bluuebunny/crossref_metadata_2025 huggingface dataset:
PU.1 protein expression has a positive linear association with protein expression of germinal centre B cell genes including BCL‐6, CD10, CD20 and CD22: identification of PU.1 putative binding sites in the BCL‐6 promotor
Authors: Torlakovic Emina , Malecka Agnieszka , Myklebust June H , Tierens Anne , Aasheim Hans‐Christian , Nesland Jahn M , Smeland Erlend , Kvaløy Stein , Delabie Jan
Published: May 2005

The transcription factor PU.1 has been shown to be crucial for the early stages of B cell development but its function at later stages of B cell development is less well known. We observed previously that PU.1 is expressed uniformly throughout the mature pre‐plasma cell B cell population, the only exception being a subpopulation of germinal centre (GC) cells which showed exceptionally high expression of PU.1. This suggested that PU.1 may also have a role in GC B cell biology. To test this hypothesis and to screen for possible genes regulated by PU.1, we first evaluated semi‐quantitatively the possible co‐expression of PU.1 with proteins known to be upregulated or downregulated during GC B cell development. Normal lymphoid tissues and 255 B cell non‐Hodgkin lymphomas of putative GC B cell origin were evaluated. PU.1 expression was positively associated with CD10 (p < 0.0001), CD20 (p = 0.043), CD22 (p = 0.005), CD79a (p = 0.024) and Bcl‐6 (p < 0.0001) and negatively associated with cytoplasmic immunoglobulin light‐chain expression (p = 0.036) in diffuse large B cell lymphoma. Identical or nearly identical associations were found in follicular lymphoma. Since CD20 is known to be partly regulated by PU.1 and putative PU.1‐binding sites have been described in the regulatory regions of the CD22, CD79a and CD10 genes, we looked for putative PU.1 binding sites in the BCL6 promotor. Four such putative PU.1 binding sites were identified. Further analysis by gel‐shift electromobility essay showed that PU.1 protein binds to three of the four putative binding sites in the BCL6 promotor. PU.1 and Bcl‐6 were also found to be upregulated in centroblasts in the normal GC, but jointly downregulated in a subpopulation of centrocytes. Our findings support the contention that PU.1 may also have an important role in GC B cell development. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Amplification and overexpression of c‐erbB‐2, epidermal growth factor receptor, and c‐met in biliary tract cancers
Authors: Nakazawa Kumiko , Dobashi Yoh , Suzuki Shioto , Fujii Hideki , Takeda Yasuhisa , Ooi Akishi
Published: May 2005

Carcinomas of the biliary tract have a poor prognosis. It is important to understand the molecular genetic characteristics of these tumours in order to employ newer effective treatments and to improve patient prognosis. There is increasing evidence that overexpression of tyrosine kinase growth factor receptors such as ErbB‐2, epidermal growth factor receptor (EGFR), and Met may play important roles in the development of biliary tract carcinomas. The aim of this study was to assess the potential for novel chemotherapies targeting these receptors. Overexpression of the tyrosine kinase receptor proteins was examined by immunohistochemistry in 221 biliary tract carcinomas, of which 28 were from the intrahepatic bile duct, 78 from the extrahepatic bile duct, 89 from the gall bladder, and 26 from the ampulla of Vater. Positively stained tumours were further examined for gene amplification by fluorescence in situ hybridization. Overexpression of ErbB‐2 was found in 15.7%, 11.5%, and 5.1% of carcinomas of the gall bladder, ampulla of Vater, and extrahepatic bile duct, respectively, and gene amplification was present in 79% of these. Overexpression of EGFR was found in 8.1% of tumours with no predominant location and was also associated with gene amplification with high frequency (77%). Met overexpression, most frequent in intrahepatic bile duct carcinomas (21.4%), was not associated with gene amplification. It is proposed that the new adjuvant chemotherapies could be directed to carcinomas of the biliary tract in which ErbB‐2 and EGFR are overexpressed. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
First evidence supporting a potential role for the BMP/SMAD pathway in the progression of oestrogen receptor‐positive breast cancer
Authors: Helms Mike W , Packeisen Jens , August Christian , Schittek Birgit , Boecker Werner , Brandt Burkhard H , Buerger Horst
Published: May 2005

Oestrogen receptor expression is generally a sign of better tumour differentiation and comparatively good clinical outcome in invasive breast cancer. However, oestrogen receptor‐positive, poorly differentiated carcinomas with a poor clinical outcome exist. The underlying genetic mechanisms and the genes involved remain obscure, even though chromosome 7p gains seem to be associated with these uncommon tumours. In this study, we compared two subsets of oestrogen receptor‐positive breast cancers, which differed in tumour grade, cytogenetic instability, and tumour proliferation, for their differential gene expression in order to identify proteins involved in the progression of oestrogen receptor‐positive breast cancers. We were able to show by means of subtractive suppression hybridization, real‐time reverse transcriptase PCR, and tissue microarray analysis that expression of the bone morphogenetic protein receptor IB (BMPR‐IB) is a major hallmark of the progression and dedifferentiation of breast cancer. Strong expression of BMPR‐IB was associated with high tumour grade, high tumour proliferation, cytogenetic instability, and a poor prognosis in oestrogen receptor‐positive carcinomas. Western blot analysis revealed that downstream signalling of this receptor is mainly mediated via phosphorylation of SMAD 1 in oestrogen receptor‐positive breast cancer. Even though BMPR‐IB was expressed in oestrogen receptor‐positive and ‐negative breast cancers, an impact on tumour grade, proliferation, and cytogenetic instability, as parameters of tumour progression, could only be demonstrated in oestrogen receptor‐positive carcinomas. This pro‐proliferative effect was complemented by significant anti‐apoptotic activity, indicated by XIAP and IAP‐2 expression in BMPR‐IB‐positive carcinomas. These results show that the BMP/SMAD pathway is activated in breast cancer and may contribute to breast cancer progression and dedifferentiation in oestrogen receptor‐positive breast cancer. The definition of this pathway characterizes a new potential target in the molecular treatment of invasive breast cancer. Copyright © 2005 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
The negative effect of red tape on research
Authors: Boshier A. , Shakir S. A. W. , Telfer P. , Behr E. , Pakrashi T. , Camm A. J.
Published: May 2005

Purposes

To describe the kind of the difficulties encountered when seeking research governance approval for a nationwide public health and genetic study—the Drug‐Induced Arrhythmia Risk Evaluation study—in England.

Methods

Description of the processes followed when seeking research governance approval for the Drug‐Induced Arrhythmia Risk Evaluation study—a case control study with annual follow‐up of cases and controls over 5 years, set in the English National Health Service (NHS).

Results

The authors describe wide variations in NHS research governance approval procedures in England.

Conclusion

NHS research governance procedures in England are impeding the process of epidemiological studies; there is the need for a centralised NHS R&D approval of studies, which is analogous to MREC for ethical approval. Copyright © 2005 John Wiley & Sons, Ltd.
Pressure and trimethylaluminum effects on ethene/1‐hexene copolymerization with methylaluminoxane‐activated (1,2,4‐Me3Cp)2ZrCl2: Trimethylaluminum suppression of standard termination reactions after 1‐hexene insertion
Authors: Bruaseth Ingvild , Bahr Matthias , Gerhard Dirk , Rytter Erling
Published: May 2005

Ethene homopolymerizations and copolymerizations with 1‐hexene were catalyzed by methylaluminoxane‐activated (1,2,4‐Me3Cp)2ZrCl2. Investigations of the effects of various pressures on the homopolymerizations and copolymerizations and of the effects of different concentrations of trimethylaluminum (TMA) on the copolymerizations were performed. The characteristics of the ethene/1‐hexene copolymers agreed with expectations for changes in the ethene concentration: the incorporation of 1‐hexene decreased, whereas the melting point and crystallinity increased, with increasing pressure. The main termination mechanism of the homopolymerizations was β‐hydrogen transfer to the monomer. Termination mechanisms resulting in vinylidene unsaturations dominated in the copolymerizations. Standard termination mechanisms producing vinyl and trans‐vinylene unsaturations occurred in parallel and were not influenced by the ethene or TMA concentration. In addition, some chain transfer to TMA, producing saturated end groups after hydrolysis, occurred. Copolymerizations with different additions of TMA, with the other polymerization conditions kept constant, showed that the catalytic productivity [tons of polyethylene/(mol of Zr h)], the 1‐hexene incorporation, and the molecular weight (from gel permeation chromatography) were independent of the TMA concentration. Surprisingly, the vinylidene content decreased almost linearly with increasing TMA concentration. TMA might have coordinated to the catalytic site after 1‐hexene insertion and rotation to the β‐agostic state and, therefore, suppressed the standard termination reactions after 1‐hexene insertion. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2584–2597, 2005
N‐Bromosuccinimide as a thermal iniferter for radical polymerization
Authors: Zhou Hong , Jiang Jianguo , Zhang Keda
Published: May 2005

N‐Bromosuccinimide (NBS) was used as a thermal iniferter for the initiation of the bulk polymerizations of methyl methacrylate, methyl acrylate, and styrene. The polymerizations showed the characteristics of a living polymerization: both the yields and the molecular weights of the resultant polymers increased linearly as the reaction time increased. The molecular weight distributions of the polymers were 1.42–1.95 under the studied conditions. The resultant polymers could be used as macroiniferters to reinitiate the polymerization of the second monomer. The copolymers poly(methyl methacrylate)‐b‐polystyrene and polystyrene‐b‐poly(methyl methacrylate) were obtained and characterized. End‐group analysis of the resultant poly(methyl methacrylate), poly(methyl acrylate), and polystyrene confirmed that NBS behaved as a thermal iniferter. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2567–2573, 2005
Hydration in a new semiaromatic polyamide observed by humidity‐controlled dynamic viscoelastometry and X‐ray diffraction
Authors: Uddin Ahmed Jalal , Gotoh Yasuo , Ohkoshi Yutaka , Nagura Masanobu , Endo Ryokei , Hara Tetsuya
Published: May 2005

Hydration in a new semiaromatic polyamide, named polyamide 9‐T (PA9‐T), a copolymer of terephthalic acid with n‐ and iso‐nonanediamines, is studied by dynamic viscoelastic analysis under controlled humidity conditions and wide‐angle X‐ray diffraction analysis in comparison with common polyamide nylon 6. The storage modulus of PA9‐T is retained at up to 60 °C with increasing humidity, then dropped with further increases in temperature past 70 °C. The decrease in mechanical properties at 70 °C due to moisture uptake is found to be substantially improved by annealing to develop molecular packing and/or crystallization. In contrast, the storage modulus of very highly crystallized (50% crystallinity) nylon 6 decreases markedly with humidity at low temperatures such as 20 °C. Thus, PA9‐T retains its mechanical properties in humid atmospheres at much higher temperatures than nylon 6. The crystalline X‐ray diffraction peaks for nylon 6 corresponding to (002) + (202) of the α form shift upon absorption of moisture, speculated to be due to the weakening of hydrogen bonds and the subsequent conformational disordering of the chains. Unlike nylon 6, the crystalline peaks of PA9‐T do not shift due to moisture uptake. This is considered to be attributable to that the long aliphatic chain in PA9‐T forms the large hydrophobic domain, rendering PA9‐T less hygroscopic than nylon 6. Additionally, strong hydrogen bonds formed by terephthalamide residues together with a strong stacking force of phenylene groups may also repel water, preventing moisture bind with the amide groups of PA9‐T crystals. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1640–1648, 2005
Thermomechanical properties and phase structure of epoxy/silica nano‐hybrid materials constructed from a linear silicone oligomer
Authors: Ochi Mitsukazu , Matsumura Tomoyuki
Published: May 2005

Epoxy‐grafted silicone oligomer (ESO), which has a linear silicone chain in the backbone moiety, was synthesized from a trifunctional alkoxysilane via a sol–gel reaction. Characterization of ESO was performed with 1H and 29Si NMR, Fourier transform infrared, and gel permeation chromatography. The number‐average molecular weight of ESO was 3300. By adding the silicone oligomer as the inorganic source in the curing process of the epoxy resin, novel epoxy/silica hybrid materials were prepared. It was observed by transmission electron microscope that fine silica‐rich domains of about 5‐nm diameter were uniformly dispersed in the cured epoxy matrix. Thermomechanical properties of the hybrid materials were also investigated. The storage modulus in the rubbery region and the peak area of the tan δ curve at the glass‐transition region increased and decreased, respectively, with the hybridization of the silica network. The mobility of the epoxy network chains should be considerably suppressed by the hybridization with the silica network. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1631–1639, 2005
Exploring the charge space of protein–protein association: A proteomic study
Authors: Shaul Yossi , Schreiber Gideon
Published: May 2005

The rate of association of a protein complex is a function of an intrinsic basal rate and of the magnitude of electrostatic steering. In the present study we analyze the contribution of electrostatics towards the association rate of proteins in a database of 68 transient hetero‐protein–protein complexes. Our calculations are based on an upgraded version of the computer algorithm PARE, which was shown to successfully predict the impact of mutations on kon by calculating the difference in Columbic energy of interaction of a pair of proteins. HyPare (http://bip.weizmann.ac.il/HyPare), automatically calculates the impact of mutations on a per‐residue basis for all residues of a protein–protein interaction, achieving a precision similar to that of PARE. Our calculations show that electrostatics play a marginal role (<10 fold) in determining the rate of association for about half of the complexes in the database. Strong electrostatic steering, which results in an increase of over 100‐fold in kon, was calculated for about 25% of the complexes. Applying HyPare to all 68 complexes in the database shows that a small number of residues are hotspots for association. About 40% of the hotspots are calculated to increase the rate of association upon mutation, and thus increase binding affinity. This is a much higher ratio than found for hotspots for dissociation, where the large majority cause weaker binding. About 40% of the hotspots are located outside the physical boundary of the binding site, making them ideal candidates for protein engineering. Our data shows that a majority of protein–protein complexes are not optimized for fast association. Hotspots are not evenly distributed between all types of amino acids. About 75% of all hotspots are of charged residues. This is understandable, as a charge‐reverse mutant changes the total charge by 2. The small number of hydrophobic residues that are hotspots upon mutation probably relates to their location and surrounding. For 18 out of the 68 complexes in the database, experimental values of kon are available. For these, a basal rate of association was calculated to be in the range of 104M−1s−1 to 107M−1s−1. Some of these rates were verified independently from experimental mutant data. The basal rates were correlated with the size of the proteins and the shape of the interface. Proteins 2005. © 2005 Wiley‐Liss, Inc.
A new relaxed state in horse methemoglobin characterized by crystallographic studies
Authors: Sankaranarayanan R. , Biswal B.K. , Vijayan M.
Published: May 2005

A new relaxed state has been characterized in the crystals of horse methemoglobin grown at neutral pH at low ionic concentration and their low humidity variants. The crystals provide an example for improvement in X‐ray diffraction quality with reduced solvent content. Only the classical R state has been so far observed in liganded horse hemoglobin. The state characterized in the present study lies in between the R state and the R2 state characterized earlier in liganded human hemoglobin. The results presented here, along with those of earlier studies, suggest that relaxed and tense hemoglobin can access ensembles of states. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Effect of dense plasma on the spectral properties of hydrogenic ions
Authors: Sil A. N. , Saha B. , Mukherjee P. K.
Published: May 2005

The effect of strongly coupled plasma on the energy levels, dynamic polarizabilities, oscillator strengths, and transition probabilities of a number of hydrogenic ions is estimated, using the ion‐sphere (IS) model. The transition properties are calculated using time‐dependent variation perturbation theory. The variation of the atomic properties under different plasma densities are analyzed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Ab initio study of the far infrared spectrum of glycine
Authors: Senent M. L. , Villa M. , Domínguez‐Gómez R. , Fernández‐Clavero A.
Published: May 2005

In glycine, four large amplitude vibrations, the three internal rotations of the CC, COH, and CN bonds, and the amine group inversion are responsible for the nonrigidity of the molecule. They present 12 potential energy surface minima corresponding to eight different conformers. The energy levels for the four motions mentioned above and the HNH bending were determined using ab initio calculations and three different flexible models in one, two, and three dimensions. For this purpose, eight different MP4/cc‐pVTZ potential energy surfaces, five one‐dimensional for each internal coordinate, one two‐dimensional potential depending on the amine wagging and bending coordinates, and one three‐dimensional potential depending on the three internal rotation coordinates, were calculated. For the most stable conformer, the harmonic frequencies corresponding to the HNH bending, NH2 inversion, and the CC, COH, and CN torsions were calculated at 1677, 955, 65, 657, and 218 cm−1, and the anharmonic fundamental frequencies to be 1454, 803, 78, 522, and 175 cm−1 with the one‐dimensional model. The NHN bending and amine wagging fundamentals are determined to be 1688, and 799 with the two‐dimensional model. The fundamentals of the CC, COH and CN torsions were calculated to be 86, 546, and 189 cm−1 with the three‐dimensional model. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Analytic atomic wave functions of NMCSCF quality: Applications
Authors: Xiong Z. , Velgakis M. I. , Bacalis N. C.
Published: May 2005

Concise analytic, nonorthogonal but selectively orthogonalizable, modified Laguerre type atomic orbitals are developed, providing conciseness, clear physical interpretation, and near‐equivalent accuracy with numerical multi‐configuration self‐consistent field, to atomic configuration interaction calculations. By analyzing the general Eckart theorem, which introduces an energy augmentation to the variational criterion for excited states, securing against variational collapse, we use them to calculate several excited atomic states known to be in danger of suffering from variational collapse. We also use them to calculate highly excited states, applied to computation of recently measured VUV spectra of He states near the second ionization threshold. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Cyanobacteria/cyanotoxin research—Looking back for the future: The opening lecture of the 6th ICTC, Bergen, Norway
Authors: Skulberg Olav M.
Published: May 2005

A retrospective view of the development of research on cyanobacteria and their toxins—in Norway and worldwide—is cursorily examined. Combined with a personal narrative of the work and life of the author, the relevant research progress in the last 50 years of the 20th century is outlined. This was the period in biology when research of toxigenic cyanobacteria was coming to a head. The knowledge and understanding achieved were the result of a collective international enterprise binding the community of specialists together. The noxious organisms were isolated, and the basic chemistry, physiology, and toxicology of the specific cyanotoxins were settled. At the threshold today of what is widely regarded as the century of biology, the study of toxigenic cyanobacteria is undergoing important transformations. New frontiers include the interface between molecular biology, biochemistry, toxicology, and ecology. The results of the basic and applied research efforts will expand the understanding of cyanobacteria and be beneficial to the management of natural resources and the care of human beings. The tiny cyanobacteria, being a geological force in the dynamics of the globe, will continually become more central to the modern world and be applied more closely, affecting our lives. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 220–228, 2005.
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

Microcystins (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

Modulation 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

In 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

The 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

A 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

The 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

Benthic 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

Many 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

X‐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

Sandia 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

The 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

We 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

Abstract

During 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.

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

Background: 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.
The application of mass spectrometry to identify immunogenic components of excretory/secretory products from adult Dictyocaulus viviparus
Authors: MATTHEWS J. B. , DAVIDSON A. J. , BEYNON R. J.
Published: May 2005

Proteomics has come to the forefront in the post-genomic era. The ability to compare and identify proteins expressed in a particular cell type under specific physiological or pathological states requires a range of technologies, including separation of complex protein or peptide mixtures, densitometry-based or isotope-coded methods for comparison of multiple proteomes, and mass spectrometric methods for identification of individual low abundance proteins. Although an emergent technology, thus far, proteomics has provided new perspectives on many problems in biomedical science. In parasitology, proteomics has been used to answer specific biological questions relating to survival and development, and also to identify candidates for vaccines. Here, we describe an ongoing research programme in which proteomics is being used to identify potential vaccine candidates for the bovine lungworm, Dictyocaulus viviparus. This work is focusing on antibody responses to the adult parasite excretory/secretory (ES) products, with selection of candidate antigens based on differential screening with serum from immune versus non-immune animals to simplify the proteome and the ensuing analytical challenges. Thus far, we have identified seven candidate proteins using this strategy. Of these, one protein showed significant identity to a previously cloned gene from D. viviparus, whilst the other six proteins have shown no significant identities. Isolation of further peptide sequences is now warranted to facilitate cloning of the genes encoding these antigens.
Data mining parasite genomes
Authors: BERRIMAN M.
Published: May 2005

The term ‘data mining’ can be used to describe any process where useful information is extracted from data with a large background of ‘noise’. In the context of a genome project, several stages involve data mining. Amongst the sequence data, ‘signals’ need to be detected that indicate the presence of interesting features. Often this involves differentiating between transcribed and non-transcribed bases to predict coding regions. After detection, defining the roles of these sequences involves sifting through multiple lines of evidence. If these roles are accurately reflected in genome annotation, they can be used by researchers to frame queries and interrogate the data further.
Screening and synthesis: high throughput technologies applied to parasitology
Authors: MORGAN R. E. , WESTWOOD N. J.
Published: May 2005

High throughput technologies continue to develop in response to the challenges set by the genome projects. This article discusses how the techniques of both high throughput screening (HTS) and synthesis can influence research in parasitology. Examples of the use of targeted and phenotype-based HTS using unbiased compound collections are provided. The important issue of identifying the protein target(s) of bioactive compounds is discussed from the synthetic chemist's perspective. This article concludes by reviewing recent examples of successful target identification studies in parasitology.