Fernando Barbosa Júnior

Identification and quantification of phytochelatins in roots of rice to long-term exposure: evidence of individual role on arsenic accumulation and translocation

Summary Six varieties of rice were exposed to low and high levels of arsenic in the same soil. Their individual responses of expressing phytochelatins have been correlated to inorganic arsenic uptake, transport, and accumulation in the rice grain.

Cryogenic sample grinding for copper, lead and manganese determination in human teeth by slurry sampling GFAAS

A simple method is proposed for copper, lead and manganese determination in deciduous teeth by graphite furnace atomic absorption spectrometry (GFAAS) using slurry sampling introduction and cryogenic sample preparation. Teeth samples were ground in a cryogenic mill in two steps: pre-cooling (5 min) and cryogenic grinding (2 min) in liquid nitrogen. After grinding, 90% of the sample particles were lower than 150 µm. The minimum mass necessary for slurry preparation as an indicator of sub-sample homogeneity was evaluated by weighting masses between 5 and 20 mg directly in autosampler cups, followed by addition of 1 mL of a solution containing 0.04% Triton® X-100 and 0.2% v/v HNO3. Samples (20 µL) were sonicated during 20 s, before delivering into a W–Rh coated platform. Detection limits based on integrated absorbance were 34.0 ng g−1 Pb, 7.4 ng g−1 Mn and 18.0 ng g−1 Cu for 2% m/v slurries. W–Rh permanent modifier permitted calibration against aqueous standards. The Certified Reference Material (H-5 animal bone) from the International Agency of Atomic Energy (IAEA) was analyzed to determine lead for method validation. For copper, lead and manganese, 12 human teeth samples were analyzed using the proposed method with calibration against aqueous solution and using a comparative Pd/Mg method with the same digested samples, and standard addition calibration, with no statistical difference at 95% level on applying the t-test.

Inhibition of hydrogen sulphide formation reduces cisplatin-induced renal damage

BACKGROUND Cisplatin (CP)-induced renal damage is associated with inflammation. Hydrogen sulphide (H2S) is involved in models of inflammation. This study evaluates the effect of DL-propargylglycine (PAG), an inhibitor of endogenous H2S formation, on the renal damage induced by CP. METHODS The rats were injected with CP (5 mg/kg, i.p.) or PAG (5 mg/kg twice a day, i.p.) for 4 days, starting 1 h before CP injection. Control rats were injected with 0.15 M NaCl or PAG only. Blood and urine samples were collected 5 days after saline or CP injections for renal function evaluation. The kidneys were removed for tumour necrosis factor (TNF)-α quantification, histological, immunohistochemical and Western blot analysis. The cystathionine γ-lyase (CSE) activity and expression were assessed. The direct toxicity of H(2)S in renal tubular cells was evaluated by the incubation of these cells with NaHS, a donor of H2S. RESULTS CP-treated rats presented increases in plasma creatinine levels and in sodium and potassium fractional excretions associated with tubulointerstitial lesions in the outer medulla. Increased expression of TNF-α, macrophages, neutrophils and T lymphocytes, associated with increased H2S formation rate and CSE expression, were also observed in the outer medulla from CP-injected rats. All these alterations were reduced by treatment with PAG. A direct toxicity of NaHS for renal tubular epithelial cells was not observed. CONCLUSIONS Treatment with PAG reduces the renal damage induced by CP. This effect seems to be related to the H2S formation and the restriction of the inflammation in the kidneys from PAG + CP-treated rats.

Quercetin protects human-derived liver cells against mercury-induced DNA-damage and alterations of the redox status.

Aim of this study was to investigate the cytotoxic and genotoxic properties of inorganic and organic mercury compounds, i.e., HgCl(2) and methylmercury (MeHg). In addition, the DNA-protective and antioxidant effects of the flavonoid quercetin (QC) were studied. All experiments were conducted with human-derived liver cells (HepG2), which possess antioxidant and drug-metabolizing enzymes in an inducible form. 8-Hydroxydeoxyguanosine (8-OHdG) and comet formation were monitored as endpoints of DNA damage. The impact of the metal compounds on the redox status was also investigated, since it is assumed that their toxic effects are due to oxidative damage. A number of biochemical parameters related to oxidative stress, namely glutathione, malondialdehyde, protein carbonyl and formation of reactive oxygen species (ROS) were measured after treatment of the cells with the mercury compounds in the presence and absence of quercetin. To elucidate the mechanisms that underlie the effects of QC, three protocols (pre-, simultaneous and post-treatment) were used. Both mercury compounds (range 0.1-5.0μM) caused induction of DNA migration and formation of 8-OHdG. In combination with the flavonoid (range 0.1-5.0μM), DNA-protective effects of QC were observed after pre- and simultaneous treatment but not when the flavonoid was added after treatment with the metal compounds. Exposure to the metal compounds led also to substantial changes of all parameters of the redox status and co-treatment experiments with QC showed that these alterations are reversed by the flavonoid. Taken together, the results of our experiments indicate that these two mercury compounds cause DNA damage and oxidative stress in human-derived liver cells and that the flavonoid reduces these effects. Since the concentrations of the metals and of the flavonoids used in the present work reflect human exposure, our findings can be taken as an indication that QC may protect humans against the adverse effects caused by the metal.

Evaluation of the genotoxic and anti-genotoxic activities of Silybin in human hepatoma cells (HepG2)

Silybin (SB), a constituent of the medicinal plant Silybum marianum, is reported to be a potent hepatoprotective agent, but little is currently known regarding its genotoxicity, mutagenicity and potential chemopreventive properties. In this study, we evaluated the ability of SB to induce DNA migration and micronuclei (MN) formation in human hepatoma cells (HepG2). Also, possible preventive effects of SB on MN formation induced by three different mutagens, bleomycin (BLEO), benzo[a]pyrene (B[a]P) and aflatoxin B(1) (AFB(1)), were studied. To clarify the possible mechanism of SB antimutagenicity, three treatment protocols were applied: pretreatment, in which SB was added before the application of the mutagens; simultaneous treatment, in which SB was added during treatment and post-treatment, in which SB was added after the application of the mutagens. At concentrations up to 100 microM, SB was non-genotoxic, while at a concentration of 200 microM, SB induced DNA migration, generated oxidized DNA bases, reduced cell viability, decreased the replicative index of the cells and induced oxidative stress. It is noteworthy that SB was able to reduce the genotoxic effect induced by B[a]P, BLEO and AFB(1) in pretreatment and simultaneous treatments but had no significant effect on DNA damage induction in post-treatment. Taken together, our findings indicate that SB presents anti-genotoxic activity in vitro, which suggests potential use as a chemopreventive agent.

Effect of different cleansers on the weight and ion release of removable partial denture: an in vitro study

Objective Removable partial dentures (RPD) require different hygiene care, and association of brushing and chemical cleansing is the most recommended to control biofilm formation. However, the effect of cleansers has not been evaluated in RPD metallic components. The aim of this study was to evaluate in vitro the effect of different denture cleansers on the weight and ion release of RPD. Material and Methods Five specimens (12x3 mm metallic disc positioned in a 38x18x4 mm mould filled with resin), 7 cleanser agents [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05% sodium hypochlorite (NaOCl), and distilled water (DW) (control)] and 2 cobalt-chromium alloys [DeguDent (DD), and VeraPDI (VPDI)] were used for each experimental situation. One hundred and eighty immersions were performed and the weight was analyzed with a high precision analytic balance. Data were recorded before and after the immersions. The ion release was analyzed using mass spectrometry with inductively coupled plasma. Data were analyzed by two-way ANOVA and Tukey HSD post hoc test at 5% significance level. Results Statistical analysis showed that CT and MI had higher values of weight loss with higher change in VPDI alloy compared to DD. The solutions that caused more ion release were NaOCl and MI. Conclusions It may be concluded that 0.05% NaOCl and Medical Interporous tablets are not suitable as auxiliary chemical solutions for RPD care.

RARE EARTH ELEMENTS IN CITRUS PRODUCTION SYSTEMS

This work focuses on the determination of rare earth elements (REE) in citrus ecosystem using instrumental neutron activation analysis (INAA) and inductively coupled plasma mass spectrometry (ICP-MS). A comprehensive sampling was carried out in two organic and two conventional farms in the vicinity of Borborema city, São Paulo State, Brazil. The concentrations of lanthanum (La) in leaves were similar to those found in the soil with soil-to-plant transfer factors ranging from 0.65 to 1.05. The amount of REE decreased sequentially in the compartments soil, leaf, peel, pulp, seed and juice. Citrus plants can be considered accumulators of REE.

Effect of diabetes on biodistribution, nephrotoxicity and antitumor activity of cisplatin in mice.

Both types of diabetes are associated with higher incidence of some types of cancer. Treating cancer in diabetic patients without aggravating diabetes-related complications is a challenge for clinicians. Additionally, little is known about how diabetes affects the treatment of cancer. One of the most effective chemotherapeutic drugs is cisplatin, which is nephrotoxic. Studies suggest that diabetes acts as a protective factor against the nephrotoxicity of cisplatin, but the mechanisms involved have not been elucidated yet. This renal protection has been attributed to decreased accumulation of cisplatin in the kidneys, which could be associated with deficient active transport of proximal tubular cells or to pharmacokinetic alterations caused by diabetes. However, it is uncertain if diabetes also compromises the antitumor activity of cisplatin. To address this issue, we developed a mouse model bearing cisplatin-induced nephrotoxicity, Sarcoma 180 and streptozotocin-induced diabetes. Four groups of treatment were defined: (i) control, (ii) diabetic, (iii) cisplatin and (iv) diabetic treated with cisplatin. The following parameters were evaluated: renal function, oxidative stress, apoptosis, renal histopathology, tumor remission, survival rate, genotoxicity and platinum concentration in tumor and several organs. Results indicate that diabetes protects against the renal damage induced by cisplatin, while also compromises its antitumor effectiveness. This is the first study to demonstrate this effect.

Possíveis efeitos do cobre sanguíneo sobre parâmetros hematológicos em idosas

INTRODUCTION: Copper is an essential trace element, and its homeostasis is important, mainly among the elderly, since their metabolism is associated with neurodegenerative diseases and erythropoiesis disorders, among others. OBJECTIVE: This study evaluated the association among cupremia, hematological parameters and oxidative stress. MATERIAL AND METHODS: Blood samples from 39 elderly women (study group) and 20 health individuals (control group) were collected. The concentrations of serum copper were quantified by ICP-MS. The activity and enzyme ALA-D reactivation index were determined by spectrophotometry and blood parameters were analyzed in the automated system. The results were expressed as mean ± standard deviation. RESULTS: Concentrations of copper, hematological parameters and ALA-D reactivation were within the reference values in both groups. However, ALA-D activity (11.47 ± 2.81 UL-1) was significantly lower in the study group compared to the control group. Spearman correlations (observed only in elderly women) between copper concentration versus hemoglobin, hematocrit and ALA-D activity were -0.384, -0.408 and -0.395, respectively (p < 0.05). Nonetheless, ALA reactivation index was not related to cupremia. DISCUSSION AND CONCLUSION: The results showed that copper, although it is within accepted reference values, may be involved in ALA-D inhibition, which may affect hematological parameters such as hemoglobin synthesis. Thus, the reference levels for copper in the elderly should be reviewed.

Ascorbic acid supplementation partially prevents the delayed reproductive development in juvenile male rats exposed to rosuvastatin since prepuberty

Dyslipidemias are occurring earlier in the population due to the increase of obesity and bad eating habits. Rosuvastatin inhibits the enzyme HMG-CoA reductase, decreasing total cholesterol. Ascorbic acid is an important antioxidant compound for male reproductive system. This study aimed to evaluate whether ascorbic acid supplementation may prevent the reproductive damage provoked by rosuvastatin administration at prepuberty. Male pups were distributed into six experimental groups that received saline solution 0.9%, 3 or 10mg/kg/day of rosuvastatin, 150mg/day of ascorbic acid, or 150mg/day of ascorbic acid associated with 3 or 10mg/kg/day of rosuvastatin from post-natal day (PND) 23 until PND53. Rosuvastatin-treated groups showed delayed puberty installation, androgen depletion and impairment on testicular and epididymal morphology. Ascorbic acid partially prevented these reproductive damages. In conclusion, rosuvastatin exposure is a probable risk to reproductive development and ascorbic acid supplementation may be useful to prevent the reproductive impairment of rosuvastatin exposure.