Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
1,925
result(s) for
"Chapman, P. M"
Sort by:
Ecotoxicology of metals in aquatic sediments: binding and release, bioavailability, risk assessment, and remediation
Major metal-binding phases in the aerobic layer of sediments are iron and manganese oxyhydroxides (FeOOH and MnOOH) and particulate organic carbon (POC). The acid-volatile sulfide (AVS) model proposed for predicting nontoxicity from metals-contaminated sediments is only applicable to anaerobic sediments. In other sediments, normalization by POC or FeOOH and MnOOH may be predictive, but binding constants are not well understood. Metal mobilization is enhanced by ligand complexation and oxidation of anaerobic sediments. Free metal ion is the most bioavailable species, but other labile metal species and nonchemical variables also determine metal bioavailability; biotic site binding models have shown promise predicting toxicity for systems of differing chemistry. Hazard identification and ecological risk assessment (ERA) depend on determining bioavailability, from water (overlying, interstitial) and food, which can be done prospectively (e.g., normalized sediment chemistry, laboratory bioassays) or retrospectively (e.g., in situ bioassays, field studies). ERA of sediment-bound metals requires primary emphasis on toxicity and consideration of the three separate transformation processes for metals in the aquatic environment, the differences between essential and nonessential metals, the complex interactions that control bioavailability, adaptation, which may occur relatively simply without appreciable cost to the organism, weight of evidence, and causality.
Journal Article
The implications of hormesis to ecotoxicology and ecological risk assessment
Changes required for the explicit recognition of hormesis are outlined for both ecotoxicology and ecological risk assessment (ERA). A major research need is the extension of hormesis beyond chemical stressors to abiotic (e.g., habitat) and biotic stressors (e.g., species introductions, organism interactions). An overreaching research need is to determine for all stressors with model organisms, populations, and communities whether hormesis has positive, neutral, or adverse effects. The latter are the least likely; however, neutral effects cannot be ruled out. Based on our present state of knowledge, hormesis is likely to have more of an impact on ecotoxicology than on ERA. In the case of the latter, it is most likely to make a difference only in a detailed-level ecological risk assessment (DLERA), the most complex form of ERA. Further, for hormesis to be accepted fully into ecotoxicology or ERA will require a paradigm shift. Three ongoing paradigm shifts to which hormesis could be linked are: recognition of the low utility of no-observed-effects concentrations (NOECs); recognition of the need for special treatment of essential element dose–concentration responses, which are similar to hormesis; and the replacement of environmental toxicology with ecological toxicology (ecotoxicology).
Journal Article
Viscoelastic hemostatic fibrinogen assays detect fibrinolysis early
Purpose
Viscoelastic hemostatic assays are emerging as the standard-of-care in the early detection of post-injury coagulopathy. TEG and ROTEM are most commonly used. Although similar in technique, each uses different reagents, which may affect their sensitivity to detect fibrinolysis. Therefore, the purpose of this study is to determine the ability of each device to detect fibrinolysis.
Methods
TEG (Rapid, Kaolin, Functional Fibrinogen) and ROTEM (EXTEM, INTEM, FIBTEM) were run simultaneously on normal blood as well as blood containing tPA from healthy volunteers (
n
= 10). A two-tailed, paired
t
-test and ANOVA were used to determine the significance between parameters obtained from normal blood and blood with tPA, and individual TEG and ROTEM assays, respectively.
Results
TEG detected significant changes in clot strength and 30-min lysis after the addition of tPA (
p
< 0.0001). All ROTEM assays detected changes in the 30-min lysis (
p
< 0.0001), but only INTEM detected changes in clot strength (
p
< 0.05). Kaolin and Rapid TEG assays detected greater changes in clot strength and lysis, but INTEM and EXTEM had decreased lysis onset times compared to TEG (
p
< 0.001). Functional Fibrinogen and FIBTEM assays detected lysis sooner than other TEG/ROTEM assays, and were comparable.
Conclusions
TEG assays detect greater changes in clot strength compared to ROTEM. Despite this, Functional Fibrinogen and FIBTEM assays detect fibrinolysis sooner than their corresponding intrinsic and extrinsic assays. Therefore, fibrinogen assays should be employed in actively bleeding trauma patients in order to provide timely antifibrinolytic therapy.
Journal Article
Defining hormesis: comments on Calabrese and Baldwin (2002)
The definition of hormesis should not include non scientific judgments as to beneficial or harmful effects. Evaluating the significance of hormesis is a separate issue that ultimately requires risk:risk comparisons, particularly since the evolutionary basis for hormesis appears to be Lamarkian rather than Darwinian. It is arguable whether ‘hormesis’ is the correct umbrella term for all low-dose exposure responses, in particular those at higher organization levels than single species, or whether it includes arousal responses.
Journal Article
Utility and relevance of aquatic oligochaetes in Ecological Risk Assessment
Ecological risk assessment (EcoRA) provides both a process and a framework to evaluate the potential for adverse ecological effects occurring as a result of exposure to contaminants or other stressors. EcoRA begins with problem formulation/hazard identification, progresses to effects and exposure assessment, and culminates with risk characterization (an estimate of the incidence and severity of any adverse effects likely to occur). Key components of EcoRA include determining: stressors/contaminants of concern; sensitive, exposed biota; and, appropriate tests and organisms for evaluating effects. Aquatic oligochaetes are not generally used directly in EcoRA because of three major perceptions. First, EcoRA personnel are generally not familiar with or comfortable using this group of organisms. Second, there is believed to be a paucity of widely accepted toxicity tests with these organisms. Third, their taxonomy is considered difficult and uncertain. In fact, aquatic oligochaetes potentially have great utility and relevance to EcoRAs because of factors including: their importance in the aquatic food chain (e.g. prey to fauna including fish and waterfowl; as a vector for contaminant movement through the food chain from bacteria); many species are widely distributed and well studied; representatives include fresh, estuarine and marine species; as a group, they range from sensitive to insensitive over a wide range of environmental insults; they have a long history of use in pollution monitoring and assessment; and, relevant toxicity and biaccumulation tests exist. Toxicity testing under defined conditions is appropriate for problem formulation while more realistic testing for effects assessment (e.g. microcosms) is logistically easier with this group of organisms than with others due to their relatively small size. The importance of aquatic oligochaetes for EcoRA, in particular of sediments, is particularly compelling.[PUBLICATION ABSTRACT]
Journal Article
Total Suspended Solids Effects on Freshwater Lake Biota Other than Fish
Protective benchmarks for the effects of total suspended solids (TSS) on freshwater aquatic biota primarily focus on fish; whether these benchmarks will also protect their prey or co-existing lower trophic level aquatic biota was uncertain. We conducted an extensive literature review of TSS effects on those organisms comprising the food webs upon which fish living in lakes depend: phytoplankton, zooplankton, periphyton, and benthic invertebrates. The available literature indicates that TSS benchmarks that protect sensitive life stages of lake fish will also protect their supporting food webs; in other words, the function of lake aquatic communities will be protected and maintained.
Journal Article
Environmental quality benchmarks—the good, the bad, and the ugly
Environmental quality benchmarks (EQBs) such as water or sediment quality guidelines comprise one line of evidence for assessing the potential harm from chemicals and other stressors (physical, biological). They are useful but not perfect tools, should not always be used, and should never be used alone for final decision-making. The “good” can be designed to be situation-specific and can provide understandable scientific input to decision-makers. The “bad” includes perception that they are absolutes (i.e., definitive binary decision points), no or limited adaptability based on good science or common sense, and protection of individual organisms not populations of organisms. The “ugly” includes benchmarks based on simplistic indices (information loss, misleading results), misuse of biomarkers, and misapplication of EQBs. Other factors to be considered include the following: appropriately deriving EQBs, uncertainty, the laboratory is not the field, contaminant uptake and cause-effect, and specifics regarding sediment quality benchmarks (i.e., their specific “good,” “bad,” and “ugly” components). EQBs are not always needed or useful.
Journal Article