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Overtraining does not mitigate contextual fear conditioning deficits produced by neurotoxic lesions of the basolateral amygdala.

The influence of overtraining on the magnitude of fear-conditioning deficits produced by neurotoxic lesions of the basolateral amygdala (BLA) was examined. Either 1 d before or 1 week after the administration of neurotoxic BLA lesions, rats received either 1 or 25 conditioning trials consisting of the delivery of unsignaled foot shock in a novel observation chamber; freezing served as the measure of conditional fear. In this conditioning paradigm, asymptotic performance is reached in five conditioning trials, and 25 conditioning trials constitutes an overtraining procedure. The results revealed that overtraining does not affect the magnitude of the contextual freezing deficits produced by post-training BLA lesions. Similarly, overtraining did not influence the level of reacquisition obtained by rats with post-training BLA lesions after 10 reacquisition trials. A similar pattern of results was observed in rats with pretraining BLA lesions. Neurotoxic BLA lesions did not alter either motor activity or shock reactivity. These results indicate that overtraining does not limit the important role of the BLA in the acquisition and expression of contextual fear conditioning.

Amygdala↗

Oxidative stress induced by environmental tobacco smoke in the workplace is mitigated by antioxidant supplementation.

Environmental tobacco smoke (ETS) is a pervasive contaminant in the workplace. Previous studies by this laboratory have shown that exposure to workplace ETS results in increased oxidative stress and damage, as measured by increased levels of the antioxidant enzymes superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase. 8-Hydroxy-2-deoxyguanosine, a marker of oxidative DNA damage, was also 63% greater in the exposed group compared with controls. Subjects in the previous study who reported workplace exposure to ETS were given a 60-day supply of an over-the-counter antioxidant formulation consisting of 3000 microg of beta-carotene, 60 mg of vitamin C, 30 I.U. of alpha-tocopherol, 40 mg of zinc, 40 microg of selenium, and 2 mg of copper. After the 60-day supplementation period, blood samples were again drawn, and the results were compared with the presupplementation values. A 62% decrease in 8-hydroxy-2-deoxyguanosine was observed after supplementation. Lipid peroxidation levels were also decreased, as were the antioxidant enzyme activities. The biochemical evidence suggests that exposure to ETS in the workplace increases oxidative stress and that antioxidant supplementation may provide some protection.

Adult↗

Direct and interacting toxicological effects on the waterflea (Daphnia magna) by natural organic matter, synthetic humic substances and cypermethrin.

Humic substances are the main component of dissolved organic matter in all aquatic ecosystems, comprising a variety of molecular structures and functional groups. They bind organic pollutants and metals, thereby decreasing the bioavailability and consequently the toxicity of these substances in most instances. Recent studies also describe direct interactions and effects on organisms. Current studies also show that in some cases mitigation effects are stronger at lower concentrations of natural organic matter (NOM) and that toxicity increases with increased NOM concentrations. We hypothetise that at higher concentrations the mitigating effects are overlayed by direct effects of NOM themselves, thus these aspects were investigated in combination. So, on the one hand, this study demonstrates direct effects on toxicological parameters and activities of transformation enzyme systems of Daphnia magna, provoked by two NOM and one synthetic humic-like substance, HS1500. On the other hand, capacities of NOM and synthetic HS1500 to mitigate effects of the insecticide cypermethrin were investigated. Taken together, mitigation effects were overlayed by direct own effects of the NOM and HS1500. The NOM used were isolates from Suwannee River (XAD, Spring 2000) and from streams of the Svartberget forest (reverse osmosis, Spring 2000). The HS1500 was synthetically produced by radicalic autoxidation of hydroquinones. Suwannee River NOM at concentrations between 50 and 100 mg/l, and HS1500 (10-50 mg/l), but not Svartberget NOM increased immobility and lethality of the daphnids. All elevated the activity of the soluble glutathione S-transferase from 0.5 mg/l (HS1500), 1.0 mg/l (Suwannee River NOM) and 10 mg/l (Svartberget NOM) onwards, the microsomal glutathione S-transferase did not react. The glutathione peroxidase tended to increase. In the single exposure, the insecticide cypermethrin increased all toxicological parameters, elevated soluble and tendentially microsomal glutathione S-transferase activity between 0.001 and 1.0 microg/l and tendentially increased glutathione peroxidase. In contrast to that, 50 mg/l of the NOM and HS1500 did not mitigate toxicological effects. HS1500 in combination with cypermethrin even increased immobility, compared to cypermethrin alone. Increase of the NOM or HS1500 concentrations in combination with cypermethrin did not increase mitigation as seen in the activity of soluble glutathione S-transferases, activities of microsomal glutathione S-transferase and glutathione peroxidase even decreased, relative to control, which can be a hint of enzyme disfunction or further damages in the cell. An increase of concentration did not increase mitigation. Mitigation was higher at lower NOM or HS1500 concentration, probably as a consequence of the direct effects caused by themselves. Consequently, direct effects are relevant for analysing the mitigation qualities.

Animals↗

ENVIRONMENTAL AUDITING: Indicators Assessment for Habitat Conservation Plan of Yolo County, California, USA.

/ Whereas habitat conservation plans (HCPs) have been intended to provide comprehensive environmental mitigation for multiple species, they often narrow in focus to one species and either one mitigation site or unspecified sites. We developed an indicators framework from which to rate land units for their ecological integrity, collateral values (nonbiological qualities that can improve conservation), and restoration and conservation opportunities. The ratings of land units were guided by the tenets of conservation biology and principles of landscape and ecosystem ecology, and they were made using existing physical and floral information managed on a GIS. As an example of how the indicators approach can be used for HCPs, the 29 legally rare species targeted by the Yolo County HCP were each associated with vegetation complexes and agricultural crops, the maps of which were used for rating some of the landscape indices. The ratings were mapped so that mitigation can be directed to the places on the landscape where the legally rare species should benefit most from conservation practices. The most highly rated land units for conservation opportunity occurred along streams and sloughs, especially where they emerged from the foothills and entered the Central Valley and where the two largest creeks intersected the Sacramento River flood basin. We recommend that priority be given to mitigation or conservation at the most highly rated land units. The indices were easy to measure and can be used with other tools to monitor the mitigation success. The indicators framework can be applied to other large-area planning efforts with some modifications.KEY WORDS: Ecosystem; Indicators; Landscape; Mitigation; Planning; Yolo County; California

Journal Article↗

Electricity from fossil fuels without CO2 emissions: assessing the costs of carbon dioxide capture and sequestration in U.S. electricity markets.

The decoupling of fossil-fueled electricity production from atmospheric CO2 emissions via CO2 capture and sequestration (CCS) is increasingly regarded as an important means of mitigating climate change at a reasonable cost. Engineering analyses of CO2 mitigation typically compare the cost of electricity for a base generation technology to that for a similar plant with CO2 capture and then compute the carbon emissions mitigated per unit of cost. It can be hard to interpret mitigation cost estimates from this plant-level approach when a consistent base technology cannot be identified. In addition, neither engineering analyses nor general equilibrium models can capture the economics of plant dispatch. A realistic assessment of the costs of carbon sequestration as an emissions abatement strategy in the electric sector therefore requires a systems-level analysis. We discuss various frameworks for computing mitigation costs and introduce a simplified model of electric sector planning. Results from a "bottom-up" engineering-economic analysis for a representative U.S. North American Electric Reliability Council (NERC) region illustrate how the penetration of CCS technologies and the dispatch of generating units vary with the price of carbon emissions and thereby determine the relationship between mitigation cost and emissions reduction.

Air Pollution↗

Assessing and managing biological risks of plants used for bioremediation, including risks of transgene flow.

The plants used for phytoremediation pose special biological risks, whether transgenic or not, as most of the species: (a) are semi-domesticated; (b) are introduced from other habitats; (c) can become established in the contaminated site; (d) can spread and displace native species, and/or; (e) may introgress transgenes into related species. The addition of transgenes can reduce the risks, e.g. to sterilize or render the species and hybrid offspring hypersensitive to environmental effects (heat, cold), or to a chemical that will cull the species. Various measures can contain transgenes used in phytoremediation species to prevent gene flow, but most containment technologies are both uni-directional (prevent either outflow or influx), and are inherently leaky, even a concept specifically utilizable for phytoremediation--grafting non-transgenic scions on bioremediating transgenic rootstocks. Containment mechanisms should be either stacked with each other or with "mitigator" genes. Transgenic mitigation (TM) has mitigator genes added in tandem to the desired primary transgene (genetically linked) and the mitigator genes confer traits that are positive or neutral to the desired species but are deleterious to hybrids, keeping them at very low frequencies. The concept was demonstrated in tobacco and oilseed rape with a dwarfing mitigator gene that enhanced the reproductive productivity (harvest index) when cultured alone, but eliminated it from mixed populations. Besides the mitigator genes previously proposed for crop species (sterility, no seed shattering, dwarfing, no secondary dormancy) there are genes especially appropriate for phytoremediation, e.g. overexpression of cytokinin oxidase (reduces cytokinin levels) conferring reduced shoot systems (unfitness to compete) with a more extensive root system that is better for extracting toxic wastes as well as no-flowering for vegetatively propagated species. Thus, biotechnology can be harnessed to reduce risks from both non-transgenic and transgenic phytoremediation species.

Biodegradation, Environmental↗

Positive-spillover effects from job to home: a closer look.

What is the association between subjective experiences in two roles, employee and mother, and women's psychological distress? Previous research indicated that employed mothers with troubled mother-child relationships reported high levels of psychological distress, unless they were in rewarding jobs. In this paper, using data from the same sample of 228 employed mothers, we explored further the above finding by addressing two related questions: (1) which job rewards mitigate the relationship between parent-role quality and psychological distress?; and (2) which parental concerns are buffered by these stress mitigators? The main finding was that having a rewarding job per se did not automatically serve as a parent-stress mitigator. Although several job-reward factors (e.g., Helping Others at Work, Challenge), were associated with reports of low distress, Challenge was the only job-reward factor that mitigated parental stress. Thus, the previously reported positive-spillover effect from work to home was attributable to the presence of rewards from challenging work. However, Challenge buffers only particular parent concerns. For employed mothers, a job high in rewards from Challenge mitigates the distress associated with Disaffection (not Burden or Safety) in their relationships with their children.

Adult↗

Maternal-fetal thyroid hormone relationships and the fetal brain.

Thyroid hormones are transferred from the mother to the fetus. Thus, despite the deiodinating enzymes of the placenta (26), some T4 and T3 is transferred, both before and after onset of fetal thyroid function, at least in those cases where fetal thyroid function is impaired. It is also possible that transfer occurs under normal conditions. Maternal to fetal transfer of T3 and T4 is partially limited. But it might be enough to mitigate severe fetal T4 and T3 deficiencies. However, the mitigating effects of both hormones are not equivalent for all fetal tissues. 1) Maternal T4 mitigates T4 and T3 deficiency of most fetal tissues, the brain included. 2) Maternal T3 mitigates T3 deficiency only in some fetal tissues, the brain being excluded. It does not mitigate cerebral T3 deficiency even at doses which are toxic for the mother, and it does not depress fetal plasma TSH. 3) Normal maternal thyroid function is important for fetal development. Maternal hypothyroxinemia is damaging to the developing fetal brain early in gestation. It might also later have adverse effects in gestation, if the fetal thyroid is impaired. Normal maternal T3 levels might avoid overt hypothyroidism of some fetal tissues, but is of no benefit to the brain.

Animals↗

Prevention versus treatment for malaria in pregnant women.

OBJECTIVES: Malaria contributes to antenatal anaemia and slowing of fetal growth, especially in first-time mothers. It is thought that these effects harm the mother and baby, and interventions to prevent or mitigate the effects of malaria are often recommended. The objective of this review was to assess the effects of anti-malarial interventions in pregnant women living in malarial areas on the mother and the infant. SEARCH STRATEGY: We searched the Cochrane Infectious Diseases Group trials register, the Cochrane Controlled Trials Register, Medline, Embase. We contacted researchers in the field. SELECTION CRITERIA: Randomised and quasi-randomised trials in pregnant women of interventions that aim to mitigate the effects of malaria in pregnancy, including drugs given routinely and mosquito control measures. DATA COLLECTION AND ANALYSIS: Trial quality was assessed. Data extraction was done by two reviewers using standard criteria. MAIN RESULTS: Fifteen trials were included. Drugs given regularly and routinely were associated with fewer episodes of fever in the mother, fewer women with severe anaemia antenatally, and higher average birthweight in infants. These effects appear to be greater in primigravidae. No difference in perinatal, neonatal and infant mortality were detected in studies of prophylaxis in all parity groups, or studies confined to women of low parity. REVIEWER'S CONCLUSIONS: Drugs locally effective for malaria when given routinely for malaria during pregnancy may reduce the incidence of low birth weight and anaemia. This effect appears to be limited to low parity women. Given the costs and inputs required to effectively deliver widescale prophylaxis programmes, we believe a large simple placebo- controlled trial testing the impact of drugs given routinely on pregnancy outcome and neonatal/infant survival is warranted.

Antimalarials↗

Evaluations, attributions, affect, and disciplinary choices in mothers at high and low risk for child physical abuse.

OBJECTIVE: The present study investigated several components of a social information-processing model of child physical abuse. The main objective was to examine the extent to which high-risk, relative to low-risk, mothers differed in their evaluations, attributions, negative affect, and disciplinary choices for children's behavior, and to explore whether these differences may be expressed in interactions between risk status and mitigating information. METHOD: Nineteen high- and 19 matched low-risk mothers' evaluations of children transgressions, attributions, affect, and choices of disciplinary techniques were examined using six vignettes depicting a child engaging in moral, conventional, and personal transgressions. One-half of the vignettes contained mitigating information and one-half did not. High- and low-risk mothers were chosen based on their potential for physical child abuse. A three-factor (2 x 3 x 2) design was used to assess the dependent variables. RESULTS: As expected, high-risk, relative to low-risk, mothers reported more hostile intent, stable and global attributions, aversiveness, annoyance, and use of power-assertion discipline. A risk group by type of transgression interaction was found for evaluation and indifference and a risk group by mitigating information interaction was found for evaluation of wrongness, internal attributions, and aversiveness. A risk by type of transgression by mitigating information interaction was found for global/specific attributions, aversiveness, and indifference toward child transgressions. CONCLUSIONS: Results support a social information processing model of child physical abuse, which suggests that high-risk, compared to low-risk, mothers process child-related information differently and use more power-assertive disciplinary techniques.

Analysis of Variance↗

Base-line model for identifying the bioaccumulation potential of chemicals.

The base-line modeling concept presented in this work is based on the assumption of a maximum bioconcentration factor (BCF) with mitigating factors that reduce the BCF. The maximum bioconcentration potential was described by the multi-compartment partitioning model for passive diffusion. The significance of different mitigating factors associated either with interactions with an organism or bioavailability were investigated. The most important mitigating factor was found to be metabolism. Accordingly, a simulator for fish liver was used in the model, which has been trained to reproduce fish metabolism based on related mammalian metabolic pathways. Other significant mitigating factors, depending on the chemical structure, e.g. molecular size and ionization were also taken into account in the model. The results (r(2)=0.84) obtained for a training set of 511 chemicals demonstrate the usefulness of the BCF base line concept. The predictability of the model was evaluated on the basis of 176 chemicals not used in the model building. The correctness of predictions (abs(logBSF(Obs)-logBCF(Calc))=0.75)) for 59 chemicals included within the model applicability domain was 80%.

Animals↗

Greenhouse-gas-trading markets.

This paper summarizes the extension of new market mechanisms for environmental services, explains of the importance of generating price information indicative of the cost of mitigating greenhouse gases (GHGs) and presents the rationale and objectives for pilot GHG-trading markets. It also describes the steps being taken to define and launch pilot carbon markets in North America and Europe and reviews the key issues related to incorporating carbon sequestration into an emissions-trading market. There is an emerging consensus to employ market mechanisms to help address the threat of human-induced climate changes. Carbon-trading markets are now in development around the world. A UK market is set to launch in 2002, and the European Commission has called for a 2005 launch of an European Union (EU)-wide market, and a voluntary carbon market is now in formation in North America. These markets represent an initial step in resolving a fundamental problem in defining and implementing appropriate policy actions to address climate change. Policymakers currently suffer from two major information gaps: the economic value of potential damages arising from climate changes are highly uncertain, and there is a lack of reliable information on the cost of mitigating GHGs. These twin gaps significantly reduce the quality of the climate policy debate. The Chicago Climate Exchange, for which the authors serve as lead designers, is intended to provide an organized carbon-trading market involving energy, industry and carbon sequestration in forests and farms. Trading among these diverse sectors will provide price discovery that will help clarify the cost of combating climate change when a wide range of mitigation options is employed. By closing the information gap on mitigation costs, society and policymakers will be far better prepared to identify and implement optimal policies for managing the risks associated with climate change. Establishment of practical experience in providing tradeable credits for carbon-absorbing land-use practices, especially reforestation and conservation management of agricultural soils, will also help demonstrate the viability of a new tool for financing activities that improve water quality, support biodiversity and constitute important elements of long-term sustainability in land-use management.

Air Pollution↗

Can hazard risk be communicated through a virtual experience?

Cyberspace, defined by William Gibson as a consensual hallucination, now refers to all computer-generated interactive environments. Virtual reality, one of a class of interactive cyberspaces, allows us to create and interact directly with objects not available in the everyday world. Despite successes in the entertainment and aviation industries, this technology has been called a 'solution in search of a problem'. The purpose of this commentary is to suggest such a problem: the inability to acquire experience with a hazard to motivate mitigation. Direct experience with a hazard has been demonstrated as a powerful incentive to adopt mitigation measures. While we lack the ability to summon hazard events at will in order to gain access to that experience, a virtual environment can provide an arena where potential victims are exposed to a hazard's effects. Immersion as an active participant within the hazard event through virtual reality may stimulate users to undertake mitigation steps that might otherwise remain undone. This paper details the possible direction in which virtual reality may be applied to hazards mitigation through a discussion of the technology, the role of hazard experience, the creation of a hazard stimulation and the issues constraining implementation.

Computer Simulation↗

Estimating health risks from natural hazards using risk assessment and epidemiology.

Risk assessment is the process of estimating the likelihood that an adverse effect may result from exposure to a specific health hazard. The process traditionally involves hazard identification, dose-response assessment, exposure assessment, and risk characterization to answer "How many excess cases of disease A will occur in a population of size B due to exposure to agent C at dose level D?" For natural hazards, however, we modify the risk assessment paradigm to answer "How many excess cases of outcome Y will occur in a population of size B due to natural hazard event E of severity D?" Using a modified version involving hazard identification, risk factor characterization, exposure characterization, and risk characterization, we demonstrate that epidemiologic modeling and measures of risk can quantify the risks from natural hazard events. We further extend the paradigm to address mitigation, the equivalent of risk management, to answer "What is the risk for outcome Y in the presence of prevention intervention X relative to the risk for Y in the absence of X?" We use the preventable fraction to estimate the efficacy of mitigation, or reduction in adverse health outcomes as a result of a prevention strategy under ideal circumstances, and further estimate the effectiveness of mitigation, or reduction in adverse health outcomes under typical community-based settings. By relating socioeconomic costs of mitigation to measures of risk, we we illustrate that prevention effectiveness is useful for developing cost-effective risk management options.

Disaster Planning↗

Impact responses of the flexed human knee using a deformable impact interface.

Blunt impact trauma to the patellofemoral joint during car accidents, sporting activities, and falls can produce a range of injuries to the knee joint, including gross bone fracture, soft tissue injury, and/or microinjuries to bone and soft tissue. Currently, the only well-established knee injury criterion applies to knee impacts suffered during car accidents. This criterion is based solely on the peak impact load delivered to seated cadavers having a single knee flexion angle. More recent studies, however, suggest that the injury potential, its location, and the characteristics of the damage are also a function of knee flexion angle and the stiffness of the impacting structure. For example, at low flexion angles, fractures of the distal patella are common with a rigid impact interface, while at high flexion angles splitting of the femoral condyles is more evident. Low stiffness impact surfaces have been previously shown to distribute impact loads over the anterior surface of the patella to help mitigate gross and microscopic injuries in the 90 deg flexed knee. The objective of the current study was to determine if a deformable impact interface would just as effectively mitigate gross and microscopic injuries to the knee at various flexion angles. Paired experiments were conducted on contralateral knees of 18 human cadavers at three flexion angles (60, 90, 120 deg). One knee was subjected to a fracture level impact experiment with a rigid impactor, and the opposite knee was impacted with a deformable interface (3.3 MPa crush strength honeycomb material) to the same load. This (deformable) impact interface was effective at mitigating gross bone fractures at approximately 5 kN at all flexion angles, but the frequency of split fracture of the femoral condyles may not have been significantly reduced at 120 deg flexion. On the other hand, this deformable interface was not effective in mitigating microscopic injuries observed for all knee flexion angles. These new data, in concert with the existing literature, suggest the chosen impact interface was not optimal for knee injury protection in that fracture and other minor injuries were still produced. For example, in 18 cadavers a total of 20 gross fractures and 20 subfracture injuries were produced with a rigid interface and 5 gross fractures and 21 subfracture injuries with the deformable interface selected for the current study. Additional studies will be needed to optimize the knee impact interface for protection against gross and microscopic injuries to the knee.

Accidents, Traffic↗

Radon and lung cancer: a cost-effectiveness analysis.

OBJECTIVES: This study examined the cost-effectiveness of general and targeted strategies for residential radon testing and mitigation in the United States. METHODS: A decision-tree model was used to perform a cost-effectiveness analysis of preventing radon-associated deaths from lung cancer. RESULTS: For a radon threshold of 4 pCi/L, the estimated costs to prevent 1 lung cancer death are about $3 million (154 lung cancer deaths prevented), or $480,000 per life-year saved, based on universal radon screening and mitigation, and about $2 million (104 lung cancer deaths prevented), or $330,000 per life-year saved, if testing and mitigation are confined to geographic areas at high risk for radon exposure. For mitigation undertaken after a single screening test and after a second confirmatory test, the estimated costs are about $920,000 and $520,000, respectively, to prevent a lung cancer death with universal screening and $130,000 and $80,000 per life-year for high risk screening. The numbers of preventable lung cancer deaths are 811 and 527 for universal and targeted approaches, respectively. CONCLUSIONS: These data suggest possible alternatives to current recommendations.

Aged↗