Role of regulator of G-protein signaling 2 (RGS2) in periodontal ligament cells under mechanical stress

Mechanical stress is thought to regulate the expression of genes in the periodontal ligament (PDL) cells. Using a microarray approach, we recently identified a regulator of G-protein signaling 2 (RGS2) as an up-regulated gene in the PDL cells under compressive force. The RGS protein family is known to turn off G-protein signaling. G-protein signaling involves the production of cAMP, which is thought to be one of the biological mediators in response to mechanical stress. Here, we investigated the role of RGS2 in the PDL cells under mechanical stress. PDL cells derived from the ligament tissues of human premolar teeth were cultured in collagen gels and subjected to static compressive force. Compressive force application time-dependently enhanced RGS2 expression and intracellular cAMP levels. To examine the interrelationship between RGS2 and cAMP, the PDL cells were treated with 2',5'-dideoxyadenosine (DDA), an inhibitor of adenyl cyclase, or antisense S-oligonucleotide (S-ODN) to RGS2 under compressive force. DDA dose-dependently inhibited RGS2 stimulated by compressive force. Blockage of RGS2 by antisense S-ODN elevated the cAMP levels compared with controls. These results indicate that cAMP stimulates RGS2 expression, which in turn leads to a decrease in the cAMP production by inactivating the G-protein signaling in the mechanically stressed PDL cells.     

Floodplain lake fish assemblages in the Amazon River: directions in conservation biology

The Neotropical region is renowned for its high biodiversity, and the Amazon River basin contains the highest number of fish species of any river system in the world. In recent years, habitat fragmentation and exploitation of biotic resources have threatened biological integrity and provoked to need for sustainable management and conservation of the Amazon River system. We studied 36 floodplain lakes along 2000 km of the Amazon River. The fish assemblages associated with flood forests are moderately diverse, with low species dominance and reduced populations. To detect nestedness of fish assemblage composition in floodplain lakes, a nested subset analysis was performed on species presence–absence. The incidence matrix (species × lakes) was maximally packed using the Nestedness Temperature Calculator software. The results of ranking lakes and species allow us to establish targets for conservation. Such strategy for sustainable management should be focused on maintaining the Amazonian biodiversity.     

Schistosoma mansoni infection enhances host portal vein contraction: role of potassium channels and p38 MAP kinase

Murine Schistosoma mansoni infection is related to an increased contraction of portal vein in response to 5-hydroxytryptamine (5-HT). The present study addressed a putative alteration of ion channels and enzymes involved in vascular contraction. In control group, either inhibition of K+ channels sensitive to ATP (K(ATP)) or Ca2+ (BK(Ca)) increased 5-HT-induced contraction, but the same did not occur in infected mice. On the other hand, inhibition of p38 MAP kinase markedly decreased the vascular contraction to 5-HT in the infected mice with minor effects in the control group. Accordingly, we observed a higher density of phospho-p38 MAP kinase, that refers to the fully active state of the enzyme, in portal veins from infected mice as compared to control animals. These results suggest that the reduced function of K(ATP) and BK(Ca) channels along with an increased contribution of p38 MAP kinase contribute to the increased contraction of portal veins to 5-HT observed in murine schistosomiasis.     

Air-pollutant chemicals and oxidized lipids exhibit genome-wide synergistic effects on endothelial cells

Background  

Ambient air pollution is associated with increased cardiovascular morbidity and mortality. We have found that exposure to ambient ultrafine particulate matter, highly enriched in redox cycling organic chemicals, promotes atherosclerosis in mice. We hypothesize that these pro-oxidative chemicals could synergize with oxidized lipid components generated in low-density lipoprotein particles to enhance vascular inflammation and atherosclerosis.     

Flow system for the automatic screening of the effect of phenolic compounds on the luminol–hydrogen peroxide–peroxidase chemiluminescence system

In this work, an automated flow‐based procedure for the screening of the effect of the different phenolic compounds on the chemiluminescence (CL) luminol–hydrogen peroxide–horseradish peroxidase (HRP) system is presented. This procedure involves the combination of multisyringe flow injection analysis (MFSIA) and sequential injection analysis (SIA) techniques and exploits the ability of the different subgroups of phenols, such as cholorophenols, nitrophenols, methylphenols and polyphenols, to enhance or inhibit the described CL system. The implementation of this reaction in the SIA–MSFIA system enabled favourable and precise conditions to evaluate the effect of phenolic compounds, as it involves an in‐line reaction between the phenolic derivative, hydrogen peroxide and peroxidase and subsequent oxidized HRP intermediates generation prior to the fast reaction with the chemiluminogenic reagent. Several studies were then performed with the aim of establishing the appropriate flow system configuration and reaction conditions. It was shown that phenol and chlorophenols produce an enhanced CL response and nitrophenols, methylphenols and polyphenols are inhibitors within the range of concentrations studied (1–100 mg/L). Based on these studies, the developed method was applied to the determination of total polyphenol and phenol content in wine/grape seeds and water samples, respectively, and the results obtained showed good agreement with those furnished by the corresponding Folin–Ciocalteu and 4‐aminoantipyrine reference methods. The developed approach is further pursued by designing an automated generic tool for performing studies of peroxidase‐catalysed CL reactions of luminol focused on the detection of compounds that will affect the rate of those reactions. Copyright © 2011 John Wiley & Sons, Ltd.     

Effect of some essential oils on in vitro methane emission

The objectives of this study were to characterise four essential oils (EO) chemically and to evaluate their effect on ruminal fermentation and methane emission in vitro. The investigated EO were isolated from Achillea santolina, Artemisia judaica, Schinus terebinthifolius and Mentha microphylla, and supplemented at four levels (0, 25, 50 and 75 microl) to 75 ml of buffered rumen fluid plus 0.5 g of substrate. The main components of the EO were piperitone (49.1%) and camphor (34.5%) in A. judaica, 16-dimethyl 15-cyclooactdaiene (60.5%) in A. santolina, piperitone oxide (46.7%) and cis-piperitone oxide (28%) in M. microphylla, and gamma-muurolene (45.3%) and alpha-thujene (16.0%) in S. terebinthifolius. The EO from A. santolina (at 25 and 50 j1), and all levels of A. judaica increased the gas production significantly, but S. terebinthifolius (at 50 and 75 microl), A. santolina (at 75 microl) and all levels of M. microphylla decreased the gas production significantly in comparison with the control. The highest levels of A. santolina and A. judaica, and all doses from M. microphylla EO inhibited the methane production along with a significant reduction in true degradation of dry matter and organic matter, protozoa count and NH3-N concentration. It is concluded that the evaluated EO have the potential to affect ruminal fermentation efficiency and the EO from M. microphylla could be a promising methane mitigating agent.     

Aporphine Alkaloids from Ocotea puberula with Anti-Trypanosoma Cruzi Potential – Activity of Dicentrine-β-N-Oxide in the Plasma Membrane Electric Potentials

One new aporphine, dicentrine-β-N-oxide ( 1 ), together with five related known alkaloids dehydrodicentrine ( 2 ), predicentrine ( 3 ), N-methyllaurotetanine ( 4 ), cassythicine ( 5 ), and dicentrine ( 6 ) were isolated from the leaves of Ocotea puberula (Lauraceae). Antiprotozoal activity of the isolated compounds was evaluated in vitro against trypomastigote forms of Trypanosoma cruzi. Among the tested compounds, alkaloid 1 exhibited higher potential with EC₅₀ value of 18.2 μM and reduced toxicity against NCTC cells (CC₅₀>200 μM – SI>11.0), similar to positive control benznidazole (EC₅₀ of 17.7 μM and SI=10.7). Considering the promising results of dicentrine-β-N-oxide ( 1 ) against trypomastigotes, the mechanism of parasite death caused by this alkaloid was investigated. As observed, this compound reached the plasma membrane electric potential directly after 2 h of incubation and triggered mitochondrial depolarization, which probably leads to trypomastigote death. Therefore, dicentrine-β-N-oxide ( 1 ), reported for the first time in this work, can contribute to future works for the development of new trypanocidal agents.