Preferential uptake of L- versus D-amino acid cell-penetrating peptides in a cell type-dependent manner

The use of protease-resistant D-peptides is a prominent strategy for overcoming proteolytic sensitivity in the use of cell-penetrating peptides (CPPs) as delivery vectors. So far, no major differences have been reported for the uptake of L- and D-peptides. Here we report that cationic L-CPPs are taken up more efficiently than their D-counterparts in MC57 fibrosarcoma and HeLa cells but not in Jurkat T leukemia cells. Reduced uptake of D-peptides co-occurred with persistent binding to heparan sulfates (HS) at the plasma membrane. In?vitro binding studies of L- and D-peptides with HS indicated similar binding affinities. Our results identify two key events in the uptake of CPPs: binding to HS chains and the initiation of internalization. Only the second event depends on the chirality of the CPP. This knowledge may be exploited for a stereochemistry-dependent preferential targeting of cells.     

A Weighted Isoperimetric Inequality in an Orthant

Let c, k ₁ , ..., k _N be non-negative numbers, and define a measure μ in the orthant W :?=?{x?∈??by \(d\mu = e^{c|x|^2 } x_1 ^{k_1 }\cdots x_N ^{k_N } \, dx \) . It is shown that among all measurable subsets of W with fixed μ-measure, the intersection of W with a ball centered at the origin renders the weighted perimeter relative to W a minimum. Norm inequalities in weighted Sobolev spaces and a comparison result for solutions to boundary value problems for degenerate elliptic equations are also given.     

Inter-laboratory trials for analysis of perfluorooctanesulfonate and perfluorooctanoate in water samples: Performance and recommendations

The ISO 25101 (International Organization for Standardization, Geneva) describes a new international standard method for the determination of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) in unfiltered samples of drinking and surface waters. The method is based on the extraction of target analytes by solid phase extraction, solvent elution, and determination by high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS). For the determination of the performance of this method, more than 20 laboratories from 9 different countries participated in an inter-laboratory trial in 2006. In addition, inter-laboratory trials were conducted in 2008 and 2009 for the analysis of perfluoroalkylsubstances (PFASs), including PFOS and PFOA, in water samples by following the protocols of Japanese Industrial Standard (JIS). Overall, the repeatability coefficients of variation (i.e., within-laboratory precision) for PFOS and PFOA in all water samples were between 3 and 11%, showing a adequate precision of the ISO and JIS methods. The reproducibility coefficients of variation (i.e., between-laboratory precision) were found to vary within a range of 7–31% for surface water and 20–40% for wastewater. The recoveries of PFOS and PFOA, as a measure of accuracy, varied from 84 to 100% for surface water and from 84 to 100% for wastewater among the samples with acceptable criteria for internal standards recovery. The determined concentrations of PFASs in samples compared well with the “true” values. The results of the inter-laboratory trial confirmed that the analytical methods are robust and reliable and can be used as a standard method for the analysis of target compounds in water samples.     

Synthesis and characterization of mixed-ligand diimine-piperonal thiosemicarbazone complexes of ruthenium(II): Biophysical investigations and biological evaluation as anticancer and antibacterial agents

We have used a novel microwave-assisted method developed in our laboratories to synthesize a series of ruthenium-thiosemicarbazone complexes. The new thiosemicarbazone ligands are derived from benzo[d][1,3]dioxole-5-carbaldehyde (piperonal) and the complexes are formulated as [(diimine)(2)Ru(TSC)](PF(6))(2) (where the TSC is the bidentate thiosemicarbazone ligand). The diimine in the complexes is either 2,2'-bipyridine or 1,10-phenanthroline. The complexes have been characterized by spectroscopic means (NMR, IR and UV-Vis) as well as by elemental analysis. We have studied the biophysical characteristics of the complexes by investigating their anti-oxidant ability as well as their ability to disrupt the function of the human topoisomerase II enzyme. The complexes are moderately strong binders of DNA with binding constants of 10(4) M(-1). They are also strong binders of human serum albumin having binding constants on the order of 10(4) M(-1). The complexes show good in vitro anticancer activity against human colon cancer cells, Caco-2 and HCT-116 and indeed show some cytotoxic selectivity for cancer cells. The IC(50) values range from 7 - 159 μM (after 72 h drug incubation). They also have antibacterial activity against Gram-positive strains of pathogenic bacteria with IC(50) values as low as 10 μM; little activity was seen against Gram-negative strains. It has been established that all the compounds are catalytic inhibitors of human topoisomerase II.     

ChemInform Abstract: The Importance of 5d Orbitals for Covalent Bonding in Ytterbium Clusters.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Effect of weathering on scratch/mar and mechanical behaviour of clearcoats

The study examines the effect of weathering on mechanical and chemical properties of two 2K (twopack, with and without light stabilisation additives) and one 1K (onepack) clearcoats, concentrating on scratch and mar resistance and acid etch resistance. The clearcoats were investigated before and in the course of accelerated weathering. For determining the mar resistance two different instruments were used: - AMTEC laboratory car wash equipment (rotating wet brush) - Crockmeter Explanations for the changes in clearcoat properties caused by weathering are given by Dynamic-Mechanical Analysis, FT-IR-Spectroscopy, Universal-hardness and surface tension measurements. The clearcoat systems investigated show a clear deterioration of their properties after short periods of accelerated weathering. This effect is more expressed for the clearcoat samples without light stabilizers.