Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 27
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
J Hazard Mater ; 471: 134370, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38688214

RESUMO

Plant growth-promoting bacteria (PGPB) offer a promising solution for mitigating heavy metals (HMs) stress in crops, yet the mechanisms underlying the way they operate in the soil-plant system are not fully understood. We therefore conducted a meta-analysis with 2037 observations to quantitatively evaluate the effects and determinants of PGPB inoculation on crop growth and HMs accumulation in contaminated soils. We found that inoculation increased shoot and root biomass of all five crops (rice, maize, wheat, soybean, and sorghum) and decreased metal accumulation in rice and wheat shoots together with wheat roots. Key factors driving inoculation efficiency included soil organic matter (SOM) and the addition of exogenous fertilizers (N, P, and K). The phylum Proteobacteria was identified as the keystone taxa in effectively alleviating HMs stress in crops. More antioxidant enzyme activity, photosynthetic pigment, and nutrient absorption were induced by it. Overall, using PGPB inoculation improved the growth performance of all five crops, significantly increasing crop biomass in shoots, roots, and grains by 33 %, 35 %, and 20 %, respectively, while concurrently significantly decreasing heavy metal accumulation by 16 %, 9 %, and 37 %, respectively. These results are vital to grasping the benefits of PGPB and its future application in enhancing crop resistance to HMs.


Assuntos
Produtos Agrícolas , Metais Pesados , Microbiologia do Solo , Poluentes do Solo , Bactérias/metabolismo , Bactérias/crescimento & desenvolvimento , Biomassa , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Produtos Agrícolas/microbiologia , Metais Pesados/metabolismo , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Raízes de Plantas/microbiologia , Solo/química , Poluentes do Solo/metabolismo
2.
Environ Pollut ; 348: 123787, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38548159

RESUMO

The co-occurrence of microplastics (MPs) and heavy metal(loid)s (HMs) has attracted growing scientific interest because of their wide distribution and environmental toxicity. Nevertheless, the interactions between MPs and HMs in soil-plant systems remain unclear. We conducted a meta-analysis with 3226 observations from 87 independent studies to quantify the impact of MPs addition on the plant biomass and HMS accumulation. Co-occurrence of MPs and HMs (except for As) induced synergistic toxicity to plant growth. MPs promoted their uptake in the shoot by 11.0% for Cd, 30.0% for Pb, and 47.1% for Cu, respectively. In contrast, MPs caused a significant decrease (22.6%, 17.9-26.9%) in the shoot As accumulation. The type and dose of MPs were correlated with the accumulation of HMs. MPs increased available concentrations of Cd, Pb, and Cu, but decreased available As concentration in soils. Meanwhile, MPs addition significantly lowered soil pH. These findings may provide explanations for MPs-mediated effects on influencing the accumulation of HMs in plants. Using a machine learning approach, we revealed that soil pH and total HMs concentration are the major contributors affecting their accumulation in shoot. Overall, our study indicated that MPs may increase the environmental risks of HMs in agroecosystems, especially metal cations.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/análise , Microplásticos , Plásticos , Chumbo/análise , Metais Pesados/análise , Plantas , Solo , Poluentes do Solo/toxicidade , Poluentes do Solo/análise
3.
AAPS J ; 25(6): 103, 2023 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-37936002

RESUMO

The in-person workshop "Drug Dissolution in Oral Drug Absorption" was held on May 23-24, 2023, in Baltimore, MD, USA. The workshop was organized into lectures and breakout sessions. Three common topics that were re-visited by various lecturers were amorphous solid dispersions (ASDs), dissolution/permeation interplay, and in vitro methods to predict in vivo biopharmaceutics performance and risk. Topics that repeatedly surfaced across breakout sessions were the following: (1) meaning and assessment of "dissolved drug," particularly of poorly water soluble drug in colloidal environments (e.g., fed conditions, ASDs); (2) potential limitations of a test that employs sink conditions for a poorly water soluble drug; (3) non-compendial methods (e.g., two-stage or multi-stage method, dissolution/permeation methods); (4) non-compendial conditions (e.g., apex vessels, non-sink conditions); and (5) potential benefit of having both a quality control method for batch release and a biopredictive/biorelevant method for biowaiver or bridging scenarios. An identified obstacle to non-compendial methods is the uncertainty of global regulatory acceptance of such methods.


Assuntos
Biofarmácia , Absorção Intestinal , Humanos , Liberação Controlada de Fármacos , Solubilidade , Água
4.
Ecotoxicol Environ Saf ; 259: 115044, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37216863

RESUMO

Potentially toxic elements (PTEs) in cultivated lands pose serious threats to the environment and human health. Therefore, improving the understanding of their distinct sources and environmental risks by integrating various methods is necessary. This study investigated the distribution, sources, and environmental risks of eight PTEs in cultivated soils in Lishui City, eastern China, using digital soil mapping, positive matrix factorisation (PMF), isotopic tracing, and Monte Carlo simulation. The results showed that Pb and Cd are the main pollutants, which posed higher ecological risks in the study area than the other PTEs. Natural, mining, traffic, and agricultural sources were identified as the four determinants of PTE accumulation via a PMF model combined with Pearson correlation analysis, showing that their contribution rates were 22.6 %, 45.7 %, 15.2 %, and 16.5 %, respectively. Stable isotope analysis further confirmed that local mining activities affected the HM accumulation. Additionally, non-carcinogenic and carcinogenic risk values for children were 3.18 % and 3.75 %, respectively, exceeding their acceptable levels. We also identified that mining activities were the most important sources of human health risks (55.7 % for adults and 58.6 % for children) via Monte Carlo simulations coupled with the PMF model. Overall, this study provides insights into the PTE pollution management and health risk control in cultivated soils.


Assuntos
Metais Pesados , Poluentes do Solo , Criança , Adulto , Humanos , Solo , Metais Pesados/análise , Monitoramento Ambiental/métodos , Método de Monte Carlo , Poluentes do Solo/análise , Medição de Risco/métodos , China
5.
J Hazard Mater ; 444(Pt B): 130425, 2023 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-36435046

RESUMO

Inoculation with growth-promoting rhizobacteria inoculation and the addition of exogenous signaling molecules are two distinct strategies for improving heavy metal resistance and promoting growth in crops through several mechanisms. However, whether rhizobacteria and phyllosphere signaling molecules can act synergistically alleviate heavy metal stress and promote growth and the mechanisms underlying these effects remain unclear. Here, a novel strategy involving the co-application of growth-promoting rhizobacteria and an exogenous signaling molecule was developed to reduce cadmium (Cd) phytotoxicity and promote pak choi growth in Cd-contaminated soil. We found that the co-application of Azospirillum brasilense and hydrogen sulfide (H2S) resulted in significant improvements in shoot biomass and antioxidant enzyme content and a decline in the levels of Cd translocation factors. In addition, this co-application significantly improved pak choi Cd resistance. Furthermore, we observed a significant negative correlation between abscisic acid concentration and Cd content of pak choi and a positive correlation between H2S concentration and biomass. These findings revealed that the co-application of rhizobacteria and exogenous signaling molecules synergistically promoted the growth of vegetable crops subjected to heavy metal stress. Our results may serve as a guide for improving the food safety of crops grown in soil contaminated with heavy metals.


Assuntos
Azospirillum brasilense , Brassica , Cádmio/toxicidade , Ácido Abscísico , Produtos Agrícolas , Solo
6.
Appl Opt ; 61(25): 7307-7314, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36256027

RESUMO

A Nd:YAG nanosecond pulsed laser was used to carry out laser peening and cryogenic laser peening (CLP) experiments at room temperature (25°C) and cryogenic temperature (-100∘C), respectively, on the vibration fatigue life of 2024-T351 aluminum alloy. It was found that CLP induced a higher amplitude of compressive residual stress and improved the nano-hardness and the elastic modulus. Compared to the LP-ed samples, the fatigue life of the CLP-ed specimens was higher, and the initiation and propagation of fatigue cracks were more effectively inhibited. Therefore, CLP can effectively improve the fatigue performance of aluminum alloys.

7.
J Hazard Mater ; 437: 129445, 2022 09 05.
Artigo em Inglês | MEDLINE | ID: mdl-35897177

RESUMO

Glomalin-related soil protein (GRSP) is an essential bioactive component that may respond to heavy metal stress; however, its exact influence on metal bioavailability and the associated mechanism remains poorly understood. This study investigated the speciation and distribution of heavy metals in soil aggregates associated with GRSP through macroscopic and microscopic approaches. A field study showed that the metal ions were distributed to the macro-aggregate fraction by partitioning the particle size classes during phytoremediation. Partial least squares path modeling (PLS-PM) demonstrated that the heavy metal bioavailability was negatively affected by aggregate stability (61.5%) and GRSP content (52.8%), suggesting that the soil aggregate properties regarding GRSP were vital drivers in mitigating environmental risk closely associated with toxic metal migration in soil-plant systems. The nonideal competitive adsorption (NICA)-Donnan model fitting suggested that GRSP were rich in acid site density, and the complexation with deprotonated groups dominated the speciation of heavy metals in soil. Further, the microfocus X-ray absorption/fluorescence spectroscopy analysis indicated that GRSP might promote the formation of stable metal species by binding with sulfur-containing sites. This study highlights the role of GRSP in heavy metal sequestration in contaminated soils, providing new guidance on the GRSP intervention for phytoremediation strategies.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Proteínas Fúngicas/química , Solo/química , Poluentes do Solo/metabolismo
8.
AAPS J ; 23(6): 113, 2021 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-34704158

RESUMO

In vivo drug dissolution kinetics of BCS Class 2a IR solid oral drug products remains largely unknown. An understanding to what extent the solubility influences in vivo dissolution is needed to design appropriate in vitro dissolution methods. In this study, nonsteroidal anti-inflammatory drugs (NSAIDs) are used to investigate the in vivo dissolution of BCS Class 2a drugs based on numerical deconvolution analyses. The PK data were obtained from published literature or drug applications submitted to the FDA. It has been hypothesized that the in vivo drug dissolution rate would likely correlate to the solubility of NSAIDs in the media at gastrointestinal pH. Our findings show a short lag time of absorption (Tlag), comparable to the liquid gastric emptying time and independent of the solubility and formulation. In Vivo drug dissolution of NSAIDs was generally rapid and complete within the regular drug residence time in the small intestine while multi-phase absorption was observed in some subjects for all the NSAIDs. The comparisons of in vivo drug dissolution rate, which was characterized by in vivo dissolution half-life (Thalf), indicate that solubility has a minimal impact on in vivo drug dissolution rate for NSAIDs. Gastric emptying regulated by migrating motor complex (MMC) under fasted state most likely governs drug dissolution and absorption of NSAIDs. For BCS Class 2a IR solid oral drug products, large variability of gastric emptying and MMC as well as the strong driving force of intestinal absorption probably outweigh the impact of solubility on drug in vivo dissolution.


Assuntos
Anti-Inflamatórios não Esteroides/química , Trato Gastrointestinal/metabolismo , Absorção Intestinal , Solubilidade , Adulto , Anti-Inflamatórios não Esteroides/farmacocinética , Liberação Controlada de Fármacos , Esvaziamento Gástrico/fisiologia , Meia-Vida , Humanos , Concentração de Íons de Hidrogênio
9.
Materials (Basel) ; 14(14)2021 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-34300700

RESUMO

The removal of organic pollutants using green environmental photocatalytic degradation techniques urgently need high-performance catalysts. In this work, a facile one-step hydrothermal technique has been successfully applied to synthesize a Nb2O5 photocatalyst with uniform micro-flower structure for the degradation of methyl orange (MO) under UV irradiation. These nanocatalysts are characterized by transmission and scanning electron microscopies (TEM and SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and UV-Vis diffuse reflectance spectroscopy (DRS). It is found that the prepared Nb2O5 micro-flowers presents a good crystal phases and consist of 3D hierarchical nanosheets with 400-500 nm in diameter. The surface area is as large as 48.6 m2 g-1. Importantly, the Nb2O5 micro-flowers exhibit superior catalytic activity up to 99.9% for the photodegradation of MO within 20 mins, which is about 60-fold and 4-fold larger than that of without catalysts (W/O) and commercial TiO2 (P25) sample, respectively. This excellent performance may be attributed to 3D porous structure with abundant catalytic active sites.

10.
Environ Pollut ; 268(Pt A): 115719, 2021 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-33007598

RESUMO

(S,S)-ethylenediaminedisuccinic acid (EDDS) has a strong capacity to mobilize potentially toxic elements (PTEs) in phytoextraction. It can release NH4+-N via biodegradation, which can enhance N supply to soil thereafter promote plant growth and plant resistance to PTEs. However, the advanced feature of released N in the EDDS-enhanced phytoextraction remains unclear. In the current study, the effects of N supply released from EDDS on ryegrass phytoextraction and plant resistance to PTEs were investigated in detail by a comparison with urea. Our results supported that the addition of both EDDS and urea increased N concentration in soil solution, yet EDDS needed more time to release available N for plant uptake and transported more N from root to shoot. Additionally, EDDS significantly increased the concentration of all targeted PTEs, i.e. Cu, Zn, Cd, and Pb, in the soil solution, which results in higher levels of their occurrence in plant biomass compared with urea. By contrast, the supply of N slightly enhanced the ryegrass uptake of micro-nutrients, i.e. Cu and Zn, yet it caused negligible effects on nonessential elements, i.e. Cd and Pb. The mobilized PTEs by EDDS lead to elevated oxidative stress because higher levels of malondialdehyde and O2•- were observed. The supply of N attenuated oxidative stress caused by O2•- and H2O2, which was associated with enhanced activities of superoxide dismutase and peroxidase. Our results advanced the understanding of the exogenous N supply and metal resistance mechanisms in the EDDS-enhanced phytoextraction. This study also highlighted that EDDS can serve as a N source to ease N-deficient problems in PTEs-contaminated soils.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Quelantes , Etilenodiaminas , Peróxido de Hidrogênio , Metais Pesados/análise , Nitrogênio , Estresse Oxidativo , Solo , Poluentes do Solo/análise , Succinatos
11.
Environ Sci Technol ; 54(7): 4016-4025, 2020 04 07.
Artigo em Inglês | MEDLINE | ID: mdl-32176845

RESUMO

Binding of Pb(II) to ferrihydrite-Bacillus subtilis composites formed in the presence of bacterial cells were investigated through macroscopic and microscopic techniques. Diffuse layer model (DLM) fitting and isothermal titration calorimetry (ITC) analysis indicated that the hydroxyl group played a key role in Pb(II) sorption onto composites by masking reactive sites, such as carboxyl and phosphoryl groups of bacterial cells. Negative enthalpy (from -39.29 to -57.87 kJ mol-1) and positive entropy (from 135.61 to 193.47 kJ mol-1) of Pb(II) sorption onto composites revealed that inner-sphere complexes formed through exothermic reactions and was driven by both entropy and enthalpy. Spatial distribution of these inner-sphere species at varied Pb(II) loading demonstrated that interactions between Pb(II) and bacterial cells preceded that of mineral components in composites, using microfocus X-ray fluorescence spectroscopy (µ-XRF) maps and microfocus X-ray absorption near edge structure (µ-XANES) spectra. Combined with bulk Pb LIII-edge X-ray absorption fine structure (XAFS) spectrum, we inferred that mononuclear bidentate edge-sharing hydroxyl-Pb complexes, monodentate mononuclear carboxyl-Pb and phosphoryl-Pb complexes predominantly contributed to Pb(II) inner-sphere binding with mineral and bacterial fractions in composites, respectively. The molecular binding mechanisms obtained in this study provide further insight into the sequestration and migration of toxic metals in natural environments.


Assuntos
Bactérias , Compostos Férricos , Adsorção , Calorimetria
12.
Environ Pollut ; 250: 118-126, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-30991280

RESUMO

Metal-resistant bacteria can survive exposure to high metal concentrations without any negative impact on their growth. Biosorption is considered to be one of the more effective detoxification mechanisms acting in most bacteria. However, molecular-scale characterization of metal biosorption by wild metal-resistant bacteria has been limited. In this study, the Pb(II) biosorption behavior of Serratia Se1998 isolated from Pb-contaminated soil was investigated through macroscopic and microscopic techniques. A four discrete site non-electrostatic model fit the potentiometric titration data best, suggesting a distribution of phosphodiester, carboxyl, phosphoryl, and amino or hydroxyl groups on the cell surface. The presence of these functional groups was verified by the attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, which also indicated that carboxyl and phosphoryl sites participated in Pb(II) binding simultaneously. The negative enthalpy (-9.11 kJ mol-1) and large positive entropy (81.52 J mol-1 K-1) of Pb(II) binding with the bacteria suggested the formation of inner-sphere complexes by an exothermic process. X-ray absorption fine structure (XAFS) analysis further indicated monodentate inner-sphere binding of Pb(II) through formation of C-O-Pb and P-O-Pb bonds. We inferred that C-O-Pb bonds formed on the flagellar surfaces, establishing a self-protective barrier against exterior metal stressors. This study has important implications for an improved understanding of metal-resistance mechanisms in wild bacteria and provides guidance for the construction of genetically engineered bacteria for remediation purposes.


Assuntos
Bactérias/metabolismo , Metais/toxicidade , Espectroscopia de Infravermelho com Transformada de Fourier , Espectroscopia por Absorção de Raios X , Adsorção/fisiologia , Bactérias/crescimento & desenvolvimento , Farmacorresistência Bacteriana , Chumbo/toxicidade , Desintoxicação por Sorção
13.
Sci Total Environ ; 658: 1440-1451, 2019 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-30678003

RESUMO

The effects of precipitation patterns on the metabolism of soil microbes are poorly understood, especially in water-limited ecosystems where soil microorganisms play crucial roles in the turnover of soil organic carbon (SOC) and nutrients. We investigated the influence of the gradient levels of mean annual precipitation (MAP from 300 to 900 mm) on soil microbial metabolism in an arid and semi-arid grassland region located in Loess Plateau, China and identified relationships between microbial metabolic limitations and the variation of soil organic matter (SOM). Microbial metabolism in this arid and semi-arid region was limited by soil C and phosphorus (P) or nitrogen (N). Microbial C and P limitations decreased with the increase of MAP. Microbial C and P limitations were lowest in the areas with MAPs of 700-900 mm, whereas N limitation was observed in the areas with MAPs >700 mm. The results of a variation-partitioning analysis and partial least squares path modeling indicated that the microbial C and N/P limitations on regional scales were mainly determined by climate factors (MAP and mean annual temperature (MAT)), followed by vegetation biomass and soil properties. The extents of soil drying-rewetting processing caused by different MAPs directly affected microbial nutrient limitation. Our results suggested that the influence of precipitation variation on microbial metabolic limitation strongly governed SOM stability and that an increase in the rate of SOM decomposition with increasing precipitation could be caused by increased microbial nutrient limitation. SOM may be most stable at a MAP of 700 mm in the arid and semi-arid regions (300-900 mm MAP) where microbial nutrient limitation was lowest. This study provided novel insights into the responses of soil microbial metabolism to precipitation change and is an important step toward understanding the mechanisms of SOM stability in an arid and semi-arid grassland ecosystem under scenarios of precipitation variation.


Assuntos
Bactérias/metabolismo , Clima Desértico , Nutrientes/análise , Chuva , Microbiologia do Solo , Solo/química , Carbono/análise , Microbiota , Nitrogênio/análise , Fósforo/análise
14.
Environ Sci Pollut Res Int ; 24(36): 28152-28164, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29018994

RESUMO

Enzymes in the soil are useful for assessing heavy metal soil pollution. We analyzed the activity of a number of enzymes, including urease, protease, catalase, and alkaline phosphatase, in three types of land (farmland, woodland, and grassland) to evaluate soil pollution by heavy metals (Pb, Zn, and Cd). Our results showed that the tested soil was polluted by a combination of Pb, Zn, and Cd, but the primary pollutant was Cd. An ecological dose analysis demonstrated that urease was the most sensitive enzyme to Pb and Cd in the farmland, and catalase and phosphatase were the most sensitive enzymes to Pb, Zn, and Cd in the woodland and grassland. The ecological risk of Cd (E Cd ) was the smallest in all three types of land, suggesting that Cd was the major metal inhibiting enzyme activity. Electrical conductivity (EC) was shown to be a negative regulator, while nitrogen, phosphorus, and clay contents were positive regulators of soil enzyme activity. The total enzyme index (TEI) inhibition rates in the woodland were 22.2 and 38.6% under moderate and heavy pollution, respectively, which were lower than those of the other two types of land. Therefore, woodlands might be the optimum land use choice in relieving heavy metal pollution. Taken together, this study identified the key metal pollutant inhibiting soil enzyme activity and suitable land use patterns around typical metal mine. These results provide possible improvement strategies to the phytomanagement of metal-contaminated land around world.


Assuntos
Monitoramento Ambiental , Chumbo/química , Mineração , Poluentes do Solo/química , Solo/química , Urease/metabolismo , Zinco/química , Silicatos de Alumínio , China , Argila , Monitoramento Ambiental/métodos
15.
Zhonghua Bing Li Xue Za Zhi ; 44(10): 729-33, 2015 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-26702531

RESUMO

OBJECTIVE: To study the prevalence of IgG4-positive plasma cells in Rosai-Dorfman disease and to assess the association between Rosai-Dorfman disease and IgG4-related sclerosing disease (IgG4-SD). METHODS: The clinicopathologic features of 12 tissue samples of Rosai-Dorfman disease (11 extranodal and one nodal) from nine patients were reviewed. The degree of fibrosis and occlusive phlebitis was studied by HE staining. The expression of IgG4 and IgG in plasma cells were studied by immunohistochemistry (EnVision) and quantitatively analyzed by medical image analysis system. RESULTS: Nine tissue samples showed different degree of fibrosis (four tissue samples were mild, one tissue sample was moderate and four tissue samples were severe) and two tissue samples showed occlusive phlebitis in the lesional tissue. Immunohistochemical study showed marked infiltration by IgG4-positive plasma cells (> 50 per high-power field) in four tissue samples, moderate infiltration (30 to 50 per high-power field) in two tissue samples, mild (10 to 29 per high-power field) in three cases and negative infiltration (< 10 per high-power field) in three tissue samples (P < 0.01). Three tissue samples fulfilled the diagnostic criteria of IgG4-SD (> 50 IgG4-positive plasma cells per high-power field and IgG4-to-IgG ratio > 40%), including one tissue sample each of Rosai-Dorfman disease in the left facial skin, above the left eye socket, and in the right parotid. CONCLUSIONS: Some cases of Rosai-Dorfman disease fulfill the diagnostic criteria and show the histologic features of IgG4-SD. They may represent members of the IgG4-SD spectrum. The detection of IgG4-positive plasma cells in the lesional tissues of Rosai-Dorfman disease may have clinical pathological significance.


Assuntos
Histiocitose Sinusal/diagnóstico , Imunoglobulina G/química , Plasmócitos/química , Fibrose , Histiocitose Sinusal/imunologia , Humanos , Imuno-Histoquímica , Flebite/patologia
16.
Biochem Pharmacol ; 83(4): 462-71, 2012 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-22155308

RESUMO

ß-Lactamase inhibitors (clavulanic acid, sulbactam, and tazobactam) contribute significantly to the longevity of the ß-lactam antibiotics used to treat serious infections. In the quest to design more potent compounds and to understand the mechanism of action of known inhibitors, 6ß-(hydroxymethyl)penicillanic acid sulfone (6ß-HM-sulfone) was tested against isolates expressing the class A TEM-1 ß-lactamase and a clinically important variant of the AmpC cephalosporinase of Pseudomonas aeruginosa, PDC-3. The addition of the 6ß-HM-sulfone inhibitor to ampicillin was highly effective. 6ß-HM-sulfone inhibited TEM-1 with an IC(50) of 12 ± 2 nM and PDC-3 with an IC(50) of 180 ± 36 nM, and displayed lower partition ratios than commercial inhibitors, with partition ratios (k(cat)/k(inact)) equal to 174 for TEM-1 and 4 for PDC-3. Measured for 20 h, 6ß-HM-sulfone demonstrated rapid, first-order inactivation kinetics with the extent of inactivation being related to the concentration of inhibitor for both TEM-1 and PDC-3. Using mass spectrometry to gain insight into the intermediates of inactivation of this inhibitor, 6ß-HM-sulfone was found to form a major adduct of +247 ± 5 Da with TEM-1 and +245 ± 5 Da with PDC-3, suggesting that the covalently bound, hydrolytically stabilized acyl-enzyme has lost a molecule of water (HOH). Minor adducts of +88 ± 5 Da with TEM-1 and +85 ± 5 Da with PDC-3 revealed that fragmentation of the covalent adduct can result but appeared to occur slowly with both enzymes. 6ß-HM-sulfone is an effective and versatile ß-lactamase inhibitor of representative class A and C enzymes.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/metabolismo , Sulbactam/análogos & derivados , Sulbactam/farmacologia , beta-Lactamases/metabolismo , Antibacterianos/química , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/genética , Domínio Catalítico , Simulação por Computador , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Escherichia coli/genética , Modelos Moleculares , Estrutura Molecular , Conformação Proteica , Pseudomonas aeruginosa/enzimologia , Sulbactam/química , Inibidores de beta-Lactamases , beta-Lactamases/genética
17.
J Hazard Mater ; 163(2-3): 563-7, 2009 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-18692313

RESUMO

The experiment was conducted to evaluate the effect of compost application on the immobilization and biotoxicity of Cd in winter wheat (Triticum aestivum L.) potted soils. Soils treated with various levels of Cd (0-50 mg Cd kg(-1) soil) were amended with 0, 30, 60 and 120 g compost kg(-1) soil. The fractions of Cd in soil were evaluated by a sequential extraction procedure. Compost application resulted in more than 70% lower soluble/exchangeable Cd (KNO(3)) but increased the concentration of organic-bound (NaOH) and inorganic precipitates (EDTA) Cd in soils. Addition of compost was effective in reducing the phytotoxicity of Cd by decreasing more than 50% Cd uptake by wheat tissue and improving wheat growth. Alleviation of Cd phytotoxicity by compost was attributed primarily to the increase of soil pH, complexation of Cd by the organic matter and coprecipitation with P content. Compost was effective in the immobilization of Cd in soils and can be used to remediate Cd-contaminated soils.


Assuntos
Cádmio/isolamento & purificação , Esterco , Poluentes do Solo/isolamento & purificação , Triticum , Cádmio/análise , Cádmio/toxicidade , Concentração de Íons de Hidrogênio , Fósforo , Solo
18.
Clin Sci (Lond) ; 116(11): 819-26, 2009 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-19086920

RESUMO

The aim of the present study was to determine whether EMMPRIN (extracellular matrix metalloproteinase inducer) is present and is up-regulated in human aneurysmal aortas, and to assess a possible association with AngII (angiotensin II)-induced aneurysm formation. The presence of EMMPRIN was assessed in 41 surgical specimens from patients with a TAA (thoracic aortic aneurysm) (Type A aortic dissection, n=12; Type B aortic dissection, n=7; and TAA without dissection, n=7) or an AAA (abdominal aortic aneurysm, n=15) by immunohistochemistry. EMMPRIN expression in aortic aneurysm tissues was compared with 12 aortas obtained during autopsy (free of any vascular diseases), and scored for both staining intensity and the percentage of vascular cells stained. EMMPRIN protein levels in cultured human aortic SMCs (smooth muscle cells) following stimulation of AngII were analysed by Western blotting. Significant EMMPRIN immunoreactivity was detected in aortic aneurysm lesions from patients with TAAs and AAAs. In the aneurysmal wall, alpha-actin-positive SMCs were the main source of EMMPRIN. The frequency of EMMPRIN overexpression was significantly higher (P=0.026) in TAAs with dissection (68.4%) than TAAs without dissection (14.3%). AngII stimulation up-regulated the expression of EMMPIRN in cultured human aortic SMCs, which was suppressed by the addition of the AT1R (AngII type 1 receptor) antagonist losartan. In conclusion, the present study is the first to report the expression of EMMPRIN in aortic aneurysmal diseases, and we speculate that EMMPRIN may be important in the pathogenesis of these diseases. Whether these abnormalities are potential therapeutic targets deserve further investigation.


Assuntos
Angiotensina II/farmacologia , Aneurisma da Aorta Abdominal/metabolismo , Dissecção Aórtica/metabolismo , Basigina/metabolismo , Músculo Liso Vascular/metabolismo , Adulto , Idoso , Dissecção Aórtica/patologia , Aneurisma da Aorta Abdominal/patologia , Células Cultivadas , Feminino , Humanos , Imuno-Histoquímica , Masculino , Pessoa de Meia-Idade , Miócitos de Músculo Liso/metabolismo , Regulação para Cima
20.
J Zhejiang Univ Sci B ; 9(6): 500-5, 2008 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-18543405

RESUMO

The coexistence of myelolipoma within adrenal cortical adenoma is extremely rare, for both tumors present usually as separate entities. There are only 16 such cases reported worldwide. To the best of our knowledge, the case we reported here is the first one of myxoid adrenal cortical adenoma associated with myelolipoma reported. A 32-year-old Chinese woman with 4-year history of hypertension was presented in our study. Computed tomography (CT) of the abdomen showed a large heterogeneously-enhancing mass (4.5 cm in diameter) in the left suprarenal region. Clinical history and laboratory results suggest a metabolic disorder as Conn's syndrome. The patient underwent a left adrenalectomy, and a histopathological study confirmed the mass to be a myxoid adrenal cortical adenoma containing myelolipoma. The patient was postoperatively well and discharged uneventfully. In the present case report, we also discuss the etiology of simultaneous myelolipoma and adrenal adenoma associated with Conn's syndrome, and the methods of the diagnosis and differential diagnosis.


Assuntos
Neoplasias do Córtex Suprarrenal/complicações , Adenoma Adrenocortical/complicações , Hiperaldosteronismo/complicações , Mielolipoma/complicações , Neoplasias Primárias Múltiplas/complicações , Neoplasias do Córtex Suprarrenal/diagnóstico , Neoplasias do Córtex Suprarrenal/patologia , Adenoma Adrenocortical/diagnóstico , Adenoma Adrenocortical/patologia , Adulto , Biomarcadores Tumorais/metabolismo , Feminino , Humanos , Inibinas/metabolismo , Mielolipoma/diagnóstico , Mielolipoma/patologia , Neoplasias Primárias Múltiplas/diagnóstico , Neoplasias Primárias Múltiplas/patologia , Sinaptofisina/metabolismo , Tomografia Computadorizada por Raios X , Vimentina/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA