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La scintigraphie aux leucocytes marqués est considérée comme l’imagerie médicale la plus performante pour le diagnostic des infections ostéoarticulaires ou des tissus mous. Cependant, et en raison du métabolisme accru du glucose dans les tissus infectés, la TEP au 18F-FDG est fréquemment utilisée.

In contrast to beta(1)-adrenoreceptor (beta(1)-AR) signaling, beta(2)-AR stimulation in cardiomyocytes augments L-type Ca(2+) current in a cAMP-dependent protein kinase (PKA)-dependent manner but fails to phosphorylate phospholamban, indicating that the beta(2)-AR-induced cAMP/PKA signaling is highly localized. Here we show that inhibition of G(i) proteins with pertussis toxin (PTX) permits a full phospholamban phosphorylation and a de novo relaxant effect following beta(2)-AR stimulation, converting the localized beta(2)-AR signaling to a global signaling mode similar to that of beta(1)-AR. Thus, beta(2)-AR-mediated G(i) activation constricts the cAMP signaling to the sarcolemma. PTX treatment did not significantly affect the beta(2)-AR-stimulated PKA activation. Similar to G(i) inhibition, a protein phosphatase inhibitor, calyculin A (3 x 10(-8) M), selectively enhanced the beta(2)-AR but not beta(1)-AR-mediated contractile response. Furthermore, PTX and calyculin A treatment had a non-additive potentiating effect on the beta(2)-AR-mediated positive inotropic response. These results suggest that the interaction of the beta(2)-AR-coupled G(i) and G(s) signaling affects the local balance of protein kinase and phosphatase activities. Thus, the additional coupling of beta(2)-AR to G(i) proteins is a key factor causing the compartmentalization of beta(2)-AR-induced cAMP signaling.

Different structure and chemical composition of the insulating materials of medium voltage XLPE cables lead to various dielectric responses of new (unaged) cables and, therefore, can lead to problems in the diagnosis in the case of water tree aged medium voltage cables. With the aim of gaining a better understanding of these problems from a technical point of view, the results of dielectric response measurements in the time as well as in the frequency domain on different new XLPE homo- and copolymer insulated medium voltage cables and on a pressed sandwich-type test specimen before and after thermal treatment are presented and discussed. The investigations show that XLPE copolymer materials give higher dielectric responses than XLPE homopolymer materials. One of the reasons is that XLPE copolymer materials have a higher amount of polar, volatile elements (e.g. crosslinking byproducts), which lead especially to a higher voltage dependent conductivity.

Phospholamban (PLB), the regulator of the cardiac sarcoplasmic reticulum (SR) Ca2+ pump is specifically phosphorylated at Ser16 and Thr17 by cAMP-dependent protein kinase (PKA) and Ca2+/calmodulin-dependent protein kinase (CaMK), respectively. The regulation of this dual-site phosphorylation of amino acid residues in direct proximity is only poorly understood. In order to study the site-specific phosphorylation of PLB, we used a synthetic peptide (PLB-24) corresponding to the cytosolic part of the PLB monomer with the phosphorylation sites as a model substrate. PLB-24 possesses substrate properties as the native PLB as demonstrated by phosphorylation with exogenous, purified PKA, cGMP-dependent protein kinase (PKG) and a type II CaMK (CaMKII). In isolated vesicles of crdiac SR there was a rapid phosphorylation of the peptide by the endogenous PKA (SR-PKA) and CaMK (SR-CaMK), but not under conditions that activate PKG. Both SR-PKA and SR-CaMK incorporated the same amount of32P into PLB-24, 0.60±0.01 nmol32P/mg SR protein and 0.61±0.03 nmol32P/mg SR protein, respectively. Phosphorylation by SR-PKA was abolished by the specific PKA inhibitor (IC50=0.2µM), whereas SR-CaMK phosphorylation was inhibited by calmidazolium (IC50=1.6µM) and a CaMKII-specific inhibitor peptide (IC50=2.5µM). Phosphorylation by SR-PKA was exclusively at Ser, whereas SR-CaMK phosphorylated only Thr. After simultaneous activation of both SR-kinases32P incorporation into PLB-24 was additive and occurred at Ser as well as at Thr. Sequential activation of SR-PKA and SR-CaMK also caused the additive phosphorylation of PLB-24 independently of which kinase was activated first. Thus, at the monomeric level of PLB the respective phosphorylation site appears to be accessible to its related SR protein kinasein vitro even when the adjacent site is phosphorylated.