Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
2.
Pediatr Neurol ; 146: 1-7, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37356227

RESUMEN

BACKGROUND: Pediatric neurocritical care (PNCC) has emerged as a field to care for children at the intersection of critical illness and neurological dysfunction. PNCC fellowship programs evolved over the past decade to train physicians to fill this clinical need. We aimed to characterize PNCC fellowship training infrastructure and curriculum in the United States and Canada. METHODS: Web-based survey of PNCC fellowship program leaders during November 2019 to January 2020. RESULTS: There were 14 self-identified PNCC fellowship programs. The programs were supported by Child Neurology and/or Pediatric Critical Care Medicine divisions at tertiary/quaternary care institutions. Most programs accepted trainees who were board-eligible or board-certified in child neurology or pediatric critical care medicine. Clinical training consisted mostly of rotations providing PNCC consultation (n = 13) or as a provider on the pediatric intensive care unit-based neurointensive care team (n = 2). PNCC-specific didactics were delivered at most institutions (n = 13). All institutions provided training in electroencephalography use in the intensive care unit and declaration of death by neurological criteria (n = 14). Scholarly activity was supported by most programs, including protected time for research (n = 10). CONCLUSIONS: We characterized PNCC fellowship training in the United States and Canada, which in this continuously evolving field, lays the foundation for exploring standardization of training going forward.


Asunto(s)
Cuidados Críticos , Becas , Niño , Humanos , Estados Unidos , Encuestas y Cuestionarios , América del Norte , Curriculum , Educación de Postgrado en Medicina
3.
J Intensive Care Med ; 38(4): 358-367, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36069025

RESUMEN

OBJECTIVES: To map the literature regarding assessment of neurocognitive outcomes in PICU survivors. Secondary objectives were to identify literature gaps and to provide data for development of a Core Outcome Measures Set in the domain. METHODS: Planned, a priori analysis was performed of data from an over-all scoping review of Post-Intensive Care Syndrome-pediatrics (PICS-p) functional outcomes. English-language databases and registries from 1970 to 2017 were searched by a medical librarian to identify manuscripts reporting on Post Intensive Care Syndrome-pediatrics (PICS-p). Further, detailed data extraction for neurocognitive outcomes was performed focusing on study characteristics, instruments used, and populations. RESULTS: 114 instruments evaluated neurocognitive function in 183 manuscripts. 83% of manuscripts were published after 2000. Median of 3 (IQR 2-5) neurocognitive instruments per manuscript were reported. Wechsler Scales (45%), clinical neurologic evaluations (21%), Pediatric Cerebral Performance Category (20%), Bayley Scales of Infant Development (16%), and Vineland Adaptive Behavior Scales (11%) were the most commonly used instruments. Median sample size was 65 (IQR 32-129) subjects. Most (63%) assessments were conducted in-person and parents/guardians (40%) provided the information. Patients with congenital heart disease and traumatic brain injury were most commonly evaluated (31% and 24% of manuscripts, respectively). Adolescents were the most commonly studied age group (34%). Baseline function was infrequently assessed (11% of manuscripts); most studies assessed patients at only one time point after PICU discharge. Within studies, neurocognitive assessments were often combined with others - especially social (18%) and physical (8%). CONCLUSIONS: 183 manuscripts studied the neurocognitive domain of PICS-p. Studies were quantitative and tended to focus on populations with anticipated cognitive impairment. Considerable variability exists among the chosen 114 instruments used; however, 4 instruments were frequently chosen with focus on intelligence, cerebral functioning, and developmental and adaptive behavior. The literature is marked by lack of agreement on methodologies but reflects the burgeoning interest in studying PICS-p neurocognitive outcomes.


Asunto(s)
Lesiones Traumáticas del Encéfalo , Disfunción Cognitiva , Lactante , Adolescente , Niño , Humanos , Enfermedad Crítica/psicología , Evaluación de Resultado en la Atención de Salud
6.
Neurocrit Care ; 34(3): 1062-1071, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-32661794

RESUMEN

As the current understanding of COVID-19 continues to evolve, a synthesis of the literature on the neurological impact of this novel virus may help inform clinical management and highlight potentially important avenues of investigation. Additionally, understanding the potential mechanisms of neurologic injury may guide efforts to better detect and ameliorate these complications. In this review, we synthesize a range of clinical observations and initial case series describing potential neurologic manifestations of COVID-19 and place these observations in the context of coronavirus neuro-pathophysiology as it may relate to SARS-CoV-2 infection. Reported nervous system manifestations range from anosmia and ageusia, to cerebral hemorrhage and infarction. While the volume of COVID-19-related case studies continues to grow, previous work examining related viruses suggests potential mechanisms through which the novel coronavirus may impact the CNS and result in neurological complications. Namely, animal studies examining the SARS-CoV have implicated the angiotensin-converting-enzyme-2 receptor as a mediator of coronavirus-related neuronal damage and have shown that SARS-CoV can infect cerebrovascular endothelium and brain parenchyma, the latter predominantly in the medial temporal lobe, resulting in apoptosis and necrosis. Human postmortem brain studies indicate that human coronavirus variants and SARS-CoV can infect neurons and glia, implying SARS-CoV-2 may have similar neurovirulence. Additionally, studies have demonstrated an increase in cytokine serum levels as a result of SARS-CoV infection, consistent with the notion that cytokine overproduction and toxicity may be a relevant potential mechanism of neurologic injury, paralleling a known pathway of pulmonary injury. We also discuss evidence that suggests that SARS-CoV-2 may be a vasculotropic and neurotropic virus. Early reports suggest COVID-19 may be associated with severe neurologic complications, and several plausible mechanisms exist to account for these observations. A heightened awareness of the potential for neurologic involvement and further investigation into the relevant pathophysiology will be necessary to understand and ultimately mitigate SARS-CoV-2-associated neurologic injury.


Asunto(s)
COVID-19/complicaciones , Enfermedades del Sistema Nervioso/virología , SARS-CoV-2/fisiología , COVID-19/diagnóstico , COVID-19/terapia , Humanos , Enfermedades del Sistema Nervioso/diagnóstico , Enfermedades del Sistema Nervioso/terapia
7.
Am J Prev Med ; 59(4): e149-e159, 2020 10.
Artículo en Inglés | MEDLINE | ID: mdl-32828587

RESUMEN

INTRODUCTION: The nutritional quality of restaurant foods in Canada is not monitored by government and limited research has evaluated the nutrient content of these foods. Given the increasing proportion of foods consumed outside the home, this study aims to assess levels of nutrients of public health concern in Canadian fast-food and sit-down restaurant menu items. METHODS: Levels of calories, saturated fat, sodium, and sugar of 10,285 menu items from 90 national chain restaurants in Canada were assessed. Data were collected in 2016, extracted and analyzed between 2018 and 2020, and presented overall and by category. Levels in fast-food and sit-down restaurant establishments were compared. RESULTS: Overall mean levels of saturated fat, sodium, and sugar were high. Entrées contained on average 52% of the total daily value for sodium (1,256 mg/serving) and 45% of the daily value for saturated fat (8.9 g/serving). Beverages and desserts had high levels of total sugar (mean=44 g and 32 g/serving, respectively) but tended to be low in sodium. Sit-down restaurant items had significantly (p≤0.0001) higher levels of calories, saturated fat, and sodium overall, although fast-food restaurant items had higher average sugar levels because of the higher number of beverage and dessert items. CONCLUSIONS: Levels of nutrients of concern in Canadian menu items are excessive among most food categories. As the frequency of eating out in restaurants rises, government policies to promote reformulation and increase transparency of the nutritional content of these items are required to reduce their negative impact on public health.


Asunto(s)
Etiquetado de Alimentos , Restaurantes , Canadá , Estudios Transversales , Ingestión de Energía , Comida Rápida , Humanos , Nutrientes , Valor Nutritivo
8.
Ann Pharmacother ; 54(9): 866-871, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32070111

RESUMEN

Background: Standardized volume dosing of 23.4% hypertonic saline (HTS) exists for adults, but the concentration, dosing and administration of HTS in pediatrics is variable. With emerging pediatric experience of 23.4% HTS, a standard volume dose approach may be helpful. Objective: To describe initial experience with a standardized 23.4% HTS weight-based volume dosing protocol of 10, 20, or 30 mL in the pediatric intensive care unit. Methods: Standard volume doses of 23.4% HTS were developed from weight dosing equivalents of 3% HTS. Pre and post sodium and intracranial pressure (ICP) measurements were compared with paired t-test or Wilcoxon rank-sum test. The site of administration and complications were noted. Results: A total of 16 pediatric patients received 37 doses of 23.4% HTS, with the smallest patient weighing 11 kg. For protocol compliance, 17 doses (46%) followed recommended dosing, 19 were less volume than recommended (51%), and 1 dose (3%) was more than recommended. Mean increase in sodium was 3.5 mEq/L (95% CI = 2-5 mEq/L); P < 0.0001. The median decrease in ICP was 10.5 mm Hg (interquartile range [IQR] 8.3-19.5) for a 37% (IQR 25%-64%) reduction. Most doses were administered through central venous access, although peripheral intravenous administrations occurred in 4 patients without complication. Conclusion and Relevance: Three standard-volume dose options of 23.4% HTS based on weight increases sodium and reduces ICP in pediatric patients. Standard-volume doses may simplify weight-based dosing, storage and administration for pediatric emergencies, although the optimum dose, and safety of 23.4% HTS in children remains unknown.


Asunto(s)
Cuidados Críticos/normas , Hipertensión Intracraneal/tratamiento farmacológico , Presión Intracraneal/efectos de los fármacos , Solución Salina Hipertónica/administración & dosificación , Sodio/sangre , Adulto , Peso Corporal , Niño , Preescolar , Cálculo de Dosificación de Drogas , Femenino , Humanos , Infusiones Intravenosas , Hipertensión Intracraneal/sangre , Masculino , Registros Médicos , Pediatría , Estudios Retrospectivos , Solución Salina Hipertónica/efectos adversos
9.
Am J Prev Med ; 56(6): e195-e203, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-31104725

RESUMEN

INTRODUCTION: The objective of this study is to investigate the early impact of Canada's first provincewide mandatory menu-labeling legislation on calorie levels in foods offered on chain restaurant menus before, leading up to, and at the point-of-implementation. METHODS: Data were obtained from Menu-FLIP, a database of publicly available nutrition data from chain restaurants in Canada. Data were collected in 2010, 2013, 2016, and 2017. Core food products, newly introduced products, discontinued products, and full menus were compared before (2010, 2013, 2016) and at the point-of-implementation (2017) of the policy. Calories and serving sizes of 2,988 unique foods (excluding beverages) from 28 chains were analyzed using mixed models comparing time points while controlling for covariates. Sub-analyses were stratified by restaurant type. RESULTS: Full menu mean calories and serving sizes increased between 2010 and 2017 (>40 calories and 17 grams, respectively). There were no significant changes in mean calories or serving sizes among core menu items (p=0.47). New products in 2013 and 2017 were significantly higher in calories and serving size versus discontinued foods and foods already on the menu. Discontinued foods did not differ in calories or serving size compared with foods already on the menu; however, in 2017, the calories of discontinued foods in sit-down restaurants were higher than foods discontinued in 2013 (p=0.02). CONCLUSIONS: The results of this investigation show that at the point-of-implementation of the Ontario Healthy Menu Choices Act supply-side calories in core food products, new products, or full menus evaluated in this study did not significantly change.


Asunto(s)
Ingestión de Energía , Etiquetado de Alimentos/legislación & jurisprudencia , Restaurantes/legislación & jurisprudencia , Restaurantes/estadística & datos numéricos , Humanos , Ontario
11.
Pediatrics ; 143(1)2019 01.
Artículo en Inglés | MEDLINE | ID: mdl-30545828

RESUMEN

A healthy 17-year-old boy with a high-functioning pervasive developmental disorder presented to the emergency department after having a 4-minute episode of seizure-like activity in the setting of presumed viral gastroenteritis. Within an hour of emergency department arrival, he developed a forehead-sparing facial droop, right-sided ptosis, and expressive aphasia, prompting stroke team assessment and urgent neuroimaging. Laboratory results later revealed a serum sodium of 119 mmol/L. Neurologic deficits self-resolved, and a full physical examination revealed diffuse abdominal tenderness in the lower abdomen with rebound tenderness in the right-lower quadrant. The patient was admitted to the PICU for electrolyte management and monitoring. A computed tomography (CT) scan of the abdomen obtained the following morning revealed the patient's final diagnosis.


Asunto(s)
Dolor Abdominal/diagnóstico por imagen , Apendicitis/diagnóstico por imagen , Trastorno Autístico/diagnóstico por imagen , Convulsiones/diagnóstico por imagen , Dolor Abdominal/complicaciones , Dolor Abdominal/cirugía , Adolescente , Apendicitis/complicaciones , Apendicitis/cirugía , Trastorno Autístico/complicaciones , Trastorno Autístico/cirugía , Gastroenteritis/complicaciones , Gastroenteritis/diagnóstico por imagen , Gastroenteritis/cirugía , Humanos , Masculino , Convulsiones/complicaciones , Convulsiones/cirugía
12.
Pediatr Crit Care Med ; 19(11): 1039-1045, 2018 11.
Artículo en Inglés | MEDLINE | ID: mdl-30134362

RESUMEN

OBJECTIVES: Pediatric neurocritical care as a conceptual service is relatively new, and implementation of such specialized services may improve outcomes for children with disorders of the brain or spinal cord. How many pediatric neurocritical care services currently exist in the United States, and attitudes about such a service are unknown. DESIGN: Web-based survey, distributed by e-mail. SETTING: Survey was sent to PICU Medical Directors and Program Directors of Pediatric Neurosurgery fellowship and Child Neurology residency programs. PATIENTS: None. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: A total of 378 surveys were distributed; 161 respondents representing 128 distinct hospitals completed the survey (43% response rate). Thirty-five percent (45/128) reported having a pediatric neurocritical care service. The most common type of service used a consultation model (82%; 32/39 responses). Other types of services were intensivist-led teams in the PICU (five hospitals) and dedicated PICU beds (two hospitals). Hospital characteristics associated with availability of pediatric neurocritical care services were level 1 trauma status (p = 0.017), greater numbers of PICU beds (χ [6, n = 128] = 136.84; p < 0.01), and greater volume of children with pediatric neurocritical care conditions (χ [3, n = 128] = 20.16; p < 0.01). The most common reasons for not having a pediatric neurocritical care service were low patient volume (34/119 responses), lack of subspecialists (30/119 responses), and lack of interest by PICU faculty (25/119 responses). The positive impacts of a pediatric neurocritical care service were improved interdisciplinary education/training (16/45 responses), dedicated expertise (13/45 responses), improved interservice communication (9/45 responses), and development/implementation of guidelines and protocols (9/45 responses). The negative impacts of a pediatric neurocritical care service were disagreement among consultants (2/45 responses) and splitting of the PICU population (2/45 responses). CONCLUSIONS: At least 45 specialized pediatric neurocritical care services exist in the United States. Eighty percent of these services are a consultation service to the PICU. Hospitals with level 1 trauma status, greater numbers of PICU beds, and greater numbers of patients with pediatric neurocritical care conditions were associated with the existence of pediatric neurocritical care as a clinical service.


Asunto(s)
Actitud del Personal de Salud , Cuidados Críticos/métodos , Unidades de Cuidado Intensivo Pediátrico , Niño , Enfermedad Crítica/epidemiología , Humanos , Unidades de Cuidado Intensivo Pediátrico/organización & administración , Unidades de Cuidado Intensivo Pediátrico/estadística & datos numéricos , Neurología , Pediatría , Encuestas y Cuestionarios , Estados Unidos/epidemiología
13.
CMAJ Open ; 6(1): E118-E125, 2018 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-29514800

RESUMEN

BACKGROUND: Restaurant foods have high sodium levels, and efforts have been made to promote reductions. The objective of this study was to understand if salt substitutes and enhancers are associated with changes in sodium levels in fast-food restaurants. METHODS: A longitudinal database (MENU-FLIP) containing nutrition information for Canadian chain restaurants with 20 or more locations nationally was created in 2010 and updated in 2013 and 2016. In 2016, when available, ingredient lists were collected from restaurant websites and searched for the presence of salt substitutes/enhancers. Changes in sodium levels (per serving) and the prevalence of salt substitutes/enhancers in 222 foods from 12 of the leading fast-food restaurant chains were compared across 3 time points. RESULTS: Sixty-nine percent of foods contained a salt substitute/enhancer. Substitutes/enhancers were found in every restaurant chain (n = 12) for which ingredient data were available. The most common substitutes/enhancers were yeast extracts (in 30% of foods), calcium chloride (28%), monosodium glutamate (14%) and potassium chloride (12%). Sodium levels in foods that contained substitutes/enhancers decreased significantly more (190 ± 42 mg/serving) over the study period than those in foods that did not contain a substitute/enhancer (40 ± 17 mg/serving, p < 0.001). INTERPRETATION: Salt substitutes and enhancers are prevalent in restaurant foods and are one means by which restaurants may be lowering sodium levels in their foods. At this time, the potential consequences of these findings, if any, are uncertain.

15.
J Nutr Educ Behav ; 49(6): 457-465.e1, 2017 06.
Artículo en Inglés | MEDLINE | ID: mdl-28363803

RESUMEN

OBJECTIVE: To test the effect of a nutrition intervention that included education and 2 labeling components on students' food choices. DESIGN: Repeat cross-sectional study taking place on 6 dinner occasions before and 6 afterward. SETTING: The study was conducted during dinner meals in a buffet-style dining hall in a university campus residence, where students paid a set price and consumed all they cared to eat. PARTICIPANTS: University students (n = 368 to 510) visited the cafeteria on each of the data collection dates. INTERVENTION: Fruit and vegetable consumption were encouraged; sugar-sweetened beverage consumption was discouraged using physical activity calorie equivalent labeling. MAIN OUTCOME MEASURES: Beverage choices and vegetable/fruit bar visits. ANALYSIS: Logistic regression was used to compare the proportion of student who selected each beverage, fruit, or vegetable before and after the intervention, while controlling for menu and gender as covariates. RESULTS: There was a significant decrease in the proportion of students selecting a sugar-sweetened beverage before vs after the intervention (49% vs 41%, respectively; P = .004) and an increase in students choosing water (43% vs 54%, respectively; P < .001). There was a significant increase in students who took fruit after the intervention (36%; P < .001) vs before (30%). The number of students visiting the vegetable bar significantly increased from 60% to 72% (P < .001). CONCLUSIONS: This intervention may be a way to encourage healthy dietary choices in campus dining halls.


Asunto(s)
Bebidas , Dieta/estadística & datos numéricos , Frutas , Promoción de la Salud/métodos , Estudiantes/estadística & datos numéricos , Verduras , Adulto , Estudios Transversales , Ejercicio Físico , Conducta Alimentaria , Femenino , Etiquetado de Alimentos , Humanos , Masculino , Universidades , Adulto Joven
16.
Nutrients ; 9(4)2017 Apr 19.
Artículo en Inglés | MEDLINE | ID: mdl-28422059

RESUMEN

Probiotic food products contain a variety of different bacterial strains and may offer different health effects. The objective was to document the prevalence and dosage of probiotic strains in the Canadian food supply and to review the literature investigating these strains in order to understand what health benefits these products may offer. The Food Label Information Program was used to identify probiotic-containing products in the food supply. PubMed, Web of Science, and Embase were searched for randomized controlled trials that tested the health effects of these strains in humans. There were six probiotic strains/strain combinations identified in the food supply. Thirty-one studies investigated these strains and found that they are associated with decreased diarrhea and constipation, improved digestive symptoms, glycemic control, antioxidant status, blood lipids, oral health, and infant breastfeeding outcomes, as well as enhanced immunity and support for Helicobacter pylori eradication. There were a limited number of studies investigating these strains. Many studies were funded by the food industry and tested dosages that were up to twenty-five times the dosage found in most food products. Probiotic food products could have health benefits not currently reported on their labels. However, many dosages are too low to provide the benefits demonstrated in clinical trials. Further research is needed to enable more effective use of these functional foods.


Asunto(s)
Análisis de los Alimentos , Probióticos/análisis , Canadá , Seguridad de Productos para el Consumidor , Bases de Datos Factuales , Dieta , Etiquetado de Alimentos , Humanos , Probióticos/administración & dosificación , Ensayos Clínicos Controlados Aleatorios como Asunto
17.
J Bone Joint Surg Am ; 98(24): e109, 2016 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-28002377

RESUMEN

BACKGROUND: The goal of this study was to evaluate the effectiveness of the American Orthopaedic Association's Own the Bone secondary fracture prevention program in the United States. METHODS: The objective of this quality improvement cohort study was dissemination of Own the Bone and implementation of secondary prevention (osteoporosis pharmacologic and bone mineral density [BMD] test recommendations). The main outcome measures were the number of sites implementing Own the Bone and implementation of secondary prevention, i.e., orders for BMD testing and/or pharmacologic treatment. The 177 sites participating in the program were academic and community hospitals, orthopaedic surgery groups, and a health system; data were obtained from the first 125 sites utilizing its registry, between January 1, 2010, and March 31, 2015. It included all patients, aged 50 years or older, presenting with fragility fractures (n = 23,132) who were enrolled in the Own the Bone web-based registry. The interventions were education, development of program elements, dissemination, implementation, and evaluation of the Own the Bone program at participating sites. RESULTS: A growing number of institutions implemented Own the Bone (14 sites in 2005-2006 to 177 sites in 2015). After consultation, 53% of patients had a BMD test ordered and/or pharmacologic therapy for osteoporosis. CONCLUSIONS: The Own the Bone intervention has succeeded in improving the behaviors of medical professionals in the areas of osteoporosis treatment and counseling, BMD testing, initiation of pharmacotherapy, and coordination of care for patients who have experienced a fragility fracture.


Asunto(s)
Conservadores de la Densidad Ósea/uso terapéutico , Densidad Ósea/efectos de los fármacos , Osteoporosis/tratamiento farmacológico , Fracturas Osteoporóticas/prevención & control , Anciano , Anciano de 80 o más Años , Conservadores de la Densidad Ósea/farmacología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sistema de Registros , Prevención Secundaria , Resultado del Tratamiento
18.
Neurocrit Care ; 23(2): 149-58, 2015 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-25693892

RESUMEN

BACKGROUND: Although attention to neurologic injuries and illnesses in pediatric critical care is not new, a sub-specialized field of pediatric neurocritical care has only recently been recognized. Pediatric neurocritical care is an emerging area of clinical and investigative focus. Little is known about the prevalence of specialized pediatric neurocritical care services nor about perceptions regarding how it is impacting medical practice. This survey sought to capture perceptions about an emerging area of specialized pediatric neurocritical care among practitioners in intersecting disciplines, including pediatric intensivists, pediatric neurologits and pediatric neurosurgeons. METHODS: A web-based survey was distributed via email to members of relevant professional societies and groups. Survey responses were analyzed using descriptive statistics. Differences in responses between groups of respondents were analyzed using Chi-squared analysis where appropriate. MAIN RESULTS: Specialized clinical PNCC programs were not uncommon among the survey respondents with 20% currently having a PNCC service at their institution. Despite familiarity with this area of sub-specialization among the survey respondents, the survey did not find consensus regarding its value. Overall, 46% of respondents believed that a specialized clinical PNCC service improves the quality of care of critically ill children. Support for PNCC sub-specialization was more common among pediatric neurologists and pediatric neurosurgeons than pediatric intensivists. This survey found support across specialties for creating PNCC training pathways for both pediatric intensivists and pediatric neurologists with an interest in this specialized field. CONCLUSIONS: PNCC programs are not uncommon; however, there is not clear agreement on the optimal role or benefit of this area of practice sub-specialization. A broader dialog should be undertaken regarding the emerging practice of pediatric neurocritical care, the potential benefits and drawbacks of this partitioning of neurology and critical care medicine practice, economic and other practical factors, the organization of clinical support services, and the formalization of training and certification pathways for sub-specialization.


Asunto(s)
Actitud del Personal de Salud , Cuidados Críticos , Encuestas de Atención de la Salud/estadística & datos numéricos , Neurología , Pediatría , Calidad de la Atención de Salud , Humanos
19.
Environ Sci Technol ; 48(7): 3815-21, 2014 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-24597860

RESUMEN

The photochemical reduction of Fe(III) complexes to Fe(II) is a well-known initiation step for the production of reactive oxygen species (ROS) in sunlit waters. Here we show a geochemical mechanism for the same in dark environments based on the tidally driven, episodic movement of anoxic groundwaters through oxidized, Fe(III) rich sediments. Sediment samples were collected from the top 5 cm of sediment in a saline tidal creek in the estuary at Murrell's Inlet, South Carolina and characterized with respect to total Fe, acid volatile sulfides, and organic carbon content. These sediments were air-dried, resuspended in aerated solution, then exposed to aqueous sulfide at a range of concentrations chosen to replicate the conditions characteristic of a tidal cycle, beginning with low tide. No detectable ROS production occurred from this process in the dark until sulfide was added. Sulfide addition resulted in the rapid production of hydrogen peroxide, with maximum concentrations of 3.85 µM. The mechanism of hydrogen peroxide production was tested using a simplified three factor representation of the system based on hydrogen sulfide, Fe(II) and Fe(III). The resulting predictive model for maximum hydrogen peroxide agreed with measured hydrogen peroxide in field-derived samples at the 95% level of confidence, although with a persistent negative bias suggesting a minor undiscovered peroxide source in sediments.


Asunto(s)
Sedimentos Geológicos/química , Hierro/química , Especies Reactivas de Oxígeno/química , Peróxido de Hidrógeno/química , Sulfuro de Hidrógeno/análisis , Modelos Teóricos , Oxidación-Reducción , South Carolina , Factores de Tiempo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...