Geochemical signature of the bed sediments at the outlet of the Ibrahim River (Lebanon): temporal variation.

Bed sediments were collected monthly at the outlet of the Ibrahim River between May 2016 and July 2017. Their physical and chemical characteristics were studied to highlight the impact of seasonal variations and discharge on the sediments' geochemical signatures. Granulometric analysis showed that samples collected after rain events contained abundant sand fractions (> 80%), while the clay fraction was more present at the beginning of the dry season, at low monthly average flows (1 m3/s). Ten major elements, 14 rare earth elements (REE), and 30 trace elements (TE) were analyzed. An excess of CaO reflected the contribution of the carbonate rocks of the Ibrahim karstic springs (30.35 ± 3.91%) but CaO concentration decreased during periods of high water. On another hand, no REE enrichment was detected, both in high and low flows. Most sediments collected at low flow had a pronounced REE depletion that occurred particularly for LREE composition (Nd, Pr, Ce, and La). A negative Ce anomaly (0.992) and a positive Eu anomaly (1.313) were revealed with an average La/Yb ratio of 0.570, reflecting a slight enrichment in HREE. Most studied TE were less concentrated than the averages mentioned in PAAS, UCC, and WSA references. However, a Ze enrichment was mainly due to the regional geochemical background, an As enrichment was associated with anthropogenic contribution, and a Zr enrichment was linked to discharges from pharmaceutical industries located at the river outlet. This study still needs to be complemented binding both spatial and temporal criteria for further fluvial sediments' monitoring of the entire catchment area.

Water and sediment microbiota diversity in response to temporal variation at the outlet of the Ibrahim River (Lebanon).

Bacterial diversity is an important factor controlling the functioning of aquatic ecosystems. With the critical sensitivity of the microbial community towards chemical and/or physical factors, this study aims to identify for the first time the microbiota of the Lebanese coastal Ibrahim River. Water and sediment samples were collected at the outlet of the river, between May 2016 and April 2017, covering a hydrological year. The main microbiological parameters were tested: total germs, total coliforms, fecal coliforms, Escherichia coli, and Enterococcus. A DNA extraction followed by NGS analysis was applied on both water and sediment samples, in order to investigate the bacterial diversity and the habitat specificity. The link between this microbial composition and seasonal variations was then investigated. Results showed fourteen different bacterial phyla, among which were major microorganisms, including a wide variety of pathogenic and commensal ones, frequently available in the aquatic ecosystem. Most of the detected water microbiota were mostly correlated to other freshwater samples, with the main dominance of 5 common phyla: Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, and Acidobacteria with the average of 43%, 13%, 16%, 10%, and 4% respectively. Despite this overall similarity, multiple patterns were visible, confirming the influence of the temporal variations and the discharge influence on taxonomic diversity. Sediment samples contained the highest relative abundance of Proteobacteria, Firmicutes, and Bacteroidetes: with an average of 31%, 44%, and 22% respectively. Our study showed that the Ibrahim River outlet has a specific habitat clustering. The among-compartment bacterial community variation, which responded to changing environmental factors, approved the existence of a meaningful temporal heterogeneity.

Adenosine reduces the reverse mode of the Na+/Ca(2+) exchanger in ferret cardiac fibres.

The aim of this study was to investigate the effects of adenosine on reverse mode Na+/Ca(2+) exchange. In intact ferret cardiac trabeculae, Na+-free contractures were investigated after treating preparations with ryanodine, a sarcoplasmic reticulum Ca(2+) -channel inhibitor, and thapsigargin, a sarcoplasmic reticulum Ca(2+) -pump inhibitor added to suppress the sarcoplasmic reticulum function. The effects of adenosine (50-100 nmol/L), adenosine deaminase (ADA, 0.1-0.5 U/L), the A1 and A2A receptor agonists CCPA (3-100 nmol/L) and CGS 21680 (25-100 nmol/L), and the A1 and A2A receptor antagonists DPCPX (25 nmol/L) and ZM 241385 (25 nmol/L) were tested on Na+-free contractures. The application of adenosine (50-100 nmol/L) had no significant effect on the characteristics of the Na+-free contractures. However, the results show that treatment with ADA (0.3 U/L), adenosine (> or =50 nmol/L) and CCPA, a specific A1 receptor agonist (3-100 nmol/L), all reduced the Na+-free contracture amplitude. In the presence of ADA, the effects of adenosine and CCPA were also reduced by a specific antagonist of A1 receptors (DPCPX, 25 nmol/L). Furthermore, adenosine, ADA, and CCPA did not affect the properties of the contractile apparatus in Triton-skinned fibres. It is therefore proposed that endogenous adenosine reduced the reverse mode of the Na+/Ca(2+) exchanger by acting on A1 receptors present in the sarcolemmal membrane.

Electrophoresis PDMS/glass chips with continuous on-chip derivatization and analysis of amino acids using naphthalene-2,3-dicarboxaldehyde as fluorogenic agent.

In this work, we developed a PDMS electrophoresis device able to carry out on-chip derivatization and quantification of amino acids (AAs) using naphthalene-2,3-dicarboxaldehyde (NDA) as a fluorogenic agent. A chemical modification of the PDMS surface was found compulsory to achieve the derivatization of AAs with NDA and a limit of detection (LOD) of 40nM was reached for glycine. Finally, we suggested the applicability of this microdevice for the analysis of real biological samples such as a rat hippocampus microdialysate.

Ferutinin stability in human plasma and interaction with human serum albumin.

Ferutinin is a potent phytoestrogen extracted from plants of the genus Ferula. The biological activity of this sesquiterpene is associated with the esterification of p-hydroxybenzoic acid with the daucane alcohol, jaeschkeanadiol. A HPLC method was developed to investigate the stability of ferutinin in acidic and basic solutions (pH 1.5 and 9.0, respectively), in buffer (pH 7.4) as well as in serial dilutions of albumin and in human plasma. The degradation of ferutinin was relatively slow at physiological pH 7.4 compared with low or high pH. Ferutinin was fully stable in human plasma as well as in albumin solution and the stability increased with albumin concentration. The binding of ferutinin to albumin was investigated by fluorescence spectroscopy. Ferutinin decreased the fluorescence of HSA and that of the only tryptophan residue located in domain IIA. As a result of the interaction between ferutinin and albumin, the binding of bilirubin decreased. The stability of ferutinin in plasma is attributable to ferutinin-albumin binding.

Effect of cucurbitacins on bilirubin-albumin binding in human plasma.

The aim of this study is to investigate the effect of three cucurbitacins (Cuc) E, D and I on the bilirubin-albumin binding, both in human serum albumin (HSA) and in plasma. Bilirubin-HSA solution and plasma free of cucurbitacins were prepared as well as others containing serial concentrations of cucurbitacins. The concentration of unbound bilirubin was determined in bilirubin-HSA solution and the direct and total bilirubin concentrations were measured in plasma (with normal or elevated bilirubinemia) by Jendrassik and Grof method. In the conditions we adopted Cuc E and D (to a lesser extent), decreased the levels of unbound bilirubin in bilirubin-HSA solution and decreased direct bilirubin concentration and total bilirubin concentration in plasma in a dose-dependent manner while Cuc I had no effect. The effect of Cuc is related to the presence of native HSA. Thus, when albumin was absent or has been denatured by heating or by urea, Cuc E did not modify bilirubin levels, suggesting that the native structure of albumin is essential for such activity. The interaction of HSA with Cuc E was investigated by fluorescence spectroscopy. Cuc E increased the intrinsic fluorescence of the protein and the magnitude of fluorescence intensity of bilirubin-albumin complex. We concluded that Cuc E and D produced a rearrangement in the structure of albumin, particularly in the domain-II, resulting in an increase in the binding of bilirubin to albumin regardless to whether it's conjugated to glucuronic acid or unconjugated.

Adenosine affects the release of Ca2+ from the sarcoplasmic reticulum via A2A receptors in ferret skinned cardiac fibres.

In this study, it was shown that adenosine potentiates caffeine-induced Ca2+ release. It was then proposed that the enhancement of the caffeine-induced Ca2+ release might occur by a direct effect on the ryanodine Ca2+ release channel or on other Ca2+ regulation mechanisms. Furthermore, A2A receptors may be functional on the ferret cardiac sarcoplasmic reticulum. Using chemically skinned fibres, experiments were conducted on ferret cardiac muscle to find out whether adenosine and the A1 and A2A adenosine receptor agonists (CCPA and CGS 21680) and antagonists (DPCPX and ZM 241385) affected caffeine-induced Ca2+ release and the Ca2+ sensitivity of contractile proteins. Changes in the caffeine-induced contracture brought about by adenosine and by adenosine-receptor agonists and antagonists were recorded in saponin-skinned fibres (50 microg ml(-1)). Tension-pCa relationships were then obtained by exposing Triton X-100-skinned fibres (1% v/v) sequentially to solutions of decreasing pCa. Adenosine (1-100 nm) and the specific A2A receptor agonist CGS 21680 (1-50 nm) produced a concentration-dependant potentiation of the caffeine-induced Ca2+ release from saponin-skinned fibres. The data plotted versus adenosine and CGS 21680 concentrations displayed sigmoid relationships (Hill relationship), with potentiation of Ca2+ release by 22.2 +/- 1.6 (n = 6) and 10.9 +/- 0.4% (n = 6), respectively. In addition, the potentiation of caffeine-induced Ca2+ release by adenosine (50 nm; 15.3 +/- 1.0%; n = 6) and by CGS 21680 (50 nm; 11.2 +/- 0.4%; n = 6) was reduced by the specific A2A receptor antagonist ZM 241385 (50 nm) to 8.0 +/- 1.4 (n = 4) and 5.4 +/- 1.2% (n = 4), respectively. The A1 receptor agonist CCPA (1-50 nm) and antagonist DPCPX (50 nm) had no significant effects on caffeine responses. In Triton X-100-skinned fibres, the maximal Ca(2+)-activated tension of the contractile proteins (41.3 +/- 4.1 mN mm(-2); n = 8), the Hill coefficient (nH = 2.2 +/- 0.1; n = 8) and the pCa50 (6.15 +/- 0.05; n = 8) were not significantly modified by adenosine (100 nm) or by CGS 21680 (50 nm).