation detectors.

Diamond, a highly radiation-resistant material, is considered a nearly ideal material for radiation detection, particularly in high-energy physics. In this study, radiation damage from high-energy proton beams was induced in diamond crystals to determine exposure lifetime in detectors made from this material; the effects were investigated using non-destructive x-ray techniques and through the FLUKA simulation package. Two diamond detectors were irradiated by an 800 MeV proton beam at different fluence rates, and the real-time current response was recorded to observe degradation in the signal over time. It was determined that the proton fluence rate had a significant effect on the device degradation. The detector performance from the irradiated detectors was characterized using x-ray beam-induced current measurements, and the mechanism of proton radiation damage to diamond sensors, especially the radiation effects on carrier transport, was studied. The vacancies generated from proton irradiation were considered the major source of detector degradation by trapping holes and inducing an internal electric field. Simulation results from the FLUKA package revealed an uneven distribution of the radiation-induced vacancies along the beam path, and the corresponding detector signals calculated from the simulation results displayed a good match to the experimental results.

[Molecular characterization of vancomycin-resistant Enterococci].

OBJECTIVE: To investigate the homology and resistant mechanism of vancomycin-resistant Enterococci (VRE) isolates. METHODS: A total of 9 VRE isolates were collected from 2006 to 2007 at PUMC hospital. The susceptibility of these isolates to 10 different antibiotics including vancomycin was tested by E-test. These strains were processed by brain heart infusion agar screening in the presence of vancomycin (6 microg/ml), and were analyzed for genotypic characteristics using the multiplex PCR. The homology of the isolates was determined by pulsed-field gel electrophoresis (PFGE). RESULTS: All the 9 VRE isolates were identified as Enterococci faecium. The visual analysis of PFGE patterns revealed 6 different PFGE types. The vanA gene was confirmed by PCR and sequencing in 9 VRE isolates, which were consistent between phenotype and genotype for glycopeptides resistance. CONCLUSIONS: Only vanA genotype was detected in PUMC hospital. Clonal dissemination, horizontal gene transfer, and the selective pressure of antimicrobial agents may contribute to the increase of VRE.

[Sutureless lamellar keratoplasty by microkeratome combined with fibrin tissue adhesive in rabbits].

OBJECTIVE: To evaluate the feasibility and safety of sutureless lamellar keratoplasty by microkeratome combined with fibrin tissue adhesive. METHODS: Twenty-four New Zealand white rabbits were divided into two groups, the donor grafts and recipient beds were made by the microkeratome, the grafts were glued over the stoma bed using the commercial product Tisseel in one group; and grafts without tissue adhesive were used as the control group. Corneal refractive power was measured by automated keratometer preoperatively and in 3 days, 2 weeks, 1 and 3 months postoperatively. Rejection and cornea transparency were observed. Confocal microscopy was used to observe corneal wound healing response and to measure the keratocyte and endothelium densities in vivo. Corneal wound healing was also evaluated using light and fluorescence microscopy. RESULTS: Ninety-two percent (11/12 eyes) of the glued grafts were retained in the Tisseel group, whereas all grafts were lost in the control group. All survived grafts were clear 1 month after surgery. However, in the control group, severe haze in the grafts occurred 2 weeks postoperatively. Confocal microscopy showed that there was a significant decrease of the keratocyte density surrounding the lenticule-host interface, and no changes occurred in the posterior keratocyte and endothelium. Histopathologic observations demonstrated the presence of a line of amorphous eosinophilic substance in the lenticule-host interface at 3 days after surgery, but the line disappeared after 1 month. Fluorescence microscopy showed no detectable regenerated stromal tissue. CONCLUSIONS: This initial study demonstrates sutureless optical lamellar keratoplasty performed by microkeratome combined with fibrin tissue adhesive is a simple and safe technique. Stromal wound healing response to this surgery is minimal. Fibrin tissue adhesive has no influence on the cornea optical property.

[The epithelial-flap abnormality of laser epithelial keratomileusis].

OBJECTIVE: To investigate the technique of epithelial-flap performance and reposition and the factors related to the complication to improve the quality of laser epithelial keratomileusis (LASEK). METHODS: Fourteen eyes (9 cases) of epithelial-flap abnormality occurring in and after the operation in 309 eyes were observed and analyzed. The factors related to the abnormal flap were listed and discussed. RESULTS: The abnormal epithelial flaps of LASEK during and after the operation were free epithelial-flap, dissolution, fragments, fold, slip, and the late epithelial-flap abnormalities including epithelial defect and sub-epithelial foreign body 48 - 72 hours postoperatively. The related factors of complication included the shallow cut of micro-trephine, improper (too small) cut ring, improper concentration of alcohol, the invasion of alcohol solution, dry center of epithelial-flap, corneal epithelial injury by irrigation, and too early removal of contact lens. CONCLUSION: The epithelial-flap of LASEK is frailer than that of LASIK. The key point in the performance of a fine epithelial-flap is to manage every procedure carefully.