Microfluidic-controlled manufacture of liposomes for the solubilisation of a poorly water soluble drug

Besides their well-described use as delivery systems for water-soluble drugs, liposomes have the ability to act as a solubilizing agent for drugs with low aqueous solubility. However, a key limitation in exploiting liposome technology is the availability of scalable, low-cost production methods for the preparation of liposomes. Here we describe a new method, using microfluidics, to prepare liposomal solubilising systems which can incorporate low solubility drugs (in this case propofol). The setup, based on a chaotic advection micromixer, showed high drug loading (41 mol%) of propofol as well as the ability to manufacture vesicles with at prescribed sizes (between 50 and 450 nm) in a high-throughput setting. Our results demonstrate the ability of merging liposome manufacturing and drug encapsulation in a single process step, leading to an overall reduced process time. These studies emphasise the flexibility and ease of applying lab-on-a-chip microfluidics for the solubilisation of poorly water-soluble drugs.

MRI pressure and stress measurement in novel homogeneous soft solids

This paper presents MRI measurements of a novel semi solid MR contrast agent to pressure. The agent is comprised of potassium chloride cross linked carageenan gum at a concentration of 2% w/v, with micron size lipid coated bubbles of air at a concentration of 3% v/v. The choice for an optimum suspending medium, the methods of production and the preliminary MRI results are presented herein. The carageenan gum is shown to be ideally elastic for compressions relating to volume changes less than 15%, in contrast to the inelastic gellan gum also tested. Although slightly lower than that of gellan gum, carageenan has a water diffusion coefficient of 1.72×10-9 m2.s-1 indicating its suitability to this purpose. RARE imaging is performed whilst simultaneously compressing test and control samples and a maximum sensitivity of 1.6% MR signal change per % volume change is found which is shown to be independent of proton density variations due to the presence of microbubbles and compression. This contrast agent could prove useful for numerous applications, and particularly in chemical engineering. More generally the method allows the user to non-invasively image with MRI any process that causes, within the solid, local changes either in bubble size or bubble shape. © 2008 American Institute of Physics.

A pragmatic approach for engineering porous mannitol and mechanistic evaluation of particle performance

The importance of mannitol has increased recently as an emerging diluent for orodispersible dosage forms. The study aims to prepare spray dried mannitol retaining high porosity and mechanical strength for the development of orally disintegrating tablets (ODTs). Aqueous feed of d-mannitol (10% w/v) comprising ammonium bicarbonate, NH4HCO3 (5% w/v) as pore former was spray dried at inlet temperature of 110-170°C. Compacts were prepared at 151MPa and characterized for porosity, hardness and disintegration time. Particle morphology and drying mechanisms were studied using thermal (HSM, DSC and TGA) and polymorphic (XRD) methods. Tablet porosity increased from 0.20±0.002 for pure mannitol to 0.53±0.03 using fabricated porous mannitol. Disintegration time dropped by 50-77% from 135±5.29s for pure mannitol to 75.33±2.52-31.67±1.53s for mannitol 110-170°C. Hardness increased by 150% at 110°C (258.67±28.89N) and 30% at 150°C (152.70±10.58N) compared to pure mannitol tablets (104.17±1.70N). Increasing inlet temperature resulted in reducing tablet hardness due to generation of 'micro-sponge'-like particles exhibiting significant elastic recovery. Impact of mannitol polymorphism on plasticity/elasticity cannot be ruled out as a mixture of α and β polymorphs formed upon spray drying.

Paediatric drug development of ramipril:reformulation, in vitro and in vivo evaluation

Ramipril is used mainly for the treatment of hypertension and to reduce incidence of fatality following heart attacks in patients who develop indications of congestive heart failure. In the paediatric population it is used most commonly for the treatment of heart failure, hypertension in type 1 diabetes and diabetic nephropathy. Due to the lack of a suitable liquid formulation, the current study evaluates the development of a range of oral liquid formulations of ramipril along with their in vitro and in vivo absorption studies. Three different formulation development approaches were studied: solubilisation using acetic acid as a co-solvent, complexation with hydroxypropyl-β-cyclodextrin (HP-β-CD) and suspension development using xanthan gum. Systematic optimisation of formulation parameters for the different strategies resulted in the development of products stable for twelve months at long term stability conditions. In vivo evaluation showed CMAX of 10.48 µg/mL for co-solvent, 13.04µg/ml for the suspension and 29.58µg/mL for the cyclodextrin based ramipril solution. Interestingly, both ramipril solution (co-solvent) and the suspension showed a TMAX of 2.5h, however, cyclodextrin based ramipril produced TMAX at 0.75h following administration. The results presented in this study provide translatable products for oral liquid ramipril which offer preferential paediatric use over existing alternatives.

Effect of incorporating cholesterol into DDA:TDB liposomal adjuvants on Bilayer properties, biodistribution, and immune responses

Cholesterol is an abundant component of mammalian cell membranes and has been extensively studied as an artificial membrane stabilizer in a wide range of phospholipid liposome systems. In this study, the aim was to investigate the role of cholesterol in cationic liposomal adjuvant system based on dimethyldioctadecylammonium (DDA) and trehalose 6,6'-dibehenate (TDB) which has been shown as a strong adjuvant system for vaccines against a wide range of diseases. Packaging of cholesterol within DDA:TDB liposomes was investigated using differential scanning calorimetery and surface pressure-area isotherms of lipid monolayers; incorporation of cholesterol into liposomal membranes promoted the formation of a liquid-condensed monolayer and removed the main phase transition temperature of the system, resulting in an increased bilayer fluidity and reduced antigen retention in vitro. In vivo biodistribution studies found that this increase in membrane fluidity did not alter deposition of liposomes and antigen at the site of injection. In terms of immune responses, early (12 days after immunization) IgG responses were reduced by inclusion of cholesterol; thereafter there were no differences in antibody (IgG, IgG1, IgG2b) responses promoted by DDA:TDB liposomes with and without cholesterol. However, significantly higher levels of IFN-gamma were induced by DDA:TDB liposomes, and liposome uptake by macrophages in vitro was also shown to be higher for DDA:TDB liposomes compared to their cholesterol-containing counterparts, suggesting that small changes in bilayer mechanics can impact both cellular interactions and immune responses. © 2013 American Chemical Society.

Colloidal dual-band gap cell for photocatalytic hydrogen generation

We report that the internal quantum efficiency for hydrogen generation in spherical, Pt-decorated CdS nanocrystals can be tuned by quantum confinement, resulting in higher efficiencies for smaller than for larger nanocrystals (17.3% for 2.8 nm and 11.4% for 4.6 nm diameter nanocrystals). We attribute this to a larger driving force for electron and hole transfer in the smaller nanocrystals. The larger internal quantum efficiency in smaller nanocrystals enables a novel colloidal dual-band gap cell utilising differently sized nanocrystals and showing larger external quantum efficiencies than cells with only one size of nanocrystals (9.4% for 2.8 nm particles only and 14.7% for 2.8 nm and 4.6 nm nanocrystals). This represents a proof-of-principle for future colloidal tandem cell.

A holistic multi evidence approach to study the fragmentation behaviour of crystalline mannitol

Mannitol is an essential excipient employed in orally disintegrating tablets due to its high palatability. However its fundamental disadvantage is its fragmentation during direct compression, producing mechanically weak tablets. The primary aim of this study was to assess the fracture behaviour of crystalline mannitol in relation to the energy input during direct compression, utilising ball milling as the method of energy input, whilst assessing tablet characteristics of post-milled powders. Results indicated that crystalline mannitol fractured at the hydrophilic (011) plane, as observed through SEM, alongside a reduction in dispersive surface energy. Disintegration times of post-milled tablets were reduced due to the exposure of the hydrophilic plane, whilst more robust tablets were produced. This was shown through higher tablet hardness and increased plastic deformation profiles of the post-milled powders, as observed with a lower yield pressure through an out-of-die Heckel analysis. Evaluation of crystal state using x-ray diffraction/differential scanning calorimetry showed that mannitol predominantly retained the β-polymorph; however x-ray diffraction provided a novel method to calculate energy input into the powders during ball milling. It can be concluded that particle size reduction is a pragmatic strategy to overcome the current limitation of mannitol fragmentation and provide improvements in tablet properties.

Designing liposomal adjuvants for the next generation of vaccines

Liposomes not only offer the ability to enhance drug delivery, but can effectively act as vaccine delivery systems and adjuvants. Their flexibility in size, charge, bilayer rigidity and composition allow for targeted antigen delivery via a range of administration routes. In the development of liposomal adjuvants, the type of immune response promoted has been linked to their physico-chemical characteristics, with the size and charge of the liposomal particles impacting on liposome biodistribution, exposure in the lymph nodes and recruitment of the innate immune system. The addition of immunostimulatory agents can further potentiate their immunogenic properties. Here, we outline the attributes that should be considered in the design and manufacture of liposomal adjuvants for the delivery of sub-unit and nucleic acid based vaccines.

Vaccines

Vaccines continue to offer the key line of protection against a range of infectious diseases; however, the range of vaccines currently available is limited. One key consideration in the development of a vaccine is risk-versus-benefit, and in an environment of perceived low risk, the benefit of vaccination may not be recognised. To address this, there has been a move towards the use of subunit-based vaccines, which offer low side-effect profiles but are generally weakly immunogenic. This can be compensated for by the development of effective adjuvants. Nanotechnology offers key attributes in this field through the ability of nanoparticulates to incorporate and protect antigens from rapid degradation, combined with their potential to effectively deliver the antigens to appropriate cells within the immune system. These characteristics can be exploited in the development of new adjuvants. This chapter will outline the applications of nanosystems in vaccine formulations and consider the mechanisms of action behind a range of formulations.

Characterization of microvesicles released from human red blood cells

Background/Aims: Extracellular vesicles (EVs) are spherical fragments of cell membrane released from various cell types under physiological as well as pathological conditions. Based on their size and origin, EVs are classified as exosome, microvesicles (MVs) and apoptotic bodies. Recently, the release of MVs from human red blood cells (RBCs) under different conditions has been reported. MVs are released by outward budding and fission of the plasma membrane. However, the outward budding process itself, the release of MVs and the physical properties of these MVs have not been well investigated. The aim of this study is to investigate the formation process, isolation and characterization of MVs released from RBCs under conditions of stimulating Ca2+ uptake and activation of protein kinase C. Methods: Experiments were performed based on single cell fluorescence imaging, fluorescence activated cell sorter/flow cytometer (FACS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). The released MVs were collected by differential centrifugation and characterized in both their size and zeta potential. Results: Treatment of RBCs with 4-bromo-A23187 (positive control), lysophosphatidic acid (LPA), or phorbol-12 myristate-13 acetate (PMA) in the presence of 2 mM extracellular Ca2+ led to an alteration of cell volume and cell morphology. In stimulated RBCs, exposure of phosphatidylserine (PS) and formation of MVs were observed by using annexin V-FITC. The shedding of MVs was also observed in the case of PMA treatment in the absence of Ca2+, especially under the transmitted bright field illumination. By using SEM, AFM and DLS the morphology and size of stimulated RBCs, MVs were characterized. The sizes of the two populations of MVs were 205.8 ± 51.4 nm and 125.6 ± 31.4 nm, respectively. Adhesion of stimulated RBCs and MVs was observed. The zeta potential of MVs was determined in the range from - 40 mV to - 10 mV depended on the solutions and buffers used. Conclusion: An increase of intracellular Ca2+ or an activation of protein kinase C leads to the formation and release of MVs in human RBCs.

A málnaültetvények integrált védelmének fejlesztését elősegítő rovartani kutatások eredményei

A málna hazánk adottságainak megfelelő integrált védelmének kidolgozása fontos feladat. A folyamat részeként a Budapesti Corvinus Egyetem Rovartani Tanszékének kutatócsoportja 2002 óta rendszeres vizsgálatokat végez a jelentősebb magyarországi málnatermesztési körzetekben, melynek eredményeként új adatokkal bővültek a málna ízeltlábú közösségével, a kulcsfontosságú kártevők dominancia-viszonyaival, az egyes kártevők biológiájával és gazda–parazitoid viszonyával, valamint a málnafajták kártevőkkel szembeni ellenállóságával kapcsolatos korábbi ismereteink. Kutatómunkánk során az előzőeken túl vizsgáltuk a termesztési módok károsítókra gyakorolt hatását is. A vizsgálatok kiterjednek minden olyan további terület kutatására (rajzásmegfigyelési lehetőségek, kártevők megjelenésének pontos előrejelzése), melyek a hatékony és egyben környezetkímélő védekezés megvalósításához alapvetően szükségesek. Jelen dolgozatunkban e vizsgálatsorozat eddig elért néhány fontosabb részeredményét ismertetjük.

With the highest ideals: The Florida State Normal College at DeFuniak Springs, 1887--1905

The urgent need for teachers led the Florida legislature in 1887 to establish the Florida State Normal College at DeFuniak Springs. The college closed in 1905 with passage of the Buckman Act, which mandated a complete reorganization of state-supported higher education and ended coeducation for white students. This small college, open for eighteen years, was uniquely situated in time and place to examine larger questions in American educational history as well as contribute to the history of higher education in Florida, which developed differently than in other states.^ This historical case study used archival sources to examine this institution, and contribute to the history of the origins of Florida's system of higher education. Key questions guiding the research were the nature of the students, fundamental aspects of school life, the impact of the school on the students, and the role of the school in the development of higher education in Florida. Original sources included the Catalogs, Register and Minutes of the school. The census of 1900 was used to develop information on the backgrounds of the students. Findings were: DeFuniak Springs was chosen for the school because of the Florida Chautauqua; the school was coeducational and had few rules but the internalized social codes of the students resulted in almost no difficulties with discipline; the students, a majority of whom were women, were from middle-class southern families; the college compared favorably in faculty, facilities and curriculum to institutions elsewhere; although few students graduated, alumni played a key role in shaping Florida's common schools; and, the Buckman Act entirely changed the nature of higher education in Florida.^ Implications were: The coeducational nature of the college a hundred years ago significantly changes the picture of Florida's higher education; the school was small, but its influence far outlasted the institution; and, the school struggled with issues which continue to trouble modern educators such as finances, the legislature, student retention, underpreparedness, and the proper structuring of a curriculum, which indicates the persistence of these issues. ^

Nursing curriculum: Changing students' knowledge and biases towards older adults

Caring for the older adult is a topic debated and discussed at all levels of today's society. Nurses are expected to educate patients and family members about their medications and care following hospitalization or contact with the health care system. The majority of these patients are elderly. The purpose of the study was to determine if a course on aging would affect the knowledge and biases of nursing students in a Baccalaureate nursing program at a Southeast Florida University. Nursing students (N = 52) were surveyed at the beginning of the semester using Palmore's Facts on Aging Quiz that is structured to determine the knowledge and biases of individuals towards the older adult. Students were surveyed before and after the nursing course that had a didactic and clinical component in the hospital setting. Analysis of the data by Chi square and repeated measure ANOVA supported the hypothesis that a course segment on aging would affect the knowledge level of the nursing students and result in changes of their biases toward the older adult. ^

The impact of information technology on organizations: A study of enterprise resource planning system influences on job design and organizational culture

The primary purpose of this research is to study the linkage between perceived job design characteristics and information system environment characteristics before and after the replacement of a legacy information system with a new type of information system (referred to as an Enterprise Resource Planning or ERP system). A public state University implementing an academic version of an ERP system was selected for the study. Three survey instruments were used to examine the perception of the information system, the job characteristics, and the organizational culture before and after the system implementation. The research participants included two large departments resulting in a sample of 130 workers. Research questions were analyzed using multivariate procedures including factor analysis, path analysis, step-wise regression, and matched pair analysis. ^ Results indicated that the ERP system has introduced new elements into the working environment that has changed the perception of how the job design characteristics and organization culture dimensions are viewed by the workers. The understanding of how the perceived system characteristics align with an individual's perceived job design characteristics is supported by each of the system characteristics significantly correlated in the proposed direction. The stronger support of this relationship becomes visible in the causal flow of the effects seen in the path diagram and in the step-wise regression. The perceived job design characteristics aligning with dimensions of organizational culture are not as strong as the literature suggests. Although there are significant correlations between the job and culture variables, only one relationship can be seen in the causal flow. ^ This research has demonstrated that system characteristics of ERP do contribute to the perception of change in an organization and do support organizational culture behaviors and job characteristics. ^