CaMKIV/CREB/BDNF signaling pathway expression in prefrontal cortex, amygdala, hippocampus and hypothalamus in streptozotocin-induced diabetic mice with anxious-like behavior.

Individuals with diabetes mellitus (DM) tend to manifest anxiety and depression, which could be related to changes in the expression of calcium/calmodulin-dependent protein kinase IV (CaMKIV), transcription factor cyclic AMP-responsive element binding protein (CREB), phosphorylated CREB (pCREB) and brain-derived neurotrophic factor (BDNF) in different brain regions. The objective of this study was to determine whether mice with type 1 diabetes (T1DM) induced with streptozotocin show a profile of anxious-type behaviors and alterations in the expression/activity of CaMKIV, CREB, pCREB and BDNF in different regions of the brain (prefrontal cortex, amygdala, hippocampus and hypothalamus) in comparison to non-diabetic mice (NDB). Mice with 3 months of chronic DM showed an anxious-like behavioral profile in two anxiety tests (Open Field and Elevated Plus Maze), when compared to NDB. There were significant differences in the expression of cell signaling proteins: diabetic mice had a lower expression of CaMKIV in the hippocampus, a greater expression of CREB in the amygdala and hypothalamus, as well as a lower pCREB/CREB in hypothalamus than NDB mice (P < 0.05). This is the first study evaluating the expression of CaMKIV in the brain of animals with DM, who presented lower expression of this protein in the hippocampus. In addition, it is the first time that CREB was evaluated in amygdala and hypothalamus of animals with DM, who presented a higher expression. Further research is necessary to determine the possible link between expression of CaMKIV and CREB, and the behavioral profile of anxiety in diabetic animals.

Atomic Force Microscopy to Study the Physical Properties of Epidermal Cells of Live Arabidopsis Roots.

A method is described here to characterize the physical properties of the cell wall of epidermal cells of living Arabidopsis roots through nanoindentations with an atomic force microscope (AFM) coupled with an optical inverted fluorescence microscope. The method consists of applying controlled forces to the sample while measuring its deformation, allowing quantifying parameters such as the apparent Young's modulus of cell walls at subcellular resolutions. It requires a careful mechanical immobilization of the sample and correct selection of indenters and indentation depths. Although it can be used only in external tissues, this method allows characterizing mechanical changes in plant cell walls during development and enables the correlation of these microscopic changes with the growth of an entire organ.

Bioactive compounds, antioxidant capacity and antitumoral activity of ethanolic extracts from fruits and seeds of Eugenia involucrata DC.

Eugenia involucrata DC. (Myrtaceae) is a native tree species from Brazil that has been scarcely studied. We investigated the phenolic composition, the antioxidant capacity and the antitumoral activity of ethanolic extracts from fruits (FE) and seeds (SE) of E. involucrata. Six anthocyanins were identified by UPLC-PDA/MS/MS in FE, being four derived from cyanidin, and the other ones derived from delphinidin and pelargonidin. Using HPLC-PDA, FE presented a larger number of phenolic compounds (epicatechin, catechin, rutin, ellagic acid, myricetin and quercetin) than SE, which did not show myricetin and quercetin. However, SE showed higher total phenolic content and generally stronger in vitro antioxidant capacity than FE, except that only FE exhibited superoxide radical scavenging activity, which may be attributed to the anthocyanins present in fruits. Additionally, only SE exhibited antitumoral activity in a pancreatic cancer cell line (PANC-1). The antitumoral mechanisms involved imbalance of antioxidant status, alteration of mitochondrial membrane potential, cytoskeleton disassembly and induction of cell death by apoptosis and necrosis. Compared to the standard antitumoral drug gemcitabine, SE exhibited higher antitumoral efficacy and selectivity index. The highest concentration of total phenolics and of specific phenolic compounds bearing antitumoral properties may be related to the antitumoral activity of SE. Our results corroborate previous data of E. involucrata as an important source of bioactive compounds and provide, for the first time, evidences of in vitro antitumoral potential of its seeds on pancreatic cancer cell line.

Evaluation of chromosomal aberrations induced by 188Re-dendrimer nanosystem on B16f1 melanoma cells.

PURPOSE: To study the rhenium-188 labeling of polyamidoamine (PAMAM) generation 4 (G4) dendrimer and its evaluation on biodistribution and chromosomal aberrations in melanoma cells induced by ionizing radiation as potential treatment agent. MATERIALS AND METHODS: Dendrimers were first conjugated with Suc-HYNIC (succinimidyl 6-hydrazinopyridine-3-carboxylic acid hydrochloride). Dendrimer-HYNIC was then incubated with 188ReO4-. Biodistribution was performed administrating 188Re-dendrimer to normal (NM) or melanoma-bearing mice (MBM). Chromosome aberration test was conducted in order to measure treatment capacity of 188Re-dendrimer in melanoma cells. RESULTS: Radiolabeling yield of dendrimer was approx. 70%. Biodistribution studies in NM showed blood clearance with hepatic and renal depuration. MBM showed a similar pattern of biodistribution with tumor uptake of 6% of injected dose. Aberrant metaphases quantified in control cells were 7%, increasing to 29.5% in cells treated with 15µCi (0.555 MBq) of 188Re-dendrimer for 24 h. CONCLUSIONS: 188Re-dendrimer can produce double-stranded breaks in DNA induced by ionizing radiation in melanoma cells in vitro.

In vitro and in vivo uptake studies of PAMAM G4.5 dendrimers in breast cancer.

BACKGROUND: Breast cancer is the second leading cause of cancer death worldwide. Nanotechnology approaches can overcome the side effects of chemotherapy as well as improve the efficacy of drugs. Dendrimers are nanometric size polymers which are suitable as drug delivery systems. To the best of our knowledge, studies on the application of PAMAM G4.5 (polyamidoamine half generation 4) dendrimers as potential drug delivery systems in breast cancer have not been reported. In this work we developed a PAMAM G4.5 dendrimer containing FITC (fluorescein isothiocyanate) dye to study their uptake by murine breast cancer cells and BALB/c mice breast tumors. RESULTS: We performed a reaction between FITC and PAMAM G4.5 dendrimers which were previously derivatized with piperazine (linker molecule), characterized them by (1)H NMR (proton nuclear magnetic resonance) spectroscopy and MALDI-TOF (matrix-assisted laser desorption/ionization- time-of-flight) mass spectrometry. The experimental data indicated that 2 FITC molecules could be bound covalently at the PAMAM G4.5 dendrimer surface, with 17 FITC molecules probably occluded in PAMAM dendrimers cavity. PAMAM-FITC dendrimer (PAMAM G4.5-piperazinyl-FITC dendrimer) size distribution was evaluated by DLS (dynamic light scattering) and TEM (transmission electron microscopy). The nanoparticle hydrodynamic size was 96.3 ± 1.4 nm with a PdI (polydispersion index) of 0.0296 ± 0.0171, and the size distribution measured by TEM was 44.2 ± 9.2 nm. PAMAM-FITC dendrimers were neither cytotoxic in 4T1 cells nor hemolytic up to 24 h of incubation. In addition, they were uptaken in vitro by 4T1 cells and in vivo by BALB/c mice breast tumors. PAMAM G4.5-piperazinyl-FITC dendrimer intracellular distribution was observed through histologic analysis of the tumor by laser confocal microscopy. CONCLUSION: These results indicate that PAMAM G4.5 dendrimers enter tumor tissue cells, being good candidates to be used as antitumor drug delivery systems for breast cancer treatment and diagnosis.

Regulation of SIRT 1 mediated NAD dependent deacetylation: a novel role for the multifunctional enzyme CD38.

The SIRT 1 enzyme is a NAD dependent deacetylase implicated in ageing, cell protection, and energy metabolism in mammalian cells. How the endogenous activity of SIRT 1 is modulated is not known. The enzyme CD38 is a multifunctional enzyme capable of synthesis of the second messenger, cADPR, NAADP, and ADPR. However, the major enzymatic activity of CD38 is the hydrolysis of NAD. Of particular interest is the fact that CD38 is present on the inner nuclear membrane. Here, we investigate the modulation of the SIRT 1 activity by CD38. We propose that by modulating availability of NAD to the SIRT1 enzyme, CD38 may regulate SIRT1 enzymatic activity. We observed that in CD38 knockout mice, tissue levels of NAD are significantly increased. We also observed that incubation of purified recombinant SIRT1 enzyme with CD38 or nuclear extracts of wild-type mice led to a significant inhibition of its activity. In contrast, incubation of SIRT1 with cellular extract from CD38 knockout mice was without effect. Furthermore, the endogenous activity of SIRT1 was several time higher in nuclear extracts from CD38 knockout mice when compared to wild-type nuclear extracts. Finally, the in vivo deacetylation of the SIRT1 substrate P53 is increased in CD38 knockout mice tissue. Our data support the novel concept that nuclear CD38 is a major regulator of cellular/nuclear NAD level, and SIRT1 activity. These findings have strong implications for understanding the basic mechanisms that modulate intracellular NAD levels, energy homeostasis, as well as ageing and cellular protection modulated by the SIRT enzymes.

Relationship between RNA synthesis and the Ca2+-filled state of the nuclear envelope store.

RNA synthesis and ATP-dependent (45)Ca(2+) uptake were measured simultaneously in isolated nuclear fraction of rat liver nuclei. Maximal level of RNA synthesis was obtained under ATP-dependent (45)Ca(2+)-uptake conditions (1 microM free [Ca(2+)] and 1 mM ATP in the bathing solution). This experimental condition was defined as "stimulated nuclei" condition. ATP-dependent (45)Ca(2+) uptake was inhibited using different strategies including: (a) eliminating Ca(2+) (1 mM EGTA); (b) lowering the ATP concentration; (c) modifying nuclear envelope membranes Ca(2+) permeability (Ca(2+) ionophores); or (d) inhibiting the nuclear Ca(2+) pump (thapsigargin and 3',3'',5',5''-tetraiodophenolsulfonephthalein). Under all the above conditions, RNA synthesis was lower than in "stimulated nuclei" condition. In the presence of ionomycin, RNA synthesis was significantly higher at 500 nM free [Ca(2+)], as compared with RNA synthesis in a Ca(2+)-free medium or at 1muM free [Ca(2+)]. However, even in such condition (500 nM free [Ca(2+)]), RNA synthesis was lower than RNA synthesis obtained in "stimulated nuclei" condition. We suggest two components for the effect of Ca(2+) on RNA synthesis: (A) a direct effect of nucleoplasmic [Ca(2+)]; and (B) an effect dependent on the accumulation of Ca(2+) in the nuclear envelope store mediated by the SERCA nuclear Ca(2+) pump.