bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diversity of hepatotoxic microcystins and bioactive anabaenopeptins in cyanobacterial blooms from Greek freshwaters
Authors: Gkelis Spyros , Harjunpää Vesa , Lanaras Tom , Sivonen Kaarina 
Published: May 2005

AbstractMicrocystins (MCs) and anabaenopeptins from 26 cyanobacterial bloom samples dominated mainly by the genus Microcystis and collected from seven Greek freshwaters were identified and quantified by high‐performance liquid chromatography coupled to a diode array detector. All the samples analyzed contained microcystins; in 27% of the samples anabaenopeptins were detected but not anabaenopeptilide (A). In each sample 1–7 microcystins and up to two anabaenopeptins (anabaenopeptins A and B) were identified. MC‐RR and MC‐LR were the predominant microcystins, followed by MC‐YR. MC‐LA and demethylated variants of MC‐LR and MC‐RR also were present but were not abundant. Total content of microcystin and anabaenopeptin varied from 40 to 2565 μg g−1 freeze‐dried material (mean 674.5 μg g−1) and from undetectable to 48 μg g−1 freeze‐dried material (mean 6.2 μg g−1), respectively. Qualitative and quantitative variation in the microcystins in the samples indicates there may be geographical trends in the distribution of microcystins. This study reports for the first time (1) the widespread occurrence of several different microcystins in Greek freshwaters and (2) quantitative data on the anabaenopeptins produced in natural cyanobacterial populations. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 249–256, 2005.
Microcystin content of Microcystis aeruginosa is modulated by nitrogen uptake rate relative to specific growth rate or carbon fixation rate
Authors: Downing T. G. , Meyer C. , Gehringer M. M. , van de Venter M. 
Published: May 2005

AbstractModulation of microcystin production has been extensively studied in both batch and continuous cultures. Positive correlations with medium nitrogen, medium phosphorous, light intensity, inorganic carbon availability, and growth rate have been reported. Negative correlations have been reported between microcystin content and medium phosphorous. The only reported quantitative relationship between any variable and microcystin production was that of growth rate. Microcystis aeruginosa PCC7806 was therefore cultured under continuous culture conditions in a bubble‐lift reactor at a growth rate of 0.01 h−1 in modified BG11 (constant phosphate concentration of 0.195 mM and varying nitrate from 0.125 to 18 mM) and sampled at steady states for analysis of cell number, microcystin content, cellular N and P, residual medium nutrient concentration, and carbon fixation rate. Cellular microcystin quotas showed significant positive correlation with both nitrate uptake and cellular nitrogen content and were negatively correlated with carbon fixation rate, phosphate uptake, and cellular phosphorous. Thus, the ratio of nitrate uptake to phosphate uptake, cellular N to cellular P, and nitrate uptake to carbon fixation were positively correlated to cellular microcystin. Microcystin quotas increased 10‐fold from the lowest to the highest steady‐state values. Cellular microcystin content therefore is controlled to a significant extent by variables other than growth rate, as was previously reported, with nitrogen the most significant modulator. Batch culture in BG11 under identical conditions yielded increased microcystin when nitrogen uptake exceeded relative growth rate, confirming the importance of nitrogen uptake in the modulation of microcystin content for a specific growth rate. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 257–262, 2005.
Chronic toxicity and responses of several important enzymes in Daphnia magna on exposure to sublethal microcystin‐LR
Authors: Chen Wei , Song Lirong , Ou Danyun , Gan Nanqin 
Published: May 2005

AbstractIn the current study, the toxicological mechanisms of microcystin‐LR and its disadvantageous effects on Daphnia magna were examined. Survival rate, number of newborn, activity of several important enzymes [glutathione S‐transferase (GST), lactate dehydrogenase (LDH), phosphatases, and glutathione], accumulated microcystins, and ultrastructural changes in different organs of Daphnia were monitored over the course of 21‐day chronic tests. The results indicated that low concentrations of dissolved microcystin had no harmful effect on Daphnia. On the contrary, stimulatory effects were detected. In the presence of toxin at high dosage and for long‐term exposure, GST and glutathione levels decreased significantly. The decreased enzyme activity in the antioxidant system probably was caused by detoxification reactions with toxins. And these processes of detoxification at the beginning of chronic tests may enable phosphatases in Daphnia magna to withstand inhibition by the toxins. At the same time, we also found that the LDH activity in test animals increased with exposure to microcystin‐LR, indicating that adverse effects occurred in Daphnia. With microcystin given at a higher dosage or for a longer exposure, the effect on Daphnia magna was fatal. In the meantime, microcystin began to accumulate in Daphnia magna, and phosphatase activity started to be inhibited. From the ultrastructure results of cells in D. magna, we obtained new information: the alimentary canal may be the target organ affected by exposure of microcystins to D. magna. The results of the current study also suggested that the oxidative damage and PPI (protein phosphatase inhibition) mechanisms of vertebrates also are adapted to Daphnia. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 323–330, 2005.
Trophic transfer of cyanobacterial toxins from zooplankton to planktivores: Consequences for pike larvae and mysid shrimps
Authors: Karjalainen Miina , Reinikainen Marko , Spoof Lisa , Meriluoto Jussi A. O. , Sivonen Kaarina , Viitasalo Markku 
Published: May 2005

AbstractThe aim of this study was to evaluate the potentially harmful effects of zooplankton preexposed to cyanobacteria on two planktivorous animals: a fish larva (pike, Esox lucius) and a mysid shrimp (Neomysis integer). The planktivores were fed zooplankton from a natural community that had been preexposed to cell‐free extract or to purified toxin (nodularin) of the cyanobacterium Nodularia spumigena, and the growth, feeding, and pellet production of the planktivores, as well as the toxin content of the pellets, were measured. In addition, radiolabeled nodularin (3H‐dihydronodularin) was used in separate experiments to measure the vector transfer of nodularin from zooplankton to their predators. During 11‐day exposures, dissolved nodularin was transferred to pike larvae and N. integer via zooplankton at very low rates of accumulation. Treatment with N. spumigena extract decreased the ingestion and feces production rates of pike larvae. With purified nodularin alone, no such effect could be observed. No effect on molting cycle length, fecal pellet production, C:N ratio, or growth of N. integer was detected. The results suggest that dissolved cyanobacterial toxins released during bloom decay can have a negative impact on feeding and, hence, on the growth of fish larvae via zooplankton, even without direct contact between cyanobacteria and the fish. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 354–362, 2005.
Effects of microcystins on and toxin degradation by Poterioochromonas sp.
Authors: Ou Danyun , Song Lirong , Gan Nanqin , Chen Wei 
Published: May 2005

AbstractA Chrysophyceae species, Poterioochromonas sp., was isolated from Microcystis cultures. This species can efficiently prey on Microcystis and can grow faster phagotrophically than autotrophically. The growth of Poterioochromonas sp. was stimulated in the presence of microcystin‐LR and microcystin‐RR (in concentrations ranging from 0.1 to 4 mg/L). The growth rate of Poterioochromonas was 4–5 times higher than the control, indicating the toxins serve as growth stimuli for this organism. A subculture of toxin‐treated cells, however, showed low cellular viability, suggesting that growth enhancement by microcystins was not a normal process. The antioxidant enzymatic activity of Poterioochromonas sp. was screened for toxicology analysis. Glutathione, malondialdehyde, and superoxide dismutase (SOD) content was up‐regulated within 8 h of exposure to microcystin‐LR (500 μg/L). A high level of SOD activity during exposure to the toxin indicated that SOD was involved in decreasing oxidative stress caused by microcystin‐LR. Simultaneously with growth, Poterioochromonas was able to degrade microcystin‐LR even, at a toxin concentration of 4 mg/L. This putative degradation mechanism in Poterioochromonas is explored further and discussed in this article. Our findings may shed light on understanding the role of Poterioochromonas in the aquatic ecosystem, in particular, as a grazer of toxic cyanobacteria and a biodegrader for microcystins. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 373–380, 2005.
Occurrence of toxic blue‐green algae in the Kucukcekmece lagoon (Istanbul, Turkey)
Authors: Albay Meric , Matthiensen Alexandre , Codd Geoffrey A. 
Published: May 2005

AbstractThe concentration of microcystin (MC) in the Kucukcekmece Lagoon, Istanbul, Turkey, and the physicochemical and biological parameters of water quality were investigated from October 2000 to June 2003. Water samples were collected from surface waters at three sites. Most bloom samples were dominated by Microcystis aeruginosa. The major microcystin variants detected by HPLC‐PDA were microcystin‐YR and microcystin‐LR. Microcystin concentration increased dramatically from early summer to early autumn and thereafter tended to decrease. The toxin concentration found in the filtered samples from surface waters varied between 0.06 and 24.2 μg L−1 microcystin‐LR equivalents. Each year extensive fish mortality was recorded between mid‐June and early October, coinciding with heavy algal blooms. A comparison of the conditions associated with cyanotoxin episodes in 2000, 2001, and 2002 showed that the microcystin increase was related to temperature, high concentration of dissolved nutrients, high light intensity (PAR). The highest MC concentrations were recorded at temperatures between 24°C and 28.5°C. Field data showed that the highest MC concentration (>3 μg L−1) and the highest cyanobacterial biomass (>30 mg L−1) corresponded to a total nitrogen:total phosphorus ratio greater than 7:1. The highest concentrations of M. aeruginosa biomass (173 mg L−1) and MC (24.2 μg L−1 MC‐LR equiv.) and the highest salinity (8.8%) were measured concurrently in the lagoon. To our knowledge, this is the first evidence of cyanobacterial toxins in the Kucukcekmece Lagoon. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 277–284, 2005.
Benthic cyanobacteria from the Baltic Sea contain cytotoxic Anabaena, Nodularia, and Nostoc strains and an apoptosis‐inducing Phormidium strain
Authors: Surakka Anu , Sihvonen Leila M. , Lehtimäki Jaana M. , Wahlsten Matti , Vuorela Pia , Sivonen Kaarina 
Published: May 2005

AbstractBenthic cyanobacteria from aquatic environments have been reported to produce biologically active metabolites. However, the toxicity and other biological activities of benthic cyanobacteria from the Baltic Sea are not well known. We determined the biological activities of 21 Anabaena, Calothrix, Nodularia, Nostoc, and Phormidium strains isolated from benthic littoral habitats of the Baltic Sea. We studied whether benthic cyanobacterial extracts caused cytotoxicity by necrosis or induced apoptosis in two mammalian cell lines, a human leukemia cell line (HL‐60) and a mouse fibroblast cell line (3T3 Swiss), and examined potential hepatotoxin (microcystin and nodularin) production. Five of the six benthic Anabaena strains, one of the two Nostoc strains, and two of the three Nodularia strains were highly cytotoxic to human leukemia cells. The Calothrix and Phormidium strains did not cause LDH leakage, but the extract of Phormidium strain BECID15 induced apoptosis in the HL‐60 cells. Neither the microcystin synthetase E (mcyE) nor the nodularin synthetase F (ndaF) gene was amplified by PCR, and no microcystins or nodularins were detected by the protein phosphatase inhibition assay from the cyanobacterial strains included in this study. This indicates that benthic Baltic cyanobacteria contain potentially harmful cytotoxic compounds even though they do not produce microcystins or nodularins. These cytotoxic compounds remain to be characterized, and the mechanisms of cytotoxicity need to be studied further. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 285–292, 2005.
Characterization of proteases in guts ofDaphnia magnaand their inhibition byMicrocystis aeruginosaPCC 7806
Authors: Agrawal Manish K. , Zitt Anja , Bagchi Divya , Weckesser Jürgen , Bagchi Suvendra N. , von Elert Eric 
Published: May 2005

AbstractMany cyanobacteria produce peptides that inhibit mammalian proteases. The hypothesis that inhibitors of mammalian proteases produced by cyanobacteria also interfere with digestive proteases of natural cladoceran grazers was tested by comparing the effects of cyanobacterial protease inhibitors on digestive proteases fromDaphnia magnaand on commercially available bovine proteases. The major digestive proteases ofD. magnaare trypsins and chymotrypsins, which differ from those of bovine origin in substrate specificity and susceptibility to synthetic inhibitors. An extract fromMicrocystis aeruginosastrain PCC 7806 inhibited both types ofD. magnaproteases. Subsequent fractionation of the extract by high‐performance liquid chromatography indicated that several inhibitors are produced byM. aeruginosathat differ in their specificity for the trypsins and chymotrypsins ofD. magna. Two fractions differed in their inhibitory effect on proteases ofD. magnaand bovine origin; therefore, assessment of the impact of cyanobacterial protease inhibitors on natural communities requires the use of digestive proteases from ecologically relevant grazers. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 314–322, 2005.
Analysis of magnetic dust layers on Mars by PIXE and XRF
Authors: Jensen J. , Folkmann F. , Gunnlaugsson H. P. , Merrison J. P. , Kinch K. , Knudsen J. M. , Nørnberg P. , Bertelsen P. , Madsen M. B. 
Published: May 2005

AbstractX‐ray analysis with the instruments on the rovers on Mars, landed in January 2004, and application to the thin dust layer accumulated on magnets on the rovers are discussed. Particle excitation and x‐ray fluorescence have different effective depths and call for a more elaborate analysis of a thin surface layer. Measurements from Mars are presented and exhibit a similar elemental composition of the accumulated magnetic dust to that of the surrounding soil. Copyright © 2005 John Wiley & Sons, Ltd.
An annular Si drift detector µPIXE system using AXSIA analysis
Authors: Doyle B. L. , Walsh D. S. , Kotula P. G. , Rossi P. , Schülein T. , Rohde M. 
Published: May 2005

AbstractSandia and Rontec have developed an annular, 12‐element, 60 mm2, Peltier‐cooled, translatable, silicon drift detector called the SDD‐12. The body of the SDD‐12 is only 22.8 mm in total thickness and easily fits between the sample and the upstream wall of the Sandia microbeam chamber. At a working distance of 1 mm, the solid angle is 1.09 sr. The energy resolution is 170 eV at count rates <40 kcps and 200 eV for rates of 1 Mcps. X‐ray count rates must be maintained below 50 kcps when protons are allowed to strike the full area of the SDD. Another innovation with this new µPIXE system is that the data are analyzed using Sandia's Automated eXpert Spectral Image Analysis (AXSIA). Copyright © 2005 John Wiley & Sons, Ltd.
Detection angle resolved PIXE and the equivalent depth concept for thin film characterization
Authors: Reis M. A. , Chaves P. C. , Corregidor V. , Barradas N. P. , Alves E. , Dimroth F. , Bett A. W. 
Published: May 2005

AbstractThe characterization of thin films using PIXE, although basically a simple matter, in practice suffers from significant problems. Here two case studies are presented in which the use of grazing detection geometry is shown to be a good solution. The first case study, the analysis of GaSb–InAs films deposited on a GaSb substrate, relates to the measurement of elements of atomic number close to and below that of the substrate. Problems may be due to the tail of the peaks that correspond to x‐rays emitted from the substrate, and also to the presence in the substrate of an element having large x‐ray emission cross‐sections. The use of the simulation capability implemented on the DATTPIXE package is shown to be of good help in the proper planning of the analysis procedure. In the second case study, the distinction between film contamination and substrate material contamination is discussed. In this case the characterization of a ZnO film deposited on sapphire is presented. The concept of equivalent depth is discussed and it is shown to be an important tool for a straightforward distinction between film and bulk contamination. Copyright © 2005 John Wiley & Sons, Ltd.
Prognosis of Hepatocellular Carcinoma after Hepatectomy in Patients with Renal Dysfunction
Authors: Kaibori Masaki , Matsui Yoichi , Kwon A‐Hon , Tokoro Toshiko , Kamiyama Yasuo 
Published: May 2005

AbstractWe evaluated the effect of renal dysfunction on the prognosis of hepatocellular carcinoma in 224 patients who underwent hepatic resection. Survival was compared between patients with (57 patients) and without renal dysfunction (116 patients), using a creatinine clearance ≤70 ml/min as the cut‐off value. There were no significant differences with respect to other preoperative characteristics, operative findings, or histology between the two groups. There was also no difference in survival between the two groups after hepatic resection. However, among 132 patients with a solitary tumor measuring ≤5 cm in greatest dimension, the disease‐free and overall survival rates of 36 patients with renal dysfunction were significantly worse after resection than those of the patients without renal dysfunction (p = 0.04 and p = 0.0003, respectively). By multivariate analysis, renal dysfunction was an independent factor indicating a poor prognosis for disease‐free and overall survival after resection of small solitary tumors (p = 0.0401 and p = 0.0031, respectively). Renal dysfunction did not affect the overall prognosis after resection of hepatocellular carcinoma, but it worsened the prognosis of patients with small solitary lesions.
Molecular Targeting of Pancreatic Disorders
Authors: Tamada Kiichi , Wang Xiao‐Ping , Brunicardi F. Charles 
Published: May 2005

AbstractDuring the last decade significant advances in gene therapy have made it possible to treat various pancreatic disorders in both animal models and in humans. For example, insulin gene delivery to non‐β‐cell tissues has been shown to reverse hyperglycemia in diabetic mice, and islet transplantation, based on in vitro differentiation of β cells and concomitant gene targeting to prevent host autoimmune responses, has become more feasible. Additionally, introduction of the glucokinase regulatory protein and protein kinase C‐ζ have been shown to improve glucose tolerance in non‐insulin‐dependent diabetes mellitus animal models. Pancreatic cancer studies utilize several DNA‐based strategies for tumor treatment including introduction of tumor suppressor genes, suppression of oncogenes, suicide gene/prodrug therapy, and restricted replication‐competent virus therapy. Tumor‐specific targeting is an important part of suicide gene therapy, and tumor‐specific promoters are used for cell‐specific targeting. Tumor‐specific suicide gene therapy directed by the rat insulin promoter has been used to eliminate insulinoma tumors in a mouse model. This review compiles a compendium of information related to the treatment of pancreatic disorders using gene therapy.
The relaxed energy for
\( S^{2} \)-valued maps and measurable weights
Authors: Millot Vincent 
Published: May 2005

We compute explicitly a relaxed type energy for maps

u:\Omega \subset \mathbb{R}^{3}\rightarrow S^{2}

. The explicit formula involves the length of a minimal connection relative to some specific distance connecting the topological singularities of

u

and associated to a measurable weight function. This result generalizes a previous result of F. Bethuel, H. Brezis and J.M. Coron.

Résumé

Nous calculons explicitement une énergie de type relaxée pour des applications

u:\Omega \subset \mathbb{R}^{3}\rightarrow S^{2}

. La formule explicite fait intervenir la longueur d'une connexion minimale relative à une certaine distance, connectant les singularités topologiques de

u

et associée à une fonction de poids mesurable. Ce résultat généralise un résultat antérieur de F. Bethuel, H. Brezis et J.M. Coron.
Femur window—a new approach to microcirculation of living bone in situ
Authors: Hansen‐Algenstaedt N. , Schaefer C. , Wolfram L. , Joscheck C. , Schroeder M. , Algenstaedt P. , Rüther W. 
Published: May 2005

AbstractBackground: The processes of osteogenesis, bone remodelling, fracture repair and metastasis to bone are determined by complex sequential interactions involving cellular and microcirculatory parameters. Consequently studies targeting the analysis of microcirculatory parameters on such processes should mostly respect these complex conditions. However these conditions could not yet be achieved in vitro and therefore techniques that allow a long‐term observation of functional and structural parameters of microcirculation in bone in vivo at a high spatial resolution are needed to monitor dynamic events, such as fracture healing, bone remodelling and tumor metastasis.Methods: We developed a bone chamber implant (femur window) for long‐term intravital microscopy of pre‐existing bone and its microcirculation at an orthotopic site in mice preserving the mechanical properties of bone. After bone chamber implantation vascular density, vessel diameter, vessel perfusion, vascular permeability and leukocyte‐endothelial interactions (LEIs) in femoral bone tissue of c57‐black mice (n = 11) were measured quantitatively over 12 days using intravital fluorescence microscopy. Furthermore a model for bone defect healing and bone metastasis in the femur window was tested.Results: Microvascular permeability and LEIs showed initially high values after chamber implantation followed by a significant decrease to a steady state at day 6 and 12, whereas structural parameters remained unaltered. Bone defect healing and tumor growth was observed over 12 and 90 days respectively.Conclusion: The new femur window design allows a long‐term analysis of structural and functional properties of bone and its microcirculation quantitatively at a high spatial resolution. Altered functional parameters of microcirculation after surgical procedures and their time dependent return to a steady state underline the necessity of long‐term observations to achieve unaltered microcirculatory parameters. Dissection of the complex interactions between bone and microcirculation enables us to evaluate physiological and pathological processes of bone and may give new insights especially in dynamic events e.g. fracture healing, bone remodeling and tumor metastasis. © 2005 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.