Elsa P. Amanatiadou

Development of new drug delivery system based on ordered mesoporous carbons: characterisation and cytocompatibility studies

Ordered mesoporous carbons that encapsulate the poorly soluble compounds ibuprofen and indomethacin were systematically studied by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC) and X-ray photon electron spectroscopy (XPS). The results showed marked differences in the release profiles of the two drug molecules in simulated gastric fluids. In vitro toxicity profiles appear to be compatible with potential therapeutic applications bringing them to the forefront as carriers of poorly water soluble drugs.

Synthesis, biological activity, and evaluation of the mode of action of novel antitubercular benzofurobenzopyrans substituted on A ring.

The 8-, 9-, 10-, and 11-halo, hydroxy, and methoxy derivatives of the antimycobacterial 3,3-dimethyl-3H-benzofuro[3,2-f][1]benzopyran were synthesized by condensation of the diazonium salts of 2-chloroanilines (13-17) with 1,4-benzoquinone (18), reduction of the intermediate phenylbenzoquinones 19-22 to dihydroxybiphenyls, cyclisation to halo-2-hydroxydibenzofurans 24-27, and construction of the pyran ring by thermal rearrangement of the corresponding dimethylpropargyl ethers 35-38. Palladium catalyzed nucleophilic aromatic substitution permitted conversion of the halo to the corresponding hydroxy derivatives which were methylated to methoxy-3,3-dimethyl-3H-benzofuro[3,2-f][1]benzopyran. All compounds substituted on the A ring were found more potent than the reference compound 1 against Mycobacterium bovis BCG and the virulent strain Mycobacterium tuberculosis H37Rv. The effect of the most active derivatives on mycolate synthesis was explored in order to confirm the preliminary hypothesis of an effect on mycobacterial cell wall biosynthesis. The linear 9-methoxy-2,2-dimethyl-2H-benzofuro[2,3-g][1]benzopyran (46) exhibiting a good antimycobacterial activity and devoid of cytotoxicity appeared to be the most promising compound.

Modified chitosan coated mesoporous strontium hydroxyapatite nanorods as drug carriers

Mesoporous strontium hydroxyapatite (SrHAp) nanorods (NRs) have been successfully synthesized using a simple and efficient chemical route, i.e. the hydrothermal method. Structural and morphological characterization of the as-synthesized SrHAp NRs have been performed by transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). TEM and HAADF-STEM measurements of the NRs reveal the coexistence of longer and shorter particles with the length ranging from 50 nm to 400 nm and a diameter of about 20-40 nm. Electron tomography measurements of the NRs allow us to better visualize the mesopores and their facets. Two model drugs, hydrophobic risperidone and hydrophilic pramipexole, were loaded into the SrHAp NRs. These nanorods were coated using a modified chitosan (CS) with poly(2-hydroxyethyl methacrylate) (PHEMA), in order to encapsulate the drug-loaded SrHAp nanoparticles and reduce the cytotoxicity of the loaded materials. The drug release from neat and encapsulated SrHAp NRs mainly depends on the drug hydrophilicity. Importantly, although neat SrHAp nanorods exhibit some cytotoxicity against Caco-2 cells, the Cs-g-PHEMA-SrHAp drug-loaded nanorods show an acceptable cytocompatibility.

GATA1 and PU.1 Bind to Ribosomal Protein Genes in Erythroid Cells: Implications for Ribosomopathies.

The clear connection between ribosome biogenesis dysfunction and specific hematopoiesis-related disorders prompted us to examine the role of critical lineage-specific transcription factors in the transcriptional regulation of ribosomal protein (RP) genes during terminal erythroid differentiation. By applying EMSA and ChIP methodologies in mouse erythroleukemia cells we show that GATA1 and PU.1 bind in vitro and in vivo the proximal promoter region of the RPS19 gene which is frequently mutated in Diamond-Blackfan Anemia. Moreover, ChIPseq data analysis also demonstrates that several RP genes are enriched as potential GATA1 and PU.1 gene targets in mouse and human erythroid cells, with GATA1 binding showing an association with higher ribosomal protein gene expression levels during terminal erythroid differentiation in human and mouse. Our results suggest that RP gene expression and hence balanced ribosome biosynthesis may be specifically and selectively regulated by lineage specific transcription factors during hematopoiesis, a finding which may be clinically relevant to ribosomopathies.

Comparison of different zeolite framework types as carriers for the oral delivery of the poorly soluble drug indomethacin

Microporous zeolites of distinct framework types, textural properties and crystal morphologies namely BEA, ZSM and NaX, have been employed as carriers to assess their effect on modulating the dissolution behavior of a BCS II model drug (indomethacin). Preparation of the loaded carriers via the incipient wetness method induced significant drug amorphization for the BEA and NaX samples, as well as high drug payloads. The stability of the amorphous drug content was retained after stressing test evaluation of the porous carriers. The dissolution profile of loaded indomethacin was evaluated in simulated gastric fluid (pH 1.2) and simulated intestinal fluids FaSSIF (fasted) and FeSSIF (fed state) conditions and was found to be dependent on the aluminosilicate ratio of the zeolites and the degree of crystalline drug content. The feasibility of the zeolitic particles as oral drug delivery systems was appraised with cytocompatibility and cellular toxicity studies in Caco-2 cultures in a time- and dose-dependent manner by means of the MTT assay and flow cytometry analysis, respectively. Intracellular accumulation of the zeolite particles was observed with no apparent cytotoxic effects at the lower concentrations tested, rendering such microporous zeolites pertinent candidates in oral drug delivery applications.

Pharmacogenomics and Nanotechnology Toward Advancing Personalized Medicine

The target of personalized medicine to achieve major benefits for all patients in terms of diagnosis and drug delivery can be facilitated by creating a sincere multidisciplinary information-based infrastructure in health care. To this end, nanotechnology, pharmacogenomics, and informatics can advance the utility of personalized medicine, enable clinical translation of genomic knowledge, empower healthcare environment, and finally improve clinical outcomes.

Possible interaction between B1 retrotransposon-containing sequences and βmajorglobin gene transcriptional activation during MEL cell erythroid differentiation

Repetitive sequences consist of >50% of mammalian genomic DNAs and among these SINEs (short interspersed nuclear elements), e.g. B1 elements, account for 8% of the mouse genome. In an effort to delineate the molecular mechanism(s) involved in the blockade of the in vitro differentiation program of MEL (murine erythroleukaemia) cells by treatment with methylation inhibitors, we detected a DNA region of 559 bp in chromosome 7 located downstream of the 3′‐end of the βmajor globin gene (designated B1‐559) with unique characteristics. We have fully characterized this B1‐559 region that includes a B1 element, several repeats of ATG initiation codons and consensus DNA‐binding sites for erythroid‐specific transcription factors NF‐E2 (nuclear factor‐erythroid‐derived 2), GATA‐1 and EKLF (erythroid Krüppel‐like factor). Fragments derived from B1‐559 incubated with nuclear extracts form protein complexes in both undifferentiated and differentiated MEL cells. Transient reporter‐gene experiments in MEL and human erythroleukaemia K‐562 cells with recombinant constructs containing B1‐559 fragments linked to HS‐2 (hypersensitive site‐2) sequences of human β‐globin gene LCR (locus control region) indicated potential cooperation upon erythropoiesis and globin gene expression. The possible interaction between the B1‐559 region and βmajor globin gene transcriptional activation upon execution of erythroid MEL cell differentiation programme is discussed.

Unveiling Transposable Elements Function to Enrich Knowledge for Human Physiology and Disease Pathogenesis

On September, 2012, data released by the ENCODE (The Encyclopedia of DNA Elements) project strongly support the notion that about 80 % of the human genome, including non-coding DNA sequences and repetitive DNA elements, serve some function. The latter, sheds light to one of the most provocative questions in biology by providing new knowledge to the functional roles of transposable elements (TEs) in the potential modulation of the genome transcriptional units organized throughout the genome either as coding (genes) or as non-coding DNA regions. Interestingly, some of these data propose that specific inter-individual genetic variability patterns are also located within the “junk DNA” structure. This direction may obviously lead toward the exploitation of genomic knowledge implicating the bulk of human genome structure and function in therapeutics and drug development. This chapter focuses on the function of TEs in physiology and human pathophysiology. In parallel, some recently data of our laboratory on the potential involvement of mouse B1 short repetitive elements in the execution of murine erythroleukemia (MEL) cell erythroid maturation program and the regulation of globin gene expression will be also discussed.