Systematic proteome-wide Mendelian randomization using the human plasma proteome to identify therapeutic targets for lung adenocarcinoma.

BACKGROUND: Lung adenocarcinoma (LUAD) is the predominant histological subtype of lung cancer and the leading cause of cancer-related mortality. Identifying effective drug targets is crucial for advancing LUAD treatment strategies. METHODS: This study employed proteome-wide Mendelian randomization (MR) and colocalization analyses. We collected data on 1394 plasma proteins from a protein quantitative trait loci (pQTL) study involving 4907 individuals. Genetic associations with LUAD were derived from the Transdisciplinary Research in Cancer of the Lung (TRICL) study, including 11,245 cases and 54,619 controls. We integrated pQTL and LUAD genome-wide association studies (GWASs) data to identify candidate proteins. MR utilizes single nucleotide polymorphisms (SNPs) as genetic instruments to estimate the causal effect of exposure on outcome, while Bayesian colocalization analysis determines the probability of shared causal genetic variants between traits. Our study applied these methods to assess causality between plasma proteins and LUAD. Furthermore, we employed a two-step MR to quantify the proportion of risk factors mediated by proteins on LUAD. Finally, protein-protein interaction (PPI) analysis elucidated potential links between proteins and current LUAD medications. RESULTS: We identified nine plasma proteins significantly associated with LUAD. Increased levels of ALAD, FLT1, ICAM5, and VWC2 exhibited protective effects, with odds ratios of 0.79 (95% CI 0.72-0.87), 0.39 (95% CI 0.28-0.55), 0.91 (95% CI 0.72-0.87), and 0.85 (95% CI 0.79-0.92), respectively. Conversely, MDGA2 (OR, 1.13; 95% CI 1.08-1.19), NTM (OR, 1.12; 95% CI 1.09-1.16), PMM2 (OR, 1.35; 95% CI 1.18-1.53), RNASET2 (OR, 1.15; 95% CI 1.08-1.21), and TFPI (OR, 4.58; 95% CI 3.02-6.94) increased LUAD risk. Notably, none of the nine proteins showed evidence of reverse causality. Bayesian colocalization indicated that RNASET2, TFPI, and VWC2 shared the same variant with LUAD. Furthermore, NTM and FLT1 demonstrated interactions with targets of current LUAD medications. Additionally, FLT1 and TFPI are currently under evaluation as therapeutic targets, while NTM, RNASET2, and VWC2 are potentially druggable. These findings shed light on LUAD pathogenesis, highlighting the tumor-promoting effects of RNASET2, TFPI, and NTM, along with the protective effects of VWC2 and FLT1, providing a significant biological foundation for future LUAD therapeutic targets. CONCLUSIONS: Our proteome-wide MR analysis highlighted RNASET2, TFPI, VWC2, NTM, and FLT1 as potential drug targets for further clinical investigation in LUAD. However, the specific mechanisms by which these proteins influence LUAD remain elusive. Targeting these proteins in drug development holds the potential for successful clinical trials, providing a pathway to prioritize and reduce costs in LUAD therapeutics.

QTL Mapping of Soybean (Glycine max) Vine Growth Habit Trait.

The vine growth habit (VGH) is a notable property of wild soybean plants that also holds a high degree of importance in domestication as it can preclude using these wild cultivars for breeding and improving domesticated soybeans. Here, a bulked segregant analysis (BSA) approach was employed to study the genetic etiology of the VGH in soybean plants by integrating linkage mapping and population sequencing approaches. To develop a recombinant inbred line (RIL) population, the cultivated Zhongdou41 (ZD41) soybean cultivar was bred with ZYD02787, a wild soybean accession. The VGH status of each line in the resultant population was assessed, ultimately leading to the identification of six and nine QTLs from the BSA sequencing of the F4 population and F6-F8 population sequence mapping, respectively. One QTL shared across these analyzed generations was detected on chromosome 19. Three other QTLs detected by BSA-seq were validated and localized to the 90.93 kb, 2.9 Mb, and 602.08 kb regions of chromosomes 6 and 13, harboring 14, 53, and 4 genes, respectively. Three consistent VGH-related QTLs located on chromosomes 2 and 19 were detected in a minimum of three environments, while an additional six loci on chromosomes 2, 10, 13, and 18 were detected in at least two environments via ICIM mapping. Of all the detected loci, five had been reported previously whereas seven represent novel QTLs. Together, these data offer new insights into the genetic basis of the VGH in soybean plants, providing a rational basis to inform the use of wild accessions in future breeding efforts.

Influence of circulation types on temporal and spatial variations of ozone in Beijing.

This study analyzes the impact of circulation types (CTs) on ozone (O3) pollution in Beijing. The easterly high-pressure (SWW) circulation occurred most frequently (30%; 276 day), followed by northwesterly high-pressure (AN) circulation (24.3%; 224 day). The SWW type had the highest O3 anomaly of +17.28 µg/m3, which was caused by excellent photochemical reactions, poor diffusion ability and regional transport. Due to the higher humidity and precipitation in the low-pressure type (C), the O3 increase (+8.02 µg/m3) was less than that in the SWW type. Good diffusion/wet deposition and weak formation ability contributed to O3 decrease in AN (-12.54 µg/m3) and northerly high-pressure (ESN) CTs (-12.26 µg/m3). The intra-area transport of O3 was significant in polluted circulations (SWW- and C-CTs). In addition, higher temperature, radiation and less rainfall also contributed to higher O3 in northern Beijing under the SWW type. For the clean CTs (AN and ESN CTs), precursor amount and intra-area transport played a dominant role in O3 distribution. Under the northeasterly low-pressure CT, better formation conditions and higher precursor amount combined with the intra-area southerly transport to cause higher O3 values in the south than in the north. The higher O3 in the northwestern area under the northeasterly high-pressure type was influenced by weaker titration loss and high O3 concentration in previous day. Annual variation in the CTs contributed up to 86.1% of the annual variation in O3. About 78%-83% of the diurnal variation in O3 resulted from local meteorological factors.

Dihydroartemisinin breaks the positive feedback loop of YAP1 and GLUT1-mediated aerobic glycolysis to boost the CD8+ effector T cells in hepatocellular carcinoma.

Aerobic glycolysis is a hallmark of hepatocellular carcinoma (HCC). Dihydroartemisinin (DHA) exhibits antitumor activity towards liver cancer. Our previous studies have shown that DHA inhibits the Warburg effect in HCC cells. However, the mechanism still needs to be clarified. Our study aimed to elucidate the interaction between YAP1 and GLUT1-mediated aerobic glycolysis in HCC cells and focused on the underlying mechanisms of DHA inhibiting aerobic glycolysis in HCC cells. In this study, we confirmed that inhibition of YAP1 expression lowers GLUT1-mediated aerobic glycolysis in HCC cells and enhances the activity of CD8+T cells in the tumor niche. Then, we found that DHA was bound to cellular YAP1 in HCC cells. YAP1 knockdown inhibited GLUT1-mediated aerobic glycolysis, whereas YAP1 overexpression promoted GLUT1-mediated aerobic glycolysis in HCC cells. Notably, liver-specific Yap1 knockout by AAV8-TBG-Cre suppressed HIF-1α and GLUT1 expression in tumors but not para-tumors in DEN/TCPOBOP-induced HCC mice. Even more crucial is that YAP1 forms a positive feedback loop with GLUT1-mediated aerobic glycolysis, which is associated with HIF-1α in HCC cells. Finally, DHA reduced GLUT1-aerobic glycolysis in HCC cells through YAP1 and prevented the binding of YAP1 and HIF-1α. Collectively, our study revealed the mechanism of DHA inhibiting glycolysis in HCC cells from a perspective of a positive feedback loop involving YAP1 and GLUT1 mediated-aerobic glycolysis and provided a feasible therapeutic strategy for targeting enhanced aerobic glycolysis in HCC.

QTL mapping and genomic selection of stem and branch diameter in soybean (Glycine max L.).

Introduction: Soybean stem diameter (SD) and branch diameter (BD) are closely related traits, and genetic clarification of SD and BD is crucial for soybean breeding. Methods: SD and BD were genetically analyzed by a population of 363 RIL derived from the cross between Zhongdou41 (ZD41) and ZYD02878 using restricted two-stage multi-locus genome-wide association, inclusive composite interval mapping, and three-variance component multi-locus random SNP effect mixed linear modeling. Then candidate genes of major QTLs were selected and genetic selection model of SD and BD were constructed respectively. Results and discussion: The results showed that SD and BD were significantly correlated (r = 0.74, P < 0.001). A total of 93 and 84 unique quantitative trait loci (QTL) were detected for SD and BD, respectively by three different methods. There were two and ten major QTLs for SD and BD, respectively, with phenotypic variance explained (PVE) by more than 10%. Within these loci, seven genes involved in the regulation of phytohormones (IAA and GA) and cell proliferation and showing extensive expression of shoot apical meristematic genes were selected as candidate genes. Genomic selection (GS) analysis showed that the trait-associated markers identified in this study reached 0.47-0.73 in terms of prediction accuracy, which was enhanced by 6.56-23.69% compared with genome-wide markers. These results clarify the genetic basis of SD and BD, which laid solid foundation in regulation gene cloning, and GS models constructed could be potentially applied in future breeding programs.

Dihydroartemisinin breaks the immunosuppressive tumor niche during cisplatin treatment in Hepatocellular carcinoma.

OBJECTIVE: Hepatocellular carcinoma, characterized by high mortality rates, often exhibits limited responsiveness to conventional treatments such as surgery, radiotherapy, and chemotherapy. Therefore, identifying a sensitizer for cisplatin has become crucial. Dihydroartemisinin, known for its potent role of tumor treatment, arises as a prospective candidate for cisplatin sensitization in clinical settings. METHODS: A mouse model of liver tumor was established through chemical induction of DEN/TCPOBOP. Upon successful model establishment, ultrasound was employed to detect tumors, Hematoxylin and eosin staining was conducted for observation of liver tissue pathology, and ELISA was utilized to assess cytokine changes (IFN-γ, IL-2, IL-4, IL-10, TGF-ß, IL-1ß, CCL2, and CCL21) in peripheral blood, para-tumor tissues, and tumor tissues. The infiltration of CD8+T cells and macrophages in tumor tissue sections was detected by immunofluorescence. RESULTS: Dihydroartemisinin combined with cisplatin obviously restrained the growth of liver tumors in mice and improved the weight and spleen loss caused by cisplatin. Cisplatin treatment of liver tumor mice increased the content of CCL2 and the number of macrophages in tumor tissues and promoted the formation of an immunosuppressive microenvironment. The combination therapy decreased the content of TGF-ß in tumor tissues while increasing CCL2 levels in para-tumor tissues. Both combination therapy and cisplatin alone increased the number of CD8+T cells in tumor tissue, but there was no difference between them. CONCLUSION: Dihydroartemisinin combined with cisplatin obviously prevented the deterioration of liver tumor in hepatocellular carcinoma mice and improve the therapeutic effect of cisplatin by improving the immunosuppressive microenvironment induced by cisplatin. Our findings provide a theoretical basis for considering dihydroartemisinin as an adjuvant drug for cisplatin in the treatment of hepatocellular carcinoma in the future.

Research Progress of Warburg Effect in Hepatocellular Carcinoma.

The Warburg effect, also called aerobic glycolysis, refers to tumor cells that metabolize glucose through glycolysis even in the presence of oxygen. This rapid breakdown of glucose fuels the fast development, growth, and migration of tumor cells. Lactate, the final product of aerobic glycolysis, contributes to an acidic environment within the tumor, promoting the formation of an immunosuppressive microenvironment and accelerating tumor progression by impeding anti-tumor immunity. Numerous studies have confirmed the critical role of aerobic glycolysis in the occurrence and development of hepatocellular carcinoma by influencing tumor cells proliferation, invasion, metastasis, apoptosis, immune escape, angiogenesis, and more. Clinical trials have shown that inhibitors of rate-limiting enzymes in the glycolysis pathway can enhance the effectiveness of sorafenib, a targeted drug for hepatocellular carcinoma, by reducing drug resistance. Additionally, active components of traditional Chinese medicine and specific compound prescriptions are gaining attention for their potential to target and regulate aerobic glycolysis in hepatocellular carcinoma. Therefore, inhibiting the aerobic glycolysis pathway holds promise as a therapeutic strategy for treating liver tumors. This manuscript aims to review the role, research directions, and clinical studies of aerobic glycolysis in hepatocellular carcinoma.

Lycium barbarum L. Balanced intestinal flora with YAP1/FXR activation in drug-induced liver injury.

Drug-induced liver injury (DILI) is a common and severe adverse drug reaction that can result in acute liver failure. Previously, we have shown that Lycium barbarum L. (wolfberry) ameliorated liver damage in acetaminophen (APAP)-induced DILI. Nevertheless, the mechanism needs further clarification. Herein, we utilized APAP-induced DILI mice to investigate how wolfberry impacts the gut-liver axis to mitigate liver damage. We showed that the abundance of Akkermansia muciniphila (A. muciniphila) was decreased, and intestinal microbiota was disrupted, while the expression levels of YAP1 and FXR-mediated CYP7A1 were reduced in the liver of DILI mice. Furthermore, wolfberry increased the abundance of A. muciniphila and the number of goblet cells in the intestines, while decreasing AST, ALT, and total bile acids (TBA) levels in the serum. Interestingly, A. muciniphila promoted YAP1 and FXR expression in hepatocytes, leading to the inhibition of CYP7A1 expression and a decrease in TBA content. Notably, wolfberry did not exert the beneficial effects mentioned above after the removal of intestinal bacteria by antibiotics (ATB)-containing water. Additionally, Yap1 knockout downregulated FXR expression and enhanced CYP7A1 expression in the liver of hepatocyte-specific Yap1 knockout mice. Therefore, wolfberry stimulated YAP1/FXR activation and reduced CYP7A1 expression by promoting the balance of intestinal microbiota, thereby suppressing the overproduction of bile acids.

[A Prognostic Model of Elderly Patients with Non-small Cell Lung Cancer 
Based on Geriatric Nutritional Risk Index].

BACKGROUND: The relationship between nutritional status and prognosis of cancer patients has emerged as a hotspot for research. The aim of this study is to explore the application value of the geriatric nutritional risk index (GNRI) in assessing the prognosis of elderly patients with non-small cell lung cancer (NSCLC), and establish a Nomogram to predict the prognosis of elderly patients with NSCLC. METHODS: The data of patients with NSCLC aged ≥65 years who were initially treated in the First Affiliated Hospital of Zhengzhou University from January 2016 to December 2019 were retrospectively analyzed. To determine the optimal cut-off value for GNRI, receiver operating characteristic (ROC) curve was constructed, and the patients were divided into high and low GNRI groups. Kaplan-Meier curve and Log-rank test were used to compare overall survival (OS) of the two groups. Univariate and multivariate Cox regression was used to analyze the risk factors for poor prognosis in elderly patients with NSCLC. Nomogram predicting survival in elderly patients with NSCLC was constructed and validated by using R software. RESULTS: Statistically significant differences in age, gender, body mass index (BMI), histological type, albumin, treatment methods, neutrophil to lymphocyte ratio (NLR), prognostic nutritional index (PNI), systemic immune-inflammation index (SII) and cytokeratin 19 fragment (CYFRA21-1) were observed between the high and low GNRI groups (P<0.05). The Kaplan-Meier curve showed a shorter OS in the low-GNRI group. Multivariate Cox regression analysis showed that CYFRA21-1>3.3 ng/mL was an independent risk factor for the development of OS in patients with NSCLC, and GNRI>97.09 was a protective factor [hazard ratio (HR)=0.52, 95% confidence interval (CI): 0.34-0.79, P<0.05]. Patients in the stage IV had a 1.98-fold increased risk of death compared with patients in the stage I (95%CI: 1.02-3.86, P<0.05). The risk of death was 3.58 times higher in patients receiving chemotherapy alone compared with those receiving combination therapy (95%CI: 2.03-6.32, P<0.05). A Nomogram constructed on the basis of GNRI, which predicted the OS of elderly patients with NSCLC with a concordance index (C-index) of 0.70 (95%CI: 0.65-0.76), and the area under the curve (AUC) for 1 and 2-year survival rates to be 0.93 (95%CI: 0.87-0.98) and 0.72 (95%CI: 0.63-0.80), respectively, and the calibration curve has a good coincidence of prediction. CONCLUSIONS: High GNRI scores are significantly associated with improved survival in elderly patients with NSCLC, and reliance on cut-off values may provide the appropriate timing for nutritional support. The Nomogram constructed in this study can be used as an effective tool to predict the survival rate of elderly patients with NSCLC, which has strong clinical practicability.

Nutritional evaluation and transcriptome analyses of short-time germinated seeds in soybean (Glycine max L. Merri.).

Germination is a common practice for nutrition improvement in many crops. In soybean, the nutrient value and genome-wide gene expression pattern of whole seeds germinated for short-time has not been fully investigated. In this study, protein content (PC), water soluble protein content (WSPC), isoflavone compositions were evaluated at 0 and 36 h after germination (HAG), respectively. The results showed that at 36HAG, PC was slightly decreased (P > 0.05) in ZD41, J58 and JHD, WSPC and free isoflavone (aglycones: daidzein, genistein, and glycitein) were significantly increased (P < 0.05), while total isoflavone content was unchanged. Transcriptomic analysis identified 5240, 6840 and 15,766 DEGs in different time point comparisons, respectively. GO and KEGG analysis showed that photosynthesis process was significantly activated from 18HAG, and alternative splicing might play an important role during germination in a complex manner. Response to hydrogen peroxide (H2O2) was found to be down regulated significantly from 18 to 36HAG, suggesting that H2O2 might play an important role in germination. Expression pattern analysis showed the synthesis of storage proteins was slowing down, while the genes coding for protein degradation (peptidase and protease) were up regulated as time went by during germination. For genes involved in isoflavone metabolism pathway, UGT (7-O-glucosyltransferase) coding genes were significantly up regulated (40 up-DEGs vs 27 down-DEGs), while MAT (7-O-glucoside-6''-O-malonyltransferase) coding genes were down regulated, which might explain the increase of aglycones after germination. This study provided a universal transcriptomic atlas for whole soybean seeds germination in terms of nutrition and gene regulation mechanism.

Trends in Piezo Channel Research Over the Past Decade: A Bibliometric Analysis.

Purpose: We used bibliometric methods to evaluate the global scientific output of research on Piezo channels and explore the current status and trends in this field over the past decade. Methods: Piezo channel-related studies published in 2010-2020 were retrieved from Web of Science. The R bibliometrix package was used for quantitative and qualitative analyses of publication outputs and author contributions. VOSviewer was used to construct networks based on co-authorship of countries/institutions/authors, co-citation analysis of journals/references, citation analysis of documents, and co-occurrence of keywords. Results: In total, 556 related articles and reviews were included in the final analysis. The number of publications has increased substantially with time. The country and institution contributing the most to this field was the United States and Scripps Research Institute, respectively. Ardem Patapoutian was the most productive author and ranked first among the cited authors, h-index, and m-index. The top cited reference was the article published by Coste B et al. in Science (2010) that identified Piezo1/2 in mammalian cells. The top journals in terms of the number of selected articles and citations were Nature Communications and Nature, respectively. The co-occurrence analysis revealed that Piezo channels are involved a variety of cell types (Merkel cells, neurons, endothelial cells, red blood cells), physiological processes (touch sensation, blood pressure, proprioception, vascular development), related ion channels (transient receptor potential, Gardos), and diseases (pain, distal arthrogryposis, dehydrated hereditary stomatocytosis, cancer), and pharmacology (Yoda1, GsMTx-4). Conclusion: Our bibliometric analysis shows that Piezo channel research continues to be a hotspot. The focus has evolved from Piezo identification to architecture, activation mechanism, roles in diseases, and pharmacology.

Follow-up study on COVID-19 survivors one year after discharge from hospital.

OBJECTIVE: To evaluate the long-term consequences of COVID-19 survivors one year after recovery, and to identify the risk factors associated with abnormal patterns in chest imaging manifestations or impaired lung function. METHODS: COVID-19 patients were recruited and prospectively followed up with symptoms, health-related quality of life, psychological questionnaires, 6-minute walking test, chest computed tomography (CT), pulmonary function tests, and blood tests. Multivariable logistic regression models were used to evaluate the association between the clinical characteristics and chest CT abnormalities or pulmonary function. RESULTS: Ninety-four patients with COVID-19 were recruited between January 16 and February 6, 2021. Muscle fatigue and insomnia were the most common symptoms. Chest CT scans were abnormal in 71.28% of participants. The results of multivariable regression showed an increased odds in age. Ten patients had diffusing capacity of the lung for carbon monoxide (DLCO) impairment. Urea nitrogen concentration on admission was significantly associated with impaired DLCO. IgG levels and neutralizing activity were significantly lower compared with those in the early phase. CONCLUSIONS: One year after hospitalization for COVID-19, a cohort of survivors were mainly troubled with muscle fatigue and insomnia. Pulmonary structural abnormalities and pulmonary diffusion capacities were highly prevalent in surviving COVID-19 patients. It is necessary to intervene in the main target population for long-term recovery.

[Differences in Pollution Characteristics Under the Southerly and Easterly Wind in Beijing].

In this study, the hourly meteorological factors and PM2.5 concentrations during 2014-2019 in Beijing were analyzed, in order to explore the characteristics of the prevailing wind direction of pollution, and the corresponding long-term tendency. During the study period, 67% of pollution in Beijing occurred under the influence of southerly and easterly wind, and pollution was most likely to occur in winter, followed by spring and autumn. The average pollution probability of winter, spring, autumn and summer was 45.2%, 34.1%, 32.1%, and 26.1% and 47.0%, 45.8%, 39.7%, and 29.6% for southerly and easterly wind, respectively. In Beijing, the southerly wind appeared more frequently, but the pollution occurrence probability was higher under the control of easterly wind, with the maximum difference of 11.7% (2.8%-18.6%) in spring and the minimum difference of 1.8% (-7.6%-13.9%) in winter. During the past six years, the pollution probability decreased at a rate of 4.6%-8.0% and 5.5%-7.9% per year under the southerly and easterly wind influence, respectively. This was clearly reflected in reduced moderate and above levels of pollution. An analysis of both the pollution and meteorological factors under the two wind directions indicates that the visibility, mixing layer height, wind speed, and the frequency of hourly wind speed greater than 3 m·s-1 were higher, and the relative humidity and dew point temperature were lower, when pollution occurred under the southerly wind, while the PM2.5 concentration of pollution was higher in winter and significantly lower in other seasons compared to that of the easterly wind. These findings show that when pollution occurred under the southerly wind, the carrying capacity and diffusion capacity of pollutants in the atmosphere was slightly better than that of the easterly wind, and the increased atmospheric water content under the easterly wind was more conducive to the maintenance and aggravation of pollution. Moreover, under the background of original emission levels, when adding urban heating in winter, the air mass transported by the southerly wind may be more conducive to increased PM2.5 concentration. Furthermore, pollution in Beijing tended to be an "easterly wind type" in spring, summer and autumn, but remained a "southerly wind type" in winter.

[Contribution Assessment of Meteorology Conditions and Emission Change for Air Quality Improvement in Beijing During 2014-2017].

During 2014-2017, the number of haze days and air pollution days declined year by year obviously in Beijing. The average mass concentrations of PM2.5, PM10, SO2, and NO2 also decreased with the alleviated pollution level. These decreases were more obvious during the heating period, especially in November and December. In order to analyze the reasons for the improvement of air quality, changes of the meteorological factors and emission-reduction have been discussed and quantified in this study. This work was based on the numerical simulation model WRF-CHEM and the large data mining technologies of k-nearest neighbor (KNN) and support vector machines (SVM). Meteorological observations indicated that the mean wind speed of 2017 increased by 7.9% compared with the last three years. The frequency of hourly wind speed higher than 3.4 m·s-1 was the highest (10.6%), and frequency of daily relative humidity higher than 70% was lowest (25.1%), in 2017. Meanwhile, the number of low wind days (daily wind speed lower than 2 m·s-1), environmental capacity, ventilation index, and height of the boundary layer showed that the diffusion conditions were better in the heating period of 2017 than those of 2014~2016, especially in November and December. The accumulated precipitation during the non-heating period was 558.3 mm in 2017, which is conducive to pollutant removal and wet deposition. Inter-annual changes of meteorological conditions are important to the air quality. A simulation for December 1~19 by WRF-CHEM during 2014-2017 was performed, and the results demonstrated that changes of meteorological conditions led to a reduction of the PM2.5 concentration of 2017 by 5%, 38%, and 25% compared with that of 2014-2016, respectively. However, it was not possible to quantify the specific contributions of meteorology conditions because of the lack of real emission reduction options. The KNN and SVM models are applied in this study based on the observed meteorology factors, haze days, and pollution days, and it was found that for the reduced haze days and heavy pollution days in 2017, 65.0% could be attributed to emission reduction and 35.0% was caused by improvement of the meteorological conditions.