Differential modulation of angiogenesis by erythropoiesis-stimulating agents in a mouse model of ischaemic retinopathy

Background: Erythropoiesis stimulating agents (ESAs) are widely used to treat anaemia but concerns exist about their potential to promote pathological angiogenesis in some clinical scenarios. In the current study we have assessed the angiogenic potential of three ESAs; epoetin delta, darbepoetin alfa and epoetin beta using in vitro and in vivo models.

Methodology/Principal Findings: The epoetins induced angiogenesis in human microvascular endothelial cells at high doses, although darbepoetin alfa was pro-angiogenic at low-doses (1-20 IU/ml). ESA-induced angiogenesis was VEGF-mediated. In a mouse model of ischaemia-induced retinopathy, all ESAs induced generation of reticulocytes but only epoetin beta exacerbated pathological (pre-retinal) neovascularisation in comparison to controls (p<0.05). Only epoetin delta induced a significant revascularisation response which enhanced normality of the vasculature (p<0.05). This was associated with mobilisation of haematopoietic stem cells and their localisation to the retinal vasculature. Darbepoetin alfa also increased the number of active microglia in the ischaemic retina relative to other ESAs (p<0.05). Darbepoetin alfa induced retinal TNF alpha and VEGF mRNA expression which were up to 4 fold higher than with epoetin delta (p<0.001).

Conclusions: This study has implications for treatment of patients as there are clear differences in the angiogenic potential of the different ESAs.

The appraisal of an automated multi-immunoaffinity chromatography system to detect anabolic agents in bile and urine

Screening for residues of anabolic steroids frequently requires extraction from tissues and fluids before analysis. Chemical procedures for these extractions can be complicated, expensive to perform and not ideal for the simultaneous extraction of analytes with different solubilities. Extraction by multi-immunoaffinity chromatography (MIAC) may be used as an alternative. Samples are passed through a column containing a range of antibodies immobilized on an inert support. The desired analytes are bound to their respective antibodies, washed and then eluted by a suitable solvent. The purified extracts can then be incorporated into the analytical tests, The analytes that can be extracted presently are alpha-nortestosterone, zeranol, trenbolone, diethylstilboestrol, boldenone and dexamethasone. Manually, the MIAC procedure is limited to about six columns per operator but bq automating the process using a robotic sample processor (RSP), 48 columns can be run simultaneously during the day or night. The RSP has also been adapted to transfer extracts and reagents on to ELISA plates. The automated system has proved to be a robust and reliable means of screening large numbers of samples for anabolic agents with minimal manual input

Dual functional ionic liquids as plasticisers and antimicrobial agents for medical polymers

Contamination of medical devices with bacteria such as Meticillin resistant Staphylococcus aureus (MRSA) is of great clinical concern. Poly(vinyl chloride) is widely used in the production of medical devices, such as catheters. The flexibility of catheter tubing is derived from the addition of plasticisers. Here, we report the design of two dual functional ionic liquids, 1-ethylpyridinium docusate and tributyl(2-hydroxyethyl)phosphonium docusate, which uniquely provide a plasticising effect, and exhibit antimicrobial and antibiofilm-forming activity to a range of antibiotic resistant bacteria. The plasticisation of poly(vinyl chloride) was tailored as a function of ionic liquid concentration. The effective antimicrobial behaviour of both ionic liquids originates from the chemical structure of the anion or cation and is not limited to the length of the alkyl chain on the anion/cation. The design approach adopted will be useful in developing ionic liquids as multi-functional additives for polymers.

FKBPL and Peptide Derivatives: Novel Biological Agents That Inhibit Angiogenesis by a CD44-Dependent Mechanism

Purpose: Antiangiogenic therapies can be an important adjunct to the management of many malignancies. Here we investigated a novel protein, FKBPL, and peptide derivative for their antiangiogenic activity and mechanism of action.

Experimental Design: Recombinant FKBPL (rFKBPL) and its peptide derivative were assessed in a range of human microvascular endothelial cell (HMEC-1) assays in vitro. Their ability to inhibit proliferation, migration, and Matrigel-dependent tubule formation was determined. They were further evaluated in an ex vivo rat model of neovascularization and in two in vivo mouse models of angiogenesis, that is, the sponge implantation and the intravital microscopy models. Antitumor efficacy was determined in two human tumor xenograft models grown in severe compromised immunodeficient (SCID) mice. Finally, the dependence of peptide on CD44 was determined using a CD44-targeted siRNA approach or in cell lines of differing CD44 status.

Results: rFKBPL inhibited endothelial cell migration, tubule formation, and microvessel formation in vitro and in vivo. The region responsible for FKBPL's antiangiogenic activity was identified, and a 24-amino acid peptide (AD-01) spanning this sequence was synthesized. It was potently antiangiogenic and inhibited growth in two human tumor xenograft models (DU145 and MDA-231) when administered systemically, either on its own or in combination with docetaxel. The antiangiogenic activity of FKBPL and AD-01 was dependent on the cell-surface receptor CD44, and signaling downstream of this receptor promoted an antimigratory phenotype.

Conclusion: FKBPL and its peptide derivative AD-01 have potent antiangiogenic activity. Thus, these agents offer the potential of an attractive new approach to antiangiogenic therapy.

Adsorption and photocatalytic bleaching of acid orange 7 on P25 titania

The observed adsorption of acid orange 7, AO7(-), on P25 titania over a range of pH values (pH 2-8) gives a good fit to data generated using a charge distribution, multisite complexation, i.e. CD-MUSIC, model, modified for aggregated dye adsorption. For this system the model predicts that both the apparent dark Langmuir adsorption constant. K-L, and the number of adsorption sites, n(o), increase with decreasing pH, and are negligible above pH 6. At pH 2 the CD-MUSIC model predicts the fraction of singly co-ordinated sites occupied by the dye,f(AO7), is ca. 32% under the in situ monitoring experimental conditions used in this work to study the photocatalytic bleaching of AO7(-) under UV light illumination ([TiO2] = 20 mgdm(-3); [AO7(-)](total) = 4.86 x 10(-5) M). Although AO7(-) adsorption on P25 titania is insignificant above pH 6 and increases almost linearly and markedly below this pH, the measured initial rate of bleaching of AO7(-), photocatalysed by titania using UV appears to only increase modestly (

Hydrogen peroxide vapour indicator

A hydrogen peroxide vapour indicator is described comprising a triarylmethane dye, lissamine green (LG), dissolved in a polymer, polyvinyl alcohol (PVA). The indicator is green/blue in the absence of hydrogen peroxide vapour but is rapidly bleached in the presence of hydrogen peroxide vapour. The kinetics of LG bleaching appear approximately first order with respect [LG] and the concentration of H2O2, which, in turn, is proportional to the partial pressure of H2O2. However, the kinetics also appear to depend directly upon the reciprocal of the film thickness, implying some dependence upon the diffusion of the H2O2 vapour through the indicator film. Like most other H2O2 indicator films (such as starch-iodide paper), the LG/PVA indicator is not particularly selective and responds to most other volatile strong oxidising agents, such as ozone and chlorine. However, it is rapid in response (

A KINETIC-STUDY OF THE BLEACHING OF RHODAMINE-6G PHOTOSENSITIZED BY TITANIUM-DIOXIDE

The results of a kinetic study of the bleaching of the photostable dye rhodamine 6G by dissolved oxygen, photosensitized by TiO2, are reported. The observed variations in the initial rate of dye photobleaching as a function of the O2 percentage, temperature, incident light intensity and concentrations of rhodamine 6G and sacrificial electron donor are described and the results are rationalized using a proposed photochemical reaction scheme. The photosensitized bleaching of rhodamine 6G dye by TiO2 has a formal quantum yield of 2.65 X 10(-3), but the rate of complete photomineralization is about twofold slower. The overall activation energy for the semiconductor-sensitized dye photobleaching process is 15.0 +/- 1.5 kJ mol-1.