Katia Vandenbulcke

Evaluation of the Antibacterial Activity and Toxicity of 2 New Hydrogels: A Pilot Study

Wound bed preparation remains a very important issue in wound healing. To promote the production of granulation tissue, it is necessary to remove necrotic tissue and to control infection. Necrotic tissue may be removed using a hydrogel preparation. Flaminal ® and Flaminal ® Hydro (Flen Pharma, Belgium) are 2 new hydroactive colloid gel dressings with state antibacterial properties. These properties are attributed to an enzymatic complex in their formulation. In the study described in this report, the antibacterial effects of Flaminal and Flaminal Hydro were confirmed in an in vitro as well as an in vivo setting. It was also demonstrated that Flaminal and Flaminal Hydro are not toxic to keratinocytes in vitro using an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] test.

mBAND analysis of chromosome aberrations in lymphocytes exposed in vitro to α-particles and γ-rays

Purpose: To investigate the profiles of chromosome damage induced in vitro by exposure to α-particles and γ-rays. Materials and methods: Human peripheral blood lymphocytes were exposed to three dose regimes: α-particle doses of 0.2 and 0.5 Gy and a γ-ray dose of 1.5 Gy. After culturing for 47 hours, chromosome aberrations involving the number 5 chromosomes were identified using a multi-coloured banding (mBAND) technique. Results: Analysis of the frequencies of chromosome 5 breaks within aberrant cells and within aberrant number 5 chromosomes demonstrated that α-particle irradiation is more likely to result in multiple breaks in a chromosome than γ-irradiation. Additionally, overdispersion was observed for all doses for the distribution of breaks amongst all cells analysed and breaks amongst total number 5 chromosomes, with this being greatest for the 0.2 Gy α-particle dose. The ratio of interchanges to intrachanges (F ratio) was 1.4 and 2.4 for 0.2 and 0.5 Gy α-particles respectively and 5.5 for 1.5 Gy γ-rays. Evaluation of simple versus complex exchanges indicated ratios of 1.9 and 2.7 for 0.2 and 0.5 Gy α-particles respectively and 10.6 for 1.5 Gy γ-rays. The majority of the intrachanges involving chromosomes 5 induced by α-particle radiation were associated with more complex exchanges. Conclusions: This study has confirmed that exchanges induced by exposure to high linear energy transfer (LET) α-particle radiation comprise a greater proportion of intrachanges than those induced by exposure to low LET γ-rays. However, since the majority of these are associated with complex rearrangements and likely to be non-transmissible, this limits their applicability as a marker of past in vivo exposure.

The Characterization and Transmissibility of Chromosome Aberrations Induced in Peripheral Blood Lymphocytes by In Vitro α-Particle Radiation

Abstract Tawn, E. J., Whitehouse, C. A., De Ruyck, K., Hodgson, L., Vandenbulcke, K. and Thierens, H. The Characterization and Transmissibility of Chromosome Aberrations Induced in Peripheral Blood Lymphocytes by In Vitro α-Particle Radiation. Radiat. Res. 168, 666–674 (2007). Peripheral blood lymphocytes were irradiated in vitro with 213Bi α particles at doses of 0, 10, 20, 50, 100, 200 and 500 mGy. Chromosome analysis was performed on 47-h cultures using single-color fluorescence in situ hybridization (FISH) to paint chromosomes 1, 3 and 5. The whole genome was analyzed for unstable aberrations to derive aberration frequencies and determine cell stability. The dose response for dicentrics was 33.60 ± 0.47 × 10−2 per Gy. A more detailed analysis revealed that the majority of aberrations scored as dicentrics were part of complex/multiple aberrations, with the proportion of cells containing complexes increasing with dose. Cells containing aberrations involving painted chromosomes (FISH aberrations) were further classified according to cell stability and complexity. The majority of cells with FISH aberrations were unstable. The proportion of aberrant FISH cells with complex/multiple aberrations ranged from 56% at 10 mGy to 89% at 500 mGy. A linear dose response for genomic frequencies of translocations in stable cells fitted the data from 0 to 200 mGy with a dose response of 7.90 ± 0.98 × 10−2 per Gy, thus indicating that they are likely to be observed in peripheral blood lymphocytes from individuals with past or chronic exposure to high-LET radiation. Comparisons with the dose response for low-LET radiation suggest an RBE of 13.6 for dicentrics in all cells and 3.2 for translocations in stable cells. Since stochastic effects of radiation are attributable to genetic changes in viable cells, translocations in stable cells may be a better measure when considering the comparative risks of different qualities of radiation.

Importance of receptor density- in alpha radioimmunotherapy in B cell malignancies: an in-vitro study

BackgroundExternal beam radiotherapy and beta radioimmunotherapy (RIT) are effective treatments for lymphoid malignancies. The development of RIT with alpha emitters is attractive because of the high linear energy transfer (LET) and short path length, allowing higher tumour cell kill and lower toxicity to healthy tissues. AimTo assess the binding of rituximab to samples of B cell chronic lymphocytic leukaemia (B-CLL) and splenic lymphoma with villous lymphocytes (SLVL), and to evaluate the induction of apoptosis by conventional therapies as well as with 213Bi conjugated to rituximab. Method213Bi was eluted from a 225Ac generator and conjugated to CD20 antibody (rituximab) with CHX-A″-DTPA as chelator. Binding assays with 213Bi-rituximab were correlated to antibody binding capacity obtained by flow cytometry. Apoptosis was scored by flow cytometric analyses of the cells stained with annexin V–FITC and 7-amino-actinomycin D. ResultsBinding of 213Bi-rituximab was significantly lower for B-CLL compared to SLVL samples (12±3 and 42±10 213Bi atoms per cell, respectively, at 370 kBq·ml−1). The induction of apoptosis did not differ significantly between the two groups (B-CLL and SLVL) after external gamma irradiation or treatment with methylprednisolone and fludarabine (17±12% and 18±11%; 23±14% and 21±12%; 9±9% and 11±8%, respectively; all results expressed as percentages of all cells). Rituximab conjugated or not to 213Bi induced significantly more apoptosis in SLVL (42±19% and 42±17%) compared to B-CLL samples (27±12% and 6±8%). ConclusionBinding assays confirm that SLVL samples present more CD20 antigens compared to B-CLL samples. Conventional therapies such as fludarabine, methylprednisolone or external gamma irradiation induce similar responses in the two populations but SLVL samples present higher sensitivity towards 213Bi-rituximab. These data are in favour of alpha-RIT in SLVL patients.