Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 53
Filtrar
1.
Clin Pediatr (Phila) ; 61(9): 622-628, 2022 10.
Artigo em Inglês | MEDLINE | ID: mdl-35673796

RESUMO

Constipation is common in general pediatrics and often results in potentially unnecessary referrals to pediatric gastroenterology. We hypothesized that a clinical decision-making tool would support primary care providers to manage pediatric constipation, improve workflow, and prevent unnecessary subspecialty care. In this pilot quality improvement initiative, a multidisciplinary team completed a root cause analysis related to challenges with the care of pediatric constipation. The results informed the development of interventions including a Clinical Decision Support tool and patient educational materials embedded within an existing order-set in the electronic health record, which we implemented in our primary care network. The use of the updated order-set continues to increase monthly, and there is reported improved workflow and increased confidence by providers. These interventions demonstrated that it is feasible to implement tools to support primary care clinicians in their management of pediatric patients with constipation.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Pediatria , Criança , Constipação Intestinal/diagnóstico , Constipação Intestinal/terapia , Humanos , Atenção Primária à Saúde , Encaminhamento e Consulta
2.
Nat Food ; 2(2): 104-109, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-37117407

RESUMO

The majority of genetically modified (GM) crops are produced for livestock consumption, whereas minimal attention has been given to GM crops for direct human consumption. In South Africa, GM white maize has been grown for direct human consumption alongside GM yellow maize and conventional hybrid (CH) maize for livestock feed since 1999. Here we investigate yield differences between GM white, GM yellow and CH maize across 106 locations, 28 years, 491 cultivars, and 49,335 dryland and 9,617 irrigated observations in South Africa. GM maize increased mean yields over CH by 0.42 metric tons (Mt) ha-1 and reduced yield risk. We show that GM white maize increased yields by 0.60 Mt ha-1 and GM yellow maize by 0.27 Mt ha-1 compared with CH maize. GM yield gains were similar for dry and irrigated production. Our study highlights the potential impacts of growing GM grain crops for human consumption in African countries.

3.
Nat Commun ; 11(1): 4408, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32879311

RESUMO

Understanding extreme weather impacts on staple crops such as wheat is vital for creating adaptation strategies and increasing food security, especially in dryland cropping systems across Southern Africa. This study analyses heat impacts on wheat using daily weather information and a dryland wheat dataset for 71 cultivars across 17 locations in South Africa from 1998 to 2014. We estimate temperature impacts on yields in extensive regression models, finding that extreme heat drives wheat yield losses, with an additional 24 h of exposure to temperatures above 30 °C associated with a 12.5% yield reduction. Results from a uniform warming scenario of +1 °C show an average wheat yield reduction of 8.5%, which increases to 18.4% and 28.5% under +2 and +3 °C scenarios. We also find evidence of differences in heat effects across cultivars, which suggests warming impacts may be reduced through the sharing of gene pools amongst wheat breeding programs.


Assuntos
Adaptação Fisiológica , Produtos Agrícolas , Triticum , Cruzamento/métodos , Mudança Climática , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/fisiologia , Genótipo , Aquecimento Global , Temperatura Alta , África do Sul , Triticum/genética , Triticum/crescimento & desenvolvimento , Triticum/fisiologia
4.
PLoS One ; 14(7): e0219199, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31295286

RESUMO

Bacterial Panicle Blight (BPB), caused by Burkholderia glumae, is a bacterial disease in rice (Oryza sativa) that reduces rice yield and quality for producers and consequently creates higher market prices for consumers. BPB is caused by the simultaneous occurrence of high daily minimum temperatures (~22°C) and relative humidity (~77%), which may increase under the current scenario of global warming. This study hypothesized that the economic damage from warming may cause an increase in economic losses, though at a decreasing rate per degree. Thus, this study estimates the yield losses associated with BPB occurrences at the county level in the Mid-South United States (US) for annual rice production in 2003-2013 and under +1-3°C warming scenarios using daily weather information with appropriate thresholds. From the estimated losses, the total production potential of a BPB-resistant rice was quantified using a spatial equilibrium trade model to further estimate market welfare changes with the counterfactual scenario that all US county-level rice production were BPB resistant. Results from the study indicate that the alleviation of BPB would represent a $69 million USD increase in consumer surplus in the US and a concomitant increase in rice production that would feed an additional 1.46 million people annually assuming a global average consumption of 54 Kg per person. Under the 1°C warming scenario, BPB occurrences and production losses would cause price increases for rice and subsequently result in a $112 million USD annual decrease in consumer surplus in the US and a loss of production equivalent to feeding 2.17 million people. Under a 3°C warming scenario, production losses due to BPB cause an annual reduction of $204 million USD in consumer surplus in the US, and a loss in production sufficient to feed 3.98 million people a year. As global warming intensifies, BPB could become a more common and formidable rice disease to combat, and breeding for BPB resistance would be the primary line-of-defense as currently no effective chemical options are available. The results of this study inform agriculturalists, policymakers, and economists about the value of BPB-resistance in the international rice market and also help support efforts to focus future breeding toward climate change impact resilience.


Assuntos
Burkholderia/patogenicidade , Aquecimento Global , Oryza/microbiologia , Doenças das Plantas/microbiologia , Cruzamento , Burkholderia/crescimento & desenvolvimento , Mudança Climática , Temperatura Alta , Oryza/crescimento & desenvolvimento , Estados Unidos
5.
PLoS One ; 14(6): e0217230, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31173598

RESUMO

Concerns about the use of child labor in West African cocoa production became widespread in the early 2000s in many high-income countries. In 2015 in Ghana, 91.8% (or a total of 878,595) of the children working in the cocoa sector were involved in a form of hazardous work. Child labor in cocoa production is not just a symptom of poverty but also a contributing factor, as children often forgo a formal education to work in cocoa orchards. Current Ghanaian law prohibits child labor, but, with many cocoa households living in poverty, child labor becomes a necessity for survival, and as such, current child labor laws are rarely enforced. Therefore, an effective policy that eliminates child labor could compensate farmers by providing an economic incentive. In this paper, we develop and calibrate a farm household model to estimate the cocoa price premium necessary to eliminate child labor from cocoa production while leaving the farm household welfare unchanged. This welfare-neutral price premium removes the negative effects of eliminating child labor for the farm household. Varying degrees of child labor exists, with certain forms posing a greater risk to children's wellbeing. The results show that eliminating the worst forms of child labor would require a cocoa price premium of 2.81% and eliminating regular work (non-hazardous work but over the maximum hours allowed for a child) and the worst forms would require an 11.81% premium, which could be paid for by the well-established Ghanaian Cocoa Marketing Board. An incentive for the Cocoa Marketing Board to pay the price premium and monitor and enforce this policy would be the ability to differentiate their cocoa as child-labor free and not lose market share to countries who cannot currently certify this practice.


Assuntos
Trabalho Infantil , Chocolate/economia , Motivação , Adolescente , Agricultura/economia , Criança , Características da Família , Gana , Humanos
6.
J Hazard Mater ; 360: 461-470, 2018 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-30142597

RESUMO

This study investigated the coupling of sulfate radical generating oxidants, (persulfate, PS and peroxymonosulfate, PMS) with TiO2 photocatalysis for the degradation of microcystin-LR (MC-LR). Treatment efficiency was evaluated by estimating the electrical energy per order (EEO). Oxidant addition at 4 mg/L reduced the energy requirements of the treatment by 60% and 12% for PMS and PS, respectively compared with conventional photocatalysis. Quenching studies indicated that both sulfate and hydroxyl radicals contributed towards the degradation of MC-LR for both oxidants, while Electron Paramagnetic Resonance (EPR) studies confirmed that the oxidants prolonged that lifetime of both radicals (concentration maxima shifted from 10 to 20 min), allowing for bulk diffusion and enhancing cyanotoxin removal. Structural identification of transformation products (TPs) formed during all treatments, indicated that early stage degradation of MC-LR occurred mainly on the aromatic ring and conjugated carbon double bonds of the ADDA amino acid. In addition, simultaneous hydroxyl substitution of the aromatic ring and the conjugated double carbon bonds of ADDA (m/z = 1027.5) are reported for the first time. Oxidant addition also increased the rates of formation/degradation of TPs and affected the overall toxicity of the treated samples. The detoxification and degradation order of the treatments was UVA/TiO2/PMS > UVA/TiO2/PS>> UVA/TiO2.


Assuntos
Microcistinas/química , Oxidantes/química , Peróxidos/química , Compostos de Potássio/química , Sulfatos/química , Titânio/química , Poluentes Químicos da Água/química , Catálise , Toxinas Marinhas , Fotólise , Titânio/efeitos da radiação , Raios Ultravioleta , Purificação da Água
7.
Plant Biotechnol J ; 14(1): 4-7, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26242818

RESUMO

India has more than 215 million food-insecure people, many of whom are farmers. Genetically modified (GM) crops have the potential to alleviate this problem by increasing food supplies and strengthening farmer livelihoods. For this to occur, two factors are critical: (i) a change in the regulatory status of GM crops, and (ii) consumer acceptance of GM foods. There are generally two classifications of GM crops based on how they are bred: cisgenically bred, containing only DNA sequences from sexually compatible organisms; and transgenically bred, including DNA sequences from sexually incompatible organisms. Consumers may view cisgenic foods as more natural than those produced via transgenesis, thus influencing consumer acceptance. This premise was the catalyst for our study--would Indian consumers accept cisgenically bred rice and if so, how would they value cisgenics compared to conventionally bred rice, GM-labelled rice and 'no fungicide' rice? In this willingness-to-pay study, respondents did not view cisgenic and GM rice differently. However, participants were willing-to-pay a premium for any aforementioned rice with a 'no fungicide' attribute, which cisgenics and GM could provide. Although not significantly different (P = 0.16), 76% and 73% of respondents stated a willingness-to-consume GM and cisgenic foods, respectively.


Assuntos
Participação da Comunidade , Oryza/genética , Humanos , Índia , Plantas Geneticamente Modificadas , Inquéritos e Questionários
9.
PLoS One ; 10(5): e0126060, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25973946

RESUMO

Both cisgenesis and transgenesis are plant breeding techniques that can be used to introduce new genes into plant genomes. However, transgenesis uses gene(s) from a non-plant organism or from a donor plant that is sexually incompatible with the recipient plant while cisgenesis involves the introduction of gene(s) from a crossable--sexually compatible--plant. Traditional breeding techniques could possibly achieve the same results as those from cisgenesis, but would require a much larger timeframe. Cisgenesis allows plant breeders to enhance an existing cultivar more quickly and with little to no genetic drag. The current regulation in the European Union (EU) on genetically modified organisms (GMOs) treats cisgenic plants the same as transgenic plants and both are mandatorily labeled as GMOs. This study estimates European consumers' willingness-to-pay (WTP) for rice labeled as GM, cisgenic, with environmental benefits (which cisgenesis could provide), or any combination of these three attributes. Data were collected from 3,002 participants through an online survey administered in Belgium, France, the Netherlands, Spain and the United Kingdom in 2013. Censored regression models were used to model consumers' WTP in each country. Model estimates highlight significant differences in WTP across countries. In all five countries, consumers are willing-to-pay a premium to avoid purchasing rice labeled as GM. In all countries except Spain, consumers have a significantly higher WTP to avoid consuming rice labeled as GM compared to rice labeled as cisgenic, suggesting that inserting genes from the plant's own gene pool is more acceptable to consumers. Additionally, French consumers are willing-to-pay a premium for rice labeled as having environmental benefits compared to conventional rice. These findings suggest that not all GMOs are the same in consumers' eyes and thus, from a consumer preference perspective, the differences between transgenic and cisgenic products are recommended to be reflected in GMO labeling and trade policies.


Assuntos
Comportamento do Consumidor , Alimentos Geneticamente Modificados , Oryza/genética , Plantas Geneticamente Modificadas/genética , Comércio , União Europeia , Feminino , Alimentos Geneticamente Modificados/economia , Humanos , Masculino
10.
Glob Chang Biol ; 21(4): 1668-78, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25379616

RESUMO

Flooded rice is grown across wide geographic boundaries from as far north as Manchuria and as far south as Uruguay and New South Wales, primarily because of its adaptability across diverse agronomic and climatic conditions. Salt-stress damage, a common occurrence in delta and coastal rice production zones, could be heightened by the interactions between high temperature and relative humidity (vapor pressure deficit--VPD). Using temporal and spatial observations spanning 107 seasons and 19 rice-growing locations throughout India with varying electrical conductivity (EC), including coastal saline, inland saline, and alkaline soils, we quantified the proportion of VPD inducing salinity damage in rice. While controlling for time-invariant factors such as trial locations, rice cultivars, and soil types, our regression analysis indicates that EC has a nonlinear detrimental effect on paddy rice yield. Our estimates suggest these yield reductions become larger at higher VPD. A one standard deviation (SD) increase in EC from its mean value is associated with 1.68% and 4.13% yield reductions at median and maximum observed VPD levels, respectively. Yield reductions increase roughly sixfold when the one SD increase is taken from the 75th percentile of EC. In combination, high EC and VPD generate near catastrophic crop loss as predicted yield approaches zero. If higher VPD levels driven by global warming materialize in conjunction with rising sea levels or salinity incursion in groundwater, this interaction becomes an important and necessary predictor of expected yield losses and global food security.


Assuntos
Agricultura , Mudança Climática , Oryza/crescimento & desenvolvimento , Cloreto de Sódio/metabolismo , Pressão de Vapor , Geografia , Temperatura Alta , Índia , Análise de Regressão , Salinidade , Estações do Ano , Estresse Fisiológico
11.
Immunology ; 144(4): 649-60, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25346485

RESUMO

Dendritic cells (DCs) are potent antigen-presenting cells necessary to establish effective adaptive immune responses. The cytokine environment that exists at the time of DC differentiation may be an important but often ignored determinant in the phenotypic and functional properties of DCs. Interleukin-27 (IL-27) is a unique cytokine that has both inflammatory and immune suppressive activities. Although it can both promote and oppose activity of different T-cell subsets, mostly anti-inflammatory activity has been described toward macrophages and DCs. However, the specific effect of IL-27 during DC differentiation and how that may change the nature of the antigen-presenting cell has not been investigated. In this report, we show that IL-27 treatment during monocyte-derived DC differentiation enhanced the ability to process antigens and stimulate T-cell activity. DCs differentiated in the presence of IL-27 showed enhanced acidification of latex bead-containing phagosomes that was consistent with elevated expression of vacuolar-ATPases. This resulted in inhibition of intracellular growth of Staphylococcus aureus. In addition, the levels of MHC class II surface expression were higher in DCs differentiated in the presence of IL-27. Production of IL-12 was also significantly increased during S. aureus infection of IL-27-differentiated DCs. The net effect of these activities was enhanced CD4(+) T-cell proliferation and T helper type 1 cytokine production. These findings are important to a wide number of immunological contexts and should be considered in the development of future vaccines.


Assuntos
Apresentação de Antígeno/efeitos dos fármacos , Linfócitos T CD4-Positivos/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Dendríticas/efeitos dos fármacos , Interleucina-27/farmacologia , Ativação Linfocitária/efeitos dos fármacos , Monócitos/efeitos dos fármacos , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Técnicas de Cocultura , Células Dendríticas/imunologia , Células Dendríticas/metabolismo , Células Dendríticas/microbiologia , Antígenos de Histocompatibilidade Classe II/imunologia , Antígenos de Histocompatibilidade Classe II/metabolismo , Humanos , Concentração de Íons de Hidrogênio , Interleucina-12/imunologia , Interleucina-12/metabolismo , Monócitos/imunologia , Monócitos/metabolismo , Fagossomos/efeitos dos fármacos , Fagossomos/imunologia , Fagossomos/metabolismo , Transdução de Sinais , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/crescimento & desenvolvimento , Staphylococcus aureus/imunologia , Células Th1/efeitos dos fármacos , Células Th1/imunologia , Células Th1/metabolismo , Fatores de Tempo
12.
Immunology ; 141(1): 39-51, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23981064

RESUMO

Tuberculosis (TB) remains a major global health problem accounting for millions of deaths annually. Approximately one-third of the world's population is infected with the causative agent Mycobacterium tuberculosis. The onset of an adaptive immune response to M. tuberculosis is delayed compared with other microbial infections. This delay permits bacterial growth and dissemination. The precise mechanism(s) responsible for this delay have remained obscure. T-cell activation is preceded by dendritic cell (DC) migration from infected lungs to local lymph nodes and synapsis with T cells. We hypothesized that M. tuberculosis may impede the ability of DCs to reach lymph nodes and initiate an adaptive immune response. We used primary human DCs to determine the effect of M. tuberculosis on expression of heterodimeric integrins involved in cellular adhesion and migration. We also evaluated the ability of infected DCs to adhere to and migrate through lung endothelial cells, which is necessary to reach lymph nodes. We show by flow cytometry and confocal microscopy that M. tuberculosis-infected DCs exhibit a significant reduction in surface expression of the ß(2) (CD18) integrin. Distribution of integrin ß(2) is also markedly altered in M. tuberculosis-infected DCs. A corresponding reduction in the αL (CD11a) and αM (CD11b) subunits that associate with integrin ß(2) was also observed. Consistent with reduced integrin surface expression, we show a significant reduction in adherence to lung endothelial cell monolayers and migration towards lymphatic chemokines when DCs are infected with M. tuberculosis. These findings suggest that M. tuberculosis modulates DC adhesion and migration to increase the time required to initiate an adaptive immune response.


Assuntos
Movimento Celular/imunologia , Quimiocinas/imunologia , Células Dendríticas/imunologia , Regulação da Expressão Gênica/imunologia , Integrinas/imunologia , Mycobacterium tuberculosis/imunologia , Tuberculose/imunologia , Adolescente , Adesão Celular/imunologia , Células Dendríticas/patologia , Feminino , Humanos , Masculino , Tuberculose/patologia
13.
Water Sci Technol ; 63(6): 1137-42, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21436548

RESUMO

Microcystins (MC) and nodularin (NOD) are common contaminants of drinking water around the world and due to their significant health impact it is important to explore suitable approaches for their removal. Unfortunately, these toxins are not always removed by conventional water treatments. One of the most exciting areas that hold promise for a successful and cost effective solution is bioremediation of microcystins. Recent work resulted in successful isolation and characterisation of 10 novel bacterial strains (Rhodococcus sp., Arthrobacter spp. and Brevibacterium sp.) capable of metabolizing microcystin-LR (MC-LR) in a Biolog MT2 assay. The work presented here aims to further investigate and evaluate the metabolism and the degradation of multiple microcystins (MC-LR, MC-LF, MC-LY, MC-LW and MC-RR) and nodularin by the bacterial isolates. A total of five bacterial isolates representing the three genera were evaluated using Biolog MT2 assay with a range of MCs where they all demonstrated an overall metabolism on all MCs and NOD. Subsequently, the results were confirmed by observing the degradation of the range of toxins in a separate batch experiment.


Assuntos
Bactérias/classificação , Bactérias/metabolismo , Microcistinas/metabolismo , Microbiologia da Água , Purificação da Água/métodos , Microcistinas/química , Água/química
14.
Syst Appl Microbiol ; 29(2): 156-64, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16464697

RESUMO

A previous pioneering study of freshwater bodies in Sri Lanka revealed the presence of toxic cyanobacteria in three out of four water bodies tested. It was therefore important to perform a more detailed investigation into the presence of cyanobacteria and their toxins throughout Sri Lanka. The country has a long history of well-planned water management with the agricultural economy and drinking water supply still dependent on thousands of man-made tanks. Seventeen reservoirs from different user categories and different climatic zones were selected to study variations in phytoplankton communities with relation to major nutrients, with particular emphasis on cyanobacteria. The study was carried out during a two-year period and heavy growths or blooms of cyanobacteria observed during the study period were tested for microcystins. The results clearly categorised the 17 reservoirs into four groups parallel to the classification based on the user categories of water bodies. Biomass of total phytoplankton, the abundance of cyanobacteria, the dominance of Microcystis spp. and concentration of nitrate (N) and total phosphorous (P) were the lowest in drinking water bodies and the highest in aesthetic water bodies. Irrigation water bodies showed the second lowest values for phytoplankton biomass, and concentration of N and P, while hydropower reservoirs showed the second highest values for the same parameters. The fraction of cyanobacteria in irrigation waters was higher than that in hydropower reservoirs, but surprisingly the dominance of Microcystis spp. was reversed. Possible reasons for these variations are discussed. More than half of the bloom material tested contained microcystins up to 81microgl(-1). Our findings indicate the potential for high-risk situations due to toxigenic cyanobacterial blooms in susceptible freshwaters of Sri Lanka.


Assuntos
Cianobactérias/isolamento & purificação , Microbiologia da Água , Toxinas Bacterianas/análise , Toxinas Bacterianas/biossíntese , Cianobactérias/metabolismo , Água Doce , Microcystis/isolamento & purificação , Microcystis/metabolismo , Plâncton , Sri Lanka
15.
Epilepsy Behav ; 6(1): 59-62, 2005 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-15652735

RESUMO

Complementary and alternative medicines (CAMs) are increasingly used by patients in the Western world. Some of the most popular herbal remedies are known to act on the cytochrome P450 system, with potential effects on antiepileptic drug (AED) levels. Few studies have explored their use in people with epilepsy. We surveyed 400 patients attending epilepsy clinics in Greater Manchester. Thirty-four percent of our patients had used or were using CAMs; the majority had not told their doctor. Use of CAMs was not predicted by age, sex, seizure frequency, number of AEDs, or dissatisfaction with conventional medicine. Patients who had gone onto higher education were significantly (P < 0.05) more likely to have used or be using CAMs. The majority of patients did not use CAMs for their epilepsy but for general health purposes. Most patients stated that CAMs had little or no effect on seizure frequency or severity.


Assuntos
Terapias Complementares/estatística & dados numéricos , Uso de Medicamentos/estatística & dados numéricos , Epilepsia/terapia , Pesquisas sobre Atenção à Saúde , Adulto , Anticonvulsivantes/uso terapêutico , Atitude Frente a Saúde , Estudos de Coortes , Terapias Complementares/métodos , Escolaridade , Epilepsia/epidemiologia , Feminino , Humanos , Masculino , Aceitação pelo Paciente de Cuidados de Saúde
16.
FEMS Microbiol Lett ; 210(2): 257-61, 2002 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-12044684

RESUMO

Antibody phage display libraries (Griffin and Tomlinson I) displaying antibody genes and maintained and amplified in Escherichia coli were used to isolate antibodies to the hapten target microcystin LR (1000 Da) conjugated to either bovine serum albumin or keyhole limpet haemocyanin. In competition enzyme-linked immunosorbent assay, bacterially expressed antibodies selected via the Griffin library showed at least 300 times greater sensitivity than those isolated from the Tomlinson library, for free microcystin. Bacterially expressed phage antibody libraries provide a rapid and relatively easy route for the selection of monoclonal antibodies specific for even the most difficult of antigenic targets such as free haptens.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/isolamento & purificação , Especificidade de Anticorpos , Escherichia coli/genética , Haptenos/imunologia , Biblioteca de Peptídeos , Peptídeos Cíclicos/imunologia , Anticorpos Monoclonais/genética , Ligação Competitiva , Clonagem Molecular , Ensaio de Imunoadsorção Enzimática , Haptenos/química , Hemocianinas , Humanos , Toxinas Marinhas , Microcistinas , Peptídeos Cíclicos/química , Soroalbumina Bovina
17.
Toxicon ; 39(9): 1411-20, 2001 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-11384731

RESUMO

The cyanobacterial toxins microcystins are known to affect a number of processes in plant tissues, and their presence in water used for irrigation may have considerable impact on the growth and development of crop plants. In this study, two plant bioassays were employed to investigate the phytotoxic effects of microcystins. A plant tissue culture assay revealed that the growth and chlorophyll content of Solanum tuberosum L. cultures was inhibited at microcystin-LR concentrations of 0.005 and 0.05 microg x cm(-3), respectively. A previously developed bioassay was also employed to determine the effects of three commonly occurring microcystin variants on the growth of Synapis alba L. seedlings. Microcystins-LR, -RR, and -LF inhibited the growth of seedlings, with GI50 values of 1.9, 1.6 and 7.7 microg x ml(-1), respectively. The growth of Phaseolus vulgaris was also examined in the presence of microcystin-LR. The toxin was found to have little effect on growth for up to 18 days, but impaired the development of the roots of exposed plants, causing them to take up approximately 30% less growth medium than those grown in the absence of toxin. Microcystin was also detected in the tissues of exposed plants using a commercially available ELISA kit, suggesting that the uptake of these toxins by edible plants may have significant implications for human health.


Assuntos
Toxinas Bacterianas/toxicidade , Peptídeos Cíclicos/toxicidade , Desenvolvimento Vegetal , Reguladores de Crescimento de Plantas/toxicidade , Toxinas Bacterianas/análise , Toxinas Bacterianas/metabolismo , Ensaio de Imunoadsorção Enzimática , Toxinas Marinhas , Microcistinas , Peptídeos Cíclicos/análise , Peptídeos Cíclicos/metabolismo , Reguladores de Crescimento de Plantas/análise , Reguladores de Crescimento de Plantas/metabolismo , Plantas/química , Plantas/metabolismo
18.
J Chromatogr A ; 912(2): 191-209, 2001 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-11330790

RESUMO

Microcystins are an increasingly important group of bioactive compounds produced by a number of mainly planktonic cyanobacteria. They are a family of cyclic heptapeptides that cause both acute and chronic toxicity. Purified microcystins are utilised in a range of research applications including toxicological and biochemical studies, development of detection systems and the investigation of water treatment strategies. The commercial availability of purified microcystins is still relatively limited and for many projects the cost of their purchase prohibitive. The purification of microcystins from both bloom material and laboratory cultures is reviewed including a discussion on extraction, separation, and the determination of purity and yield.


Assuntos
Peptídeos Cíclicos/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Cromatografia por Troca Iônica , Cromatografia em Camada Fina , Cianobactérias/química , Microcistinas
19.
FEMS Microbiol Lett ; 193(1): 83-8, 2000 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-11094283

RESUMO

Single-chain antibody fragments against the cyanobacterial hepatotoxin microcystin-LR were isolated from a naive human phage display library and expressed in Escherichia coli. In competition enzyme-linked immunosorbent assay (ELISA), the most sensitive antibody clone selected from the library detected free microcystin-LR with an IC(50) value of 4 microM. It was found to cross react with three other microcystin variants - microcystin-RR, microcystin-LW and microcystin-LF - and detected microcystins in extracts of the cyanobacterium Microcystis aeruginosa, found to contain the toxins by high-performance liquid chromatography (HPLC). The quantification of microcystins in these extracts by ELISA and HPLC showed good correlation. Although the antibody isolated in this study was considerably less sensitive than the polyclonal and monoclonal antibodies already available for microcystin detection, phage display technology represents a cheaper, more rapid alternative for the production of anti-microcystin antibodies than the methods currently in use.


Assuntos
Cianobactérias/química , Fragmentos de Imunoglobulinas/imunologia , Peptídeos Cíclicos/análise , Peptídeos Cíclicos/imunologia , Especificidade de Anticorpos , Cromatografia Líquida de Alta Pressão , Reações Cruzadas , Ensaio de Imunoadsorção Enzimática , Humanos , Fragmentos de Imunoglobulinas/genética , Fragmentos de Imunoglobulinas/isolamento & purificação , Toxinas Marinhas , Microcistinas , Biblioteca de Peptídeos , Peptídeos Cíclicos/isolamento & purificação , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/isolamento & purificação
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...