CNS delivery of antisense oligodeoxynucleotides using biodegradable microspheres

Antisense oligodeoxynucleotides can selectively inhibit gene expression provided they are delivered to their target site successfully for a sufficient duration. Biodegradable microspheres have previously been developed for the potential systemic delivery of antisense oligodeoxynucleotides and offer an excellent strategy for central administration of antisense oligodeoxynucleotides, providing a sustained-release delivery system. Biodegradable microspheres were formulated to entrap antisense oligodeoxynucleotides for stereotaxic implantation into site-specific regions of the rat brain.Release profiles of antisense oligodeoxynucleotides from biodegradable microspheres over 56 days that were triphasic were observed with high molecular weight polymers. Antisense oligodeoxynucleotides loaded into microspheres (1-10μm) had a five-fold increase in cellular association with glial and neuronal cells compared to the naked molecule, which was partially due to a greater cellular accumulation as observed by a slower efflux profile. In vivo distribution studies of antisense oligodeoxynucleotides demonstrated that the use of microspheres provided a sustained-release over more than 2 days compared to 12 hours of the naked molecule. Efficacy of antisense oligodeoxynucleotides was demonstrated during locomotor activity investigations, which significantly reduced cocaine-induced locomotor activity, where no efficacy was demonstrated with microspheres, possibly attributed to antisense loading and measurements being taken during a lag phase of antisense oligodeoxynucleotide release. Biodegradable microspheres can be delivered site-specifically into the brain and provide sustained-release of antisense oligodeoxynucleotides, offering the potential of in vivo efficacy in these reagents in the brain.

Solubility enhancement of poorly water soluble drugs using liposome technology

The aim of this work is to investigate the various parameters that could control the encapsulation of lipophilic drugs and investigate the influence of the physical properties of poorly water-soluble drugs on bilayer loading. Initial work investigated on the solubilisation of ibuprofen, a model insoluble drug. Drug loading was assessed using HPLC and UV spectrophotometric analysis. Preliminary studies focused on the influence of bilayer composition on drug loading to obtain an optimum cholesterol concentration. This was followed up by studies investigating the effect of longer alkyl chain lipids, unsaturated alkyl chain lipids and charged lipids. The studies also focused on the effects of pH of the hydration medium and addition of the single chain surfactant a-tocopherol. The work was followed up by investigation of a range of insoluble drugs including flurbiprofen, indomethacin, sulindac, mefenamic acid, lignocaine and progesterone to investigate the influence of drugs properties and functional group on liposomal loading. The results show that no defined trend could be obtained linking the drug loading to the different drug properties including molecular weight, log P and other drug specific characteristics. However, the presence of the oppositely charged lipids improved the encapsulation of all the drugs investigated with a similar effect obtained with the substitution of the longer chain lipids. The addition of the single chain surfactant a-tocopherol resulted in enhancement of drug loading and possibly is governed by the log P of the drug candidate. Environmental scanning-electron microscopy (ESEM) was used to dynamically follow the changes in liposome morphology in real time during dehydration thereby providing a alternative assay of liposome formulation and stability. The ESEM analysis clearly demonstrated ibuprofen incorporation enhanced the stability of PC:Chol liposomes.

The delivery of bioactive proteins using biodegradable microspheres

In this project, antigen-containing microspheres were produced using a range of biodegradable polymers by single and double emulsion solvent evaporation and spray drying techniques. The proteins used in this study were mainly BSA, tetanus toxoid, F1 and V, Y. pestis subunit vaccines and the cytokine, interferon-gamma. The polymer chosen for use in the vaccine preparation will directly determine the characteristics of the formulation. Full in vitro analysis of the preparations was carried out, including surface hydrophobicity and drug release profiles. The influence of the surfactants employed on microsphere surface hydrophobicity was demonstrated. Preparations produced with polyhydroxybutyrate and poly(DTH carbonate) polymers were also shown to be more hydrophobic than PLA microspheres, which may enhance particle uptake by antigen presenting cells and Peyer's patches. Systematic immunisation with microspheres with a range of properties showed differences in the time course and extent of the immune response generated, which would allow optimisation of the dosing schedule to provide maximal response in a single dose preparation. Both systematic and mucosal responses were induced following oral delivery of microencapsulated tetanus toxoid indicating that the encapsulation of the antigen into a microsphere preparation provides protection in the gut and allows targeting of the mucosal-associated lymphoid tissue. Co-encapsulation of adjuvants for further enhancement of immune response was also carried out and the effect on loading and release pattern assessed. Co-encapsulated F1 and interferon-gamma was administered i.p. and the immune responses compared with singly encapsulated and free subunit antigen.

The targeting of corticosteroids to inflamed tissues

In recent years, much interest has focused on the beneficial effects of administering potentially harmful therapeutic agents in drug carriers so as to reduce their toxic side effects. Rheumatoid arthritis is a chronic systemic disease with progressive destruction of the Joints and long term patient disability, Corticosteroids have been shown to retard the progression of Joint destruction but are limited in their use due to adverse side effects,This project, following the line of investigation started by other workers, was designed to study the use of microspheres to deliver corticosteroids to inflamed tissues by both the oral and intravenous routes. Hydrocortisone (HC)-loaded albumin microspheres were prepared by three different methods, by direct incorporation of HC within the particles, by indirect incorporation of HC by the enzymatic conversion of hydrocortisone-21-phosphate (H-21-P) to HC within the particles, and by the adsorption of HC onto the surface. HC was also loaded with PLA microspheres. The level of corticosteriod loading and in vitro release from microspheres was determined by HPLC analysis. A reversed-phase, ion-pairing HPLC method was developed to simultaneously measure both HC and H-21-P. The highest level of corticosteroid loading was achieved using the incorporation of H-21-P with enzymatic conversion to HC method. However, HPLC analysis showed only 5% of the incorporated steroid was HC. In vitro release rates of steroid from albumin microspheres showed >95% of incorporated steroid was released within 2 hours of dissolution. Increasing the protein:steroid ratio, and the temperature and duration of microsphere stabilization, had little effect on prolonging drug release. In vivo studies, using the carrageenan-induced rat hind-paw model of inflammation, indicated steroid-incorporated microspheres administered both orally and intraperitoneally were not therapeutically advantageous when compared to equivalent free steroid doses. The ability of orally and intravenously dosed [125I]~albumin microspheres (2.67 μm mean diameter) to accumulate in acutely and chronically inflamed tissues was investigated, The subcutaneous air-pouch was the model of inflammation used, with carrageenan as the inflammatory stimulus. Acute and chronic inflammation was shown to be consistently formed  in pouch tissues in terms of cell infiltration and fluid exudate formation in the pouch cavity. Albumin microspheres were shown to accumulate in the inflamed tissues and pouch fluids after both oral and intravenous administration. Preliminary, confirmatory studies using latex microspheres and quantitation by GPC analysis, also indicated microsphere accumulation in both acutely and chronically inflamed air-pouch tissues. tntl lUr"'poucbtis,sues; The results indicate the uptake and transfer of microspheres across the gastrointestinal tract into the circulation and their migration through disrupted endothelium and basement membranes at the inflamed sites. , .

Damage analysis of bridge structures using vibrational techniques

Much research is currently centred on the detection of damage in structures using vibrational data. The work presented here examined several areas of interest in support of a practical technique for identifying and locating damage within bridge structures using apparent changes in their vibrational response to known excitation. The proposed goals of such a technique included the need for the measurement system to be operated on site by a minimum number of staff and that the procedure should be as non-invasive to the bridge traffic-flow as possible. Initially the research investigated changes in the vibrational bending characteristics of two series of large-scale model bridge-beams in the laboratory and these included ordinary-reinforced and post-tensioned, prestressed designs. Each beam was progressively damaged at predetermined positions and its vibrational response to impact excitation was analysed. For the load-regime utilised the results suggested that the infuced damage manifested itself as a function of the span of a beam rather than a localised area. A power-law relating apparent damage with the applied loading and prestress levels was then proposed, together with a qualitative vibrational measure of structural damage. In parallel with the laboratory experiments a series of tests were undertaken at the sites of a number of highway bridges. The bridges selected had differing types of construction and geometric design including composite-concrete, concrete slab-and-beam, concrete-slab with supporting steel-troughing constructions together with regular-rectangular, skewed and heavily-skewed geometries. Initial investigations were made of the feasibility and reliability of various methods of structure excitation including traffic and impulse methods. It was found that localised impact using a sledge-hammer was ideal for the purposes of this work and that a cartridge `bolt-gun' could be used in some specific cases.

A failure criterion for fillet welds

The work constitutes a study of the strength of mild steel fillet welds subject to static loading, and the behaviour of flange welded beam-column connections under combined bending and shear. Tests are conducted on short welds in the as-welded and stress relieved conditions, and also on full-size beam-column connections. It is shown that welds under compression have a lower strength than when under tension. Failure of the fillet weld is initiated at the weld root, the important factor controlling the initiation being weld ductility. The greater the residual stress, the lower the weld ductility and ultimate strength. Thermal stress relieving increases strength by as much as 30%. Weld failure plane is rarely at the throat and varies from 0° to 45° depending upon loading condition. Failure plane average stresses are related by a circular function which is expressed in terms of externally applied forces at limit state. The tension weld of a flange-welded beam-column connection always fails before the compression weld. The shear load sharing between the welds is a complex function of elastic compression of the web, elastic/plastic deformation of the flanges, load/deformation characteristics, and the type of load application. Bearing forces between the compression flange and column face produce low level bearing stresses and frictional forces which make a negligible contribution to shear load resistance. Three modes of connection failure are possible; 'end mode', 'bending mode' and 'shear mode', with a sudden change taking place between the two latter.

Parametric study of the behaviour of reinforced concrete columns in fire

The research is concerned with the application of the computer simulation technique to study the performance of reinforced concrete columns in a fire environment. The effect of three different concrete constitutive models incorporated in the computer simulation on the structural response of reinforced concrete columns exposed to fire is investigated. The material models differed mainly in respect to the formulation of the mechanical properties of concrete. The results from the simulation have clearly illustrated that a more realistic response of a reinforced concrete column exposed to fire is given by a constitutive model with transient creep or appropriate strain effect The assessment of the relative effect of the three concrete material models is considered from the analysis by adopting the approach of a parametric study, carried out using the results from a series of analyses on columns heated on three sides which produce substantial thermal gradients. Three different loading conditions were used on the column; axial loading and eccentric loading both to induce moments in the same sense and opposite sense to those induced by the thermal gradient. An axially loaded column heated on four sides was also considered. The computer modelling technique adopted separated the thermal and structural responses into two distinct computer programs. A finite element heat transfer analysis was used to determine the thermal response of the reinforced concrete columns when exposed to the ISO 834 furnace environment. The temperature distribution histories obtained were then used in conjunction with a structural response program. The effect of the occurrence of spalling on the structural behaviour of reinforced concrete column is also investigated. There is general recognition of the potential problems of spalling but no real investigation into what effect spalling has on the fire resistance of reinforced concrete members. In an attempt to address the situation, a method has been developed to model concrete columns exposed to fire which incorporates the effect of spalling. A total of 224 computer simulations were undertaken by varying the amounts of concrete lost during a specified period of exposure to fire. An array of six percentages of spalling were chosen for one range of simulation while a two stage progressive spalling regime was used for a second range. The quantification of the reduction in fire resistance of the columns against the amount of spalling, heating and loading patterns, and the time at which the concrete spalls appears to indicate that it is the amount of spalling which is the most significant variable in the reduction of fire resistance.

Engineering liposomal systems to develop solubility enhancing technology

This research primarily focused on identifying the formulation parameters which control the efficacy of liposomes as delivery systems to enhance the delivery of poorly soluble drugs. Preliminary studies focused on the drug loading of ibuprofen within vesicle systems. Initially both liposomal and niosomal formulations were screened for their drug-loading capacity: liposomal systems were shown to offer significantly higher ibuprofen loading and thereafter lipid based systems were further investigated. Given the key role cholesterol is known to play within the stability of bilayer vesicles. the optimum cholesterol content in terms of drug loading and release of poorly soluble drugs was then investigated. From these studies a concentration of 11 total molar % of cholesterol was used as a benchmark for all further formulations. Investigating the effect of liposomc composition on several low solubility drugs, drug loading was shown to be enhanced by adopting longer chain length lipids. cationic lipids and. decreasing drug molecular weight. Drug release was increased by using cationic lipids and lower molecular weight of drug; conversely, a reduction was noted when employing longer chain lipids thus supporting the rational of longer chain lipids producing more stable liposomes, a theory also supported by results obtained via Langmuir studies· although it was revealed that stability is also dependent on geometric features associated with the lipid chain moiety. Interestingly, reduction in drug loading appeared to be induced when symmetrical phospholipids were substituted for lipids constituting asymmetrical alkyl chain groups thus further highlighting the importance of lipid geometry. Combining a symmetrical lipid with an asymmetrical derivative enhanced encapsulation of a hydrophobic drug while reducing that of another suggesting the importance of drug characteristics. Phosphatidylcholine liposornes could successfully be prepared (and visualised using transmission electron microscopy) from fatty alcohols therefore offering an alternative liposomal stabiliser to cholesterol. Results obtained revealed that liposomes containing tetradecanol within their formulation shares similar vesicle size, drug encapsulation, surface charge. and toxicity profiles as liposomes formulated with cholesterol, however the tetradecanol preparation appeared to release considerably more drug during stability studies. Langmuir monolayer studies revealed that the condensing influence by tetradecanol is less than compared with cholesterol suggesting that this reduced intercalation by the former could explain why the tetradecanol formulation released more drug compared with cholesterol formulations. Environmental scanning electron microscopy (ESEM) was used to analyse the morphology and stability of liposomes. These investigations indicated that the presence of drugs within the liposomal bilayer were able to enhance the stability of the bilayers against collapse under reduced hydration conditions. In addition the presence of charged lipids within the formulation under reduced hydration conditions compared with its neutral counterpart. However the applicability of using ESEM as a new method to investigate liposome stability appears less valid than first hoped since the results are often open to varied interpretation and do not provide a robust set of data to support conclusions in some cases.

Complementary methods to investigate the development of clogging within a horizontal sub-surface flow tertiary treatment wetland

A combination of experimental methods was applied at a clogged, horizontal subsurface flow (HSSF) municipal wastewater tertiary treatment wetland (TW) in the UK, to quantify the extent of surface and subsurface clogging which had resulted in undesirable surface flow. The three dimensional hydraulic conductivity profile was determined, using a purpose made device which recreates the constant head permeameter test in-situ. The hydrodynamic pathways were investigated by performing dye tracing tests with Rhodamine WT and a novel multi-channel, data-logging, flow through Fluorimeter which allows synchronous measurements to be taken from a matrix of sampling points. Hydraulic conductivity varied in all planes, with the lowest measurement of 0.1 md1 corresponding to the surface layer at the inlet, and the maximum measurement of 1550 md1 located at a 0.4m depth at the outlet. According to dye tracing results, the region where the overland flow ceased received five times the average flow, which then vertically short-circuited below the rhizosphere. The tracer break-through curve obtained from the outlet showed that this preferential flow-path accounted for approximately 80% of the flow overall and arrived 8 h before a distinctly separate secondary flow-path. The overall volumetric efficiencyof the clogged system was 71% and the hydrology was simulated using a dual-path, dead-zone storage model. It is concluded that uneven inlet distribution, continuous surface loading and high rhizosphere resistance is responsible for the clog formation observed in this system. The average inlet hydraulic conductivity was 2 md1, suggesting that current European design guidelines, which predict that the system will reach an equilibrium hydraulic conductivity of 86 md1, do not adequately describe the hydrology of mature systems.

Two-dimensional viscoelastic discrete triangular system with negative-stiffness components

Potential applications of high-damping and high-stiffness composites have motivated extensive research on the effects of negative-stiffness inclusions on the overall properties of composites. Recent theoretical advances have been based on the Hashin-Shtrikman composite models, one-dimensional discrete viscoelastic systems and a two-dimensional nested triangular viscoelastic network. In this paper, we further analyze the two-dimensional triangular structure containing pre-selected negative-stiffness components to study its underlying deformation mechanisms and stability. Major new findings are structure-deformation evolution with respect to the magnitude of negative stiffness under shear loading and the phenomena related to dissipation-induced destabilization and inertia-induced stabilization, according to Lyapunov stability analysis. The evolution shows strong correlations between stiffness anomalies and deformation modes. Our stability results reveal that stable damping peaks, i.e. stably extreme effective damping properties, are achievable under hydrostatic loading when the inertia is greater than a critical value. Moreover, destabilization induced by elemental damping is observed with the critical inertia. Regardless of elemental damping, when the inertia is less than the critical value, a weaker system instability is identified.

Enhanced selective aerobic alcohol oxidation through nanoengineered catalyst supports

The selective conversion of alcohols to their carbonyl derivatives is a critical step towards a sustainable chemical industry. Heterogeneous Pd catalysts represent some of the most active systems known, even so further studies into the active species and role of support are required. Through controlling support mesostructure, using non-interconnected SBA-15 and interlinked SBA-16 and KIT-6, we have evaluated the role of pore architecture on supported Pd nanoparticles and their subsequent activity for liquid phase aerobic allylic alcohol selective oxidation.[1,2] These synthesised silica supports exhibit high surface areas (>800 m2g-1), and similar mesopore diameters (3.5 to 5 nm), but differ in their pore connectivity and arrangement; p6mm (SBA-15), I3mm (SBA-16) and I3ad (KIT-6). When evaluated alongside commercial non-mesoporous silica (200 m2 g-1) they promote enhanced Pd dispersion with interpenetrating assemblies providing further elevation. Macropore introduction into SBA-15, producing a hierarchical macro-mesoporous silica (MM-SBA-15), allows control over mesopore length and accessibility which escalates Pd distribution to levels akin to KIT-6 and SBA-16. Controlling dispersion, and likewise nanoparticle size, is thus facilitated through the choice of support and additionally Pd loading, with cluster sizes spanning 3.2 to 0.8 nm. X-ray spectroscopies indicate nanoparticles are PdO terminated with the oxide content a function of dispersion. Kinetic studies allude to surface PdO being the active site responsible, with a constant TOF observed, independent of loading and support. This confirms activity is governed by PdO density, whilst also overruling internal mass diffusion constraints. MM-SBA-15 facilitates superior activity and TOFs for long chain acyclic terpene alcohols due to reduced internal mass transport constraints.

Valorisation of vietnamese rice straw waste:catalytic aqueous phase reforming of hydrolysate from steam explosion to platform chemicals

A family of tungstated zirconia solid acid catalysts were synthesised via wet impregnation and subsequent thermochemical processing for the transformation of glucose to 5-hydroxymethylfurfural (HMF). Acid strength increased with tungsten loading and calcination temperature, associated with stabilisation of tetragonal zirconia. High tungsten dispersions of between 2 and 7 W atoms·nm−2 were obtained in all cases, equating to sub-monolayer coverages. Glucose isomerisation and subsequent dehydration via fructose to HMF increased with W loading and calcination temperature up to 600 °C, indicating that glucose conversion to fructose was favoured over weak Lewis acid and/or base sites associated with the zirconia support, while fructose dehydration and HMF formation was favoured over Brönsted acidic WOx clusters. Aqueous phase reforming of steam exploded rice straw hydrolysate and condensate was explored heterogeneously for the first time over a 10 wt% WZ catalyst, resulting in excellent HMF yields as high as 15% under mild reaction conditions.

Hydroxyl radical generation by cactus-like copper oxide nanoporous carbon catalysts for microcystin-LR environmental remediation

Copper oxide supported on nanoporous activated carbon (CuO-NPAC) is reported for the aqueous phase catalytic degradation of cyanotoxin microcystin-LR (MC-LR). The loading and spatial distribution of CuO throughout the NPAC matrix strongly influence the catalytic efficiency. CuO-NPAC synthesis was optimized with respect to the copper loading and thermal processing, and the physicochemical properties of the resulting materials were characterized by XRD, BET, TEM, SEM, EPR, TGA, XPS and FT-IR spectroscopy. EPR spin trapping and fluorescence spectroscopy showed in situ ˙OH formation via H2O2 over CuO-NPAC as the catalytically relevant oxidant. The impact of reaction conditions, notably CuO-NPAC loading, H2O2 concentration and solution pH, is discussed in relation to the reaction kinetics for MC-LR remediation.

All-fiber loading sensor based on 45° and 81° tilted fiber gratings

Cardiovascular health of the human population is a major concern for medical clinicians, with cardiovascular diseases responsible for 48% of all deaths worldwide, according to the World Health Organisation. Therefore the development of new practicable and economical diagnostic tools to scrutinise the cardiovascular health of humans is a major driver for clinicians. We offer a new technique to obtain seismocardiographic signals covering both ballistocardiography (below 20Hz) and audible heart sounds (20Hz upwards). The detection scheme is based upon an array of curvature/displacement sensors using fibre optic long period gratings interrogated using a variation of the derivative spectroscopy interrogation technique. © 2014 SPIE.

A review of the effects of distributed energy resources and power-electronic controlled loading on distribution network stability

This paper looks at potential distribution network stability problems under the Smart Grid scenario. This is to consider distributed energy resources (DERs) e.g. renewable power generations and intelligent loads with power-electronic controlled converters. The background of this topic is introduced and potential problems are defined from conventional power system stability and power electronic system stability theories. Challenges are identified with possible solutions from steady-state limits, small-signal, and large-signal stability indexes and criteria. Parallel computation techniques might be included for simulation or simplification approaches are required for a largescale distribution network analysis.