RESUMO
PURPOSE: PCNL requires a lithotrite to efficiently break stones, and some devices include active suction to remove the fragments. We set out to determine the efficacy and safety of the Swiss LithoClast® Trilogy, in a prospective European multicentre evaluation and compared it to published stone clearance rates for Trilogy based on surface area (68.9 mm2/min) and using the 3D calculated stone volume (526.7 mm3/min). METHODS: Ten European centres participated in this prospective non-randomized study of Trilogy for PCNL. Objective measures of stone clearance rate, device malfunction, complications and stone-free rates were assessed. Each surgeon subjectively evaluated ergonomic and device effectiveness, on a 1-10 scale (10 = extremely ergonomic/effective) and compared to their usual lithotrite on a 1-10 scale (10 = extremely effective). RESULTS: One hundred and fifty seven PCNLs using Trilogy were included (53% male, 47% female; mean age 55 years, range 13-84 years). Mean stone clearance rate was 65.55 mm2/min or 945 mm3/min based on calculated 3D volume. Stone-free rate on fluoroscopy screening at the end of the procedure was 83%. Feedback for suction effectiveness was 9.0 with 9.1 for combination and 9.0 for overall effectiveness compared to lithotrite used previously. Ergonomic score was 8.1, the least satisfactory element. Complications included 13 (8.2%) Clavien-Dindo Grade II and 2 (1.3%) Grade III. Probe breakage was seen in 9 (5.7%), none required using a different lithotrite. CONCLUSIONS: We have demonstrated that Trilogy is highly effective at stone removal. From a user perspective, the device was perceived by surgeons to be highly effective overall and compared to the most commonly used previous lithotrite, with an excellent safety profile.
Assuntos
Cálculos Renais/cirurgia , Nefrolitotomia Percutânea/instrumentação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento , Adulto JovemRESUMO
Freshwater fish in several regions of New York State (NYS) are known to contain concentrations of mercury (Hg) associated with negative health effects in wildlife and humans. We collected blood and breast feathers from bald eagle (Haliaeetus leucocephalus) nestlings throughout NYS, with an emphasis on the Catskill region to determine their exposure to Hg. We assessed whether habitat type (lake or river), region (Delaware-Catskill region vs. rest of NY) or sample site elevation influenced Hg concentrations in bald eagle breast feathers using ANCOVA. The model was significant and accounted for 41% of the variability in log10 breast feather Hg concentrations. Mercury concentrations in nestling breast feathers were significantly greater in the Delaware-Catskill Region (geometric mean: 14.5 µg/g dw) than in the rest of NY (7.4 µg/g, dw), and greater at nests located at higher elevations. Habitat type (river vs. lake) did not have a significant influence on breast feather Hg concentrations. Geometric mean blood Hg concentrations were significantly greater in Catskill nestlings (0.78 µg/g ww) than in those from the rest of NY (0.32 µg/g). Mercury concentrations in nestling breast feathers and especially blood samples from the Delaware-Catskill region were generally greater than those reported for most populations sampled elsewhere, including areas associated with significant Hg pollution problems. Bald eagles can serve as valuable Hg bioindicators in aquatic ecosystems of NYS, particularly given their broad statewide distribution and their tendency to nest across all major watersheds and different habitat types.
Assuntos
Águias , Monitoramento Ambiental , Poluentes Ambientais/análise , Mercúrio/análise , Animais , Ecossistema , Plumas/química , New YorkRESUMO
Integrated high-resolution maps of carbon stocks and biodiversity that identify areas of potential co-benefits for climate change mitigation and biodiversity conservation can help facilitate the implementation of global climate and biodiversity commitments at local levels. However, the multi-dimensional nature of biodiversity presents a major challenge for understanding, mapping and communicating where and how biodiversity benefits coincide with climate benefits. A new integrated approach to biodiversity is therefore needed. Here, we (a) present a new high-resolution map of global above- and below-ground carbon stored in biomass and soil, (b) quantify biodiversity values using two complementary indices (BIp and BIr) representing proactive and reactive approaches to conservation, and (c) examine patterns of carbon-biodiversity overlap by identifying 'hotspots' (20% highest values for both aspects). Our indices integrate local diversity and ecosystem intactness, as well as regional ecosystem intactness across the broader area supporting a similar natural assemblage of species to the location of interest. The western Amazon Basin, Central Africa and Southeast Asia capture the last strongholds of highest local biodiversity and ecosystem intactness worldwide, while the last refuges for unique biological communities whose habitats have been greatly reduced are mostly found in the tropical Andes and central Sundaland. There is 38 and 5% overlap in carbon and biodiversity hotspots, for proactive and reactive conservation, respectively. Alarmingly, only around 12 and 21% of these proactive and reactive hotspot areas, respectively, are formally protected. This highlights that a coupled approach is urgently needed to help achieve both climate and biodiversity global targets. This would involve (1) restoring and conserving unprotected, degraded ecosystems, particularly in the Neotropics and Indomalaya, and (2) retaining the remaining strongholds of intactness. This article is part of the theme issue 'Climate change and ecosystems: threats, opportunities and solutions'.
Assuntos
Biodiversidade , Sequestro de Carbono , Mudança Climática , Conservação dos Recursos Naturais/métodos , EcossistemaRESUMO
The Global Deal for Nature (GDN) is a time-bound, science-driven plan to save the diversity and abundance of life on Earth. Pairing the GDN and the Paris Climate Agreement would avoid catastrophic climate change, conserve species, and secure essential ecosystem services. New findings give urgency to this union: Less than half of the terrestrial realm is intact, yet conserving all native ecosystems-coupled with energy transition measures-will be required to remain below a 1.5°C rise in average global temperature. The GDN targets 30% of Earth to be formally protected and an additional 20% designated as climate stabilization areas, by 2030, to stay below 1.5°C. We highlight the 67% of terrestrial ecoregions that can meet 30% protection, thereby reducing extinction threats and carbon emissions from natural reservoirs. Freshwater and marine targets included here extend the GDN to all realms and provide a pathway to ensuring a more livable biosphere.
Assuntos
Biodiversidade , Conservação dos Recursos Naturais , Planeta Terra , Ecossistema , Modelos Biológicos , Adaptação Fisiológica , Animais , Mudança Climática , HumanosRESUMO
Mercury (Hg) exposure was evaluated in bald eagles (Haliaeetus leucocephalus) in the lower Penobscot River watershed (PRW) in Maine to assess whether Hg discharges from a chlor-alkali plant (HoltraChem) influenced Hg concentrations in nestling tissues. Mean Hg concentrations in nestling blood and breast feathers sampled in marine and estuarine areas potentially contaminated with Hg from HoltraChem (the potential Hg impact zone) were significantly greater than those from reference sites spanning the Maine coast. To place Hg exposure in the potential Hg impact zone into a broader context, Hg exposure in bald eagle nestlings from four habitat types in the PRW was assessed. Mercury concentrations varied significantly across habitat types within the PRW, generally following the pattern: marine=estuarineAssuntos
Águias/metabolismo
, Monitoramento Ambiental
, Poluentes Ambientais/metabolismo
, Mercúrio/metabolismo
, Animais
, Plumas
, Maine
RESUMO
A crucial aspect of episodic memory formation is the way in which our experiences are stored within a coherent spatio-temporal context. We review research that highlights how the experience of a negative event can alter memory encoding in a complex manner, strengthening negative items but weakening associations with other items and the surrounding context. Recent evidence suggests that these opposing effects can occur through amygdala up-modulation to facilitate item encoding, while the hippocampal provision of contextual binding is down-modulated. We consider how these characteristics of memory for negative events might contribute to the development and maintenance of distressing intrusive imagery in posttraumatic stress disorder, and how they should influence therapeutic interventions.
RESUMO
We investigated mercury (Hg) concentrations in small fish (mainly yellow perch, Perca flavescens; â¼60% of fish collected) and in blood of common loons (Gavia immer) that prey upon them during the breeding season on lakes in 4 large, widely separated study areas in Canada (>13 lakes per study area; total number of lakes = 93). Although surface sediments from lakes near a base metal smelter in Flin Flon, Manitoba had the highest Hg concentrations, perch and other small fish and blood of common loon chicks sampled from these same lakes had low Hg concentrations similar to those from uncontaminated reference lakes. Multiple regression modeling with AIC analysis indicated that lake pH was by far the most important single factor influencing perch Hg concentrations in lakes across the four study areas (R(2) = 0.29). The best model was a three-variable model (pH + alkalinity + sediment Se; Wi = 0.61, R(2) = 0.85). A single-variable model (fish Hg) best explained among-lake variability in loon chick blood Hg (Wi = 0.17; R(2) = 0.53). From a toxicological risk perspective, all lakes posing a potential Hg health risk for perch and possibly other small pelagic fish species (where mean fish muscle Hg concentrations exceeded 2.4 µg/g dry wt.), and for breeding common loons (where mean fish muscle Hg concentrations exceeded 0.8 µg/g dry wt., and loon chick blood Hg exceeded 1.4 µg/g dry wt.) had pH < 6.7 and were located in eastern Canada.
Assuntos
Aves/sangue , Peixes , Mercúrio/análise , Poluentes Químicos da Água/análise , Animais , Canadá , Concentração de Íons de Hidrogênio , Lagos/química , Músculo Esquelético/química , PercasRESUMO
INTRODUCTION: Discussing and planning the appropriate management for suspicious renal masses can be challenging. With the development of nephrometry scoring methods, we aimed to evaluate the ability of the RENAL nephrometry score to predict both the incidence of postoperative complications and the change in renal function after a partial nephrectomy. METHODS: This was a retrospective study including 128 consecutive patients who underwent a partial nephrectomy (open and laparoscopic) for renal lesions in a tertiary UK referral centre. Univariate and multivariate ordinal regression models were used to identify associations between Clavien-Dindo classification and explanatory variables. The Kendall rank correlation coefficient was used to examine an association between RENAL nephrometry score and a drop in estimated glomerular filtration rate (eGFR) following surgery. RESULTS: An increase in the RENAL nephrometry score of one point resulted in greater odds of being in a higher Clavien-Dindo classification after controlling for RENAL suffix and type of surgical procedure (odds ratio [OR]: 1.29, 95% confidence interval [CI]: 1.04-1.64, p=0.043). Furthermore, a patient with the RENAL suffix 'p' (ie posterior location of tumour) had increased odds of developing more serious complications (OR: 2.60, 95% CI: 1.07-6.30, p=0.042). A correlation was shown between RENAL nephrometry score and postoperative drop in eGFR (Kendall's tau coefficient -0.24, p=0.004). CONCLUSIONS: To our knowledge, this is the first study that has shown the predictive ability of the RENAL nephrometry scoring system in a UK cohort both in terms of postoperative complications and change in renal function.
Assuntos
Neoplasias Renais/cirurgia , Nefrectomia/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Neoplasias Renais/patologia , Laparoscopia/efeitos adversos , Masculino , Pessoa de Meia-Idade , Nefrectomia/métodos , Tratamentos com Preservação do Órgão/efeitos adversos , Tratamentos com Preservação do Órgão/métodos , Valor Preditivo dos Testes , Estudos Retrospectivos , Medição de Risco/métodos , Índice de Gravidade de Doença , Adulto JovemRESUMO
The ability to self-localise and to navigate to remembered goals in complex and changeable environments is crucial to the survival of many mobile species. Electrophysiological investigations of the mammalian hippocampus and associated brain structures have identified several classes of neurons which represent information about an organism's position and orientation. These include place cells, grid cells, head direction cells, and boundary vector cells, as well as cells representing aspects of self-motion. Understanding how these neural representations are formed and updated from environmental sensory information and from information relating to self-motion is an important topic attracting considerable current interest. Here we review the computational mechanisms thought to underlie the formation of these different spatial representations, the interactions between them, and their use in guiding behaviour. These include some of the clearest examples of computational mechanisms of general interest to neuroscience, such as attractor dynamics, temporal coding and multi-modal integration. We also discuss the close relationships between computational modelling and experimental research which are driving progress in this area.
Assuntos
Biologia Computacional/métodos , Meio Ambiente , Hipocampo/fisiologia , Mamíferos/fisiologia , Modelos Neurológicos , Orientação/fisiologia , Percepção Espacial/fisiologia , Animais , Hipocampo/citologia , Ritmo Teta/fisiologiaRESUMO
Place and grid cells in the rodent hippocampal formation tend to fire spikes at successively earlier phases relative to the local field potential theta rhythm as the animal runs through the cell's firing field on a linear track. However, this 'phase precession' effect is less well characterized during foraging in two-dimensional open field environments. Here, we mapped runs through the firing fields onto a unit circle to pool data from multiple runs. We asked which of seven behavioural and physiological variables show the best circular-linear correlation with the theta phase of spikes from place cells in hippocampal area CA1 and from grid cells from superficial layers of medial entorhinal cortex. The best correlate was the distance to the firing field peak projected onto the animal's current running direction. This was significantly stronger than other correlates, such as instantaneous firing rate and time-in-field, but similar in strength to correlates with other measures of distance travelled through the firing field. Phase precession was stronger in place cells than grid cells overall, and robust phase precession was seen in traversals through firing field peripheries (although somewhat less than in traversals through the centre), consistent with phase coding of displacement along the current direction. This type of phase coding, of place field distance ahead of or behind the animal, may be useful for allowing calculation of goal directions during navigation.
Assuntos
Potenciais de Ação/fisiologia , Região CA1 Hipocampal/fisiologia , Córtex Entorrinal/fisiologia , Células Piramidais/fisiologia , Comportamento Espacial/fisiologia , Ritmo Teta/fisiologia , Animais , Região CA1 Hipocampal/citologia , Análise por Conglomerados , Córtex Entorrinal/citologia , Masculino , Ratos , Ratos Long-Evans , Análise de Regressão , Gravação em VídeoRESUMO
We present a GIS method to interpret qualitatively expressed socio-economic scenarios in quantitative map-based terms. (i) We built scenarios using local stakeholders and experts to define how major land cover classes may change under different sets of drivers; (ii) we formalized these as spatially explicit rules, for example agriculture can only occur on certain soil types; (iii) we created a future land cover map which can then be used to model ecosystem services. We illustrate this for carbon storage in the Eastern Arc Mountains of Tanzania using two scenarios: the first based on sustainable development, the second based on 'business as usual' with continued forest-woodland degradation and poor protection of existing forest reserves. Between 2000 and 2025 4% of carbon stocks were lost under the first scenario compared to a loss of 41% of carbon stocks under the second scenario. Quantifying the impacts of differing future scenarios using the method we document here will be important if payments for ecosystem services are to be used to change policy in order to maintain critical ecosystem services.
Assuntos
Ecossistema , Sistemas de Informação Geográfica , Modelos Teóricos , Fatores Socioeconômicos , TanzâniaRESUMO
The oscillatory interference model (Burgess et al. (2007) Hippocampus 17:801-812) explains the generation of spatially stable, regular firing patterns by medial entorhinal cortical (mEC) grid cells in terms of the interference between velocity-controlled oscillators (VCOs) with different preferred directions. This model predicts specific relationships between the intrinsic firing frequency and spatial scale of grid cell firing, the EEG theta frequency, and running speed (Burgess,2008). Here, we use spectral analyses of EEG and of spike autocorrelograms to estimate the intrinsic firing frequency of grid cells, and the concurrent theta frequency, in mEC Layer II in freely moving rats. The intrinsic firing frequency of grid cells increased with running speed and decreased with grid scale, according to the quantitative prediction of the model. Similarly, theta frequency increased with running speed, which was also predicted by the model. An alternative Moiré interference model (Blair et al.,2007) predicts a direction-dependent variation in intrinsic firing frequency, which was not found. Our results suggest that interference between VCOs generates the spatial firing patterns of entorhinal grid cells according to the oscillatory interference model. They also provide specific constraints on this model of grid cell firing and have more general implications for viewing neuronal processing in terms of interfering oscillatory processes.
Assuntos
Potenciais de Ação/fisiologia , Relógios Biológicos/fisiologia , Córtex Entorrinal/fisiologia , Rede Nervosa/fisiologia , Neurônios/fisiologia , Ritmo Teta , Animais , Simulação por Computador , Eletroencefalografia/métodos , Locomoção/fisiologia , Masculino , Potenciais da Membrana/fisiologia , Orientação/fisiologia , Ratos , Ratos Long-Evans , Corrida/fisiologia , Processamento de Sinais Assistido por Computador , Transmissão Sináptica/fisiologiaRESUMO
Fish-eating birds can be exposed to levels of dietary methylmercury (MeHg) known or suspected to adversely affect normal behavior and reproduction, but little is known regarding Hg's subtle effects on the avian brain. In the current study, we explored relationships among Hg, Se, and neurochemical receptors and enzymes in two fish-eating birds--common loons (Gavia immer) and bald eagles (Haliaeetus leucocephalus). In liver, both species demonstrated a wide range of total Hg (THg) concentrations, substantial demethylation of MeHg, and a co-accumulation of Hg and Se. In liver, there were molar excesses of Se over Hg up to about 50-60 microg/g THg, above which there was an approximate 1:1 molar ratio of Hg:Se in both species. However, in brain, bald eagles displayed a greater apparent ability to demethylate MeHg than common loons. There were molar excesses of Se over Hg in brains of bald eagles across the full range of THg concentrations, whereas common loons often had extreme molar excesses of Hg in their brains, with a higher proportion of THg remaining as MeHg compared with eagles. There were significant positive correlations between brain THg and muscarinic cholinergic receptor concentrations in both species studied; whereas significant negative correlations were observed between N-methyl-D-aspartic acid (NMDA) receptor levels and brain Hg concentration. There were no significant correlations between brain Se and neurochemical receptors or enzymes (cholinesterase and monoamine oxidase) in either species. Our findings suggest that there are significant differences between common loons and bald eagles with respect to cerebral metabolism and toxicodynamics of MeHg and Se. These interspecies differences may influence relative susceptibility to MeHg toxicity; however, neurochemical responses to Hg in both species were similar.
Assuntos
Aves/metabolismo , Encéfalo/efeitos dos fármacos , Águias/metabolismo , Compostos de Metilmercúrio/toxicidade , Selênio/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Biotransformação , Encéfalo/enzimologia , Encéfalo/metabolismo , Colinesterases/metabolismo , Remoção de Radical Alquila , Peixes/metabolismo , Cadeia Alimentar , Fígado/efeitos dos fármacos , Fígado/metabolismo , Mercúrio/metabolismo , Mercúrio/toxicidade , Compostos de Metilmercúrio/metabolismo , Monoaminoxidase/metabolismo , Receptores Muscarínicos/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Especificidade da Espécie , Distribuição Tecidual , Poluentes Químicos da Água/metabolismoRESUMO
BACKGROUND: This study aimed to determine whether the morbidity and outcome rates for laparoscopic transperitoneal dismembered pyeloplasty are different from those for dismembered pyeloplasty, to analyze the learning curve of laparoscopic pyeloplasty, and to determine whether preoperative stent placement affects outcome. METHODS: For this study, 49 laparoscopic pyeloplasties (period 2000-2005) and 51 open pyeloplasties (period 1992-2003) were reviewed. RESULTS: Compared with open procedures, laparoscopic procedures were associated with a longer mean operating time (159 vs 91 min; p < 0.001), a shorter mean time to normal diet (38 vs 72 h; p < 0.001), and a similar mean hospital stay (5 days; p = 0.6). The operative complication rates were 17% for primary laparoscopic pyeloplasties and 24% for primary open pyeloplasties. The rates were higher for secondary procedures. The success rates for primary and secondary procedures were, respectively, 98% (41/42) and 57% (4/7) for laparoscopy and 96% (46/48) and 67% (2/3) for open surgery. Failed procedures showed no improvement in loin pain or obstruction. At the 6-month follow-up evaluation, 29% of the open surgery patients but none of the laparoscopic surgery patients reported wound pain. CONCLUSIONS: The efficacy of laparoscopic pyeloplasty is equivalent to that of open pyeloplasty, with less wound pain at 6 months. The outcome for secondary procedures is inferior. There was a trend toward a reduction in complications and the conversion rates with time, suggesting that there may be a learning curve of approximately 30 laparoscopic pyeloplasty cases. Preoperative stent insertion did not seem to affect any objective measures of outcome for laparoscopic pyeloplasty.
Assuntos
Pelve Renal/cirurgia , Laparoscopia , Obstrução Ureteral/cirurgia , Adulto , Feminino , Humanos , Masculino , Estudos Retrospectivos , Resultado do Tratamento , Procedimentos Cirúrgicos Urológicos/métodosRESUMO
The hippocampal formation (HF) plays a key role in novelty detection, but the mechanisms remain unknown. Novelty detection aids the encoding of new information into memory-a process thought to depend on the HF and to be modulated by the theta rhythm of EEG. We examined EEG recorded in the HF of rats foraging for food within a novel environment, as it became familiar over the next five days, and in two more novel environments unexpectedly experienced in trials interspersed with familiar trials over three further days. We found that environmental novelty produces a sharp reduction in the theta frequency of foraging rats, that this reduction is greater for an unexpected environment than for a completely novel one, and that it slowly disappears with increasing familiarity. These results do not reflect changes in running speed and suggest that the septo-hippocampal system signals unexpected environmental change via a reduction in theta frequency. In addition, they provide evidence in support of a cholinergically mediated mechanism for novelty detection, have important implications for our understanding of oscillatory coding within memory and for the interpretation of event-related potentials, and provide indirect support for the oscillatory interference model of grid cell firing in medial entorhinal cortex.
Assuntos
Relógios Biológicos/fisiologia , Comportamento Exploratório/fisiologia , Hipocampo/fisiologia , Memória/fisiologia , Ritmo Teta , Acetilcolina/metabolismo , Potenciais de Ação/fisiologia , Animais , Fibras Colinérgicas/fisiologia , Eletroencefalografia , Potenciais Evocados/fisiologia , Masculino , Modelos Neurológicos , Atividade Motora/fisiologia , Vias Neurais/fisiologia , Neurônios/fisiologia , Ratos , Núcleos Septais/fisiologia , Fatores de TempoRESUMO
PURPOSE: Ureteral stents are composed of different polymers and it is unclear if stent composition influences patient comfort. We compared the impact of stents composed of firm and soft polymer on patient health related quality of life. MATERIALS AND METHODS: A total of 130 patients requiring insertion of ureteral stents during the treatment of urinary calculi were randomized to receive a stent composed of firm (Percuflex, group 1) or soft (Contour, group 2) polymer. Patients were asked to complete the Ureteric Stent Symptoms Questionnaire, a validated instrument, at weeks 1 and 4 with the stent in situ and 4 weeks after its removal, this served as the main outcome measure. Additional assessments included difficulty in stent insertion and the need for early stent removal. RESULTS: There were 78 men and 38 women in total (61 in group 1 and 55 in group 2) with a mean age of 51 years (range 22 to 79) and no difference in age between the 2 groups (p = 0.9). Comparison of the results of the Ureteric Stent Symptoms Questionnaire survey at weeks 1 and 4 with stent in situ revealed no significant differences in the domain scores of urinary symptoms (p = 0.9 and p = 0.8), pain (p = 0.8 and p = 0.6) and general health (p = 0.6 and p = 0.4). Similarly, there were no differences in the number of days with reduced activities, work performance (p = 0.7) and sexual dysfunction between the 2 groups. A similar number of patients (8 and 7 in groups 1 and 2, respectively) required stent removal earlier than planned due to stent related symptoms. CONCLUSIONS: This randomized study showed no difference in the impact on patient quality of life between ureteral stents composed of firm or soft polymer.
Assuntos
Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/uso terapêutico , Polímeros/química , Polímeros/uso terapêutico , Qualidade de Vida , Stents , Cálculos Ureterais/terapia , Adulto , Idoso , Materiais Revestidos Biocompatíveis/efeitos adversos , Remoção de Dispositivo , Feminino , Nível de Saúde , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Polímeros/efeitos adversos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Estudos Prospectivos , Perfil de Impacto da Doença , Método Simples-Cego , Stents/efeitos adversos , Inquéritos e Questionários , Resultado do Tratamento , Cálculos Ureterais/cirurgiaRESUMO
Polychlorinated biphenyls (PCBs) were measured in marine sediments and the coastal food web in Saglek Bay, Labrador, to investigate the influence of a local PCB source. Saglek Bay has been the site of a military radar station since the late 1950s and there was PCB-contaminated soil at a beach prior to cleanup in 1997-1999. PCB concentrations in marine sediments during 1997-1999 ranged from 0.24 to 62000 ng/g (dry weight) and decreased exponentially with distance from the contaminated beach. Given this gradient, spatial trends of PCBs in the food web were examined over four zones, according to distance from the contaminated beach: within 1.5 km--zone one, 1.5-4.5 km--zone two, 4.5-7.5 km--zone three, and greater than 7.5 km--zone four. PCB concentrations in a bottom-feeding fish (shorthorn sculpin, Myoxocephalus scorpius), decreased significantly from zone one to zone two, three, four, and distant Labrador reference sites. PCB concentrations in the eggs of a diving seabird (black guillemot, Cepphus grylle) were as high as 48000 ng/g during 1997-1999 and average concentrations in zones one and two were 84 and 13 times higher than in zone four. Marine invertebrates closely reflected the concentrations of PCBs in the associated sediment. In contrast to the benthic-based food web, anadromous arctic char (Salvelinus alpinus) showed no evidence of PCB accumulation from the contaminated sediments. Relatively high PCB concentrations were discovered in some great black-backed gulls (Larus marinus) and ringed seals (Phoca hispida) but appear to relate more to their high trophic level than sampling location. Those species that fed on or near the seabed and had limited foraging ranges were strongly influenced by the local contamination. Total PCB concentrations in the benthic-based food web were significantly higher than background levels for a distance of at least 7.5 km from the contaminated beach. This area is small in the context of widely distributed contamination from long-range transport but the area's high concentrations are comparable to levels associated with adverse effects elsewhere. Our findings should be useful to better assess the environmental impacts of PCB contamination at other coastal sites in the Arctic.
Assuntos
Cadeia Alimentar , Sedimentos Geológicos/análise , Bifenilos Policlorados/análise , Poluentes Químicos da Água/análise , Tecido Adiposo/química , Animais , Aves , Monitoramento Ambiental , Peixes , Invertebrados , Fígado/química , Masculino , Músculos/química , Terra Nova e Labrador , Óvulo/química , PhocaRESUMO
Different patterns of prefrontal activation are commonly found in studies of episodic and source memory (typically anterior and lateral) compared to those found in studies of autobiographical memory (typically ventromedial). We investigated a proposal that the former pattern reflects contextual interference when retrieving events that occurred in similar contexts. We used virtual reality to simulate contextually varied life-like events, in which subjects received distinct objects from a number of people in a number of locations. We compared fMRI data from two experiments in which the number of events per context varied. The first experiment (Burgess, N., Maguire, E.A., Spiers, H.J., and O'Keefe, J. 2001. A temporoparietal and prefrontal network for retrieving the spatial context of lifelike events. Neuroimage 14, 439-453) involved 16 objects received from one of two people in one of two locations. The second experiment involved 20 objects, each received from a different person in a different location. The first experiment showed extensive bilateral activation of anterior and lateral prefrontal cortex, as well as a medial temporal and parietal network characteristic of both autobiographical and episodic memory. In the second study, the prefrontal activations were largely absent, while the medial parietal and temporal activations remained, and a ventromedial prefrontal area was additionally activated. Direct comparisons revealed large areas of significantly reduced activation in BA10, with lesser reductions in lateral prefrontal regions. We suggest that involvement of these prefrontal regains in episodic and source memory reflects the use of paradigms involving many events and few sources rather than any fundamental processing requirement of contextual retrieval in the absence of interference.
Assuntos
Memória/fisiologia , Córtex Pré-Frontal/fisiologia , Adolescente , Adulto , Sensibilidades de Contraste , Sinais (Psicologia) , Interpretação Estatística de Dados , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Modelos NeurológicosRESUMO
Lowered extracellular pH in a variety of tissues is associated with increased tissue destruction and initiation of inflammatory processes. Although the acid-sensing receptors described previously are ion channels, we describe a G protein-coupled proton-sensitive receptor that stimulates Ca(2+) release from intracellular stores in a tumor-derived synoviocyte cell line (SW982) and in primary cultures of human synovial cells from patients with inflammatory arthropathies. We established a link between proton-dependent receptor activation and intracellular Ca(2+) mobilization by demonstrating 1) dependence on the integrity of the intracellular Ca(2+) store, 2) independence from extracellular Ca(2+), and 3) proton-induced production of inositol phosphate and 4) by abolishing the effect with GTPase inhibitors. We propose that this G protein-coupled acid-sensing receptor linked to intracellular Ca(2+) mobilization in synoviocytes can contribute to downstream inflammatory and cellular proliferative processes in synovial fibroblasts. The acid-sensing receptor has distinct characteristics as a metabotropic G protein-coupled receptor on human synoviocytes in this emerging new class of receptors.