GOLVEN peptide signalling through RGI receptors and MPK6 restricts asymmetric cell division during lateral root initiation

During lateral root initiation, lateral root founder cells undergo asymmetric cell divisions that generate daughter cells with different sizes and fates, a prerequisite for correct primordium organogenesis. An excess of the GLV6/RGF8 peptide disrupts these initial asymmetric cell divisions, resulting in more symmetric divisions and the failure to achieve lateral root organogenesis. Here, we show that loss-of-function GLV6 and its homologue GLV10 increase asymmetric cell divisions during lateral root initiation, and we identified three members of the RGF1 INSENSITIVE/RGF1 receptor subfamily as likely GLV receptors in this process. Through a suppressor screen, we found that MITOGEN-ACTIVATED PROTEIN KINASE6 is a downstream regulator of the GLV pathway. Our data indicate that GLV6 and GLV10 act as inhibitors of asymmetric cell divisions and signal through RGF1 INSENSITIVE receptors and MITOGEN-ACTIVATED PROTEIN KINASE6 to restrict the number of initial asymmetric cell divisions that take place during lateral root initiation. The authors demonstrate the negative role of GOLVEN peptides during lateral root initiation in Arabidopsis, at the very early stage of the first asymmetric cell division of lateral root founder cells, and identify the receptors for these peptides

A 3D study on the amplification of regional haze and particle growth by local emissions

The role of new particle formation (NPF) events and their contribution to haze formation through subsequent growth in polluted megacities is still controversial. To improve the understanding of the sources, meteorological conditions, and chemistry behind air pollution, we performed simultaneous measurements of aerosol composition and particle number size distributions at ground level and at 260 m in central Beijing, China, during a total of 4 months in 2015-2017. Our measurements show a pronounced decoupling of gas-to-particle conversion between the two heights, leading to different haze processes in terms of particle size distributions and chemical compositions. The development of haze was initiated by the growth of freshly formed particles at both heights, whereas the more severe haze at ground level was connected directly to local primary particles and gaseous precursors leading to higher particle growth rates. The particle growth creates a feedback loop, in which a further development of haze increases the atmospheric stability, which in turn strengthens the persisting apparent decoupling between the two heights and increases the severity of haze at ground level. Moreover, we complemented our field observations with model analyses, which suggest that the growth of NPF-originated particles accounted up to similar to 60% of the accumulation mode particles in the Beijing-Tianjin-Hebei area during haze conditions. The results suggest that a reduction in anthropogenic gaseous precursors, suppressing particle growth, is a critical step for alleviating haze although the number concentration of freshly formed particles (3-40 nm) via NPF does not reduce after emission controls.Peer reviewe

Role of iodine oxoacids in atmospheric aerosol nucleation

Iodic acid (HIO3) is known to form aerosol particles in coastal marine regions, but predicted nucleation and growth rates are lacking. Using the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we find that the nucleation rates of HIO3 particles are rapid, even exceeding sulfuric acid-ammonia rates under similar conditions. We also find that ion-induced nucleation involves IO3- and the sequential addition of HIO3 and that it proceeds at the kinetic limit below +10 degrees C. In contrast, neutral nucleation involves the repeated sequential addition of iodous acid (HIO2) followed by HIO3, showing that HIO2 plays a key stabilizing role. Freshly formed particles are composed almost entirely of HIO3, which drives rapid particle growth at the kinetic limit. Our measurements indicate that iodine oxoacid particle formation can compete with sulfuric acid in pristine regions of the atmosphere.Peer reviewe

Molecular Composition of Oxygenated Organic Molecules and Their Contributions to Organic Aerosol in Beijing

The understanding at a molecular level of ambient secondary organic aerosol (SOA) formation is hampered by poorly constrained formation mechanisms and insufficient analytical methods. Especially in developing countries, SOA related haze is a great concern due to its significant effects on climate and human health. We present simultaneous measurements of gas-phase volatile organic compounds (VOCs), oxygenated organic molecules (OOMs), and particle-phase SOA in Beijing. We show that condensation of the measured OOMs explains 26-39% of the organic aerosol mass growth, with the contribution of OOMs to SOA enhanced during severe haze episodes. Our novel results provide a quantitative molecular connection from anthropogenic emissions to condensable organic oxidation product vapors, their concentration in particle-phase SOA, and ultimately to haze formation.Peer reviewe

Direct field evidence of autocatalytic iodine release from atmospheric aerosol

Reactive iodine plays a key role in determining the oxidation capacity, or cleansing capacity, of the atmosphere in addition to being implicated in the formation of new particles in the marine boundary layer. The postulation that heterogeneous cycling of reactive iodine on aerosols may significantly influence the lifetime of ozone in the troposphere not only remains poorly understood but also heretofore has never been observed or quantified in the field. Here, we report direct ambient observations of hypoiodous acid (HOI) and heterogeneous recycling of interhalogen product species (i.e., iodine monochloride [ICI] and iodine monobromide [IBr]) in a midlatitude coastal environment. Significant levels of ICI and IBr with mean daily maxima of 4.3 and 3.0 parts per trillion by volume (1-min average), respectively, have been observed throughout the campaign. We show that the heterogeneous reaction of HOI on marine aerosol and subsequent production of iodine interhalogens are much faster than previously thought. These results indicate that the fast formation of iodine interhalogens, together with their rapid photolysis, results in more efficient recycling of atomic iodine than currently considered in models. Photolysis of the observed ICI and IBr leads to a 32% increase in the daytime average of atomic iodine production rate, thereby enhancing the average daytime iodine-catalyzed ozone loss rate by 10 to 20%. Our findings provide direct field evidence that the autocatalytic mechanism of iodine release from marine aerosol is important in the atmosphere and can have significant impacts on atmospheric oxidation capacity.Peer reviewe

Role of sesquiterpenes in biogenic new particle formation

Biogenic vapors form new particles in the atmosphere, affecting global climate. The contributions of monoterpenes and isoprene to new particle formation (NPF) have been extensively studied. However, sesquiterpenes have received little attention despite a potentially important role due to their high molecular weight. Via chamber experiments performed under atmospheric conditions, we report biogenic NPF resulting from the oxidation of pure mixtures of β-caryophyllene, α-pinene, and isoprene, which produces oxygenated compounds over a wide range of volatilities. We find that a class of vapors termed ultralow-volatility organic compounds (ULVOCs) are highly efficient nucleators and quantitatively determine NPF efficiency. When compared with a mixture of isoprene and monoterpene alone, adding only 2% sesquiterpene increases the ULVOC yield and doubles the formation rate. Thus, sesquiterpene emissions need to be included in assessments of global aerosol concentrations in pristine climates where biogenic NPF is expected to be a major source of cloud condensation nuclei

Role of iodine oxoacids in atmospheric aerosol nucleation

Iodic acid (HIO₃) is known to form aerosol particles in coastal marine regions, but predicted nucleation and growth rates are lacking. Using the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we find that the nucleation rates of HIO₃ particles are rapid, even exceeding sulfuric acid–ammonia rates under similar conditions. We also find that ion-induced nucleation involves IO₃⁻ and the sequential addition of HIO₃ and that it proceeds at the kinetic limit below +10°C. In contrast, neutral nucleation involves the repeated sequential addition of iodous acid (HIO₂) followed by HIO₃, showing that HIO₂ plays a key stabilizing role. Freshly formed particles are composed almost entirely of HIO₃, which drives rapid particle growth at the kinetic limit. Our measurements indicate that iodine oxoacid particle formation can compete with sulfuric acid in pristine regions of the atmosphere

Predicting Hepatotoxicity Associated with Low-Dose Methotrexate Using Machine Learning

An accurate prediction of the hepatotoxicity associated with low-dose methotrexate can provide evidence for a reasonable treatment choice. This study aimed to develop a machine learning-based prediction model to predict hepatotoxicity associated with low-dose methotrexate and explore the associated risk factors. Eligible patients with immune system disorders, who received low-dose methotrexate at West China Hospital between 1 January 2018, and 31 December 2019, were enrolled. A retrospective review of the included patients was conducted. Risk factors were selected from multiple patient characteristics, including demographics, admissions, and treatments. Eight algorithms, including eXtreme Gradient Boosting (XGBoost), AdaBoost, CatBoost, Gradient Boosting Decision Tree (GBDT), Light Gradient Boosting Machine (LightGBM), Tree-based Pipeline Optimization Tool (TPOT), Random Forest (RF), and Artificial Neural Network (ANN), were used to establish the prediction model. A total of 782 patients were included, and hepatotoxicity was detected in 35.68% (279/782) of the patients. The Random Forest model with the best predictive capacity was chosen to establish the prediction model (receiver operating characteristic curve 0.97, accuracy 64.33%, precision 50.00%, recall 32.14%, and F1 39.13%). Among the 15 risk factors, the highest score was a body mass index of 0.237, followed by age (0.198), the number of drugs (0.151), and the number of comorbidities (0.144). These factors demonstrated their importance in predicting hepatotoxicity associated with low-dose methotrexate. Using machine learning, this novel study established a predictive model for low-dose methotrexate-related hepatotoxicity. The model can improve medication safety in patients taking methotrexate in clinical practice

Validating the Chinese geriatric trigger tool and analyzing adverse drug event associated risk factors in elderly Chinese patients: A retrospective review.

OBJECTIVE:The aim was to evaluate the performance of the initial Chinese geriatric trigger tool to detect adverse drug events (ADEs) in Chinese older patients, to attempt to shorten this list for improving the efficiency of the trigger tool, and to study the incidence and characteristics of ADEs in this population. METHODS:A sample of 25 cases was randomly selected per half a month from eligible patients who aged 60 years and older, hospitalized more than 24 hours, and discharged or died between January 1, 2015 and December 31, 2017 in West China hospital. A two-stage retrospective chart review of the included inpatients were conducted. ADEs were detected using a list of 42 triggers previously selected by an expert panel by means of a Delphi method. The number of triggers identified and ADEs detected were recorded and the positive predictive value (PPV) of each trigger was calculated to select the most efficient triggers. Several variables were recorded, including age, sex, number of diseases, length of hospital stay and so on, to analyze the risk factor of ADEs. RESULTS:Among 1800 patients, 1646 positive triggers and 296 ADEs were detected in 234 (13.00%) patients. Older patients who were younger, had more medications, longer stays or more admission, and did not experience surgical operation more likely experienced ADEs. Triggers with PPV less than 5% were eliminated, which resulted in the upgraded version of Chinese geriatric trigger tool of 20 triggers with a PPV of 28.50%. This upgraded tool accounted for 99.66% of all ADEs detected. CONCLUSIONS:The upgraded version of Chinese geriatric trigger tool was an efficient tool for identifying ADEs in Chinese older patients. Future, the trigger tool could be incorporated into routine screen systems to provide real-time identification of ADEs, thereby enabling timely clinical interventions