Recent advances in catalytic and non-catalytic epoxidation of terpenes: a pathway to bio-based polymers from waste biomass

Epoxides derived from waste biomass are a promising avenue for the production of bio-based polymers, including polyamides, polyesters, polyurethanes, and polycarbonates. This review article explores recent efforts to develop both catalytic and non-catalytic processes for the epoxidation of terpene, employing a variety of oxidizing agents and techniques for process intensification. Experimental investigations into the epoxidation of limonene have shown that these methods can be extended to other terpenes. To optimize the epoxidation of bio-based terpene, there is a need to develop continuous processes that address limitations in mass and heat transfer. This review discusses flow chemistry and innovative reactor designs as part of a multi-scale approach aimed at industrial transformation. These methods facilitate continuous processing, improve mixing, and either eliminate or reduce the need for solvents by enhancing heat transfer capabilities. Overall, the objective of this review is to contribute to the development of commercially viable processes for producing bio-based epoxides from waste biomass.

A foam column system harvesting freshwater algae for biodiesel production: An experiment and process model evaluations

The purpose of this study was to examine the application of the mathematical model of drift flux to the experimental results of the effect of cationic trimethyl-ammonium bromide (CTAB)-aided continuous foam flotation harvesting on the lipid content in Chlorella vulgaris microalgae. An experiment was conducted to determine the effect of the operating conditions on the enrichment factor (EF) and percentage recovery efficiency (%RE), where the flow rates at the inlet and bottom outlet remained constant. Data for the binary system (without algae) and ternary system (with algae) in an equal-area foam column show that the EF decreases linearly with increasing initial CTAB concentrations ranging from 30 to 75 mg/L for three levels of the studied air volumetric flow rate range (1-3) L/min. The percentage harvesting efficiency increased with increasing initial CTAB concentration and air volumetric flow rate to 96 % in the binary systems and 94 % in the ternary systems. However, in the foam column with the riser used in the three systems, a lower volume of liquid foam in the upward outlet stream resulted in a lower RE% than that of the column without the riser. The objective function of EF for the system with algae increased when the initial CTAB concentration was increased from 30 to 45 mg/L in the foam column with a riser for all air flow rates, and after 45 mg/L, a sudden drop in the microalgae EF was observed. In the comparison between the foam column with and without the riser for the system with algae, the optimum EF was 145 for the design of the column with the riser and 139 for the column without the riser.

Synthesis of cyclic α-pinane carbonate - a potential monomer for bio-based polymers

This work reports the first known synthesis of α-pinane carbonate from an α-pinene derivative. Pinane carbonate is potentially useful as a monomer for poly(pinane carbonate), which would be a sustainable bio-based polymer. α-Pinene is a major waste product from the pulp and paper industries and the most naturally abundant monoterpene in turpentine oil. α-Pinene is routinely converted to pinene oxide and pinanediol, but no study has yet demonstrated the conversion of pinanediol into α-pinane carbonate. Here, α-pinane carbonate was synthesised via carboxylation of α-pinanediol with dimethyl carbonate under base catalysis using triazabicyclodecene guanidine (TBD). 81.1 ± 2.8% α-pinane carbonate yield was achieved at 98.7% purity. The produced α-pinane carbonate was a white crystalline solid with a melting point of 86 °C. It was characterised using FTIR, NMR, GCMS and a quadrupole time-of-flight (QTOF) mass spectrometer. The FTIR exhibited a C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O peak at 1794 cm⁻¹ confirming the presence of a cyclic carbonate. GCMS showed that the α-pinane carbonate fragments with loss of CO₂, forming pinene epoxide. Base hydrolysis of the α-pinane carbonate using NaOH/ethanol/water regenerated the pinanediol with formations of Na₂CO₃.

Synthesis of α-pinane carbonate from an α-pinene derivative.

Osteoprotegerin regulates vascular function through syndecan-1 and NADPH oxidase-derived reactive oxygen species

Osteogenic factors, such as osteoprotegerin (OPG), are protective against vascular calcification. However, OPG is also positively associated with cardiovascular damage, particularly in pulmonary hypertension, possibly through processes beyond effects on calcification. In the present study, we focused on calcification-independent vascular effects of OPG through activation of syndecan-1 and NADPH oxidases (Noxs) 1 and 4. Isolated resistance arteries from Wistar-Kyoto (WKY) rats, exposed to exogenous OPG, studied by myography exhibited endothelial and smooth muscle dysfunction. OPG decreased nitric oxide (NO) production, eNOS activation and increased reactive oxygen species (ROS) production in endothelial cells. In VSMCs, OPG increased ROS production, H2O2/peroxynitrite levels and activation of Rho kinase and myosin light chain. OPG vascular and redox effects were also inhibited by the syndecan-1 inhibitor synstatin (SSNT). Additionally, heparinase and chondroitinase abolished OPG effects on VSMCs-ROS production, confirming syndecan-1 as OPG molecular partner and suggesting that OPG binds to heparan/chondroitin sulphate chains of syndecan-1. OPG-induced ROS production was abrogated by NoxA1ds (Nox1 inhibitor) and GKT137831 (dual Nox1/Nox4 inhibitor). Tempol (SOD mimetic) inhibited vascular dysfunction induced by OPG. In addition, we studied arteries from Nox1 and Nox4 knockout (KO) mice. Nox1 and Nox4 KO abrogated OPG-induced vascular dysfunction. Vascular dysfunction elicited by OPG is mediated by a complex signalling cascade involving syndecan-1, Nox1 and Nox4. Our data identify novel molecular mechanisms beyond calcification for OPG, which may underlie vascular injurious effects of osteogenic factors in conditions such as hypertension and/or diabetes.

Development of rapid and selective epoxidation of α-pinene using single-step addition of H2O2 in an organic solvent-free process

This study reports substantial improvement in the process for oxidising α-pinene, using environmentally friendly H₂O₂ at high atom economy (∼93%) and selectivity to α-pinene oxide (100%). The epoxidation of α-pinene with H₂O₂ was catalysed by tungsten-based polyoxometalates without any solvent. The variables in the screening parameters were temperatures (30–70 °C), oxidant amount (100–200 mol%), acid concentrations (0.02–0.09 M) and solvent types (i.e., 1,2-dichloroethane, toluene, p-cymene and acetonitrile). Screening the process parameters revealed that almost 100% selective epoxidation of α-pinene to α-pinene oxide was possible with negligible side product formation within a short reaction time (∼20 min), using process conditions of a 50 °C temperature in the absence of solvent and α-pinene/H₂O₂/catalyst molar ratio of 5 : 1 : 0.01. A kinetic investigation showed that the reaction was first-order for α-pinene and catalyst concentration, and a fractional order (∼0.5) for H₂O₂ concentration. The activation energy (E_a) for the epoxidation of α-pinene was ∼35 kJ mol⁻¹. The advantages of the epoxidation reported here are that the reaction could be performed isothermally in an organic solvent-free environment to enhance the reaction rate, achieving nearly 100% selectivity to α-pinene oxide.

Products obtained from the oxidation of α-pinene with hydrogen peroxide (H₂O₂) in the presence of tungsten-based polyoxometalates (α-pinene 1, α-pinene oxide 2, pinanediol 3, campholenic aldehyde 4, sobrerol 5, verbenol 6 and verbenone 7).

Downregulation of PPARα during Experimental Left Ventricular Hypertrophy Is Critically Dependent on Nox2 NADPH Oxidase Signalling

Pressure overload-induced left ventricular hypertrophy (LVH) is initially adaptive but ultimately promotes systolic dysfunction and chronic heart failure. Whilst underlying pathways are incompletely understood, increased reactive oxygen species generation from Nox2 NADPH oxidases, and metabolic remodelling, largely driven by PPARα downregulation, are separately implicated. Here, we investigated interaction between the two as a key regulator of LVH using in vitro, in vivo and transcriptomic approaches. Phenylephrine-induced H9c2 cardiomyoblast hypertrophy was associated with reduced PPARα expression and increased Nox2 expression and activity. Pressure overload-induced LVH and systolic dysfunction induced in wild-type mice by transverse aortic constriction (TAC) for 7 days, in association with Nox2 upregulation and PPARα downregulation, was enhanced in PPARα-/- mice and prevented in Nox2-/- mice. Detailed transcriptomic analysis revealed significantly altered expression of genes relating to PPARα, oxidative stress and hypertrophy pathways in wild-type hearts, which were unaltered in Nox2-/- hearts, whilst oxidative stress pathways remained dysregulated in PPARα-/- hearts following TAC. Network analysis indicated that Nox2 was essential for PPARα downregulation in this setting and identified preferential inflammatory pathway modulation and candidate cytokines as upstream Nox2-sensitive regulators of PPARα signalling. Together, these data suggest that Nox2 is a critical driver of PPARα downregulation leading to maladaptive LVH.

Chanzyme TRPM7 protects against cardiovascular inflammation and fibrosis

AIMS

Transient Receptor Potential Melastatin 7 (TRPM7) cation channel is a chanzyme (channel + kinase) that influences cellular Mg2+ homeostasis and vascular signalling. However, the pathophysiological significance of TRPM7 in the cardiovascular system is unclear. The aim of this study was to investigate the role of this chanzyme in the cardiovascular system focusing on inflammation and fibrosis.

METHODS AND RESULTS

TRPM7-deficient mice with deletion of the kinase domain (TRPM7+/Δkinase) were studied and molecular mechanisms investigated in TRPM7+/Δkinase bone marrow-derived macrophages (BMDM) and co-culture systems with cardiac fibroblasts. TRPM7-deficient mice had significant cardiac hypertrophy, fibrosis, and inflammation. Cardiac collagen and fibronectin content, expression of pro-inflammatory mediators (SMAD3, TGFβ) and cytokines [interleukin (IL)-6, IL-10, IL-12, tumour necrosis factor-α] and phosphorylation of the pro-inflammatory signalling molecule Stat1, were increased in TRPM7+/Δkinase mice. These processes were associated with infiltration of inflammatory cells (F4/80+CD206+ cardiac macrophages) and increased galectin-3 expression. Cardiac [Mg2+]i, but not [Ca2+]i, was reduced in TRPM7+/Δkinase mice. Calpain, a downstream TRPM7 target, was upregulated (increased expression and activation) in TRPM7+/Δkinase hearts. Vascular functional and inflammatory responses, assessed in vivo by intra-vital microscopy, demonstrated impaired neutrophil rolling, increased neutrophil: endothelial attachment and transmigration of leucocytes in TRPM7+/Δkinase mice. TRPM7+/Δkinase BMDMs had increased levels of galectin-3, IL-10, and IL-6. In co-culture systems, TRPM7+/Δkinase macrophages increased expression of fibronectin, proliferating cell nuclear antigen, and TGFβ in cardiac fibroblasts from wild-type mice, effects ameliorated by MgCl2 treatment.

CONCLUSIONS

We identify a novel anti-inflammatory and anti-fibrotic role for TRPM7 and suggest that its protective effects are mediated, in part, through Mg2+-sensitive processes.

Techno-Economic Analysis of Glycerol Valorization via Catalytic Applications of Sulphonic Acid-Functionalized Copolymer Beads

The design of experiments response surface analysis was employed for the first time to study the effect of divinylbenzene (DVB) (20–80 wt. %), diluent (0–100 wt.%), and mixing (200–900 rpm) on the beads' physical properties and on swelling ability. The beads with the highest performances, in terms of mechanical stability, surface area, and swelling ability, were sulphated, and tested in converting glycerol to a valuable product “solketal.” Process options for glycerol valorization to solketal using synthesized sulphonic acid-functionalized styrene-divinylbenzene (ST-DVB-SO₃H) copolymer beads and techno-economic analysis of the processes have been investigated. Three processes were evaluated: two one-stage processes at 8.5 wt.% catalyst and 50°C, based on either 6:1 acetone to glycerol molar ratio (87% conversion) or 12:1 (98% glycerol to solketal conversion), and a two-stage route (two acetone additions), where ≥98% conversion can be achieved with lower overall acetone use (10:1 acetone to glycerol molar ratio and 50°C). Techno-economic analyses of the three solketal options were performed using Aspen (HYSYS), based on a fixed capacity of 100,000 te/y and 20-years lifetime. The techno-economic analyses showed that the net present values for the solketal process options were $707 M for the two-stage, $384 M for the one-stage at 6:1 acetone to glycerol molar ratio, and $703 M for the one-stage at 12:1 acetone to glycerol molar ratio. The break-even prices for these solketal processes were $2,058/ ton for the one-stage at 12:1 of acetone and two-stage and $2,088/ton for the one-stage at 6:1 of acetone, which is lower than the current price of solketal at $3,000/ton. The two-stage process was found to be the most effective method of glycerol valorization production to solketal.

Oscillatory Flow Bioreactor (OFB) Applied in Enzymatic Hydrolysis at High Solid Loadings

Within this study, an enzymatic hydrolysis process using α-cellulosic feedstock was<br /> performed in a specially designed plug-flow reactor, referred to as an Oscillatory Flow<br /> Bioreactor (OFB). The aims of this approach were to achieve intensification in terms of<br /> realising a more energy- and resource-efficient enzymatic hydrolysis, as well as to set the<br /> basis for continuous processes in such a reactor. The OFB performance was evaluated for<br /> high solid loadings of up to 15 %, and compared to the performance of a Stirred Tank Reactor (STR). Experimental results of the OFB operating at an oscillation frequency of<br /> 2 Hz and an oscillation amplitude of 10 mm exhibit better conversion efficiencies (+ 6.7 %)<br /> than the STR after 24 h, while requiring only 7 % of the STR power density (W m–3). Therefore, the OFB enables efficient, uniform mixing at lower power densities than STRs for applications with high solid loadings.

ER stress and Rho kinase activation underlie the vasculopathy of CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) leads to premature stroke and vascular dementia. Mechanism-specific therapies for this aggressive cerebral small vessel disease are lacking. CADASIL is caused by NOTCH3 mutations that influence vascular smooth muscle cell (VSMC) function through unknown processes. We investigated molecular mechanisms underlying the vasculopathy in CADASIL focusing on endoplasmic reticulum (ER) stress and RhoA/Rho kinase (ROCK). Peripheral small arteries and VSMCs were isolated from gluteal biopsies of CADASIL patients and mesentery of TgNotch3R169C mice (CADASIL model). CADASIL vessels exhibited impaired vasorelaxation, blunted vasoconstriction, and hypertrophic remodeling. Expression of NOTCH3 and ER stress target genes was amplified and ER stress response, Rho kinase activity, superoxide production, and cytoskeleton-associated protein phosphorylation were increased in CADASIL, processes associated with Nox5 upregulation. Aberrant vascular responses and signaling in CADASIL were ameliorated by inhibitors of Notch3 (γ-secretase inhibitor), Nox5 (mellitin), ER stress (4-phenylbutyric acid), and ROCK (fasudil). Observations in human CADASIL were recapitulated in TgNotch3R169C mice. These findings indicate that vascular dysfunction in CADASIL involves ER stress/ROCK interplay driven by Notch3-induced Nox5 activation and that NOTCH3 mutation-associated vascular pathology, typical in cerebral vessels, also manifests peripherally. We define Notch3-Nox5/ER stress/ROCK signaling as a putative mechanism-specific target and suggest that peripheral artery responses may be an accessible biomarker in CADASIL.

Abstract 011: TRPM7 is Cardiovascular Protective in Aldosterone-Induced Hypertension

TRPM7 is a chanzyme that influences cellular Mg 2+ homeostasis and vascular signaling. We demonstrated that aldosterone mediates cellular effects through TRPM7-dependent signaling pathways. Since hyperaldosteronism causes hypertension and Mg 2+ wasting, we questioned whether TRPM7 plays a role in aldosterone-induced hypertension. Wild-type (WT) and TRPM7-deficient (M7+/Δ) mice were treated with aldosterone (600μg/Kg/day) and/or 1% NaCl (drinking water) (aldo, salt or aldo/salt) for 4 weeks. Blood pressure (BP) was evaluated by tail-cuff. Vessel function was investigated in mesenteric arteries by wire and pressure myography. Protein expression was assessed by western-blot and histology. Cardiac fibroblasts (CF) were isolated from WT and M7+/Δ. M7+/Δ exhibited increased BP by aldo (140mmHg), salt (135mmHg) and aldo/salt (137mmHg) vs M7+/Δ-veh (117mmHg) (p<0.05), whereas in WT, BP was increased only by aldo/salt (134mmHg). All treatments induced endothelial dysfunction in M7+/Δ as observed in acetylcholine-relaxation curves [Emax % M7+/Δ: aldo (81±4), salt (69±4) and aldo/salt (75±3.0), p<0.05], whereas in WT, Emax % was reduced after aldo (68±4) and aldo/salt (80±3). Phenylephrine-contraction and SNP-relaxation curves were similar among groups. Pressure myography showed that in WT, aldo/salt increased wall/lumen ratio (83%) inducing eutrophic inward remodeling, whereas M7+/Δ-veh presented 62% reduction in cross-sectional area vs WT, which was increased by salt and aldo/salt, resulting in hypertrophic outward remodeling. Collagen was increased in aortas from M7+/Δ by aldo (31%) and aldo/salt (45%) and no changes in WT. Aldo/salt induced higher collagen deposition in hearts (68%) and kidneys (126%) from M7+/Δ vs WT. Hearts and kidneys from M7+/Δ veh exhibited increased α-SMA (2-fold) and p-Stat1 (1.5-fold), whereas tissues from WT exhibited 3-fold increase only after treatments. CF from M7+/Δ stimulated with aldosterone (100nM) showed increased activation of Stat1 (177%), Smad3 (300%) and reduced pStat3 (70%) vs WT, p<0.05. We define a novel protective role of TRPM7 in the cardiovascular system, which when downregulated, promotes increased blood pressure, vascular remodeling and cardiac fibrosis mediated by aldosterone and salt.

Scale-up and Sustainability Evaluation of Biopolymer Production from Citrus Waste Offering Carbon Capture and Utilisation Pathway

Invited for this month's cover picture is the group of Dr Miao Guo from Department of Chemical Engineering at the Imperial College London (UK). The cover picture shows modelling research on the co-polymerisation of waste-sourced limonene oxide with CO2 to produce poly(limonene carbonate), which offers a sustainable pathway to achieve carbon capture and utilisation. A computational approach to process design was integrated with sustainability evaluation to model this synthetic pathway and identify the environmental-damaging and performance-limiting steps for further improvement. Our research highlights the potential of closed-loop manufacturing systems with waste recovery, which is instrumental in building a sustainable circular economy. Read the full text of their Full Paper at 10.1002/open.201900015.

Scale-up and Sustainability Evaluation of Biopolymer Production from Citrus Waste Offering Carbon Capture and Utilisation Pathway

Poly(limonene carbonate) (PLC) has been highlighted as an attractive substitute to petroleum derived plastics, due to its utilisation of CO₂ and bio‐based limonene as feedstocks, offering an effective carbon capture and utilisation pathway. Our study investigates the techno‐economic viability and environmental sustainability of a novel process to produce PLC from citrus waste derived limonene, coupled with an anaerobic digestion process to enable energy cogeneration and waste recovery maximisation. Computational process design was integrated with a life cycle assessment to identify the sustainability improvement opportunities. PLC production was found to be economically viable, assuming sufficient citrus waste is supplied to the process, and environmentally preferable to polystyrene (PS) in various impact categories including climate change. However, it exhibited greater environmental burdens than PS across other impact categories, although the environmental performance could be improved with a waste recovery system, at the cost of a process design shift towards energy generation. Finally, our study quantified the potential contribution of PLC to mitigating the escape of atmospheric CO₂ concentration from the planetary boundary. We emphasise the importance of a holistic approach to process design and highlight the potential impacts of biopolymers, which is instrumental in solving environmental problems facing the plastic industry and building a sustainable circular economy.

Experimental Determination of Optimal Conditions for Reactive Coupling of Biodiesel Production With in situ Glycerol Carbonate Formation in a Triglyceride Transesterification Process

This study investigated a reactive coupling to determine the optimal conditions for transesterification of rapeseed oil (RSO) to fatty acid methyl ester (FAME) and glycerol carbonate (GLC) in a one-step process, and at operating conditions which are compatible with current biodiesel industry. The reactive coupling process was studied by transesterification of RSO with various molar ratios of both methanol and dimethyl carbonate (DMC), using triazabicyclodecene (TBD) guanidine catalyst and reaction temperatures of 50–80°C. The optimal reaction conditions obtained, using a Design of Experiments approach, were a 2:1 methanol-to-RSO molar ratio and 3:1 DMC-to-RSO molar ratio at 60°C. The FAME and GLC conversions at the optimal conditions were 98.0 ± 1.5 and 90.1 ± 2.2%, respectively, after 1 h reaction time using the TBD guanidine catalyst. Increase in the DMC-to-RSO molar ratio from 3:1 to 6:1 slightly improved the GLC conversion to 94.1 ± 2.8% after 2 h, but this did not enhance the FAME conversion. Methanol substantially improved both FAME and GLC conversions at 1:1–2:1 methanol-to-RSO molar ratios and enhanced the GLC separation from the reaction mixture. It was observed that higher methanol molar ratios (>3:1) enhanced only FAME yields and resulted in lower GLC conversions due to reaction equilibrium limitations. At a 6:1 methanol-to-RSO molar ratio, 98.4% FAME and 73.3% GLC yields were obtained at 3:1 DMC-to-RSO molar ratio and 60°C. This study demonstrates that formation of low value crude glycerol can be reduced by over 90% compared to conventional biodiesel production, with significant conversion to GLC, a far more valuable product.

Extractive recovery and valorisation of arsenic from contaminated soil through phytoremediation using Pteris cretica

Contamination of ground water and soil by arsenic poses serious environmental challenges globally. A possible solution to this problem is through phytoremediation using hyper-accumulating plants. This study investigates phytoremediation of soil containing 200 ± 3 mg kg^-1 of arsenic using Pteris cretica ferns, and the strategies for arsenic extraction from the ferns biomass and subsequent conversions to valuable arsenic products. The Pteris cretica ferns achieved maximum arsenic accumulations of 4427 ± 79 to 4875 ± 96 mg of arsenic per kg dry biomass after 30 days. Extraction efficiencies of arsenic in the ferns fronds were 94.3 ± 2.1% for ethanol-water (1:1 v/v), 81.5 ± 3.2% for 1:1 (v/v) methanol-water, and 70.8 ± 2.9% for water alone. Molybdic acid process was used to recover 90.8 ± 5.3% of the arsenic, and 95.1 ± 4.6% of the phosphorus in the biomass extract. Quantitative precipitation of Mg₃(AsO₄)₂ and Mg₃(PO₄)₂ occurred on treatment of the aqueous solutions of arsenic and phosphorus after stripping at pH of 8-10. The efficiencies of Mg₃(AsO₄)₂ and Mg₃(PO₄)₂ precipitation were 96 ± 7.2% and 94 ± 3.4%, respectively. Arsenic nanoparticles produced from the recovered Mg₃(AsO₄)₂, using two-stage reduction process, had average particle diameters of 45.5 ± 11.3 nm. These nanoparticles are potentially valuable for medical applications, while the Mg₃(AsO₄)₂ could be converted to more valuable forms of arsenic or used as a pesticide, and the Mg₃(PO₄)₂ in fertiliser. Recovery of these valuable products from phytoremediation biomass would incentivise and drive commercial industries' participation in remediation of contaminated lands.

Abstract 129: TRPM7 α-kinase Deficiency Causes Cardiovascular Inflammation and Fibrosis

We previously demonstrated that TRPM7, a Mg 2+ /cation channel fused to an α-kinase domain, is regulated by vasoactive mediators and plays a protective role in hypertension. Here we questioned whether TRPM7-kinase influences vascular inflammation and fibrosis. We used Wild-type (WT) and heterozygote mutant mice for TRPM7-kinase (M7+/-). Vascular inflammatory responses were assessed ex vivo by intravital microscopy. Immune cells were investigated by flow cytometry. Fibrosis was investigated by sirius-red staining. Bone-marrow derived macrophages (BMDM) and Cardiac fibroblasts (CF) were obtained from WT and M7+/. [Mg 2+ ]i in cardiac tissue, cardiac macrophages and circulating monocytes was significantly reduced (30-50%) in M7+/- vs WT mice. In small arteries studied by intravital microscopy, leukocytes from M7+/- showed reduced velocity (47%), increased adhesion (222%) and transmigration (480%). Expression of vascular pro-inflammatory markers including VCAM-1(33-fold), iNOS (12-fold), and IL-12 (6.8-fold) was increased in M7+/- vs WT. Cardiac galectin-3 (Gal-3) levels (16.6±3.6 vs WT 9.2±1.2 cells/field), collagen area (6.7% vs WT 2.6%), infiltration of CD45+ cells (6±0.6% vs WT 4±0.4%) and protein expression of fibronectin (280%), TGFβ (125%), and p-Smad3 (66%), were increased in M7+/- mice. BMDM macrophages from M7+/- exhibited increased levels of Gal-3 (2.6±0.05 vs WT 2.1±0.09ng/mL), IL-10 (807±92 vs WT 305±37 pg/mL) and IL-6 (84±8 vs WT 13±5 pg/mL). A similar profile was demonstrated in resident peritoneal macrophages. CF treated with supernatant of macrophages from M7+/- increased fibronectin (43%) and PCNA (36%) vs WT. To evaluate whether these processes are Mg 2+ -sensitive, we examined effects of Mg 2+ treatment and demonstrated that Mg 2+ ameliorated pro-fibrotic and pro-inflammatory signalling evident in TRPM7+/- mice. In conclusion, TRPM7-kinase deficiency is associated with cardiac and vascular inflammation and fibrosis, processes associated with cellular Mg 2+ deficiency. Our findings highlight an important cardiovascular protective role of TRPM7 and Mg 2+ .

NADPH Oxidase 5 Is a Pro-Contractile Nox Isoform and a Point of Cross-Talk for Calcium and Redox Signaling-Implications in Vascular Function

Background

NADPH Oxidase 5 (Nox5) is a calcium‐sensitive superoxide‐generating Nox. It is present in lower forms and higher mammals, but not in rodents. Nox5 is expressed in vascular cells, but the functional significance remains elusive. Given that contraction is controlled by calcium and reactive oxygen species, both associated with Nox5, we questioned the role of Nox5 in pro‐contractile signaling and vascular function.

Methods and Results

Transgenic mice expressing human Nox5 in a vascular smooth muscle cell–specific manner (Nox5 mice) and Rhodnius prolixus, an arthropod model that expresses Nox5 endogenoulsy, were studied. Reactive oxygen species generation was increased systemically and in the vasculature and heart in Nox5 mice. In Nox5‐expressing mice, agonist‐induced vasoconstriction was exaggerated and endothelium‐dependent vasorelaxation was impaired. Vascular structural and mechanical properties were not influenced by Nox5. Vascular contractile responses in Nox5 mice were normalized by N‐acetylcysteine and inhibitors of calcium channels, calmodulin, and endoplasmic reticulum ryanodine receptors, but not by GKT137831 (Nox1/4 inhibitor). At the cellular level, vascular changes in Nox5 mice were associated with increased vascular smooth muscle cell [Ca²⁺]_i, increased reactive oxygen species and nitrotyrosine levels, and hyperphosphorylation of pro‐contractile signaling molecules MLC20 (myosin light chain 20) and MYPT1 (myosin phosphatase target subunit 1). Blood pressure was similar in wild‐type and Nox5 mice. Nox5 did not amplify angiotensin II effects. In R. prolixus, gastrointestinal smooth muscle contraction was blunted by Nox5 silencing, but not by VAS2870 (Nox1/2/4 inhibitor).

Conclusions

Nox5 is a pro‐contractile Nox isoform important in redox‐sensitive contraction. This involves calcium‐calmodulin and endoplasmic reticulum–regulated mechanisms. Our findings define a novel function for vascular Nox5, linking calcium and reactive oxygen species to the pro‐contractile molecular machinery in vascular smooth muscle cells.

Vascular Nox (NADPH Oxidase) Compartmentalization, Protein Hyperoxidation, and Endoplasmic Reticulum Stress Response in Hypertension

Vascular Nox (NADPH oxidase)-derived reactive oxygen species and endoplasmic reticulum (ER) stress have been implicated in hypertension. However, relationships between these processes are unclear. We hypothesized that Nox isoforms localize in a subcellular compartment-specific manner, contributing to oxidative and ER stress, which influence the oxidative proteome and vascular function in hypertension. Nox compartmentalization (cell fractionation), O₂^- (lucigenin), H₂O₂ (amplex red), reversible protein oxidation (sulfenylation), irreversible protein oxidation (protein tyrosine phosphatase, peroxiredoxin oxidation), and ER stress (PERK [protein kinase RNA-like endoplasmic reticulum kinase], IRE1α [inositol-requiring enzyme 1], and phosphorylation/oxidation) were studied in spontaneously hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). VSMC proliferation was measured by fluorescence-activated cell sorting, and vascular reactivity assessed in stroke-prone SHR arteries by myography. Noxs were downregulated by short interfering RNA and pharmacologically. In SHR, Noxs were localized in specific subcellular regions: Nox1 in plasma membrane and Nox4 in ER. In SHR, oxidative stress was associated with increased protein sulfenylation and hyperoxidation of protein tyrosine phosphatases and peroxiredoxins. Inhibition of Nox1 (NoxA1ds), Nox1/4 (GKT137831), and ER stress (4-phenylbutyric acid/tauroursodeoxycholic acid) normalized SHR vascular reactive oxygen species generation. GKT137831 reduced IRE1α sulfenylation and XBP1 (X-box binding protein 1) splicing in SHR. Increased VSMC proliferation in SHR was normalized by GKT137831, 4-phenylbutyric acid, and STF083010 (IRE1-XBP1 disruptor). Hypercontractility in the stroke-prone SHR was attenuated by 4-phenylbutyric acid. We demonstrate that protein hyperoxidation in hypertension is associated with oxidative and ER stress through upregulation of plasmalemmal-Nox1 and ER-Nox4. The IRE1-XBP1 pathway of the ER stress response is regulated by Nox4/reactive oxygen species and plays a role in the hyperproliferative VSMC phenotype in SHR. Our study highlights the importance of Nox subcellular compartmentalization and interplay between cytoplasmic reactive oxygen species and ER stress response, which contribute to the VSMC oxidative proteome and vascular dysfunction in hypertension.

Development of a selective, solvent-free epoxidation of limonene using hydrogen peroxide and a tungsten-based catalyst

Kinetic and modelling of the highly selective epoxidation of limonene with hydrogen peroxide (H₂O₂) in a solvent-free environment.

Abstract 029: Nox5 is a Pro-contractile Nox Isoform - Implications in Vascular Contraction and Cardiac Fibrosis

The functional significance of Nox5 is unknown. Considering the fact that Nox5 is closely associated with changes in [Ca 2+ ] and that it generates ROS, both of which are important in contraction, we questioned whether Nox5 plays a role in pro-contractile signaling and whether it influences vascular function. We generated humanised Nox5 mice with Nox5 expressed in a VSMC-specific manner (Nox5+SM22+). Vascular contraction was measured by myography. ROS production was assessed by HPLC, amplex red and ELISA. Protein levels were evaluated by immunoblotting. Fibrosis was assessed by Picro Sirius red staining and polarized microscopy. Contraction to U46619 was increased in Nox5+/SM22+ mice (5.8±0.3 mN vs WT: 4.2±0.2 mN, p<0.05), an effect blocked by a NAC (ROS scavenger), calmidazolium (calmodulin inhibitor), dantrolene (ryanodine receptor Ca 2+ channel inhibitors) and CDN1163 (SERCA channel activator). ONOO - levels were increased in vessels from Nox5+/SM22+ (5.8±0.9 vs WT 3.4±0.1 AU/mg, p<0.05). ZIPK is an important regulator of MYPT1 inactivation. In vessels from Nox5+/SM22+ mice, ZIPK activation was increased (58.6±3.64 vs 27.73±7.64 AU, p<0.05). VSMC-Nox5 exhibited increased cardiac levels of superoxide (WT: 606.3±78.5 vs 1456.0±184.8 nmol/mg of protein), H2O2 (WT: 11.1±1.3 vs 23.88±5.1 μM/μg of protein) lipid peroxidation (WT: 0.70±0.09 vs 1.18±0.18 nmol/ μg of protein), cardiac fibrosis (WT: 3.46±1.71 vs 4.39±0.04 AU), p38 MAPK activation (WT:0.98±0.04 vs 1.61±0.12 AU) and fibronectin expression (WT:1.23±0.07 vs 2.31±0.29 AU) (p<0.05). Moreover, peroxiredoxin oxidation was increased (WT: 1.43±0.4 vs 6.28±2.0 AU, p<0.05). In VSMCs, downregulation of Nox5, but not Nox1,2,4, by siRNA was associated with reduced phosphorylation of MLC20 and MYPT1. In conclusion, our results demonstrate that Nox5 regulates vascular contraction through processes that involve , ROS, calmodulin, ryanodine and ER-Ca 2+ channels. Nox5 may be an important regulator of the contractile machinery in VSMCs. In addition, VSMC-Nox5 induces oxidative stress in the heart, leading to fibrosis. Our study defines a novel role for Nox5 as a pro-contractile Nox isoform that may have important implications in conditions associated with vascular hypercontractility.

Abstract P510: Nox4 Deficiency Leads to Hypertension and Vascular Damage With Enhanced Effects in Ang II-dependent Hypertension

We previously showed that Nox1 and Nox2 are not involved in chronic Ang II-dependent hypertension, which recapitulates human hypertension. Here we questioned the role of Nox4 by studying transgenic mice expressing human renin (LinA3) crossed with Nox4-/- mice. Four groups were used: wildtype (WT), LinA3, Nox4 KO (Nox4), and LinA3/Nox4 KO (LinA3/Nox4). Blood pressure was measured by tail cuff. Aorta was collected to assess wall thickness, collagen and glycosaminoglycans (GAGs) deposition, and TNFα expression. Mesenteric arteries were used to access vascular function by myography. Blood pressure was increased in LinA3, Nox4 and LinA3/Nox4 mice vs WT (p<0.05). All three experimental groups exhibited vascular remodeling with evidence of increased fibrosis. Although LinA3 had increased aortic wall thickness (+31%), there was no significant change in collagen (10.3±3 vs. 8.5±2% in WT) and GAGs (6.6±3 vs 2.8±2% in WT) deposition (p<0.05). Nox4 mice, which presented a similar increase in wall thickness to LinA3 (+31%), had significant increase in collagen (20.6±6%) and GAGs (22.3±4%) in aorta (p<0.05). In LinA3/Nox4 mice, collagen (24.6±7%) and GAGs (37.1±10%) deposition were increased vs LinA3. TNFα was increased in LinA3 (130.4±6 a.u.) and LinA3/Nox4 mice (129±5 a.u.) vs WT (116.8±9 a.u.) (p<0.05). Mesenteric arteries from LinA3, Nox4 and LinA3/Nox4 mice, exhibit increased Phenylephrine-induced vasoconstriction vs WT (Emax: WT 6.79±0.29 vs LinA3 9.37±0.51; Nox4 9.87±1.59; LinA3/Nox4 9.12±1.63, p<0.05). Endothelium-dependent vasodilation was not reduced in Nox4 but impaired in LinA3 and LinA3/Nox4 (Emax: WT 86.48±0.01 vs LinA3 59.70±0.03; LinA3/Nox4 33.57±0.26, p<0.05). In conclusion, Nox4 deficiency was associated with increased blood pressure, vascular dysfunction and fibrosis, effects that were variably enhanced in LinA3/Nox4 mice. We also observed that the fibrosis in vessels from Nox4 mice was not associated with inflammation. These results suggest that Nox4 may be cardiovascular protective, which when downregulated leads to blood pressure elevation and vascular injury, processes that may be amplified by Ang II-dependent hypertension.

Vascular dysfunction and fibrosis in stroke-prone spontaneously hypertensive rats: The aldosterone-mineralocorticoid receptor-Nox1 axis

AIMS

We questioned whether aldosterone and oxidative stress play a role in vascular damage in severe hypertension and investigated the role of Nox1 in this process.

MATERIALS AND METHODS

We studied mesenteric arteries, aortas and vascular smooth muscle cells (VSMC) from WKY and SHRSP rats. Vascular effects of eplerenone or canrenoic acid (CA) (mineralocorticoid receptor (MR) blockers), ML171 (Nox1 inhibitor) and EHT1864 (Rac1/2 inhibitor) were assessed. Nox1-knockout mice were also studied. Vessels and VSMCs were probed for Noxs, reactive oxygen species (ROS) and pro-fibrotic/inflammatory signaling.

KEY FINDINGS

Blood pressure and plasma levels of aldosterone and galectin-3 were increased in SHRSP versus WKY. Acetylcholine-induced vasorelaxation was decreased (61% vs 115%) and phenylephrine-induced contraction increased in SHRSP versus WKY (Emax 132.8% vs 96.9%, p<0.05). Eplerenone, ML171 and EHT1864 attenuated hypercontractility in SHRSP. Vascular expression of collagen, fibronectin, TGFβ, MCP-1, RANTES, MMP2, MMP9 and p66Shc was increased in SHRSP versus WKY. These changes were associated with increased ROS generation, 3-nitrotyrosine expression and Nox1 upregulation. Activation of vascular p66Shc and increased expression of Nox1 and collagen I were prevented by CA in SHRSP. Nox1 expression was increased in aldosterone-stimulated WKY VSMCs, an effect that was amplified in SHRSP VSMCs (5.2vs9.9 fold-increase). ML171 prevented aldosterone-induced VSMC Nox1-ROS production. Aldosterone increased vascular expression of fibronectin and PAI-1 in wild-type mice but not in Nox1-knockout mice.

SIGNIFICANCE

Our findings suggest that aldosterone, which is increased in SHRSP, induces vascular damage through MR-Nox1-p66Shc-mediated processes that modulate pro-fibrotic and pro-inflammatory signaling pathways.

Serotonin Signaling Through the 5-HT1B Receptor and NADPH Oxidase 1 in Pulmonary Arterial Hypertension

OBJECTIVE

Serotonin can induce human pulmonary artery smooth muscle cell (hPASMC) proliferation through reactive oxygen species (ROS), influencing the development of pulmonary arterial hypertension (PAH). We hypothesize that in PASMCs, serotonin induces oxidative stress through NADPH-oxidase-derived ROS generation and reduced Nrf-2 (nuclear factor [erythroid-derived 2]-like 2) antioxidant systems, promoting vascular injury.

APPROACH AND RESULTS

HPASMCs from controls and PAH patients, and PASMCs from Nox1^-/- mice, were stimulated with serotonin in the absence/presence of inhibitors of Src kinase, the 5-HT_1B receptor, and NADPH oxidase 1 (Nox1). Markers of fibrosis were also determined. The pathophysiological significance of our findings was examined in vivo in serotonin transporter overexpressing female mice, a model of pulmonary hypertension. We confirmed thatserotonin increased superoxide and hydrogen peroxide production in these cells. For the first time, we show that serotonin increased oxidized protein tyrosine phosphatases and hyperoxidized peroxiredoxin and decreased Nrf-2 and catalase activity in hPASMCs. ROS generation was exaggerated and dependent on cellular Src-related kinase, 5-HT_1B receptor, and the serotonin transporter in human pulmonary artery smooth muscle cells from PAH subjects. Proliferation and extracellular matrix remodeling were exaggerated in human pulmonary artery smooth muscle cells from PAH subjects and dependent on 5-HT_1B receptor signaling and Nox1, confirmed in PASMCs from Nox1^-/- mice. In serotonin transporter overexpressing mice, SB216641, a 5-HT_1B receptor antagonist, prevented development of pulmonary hypertension in a ROS-dependent manner.

CONCLUSIONS

Serotonin can induce cellular Src-related kinase-regulated Nox1-induced ROS and Nrf-2 dysregulation, contributing to increased post-translational oxidative modification of proteins and activation of redox-sensitive signaling pathways in hPASMCs, associated with mitogenic responses. 5-HT_1B receptors contribute to experimental pulmonary hypertension by inducing lung ROS production. Our results suggest that 5-HT_1B receptor-dependent cellular Src-related kinase-Nox1-pathways contribute to vascular remodeling in PAH.

Applied in situ product recovery in ABE fermentation

The production of biobutanol is hindered by the product's toxicity to the bacteria, which limits the productivity of the process. In situ product recovery of butanol can improve the productivity by removing the source of inhibition. This paper reviews in situ product recovery techniques applied to the acetone butanol ethanol fermentation in a stirred tank reactor. Methods of in situ recovery include gas stripping, vacuum fermentation, pervaporation, liquid–liquid extraction, perstraction, and adsorption, all of which have been investigated for the acetone, butanol, and ethanol fermentation. All techniques have shown an improvement in substrate utilization, yield, productivity or both. Different fermentation modes favored different techniques. For batch processing gas stripping and pervaporation were most favorable, but in fed‐batch fermentations gas stripping and adsorption were most promising. During continuous processing perstraction appeared to offer the best improvement. The use of hybrid techniques can increase the final product concentration beyond that of single‐stage techniques. Therefore, the selection of an in situ product recovery technique would require comparable information on the energy demand and economics of the process. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:563–579, 2017

A comparison of the energy use of in situ product recovery techniques for the Acetone Butanol Ethanol fermentation

The productivity of the Acetone Butanol Ethanol (ABE) fermentation can be significantly increased by application of various in situ product recovery (ISPR) techniques. There are numerous technically viable processes, but it is not clear which is the most economically viable in practice. There is little available information about the energy requirements and economics of ISPR for the ABE fermentation. This work compares various ISPR techniques based on UniSim process simulations of the ABE fermentation. The simulations provide information on the process energy and separation efficiency, which is fed into an economic assessment. Perstraction was the only technique to reduce the energy demand below that of a batch process, by approximately 5%. Perstraction also had the highest profit increase over a batch process, by 175%. However, perstraction is an immature technology, so would need significant development before being integrated to an industrial process.

Abstract 057: Nox5 Induces Vascular Dysfunction and Arterial Remodelling Independently of Blood Pressure Elevation in Ang II-infused Nox5-expressing Mice

Nox5 is a unique Ca 2+ -sensitive Nox isoform that is expressed in human vascular smooth muscle cells (VSMC). Although Nox5 has been implicated in diabetic nephropathy, its role in vascular function and development of hypertension remain unclear. Nox5 is not expressed in rodents, and accordingly we generated humanised Nox5 mice with Nox5 expressed in a VSMC-specific manner (Nox5SM22). Control (wild-type) and Nox5SM22 mice were infused with Ang II (600 ng/Kg/day). Blood pressure (BP) was assessed by tail-cuff. Vascular function and structure of resistance arteries were measured by myography. Ang II increased BP in WT (182.5±10 mmHg) and Nox5SM22 mice (173.1±5 mmHg) with no significant differences. Arteries from Nox5SM22 mice exhibited reduced endothelium-dependent relaxation versus WT controls (%ACh relaxation: 55.1±4 vs ctl: 81.6±7%). Fasudil (Rho kinase inhibitor)-induced relaxation was reduced in Nox5SM22 mice versus controls (%Fas: 111.3±11 vs ctl: 166.6±8%) (p<0.05). Ang II increased the maximal contraction to U46619 (thromboxane A2 mimetic) in WT (115.8±2 vs untreated: 101.4±2%) and Nox5SM22 (121.3±3 vs untreated: 99.1±2) (p<0.05) and induced endothelial dysfunction in all groups. Fasudil-induced relaxation was impaired by Ang II in WT (102.7±6 vs untreated: 166.6±8%, p<0.05) but not further impaired in Nox5SM22 mice (114.9±6 vs untreated: 111.3±11%). Ang II increased cross-sectional area (CSA) and lumen diameter; while in Nox5SM22 mice, Ang II increased wall thickness, wall-to-lumen ratio, CSA and decreased lumen diameter, with associated increased vascular stiffness. Our findings indicate that in mice expressing human Nox5 in VSMCs, endothelium-dependent relaxation is impaired, fasudil-mediated vasodilation is attenuated and vessels undergo exaggerated hypertrophic inward remodelling with increased stiffness; processes that occur independently of BP elevation. These data suggest an important role for Nox5 in Ang II-induced vascular dysfunction and remodeling, but not in the development of hypertension. Moreover, we identify Rho kinase as a putative target for Nox5-induced vascular injury. We provide novel insights into Nox5 vascular biology and demonstrate that vascular Nox5 actions are dissociated from BP effects.

Nicotinamide Adenine Dinucleotide Phosphate Oxidase-Mediated Redox Signaling and Vascular Remodeling by 16α-Hydroxyestrone in Human Pulmonary Artery Cells: Implications in Pulmonary Arterial Hypertension

Estrogen and oxidative stress have been implicated in pulmonary arterial hypertension (PAH). Mechanisms linking these systems are elusive. We hypothesized that estrogen metabolite, 16α-hydroxyestrone (16αOHE1), stimulates nicotinamide adenine dinucleotide phosphate oxidase (Nox)-induced reactive oxygen species (ROS) generation and proliferative responses in human pulmonary artery smooth muscle cells (hPASMCs) and that in PAH aberrant growth signaling promotes vascular remodeling. The pathophysiological significance of estrogen-Nox-dependent processes was studied in female Nox1(-/-) and Nox4(-/-) mice with PAH. PASMCs from control subjects (control hPASMCs) and PAH patients (PAH-hPASMCs) were exposed to estrogen and 16αOHE1 in the presence/absence of inhibitors of Nox, cytochrome P450 1B1, and estrogen receptors. Estrogen, through estrogen receptor-α, increased Nox-derived ROS and redox-sensitive growth in hPASMCs, with greater effects in PAH-hPASMCs versus control hPASMCs. Estrogen effects were inhibited by cytochrome P450 1B1 blockade. 16αOHE1 stimulated transient ROS production in hPASMCs, with sustained responses in PAH-hPASMCs. Basal expression of Nox1/Nox4 was potentiated in PAH-hPASMCs. In hPASMCs, 16αOHE1 increased Nox1 expression, stimulated irreversible oxidation of protein tyrosine phosphatases, decreased nuclear factor erythroid-related factor 2 activity and expression of nuclear factor erythroid-related factor 2-regulated antioxidant genes, and promoted proliferation. This was further amplified in PAH-hPASMCs. Nox1(-/-) but not Nox4(-/-) mice were protected against PAH and vascular remodeling. Our findings demonstrate that in PAH-hPASMCs, 16αOHE1 stimulates redox-sensitive cell growth primarily through Nox1. Supporting this, in vivo studies exhibited protection against pulmonary hypertension and remodeling in Nox1(-/-) mice. This study provides new insights through Nox1/ROS and nuclear factor erythroid-related factor 2 whereby 16αOHE1 influences hPASMC function, which when upregulated may contribute to vascular injury in PAH, particularly important in women.

Abstract P083: Gender Specific Effects in Nox4-/- Mice in Hypoxia Induced Pulmonary Hypertension and Pulmonary Vascular Resistance

Oxidative stress and Noxs have been implicated in the pathogenesis of experimental and human pulmonary arterial hypertension (PH). Gender differences in PH may be, in part, due to increased formation of NADPH oxidase (Nox) derived reactive oxygen species (ROS). A large body of evidence implicates E2 in the pathogenesis of PAH and an interaction between E2 and Noxs has been suggested. We hypothesised that i) Estrogen (E2) leads to Nox-induced oxidative stress, which promotes PASMC damage, ii) E2-induced Nox activation may account for gender differences in PH.

Cultured human PASMC were stimulated with E2 (1nM). ROS production was assessed by chemiluminescence (O2-) and proliferation by BrdU assay. E2 increased superoxide (219%; p<0.05) and proliferation in PASMC, effects blocked by GKT137831 (Nox4/1 inhibitor).

In vivo studies were conducted to assess the role of Nox4 in hypoxia-induced pulmonary hypertension in male and female mice. Hypobaric hypoxia was used to induce PH in mice, which were divided into 8 groups: normoxic WT (NWT), hypoxic WT (HWT), normoxic Nox4-/- (NKO) and hypoxic Nox4-/- (HKO) for both male and female mice. In male HWT mice, RVSP (20.5 NWT vs. 45.2mmHg HWT, p<0.001) and RVH by Fulton Index (0.20 NWT vs. 0.395 HWT, p<0.01) were increased, an effect that was significantly reduced in male Nox4-/- mice (RVSP: 36.4mmHg HKO; RVH: 0.030 HKO; p<0.05). In female HWT mice, RVSP (21.4 NWT vs. 39.8mmHg HWT, p<0.05) and RVH (0.20 NWT vs. 0.31 HWT, p<0.01) were elevated in hypoxia, yet female Nox4-/- mice were not protected against hypoxia-induced PAH (RVSP: 34.2mmHg HKO; RVH: 0.33 HKO).

Hypoxia-induced endothelial dysfunction in both male and female WT pulmonary arteries was improved in male HKO, however, endothelial dysfunction remained in HKO females. In female Nox4-/- mice, increased spleen and uterine weight (which has been associated with altered ovarian hormone biogenesis) suggests a role for inflammatory and fibrotic processes.

In conclusion, genetic ablation of Nox4 in males, but not females, protects against the development of hypoxic PH. The effects of E2 on oxidative stress is present in PASMCs where Nox4-derived ROS may be an important regulator of, and impact on, molecular processes contributing to vascular remodelling in PAH.

A more robust model of the biodiesel reaction, allowing identification of process conditions for significantly enhanced rate and water tolerance

A more robust kinetic model of base-catalysed transesterification than the conventional reaction scheme has been developed. All the relevant reactions in the base-catalysed transesterification of rapeseed oil (RSO) to fatty acid methyl ester (FAME) were investigated experimentally, and validated numerically in a model implemented using MATLAB. It was found that including the saponification of RSO and FAME side reactions and hydroxide-methoxide equilibrium data explained various effects that are not captured by simpler conventional models. Both the experiment and modelling showed that the "biodiesel reaction" can reach the desired level of conversion (>95%) in less than 2min. Given the right set of conditions, the transesterification can reach over 95% conversion, before the saponification losses become significant. This means that the reaction must be performed in a reactor exhibiting good mixing and good control of residence time, and the reaction mixture must be quenched rapidly as it leaves the reactor.

Biodiesel production from indigenous microalgae grown in wastewater

This paper describes a process for producing biodiesel sustainably from microalgae grown in wastewater, whilst significantly reducing the wastewater's nutrients and total coliform. Furthermore, ozone-flotation harvesting of the resultant biomass was investigated, shown to be viable, and resulted in FAMEs of greater oxidation stability. Desmodesmus sp. and two mixed cultures were successfully grown on wastewater. Desmodesmus sp. grew rapidly, to a higher maximum biomass concentration of 0.58 g/L. A native mixed culture dominated by Oscillatoria and Arthrospira, reached 0.45 g/L and exhibited the highest lipid and FAME yield. The FAME obtained from ozone-flotation exhibited the greatest oxidative stability, as the degree of saturation was high. In principle ozone could therefore be used as a combined method of harvesting and reducing FAME unsaturation. During microalgae treatment, the total nitrogen in wastewater was reduced by 55.4-83.9%. More importantly, total coliform removal was as high as 99.8%.

The gastrointestinal peptide obestatin induces vascular relaxation via specific activation of endothelium-dependent NO signalling

BACKGROUND AND PURPOSE

Obestatin is a recently discovered gastrointestinal peptide with established metabolic actions, which is linked to diabetes and may exert cardiovascular benefits. Here we aimed to investigate the specific effects of obestatin on vascular relaxation.

EXPERIMENTAL APPROACH

Cumulative relaxation responses to obestatin peptides were assessed in rat isolated aorta and mesenteric artery (n≥ 8) in the presence and absence of selective inhibitors. Complementary studies were performed in cultured bovine aortic endothelial cells (BAEC).

KEY RESULTS

Obestatin peptides elicited concentration-dependent relaxation in both aorta and mesenteric artery. Responses to full-length obestatin(1-23) were greater than those to obestatin(1-10) and obestatin(11-23). Obestatin(1-23)-induced relaxation was attenuated by endothelial denudation, l-NAME (NOS inhibitor), high extracellular K(+) , GDP-β-S (G-protein inhibitor), MDL-12,330A (adenylate cyclase inhibitor), wortmannin (PI3K inhibitor), KN-93 (CaMKII inhibitor), ODQ (guanylate cyclase inhibitor) and iberiotoxin (BK(Ca) blocker), suggesting that it is mediated by an endothelium-dependent NO signalling cascade involving an adenylate cyclase-linked GPCR, PI3K/PKB, Ca(2+) -dependent eNOS activation, soluble guanylate cyclase and modulation of vascular smooth muscle K(+) . Supporting data from BAEC indicated that nitrite production, intracellular Ca(2+) and PKB phosphorylation were increased after exposure to obestatin(1-23). Relaxations to obestatin(1-23) were unaltered by inhibitors of candidate endothelium-derived hyperpolarizing factors (EDHFs) and combined SK(Ca) /IK(Ca) blockade, suggesting that EDHF-mediated pathways were not involved.

CONCLUSIONS AND IMPLICATIONS

Obestatin produces significant vascular relaxation via specific activation of endothelium-dependent NO signalling. These actions may be important in normal regulation of vascular function and are clearly relevant to diabetes, a condition characterized by endothelial dysfunction and cardiovascular complications.

Surgical optimization and characterization of a minimally invasive aortic banding procedure to induce cardiac hypertrophy in mice

Left ventricular pressure overload in response to aortic banding is an invaluable model for studying progression of cardiac hypertrophy and transition to heart failure. Traditional aortic banding has recently been superceded by minimally invasive transverse aortic banding (MTAB), which does not require ventilation so is less technically challenging. Although the MTAB approach is superior, few laboratories have documented success, and minimal information on the model is available. The aim of this study was to optimize conditions for MTAB and to characterize the development and progression of cardiac hypertrophy. Isofluorane proved the most suitable anaesthetic for MTAB surgery in mice, and 1 week after surgery the MTAB animals showed significant increases in systolic blood pressure (MTAB 110 ± 6 mmHg versus sham 78 ± 3 mmHg, n = 7, P < 0.0001) and heart weight to body weight ratio (MTAB 6.2 ± 0.2 versus sham 5.1 ± 0.1, n = 12, P < 0.001), together with systolic (e.g. fractional shortening, MTAB 31.7 ± 1% versus sham 36.6 ± 1.4%, P = 0.01) and diastolic dysfunction (e.g. left ventricular end-diastolic pressure, MTAB 12.7 ± 1.0 mmHg versus sham 6.7 ± 0.8 mmHg, P < 0.001). Leucocyte infiltration to the heart was evident after 1 week in MTAB hearts, signifying an inflammatory response. More pronounced remodelling was observed 4 weeks postsurgery (heart weight to body weight ratio, MTAB 9.1 ± 0.6 versus sham 4.6 ± 0.04, n = 10, P < 0.0001) and fractional shortening was further decreased (MTAB 24.3 ± 2.5% versus sham 43.6 ± 1.7%, n = 10, P = 0.003), together with a significant increase in cardiac fibrosis and further cardiac inflammation. Our findings demonstrate that MTAB is a relevant experimental model for studying development and progression of cardiac hypertrophy, which will be highly valuable for future studies examining potential novel therapeutic interventions in this setting.

Triglyceride cracking for biofuel production using a directly synthesised sulphated zirconia catalyst

In this study, sulphated zirconia was directly synthesised and compared to the conventional wet method of preparation. The surface areas and pore sizes were 169 m(2)/g, 0.61 μm (directly synthesized) and 65 m(2)/g, 0.24 μm (conventional method), respectively. Directly synthesized sulphated zirconia was amorphous, whereas conventionally prepared sulphated zirconia is polycrystalline. Their IR spectra were broadly similar, although the area of the 1250 to 950 cm(-1) band was larger for directly synthesised sulphated zirconia. Not only were conversions greater for directly synthesised sulphated zirconia (63% vs. 42% after 4h), but it exhibited significantly greater yield for fatty acid methyl esters. The percentage yield (after 1h) of methyl esters was 43% for the directly synthesised catalyst and 15% for the conventionally synthesised.

Nox2 NADPH oxidase promotes pathologic cardiac remodeling associated with Doxorubicin chemotherapy

Doxorubicin is a highly effective cancer treatment whose use is severely limited by dose-dependent cardiotoxicity. It is well established that doxorubicin increases reactive oxygen species (ROS) production. In this study, we investigated contributions to doxorubicin cardiotoxicity from Nox2 NADPH oxidase, an important ROS source in cardiac cells, which is known to modulate several key processes underlying the myocardial response to injury. Nox2-deficient mice (Nox2-/-) and wild-type (WT) controls were injected with doxorubicin (12 mg/kg) or vehicle and studied 8 weeks later. Echocardiography indicated that doxorubicin-induced contractile dysfunction was attenuated in Nox2-/- versus WT mice (fractional shortening: 29.5±1.4 versus 25.7±1.0%; P<0.05). Similarly, in vivo pressure-volume analysis revealed that systolic and diastolic function was preserved in doxorubicin-treated Nox2-/- versus WT mice (ejection fraction: 52.6±2.5 versus 28.5±2.3%, LVdP/dtmin: -8,379±416 versus -5,198±527 mmHg s(-1); end-diastolic pressure-volume relation: 0.051±0.009 versus 0.114±0.012; P<0.001). Furthermore, in response to doxorubicin, Nox2-/- mice exhibited less myocardial atrophy, cardiomyocyte apoptosis, and interstitial fibrosis, together with reduced increases in profibrotic gene expression (procollagen IIIαI, transforming growth factor-β3, and connective tissue growth factor) and matrix metalloproteinase-9 activity, versus WT controls. These alterations were associated with beneficial changes in NADPH oxidase activity, oxidative/nitrosative stress, and inflammatory cell infiltration. We found that adverse effects of doxorubicin were attenuated by acute or chronic treatment with the AT1 receptor antagonist losartan, which is commonly used to reduce blood pressure. Our findings suggest that ROS specifically derived from Nox2 NADPH oxidase make a substantial contribution to several key processes underlying development of cardiac contractile dysfunction and remodeling associated with doxorubicin chemotherapy.