Marcos Marques da Silva Paula

DNA damage after acute and chronic treatment with malathion in rats

Malathion is an insecticide widely used in agriculture and in public health programs that when used indiscriminately in large amounts can cause environmental pollution and risk to human health. However, it is possible that during the metabolism of malathion, reactive oxygen species can be generated, and malathion may produce oxidative stress in intoxicated rats that can be responsible for alterations in DNA molecules related in some studies. As a result, the present study aimed to investigate the DNA damage of cerebral tissue and peripheral blood in rats after acute and chronic malathion exposure. We used single cell gel electrophoresis (Comet assay) to measure early damage in hippocampus and peripheral blood and the Micronucleus test in total erythrocytes samples. Malathion was administered intraperitoneally once a day for one day (acute) or for 28 days (chronic) protocols (in both protocols, malathion was administered at 25, 50, 100, and 150 mg/kg). Our results showed that malathion (100 and 150 mg/kg) increased the DNA damage index in the peripheral blood and in the hippocampus after both chronic and acute treatment. Malathion increased the frequency of micronuclei only in chronic treatment at 150 mg/kg dose, and induced a cytotoxic dose-dependent decrease in the frequency of polychromatic erythrocytes in the peripheral blood of rats. In conclusion, since malathion increased both the peripheral blood and hippocampus DNA damage index using the Comet assay and increased the frequency of micronuclei in the total peripheral blood, it can be regarded as a potential mutagen/carcinogenic agent.

Effects of Therapeutic Pulsed Ultrasound and Dimethylsulfoxide (DMSO) Phonophoresis on Parameters of Oxidative Stress in Traumatized Muscle

Many studies have demonstrated an increase in reactive oxygen species (ROS) and oxidative damage markers after muscle damage. Phonophoresis aims to achieve therapeutically relevant concentrations of the transdermally introduced drug in the tissues subjected to the procedure by the use ultrasound waves. The aim of the study was to evaluate the effects on the therapeutic pulsed ultrasound (TPU) together with gel-dimethylsulfoxide (DMSO) in the parameters of muscular damage and oxidative stress. Male Wistar rats were divided randomly into six groups (n=6): sham (uninjured muscle); muscle injury without treatment; muscle injury and treatment with gel-saline (0.9%); muscle injury and treatment with gel-DMSO (15mg/kg); muscle injury and TPU plus gel-saline; and muscle injury and TPU plus gel-DMSO. Gastrocnemius injury was induced by a single impact blunt trauma. TPU (6min duration, frequency of 1.0MHz, intensity of 0.8W/cm(2)) was used 2, 12, 24, 48, 72, 96 and 120h after muscle trauma. The CK and acid phosphatase activity in serum was used as an indicator of skeletal muscle injury. Superoxide anion, TBARS, protein carbonyls, superoxide dismutase (SOD) and catalase (CAT) activity was used as indicators of stress oxidative. Results showed that TPU and gel-DMSO improved muscle healing. Moreover, superoxide anion production, TBARS level and protein carbonyls levels, superoxide dismutase (SOD) and catalase (CAT) activity were all decreased in the group TPU plus gel-DMSO. Our results show that DMSO is effective in the reduction of the muscular lesion and in the oxidative stress after mechanical trauma only when used with TPU. (E-mail: silveira_paulo2004@yahoo.com.br).

Synthesis of luminescent liquid crystals derived from gallic acid containing heterocyclic 1,3,4-oxadiazole

This article describes the synthesis, liquid crystalline and photophysical properties of luminescent liquid crystalline compounds, derived from gallic acid containing heterocyclic 1,3,4-oxadiazole. The mesophases of these compounds were characterised using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All compounds showed high thermal stability and blue photoluminescence in solution, with emission maxima between 376 and 381 nm. For all compounds, the liquid crystalline behaviour was preserved on cooling from the isotropic state to room temperature. These characteristics make these materials good candidates for application in organic electronics.

In vitro effect of silver nanoparticles on creatine kinase activity

One of the most prominent nanoproducts is the silver nanoparticle (AgN), since silver ions exhibit remarkably unusual physical, chemical and biological properties. Creatine kinase (CK) plays a central role in metabolism of high-energy consuming tissues such as brain, skeletal muscle and heart, where it functions as an effective buffering system of cellular ATP levels. A decrease of CK activity may impair energy homeostasis, contributing to cell death. In the present work we studied the in vitro effect of AgN on the activity of CK from rat brain, heart and skeletal muscle. Our results demonstrated that AgN (10, 25 and 50 mg L-1) in vitro inhibited CK from brain and skeletal muscle, but not from heart. Several works showed that AgN cytotoxic effects probably involve interaction between silver ions and sulphydryl groups of proteins. We suggest that AgN inhibited CK activity through interactions with thiol groups of the enzyme.

Effects of gold nanoparticles on endotoxin-induced uveitis in rats.

PURPOSE This study evaluates the effects of the gold nanoparticle in endotoxin-induced uveitis in rats. METHODS Adult male Wistar rats were divided into five groups: saline + saline, lipopolysaccharide (LPS) + saline, LPS + prednisolone, LPS + gold salt (GS) and LPS + gold nanoparticle (GNP). Two hours after LPS administration, prednisolone acetate 1%, GS, and GNP were topically applied to both eyes of rats and repeated every 6 hours for 24 hours. After 24 hours, rats were anesthetized and aqueous humor was sampled and the irides were removed. Aqueous humor TNF-α, myeloperoxidase activity were determined. Irides oxidative damage and content of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) were determined. RESULTS The administration of LPS-induced eye inflammatory response characterized by an increase in aqueous humor TNF-α, myeloperoxidase, and by irides oxidative damage. All these parameters were decreased by the administration of GNP. Since the inflammatory response secondary to LPS administration depends, in part, to the activation of the TLR4-NF-κB pathway we demonstrated here that a potential mechanism to explain the GNP effects was the decrease on TLR4 content and NF-κB activation. CONCLUSIONS These findings suggest that topical GNP decreases intraocular inflammation and oxidative damage by interfering in the TLR4-NF-κB pathway.

Acute and chronic administration of gold nanoparticles cause DNA damage in the cerebral cortex of adult rats.

The use of gold nanoparticles is increasing in medicine; however, their toxic effects remain to be elucidated. Studies show that gold nanoparticles can cross the blood-brain barrier, as well as accumulate in the brain. Therefore, this study was undertaken to better understand the effects of gold nanoparticles on rat brains. DNA damage parameters were evaluated in the cerebral cortex of adult rats submitted to acute and chronic administration of gold nanoparticles of two different diameters: 10 and 30nm. During acute administration, adult rats received a single intraperitoneal injection of either gold nanoparticles or saline solution. During chronic administration, adult rats received a daily single injection for 28 days of the same gold nanoparticles or saline solution. Twenty-four hours after either single (acute) or last injection (chronic), the rats were euthanized by decapitation, their brains removed, and the cerebral cortices isolated for evaluation of DNA damage parameters. Our study showed that acute administration of gold nanoparticles in adult rats presented higher levels of damage frequency and damage index in their DNA compared to the control group. It was also observed that gold nanoparticles of 30nm presented higher levels of damage frequency and damage index in the DNA compared to the 10nm ones. When comparing the effects of chronic administration of gold nanoparticles of 10 and 30nm, we observed that occurred significant different index and frequency damage, comparing with control group. However, there is no difference between the 10 and 30nm groups in the levels of DNA damage for both parameters of the Comet assay. Results suggest that gold nanoparticles for both sizes cause DNA damage for chronic as well as acute treatments, although a higher damage was observed for the chronic one.

Effect of Therapeutic Pulsed Ultrasound on Lipoperoxidation and Fibrogenesis in an Animal Model of Wound Healing

Evidence from the literature has shown that the wound healing process is enhanced by ultrasound therapy. In the present study, we measured thiobarbituric acid-reactive substances (TBARS; index of lipoperoxidation) and hydroxyproline (index of collagen synthesis) levels in wounds after therapeutic pulsed ultrasound (TPU) treatment. Male Wistar rats were submitted to skin ulceration, and three doses of TPU (0.4, 0.6, and 0.8W/cm(2)) were used. A circular area of skin was removed with a punch biopsy from the medial dorsal region. After TPU for 10 days, TBARS (Draper and Hadley [21]) and hydroxyproline (Woessner [22]) levels were measured in the tissue around the wound. Results showed that TPU improved wound healing, since the wound size was significantly smaller 5 and 10 days after ulceration in groups submitted to this treatment. Moreover, TBARS levels were decreased in the 0.4, 0.6, and 0.8W/cm(2) TPU groups, and hydroxyproline levels were increased in the 0.6 and 0.8W/cm(2) TPU groups. These findings indicate that TPU presents beneficial effects on the wound healing process, probably by speeding up the inflammatory phase and inducing collagen synthesis.

Antioxidant activity of new ruthenium compounds

Abstract Many biological properties have been attributed to ruthenium complexes including anti-tumor activity and the attenuation of reperfusion damage and infarct size. In this work, we characterize the antioxidant activity of trans-[RuCl2(nic)4] where nic is 3-pyridinecarboxylic acid and trans-[RuCl2(i-nic)4] where i-nic is 4-pyridinecarboxylic acid by (i) evaluation of total antioxidant potential (TRAP); (ii) prevention of DNA damage induced by hydrogen peroxide using the alkaline comet assay; and (iii) the prevention of lipid peroxidation and cell death induced by iron in liver slices. Our results suggest that nic has stronger antioxidant potential when compared to the i-nic. Higher doses (above 200 μM) of these compounds gave genotoxic effects, but the antioxidant potential could be obtained with the use lower doses (0.1–10 μM).

Gold nanoparticles alter parameters of oxidative stress and energy metabolism in organs of adult rats.

This study evaluated the parameters of oxidative stress and energy metabolism after the acute and long-term administration of gold nanoparticles (GNPs, 10 and 30 nm in diameter) in different organs of rats. Adult male Wistar rats received a single intraperitoneal injection or repeated injections (once daily for 28 days) of saline solution, GNPs-10 or GNPs-30. Twenty-four hours after the last administration, the animals were killed, and the liver, kidney, and heart were isolated for biochemical analysis. We demonstrated that acute administration of GNPs-30 increased the TBARS levels, and that GNPs-10 increased the carbonyl protein levels. The long-term administration of GNPs-10 increased the TBARS levels, and the carbonyl protein levels were increased by GNPs-30. Acute administration of GNPs-10 and GNPs-30 increased SOD activity. Long-term administration of GNPs-30 increased SOD activity. Acute administration of GNPs-10 decreased the activity of CAT, whereas long-term administration of GNP-10 and GNP-30 altered CAT activity randomly. Our results also demonstrated that acute GNPs-30 administration decreased energy metabolism, especially in the liver and heart. Long-term GNPs-10 administration increased energy metabolism in the liver and decreased energy metabolism in the kidney and heart, whereas long-term GNPs-30 administration increased energy metabolism in the heart. The results of our study are consistent with other studies conducted in our research group and reinforce the fact that GNPs can lead to oxidative damage, which is responsible for DNA damage and alterations in energy metabolism.

Biological Activity of Gold Nanoparticles towards Filamentous Pathogenic Fungi

Gold nanoparticles (GNP) were synthesized, characterized and their antifungal activities investigated against three pathogenic fungi of different genera and species (Fusarium verticillioides, Penicillium citrinum and Aspergillus flavus). The anti-fungi treatments efficiency of the GNP (concentrations: 0, 0.05, 0.1 and 0.2 mg L-1 in PDA media) were evaluated at 2, 4, 6 and 8 days after incubation by measuring the diameter of fungal colonies and investigating fungi structure alterations by scanning electron microscopy (SEM). It was observed that the GNP concentration increased, fungal colony growth diameter reduced. However, the highest GNP concentration applied in the experiment was not able to completely inhibit fungal growth. The SEM analysis of the fungi structure Au treated showed damaged hyphae and unusual bulges that were not observed in fungi that growth on medium without treatment (Control). Although up to the highest concentration of GNP media applied did not completely inhibited fungi growth, the hyphae modifications led growth reduction which could influence the toxins production by these fungi.