Preparation of protein gradients through the controlled deposition of protein-nanoparticle conjugates onto functionalized surfaces

This paper describes a simple method for the preparation and characterization of protein density gradients on solid supports. The method employs colloidal metal nanoparticles as protein carriers and optical tags and is capable of forming linear, exponential, 1D, 2D, and multiprotein gradients of varying slope without expensive or sophisticated surface patterning techniques. Surfaces patterned with proteins using the procedures described within are shown to support cell growth and are thus suitable for studies of protein-cell interactions.     

Zeroes of Gaussian analytic functions with translation-invariant distribution

We study zeroes of Gaussian analytic functions in a strip in the complex plane, with translation-invariant distribution. We prove that the horizontal limiting measure of the zeroes exists almost surely, and that it is non-random if and only if the spectral measure is continuous (or degenerate). In this case, the limiting measure is computed in terms of the spectral measure. We compare the behavior with Gaussian analytic functions with symmetry around the real axis. These results extend a work by Norbert Wiener.     

on the positivity of certain sums of ultraspherical polynomials

Journal d'Analyse Mathématique -     

Suppression of nitric oxide production in mouse macrophages by soybean flavonoids accumulated in response to nitroprusside and fungal elicitation

Background

The anti-inflammatory properties of some flavonoids have been attributed to their ability to inhibit the production of NO by activated macrophages. Soybean cotyledons accumulate certain flavonoids following elicitation with an extract of the fungal pathogen Diaporthe phaseolorum f. sp. meridionalis (Dpm). Sodium nitroprusside (SNP), a nitric oxide donor, can substitute for Dpm in inducing flavonoid production. In this study, we investigated the effect of flavonoid-containing diffusates obtained from Dpm- and SNP-elicited soybean cotyledons on NO production by lipopolysaccharide (LPS)- and LPS plus interferon-γ (IFNγ)-activated murine macrophages.

Results

Significant inhibition of NO production, measured as nitrite formation, was observed when macrophages were activated in the presence of soybean diffusates from Dpm- or SNP-elicited cotyledons. This inhibition was dependent on the duration of exposure to the elicitor. Daidzein, genistein, luteolin and apigenin, the main flavonoids present in diffusates of elicited cotyledons, suppressed the NO production by LPS + IFNγ activated macrophages in a concentration-dependent manner, with IC₅₀ values of 81.4 μM, 34.5 μM, 38.6 μM and 10.4 μM respectively. For macrophages activated with LPS alone, the IC₅₀ values were 40.0 μM, 16.6 μM, 10.4 μM and 2.8 μM, respectively. Western blot analysis showed that iNOS expression was not affected by daidzein, was reduced by genistein, and was abolished by apigenin, luteolin and Dpm- and SNP-soybean diffusates at concentrations that significantly inhibited NO production by activated macrophages.

Conclusions

These results suggest that the suppressive effect of flavonoids on iNOS expression could account for the potent inhibitory effect of Dpm- and SNP-diffusates on NO production by activated macrophages. Since the physiological concentration of flavonoids in plants is normally low, the treatment of soybean tissues with SNP may provide a simple method for substantially increasing the concentration of metabolites that are beneficial for the treatment of chronic inflammatory diseases associated with NO production.

     

RNA-mediated control of metal nanoparticle shape

RNA sequences previously isolated by in vitro selection were further characterized for their ability to control palladium particle growth. Five pyridyl-modified RNA sequences (Pdases) representing each of the different evolved families were found to form hexagonal plates with a high degree of shape specificity. However, a sixth nonrelated pyridyl-modified RNA sequence was found to form exclusively cubic particles under identical conditions. Replacing pyridyl-modified RNA with native RNA resulted in a complete loss of RNA function. Removing the 3'-fixed sequence region from the Pdase had little effect on particle growth; however, further truncations into the variable region resulted in a significant loss of activity and particle shape control. These Pdases were selected using the organometallic precursor complex tris(dibenzylideneacetone) dipalladium(0) ([Pd2(DBA)3]). Changing the metal center and ligand of the group VIII organometallic precursor complex revealed a strong dependence of particle growth and shape on the DBA ligands. Changing the metal center from Pd to Pt while retaining the DBA ligands gave predominantly hexagonal Pt, but with a decrease in shape control. Taken together, the results of this study suggest that the full-length Pdases contain active sites capable of highly specific molecular recognition of organometallic complexes as particle formation reagents.     

Inhibition of HIV fusion with multivalent gold nanoparticles

The design and synthesis of a multivalent gold nanoparticle therapeutic is presented. SDC-1721, a fragment of the potent HIV inhibitor TAK-779, was synthesized and conjugated to 2.0 nm diameter gold nanoparticles. Free SDC-1721 had no inhibitory effect on HIV infection; however, the (SDC-1721)-gold nanoparticle conjugates displayed activity comparable to that of TAK-779. This result suggests that multivalent presentation of small molecules on gold nanoparticle surfaces can convert inactive drugs into potent therapeutics.     

Sur les probabilités en chaîne

Sans résumé     

Quelques recherches sur l'interpolation de Lagrange et d'Hermite par la méthode du développement des fonctions fondamentales

Sans résumé