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排序方式: 共有51条查询结果,搜索用时 15 毫秒
1.
Ben F. Brammell J. Scott McClain James T. Oris David J. Price Wesley J. Birge Adria A. Elskus 《Archives of environmental contamination and toxicology》2010,58(3):772-782
It has become increasingly apparent that resident fish can develop resistance to chemicals in their environment, thus compromising
their usefulness as sentinels of site-specific pollution. By using a stream system whose resident fish appear to have developed
pollutant resistance (Brammell et al., Mar Environ Res 58:251–255, 2005), we tested the hypothesis that the pollutant-inducible biomarker, cytochrome P4501A (CYP1A), as measured in field-caged
juvenile rainbow trout (Oncorhynchus mykiss), would reflect relative pollution differences between reference and polychlorinated biphenyl (PCB)-contaminated sites. Trout
were caged in the Town Branch/Mud River system (Logan County, KY), a stream system undergoing remediation for PCBs. Fish were
held in remediated (Town Branch), unremeditated (Mud River), and reference sites for 2 weeks during spring 2002. At the end
of this period, gill and hepatic CYP1A expression were measured. To evaluate the relative PCB exposure of caged trout and
provide a reference point against which to calibrate CYP1A response, PCB levels were quantified in sediments from each site.
Hepatic CYP1A expression in caged trout clearly detected the presence of PCBs in the Town Branch/Mud River stream system.
Sediment PCB levels and hepatic CYP1A expression in caged trout produced identical pollution rankings for the study sites.
Gill CYP1A expression, although suggestive of site differences, was not statistically different among sites. Unlike resident
fish, which failed to show site differences in hepatic CYP1A expression in this waterway (Brammell et al. 2005), caged fish proved to be a sensitive discriminator of relative PCB contamination in this system. In summary, we determined
that CYP1A expression in caged fish reflected relative in situ pollutant exposure. The exposure paradigm confirmed that 2 weeks
was a sufficient caging period for evaluating CYP1A response in this species at these temperatures (13–19°C). In addition,
these studies demonstrate that tissue-specific CYP1A expression can provide insights into likely routes of exposure. We conclude
that CYP1A expression in caged trout is a reliable and inexpensive first-pass determination of relative environmental pollutant
exposure and bioavailability in aqueous systems. 相似文献
2.
Jean-Baptiste Bouillon-Minois Marion Trousselard David Thivel Brett Ashley Gordon Jeannot Schmidt Fars Moustafa Charlotte Oris Frdric Dutheil 《Nutrients》2021,13(3)
Introduction: Ghrelin is an orexigenic hormone which favors food-seeking behavior and has been postulated to be a biomarker of stress. We conducted a systematic review and meta-analysis on the evolution of ghrelin levels following acute stress. Methods: The PubMed, Cochrane Library, Embase, and ScienceDirect databases were searched for studies reporting ghrelin levels before and after acute stress in humans. Results: We included ten studies for a total of 348 patients. Acute stress (intervention) was always in a laboratory. Acute stress was psychological (Trier Social Stress Test), physical, or mixed (cold pressure test). The overall meta-analysis demonstrated an increase in ghrelin after the stress intervention (ES = 0.21, 95CI 0.09 to 0.34) compared with baseline levels. Stratification by time demonstrated an acute increase in ghrelin levels in the five minutes immediately following the initiation of stress (0.29, 0.10 to 0.48) but without any difference after. Obese individuals had a more significant (ES = 0.51, 95CI 0.18 to 0.84) and prolonged increase in ghrelin levels for up to 45 min compared with non-obese individuals who had a significant increase only five minutes after stress. Moreover, the ghrelin levels increased in response to stress with BMI (coefficient 0.028, 0.01 to 0.49; p = 0.013) and decreased with the time after the stress intervention (coefficient -0.007, −0.014 to −0.001; p = 0.025). Conclusion: Ghrelin is a biomarker of stress, with a short-term increase following acute stress. Obese individuals have both a higher and prolonged response, emphasizing the link between obesity and stress. 相似文献
3.
Activities of an intravenous formulation of itraconazole in experimental disseminated Aspergillus, Candida, and Cryptococcus infections 总被引:4,自引:0,他引:4
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Odds FC Oris M Van Dorsselaer P Van Gerven F 《Antimicrobial agents and chemotherapy》2000,44(11):3180-3183
An intravenous (i.v.) formulation of itraconazole was evaluated in disseminated fungal infection models in guinea pigs. In acute disseminated Candida albicans and Aspergillus fumigatus infections, treatment at 5 mg/kg of body weight twice a day (b.i.d.) significantly prolonged survival. In these models and in animals with chronic disseminated cryptococcosis, itraconazole given i.v. at 2.5 and 5 mg/kg b.i.d. greatly reduced the proportions of organs with culture-detectable fungal burdens. The efficacy of i.v. itraconazole in these animal models justifies its further investigation for the treatment of life-threatening mycoses in humans. 相似文献
4.
Effectively and accurately assessing the toxicity of chemicals and their impact on the environment continues to be an important concern in ecotoxicology. Single experiments conducted by a particular laboratory commonly serve as the basis of toxicity risk assessment. These laboratories often have a long history of conducting experiments using particular protocols. In the present study, a Bayesian analysis for estimating potency based on a single experiment was formulated, which then served as the basis for incorporating the experimental information from historical controls. A Bayesian hierarchical model was developed to estimate the relative inhibition concentrations (RIp) of a toxicant and flexible ways of using historical control information were suggested. The methods were illustrated using a data set produced by the test for reproduction in Ceriodaphnia dubia in which the number of young produced over three broods was recorded. In addition, simulation studies were included to compare the Bayesian methods with previously proposed estimators of potency. The Bayesian methods gave more precise RIp estimates with smaller variation and nominal coverage probability offsetting a small negative bias in the point estimate. Incorporating historical control information in the Bayesian hierarchical model effectively uses the useful information from past similar experiments when estimating the RIp, and results in potency estimates that are more precise compared to frequentist methods. 相似文献
5.
Sitthiseripratip K Van Oosterwyck H Vander Sloten J Mahaisavariya B Bohez EL Suwanprateeb J Van Audekercke R Oris P 《Medical engineering & physics》2003,25(2):99-106
A three-dimensional finite element study of trochanteric fracture fixation by a trochanteric gamma nail (TGN) was investigated in this study. The analyses were performed under one-legged stance load boundary conditions to study the stress distribution and displacements. The influence of material properties (E-modulus) of the implant, the bone and contact condition in the fracture zone was determined. The results show that the stresses in the implant were lower in case of titanium alloy implant material but at the same time higher displacements occurred. The results also indicate that the stresses in the TGN gradually reduced throughout the healing process of the bone in the fracture zone. 相似文献
6.
Naesens R Magerman K Gyssens I Leenders A Meekelenkamp J Van Esbroeck M CoppensG Oris E Craeghs J Thoelen I Gabri?ls P Vandevelde M Forier AM Waumans L Cartuyvels R 《European journal of clinical microbiology & infectious diseases》2012,31(8):2053-2055
Data from three different data sources were compiled to estimate the presence of Coxiella burnetii in the Belgian Limburg province for both humans and livestock. First, serological data of all samples sent to the Belgian reference centre (2003–2010) for human Q fever were analysed, showing evidence for an acute Q fever infection in 1–5% of the cases. Second, a multi-centre prospective survey was conducted in Limburg in 2010 to detect undiagnosed human cases; evidence for a recent infection with Coxiella burnetii was found in three out of 100 patients from which clinicians suspected a Mycoplasma pneumoniae infection. Third, we analyzed data from the Belgian livestock screening program (2009–2010) which consisted of investigating all reported abortions, sampling tank milk, and serological screening of cattle. The results suggest an endemicity in the Limburgian livestock which seems to be especially high in cattle. 相似文献
7.
Bowling AM Hammerschmidt CR Oris JT 《Aquatic toxicology (Amsterdam, Netherlands)》2011,102(3-4):134-141
Omnivory has an important role in the movement of energy, nutrients, and contaminants between benthic and pelagic food webs. While top-predator fish are known to supplement a mostly piscivorous diet with benthic organisms, a more obscure benthic-pelagic coupling occurs when benthic invertebrates forage on fish carcasses, referred to as necrophagy. The combination of these two benthic-pelagic links, top-predator fish feeding on benthic organisms that have fed on dead fish, can generate a trophic feedback cycle that conserves energy and nutrients and may have implications for biomagnification of methylmercury (MeHg) in fish. We investigated the role of necrophagy by crayfish (Procambarus clarkii), via a trophic feedback cycle, on the biomagnification of MeHg in largemouth bass (Micropterus salmoides), a cosmopolitan top predator fish known to feed on crayfish. Controlled laboratory tests quantified the uptake of MeHg by both organisms from artificial and natural food (whole crayfish or bass tissue). Assimilation efficiency (AE) of MeHg was greater for bass fed crayfish (79±0.5%) than those fed artificial food (60±3%). Furthermore, AE of MeHg was greatest for largemouth bass fed crayfish that fed on MeHg-dosed dead fish (i.e., trophic feedback cycle; 94±17%). A model, parameterized with results of the laboratory experiments, was used to make steady-state projections of MeHg biomagnification factors. Model projections also indicate that MeHg biomagnification would be greatest for largemouth bass from a trophic feedback cycle. These results suggest that food web ecology has an important role in determining MeHg levels in predatory fish and underscore the need for further investigation into the magnitude that necrophagy may affect MeHg biomagnification in aquatic systems. 相似文献
8.
Differential survivorship among allozyme genotypes of Hyalella azteca exposed to cadmium, zinc or low pH. 总被引:6,自引:0,他引:6
Y Duan S I Guttman J T Oris A J Bailer 《Aquatic toxicology (Amsterdam, Netherlands)》2001,54(1-2):15-28
The survival functions (SF) during acute exposures to cadmium, zinc or low pH were examined for amphipods exhibiting variation at three loci. Significant differences were observed in eight of nine locus/toxicant combinations. Two general types of survival curve patterns were identified when genotype-related SF differences were observed. In the first pattern, the survival differences between genotypes were immediately apparent with two SF curves separated at the beginning of exposure with little or no overlap. For the second pattern, both genotypes had similar SF for a period of time, during which the two survival curves crossed or overlapped. After this period, the survival probability of one genotype dropped sharply relative to the other. While SF was related to genotype, it was not related to heterozygosity. Genetic distance analysis showed that exposure to cadmium, zinc or low pH each resulted in directional selection, suggesting the potential use of genetic distance as a bioindicator. 相似文献
9.
The increased production of nanotechnology materials is a potential source of nano-sized particles (NSPs) in aquatic ecosystems. Meanwhile, polycyclic aromatic hydrocarbons (PAHs), in the presence of ecologically relevant levels of ultraviolet radiation (UV), can be acutely toxic to aquatic species including fish and invertebrates. Considering that suspended carbon-based NSPs (e.g., C60 fullerenes) may act in similar ways as dissolved organic matter (DOM) by altering the bioavailability of PAHs, the objective of this research was to determine the effect of suspended C60 on the photo-induced toxicity of fluoranthene. Transmission electron microscopy indicated that the presence of C60 protected cellular components (e.g., mitochondria, microvilli, and basal infoldings) in organisms exposed to UV and fluoranthene phototoxicity in short-term exposures. However, we found that long-term exposure (21 d) of low-level C60 caused significant cellular damage in the Daphnia magna alimentary canal. This paper highlights the importance of examining the interactions between existing stressors and nanoparticles in the aquatic environment. 相似文献
10.
Phylogenetic relationships among domesticated and wild species of
Cucurbita (Cucurbitaceae) inferred from a mitochondrial
gene: Implications for crop plant evolution and areas of origin
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Oris I. Sanjur Dolores R. Piperno Thomas C. Andres Linda Wessel-Beaver 《Proceedings of the National Academy of Sciences of the United States of America》2002,99(1):535-540
We have investigated the phylogenetic relationships among six wild and six domesticated taxa of Cucurbita using as a marker an intron region from the mitochondrial nad1 gene. Our study represents one of the first successful uses of a mtDNA gene in resolving inter- and intraspecific taxonomic relationships in Angiosperms and yields several important insights into the origins of domesticated Cucurbita. First, our data suggest at least six independent domestication events from distinct wild ancestors. Second, Cucurbita argyrosperma likely was domesticated from a wild Mexican gourd, Cucurbita sororia, probably in the same region of southwest Mexico that gave rise to maize. Third, the wild ancestor of Cucurbita moschata is still unknown, but mtDNA data combined with other sources of information suggest that it will probably be found in lowland northern South America. Fourth, Cucurbita andreana is supported as the wild progenitor of Cucurbita maxima, but humid lowland regions of Bolivia in addition to warmer temperate zones in South America from where C. andreana was originally described should possibly be considered as an area of origin for C. maxima. Fifth, our data support other molecular results that indicate two separate domestications in the Cucurbita pepo complex. The potential zone of domestication for one of the domesticated subspecies, C. pepo subsp. ovifera, includes eastern North America and should be extended to northeastern Mexico. The wild ancestor of the other domesticated subspecies, C. pepo subsp. pepo, is undiscovered but is closely related to C. pepo subsp. fraterna and possibly will be found in southern Mexico. 相似文献