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  • 1
    Publication Date: 2012-10-12
    Description: Adoptive cell transfer therapies (ACTs) with cytotoxic T cells that target melanocytic antigens can achieve remissions in patients with metastatic melanomas, but tumours frequently relapse. Hypotheses explaining the acquired resistance to ACTs include the selection of antigen-deficient tumour cell variants and the induction of T-cell tolerance. However, the lack of appropriate experimental melanoma models has so far impeded clear insights into the underlying mechanisms. Here we establish an effective ACT protocol in a genetically engineered mouse melanoma model that recapitulates tumour regression, remission and relapse as seen in patients. We report the unexpected observation that melanomas acquire ACT resistance through an inflammation-induced reversible loss of melanocytic antigens. In serial transplantation experiments, melanoma cells switch between a differentiated and a dedifferentiated phenotype in response to T-cell-driven inflammatory stimuli. We identified the proinflammatory cytokine tumour necrosis factor (TNF)-alpha as a crucial factor that directly caused reversible dedifferentiation of mouse and human melanoma cells. Tumour cells exposed to TNF-alpha were poorly recognized by T cells specific for melanocytic antigens, whereas recognition by T cells specific for non-melanocytic antigens was unaffected or even increased. Our results demonstrate that the phenotypic plasticity of melanoma cells in an inflammatory microenvironment contributes to tumour relapse after initially successful T-cell immunotherapy. On the basis of our work, we propose that future ACT protocols should simultaneously target melanocytic and non-melanocytic antigens to ensure broad recognition of both differentiated and dedifferentiated melanoma cells, and include strategies to sustain T-cell effector functions by blocking immune-inhibitory mechanisms in the tumour microenvironment.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Landsberg, Jennifer -- Kohlmeyer, Judith -- Renn, Marcel -- Bald, Tobias -- Rogava, Meri -- Cron, Mira -- Fatho, Martina -- Lennerz, Volker -- Wolfel, Thomas -- Holzel, Michael -- Tuting, Thomas -- England -- Nature. 2012 Oct 18;490(7420):412-6. doi: 10.1038/nature11538. Epub 2012 Oct 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Experimental Dermatology, Department of Dermatology and Allergy, University of Bonn, D-53105 Bonn, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23051752" target="_blank"〉PubMed〈/a〉
    Keywords: Adoptive Transfer ; Animals ; *Cell Dedifferentiation ; Cell Differentiation ; Cell Line, Tumor ; Cell Proliferation/drug effects ; Disease Models, Animal ; Humans ; *Immunotherapy ; Inflammation/immunology/*pathology ; Melanoma/immunology/metabolism/*pathology/*therapy ; Mice ; Mice, Inbred C57BL ; Neoplasm Transplantation ; T-Lymphocytes, Cytotoxic/*immunology/*transplantation ; Tumor Microenvironment/immunology ; Tumor Necrosis Factor-alpha/immunology/pharmacology ; gp100 Melanoma Antigen/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2014-02-28
    Description: Intermittent intense ultraviolet (UV) exposure represents an important aetiological factor in the development of malignant melanoma. The ability of UV radiation to cause tumour-initiating DNA mutations in melanocytes is now firmly established, but how the microenvironmental effects of UV radiation influence melanoma pathogenesis is not fully understood. Here we report that repetitive UV exposure of primary cutaneous melanomas in a genetically engineered mouse model promotes metastatic progression, independent of its tumour-initiating effects. UV irradiation enhanced the expansion of tumour cells along abluminal blood vessel surfaces and increased the number of lung metastases. This effect depended on the recruitment and activation of neutrophils, initiated by the release of high mobility group box 1 (HMGB1) from UV-damaged epidermal keratinocytes and driven by Toll-like receptor 4 (TLR4). The UV-induced neutrophilic inflammatory response stimulated angiogenesis and promoted the ability of melanoma cells to migrate towards endothelial cells and use selective motility cues on their surfaces. Our results not only reveal how UV irradiation of epidermal keratinocytes is sensed by the innate immune system, but also show that the resulting inflammatory response catalyses reciprocal melanoma-endothelial cell interactions leading to perivascular invasion, a phenomenon originally described as angiotropism in human melanomas by histopathologists. Angiotropism represents a hitherto underappreciated mechanism of metastasis that also increases the likelihood of intravasation and haematogenous dissemination. Consistent with our findings, ulcerated primary human melanomas with abundant neutrophils and reactive angiogenesis frequently show angiotropism and a high risk for metastases. Our work indicates that targeting the inflammation-induced phenotypic plasticity of melanoma cells and their association with endothelial cells represent rational strategies to specifically interfere with metastatic progression.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Bald, Tobias -- Quast, Thomas -- Landsberg, Jennifer -- Rogava, Meri -- Glodde, Nicole -- Lopez-Ramos, Dorys -- Kohlmeyer, Judith -- Riesenberg, Stefanie -- van den Boorn-Konijnenberg, Debby -- Homig-Holzel, Cornelia -- Reuten, Raphael -- Schadow, Benjamin -- Weighardt, Heike -- Wenzel, Daniela -- Helfrich, Iris -- Schadendorf, Dirk -- Bloch, Wilhelm -- Bianchi, Marco E -- Lugassy, Claire -- Barnhill, Raymond L -- Koch, Manuel -- Fleischmann, Bernd K -- Forster, Irmgard -- Kastenmuller, Wolfgang -- Kolanus, Waldemar -- Holzel, Michael -- Gaffal, Evelyn -- Tuting, Thomas -- England -- Nature. 2014 Mar 6;507(7490):109-13. doi: 10.1038/nature13111. Epub 2014 Feb 26.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory of Experimental Dermatology, Department of Dermatology and Allergy, University of Bonn, 53115 Bonn, Germany. ; Molecular Immunology and Cell Biology, Life and Medical Sciences Institute, University of Bonn, 53115 Bonn, Germany. ; Unit for RNA Biology, Department of Clinical Chemistry and Clinical Pharmacology, University of Bonn, 53105 Bonn, Germany. ; Institute for Dental Research and Oral Musculoskeletal Biology, Center for Biochemistry, Medical Faculty, University of Cologne, D-50931 Cologne, Germany. ; Immunology and Environment, Life and Medical Sciences Institute, University of Bonn, 53115 Bonn, Germany. ; Institute for Physiology I, Life & Brain Center, University of Bonn, 53105 Bonn, Germany. ; Department of Dermatology, University Hospital Essen, 45122 Essen, Germany. ; Institute of Cardiovascular Research and Sport Medicine, Department of Molecular and Cellular Sport Medicine, German Sport University Cologne, 50933 Cologne, Germany. ; Division of Genetics and Cell Biology, San Raffaele University and Scientific Institute, 20132 Milan, Italy. ; Department of Pathology and Laboratory Medicine, Jonsson Comprehensive Cancer Center, University of California Los Angeles (UCLA) Medical Center, Los Angeles, California 90095, USA. ; Institutes of Molecular Medicine and Experimental Immunology, University of Bonn, 53105 Bonn, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24572365" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Cell Movement/radiation effects ; Cell Transformation, Neoplastic/radiation effects ; Disease Models, Animal ; Disease Progression ; Female ; HMGB1 Protein/metabolism ; Immunity, Innate/radiation effects ; Inflammation/*etiology ; Keratinocytes/metabolism/pathology/radiation effects ; Lung Neoplasms/blood supply/etiology/*secondary ; Male ; Melanocytes/pathology/radiation effects ; Melanoma/*blood supply/etiology/*pathology ; Mice ; Mice, Inbred C57BL ; Neovascularization, Pathologic/etiology ; Neutrophils/immunology/metabolism ; Skin Neoplasms/blood supply/etiology/*pathology ; Sunburn/complications/*etiology ; Toll-Like Receptor 4/metabolism ; *Ultraviolet Rays
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2013-08-06
    Description: The ABC toxin complexes produced by certain bacteria are of interest owing to their potent insecticidal activity and potential role in human disease. These complexes comprise at least three proteins (A, B and C), which must assemble to be fully toxic. The carboxy-terminal region of the C protein is the main cytotoxic component, and is poorly conserved between different toxin complexes. A general model of action has been proposed, in which the toxin complex binds to the cell surface via the A protein, is endocytosed, and subsequently forms a pH-triggered channel, allowing the translocation of C into the cytoplasm, where it can cause cytoskeletal disruption in both insect and mammalian cells. Toxin complexes have been visualized using single-particle electron microscopy, but no high-resolution structures of the components are available, and the role of the B protein in the mechanism of toxicity remains unknown. Here we report the three-dimensional structure of the complex formed between the B and C proteins, determined to 2.5 A by X-ray crystallography. These proteins assemble to form an unprecedented, large hollow structure that encapsulates and sequesters the cytotoxic, C-terminal region of the C protein like the shell of an egg. The shell is decorated on one end by a beta-propeller domain, which mediates attachment of the B-C heterodimer to the A protein in the native complex. The structure reveals how C auto-proteolyses when folded in complex with B. The C protein is the first example, to our knowledge, of a structure that contains rearrangement hotspot (RHS) repeats, and illustrates a marked structural architecture that is probably conserved across both this widely distributed bacterial protein family and the related eukaryotic tyrosine-aspartate (YD)-repeat-containing protein family, which includes the teneurins. The structure provides the first clues about the function of these protein repeat families, and suggests a generic mechanism for protein encapsulation and delivery.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Busby, Jason N -- Panjikar, Santosh -- Landsberg, Michael J -- Hurst, Mark R H -- Lott, J Shaun -- England -- Nature. 2013 Sep 26;501(7468):547-50. doi: 10.1038/nature12465. Epub 2013 Aug 4.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉AgResearch Structural Biology Laboratory, School of Biological Sciences, The University of Auckland, Auckland 1142, New Zealand.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23913273" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Motifs ; Amino Acid Sequence ; Bacterial Toxins/*chemistry/metabolism ; Consensus Sequence ; Conserved Sequence ; Crystallography, X-Ray ; Insecticides/chemistry ; Models, Molecular ; Molecular Sequence Data ; Protein Subunits/chemistry/metabolism ; Proteolysis ; *Repetitive Sequences, Amino Acid ; Yersinia/*chemistry
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Streptococcus agalactiae was isolated from cultured gilthead seabream, Sparus auratus L., and diseased wild Klunzinger's mullet, Liza klunzingeri (Day), in Kuwait Bay, Arabian Gulf. Isolates were catalase negative, β-haemolytic, Gram-positive cocci and serogroup B. Experimental infectivity trials with mullet and seabream brain isolates in Nile tilapia, Oreochromis niloticus L., caused 100 and 90% mortality, respectively, within 7 days post-inoculation indicating virulent S. agalactiae as the bacterial pathogen responsible for the epizootic in Kuwait Bay.
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Stomatal conductances (gs) were measured on the leaves of 3–4 year old Golden Delicious trees and of seedlings of two other cultivars. Measurements were made on container grown trees in the field with a diffusion porometer in 1975 and 1976, and in controlled conditions in a leaf chamber in the laboratory in 1976. Stomatal densities in the Golden Delicious leaves were assessed from scanning electron micrographs. Stomatal density on extension shoot leaves was higher than on other leaf types after June.The response to irradiance shown by both the porometer and the leaf chamber results could be described by a rectangular hyperbola: 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:01407791:PCE13:PCE_13_mu1"/〉where gmax is maximum conductance and β indicates the sensitivity of gs to photon influx density (Qp). The values of β were in the range 60–90 μmol m−2 s−1.There was no evidence that apple stomata are sensitive to temperature per se, but gs was reduced by increasing leaf to air vapour pressure deficits (D). There was a linear relationship between gs and D which was not attributable to feed-back to leaf water potential (ψL) as the latter did not affect gs until a threshold of about −2.0 to −2.5 MPa was reached. Conductance generally declined with increasing ambient CO2 concentration.
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. An empirical model of stomatal response to environmental factors was developed from measurements of stomatal conductance (gs) made in a leaf chamber under controlled conditions. Results presented in a companion paper (Warrit, Landsberg & Thorpe, 1980) indicated that the model could be written in terms of only two factors, photon flux density (Qp) and leaf to air vapour pressure gradient (D). The response of Qp was hyperbolic and that to D linear; combining these the equation of the model is〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:01407791:PCE23:PCE_23_mu1"/〉where gr is a reference conductance, α is the slope of the response to D and β indicates the sensitivity of gs response to Qp. Values of α were 0.20 and 0.30 kPa−1 in June and August; the corresponding values of β were 59 and 79 μmol m−2 s−1.The model was tested against mean values of gs obtained with a porometer in the field, using environmental measurements as inputs. Correspondence between measured and calculated values was good. Transpiration rates were calculated from the Penman-Monteith equation, with stomatal resistance values calculated from the model, and compared with gravimetric measurements of tree water use. It was shown that transpiration could be calculated with acceptable accuracy. The effects of variations in stomatal resistance on transpiration rates under a range of conditions were explored using the model and the Penman- Monteith equation.
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 1 (1978), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Using an open-system leaf chamber, gas exchange measurements on attached leaves of 3-4-year-old Golden Delicious apple trees, made through two seasons, provided data from which the parameters of a leaf photosynthesis model could be derived. The equation is: 〈displayedItem type="mathematics" xml:id="mu1" numbered="no"〉〈mediaResource alt="image" href="urn:x-wiley:01407791:PCE51:PCE_51_mu1"/〉where C1 is internal CO2 concentration and Qp is the incident quantum flux. There was considerable leaf to leaf variation in the values of the parameters but no clear seasonal trends were established. The initial slope (a) had an average value of about 2.5 × 10−3 mg μmol−1† (i.e. quantum yield ∼ 0.057); the mesophyll conductance (gm) was about 3.5 mm s−1 in extension leaves of trees carrying fruit and 2.5 mm s−1 in extension leaves of defruited trees. Differences between the values of gm for spur leaves with and without subtending fruits were not significant; 2.5 mm s−1 may be used. Dark respiration (Rd, mg m−2 s−1) increased exponentially with temperature (T°C); Rd∼ 0.006 exp (0.09 T). At saturating photon flux density Pn was linearly related to Ci, up to Ci∼ 250 mg m−3. Optimum temperatures for Pn were slightly different in the two years and were in the range 16-26°C.
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing
    Plant, cell & environment 5 (1982), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 4 (1981), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Measurements of the efflux of CO2 from 5–6 year old container grown apple trees, in the dark at a range of temperatures (T), indicated that respiration rate (R) can be described by the equation R = SL e kT. The temperature coefficient k, was the same at all times of the year and for all components of the trees, but the values of a varied. At the same temperature respiration rates were low when the trees were dormant, rose rapidly to a peak in spring (before full bloom) and then declined steadily through the season. When respiration was expressed as a flux density, rates for different components of the tree were usually similar. Differences were sometimes statistically significant but no clear pattern emerged. The results obtained are similar to those published for other plants and the equation can be used in the calculation of the carbon balance of apple trees.
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  • 10
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 3 (1980), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. Transpiration rates from apple leaves are analysed in terms of the ratio of latent heat flux (λE) to leaf net radiation (Q1) and the climatological resistance (ri). Increases in stomatal resistance with increasing leaf to air vapour pressure gradient (D), described by an empirical model, are incorporated in the analysis. This humidity effect causes the proportion of energy dissipated as latent heat to fall as Q1 increases, so that leaf transpiration rates in high energy environments are likely to be similar to those in lower energy environments. Boundary layer resistance (ra) exerts an increasingly important effect on transpiration rates as Q1 increases. At constant Q1 stomatal closure in response to increasing D results in very small changes in leaf temperature (T1) across a wide range of ambient vapour pressure deficits (δe); ra is then the major factor determining T1. The implications of these results are discussed.
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