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PubMed2006

Cognitive impairment.

As populations continue to age, the prevalence of dementia is expected to increase. AD is by far the most common cause of dementia. The clinical course of dementia represents the challenges that this disease presents. There are no truly effective therapies for treating dementia, and the cost effectiveness of ChEIs has been challenged; however, there has been an explosion of information about AD. Evidence-based practice parameters for diagnosis and management of dementia have been developed. There has been an increased interest in the possible prodromal states of dementia, such as MCI. The concept of MCI has risen in prominence in recent years; it is speculated that initiation of therapies early in the course of disease may be needed for them to be effective. Considering the enormous burdens that AD places on individuals and society, disease-modifying treatments for AD are needed desperately. There are promising avenues for the development of potentially disease-modifying therapies for this devastating disease.

Aged↗
PubMed2006

A linked spatial and temporal model of the chemical and biological status of a large, acid-sensitive river network.

Freshwater sensitivity to acidification varies according to geology, soils and land-use, and consequently it remains difficult to quantify the current extent of acidification, or its biological impacts, based on limited spot samples. The problem is particularly acute for river systems, where the transition from acid to circum-neutral conditions can occur within short distances. This paper links an established point-based long-term acidification model (MAGIC) with a landscape-based mixing model (PEARLS) to simulate spatial and temporal variations in acidification for a 256 km(2) catchment in North Wales. Empirical relationships are used to predict changes in the probability of occurrence of an indicator invertebrate species, Baetis rhodani, across the catchment as a function of changing chemical status. Results suggest that, at present, 27% of the river network has a mean acid neutralising capacity (ANC) below a biologically-relevant threshold of 20 microeq l(-1). At high flows, this proportion increases to 45%. The model suggests that only around 16% of the stream network had a mean ANC < 20 microeq l(-1) in 1850, but that this increased to 42% at the sulphur deposition peak around 1970. By 2050 recovery is predicted, but with some persistence of acid conditions in the most sensitive, peaty headwaters. Stream chemical suitability for Baetis rhodani is also expected to increase in formerly acidified areas, but for overall abundance to remain below that simulated in 1850. The approach of linking plot-scale process-based models to catchment mixing models provides a potential means of predicting the past and future spatial extent of acidification within large, heterogeneous river networks and regions. Further development of ecological response models to include other chemical predictor variables and the effects of acid episodes would allow more realistic simulation of the temporal and spatial dynamics of ecosystem recovery from acidification.

Acid Rain↗
PubMed2006

Stream fish assemblages and basin land cover in a river network.

This study focused on characterizing fish assemblages in the Adour-Garonne basin and identifying the relative influences of landscape-scale features on observed patterns in stream fish assemblages. Two different artificial neural network algorithms were used: a self-organizing map (SOM) and a multilayer perceptron (MLP). A SOM was applied to determine fish assemblage types, and a MLP was used to predict the fish assemblage types defined by the SOM. Thirty four species were collected at 191 sampling sites in a major river-system, the Adour-Garonne basin, and topographical factors, namely altitude, distance from source and surface area of drainage basin were measured. Using GIS, land cover types (agricultural land, forests and urbanized artificial surface) were calculated for each site and expressed as percentage of the surface area of basin. These variables were introduced to the MLP and factorial discriminant analysis for the prediction of assemblage types. As a result, the SOM distinguished three fish assemblage types according to the differences of species composition, and the assemblage types were better predicted with landscape-scale features by MLP than discriminant analysis. The percentages of agricultural land and the surface area of a basin showed the greatest influence on assemblage types 1 and 2, and distance from source was the most important factor to determine assemblage type 3.

Agriculture↗
PubMed2004

Biocenosis of BAC(F)s used for groundwater treatment.

The studies on the biocenosis of biologically active carbon filters (BAC(F)) used in treatment of Miocene water revealed the presence of protozoa of the group of flagellates and ciliates (Glaucoma sp., Opercularia sp.), saprophytic bacteria, phase I and II nitrifying bacteria, Fe(II) and Mn(II) oxidizing bacteria of the family Siderocapsaceae, Leptothrix ochracea and Pedomicrobium sp., as well as microscopic fungi. The stratification of biofilter colonisation by these microorganisms was found to be similar to that occurring in biofilters applied in sewage treatment. A hypothetical model of microbiological transformations in BAC(F)s, brought about by various physiological groups of microorganisms, is presented. It is shown that ozone pre-treatment of water dosed to the biofilter reduces the number of saprophytic bacteria and moulds in its upper layer, as well as Fe(II) oxidizing bacteria of the family Siderocapsaceae across the full section of the biofilter; it does not, however, influence the abundance of nitrifying phase I and II autotrophic bacteria and Mn(II) oxidizing bacteria of the family Siderocapsaceae. The abundance of microorganisms in the biofilter outflow is increased in comparison with that in untreated water; they do not, however, create a health hazard for human beings.

Animals↗
PubMed1984

Imaging of venous thromboemboli with labeled platelets.

Prevention and optimal treatment of venous thromboembolism requires techniques that can: (1) monitor patients at high risk; (2) promptly detect thromboemboli; (3) follow the course of patients during treatment. Multiple techniques have been introduced to assist in these tasks. Some have not been well validated. Others, while established as of substantial value, have limitations with respect to specificity, sensitivity, patient access, patient acceptability, or risk. The dynamic nature of venous thromboembolism makes it unlikely that any one procedure will satisfy all diagnostic needs. Platelets labeled with 111In (111In-P) have promise as a useful addition to the existing diagnostic armamentarium. Because 111In-P are incorporated into forming and growing thromboemboli, and can provide a gamma camera image, they offer certain potential advantages versus other techniques. However, to establish the clinical value and proper use of the 111In-P technique, additional investigations are needed to determine the impact of thrombus location, age, anticoagulant therapy, and imaging technique and timing upon in vivo visualization of thromboemboli.

Animals↗
PubMed1998

Chaos in the cardiovascular system: an update.

Rhythmic changes of blood pressure, heart rate, and other cardiovascular measures have drawn the attention of several investigators, since these oscillations can shed light onto the activity of the underlying control network. The overwhelming proportion of circulatory variations, however, are not linear, i.e., they do not consist of perfectly rhythmic components. Thus, these fluctuations are more adequately analysed by non-linear techniques, most of which are adopted from chaos theory. A spotlight issue of 'Cardiovascular Research' (Vol. 31, 1996), focused on chaos in the cardiovascular system. This current review outlines today's understanding of this field by presenting the major discoveries and developments which have taken place since then.

Blood Vessels↗
PubMed2002

The inhibition of marine nitrification by ocean disposal of carbon dioxide.

In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with pH values ranging from 6 to 8. In an effort to determine whether these CO2-induced pH changes have any effect on marine nitrification processes, surficial (euphotic zone) and deep (aphotic zone) seawater samples were sparged with CO2 for varying time durations to achieve a specified pH reduction, and the rate of microbial ammonia oxidation was measured spectrophotometrically as a function of pH using an inhibitor technique. For both seawater samples taken from either the euphotic or aphotic zone, the nitrification rates dropped drastically with decreasing pH. Relative to nitrification rates in the original seawater at pH 8, nitrification rates were reduced by ca. 50% at pH 7 and more than 90% at pH 6.5. Nitrification was essentially completely inhibited at pH 6. These findings suggest that the disposal of CO2 into mid or deep oceans will most likely result in a drastic reduction of ammonia oxidation rates within the pH plume and the concomitant accumulation of ammonia instead of nitrate. It is unlikely that ammonia will reach the high concentration levels at which marine aquatic organisms are known to be negatively affected. However, if the ammonia-rich seawater from inside the pH plume is upwelled into the euphotic zone, it is likely that changes in phytoplankton abundance and community structure will occur. Finally, the large-scale inhibition of nitrification and the subsequent reduction of nitrite and nitrate concentrations could also result in a decrease of denitrification rates which, in turn, could lead to the buildup of nitrogen and unpredictable eutrophication phenomena. Clearly, more research on the environmental effects of ocean disposal of CO2 is needed to determine whether the potential costs related to marine ecosystem disturbance and disruption can be justified in terms of the perceived benefits that may be achieved by temporarily delaying global warming.

Ammonia↗
PubMed2003

Bacterial contamination of Mediterranean coastal seawater as affected by riverine inputs: simulation approach applied to a shellfish breeding area (Thau lagoon, France).

Consequences of short-term changes in thermotolerant coliform loads on their spatio-temporal distribution in a Mediterranean lagoon with large-scale mollusk farming (Thau lagoon, France) were explored using a simulation approach. Simulations were based on bacterial transport and survival coupled models forced by the input of bacterial loads from the two main rivers (Vène and Pallas) that flow into the lagoon. Different flow types (reference, sudden and constant), bringing the same bacterial load, were considered and subsequent spatial and temporal bacterial contamination of lagoon surface water and shellfish was estimated. Simulation results showed that as long as loads were high, hydrodynamical processes governed the distribution of bacterial abundance in receiving areas. As soon as loads decreased or when time supply increased, biological die-off processes became dominant. Bacterial contamination of shellfish induced by the different flow types appeared to depend on the receiving area. In the case of Pallas River area, a sudden input of bacteria led to a high bacterial contamination of shellfish but only during a short period ( approximately 1 day). A constant input of the same amount of bacteria induced a lower but significant contamination during all the simulation period (10 days). On the contrary, bacterial inputs from the Vène River led to shellfish contamination only when bacteria were delivered through a flood event. Exposure time of bacteria to adverse environmental conditions appeared to be the main explanation to the above-mentioned differences. Consequences of our results in terms of environmental management strategy were discussed.

Animals↗
PubMed2001

Priority assessment of toxic substances in life cycle assessment. III: Export of potential impact over time and space.

Toxicity potentials are scaling factors used in life cycle assessment (LCA) indicating their relative importance in terms of potential toxic impacts. This paper presents the results of an uncertainty assessment of toxicity potentials for 181 substances that were calculated with the global nested multi-media fate, exposure and effects model USES-LCA. The variance in toxicity potentials resulting from choices in the modelling procedure was quantified by means of scenario analysis. A first scenario analysis showed to what extent potential impacts in the relatively short term are obscured by the inclusion of impacts on the very long term. Toxicity potentials representing potential impacts over time horizons of 20, 100 and 500 years were compared with toxicity potentials representing potential impacts over an infinite time horizon. Time horizon dependent differences up to 6.5 orders of magnitude were found for metal toxicity potentials, while for toxicity potentials of organic substances under study, differences remain within 0.5 orders of magnitude. The second scenario analysis addressed to what extent potential impacts on the continental scale are obscured by the inclusion of impacts on the global scale. Exclusion of potential impacts on the global scale changed the toxicity potentials of metals and volatile persistent halogenated organics up to 2.3 orders of magnitude. These scenario analyses also provide the basis for determining exports to future generations and outside the emission area.

Animals↗
PubMed2003

Estimation of effects of dioxins and dioxin-like PCBs on wildlife population--a case study on common cormorant.

We presented a method for quantitatively evaluating the effects of chemical pollutants in the environment on a wildlife population. We expressed the effects of exposure to dioxins and dioxin-like PCBs in Tokyo Bay sediment on a common cormorant (Phalacrocorax carbo) population in two ways. One was the changes in the intrinsic growth rate, and the other was the changes in the gross population size. The effects of exposure to the compounds were estimated by using the method of population ecology and available field data. Common cormorant population at Shinobazu Pond in Tokyo, Japan during 1974-1986 was selected as the target population. Intrinsic growth rate or gross size of the population based on the calculated residual level of dioxins and dioxin-like PCBs in the period was estimated to decrease to 89% or 85% of that without exposure to the compounds, respectively.

Animals↗
PubMedDate not supplied

Coping with relocation.

Explore the source record for details and available documents.

Adaptation, Psychological↗
PubMed2001

Population dynamics of transgenic microorganisms in the different microecosystem conditions.

The role of key environmental factors in adaptation of spore-forming and non-spore-forming transgenic microorganisms (TM) have been studied in model ecosystems. Model TM Escherichia coli Z905 (bearing plasmid genes of bacterial luminescence Ap (r) Lux+) has been found to have a higher adaptation potential than TM Bacillus subtilis 2335/105 (bearing genes of human alpha 2-interferon Km (r) Inf+), planned for employment as a living vaccine under varying environmental conditions. Effects of abiotic factors on migration of natural and recombinant plasmids between microorganisms under model ecosystem conditions has been estimated. The transgenic microorganisms with low copy number survived better under introduction conditions in the microcosms studied. This trend has been shown to be independent of the microcosm type and its complexity. Grant numbers: 99-04-96017, 25, 00-07-9011.

Adaptation, Physiological↗
PubMed2002

A study of relative horn fly, Haematobia irritans (Diptera: Muscidae), abundance on Holstein steers and steers of two Holstein crosses.

A study was performed to determine if the number of horn fly (Haematobia irritans) adults differ significantly on Holstein (black and white coat color), Holstein x Holstein Friesian (black and white coat color) and Holstein x Jersey (black coat color) steers, 10-12 months old at the onset of the study. All steers were run together on lucerne paddocks and the number of flies counted at 30-day intervals from September 2000 to August 2001. No significant differences (P > 0.05, test of Kruskal-Wallis) were found in fly numbers, even in the period April-May 2001 when the infestation reached its peak. We were unable to demonstrate that coat color influenced horn fly abundance in the present study. It appears that none of the biotypes evaluated had any advantage for natural control of H. irritans.

Animals↗
PubMed1999

Federal surveillance of veterinary drugs and chemical residues (with recent data).

The National Residue Program is a dynamic risk-based program involving many Federal agencies, with the objective of preventing illegal drug residues and chemicals in the food supply. Surveillance is the systematic collection, analysis, and interpretation of residue data for public health action. This consists of assessing the cause(s) of the problem, recommending educational incentives, and intervention of prevention and control measures. The role of residue databases in formulating policy decisions and identifying risk factors for drug residues is discussed. A descriptive analysis, of 5 years (1992-1996) field investigative reports of drug residue occurrence in food animals is presented. The results showed that violative residues occurred predominately in culled dairy cows and bob veal calves.

Animals↗
PubMed2000

[Tracheal gas insufflation associated with mechanical ventilation for CO2 removal].

OBJECTIVE: Tracheal gas insufflation (TGI) either continuously, or at inspiration, or at expiration, is a technique associated with mechanical ventilation aimed to enhance CO2 elimination in favouring washout of anatomical dead space. This article analyses the mechanism of action, the techniques and the effects of TGI in presence of hypercapnia, especially in the fame of ARDS in adults. DATA SOURCES: In addition to some historical or major references, the articles on TGI published over the past five years have been searched in the Medline data base. STUDY SELECTION: Articles with data on TGI associated with mechanical ventilation were selected. DATA EXTRACTION: Data on mechanisms of action, technical and practical aspects of TGI were extracted. DATA SYNTHESIS: CO2 elimination is increased when the TGI catheter tip is close to the carina, when the gas jet is directed towards the latter, by a continuous gas jet, by a high washing gas volume. The effect on oxygenation is minor. The work of breathing is decreased. An increased intracranial pressure is decreased. Circulatory effects are minor. The major risk is dynamic pulmonary over distension. Local complications include dessiccation and lesion of bronchial mucosa by the gas jet. CONCLUSION: In mechanically ventilated patients, additional TGI is a valuable technique for decreasing anatomical dead space. TGI decreases hypercapnia during mechanical ventilation with limited tidal volumes in permissive hypercapnia. Further clinical studies with large series of patients are required to assess the benefits and the effect of TGI on outcome.

Animals↗