14,176 research outputs found

    Chemokine-induced secretion of gelatinase B in primary human monocytes

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    Chemokines help control normal leukocyte trafficking as well as their infiltration into tissues during acute and chronic inflammation. Matrix metalloproteinases (MMPs) help support the extravasation and infiltration of leukocytes through limited proteolysis of basement membranes and matrix material. The effect of the chemokines RANTES/CCL5, MCP-1/CCL and SDF-1 /CXCL12 on secretion of the matrix metalloproteinase B and its endogenous inhibitor TIMP-1 was studied. RANTES/CCL5 and SDF-1/CXCL12 were found to induce MMP-9 secretion in primary human monocytes while TIMP-1 secretion was not affected. RANTES/CCL5 effects were mediated through CCR1 because the CCR1 antagonist BX471 was found to effectively block RANTES/CCL5-induced MMP-9 secretion

    On the Existence of the Quantum Action

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    We have previously proposed a conjecture stating that quantum mechanical transition amplitudes can be parametrized in terms of a quantum action. Here we give a proof of the conjecture and establish the existance of a local quantum action in the case of imaginary time in the Feynman-Kac limit (when temperature goes to zero). Moreover we discuss some symmetry properties of the quantum action.Comment: revised version, Text (LaTeX

    Chemical chronology of the Southern Coalsack

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    We demonstrate how the observed H2O ice column densities toward three dense globules in the Southern Coalsack could be used to constrain the ages of these sources. We derive ages of ~10^5 yr, in agreement with dynamical studies of these objects. We have modelled the chemical evolution of the globules, and show how the molecular abundances are controlled by both the gas density and the initial chemical conditions as the globules formed. Based on our derived ages, we predict the column densities of several species of interest. These predictions should be straightforward to test by performing molecular line observationsComment: 10 pages, 4 figures, in press at MNRA

    Bryophytes of Uganda : 2., new and interesting records

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    51 hepatics and 46 mosses are reported new to Uganda, including one moss new to Africa, one hepatic and two mosses new to mainland Africa, and 2 hepatics that are otherwise known only from their type collection

    The calpastatin-derived calpain inhibitor CP1B reduces mRNA expression of matrix metalloproteinase-2 and-9 and invasion by leukemic THP-1 cells

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    The ubiquitous proteases ÎĽ- and m-calpain are Ca2+-dependent cysteine endopeptidases. Besides involvement in a variety of physio(patho)logical processes, recent studies suggest a pivotal role of calpains in differentiation of hematopoietic cells and tumor cell invasion. However, the precise actions of calpains and their endogenous inhibitor, calpastatin, in these processes are only partially understood. Here we have studied the role of the calpain/calpastatin system in the invasion of leukemic cells under basal and differentiationstimulating conditions. To further differentiate the human leukaemic cell line THP-1 (monocytic), the cells were treated for 24 hours with the differentiationstimulating reagents phorbol 12-myristate 13-acetate (PMA) and dimethyl sulfoxide (DMSO). Macrophage and granulocytelike differentiation was confirmed by induction of vimentin expression as well as by microscopic and fluorescence assisted cytometric analysis. Extracellular matrix (ECM) invasion of both the basal and differentiation stimulated cells in a Matrigel assay was inhibited by preincubation of the cells with the specific calpain inhibitor CP1B for 24 hours. Inhibition of invasiveness correlated with decreased mRNA expression and secretion of the matrix metalloproteinases MMP-2 and MMP-9. In contrast, addition of CP1B only during the invasion process did neither influence transmigration nor MMP release. This is the first report showing that the calpain/calpastatin system mediates MMPmRNA expression of the leukemic THP-1 cells and as a consequence their invasiveness

    Simulation studies of air transport operational problems

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    An experimental evaluation of the monitored approach procedure for conducting low visibility instrument approaches is described. Four airline crews each flew 16 approaches using the monitored procedure and 16 using a modified standard procedure in a DC-10 simulator under various conditions of visibility, wind shear and turbulence, and radar vectoring scenarios. In terms of system measures of aircrew performance, no major differences were found. Pilot opinion data indicate that there are some desirable characteristics of the monitored procedure, particularly with reference to the increased role of the flight engineer in conducting low visibility approaches. Rationale for developing approach procedures is discussed

    Selecting and preparing seed corn.

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    The following circular has been prepared in answer to the many letters which are being received daily asking for information regarding the purchasing and testing of seed corn and its preparation for planting. When we consider that more than nine million acres, considerably over one-fourth of the entire area of the state, will be planted to corn the coming season and that it will require more than 1,300,000 bushels of seed to plant this area; and when we realize that the character of the seed, its vitality, breeding, purity, adaptability to the soil and climate and uniformity in both size and shape of kernels, all exercise a great influence on the future yield, the great importance of paying the closest attention to the testing and the preparation of the seed corn for the planter cannot be over estimated

    The mass gap and vacuum energy of the Gross-Neveu model via the 2PPI expansion

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    We introduce the 2PPI (2-point-particle-irreducible) expansion, which sums bubble graphs to all orders. We prove the renormalizibility of this summation. We use it on the Gross-Neveu model to calculate the mass gap and vacuum energy. After an optimization of the expansion, the final results are qualitatively good.Comment: 14 pages,19 eps figures, revtex

    The principal soil areas of Iowa

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    All the soils of Iowa without exception are, in respect to their origin, referable to one or the other of four easily distinguishable classes, which, are to be found in plainly marked areas. These are: 1. Geest, or soils resulting from the secular decay of indurated rocks. 2. Soils Of Fluviatile Origin, or stream made soils (alluvium). 3. Soils Of Aeolian Origin, or wind made soils (loess). 4. Soils Of Glacial Origin, or ice made soils (till)
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