Dana Iordachescu

Comparative Effects of Boric Acid and Calcium Fructoborate on Breast Cancer Cells

Recent studies suggested that boron has a chemo-preventive role in prostate cancer. In the present report, we investigated the effects of calcium fructoborate (CF) and boric acid (BA) on activation of the apoptotic pathway in MDA-MB-231 human breast cancer cells. Exposure to BA and CF inhibited the proliferation of breast cancer cells in a dose-dependent manner. Treatment with CF but not BA resulted in a decrease in p53 and bcl-2 protein levels. Furthermore, after the treatment with CF, augmentation of pro-caspase-3 protein expression, cytosolic cytochrome c level, and caspase-3 activity were observed, indicating apoptotic cell death induction. This was also demonstrated by terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick-end-labeling assay. In conclusion, our data provide arguments to the fact that both BA and CF inhibited the growth of breast cancer cells, while only CF induced apoptosis. Additional studies will be needed to identify the underlying mechanism responsible for the observed cellular responses to these compounds and to determine if BA and CF may be further evaluated as chemotherapeutic agents for human cancer.

In vitro evaluation of the antioxidant activity of calcium fructoborate

Although increasing evidence shows the nutritional benefits of calcium fructoborate (CF) on animals and humans, its action mechanism has not been clearly identified. The present study aims to investigate the possible antioxidant function of CF. Based on its efficiency in skin wound healing, the authors tested whether CF possesses antioxidant properties on human keratinocytes cultures, in a complete serum-free medium (KMK-2; Sigma). The cells treated with CF (0–450 nmol/culture medium) were exposed to exogenous 100 μmol of hydrogen peroxide to mimic the oxidative stress. The changes in general cell oxidant production evaluated with dihydrorhodamine-123 showed that the intracellular reactive oxygen species (ROS) were markedly reduced by preincubation with CF. The maximum antioxidant activity was notice at 90 nmol CF. To assess the reactivity of CF on ROS, we analyzed its ability to inhibit the superoxide-dependent auto-oxidation of pyrogallol. The CF inhibited the pyrogallol auto-oxidation depending on time and concentration, which suggests its possible role as a superoxide radical scavenger. Taken together, our results indicate that CF has antioxidant activity, which could have clinical significance in protecting cells from oxidant-induced injury. A hypothetic mechanism for the antioxidant activity of CF is proposed.

In vitro biocompatibility and corrosion resistance of a new implant titanium base alloy

One objective of this work was to study the corrosion resistance of the new implant Ti–10Zr–5Ta–5Nb alloy in physiological fluids of different pH values, simulating the extreme functional conditions. Another objective was in vitro biocompatibility evaluation of the new alloy using human fetal osteoblast cell line hFOB 1.19. Cytocompatibility was assessed by determination of possible material cytotoxic effects, cell morphology and cell adhesion. The thermo-mechanical processing of the new implant alloy consisted in plastic deformation (almost 90%) performed by hot rolling accompanied by an initial and final heat treatment. The new Ti–10Zr–5Ta–5Nb alloy presented self-passivation, with a large passive potential range and low passive current densities, namely, a very good anticorrosive resistance in Ringer solution of acid, neutral and alkaline pH values. Cell viability was not affected by the alloy substrate presence and a very good compatibility was noticed.

In Vitro Effects of Calcium Fructoborate upon Production of Inflammatory Mediators by LPS-stimulated RAW 264.7 Macrophages

The present study is supported by our previous findings suggesting that calcium fructoborate (CF) has anti-inflammatory and antioxidant properties. Thus, we investigated the effects of CF on a model for studying inflammatory disorders in vitro represented by lipopolysaccharide (LPS)-stimulated murine macrophage RAW 264.7 cells. This investigation was performed by analyzing the levels of some mediators released during the inflammatory process: cytokines such as tumor necrosis factor-α (TNF-α), interleukins IL-1β and IL-6 as well as cyclooxygenase-2 (COX-2), the main enzyme responsible for endotoxin/LPS-induced prostaglandin synthesis by macrophages. We also measured production of nitric oxide (NO) that plays an important role in the cytotoxicity activity of macrophages towards microbial pathogens. After CF treatment of LPS-stimulated macrophages we found an up-regulation of TNF-α protein level in culture medium, no significant changes in the level of COX-2 protein expression and a decrease in NO production as well as in IL-1β and IL-6 release. Collectively, this series of experiments indicate that CF affect macrophage production of inflammatory mediators. However, further research is required in order to establish whether CF treatment can be beneficial in suppression of pro-inflammatory cytokine production and against progression of endotoxin-related diseases.

Phospholipase A2 modulates respiratory burst developed by neutrophils in patients with rheumatoid arthritis.

Activated by bacterial peptides, phorbol esters, calcium ionophores and other agonists, neutrophils (PMNs) release the proinflammatory mediator, arachidonic acid (AA) via the intervention of phospholipase A2 (PLA2). AA may play an essential role in activation of NADPH‐oxidase, which is involved in the generation of superoxide anion by neutrophils. The present study is focused on the involvement of PLA2 in the respiratory burst developed by PMNs isolated from patients with rheumatoid arthritis (RA). PLA2 exists in very high levels in diseases such as rheumatoid arthritis and may cause acute inflammatory and proliferative changes in synovial structures. The respiratory burst was evaluated as superoxide anion release, using an amplified chemiluminiscence method. The assays were performed using PMNs untreated or treated with different doses of stimulatory reagents (phorbol 12‐myristate‐13‐acetate (PMA), calcium ionophore (A23187)). Our data suggested that PMA stimulated the production of superoxid anion in a dose‐response manner, as compared with A23187, which did not induce a significant release of superoxide anion in PMNs‐RA. The exogenous addition of AA significantly amplified the superoxide anion release by PMNs‐RA stimulated with PMA and to a lesser extent, by PMNs stimulated with A23187. AA has also reversed the inhibitory effect of arachidonyl‐trifluorometylketone and E‐6‐(bromomethylene)tetrahydro‐3‐(1‐naph‐thalenyl)2H‐pyran‐2‐one (BEL) on the superoxide anion release by PMNs‐RA. In conclusion, the differential responses to these two agents suggested that different isoforms of PLA2 were activated by A23187 or PMA, and support the idea that activation of these different PLA2 served distinct functions of PMNs. Therefore, the inhibition of PLA2 enzymes might be of great importance in the immunotherapy of rheumatoid arthritis.

Osteoblast cell behavior on the new beta-type Ti-25Ta-25Nb alloy.

Among metallic materials used as bone substitutes, β titanium alloys gain an increasing importance because of their low modulus, high corrosion resistance and good biocompatibility. In this work, an investigation of the in vitro cytocompatibility of a recently new developed β-type Ti-25Ta-25Nb alloy was carried out by evaluating the behavior of human osteoblasts. The metallic Ti-6Al-4V biomaterial, which is one of representative α+β type titanium alloys for biomedical applications, and Tissue Culture Polystyrene (TCPS), were also investigated as reference Ti-based material and control substrate, respectively. Both metallic surfaces were analyzed by X-ray diffraction, atomic force microscopy and X-ray photoelectron spectroscopy. The cellular response was quantified by assessments of viability, cell attachment and spreading, cell morphology, production and extracellular organization of fibronectin and cell proliferation. Polished surfaces from both materials having an equiaxed grain microstructure and nanometre scale surface roughness elicited an essentially identical osteoblast response in terms of all analyzed cellular parameters. Thus, on both surfaces the cells displayed high survival rates, good cell adhesion and spreading, a dense and randomly dispersed fibronectin matrix and increasing cell proliferation rates over the incubation time. Furhermore, the enhanced biological performance of Ti-25Ta-25Nb was highly supported by the results obtained in comparison with TCPS. These findings, together with previously shown superelastic behavior, low Youngs modulus and high corrosion resistance, recommend Ti-25Ta-25Nb as good candidate for applications in bone implantology.

Effects of synovial fluid on the respiratory burst of granulocytes in rheumatoid arthritis

Neutrophil infiltration in the synovia is an important feature of the local inflammatory process associated with rheumatoid arthritis. The present study is focused on the effects exerted in vitro by the synovial fluid versus serum on the respiratory burst of granulocytes isolated either from blood or synovial fluid of rheumatoid arthritis patients. The respiratory burst was evaluated as superoxide anion release, by lucigenin‐amplified chemiluminescence. Our data show that the respiratory burst of granulocytes isolated from rheumatoid arthritis patients might trigger a significant oxidative stress both in periphery and the inflamed joint. These cells show no pathological pattern when activated in vitro by the chemotactic peptide fMLP, heterologous synovial fluid or serum. Acellular synovial fluid amplifies the superoxide anion release induced by fMLP more than the corresponding serum, indicating that a bacterian infection in the joint might enhance the oxidative damage in the inflamed synovium.

The influence of sodium metavanadate on the process of diabetogenesis in BB rats

Vanadium has been shown to be beneficial in the oral treatment of animal models of type 1 and type 2 diabetes. The aim of the study was to evaluate the short‐term effects of sodium metavanadate in prediabetic BB‐DP rats. To do this, 96 rats were divided into 4 equal groups. Groups VI, V2, V3 were treated with sodium metavanadate (0.1, 0.2 and 0.3 mg/ml respectively) and sodium chloride (0.5 mg/ml) in drinking water for 7 days. Group C received only sodium chloride (0.5 mg/ml). Blood glucose (BG), glycosuria, ketonuria, body weight and insulinemia were determined. The age of onset of diabetes was significantly higher for groups V2, V3 compared to group C, (p < 0.05) and depends on the metavanadate concentration (V3 vs. V1, p=0.006). The incidence of diabetes was lower in the rats treated with metavanadate than in the control group, but this difference was not statistically significant. In diabetic rats, the BG at the onset was higher in group C than in groups V, p < 0.05. Insulinemia, at the onset of the treatment as well as immediately after its cessation showed a drop in the treatment groups, proportionally to the dosage of vanadium, but later increased slowly and continuously until the end of the experiment. In conclusion, metavanadate delays the development of diabetes in BB‐DP rats, but does not prevent its onset. A milder form of diabetes occurs in diabetic rats treated with metavanadate. The effects depend on the metavanadate concentration and 0.2 mg/ml is preferable.

Surface Analysis and Cell Biology Technique in Understanding Degradation of Natural Temporary Teeth Collected from an Area with High Pollution

The aim of this paper is to correlate surface features of degraded temporary teeth from area with high pollution with the cell adhesion and proliferation. Viability of gingival fibroblast (HGF-1, CRL-2014, American Type Culture Collection) was evaluated with a MTT (3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolium bromide ) test and the values are discussed for the most degraded temporary teeth in correlation with the change in surface morphology and hydrophilic/hydrophobic balance, taking into account that cell adhesion is related to a more hydrophilic character.

Plasma membrane potential interferes with the respiratory burst of peripheral granulocytes

Membrane potential is involved in the regulation of several immune functions developed by granulocytes. The Na+/K+ gradient across the plasma membrane, mainly generated by the Na+/K+ pump, plays a key role in the maintenance of membrane potential. This study is focused on the correlation between plasma membrane potential and the in vitro receptor ‐ triggered respiratory burst of normal human peripheral granulocytes. The respiratory burst was measured as superoxide anion release by the cytochrome c reduction test and plasma membrane potential was modulated by experimental changes of the extracellular potassium concentration. Results show a differentiated cellular response, depending on the in vivo activation state and on the signals received in vitro by granulocytes via CR3 or FcγR. Alteration of the membrane potassium gradient modulates the respiratory burst of unstimulated and CR3‐activated cells, whilst it does not seem to significantly interfere with the signals delivered by FcγR.