Floral temperature and optimal foraging: is heat a feasible floral reward for pollinators?

As well as nutritional rewards, some plants also reward ectothermic pollinators with warmth. Bumble bees have some control over their temperature, but have been shown to forage at warmer flowers when given a choice, suggesting that there is some advantage to them of foraging at warm flowers (such as reducing the energy required to raise their body to flight temperature before leaving the flower). We describe a model that considers how a heat reward affects the foraging behaviour in a thermogenic central-place forager (such as a bumble bee). We show that although the pollinator should spend a longer time on individual flowers if they are warm, the increase in total visit time is likely to be small. The pollinator's net rate of energy gain will be increased by landing on warmer flowers. Therefore, if a plant provides a heat reward, it could reduce the amount of nectar it produces, whilst still providing its pollinator with the same net rate of gain. We suggest how heat rewards may link with plant life history strategies

Coronary plaque composition as assessed by greyscale intravascular ultrasound and radiofrequency spectral data analysis

Objectives: (i) To explore the relation between greyscale intravascular ultrasound (IVUS) plaque qualitative classification and IVUS radiofrequency data (RFD) analysis tissue types; (ii) to evaluate if plaque composition as assessed by RFD analysis can be predicted by visual assessment of greyscale IVUS images. Methods: In 120 IVUS-RFD cross-sections, a sector of the plaque with homogenous tissue composition (e.g., fibrous, fibrofatty, necrotic core, and dense calcium) was selected. Two experienced observers analyzed twice the corresponding greyscale IVUS images to: (1) classify the selected sectors according to greyscale IVUS plaque type classification and (2) predict the tissue type expected in the sector by RFD analysis. Results: In the greyscale IVUS plaque type classification, the observers agreed in 90/120 sectors (κ = 0.64). Calcified, soft and mixed plaques by greyscale IVUS classification were mainly composed of dense calcium, fibrofatty, and necrotic core, respectively, in the RFD analysis. The plaques classified in greyscale IVUS as fibrous were actually fibrous tissue by IVUS RFD in only 30% of the cases. Overall, high interobserver variability in the prediction of RFD results by visual assessment of greyscale IVUS images (κ = 0.23 for observer 1 and 0.55 for observer 2) was found. Sens

Stationary Black Holes: Uniqueness and Beyond

The spectrum of known black-hole solutions to the stationary Einstein equations has been steadily increasing, sometimes in unexpected ways. In particular, it has turned out that not all black-hole-equilibrium configurations are characterized by their mass, angular momentum and global charges. Moreover, the high degree of symmetry displayed by vacuum and electro-vacuum black-hole spacetimes ceases to exist in self-gravitating non-linear field theories. This text aims to review some developments in the subject and to discuss them in light of the uniqueness theorem for the Einstein-Maxwell system.Comment: Major update of the original version by Markus Heusler from 1998. Piotr T. Chru\'sciel and Jo\~ao Lopes Costa succeeded to this review's authorship. Significantly restructured and updated all sections; changes are too numerous to be usefully described here. The number of references increased from 186 to 32

Role of tumor size in the pre-operative management of rectal cancer patients

Clinical management of rectal cancer patients relies on pre-operative staging. Studies however continue to report moderate degrees of over/understaging as well as inter-observer variability. The aim of this study was to determine the sensitivity, specificity and accuracy of tumor size for predicting T and N stages in pre-operatively untreated rectal cancers

The Effect of Enzymatically Polymerised Polyphenols on CD4 Binding and Cytokine Production in Murine Splenocytes

High-molecular weight polymerised polyphenols have been shown to exhibit anti-influenza virus, anti-HIV, and anti-cancer activities. The purpose of this study was to evaluate the immunomodulating activities of enzymatically polymerised polyphenols, and to clarify the underlying mechanisms of their effects. The cytokine-inducing activity of the enzymatically polymerised polyphenols derived from caffeic acid (CA), ferulic acid (FA), and p-coumaric acid (CoA) was investigated using murine splenocytes. Polymerised polyphenols, but not non-polymerised polyphenols, induced cytokine synthesis in murine splenocytes. Polymerised polyphenols induced several cytokines in murine splenocytes, with interferon-γ (IFN-γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) being the most prominent. The underlying mechanisms of the effects of the polymerised polyphenols were then studied using neutralising antibodies and fluorescent-activated cell sorting (FACS) analysis. Our results show that polymerised polyphenols increased IFN-γ and GM-CSF production in splenocytes. In addition, the anti-CD4 neutralised monoclonal antibody (mAb) inhibited polymerised polyphenol-induced IFN-γ and GM-CSF secretion. Moreover, polymerised polyphenols bound directly to a recombinant CD4 protein, and FACS analysis confirmed that interaction occurs between polymerised polyphenols and CD4 molecules expressed on the cell surface. In this study, we clearly demonstrated that enzymatic polymerisation confers immunoactivating potential to phenylpropanoic acids, and CD4 plays a key role in their cytokine-inducing activity

Blechnum Orientale Linn - a fern with potential as antioxidant, anticancer and antibacterial agent

<p>Abstract</p> <p>Background</p> <p><it>Blechnum orientale </it>Linn. (<it>Blechnaceae</it>) is used ethnomedicinally for the treatment of various skin diseases, stomach pain, urinary bladder complaints and sterilization of women. The aim of the study was to evaluate antioxidant, anticancer and antibacterial activity of five solvent fractions obtained from the methanol extract of the leaves of <it>Blechnum orientale </it>Linn.</p> <p>Methods</p> <p>Five solvent fractions were obtained from the methanol extract of <it>B. orientale</it> through successive partitioning with petroleum ether, chloroform, ethyl acetate, butanol and water. Total phenolic content was assessed using Folin-Ciocalteu's method. The antioxidant activity was determined by measuring the scavenging activity of DPPH radicals. Cytotoxic activity was tested against four cancer cell lines and a non-malignant cell using MTT assay. Antibacterial activity was assessed using the disc diffusion and broth microdilution assays. Standard phytochemical screening tests for saponins, tannins, terpenoids, flavonoids and alkaloids were also conducted.</p> <p>Results</p> <p>The ethyl acetate, butanol and water fractions possessed strong radical scavenging activity (IC₅₀8.6-13.0 μg/ml) and cytotoxic activity towards human colon cancer cell HT-29 (IC₅₀27.5-42.8 μg/ml). The three extracts were also effective against all Gram-positive bacteria tested: <it>Bacillus cereus, Micrococcus luteus</it>, methicillin-susceptible <it>Staphylococcus aureus </it>(MSSA), methicillin-resistant <it>Staphylococcus aureus </it>(MRSA) and <it>Stapylococcus epidermidis</it>(minimum inhibitory concentration MIC 15.6-250 μg/ml; minimum bactericidal concentration MBC 15.6-250 μg/ml). Phytochemical analysis revealed the presence of flavonoids, terpenoids and tannins. Ethyl acetate and butanol fractions showed highest total phenolic content (675-804 mg gallic acid equivalent/g).</p> <p>Conclusions</p> <p>The results indicate that this fern is a potential candidate to be used as an antioxidant agent, for colon cancer therapy and for treatment of MRSA infections and other MSSA/Gram-positive bacterial infectious diseases.</p

Knockdown of STAT3 expression by RNAi induces apoptosis in astrocytoma cells

BACKGROUND: Astrocytomas are the most common type of primary central nervous system tumors. They are frequently associated with genetic mutations that deregulate cell cycle and render these tumors resistant to apoptosis. STAT3, signal transducer and activator of transcription 3, participates in several human cancers by inducing cell proliferation and inhibiting apoptosis and is frequently activated in astrocytomas. METHODS: RNA interference was used to knockdown STAT3 expression in human astrocytes and astrocytoma cell lines. The effect of STAT3 knockdown on apoptosis, cell proliferation, and gene expression was then assessed by standard methods. RESULTS: We have found that STAT3 is constitutively activated in several human astrocytoma cell lines. Knockdown of STAT3 expression by siRNA induces morphologic and biochemical changes consistent with apoptosis in several astrocytoma cell lines, but not in primary human astrocytes. Moreover, STAT3 is required for the expression of the antiapoptotic genes survivin and Bcl-xL in the A172 glioblastoma cell line. CONCLUSION: These results show that STAT3 is required for the survival of some astrocytomas. These studies suggest STAT3 siRNA could be a useful therapeutic agent for the treatment of astrocytomas

Analysis of the 10q23 chromosomal region and the PTEN gene in human sporadic breast carcinoma

We examined a panel of sporadic breast carcinomas for loss of heterozygosity (LOH) in a 10-cM interval on chromosome 10 known to encompass the PTEN gene. We detected allele loss in 27 of 70 breast tumour DNAs. Fifteen of these showed loss limited to a subregion of the area studied. The most commonly deleted region was flanked by D10S215 and D10S541 and encompasses the PTEN locus. We used a combination of denaturing gradient gel electrophoresis and single-strand conformation polymorphism analyses to investigate the presence of PTEN mutations in tumours with LOH in this region. We did not detect mutations of PTEN in any of these tumours. Our data show that, in sporadic breast carcinoma, loss of heterozygosity of the PTEN locus is frequent, but mutation of PTEN is not. These results are consistent with loss of another unidentified tumour suppressor in this region in sporadic breast carcinoma. © 1999 Cancer Research Campaig

Proteomic characterization of HIV-modulated membrane receptors, kinases and signaling proteins involved in novel angiogenic pathways

<p>Abstract</p> <p>Background</p> <p>Kaposi's sarcoma (KS), hemangioma, and other angioproliferative diseases are highly prevalent in HIV-infected individuals. While KS is etiologically linked to the human herpesvirus-8 (HHV8) infection, HIV-patients without HHV-8 and those infected with unrelated viruses also develop angiopathies. Further, HIV-Tat can activate protein-tyrosine-kinase (PTK-activity) of the vascular endothelial growth factor receptor involved in stimulating angiogenic processes. However, Tat by itself or HHV8-genes alone cannot induce angiogenesis <it>in vivo </it>unless specific proteins/enzymes are produced synchronously by different cell-types. We therefore tested a hypothesis that <it>chronic </it>HIV-<it>replication in non-endothelial cells </it>may produce novel factors that provoke angiogenic pathways.</p> <p>Methods</p> <p>Genome-wide proteins from HIV-infected and uninfected T-lymphocytes were tested by subtractive proteomics analyses at various stages of virus and cell growth <it>in vitro </it>over a period of two years. Several thousand differentially regulated proteins were identified by mass spectrometry (MS) and >200 proteins were confirmed in multiple gels. Each protein was scrutinized extensively by protein-interaction-pathways, bioinformatics, and statistical analyses.</p> <p>Results</p> <p>By functional categorization, 31 proteins were identified to be associated with various signaling events involved in angiogenesis. 88% proteins were located in the plasma membrane or extracellular matrix and >90% were found to be essential for regeneration, neovascularization and angiogenic processes during embryonic development.</p> <p>Conclusion</p> <p>Chronic HIV-infection of T-cells produces membrane receptor-PTKs, serine-threonine kinases, growth factors, adhesion molecules and many diffusible signaling proteins that have not been previously reported in HIV-infected cells. Each protein has been associated with endothelial cell-growth, morphogenesis, sprouting, microvessel-formation and other biological processes involved in angiogenesis (p = 10^-4to 10^-12). Bioinformatics analyses suggest that overproduction of PTKs and other kinases in HIV-infected cells has <it>suppressed </it>VEGF/VEGFR-PTK expression and promoted <it>VEGFR-independent </it>pathways. This unique mechanism is similar to that observed in neovascularization and angiogenesis during embryogenesis. Validation of clinically relevant proteins by gene-silencing and translational studies <it>in vivo </it>would identify specific targets that can be used for early diagnosis of angiogenic disorders and future development of inhibitors of angiopathies. This is the first comprehensive study to demonstrate that HIV-infection alone, without any co-infection or treatment, can induce numerous "embryonic" proteins and kinases capable of generating novel <it>VEGF-independent </it>angiogenic pathways.</p