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Selected AbstractsAcute toxicity of triorganotin compounds: Different specific effects on the energy metabolism and role of pHENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2002René W. Hunziker Abstract Triorganotin compounds exhibit several modes of toxic action on the energy metabolism in energy-transducing membranes. The inhibition of the adenosine triphosphate (ATP) synthase and the hydroxide/chloride-antiport have been extensively investigated, but debate still exists on whether further mechanisms are relevant. In this work, two possible further effects have been investigated: inhibition of the bc1 complex and the hydroxide uniport, and in addition, the overall inhibition of the ATP synthesis was investigated in chromatophores of the photosynthetic purple bacterium Rhodobacter sphaeroides at pH = 7.5 and pH = 6.1. Experimental conditions were chosen in order to exclude the hydroxide/anion antiport as a possible effect. Inhibition of the cytochromes bc1 complex was detected, but at such high concentrations that it is not relevant for acute toxicity. Tributyltin was found to induce a decrease of the membrane potential, which can be attributed to a hydroxide uniport, whereas for triphenyltin no such activity was observed. For both compounds, inhibition of the ATP synthesis was higher at pH = 6.1 than at pH = 7.5. Also the hydroxide uniport activity of tributyltin was higher at lower pH. The contribution of the hydroxide uniport of tributyltin to the overall inhibition of the ATP synthesis cannot be quantified; however, hydroxide uniport occurred in the same concentration range as inhibition of the ATP synthesis. For triphenyltin, inhibition of the ATP synthesis can be attributed to the inhibition of the ATP synthase. It was concluded that chromatophores of R. sphaeroides are a useful system to discriminate various effects of toxicants on the energy metabolism of a cell. [source] Pathogenesis of Helicobacter pylori InfectionHELICOBACTER, Issue 2008Javier Torres Abstract The clinical outcome of Helicobacter pylori infection is determined by a complex scenario of interactions between the bacterium and the host. The main bacterial factors associated with colonization and pathogenicity comprise outer membrane proteins including BabA, SabA, OipA, AlpA/B, as well as the virulence factors CagA in the cag pathogenicity island (cagPAI) and the vacuolating cytotoxin VacA. The multitude of these proteins and allelic variation makes it extremely difficult to test the contribution of each individual factor. Much effort has been put into identifying the mechanism associated with H. pylori -associated carcinogenesis. Interaction between bacterial factors such as CagA and host signal transduction pathways seems to be critical for mediating the induction of membrane dynamics, actin-cytoskeletal rearrangements and the disruption of cell-to-cell junctions as well as proliferative, pro-inflammatory and antiapoptotic nuclear responses. An animal model using the Mongolian gerbil is a useful system to study the gastric pathology of H. pylori infection. [source] Effects of hybridization on the immunity of collared Ficedula albicollis and pied flycatchers F. hypoleuca, and their infection by haemosporidiansJOURNAL OF AVIAN BIOLOGY, Issue 4 2009Chris Wiley Because they are ubiquitous and typically reduce the fitness of hosts, parasites may play important roles in hybrid zone dynamics. Despite much work on herbivores and hybrid plants, the effect of parasites on the fitness of animal hybrids is poorly known. In an attempt to partly fill this gap, we examined the prevalence of avian haemosporidians Haemoproteus in a hybrid zone between collared Ficedula albicollis and pied flycatchers F. hypoleuca. 40 species-informative genetic markers allowed us to identify F1 hybrids, thus avoiding problems inherent in many studies that group hybrid genotypes. Furthermore, naturally occurring extra-pair paternity allowed us to test the immune responses of pure and hybrid nestlings to a novel antigen (phytohaemagglutinin) in a shared environment. In contrast to previous suggestions that animal hybrids may more often display resistance against parasites than plant hybrids, F1 hybrids exhibited prevalence of parasitism and immune responses that were intermediate between the two parental species. We also detected differences between the two parental species in their prevalence of infection, with the competitively dominant species (collared flycatcher) being less often infected by Haemoproteus. Overall, our results contribute to other recent data supporting the idea that the resistance of animals to parasites is variously and unpredictably affected by hybridization, and that there is a concordance in the general patterns observed in plants and animals. Haemosporidians in avian hybrids provide a useful system for investigating the interactions between hosts and parasites that characterize host contact zones. [source] Managing the optimal workload by the PAONCIL method , a challenge for nursing leadership in care of older peopleJOURNAL OF NURSING MANAGEMENT, Issue 4 2009MARIANNE FRILUND RN, MNSc Aim, The aim of the study was to test the ability of the professional assessment of optimal nursing care intensity level (PAONCIL)-method to establish the optimal nursing intensity (NI) per care giver within the care of older people by testing whether the method's prerequisites for hospital settings can be fulfilled within the care of older people as well. Background, The PAONCIL method is included in the RAFAELA system as a method for calculating personnel resources based on NI. Method, The PAONCIL assessments were collected through questionnaires (n = 3512). The data was analysed by simple linear regression analysis. Results, It can be stated that the prerequisites for the PAONCIL method were fulfilled and that the optimal NI-level could be determined on seven participating units. Discussion, It can be stated that the RAFAELA system is a useful system for measuring NI within the care of older people, but additional research is needed, especially within the home care setting. Conclusion, Although an instrument never provides a complete overview of the patient's care needs and need satisfaction, it provides information about the daily situation as well as gives guidelines for long-term strategic planning. [source] Hydrogenated castor oil nanoparticles as carriers for the subcutaneous administration of tilmicosin: in vitro and in vivo studiesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2009C. HAN Tilmicosin-loaded solid lipid nanoparticles (SLN) were prepared with hydrogenated castor oil (HCO) by o/w emulsion,solvent evaporation technique. The nanoparticle diameters, surface charges, drug loadings and encapsulation efficiencies of different formulations were 90,230 nm, ,6.5,,12.5 mV, 40.3,59.2% and 5.7,11.7% (w/w), respectively. In vitro release studies of the tilmicosin-loaded nanoparticles showed a sustained release and the released tilmicosin had the same antibacterial activity as that of the free drug. Pharmacokinetics study after subcutaneous administration to Balb/c mice demonstrated that a single dose of tilmicosin-loaded nanoparticles resulted in sustained serum drug levels (>0.1 ,g/mL) for 8 days, as compared with only 5 h for the same amount of tilmicosin phosphate solution. The time to maximum concentration (Tmax), half-life of absorption (T˝ ab) and half-life of elimination (T˝ el) of tilmicosin-loaded nanoparticles were much longer than those of tilmicosin phosphate solution. Tissue section showed that drug-loaded nanoparticles caused no inflammation at the injection site. Cytotoxicity study in cell culture and acute toxicity test in mice demonstrated that the nanoparticles had little or no toxicity. The results of this exploratory study suggest that the HCO,SLN could be a useful system for the delivery of tilmicosin by subcutaneous administration. [source] Fluorescence of Sunscreens Adsorbed to Dielectric Nanospheres: Parallels to Optical Behavior on HaCat Cells and SkinPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 6 2006Rajagopal Krishnan Sunscreens applied to the skin are retained primarily in the stratum corneum, where they adsorb and act as a barrier preventing UV penetration to deeper layers. Photophysical properties of sunscreens have traditionally been studied either in solvents, which are very different from skin, or in skin or complex artificial skin systems, which are difficult to handle. The purpose of this study was to determine whether polystyrene nanospheres could serve as an improvement over solvents for evaluation of the photophysical properties of sunscreens without the presence of autofluorescence from and interactions with specific skin biomolecules. We used HaCat cells and excised skin for this comparative study with nanospheres. Fluorescence spectral properties of common hydrophobic sunscreens octyl salicylate, padimate O (2-ethylhexyl-4-dimethylaminobenzoate) and octyl methoxycinnamate adsorbed to 220 nm polystyrene spheres are similar to those of sunscreens adsorbed to HaCat cells and excised skin. Specifically, similarity in the emission peaks and their approximate positions, excitation peak positions and a measurable reduction in scattering upon sunscreen addition suggest that polystyrene nanospheres constitute a useful system to evaluate the photophysical properties of topical sunscreens and may serve as a model system for high-throughput evaluation of potential sunscreens. An unexpected result of this comparative study was the observation of an increase in a specific skin component emission caused by addition of padimate O. [source] Efficient Gene Expression System Using the RTP801 Promoter in the Corpus Cavernosum of High-Cholesterol Diet-Induced Erectile Dysfunction Rats for Gene TherapyTHE JOURNAL OF SEXUAL MEDICINE, Issue 6 2008Minhyung Lee PhD ABSTRACT Introduction., The application of gene therapy for a nonlife-threatening disease, such as erectile dysfunction (ED), requires a higher safety level and more efficacious systems for gene transfer. Aim., To establish a novel technique for gene expression in a rat model of hypercholesterolemic ED that uses the RTP801 promoter, a hypoxia-inducible promoter. Methods., Two-month-old male Sprague,Dawley rats were fed a diet containing 4% cholesterol and 1% cholic acid, and age-matched control animals were fed a normal diet, for 3 months. Main Outcome Measures., Cavernous expression of hypoxia-inducible factor (HIF)-1, was evaluated by Western blot. After intracavernous injection of pSV-Luc or pRTP801-Luc, gene expression was evaluated by luciferase assay, and the gene expression area was evaluated by immunohistochemistry. Results., HIF-1, was up-regulated in the corpus cavernosum of hypercholesterolemic rats. Although pSV-Luc did not induce gene expression in either the control or the cholesterol group, pRTP801-Luc significantly induced gene expression in the cholesterol group and resulted in higher luciferase activity than did pSV-Luc up to 14 days after injection. Immunohistochemistry showed that the gene expression area was also greater in the pRTP801-Luc group than in the pSV-Luc group, but the difference was not as great as that in luciferase activity. This suggests that pRTP801-Luc exerts its effect mainly by inducing promoter activity under hypoxia, not by increasing the number of transfected cells. Conclusion., The RTP801 promoter-driven gene expression system increased gene expression in the corpus cavernosum tissue of rats with cholesterol-induced ED. This may be a useful system for the development of gene therapy in vasculogenic ED. Lee M, Ryu J-K, Piao S, Choi MJ, Kim HA, Zhang L-W, Shin H-Y, Jung HI, Kim I-H, Kim SW, and Suh J-K. Efficient gene expression system using the RTP801 promoter in the corpus cavernosum of high-cholesterol diet-induced erectile dysfunction rats for gene therapy. J Sex Med 2008;5:1355,1364. [source] Improved secretion of molecular chaperone-assisted human IgG in silkworm, and no alterations in their N -linked glycan structuresBIOTECHNOLOGY PROGRESS, Issue 1 2010Takashi Dojima Abstract Human 29IJ6 IgG was expressed in silkworm using a Bombyx mori nucleopolyhedrovirus (BmNPV) bacmid system. The mean amounts of 296IJ6 IgG produced in larval hemolymph and whole pupae were 30.1 ,g/larva and 78.0 ,g/pupa, respectively. The use of molecular chaperones including calreticulin (CRT), calnexin (CNX), and immunoglobulin heavy chain binding protein (BiP, GRP78) improved the production of 296IJ6 IgG secretion in the larvae fivefold. The total yield of recombinant 29IJ6 IgG was 239 ,g/mL when coexpressed with CRT. However, the overexpression of molecular chaperones had negative effects on secretion. The N -linked glycans of secreted 296IJ6 IgG in silkworm hemolymph were dominated by paucimannose structures. Small amounts of GlcNAc residues linked to the Man,1,3 branch were detected. When molecular chaperones were coexpressed, the compositions of N -linked glycans in the IgG1 produced were unchanged compared with those produced without them. This suggests that N -glycosylation is controlled by a regulatory function in the Golgi apparatus even though the post-translational modification of 296IJ6 IgG was assisted by the coexpression of molecular chaperones. Therefore, if the glycosylation pathways that coexpress N -acetylglucosaminyltransferase, galactosyltransferase, and sialyltransferase could be improved, silkworm larvae might prove a useful system for producing human antibodies. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] Geographic variation in prey preference in bark beetle predatorsECOLOGICAL ENTOMOLOGY, Issue 2 2009JOHN D. REEVE Abstract 1.,Bark beetles and their predators are useful systems for addressing questions concerning diet breadth and prey preference in arthropod natural enemies. These predators use bark beetle pheromones to locate their prey, and the response to different pheromones is a measure of prey preference. 2.,Trapping experiments were conducted to examine geographic variation in the response to prey pheromones by two bark beetle predators, Thanasimus dubius and Temnochila virescens. The experiments used pheromones for several Dendroctonus and Ips prey species (frontalin, ipsdienol, and ipsenol) and manipulated visual cues involved in prey location (black vs. white traps). The study sites included regions where the frontalin-emitter Dendroctonus frontalis was in outbreak vs. endemic or absent. 3.,There was significant geographic variation in pheromone preference for T. dubius. This predator strongly preferred a pheromone (frontalin) associated with D. frontalis at outbreak sites, while preference was more even at endemic and absent sites. No geographic variation was found in the response by T. virescens. White traps caught fewer insects than black traps for both predators, suggesting that visual cues are also important in prey location. 4.,The overall pattern for T. dubius is consistent with switching or optimal foraging theory, assuming D. frontalis is a higher quality prey than Ips. The two predator species partition the prey pheromones in areas where D. frontalis is abundant, possibly to minimise competition and intraguild predation. [source] Herbivory influences tree linesJOURNAL OF ECOLOGY, Issue 6 2004DAVID M. CAIRNS Summary 1Transitions between major vegetation types, such as the tree line, are useful systems for monitoring the response of vegetation to climate change. Tree lines have, however, shown equivocal responses to such change. 2Tree lines are considered to be primarily thermally controlled, although recent work has highlighted the importance of biotic factors. Dispersal limitation and the invasibility of the tundra matrix have been implicated and here we propose herbivory as an additional control at some tree lines. 3We propose a conceptual model in which differing relative impacts of foliage consumption, availability of establishment sites, trampling, dispersal and seed predation can lead to very different tree-line responses. 4The presence of large numbers of small trees above the current tree line at a site in northern Sweden that experiences limited reindeer (Rangifer tarandus) herbivory suggests range expansion. Other locations in the same region with higher reindeer populations have considerably fewer small trees, suggesting that range expansion is occurring much more slowly, if at all. 5The use of tree lines as indicators of climate change is confounded by the activity of herbivores, which may either strengthen or nullify the impacts of a changed climate. Similar arguments are likely to be applicable to other ecotones. [source] Tracking island colonization history and phenotypic shifts in Indian Ocean bulbuls (Hypsipetes: Pycnonotidae)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2005BEN H. WARREN Molecular phylogenies of island organisms provide useful systems for testing hypotheses of convergent or parallel evolution, since selectively neutral molecular characters are likely to be independent of phenotype, and the existence of similar environments on multiple isolated islands provides numerous opportunities for populations to evolve independently under the same constraints. Here we construct a phylogenetic hypothesis for Hypsipetes bulbuls of the western Indian Ocean, and use this to test hypotheses of colonization pattern and phenotypic change among islands of the region. Mitochondrial sequence data were collected from all extant taxa of the region, combined with sequence data from relevant lineages in Asia. Data are consistent with a single Hypsipetes colonization of the western Indian Ocean from Asia within the last 2.6 Myr. The expansion of Hypsipetes appears to have occurred rapidly, with descendants found across the breadth of its western Indian Ocean range. The data suggest that a more recent expansion of Hypsipetes madagascariensis from Madagascar led to the colonization of Aldabra and a secondary colonization of the Comoros. Groupings of western Indian Ocean Hypsipetes according to phenotypic similarities do not correspond to mtDNA lineages, suggesting that these similarities have evolved by convergence or parallelism. The direction of phenotypic change cannot be inferred with confidence, since the primary expansion occurred rapidly relative to the rate of mtDNA substitution, and the colonization sequence remains uncertain. However, evidence from biogeography and comparison of independent colonization events are consistent with the persistence of a small grey continental bulbul in India and Madagascar, and multiple independent origins of large size and green plumage in insular island populations of the Comoros, Mascarenes and Seychelles. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 271,287. [source] | |||||||||||||