Functional analyses of Toxoplasma gondii dihydroorotase reveal a promising anti-parasitic target.

Toxoplasma gondii relies heavily on the de novo pyrimidine biosynthesis pathway for fueling the high uridine-5'-monophosphate (UMP) demand during parasite growth. The third step of de novo pyrimidine biosynthesis is catalyzed by dihydroorotase (DHO), a metalloenzyme that catalyzes the reversible condensation of carbamoyl aspartate to dihydroorotate. Here, functional analyses of TgDHO reveal that tachyzoites lacking DHO are impaired in overall growth due to decreased levels of UMP, and the noticeably growth restriction could be partially rescued after supplementation with uracil or high concentrations of L-dihydroorotate in vitro. When pyrimidine salvage pathway is disrupted, both DHOH35A and DHOD284E mutant strains proliferated much slower than DHO-expressing parasites, suggesting an essential role of both TgDHO His35 and Asp284 residues in parasite growth. Additionally, DHO deletion causes the limitation of bradyzoite growth under the condition of uracil supplementation or uracil deprivation. During the infection in mice, the DHO-deficient parasites are avirulent, despite the generation of smaller tissue cysts. The results reveal that TgDHO contributes to parasite growth both in vitro and in vivo. The significantly differences between TgDHO and mammalian DHO reflect that DHO can be exploited to produce specific inhibitors targeting apicomplexan parasites. Moreover, potential DHO inhibitors exert beneficial effects on enzymatic activity of TgDHO and T. gondii growth in vitro. In conclusion, these data highlight the important role of TgDHO in parasite growth and reveal that it is a promising anti-parasitic target for future control of toxoplasmosis.

Leaching behavior and comprehensive toxicity evaluation of heavy metals in MSWI fly ash from grate and fluidized bed incinerators using various leaching methods: A comparative study.

Municipal solid waste incineration fly ash (MSWI FA) is a kind of hazardous waste that contains a substantial amount of heavy metals. To facilitate the appropriate treatment of MSWI FA, the leaching behavior of heavy metals was evaluated in MSWI FA from various sources using different leaching methods. Nine kinds of MSWI FA were investigated using three kinds of batch leaching tests (TCLP, HJ/T 300, and EN12457-2). The chemical form distributions of heavy metals in MSWI FA were obtained by sequential extraction procedures (SEPs) and the environmental risk posed by MSWI FA was comprehensively evaluated. The results showed that the grate and fluidized bed MSWI FA performed differently in various leaching methods, which was mainly dependent on the leachate pH and the chemical form distributions of the heavy metals. In addition, the BCR SEP was more suitable for the fractionation of heavy metals and the environmental risk assessment of MSWI FA when compared with Tessier's SEP. The overall pollution toxicity index allowed a comprehensive risk assessment specific to the leaching environment, thereby offering valuable guidelines for the stabilization or resource-based treatment of MSWI FA.

Immobilization mechanisms of heavy metals by utilizing natural cow bone waste for municipal solid waste incineration fly ash treatment.

Municipal solid waste incinerator (MSWI) fly ash poses intricate compositional challenges and potential environmental hazards. Effective management of such hazardous waste is imperative to mitigate the release of toxic compounds into the environment. Solidification/stabilization (S/S) processes have emerged as a viable strategy to transform MSWI fly ash from incineration waste into a safer and more environmentally benign material. This study aims to comprehensively investigate the potential of utilizing cow bone waste to stabilize heavy metals, focusing on Pb, within municipal solid waste incineration fly ash. Experimental investigations encompassed cow bone-to-fly ash weight ratios ranging from 0.0 (control group) to 7:3, a settling time of 2 h, and a liquid-to-solid (L/S) ratio of 1.0 mL/g. Cow bone waste exhibited pronounced efficacy, particularly within the short settling time, yielding a remarkable Pb removal efficiency of up to 99% at a cow bone waste dose of merely 2% and an L/S ratio of 1.0 mL/g. Concurrently, other heavy metals such as Cd, Cu, and Zn were effectively stabilized with a cow bone waste dose of 1.5% during the same 2-h settling period. The results underscore the pivotal roles of ash/bone ratio and settling time in augmenting Pb stabilization in MSWI fly ash. The application of cow bone waste is anticipated to offer a cost-effective and environmentally sound approach, aligning with sustainable waste management principles.

In Vitro Evaluation Reveals Effect and Mechanism of Artemether against Toxoplasma gondii.

Due to the limited effectiveness of existing drugs for the treatment of toxoplasmosis, there is a dire need for the discovery of new therapeutic options. Artemether is an important drug for malaria and several studies have indicated that it also exhibits anti-T. gondii activity. However, its specific effect and mechanisms are still not clear. To elucidate its specific role and potential mechanism, we first evaluated its cytotoxicity and anti-Toxoplasma effect on human foreskin fibroblast cells, and then analyzed its inhibitory activity during T. gondii invasion and intracellular proliferation. Finally, we examined its effect on mitochondrial membrane potential and reactive oxygen species (ROS) in T. gondii. The CC50 value of artemether was found to be 866.4 µM, and IC50 was 9.035 µM. It exhibited anti-T. gondii activity and inhibited the growth of T. gondii in a dose-dependent manner. We also found that the inhibition occurred primarily in intracellular proliferation, achieved by reducing the mitochondrial membrane integrity of T. gondii and stimulating ROS production. These findings suggest that the mechanism of artemether against T. gondii is related to a change in the mitochondrial membrane and the increase in ROS production, which may provide a theoretical basis for optimizing artemether derivatives and further improving their anti-Toxoplasma efficacy.

Improving stabilization/solidification of MSWI fly ash with coal gangue based geopolymer via increasing active calcium content.

Municipal solid waste incineration fly ash (MSWI FA) is categorized as a hazardous waste, which demands environmentally acceptable treatment due to its easy leachability toxic of heavy metals. This study investigated an innovative and improved method for stabilization/solidification (S/S) of MSWI FA with coal gangue based geopolymer by the addition of active calcium content. The specimen with addition of calcium oxide up to 10 % reached the compressive strength of 2.14 MPa at 28 d. The addition of 30 % calcium oxide resulted in the highest immobilization efficiencies of Cd (98.96 %) and Pb (99.19 %). X-ray Diffraction (XRD), Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscope (SEM), and thermogravimetric (TG) analysis indicated the generation of calcium-containing hydration products was promoted after the improvement of calcium content in binder. Heavy metals were stabilized through the chemical adsorption and ions exchange of amorphous hydration products. On the whole, this study illustrated that the incorporation of active calcium content can improve efficiently S/S of hazardous ash waste such as MSWI FA.

Deep learning radiomics of dual-modality ultrasound images for hierarchical diagnosis of unexplained cervical lymphadenopathy.

BACKGROUND: Accurate diagnosis of unexplained cervical lymphadenopathy (CLA) using medical images heavily relies on the experience of radiologists, which is even worse for CLA patients in underdeveloped countries and regions, because of lack of expertise and reliable medical history. This study aimed to develop a deep learning (DL) radiomics model based on B-mode and color Doppler ultrasound images for assisting radiologists to improve their diagnoses of the etiology of unexplained CLA. METHODS: Patients with unexplained CLA who received ultrasound examinations from three hospitals located in underdeveloped areas of China were retrospectively enrolled. They were all pathologically confirmed with reactive hyperplasia, tuberculous lymphadenitis, lymphoma, or metastatic carcinoma. By mimicking the diagnosis logic of radiologists, three DL sub-models were developed to achieve the primary diagnosis of benign and malignant, the secondary diagnosis of reactive hyperplasia and tuberculous lymphadenitis in benign candidates, and of lymphoma and metastatic carcinoma in malignant candidates, respectively. Then, a CLA hierarchical diagnostic model (CLA-HDM) integrating all sub-models was proposed to classify the specific etiology of each unexplained CLA. The assistant effectiveness of CLA-HDM was assessed by comparing six radiologists between without and with using the DL-based classification and heatmap guidance. RESULTS: A total of 763 patients with unexplained CLA were enrolled and were split into the training cohort (n=395), internal testing cohort (n=171), and external testing cohorts 1 (n=105) and 2 (n=92). The CLA-HDM for diagnosing four common etiologies of unexplained CLA achieved AUCs of 0.873 (95% CI: 0.838-0.908), 0.837 (95% CI: 0.789-0.889), and 0.840 (95% CI: 0.789-0.898) in the three testing cohorts, respectively, which was systematically more accurate than all the participating radiologists. With its assistance, the accuracy, sensitivity, and specificity of six radiologists with different levels of experience were generally improved, reducing the false-negative rate of 2.2-10% and the false-positive rate of 0.7-3.1%. CONCLUSIONS: Multi-cohort testing demonstrated our DL model integrating dual-modality ultrasound images achieved accurate diagnosis of unexplained CLA. With its assistance, the gap between radiologists with different levels of experience was narrowed, which is potentially of great significance for benefiting CLA patients in underdeveloped countries and regions worldwide.

Adsorptive separation of para-xylene by nonporous adaptive crystals of phenanthrene[2]arene.

In this work, we developed a new method for the preparation of phenanthrene[2]arene on a large-scale. Meanwhile, the synthetic phenanthrene[2]arene has been successfully used as nonporous adaptive crystals for the separation of para-xylene (pX) from xylene isomers. The crystal structure revealed that one host molecule can adsorb one pX molecule to form the 1@pX complex, in which pX is located in the cavity of the host.

Study of Corrosion Kinetic Measurement and Morphology Observation of Superheater Tube 12Cr1MoV Alloy in Simulated MSWI Flue Gas Containing Varied HCl or SO2 Concentrations.

Severe corrosion to superheater tubes at high temperatures was gained virtually by gaseous corrosion media, such as HCl and SO2, in the municipal solid waste incineration flue gas. To clarify the effect of varying concentrations of HCl and SO2 in the oxidizing atmosphere on the corrosion of 12Cr1MoV, a commercial alloy used in superheaters, two series of corrosion tests under simulated flue gas were performed. Both the corrosion kinetics and corrosion morphology were measured in this work. The results of the present study demonstrated that the addition of HCl was more corrosive than that of SO2 under an oxidizing atmosphere. The increased HCl concentration had an accelerating effect on the corrosion rate, but the relation between the two was not linear. In contrast, SO2 exhibited a negligible or even inhibitory effect on corrosion. Both series of test results consistently proved that the temperature had a significant influence on the corrosion of 12Cr1MoV alloy, in particular at 580 °C.

Radix Tetrastigma Extracts Enhance the Chemosensitivity in Triple-Negative Breast Cancer Via Inhibiting PI3K/Akt/mTOR-Mediated Autophagy.

OBJECTIVE: Drug resistance in tumors is one of the major factors that leads to chemotherapy failure. This study aims to investigate the effect of Radix Tetrastigma extracts (RTEs) on Taxol-induced autophagy and the chemosensitivity against drug resistance in triple-negative breast cancer (TNBC). METHODS: Taxol-resistant MDA-MB-468 (MDA-MB-468/Taxol) cells were induced and treated with RTEs and/or Taxol. Mice were subcutaneously inoculated with MDA-MB- 468/Taxol cells to establish xenograft models. The associated protein levels were measured by western blotting. Flow cytometry, CCK-8 and EdU assay were performed to detect cell apoptosis, viability, and proliferation, respectively. RESULTS: In MDA-MB-468/Taxol cells, RTEs & Taxol treatment increased cell apoptosis, reduced cell viability and proliferation, up-regulated anti-autophagy marker LC3I/LC3II ratio, and enhanced mTOR level. With RTEs & Taxol treatment, mTOR silencing downregulated LC3I/LC3II ratio, increased cell viability and proliferation, and reduced cell apoptosis, while mTOR overexpression showed the opposite results. PI3K inhibitor reduced AKT and mTOR levels, and the effects on cell activities were similar to the results of mTOR silencing. After RTEs & Taxol injection, xenograft tumor was smaller, and AKT, mTOR, LC3I/LC3II ratio and apoptotic marker cleaved caspase-3 were increased. CONCLUSION: RTEs enhanced the chemosensitivity of resistant TNBC cells to Taxol through inhibiting PI3K/Akt/mTOR-mediated autophagy. MICRO: RTEs exerted anti-tumor effects in various cancers, and this study determined its role in TNBC. Taxol-resistant MDA-MB-468 cells were induced and xenograft models were established. We found that RTEs inhibited autophagy of MDA-MB-468/Taxol cells and reduced tumor growth. Inhibition of PI3K/Akt/mTOR pathway promoted autophagy of MDA-MB-468/Taxol cells. We may provide a new potential strategy for TNBC treatment.

The Curcumin Analog EF24 Inhibits Proliferation and Invasion of Triple-Negative Breast Cancer Cells by Targeting the Long Noncoding RNA HCG11/Sp1 Axis.

EF24, a curcumin analog, exerts a potent antitumor effect on various cancers. However, whether EF24 retards the progression of triple-negative breast cancer (TNBC) remains unclear. In this study, we explored the role of EF24 in TNBC and clarified the underlying mechanism. In a mouse model of TNBC xenograft, EF24 administration reduced the tumor volume, suppressed cell proliferation, promoted cell apoptosis, and downregulated long noncoding RNA human leukocyte antigen complex group 11 (HCG11) expression. In TNBC cell lines, EF24 administration reduced cell viability, suppressed cell invasion, and downregulated HCG11 expression. HCG11 overexpression reenhanced the proliferation and invasion of TNBC cell lines suppressed by EF24. The following mechanism research revealed that HCG11 overexpression elevated Sp1 transcription factor (Sp1) expression by reducing its ubiquitination, thereby enhanced Sp1-mediated cell survival and invasion in the TNBC cell line. Finally, the in vivo study showed that HCG11-overexpressed TNBC xenografts exhibited lower responsiveness in response to EF24 treatment. In conclusion, EF24 treatment reduced HCG11 expression, resulting in the degradation of Sp1 expression, thereby inhibiting the proliferation and invasion of TNBC cells.

Enhancing the Potential of Miniature-Scale DNA-Compatible Radical Reactions via an Electron Donor-Acceptor Complex and a Reversible Adsorption to Solid Support Strategy.

DNA-encoded library (DEL) technology is a powerful tool in the discovery of bioactive probe molecules and drug leads. Mostly, the success in DEL technology stems from the molecular diversity of the chemical libraries. However, the construction of DELs has been restricted by the idiosyncratic needs and the required low concentration (∼1 mM or less) of the library intermediate. Here, we report visible-light-promoted on-DNA radical coupling reactions via an electron donor-acceptor (EDA) complex and a reversible adsorption to solid support (RASS) strategy. This protocol provides a unique solution to the challenges of increasing the reactivity of highly diluted DNA substrates and reducing the residues of heavy metals from photocatalysts. A series of on-DNA indole sulfone and selenide derivatives were obtained with good to quantitative conversions. It is anticipated that these mild-condition on-DNA radical reactions will significantly improve the chemical diversity of DELs and find widespread utility to DEL construction.

Inhibition of DNA­PK by gefitinib causes synergism between gefitinib and cisplatin in NSCLC.

Lung cancer has the highest incidence and mortality rates among the malignant tumor types worldwide. Platinum­based chemotherapy is the main treatment for advanced non­small­cell lung cancer (NSCLC), and epidermal growth factor receptor­tyrosine kinase inhibitors (EGFR­TKIs) have greatly improved the survival of patients with EGFR­sensitive mutations. However, there is no standard therapy for treating patients who are EGFR­TKI resistant. Combining EGFR­TKIs and platinum­based chemotherapy is the most popular strategy in the clinical practice. However, the synergistic mechanism between EGFR­TKIs and platinum remains unknown. Therefore, the aim of the present study was to determine the synergistic mechanism of gefitinib (an EGFR­TKI) and cisplatin (a main platinum­based drug). MTT assay, apoptosis analysis, tumorsphere formation and an orthotropic xenograft mouse model were used to examine the combination effects of gefitinib and cisplatin on NSCLC. Co­immunoprecipitation and immunofluorescence were used to identify the underlying mechanism. It was found that gefitinib could selectively inhibit EGFR from entering the nucleus, decrease DNA­PK activity and enhance the cytotoxicity of cisplatin on NSCLC. Collectively, the results suggested that inhibition of DNA­dependent protein kinase by gefitinib may be due to the synergistic mechanism between gefitinib and cisplatin. Thus, the present study provides a novel insight into potential biomarkers for the selection of combination therapy of gefitinib and cisplatin.

Bioinformatics analysis of prognosis-related long non-coding RNAs in invasive breast carcinoma.

Breast cancer is one of the most common types of cancer among women worldwide and needs more sensitive prognostic biomarkers to improve its treatment. In the present study, differentially expressed long non-coding RNAs (lncRNAs) in invasive breast carcinoma from The Cancer Genome Atlas and cBioPortal database were investigated, identifying 292 differentially expressed lncRNAs in 1,100 cases. By analyzing the overall survival rate, 10 lncRNAs were significantly correlated with poor prognosis. To explore the underlying molecular mechanisms of the 10 prognosis-related lncRNAs, bioinformatic methods were used to predict the potential target miRNAs, mRNAs and proteins, and to construct a lncRNA-miRNA-mRNA regulatory network and lncRNA-protein interaction network. Finally, the functions of the target genes and proteins were insvestigated using Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses. The results showed that these 10 lncRNAs could be novel prognostic markers for invasive breast carcinoma and the present study aimed to provide novel insight into the diagnosis and treatment of breast cancer.

[Effects of organic fertilizer on soil environment and yield of tomato under year-round cultivation]. / æœ‰æœºè‚¥å¯¹è®¾æ–½ç•ªèŒ„å‘¨å¹´æ ½åŸ¹åœŸå£¤çŽ¯å¢ƒå’Œäº§é‡çš„å½±å“.

The early-spring and autumn-winter tomato in greenhouse is the main planting patterns of protected vegetable in North China. Taking the customary fertilization amount of farmers under this planting pattern as control (CK, 100% chemical fertilizer), six organic fertilizer replacing chemical fertilizer treatments were set, namely, 15% (T1), 30% (T2), 45% (T3), 60% (T4), 75% (T5), 100% organic fertilizer (T6), to examine the replacing effects on soil environment and tomato yield. The results showed that soil bacteria increased with increasing organic fertilizer amount, the actinomycetes wers up to 12.12×106 cfu·g-1 under T1 treatment which was the highest one. Combined application of organic fertilizer could increase soil urease activity, decrease catalase activity, increase soil organic matter, and enhance the concentrations of available phosphorus and available potassium, indicating that organic fertilizer had significant effects on soil physical and chemical properties, soil enzyme activity and nutrient accumulation. The invertase activity and available phosphorus content under T1 treatment were the highest, being 1.36 mg·g-1 and 305.4 mg·kg-1, respectively, while the available potassium content of T2 treatment was the highest (582.6 g·kg-1). In addition, T2 had the largest percentage of >0.25 mm water-stable agglomerate (94.2%). Compared with CK, the application of organic fertilizer could improve tomato quality and increase yield. The lycopene content of T1 was the highest (5.69), the sugar-acid ratio of T1 and T2 was 8.19 and 8.70, respectively, with better tastes. The yield of T1 was the highest, followed by T2 treatment, which was 16.6% and 5.8% higher than that of CK, respectively. It suggested that reducing the application rate of chemical fertilizers by 15%-30% with organic fertilizer was a preferred fertilization measure in this planting pattern.

Punicalagin inhibits the viability, migration, invasion, and EMT by regulating GOLPH3 in breast cancer cells.

Breast cancer (BC) is one of the most common malignancies worldwide. Punicalagin (PN), which is a type of polyphenol, has been reported to act as a tumor suppressor. This study aimed to investigate the effects of PN on cellular process in BC and its molecular mechanism. The effects of various doses of PN on cell viability, migration, and invasion capacities of MCF-7 and MDA-MB-231 cells were detected by CCK-8, wound-healing, and Transwell assays. Golgi phosphoprotein 3 (GOLPH3) was then transfected into the cells with or without PN treatment, and GPLPH3 expression level was examined by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot, and expressions of epithelial-mesenchymal transition (EMT)-related protein matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), E-Cadherin, and N-Cadherin were measured by Western blot. High dose of PN treatment (50 µM or higher) significantly inhibited viability, migration, and invasion of MCF-7 and MDA-MB-231 cells, while overexpressed GOLPH3 promoted cell viability, migration, and invasion, and partially reversed the effects of PN treatment on the BC cells. PN inhibited the expressions of GOLPH3, MMP-2, MMP-9, and N-Cadherin, and promoted E-Cadherin expression, while overexpression of GOLPH3 partly reversed above effects attributing to PN. Thus, PN suppresses cell viability and metastasis via regulating GOLPH3 in BC, which provides a possible therapeutic direction to the treatment of BC.

[Application effects of biogas slurry partly substituting for chemical fertilizer on autumn tomato production in winter-solar greenhouse]. / æ²¼æ¶²éƒ¨åˆ†æ›¿ä»£åŒ–è‚¥åœ¨æ—¥å ‰æ¸©å®¤ç§‹ç•ªèŒ„ä¸Šçš„åº”ç”¨æ•ˆæžœ.

To explore the effects of biogas slurry coordinating chemical fertilizer on growth promotion of tomato, we used three kinds of typical biogas slurry as concentrated nutrient solution, respectively fermented from raw duck manure, pig manure, cow dung, while urea, monocalcium phosphate and potassium sulphate as auxiliary nutrition to balance the nutrient difference between different dilution ratios of biogas slurry. The results showed the biogas slurry partially substituting chemical fertilizer could significantly improve soil fertility, including available nitrogen, phospho-rus, and potassium. As for water soluble calcium, magnesium, iron, manganese and zinc in soil, biogas slurry application could activate their availability, with the magnitude of such effects depended on the fermentation level of raw materials and dilution ratio. Compared with chemical fertilizer, coordinating biogas liquid fertilizer significantly promoted the growth of tomato, with the yield increased by 55.9%-232.8% and the chemical fertilizer dosage decreased by 18.2%-85.0%. Furthermore, such effects became more prominent along with prolonged time. The fruit quality was significantly improved with the increases of lycopene, ascorbic acid and total sugar, and the decreases of acidity and nitrite concentration, and the decrease of NO2- by 35.6%-90.3%. In addition, the taste flavor of fruits was 7.0%-20.3% higher than that of chemical fertilizer treatment. The yield and quality of tomato took on nonlinear synchronization, and the relation between taste flavor and sugar/acid showed significantly positive correlation, which was affected by fertilizer type. Biogas slurry partly substituting chemical fertilizer could achieve the goals of high yield, high quality, environmental protection, efficient utilization of agricultural resources in tomato production.

Development of an inflammation imaging tracer, 111In-DOTA-DAPTA, targeting chemokine receptor CCR5 and preliminary evaluation in an ApoE-/- atherosclerosis mouse model.

BACKGROUND: Chemokine receptor 5 (CCR5) plays an important role in atherosclerosis. Our objective was to develop a SPECT tracer targeting CCR5 for imaging plaque inflammation by radiolabeling D-Ala-peptide T-amide (DAPTA), a CCR5 antagonist, with 111In. METHODS: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) conjugated DAPTA (DOTA-DAPTA) was labeled with 111In. Cell uptake studies were conducted in U87-CD4-CCR5 and U87-MG cells. Biodistribution was determined in C57BL/6 mice. Autoradiography, en face and Oil Red O (ORO) imaging studies were performed in ApoE-/- mice. RESULTS: DOTA-DAPTA was radiolabeled with 111In with high radiochemical purity (> 98%) and specific activity (70 MBq·nmol). 111In-DOTA-DAPTA exhibited fast blood and renal clearance and high spleen uptake. The U87-CD4-CCR5 cells had significantly higher uptake in comparison to the U87-MG cells. The cell uptake was reduced by three times with DAPTA, indicating the receptor specificity of the uptake. Autoradiographic images showed significantly higher lesion uptake of 111In-DOTA-DAPTA in ApoE-/- mice than that in C57BL/6 mice. The tracer uptake in 4 month old ApoE-/- high fat diet (HFD) mice with blocking agent was twofold lower than the same mice without the blocking agent, demonstrating the specificity of the tracer for the CCR5 receptor. CONCLUSION: 111In-DOTA-DAPTA, specifically targeting chemokine receptor CCR5, is a potential SPECT agent for imaging inflammation in atherosclerosis.

[Effects of purified humic acid on the growth and nitrogen metabolism of cucumber seedlings under nitrogen stress.] / çº¯åŒ–è æ¤é ¸å¯¹æ°®èƒè¿«ä¸‹é»„ç“œå¹¼è‹—ç”Ÿé•¿å’Œæ°®ä»£è°¢çš„å½±å“.

To investigate the effects of purified humic acid (PHA) on the growth and nitrogen metabolism of cucumber under different levels of nitrogen stress and to explore the mechanism of PHA's alleviation on abiotic stress, we examined the effects of PHA on 'Xintaimici' cucumber growth and nitrogen metabolism under low nitrogen (1.0 mmol·L-1 NO3-) stress and high nitrogen (101 mmol·L-1 NO3-) stress in hydroponics compared with normal level (11 mmol·L-1 NO3-). The results showed that the growth of cucumber seedlings was inhibited under nitrogen stress treatments. Plant height, stem diameter, leaf area and dry matter accumulation under nitrogen stress were lower than that at normal nitrogen level. Dry matter accumulation under the normal nitrogen level and low nitrogen stress were significantly increased by PHA, but there was no significant difference under high nitrogen stress. The absorption of NO3- in cucumber seedlings was affected by PHA, showing increased nitrate content in cucumber seedlings under low nitrogen stress and decreased under high nitrogen stress. PHA significantly decreased ammonium content in roots and leaves under low and high nitrogen stress. Compared with normal level of nitrogen (CK), NR, GS, GOGAT, GDH activity in roots and leaves and NiR activity in roots significantly decreased under low and high nitrogen stress. PHA increased the activities of NR, NiR, GS, GOGAT, and GDH to different extents. PHA increased amino acid and soluble protein content in cucumber seedling roots and leaves. In summary, PHA addition alleviated the inhibitory effect of nitrogen stress on the growth of cucumber seedlings.

[Effects of sodium nitroprusside on growth and physiological characteristics of tomato seedlings under iron deficiency and NO3- stress]. / ç¡æ™®é’ å¯¹ç¼ºé“å’Œç¡é ¸ç›èƒè¿«ä¸‹ç•ªèŒ„å¹¼è‹—ç”Ÿé•¿åŠç”Ÿç†ç‰¹æ€§çš„å½±å“.

The solution culture method was used to study the effects of sodium nitroprusside (SNP) on plant growth, nutrient uptake and antioxidant enzyme activities of tomato seedlings under iron deficiency and NO3- stress. The results indicated that after 7 d of treatment, iron deficiency inhibited the tomato seedling growth, decreased chlorophyll (a and b) and carotenoid contents, and led to obvious chlorosis; iron deficiency also reduced the activity of SOD, POD and CAT, resulting in significant accumulation of MDA contents and higher electrolytic leakage; proline and soluble sugar contents were not significantly changed; contents of N, P, K, Ca, Mg and Fe in both leaves and roots of tomato seedlings were decreased under iron deficiency in varying degrees. The combined stress of NO3- stress and iron deficiency promoted the inhibition of plant growth, decreased chlorophyll (a and b), carotenoid contents and the activities of SOD, POD and CAT; electrolytic leakage MDA, proline and soluble sugar contents of N, P, Mg, Fe in both leaves and roots of tomato seedlings were much lower, but the contents of K and Ca were significantly increased. Compared to the treatment without SNP, adding 0.1 mmol·L-1 SNP could alleviate the growth inhibition of stressed tomato seedlings. Adding 0.1 mmol·L-1 SF (sodium ferrocyanide) also showed alleviating or promoting effect on some above indexes including the activity of SOD, POD and CAT to some degree, but the other physiological indexes were not significantly changed because iron was contained in SF.

Formulation, characterization and tissue distribution of a novel pH-sensitive long-circulating liposome-based theranostic suitable for molecular imaging and drug delivery.

PURPOSE: When designing liposome formulas for treatment and diagnostic purposes, two of the most common challenges are 1) the lack of a specific release mechanism for the encapsulated contents and 2) a short circulation time due to poor resistance to biological fluids. This study aimed to create a liposome formula with prolonged in vivo longevity and pH-sensitivity for cytoplasmic drug delivery. MATERIALS AND METHODS: Liposomal particles were generated using hydrogenated soy (HS) phosphatidylcholine, cholesteryl hemisuccinate (CHEM), polyethylene glycol (PEG) and diethylenetriaminepentaacetic acid-modified phosphatidylethanolamine with film hydration and extrusion methods. The physicochemical properties of the different formulas were characterized. pH-sensitivity was evaluated through monitoring release of encapsulated calcein. Stability of the radiolabeled liposomes was assessed in vitro through incubation with human serum. The best formula was selected and injected into healthy rats to assess tissue uptake and pharmacokinetics. RESULTS: Liposomal particles were between 88 and 102 nm in diameter and negatively charged on the surface. Radiolabeling of all formulas with indium-111 was successful with good efficiency. 1%PEG-HS-CHEM not only responded to acidification very quickly but also underwent heavy degradation with serum. The 4%PEG-HS-CHEM, which exhibited both comparatively good pH-sensitivity (up to 20% release) and satisfactory stability (stability >70% after 24 h), was considered the best candidate for in vivo evaluation. Tissue distribution of 4%PEG-HS-CHEM was comparable to that of 4%PEG-HS-Chol, a long-circulating but pH-insensitive control, showing major accumulation in liver, spleen, intestine and kidneys. Analysis of blood clearance showed favorable half-life values: 0.6 and 14 h in fast and slow clearance phases, respectively. CONCLUSION: 4%PEG-HS-CHEM showed promising results in pH-sensitivity, serum stability, tissue uptake and kinetics and is a novel liposome formulation for multifunctional theranostic applications.