Normalized differential cross sections for elastic (rotationally averaged) electron scattering from gaseous water (H2O) are obtained using the relative flow method against helium with a thin aperture collimating source of gas instead of a tube. This method obviates the use of gas kinetic molecular diameters for helium or water. Our measurements are found to be largely in quantitative disagreement with past differential elastic electron scattering measurements and suggest that present recommended electron scattering total cross sections for water be revised.

Measured and calculated differential cross sections for elastic ͑rotationally unresolved͒ electron scattering from two primary alcohols, methanol ͑CH 3 OH͒ and ethanol ͑C 2 H 5 OH͒, are reported. The measurements are obtained using the relative flow method with helium as the standard gas and a thin aperture as the collimating target gas source. The relative flow method is applied without the restriction imposed by the relative flow pressure conditions on helium and the unknown gas. The experimental data were taken at incident electron energies of 1, 2, 5, 10, 15, 20, 30, 50, and 100 eV and for scattering angles of 5°-130°. There are no previous reports of experimental electron scattering differential cross sections for CH 3 OH and C 2 H 5 OH in the literature. The calculated differential cross sections are obtained using two different implementations of the Schwinger multichannel method, one that takes all electrons into account and is adapted for parallel computers, and another that uses pseudopotentials and considers only the valence electrons. Comparison between theory and experiment shows that theory is able to describe low-energy electron scattering from these polyatomic targets quite well.

We examined the mechanism of accumulation of charged polynuclear platinum complexes (PPCs), based on analogy of polyarginine interactions with the cell surface heparan sulfate proteoglycan (HSPG) family of protein-linked glycosoaminoglycan polysaccharides (GAGs). GAGS such as heparan sulfate (HS) and chondroitin sulfate (CS) mediate the cellular entry of many charged molecules. Fluorescence microscopy and flow cytometry showed that PPCs, but not the neutral cisplatin or oxaliplatin, blocked the cellular entry of TAMRA-R9 (a nonarginine peptide, R9) coupled to the TAMRA fluorescent label 5-(and 6-)carboxytetramethylrhodamine) in Chinese Hamster Ovary (CHO), human colon carcinoma (HCT116), and osteosarcoma (SAOS-2) cells. Furthermore, detection of platinum accumulation in wt CHO, mutant CHO-pgsD-677 (lacking HS), and CHO-pgsA (lacking HS/CS) cells confirms that HSPG-mediated interactions are an important mechanism for PPC internalization, but not so for uncharged cisplatin and oxaliplatin. Endocytosis inhibitor studies show that macropinocytosis, a mechanism of cell entry for heparan sulfate GAGs and arginine-rich peptides, is important in the cellular accumulation of “non-covalent” TriplatinNC, and to a lesser degree, the covalently-binding BBR3464. Clathrin-mediated endocytosis, however, was not involved in either case. Overall the results suggest a new proteoglycan-mediated mechanism for cellular accumulation of PPCs not shared by cisplatin or oxaliplatin. The results have significant implications for rational design of platinum antitumor drugs with distinct biological profiles in comparison to the clinically-used agents as well as expanding the chemotypes for HS proteoglycan-dependent receptors.

Gold complexes that could act as antitumor agents have attracted great attention. Heterocyclic compounds and their metal complexes display a broad spectrum of pharmacological properties. The present study reports the preparation and characterization of four novel gold(I) complexes containing tertiary phosphine and new ligands 5-adamantyl-1,3-thiazolidine-2-thione, 3-methyladamantane-1,3,4-oxadiazole-2-thione. Spectroscopic data suggest that gold is coordinated to the exocyclic sulfur atom in all cases, as confirmed by X-ray crystallographic data obtained for complex (1) and supported by quantum-mechanical calculations. The cytotoxicity of the compounds has been evaluated in comparison to cisplatin and auranofin in three different tumor cell lines, colon cancer (CT26WT), metastatic skin melanoma (B16F10), mammary adenocarcinoma (4T1) and kidney normal cell (BHK-21). The gold complexes were more active than their respective free ligands and able to inhibit the thioredoxin reductase (TrxR) enzyme, even in the presence of albumin. Molecular modeling studies were carried out to understand the interaction between the compounds and the TrxR enzyme, considered as a potential target for new compounds in cancer treatment. The docking results show that the adamantane ring is essential to stabilize the ligand-enzyme complex prior the formation of covalent bond with gold center. The structure of the new gold compounds was established on the basis of spectroscopic data, DFT calculations and X-ray diffraction. TrxR inhibition was evaluated and the results correlated with the assays in tumor cells, suggesting the TrxR as possible target for these compounds.

Differential cross sections for elastic electron scattering from gaseous water are reported. The measurements are obtained using the relative flow method with He as the standard gas and a thin collimating aperture source of gas instead of a conventional needle source. Differential cross sections were measured at incident energies of 1, 2, 4, 6, 8, 10, 15, 20, 30, 50, and 100 eV for scattering angles ranging from 5°to 130°and integrated over angles to obtain integral cross sections. Corresponding calculations of the differential cross section are carried out using the Schwinger multichannel method, employing extensive basis sets and considering polarization and dipole-scattering effects. Whereas excellent qualitative agreement with past measurements of differential cross sections is observed, our measurements are found to be consistently in significant quantitative disagreement with these measurements. The present calculations, on the other hand, generally agree in magnitude with previous results.