Thermoelectric and Structural Characterization of Al-Doped ZnO/Y₂O₃ Multilayers

The influence of Y2O3 nanolayers on thermoelectric performance and structure of 2% Al-doped ZnO (AZO) thin films has been studied. Multilayers based on five 50 nm thick AZO layers alternated with few nanometers thick Y2O3 layers were prepared by pulsed laser deposition on Al2O3 single crystals by alternate ablation of AZO target and Y2O3 target. The number of laser shots on Y2O3 target was maintained very low (5, 10 and 15 pulses in three separate experiments. The main phase (AZO) presents polycrystalline orientation and typical columnar growth not affected by the presence of Y2O3 nanolayers. The multilayer with 15 laser shots of Y2O3 showed best thermoelectric performance with electrical conductivity σ 48 S/cm and Seebeck coefficient S = −82 μV/K, which estimate power factor (S2·σ) about 0.03 × 10−3 W m−1 K−2 at 600 K. The value of thermal conductivity (κ) was found 10.03 W m−1 K−1 at 300 K, which is one third of typical value previously reported for bulk AZO. The figure of merit, ZT = S2·σ·T/κ, is calculated 9.6 × 10−4 at 600 K. These results demonstrated the feasibility of nanoengineered defects insertion for the depression of thermal conductivity.

NPY-Y1 coexpressed with NPY-Y5 receptors modulate anxiety but not mild social stress response in mice

The Y1 and Y5 receptors for neuropeptide Y have overlapping functions in regulating anxiety. We previously demonstrated that conditional removal of the Y1 receptor in the Y5 receptor expressing neurons in juvenile Npy1r(Y5R-/-) mice leads to higher anxiety but no changes in hypothalamus-pituitary-adrenocortical axis activity, under basal conditions or after acute restraint stress. In the present study, we used the same conditional system to analyze the specific contribution of limbic neurons coexpressing Y1 and Y5 receptors on the emotional and neuroendocrine responses to social chronic stress, using different housing conditions (isolation vs. group-housing) as a model. We demonstrated that control Npy1r(2lox) male mice housed in groups show increased anxiety and hypothalamus-pituitary-adrenocortical axis activity compared with Npy1r(2lox) mice isolated for six weeks immediately after weaning. Conversely, Npy1r(Y5R-/-) conditional mutants display an anxious-like behavior but no changes in hypothalamus-pituitary-adrenocortical axis activity as compared with their control littermates, independently of housing conditions. These results suggest that group housing constitutes a mild social stress for our B6129S mouse strain and they confirm that the conditional inactivation of Y1 receptors specifically in Y5 receptor containing neurons increases stress-related anxiety without affecting endocrine stress responses.

Enzymes involved in arachidonic acid release in adrenal and Leydig cells

Stimulation of receptors and subsequent signal transduction results in the activation of arachidonic acid (AA) release. Once AA is released from phospholipids or others esters, it may be metabolized via the cycloxygenase or the lipoxygenase pathways. How the cells drive AA to these pathways is not elucidated yet. It is reasonable to speculate that each pathway will have different sources of free AA triggered by different signal transduction pathways. Several reports have shown that AA and its lipoxygenase-catalyzed metabolites play essential roles in the regulation of steroidogenesis by influencing cholesterol transport from the outer to the inner mitochondrial membrane, the rate-limiting step in steroid hormone biosynthesis. Signals that stimulate steroidogenesis also cause the release of AA from phospholipids or other esters by mechanisms that are not fully understood. This review focuses on the enzymes of AA release that impact on steroidogenesis.

Relative Prognostic Value of Self-Reported Adherence and Plasma Nnrti/Pi Concentrations to Predict Virological Rebound in Patients Initially Responding to Haart

We studied the predictive value of self-reported adherence and plasma drug concentrations on virological rebound to HAART. Among 238 participants in the AdICoNA study who had viral load ≤500 copies/ml, 42 (17.6%) experienced virological rebound by 96 weeks. Both self-reported non-adherence and sub-optimal concentration were independently associated with a higher risk of virological rebound.

[Importation dengue]

We describe two cases of dengue fever (DF) serologicaly confirmed. In both, the clinical features are characterized by: fever, severe headache, myalgias and arthalgias, transient macule-papule rash, leukopenia and thrombocytopenia. The entire illness last few days and terminates abruptly without therapy. A history of travel to dengue-endemic areas and occurrence of other cases in a community are important reminders to include this disease in the differential diagnosis. The hemoagglutination inhibition test for DF at the Laboratory of Virology of the Istituto Superiore di Sanità on two collected sera, during the acute and convalescent phases, has showed a seroconversion. A problem is to advise patients to avoid endemic areas because the second exposure could induce DHF/dengue shock syndrome.

Exocytosis of vacuolar apical compartment (VAC) in Madin-Darby canine kidney epithelial cells: cAMP is involved as second messenger

Vacuolar apical compartment (VAC) is a transient organelle originally observed in Madin-Darby canine kidney (MDCK) epithelial cells impaired from forming cell-cell contacts. VACs are large vacuoles which contain microvilli and apical plasma membrane markers (among others, a 184-kDa plasma membrane protein, AP2), but exclude basolateral membrane markers. Upon reestablishment of cell-cell contacts, VACs are rapidly (within 1 h) exocytosed toward intercellular spaces, after which the apical plasma membrane drifts toward its final destination (Vega-Salas, Salas, and Rodriguez-Boulan. 1988. J. Cell Biol. 107, 1717-1728). In this work, we studied the role of cAMP as a mediator for the exocytosis of VACs. We shifted confluent cells from low to normal calcium medium (thus reestablishing cell-cell contacts and causing VAC exocytosis), a shift which resulted in a significant rise of cellular levels of both total intracellular and protein-bound cAMP. The 8-Br analog of cAMP (8-Br-cAMP) (5-50 microM) caused externalization of the intracellular compartment of AP2 as measured by radioimmunoassay. A similar effect was observed with 3-isobutyl-1-methylxanthine. 8-Br-cAMP also caused the appearance of AP2-positive VAC images in nonpermeabilized cells, namely, VACs that become accessible to extracellular antibodies upon fusion with the plasma membrane. Lanthanum, which abolishes the peak of intracellular free calcium during a calcium switch, failed to block the exocytosis. On the other hand, 12-O-tetradecanoylphorbol-13-acetate induced only a modest exocytic response. Finally, 8-Br-cAMP induced VAC exocytosis in sparse MDCK cells grown in normal calcium medium. These data indicate that cAMP is a mediator between the extracellular signal provided by cell-cell contacts and VAC exocytosis.

The cytosol as site of phosphorylation of the cyclic AMP-dependent protein kinase in adrenal steroidogenesis

The mitochondria, the microsomes and the cytosol have been described as possible sites of cAMP-dependent phosphorylation. However, there has been no direct demonstration of a cAMP-dependent kinase associated with the activation of the side-chain cleavage of cholesterol. We have investigated the site of action of the cAMP-dependent kinase using a sensitive cell-free assay. Cytosol derived from cells stimulated with ACTH or cAMP was capable of increasing progesterone synthesis in isolated mitochondria when combined with the microsomal fraction. Cytosol derived from cyclase or kinase of negative mutant cells did not. Cyclic AMP and cAMP-dependent protein kinase stimulated in vitro a cytosol derived from unstimulated adrenal cells. This cytosol was capable of stimulating progesterone synthesis in isolated mitochondria. Inhibitor of cAMP-dependent protein kinase abolished the effect of the cAMP. ACTH stimulation of cytosol factors is a rapid process observable with a half maximal stimulation at about 3 pM ACTH. The effect was also abolished by inhibitor of arachidonic acid release. The function of cytosolic phosphorylation is still unclear. The effect of inhibitors of arachidonic acid release, and the necessity for the microsomal compartment in order to stimulate mitochondrial steroidogenesis, suggest that the factor in the cytosol may play a role in arachidonic acid release.

The action of luteinizing hormone on the testis

Luteinizing hormone (LH) and human chorionic gonadotrophin (hCG) receptors are coupled to intracellular effector systems, most notably adenylate cyclase, through guanyl nucleotide-binding proteins or G-proteins. The molecular mechanism involved in the dynamic coupling of the LH/hCG receptor however, are not known. It has been postulated that receptor aggregation at the molecular level plays a critical role in this process. There have been attempts to understand the receptor association and dissociation phenomena at the molecular level. One of them involves the participation of the major histocompatibility complex (MHC) class I antigen in the mechanism of receptor activation and/or expression. One molecular basis for these mechanisms consists of a physical interaction between MHC proteins and receptors to form "compound receptors" able to transfer a hormonal signal to the cell. Using a photo-reactive probe we demonstrated that the LH/hCG receptors and the class I antigens are closely associated in the membrane. Thus, it is possible to form covalent complexes of hCG and class I antigens through the binding of the hormone to specific receptors. These findings imply that LH/hCG receptors and the MHC class I antigens may interact at the level of the plasma membrane in the mechanism of LH action. We also performed experiments using a single cell and limiting stimulation to a patch of membrane. The results stimulating the cell in a localized area suggested that even if all components are entirely free to float there is a constraint in the localization of the receptor, G-protein, and/or the effector, supporting the constraint dissociation model. Within a limited area subunits could dissociate, but they would not be free to diffuse throughout the membrane. Moreover the concept of compartmentalization that has been utilized to explain some inconsistencies in second-messenger action now can be proved by experimental design.