Impact of soil-atmosphere HONO exchange on concentrations of HONO and O3 in the North China Plain

Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH) and plays a vital role in atmospheric photochemistry and nitrogen cycling. Soil emissions have been considered as a potential source of HONO. Lately, the HONO emission via soil-atmosphere exchange (ESA-exchange) from soil nitrite has been validated and quantified through chamber experiments, but has not been assessed in the real atmosphere. We coupled ESA-exchange and the other seven potential sources of HONO (i.e., traffic, indoor and soil bacterial emissions, heterogeneous reactions on ground and aerosol surfaces, nitrate photolysis, and acid displacement) into the Weather Research and Forecasting model with Chemistry (WRF-Chem), and found that diurnal variations of the soil emission flux at the Wangdu site were well simulated. During the non-fertilization period, ESA-exchange contributed ∼28 % and ∼35 % of nighttime and daytime HONO, respectively, and enhanced the net ozone (O3) production rate by ∼8 % across the North China Plain (NCP). During the preintensive/intensive fertilization period, the maximum ESA-Exchange contributions attained ∼70 %/83 % of simulated HONO in the afternoon across the NCP, definitely asserting its dominance in HONO production. ESA-Exchange enhanced the OH production rate via HONO photolysis by ∼3.5/7.0 times, and exhibited an increase rate of ∼13 %/20 % in the net O3 production rate across the NCP. The total enhanced O3 due to the eight potential HONO sources ranged from ∼2 to 20 ppb, and ESA-exchange produced O3 enhancements of ∼1 to 6 ppb over the three periods. Remarkably, the average contribution of ESA-exchange to the total O3 enhancements remained ∼30 %. This study suggests that ESA-exchange should be included in three-dimensional chemical transport models and more field measurements of soil HONO emission fluxes and soil nitrite levels are urgently required.

[Comparison of the clinical efficacy of all-inside arthroscopic lateral ligament augmentation procedure and Broström procedure for the treatment of chronic lateral rotational ankle instability]

Objective: To compare the clinical efficacy of patients with chronic lateral rotational ankle instability(CLRAI) after all-inside arthroscopic lateral ligament augmentation procedure and Broström procedure. Methods: This is a retrospective cohort study. The clinical and imaging data of 106 CLRAI patients were collected at the Xuzhou Central Hospital from January 2021 to December 2022. The patients included 55 males and 51 females with an age of (32.6±8.2) years (range: 16 to 50 years). All patients were treated under all-inside arthroscopic, and were divided into Broström-Gould surgery group (n=54) and Broström surgery group (n=52) according to different ligament repair methods. At 3, 6, and 12 months after surgery, ankle inversion stress tests and anterior drawer tests were used to examine the stability of the ankle joint and observe gait. The American Orthopedic Foot and Ankle Society ankle hindfoot scale (AOFAS-AH) and Karlsson ankle function score (KAFS) were used to assess ankle function; Tegner score was used to assess the patient's level of exercise; the foot and ankle outcome score(FAOS)(including score of symptoms,pain,function, daily living,function, sports and recreational activities (sport); quality of life (QOL)) was used to assess the patient's daily activity ability. Comparisons of data were made using independent sample t test, repeated measures analysis of variance, LSD multiple comparison method, χ2 test or Mann-Whitney U test. Results: All operations were successfully accomplished. All incisions healed by first intention, without evidence of postoperative complications of implant rejection, ligation reaction, and nerve and vessel injury. All patients were followed up at 3, 6, and 12 months after surgery. Ankle varus stress test and anterior drawer test were negative. No evidence supporting lateral ankle instability was obtained. All patients eventually regained normal gait. No patients underwent revision surgery. Repeated measurement analysis of variance showed that AOFAS-AH, Tegner, KAFS and FAOS scores in the Brostrom-Gould group and the Brostrom group were significantly higher than those before surgery (P<0.01). The change trends of Tegner score and FAOS-sport score were significantly different between the two groups (F=18.839, P<0.01; F=8.169, P=0.005). Multiple comparisons revealed that at 3-, 6-and 12-month follow-up, the Tegner scores ((3 months: 3.7±0.5 vs. 3.3±0.5, t=-3.980, P<0.01; 6 months: 4.4±0.6 vs. 3.8±0.7, t=-4.792,P<0.01;12 months: 5.8±0.9 vs. 5.1±1.0, t=-3.889,P<0.01)), sport scores ((3 months: 82.5±3.7 vs. 79.3±3.8, LSD-t=-4.316, P<0.01; 6 months: 88.5±4.9 vs. 85.7±3.8, LSD-t=-3.312,P=0.001;12 months: 90.1±4.3 vs. 88.2±5.1, LSD-t=-2.112,P=0.037)) in the Broström-Gould surgery group were higher than those in the Broström surgery group, with statistical significances. Conclusions: Both Broström-Gould and Broström procedures under all-inside arthroscopic can make ankle stability and improve ankle function in the treatment of CLRAI. However, the former maybe shorten the time to return to exercise and achieve higher motor function.

Rapid hydrolysis of NO2 at High Ionic Strengths of Deliquesced Aerosol Particles

Nitrogen dioxide (NO2) hydrolysis in deliquesced aerosol particles forms nitrous acid and nitrate and thus impacts air quality, climate, and the nitrogen cycle. Traditionally, it is considered to proceed far too slowly in the atmosphere. However, the significance of this process is highly uncertain because kinetic studies have only been made in dilute aqueous solutions but not under high ionic strength conditions of the aerosol particles. Here, we use laboratory experiments, air quality models, and field measurements to examine the effect of the ionic strength on the reaction kinetics of NO2 hydrolysis. We find that high ionic strengths (I) enhance the reaction rate constants (kI) by more than an order of magnitude compared to that at infinite dilution (kI=0), yielding log10(kI/kI=0) = 0.04I or rate enhancement factor = 100.04I. A state-of-the-art air quality model shows that the enhanced NO2 hydrolysis reduces the negative bias in the simulated concentrations of nitrous acid by 28% on average when compared to field observations over the North China Plain. Rapid NO2 hydrolysis also enhances the levels of nitrous acid in other polluted regions such as North India and further promotes atmospheric oxidation capacity. This study highlights the need to evaluate various reaction kinetics of atmospheric aerosols with high ionic strengths.

Heterogeneity of foam cell biogenesis across diseases

Foam cells are dysfunctional, lipid-laden macrophages associated with chronic inflammation of diverse origin. The long-standing paradigm that foam cells are cholesterol-laden derives from atherosclerosis research. We previously showed that, in tuberculosis, foam cells surprisingly accumulate triglycerides. Here, we utilized bacterial ( Mycobacterium tuberculosis ), fungal ( Cryptococcus neoformans ), and human papillary renal cell carcinoma (pRCC) models. We applied mass spectrometry-based imaging to assess the spatial distribution of storage lipids relative to foam-cell-rich areas in lesional tissues, and characterized lipid-laden macrophages generated under corresponding in vitro conditions. The in vivo data were consistent with in vitro findings showing that cryptococcus-infected macrophages accumulated triglycerides, while macrophages exposed to pRCC-conditioned-medium accumulated both triglycerides and cholesterol. Moreover, cryptococcus- and mycobacterium-infected macrophages accumulated triglycerides by different mechanisms. Collectively, our data indicate that the mechanisms of foam cell formation are disease-microenvironment-specific. Since foam cells are potential therapeutic targets, recognizing that their formation is disease-specific opens new biomedical research directions.

Preoperative CT histogram analysis to predict the expression of Ki-67 in solid pseudopapillary tumours of the pancreas

AIM

To explore the value of preoperative computed tomography (CT) histogram features in predicting the expression status of Ki-67 in patients with solid pseudopapillary pancreatic tumours (SPTP).

MATERIALS AND METHODS

This retrospective study analysed venous phase CT images of 39 patients with SPTP confirmed at surgery and histopathology and measured using the Ki-67 proliferation index from November 2015 to February 2022. According to the Ki-67 proliferation index, they were divided into high expression (Ki-67 ≥ 4%) and low expression (Ki-67 < 4%) groups. The histogram features of quantitative parameters were extracted using MaZda software, and the quantitative parameters of CT histograms were compared between groups. The receiver operating characteristic (ROC) curves of the patients were plotted according to the parameters, with statistically significant differences. The area under the curve (AUC), sensitivity, and specificity were calculated, and the effectiveness of the histogram parameters in predicting Ki-67 expression was analysed and evaluated.

RESULTS

In total, 27 SPTP patients were enrolled, including 11 with high expression of Ki-67 and 16 with low expression. Comparative analysis of the Ki-67 high- and low-expression groups revealed a statistically significant in necrosis and variance (p<0.05). ROC curve analysis showed that the AUC of necrosis and variance predicting Ki-67 expression status were 0.753 and 0.841, the sensitivities were 81.8% and 81.3%, and the specificities were 68.7% and 81.8%, respectively.

CONCLUSION

Preoperative CT histogram features help predict Ki-67 expression status in patients with SPTP.

Dynamic stabilization of ablative Rayleigh-Taylor instability in the presence of a temporally modulated laser pulse

This paper presents a numeric study of the dynamic stabilization of the ablative Rayleigh-Taylor instability (ARTI) in the presence of a temporally modulated laser pulse. The results show that the specially modulated laser produces a dynamically stabilized configuration near the ablation front. The physical features of the relevant laser-driven parameters in the unperturbed ablative flows have been analyzed to reveal the inherent stability mechanism underlying the dynamically stabilized configuration. A single-mode ARTI for the modulated laser pulse is first compared with that of the unmodulated laser pulse. The results show that the modulated laser stabilizes the surface perturbations and reduces the linear growth rate and enhancement of the cutoff wavelength. For multimode perturbations, the dynamic stabilization effect of the modulated laser pulse contributes to suppress the small-scale structure and reduce the width of the mixing layer. Moreover, the results show that the stabilization effect of the modulated laser pulse decreases as the maximum wavelength increases.

Value of spectral CT parameters in predicting the efficacy of neoadjuvant chemotherapy for gastric cancer

AIM

To investigate the value of pre-chemotherapy spectral computed tomography (CT) parameters in predicting neoadjuvant chemotherapy (NAC) response in gastric cancer (GC).

MATERIALS AND METHODS

Sixty patients with GC who received NAC and underwent spectral CT examination before chemotherapy were enrolled retrospectively and divided into a responsive group and a non-responsive group according to the postoperative pathological tumour regression grade. Clinical characteristics were collected. The iodine concentration (IC), water concentration (WC), and effective atomic number (Eff-Z) of the portal venous phases were measured before chemotherapy, and IC was normalised to that of the aorta to provide the normalised IC (NIC). An independent samples t-test, Mann-Whitney U-test, or chi-square test was used to analyse the differences between the two groups, and the receiver operating curve (ROC) was used to evaluate the predictive performance of different variables.

RESULTS

The neutrophil-to-lymphocyte ratio (NLR) was lower in the responsive group than in the non-responsive group (p<0.05). IC, NIC, and Eff-Z values were significantly higher in the responsive group than in the non-responsive group (p<0.01). The areas under the ROC curves for the NLR, IC, NIC, and Eff-Z were 0.694, 0.688, 0.799, and 0.690, respectively. The combination of NIC, Eff-Z, and NLR values showed good diagnostic performance in predicting response to NAC in GC, with an area under the ROC curve of 0.857, 76.92% sensitivity, 80% accuracy, and 85.71% specificity.

CONCLUSION

Spectral CT parameters may serve as non-invasive tools for predicting the response to NAC in patients with GC.

A study on wildfire impacts on greenhouse gas emissions and regional air quality in South of Orléans, France

Wildfire events are increasing globally which may be partly associated with climate change, resulting in significant adverse impacts on local, regional air quality and global climate. In September 2020, a small wildfire (burned area: 36.3 ha) event occurred in Souesmes (Loir-et-Cher, Sologne, France), and its plume spread out over 200 km on the following day as observed by the MODIS satellite. Based on measurements at a suburban site (∼ 50 km northwest of the fire location) in Orléans and backward trajectory analysis, young wildfire plumes were characterized. Significant increases in gaseous pollutants (CO, CH4, N2O, VOCs, etc.) and particles (including black carbon) were found within the wildfire plumes, leading to a reduced air quality. Emission factors, defined as EF (X) = ∆X/∆CO (where, X represents the target species), of various trace gases and black carbon within the young wildfire plumes were determined accordingly and compared with previous studies. Changes in the ambient ions (such as ammonium, sulfate, nitrate, chloride, and nitrite in the particle- and gas- phase) and aerosol properties (e.g., aerosol water content, aerosol pH) were also quantified and discussed. Moreover, we estimated the total carbon and climate-related species (e.g., CO2, CH4, N2O, and BC) emissions and compared them with fire emission inventories. Current biomass burning emission inventories have uncertainties in estimating small fire burned areas and emissions. For instance, we found that the Global Fire Assimilation System (GFAS) may underestimate emissions (e.g., CO) of this small wildfire while other inventories (GFED and FINN) showed significant overestimation. Considering that it is the first time to record wildfire plumes in this region, related atmospheric implications are presented and discussed.

Effects of oleanolic acid on acute liver injury triggered by lipopolysaccharide in broiler chickens

1. Infectious injury caused by lipopolysaccharide (LPS), a metabolite of gram-negative bacteria, can induce stress responses in animals and is a significant cause of morbidity and mortality in young birds. The purpose of this study was to investigate the effects of dietary supplementation with oleanolic acid (OA) on acute liver injury in broiler chickens challenged with LPS.2. In total, 120 broiler chickens were randomly divided into six groups and fed a basal diet containing 0, 50, 100, or 200 mg/kg OA or 100 mg/kg aureomycin. On d 15, broiler chickens were injected with either LPS or an equivalent volume of normal saline. Six hours after LPS injection, two broiler chicks were randomly selected for sampling in each replicate.3. The results indicated that dietary aureomycin was ineffective in alleviating LSP-associated liver injury, but protected broiler chickens from LPS-induced liver damage. This promoted a significant reduction in the levels of malondialdehyde and an increase in the levels of superoxide dismutase in liver. In addition, OA was found to cause significant reductions in the relative expression of IL-1β, IL-6, and TNF-α in broiler liver tissues, whereas the relative expression of IL-10 was significantly increased.4. In conclusion, oleanolic acid can alleviate oxidative stress and injury in the livers of broiler chickens induced by lipopolysaccharide. Consequently, oleanolic acid has potential utility as a novel anti-inflammatory and antioxidant feed additive.

[Effect of hollow compression screw internal fixation in treating McCrory-Bladin type Ⅱ lateral process fracture of the talus: open versus arthroscopy surgery]

In order to explore the clinical efficacy of hollow compression screw internal fixation in the treatment of lateral process fracture of the talus under open surgery versus arthroscopy procedure, a retrospective cohort study was conducted to analyze the clinical data of 33 patients with lateral process fracture of the talus admitted to Xuzhou Central Hospital from January 2019 to December 2021. There were 19 males (19 feet) and 14 females (14 feet), aged 18 to 50 years, with an average age of (32.2±9.3) years. According to the modified McCrory-Bladin classification, all patients were classified as type Ⅱ. Based on the different surgical methods, the patients were divided into the arthroscopy group (21 cases, treated with double-tunnel subtalar arthroscopy combined with hollow compression screw internal fixation) and the open group (12 cases, treated with open reduction and internal fixation with hollow compression screw). The operation time was observed and the surgical effects were evaluated using the visual analogue scale (VAS) of pain, the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, the Foot Function Index (FFI), and the Foot and Ankle Ability Measure (FAAM), which includes the FAAM-ADL (activity of daily living subscale) and the FAAM-S (sport subscale). All the patients of the two groups achieved stage Ⅰ wound healing. On the first day after the operation, the mean VAS score of the arthroscopy group was 2.4±0.7, which was significantly lower than that of the open group (3.4±1.6) (P=0.020). No significant difference was observed in terms of the follow-up time, operation time and AOFAS score between the two groups (all P>0.05). The FFI score of the arthroscopy group was significantly lower than that of the open group, and the FAAM-ADL and FAAM-S scores were significantly higher than those in the open group (all P<0.05). Two cases of dorsal foot numbness occurred in the open group after the operation, and the incidence of complications was not significantly different from that of the arthroscopy group (P=0.054). For McCrory-Bladin type Ⅱ lateral process fracture of the talus, the use of compression screw internal fixation could achieve reliable results, however, compared to open surgery, arthroscopy procedure obtained mini trauma and better functions.

Soil Emissions of Reactive Nitrogen Accelerate Summertime Surface Ozone Increases in the North China Plain

Summertime surface ozone in China has been increasing since 2013 despite the policy-driven reduction in fuel combustion emissions of nitrogen oxides (NOx). Here we examine the role of soil reactive nitrogen (Nr, including NOx and nitrous acid (HONO)) emissions in the 2013-2019 ozone increase over the North China Plain (NCP), using GEOS-Chem chemical transport model simulations. We update soil NOx emissions and add soil HONO emissions in GEOS-Chem based on observation-constrained parametrization schemes. The model estimates significant daily maximum 8 h average (MDA8) ozone enhancement from soil Nr emissions of 8.0 ppbv over the NCP and 5.5 ppbv over China in June-July 2019. We identify a strong competing effect between combustion and soil Nr sources on ozone production in the NCP region. We find that soil Nr emissions accelerate the 2013-2019 June-July ozone increase over the NCP by 3.0 ppbv. The increase in soil Nr ozone contribution, however, is not primarily driven by weather-induced increases in soil Nr emissions, but by the concurrent decreases in fuel combustion NOx emissions, which enhance ozone production efficiency from soil by pushing ozone production toward a more NOx-sensitive regime. Our results reveal an important indirect effect from fuel combustion NOx emission reduction on ozone trends by increasing ozone production from soil Nr emissions, highlighting the necessity to consider the interaction between anthropogenic and biogenic sources in ozone mitigation in the North China Plain.

New antifungal strategies: drug combination and co-delivery

The growing occurrence of invasive fungal infections and the mounting rates of drug resistance constitute a significant menace to human health. Antifungal drug combinations have garnered substantial interest for their potential to improve therapeutic efficacy, reduce drug doses, reverse, or ameliorate drug resistance. A thorough understanding of the molecular mechanisms underlying antifungal drug resistance and drug combination is key to developing new drug combinations. Here we discuss the mechanisms of antifungal drug resistance and elucidate how to discover potent drug combinations to surmount resistance. We also examine the challenges encountered in developing such combinations and discuss prospects, including advanced drug delivery strategies.

Aging of pollution air parcels acts as the dominant source for nocturnal HONO

Atmospheric HONO acts as a major source for OH radicals in polluted areas, playing an important role in formation of secondary pollutants. However, the atmospheric HONO sources remain unclear. Here we propose that the heterogeneous reaction of NO₂ on aerosols during aging processes acts as the dominant source for nocturnal HONO. Based on the nocturnal variations of HONO and related species in Tai'an city of China, we firstly developed new method to estimate the localized HONO dry deposition velocity (v(HONO)). The estimated v(HONO) of 0-0.077 m/s was in a good agreement with the reported ranges. Additionally, we set up a parametrization to reflect the HONO formation from the aged air parcels based on the variation of HONO/NO₂ ratio. The detailed variation of nocturnal HONO could be well reproduced by a complete budget calculation coupled with above parameterizations, with the difference between the observed and calculated HONO levels being <5 %. The results also revealed the average contribution of HONO formation from aged air parcels to atmospheric HONO could achieve to be ~63 % in average.

Direct Observation of HONO Emissions from Real-World Residential Natural Gas Heating in China

Atmospheric nitrous acid (HONO) is an important precursor of atmospheric hydroxyl radicals. Vehicle emissions and heterogeneous reactions have been identified as major sources of urban HONO. Here, we report on HONO emissions from residential natural gas (RNG) for water and space heating in urban areas based on in situ measurements. The observed HONO emission factors (EFs) of RNG heating vary between 6.03 and 608 mg·m^-3 NG, which are highly dependent on the thermal load. The highest HONO EFs are observed at a high thermal load via the thermal NO homogeneous reaction. The average HONO EFs of RNG water heating in winter are 1.8 times higher than that in summer due to the increased thermal load caused by the lower inlet water temperatures in winter. The power-based HONO EFs of the traditional RNG heaters are 1085 times and 1.7 times higher than those of gasoline and diesel vehicles that meet the latest emission standards, respectively. It is estimated that the HONO emissions from RNG heaters in a typical Chinese city are gradually close to emissions from on-road vehicles when temperatures decline. These findings highlight that RNG heating is a non-negligible source of urban HONO emissions in China. With the continuous acceleration of coal-to-gas projects and the continuous tightening of NOx emission standards for vehicle exhaust, HONO emissions from RNG heaters will become more prominent in urban areas. Hence, it is urgently needed to upgrade traditional RNG heaters with efficient emission reduction technologies such as frequency-converted blowers, secondary condensers, and low-NOx combustors.

Atmospheric ammonia in the rural North China Plain during wintertime: Variations, sources, and implications for HONO heterogeneous formation

Atmospheric ammonia (NH₃) plays an important role in secondary inorganic aerosol formation. Understanding the temporal variations, sources, and environmental influences of NH₃ is conducive to better formulate PM_2.5 pollution control strategies for policy-makers. Here, we performed a comprehensive field campaign with the measurements of NH₃ and related parameters at a rural site of the North China Plain (NCP) in winter of 2017. The results showed that residential coal combustion contributed dominantly to NH₃ during the entire observation period, resulting in the obviously high average concentration of NH₃ (31.2 ± 24.6 ppbv). The sensitivity tests of pH-NH_x during the three different pollution periods suggested that the rural site was always in the NH_x-rich atmosphere where high levels of NH_x increased the particle pH inefficiently. Nevertheless, the particle pH still elevated by 1.5-2.2 units at the excessive NH_x levels during the three pollution periods. In addition, the HONO/NO₂ ratios were found to correlate linearly with NH₃ concentrations, implying the acceleration effect of NH₃ on HONO production from NO₂ heterogeneous reactions. After considering the NH₃-enhanced uptake coefficient of NO₂ in the nocturnal HONO budget, the unknown source of HONO could be fully explained. Therefore, more attentions should be given for effective emission control of NH₃ to improve air quality throughout the NCP, especially in the rural areas.

Transport Pathways of Nitrate Formed from Nocturnal N2O5 Hydrolysis Aloft to the Ground Level in Winter North China Plain

Particulate nitrate (NO₃^-) has currently become the major component of fine particles in the North China Plain (NCP) during winter haze episodes. However, the contributions of formation pathways to ground NO₃^- in the NCP are not fully understood. Herein, the NO₃^- formation pathways were comprehensively investigated based on model simulations combined with two-month field measurements at a rural site in the winter NCP. The results indicated that the nocturnal chemistry of N₂O₅ hydrolysis aloft could contribute evidently to ground NO₃^- at the rural site during the pollution episodes with high aerosol water contents, achieving the contribution percentages of 25.2-30.4% of the total. In addition to the commonly proposed vertical mixing of breaking nocturnal boundary layer in the early morning, two additional transport pathways (frontal downdrafts and downslope mountain breezes) in the nighttime were found to make higher contributions to ground NO₃^-. Considering the dominant role (69.6-74.8%) of diurnal chemistry in NO₃^- formation, reduction of NO_x emissions in the daytime may be an effective control measure for reducing regional NO₃^- in the NCP.

Nearly five-year continuous atmospheric measurements of black carbon over a suburban area in central France

Atmospheric black carbon (BC) concentration over a nearly 5 year period (mid-2017-2021) was continuously monitored over a suburban area of Orléans city (France). Annual mean atmospheric BC concentration were 0.75 ± 0.65, 0.58 ± 0.44, 0.54 ± 0.64, 0.48 ± 0.46 and 0.50 ± 0.72 μg m^-3, respectively, for the year of 2017, 2018, 2019, 2020 and 2021. Seasonal pattern was also observed with maximum concentration (0.70 ± 0.18 μg m^-3) in winter and minimum concentration (0.38 ± 0.04 μg m^-3) in summer. We found a different diurnal pattern between cold (winter and fall) and warm (spring and summer) seasons. Further, fossil fuel burning contributed >90 % of atmospheric BC in the summer and biomass burning had a contribution equivalent to that of the fossil fuel in the winter. Significant week days effect on BC concentrations was observed, indicating the important role of local emissions such as car exhaust in BC level at this site. The behavior of atmospheric BC level with COVID-19 lockdown was also analyzed. We found that during the lockdown in warm season (first lockdown: 27 March-10 May 2020 and third lockdown 17 March-3 May 2021) BC concentration were lower than in cold season (second lockdown: 29 October-15 December 2020), which could be mainly related to the BC emission from biomass burning for heating. This study provides a long-term BC measurement database input for air quality and climate models. The analysis of especially weekend and lockdown effect showed implications on future policymaking toward improving local and regional air quality as well.

Development of a Heat-Killed fbp1 Mutant Strain as a Therapeutic Agent To Treat Invasive Cryptococcus Infection

In previous studies, we determined that the F-box protein Fbp1, a subunit of the SCF(Fbp1) E3 ligase in Cryptococcus neoformans, is essential for fungal pathogenesis. Heat-killed fbp1Δ cells (HK-fbp1) can confer vaccine-induced immunity against lethal challenge with clinically important invasive fungal pathogens, e.g., C. neoformans, C. gattii, and Aspergillus fumigatus. In this study, we found that either CD4+ T cells or CD8+ T cells were sufficient to confer protection against lethal challenge by C. neoformans in HK-fbp1-induced immunity. Given the potent effect of HK-fbp1 as a preventative vaccine, we further tested the potential efficacy of administering HK-fbp1 cells as a therapeutic agent for treating animals after infection. Remarkably, administration of HK-fbp1 provided robust host protection against preexisting C. neoformans infection. The mice infected with wild-type H99 cells and then treated with HK-fbp1 showed significant reduction of fungal burden in the infected lung and no dissemination of fungal cells to the brain and spleen. We find that early treatment is critical for the effective use of HK-fbp1 as a therapeutic agent. Immune analysis revealed that early treatment with HK-fbp1 cells elicited Th1-biased protective immune responses that help block fungal dissemination and promote better host protection. Our data thus suggest that HK-fbp1 is both an effective prophylactic vaccine candidate against C. neoformans infection in both immunocompetent and immunocompromised populations and a potential novel therapeutic strategy to treat early-stage cryptococcosis. IMPORTANCE Invasive fungal infections, e.g., cryptococcosis, are often life threatening and difficult to treat with very limited therapeutic options. There is no vaccine available in clinical use to prevent or treat fungal infections. Our previous studies demonstrated that heat-killed fbp1Δ cells (HK-fbp1) in Cryptococcus neoformans can be harnessed to confer protection against a challenge by the virulent parental strain, even in immunocompromised animals, such as ones lacking CD4+ T cells. In this study, we further determined that T cells are required for vaccine-induced protection against homologous challenge and that either CD4+ or CD8+ cells are sufficient. This finding is particularly important for the potential utility of this vaccine candidate in the context of HIV/AIDS-induced immune deficiency, the main risk factor for cryptococcosis in humans. Furthermore, in addition to the utility of HK-fbp1 as a prophylactic vaccine, we found that HK-fbp1 administration can inhibit disease dissemination when animals are treated at an early stage during Cryptococcus infection. Our findings could significantly expand the utility of HK-fbp1 not only as a prophylactic vaccine but also as a novel therapy against cryptococcosis. In all, our studies showed that the HK-fbp1 strain can be used both preventively and therapeutically to elicit robust host protection against cryptococcosis.

The Lack of HONO Measurement May Affect the Accurate Diagnosis of Ozone Production Sensitivity

Recently, deteriorating ozone (O₃) pollution in China brought the precise diagnosis of O₃ sensitive chemistry to the forefront. As a dominant precursor of OH radicals, atmospheric nitrous acid (HONO) plays an important role in O₃ production. However, its measurement unavailability in many regions especially for second- and third-tier cities may lead to the misjudgment of the O₃ sensitivity regime derived from observation-based models. Here, we systematically assess the potential impact of HONO on diagnosing the sensitivity of O₃ production using a 0-dimension box model based on a comprehensive summer urban field campaign. The results indicated that the default mode (only the NO + OH reaction is included) in the model could underestimate ∼87% of observed HONO levels, leading to an obvious decrease (∼19%) of net O₃ production in the morning, which was in line with the previous studies. The unconstrained HONO in the model was found to significantly push O₃ production toward the VOC-sensitive regime. Additionally, it is unrealistic to change NO _x but constrain HONO in the model due to the dependence of HONO formation on NO _x . Assuming that HONO varied proportionally with NO _x , a stronger NO _x -sensitive condition could be achieved. Therefore, effective reduction of NO _x should be given more attention together with VOC emission control for O₃ mitigation.

[Long-term trend of gastric cancer survival rate in Qidong, 1972-2016]

Objective: The survival rate of gastric cancer cases in the whole population of Qidong City of Jiangsu Province from 1972 to 2016 was analyzed to provide a data basis for prevention and control of gastric cancer. Methods: The observed survival rate (OSR) was calculated by the life table method, the relative survival rate (RSR) was calculated by SURV 3.01 software, and the trend test was performed by Hakulinen's likelihood ratio test. Age-standardized relative survival rate (ARSR) was calculated using the International Cancer Survival Standard (ICSS). The Joinpoint regression model was used to calculate the average annual percentage change (AAPC) of survival rate, and the trend analysis of the overall survival rate of gastric cancer and the survival rates of different sexes and ages was conducted. The ARIMA model was used to predict the survival rate. Results: From 1972 to 2016, there were 18 067 new cases of gastric cancer in Qidong City. The OSRs at 1, 5, and 10 years were 37.12%, 17.16%, and 12.86%, respectively, and the RSRs at 1, 5, and 10 years were 38.83%, 21.73%, and 21.20%. Dividing 1972-2016 into 9 periods at 5-year intervals, compared with 1972-1976, the 5-year RSR in 2012-2016 increased from 12.53% to 36.26%, and the RSR in the 9 periods increased with statistical significance (χ(2)=747.19, P<0.001). Both OSR and RSR were slightly higher in men than in women, and decreased with age. The AAPC results showed that the AAPC of the 5-year RSR of gastric cancer in Qidong was 2.88%, 2.75% in males and 3.05% in females, and the upward trend was statistically significant (P<0.001). From 1972 to 2016, the 5-year RSR of gastric cancer in all age groups showed an upward trend. Except for the 35-44-year-old group (AAPC=1.07%, t=2.16, P=0.067), the age groups had statistical significance ( AAPC=2.59% in the 45-54-year-old group, AAPC=3.19% in the AAPCs of other 55-64-year-old group, AAPC=3.99% in the 65-74-year-old group, and AAPC=2.97% in the 75-year-old group, all P<0.05). The prediction results of the ARIMA model showed that in 2026, the 5-year OSR of gastric cancer in Qidong will increase to 39.82%, and the 5-year RSR will increase to 49.23%. Conclusion: The overall survival rate of registered gastric cancer cases in Qidong has been greatly improved, but there is still large room for improvement. More attention should be paid to the prevention and treatment of gastric cancer.

Ubiquitin proteolysis of a CDK-related kinase regulates titan cell formation and virulence in the fungal pathogen Cryptococcus neoformans

Fungal pathogens often undergo morphological switches, including cell size changes, to adapt to the host environment and cause disease. The pathogenic yeast Cryptococcus neoformans forms so-called 'titan cells' during infection. Titan cells are large, polyploid, display alterations in cell wall and capsule, and are more resistant to phagocytosis and various types of stress. Titan cell formation is regulated by the cAMP/PKA signal pathway, which is stimulated by the protein Gpa1. Here, we show that Gpa1 is activated through phosphorylation by a CDK-related kinase (Crk1), which is targeted for degradation by an E3 ubiquitin ligase (Fbp1). Strains overexpressing CRK1 or an allele lacking a PEST domain exhibit increased production of titan cells similarly to the fbp1∆ mutant. Conversely, CRK1 deletion results in reduced titan cell production, indicating that Crk1 stimulates titan cell formation. Crk1 phosphorylates Gpa1, which then localizes to the plasma membrane and activates the cAMP/PKA signal pathway to induce cell enlargement. Furthermore, titan cell-overproducing strains trigger increased Th1 and Th17 cytokine production in CD4+ T cells and show attenuated virulence in a mouse model of systemic cryptococcosis. Overall, our study provides insights into the regulation of titan cell formation and fungal virulence.

The Anticancer Drug Bleomycin Shows Potent Antifungal Activity by Altering Phospholipid Biosynthesis

Invasive fungal infections are difficult to treat with limited drug options, mainly because fungi are eukaryotes and share many cellular mechanisms with the human host. Most current antifungal drugs are either fungistatic or highly toxic. Therefore, there is a critical need to identify important fungal specific drug targets for novel antifungal development. Numerous studies have shown the fungal phosphatidylserine (PS) biosynthetic pathway to be a potential target. It is synthesized from CDP-diacylglycerol and serine, and the fungal PS synthesis route is different from that in mammalian cells, in which preexisting phospholipids are utilized to produce PS in a base-exchange reaction. In this study, we utilized a Saccharomyces cerevisiae heterologous expression system to screen for inhibitors of Cryptococcus PS synthase Cho1, a fungi-specific enzyme essential for cell viability. We identified an anticancer compound, bleomycin, as a positive candidate that showed a phospholipid-dependent antifungal effect. Its inhibition on fungal growth can be restored by ethanolamine supplementation. Further exploration of the mechanism of action showed that bleomycin treatment damaged the mitochondrial membrane in yeast cells, leading to increased generation of reactive oxygen species (ROS), whereas supplementation with ethanolamine helped to rescue bleomycin-induced damage. Our results indicate that bleomycin does not specifically inhibit the PS synthase enzyme; however, it may affect phospholipid biosynthesis through disruption of mitochondrial function, namely, the synthesis of phosphatidylethanolamine (PE) and phosphatidylcholine (PC), which helps cells maintain membrane composition and functionality. IMPORTANCE Invasive fungal pathogens cause significant morbidity and mortality, with over 1.5 million deaths annually. Because fungi are eukaryotes that share much of their cellular machinery with the host, our armamentarium of antifungal drugs is highly limited, with only three classes of antifungal drugs available. Drug toxicity and emerging resistance have limited their use. Hence, targeting fungi-specific enzymes that are important for fungal survival, growth, or virulence poses a strategy for novel antifungal development. In this study, we developed a heterologous expression system to screen for chemical compounds with activity against Cryptococcus phosphatidylserine synthase, Cho1, a fungi-specific enzyme that is essential for viability in C. neoformans. We confirmed the feasibility of this screen method and identified a previously unexplored role of the anticancer compound bleomycin in disrupting mitochondrial function and inhibiting phospholipid synthesis.

The seasonal variations and potential sources of nitrous acid (HONO) in the rural North China Plain

Nitrous acid (HONO), an essential precursor of hydroxyl radicals (OH) in the troposphere, plays an integral role in atmospheric photochemistry. However, potential HONO sources remain unclear, particularly in rural areas, where long-term (including seasonal) measurements are scarce. HONO and related parameters were measured at a rural site in the North China Plain (NCP) during the winter of 2017 and summer and autumn of 2020. The mean HONO level was higher in winter (1.79 ± 1.44 ppbv) than in summer (0.67 ± 0.50 ppbv) and autumn (0.83 ± 0.62 ppbv). Source analysis revealed that the heterogeneous conversion (including photo-enhanced conversion) of NO₂ on the ground surface dominated the daytime HONO production in the three seasons (43.1% in winter, 54.3% in summer, and 62.0% in autumn), and the homogeneous reaction of NO and OH contributed 37.8, 12.2, and 28.4% of the daytime HONO production during winter, summer, and autumn, respectively. In addition, the total contributions of other sources (direct vehicle emissions, particulate nitrate photolysis, NO₂ uptake and its photo-enhanced reaction on the aerosol surface) to daytime HONO production were less than 5% in summer and autumn and 12.0% in winter. Unlike winter and autumn, an additional HONO source was found in summer (0.45 ± 0.21 ppbv h^-1, 31.4% to the daytime HONO formation), which might be attributed to the HONO emission from the fertilized field. Among the primary radical sources (photolysis of HONO, O₃, and formaldehyde), HONO photolysis was dominant, with contributions of 82.6, 49.3, and 63.2% in winter, summer, and autumn, respectively. Our findings may aid in understanding HONO formation in different seasons in rural areas and may highlight the impact of HONO on atmospheric oxidation capacity.

Strong impacts of biomass burning, nitrogen fertilization, and fine particles on gas-phase hydrogen peroxide (H2O2)

Gas-phase hydrogen peroxide (H₂O₂) plays an important role in atmospheric chemistry as an indicator of the atmospheric oxidizing capacity. It is also a vital oxidant of sulfur dioxide (SO₂) in the aqueous phase, resulting in the formation of acid precipitation and sulfate aerosol. However, sources of H₂O₂ are not fully understood especially in polluted areas affected by human activities. In this study, we reported some high H₂O₂ cases observed during one summer and two winter campaigns conducted at a polluted rural site in the North China Plain. Our results showed that agricultural fires led to high H₂O₂ concentrations up to 9 ppb, indicating biomass burning events contributed substantially to primary H₂O₂ emission. In addition, elevated H₂O₂ and O₃ concentrations were measured after fertilization as a consequence of the enhanced atmospheric oxidizing capacity by soil HONO emission. Furthermore, H₂O₂ exhibited unexpectedly high concentration under high NO_x conditions in winter, which are closely related to multiphase reactions in particles involving organic chromophores. Our findings suggest that these special factors (biomass burning, fertilization, and ambient particles), which are not well considered in current models, are significant contributors to H₂O₂ production, thereby affecting the regional atmospheric oxidizing capacity and the global sulfate aerosol formation.

Harnessing the Immune Response to Fungal Pathogens for Vaccine Development

Invasive fungal infections are emerging diseases that kill over 1.5 million people per year worldwide. With the increase of immunocompromised populations, the incidence of invasive fungal infections is expected to continue to rise. Vaccines for viral and bacterial infectious diseases have had a transformative impact on human health worldwide. However, no fungal vaccines are currently in clinical use. Recently, interest in fungal vaccines has grown significantly. One Candida vaccine has completed phase 2 clinical trials, and research on vaccines against coccidioidomycosis continues to advance. Additionally, multiple groups have discovered various Cryptococcus mutant strains that promote protective responses to subsequent challenge in mouse models. There has also been progress in antibody-mediated fungal vaccines. In this review, we highlight recent fungal vaccine research progress, outline the wealth of data generated, and summarize current research for both fungal biology and immunology studies relevant to fungal vaccine development. We also review technological advancements in vaccine development and highlight the future prospects of a human vaccine against invasive fungal infections.

Discrimination between microcystic meningioma and atypical meningioma using whole-lesion apparent diffusion coefficient histogram analysis

AIM

To explore the value of whole-lesion apparent diffusion coefficient (ADC) histogram analysis in discriminating microcystic meningioma (MCM) from atypical meningioma (AM).

MATERIALS AND METHODS

Clinical and preoperative MRI data of 20 patients with MCM and 26 patients with AM were analysed retrospectively. Whole-lesion apparent diffusion coefficient (ADC) histogram analysis was performed on each patient's lesion to obtain histogram parameters, including mean, variance, skewness, kurtosis, the 1st (ADCp1), 10th (ADCp10), 50th (ADCp50), 90th (ADCp90), and 99th (ADCp99) percentiles of ADC. The differences between the ADC histogram parameters of the two tumours were compared, and the receiver operating characteristic (ROC) curve was used to assess the diagnostic performance of statistically significant parameters in distinguishing the two tumours.

RESULTS

The mean, ADCp1, ADCp10, ADCp50, and ADCp90 of MCM were greater than those of AM, and significant differences were observed in these parameters between MCM and AM (all p<0.05). ROC analysis showed that the mean had the highest area under the curve value (AUC) in distinguishing the two tumours (AUC = 0.852), when using 120.46 × 10^-6 mm²/s as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for discriminating the two groups were 84.6%, 75%, 80.4%, 81.5%, and 78.9%, respectively.

CONCLUSION

Histogram analysis based on whole-lesion ADC maps was useful for discriminating between MCM from AM preoperatively, with the mean being the most promising potential parameter.

Development of Antifungal Peptides against Cryptococcus neoformans; Leveraging Knowledge about the cdc50Δ Mutant Susceptibility for Lead Compound Development

Cryptococcus neoformans is a major fungal pathogen that often causes life-threatening meningitis in immunocompromised populations. This yeast pathogen is highly resistant to the echinocandin drug caspofungin. Previous studies showed that Cryptococcus lipid translocase (flippase) is required for the caspofungin resistance of that fungus. Mutants with a deleted subunit of lipid flippase, Cdc50, showed increased sensitivity to caspofungin. Here we designed an antifungal peptide targeting the P4-ATPase function. We synthesized stable peptides based on the Cdc50 loop region to identify peptides that can sensitize caspofungin by blocking flippase function and found that myristylated peptides based on the "AS15 sequence" was effective at high concentrations. A modified peptide, "AW9-Ma" showed a MIC of 64 μg/mL against H99 wild type and a fractional inhibitory concentration (FIC) index value of 0.5 when used in combination with caspofungin. Most notably, in the presence of the AW9-Ma peptide, C. neoformans wild type was highly sensitive to caspofungin with a MIC of 4 μg/mL, the same as the cdc50Δ mutant. Further assays with flow cytometry showed inhibition of the lipid flippase enzyme activity and significant accumulation of phosphatidylserine on the cell membrane surface. Using a fluorescently labeled peptide, we confirmed that the peptide co-localized with mCherry-tagged P4-ATPase protein Apt1 in C. neoformans. Structure-activity relationship studies of the AW9 sequence showed that two lysine residues on the peptide are likely responsible for the interaction with the P4-ATPase, hence critical for its antifungal activity. IMPORTANCE The authors have developed a lead compound peptide antifungal drug targeting a protein from the organism Cryptococcus neoformans. Binding of the drug to the target fungal protein causes charged lipid molecules to be retained on the surface. This peptide works in synergy with the existing antifungal drug caspofungin. Echinocandin drugs like caspofungin are one of the few classes of existing antifungals. Due to the high concentrations needed, caspofungin is rarely used to treat C. neoformans infections. The authors believe that their new compound provides a way to lower the concentration of caspofungin needed to treat such infections, thus opening the possibility for greater utility of these antifungal.

Macrophage Mediated Immunomodulation During Cryptococcus Pulmonary Infection

Macrophages are key cellular components of innate immunity, acting as the first line of defense against pathogens to modulate homeostatic and inflammatory responses. They help clear pathogens and shape the T-cell response through the production of cytokines and chemokines. The facultative intracellular fungal pathogen Cryptococcus neoformans has developed a unique ability to interact with and manipulate host macrophages. These interactions dictate how Cryptococcus infection can remain latent or how dissemination within the host is achieved. In addition, differences in the activities of macrophages have been correlated with differential susceptibilities of hosts to Cryptococcus infection, highlighting the importance of macrophages in determining disease outcomes. There is now abundant information on the interaction between Cryptococcus and macrophages. In this review we discuss recent advances regarding macrophage origin, polarization, activation, and effector functions during Cryptococcus infection. The importance of these strategies in pathogenesis and the potential of immunotherapy for cryptococcosis treatment is also discussed.

High crop yield losses induced by potential HONO sources - A modelling study in the North China Plain

Nitrous acid (HONO) is a major source of hydroxyl radicals in the troposphere through its photolysis, and can significantly influence ozone (O₃) levels, thereby causing considerable crop yield losses. Previous studies have assessed relative crop yield losses by using exposure-response equations with observed or simulated O₃, however, the contribution of enhanced O₃ due to potential HONO sources to the crop yield losses has never been quantified. In this study, for the first time, we evaluated the crop yield losses caused by potential HONO sources in the North China Plain (NCP), which is one of the major grain-producing areas in China suffering from heavy O₃ pollution, by using the Weather Research and Forecasting/Chemistry (WRF-Chem) model during the wheat and maize growing seasons of 2016. HONO simulations were significantly improved after including six potential HONO sources in the WRF-Chem model. The potential HONO sources produced a daily maximum 8-h O₃ enhancement of 8.1/8.2 ppb during the wheat/maize growing seasons, respectively, and led to ~11.4%/3.3% relative yield losses for wheat/maize, respectively, corresponding to approximately US$3.78/0.66 billion losses, respectively, in NCP in 2016. The above results suggest that potential HONO sources play a significant role in O₃ formation and could induce high crop yield losses globally.

[Validation of a hyperkalemia prediction model in chronic kidney disease]

Objective: To validate the accuracy and consistency of a previously established prediction model for the occurrence of hyperkalemia in non-dialytic chronic kidney disease (CKD) patients. Methods: All patients diagnosed with CKD from Outpatient Department of Shanghai Changzheng Hospital during the 4th quarter of 2020 were recruited. Demographic data, clinical characteristics and prediction model-related parameters of the patients were collected and analyzed. Receiver operating characteristic (ROC) curve was drawn to evaluate the effectiveness of the model, and the specificity and sensitivity were calculated based on the cut-off value of 4 obtained from the previous model. The improved Hanley method was used to compare the area under the curve (AUC) between the previously established model and current validation dataset. The calibration curve was drawn to verify the model calibration degree. Results: A total of 434 patients diagnosed with non-dialytic CKD were enrolled, among whom 233 were males and 201 were females, with an average age of (55±16) years. According to the measured serum potassium values, the prevalence of hyperkalemia was 7.6%. And 33 patients were allocated to the hyperkalemia group and 401 patients were to the normal potassium group. There was no significant difference in age and sex between the two groups (both P>0.05). A combination of hyperkalemia and heart failure (27.3% vs 3.7%, P<0.001), diabetes (42.4% vs 19.7%, P=0.002), and acidosis (51.5% vs 7.0%, P<0.001) were more frequently in the hyperkalemia group, compared with the normal serum potassium group. Patients in the hyperkalemia group were more likely to have a past history of serum potassium ≥5.0 mmol/L (48.5% vs 2.5%, P<0.001). For the drugs that could increase serum potassium levels, there was a significant correlation between Chinese herbal medicine and the occurrence of hyperkalemia, while renin-angiotensin-aldosterone system inhibitor (RAASi) and potassium supplementation showed no significant difference between the two groups. The results of ROC curve analysis showed that the AUC was 0.914, with the sensitivity of 84.8% and the specificity of 79.8% with the cut-off value of 4. The difference of AUC between the previously established risk assessment model of hyperkalemia in patients with non-dialytic CKD and current validation dataset was not statistically significant (Z=1.924, P=0.054), indicating the good accuracy and consistency of the prediction model. In the calibration curve, when the predicted risk of patients was below 0.4 or above 0.6, the prediction effect of the model was better. Conclusion: The previously-constructed hyperkalemia prediction model in non-dialytic CKD patients had good accuracy and consistency, and could be used to evaluate the risk of hyperkalemia in all stages of non-dialytic CKD patients.

Photochemical Aging of Atmospheric Fine Particles as a Potential Source for Gas-Phase Hydrogen Peroxide

Atmospheric hydrogen peroxide (H₂O₂), as an important oxidant, plays a key role in atmospheric sulfate formation, affecting the global radiation budget and causing acid rain deposition. The disproportionation reactions of hydroperoxyl radicals (HO₂) in both gas and aqueous phases have long been considered as dominant sources for atmospheric H₂O₂. However, these known sources cannot explain the significant formation of H₂O₂ in polluted areas under the conditions of high NO levels and low ambient relative humidity (RH). Here, we show that under relatively dry conditions during daytime, atmospheric fine particles directly produce abundant gas-phase H₂O₂. The formation of H₂O₂ is verified to be by a reaction between the particle surface -OH group and HO₂ radicals formed by photooxidation of chromophoric dissolved organic matters (CDOMs), which is slightly influenced by the presence of high NO levels but remarkably accelerated by water vapor and O₂. In contrast to aqueous-phase chemistry, transition metal ions (TMIs) are found to significantly suppress H₂O₂ formation from the atmospheric fine particles. The H₂O₂ formed from relatively dry particles can be directly involved in in situ SO₂ oxidation, leading to sulfate formation. As CDOMs are ubiquitous in atmospheric fine particles, their daytime photochemistry is expected to play important roles in formation of H₂O₂ and sulfate worldwide.

More Than Just Cleaning: Ubiquitin-Mediated Proteolysis in Fungal Pathogenesis

Ubiquitin-proteasome mediated protein turnover is an important regulatory mechanism of cellular function in eukaryotes. Extensive studies have linked the ubiquitin-proteasome system (UPS) to human diseases, and an array of proteasome inhibitors have been successfully developed for cancer therapy. Although still an emerging field, research on UPS regulation of fungal development and virulence has been rapidly advancing and has generated considerable excitement in its potential as a target for novel drugs. In this review, we summarize UPS composition and regulatory function in pathogenic fungi, especially in stress responses, host adaption, and fungal pathogenesis. Emphasis will be given to UPS regulation of pathogenic factors that are important for fungal pathogenesis. We also discuss future potential therapeutic strategies for fungal infections based on targeting UPS pathways.

Improving the representation of HONO chemistry in CMAQ and examining its impact on haze over China

We compare Community Multiscale Air Quality (CMAQ) model predictions with measured nitrous acid (HONO) concentrations in Beijing, China for December 2015. The model with the existing HONO chemistry in CMAQ severely under-estimates the observed HONO concentrations with a normalized mean bias of -97%. We revise the HONO chemistry in the model by implementing six additional heterogeneous reactions in the model: reaction of nitrogen dioxide (NO2) on ground surfaces, reaction of NO2 on aerosol surfaces, reaction of NO2 on soot surfaces, photolysis of aerosol nitrate, nitric acid displacement reaction, and hydrochloric acid displacement reaction. The model with the revised chemistry substantially increases HONO predictions and improves the comparison with observed data with a normalized mean bias of -5%. The photolysis of HONO enhances day-time hydroxyl radical by almost a factor of two. The enhanced hydroxyl radical concentrations compare favourably with observed data and produce additional sulfate via the reaction with sulfur dioxide, aerosol nitrate via the reaction with nitrogen dioxide, and secondary organic aerosols via the reactions with volatile organic compounds. The additional sulfate stemming from revised HONO chemistry improves the comparison with observed concentration; however, it does not close the gap between model prediction and the observation during polluted days.

Particle-Phase Photoreactions of HULIS and TMIs Establish a Strong Source of H2O2 and Particulate Sulfate in the Winter North China Plain

During haze periods in the North China Plain, extremely high NO concentrations have been observed, commonly exceeding 1 ppbv, preventing the classical gas-phase H₂O₂ formation through HO₂ recombination. Surprisingly, H₂O₂ mixing ratios of about 1 ppbv were observed repeatedly in winter 2017. Combined field observations and chamber experiments reveal a photochemical in-particle formation of H₂O₂, driven by transition metal ions (TMIs) and humic-like substances (HULIS). In chamber experiments, steady-state H₂O₂ mixing ratios of 116 ± 83 pptv were observed upon the irradiation of TMI- and HULIS-containing particles. Correspondingly, H₂O₂ formation rates of about 0.2 ppbv h^-1 during the initial irradiation periods are consistent with the H₂O₂ rates observed in the field. A novel chemical mechanism was developed explaining the in-particle H₂O₂ formation through a sequence of elementary photochemical reactions involving HULIS and TMIs. Dedicated box model studies of measurement periods with relative humidity >50% and PM_2.5 ≥ 75 μg m^-3 agree with the observed H₂O₂ concentrations and time courses. The modeling results suggest about 90% of the particulate sulfate to be produced from the SO₂ reaction with OH and HSO₃^- oxidation by H₂O₂. Overall, under high pollution, the H₂O₂-caused sulfate formation rate is above 250 ng m^-3 h^-1, contributing to the sulfate formation by more than 70%.

[Establishment of animal models of epidermal growth factor receptor inhibitor-related rashes]

OBJECTIVE

To establish animal models epidermal growth factor receptor inhibitor-related skin rashes using cetuximab, gefitinib or erlotinib.

OBJECTIVE

Female SCID mice were randomly divided into blank control group and high-, moderate-, and low-dose cetuximab groups. The mice in control group received intraperitoneal injection of saline, and those in the 3 cetuximab groups were injected with 80, 40, and 20 mg/kg cetuximab (3 times a week for 4 weeks), respectively. The general skin appearance and skin pathologies of the mice were observed. Female BN rats were randomly divided into blank group, ovalbumin group, gefitinib group and erlotinib group, and in the latter 3 groups, the rats were given ovalbumin (1 mg), gefitinib (37.5 mg/kg), and erlotinib (23.5 mg/kg) by lavage once daily for 45 days, respectively. Skin pathologies of the rats were observed, and serum levels of TNF-α, IL-6 and other inflammatory factors were detected using ELISA.

OBJECTIVE

Intraperitoneal injection of cetuximab did not induce typical skin rashes, scabs or obvious skin inflammation in the mice. In female BN rats, lavage of gefitinib caused obvious skin rashes, scabs and exudation, and obvious inflammatory cell infiltration, keratinosis, spinous layer release and epidermal thickening were observed in the skin. No obvious skin inflammation were observed in the rats in the control, ovalbumin or erlotinib groups. While IgE (P=0.061) and TNF-α concentrations (P=0.057) did not differ significantly among the groups, serum levels of IL-6 was significantly higher in gefitinib group than in the blank control group (P=0.016) but similar between erlotinib group and the blank group (P=0.910).

OBJECTIVE

Intraperitoneal injection of cetuximab can not induce epidermal growth factor receptor inhibitor-related skin rashes in SCID mice. Lavage of gefitinib, but not erlotinib, can be used to establish models of epidermal growth factor receptor inhibitor-related rashes in BN rats.

COVID-19-Induced Lockdowns Indicate the Short-Term Control Effect of Air Pollutant Emission in 174 Cities in China

The contradiction between the regional imbalance and an one-size-fits-all policy is one of the biggest challenges in current air pollution control in China. With the recent implementation of first-level public health emergency response (FLPHER) in response to the COVID-19 pandemic in China (a total of 77 041 confirmed cases by February 22, 2020), human activities were extremely decreased nationwide and almost all economic activities were suspended. Here, we show that this scenario represents an unprecedented "base period" to probe the short-term emission control effect of air pollution at a city level. We quantify the FLPHER-induced changes of NO₂, SO₂, PM_2.5, and PM₁₀ levels in 174 cities in China. A machine learning prediction model for air pollution is established by coupling a generalized additive model, random effects meta-analysis, and weather research and forecasting model with chemistry analysis. The short-term control effect under the current energy structure in each city is estimated by comparing the predicted and observed results during the FLPHER period. We found that the short-term emission control effect ranges within 53.0%-98.3% for all cities, and southern cities show a significantly stronger effect than northern cities (P < 0.01). Compared with megacities, small-medium cities show a similar control effect on NO₂ and SO₂ but a larger effect on PM_2.5 and PM₁₀.

[Cost-effectiveness of primary prophylaxis with PEG-rhG-CSF in early-stage breast cancer patients receiving chemotherapy in China]

Objective: To evaluate the cost effectiveness of primary prophylaxis (PP) with pegylated recombinant human granulocyte colony stimulating factor (PEG-rhG-CSF), PP with recombinant human granulocyte colony stimulating factor (rhG-CSF) and no prophylaxis in women with early-stage breast cancer in China. Methods: Two phase Markov models were constructed for a hypothetical cohort of patients aged 45 with stage Ⅱ breast cancer. The first phase modelled costs and outcomes of 4 cycles docetaxel combined with cyclophosphamide [TC×4, febrile neutropenia (FN) risk>20%] chemotherapy, which assumptions based on literature reviews, including FN rates [base-case (deterministic sensitivity analysis range), 0.29 (0.24-0.35)] and related events [FN case-fatality, 3.4 (2.7-4.1)]. Second phase modelled the long term survival which was link with the relative dose intensity (RDI) [mortality hazard ratio (HR) of RDI < 85% vs ≥85%, 1.45 (1.00-2.32)]. Clinical effectiveness, therapeutic costs, and economic utilities were estimated from peer-reviewed publications and expert opinions in case of unavailability of published evidences. Results: Compared to rhG-CSF PP and no prophylaxis, the cost of PEG-rhG-CSF PP increased to 5 208.19 RMB and 5 222.73 RMB, respectively. The quality-adjusted life-years (QALYs) enhanced to 0.066 and 0.297, respectively. Accordingly, the incremental cost effectiveness ratios (ICERs) are 79 146.3 RMB and 17 558.77 RMB per QALY, which were both below the willingness to pay (WTP) threshold of three times GDP per capita (18, 000 RMB) recommended by the WHO. Sensitivity analysis suggested that the more clinically effective the primary prophylaxis with PEG-rhG-CSF is, the more cost-effective primary prophylaxis with PEG-rhG-CSF will be. And the lower the mortality HR of RDI<85% vs ≥85% is, the more cost-effective primary prophylaxis with PEG-rhG-CSF will be. Conclusion: Although the cost of PP PEG-rhG-CSF is higher, considering the additional benefits, the administrating of PP PEG-rhG-CSF is likely to be a cost-effective alternative to PP rhG-CSF and no prophylaxis in patients with early stage breast cancer whose FN risks are more than 20% in China.

HONO Budget and Its Role in Nitrate Formation in the Rural North China Plain

Nitrous acid (HONO) is a major precursor of tropospheric hydroxyl radical (OH) that accelerates the formation of secondary pollutants. The HONO sources, however, are not well understood, especially in polluted areas. Based on a comprehensive winter field campaign conducted at a rural site of the North China Plain, a box model (MCM v3.3.1) was used to simulate the daytime HONO budget and nitrate formation. We found that HONO photolysis acted as the dominant source for primary OH with a contribution of more than 92%. The observed daytime HONO could be well explained by the known sources in the model. The heterogeneous conversion of NO₂ on ground surfaces and the homogeneous reaction of NO with OH were the dominant HONO sources with contributions of more than 36 and 34% to daytime HONO, respectively. The contribution from the photolysis of particle nitrate and the reactions of NO₂ on aerosol surfaces was found to be negligible in clean periods (2%) and slightly higher during polluted periods (8%). The relatively high OH levels due to fast HONO photolysis at the rural site remarkably accelerated gas-phase reactions, resulting in the fast formation of nitrate as well as other secondary pollutants in the daytime.

The pollution levels, variation characteristics, sources and implications of atmospheric carbonyls in a typical rural area of North China Plain during winter

Atmospheric carbonyls were measured at a typical rural area of the North China Plain (NCP) from November 13 to December 24, 2017 to investigate the pollution characteristics, sources and environmental implications. Fifteen carbonyls were detected, and formaldehyde, acetaldehyde and acetone accounted for about 81% at most. The concentration of the total carbonyls in heavily polluted days was twice more than that in clean days. In contrast to other carbonyls, m-tolualdehyde exhibited relatively high concentrations in the clean days in comparison with the polluted days. The ratios of three principal carbonyls to CO showed similar daily variations at different pollution levels with significant daytime peaks. Multiple linear regression analysis revealed that the contributions of background, primary and secondary sources to three principal carbonyls showed similar variation trends from the clean level to the heavily polluted level. The OH formation rate of formaldehyde showed a similar variation trend to its photodegradation rate, reaching the peak value at noon, which is important to maintain relatively high OH levels to initiate the oxidation of various gas-phase pollutants for secondary pollutant formation at the rural site. OH radical consumption rate and ozone formation potential (OFP) calculations showed that formaldehyde and acetaldehyde were the dominant oxidative species among measured carbonyls. As for OH radical consumption, n-butyraldehyde and m-tolualdehyde were important contributors, while for ozone formation potential, n-butyraldehyde and propionaldehyde made significant contributions. In addition, the contribution of carbonyl compounds to secondary organic aerosol (SOA) formation was also important and needs further investigation.

Pollution levels, composition characteristics and sources of atmospheric PM2.5 in a rural area of the North China Plain during winter

The pollution levels, composition characteristics and sources of atmospheric PM_2.5 were investigated based on field measurement at a rural site in the North China Plain (NCP) from pre-heating period to heating period in winter of 2017. The hourly average concentrations of PM_2.5 frequently exceeded 150 µg/m³ and even achieved 400 µg/m³, indicating that the PM_2.5 pollution was still very serious despite the implementation of stricter control measures in the rural area. Compared with the pre-heating period, the mean concentrations of organic carbon (OC), element carbon (EC) and chlorine ion (Cl^-) during the heating period increased by 20.8%, 36.6% and 38.8%, accompanying with increments of their proportions in PM_2.5 from 37.5%, 9.8% and 5.5% to 42.9%, 12.7% and 7.2%, respectively. The significant increase of both their concentrations and proportions during the heating period was mainly ascribed to the residential coal combustion. The proportions of sulfate, nitrate and ammonium respectively increased from 9.9%, 10.9% and 9.0% in nighttime to 13.8%, 16.2% and 11.1% in daytime, implying that the daytime photochemical reactions made remarkable contributions to the secondary inorganic aerosols. The simulation results from WRF-Chem revealed that the emission of residential coal combustion in the rural area was underestimated by the current emission inventory. Six sources identified by positive matrix factorization (PMF) based on the measurement were residential coal combustion, secondary formation of inorganic aerosols, biomass burning, vehicle emission and raising dust, contributing to atmospheric PM_2.5 of 40.5%, 21.2%, 16.4%, 10.8%, 8.6% and 2.5%, respectively.

Effect of potential HONO sources on peroxyacetyl nitrate (PAN) formation in eastern China in winter

As an important secondary photochemical pollutant, peroxyacetyl nitrate (PAN) has been studied over decades, yet its simulations usually underestimate the corresponding observations, especially in polluted areas. Recent observations in north China found unusually high concentrations of PAN during wintertime heavy haze events, but the current model still cannot reproduce the observations, and researchers speculated that nitrous acid (HONO) played a key role in PAN formation. For the first time we systematically assessed the impact of potential HONO sources on PAN formation mechanisms in eastern China using the Weather Research and Forecasting/Chemistry (WRF-Chem) model in February of 2017. The results showed that the potential HONO sources significantly improved the PAN simulations, remarkably accelerated the RO_x (sum of hydroxyl, hydroperoxyl, and organic peroxy radicals) cycles, and resulted in 80%-150% enhancements of PAN near the ground in the coastal areas of eastern China and 10%-50% enhancements in the areas around 35-40°N within 3 km during a heavy haze period. The direct precursors of PAN were aldehyde and methylglyoxal, and the primary precursors of PAN were alkenes with C > 3, xylenes, propene and toluene. The above results suggest that the potential HONO sources should be considered in regional and global chemical transport models when conducting PAN studies.

Activation of Meiotic Genes Mediates Ploidy Reduction during Cryptococcal Infection

Cryptococcus neoformans is a global human fungal pathogen that causes fatal meningoencephalitis in mostly immunocompromised individuals. During pulmonary infection, cryptococcal cells form large polyploid cells that exhibit increased resistance to host immune attack and are proposed to contribute to the latency of cryptococcal infection. These polyploid titan cells can generate haploid and aneuploid progeny that may result in systemic infection. What triggers cryptococcal polyploidization and how ploidy reduction is achieved remain open questions. Here, we discovered that Cryptococcus cells polyploidize in response to genotoxic stresses that cause DNA double-strand breaks. Intriguingly, meiosis-specific genes are activated in C. neoformans and contribute to ploidy reduction, both in vitro and during infection in mice. Cryptococcal cells that activated their meiotic genes in mice were resistant to specific genotoxic stress compared to sister cells recovered from the same host tissue but without activation of meiotic genes. Our findings support the idea that meiotic genes, in addition to their conventional roles in classic sexual reproduction, contribute to adaptation of eukaryotic cells that undergo dramatic genome changes in response to genotoxic stress. The discovery has additional implications for evolution of sexual reproduction and the paradox of the presence of meiotic machinery in asexual species. Finally, our findings in this eukaryotic microbe mirror the revolutionary discoveries of the polyploidization and meiosis-like ploidy reduction process in cancer cells, suggesting that the reversible ploidy change itself could provide a general mechanism for rejuvenation to promote individual survival in response to stress.