New Family of Benzimidazole-Based Chitosan Derivatives against Penicillium expansum.

Penicillium expansum is the major fungus that causes blue mold and produces patulin, threatening human health. Due to health and environmental pollution concerns, chitosan (CS) has attracted more and more attention as a safer alternative to synthetic fungicides for the control of blue mold. In the present study, four different benzimidazole groups were introduced onto CS by the acylation reaction to obtain benzimidazole-based chitosan derivatives (R1b-R4b). After being well-characterized with Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis spectra), and nuclear magnetic resonance (NMR), their antifungal activities against P. expansum were screened. Results showed that the inhibitory effects of chitosan derivatives against the pathogen were significantly correlated with chitosan derivatives' concentration and their structures. R4b was shown as optimum with good solubility and antifungal activity with a minimum inhibitory concentration (MIC) value of 0.5 mg/mL and a minimum fungicidal concentration (MFC) value of 2.0 mg/mL. The remarkable antifungal efficiency of R4b against P. expansum was further demonstrated in terms of spore germination, mycelial growth, patulin production, and the preliminary antifungal mechanism. R4b exhibited significant inhibition of patulin production, while its antifungal mechanism was revealed by destroying cell membrane integrity and inducing membrane depolarization. Furthermore, R4b treatment could significantly reduce the incidence of blue mold rot in apple fruit, and the MTT assay showed the nontoxicity of R4b against Raw 264.7, HBZY-1, and Caco-2 cells. Altogether, these results indicate that it is promising to be used as a fruit preservative in the future.

Comparative efficacy and hematologic safety of different dosages of JAK inhibitors in the treatment of myelofibrosis: a network meta-analysis.

Background: Myelofibrosis (MF) is a myeloproliferative neoplasm characterized by bone marrow fibrosis associated with substantial morbidity and mortality. The therapeutic landscape for MF has advanced with the development of Janus kinase inhibitors (JAKis) like ruxolitinib (RUX), fedratinib (FED), pacritinib (PAC), and momelotinib (MMB), aiming to alleviate symptoms and enhance patient comfort. Methods: A network meta-analysis was conducted to assess the efficacy and safety of eleven JAKi treatment regimens across nine randomized controlled trials (RCTs) with a total of 2340 participants. Outcomes were evaluated in terms of spleen volume reduction (SVR), total symptom score reduction (TSSR), hematological safety profiles, and overall survival (OS). Results: RUX and MMB were superior in achieving SVR and TSSR, with significant dose-response relationships observed. PAC and MMB were associated with a decreased risk of grade 3/4 anemia and thrombocytopenia compared to other JAKis. However, no substantial benefits in OS were observed with newer JAKis compared to RUX. The poorer OS outcomes with certain PAC dosages were likely influenced by baseline patient characteristics, particularly severe cytopenias. Conclusion: The introduction of JAKis significantly changed the treatment of MF. This meta-analysis reaffirms the core role of RUX and positions MMB as a potentially powerful alternative for treating symptoms and reducing spleen size. Meanwhile, MMB and PAC have a positive effect on anemia in MF while FED is more tolerable for patients with thrombocytopenia. However, it should be noted that these results are influenced by baseline patient characteristics, particularly cytopenias, which affects both management and overall survival. Therefore, there is an urgent need for personalized dosing strategies to optimize the balance between efficacy and safety, with careful consideration of patient-specific factors. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023424179.

Development and external validation of a risk prediction model for depression in patients with coronary heart disease.

BACKGROUND: Depression is an independent risk factor for adverse outcomes of coronary heart disease (CHD). This study aimed to develop a depression risk prediction model for CHD patients. METHODS: This study utilized data from the National Health and Nutrition Examination Survey (NHANES). In the training set, reference literature, logistic regression, LASSO regression, optimal subset algorithm, and machine learning random forest algorithm were employed to screen prediction variables, respectively. The optimal prediction model was selected based on the C-index, Net Reclassification Improvement (NRI), and Integrated Discrimination Improvement (IDI). A nomogram for the optimal prediction model was constructed. 3 external validations were performed. RESULTS: The training set comprised 1375 participants, with a depressive symptoms prevalence of 15.2 %. The optimal prediction model was constructed using predictors obtained from optimal subsets algorithm (C-index = 0.774, sensitivity = 0.751, specificity = 0.685). The model includes age, gender, education, marriage, diabetes, tobacco use, antihypertensive drugs, high-density lipoprotein cholesterol (HDLC), and aspartate aminotransferase (AST). The model demonstrated consistent discrimination ability, accuracy, and clinical utility across the 3 external validations. LIMITATIONS: The applicable population of the model is CHD patients. And the clinical benefits of interventions based on the prediction results are still unknown. CONCLUSION: We developed a depression risk prediction model for CHD patients, which was presented in the form of a nomogram for clinical application.

Effects of tranexamic acid preconditioning on the incidence of postpartum haemorrhage in vaginal deliveries with identified risk factors in China: a prospective, randomized, open-label, blinded endpoint trial.

OBJECTIVE: This study aimed to evaluate the effects of tranexamic acid (TXA) in preventing postpartum haemorrhage (PPH) among women with identified risk factors for PPH undergoing vaginal delivery in China. METHODS: This prospective, randomized, open-label, blinded endpoint (PROBE) trial enrolled 2258 women with one or more risk factors for PPH who underwent vaginal delivery. Participants were randomly assigned in a 1:1 ratio to receive an intravascular infusion of 1 g TXA or a placebo immediately after the delivery of the infant. The primary outcome assessed was the incidence of PPH, defined as blood loss ≥500 mL within 24 h after delivery, while severe PPH was considered as a secondary outcome and defined by total blood loss ≥1000 mL within 24 h. RESULTS: 2245 individuals (99.4%) could be followed up to their primary outcome. PPH occurred in 186 of 1128 women in the TXA group and in 215 of 1117 women in the placebo group (16.5% vs. 19.2%; RR, 0.86; 95% CI, 0.72 to 1.02; p = 0.088). Regarding secondary outcomes related to efficacy, women in the TXA group had a significant lower rate of severe PPH than those in the placebo group (2.7% vs. 5.6%; RR, 0.49; 95% CI, 0.32 to 0.74; p = 0.001; adjusted p = 0.002). Similarly, there was a significant reduction in the use of additional uterotonic agents (7.8% vs. 15.6%; RR, 0.50; 95% CI, 0.39 to 0.63; p < 0.001; adjusted p = 0.001). No occurrence of thromboembolic events and maternal deaths were reported in both groups within 30 days after delivery. CONCLUSIONS: In total population with risk factors for PPH, the administration of TXA following vaginal delivery did not result in a statistically significant reduction in the incidence of PPH compared to placebo; however, it was associated with a significantly lower incidence of severe PPH.

Prophylactic administration of TXA did not yield a statistically significant reduction in the incidence of PPH among women with risk factors in vaginal deliveries.Prophylactic use of TXA may help to reduce the incidence of severe PPH.

The OsSRO1c-OsDREB2B complex undergoes protein phase transition to enhance cold tolerance in rice.

Cold stress is one of the major abiotic stress factors affecting rice growth and development, leading to significant yield loss in the context of global climate change. Exploring natural variants that confer cold resistance and the underlying molecular mechanism responsible for this is the major strategy to breed cold tolerant rice varieties. Here, we show that the natural variations of a SIMILAR to RCD ONE (SRO) gene, OsSRO1c, confer cold tolerance in rice at both seedling and booting stages. OsSRO1c possesses intrinsic liquid-liquid phase separation ability in vivo and in vitro and recruits an AP2/ERF transcription factor and positive cold stress regulator, OsDREB2B, into its biomolecular condensates in the nucleus, resulting in elevated transcriptional activity of OsDREB2B. The OsSRO1c-OsDREB2B complex directly responds to low temperature through dynamic phase transitions and regulates key cold response genes, including COLD1. Furthermore, introgression of an elite haplotype of OsSRO1c into a cold susceptible indica rice significantly increases its cold resistance. Collectively, our work reveals a novel cold tolerance regulatory module in rice and provides promising genetic targets for molecular breeding of cold-tolerant rice varieties.

Deep Reconstruction of Ruthenate Perovskite Oxide Enables Efficient pH-Universal Hydrogen Evolution Reaction.

Designing highly efficient, stable, and pH-universal perovskites for hydrogen evolution reaction (HER) is urgently needed yet remains a grand challenge. Herein, a titanium-containing strontium ruthenate (SrTi0.5Ru0.5O3, STRO) is developed as an excellent HER electrocatalyst in a wide pH range. The introduction of Ti into SrRuO3 significantly reduces the size of STRO, endowing with a high reactivity that facilitates a deep surface-reconstruction during HER. Furthermore, Sr2+ leaching triggered reconstruction leads to STRO breaking into tiny nanoparticles accompanied by high-valence ruthenium (Ru) species reducing to metallic Ru. The generated active species, increased accessible sites, and improved electrical conductivity greatly boost HER. The reconstructed STRO displays remarkable HER activities with exceptional low overpotentials of 18, 24, and 55 mV at 10 mA cm-2 in 1 m KOH, 0.5 m H2SO4, and 1 m PBS, respectively, surpassing most perovskites reported previously and comparable to or even outperforming that of commercial Pt/C. Moreover, the STRO exhibits excellent stabilities over 200 h in alkaline and acidic media, superior to that of Pt/C. This work not only provides insights into structure reconstruction of perovskites during HER, but also opens new perspectives for developing high-efficiency and pH-universal electrocatalysts for future energy applications.

Enhancing aqueous zinc-ion energy storage performance with ion-mediating carbon quantum dots-modified separators regulating zinc deposition behavior.

Aqueous zinc-ion batteries (AZIBs) hold promising applications owing to their safety, cost-effectiveness, and competitive capacity. However, issues such as zinc dendritic formation and side reactions severely impede their practical viability. Utilizing carbon quantum dots (CQDs) to modify cheap, tenacious, and highly hydrophilic filter paper (FP) as separator effectively improves the electrochemical performance of zinc ion energy storage systems. The structured arrangement of CQDs redistributes zinc ion transport and induces uniform zinc icon deposition, thereby improving zinc ion reaction kinetics. Moreover, the rich functional groups on the surface of CQDs readily form hydrogen bonds with active H2O, further inhibiting corrosion reactions. With the assistance of CQDs, the FP-CQDs separator maintains high ionic conductivity and a high zinc-ion transference number, ensuring dendrite-free and corrosion-resistant operation with high coulombic efficiency and a prolonged lifespan of 1200 h at 1 mA cm-2. Zn//AC hybrid capacitors incorporating FP-CQDs separator demonstrate superior capacity retention compared to those using FP separator alone, with a high capacity retention after 600 cycles at 1 A/g, while Zn//V2O5 full batteries also exhibit excellent cycling stability. Given these findings, this study presents a new composite separator for advanced aqueous zinc-ion energy storage systems.

Prolonged second stage of labor and risk of postpartum hemorrhage in nullipara with epidural anesthesia and vaginal delivery: A cohort study with propensity score analysis.

OBJECTIVE: To conduct an analysis using propensity score methods, exploring the association between a prolonged second stage (>3 h) and the risk of postpartum hemorrhage (PPH) in a diverse population. METHODS: We conducted a prospective cohort study involving nullipara with epidural anesthesia and vaginal delivery, aged ≥18 years, presenting cephalically, and with a gestational age (GA) of ≥24 weeks at a tertiary maternity hospital in China (chictr.org.cn identifier: ChiCTR2200063094). Women undergoing emergency cesarean section in labor were excluded. The primary outcome was PPH, with secondary outcomes including severe postpartum hemorrhage and blood transfusion. We employed propensity score overlap weighting to analyze the association between prolonged second stage labor and PPH. RESULTS: The study included 3643 nullipara with epidural anesthesia, comprising 77 with a second stage of labor >3 h and 3566 with a second stage ≤3 h. Utilizing propensity score overlap weighting, there were no significant differences observed between the two groups regarding the risk of PPH (29.87% in >3 h group vs 17.64% in ≤3 h group; weighted odds ratio 1.01; 95% CI: 0.51-2.02). Subgroup interaction tests for PPH were not significant for assisted vaginal delivery, induction of labor, macrosomia, third-/fourth-degree perineal laceration, GA >41 weeks, twin pregnancies, episiotomy and GA >37 weeks. Sensitivity analysis did not reveal significant differences. CONCLUSION: This study did not find evidence supporting an increased risk of PPH associated with a second stage of labor lasting >3 h in our population, providing additional evidence for clinical practice.

HO-1 activation contributes to cadmium-induced ferroptosis in renal tubular epithelial cells via increasing the labile iron pool and promoting mitochondrial ROS generation.

Cadmium (Cd), a prevalent environmental contaminant, has attracted widespread attention due to its serious health hazards. Ferroptosis is a form of iron-dependent oxidative cell death that contributes to the development of various kidney diseases. However, the mechanisms underlying the occurrence of ferroptosis in Cd-induced renal tubular epithelial cells (TECs) have not been fully elucidated. Hereby, both in-vitro and in-vivo experiments were established to elucidate this issue. In this study, we found that Cd elicited accumulation of lipid peroxides due to intracellular ferrous ion (Fe2+) overload and glutathione depletion, contributing to ferroptosis. Inhibition of ferroptosis via chelation of Fe2+ or reduction of lipid peroxidation can significantly mitigate Cd-induced cytotoxicity. Renal transcriptome analysis revealed that the activation of heme oxygenase 1 (HO-1) was closely related to ferroptosis in Cd-induced TECs injury. Cd-induced ferroptosis and resultant TECs injury are significantly alleviated due to HO-1 inhibition, demonstrating the crucial role of HO-1 in Cd-triggered ferroptosis. Further studies showed that accumulation of lipid peroxides due to iron overload and mitochondrial ROS (mtROS) generation was responsible for HO-1-triggered ferroptosis in Cd-induced cytotoxicity. In conclusion, the current study demonstrates that excessively upregulating HO-1 promotes iron overload and mtROS overproduction to trigger ferroptosis in Cd-induced TECs injury, highlighting that targeting HO-1-mediated ferroptosis may provide new ideas for preventing Cd-induced nephrotoxicity.

Knowledge, Attitude and Practice of Radiologists Regarding Artificial Intelligence in Medical Imaging.

Purpose: This study aimed to investigate the knowledge, attitudes, and practice (KAP) of radiologists regarding artificial intelligence (AI) in medical imaging in the southeast of China. Methods: This cross-sectional study was conducted among radiologists in the Jiangsu, Zhejiang, and Fujian regions from October to December 2022. A self-administered questionnaire was used to collect demographic data and assess the KAP of participants towards AI in medical imaging. A structural equation model (SEM) was used to analyze the relationships between KAP. Results: The study included 452 valid questionnaires. The mean knowledge score was 9.01±4.87, the attitude score was 48.96±4.90, and 75.22% of participants actively engaged in AI-related practices. Having a master's degree or above (OR=1.877, P=0.024), 5-10 years of radiology experience (OR=3.481, P=0.010), AI diagnosis-related training (OR=2.915, P<0.001), and engaging in AI diagnosis-related research (OR=3.178, P<0.001) were associated with sufficient knowledge. Participants with a junior college degree (OR=2.139, P=0.028), 5-10 years of radiology experience (OR=2.462, P=0.047), and AI diagnosis-related training (OR=2.264, P<0.001) were associated with a positive attitude. Higher knowledge scores (OR=5.240, P<0.001), an associate senior professional title (OR=4.267, P=0.026), 5-10 years of radiology experience (OR=0.344, P=0.044), utilizing AI diagnosis (OR=3.643, P=0.001), and engaging in AI diagnosis-related research (OR=6.382, P<0.001) were associated with proactive practice. The SEM showed that knowledge had a direct effect on attitude (ß=0.481, P<0.001) and practice (ß=0.412, P<0.001), and attitude had a direct effect on practice (ß=0.135, P<0.001). Conclusion: Radiologists in southeastern China hold a favorable outlook on AI-assisted medical imaging, showing solid understanding and enthusiasm for its adoption, despite half lacking relevant training. There is a need for more AI diagnosis-related training, an efficient standardized AI database for medical imaging, and active promotion of AI-assisted imaging in clinical practice. Further research with larger sample sizes and more regions is necessary.

Value of improved nursing measures and enhanced nursing management to reduce the occurrence of adverse events in pediatric infusion.

BACKGROUND: Intravenous infusion is a common method of drug administration in clinical practice. Errors in any aspect of the infusion process, from the verification of medical orders, preparation of the drug solution, to infusion by nursing staff, may cause adverse infusion events. AIM: To analyzed the value of improving nursing measures and enhancing nursing management to reduce the occurrence of adverse events in pediatric infusion. METHODS: The clinical data of 130 children who received an infusion in the pediatric department of our hospital from May 2020 to May 2021 were analyzed and divided into two groups according to the differences in nursing measures and nursing management: 65 patients in the control group received conventional nursing and nursing management interventions, while 65 patients in the observation group received improved nursing measure interventions and enhanced nursing management. The occurrence of adverse events, compliance of children, satisfaction of children's families, and complaints regarding the transfusion treatment were recorded in both groups. RESULTS: The incidence of fluid extravasation and infusion set dislodgement in the observation group were 3.08% and 1.54%, respectively, which were significantly lower than 12.31% and 13.85% in the control group (P < 0.05), while repeated punctures and medication addition errors in the observation group were 3.08% and 0.00%, respectively, which were lower than 9.23% and 3.08% in the control group, but there was no significant difference (P > 0.05). The compliance rate of children in the observation group was 98.46% (64/65), which was significantly higher than 87.69% (57/65) in the control group, and the satisfaction rate of children's families was 96.92% (63/65), which was significantly higher than 86.15% (56/65) in the control group (P < 0.05). The observation group did not receive any complaints from the child's family, whereas the control group received four complaints, two of which were due to the crying of the child caused by repeated punctures, one due to the poor attitude of the nurse, and one due to medication addition errors, with a cumulative complaint rate of 6.15%. The cumulative complaint rate of the observation group was significantly lower than that of the control group (P < 0.05). CONCLUSION: Improving nursing measures and enhancing nursing management can reduce the incidence of fluid extravasation and infusion set dislodgement in pediatric patients, improve children's compliance and satisfaction of their families, and reduce family complaints.

Covalent Organic Frameworks Meet Titanium Oxide.

In order to expand the applicability of materials and improve their performance, the combined use of different materials has increasingly been explored. Among these materials, inorganic-organic hybrid materials often exhibit properties superior to those of single materials. Covalent organic frameworks (COFs) are famous crystalline porous materials constructed by organic building blocks linked by covalent bonds. In recent years, the combination of COFs with other materials has shown interesting properties in diverse fields, and the composite materials of COFs and TiO2 have been investigated more and more. These two outstanding materials are combined through covalent bonding, physical mixing, and other methods and exhibit excellent performance in various fields, including photocatalysis, electrocatalysis, sensors, separation, and energy storage and conversion. In this Review, the current preparation methods and applications of COF-TiO2 hybrid materials are introduced in detail, and their future development and possible problems are discussed and prospected, which is of great significance for related research. It is believed that these interesting hybrid materials will show greater application value as research progresses.

Complex heterozygous mutations in hereditary spherocytosis: A case report.

BACKGROUND: The aim of this study was to investigate the complex heterozygous mutations of ANK1 and SPTA1 in the same individual and improve our understanding of hereditary spherocytosis (HS) in children. We also hope to promote the application of gene detection technology in children with HS, with the goals of identifying more related gene mutations, supporting the acquisition of improved molecular genetic information to further reveal the pathogenesis of HS in children, and providing important guidance for the diagnosis, treatment, and prevention of HS in children. CASE SUMMARY: A 1-year and 5-month-old patient presented jaundice during the neonatal period, mild anemia 8 months later, splenic enlargement at 1 year and 5 months, and brittle red blood cell permeability. Genetic testing was performed on the patient, their parents, and sister. Swiss Model software was used to predict the protein structure of complex heterozygous mutations in ANK1 and SPTA1. Genetic testing revealed that the patient harbored a new mutation in the ANK1 gene from the father and a mutation in the SPTA1 gene from the mother. Combined with the clinical symptoms of the children, it is suggested that the newly discovered complex heterozygous mutations of ANK1 and SPTA1 may be the cause, providing important guidance for revealing the pathogenesis, diagnosis, treatment, and promotion of gene detection technology in children with HS. CONCLUSION: This case involves an unreported complex heterozygous mutation of ANK1 and SPTA1, which provides a reference for exploring HS.

Increased ecological land and atmospheric CO2 dominate the growth of ecosystem carbon sinks under the regulation of environmental conditions in national key ecological function zones in China.

Increased ecological land (IEL) such as forests and grasslands can greatly enhance ecosystem carbon sinks. Understanding the mechanisms for the magnitude of IEL-induced ecosystem carbon sinks is crucial for achieving carbon neutrality. We estimated the impact of IEL, specifically the increase in forests and grasslands, as well as global changes including atmospheric CO2 concentration, nitrogen deposition, and climate change on net ecosystem productivity (NEP) in National Key Ecological Function Zones (NKEFZs) in China using a calibrated ecological process model. The NEP in NKEFZs in China was calculated to be 119.4 Tg C yr-1, showing an increase of 42.6 Tg C yr-1 from 2001 to 2021. Compared to the slight contributions of climate change (-8.0%), nitrogen deposition (11.5%), and reduction in ecological land (-3.5%), the increase in NEP was primarily attributed to CO2 (66.5%) and IEL (33.5%). Moreover, the effect of IEL (14.8 Tg C yr-1) surpassed that of global change (13.1 Tg C yr-1) in the land use change zone. The IEL-induced NEP is significantly associated with CO2 fertilization, regulated by precipitation and nitrogen deposition. The high values of IEL-induced NEP occurred in areas with precipitation exceeding 800 mm and nitrogen deposition exceeding 25 kg N ha-1 yr-1. We recommend prioritizing the expansion of ecological land in areas with sufficient water and nutrients to enhance CO2 fertilization, while avoiding increasing ecological land in regions facing unfavorable climate change conditions. This study serves as a foundation for comprehending the NEP response to ecological restoration and global change.

Advances in pH Sensing: From Traditional Approaches to Next-Generation Sensors in Biological Contexts.

pH has been considered one of the paramount factors in bodily functions because most cellular tasks exclusively rely on precise pH values. In this context, the current techniques for pH sensing provide us with the futuristic insight to further design therapeutic and diagnostic tools. Thus, pH-sensing (electrochemically and optically) is rapidly evolving toward exciting new applications and expanding researchers' interests in many chemical contexts, especially in biomedical applications. The adaptation of cutting-edge technology is subsequently producing the modest form of these biosensors as wearable devices, which are providing us the opportunity to target the real-time collection of vital parameters, including pH for improved healthcare systems. The motif of this review is to provide insight into trending tech-based systems employed in real-time or in-vivo pH-responsive monitoring. Herein, we briefly go through the pH regulation in the human body to help the beginners and scientific community with quick background knowledge, recent advances in the field, and pH detection in real-time biological applications. In the end, we summarize our review by providing an outlook; challenges that need to be addressed, and prospective integration of various pH in vivo platforms with modern electronics that can open new avenues of cutting-edge techniques for disease diagnostics and prevention.

Novel biomarkers for prediction of atonic postpartum hemorrhage among 'low-risk' women in labor.

Background: Postpartum hemorrhage (PPH) is the primary cause of maternal mortality globally, with uterine atony being the predominant contributing factor. However, accurate prediction of PPH in the general population remains challenging due to a lack of reliable biomarkers. Methods: Using retrospective cohort data, we quantified 48 cytokines in plasma samples from 40 women diagnosed with PPH caused by uterine atony. We also analyzed previously reported hemogram and coagulation parameters related to inflammatory response. The least absolute shrinkage and selection operator (LASSO) and logistic regression were applied to develop predictive models. Established models were further evaluated and temporally validated in a prospective cohort. Results: Fourteen factors showed significant differences between the two groups, among which IL2Rα, IL9, MIP1ß, TNFß, CTACK, prenatal Hb, Lymph%, PLR, and LnSII were selected by LASSO to construct predictive model A. Further, by logistic regression, model B was constructed using prenatal Hb, PLR, IL2Rα, and IL9. The area under the curve (AUC) values of model A in the training set, internal validation set, and temporal validation set were 0.846 (0.757-0.934), 0.846 (0.749-0.930), and 0.875 (0.789-0.961), respectively. And the corresponding AUC values for model B were 0.805 (0.709-0.901), 0.805 (0.701-0.894), and 0.901 (0.824-0.979). Decision curve analysis results showed that both nomograms had a high net benefit for predicting atonic PPH. Conclusion: We identified novel biomarkers and developed predictive models for atonic PPH in women undergoing "low-risk" vaginal delivery, providing immunological insights for further exploration of the mechanism underlying atonic PPH.