Inhibition by 5-(tetradecyloxy)-2-furoic acid of fatty acid and cholesterol synthesis in isolated rat hepatocytes

Fatty acid and cholesterol synthesis in isolated rat hepatocytes were strongly inhibited by 5-(tetradecyloxy)-2-furoic acid. With either³H₂O or [2-¹⁴C]acetate as the labeled precursor, the concentrations of inhibitor causing 50% decrease in fatty acid and cholesterol synthesis were, respectively, <0.005 mM and 0.020 mM. At 0.1 mM inhibitor, citrate concentration in cells from fed rats was increased by 75%; lactate and pyruvate concentrations were decreased by 30%; ethanol oxidation was decreased by 20%; with cells from starved rats, the mitochondrial [NAD⁺]/[NADH] was decreased. Other parameters were unaffected. Both its potency and its specificity indicate that 5-(tetradecyloxy)-2-furoic acid will be useful in studies on the regulation of lipid biosynthesis.     

Mirror or Megaphone?: How relationships between narcissism and social networking site use differ on Facebook and Twitter

As research on the connection between narcissism and social networking site (SNS) use grows, definitions of SNS and measurements of their use continue to vary, leading to conflicting results. To improve understanding of the relationship between narcissism and SNS use, as well as the implications of differences in definition and measurement, we examine two ways of measuring Facebook and Twitter use by testing the hypothesis that SNS use is positively associated with narcissism. We also explore the relation between these types of SNS use and different components of narcissism within college students and general adult samples. Our findings suggest that for college students, posting on Twitter is associated with the Superiority component of narcissistic personality while Facebook posting is associated with the Exhibitionism component. Conversely, adults high in Superiority post on Facebook more rather than Twitter. For adults, Facebook and Twitter are both used more by those focused on their own appearances but not as a means of showing off, as is the case with college students. Given these differences, it is essential for future studies of SNS use and personality traits to distinguish between different types of SNS, different populations, and different types of use.     

Structural relaxations in Fe-Co-Si-B amorphous alloys

The structural relaxation involved in the thermal treatment of Fe-Co-Si-B metallic glasses and the crystallization process as a function of Co content have been investigated. Magnetic measurements and the Mössbauer temperature scanning method for measuring the Curie temperature were used. One stage of structural relaxation above 570 K in metallic glasses with composition Fe_78–x Co _x Si₉B₁₃ was observed. This stage is characterized by a change of the chemical short-range ordering. The crystallization process detected by the magnetic measurements proceeds in two and in some cases in three steps.     

A Novel Nanoprobe for Multimodal Imaging Is Effectively Incorporated into Human Melanoma Metastatic Cell Lines

To facilitate efficient drug delivery to tumor tissue, several nanomaterials have been designed, with combined diagnostic and therapeutic properties. In this work, we carried out fundamental in vitro and in vivo experiments to assess the labeling efficacy of our novel theranostic nanoprobe, consisting of glycogen conjugated with a red fluorescent probe and gadolinium. Microscopy and resazurin viability assays were used to study cell labeling and cell viability in human metastatic melanoma cell lines. Fluorescence lifetime correlation spectroscopy (FLCS) was done to investigate nanoprobe stability. Magnetic resonance imaging (MRI) was performed to study T₁ relaxivity in vitro, and contrast enhancement in a subcutaneous in vivo tumor model. Efficient cell labeling was demonstrated, while cell viability, cell migration, and cell growth was not affected. FLCS showed that the nanoprobe did not degrade in blood plasma. MRI demonstrated that down to 750 cells/μL of labeled cells in agar phantoms could be detected. In vivo MRI showed that contrast enhancement in tumors was comparable between Omniscan contrast agent and the nanoprobe. In conclusion, we demonstrate for the first time that a non-toxic glycogen-based nanoprobe may effectively visualize tumor cells and tissue, and, in future experiments, we will investigate its therapeutic potential by conjugating therapeutic compounds to the nanoprobe.     

Autoxidation of stored soybean lecithin

Soybean phospholipid concentrates, generally called lecithins, can be stored for long time in a refrigerator or even at room temperature, without apparent changes of sensory properties, and their peroxide value usually remains low. This behaviour is related to the antioxidant activity of phospholipids in refined vegetable oils [1] which was attributed to their synergistic effect in presence of tocopherols [2, 3]. Both the low peroxide content and the inhibitory activity may be explained, at least partially, by the hydroperoxide decomposing activity of phospholipids [4], the rate of hydroperoxide decomposition being proportinal to the square root of the hydroperoxide content [5]. Therefore, we have analysed several samples of lecithin to find out whether the presence of phospholipids only affects the rate of hydroperoxide accumulation or the formation of total oxidation products, respectively.     

Purification of delta-aminolevulinate dehydratase from genetically engineered yeast

Saccharomyces cerevisiae transformed with a multicopy plasmid carrying the yeast structural gene HEM2, which codes for delta-aminolevulinate dehydratase, was enriched 20-fold in the enzyme. Beginning with cell-free extracts of transformed cells, the dehydratase was purified 193-fold to near-homogeneity. This represents a 3900-fold purification relative to the enzyme activity in normal, untransformed yeast cells. The specific activity of the purified enzyme was 16.2 mumol h-1 per mg protein at pH 9.4 and 37.5 degrees C. In most respects the yeast enzyme resembles mammalian enzymes. It is a homo-octamer with an apparent Mr of 275,000, as determined by centrifugation in glycerol density gradients, and under denaturing conditions behaved as a single subunit of Mr congruent to 37,000. The enzyme requires reduced thiol compounds to maintain full activity, and maximum activity was obtained in the presence of 1.0 mM-Zn2+. It is sensitive to inhibition by the heavy metal ions Pb2+ and Cu2+. The enzyme exhibits Michaelis-Menten kinetics and has an apparent Km of 0.359 mM. Like dehydratases from animal tissues, the yeast enzyme is rather thermostable. During the purification process an enhancement in total delta-aminolevulinate dehydratase activity suggested the possibility that removal of an inhibitor of the enzyme could be occurring.     

The influence of porous silicon on junction formation in silicon solar cells

In this work the results of a structural investigation by SEM of porous silicon (PS) before and after diffusion processes are reported. The formation of PS n⁺/p structures were carried out on PS p/p silicon wafers with two methods: from POCl₃ in a conventional furnace and from a phosphorous doped paste in an infrared furnace. Sheet resistance was found to be a strong function of PS structure. Further details on sheet resistance distribution are reported. The electrical contacts in prepared solar cells were obtained by screen printing process, with a Du Ponte photovoltaic silver paste for front contacts and home-prepared silver with 3% aluminium paste for the back ones. Metallization was done in the infrared furnace. Solar cell current–voltage characteristics were measured under an AM 1.5 global spectrum sun simulator. The average results for multi-crystalline silicon solar cells without antireflection coating are: I_sc=720 (mA), V_oc=560 (mV), FF=69%, Eff=10.6% (area 25 cm²).