RESUMEN
The effect of temperature on the vibrational properties of struvite crystals grown from silica gels was systematically studied by µ-Raman spectroscopy. The time-dependent Raman spectra recorded in the process of long time annealing of struvite crystal at 353 K do not indicate structural changes in the struvite crystal with the time of annealing. The temperature-dependent Raman spectra recorded in the range 298-423 K reveal a phase transition in struvite at about 368 K. Above this characteristic temperature, some of bands assigned to vibrations of the PO4 and NH4 tetrahedra and water molecules observed in the Raman spectra in low temperatures (orthorhombic phase) change their spectral parameters or disappear, which indicates a transition to a higher symmetry structure of struvite in the range of high temperatures.
RESUMEN
It has been revealed that lanthanum calcium borate (La2CaB10O19) crystals show two-photon absorption (TPA) induced by a UV laser field. UV-induced TPA measurements were performed in the spectral range of 475-1130 nm using as fundamental beam the third harmonics of the 28 ps Nd-YAG pulsed laser as a pumping beam for LiB3O5 optical parametrized generator using Z-scan method. Investigations performed by the Z-scan method were done during illumination by a Xe-F laser (lambda = 217 nm) as a photoinducing (pumping) beam. The pumping laser beam created a thin surface layer (about 80-90 nm) that was the source of the observed photoinduced TPA. The highest values of the TPA beta coefficients were achieved for polarization of the pumping light directed along the second-order crystallographic axis of the investigated crystals. The obtained values of the TPA coefficients were higher than those for the BiB3O6 crystals investigated earlier by us.
RESUMEN
In the absence of the recently identified putative transcription factor scurfin, mice develop a lymphoproliferative disorder resulting in death by 3 wk of age from a pathology that resembles TGF-beta or CTLA-4 knockout mice. In this report, we characterize mice that overexpress the scurfin protein and demonstrate that these animals have a dramatically depressed immune system. Mice transgenic for the Foxp3 gene (which encodes the scurfin protein) have fewer T cells than their littermate controls, and those T cells that remain have poor proliferative and cytolytic responses and make little IL-2 after stimulation through the TCR. Although thymic development appears normal in these mice, peripheral lymphoid organs, particularly lymph nodes, are relatively acellular. In a separate transgenic line, forced expression of the gene specifically in the thymus can alter thymic development; however, this does not appear to affect peripheral T cells and is unable to prevent disease in mice lacking a functional Foxp3 gene, indicating that the scurfin protein acts on peripheral T cells. The data indicate a critical role for the Foxp3 gene product in the function of the immune system, with both the number and functionality of peripheral T cells under the aegis of the scurfin protein.
Asunto(s)
Proteínas de Unión al ADN/biosíntesis , Proteínas de Unión al ADN/genética , Activación de Linfocitos/genética , Subgrupos de Linfocitos T/inmunología , Subgrupos de Linfocitos T/patología , Animales , Linfocitos T CD4-Positivos/inmunología , Linfocitos T CD4-Positivos/metabolismo , Linfocitos T CD4-Positivos/patología , Linfocitos T CD8-positivos/inmunología , Linfocitos T CD8-positivos/metabolismo , Linfocitos T CD8-positivos/patología , Células Cultivadas , Proteínas de Unión al ADN/fisiología , Factores de Transcripción Forkhead , Regulación de la Expresión Génica/inmunología , Histocitoquímica , Inmunofenotipificación , Activación de Linfocitos/inmunología , Recuento de Linfocitos , Prueba de Cultivo Mixto de Linfocitos , Linfopenia/genética , Linfopenia/inmunología , Linfopenia/patología , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos C57BL , Ratones Mutantes , Ratones Transgénicos , Subgrupos de Linfocitos T/metabolismo , Timo/inmunología , Timo/metabolismo , Timo/patología , Transgenes/inmunologíaRESUMEN
Our findings using B cells from either wild-type, CD86-deficient, or beta 2-adrenergic receptor (beta2AR)-deficient mice suggest three mechanisms by which the level of IgG1 and IgE production can be increased on a per cell basis. Trinitrophenyl-specific B cells enriched from unimmunized mouse spleens were pre-exposed to Ag and/or the beta 2AR ligand terbutaline for 24 h before being activated by either a beta 2AR-negative Th2 cell clone or CD40 ligand/Sf9 cells and IL-4 in the presence or absence of an anti-CD86 Ab. Data suggest that the first mechanism involves a B cell receptor (BCR)-dependent up-regulation of CD86 expression that, when CD86 is stimulated, increases the amount of IgG1 and IgE produced in comparison to unstimulated cells. The second mechanism involves a BCR- and beta 2AR-dependent up-regulation of CD86 to a level higher than that induced by stimulation of either receptor alone that, when CD86 is stimulated, further increases the amount of IgG1 and IgE produced. The third mechanism is BCR-independent and involves a beta 2AR-dependent increase in the ability of a B cell to respond to IL-4. Flow cytometric and limiting dilution analyses suggest that the increase in IgG1 and IgE occurs independently from the isotype switching event. These findings suggest that the BCR, the beta 2AR, and CD86 are involved in regulating IL-4-dependent IgG1 and IgE production.
Asunto(s)
Antígenos CD/metabolismo , Subgrupos de Linfocitos B/inmunología , Subgrupos de Linfocitos B/metabolismo , Inmunoglobulina E/biosíntesis , Inmunoglobulina G/biosíntesis , Glicoproteínas de Membrana/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Receptores de Antígenos de Linfocitos B/metabolismo , Agonistas de Receptores Adrenérgicos beta 2 , Animales , Antígenos/farmacología , Antígenos CD/biosíntesis , Antígenos CD/fisiología , Subgrupos de Linfocitos B/efectos de los fármacos , Antígeno B7-2 , Antígenos CD40/metabolismo , Ligando de CD40 , Células Cultivadas , Femenino , Interleucina-4/farmacología , Ligandos , Activación de Linfocitos/inmunología , Masculino , Glicoproteínas de Membrana/biosíntesis , Glicoproteínas de Membrana/farmacología , Glicoproteínas de Membrana/fisiología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Distribución de Poisson , Receptores Adrenérgicos beta 2/fisiología , Receptores de Antígenos de Linfocitos B/biosíntesis , Receptores de Antígenos de Linfocitos B/fisiología , Terbutalina/farmacología , Células Th2/inmunologíaRESUMEN
An important function of the sympathetic nervous system is to maintain homeostasis by modulating the level of cellular activity in many diverse organ systems. The sympathetic neurotransmitter norepinephrine modulates the level of T and B lymphocyte activity by binding to the beta2-adrenergic receptor (beta2AR). The present study was designed to elucidate the mechanism by which stimulation of the beta2AR affects both Th1/Th2 cell cytokine production and Th1/Th2 cell-dependent Ab production. Clones of murine Th1/Th2 cells were exposed to the beta2AR agonist terbutaline before activation by Ag-presenting B cells. Terbutaline exposure of Th1 cells before activation inhibited IFN-gamma production by Th1 cells and subsequent IgG2a production by B cells. IgG2a inhibition was prevented by addition of the betaAR antagonist nadolol or exogenous IFN-gamma. In contrast to Th1 cells, terbutaline did not affect either IL-4 production by Th2 cells or subsequent IgG1 production by B cells. Although baseline levels of intracellular cAMP were similar in both subsets, terbutaline induced an increase in cAMP levels in Th1 cells only. Radioligand binding studies showed that a detectable number of beta2AR binding sites were present on Th1 cells, but not on Th2 cells. Immunofluorescence analyses showed that Th1 cells expressed a higher level of the beta2AR cytoplasmic carboxyl terminus than did Th2 cells. These results show that expression of the beta2AR binding site by Th1 cells, but not by Th2 cells, establishes a physiologic mechanism for selective modulation of Th1 cell IFN-gamma production and IFN-gamma-dependent IgG2a production, provided that beta2AR stimulation occurs before cell activation by a B cell.