Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 17 de 17
Filtrar
1.
Pediatr Emerg Care ; 40(7): e94-e104, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38355126

RESUMO

OBJECTIVES: More than 19 million adolescents seek care in the emergency department (ED) annually. We aimed to describe the knowledge, attitudes, and behaviors related to confidential adolescent care among pediatric ED physicians. METHODS: We conducted a cross-sectional questionnaire of US physician members of the Pediatric Emergency Medicine Collaborative Research Committee survey listserv. The 24-item questionnaire assessed familiarity with adolescent confidentiality laws, attitudes toward providing confidential care, frequency of discussing behavioral health topics confidentially, and factors influencing the decision to provide confidential care. We dichotomized Likert responses and used χ 2 to compare subgroups. RESULTS: Of 476 eligible physicians, 151 (32%) participated. Most (91. 4%) had completed pediatric emergency medicine fellowship. More participants reported familiarity with all sexual health-related laws compared with all mental health-related laws (64% vs 49%, P < 0.001). The median age at which participants thought it was important to begin routinely providing confidential care was 12 years; 9% thought confidential interviews should not be routinely conducted until older adolescence or at all. Their decision to provide confidential care was influenced by the following: chief complaint (97%), time (43%), language (24%), presence of family (23%) or friends (14%), and space (22%). CONCLUSIONS: Respondents reported moderate familiarity with adolescent confidentiality laws. Although they viewed confidential care as something they were comfortable providing, the likelihood of doing so varied. Barriers to confidential care were influenced by their assessment of adolescents' behavioral health risk, which may contribute to health inequity. Future efforts are needed to develop strategies that augment confidential ED care for adolescents.


Assuntos
Confidencialidade , Serviço Hospitalar de Emergência , Conhecimentos, Atitudes e Prática em Saúde , Humanos , Adolescente , Estudos Transversais , Feminino , Masculino , Inquéritos e Questionários , Atitude do Pessoal de Saúde , Médicos/psicologia , Estados Unidos , Adulto , Pessoa de Meia-Idade , Criança
2.
Curr Opin Pediatr ; 35(3): 331-336, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36876657

RESUMO

PURPOSE OF REVIEW: Transgender and Gender Diverse (TGD) youth represent a growing subset of pediatric patients who are at increased risk for harmful health outcomes. Consideration of these risks during emergency encounters may decrease these undesired, sometimes fatal, adverse events. RECENT FINDINGS: Gender affirmative care of TGD youth is considered a basic healthcare right as noted by several academic societies including the American Academy of Pediatrics, the American Academy of Child and Adolescent Psychiatry, and the American Psychological Association [1-3] ( Table 1 ). Withholding gender affirmative care can lead to undesired health outcomes including but not limited to an increased incidence of mood disorders, self-injurious behavior, suicidal ideation, sexually transmitted diseases, and delayed presentations of treatable illness. TGD youth often access acute care settings, yet many feel apprehensive due to prior negative experiences or fear of discrimination. Practitioners are also often unaware as to how to effectively provide this type of healthcare. SUMMARY: Acute care settings provide a unique and impactful environment to provide evidence-based, gender-affirming care that can make patients feel validated, mitigate future care avoidance, and minimize negative downstream health effects. In this review, we have consolidated high yield health considerations regarding TGD youth for acute care and emergency providers to deliver optimal care for this population.


Assuntos
Serviços Médicos de Emergência , Infecções Sexualmente Transmissíveis , Pessoas Transgênero , Humanos , Adolescente , Criança , Pessoas Transgênero/psicologia , Identidade de Gênero , Atenção à Saúde
3.
Pediatr Emerg Care ; 38(5): e1237-e1244, 2022 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-35380752

RESUMO

OBJECTIVES: This study aimed to evaluate trends in pediatric emergency department (ED) 72-hour return visits and factors associated with return visits. METHODS: We performed a cross-sectional study from 2002 to 2018 using the National Hospital Ambulatory Medical Care Survey, a complex survey of nonfederal US ED encounters. Patients 18 years or older were excluded. Our outcome of interest was 72-hour return ED encounter. We assessed changes in proportions of return visits over time using the Spearman rank-correlation test. We performed survey-weighted univariable and multivariable logistic regressions to identify factors associated with 72-hour return visit status. RESULTS: A total of 501 million (95% confidence interval [CI], 452-551 million) pediatric survey-weighted ED encounters occurred during the 17-year study period, of which 14,353,697 (3.2%; 95% CI, 2.7%-3.7%) represented 72-hour return visits. The proportion of pediatric ED return visits increased from 22.9 to 36.5 per 1000 pediatric encounters over the study period (ρ = 0.68, P < 0.01). Most return visits were of lower acuity (73.0%; 95% CI, 68.6%-11.5%), and 8.1% (95% CI, 6.3%-9.9%) of return visits were admitted to the hospital or transferred to a different facility. In multivariable analyses, older age, abnormal heart rate, and abnormal temperature had lower adjusted odds ratio (aOR) of 72-hour return visits compared with encounters not classified as return visit. Complaints of returning for test results, treatment, and diagnostic screening/administrative purposes were associated with a higher aOR of return visit. Admission/transfer (in comparison with discharge) had a higher odds of return visit status in univariable (odds ratio, 1.59; 95% CI, 1.24-2.04) and multivariable (aOR, 1.31; 95% CI, 1.03-1.68) analyses. CONCLUSIONS: The proportion of 72-hour US pediatric ED return visits is increasing over time. Return visit status was associated with admission/transfer, but otherwise with markers of lower patient acuity. These findings inform quality improvement efforts aimed at improving pediatric transition to outpatient care after an ED encounter.


Assuntos
Serviço Hospitalar de Emergência , Hospitalização , Criança , Estudos Transversais , Humanos , Razão de Chances , Alta do Paciente , Estudos Retrospectivos
4.
Microb Ecol ; 70(3): 741-50, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25921518

RESUMO

Rock varnish is a thin layer of Fe and Mn oxyhydroxides with embedded clay minerals that contain an increased Mn/Fe ratio compared to that of the Earth's crust. Even if the study of rock varnish has important implications in several fields, the composition of epilithic bacterial communities and the distribution of taxa on varnish surfaces are still not wholly described. The aim of this study was (i) to identify the bacterial taxa which show the greatest variation between varnish and non-varnish environments, collected from the same rock, and (ii) to describe the morphology of epilithic communities through scanning electron microscopy (SEM). Triplicate samples of rock surfaces with varnish and triplicate samples without varnish were collected from five sites in Matsch Valley (South Tyrol, Italy). The V4 region of 16S rRNA gene was analyzed by Illumina sequencing. Fifty-five ubiquitous taxa have been examined to assess variation between varnish and non-varnish. Cyanobacteria, Chloroflexi, Proteobacteria along with minor taxa such as Solirubrobacterales, Conexibaxter, and Rhodopila showed significant variations of abundance, diversity, or both responding to the ecology (presence/absence of varnish). Other taxa, such as the genus Edaphobacter, showed a more marked spatial variation responding to the sampling site. SEM images showed a multitude of bacterial morphologies and structures involved in the process of attachment and creation of a suitable environment for growth. The features emerging from this analysis suggest that the highly oxidative Fe and Mn-rich varnish environment favors anoxigenic autotrophy and establishment of highly specialized bacteria.


Assuntos
Fenômenos Fisiológicos Bacterianos , Meio Ambiente , Microbiota , Bactérias/genética , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Itália , Microscopia Eletrônica de Varredura , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/metabolismo , Análise de Sequência de DNA , Especificidade por Substrato
5.
Microb Ecol ; 64(4): 870-80, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22622763

RESUMO

Mining of pyrite minerals is a major environmental issue involving both biological and geochemical processes. Here we present a study of an artificial lake of a former uranium open pit mine with the aim to connect the chemistry and bacterial community composition (454-pyrosequencing of 16S rRNA genes) in the stratified water column. A shift in the water chemistry from oxic conditions in the epilimnion to anoxic, alkaline, and metal and sulfide-rich conditions in the hypolimnion was corresponded by a strong shift in the bacterial community, with few shared operational taxonomic units (OTU) between the water layers. The epilimnetic bacterial community of the lake (~20 years old) showed similarities to other temperate freshwater lakes, while the hypolimnetic bacterial community showed similarity to extreme chemical environments. The epilimnetic bacterial community had dominance of Actinobacteria and Betaproteobacteria. The hypolimnion displayed a higher bacterial diversity and was dominated by the phototrophic green sulphur bacterium of the genus Chlorobium (ca. 40 % of the total community). Deltaproteobacteria were only represented in the hypolimnion and the most abundant OTUs were affiliated with ferric iron and sulfate reducers of the genus Geobacter and Desulfobulbus, respectively. The chemistry is clearly controlling, especially the hypolimnetic, bacterial community but the community composition also indicates that the bacteria are involved in metal cycling in the lake.


Assuntos
Bactérias/classificação , Ecossistema , Lagos/química , Lagos/microbiologia , Mineração , Urânio , Bactérias/genética , Bactérias/isolamento & purificação , DNA Bacteriano/análise , DNA Bacteriano/genética , Compostos Férricos/análise , Compostos Férricos/metabolismo , Genes de RNAr , Proteobactérias/classificação , Proteobactérias/genética , RNA Ribossômico 16S/genética , Análise de Sequência de DNA/métodos , Enxofre/análise , Enxofre/metabolismo , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
6.
Environ Technol ; 33(1-3): 129-41, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22519096

RESUMO

Trace-level analysis of alkylphenol polyethoxylates (APEOs) in wastewater containing sludge requires the prior removal of contaminants and preconcentration. In this study, the effects on optimal work-up procedures of the types of alkylphenols present, their degree of ethoxylation, the biofilm wastewater treatment and the sample matrix were investigated for these purposes. The sampling spot for APEO-containing specimens from an industrial wastewater treatment plant was optimized, including a box that surrounded the tubing outlet carrying the wastewater, to prevent sedimented sludge contaminating the collected samples. Following these changes, the sampling precision (in terms of dry matter content) at a point just under the tubing leading from the biofilm reactors was 0.7% RSD. The findings were applied to develop a work-up procedure for use prior to a high-performance liquid chromatography-fluorescence detection analysis method capable of quantifying nonylphenol polyethoxylates (NPEOs) and poorly investigated dinonylphenol polyethoxylates (DNPEOs) at low microg L(-1) concentrations in effluents from non-activated sludge biofilm reactors. The selected multi-step work-up procedure includes lyophilization and pressurized fluid extraction (PFE) followed by strong ion exchange solid phase extraction (SPE). The yields of the combined procedure, according to tests with NP10EO-spiked effluent from a wastewater treatment plant, were in the 62-78% range.


Assuntos
Reatores Biológicos , Fenóis/química , Polietilenoglicóis/química , Esgotos/análise , Biofilmes , Cromatografia Líquida de Alta Pressão , Extração em Fase Sólida , Espectrometria de Massas por Ionização por Electrospray , Tensoativos/análise
7.
PLoS One ; 16(9): e0244910, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34469447

RESUMO

The elimination of hazardous compounds in chemical wastes can be a complex and technically demanding task. In the search for environmental-friendly technologies, fungal mediated remediation and removal procedures are of concern. In this study, we investigated whether there are fungal species that can survive and grow on solely amine-containing compounds. One compound containing a primary amine group; 2-diethylaminoethanol, one compound with a primary amide group; 2,6-dichlorobenzamide (BAM), and a third compound containing a quaternary ammonium group; N3-trimethyl(2-oxiranyl)methanaminium chloride, were selected. The choice of these compounds was motivated by their excessive use in large scale manufacturing of protein separation media (2-diethylaminoethanol and the quaternary amine). 2,6-dichlorobenzamide, the degradation product of the herbicide 2,6-dichlorobenzonitrile (dichlobenil), was chosen since it is an extremely recalcitrant compound. Utilising part of the large fungal diversity in Northern European forests, a screening study using 48 fungal isolates from 42 fungal species, including saprotrophic and mycorrhizal fungi, was performed to test for growth responses to the chosen compounds. The ericoid (ERM) mycorrhizal fungus Rhizoscyphus ericae showed the best overall growth on 2-diethylaminoethanol and BAM in the 1-20 g L-1 concentration range, with a 35-fold and 4.5-fold increase in biomass, respectively. For N3-trimethyl(2-oxiranyl)methanaminium chloride, the peak growth occurred at 1 g L-1. In a second experiment, including three of the most promising fungi (Laccaria laccata, Hygrophorus camarophyllus and Rhizoscyphus ericae) from the screening experiment, a simulated process water containing 1.9% (w/v) 2-diethylaminoethanol and 0.8% (w/v) N3-trimethyl(2-oxiranyl)methanaminium chloride was used. Laccaria laccata showed the best biomass increase (380%) relative to a control, while the accumulation for Rhizoscyphus ericae and Hygrophorus camarophyllus were 292% and 136% respectively, indicating that mycorrhizal fungi can use amine- and amide-containing substrates as nutrients. These results show the potential of certain fungal species to be used in alternative green wastewater treatment procedures.


Assuntos
Amidas , Aminas , Compostos de Amônio , Micorrizas , Agaricales
8.
Hosp Pediatr ; 10(5): 415-423, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32269075

RESUMO

OBJECTIVES: The appropriateness of interfacility transfer admissions for bronchiolitis to pediatric centers is uncertain. We characterized avoidable transfer admissions for bronchiolitis. We hypothesized that a higher proportion of hospitalized infants transferred from a community emergency department (ED) or hospital (transfer admission) would be discharged within 48 hours with little or no intervention, compared with direct admissions from an enrolling ED (nontransfer admission). METHODS: We analyzed a 17-center, prospective infant cohort (age <1 year) hospitalized for bronchiolitis (2011-2014). An avoidable transfer admission (primary outcome) was hospitalization for <48 hours without an intervention for severe illness in which a pediatric specialist could be beneficial (oxygen, advanced airway management, life support). Parenteral fluids and routine medications were excluded. We compared admissions by patient, ED, inpatient, and transferring hospital characteristics to identify factors associated with avoidable transfer admissions. Multivariable logistic regression was used to identify predictors of avoidable transfer admission. RESULTS: Among 1007 infants, 558 (55%) were nontransfer admissions, 164 (16%) were transfer admissions, and 204 (20%) were referrals from clinics; 81 (8%) were missing referral type. Significantly fewer transferred infants were hospitalized for <48 hours with little or no intervention (40 of 164; 24% [95% confidence interval 18%-32%]) than nontransferred infants (199 of 558; 36% [95% confidence interval 32%-40%]; P = .007). Avoidable transfer admissions were more likely to be children of color, have nonprivate insurance, receive fewer ED interventions, and originate from small EDs. A multivariable model revealed that minority race and/or ethnicity, normal oxygenation, and small ED transfers increased odds of avoidable transfer admission. CONCLUSIONS: Although most transferred infants hospitalized for bronchiolitis required interventions for severe illness, 1 in 4 admissions were potentially avoidable.


Assuntos
Bronquiolite , Hospitalização , Transferência de Pacientes , Serviço Hospitalar de Emergência , Hospitais Comunitários , Humanos , Lactente , Modelos Logísticos , Masculino , Análise Multivariada , Alta do Paciente , Estudos Prospectivos
9.
FEMS Microbiol Ecol ; 95(11)2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31539041

RESUMO

In boreal systems, soil profiles typically consist of distinct stratified horizons, with organic layers at the surface overlying deeper mineral horizons providing microhabitat variation along a depth gradient, and vertical stratification of fungal communities along such soil profiles is commonly observed. We studied fungal community structure in a coastal pine forest along a gradient of decreasing influence from the coast. In this system, the vertical stratification pattern of soil microhabitats (defined here as organic, mineral with roots and mineral without roots: O, MR and MN, respectively) is non-uniform; organic horizons are sometimes buried under drifting sand dunes. Our results show that soil microhabitats are distinct with respect to physiochemical characteristics, community composition and OTU richness. While community composition was partly related to depth and distance from the coastal forest edge, microhabitat appeared to have the strongest influence. A closer inspection of the OTUs with the highest relative sequence abundance within each microhabitat revealed that microhabitats support functionally distinct fungal communities with respect to trophic mode and growth morphology. These results suggest that in coastal pine forests, variation in soil microhabitats contributes to the high fungal diversity found belowground and may play an important role in optimizing nutrient cycling.


Assuntos
Florestas , Fungos/isolamento & purificação , Pinus/microbiologia , Microbiologia do Solo , Fungos/classificação , Micobioma , Raízes de Plantas , Solo/química
10.
PLoS One ; 13(8): e0200351, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30089115

RESUMO

Garnets from disparate geographical environments and origins such as oxidized soils and river sediments in Thailand host intricate systems of microsized tunnels that significantly decrease the quality and value of the garnets as gems. The origin of such tunneling has previously been attributed to abiotic processes. Here we present physical and chemical remains of endolithic microorganisms within the tunnels and discuss a probable biological origin of the tunnels. Extensive investigations with synchrotron-radiation X-ray tomographic microscopy (SRXTM) reveal morphological indications of biogenicity that further support a euendolithic interpretation. We suggest that the production of the tunnels was initiated by a combination of abiotic and biological processes, and that at later stages biological processes came to dominate. In environments such as river sediments and oxidized soils garnets are among the few remaining sources of bio-available Fe2+, thus it is likely that microbially mediated boring of the garnets has trophic reasons. Whatever the reason for garnet boring, the tunnel system represents a new endolithic habitat in a hard silicate mineral otherwise known to be resistant to abrasion and chemical attack.


Assuntos
Sedimentos Geológicos/química , Minerais/química , Rios/química , Silicatos/química , Solo/química , Compostos Ferrosos/química , Fósseis , Sedimentos Geológicos/microbiologia , Microscopia Eletrônica de Varredura , Espectrometria por Raios X , Tailândia
12.
Environ Sci Pollut Res Int ; 22(24): 19376-83, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25414032

RESUMO

Heavy metal-contaminated soil derived from a former uranium mining site in Ronneburg, Germany, was used for sterile mesocosms inoculated with the extremely metal-resistant Streptomyces mirabilis P16B-1 or the sensitive control strain Streptomyces lividans TK24. The production and fate of bacterial hydroxamate siderophores in soil was analyzed, and the presence of ferrioxamines E, B, D, and G was shown. While total ferrioxamine concentrations decreased in water-treated controls after 30 days of incubation, the sustained production by the bacteria was seen. For the individual molecules, alteration between neutral and cationic forms and linearization of hydroxamates was observed for the first time. Mesocosms inoculated with biomass of either strain showed changes of siderophore contents compared with the non-treated control indicating for auto-alteration and consumption, respectively, depending on the vital bacteria present. Heat stability and structural consistency of siderophores obtained from sterile culture filtrate were shown. In addition, low recovery (32 %) from soil was shown, indicating adsorption to soil particles or soil organic matter. Fate and behavior of hydroxamate siderophores in metal-contaminated soils may affect soil properties as well as conditions for its inhabiting (micro)organisms.


Assuntos
Metais Pesados/química , Sideróforos/biossíntese , Microbiologia do Solo , Poluentes do Solo/química , Streptomyces/metabolismo , Adsorção , Compostos Férricos/química , Alemanha , Ácidos Hidroxâmicos/química , Mineração , Sideróforos/química , Solo/química
13.
J Chromatogr A ; 1020(1): 91-7, 2003 Dec 05.
Artigo em Inglês | MEDLINE | ID: mdl-14661760

RESUMO

In this study a new approach to determine three different siderophores (ferrichrome, ferrichrysin, ferricrocin) in natural soil solutions as well as in cultures of fungi is presented. The method includes enrichment of the analytes on a short pre-column, packed with C18 material, and subsequent highly selective separation of the analytes on a capillary porous graphitic carbon (PGC) column. In contrast to normal C18 packing materials, porous graphitic carbon offers chromatographic resolution between the three very similar analytes. The selectivity of the method is enhanced even further by the electrospray ionization (ESI) mass spectrometric detection. The combination of a short pre-column and a packed capillary separation column results in a method with high sensitivity. Reported detection limits, defined as the concentration giving the signal-to-noise ratio 3:1, is 27.7 pM for ferrichrome, 46.1 pM for ferricrocin and 37.4 pM for ferrichrysin.


Assuntos
Cromatografia Líquida/métodos , Ácidos Hidroxâmicos/análise , Espectrometria de Massas/métodos , Sideróforos/análise , Ácidos Hidroxâmicos/química , Sideróforos/química
14.
Astrobiology ; 11(7): 633-50, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21895442

RESUMO

We report the discovery of fossilized filamentous structures in samples of the lithified, volcaniclastic apron of Gran Canaria, which were obtained during Leg 157 of the Ocean Drilling Program (ODP). These filamentous structures are 2-15 µm in diameter and several hundred micrometers in length and are composed of Si, Al, Fe, Ca, Mg, Na, Ti, and C. Chitin was detected in the filamentous structures by staining with wheat germ agglutinin dye conjugated with fluorescein isothiocyanate (WGA-FITC), which suggests that they are fossilized fungal hyphae. The further elucidation of typical filamentous fungal morphological features, such as septa, hyphal bridges, and anastomosis and their respective sizes, support this interpretation. Characteristic structures that we interpreted as fossilized spores were also observed in association with the putative hyphae. The fungal hyphae were found in pyroxene phenocrysts and in siderite pseudomorphs of a basalt breccia. The fungal colonization of the basalt clasts occurred after the brecciation but prior to the final emplacement and lithification of the sediment at ∼16-14 Ma. The siderite appears to have been partially dissolved by the presence of fungal hyphae, and the fungi preferentially colonized Fe-rich carbonates over Fe-poor carbonates (aragonite). Our findings indicate that fungi may be an important geobiological agent in subseafloor environments and an important component of the deep subseafloor biosphere, and that hydrothermal environments associated with volcanism can support a diverse ecosystem, including eukaryotes.


Assuntos
Fósseis , Fungos/isolamento & purificação , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Carbonatos/química , Ecossistema , Compostos Férricos/química , Hifas , Minerais/química , Paleontologia , Espanha , Erupções Vulcânicas/análise
15.
J Chromatogr A ; 1216(41): 6974-7, 2009 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-19744662

RESUMO

A novel reversed phase HPLC method for the simultaneous analysis of surfactants containing nonylphenol/dinonylphenol-polyethoxylates and their o-phosphate esters is reported, in which eluting substances are detected fluorescently. Their chemical structures were elucidated by direct infusion electrospray-mass spectrometry in positive mode. The limits of quantification and range of the method were determined to be 0.1mg and 0.1-100 mg surfactant L(-1), respectively, with a reproducibility (RSD) at a concentration of 38 mg surfactant L(-1) of 5.6%. The accuracy was determined by spiking selected process water samples with known amounts of surfactant, and recoveries were typically in the 82-102% range.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Resíduos Industriais , Organofosfatos/análise , Tensoativos/química , Calibragem , Ésteres , Estrutura Molecular , Organofosfatos/química , Fenóis/análise , Reprodutibilidade dos Testes , Espectrometria de Fluorescência , Espectrometria de Massas por Ionização por Electrospray
16.
Biometals ; 19(3): 269-82, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16799865

RESUMO

Concentrations up to 2 and 12 nM of the hydroxamate siderophores ferrichrome and ferricrocin, respectively, were identified in soil solutions of podzolic forest soils at four sites in both northern and southern Sweden. No ferrichrysin was detected. As with the dissolved organic carbon and low molecular mass organic acids, the highest concentrations of the siderophores were found in the upper layers i.e. the mor layer, the eluvial and upper illuvial horizons. At the southern sites, the concentrations of ferrichrome and ferricrocin were both of similar magnitude and did not differ between the two sites. In contrast, soil solutions at the two northern sites contained more ferricrocin than ferrichrome; the ferricrocin concentrations were also higher at the northern sites than at the southern sites. Analyses were performed by high performance liquid chromatography with a porous graphitic carbon column on which ferrichrome, ferricrocin and ferrichrysin were separated. Detection by electrospray ionization mass spectrometry (ESI-MS) combined with on-line sample pre-concentration, by means of column-switching, enabled detection limits of 0.1-0.2 nM for ferrichrome, ferrichrysin and ferricrocin. The structural identities of the siderophores were further verified by MS/MS fragmentation. Fragmentation of ferrichrome, ferricrocin and ferrichrysin occurred mainly via peptide cleavage. The most intense fragments were typified by the loss of one of the three iron(III) chelating hydroxamate residues, i.e N(5)-acyl-N(5)-hydroxy ornithine.


Assuntos
Ferricromo/análogos & derivados , Ferricromo/análise , Sideróforos/análise , Solo/análise , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas por Ionização por Electrospray , Suécia
17.
Anal Chem ; 76(9): 2618-22, 2004 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-15117206

RESUMO

Column-switching liquid chromatography followed by low-resolution ICPMS was evaluated as a tool for speciation analysis of metal-containing biomolecules. The strategy was applied on siderophores, strong iron chelators of low molecular weight (M(w) < 1500). Prior to the LC-ICPMS analysis, reductive displacement of iron by gallium was performed using ascorbate as the reducing agent to increase the sensitivity. Different experimental conditions during the exchange reaction were tested using ferrichrysin and ferrichrome for evaluation. A reaction time of 30 min and a pH of 3.9 gave an exchange yield of 27 and 83% for ferrichrysin and ferrichrome, respectively. A gradient elution profile was also developed to separate gallium-chelated siderophores on a PGC column. Detection limits for standard solutions of ferrichrysin and ferrichrome in the low-nanomolar range were obtained by monitoring the gallium-69 isotope. The combined use of LC-ICPMS and LC-ESI-MS/MS was also evaluated as a tool to identify unknown metal complexes, here siderophores, in field soil solution samples.


Assuntos
Gálio/química , Ferro/química , Metais/química , Sideróforos/análise , Espectrometria de Massas por Ionização por Electrospray/métodos , Ácido Ascórbico/análise , Ácido Ascórbico/química , Cromatografia Líquida de Alta Pressão/métodos , Gálio/análise , Ferro/análise , Estrutura Molecular , Oxirredução , Sensibilidade e Especificidade , Sideróforos/química , Espectrometria de Massas por Ionização por Electrospray/instrumentação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/instrumentação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA