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31.
Thomas-B. Seiler Andrew Rastall Erik Leist Lothar Erdinger Thomas Braunbeck Henner Hollert 《Journal of Soils and Sediments》2006,6(1):20-29
Goal, Scope and Background Organic solvents are routinely used to extract toxicants from polluted soils and sediments prior to chemical analysis or
bioassay. Conventional extraction methods often require the use of heated organic solvents, in some cases under high pressure.
These conditions can result in loss of volatile compounds from the sample and the degradation of thermally labile target
analytes. Moreover, extracts of soils and sediments also frequently contain substantial quantities of organic macromolecules
which can act as sorbing phases for target analytes and in doing so interfere with both chemical analysis and bioassays.
Membrane dialysis extraction (MDE) is described as a simple, passive extraction method for selectively extracting toxicologically
relevant hydrophobic organic compounds (HOCs) from polluted soils and sediments and anaylzed for its applicability in ecotoxicological
investigations.
Methods Toxicologically relevant hydrophobic organic compounds were extracted from wet and dry sediments by sealing replicate samples
in individual lengths of pre-cleaned low-density polyethylene (LD-PE) tubing and then dialysing in n-hexane. The efficacy
of the MDE method for use in ecotoxicological investigations was assessed by testing the concentrated extracts in the neutral
red assay for acute cytotoxicity, in the EROD assay for the presence of dioxin-like compounds and in the Danio rerio fish
egg assay for embryotoxic and teratogenic effects. Conditions of the sediment sample (with or without water content), dialysis
membrane length and duration of dialysis were analyzed with respect to their impact on three endpoints. Results of the MDE
investigations were compared to data obtained in samples prepared using conventional Soxhlet extraction.
Results and Discussion The membrane dialysis extraction was found to be at least as efficient as Soxhlet methodology to extract toxicologically
relevant HOCs from sediment samples. In most cases, MDE-derived extracts showed a higher toxicological potential than the
Soxhlet extracts. Lack of any significant effects in any MDE controls indicated these differences were not caused by contamination
of the LD-PE membrane used. The elevated toxicological potential of MDE extracts is most likely the result of enhanced bioavailability
of toxic compounds in consequence of lower amounts of organic macromolecules (i.e. sorbing phases) in the MDE extracts.
This effect is probably the result of a size-selective restriction by the LD-PE membrane.
Conclusion Membrane dialysis extraction was found to be a simple, efficient and cost-effective method for the extraction of sediment
samples. MDE can be used to extract toxicologically relevant hydrophobic organic compounds from both wet and dry sediments
without the risk of loosing volatile and thermally labile target analytes. The size-selectivity of the LD-PE membrane also
appears to have the capacity to increase the bioavailablity of potential target analytes in the resulting extracts by retaining
much of the organic macromolecules present in the sample. Thus, results suggest that MDE may be particularly useful for
the extraction of toxicologically relevant hydrophobic organic compounds from soils and sediments for bioassays and other
ecotoxicological investigations.
Recommendation and Perspective Further validation of MDE has been initiated and the applicability of the methodology to other sample types will be investigated.
Of particular interest is the potential application of MDE to recover hydrophobic target analytes from biological samples
such as muscle, other soft tissues and blood. 相似文献
32.
33.
Sarr Mame S. Seiler John R. Sullivan Jay Diallo Adja M. Strahm Brian D. 《New Forests》2021,52(6):943-957
New Forests - With continued global change as a result of land use changes, invasive species and changing climatic patterns, it is becoming increasingly important to understand the adaptability of... 相似文献
34.
The soil hydrogenases of chernozem and eolian sand were different with respect to their kinetic properties. Increase of soil moisture above optimum moisture content or prior incubation of the soils under very high H2-mixing ratios (i.e. 1%) resulted in a decrease of Vmax or in an increase of the Km of the H2 oxidation reaction. Under anaerobic conditions, the Km for H2 was higher and Vmax was lower than under aerobic conditions. The anaerobic H2-oxidation activity of both soils was stimulated by the addition of artificial electron acceptors with redox potentials of at least 80 mV. Ferricyanide as the most efficient stimulator did not function as a final electron acceptor for anaerobic H2-oxidation, but acted as a catalyst by bypassing a rate-limiting electron transport step. In eolian sand, the aerobic as well as the anaerobic activity for atmospheric H2 oxidation decreased upon exposure to very high H2-mixing ratios (i.e. 1%). A similar effect was observed after incubation with ferricyanide which enabled the inflow of excess electrons from soil reductants or added NADH into the electron transport system of the soil hydrogenase with anaerobic activity. The activity for atmospheric H2 oxidation was regenerated during incubation in H2-free atmospheres, especially in the presence of oxygen. Inhibition and regeneration were probably due to alterations in components of the soil hydrogenases caused by the extent of a maximal electron flow through the electron transport system of the soil hydrogenases. Two classes of hydrogenase activities were discerned in eolian sand: one predominantly active under aerobic and the other under anaerobic conditions. 相似文献
35.
Wilko Heimann Maria Sylvester Thomas-Benjamin Seiler Henner Hollert Ralf Schulz 《Journal of Soils and Sediments》2011,11(7):1279-1291
Purpose
Although the water quality of the Rhine River in Europe has improved, contaminated sediments may still threaten fish populations. This is particularly likely in Upper Rhine oxbow lakes, which are connected to the main river channel only at one end, except for extreme flood events. The impact of such extreme flood events on the sediment toxicity has, however, not yet been investigated, although numerous oxbow lakes exist with varying degrees of connection to their main river channels. 相似文献36.
Listeria spp. isolated from cheese were tested for biochemical characteristics together with reference strains from culture collections. Microtitration plates were used for testing the fermentation patterns. The results were subjected to a numerical cluster analysis based on linkage maps. The variation of the group structures calculating the characteristics with and without the hemolysin reactions is demonstrated. The pathogenic species L. monocytogenes could only be separated from the avirulent species L. innocua by the hemolysin tests. Most of the cheese isolates were identified as L. innocua, some as L. monocytogenes and L. seeligeri. There is a need for an inexpensive commercial test kit to identify the serovars or virulence factors of Listeria spp. in the quality assessment of food. The present study sets up doubts for a sufficiently ensured separation of L. innocua from L. monocytogenes. 相似文献
37.
R Helmuth M A Montenegro A Steinbeck A Seiler O Pietzsch 《Berliner und Münchener tier?rztliche Wochenschrift》1990,103(12):416-421
The principles of molecular biological methods for epidemiological investigation of infectious bacteria are described. They were applied for differentiating S. enteritidis isolates originating from poultry. Among the methods described are the determination of the chromosomal DNA fingerprints (BRENDA), the methods of multilocus enzyme electrophoresis, plasmid profiles, and the outer membrane protein as well as lipopolysaccharide pattern. It turned out, that S. enteritidis strains isolated before 1987, in 1988 and the ones originating from Great Britain did not differ in anyone of these criteria. Consequently one has to assume, that the strains recently causing problems originate from the population of S. enteritidis which had existed in poultry before. 相似文献
38.
Gabriela Seiler Dr. Med. Vet. Sigitas Cizinauskas Dr. Med. Vet. Jürg Scheidegger Dr. Med. FMH Johann Lang Dr. Med. Vet. 《Veterinary radiology & ultrasound》2001,42(5):417-422
Magnetic resonance imaging was performed on an eight-year-old, neutered female German Shepherd dog with a history of acute depression, inappetence, and hyperthermia. A lesion in the cerebrum was suspected. Possible differential diagnoses were meningoencephalitis, neoplasia, and vascular lesion (infarction, bleeding). A ring enhancing lesion was found in the basal ganglia on the left side with edema of the surrounding brain tissue. A similar mass lesion was present in the right pterygoid musculature. With inversion recovery sequences an altered composition of the cerebrospinal fluid (CSF) in the left lateral ventricle could be detected. CSF analysis confirmed a pyocephalus, probably due to rupture of a brain abscess into the left lateral ventricle. 相似文献
39.
C.L. Mariani M.K. Jennings N.J. Olby L.B. Borst J.C. Brown Jr I.D. Robertson G.S. Seiler E. MacKillop 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2015,29(2):607-613
Background
Reports of histiocytic sarcoma (HS) involving the central nervous system (CNS) are sparse and consist mainly of case reports describing 1–3 animals.Objective
The objective of this study was to report the signalments, clinical signs, clinicopathologic and diagnostic imaging findings, treatment, and outcome of a series of dogs with HS and CNS involvement.Animals
Nineteen dogs with HS examined at veterinary referral hospitals.Methods
Retrospective case series. Medical records were reviewed and cases with a histopathological diagnosis of CNS HS were included in the study. Diagnostic imaging studies of the CNS were evaluated and histopathologic samples were reviewed to confirm the diagnosis.Results
Retrievers and Pembroke Welsh Corgis were overrepresented in this cohort of dogs. Tumors involved the brain in 14 dogs and the spinal cord in 5. In 4 dogs, HS was part of a disseminated, multiorgan process whereas it appeared confined to the CNS in 15 dogs. Diagnostic imaging had variable appearances although extraaxial masses predominated in the brain. There was meningeal enhancement in all dogs that was often profound and remote from the primary mass lesion. Pleocytosis was present in all dogs with CSF evaluation. Median survival was 3 days.Conclusions and Clinical Importance
Breed predispositions appear to vary from reports of HS in other organ systems. Some unique imaging and clinicopathologic characteristics, particularly brain herniation, profound meningeal enhancement, and pleocytosis in combination with 1 or more mass lesions, might help to differentiate this neoplasm from others involving the CNS, although this requires further study. 相似文献40.
ELASTOGRAPHIC EVALUATION OF NATURALLY OCCURING TENDON AND LIGAMENT INJURIES OF THE EQUINE DISTAL LIMB 下载免费PDF全文
Meghann Lustgarten W. Rich Redding Raphael Labens Weston Davis Thomas M. Daniel Emily Griffith Gabriela S. Seiler 《Veterinary radiology & ultrasound》2015,56(6):670-679
Compression elastography is an ultrasonographic technique that estimates tissue strain and may have utility in diagnosing and monitoring soft tissue injuries in the equine athlete. Recently, elastography has been proven to be a feasible and repeatable imaging modality for evaluating normal tendons and ligaments of the equine distal forelimb. The purposes of this prospective study were to investigate the ability of elastography to detect spontaneously occurring lesions of equine tendons and ligaments diagnosed with magnetic resonance imaging (MRI) and gray‐scale ultrasound (US) and to characterize the differences in the elastographic appearance of acute vs. chronic injuries. Fifty seven horses with a total of 65 lesions were evaluated. Images were assessed quantitatively and qualitatively. Acute lesions were found to be significantly softer (P < 0.0001) than chronic lesions (P < 0.0001) and the stiffness of lesions increased with progression of healing (P = 0.0138). A negative correlation between lesion hypoechogenicity and softness was appreciated with more hypoechoic lesions appearing softer (P = 0.0087) and more hyperechoic regions harder (P = 0.0002). A similar finding occurred with increased signal intensity on short tau inversion recovery (STIR) and proton density (PD) MRI sequences correlating with increased softness on elastography (P = 0.0164). Using US and MRI as references, commonly encountered soft tissue injuries of the equine distal limb could be detected with elastography. However, elastography was limited for detecting small, proximal injuries of the hindlimb proximal suspensory ligament. Elastographic evaluation of equine tendons and ligaments may allow better characterization of lesion chronicity and severity, and sequential examinations may optimize lesion management, rehabilitation, and return to training. 相似文献