RESUMEN

Urban centres acquire and accumulate many materials from their hinterland, among these are nutrient elements such as nitrogen (N). The popular North American vision of a peri-urban setting is one where urban food production, composting and re-cycling are assumed to limit urban accumulation of nutrients. This study quantifies this assumption using the Lower Fraser Valley (LFV) of British Columbia as an example, ideal because it is surrounded by mountains, ocean and an international border which collectively delimit the peri-urban boundaries. Nitrogen influxes are dominated by livestock feed imports to support dairy and poultry production (18000 tonnes N), followed by human food imports (9210 tonnes N), as well as 5410 tonnes N as fertilizer and 4690 tonnes N in atmospheric deposition. There is a transfer of 6700 tonnes N from agricultural to urban ecosystems displacing food imports, but food production contributes to the N footprint of the LFV. Nitrogen effluxes are dominated by sewage disposal (10400 tonnes N), solid waste disposal (7020 tonnes N) and atmospheric emissions (9460 tonnes N). The total influx is 15 kg N per person, the net influx is 3.1 kg N per person. Per unit land area, these are a total influx of 24 kg N/ha and a net influx of 4.7 kg N/ha. The atmospheric emissions are 4.7 kg N per person and 7.2 kg/ha. The N in soil is mobile and it is assumed soil N is at a steady state concentration, thus the surplus N is lost from the soil, probably by leaching and runoff. The Fraser River is estimated to acquire and transport 5230 tonnes N from the region into the ocean each year, in addition to 10300 tonnes N from sewage outfall. This is coupled with effluxes of phosphorus (estimated previously), and the result probably has an impact on the coastal waters. There is little reuse of imported N and current waste management practices including composting and combustion do little to improve N efficiency.

Asunto(s)

Ecosistema , Ciclo del Nitrógeno , Animales , Colombia Británica , Fertilizantes , Humanos , Nitrógeno

RESUMEN

There have been revisions in the composition of swine diets in the last two decades that not only improved production profitability but also had potential environmental benefits. Among other changes, the use of phytase in feed has enabled lower total P concentrations. Nitrogen, specifically protein, concentrations are expected to be lower, and certain trace elements were also expected to change. In this study, analyses of 1195 swine slurry manure samples from various barn types in Manitoba, Canada, collected from 1997 to 2002 were compared with similar analyses from 2010 and 2017. Concentrations of P were significantly lower in 2017, from a median in sow barns of 28.0 g kg dry weight (dw) in 1998 to 2002 to 20.6 g kg dw in 2010 and 2017, and from a median in feeder finisher barns of 24.1 g kg dw in 1998 to 2002 to 18.7 g kg dw in 2010 and 2017. Total N levels did not change with time, but the fraction of manure N that was NH decreased. Zinc concentrations were consistently higher in nursery manures than in other swine manures and increased from a median of 2800 mg kg dw in nursery barns in 1998 to 2002 to 5580 mg kg dw in nursery barns in 2010 and 2017. Concentrations of most other trace elements decreased over this time period. With the exception of Zn from nursery barns, these temporal changes should lessen the potential for environmental consequences from swine manure application to land.

Asunto(s)

Estiércol , Oligoelementos , Animales , Canadá , Femenino , Nitrógeno , Porcinos

RESUMEN

OBJECTIVES: Many Veterans suffer from substance use disorders (SUDs). Treatment challenges include poor treatment engagement and high relapse rates. Complementary interventions have the potential to enhance both. This study was a preliminary evaluation of sailing adventure therapy (SAT) for this population. DESIGN: Retrospective chart review. Participants in the intervention were 22 Veterans (20 male, 2 female) aged 22-65 who entered a Veterans Administration residential SUD treatment program. All subjects had two or more SUDs, and many had psychiatric (95%) and/or medical (77%) comorbidities. The age, gender and diagnosis-matched control group (n = 22) received residential SUD treatment as usual (TAU) in the same program but without SAT. SETTING: Residential SUD treatment program at a Veterans Administration Medical Center. INTERVENTION: Sailing adventure therapy. MAIN OUTCOME MEASURES: Positive and Negative Affect Schedule (PANAS), State Trait Anxiety Inventory six-item short form (STAI: Y-6 item), Acceptance and Action Questionnaire II (AAQ II), Five Facet Mindfulness Questionnaire (FFMQ) and a locally developed patient survey. Outcome comparison among SAT plus TAU group versus TAU - only group included measures of successful completion of residential SUD treatment program as well as psychiatric hospitalizations and/or residential SUD treatment program readmissions within 12 months. RESULTS: Neither physical injuries nor increases in anxiety or negative affect occurred, as measured by the PANAS (positive change, p = 0.351; negative change, p = 0.605) and the STAI: Y-6 item (p = 0.144) respectively. There was no significant change in FFMQ (p = 0.580) but a significant increase occurred in AAQ II scores (p = 0.036) indicating an increase in psychological flexibility. Survey responses indicated the participants perceived the experience to be both pleasurable and calming. The preliminary outcome evaluation revealed a significant between-group difference (X2 = 5.34, DF = 1, p = 0.02, r = 0.35) indicating participating in SAT was associated with a greater likelihood of successfully completing residential SUD treatment. However, there were no significant between-group differences in number of psychiatric hospitalizations (X2 = 1.09, DF = 1, p = 0.29, r = 0.16) or residential substance abuse treatment program readmissions (X2 = 0.23, DF = 1, p = 0.64, r = 0.07) in the 12 months after discharge from the program. CONCLUSIONS: Preliminary evidence suggests that SAT is physically safe and not associated with increased anxiety or negative affect. Participant's perceptions of the experience were positive. Preliminary outcome measures suggest associations between participation in SAT and increased psychological flexibility as well as successful completion of a residential SUD treatment program. Further research is indicated to determine whether SAT may be developed as an effective complementary intervention for Veterans with SUDs.

Asunto(s)

Terapias Complementarias , Terapia Recreativa , Trastornos Relacionados con Sustancias/terapia , Veteranos , Deportes Acuáticos , Adulto , Anciano , Terapias Complementarias/efectos adversos , Terapias Complementarias/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Seguridad del Paciente , Adulto Joven

Asunto(s)

Radón

RESUMEN

Excess phosphorus (P) in peri-urban regions is an emerging issue, whereas there is global depletion of quality mined supplies of P. The flow of P across the landscape leading to regional surpluses and deficits is not well understood. We computed a regional P budget with internal P flows in a fairly discreet peri-urban region (Lower Fraser Valley, BC) with closely juxtaposed agricultural and non-agricultural urban ecosystems, in order to clarify the relationship between food production, food consumption and other activities involving use of P (e.g. keeping pets and horses and using soaps). We hypothesized changes that might notably improve P efficiency in peri-urban settings and wider regions. Livestock feed for the dairy and poultry sectors was the largest influx of P: the peri-urban land is too limited to grow feed grains and they are imported from outside the region. Fertilizer and import of food were the next largest influxes of P and a similar amount of P flows as food from the agricultural to urban ecosystems. Export of horticultural crops (berries and greenhouse crops) and poultry represented agricultural effluxes that partially offset the influxes. P efficiency was lower for horticultural production (21%) than animal production (32%), the latter benefited from importing feed crops, suggesting a regional advantage for animal products. There was 2.0, 3.8, 5.7 and 5.6 tonnes imported P per $ million farm cash receipts for horticulture, dairy, poultry meat and eggs. Eliminating fertilizer for corn and grass would reduce the ratio for the dairy industry. The net influx, dominated by fertilizer, animal feed and food was 8470 tonnes P per year or 3.2 kg P per person per year, and of this the addition to agricultural soils was 3650 tonnes P. The efflux in sewage effluent to the sea was 1150 tonnes P and exported sewage solids was 450 tonnes P. Municipal solid waste disposal was most difficult to quantify and was about 1800 tonnes P, 80% of which was partly reused in the urban regions and partly sequestered in landfill, which may be considered an efflux or a surplus. Reuse of rendering waste for feeding poultry significantly reduced P importation, but no rendering waste is used for cattle due to health concerns. Sensitivity analysis showed that variation in human population and the amount of P consumed per person in chicken and dairy products had the most influence on the total movement of P from agricultural to urban-ecosystems. There are current farm practices that mitigate P surpluses and new technologies are being developed to further reduce farm imbalances. However, current waste management policies that promote practices such composting of home wastes and exporting of poultry manure and biosolids to semiarid rangeland do little to enhance overall P cycling because the P is not returned to the farms producing feed and food for the peri-urban region. Sequestering in landfills may be a better solution until better ways are found to return surplus P.

Asunto(s)

Industria de Alimentos , Fósforo/análisis , Agricultura , Alimentación Animal/análisis , Animales , Bovinos , Productos Agrícolas , Ecosistema , Ambiente , Fertilizantes , Geografía , Humanos , Residuos Industriales , Estiércol , Aves de Corral , Eliminación de Residuos , Aguas del Alcantarillado , Suelo , Instalaciones de Eliminación de Residuos , Administración de Residuos

RESUMEN

Acute appendicitis is one of the most common etiologies for acute abdomen. However, fewer than 30 cases of acute appendicitis after liver transplantation have so far been reported in the literature. Previous case studies have concluded that acute appendicitis after liver transplantation may present differently than in non-immunosuppressed patients and thus may lead to more complications. Herein, we describe the fourth case of laparoscopic appendectomy in a 40-year-old female presenting with an acute abdomen, 10 years after orthotopic liver transplantation for autoimmune hepatitis. Additionally, we review the literature, and emphasize the importance for laparoscopic, rather than open appendectomy after liver transplantation. Overall, despite the small number of reported cases of appendicitis after orthotopic liver transplantation, we found the incidence and clinical presentation are similar to patients without liver transplantation. The etiologies for appendicitis in patients after liver transplantation may be different than in those not chronically immunosuppressed, with significantly less lymphoid hyperplasia and increased fecalith and cytomegaloviral infections. Preliminary results showed that laparoscopic appendectomy after liver transplantation results in decreased hospital stays and fewer complications.

Asunto(s)

Publicaciones Periódicas como Asunto , Plagio , Contaminantes Radiactivos

RESUMEN

Staphylococcus aureus bacteremia cases are complicated by bacterial persistence and treatment failure despite the confirmed in vitro susceptibility of the infecting strain to administered antibiotics. A high incidence of methicillin-resistant S. aureus (MRSA) bacteremia cases are classified as persistent and are associated with poorer patient outcomes. It is still unclear how S. aureus evades the host immune system and resists antibiotic treatment for the prolonged duration of a persistent infection. In this study, the genetic changes and associated phenotypic traits specific to S. aureus persistent bacteremia were identified by comparing temporally dispersed isolates from persistent infections (persistent isolates) originating from two independent persistent S. aureus bacteremia cases with the initial infection isolates and with three resolved S. aureus bacteremia isolates from the same genetic background. Several novel traits were associated specifically with both independent sets of persistent S. aureus isolates compared to both the initial isolates and the isolates from resolved infections (resolved isolates). These traits included (i) increased growth under nutrient-poor conditions; (ii) increased tolerance of iron toxicity; (iii) higher expression of cell surface proteins involved in immune evasion and stress responses; and (iv) attenuated virulence in a Galleria mellonella larva infection model that was not associated with small-colony variation or metabolic dormancy such as had been seen previously. Whole-genome sequence analysis identified different single nucleotide mutations within the mprF genes of all the isolates with the adaptive persistence traits from both independent cases. Overall, our data indicate a novel role for MprF function during development of S. aureus persistence by increasing bacterial fitness and immune evasion.

Asunto(s)

Bacteriemia/microbiología , Evasión Inmune , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/inmunología , Antibacterianos/farmacología , Bacteriemia/inmunología , Humanos , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Staphylococcus aureus Resistente a Meticilina/genética , Staphylococcus aureus Resistente a Meticilina/inmunología , Staphylococcus aureus Resistente a Meticilina/aislamiento & purificación , Pruebas de Sensibilidad Microbiana , Fenotipo , Infecciones Estafilocócicas/inmunología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación

RESUMEN

Tumour-initiating cells (TICs) have been identified in many solid human tumours, including malignant melanoma. In this study, an enriched TIC population was identified in two canine malignant melanoma cell lines (CML1 and CML6M) using cell surface markers and functional assays, including the sphere forming assay, aldehyde dehydrogenase (ALDH) assay, reverse transcriptase-polymerase chain reaction and γH2AX staining for double-stranded DNA (dsDNA)break identification and repair. The CD34(-) population of cells in both cell lines expressed stem cell genes, such as Oct4, Nanog and Ptch1, were more efficient at making spheres in adherence-free media conditions and were able to repair dsDNA breaks faster than the CD34(+) population. A subpopulation of cells with high expression of ALDH was identified in both cell lines by flow cytometry. The findings indicate the presence of TICs in two canine malignant melanoma cell lines.

Asunto(s)

Enfermedades de los Perros , Melanoma/metabolismo , Células Madre Neoplásicas/citología , Animales , Línea Celular Tumoral , Roturas del ADN de Doble Cadena , Perros , Citometría de Flujo , Histonas , Células Madre Neoplásicas/fisiología , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa

RESUMEN

Children undergoing magnetic resonance imaging (MRI) often require general anaesthesia (GA). Children under GA are at risk of decreases in body temperature. This risk may be greater during MRI due to MRI scanners requiring cool ambient temperatures. Conversely, radiofrequency radiation emitted by MRI scanners is absorbed by the patient as heat energy, creating a risk of an increase in body temperature. The aim of this study was to determine the proportion of anaesthetised children undergoing an MRI scan who develop hyperthermia or hypothermia, and the risk factors associated with temperature changes in these children. Pre-scan and post-scan tympanic temperatures were obtained from 193 children (aged three months to six years) undergoing an MRI procedure under GA. No active warming or cooling devices were used during the MRI scans. The median duration for anaesthesia was 42 minutes (35 to 57 minutes). Fifty-two percent of children were hypothermic after their scan, while no subjects were hyperthermic after their scan. The mean (± standard deviation) pre-scan temperature was 36.2°C±0.5°C, and the mean (± standard deviation) post-scan temperature was 35.9°C±0.6°C (an overall mean temperature decrease of 0.28°C was observed [95% confidence interval, -0.36°C to -0.19°C], P <0.001). In conclusion, core body temperature was found to decrease slightly during an MRI scan under GA. These results suggest that more focus is needed regarding the cooling effects of GA agents during MRI, as opposed to the heating effects of the MRI scanner.

Asunto(s)

Anestesia General/efectos adversos , Temperatura Corporal , Imagen por Resonancia Magnética/efectos adversos , Niño , Preescolar , Femenino , Humanos , Lactante , Masculino

Asunto(s)

Accidente Nuclear de Chernóbil , Accidente Nuclear de Fukushima , Radiobiología , Congresos como Asunto

Asunto(s)

Estiércol , Suelo , Agricultura , Fósforo , Oligoelementos

RESUMEN

A recent study measured transfer factors for 49 elements in hunter-killed Whitetail deer (Odocoileus virginianus), using concentrations in the stomach content as the substrate/denominator to compute muscle/vegetation concentration ratios (CR(m-stomach)) and daily fractional transfer factors (Ff). Using the stomach content ensured an accurate representation of what the deer ate, except that it was limited in time to the vegetation selected by the animal just before it was killed. Here, two alternatives are considered, one where the feed is represented by samples of 21 different vegetation types that deer may have eaten in the area (CR(m-plant)), and the other is using soil concentration in the region as the denominator (CR(m-soil)). The latter is the formulation used in the ERICA tool, and other sources, for risk assessment to non-human biota. Across elements, (log) concentrations in all the media were highly correlated. The stomach contents had consistently higher ash and rare earth element concentrations than the sampled (and washed) vegetation and this was attributed to soil or dust ingestion. This lends credence to the use of soil-based CRm-soil values, despite (or more accurately because of) the inclusive yet gross simplicity of the approach. However, it was clear that variation of CR(m-soil) values was larger than for CR(m-stomach) or CR(m-plant), even if soil load on vegetation was included in the latter values. It was also noted that the variation in CR(m-soil) computed from the product of CR(m-plant) and CR(plant-soil) (where CR(plant-soil) is the plant/soil concentration ratio) was somewhat larger than the variation inherent in CR(m-soil) data. Thus it is reasonable to estimate CR(m-soil) from CR(m-plant) and CR(plant-soil) if observed CR(m-soil) values are not available, but this introduces further uncertainty.

Asunto(s)

Ciervos/metabolismo , Contenido Digestivo/química , Plantas/metabolismo , Radioisótopos/metabolismo , Contaminantes del Suelo/metabolismo , Animales , Plantas/química , Radioisótopos/análisis , Contaminantes del Suelo/análisis

RESUMEN

Human campylobacteriosis exhibits a distinctive seasonality in temperate regions. This paper aims to identify the origins of this seasonality. Clinical isolates [typed by multi-locus sequence typing (MLST)] and epidemiological data were collected from Scotland. Young rural children were found to have an increased burden of disease in the late spring due to strains of non-chicken origin (e.g. ruminant and wild bird strains from environmental sources). In contrast the adult population had an extended summer peak associated with chicken strains. Travel abroad and UK mainland travel were associated with up to 17% and 18% of cases, respectively. International strains were associated with chicken, had a higher diversity than indigenous strains and a different spectrum of MLST types representative of these countries. Integrating empirical epidemiology and molecular subtyping can successfully elucidate the seasonal components of human campylobacteriosis. The findings will enable public health officials to focus strategies to reduce the disease burden.

Asunto(s)

Infecciones por Campylobacter/etiología , Adolescente , Adulto , Factores de Edad , Anciano , Animales , Animales Salvajes/microbiología , Aves/microbiología , Infecciones por Campylobacter/epidemiología , Pollos/microbiología , Niño , Preescolar , Humanos , Incidencia , Persona de Mediana Edad , Epidemiología Molecular/métodos , Tipificación de Secuencias Multilocus , Población Rural/estadística & datos numéricos , Escocia/epidemiología , Estaciones del Año , Viaje , Población Urbana/estadística & datos numéricos , Adulto Joven

RESUMEN

Modern animal feeds often include nutritional mineral supplements, especially elements such as Cu, P, Se, and Zn. Other sources of trace elements also occur in livestock systems, such as pharmaceutical use of As and Zn to control gut flora, Bi in dairy for mastitis control, and Cu as hoof dips. Additionally, potential exists for inadvertent inclusion of trace elements in feeds or manures. There is concern about long-term accumulation of trace elements in manured soil that may even exceed guideline "safe" concentrations. This project measured ∼60 elements in 124 manure samples from broiler, layer, turkey, swine grower, swine nursery, sow, dairy, and beef operations. The corresponding feeds were also analyzed. In general, concentrations in manure were two- to fivefold higher than those in feed: the manure/feed concentration ratios were relatively consistent for all the animal-essential elements and were numerically similar for many of the non-nutrient elements. To confirm the potential for accumulation in soil, total trace element concentrations were measured in the profiles of 10 manured and 10 adjacent unmanured soils. Concentrations of several elements were found to be elevated in the manured soils, with Zn (and P) the most common. One soil from a dairy standing yard had concentrations of B that exceeded soil health guideline concentrations. Given that the Cu/P and Zn/P ratios found in manure were greater than typically reported in harvested crop materials, these elements will accumulate in soil even if manure application rates are managed to prevent accumulation of P in soil.

Asunto(s)

Alimentación Animal/análisis , Estiércol/análisis , Eliminación de Residuos/métodos , Suelo/química , Oligoelementos/química , Animales , Bovinos , Conservación de los Recursos Energéticos , Monitoreo del Ambiente , Aves de Corral , Contaminantes del Suelo/química , Porcinos

RESUMEN

BACKGROUND: Tolfenamic acid (TA) is an NSAID currently under investigation as an anticancer agent in humans. TA induces proteosome-dependent degradation of transcription factors Sp 1, 3, and 4. These proteins are known to be overexpressed in many human cancers. HYPOTHESIS: To evaluate the protein expression of Sps in canine tissue, and efficacy of TA against several canine tumor cell lines. METHODS: Six canine cell lines (2 osteosarcoma, 2 mammary carcinoma, 2 melanoma) were evaluated. Protein levels of Sp 1-4 and their downstream targets were evaluated using Western Blots. Cell survival and TUNEL assays were performed on cell lines, and Sp1 expression was evaluated on histologic samples from archived canine cases. ANIMALS: Six immortalized canine cancer cell lines derived from dogs were used. Archived tissue samples were also used. RESULTS: Sps were highly expressed in all 6 cell lines and variably expressed in histologic tissues. TA decreased expression of Sps 1-4 in all cell lines. All of the downstream targets of Sps were inhibited in the cell lines. Variable Sp1 expression was identified in all histologic samples examined. TA significantly inhibited cell survival in all cell lines in a dose dependant fashion. The number of cells undergoing apoptosis was significantly increased (P < .05) in all cell lines after exposure to TA in a dose-dependent fashion. CONCLUSIONS, AND CLINICAL IMPORTANCE: Tolfenamic acid is a potential anticancer NSAID and further investigation is needed to determine its usefulness in a clinical setting.

Asunto(s)

Antiinflamatorios no Esteroideos/farmacología , Enfermedades de los Perros/tratamiento farmacológico , Proteínas de Neoplasias/metabolismo , Neoplasias/veterinaria , Factores de Transcripción Sp/metabolismo , ortoaminobenzoatos/farmacología , Animales , Western Blotting , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/patología , Neoplasias de la Mama/veterinaria , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Enfermedades de los Perros/metabolismo , Enfermedades de los Perros/patología , Perros , Femenino , Regulación Neoplásica de la Expresión Génica , Inmunohistoquímica , Melanoma/tratamiento farmacológico , Melanoma/patología , Melanoma/veterinaria , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , Neoplasias/tratamiento farmacológico , Neoplasias/metabolismo , Neoplasias/patología , Osteosarcoma/tratamiento farmacológico , Osteosarcoma/patología , Osteosarcoma/veterinaria , ARN Neoplásico/química , ARN Neoplásico/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/veterinaria , Factores de Transcripción Sp/biosíntesis , Factores de Transcripción Sp/genética , Regulación hacia Arriba/efectos de los fármacos

RESUMEN

Assessment of the potential environmental impacts of nuclear fuel waste involves multiple lines of argument, one of which is an evaluation of the possible increments to background concentrations of certain radionuclides. This is especially relevant for radionuclides such as (3)H, (36)Cl and (129)I where there is continuous cosmogenic or geogenic production. However, for (36)Cl and (129)I and certain U/Th-series radionuclides, data are scarce because the analysis methods are complex and costly. The present study used accelerator mass spectroscopy (AMS) to measure(36)Cl and (129)I in river waters throughout Canada. Radiochemical methods were used for (3)H and the selected U/Th-series radionuclides, and stable element concentrations were also determined. There were distinct differences in concentrations among the sites. Stable Cl and I tended to be at higher concentrations near the ocean or population centres. The (3)H was high in regions with power reactors. The (226)Ra, (235)U and (238)U concentrations were high in areas with known U mineralizations, as expected. The (36)Cl and (129)I concentrations were generally homogenous in mid-latitudes, but the (129)I concentration was lower in the one arctic site sampled. Because the stable and radioactive isotopes of Cl and I varied in response to different factors, the resulting specific activities were especially variable. Both Cl and I are homeostatically controlled in animals, thus it follows that dose from (36)Cl and (129)I will depend more closely on specific activity than concentration, and therefore the environmental increments of interest are in the specific activities rather than simply concentrations.

Asunto(s)

Radiación de Fondo , Agua Dulce/química , Radioisótopos/análisis , Contaminantes Radiactivos del Agua/análisis , Canadá , Monitoreo de Radiación

Asunto(s)

Radiación de Fondo , Sedimentos Geológicos/química , Minerales/análisis , Radioisótopos de Potasio/análisis , Monitoreo de Radiación/estadística & datos numéricos , Ríos , Torio/análisis , Uranio/análisis

RESUMEN

Discrepancies about probable no effect concentrations (PNEC) for uranium in soils may be because toxicity tests used freshly contaminated soils. This study used 3 soils amended with a range of uranium concentrations 10 years previously. The toxicity tests with northern wheatgrass (Elymus lanceolatus); earthworm (Eisenia andrei) were not affected below ~1,000 mg U kg(-1), and the soil arthropod Folsomia candida was not affected below ~350 mg U kg(-1). Survival of Orthonychiurus folsomi was diminished 20% (EC(20)) by ~85-130 mg U kg(-1), supporting a PNEC in the range of 100-250 mg U kg(-1) as derived previously.

Asunto(s)

Artrópodos/efectos de los fármacos , Oligoquetos/efectos de los fármacos , Plantas/efectos de los fármacos , Contaminantes Radiactivos del Suelo/toxicidad , Pruebas de Toxicidad/métodos , Uranio/toxicidad , Animales , Bioensayo

RESUMEN

An earlier preliminary paper is expanded. Women who had given birth to one or more infants with a neural tube defect were recruited into a trial of periconceptional vitamin supplementation. Two hundred mothers attending five centres were fully supplemented (FS), 50 were partially supplemented (PS), and 300 were unsupplemented (US). Neural tube defect recurrences in the study pregnancies were 1(0.5%), in FS, none in PS, and 13 (4%) in US mothers. The difference in outcome between FS and US mothers is significant. The most likely explanation is that supplementation has prevented some neural tube defects, but further studies are needed.

Asunto(s)

Defectos del Tubo Neural/historia , Atención Preconceptiva/historia , Vitaminas/historia , Femenino , Historia del Siglo XX , Humanos , Defectos del Tubo Neural/prevención & control , Embarazo , Vitaminas/uso terapéutico