Marília Martins Melo

Gossypol Toxicity from Cottonseed Products

Gossypol is a phenolic compound produced by pigment glands in cotton stems, leaves, seeds, and flower buds (Gossypium spp.). Cottonseed meal is a by-product of cotton that is used for animal feeding because it is rich in oil and proteins. However, gossypol toxicity limits cottonseed use in animal feed. High concentrations of free gossypol may be responsible for acute clinical signs of gossypol poisoning which include respiratory distress, impaired body weight gain, anorexia, weakness, apathy, and death after several days. However, the most common toxic effects is the impairment of male and female reproduction. Another important toxic effect of gossypol is its interference with immune function, reducing an animals resistance to infections and impairing the efficiency of vaccines. Preventive procedures to limit gossypol toxicity involve treatment of the cottonseed product to reduce the concentration of free gossypol with the most common treatment being exposure to heat. However, free gossypol can be released from the bound form during digestion. Agronomic selection has produced cotton varieties devoid of glands producing gossypol, but these varieties are not normally grown because they are less productive and are more vulnerable to attacks by insects.

Biochemical profile of dogs experimentally envenomed with Tityus serrulatus scorpion venom.

The aim of this study was to evaluate the canine blood and urinary profiles after envenomation by Tityus serrulatus venom. Twelve dogs were randomly distributed into two equal groups. Control group animals received 0.5 mL phosphate buffered saline (PBS) injected subcutaneously into the internal portion of the left thigh, whilst dogs in the envenomed group were injected with scorpion venom (250 microg/kg in 0.5 mL PBS). No significant alterations were detected in the urine of envenomed dogs. Levels of plasma glucose and serum urea, creatinine, total protein, potassium, alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK), lactate dehydrogenase (LDH), and amylase were determined. Semi-quantitative analysis of serum cardiac troponin I (cTnI) was performed using an immunochromatographic test. The concentrations of cortisol and insulin were determined using commercial radioimmunoassay kits. Increases in serum cortisol levels in experimental group animals coincided with hyperglycaemia and was probably a response to pain. Increased insulin levels were observed during the hyperglycaemic peaks. Envenomed dogs presented discreet increases in ALT, AST and CK, but no alterations in LDH, amylase, cTnI, urea, creatinine and potassium levels were observed. It was concluded that the venom of T. serrulatus induces blood and urinary biochemical changes in dogs.

Doxorubicin has in vivo toxicological effects on ex vivo cultured mesenchymal stem cells.

Doxorubicin (dox) is an effective chemotherapeutic agent that leads to cardiotoxicity. An alternative treatment for dox-cardiotoxicity is autologous mesenchymal stem cells (MSCs) transplantation. It remains unclear if dox has deleterious effects on MSCs from subjects under chemotherapy, therefore this study aimed to evaluate dox in vivo toxicological effects on ex vivo cultured MSCs, inferring whether autologous transplantation may be an alternative treatment in patients who are exposed to the drug. Wistar rats received either dox or saline. Following treatments, animals were sacrificed and bone marrow MSCs were isolated, characterized for cell surface markers and assessed according to their viability, alkaline phosphatase production, and proliferation kinetics. Moreover, MSCs were primed to cardiac differentiation and troponin T and connexin 43 expressions were evaluated. Compared to control, undifferentiated MSCs from dox group kept the pattern for surface marker and had similar viability results. In contrast, they showed lower alkaline phosphatase production, proliferation rate, and connexin 43 expression. Primed MSCs from dox group showed lower troponin T levels. It was demonstrated a toxic effect of dox in host MSCs. This result renders the possibility of autologous MSCs transplantation to treat dox-cardiotoxicity, which could be a non-suitable option for subjects receiving such antineoplastic agent.

Antitumor effectiveness and toxicity of cisplatin-loaded long-circulating and pH-sensitive liposomes against Ehrlich ascitic tumor

Cisplatin (CDDP) is one of the most active cytotoxic agents commonly used in the treatment of peritoneal carcinomatosis. The disadvantages of its clinical use are systemic side-effects, such as nephrotoxicity and myelotoxicity. Long-circulating and pH-sensitive liposomes containing CDDP (SpHL-CDDP) were developed by our research group aiming to promote the release of CDDP near the tumor as well as decreasing toxicity. The aim of this study was to evaluate the antitumor efficacy and toxicity of SpHL-CDDP after intraperitoneal administration in initial or disseminated tumor-bearing mice, at a dose of 12 mg/kg. The survival was monitored and blood samples were collected for biochemical and hematological analysis. Kidneys, liver and spleen were removed for histopathological examination. Tumor cells were evaluated for cellular viability and cell cycle. The survival of animals treated with SpHL-CDDP was higher than those treated with free CDDP. The cell death caused by treatment with SpHL-CDDP occurred through induction of apoptosis, with a cell cycle arrest at the G0/G1 phase. The treatment of mice presenting initial cancer with both formulations provoked a suppression of granulocytes. Mice treated with free CDDP also showed a decrease in platelet count, which suggests a high myelotoxicity. In an advanced cancer model, SpHL-CDDP treatment allowed an improvement of the immune response. Mice affected by cancer at an early stage and treated with free CDDP or SpHL-CDDP showed a lower urea/creatinine index compared with the saline control group. These findings indicate that both treatments were able to reduce the renal damage caused by peritoneal carcinomatosis. Microscopic analysis of kidneys from mice treated with SpHL-CDDP showed a discrete morphological alteration, while tubular necrosis was observed for free CDDP-treated mice. Concerning hepatotoxicity, no alteration in clinical chemistry parameters was observed. These findings reveal that SpHL-CDDP can improve the antitumor efficacy and decrease renal and bone marrow toxicity.

Pesticide exposure of honeybees (Apis mellifera) pollinating melon crops

The decline of honeybee (Apis mellifera L.) populations impacts global agricultural production and affects both food production and the economy. One of the probable causes for this decline is the indiscriminate use of pesticides. Here, we compare the levels of pesticide exposure among honeybees that are used to pollinate melon (Cucumis melo L.) crops, honeybees that forage in the forest, and stingless bees, Melipona subnitida, that forage in the forest. The level of pesticide exposure was determined by measuring residual pesticide levels of 152 compounds in the honey. Honey samples from the present study contained 19 different pesticides, 13 of which were present in honey from bees pollinating melon crops. The levels of some compounds were sufficiently high to promote toxic effects in the bees. Thus, crop pollination presents a toxicological risk to bees that may reduce their life span.

Tityus fasciolatus envenomation induced cardio-respiratory alterations in rats.

The present study characterized envenomation in young rats by Tityus fasciolatus, an endemic scorpion to Central Brazilian and state of Minas Gerais. Electrocardiographic examinations were performed prior to treatment and every 5 min during the first 30 min after envenomation. The cardiac blood profile [creatine kinase, CK isoenzyme MB, lactate dehydrogenase, aspartate aminotransferase and troponina] together with macroscopic and microscopic alterations in the lungs and heart were evaluated. Envenomated animals showed ECG changes suggesting electrolytic imbalance, myocarditis and venom interference on the conduction tissue. Biochemical analyses indicated myocardial damage with high levels of CK, CK-MB and LDH. Macroscopic and microscopic findings included detection of pulmonary haemorrhages. In conclusion, T. fasciolatus venom leads to acute cardio-respiratory changes in young rats.

Intoxicação experimental com extratos de Mascagnia rigida (Malpighiaceae) em camundongos

Foi realizado o fracionamento quimico do extrato aquoso da Mascagnia rigida Griseb., uma importante planta toxica no Brasil, para se obter cinco substratos ricos em diferentes grupos quimicos - alcaloides, flavanoides, taninos, saponinas e acucares, acidos orgânicos e aminoacidos -, e investigar a toxicidade dessas fracoes, exceto a ultima, em 75 camundongos. Os animais, distribuidos aleatoriamente em cinco grupos, receberam: grupo I - alcaloides; grupo II - flavanoides; grupo III - taninos; grupo IV - saponinas e grupo V - placebo, este ultimo funcionando como controle negativo. Todos os grupos, com excecao do grupo-controle, redistribuidos em tres subgrupos, A, B e C, com cinco animais cada, receberam, respectivamente, 9g/kg, 18g/kg e 27g/kg de cada substrato. As fracoes foram fornecidas via oral, diariamente, por sete dias; no setimo dia, foi coletado sangue para o estudo do perfil sanguineo e dosagem de enzimas musculares. As fracoes de alcaloides e taninos foram capazes de causar alteracao no perfil enzimatico-muscular, com aumento significativo da enzima miocardica. Observou-se, tambem, aumento significativo na porcentagem da CK-MB apos a administracao das fracoes de saponinas e taninos, comprovando a acao toxica da M. rigida sobre a fibra muscular cardiaca.

Experimental intoxication of pregnant goats with Tetrapterys multiglandulosa A. Juss. (Malpighiaceae)

Com o objetivo de investigar a toxicidade da Tetrapterys multiglandulosa A. Juss. foram utilizadas 15 cabras gestantes, divididas aleatoriamente em tres grupos (GI, GII e GIII) com cinco animais cada. Apos estabelecer o diagnostico de gestacao no tempo medio de 35 dias, eram oferecidas diariamente doses de 10 e 20g/kg PV das folhas (jovens e maduras) de Tetrapterys multiglandulosa para os grupos I e II, respectivamente, junto ao capim picado, feno e concentrado. Para o grupo III, usado como controle, foram fornecidos somente capim picado, feno e concentrado. Todos os animais foram submetidos a exames clinicos diarios e a ultra-sonografia a cada tres dias. Foi detectada por ultra-sonografia morte fetal e, ao exame clinico, presenca de secrecao vaginal com subsequente aborto. Os animais dos grupos I e II (tradados) abortaram no terceiro e no final do segundo mes de gestacao, respectivamente, e juntos com os do grupo III (controle) foram sacrificados e submetidos a exames anatomo-histopatologicos. Pela histopatologia observou-se placentite focal com grande quantidade de celulas trofoblasticas binucleadas em apoptose, alem de endometrite focal aguda e petequias vulvo-vaginais. Todos os fetos abortados estavam subdesenvolvidos quando comparados com os fetos do grupo III (controle) devido a malnutricao, pois nenhum defeito congenito pode ser notado. Varios fetos abortados mostravam alguma autolise, pois sua morte precedia em cinco e tres dias o aborto, nos tratamentos I e II, respectivamente. As lesoes fetais observadas foram hemorragias difusas ou focais na pele, meninges e serosa visceral.

Pesticides residues in the Prochilodus costatus (Valenciennes, 1850) fish caught in the São Francisco River, Brazil

The objective of this study was to determine the levels of pesticides in the fish Prochilodus costatus caught in São Francisco River, one of most important rivers in Brazil. Thirty-six fish were captured in three different areas, and samples of the dorsal muscle and pooled viscera were collected for toxicological analysis. We evaluated the presence of 150 different classes of insecticides, fungicides, herbicides and acaricides by multiresidue analysis technique using liquid chromatography-tandem mass spectrometry (LC-MS/MS), with the limit of detection of 5 ppb. In this study, organophosphorus and carbamate pesticides were detected at the highest levels in the caught fish. Among the 41 organophosphorus pesticides surveyed, nine types were detected (chlorpyrifos, diazinon, dichlorvos, disulfoton, ethion, etrimfos, phosalone, phosmet and pyrazophos) in the muscle, viscera pool, or both in 22 (61.1%) fish. Sampled tissues of 20 (55.6%) fish exhibited at least one of the eight evaluated carbamate pesticides and their metabolites: aldicarb, aldicarb sulfoxide, carbaryl, carbofuran, carbosulfan, furathiocarb, methomyl and propoxur. Fungicides (carbendazim, benalaxyl, kresoxim-methyl, trifloxystrobin, pyraclostrobin and its metabolite BF 500 pyraclostrobin), herbicides (pyridate and fluasifop p-butyl), acaricide (propargite) and pyrethroid (flumethrin) were also detected. In conclusion, P. costatus fish caught in the São Francisco River contained residues of 17 different pesticides, in both muscles and the viscera pool, indicating heavy environmental contamination by pesticides in the study area.

Evaluation of adverse effects in tamoxifen exposed healthy female dogs

BackgroundMammary tumors are among the most frequent neoplasms in female dogs, but the strategies employed in animal treatment are limited. In human medicine, hormone manipulation is used in cancer therapy. Tamoxifen citrate is a selective inhibitor of oestrogen receptors and exerts a potent anti-oestrogen effect on the mammary gland. The aim of this study was to evaluate the adverse effects when exposing healthy female dogs to tamoxifen.MethodsTamoxifen was administered for 120 days at a dose of 0.5 or 0.8 mg/kg/day to either intact or spayed female dogs. The effects were assessed through clinical examination, haematology, serum biochemistry, ophthalmology and bone marrow aspirate examination. Ovariohysterectomy was performed and the uterus examined by histopathology.ResultsVulva oedema and purulent vaginal discharge developed with 10 days of tamoxifen exposure in all groups. Pyometra was diagnosed after around 90 days of exposure in intact females with frequencies increasing during the following 30 days of exposure. Up to 50% of dogs within the groups developed retinitis but none of the dogs had signs of reduced visual acuity. The prevalence of retinitis in each group was similar after 120 days of exposure. Haematological, biochemical and bone marrow changes were not observed. Due to the high risk of developing pyometra after prolonged exposure to tamoxifen, only spayed animals should be given this medication.ConclusionsA dose of 0.8 mg tamoxifen/kg body weight/day is recommended when treating tamoxifen-responsive canine mammary tumors. Due to the high risk of developing pyometra, ovariohysterectomy is recommended.