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排序方式: 共有401条查询结果,搜索用时 62 毫秒
101.
Ettore Murabito Evangelos Simeonidis Kieran Smallbone Jonathan Swinton 《Journal of theoretical biology》2009,260(3):445-452
As genome-scale metabolic reconstructions emerge, tools to manage their size and complexity will be increasingly important. Flux balance analysis (FBA) is a constraint-based approach widely used to study the metabolic capabilities of cellular or subcellular systems. FBA problems are highly underdetermined and many different phenotypes can satisfy any set of constraints through which the metabolic system is represented.Two of the main concerns in FBA are exploring the space of solutions for a given metabolic network and finding a specific phenotype which is representative for a given task such as maximal growth rate. Here, we introduce a recursive algorithm suitable for overcoming both of these concerns. The method proposed is able to find the alternate optimal patterns of active reactions of an FBA problem and identify the minimal subnetwork able to perform a specific task as optimally as the whole.Our method represents an alternative to and an extension of other approaches conceived for exploring the space of solutions of an FBA problem. It may also be particularly helpful in defining a scaffold of reactions upon which to build up a dynamic model, when the important pathways of the system have not yet been well-defined. 相似文献
102.
Evangelos J. Giamarellos-Bourboulis Maria Raftogiannis Anastasia Antonopoulou Fotini Baziaka Pantelis Koutoukas Athina Savva Theodora Kanni Marianna Georgitsi Aikaterini Pistiki Thomas Tsaganos Nikolaos Pelekanos Sofia Athanassia Labrini Galani Efthymia Giannitsioti Dimitra Kavatha Flora Kontopidou Maria Mouktaroudi Garyfallia Poulakou Vissaria Sakka Periklis Panagopoulos Antonios Papadopoulos Kyriaki Kanellakopoulou Helen Giamarellou 《PloS one》2009,4(12)
Background
The pandemic by the novel H1N1 virus has created the need to study any probable effects of that infection in the immune system of the host.Methodology/Principal Findings
Blood was sampled within the first two days of the presentation of signs of infection from 10 healthy volunteers; from 18 cases of flu-like syndrome; and from 31 cases of infection by H1N1 confirmed by reverse RT-PCR. Absolute counts of subtypes of monocytes and of lymphocytes were determined after staining with monoclonal antibodies and analysis by flow cytometry. Peripheral blood mononuclear cells (PBMCs) were isolated from patients and stimulated with various bacterial stimuli. Concentrations of tumour necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-18, interferon (FN)-alpha and of IFN-gamma were estimated in supernatants by an enzyme immunoassay. Infection by H1N1 was accompanied by an increase of monocytes. PBMCs of patients evoked strong cytokine production after stimulation with most of bacterial stimuli. Defective cytokine responses were shown in response to stimulation with phytohemagglutin and with heat-killed Streptococcus pneumoniae. Adaptive immune responses of H1N1-infected patients were characterized by decreases of CD4-lymphocytes and of B-lymphocytes and by increase of T-regulatory lymphocytes (Tregs).Conclusions/Significance
Infection by the H1N1 virus is accompanied by a characteristic impairment of the innate immune responses characterized by defective cytokine responses to S.pneumoniae. Alterations of the adaptive immune responses are predominated by increase of Tregs. These findings signify a predisposition for pneumococcal infections after infection by H1N1 influenza. 相似文献103.
John Panelos Spyridon Voulgaris Evangelos Michos Michael Doukas Konstantinos Charalabopoulos Anna Batistatou 《Diagnostic pathology》2006,1(1):1-5
Background
TMAs are becoming a useful tool for research and quality control methods, mostly for immunohistochemistry and in situ hybridization.Methods
A new technique that allows building TMA blocks with more than 300 tissue cores without using a recipient paraffin block for the tissue cores and without using a commercial TMA builder instrument is described. This technique is based on the construction of TMA needles modifying conventional hypodermic needles to punch tissue cores from donor blocks, which are attached by double-side adhesive tape on a computer-generated paper grid used to align the cores on the block mould, which is filled with liquid paraffin.Results
More than two hundred TMA blocks were constructed using this method, utilized in immunohistochemistry and histochemistry as positive and negative controls and also in research.Conclusion
This technique has the following advantages: it is easy to reproduce, affordable, quick and creates uniform blocks with more than 300 cores aligned, adherent and easy to cut, with negligible losses during cutting and immunohistochemistry and in situ hybridization procedures. 相似文献104.
Papagrigoriou E McEwan PA Walsh PN Emsley J 《Nature structural & molecular biology》2006,13(6):557-558
Factor XI (FXI), a coagulation protein essential to normal hemostasis, circulates as a disulfide-linked dimer. Here we report the full-length FXI zymogen crystal structure, revealing that the protease and four apple domains assemble into a unique 'cup and saucer' architecture. The structure shows that the thrombin and platelet glycoprotein Ib binding sites are remote within the monomer but lie in close proximity across the dimer, suggesting a transactivation mechanism. 相似文献
105.
Kouloukoussa M Aleporou-Marinou V Angelopoulou B Trougakos IP Panagopoulou E Kittas C Marinos E 《Tissue & cell》2004,36(2):149-155
Actin and vinculin are two of the most abundant cytoskeletal proteins, widely expressed in nearly all types of eukaryotic cells. It has been well established that long-term exposure to the tumor promoter phorbol myristate acetate (PMA) affects Sertoli cell morphology, as well as F-actin and vinculin organization in vitro. To analyze in a quantitative manner the F-actin and vinculin content of rat immature Sertoli cells in vitro in response to PMA exposure, cytoskeletal fractions were prepared following extraction with Triton X-100. Analysis of the isolated cytoskeletal fractions by immunoblotting showed that exposure of immature rat Sertoli cells to PMA for 8h has an appreciable effect on the cellular level of both the actin and vinculin. Interestingly, as revealed by using calphostin C, a specific protein kinase C inhibitor, the observed F-actin and vinculin changes are most probably mediated by a mechanism that depends on protein kinase activity. A discussion is made concerning PKC modulation by PMA and the subsequent actin and vinculin quantitative changes and reorganization, phenomena that have been closely related to cell transformation. 相似文献
106.
Mohamad M. Abou Auda Lazaros Symeonidis Evangelos Hatzistavrou Traianos Yupsanis 《Journal of plant physiology》2002,159(10):1087
Serpentine and non-serpentine plants of Alyssum murale, a nickel (Ni) accumulator plant, from North Greece, were studied in order to examine: (1) The ability of natural plants to accumulate metals; (2) the ability of their seedlings to tolerate increasing concentrations of Ni2+ or Mn2+ (0, 0.16, 0.32, 0.5 and 1 mmol/L), when grown in nutrient solution; (3) the activities and electrophoretic patterns of root and shoot DNases and RNases under the above conditions. Measurements of metal concentrations in serpentine and non-serpentine natural plants and the respective soils revealed: (1) Very low calcium (Ca)/magnesium (Mg) (0.16) ratio and high concentration of Ni in serpentine soil; (2) very high Ca/Mg (17) ratio and high concentration of manganese (Mn) in non-serpentine soil; (3) the ability of serpentine natural plants to accumulate Ni and the inability of plants of both serpentine and non-serpentine populations to accumulate Mn. A. murale plants grown in nutrient solution with increasing Ni2+ or Mn2+ concentrations showed a negative correlation between the Ni2+ or Mn2+ concentrations in the nutrient solution, and the chlorophyll concentration, shoot and especially root length. The accumulation of Ni2+ or Mn2+ in the plant showed a positive correlation with increasing Ni2+ or Mn2+ concentrations in the nutrient solution. Application of 0.5 mmol/L Ni2+ or Mn2+ resulted in the inhibition of DNase activities and the appearance of a new DNase form, in both root and shoot detected by electrophoresis in active ssDNA polyacrylamide gel. The new gel-extracted DNase showed nicking action against plasmid DNA and has been characterised as an endo-DNase. In contrast, electrophoretic patterns and RNase activities were unaffected. According to our studies on growth, both serpentine and non-serpentine plants of A. murale have a constitutive ability to tolerate and accumulate Ni2+ or Mn2+; they have similar DNase and RNase electrophoretic patterns and show a new DNase form under Ni2+ or Mn2+ stress. This is the first report on the response of nucleolytic enzymes under metallic elements hyperaccumulation. 相似文献
107.
Estimating Photosynthesis and Concurrent Export Rates in
C3 and C4 Species at Ambient and Elevated
CO2 总被引:2,自引:0,他引:2
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The ability of 21 C3 and C4 monocot and dicot species to rapidly export newly fixed C in the light at both ambient and enriched CO2 levels was compared. Photosynthesis and concurrent export rates were estimated during isotopic equilibrium of the transport sugars using a steady-state 14CO2-labeling procedure. At ambient CO2 photosynthesis and export rates for C3 species were 5 to 15 and 1 to 10 μmol C m−2 s−1, respectively, and 20 to 30 and 15 to 22 μmol C m−2 s−1, respectively, for C4 species. A linear regression plot of export on photosynthesis rate of all species had a correlation coefficient of 0.87. When concurrent export was expressed as a percentage of photosynthesis, several C3 dicots that produced transport sugars other than Suc had high efflux rates relative to photosynthesis, comparable to those of C4 species. At high CO2 photosynthetic and export rates were only slightly altered in C4 species, and photosynthesis increased but export rates did not in all C3 species. The C3 species that had high efflux rates relative to photosynthesis at ambient CO2 exported at rates comparable to those of C4 species on both an absolute basis and as a percentage of photosynthesis. At ambient CO2 there were strong linear relationships between photosynthesis, sugar synthesis, and concurrent export. However, at high CO2 the relationships between photosynthesis and export rate and between sugar synthesis and export rate were not as strong because sugars and starch were accumulated. 相似文献
108.
Evangelos P. Zafeiris George C. Babis Christos P. Zafeiris Efstathios Chronopoulos 《Journal of musculoskeletal & neuronal interactions》2021,21(4):509
Objectives:The aim of this study was to analyze the association of knee OA with bone mineral density (BMD) and vitamin D serum levels in postmenopausal women.Methods:A cross-sectional study including 240 postmenopausal women with knee OA was conducted. Demographic data were recorded along with balance and functionality scores. Knee OA severity was assessed by the radiological Kellgren & Lawrence scale. BMD and T-scores were calculated in hips and lumbar spine. Serum levels of vitamin D were also measured.Results:High BMI (p<0.005), high number of children (p=0.022) and family history of hip fracture (p=0.011) are significantly associated with knee OA severity. Lumbar spine OP is negatively associated with knee OA (p<0.005). A significant difference was detected between vitamin D deficiency and severe knee OA, adjusted for BMD [OR (95%CI); 3.1 (1.6-6.1), p=0.001]. BMD does not affect the relationship of vitamin D levels in relation to OA and vitamin D levels do not affect the relationship of BMD with OA.Conclusions:Low BMD has a protective role against knee OA while vitamin D deficiency contributes significantly to knee OA severity. However, the association between OA and OP is not affected by vitamin D deficiency and the association of OA and vitamin D serum levels is not affected by BMD. 相似文献
109.
Kontargiris E Kolettas E Vadalouca A Trougakos IP Gonos ES Kalfakakou V 《Cell research》2004,14(5):415-422
Local anesthetics inhibit cell proliferation and induce apoptosis in various cell types. Ropivacaine, a unique, novel tertiary amine-type anesthetic, was shown to inhibit the proliferation of several cell types including keratinocytes. We found that Ropivacaine could inhibit the proliferation and induce apoptosis in an immortalized human keratinocyte line,HaCaT, in a dose- and time-dependent manner and with the deprivation of serum. The dose-dependent induction of apoptosis by ropivacaine was demonstrated by DNA fragmentation analysis and the proteolytic cleavage of a caspase-3 substrate—poly (ADP-ribose) polymerase (PARP). In addition, ropivacaine downregulated the expression of clusterin/ apoliporotein J, a protein with anti-apoptotic properties, in a dose-dependent manner, which well correlated with the induction of apoptosis of HaCaT cells. To investigate the role of clusterin/apoliporotein J in ropivacaine-induced apoptosis,HaCaT cells overexpressing clusterin/apoliporotein J were generated and compared to cells expressing the well established anti-apoptotic Bcl-2 protein. Ectopic overexpression of the secreted form of clusterin/apoliporotein J or Bcl-2decreased the sensitivity of HaCaT cells to toxic effects of ropivacaine as demonstrated by DNA fragmentation, the proteolytic cleavage of PARP and by a reduction in procaspase-3 expression. Furthermore, the downregulation of endogenous clusterin/apolipoprotein J levels by ropivacaine suggested that this might be one mechanism by which ropivacaine induced cell death in HaCaT cells. In conclusion, the ability of ropivacaine to induce antiproliferative responses and to suppress the expression of the anti-apoptotic protein clusterin/apolipoprotein J, combined with previously reported anti-inflammatory activity and analgesic property of the drug, suggests that ropivacaine may have potential utility in the local treatment of tumors. 相似文献
110.
Nahm WK Philpot BD Adams MM Badiavas EV Zhou LH Butmarc J Bear MF Falanga V 《Journal of cellular physiology》2004,200(2):309-317
Increasing data suggest that glutamate might act as a cell-signaling molecule in non-neuronal tissues such as the skin. Here we demonstrate the presence of functional N-methyl-D-aspartate (NMDA)-type glutamate receptors in human keratinocytes. NMDA receptor expression strongly reflects the degree of cell-to-cell contact. Wounding polarizes the expression of NMDA receptors in keratinocytes involved in re-epithelialization, and the process of re-epithelialization is inhibited by NMDA receptor activation. We also demonstrate that squamous cell carcinomas lack NMDA receptors. Our data suggest that Ca2+ entry through NMDA receptors influences the cycle of keratinocyte proliferation, differentiation, and migration during epithelialization. Moreover, NMDA receptor activation might play a role in contact-mediated inhibition of growth, a process that is absent during neoplastic pathology. This receptor may serve as a pharmacological target for modulating keratinocyte behavior and treating cutaneous disorders. 相似文献