Evaluation of disease severity and prediction of severe cases in children hospitalized with influenza A (H1N1) infection during the post-COVID-19 era: a multicenter retrospective study.

BACKGROUND: The rebound of influenza A (H1N1) infection in post-COVID-19 era recently attracted enormous attention due the rapidly increased number of pediatric hospitalizations and the changed characteristics compared to classical H1N1 infection in pre-COVID-19 era. This study aimed to evaluate the clinical characteristics and severity of children hospitalized with H1N1 infection during post-COVID-19 period, and to construct a novel prediction model for severe H1N1 infection. METHODS: A total of 757 pediatric H1N1 inpatients from nine tertiary public hospitals in Yunnan and Shanghai, China, were retrospectively included, of which 431 patients diagnosed between February 2023 and July 2023 were divided into post-COVID-19 group, while the remaining 326 patients diagnosed between November 2018 and April 2019 were divided into pre-COVID-19 group. A 1:1 propensity-score matching (PSM) was adopted to balance demographic differences between pre- and post-COVID-19 groups, and then compared the severity across these two groups based on clinical and laboratory indicators. Additionally, a subgroup analysis in the original post-COVID-19 group (without PSM) was performed to investigate the independent risk factors for severe H1N1 infection in post-COIVD-19 era. Specifically, Least Absolute Shrinkage and Selection Operator (LASSO) regression was applied to select candidate predictors, and logistic regression was used to further identify independent risk factors, thus establishing a prediction model. Receiver operating characteristic (ROC) curve and calibration curve were utilized to assess discriminative capability and accuracy of the model, while decision curve analysis (DCA) was used to determine the clinical usefulness of the model. RESULTS: After PSM, the post-COVID-19 group showed longer fever duration, higher fever peak, more frequent cough and seizures, as well as higher levels of C-reactive protein (CRP), interleukin 6 (IL-6), IL-10, creatine kinase-MB (CK-MB) and fibrinogen, higher mechanical ventilation rate, longer length of hospital stay (LOS), as well as higher proportion of severe H1N1 infection (all P < 0.05), compared to the pre-COVID-19 group. Moreover, age, BMI, fever duration, leucocyte count, lymphocyte proportion, proportion of CD3+ T cells, tumor necrosis factor α (TNF-α), and IL-10 were confirmed to be independently associated with severe H1N1 infection in post-COVID-19 era. A prediction model integrating these above eight variables was established, and this model had good discrimination, accuracy, and clinical practicability. CONCLUSIONS: Pediatric H1N1 infection during post-COVID-19 era showed a higher overall disease severity than the classical H1N1 infection in pre-COVID-19 period. Meanwhile, cough and seizures were more prominent in children with H1N1 infection during post-COVID-19 era. Clinicians should be aware of these changes in such patients in clinical work. Furthermore, a simple and practical prediction model was constructed and internally validated here, which showed a good performance for predicting severe H1N1 infection in post-COVID-19 era.

Determination of Cations and Anions in Desulfurization Waste Water of Coal-Fired Power Plant by Ion Chromatography.

The reliable and accurate determination of corrosive anions at sub- to low-µg/L levels is a challenging analytical problem. In this manuscript, a simultaneous determination method of cations and anions in power plant water samples was established by large volume injection ion chromatography. The analytical parameters including separation column, the suppressor current and the elute concentration were optimized. Results showed good separation under the optimum conditions, and the calibration curves of all analytes were linear with good coefficient of determination (r2) >0.997, and the mean recoveries for all analytes ranged from 75.62 to 118.58% with RSD of 0.07-4.83%. The established method was successfully applied to determine the cations and anions in realwaste water samples from coal-fired power, and was verified by inductively coupled plasma optical emission spectrometry and electrometric titration. The relative deviation between methods was all below 6.72%, which indicated good accuracy of the established ion chromatography method. The results could also provide reference for the precise and rapid detection of cations and anions in environmental water samples.

[Separation and identification of Fischer-Tropsch wax by high temperature gas chromatography-mass spectrometry].

Fischer-Tropsch (FT) wax is an important material produced from FT synthesis reactions. In this study, an improved separation and identification method for FT wax by high temperature gas chromatography (HTGC) coupled with cold-on-column (without pretreatment) was developed. In our improved separation procedure, the carrier gas was changed to helium and a long chromatographic column was adapted for use at high temperature. The n-alkanes in FT wax were well separated from other unknown components and the heavy components with carbon numbers higher than C90 could be eluted. Unknown components of the FT wax fraction were confirmed as alkanes, alkenes and oxygenated compounds by using HTGC-mass spectrometry. These results improve our understanding of the FT synthesis process and increase our detailed knowledge of FT products.

Determination of fungicides in fruit juice by ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic solvent droplets followed by high performance liquid chromatography.

Ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) based on solidification of the floating organic solvent droplets (SFO) combined with HPLC was used for determination of five fungicides in fruit juice samples. 1-Dodecanol, which has a low density and low toxicity, was used as the extraction solvent in UA-DLLME. The solidification of floating organic droplets facilitates the transfer of analytes from the aqueous phase to the organic phase. This method was easy, quick, inexpensive, precise, and linear over a wide range. Under the optimized conditions, the enrichment factors for a 5 mL fruit juice sample were 25 to 56, and the LODs for the five fungicides ranged from 5 to 50 microg/L. The average recoveries ranged from 71.8 to 118.2% with RSDs of 0.9 to 13.9%. Application of the DLLME-SFO technique allows successful separation and preconcentration of the fungicides at a low concentration level in fruit juice samples.

Residue and risk assessment of pyridaben in cabbage.

The dissipation and residue of pyridaben in cabbage under field conditions were investigated. A sensitive, simple, and fast method for determining pyridaben in cabbage was established by high-performance liquid chromatography tandem mass spectrometry. The average recoveries were in the range of 90.29-95.00% with relative standard deviations ranging from 1.72% to 6.39%. The field results showed that pyridaben dissipated rapidly in cabbage and had a half-life of 2.8-3.5 d. During harvest, the terminal residues of pyridaben were 0.01-0.80 mg/kg. Given that no maximum residue limit (MRL) has been set for pyridaben in cabbage, risk assessment was evaluated by using the risk quotient (RQ). Results indicated that the RQ value was significantly lower than RQ = 1. Thus, the effect of pyridaben in cabbage at the recommended dosage was negligible to humans. This study could provide guidance for the safe and reasonable use of pyridaben as a broad-spectrum acaricide and serve as a reference for the establishment of an MRL in China.

Pyrimethanil residue and dissipation in tomatoes and soil under field conditions.

A residue analytical method to detect pyrimethanil in tomatoes and soil was developed by using high-performance liquid chromatography with a diode array detector. The dissipation and residue level of pyrimethanil in tomatoes and soil were also investigated. Results showed that the average recoveries are in the range of 87.2 to 90.0 % with a relative standard difference of 2.22 to 7.61 % in tomatoes and soil. In Guangdong, Shandong, and Yunnan, the half-lives of pyrimethanil in tomatoes were 1.8, 3.6, and 4.2 days and those in soil were 4.0, 3.3, and 3.9 days, respectively. The dissipation rate of pyrimethanil in tomatoes and soil was affected by temperature, precipitation, and soil type. The terminal residue results showed that when pesticide pyrimethanil was used under the experiment design, all the results were far below the available maximum residue limits. Low residues in tomatoes and soil suggest that this pesticide is safe to use under the recommended dosage.

Dissipation, residues, and risk assessment of spirodiclofen in citrus.

The dissipation, residues, and distribution of spirodiclofen, a new type of insecticide and acaricide that belongs to the class of ketoenols or tetronic acids, in citrus were investigated in this study. Risk assessment of sprodiclofen was also conducted based on those data. The open-field experiments were conducted in Guangdong, Fujian, and Guangxi of China. Results showed that the half-lives in citrus ranged from 6.5 to 13.6 days at three sites. The terminal residues of spirodiclofen were all below the FAO/WHO maximum residue limit of 0.5 mg/kg in citrus, when they were determined 14 days after final application. Distribution of spirodiclofen in peel and flesh was analyzed, and residues were found to be concentrated on peel. Risk assessment was performed by calculation of risk quotient, which showed that the use of spirodiclofen is comparably safe for humans.

Dissipation and residue of bifenthrin in wheat under field conditions.

Field trials were carried out to investigate the dissipation and residue levels of bifenthrin in wheat. After extraction with acetonitrile, the samples were cleaned up by dispersive solid-phase extraction and detected by gas chromatography-mass spectrometry. The half-lives of bifenthrin in wheat seedlings ranged from 2.4 to 10.5 days. At harvest time, the terminal residues of bifenthrin were below the maximum residue limit (0.5 mg/kg) set by Codex Alimentarius Committee or European Union in wheat grain, which suggested that the use of this pesticide was safe for humans. However, the relatively high residue levels of bifenthrin in wheat straw should be paid attention to.

Behavior of mixed formulation of metalaxyl and dimethomorph in grape and soil under field conditions.

This study investigates the dissipation and residue of a metalaxyl and dimethomorph mixed formulation in grape and soil. A high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analytical method was developed to determine the residue of metalaxyl and dimethomorph in grape and soil. The results showed that the average recoveries are in the range of 86.84 percent to 97.30 percent. The dissipation rate of metalaxyl in grape (with half life of 4.9 days) was faster than in soil (with half life of 8.7 days). The dissipation rates of E- and Z-isomers of dimethomorph in grape were almost the same (with half lives of 9.0 and 9.8 days, respectively). However, the dissipation rate of the E-isomer in soil was much faster than that of the Z-isomer (with half lives of 10.3 and 31.5 days, respectively). Moreover, the terminal residue of metalaxyl and dimethomorph were significantly below the available maximum residue limits (MRL). However, a difference was observed between the concentration of the Z- and E-isomers either in grape or soil. The ratio of E-isomer to Z-isomer in grape was higher than in soil, which may due to the different water solubilities and polarities of the two isomers.

Dissipation of pyraclostrobin and its metabolite BF-500-3 in maize under field conditions.

The dissipation and residue of pyraclostrobin and its metabolite BF-500-3 in maize under field conditions were investigated. A sensitive, simple and fast method for simultaneous determination of pyraclostrobin and BF-500-3 in maize matrix was established by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The average recoveries of pyraclostrobin and BF-500-3 were found in the range of 83.6-104.9% with relative standard deviations (RSDs) of 2.3-10.0%. The results showed that pyraclostrobin dissipated quickly in maize plant with half-lives of 1.6-1.7 days. Its metabolite BF-500-3 showed a tendency of rapid increasing initially and decreasing afterwards. At harvest time, the terminal residues of pyraclostrobin were below the maximum residue limit (MRL) set by USA and Canada in maize grain when measured 7 days after the final application, which suggested that the use of this fungicide was safe for humans. The results could provide guidance to safe and reasonable use of pyraclostrobin in agriculture.

Dissipation and residue of 2,4-D isooctyl ester in wheat and soil.

A simple analytical method was developed to determine the 2,4-D isooctyl ester residue in wheat and soil by gas chromatography coupled with electron capture detector. Using the method, the dissipation and residue of 2,4-D isooctyl ester in wheat field was investigated. The average recoveries of 2,4-D isooctyl ester ranged from 80.1% to 110.0% with relative standard deviations of 2.4% to 16.1%. The pesticide showed a rapid dissipation rate either in wheat seedling or soil, with the half-lives of 1.0 to 3.0 days. The terminal residue results in wheat grain were much lower than the codex MRL (2.0 mg/kg). It could be considered safe to food and environment when using this herbicide for controlling weeds in wheat field.

Dissipation and residue of cyprodinil in strawberry and soil.

The dissipation of cyprodinil under field and greenhouse condition in China was investigated. The pesticide cyprodinil dissipation differed under different cultivate conditions, the half lives were 14.5 and 12.5 days in strawberry and soil, respectively, under the field condition, 5.5 and 6.5 days, respectively, under greenhouse. The results showed that the dissipation rate under greenhouse condition was much faster than under field condition either in strawberry or soil. The terminal residues in strawberries were below the EU maximum residue level (5 mg/kg) after 7 days of application. This study will give a suggestion for the reasonable use of cyprodinil under different cultivate conditions and can also provide reference to set MRL value in strawberry in China.

Analysis of cyprodinil in leek and pepper and its decline under field conditions.

A HPLC-UV method for determination of cyprodinil in leek, pepper, and soil was developed and the decline of cyprodinil under field conditions in China was investigated. The samples were extracted with acetonitrile. For leek and pepper samples, further clean-up with a florisil SPE column was necessary. Average recoveries of cyprodinil were found in the range of 82.92-107.43% with relative standard deviations of 2.48-14.55%. The pesticide cyprodinil showed a relatively fast decline rate. The half lives were from 2 to 4 days in leek and pepper, from 2-5 days in soil except in Beijing (14.7 days). So the decline of cyprodinil in leek and pepper was almost same in different experiment plots. However, the decline in soil was much complicated, and affected by the precipitation and other climate condition. The results could provide guidance to safe and reasonable use of this pesticide in agriculture.

Determination of five polar herbicides in water samples by ionic liquid dispersive liquid-phase microextraction.

A simple, rapid and efficient ionic liquid based on dispersive liquid-phase microextraction (IL-DLPME) method was developed for the determination of three triazine and two phenylurea herbicides in water samples. IL (1-hexyl-3-methylimidazolium hexafluorophosphate [C(6)MIM][PF(6)]) that dispersed completely into the water solution under controlled temperature was used as the extraction solvent. The analytes were easily concentrated into the ionic liquid phase. This technique combined the process of extraction and concentration of the analytes into one step and avoided use of the more common, toxic organic solvents. The factors affecting the extraction efficiency such as the IL volume, sample pH, extraction time, centrifugal time, dissoluble temperature and ionic strength were optimized. The extracts were analyzed by high-performance liquid chromatography (HPLC) coupled with diode array detector (DAD). Under the optimized conditions, recoveries (50.5-109.1%) were obtained for the target analytes in water samples. The calibration curves were linear and the correlation coefficient ranged from 0.9947 to 0.9973 in the concentration levels of 5-100 microg L(-1). The relative standard deviations (RSDs, n = 5) were 6.80-10.78%. The limit of detections (LODs) for the five polar herbicides were between 0.46 microg L(-1) and 0.89 microg L(-1).

Famoxadone residue and dissipation in watermelon and soil.

The residue levels and dissipation rate of famoxadone in watermelon and soil were determined by HPLC-UVD. The LODs for famoxadone in watermelon, peel, flesh and soil were 0.002mg/kg (0.004mg/kg in leaf). The fortified recoveries ranged from 84.91% to 99.41% with relative standard deviations (RSDs) of 0.06-4.50%. The dissipation of famoxadone residue over the time in watermelon leaf and soil fitted to the equation C(T)=19.695e(-0.078T) and C(T)=1.369e(-0.129T). The half-lives (T(1/2)) of famoxadone in watermelon leaf and soil were 9.7 and 5.5 days, respectively. The final residue in watermelon was lower than 0.1mg/kg at harvest, which suggested the use of this fungicide to be safe to both human and environment. This work would be helpful in establishing the maximum residue limit (MRL) for famoxadone in watermelon in China, and provide guidance to the proper and safe use of this pesticide in agriculture.