Elisângela de Paula Silveira-Lacerda

Real-time infrared thermography detection of magnetic nanoparticle hyperthermia in a murine model under a non-uniform field configuration.

Abstract Purpose: Magnetic nanoparticle hyperthermia consists of an increase of the temperature of magnetic nanoparticles (heat centres) due to the interaction of their magnetic moments with an alternating magnetic field. In vivo experiments using this method usually use a few fibre-optic thermometers inserted in the animal body to monitor the heat deposition. As a consequence, only a few points of the 3D temperature distribution can be monitored by this invasive procedure. It is the purpose of this work to show that non-invasive infrared thermography is able to detect, in real time, magnetic nanoparticle hyperthermia as well as monitor the harmful field-induced eddy currents in a murine model with a subcutaneous tumour. This surface temperature measurement method has the potential to give information about the intratumoral temperature. Materials and methods: The non-invasive magnetic hyperthermia experiments were performed at 300 kHz in non-uniform field configuration conditions in healthy mice and murine tumour induced by sarcoma S180. A soft ferrite-based biocompatible magnetic colloid consisting of manganese–ferrite nanoparticles surface-coated with citric acid were used in the experiments, which were extensively characterised by several techniques (transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM)). The amplitude of the alternating magnetic fields was obtained from measurements using an AC field probe at similar experimental conditions. The temperature measurements were obtained from an infrared thermal camera and a fibre-optic thermometer. Results: Three-minute magnetic hyperthermia experiments revealed surface temperature increase as high as 11 °K in healthy and (5 °K in S180 tumour) animals when injecting subcutaneously 2 mg of magnetic nanoparticles (86 μL of magnetic fluid), in contrast to around 1.5 °K (for healthy) and 2.5 °K (for cancerous) animals in experiments without the colloid due to field-induced eddy currents at the animal surface. The thermographic temperature measurements were found to agree with the fibre-optic measurements within a 5% error, and were associated with the skin emissivity angle of dependence in the experimental set-up. On the other hand, a 30-min magnetic nanoparticle hyperthermia revealed surface temperature increases as high as 12 °K close to the injection site, while above 2–3 cm no significant temperature increase was observed. Curiously, the intratumoral temperature, monitored by a fibre-optic sensor, was found to be almost the same as the thermal camera surface temperature after achieving an equilibrium temperature regime. From the observed isotherms at the animal surface, using an analytical heat conduction model, taking into account surface conductance, we estimate a magnetic heating power of 0.45 W/cm3 and a specific loss power (SLP) of 85 W/g for a field of the order of only 10 kA/m at the injection site region. Conclusions: The results indicate that infrared thermography may be a promising tool for both early cancer detection and for hyperthermia treatment (at least for subcutaneous tumours), since the method permits access to information about the intratumoral temperature during a real-time magnetic hyperthermia as well as to estimate the in vivo nanoparticles SLP.

Atypical fluoroquinolone gold(III) chelates as potential anticancer agents: Relevance of DNA and protein interactions for their mechanism of action

Quinolones are known for their antimicrobial and antitumor activities. Gold(III) compounds constitute an emerging class of biologically active substances, of special interest as potential anticancer agents. In this work three gold(III) complexes of the fluoroquinolones antimicrobial agents norfloxacin (NOR), levofloxacin (LEVO) and sparfloxacin (SPAR) were prepared and characterized with physicochemical and spectroscopic techniques. In these complexes, NOR, LEVO and SPAR act as bidentate neutral ligands bound to gold(III) through the nitrogen atoms of the piperazine ring, which is an unusual mode of coordination for this class of compounds. Two chloride ions occupy the remaining coordination sites. The cytotoxic activity of the fluoroquinolones and their gold(III) complexes was tested against the A20 (murine lymphoma), B16-F10 (murine melanoma) and K562 (human myeloid leukemia) tumor cell lines as well as the L919 (murine lung fibroblasts) and MCR-5 (human lung fibroblasts) normal cells lines. All complexes were more active than their corresponding free ligands. Complex [AuCl(2)(LEVO)]Cl was selected for DNA fragmentation and cell cycle analysis. Spectroscopic titration with calf-thymus DNA (CT DNA) showed that the complexes can bind weakly to CT DNA, probably by an external contact (electrostatic or groove binding). The complexes exhibit good binding propensity to bovine serum albumin (BSA) having relatively high binding constant values.

Cytoxicity and Apoptotic Mechanism of Ruthenium(II) Amino Acid Complexes in Sarcoma-180 Tumor Cells

Over the past several decades, much attention has been focused on ruthenium complexes in antitumor therapy. Ruthenium is a transition metal that possesses several advantages for rational antitumor drug design and biological applications. In the present study, five ruthenium complexes containing amino acids were studied in vitro to determine their biological activity against sarcoma-180 tumor cells. The cytotoxicity of the complexes was evaluated by an MTT assay, and their mechanism of action was investigated. The results demonstrated that the five complexes inhibited the growth of the S180 tumor cell line, with IC50 values ranging from 22.53 µM to 50.18 µM, and showed low cytotoxicity against normal L929 fibroblast cells. Flow cytometric analysis revealed that the [Ru(gly)(bipy)(dppb)]PF6 complex (2) inhibited the growth of the tumor cells by inducing apoptosis, as evidenced by an increased number of Annexin V-positive cells and G0/G1 phase cell cycle arrest. Further investigation showed that complex 2 caused a loss of mitochondrial membrane potential; activated caspases 3, caspase-8, and caspase-9 and caused a change in the mRNA expression levels of caspase 3, caspase-9 as well as the bax genes. The levels of the pro-apoptotic Bcl-2 family protein Bak were increased. Thus, we demonstrated that ruthenium amino acid complexes are promising drugs against S180 tumor cells, and we recommend further investigations of their role as chemotherapeutic agents for sarcomas.

Antitumor effects of snake venom chemically modified Lys49 phospholipase A2-like BthTX-I and a synthetic peptide derived from its C-terminal region.

The present work evaluates both in vitro and in vivo antitumor activity of BPB-modified BthTX-I and its cationic synthetic peptide derived from the 115-129 C-terminal region. BPB-BthTX-I presented cytotoxicity of 10-40% on different tumor cell lines, which were also susceptible to the lytic action of the synthetic peptide. Injection of the modified protein or the peptide in mice, 5 days after transplantation of S180 tumor cells, reduced 30 and 36% of the tumor size on day 14th and 76 and 79% on day 60th, respectively, when compared to the untreated control group. Thus, these antitumor properties might be of interest in the development of therapeutic strategies against cancer.

Molecular Detection of Adenoviruses in Lakes and Rivers of Goiânia, Goiás, Brazil

Adenoviruses are a highly important public health issue, since they are among the most persistent and ubiquitous viruses present in water and associated with a variety of clinical manifestations. The aim of this study was to use molecular techniques for the detection of adenovirus in public and recreational water supplies in Goiânia, Brazil. From December 2007 to November 2008, 54 water samples were collected in 5 different sites in 2 lakes and 2 rivers of the city. The samples were filtered in a positively charged nylon membrane, and the DNA was extracted using the phenol–chloroform–isoamyl alcohol method. Semi-nested PCR was used to detect adenovirus DNA, and sequence analysis of the semi-nested PCR products was performed to identify the recovered viruses. Adenovirus DNA was detected in 43% (24 of 54) of samples collected. Considering all examined sites, MP1 presented the highest occurrence of adenovirus (6 positive from 10 collected samples), followed by MP2 (3 positive from 6 collected samples), JL (10 positive from 21 collected samples), VB (3 positive from 9 collected samples), and BB (2 positive from 8 collected samples), respectively. The methodology employed proved to be feasible, fast, low-cost, and suitable to be used as screening approach on adenovirus detection in water for public sanitation companies.

Proteomic profile response of Paracoccidioides lutzii to the antifungal argentilactone.

The dimorphic fungi Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM), a mycosis of high incidence in Brazil. The toxicity of drug treatment and the emergence of resistant organisms have led to research for new candidates for drugs. In this study, we demonstrate that the natural product argentilactone was not cytotoxic or genotoxic to MRC5 cells at the IC50 concentration to the fungus. We also verified the proteomic profile of Paracoccidioides lutzii after incubation with argentilactone using a label free quantitative proteome nanoUPLC-MSE. The results of this study indicated that the fungus has a global metabolic adaptation in the presence of argentilactone. Enzymes of important pathways, such as glycolysis, the Krebs cycle and the glyoxylate cycle, were repressed, which drove the metabolism to the methylcytrate cycle and beta-oxidation. Proteins involved in cell rescue, defense and stress response were induced. In this study, alternative metabolic pathways adopted by the fungi were elucidated, helping to elucidate the course of action of the compound studied.

The ruthenium complex cis-(dichloro)tetrammineruthenium(III) chloride induces apoptosis and damages DNA in murine sarcoma 180 cells.

Ruthenium(III) complexes are increasingly attracting the interest of researchers due to their promising pharmacological properties. Recently, we reported that the cis-(dichloro)tetrammineruthenium(III) chloride compound has cytotoxic effects on murine sarcoma 180 (S-180) cells. In an effort to understand the mechanism responsible for their cytotoxicity, study we investigated the genotoxicity, cell cycle distribution and induction of apoptosis caused by cis-(dichloro)tetrammineruthenium(III) chloride in S-180 tumour cells. cis-(dichloro)tetrammineruthenium(III) chloride treatment induced significant DNA damage in S-180 cells, as detected by the alkaline comet assay. In the cell cycle analysis, cis-(dichloro)tetrammineruthenium(III) chloride caused an increase in the number of cells in G1 phase, accompanied by a decrease in the S and G2 phases after 24 h of treatment. In contrast, the cell cycle distribution of S-180 cells treated with cis-(dichloro)tetrammineruthenium(III) chloride for 48 h showed a concentration-dependent increase in the sub-G1 phase (indicating apoptosis), with a corresponding decrease in cells in the G1, S and G2 phases. In addition, cis-(dichloro)tetrammineruthenium(III) chloride treatment induced apoptosis in a time-dependent manner, as observed by the increased numbers of annexin V-positive cells. Taken together, these findings strongly demonstrate that DNA damage, cell cycle changes and apoptosis may correlate with the cytotoxic effects of cis-(dichloro)tetrammineruthenium(III) chloride on S-180 cells.

Precise determination of the heat delivery during in vivo magnetic nanoparticle hyperthermia with infrared thermography

Non-invasive and real-time monitoring of the heat delivery during magnetic nanoparticle hyperthermia (MNH) is of fundamental importance to predict clinical outcomes for cancer treatment. Infrared thermography (IRT) can determine the surface temperature due to three-dimensional heat delivery inside a subcutaneous tumor, an argument that is supported by numerical simulations. However, for precise temperature determination, it is of crucial relevance to use a correct experimental configuration. This work reports an MNH study using a sarcoma 180 murine tumor containing 3.9 mg of intratumorally injected manganese-ferrite nanoparticles. MNH was performed at low field amplitude and non-uniform field configuration. Five 30 min in vivo magnetic hyperthermia experiments were performed, monitoring the surface temperature with a fiber optical sensor and thermal camera at distinct angles with respect to the animals surface. The results indicate that temperature errors as large as [Formula: see text]C can occur if the experiment is not properly designed. A new IRT error model is found to explain the data. More importantly, we show how to precisely monitor temperature with IRT during hyperthermia, which could positively impact heat dosimetry and clinical planning.

Cytotoxic and Genotoxic Effects of cis-Tetraammine(oxalato)Ruthenium(III) Dithionate on the Root Meristem Cells of Allium cepa

Ruthenium complexes have attracted much attention as possible building blocks for new transition-metal-based antitumor agents. The present study examines the mitotoxic and clastogenic effects induced in the root tips of Allium cepa by cis-tetraammine(oxalato)ruthenium(III) dithionate {cis-[Ru(C2O2)(NH3)4]2(S2O6)} at different exposure durations and concentrations. Correlation tests were performed to determine the effects of the time of exposure and concentration of ruthenium complex on mitotic index (MI) and mitotic aberration index. A comparison of MI results of cis-[Ru(C2O2)(NH3)4]2(S2O6) to those of lead nitrate reveals that the ruthenium complex demonstrates an average mitotic inhibition eightfold higher than lead, with the frequency of cellular abnormalities almost fourfold lower and mitotic aberration threefold lower. A. cepa root cells exposed to a range of ruthenium complex concentrations did not display significant clastogenic effects. Cis-tetraammine(oxalato)ruthenium(III) dithionate therefore exhibits a remarkable capacity to inhibit mitosis, perhaps by inhibiting DNA synthesis or blocking the cell cycle in the G2 phase. Further investigation of the mechanisms of action of this ruthenium complex will be important to define its clinical potential and to contribute to a novel and rational approach to developing a new metal-based drug with antitumor properties complementary to those exhibited by the drugs already in clinical use.

Cytotoxic effects of the compound cis-tetraammine(oxalato)ruthenium(III) dithionate on K-562 human chronic myelogenous leukemia cells.

Chemotherapy is a common treatment for leukemia. Ruthenium complexes have shown potential utility in chemotherapy and photodynamic therapy. The identification of new chemotherapeutics agents is critical for further progress in the treatment of leukemia. Ruthenium complexes generally have lower toxicities compared to cisplatin attributed to their specific accumulation in cancer tissues. Based on these evidences, in the present work we studied the cytotoxic activity of the ruthenium(III) compound cis-tetraammine(oxalato)ruthenium(III) dithionate - {cis-[Ru(C2O4)(NH3)4]2(S2O6)} against human chronic myelogenous leukemia cells (K-562) tumor cell line. The tested compound induces cell death in a dose and time dependent manner on K-562 cells. It is found that the effect was improved linearly while prolonging the incubation time. Compared to the cell cycle profiles of untreated cells, flow cytometric analysis indicated the sub-G1 arresting effect of ruthenium compound on K-562 cells. In our study, {cis-[Ru(C2O4)(NH3)4]2(S2O6)} shows a significant increase in tailed cells in any of the concentrations tested compared with negative control. Consequently, the concentration of {cis-[Ru(C2O4)(NH3)4]2(S2O6)} might be associated cytotoxicity with direct effect on K-562 cells DNA. Thus, it can be deducted that ruthenium-based compounds present selectivity to enter both tumor and normal cells. Additional studies are needed to determine the molecular mechanisms of the active components and to evaluate the potential in vivo anticancer activity of the cis-tetraammine(oxalato)ruthenium(III) dithionate.