[en] The uptake and subcellular localization of selenium-75 was examined in 3 established mammary cell lines in vitro. Previous studies had demonstrated that cell line YN-4 exhibited a biphasic growth response to selenium, whereas cell lines CL-S1 and WAZ-2t exhibited only an inhibition of growth. All 3 cell lines incorporated selenium-75 readily over a 48-h incubation period and the concentration of selenium-dependent glutathione peroxidase was correlated with the level of selenium-75 uptake. However, neither of these 2 parameters could be related to the unique biphasic growth response exhibited by cell line YN-4. The intracellular localization of selenium-75 was similar in lines CL-S1 and YN-4 with the label incorporated primarily in the cytosol and secondarily in the mitochondria. Although the unique growth response of line YN-4 could not be attributed to the incorporation parameters examined herein, the stable incorporation of selenium-75 at high levels should make these lines useful for further studies on the subcellular localization of selenium into organelles and macromolecules. (author)

[en] The structure of liquid-mercury-supported Langmuir films (LFs) of chiral serine-modified fatty acid molecules was studied as a function of length, n = 8-22 carbons, temperature, T = 5-25 C, and surface coverage, A ∼ 40-200 (angstrom)² per molecule, for both homochiral and heterochiral compounds. Using surface pressure π-area A isotherms and surface-specific synchrotron X-ray diffraction methods the phase diagram was determined in detail. No lateral order was found for phases comprising surface-parallel molecules, in contrast with unmodified fatty acid LFs on mercury. For phases comprising standing-up molecules, long range lateral order was found for n ≥ 12, but no order for n = 8. The molecules in the ordered phases are extended, and tilt rigidly by ∼40^o from the surface normal. The homochiral LFs pack in an oblique, single-molecule, unit cell. The heterochiral LFs pack in a body-centered rectangular unit cell, containing two molecules. Unlike unmodified fatty acid LFs, the structure of the standing-up phase does not vary with n, T or A. The interactions underlying these characteristics, and the role of chirality, are discussed.

[en] We have investigated the effect of hydrogen interaction with silicene monolayer and multilayer films grown on Ag(111) by means of scanning tunneling microscopy, low energy diffraction and high-resolution electron energy loss spectroscopy. On monolayer silicene, we demonstrate that the recently reported hydrogenated γ-(3 × 3) is indeed observed, but is found often in coexistence with the usual “flower” pattern of the clean silicene-(3 × 3), also labeled α-(3 × 3). In the vibrational spectra, features related to Si−H vibrational modes show shifts towards lower energies as compared to hydrogenated Si surfaces. This substantial bond softening is indicative of a partial charge filling of the bonding or anti-bonding orbitals of the Si−H bonds as compared to Si(111)−H. Indirectly, this is an evidence of the hybridization of monolayer silicene with the Ag(111) substrate. At multilayer coverage, the situation is clearly different. Indeed, hydrogen strongly perturbs the √3 × √3 reconstruction of the multilayer film, leading to its local dissolution and to the formation of protrusions due to clustering of atoms. The vibrational spectrum of the √3 × √3 silicene closely resembles that of a highly hydrogenated Si surfaces, with the simultaneous presence of Si−H, Si−H₂ and Si−H₃ bonds.

[en] Intracellular sodium, chlorine, and potassium concentrations (mmol/kg dry weight) were determined by electron probe X-ray microanalysis of individual epithelial cells in freeze-dried 2-micrometer sections of mouse mammary tissue which were cut at -30 degrees. A model system was utilized in order to compare elemental content of cells from normal pregnant mammary tissue and preneoplastic and neoplastic mammary tissues from female BALB/cCrlMed mice. Animals were killed by cervical dislocation, and tissue was rapidly frozen in liquid propane. Normal mammary glands were obtained from primiparous mice at 16 to 17 days of gestation. Tissue from the hyperplastic alveolar nodule line D1 was removed from donor mice 12 to 16 weeks after transplantation into the cleared mammary fat pad. All mammary adenocarcinomas, D1T, were primary tumors which developed in mice with transplants of nodule line D1. Data were collected from five animals (10 cells/animal) in each of the three groups. It was found that the electrolyte content of cells of preneoplastic tissue was the same as that of the normal mammary tissue but was significantly elevated in neoplastic tissue (162, 130, and 48% increases for sodium, chlorine, and potassium, respectively). Thus, an increase in electrolyte content seems to be associated with the transformation to a neoplastic state and not associated with conversion to the preneoplastic state

[en] The COMMA-D mammary cell line exhibits mammary-specific functional differentiation under appropriate conditions in cell culture. The cytologically heterogeneous COMMA-D parental line and the clonal lines DB-1, TA-5, and FA-1 derived from the COMMA-D parent were examined for similar properties of functional differentiation. In monolayer cell culture, the cell lines DB-1, TA-5, FA-1, and MA-4 were examined for expression of mammary-specific and epithelial-specific proteins by an indirect immunofluorescence assay. The clonal cell lines were relatively homogeneous in their respective staining properties and seemed to represent three subpopulations found in the heterogeneous parental COMMA-D lines. None of the four clonal lines appeared to represent myoepithelial cells. The cell lines were examined for expression of β-casein mRNA in the presence or absence of prolactin. The inducibility of β-casein in the COMMA-D cell line was further enhanced by a reconstituted basement membrane preparation enriched in laminin, collagen IV, and proteoglycans. These results support the hypothesis that the functional response of inducible mammary cell populations is a result of interaction among hormones, multiple extracellular matrix components, and specific cell types

[en] Due to its potential thermal degradation or polymorphic transformation, thermal stability of a food additive may limit its use in food preparations, when heating process is involved. In this paper, we present an investigation on thermal behavior of sodium cyclamate, one of the most frequently used components in tabletop sweeteners. Thermogravimetric data revealed that sodium cyclamate exists in two polymorphic forms: sodium cyclamate di-hydrated (C₆H₁₂NSO₃Na·2H₂O) and anhydrous sodium cyclamate (C₆H₁₂NSO₃Na). X-ray powder diffraction data revealed that hydrate and anhydrate sodium cyclamate are true polymorphs. Under heating conditions, the hydrated form dehydrated in a complex multiple-step process. Finally, thermal decomposition of sodium cyclamate was studied and a degradation mechanism is proposed. At 170 °C, sodium cyclamate sublimates and dimerizes, by condensation of two cyclamate moieties, leading to formation of highly pure N,N-diciclohexyl sulfamide, a potential anxiolytic compound.

[en] The present job describes the technical characteristics and operation of two clinical equipment designed in Cuba, for the determination in vivo of the osseous mineral content in forearm, based on the of gamma absorption technique of a single photon. The development of these equipment and the measurements done with one of them are the first intents carried out in the country to diagnose osseous illnesses by means of this method. (author)

[en] Total arsenic concentrations (t As) and the presence of total and fecal coliforms in drinking water from Tecuala, Nayarit, Mexico, were determined. The presence of t As was analyzed by means of hydride generation atomic fluorescence spectrometry. Total and fecal coliforms were determined through the Most Probable Number (MPN) method. According to the results, the mean concentration of t As in Tecuala wa 15.82 μg/L, in Atotonilco 19.88 μg/L, in Pajaritos 21.49 μg/L, in Quimichis 17.80 μg/L, and in Playas de Novillero 19.79 μg/L. The t As concentrations in drinking water from Tecuala, Nayarit, are within the limit set by the Mexican official standards (25 μg/L); still, they are over the limit established by the World Health Organization (10 μg/L). The concentration of coliforms in water from wells 1 and 3 was 180 MPN/100 ml and 43 MPN/100 ml for well water 2. The presence of total and fecal coliforms, suggest the infiltration of sewage which could increase the levels of dissolved arsenic. The results of this study will serve as an antecedent of the water quality in Tecuala, Nayarit. (Author)