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1.
J Emerg Med ; 58(5): e233-e235, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32362373

RESUMEN

Emergency medicine is a profession that requires good leadership skills. Emergency physicians must be able to instill confidence in both the staff and patients, inspire the best in others, have the enthusiasm to take on a surplus of responsibilities, and maintain calmness during unexpected circumstances. Accordingly, residency program directors look carefully for leadership qualities and potential among their applicants. Although some people do have a predisposition to lead, leadership can be both learned and taught. In this article, we provide medical students with the tools that will help them acquire those qualities and thus make them more desirable by program directors.


Asunto(s)
Medicina de Emergencia , Internado y Residencia , Estudiantes de Medicina , Medicina de Emergencia/educación , Humanos , Liderazgo
2.
Am J Emerg Med ; 36(12): 2166-2171, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-29622393

RESUMEN

BACKGROUND: Heart failure (HF) readmissions are a longstanding national healthcare issue for both hospitals and patients. Our purpose was to evaluate the efficacy of a structured, educational intervention targeted towards un- and under-insured emergency department (ED) HF patients. METHODS: HF patients presenting to the ED for care were enrolled between July and December 2015 as part of an open label, interventional study, using a parallel observational control group. Eligible patients provided informed consent, had an established HF diagnosis, and were hemodynamically stable. Intervention patients received a standardized educational intervention in the ED waiting room before seeing the emergency physician, and a 30-day telephone follow-up. Primary and secondary endpoints were 30- and 90-day ED and hospital readmission rates, as well as days alive and out of hospital (DAOH) respectively. RESULTS: Of the 94 patients enrolled, median age was 58.4 years; 40.4% were female, and 54.3% were African American. Intervention patients (n = 45) experienced a 47.8% and 45.3% decrease in ED revisits (P = 0.02 &P < 0.001), and 60.0% and 47.4% decrease in hospital readmissions (P = 0.049 &P = 0.007) in the 30 and 90 days pre- versus post-intervention respectively. Control patients (n = 49) had no change in hospital readmissions or 30-day ED revisits, but experienced a 36.6% increase in 90-day ED revisits (P = 0.03). Intervention patients also saw a 59.2% improvement in DAOH versus control patients (P = 0.03). CONCLUSION: An ED educational intervention markedly decreases ED and hospital readmissions in un- and under-insured HF patients.


Asunto(s)
Insuficiencia Cardíaca/terapia , Educación del Paciente como Asunto/métodos , Readmisión del Paciente/estadística & datos numéricos , Anciano , Manejo de la Enfermedad , Servicio de Urgencia en Hospital , Femenino , Humanos , Masculino , Pacientes no Asegurados , Persona de Mediana Edad , Teléfono , Texas , Factores de Tiempo
3.
J Health Care Poor Underserved ; 27(3): 1267-77, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-27524767

RESUMEN

OBJECTIVE: Patients seen in emergency departments (EDs) not requiring admission are typically discharged with appropriate follow-up. Sometimes hospitals indirectly refer, or redirect, patients to a different hospital's ED. Anecdotally, indirect referrals are commonly received in safety-net hospitals. This study characterizes the types of patients and hospitals affected and the cost of indirect referral in the orthopaedic trauma population. METHODS: A retrospective cross-sectional chart review was conducted of 1,162 consecutive adult patients receiving orthopaedic care in an urban public hospital ED over a six-month period in 2011. Multivariable logistic regression analysis compared patients who were indirectly referred with those presenting primarily. RESULTS: One in five (N=236) patients treated for orthopaedic injury was indirectly referred from neighboring hospitals with orthopaedists available; 209 (88.6%) of these patients were uninsured (OR 3.69; CI 1.85-7.34). Nonprofit hospitals initially treated 107 (64.1%) of these patients. Costs for largely uncompensated care at the public hospital were $1.77 million.


Asunto(s)
Servicio de Urgencia en Hospital/estadística & datos numéricos , Pacientes no Asegurados/estadística & datos numéricos , Ortopedia/estadística & datos numéricos , Transferencia de Pacientes/estadística & datos numéricos , Proveedores de Redes de Seguridad/estadística & datos numéricos , Adulto , Factores de Edad , Estudios Transversales , Servicio de Urgencia en Hospital/economía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Ortopedia/economía , Transferencia de Pacientes/economía , Estudios Retrospectivos , Proveedores de Redes de Seguridad/economía , Factores Socioeconómicos , Atención no Remunerada/economía , Heridas y Lesiones/economía , Heridas y Lesiones/cirugía
4.
MMWR Suppl ; 65(3): 50-6, 2016 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-27390018

RESUMEN

The 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa underscores the need for health care infection prevention and control (IPC) practices to be implemented properly and consistently to interrupt transmission of pathogens in health care settings to patients and health care workers. Training and assessing IPC practices in general health care facilities not designated as Ebola treatment units or centers became a priority for CDC as the number of Ebola virus transmissions among health care workers in West Africa began to affect the West African health care system and increasingly more persons became infected. CDC and partners developed policies, procedures, and training materials tailored to the affected countries. Safety training courses were also provided to U.S. health care workers intending to work with Ebola patients in West Africa. As the Ebola epidemic continued in West Africa, the possibility that patients with Ebola could be identified and treated in the United States became more realistic. In response, CDC, other federal components (e.g., Office of the Assistant Secretary for Preparedness and Response) and public health partners focused on health care worker training and preparedness for U.S. health care facilities. CDC used the input from these partners to develop guidelines on IPC for hospitalized patients with known or suspected Ebola, which was updated based on feedback from partners who provided care for Ebola patients in the United States. Strengthening and sustaining IPC helps health care systems be better prepared to prevent and respond to current and future infectious disease threats.The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html).


Asunto(s)
Infección Hospitalaria/prevención & control , Epidemias/prevención & control , Instituciones de Salud , Fiebre Hemorrágica Ebola/prevención & control , África Occidental/epidemiología , Centers for Disease Control and Prevention, U.S./organización & administración , Personal de Salud/educación , Fiebre Hemorrágica Ebola/epidemiología , Humanos , Cooperación Internacional , Guías de Práctica Clínica como Asunto , Estados Unidos/epidemiología
6.
Int J Crit Illn Inj Sci ; 4(3): 261-5, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25337491

RESUMEN

There have been many technological advances improving the work up and treatment of patients in the emergency department (ED). Point of care testing (POCT) is becoming more common, especially in the time compressed clinically high-pressured environment of the emergency department. In present times, emphasis of POCT has spurred search of novel biomarkers which promise earlier and more specific detection of disease. This article reviews the role of ST2, Galectin-3 and Adrenomedullin in the acute care setting addressing the screening, diagnostic, and prognostic role of each marker for stratification of patients. Use of these markers has shown a strong correlation with early identification and efficient management in the ED.

7.
J Bone Joint Surg Am ; 96(19): 1650-8, 2014 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-25274790

RESUMEN

BACKGROUND: Orthopaedic clinic follow-up is required to ensure optimal management and outcome for many patients who present to the emergency department (ED) with an orthopaedic injury. While several studies have shown that demographic variables influence patient follow-up after discharge from the ED, the objective of this study was to examine orthopaedic-related and other factors associated with the failure to return for orthopaedic outpatient management, so-called "no-show," after an ED visit. METHODS: A chart review was conducted at a large academic public hospital. Four hundred and sixty-four consecutive adult patients who received an orthopaedic consult in the ED with subsequent referral to the orthopaedic clinic from January through June, 2011, were included. With use of chi-square and Mann-Whitney univariate tests, data regarding injury type and management were analyzed for association with no-show. Variables with p < 0.25 were included in a multivariate stepwise forward logistic regression analysis. RESULTS: The overall no-show rate was 26.1%. Logistic regression modeling revealed significant differences in no-show rates based on cause of injury (odds ratio [OR] 7.51; 95% confidence interval [CI], 2.27 to 25.1), with assault victims having the highest no-show rate. Anatomic region of injury significantly influenced no-show rates (OR 6.61; 95% CI, 1.45 to 30.5), with patients with a spine or back complaint having the highest no-show rate. Follow-up rates were influenced by the orthopaedic resident provider consulted (OR 10.8; 95% CI, 4.11 to 31.1), and this was not related to level of training (p = 0.25). The type of bracing applied influenced the no-show rate (OR 2.46; 95% CI, 1.58 to 3.96), and the easier it was to remove the brace (splint), the worse the follow-up (p = 0.0001). Several demographic variables were also predictive of clinic nonattendance, including morbid obesity (OR 15.0; 95% CI, 4.83 to 51.6) and current tobacco use (OR 5.56; 95% CI, 2.19 to 15.4). CONCLUSIONS: This study supports previous evidence of high no-show rates with scheduled orthopaedic follow-up among patients treated in the ED. The data highlight distinct orthopaedic-related factors associated with nonattendance. These findings are useful in identifying patients at high risk for no-show to scheduled orthopaedic follow-up appointments and may influence disposition and management decisions for these patients.


Asunto(s)
Cuidados Posteriores , Enfermedades Óseas/terapia , Huesos/lesiones , Servicios Médicos de Urgencia , Perdida de Seguimiento , Adulto , Cuidados Posteriores/estadística & datos numéricos , Cuidados Posteriores/tendencias , Enfermedades Óseas/complicaciones , Demografía , Humanos , Ortopedia , Análisis de Regresión
8.
Environ Sci Technol ; 48(18): 10531-8, 2014 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-25121583

RESUMEN

Current research policy and strategy documents recommend applying life cycle assessment (LCA) early in research and development (R&D) to guide emerging technologies toward decreased environmental burden. However, existing LCA practices are ill-suited to support these recommendations. Barriers related to data availability, rapid technology change, and isolation of environmental from technical research inhibit application of LCA to developing technologies. Overcoming these challenges requires methodological advances that help identify environmental opportunities prior to large R&D investments. Such an anticipatory approach to LCA requires synthesis of social, environmental, and technical knowledge beyond the capabilities of current practices. This paper introduces a novel framework for anticipatory LCA that incorporates technology forecasting, risk research, social engagement, and comparative impact assessment, then applies this framework to photovoltaic (PV) technologies. These examples illustrate the potential for anticipatory LCA to prioritize research questions and help guide environmentally responsible innovation of emerging technologies.


Asunto(s)
Conservación de los Recursos Naturales/métodos , Contaminación Ambiental/prevención & control , Materiales Manufacturados , Modelos Teóricos , Tecnología/normas , Conservación de los Recursos Naturales/estadística & datos numéricos , Conservación de los Recursos Naturales/tendencias , Contaminación Ambiental/estadística & datos numéricos , Humanos , Formulación de Políticas , Riesgo , Tecnología/estadística & datos numéricos , Tecnología/tendencias
9.
Crit Pathw Cardiol ; 12(3): 116-20, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23892940

RESUMEN

BACKGROUND: The Society of Cardiovascular Patient Care (SCPC) accredits hospital acute coronary syndrome management. The influence of accreditation on the subset of patients diagnosed with acute myocardial infarction (AMI) is unknown. Our purpose was to describe the association between SCPC accreditation and hospital quality metric performance among AMI patients enrolled in ACTION Registry-GWTG (ACTION-GWTG). This program is a voluntary registry that receives self-reported hospital AMI quality metrics data and provides quarterly feedback to 487 US hospitals. METHODS: Using urban nonacademic hospital registry data from January 1, 2007, to June 30, 2010, we performed a 1 to 2 matched pairs analysis, selecting 14 of 733 (1.9%) SCPC accredited and 28 of 309 (9.1%) nonaccredited registry facilities to compare changes in quality metrics between the year before and after SCPC accreditation. RESULTS: All hospitals improved quality metric compliance during the study period. Nonaccredited hospitals started with slightly lower rates of AMI composite score 1 year before accreditation. Although improvement compared with baseline was greater for nonaccredited hospitals (odds ratio = 1.27; 95% confidence interval: 1.20, 1.35) than accredited hospitals (odds ratio = 1.15; 95% confidence interval: 1.07, 1.23) (P = 0.022), the group ended with similar compliance scores (92.1% vs. 92.2%, respectively). Improvements in evaluating left ventricular function (P = 0.0001), adult smoking cessation advice (P = 0.0063), and cardiac rehab referral (P = 0.0020) were greater among nonaccredited hospitals, whereas accredited hospitals had greater improvement in discharge angiotensin-converting-enzyme inhibitor or angiotensin II receptor blocker use for left ventricular systolic dysfunction (P = 0.0238). CONCLUSIONS: All hospitals had high rates of quality metric compliance and finished with similar overall AMI performance composite scores after 1 year.


Asunto(s)
Acreditación/estadística & datos numéricos , Adhesión a Directriz/estadística & datos numéricos , Hospitales Urbanos/estadística & datos numéricos , Infarto del Miocardio/terapia , Calidad de la Atención de Salud/estadística & datos numéricos , Acreditación/normas , Antagonistas de Receptores de Angiotensina/uso terapéutico , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Adhesión a Directriz/normas , Hospitales Urbanos/normas , Humanos , Análisis por Apareamiento , Infarto del Miocardio/diagnóstico , Infarto del Miocardio/rehabilitación , Guías de Práctica Clínica como Asunto , Garantía de la Calidad de Atención de Salud , Calidad de la Atención de Salud/normas , Derivación y Consulta/normas , Derivación y Consulta/estadística & datos numéricos , Sistema de Registros , Cese del Hábito de Fumar , Disfunción Ventricular Izquierda/diagnóstico , Disfunción Ventricular Izquierda/terapia
10.
J Contam Hydrol ; 151: 16-33, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23697993

RESUMEN

The interaction between emulsified vegetable oil (EVO) and trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) was observed using two soil columns and subsequent reductive dechlorination of TCE was monitored over a three year period. Dyed TCE DNAPL (~75 g) was emplaced in one column (DNAPL column), while the second was DNAPL-free (plume column). EVO was added to both columns and partitioning of the EVO into the TCE DNAPL was measured and quantified. TCE (1.9 mM) was added to the influent of the plume column to simulate conditions down gradient of a DNAPL source area and the columns were operated independently for more than one year, after which they were connected in series. Initially limited dechlorination of TCE to cDCE was observed in the DNAPL column, while the plume column supported complete reductive dechlorination of TCE to ethene. Upon connection and reamendment of the plume column with EVO, near saturation levels of TCE from the effluent of the DNAPL column were rapidly dechlorinated to c-DCE and VC in the plume column; however, this high rate dechlorination produced hydrochloric acid which overwhelmed the buffering capacity of the system and caused the pH to drop below 6.0. Dechlorination efficiency in the columns subsequently deteriorated, as measured by the chloride production and Dehalococcoides counts, but was restored by adding sodium bicarbonate buffer to the influent groundwater. Robust dechlorination was eventually observed in the DNAPL column, such that the TCE DNAPL was largely removed by the end of the study. Partitioning of the EVO into the DNAPL provided significant operational benefits to the remediation system both in terms of electron donor placement and longevity.


Asunto(s)
Contaminantes del Suelo/metabolismo , Aceite de Soja/química , Tricloroetileno/metabolismo , Bacterias/metabolismo , Biodegradación Ambiental , Emulsiones , Oxidación-Reducción , Contaminantes del Suelo/química , Tricloroetileno/química
12.
J Contam Hydrol ; 131(1-4): 100-18, 2012 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-22366331

RESUMEN

A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study was designed as a fractional factorial experiment involving 177 bottles distributed between four industrial laboratories and was used to assess the impact of six electron donors, bioaugmentation, addition of supplemental nutrients, and two TCE levels (0.57 and 1.90 mM or 75 and 250 mg/L in the aqueous phase) on TCE dechlorination. Performance was assessed based on the concentration changes of TCE and reductive dechlorination degradation products. The chemical data was evaluated using analysis of variance (ANOVA) and survival analysis techniques to determine both main effects and important interactions for all the experimental variables during the 203-day study. The statistically based design and analysis provided powerful tools that aided decision-making for field application of this technology. The analysis showed that emulsified vegetable oil (EVO), lactate, and methanol were the most effective electron donors, promoting rapid and complete dechlorination of TCE to ethene. Bioaugmentation and nutrient addition also had a statistically significant positive impact on TCE dechlorination. In addition, the microbial community was measured using phospholipid fatty acid analysis (PLFA) for quantification of total biomass and characterization of the community structure and quantitative polymerase chain reaction (qPCR) for enumeration of Dehalococcoides organisms (Dhc) and the vinyl chloride reductase (vcrA) gene. The highest increase in levels of total biomass and Dhc was observed in the EVO microcosms, which correlated well with the dechlorination results.


Asunto(s)
Bacterias/metabolismo , Etilenos/metabolismo , Tricloroetileno/metabolismo , Contaminantes Químicos del Agua/metabolismo , Análisis de Varianza , Biodegradación Ambiental , Cromatografía de Gases , Conductividad Eléctrica , Ionización de Llama , Modelos Estadísticos , Oxidación-Reducción , Análisis de Regresión , Reino Unido
13.
Ann Emerg Med ; 58(1 Suppl 1): S79-84, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21684414

RESUMEN

OBJECTIVE: We implement an opt-out routine screening program in a high-volume, urban emergency department (ED), using conventional (nonrapid) technology as an alternative to rapid HIV tests. METHODS: We performed a retrospective cohort study. Since October 2008, all patients who visited Ben Taub General Hospital ED and had blood drawn were considered eligible for routine opt-out HIV screening. The hospital is a large, publicly funded, urban, academic hospital in Houston, TX. The ED treats approximately 8,000 patients monthly. Screening was performed with standard chemiluminescence technology, batched hourly. Patients with positive screening test results were informed of their likely status, counseled by a service linkage worker, and offered follow-up care at an HIV primary care clinic. Confirmatory Western blot assays were automatically performed on all new HIV-positive samples. RESULTS: Between October 1, 2008, and April 30, 2009, 14,093 HIV tests were performed and 39 patients (0.3%) opted out. Two hundred sixty-two (1.9%) HIV test results were positive and 80 new diagnoses were made, for an incidence of new diagnoses of 0.6%. There were 22 false-positive chemiluminescence results and 7 indeterminate Western blot results. Nearly half the patients who received a new diagnosis were not successfully linked to HIV care in our system. CONCLUSION: Opt-out screening using standard nonrapid technology, rather than rapid testing, is feasible in a busy urban ED. This method of HIV screening has cost benefits and a low false-positivity rate, but aggressive follow-up and referral of patients with new diagnoses for linkage to care is required.


Asunto(s)
Serodiagnóstico del SIDA/métodos , Técnicas de Laboratorio Clínico , Servicio de Urgencia en Hospital , Hospitales Urbanos , Aceptación de la Atención de Salud , Serodiagnóstico del SIDA/estadística & datos numéricos , Adulto , Anciano , Técnicas de Laboratorio Clínico/psicología , Técnicas de Laboratorio Clínico/estadística & datos numéricos , Continuidad de la Atención al Paciente , Femenino , Infecciones por VIH/diagnóstico , Hospitales Urbanos/estadística & datos numéricos , Humanos , Consentimiento Informado , Masculino , Persona de Mediana Edad , Texas , Adulto Joven
14.
J Forensic Sci ; 51(4): 893-5, 2006 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-16882235

RESUMEN

We report on two cases of suicide in which the victims started fires before their deaths. In one case the victim died of a single self-inflicted gunshot wound to the head after setting several fires in his residence. In the second case the victim hung himself after setting several fires in his residence and an adjoining building. In both cases, the victim's position was not near the origin of the fires suggesting that the arson was not a failsafe device to the primary mechanism of suicide. Neither victim showed a significant percentage of carboxyhemoglobin, or thermal damage from the fires. Both cases are remarkable in that, had the fire caused more damage to the remains and dwellings, a finding of suicide may not have been reached. We discuss similar aspects between the two reported cases and discuss differences observed with similar events such as complex suicide, suicide by self-immolation, and concealed homicide by burning. Similar cases should be reported to broaden our understanding of these complex events.


Asunto(s)
Piromanía , Suicidio , Anciano , Colorado , Medicina Legal , Humanos , Masculino , Persona de Mediana Edad , Traumatismos del Cuello/patología , Suicidio/psicología , Heridas por Arma de Fuego/patología
15.
Am J Psychiatry ; 163(1): 145-7, 2006 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-16390902

RESUMEN

OBJECTIVE: The authors' goal was to determine the concentration of antidepressants in amniotic fluid during maternal treatment of depression. METHOD: Women treated with antidepressants undergoing amniocentesis for obstetrical reasons were enrolled. Antidepressant concentrations in amniotic fluid and maternal serum were determined with high-performance liquid chromatography. RESULTS: Amniotic fluid was obtained from 27 women, and the amniotic fluid's antidepressant concentrations were highly variable. For the parent compounds, the amniotic fluid concentrations of selective serotonin uptake inhibitors averaged 11.6% (SD=9.9%) of maternal serum concentrations (N=22). Amniotic fluid to maternal serum ratios were higher for venlafaxine: 172% (SD=91%) (N=3). Of interest, the amniotic fluid to maternal serum ratios for the metabolites (N=19) did not demonstrate a consistent pattern compared to the parent compound ratios. In 10 subjects, the amniotic fluid to maternal serum ratio for the metabolites was higher than the parent compound and lower in the remaining nine subjects. CONCLUSIONS: The pattern of antidepressant concentrations in amniotic fluid is similar to recent data for placental passage. Although the significance of amniotic fluid exposure remains to be determined, these results demonstrate that maternally administered antidepressants are accessible to the fetus in a manner not previously appreciated.


Asunto(s)
Líquido Amniótico/metabolismo , Antidepresivos/metabolismo , Antidepresivos/uso terapéutico , Trastorno Depresivo/sangre , Trastorno Depresivo/tratamiento farmacológico , Feto/metabolismo , Complicaciones del Embarazo/sangre , Complicaciones del Embarazo/tratamiento farmacológico , Amniocentesis , Líquido Amniótico/química , Antidepresivos/análisis , Cromatografía Líquida de Alta Presión , Trastorno Depresivo/metabolismo , Femenino , Humanos , Exposición Materna , Intercambio Materno-Fetal , Embarazo , Complicaciones del Embarazo/metabolismo , Resultado del Embarazo
16.
Environ Sci Technol ; 36(13): 2897-904, 2002 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-12144265

RESUMEN

The effects of natural organic matter (NOM), ferrozine, and AQDS (anthraquinone-2,6-disulfonate) on the reduction of hematite (alpha-Fe2O3) by Shewanella putrefaciens CN32 were studied. It has been proposed that NOM enhances the reduction of Fe(III) by means of electron shuttling or by Fe(II) complexation. Previously both mechanisms were studied separately using "functional analogues" (AQDS for electron shuttling and ferrozine for complexation) and are presently compared with seven different NOMs. AQDS enhanced hematite reduction within the first 24 h of incubation, and this had been ascribed to electron shuttling. Most of the NOMs enhanced hematite reduction after 1 day of incubation indicating that these materials could also serve as electron shuttles. The effect of ferrozine was linear with concentration, and all of the NOMs exhibited this behavior. Fe(II) complexation only enhanced hematite reduction after sufficient Fe(II) had accumulated in the system. Fe(II) complexation appeared to alleviate a suppression of the hematite reduction rate caused by accumulation of Fe(II) in the system. Addition of Fe(II) to the hematite suspension, prior to inoculation with CN32, significantly inhibited hematite reduction and greatly diminished the effects of all of the organic materials, although some enhancement was observed due to addition of anthroquinone-2,6-disulfonate. These results demonstrate that NOM can enhance iron reduction by electron shuttling and by complexation mechanisms.


Asunto(s)
Compuestos Férricos/química , Hierro/química , Shewanella putrefaciens/fisiología , Biodegradación Ambiental , Electrones , Ferrozina/química , Quelantes del Hierro/química , Compuestos Orgánicos , Oxidación-Reducción
17.
Environ Sci Technol ; 36(9): 1939-46, 2002 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-12026974

RESUMEN

Natural organic matter (NOM) enhancement of the biological reduction of hematite (alpha-Fe2O3) by the dissimilatory iron-reducing bacterium Shewanella putrefaciens strain CN32 was investigated under nongrowth conditions designed to minimize precipitation of biogenic Fe(II). Hydrogen served as the electron donor. Anthraquinone-2,6-disulfonate (AQDS), methyl viologen, and methylene blue [quinones with an Ew0 (pH 7) of 0.011 V or less], ferrozine [a strong Fe(II) complexing agent], and characterized aquatic NOM (Georgetown NOM or Suwannee River fulvic acid) enhanced bioreduction in 5-day experiments whereas 1,4-benzoquinone (Ew0 value = 0.280 V) did not. A linear relationship existed between total Fe(II) produced and concentrations of ferrozine or NOM but not quinones, except in the case of methylene blue. Such a linear relationship between Fe(II) and methylene blue concentrations could be due to the systems being far undersaturated with respect to methylene blue or the loss of the thermodynamic driving force. A constant concentration of AQDS and variable concentrations of ferrozine produced a linear relationship between total Fe(II) produced and the concentration of ferrozine. Enhancement effects of both AQDS and ferrozine were additive. NOM may serve as both an electron shuttle and an Fe(II) complexant; however, the concentration dependence of hematite reduction with NOM was more similar to ferrozine than quinones. NOM likely enhances hematite reduction initially by electron shuttling and then further by Fe(II) complexation, which prevents Fe(II) sorption to hematite and cell surfaces.


Asunto(s)
Compuestos Férricos/metabolismo , Compuestos Ferrosos/química , Shewanella putrefaciens/fisiología , Adsorción , Precipitación Química , Transporte de Electrón , Compuestos Férricos/química , Sedimentos Geológicos/química
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