In vitro toxicity evaluation of Ti(4+)-stabilized γ-Bi2O3 sillenites.

We report results regarding the in vitro toxicology of γ-Bi2O3 represented by its isomorphous phase Bi12TiO20 (γ-BTO). The γ-BTO microparticles were synthesized by two methods: coprecipitation from a bismuth nitrate-tetrabutyl titanate solution and solid state reaction of Bi2O3 and TiO2 oxides. The structural and morphological characteristics of the obtained materials were determined using X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission (TEM) and scanning (SEM) electron microscopy. The elemental composition was investigated using energy dispersive spectrometry (EDS). The cytotoxicity and oxidative/nitrosative stress (intracellular reactive oxygen species (ROS) and nitric oxide (NO) release) induced by the studied microparticles in HepG2, SH-SY5Y and 3T3-L1 cell cultures were determined using the MTT, DCF-DA (2',7'-dichlorfluorescein-diacetate) and Griess methods respectively. Depending on the cell type and γ-BTO concentration, results showed only weak cytotoxic effects after 24h of γ-BTO exposure and cell proliferation effects for longer treatment times. Only reduced NO release increases (corresponding to high γ-BTO concentrations) were detected in case of SH-SY5Y and 3T3-L1 cells. The intracellular ROS production (higher for HepG2 cells) appeared inversely proportional to the γ-BTO concentration. The obtained results indicated a promising in vitro biocompatibility of γ-BTO and encourage further studies regarding its potential for biomedical applications.

Structural properties of silver doped hydroxyapatite and their biocompatibility.

The aim of this study was to obtain a novel hydroxyapatite-based material with high biocompatibility. The structural properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS). The X-ray diffraction studies revealed the characteristic peaks of hydroxyapatite in each sample. Other phases or impurities were not observed. The scanning electron microscopy observations suggest that the doping components have no influence on the surface morphology of the samples, which reveals a homogeneous aspect of the synthesized particles for all samples. The presence of calcium (Ca), phosphor (P), oxygen (O) and silver (Ag) in the Ag:HAp is confirmed by energy dispersive X-ray (EDAX) and X-ray Photoelectron Spectroscopy analyses. Nanocrystalline silver doped HAp stimulated viability and potentiated the activation of murine macrophages.

The noncellular reduction of MTT tetrazolium salt by TiO2 nanoparticles and its implications for cytotoxicity assays.

We report results of noncellular tests, revealing the occurrence of photocatalytic interactions between titanium dioxide (TiO2, titania) nanoparticles and the MTT [3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide] cytotoxicity indicator. These interactions induce the reduction of MTT and formation of purple formazan under biologically relevant conditions. Classical MTT assays have been performed to evaluate the production of formazan in DMEM-F12 and RPMI-1640 cell culture media (containing 10% fetal bovine serum-FBS) treated with Degussa-P25 TiO2 nanoparticles, in the absence of cells. The colorimetric determinations revealed the noncellular MTT to formazan transformation induced by TiO2 nanoparticles, under conditions commonly used for in vitro cytotoxicity testing of nanomaterials. The formazan precipitation was found to be proportional to the TiO2 concentration, being enhanced under laboratory daylight exposure. The photocatalytic nature of the studied effect was assessed under UV irradiation at 365nm. The biological significance of the reported reaction was established with respect to cellular reference experiments performed on V79-4, HeLa and B16 cell lines. The results show false viability increases with up to 14% (for TiO2 concentrations generally higher than 50µg/ml), induced by the TiO2-MTT reaction. This type of artifacts may lead to underestimated toxicity or false proliferation results.

Etiopathogenesis and prognostic implications of autoimmune hemolytic anemia association with chronic lymphocytic leukemia B.

Biological complexity of mechanisms of autoimmune hemolytic anemia (AHAI) in chronic lymphocytic leukemia B (CLL) and the relation cause / effect between these two diseases has been extensively researched, but currently is still far from being completely understood. It is known that the immune system has an important role in the pathogenesis of autoimmune diseases but also in the chronic lymphoproliferative malignancies. In this process of autoimmunity associated with immunodeficiency, the CLL neoplastic cells, the non-malignant B cells, T cells, and the cellular microenvironment cells are also involved. CLL pathological lymphocytes change peripheral immune tolerance acting as an antigen presenting cells and / or cells expressing inhibitory cytokines. The two subpopulations of T cells also have an important place: self-reactive T helper cells (TH) and regulatory T cells (Treg). The Fas / Fas ligand - cell death mechanism has a significant role both in maintaining cellular homeostasis, malignant hematopoietic cell expansion and the development of autoimmune disorders, including AIHA. The article reviews the etiopathogenesis of the autoimmune mechanism of AIHA in CLL, and its impact on the prognosis and long - term survival of patients with chronic lymphocytic leukemia B.

Prognosis Factors in Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia is still one of the most common hematologic malignancies. Finding a curative solution is the objective of numerous followed cases and clinical trials. Diagnosis is based on the interlocking of classic elements and newly identified prognostic factors but time to first treatment is still an open issue. CD38, ZAP 70, IgHV gene mutational status and cytogenetic changes are proven negatively influence the evolution of chronic lymphocytic leukemia. Whether through aggressive rapid evolution or by the difficulty of obtaining a complete remission or risk of early relapse, CLL is still important. Adapted to these prognostic factors, combined therapeutic regimens have proved to be effective in achieving a durable complete remission, new agents, with encouraging partial results, being studied. Requiring initial screening, for comparative purposes, a current and growing importance has minimal residual disease; its absence at the end of treatment represents a strong positive prognostic factor.

Importance of assessing cytogenetic and molecular risk factors in acute myeloid leukemia therapy.

Acute myeloid leukemia (AML) is a heterogeneous disease in clinical presentation, outcome and therapeutic response. Cytogenetic and molecular characteristics are important prognostic indicators allowing the identification of distinct subtypes of AML, prognostic stratification and risk-adapted treatment. We present our experience during 5 years, in which we treated 245 patients with AML, of which we could genetically characterize 48 cases (26 females, 22 males) with a median age of 52 years. Cytogenetic analysis was performed by GTG banding on cultures of marrow cells treated with colcemid. Molecular analysis used RT-PCR performed on ABI 9700 platform in order to identify the following fusion genes: E2A-PBX1, TEL-AML1, AML1-ETO, PML-RARα, MLL-AF4, CBFC-MYH11, BCR-ABL, SIL-TAL, and MLL-AF9as well as mutations in Flt3, NPM1, WT1 genes. Fourteen patients were older than 60 years. In 12 we performed cytogenetic analysis showing 5 cases with complex karyotype, 2 normal karyotypes, 1 case of del(21), del (9), 11q- and t(3;15) respectively as well as 2 unevaluable karyotypes. These anomalies were associated with a high incidence of secondary AMLs (10/14) and with a low remission (CR) rate (5/14). Out of the 35 patients younger than 60 years, 25 were evaluated by cytogenetics showing a high incidence of favorable cytogenetic changes: 6 anomalies of chromosome 16 (5 inv (16) and 1 t (16; 16)), 3 t (15; 17), 3 cases of t (8; 21) of which 2 with additional abnormalities, 7 normal karyotypes and 1 case of 7q-, -y,-3 and respectively -8 associated with +18. In 25 cases molecular analysis was performed showing alterations in 21 patients: 6 cases with AML/ETO, 3 PML/RAR, 7 Flt3 mutations (2 associated with NPM1 mutation) as well as 1 case of isolated mutation of NPM1 and respectively WT1. CR rate was of 28/35. All cases with t (15; 17) and PML/RAR as well all cases with t (8; 21) and/or AML/ETO achieved CR. Out of the 7 cases with Flt3 mutations only 4 achieved CR including the 2 cases with associated NPM1 mutations. In our experience, genetic characteristics correlate with other prognostic markers such as age and secondary leukemia; "favorable" genetic anomalies were associated with a high CR rate; association of t (8; 21) with additional abnormalities did not influence CR rate.