Spectroelectrochemical study of complexes [Mo(CO)2(h3-allyl)(adiimine)(NCS)] (a-diimine ¼ bis(2,6-dimethylphenyl)- acenaphthenequinonediimine and 2,20-bipyridine) exhibiting different molecular structure and redox reactivity

The redox properties and reactivity of [Mo(CO)2(η3-allyl)(α-diimine)(NCS)] (α-diimine = bis(2,6-dimethylphenyl)-acenaphthenequinonediimine (2,6-xylyl-BIAN) and 2,2′-bipyridine (bpy)) were studied using cyclic voltammetry and IR/UV–Vis spectroelectrochemistry. [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(NCS)] was shown by X-ray crystallography to have an asymmetric (B-type) conformation. The extended aromatic system of the strong π-acceptor 2,6-xylyl-BIAN ligand stabilises the primary 1e−-reduced radical anion, [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN•−)(NCS)]−, that can be reduced further to give the solvento anion [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(THF)]−. The initial reduction of [Mo(CO)2(η3-allyl)(bpy)(NCS)] in THF at ambient temperature results in the formation of [Mo(CO)2(η3-allyl)(bpy)]2 by reaction of the remaining parent complex with [Mo(CO)2(η3-allyl)(bpy)]− produced by dissociation of NCS− from [Mo(CO)2(η3-allyl)(bpy•−)(NCS)]−. Further reduction of the dimer [Mo(CO)2(η3-allyl)(bpy)]2 restores [Mo(CO)2(η3-allyl)(bpy)]−. In PrCN at 183 K, [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN•−)(NCS)]− converts slowly to 2e−-reduced [Mo(CO)2(η3-allyl)(2,6-xylyl-BIAN)(PrCN)]− and free NCS−. At room temperature, the reduction path in PrCN involves mainly the dimer [Mo(CO)2(η3-allyl)(bpy)]2; however, the detailed course of the reduction within the spectroelectrochemical cell is complicated and involves a mixture of several unassigned products. Finally, it has been shown that the five-coordinate anion [Mo(CO)2(η3-allyl)(bpy)]− promotes in THF reduction of CO2 to CO and formate via the formation of the intermediate [Mo(CO)2(η3-allyl)(bpy)(O2CH)] and its subsequent reduction.

Electrocatalytic reduction of carbon dioxide with a manganese(I)tricarbonyl complex containing a nonaromatic α‑diimine ligand

The 2e reduced anion [Mn(CO)3(iPr-DAB)]− (DAB = 1,4- diazabuta-1,3-diene, iPr = isopropyl) was shown to convert in the presence of CO2 and a small amount of water to the unstable complex [Mn(CO)3(iPr-DAB)(η1-OCO2H)] (OCO2H− = unidentate bicarbonate) that was further reductively transformed to give a stable catalytic intermediate denoted as X2, showing νs(OCO) 1672 and 1646 (sh) cm−1. The subsequent cathodic shift by ca. 650 mV in comparison to the single 2e cathodic wave of the parent [Mn(CO)3(iPr-DAB)Br] triggers the reduction of intermediate X2 and catalytic activity converting CO2 to CO. Infrared spectroelectrochemistry has revealed that the high excess of CO generated at the cathode leads to the conversion of [Mn(CO)3(iPr-DAB)]− to inactive [Mn(CO)5]−. In contrast, the five-coordinate anion [Mn(CO)3(pTol-DAB)]−(pTol = 4-tolyl) is completely inert toward both CO2 and H2O (solvolysis). This detailed spectroelectrochemical study is a further contribution to the development of sustainable electro- and photoelectrocatalysts of CO2 reduction based on abundant first-row transition metals, in particular manganese.

High-temperature order–disorder transitions in the skutterudites CoGe1.5Q1.5 (Q=S, Te)

The temperature dependence of anion ordering in the skutterudites CoGe1.5Q1.5 (Q=S, Te) has been investigated by powder neutron diffraction. Both materials adopt a rhombohedral structure at room temperature (space group R-3 ) in which the anions are ordered trans to each other within Ge2Q2 rings. In CoGe1.5S1.5, anion ordering is preserved up to the melting point of 950 °C. However, rhombohedral CoGe1.5Te1.5 undergoes a phase transition at 610 °C involving a change to cubic symmetry (space group Im-3). In the high-temperature modification, there is a statistical distribution of anions over the available sites within the Ge2Te2 rings. The structural transition involves a reduction in the degree of distortion of the Ge2Te2 rings which progressively transform from a rhombus to a rectangular shape. The effect of this transition on the thermoelectric properties has been investigated.

Molecular targets of cannabidiol in neurological disorders

Cannabis has a long history of anecdotal medicinal use and limited licensed medicinal use. Until recently, alleged clinical effects from anecdotal reports and the use of licensed cannabinoid medicines are most likely mediated by tetrahydrocannabinol by virtue of: 1) this cannabinoid being present in the most significant quantities in these preparations; and b) the proportion:potency relationship between tetrahydrocannabinol and other plant cannabinoids derived from cannabis. However, there has recently been considerable interest in the therapeutic potential for the plant cannabinoid, cannabidiol (CBD), in neurological disorders but the current evidence suggests that CBD does not directly interact with the endocannabinoid system except in vitro at supraphysiological concentrations. Thus, as further evidence for CBD’s beneficial effects in neurological disease emerges, there remains an urgent need to establish the molecular targets through which it exerts its therapeutic effects. Here, we conducted a systematic search of the extant literature for original articles describing the molecular phar- macology of CBD. We critically appraised the results for the validity of the molecular targets proposed. Thereafter, we considered whether the molecular targets of CBD identified hold therapeutic potential in relevant neurological diseases. The molecular targets identified include numerous classical ion channels, receptors, transporters, and enzymes. Some CBD effects at these targets in in vitro assays only manifest at high concentrations, which may be difficult to achieve in vivo, particularly given CBD’s relatively poor bioavailability. Moreover, several targets were asserted through experimental designs that demonstrate only correlation with a given target rather than a causal proof. When the molecular targets of CBD that were physiologically plausible were considered for their potential for exploitation in neurological therapeu- tics, the results were variable. In some cases, the targets identified had little or no established link to the diseases considered. In others, molecular targets of CBD were entirely consistent with those already actively exploited in relevant, clinically used, neurological treatments. Finally, CBD was found to act upon a number of targets that are linked to neurological therapeutics but that its actions were not consistent with modulation of such targets that would derive a therapeutically beneficial outcome. Overall, we find that while >65 discrete molecular targets have been reported in the literature for CBD, a relatively limited number represent plausible targets for the drug’s action in neurological disorders when judged by the criteria we set. We conclude that CBD is very unlikely to exert effects in neurological diseases through modulation of the endocannabinoid system. Moreover, a number of other molecular targets of CBD reported in the literature are unlikely to be of relevance owing to effects only being observed at supraphysiological concentrations. Of interest and after excluding unlikely and implausible targets, the remaining molecular targets of CBD with plausible evidence for involvement in therapeutic effects in neurological disorders (e.g., voltage-dependent anion channel 1, G protein-coupled receptor 55, CaV3.x, etc.) are associated with either the regulation of, or responses to changes in, intracellular calcium levels. While no causal proof yet exists for CBD’s effects at these targets, they represent the most probable for such investigations and should be prioritized in further studies of CBD’s therapeutic mechanism of action.

The p38-MAPK inhibitor, SB203580, inhibits cardiac stress-activated protein kinases/c-Jun N-terminal kinases (SAPKs/JNKs).

SB203580 is a recognised inhibitor of p38-MAPKs. Here, we investigated the effects of SB203580 on cardiac SAPKs/JNKs. The IC50 for inhibition of p38-MAPK stimulation of MAPKAPK2 was approximately 0.07 microM, whereas that for total SAPK/JNK activity was 3-10 microM. SB203580 did not inhibit immunoprecipitated JNK1 isoforms. Three peaks of SAPK/JNK activity were separated by anion exchange chromatography, eluting in the isocratic wash (44 kDa), and at 0.08 M (46 and 52 kDa) and 0.15 M NaCl (54 kDa). SB203580 (10 microM) completely inhibited the 0.15 M NaCl activity and partially inhibited the 0.08 M NaCl activity. Since JNK1 antibodies immunoprecipitate the 46 kDa activity, this indicates that SB203580 selectively inhibits 52 and 54 kDa SAPKs/JNKs.

Regulation of Multidrug Resistance-Associated Protein 2 by Calcium Signaling in Mouse Liver

Mu hiding resistance associated protein 2 (Mrp2) is a canalicular transporter responsible for organic anion secretion into bile. Mrp2 activity is regulated by insertion into the plasma membrane; however, the factors that control this are not understood. Calcium (Ca(2+)) signaling regulates exocytosis of vesicles in most cell types, and the type II inositol 1,4,5-triphosphate receptor (InsP(3)R2) regulates Ca(2+) release in the canalicular region of hepatocytes. However, the role of InsP(3)R2 and of Ca(2+) signals in canalicular insertion and function of Mrp2 is not known. The aim of this study was to determine the role of InsP(3)R2-mediated Ca(2+) signals in targeting Mrp2 to the canalicular membrane. Livers, isolated hepatocytes, and hepatocytes in collagen sandwich culture from wild-type (WT) and InsP(3)R2 knockout (KO) mice were used for western blots, confocal immunofluorescence, and time-lapse imaging of Ca(2+) signals and of secretion of a fluorescent organic anion. Plasma membrane insertion of green fluorescent protein (GFP)-Mrp2 expressed in HepG2 cells was monitored by total internal reflection microscopy. InsP(3)R2 was concentrated in the canalicular region of WT mice but absent in InsP(3)R2 KO livers, whereas expression and localization of InsP(3)R1 was preserved, and InsP(3)R3 was absent from both WT and KO livers. Ca(2+) signals induced by either adenosine triphosphate (ATP) or vasopressin were impaired in hepatocytes lacking InsP(3)R2. Canalicular secretion of the organic anion 5-chloromethylfluorescein diacetate (CMFDA) was reduced in KO hepatocytes, as well as in WT hepatocytes treated with 1,2-bis(o-aminophenoxy)ethane-N,N,N`,N`-tetra-acetic acid (BAPTA). Moreover, the choleretic effect of tauroursodeoxycholic acid (TUDCA) was impaired in InsP(3)R2 KO mice. Finally, ATP increased GFP-Mrp2 fluorescence in the plasma membrane of HepG2 cells, and this also was reduced by BAPTA. Conclusion: InsP(3)R2-mediated Ca(2+) signals enhance organic anion secretion into bile by targeting Mrp2 to the canalicular membrane. (HEPATOLOGY 2010;52:327-337)

Reactive oxygen and nitrogen species balance in the determination of thyroid hormones-induced cardiac hypertrophy mediated by renin-angiotensin system

Role of reactive oxygen species (ROS)/nitric oxide (NO) balance and renin-angiotensin system in mediating cardiac hypertrophy in hyperthyroidism was evaluated in an in vivo and in vitro experimental model. Male Wistar rats were divided into four groups: control, thyroid hormone, vitamin E (or Trolox, its hydrosoluble analogue), thyroid hormone + vitamin E. Angiotensin II receptor (AT1/AT2) gene expression, immunocontent of AT1/AT2 receptors, angiotensinogen, NADPH oxidase (Nox2), and nitric oxide synthase isoforms, as well as ROS concentration (hydrogen peroxide and superoxide anion) were quantified in myocardium. Thyroid hormone increased ROS and NO metabolites, iNOS, nNOS and eNOS isoforms and it was accompanied by cardiac hypertrophy. AT1/AT2 expression and the immunocontent of angiotensinogen and Nox2 were enhanced by thyroid hormone. Antioxidants reduced ROS levels, Nox2, AT1/AT2, NOS isoforms and cardiac hypertrophy. In conclusion, ROS/NO balance may play a role in the control of thyroid hormone-induced cardiac hypertrophy mediated by renin-angiotensin system. (C) 2011 Elsevier Ireland Ltd. All rights reserved.

Modulation of rat neutrophil function in vitro by cis- and trans-MUFA

In the present study, the effects of trans-MUFA, elaidic acid (EA; 18 : 1-9t) and vaccenic acid (VA; 18 : 1-11t) on rat neutrophil functions were compared with those of cis-monounsaturated oleic acid (OA) (18 : 1-9c) and saturated stearic acid (SA; 18 : 0) (10-150 mu M). Trans-fatty acids enhanced neutrophil phagocytic capacity, superoxide (O(2)(center dot-)) and hydrogen peroxide production, and candidacidal activity. The same effects were observed for OA. Cells treated with trans-MUFA showed reduced production of NO(center dot), whereas those treated with OA showed an increase in production. Treatment with SA did not provoke significant effect on the parameters investigated. The increase in O(2)(center dot-) production induced by MUFA was not observed when diphenyleneiodonium, an NADPH oxidase inhibitor, was added to the medium. This finding suggests that MUFA stimulate neutrophil NADPH oxidase activity. The addition of 3-[1-[3-(dimethylamino)propyl]-1H-indol-3-yl]-4-(1H-inclol-3-yl)-1H-pyrrole-2,5-dione, a protein kinase C (PKC) inhibitor, and wortmannin, a phosphatidylinositol-3 kinase (PI3K) inhibitor, did not affect O(2)(center dot-) production induced by MUFA. Therefore, the mechanisms by which MUFA stimulate NADPH oxidase are not dependent on PKC and do not seem to involve PI3K. Experiments using Zn(2+), an inhibitor of NADPH oxidase H(+) channel, indicated that MUFA activate the NADPH oxidase complex in rat neutrophil due to opening of H(+) channel.

Effects of the cationic antimicrobial peptide eumenitin from the venom of solitary wasp Eumenes rubronotatus in planar lipid bilayers: Surface charge and pore formation activity

Eumenitin, a novel cationic antimicrobial peptide from the venom of solitary wasp Eumenes rubronotatus, was characterized by its effects on black lipid membranes of negatively charged (azolectin) and zwitterionic (1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) or DPhPC-cholesterol) phospholipids: surface potential changes, single-channel activity, ion selectivity, and pore size were studied. We found that eumenitin binds preferentially to charged lipid membranes as compared with zwitterionic ones. Eumenitin is able to form pores in azolectin (G(1) = 118.00 +/- 3.67 pS or G(2) = 160.00 +/- 7.07 pS) and DPhPC membranes (G = 61.13 +/- 7.57 pS). Moreover, cholesterol addition to zwitterionic DPhPC membranes inhibits pore formation activity but does not interfere with the binding of peptide. Open pores presented higher cation (K (+)) over anion (Cl-) selectivity. The pore diameter was estimated at between 8.5and 9.8 angstrom in azolectin membranes and about 4.3 angstrom in DPhPC membranes. The results are discussed based on the toroidal pore model for membrane pore-forming activity and ion selectivity. (c) 2007 Elsevier Ltd. All rights reserved.

Acid-base transport by the renal distal nephron

The functional versatility of the distal nephron is mainly due to the large cytological heterogeneity of the segment. Part of Na(+) uptake by distal tubules is dependent on Na(+)/H(+). exchanger 2 (NHE2), implicating a role of distal convoluted cells also in acid-base homeostasis. In addition, intercalated (IC) cells expressed in distal convoluted tubules, connecting tubules and collecting ducts are involved in the final regulation of acid-base excretion. IC cells regulate acid-base handling by 2 main transport proteins, a V-type H(+)-ATPase and a Cl/HCO(3)(-) exchanger, localized at different membrane domains. Type A IC cells are characterized by a luminal H(+)-ATPase in series with a basolateral Cl/HCO(3)(-) exchanger, the anion exchanger AE1. Type B IC cells mediate HCO(3)(-) secretion through the apical Cl(-)/HCO(3)(-) exchanger pendrin in series with a H(+)-ATPase at the basolateral membrane. Alternatively, H(+)/K(+)-ATPases have also been found in several distal tubule cells, particularly in type A and B IC cells. All of these mechanisms are finely regulated, and mutations of 1 or more proteins ultimately lead to expressive disorders of acid-base balance.

Oxidative stress and inflammatory mediators contribute to endothelial dysfunction in high-fat diet-induced obesity in mice

Objective We investigated the effects of high-fat diet-induced obesity on vascular proinflammatory factors and oxidative stress on endothelium-dependent relaxation of the aorta. Methods Female Swiss mice were submitted to a high-fat diet for 16 weeks. At the end of the experimental period, we evaluated blood pressure, relaxation in response to acetylcholine in aortic rings in the absence and the presence of the superoxide anion scavenger, superoxide dismutase (SOD, 150 U/ml), and the nuclear factor (NF)-kappa B inhibitor, sodium salicylate (5 mmol/l). Aortic protein expression of endothelial nitric oxide synthase, Cu/Zn-SOD, NF-kappa B, I kappa B-alpha, and proinflammatory cytokines were also evaluated. Results Obese mice presented higher systolic and diastolic blood pressure than control mice (P<0.05). The relaxation of aortas to acetylcholine, but not to sodium nitroprusside, was significantly decreased in obese mice and was corrected by both SOD and sodium salicylate (P<0.05). The protein expression of endothelial nitric oxide synthase and Cu/Zn-SOD was significantly decreased in aorta from obese mice (P<0.05). Total p65 NF-kappa B subunit protein expression was not affected by obesity, but the protein expression of NF-kappa B inhibitor I kappa B-alpha was lower in aorta from obese mice (P<0.05). There were no significant differences in the interleukin (IL)-1 beta and IL-6 protein expression between groups. In contrast, the expression of TNF-alpha was significantly increased in aortas from obese mice. Conclusion Our resultssuggest that the reducedantioxidant defense and the local NF-kappa B pathway play an important role in the impairment of endothelium-dependent relaxation in aorta from obese mice. J Hypertens 28: 2111-2119 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Testosterone suppresses oxidative stress in human neutrophils

The in vitro effect of testosterone on human neutrophil function was investigated. Blood neutrophils from healthy male subjects were isolated and treated with 10 nM, 0.1 and 10 mu M testosterone for 24 h. As compared with untreated cells, the testosterone treatment produced a significant decrease of superoxide production as indicated by the measurement of extra- and intracellular superoxide content. An increment in the production of nitric oxide was observed at 0.1 and 10 mu M testosterone concentrations, whereas no effect was found for 10 nM. Intracellular calcium mobilization was significantly increased at 10 nM, whereas it was reduced at 10 mu M testosterone. There was an increase in phagocytic capacity at 10 nM and a decrease of microbicidal activity in neutrophils treated with testosterone at 10 mu M. Glutathione reductase activity was increased by testosterone treatment, whereas no effect was observed in other antioxidant enzyme activities. An increase in the content of thiol groups was observed at all testosterone concentrations. Lipid peroxidation in neutrophils evaluated by levels of TBARS was decreased at 10 nM and 0.1 mu M testosterone. These results indicate the antioxidant properties of testosterone in neutrophils as suggested by reduction of superoxide anion production, and lipid peroxidation, and by the increase in nitric oxide production, glutathione reductase activity and the content of thiol groups. Therefore, the plasma levels of testosterone are important regulators of neutrophil function and so of the inflammatory response. Copyright (C) 2010 John Wiley & Sons, Ltd.

Effect of chronic supplementation with shark liver oil on immune responses of exercise-trained rats

Previous studies have reported that chronic supplementation with shark liver oil (SLO) improves immune response of lymphocyte, macrophage and neutrophil in animal models and humans. In a similar manner, exercise training also stimulates the immune system. However, we are not aware of any study about the association of exercise and SLO supplementation on immune response. Thus, our main goal was to investigate the effect of chronic supplementation with SLO on immune responses of exercise-trained rats. Male Wistar rats were divided into four groups: sedentary with no supplementation (SED, n = 20), sedentary with SLO supplementation (SEDslo, n = 20), exercised (EX, n = 17) and exercised supplemented with SLO (EXslo, n = 19). Rats swam for 6 weeks, 1.5 h/day, in water at 32 +/- A 1A degrees C, with a load of 6.0% body weight attached to the thorax of rat. Animals were killed 48 h after the last exercise session. SLO supplementation did not change phagocytosis, lysosomal volume, superoxide anion and hydrogen peroxide production by peritoneal macrophages and blood neutrophils. Thymus and spleen lymphocyte proliferation were significantly higher in SEDslo, EX, and EXslo groups compared with SED group (P < 0.05). Gut-associated lymphocyte proliferation, on the other hand, was similar between the four experimental groups. Our findings show that SLO and EX indeed are able to increase lymphocyte proliferation, but their association did not induce further stimulation in the adaptive immune response and also did not modify innate immunity.

BnP1, a novel P-I metalloproteinase from Bothrops neuwiedi venom: Biological effects benchmarking relatively to jararhagin, a P-IIISVMP

Snake venom metalloproteinases (SVMPs) have been extensively studied and their effects associated with the local bleeding observed in human accidents by viper snakes. Representatives of P-I and P-III classes of SVMPs similarly hydrolyze extracellular matrix proteins or coagulation factors while only P-III SVMPs induce significant hemorrhage in experimental models. In this work, the effects of P-I and P-III SVMPs on plasma proteins and cultures of muscle and endothelial cells were compared in order to enlighten the mechanisms involved in venom-induced hemorrhage. To reach this comparison, BnP1 was isolated from B. neuwiedi venom and used as a weakly hemorrhagic P-I SVMPs and jararhagin was used as a model of potently hemorrhagic P-III SVMP. BnP1 was isolated by size exclusion and anion-exchange chromatographies, showing apparent molecular mass of approximately 24kDa and sequence similarity with other members of SVMPs, which allowed its classification as a group P-I SVMP. The comparison of local effects induced by SVMPs showed that BnP1 was devoid of significant myotoxic and hemorrhagic activities and jararhagin presented only hemorrhagic activity. BnP1 and jararhagin were able to hydrolyze fibrinogen and fibrin, although the latter displayed higher activity in both systems. Using HUVEC primary cultures, we observed that BnP1 induced cell detachment and a decrease in the number of viable endothelial cells in levels comparable to those observed by treatment with jararhagin. Moreover, both BnP1 and jararhagin induced apoptosis in HUVECs while only a small increase in LDH supernatant levels was observed after treatment with jararhagin, suggesting that the major mechanism involved in endothelial cell death is apoptosis. Jararhagin and BnP1 induced little effects on C2C12 muscle cell cultures, characterized by a partial detachment 24h after treatment and a mild necrotic effect as evidenced by a small increase in the supernatants LDH levels. Taken together, our data show that P-I and P-III SVMPs presented comparable effects except for the hemorrhagic activity, suggesting that hydrolysis of coagulation factors or damage to endothelial cells are not sufficient for induction of local bleeding. (C) 2007 Elsevier Ltd. All rights reserved.

Infrared emissions, visible up-conversion, thermoluminescence and defect centres in Er(3)Al(5)O(12) phosphor obtained by solution combustion reaction

The Er(3)Al(5)O(12) phosphor powders were prepared using the solution combustion method. Formation and homogeneity of the Er(3)Al(5)O(12) phosphor powders have been verified by X-ray diffraction and energy-dispersive X-ray analysis respectively. The frequency up-conversion from Er(3)Al(5)O(12) phosphor powder corresponding to the (2)H(9/2) -> (4)I(15/2), (2)H(11/2) -> (4)I(15/2), (4)S(3/2) -> (4)I(15/2), (4)F(9/2) -> (4)I(15/2) and the infrared emission (IR) due to the (4)I(13/2) -> (4)I(15/2) transitions lying at similar to 410, similar to 524, similar to 556, 645-680 nm and at similar to 1.53 mu m respectively upon excitation with a Ti-Sapphire pulsed/CW laser have been reported. The mechanism responsible for the frequency up-conversion and IR emission is discussed in detail. Defect centres induced by radiation were studied using the techniques of thermoluminescence and electron spin resonance. A single glow peak at 430A degrees C is observed and the thermoluminescence results show the presence of a defect center which decays at high temperature. Electron spin resonance studies indicate a center characterized by a g-factor equal to 2.0056 and it is observed that this center is not related to the thermoluminescence peak. A negligibly small concentration of cation and anion vacancies appears to be present in the phosphor in accordance with the earlier theoretical predictions.