Home About us Contact
|
Home About us Contact | ||
|
|
||
Mortality Only (mortality + only)
Selected AbstractsEffects of bisphenol A and tetrabromobisphenol A on sex organ development in quail and chicken embryosENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2001Cecilia Berg Abstract The plastic monomere bisphenol A (BPA) and the flame retardant tetrabromobisphenol A (TBBPA) were examined for estrogen-like developmental effects on the reproductive organs in avian embryos. The synthetic estrogen diethylstilbestrol (DES) was used as a positive control. The test compounds were injected into the yolk of quail and chicken eggs early during incubation and the embryos were examined 2 d before anticipated hatching. At 200 ,g/g egg, BPA induced Müllerian duct (embryonic oviduct) malformation in female quail embryos and feminization of the left testis (ovotestis) in male chicken embryos. The estrogenic potency of BPA compared with DES was species and endpoint specific. Müllerian duct malformation was the most sensitive endpoint in quail embryos, whereas ovotestis formation was the most sensitive response in chicken embryos. Tetrabromobisphenol A caused high embryo mortality at 45 ,g/g egg in both species, but no estrogen-like effects were observed. Bisphenol A caused mortality only in chicken embryos at 67 and 200 ,g/g egg. To our knowledge, this is the first report on estrogen-like or embryolethal effects of BPA and TBBPA in birds. [source] Habitat-specific demography and source,sink dynamics in a population of Siberian jaysJOURNAL OF ANIMAL ECOLOGY, Issue 1 2010Magdalena Nystrand Summary 1.,There are a number of models describing population structure, many of which have the capacity to incorporate spatial habitat effects. One such model is the source,sink model, that describes a system where some habitats have a natality that is higher than mortality (source) and others have a mortality that exceeds natality (sink). A source can be maintained in the absence of migration, whereas a sink will go extinct. 2.,However, the interaction between population dynamics and habitat quality is complex, and concerns have been raised about the validity of published empirical studies addressing source,sink dynamics. In particular, some of these studies fail to provide data on survival, a significant component in disentangling a sink from a low quality source. Moreover, failing to account for a density-dependent increase in mortality, or decrease in fecundity, can result in a territory being falsely assigned as a sink, when in fact, this density-dependent suppression only decreases the population size to a lower level, hence indicating a ,pseudo-sink'. 3.,In this study, we investigate a long-term data set for key components of territory-specific demography (mortality and reproduction) and their relationship to habitat characteristics in the territorial, group-living Siberian jay (Perisoreus infaustus). We also assess territory-specific population growth rates (r), to test whether spatial population dynamics are consistent with the ideas of source,sink dynamics. 4.,Although average mortality did not differ between sexes, habitat-specific mortality did. Female mortality was higher in older forests, a pattern not observed in males. Male mortality only increased with an increasing amount of open areas. Moreover, reproductive success was higher further away from human settlement, indicating a strong effect of human-associated nest predators. 5.,Averaged over all years, 76% of the territories were sources. These territories generally consisted of less open areas, and were located further away from human settlement. 6.,The source,sink model provides a tool for modelling demography in distinct habitat patches of different quality, which can aid in identifying key habitats within the landscape, and thus, reduce the risk of implementing unsound management decisions. [source] Synergistic, antagonistic and additive effects of multiple stressors: predation threat, parasitism and pesticide exposure in Daphnia magnaJOURNAL OF APPLIED ECOLOGY, Issue 6 2008Anja Coors Summary 1Predation and parasitism are important factors in the ecology and evolution of natural populations and may, along with other environmental factors, interact with the impact of anthropogenic pollutants. 2Our study aimed at identifying potential interactions between three stressors (predation threat, parasitism and pesticide exposure) and at exploring the predictability of their joint effects by using the model of independent action. We assessed in a full-factorial design the impacts of these stressors on key life-history traits and population growth rate of the water flea Daphnia magna. 3When applied as single stressors, predation threat and parasite challenge induced varying stressor-specific adaptive responses. The pesticide carbaryl was applied at a generally sublethal concentration, which caused low mortality only in first-brood offspring. 4Pesticide exposure interacted synergistically with parasite challenge regarding survival, which suggests immunomodulatory activity of the pesticide. Predation threat by phantom midge larvae showed antagonistic interactions for amount of first-brood offspring with both parasite challenge and carbaryl exposure. All stressors additively affected age and size at maturity, which added up to a considerable delay in the onset of reproduction in the three-stressor combination. The intrinsic rate of natural increase, r, reflected the non-additive and additive effects on single endpoints and showed significant synergistic interactions for all two-stressor combinations. The combination of all stressors resulted in a dramatic reduction of r compared to the stressor-free control. 5The model of independent action proved useful in quantitatively predicting effects of additively acting stressors, and in visualizing the occurrence and magnitude of non-additive effects in accordance with results of analysis of variances. 6Synthesis and applications. Cumulative additive effects and non-additive interactions of natural antagonists and pollutants are shown to result in considerable impacts on ecologically relevant parameters. As a starting point for an environmentally more realistic risk assessment of chemicals, it may be a valuable strategy to screen for non-additive effects among many stress factors simultaneously in simplified experimental designs by using the model of independent action. [source] Original Article: A prospective study of uric acid by glucose tolerance status and survival: the Rancho Bernardo StudyJOURNAL OF INTERNAL MEDICINE, Issue 6 2010C. K. Kramer Abstract., Kramer CK, von Mühlen D, Jassal SK, Barrett-Connor E (University of California, La Jolla, CA; and Hospital de Clinicas de Porto Alegre, RS, Brazil). A prospective study of uric acid by glucose tolerance status and survival: the Rancho Bernardo Study. J Intern Med 2010. Objectives., Little is known about uric acid (UA) levels and mortality in the context of glycaemia. We examined whether serum UA levels predict all-cause and cardiovascular disease (CVD) mortality differentially in older adults by glucose tolerance status. Design and methods., Between 1984 and 1987, 2342 community-dwelling men and women had an oral glucose tolerance test, UA measurement, and assessment of traditional CVD risk factors. We defined glucose tolerance status as normoglycaemia (NG), pre-diabetes (pre-DM), and type 2 diabetes mellitus (T2DM). Ninety per cent were followed for vital status up to 23 years. Death certificates were coded using the Ninth International Classification of Diseases. Results., Baseline age was 69.5 years; 44.4% were men. At baseline 939 had NG, 957 pre-DM, and 446 T2DM. The mean UA by glucose tolerance status was 327.1, 362.8, and 374.7 ,mol L,1. During follow-up, there were 1318 deaths 46.8% attributed to CVD. In Cox-regression analysis, each 119 ,mol L,1 (2 mg dL,1) increment in UA levels predicted an increased hazard ratio (HR) for all-cause deaths independent of age, smoking, body mass index, alcohol, physical activity, diuretic use and estimated glomerular filtration rate in all groups (NG: HR 1.25 95% CI 1.06,1.47, P =0.005; pre-DM: HR 1.20 95% CI 1.06,1.37, P = 0.04; T2DM: HR 1.20 95% CI 1.01,1.47, P = 0.04). After adjusting for CVD risk factors, the UA association with CVD mortality was significant only in the pre-DM and T2DM groups. Conclusion., All-cause mortality was independently associated with UA in all groups, but UA predicted CVD mortality only in those with abnormal glucose tolerance. [source] A NEW LARVAL FISH BIOASSAY FOR TESTING THE PATHOGENICITY OF PFIESTERIA SPP. (DINOPHYCEAE),JOURNAL OF PHYCOLOGY, Issue 3 2003Vincent J. Lovko Water quality, microbial contamination, prior fish health, and variable results have been major impediments to identifying the cause and mechanism of fish mortality in standard aquarium-format Pfiesteria bioassays. Therefore, we developed a sensitive 96-h larval fish bioassay for assessing Pfiesteria spp. pathogenicity using six-well tissue culture plates and 7-day-old larval cyprinodontid fish. We used the assay to test pathogenicity of several clonal lines of Pfiesteria piscicida Steidinger and Burkholder and P. shumwayae Glasgow and Burkholder that had been cultured with algal prey for 2 to 36 months. The P. shumwayae cultures exhibited 80%,100% cumulative mortality in less than 96 h at initial zoospore densities of approximately 1000 cells·mL,1. No fish mortalities occurred with P. piscicida at identical densities or in controls. In a dose-response assay, we demonstrated a strong positive correlation between dinospore density and fish mortality in a highly pathogenic culture of P. shumwayae, generating a 96-h LD50 of 108 zoospores·mL,1. Additionally, we applied the assay to evaluate a 38-L P. shumwayae bioassay that was actively killing fish and compared results with those from exposures of juvenile tilapia (Oreochromis niloticus) in a 500-mL assay system. Water from the fish-killing 38-L assay was filtered and centrifuged to produce fractions dominated by dinoflagellates, bacteria, or presumed ichthyotoxin (cell-free fraction). After 96 h, the larval fish assay exhibited 50%,100% cumulative mortality only in fractions containing dinoflagellates, with no mortalities occurring in the other fractions. The 500-mL bioassay with tilapia produced inconsistent results and demonstrated no clear correlation between mortality and treatment. The new larval fish bioassay was demonstrated as a highly effective method to verify and evaluate dinoflagellate pathogenicity. [source] Determinants of Mortality in Patients Undergoing Cardiac Resynchronization Therapy: Baseline Clinical, Echocardiographic, and Angioscintigraphic Evaluation Prior to ResynchronizationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 12 2005ANTONIO DE SISTI Background: In dilated cardiomyopathy (DCM) patients (pts) with cardiac resynchronization therapy (CRT) for ventricular dyssynchrony, long-term predictors of mortality and morbidity remain poorly investigated. Method and Results: We reviewed data of 102 pts, 68 ± 10 years, NYHA Class II,IV (14 Class II, 67 Class III, 21 Class IV), who benefited from CRT (69 CRT, 33 CRT-ICD). Fifty-two patients had an ischemic DCM, 36 a previously implanted conventional PM/ICD, 29 a permanent atrial fibrillation, and 19 needed dobutamine in the month preceding implant. QRS duration was 187 ± 35 ms, left ventricular end-diastolic diameter 72 ± 10 mm, mitral regurgitation severity 1.9 ± 0.8, echographic aorto-pulmonary electromechanical delay 61.5 ± 25 ms and septo-lateral left intraventricular delay 86 ± 56 ms, pulmonary artery pressure (PAP) 43 ± 11 mmHg, angioscintigraphic left ventricular ejection fraction (EF) 20 ± 9%, and right ventricular EF 30.5 ± 14%. Over a mean follow-up of 23 ± 20 months, 26 pts died (18 heart failures (HFs), 1 arrhythmic storm, 7 noncardiac deaths). Positive univariate predictors of death from any cause were NYHA Class IV (P < 0.001), and need for dobutamine the month preceding CRT (P < 0.008), while use of ,-blocking agents (P < 0.08) and left ventricular EF (P < 0.09) were negative ones. NYHA Class IV was the only independent predictor at multivariate analysis (P < 0.01). Survival at 24 months was 85% in Class II, 80% in Class III, and 37% in Class IV (II vs III, P = ns; III vs IV, P < 0.001). When using a composite endpoint of death from any cause and unplanned rehospitalization for a major cardiovascular event, there were 48 events (14 HF deaths, 3 noncardiac deaths, 26 HF rehospitalizations, 2 paroxysmal atrial fibrillation, 2 sustained ventricular tachycardia, 1 nonfatal pulmonary embolism). Predictors of death from any cause/unplanned rehospitalization for a major cardiovascular event in the follow-up were NYHA Class IV (P < 0.001), need for dobutamine during the month preceding CRT (P < 0.002), and PAP (<0.02). NYHA Class IV was the only independent predictor at multivariate analysis (P < 0.05). Event-free proportion at 24 months was 70% in Class II, 64% in Class III, and 37% in Class IV (II vs III, P = ns; III vs IV, P < 0.01). When considering determinants of mortality only in NYHA Class IV patients, no variable was significantly correlated to mortality. Need for dobutamine during the last month preceding CRT did not add an adjunctive mortality risk. Conclusion: Baseline NYHA Class IV at implantation appears as the most important determinant of a poor clinical outcome in terms of both mortality and morbidity. No predictive criteria seem available for NYHA Class IV patients, in order to discriminate who will die after CRT and who will not. NYHA Class IV strongly influences the clinical outcome, suggesting that, in future studies planned on mortality and rehospitalization as major endpoints, baseline NYHA Class IV should be separately taken into account. [source] Insecticidal activity of 23 essential oils and their major compounds against adult Lipaphis pseudobrassicae (Davis) (Aphididae: Homoptera)PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2005Blair J Sampson Abstract Essential oils from 23 species of plants comprising 14 genera and 4 plant families were obtained by Clevenger-type water distillation. The major compounds in these essential oils were identified with GC-MS and their insecticidal activity against adult turnip aphids, Lipaphis pseudobrassicae (Davis), tested with dosage-mortality bioassays. We examined mortality only for viviparous adults because sizeable aphid populations on crucifer (Brassicaceae) hosts are largely produced by these wingless, parthenogenic females. Twenty-two of the oils were directly applied to aphid females in randomized blocks at concentrations of 0.0, 1.0, 2.5, 5.0 and 10.0 mg ml,1. Essential oils mixed with a non-toxic emulsifying agent, dimethyl sulfoxide (DMSO), more easily penetrated the waxy insect cuticle. Probit analysis and LC50 at three different exposures showed aphids were quickly incapacitated and killed by aliphatic aldehydes, phenols and monocyclic terpenes contained in Bifora and Satureja oils and at applied concentrations as low as 0.3 to 1.0 mg ml,1. Only enough Pimpinella isaurica oil and its three phenylpropanoid fractions were available for testing at a single concentration of 10 mg ml,1. We could not spare any additional P. isaurica oil for testing at other concentrations. Phenylpropanoids isolated from P. isaurica oil when recombined or left naturally blended in the oil were highly bioactive against L. pseudobrassicae at 10 mg ml,1. Copyright © 2005 Society of Chemical Industry [source] | |||||||||||||