In vitro antimicrobial activity of propolis samples from different geographical origins against certain oral pathogens

Propolis is an agent having antimicrobial properties, however, its composition can vary depending on the area where it is collected. In the present study, the antimicrobial activity of five propolis samples, collected from four different regions in Turkey and from Brazil, against nine anaerobic strains was evaluated. Ethanol extracts of propolis (EEP) were prepared from propolis samples and we determined minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of EEP on the growth of test microorganisms by using agar dilution method. All strains were susceptible and MIC values ranged from 4 to 512 microg/ml for propolis activity. Propolis from Kazan-Ankara showed most effective MIC values to the studied microorganisms. MBC values of Kazan-Ankara EEP samples were ranged from 8 to 512 microg/ml. Death was observed within 4 h of incubation for Peptostreptococcus anaerobius and micros and Lactobacillus acidophilus and Actinomyces naeslundii, while 8 h for Prevotella oralis and Prevotella melaninogenica and Porphyromonas gingivalis, 12 h for Fusobacterium nucleatum, 16 h for Veillonella parvula. It was shown that propolis samples were more effective against Gram positive anaerobic bacteria than Gram negative ones. The organic chemical compositions of EEPs were determined by high-resolution gas chromatography coupled to mass spectrometry (GC-MS). The main compounds of EEPs were flavonoids such as pinobanksin, quercetin, naringenin, galangine, chrysin and aromatic acids such as cafeic acid. Because of increased antimicrobial resistance, propolis may be kept in mind in the treatment of oral cavity diseases.     

Nitric oxide inhibition of adenylyl cyclase type 6 activity is dependent upon lipid rafts and caveolin signaling complexes

Several cell types, including cardiac myocytes and vascular endothelial cells, produce nitric oxide (NO) via both constitutive and inducible isoforms of NO synthase. NO attenuates cardiac contractility and contributes to contractile dysfunction in heart failure, although the precise molecular mechanisms for these effects are poorly defined. Adenylyl cyclase (AC) isoforms type 5 and 6, which are preferentially expressed in cardiac myocytes, may be inhibited via a direct nitrosylation by NO. Because endothelial NO synthase (eNOS and NOS3), beta-adrenergic (betaAR) receptors, and AC6 all can localize in lipid raft/caveolin-rich microdomains, we sought to understand the role of lipid rafts in organizing components of betaAR-G(s)-AC signal transduction together with eNOS. Using neonatal rat cardiac myocytes, we found that disruption of lipid rafts with beta-cyclodextrin inhibited forskolin-stimulated AC activity and cAMP production, eliminated caveolin-3-eNOS interaction, and increased NO production. betaAR- and G(s)-mediated activation of AC activity were inhibited by beta-cyclodextrin treatment, but prostanoid receptor-stimulated AC activity, which appears to occur outside caveolin-rich microdomains, was unaffected unless eNOS was overexpressed and lipid rafts were disrupted. An NO donor, SNAP, inhibited basal and forskolin-stimulated cAMP production in both native cardiac myocytes and cardiac myocytes and pulmonary artery endothelial cells engineered to overexpress AC6. These effects of SNAP were independent of guanylyl cyclase activity and were mimicked by overexpression of eNOS. The juxtaposition of eNOS with betaAR and AC types 5 and 6 results in selective regulation of betaAR by eNOS activity in lipid raft domains over other G(s)-coupled receptors localized in nonraft domains. Thus co-localization of multiple signaling components in lipid rafts provides key spatial regulation of AC activity.     

P2Y2 and TrkA receptors interact with Src family kinase for neuronal differentiation

The crosstalk between the P2Y(2) G-protein-coupled receptor (GPCR) with TrkA receptor tyrosine kinase (RTK) is an important mechanism that regulates neuronal differentiation. We show that Src family kinases (SFK) regulate P2Y(2)-TrkA molecular crosstalk. SFK inhibitors block ATPgammaS/P2Y(2)-promoted enhancement of NGF/TrkA signaling and neuronal differentiation in PC12 cells, abrogate the enhancement by ATPgammaS of neurite outgrowth in primary cultures of dorsal root ganglion neurons, and block co-immunoprecipitation of TrkA, P2Y(2) receptors and SFK. These results identify SFK as mediating nucleotide-enhanced neurotrophin-dependent neuronal differentiation and thus, as a key convergence point for interaction between RTKs and GPCRs.     

Pharmacogenomics and personalized medicine in neuropsychiatry

Despite the need for more effective treatments for psychiatric disorders, development of new medications has stalled. Here we discuss the promise of personalized medicine in developing more efficacious and individualized pharmacotherapies that take into account genetic variation and target groups of patients who share biology, not just symptoms.     

Molecular mechanism of beta-adrenergic receptor blockers with intrinsic sympathomimetic activity

beta-Adrenergic receptor (beta AR) blocking agents with intrinsic sympathomimetic activity (ISA) can induce modest increases in beta AR-stimulated activity, such as rate and force of contraction in cardiac tissue. The molecular basis for this activity has been elusive. Previous studies have suggested that these compounds do not stimulate cyclic AMP (cAMP) formation even though activation of adenylate cyclase is the generally accepted mechanism for beta AR promotion of target cell response. In the current studies, we show that several beta AR antagonists with ISA (dichloroisoproterenol, pindolol, and celiprolol) stimulate cAMP accumulation five-, two-, and threefold, respectively, in S49 lymphoma cells, but only if cells are simultaneously incubated with the diterpene forskolin. The KI values observed for inhibition of isoproterenol-stimulated cAMP accumulation or of beta AR [( 125I]iodocyanopindolol) binding for each of the beta blockers with ISA were comparable in magnitude to their respective EC50 values for forskolin-potentiated cAMP accumulation. The forskolin-potentiated responses of these compounds were abolished by the beta AR-antagonist propranolol. These results indicate that the ISA of beta-blocking drugs most likely results from a modest beta AR-mediated stimulation of adenylate cyclase activity. The results further suggest that treatment of target cells with forskolin provides a means to define partial agonism at receptors that are linked to stimulation of adenylate cyclase.     

Replacement of serum with a defined medium increases beta-adrenergic receptor number in cultured glioma cells

Lymphocyte chromosomes from a cercopithecoid species, Macaca mulatta, were studied for the occurrence of lateral asymmetry in constitutive heterochromatin. The technique consisted of growing the lymphocytes for one cell cycle in BrdUrd, staining with 33258 Hoechst, exposing them to UV light, treating them with 2 SSC and staining with Giemsa. This procedure revealed asymmetric staining in the region of constitutive heterochromatin of the nucleolar organizer marker chromosome (no. 13 of the complement). In these chromosomes, the darkly staining region was confined at any given point to a single chromatid, while the corresponding region on the sister chromatid was lightly stained. This pattern of asymmetric staining in the constitutive heterochromatic region was not observed in any other chromosome of Macaca mulatta. The lateral asymmetry of constitutive heterochromatin in this species is presumed to reflect the strand bias in the distribution of thymine in the alphoid DNA fractions.