Characterization of the quaternary amine transporters of Rhizobium leguminosarum bv. viciae 3841

Rhizobium leguminosarum bv. viciae 3841 contains six putative quaternary ammonium transporters (Qat), of the ABC family. Qat6 was strongly induced by hyperosmosis although the solute transported was not identified. All six systems were induced by the quaternary amines choline and glycine betaine. It was confirmed by microarray analysis of the genome that pRL100079-83 (qat6) is the most strongly upregulated transport system under osmotic stress, although other transporters and 104 genes are more than threefold upregulated. A range of quaternary ammonium compounds were tested but all failed to improve growth of strain 3841 under hyperosmotic stress. One Qat system (gbcXWV) was induced 20-fold by glycine betaine and choline and a Tn5::gbcW mutant was severely impaired for both transport and growth on these compounds, demonstrating that it is the principal system for their use as carbon and nitrogen sources. It transports glycine betaine and choline with a high affinity (apparent K-m, 168 and 294 nM, respectively).

Synthesis of hyperbranched poly(aryl amine)s via a carbene insertion approach

A novel diazirine functionalised aniline derivative, 3-(3-aminophenyl)-3-methyldiazirine 1, was prepared and employed as an AB(2)-type monomer in the synthesis of hyperbranched polymers; thus providing the first instance in which polyamines have been prepared via carbene insertion polymerisation. Photolysis of the monomer 1 in bulk and in solution resulted in the formation of hyperbranched poly(aryl amine)s with degrees of polymerisation (DP) varying from 9 to 26 as determined by gel permeation chromatography (GPC). In solution, an increase in the initial monomer concentration was generally found to result in a decrease in the molecular weight characteristics of the resulting poly(aryl amine) s. Subsequent thermal treatment of the poly(aryl amine) s caused a further increase in the DP values up to a maximum of 31. Nuclear magnetic resonance (NMR) spectroscopic analysis revealed that the increase in molecular weight upon thermal treatment resulted from hydroamination of styrenic species formed in the initial photopolymerisation or activation of diazirine moieties.

Osmotic pressure and aggregate shape in BSA/poly (ethylene glycol)-lipid/Dextran solutions

In this work we study the colloidal osmotic pressure (COP) and aggregate shape in phosphate saline buffer solutions (PH 7.4) containing bovine serum albumin (BSA), poly(ethylene glycol) lipid (PEG(2000)-PE) and Dextran (Dx). Dx was added to the BSA/PEG(2000)-PE system in order to increase the COP of the solution to levels comparable to the COP of healthy adults, with the aim of using the solution as a blood COP regulator. Dynamic light scattering and small angle X-ray scattering results shown the formation of BSA/PEG(2000)-PE/Dx aggregates in the solution. Osmometry results shown that the addition of Dx to the BSA/PE2000-PE system could successfully increase the COP, through the formation of BSA/PEG(2000)-PE/Dx aggregates. The BSA/PEG(2000)-PE/Dx solutions attained COP= 15 mm Hg, representing 60% of COP measured for healthy adults. (c) 2008 Elsevier B.V. All rights reserved.

Synthesis of bischromones by deformylative Mannich type reaction on chromone-3-carbaldehyde using alpha-aminoacid as the source of amine

Chromone-3-carbaldehyde reacts with N-methylglycine or glycine in the presence of excess formaldehyde to produce N-(chromone-3-ylmethyl)-N-methylglycine or N,N-di(chromone-3-ylmethyl)glycine, respectively, by a deformylative Mannich type reaction. Use of alanine or leucine or methionine in place of glycine produces N-(chromone-3-ylmethyl)alanine/-leucine/-methionine, respectively. (C) 2009 Elsevier Ltd. All rights reserved.

Ligand-centred reactivity of bis(picolyl)amine iridium: sequential deprotonation, oxidation and oxygenation of a "non-innocent" ligand

Treatment of [Ir(bpa)(cod)](+) complex [1](+) with a strong base (e.g., tBuO(-)) led to unexpected double deprotonation to form the anionic [Ir-(bpa-2H)(cod)](-) species [3](-), via the mono-deprotonated neutral amido complex [Ir(bpa-H)(cod)] as an isolable intermediate. A certain degree of aromaticity of the obtained metal-chelate ring may explain the favourable double deprotonation. The rhodium analogue [4](-) was prepared in situ. The new species [M(bpa-2H)(cod)](-) (M = Rh, Ir) are best described as two-electron reduced analogues of the cationic imine complexes [M-I(cod)(Py-CH2-N=CH-Py)](+). One-electron oxidation of [3](-) and [4](-) produced the ligand radical complexes [3]* and [4]*. Oxygenation of [3](-) with O-2 gave the neutral carboxamido complex [Ir(cod)(py-CH2-N-CO-py)] via the ligand radical complex [3]* as a detectable intermediate.

Glycol methyl ether and glycol amine substituted titanocenes as antitumor agents

6-[4-(2-Methoxyethoxy)phenyl]fulvene (3a) and 6-(4-[2-(di-methylamino)ethoxy]phenyl)fulvene (3b) were prepared as starting materials for the synthesis of three dofferent classes of titanocenes, which are ansa-titanocenes, diarylmethyl-substituted titanicenes and benzyl-substituted titanocenes and benyzyl-subtituted titanocenes. Because the synthetic possibilities seem to be limited, only ansa-titanocene {1,2-bis(cyclopentadienyl)-1,2-bis[4-(2-methoxyethoxy)phenyl]ethanediyl}titanium dichloride (4a) and benzyl-substituted titanocene bis-{[4-(2-methoxyethoxy)benzyl]cyclopentadienyl}titantium(IV) dichloride (6a) were obtained and characterised. The change in the substitution pattern f the phenyl moiety from an oxygen atom to a nitrogen atom had such a big influence on the reaction that not one compound of the threee titanocene classes could be synthesised, and it was also not possible to obtain diarylmethyl-substituted titanocenes with the use of either of the fulvenes. When benzyl-substituted titanocene 6a was tested agianst pig kidney cells (LLC-PK), an antiproliferative effect that result in an IC50 value of 43 mu m, was observed. This IC50 value is in the lower range of the cytotoxicities evaluated for titanocenes up to now. ansa-Titanocene 4a surprisingly showed, when tested on the same cell line, a proliferative effect together with a fast rate of hydrolysis.

The antithrombotic effect of dextran-40 in man is due to enhanced fibrinolysis in vivo

BACKGROUND: Dextran-40 is effective in reducing postoperative Doppler-detectable embolization in patients undergoing carotid endarterectomy (CEA). Dextrans are thought to have antithrombotic and antiplatelet effects. The mode of action is unclear. In rats, dextran blocks uptake of tissue plasminogen activator (tPA) by mannose-binding receptors. Because this would have the effect of enhancing endogenous fibrinolysis, we explored this effect of dextran-40 on fibrinolysis in man. METHODS: Twenty patients undergoing endovascular stenting for abdominal aortic aneurysm were randomized to receive 100 mL of 10% dextran-40 or saline, over 1 hour, during their operation in addition to heparin. Blood samples were taken preoperatively, intraoperatively (immediately after operative procedure), and 24 hours postoperatively. Thrombi were formed in a Chandler loop and used to assess endogenous fibrinolysis over 24 hours, measured as the fall in thrombus weight, and the release of fluorescently labelled fibrinogen from the thrombus. Plasma samples were analyzed for markers of fibrinolysis; plasmin-antiplasmin (PAP), PAI-1, and t-PA, and for functional von Willebrand factor (vWF). Platelet response to thrombin and other agonists was measured by flow cytometry. RESULTS: Thrombi formed ex vivo from the intraoperative blood samples from the dextran-treated patients exhibited significantly greater fibrinolysis vs preoperative samples, seen both as a significantly greater percentage reduction in thrombus weight (from 34.7% to 70.6% reduction) and as an 175% increase in the release of fluorescence (P < .05). Fibrinolysis returned to baseline levels the next day. No change was seen in the saline-treated group. Plasma levels of PAP and PAI-1 increased significantly postoperatively in the dextran-treated group vs the saline group (P < .05). The postoperative level of functional VWF was significantly lower in the dextran-treated group vs controls. A specific reduction occurred in the platelet response to thrombin, but not to other agonists, in the intraoperative samples from the dextran-treated group (11.1% vs 37.1%; P = .022), which was not seen in the controls. CONCLUSIONS: These data are consistent with a rise in plasmin due to dextran blockade of tPA uptake in vivo, leading to enhanced fibrinolysis, cleavage of vWF and of the platelet protease-activated receptor-1 (PAR-1) thrombin receptor. This suggests that dextran exerts a combined therapeutic effect, enhancing endogenous fibrinolysis, whilst also reducing platelet adhesion to vWF and platelet activation by thrombin. The proven antithrombotic efficacy of low-dose dextran in carotid surgery may be applicable to wider therapeutic use.

Potential of novel dextran oligosaccharides as prebiotics for obesity management through in vitro experimentation.

The energy-salvaging capacity of the gut microbiota from dietary ingredients has been proposed as a contributing factor for the development of obesity. This knowledge generated interest in the use of non-digestible dietary ingredients such as prebiotics to manipulate host energy homeostasis. In the present study, the in vitro response of obese human faecal microbiota to novel oligosaccharides was investigated. Dextrans of various molecular weights and degrees of branching were fermented with the faecal microbiota of healthy obese adults in pH-controlled batch cultures. Changes in bacterial populations were monitored using fluorescent in situ hybridisation and SCFA concentrations were analysed by HPLC. The rate of gas production and total volume of gas produced were also determined. In general, the novel dextrans and inulin increased the counts of bifidobacteria. Some of the dextrans were able to alter the composition of the obese human microbiota by increasing the counts of Bacteroides–Prevotella and decreasing those of Faecalibacterium prausnitzii and Ruminococcus bromii/R. flavefaciens. Considerable increases in SCFA concentrations were observed in response to all substrates. Gas production rates were similar during the fermentation of all dextrans, but significantly lower than those during the fermentation of inulin. Lower total gas production and shorter time to attain maximal gas production were observed during the fermentation of the linear 1 kDa dextran than during the fermentation of the other dextrans. The efficacy of bifidobacteria to ferment dextrans relied on the molecular weight and not on the degree of branching. In conclusion, there are no differences in the profiles between the obese and lean human faecal fermentations of dextrans.

Effect of processing on amine formation and the lipid profile of cod (Gadus morhua) roe

The processing of fish roe leads to changes in its chemical composition, the extent of which depends on the techniques and additives employed. This study aimed to investigate the effects of ripening temperature and the use of sodium benzoate and citric acid on the quality of ripened cod roe, with respect to the contents of volatile base nitrogen (VBN), trimethylamine (TMA), biogenic amines (BA) and on the lipid composition. In comparison with fresh roes, ripened roes presented higher contents of VBN, TMA, BA and the proportion of free fatty acids regardless of the temperature and additives used during the ripening process. The greatest increases were observed in the samples ripened at 17 degrees C without additives, in which histamine was detected at 8.8 mg/100 g. A low ripening temperature was the main factor responsible for minimising changes in the cod roe composition. The addition of sodium benzoate as a preservative or citric acid to decrease the pH value had a significant effect in maintaining the quality of the cod roes, mainly at high ripening temperature. (C) 2011 Elsevier Ltd. All rights reserved.

Electronic synergism in [RuCl(2)(PPh(3))(2)(amine)] complexes differing the reactivity for ROMP of norbornene and norbornadiene

The reactivity of the new complex [RuCl(2)(PPh(3))(2)(3,5-Me(2)piperidine)], complex 1, was investigated for ring opening metathesis polymerization (ROMP) of norbornene (NBE) and norbornadiene (NBD) in the presence of ethyl diazoacetate (EDA) in CHCl(3). The aim is to observe the combination of PPh(3) and an amine as ancillary ligands concerning the steric hindrance and the electronic perturbation in the properties of the N-bound site when replacing the amines. Thus, the results with 1 were compared to the results obtained when the amine is piperidine (complex 2). Reaction with 1 provides 70% yield of isolated polyNBE (M(n) =8.3 x 10(4) g/mol; PDI = 2.03), whereas 2 provides quantitative reaction (M(n) = 1.2 x 10(5) g/mol; PDI = 1.90) with [NBE]/[Ru] = 5000, [EDA]/[Ru] = 48 and 1.1 mu mol of Ru for 5 min at 25 degrees C. The resulting polymers showed c.a. 62% of trans-polyNBE, determined by (1)H NMR, and T(g) = 32 degrees C, determined by DSC and DMTA. For ROMP of NBD, 1 showed quantitative yield with PDI =2.62 when [NBD]/[Ru] = 5000 for 20 min at 25 degrees C, whereas the reaction with 2 reached 55% with PDI = 2.16 in the same conditions. It is concluded that the presence of the two methyl groups in the piperidine ring provides an increase in the induction period to produce the Ru-carbene species justifying better polyNBE results with 2, and a greater amine(sigma)-> Ru(pi)-> monomer synergism which contributed to the best activation of less tensioned olefin as NBD. (C) 2010 Elsevier B.V. All rights reserved.

Formation of Dextran Deposits in Brazilian Sugar Cane Spirits

The formation of dextran deposits in sugared Brazilian cachaca was studied as a function of the time considering the effects of temperature, molecular weight (M(w)), visible light, pH, and the presence of Ca, Mg, Cu, and Fe ions in the concentrations at which they are usually present in this beverage. At 25 degrees C and pH 4.4, the experimental half-lives (t(1/2)) for precipitation are 73 and 124 days for dextrans with M(w) 5.9 x 10(6) and 2.1 x 10(6) Da, respectively. For dextrans with M(w) 5.0 x 10(5) and 4.0 x 10(4) Da, the experimental t(1/2) values are >180 days. For a dextran with M(w) 2.1 x 10(6) Da a change in pH from 4.4 to 5.5 at 25 degrees C resulted in a t(1/2) decrease from 124 to 25 days. At pH 4.4 the visible light and the presence of metal ions in average concentrations usually found in cachacas do not exhibit noticeable influence on the rate of dextran precipitation.