Hematotoxicity of bacillus thuringiensis as spore-crystal strains cry1aa, cry1ab, cry1ac or cry2aa in swiss albino mice

Formulated and sporulated cultures of Bacillus thuringiensis (Bt) have been widely used against insect pests, but after the advent of genetically modified plants expressing δ-endotoxins, the bioavailability of Cry proteins has been increased. For biosafety reasons their adverse effects should be studied, mainly for non-target organisms. Thus, we evaluated, in Swiss albino mice, the hematotoxicity and genotoxicity of four Bt spore-crystals genetically modified to express individually Cry1Aa, Cry1Ab, Cry1Ac or Cry2A, administered alone by gavage with a single dose of 27 mg/ Kg, 136 mg/Kg or 270 mg/Kg, 24 h, 72 h or 7 days before euthanasia. Binary combinations of these four spore-crystal proteins were also assayed at 270 mg/Kg with a single administration 24 h before euthanasia. Control mice received filtered water or cyclophosphamide at 27 mg/kg. For hematotoxicity evaluations, blood samples were drawn by cardiac puncture and processed in a multiple automated hematology analyzer; for genotoxicity analyses, micronucleus test was carried out in mice bone marrow cells. Spore-crystal administrations provoked selective hematotoxicity for the 3 exposure times, particularly for erythroid lineage. A significant reduction in bone marrow cell proliferation demonstrated cytotoxic but not genotoxic effects. These effects persisted for all exposure times, becoming more evident at 7 days. Similar results were observed for binary combinations at 24 h, suggesting that further studies are required to clarify the mechanism involved in the hematotoxicity found in mice, and to establish the toxicological risks to non-target organisms, especially mammals, before concluding that these microbiological control agents are safe for mammals

Antitumor activity of photodynamic therapy performed with nanospheres containing zinc-phthalocyanine

Abstract\ud \ud Background\ud The increasing incidence of cancer and the search for more effective therapies with minimal collateral effects have prompted studies to find alternative new treatments. Among these, photodynamic therapy (PDT) has been proposed as a very promising new modality in cancer treatment with the lowest rates of side effects, revealing itself to be particularly successful when the photosensitizer is associated with nanoscaled carriers. This study aimed to design and develop a new formulation based on albumin nanospheres containing zinc-phthalocyanine tetrasulfonate (ZnPcS4-AN) for use in the PDT protocol and to investigate its antitumor activity in Swiss albino mice using the Ehrlich solid tumor as an experimental model for breast cancer.\ud \ud \ud Methods\ud Ehrlich tumor’s volume, histopathology and morphometry were used to assess the efficacy of intratumoral injection of ZnPcS4-AN in containing tumor aggressiveness and promoting its regression, while the toxicity of possible treatments was assessed by animal weight, morphological analysis of the liver and kidneys, hemogram, and serum levels of total bilirubin, direct bilirubin, indirect bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma glutamyl transferase (GGT), alkaline phosphatase, creatinine and urea. In order to evaluate the efficacy of PDT, groups of animals treated with intratumoral injection of doxorubicin (Dox) were also investigated.\ud \ud \ud Results\ud Intratumoral injection of ZnPcS4-AN was found to be efficient in mediating PDT to refrain tumor aggressiveness and to induce its regression. Although tumor volume reduction was not significant, PDT induced a remarkable increase in the necrosis area seen in the tumor’s central region, as in other experimental groups, including tumor and Dox treated groups, but also in the tumor’s peripheral region. Further, PDT showed minimal adverse effects. Indeed, the use of ZnPcS4-AN in mediating PDT revealed anti-neoplastic activity similar to that obtained while using intratumoral Dox therapy.\ud \ud \ud Conclusions\ud PDT mediated by the new formulation ZnPcS4-AN enhanced the inhibition of tumor growth while producing practically no adverse effects and thus emerges as a very promising nanotechnology-based strategy for solid cancer treatment.We are grateful to the Sabin Institute/Sabin Laboratories for technical\ud support and to the Brazilian National Council for Technological and Scientific\ud Development (CNPq), the Foundation to Support Research in the Federal\ud District (FAPDF), the Coordination for Further Training of Graduate Staff\ud (CAPES), the Nanobiotechnology-Network CON-NANO (CAPES), INCTNanobiotecnologia\ud (MCTI, CNPq, CAPES), CNANO-UnB, the São Paulo\ud Research Foundation (FAPESP) #08/53719-4 ACT, and the DPP-University of\ud Brasília, for financial support

Síndrome de Torsades de Pointes: análise de casos: Torsades de Pointes Syndrome: case analysis

A Síndrome de Torsades de Pointes (TdP) é uma taquiarritmia ventricular polimórfica de pacientes com um intervalo QT longo congênito ou induzido por fármacos, cujo eletrocardiograma possui aspecto de “torção das pontas” e os sinais e sintomas característicos são síncope, palpitação ou mesmo evolução para fibrilação ventricular e morte súbita. O sexo mais frequentemente acometido é o feminino, o diagnóstico se baseia no eletrocardiograma e o tratamento preconizado é o sulfato de magnésio (MgSO4) intravenoso, a correção dos distúrbios eletrolíticos, principalmente a hipocalemia e o tratamento da causa base, na TdP farmacoinduzida. O objetivo do estudo é analisar os casos de Síndrome de Torsades de Pointes em pacientes com alterações do intervalo QT no eletrocardiograma. Trata-se de uma revisão bibliográfica integrativa, do tipo quantitativa, que utilizou as plataformas do PubMed, SciELO e Cochrane Library como bases de dados para seleção dos artigos, todos na língua inglesa. Foram utilizadas literaturas publicadas com recorte temporal de 2017 a 2022. De acordo com as literaturas analisadas, conclui-se que a TdP é uma taquiarritmia ventricular polimórfica com um mau prognóstico se não tratada precocemente com o MgSO4 intravenoso e, por ter diversas etiologias, é primordial que o diagnóstico preciso seja estabelecido de forma rápida, devido ao alto índice de mortalidade. Pacientes portadores da síndrome do QT longo congênita, bradicardia sinusal e bloqueio atrioventricular de 1º grau possuem predisposição para o desenvolvimento de TdP. Observa-se escassez na literatura a respeito das formas adequadas de prevenção da TdP, já que muitos pacientes que participam das triagens, muitas das vezes inefetivas, adquirem a síndrome após o uso de drogas que a predispõem, com prolongamento do intervalo QT, ou não sabem que possuem uma SQTL pré-existente, obrigatória para o desenvolvimento da TdP

O uso de nanoesferas de albumina na terapia fotodinâmica e magnetohipertermia do tumor de Ehrlich

Tese (doutorado)—Universidade de Brasília, Faculdade de Medicina, 2011.O aumento crescente da incidência de câncer e a necessidade de se desenvolver terapias mais eficazes com o mínimo de efeitos adversos têm suscitado a busca de tratamentos alternativos. Entre estes, duas terapias promissoras são a magnetohipertermia (MHT) e a terapia fotodinâmica (TFD), as quais podem proporcionar ainda maior eficácia se realizadas com materiais nanoestruturados. O presente trabalho teve o objetivo de, utilizando modelos de tumor sólido de Ehrlich, verificar a atividade antitumoral de duas amostras à base de nanoesferas de albumina: (1) amostra contendo nanopartículas magnéticas à base de maghemita (PAM) usadas na concentração de 1,2 × 1015 partículas magnéticas/mL foi testada para MHT de tumores localizados na cabeça após administração de 5,5 × 104 células tumorais e (2) amostra contendo 0,5 mM zinco-ftalocianina tetrassulfonada (PAF) para TFD na orelha após administração de 2,75 x 104 células tumorais. PAM e PAF foram usadas, respectivamente, em diferentes protocolos de MHT e TFD. MHT foi feita com equipamento operando a 1 MHz e 40 Oe de amplitude de campo e foram realizadas análises histológicas do tumor para verificar o grau de necrose. As análises mostraram que dois dos animais submetidos à MHT duas vezes ao dia, durante três dias consecutivos, apresentaram 100% de necrose e ausência de proliferação celular. Para a realização da TFD foi usado luz laser com comprimento de onda de 670 nm e animais distribuídos em três grupos experimentais. A avaliação dos procedimentos foi feita por observações clínicas (peso do animal, peso e volume do tumor), testes hematológicos e bioquímicos, análise morfológica, tanto do fígado, quanto dos rins para avaliar possíveis alterações teciduais, e análises morfométricas do tumor para avaliar o grau de necrose obtido. Para validar os experimentos de TFD, grupos tratados com o quimioterápico doxorrubicina (Dox) foram investigados. Os resultados mostraram que a TFD, quando realizada de três em três dias durante nove dias experimentais induziu necrose equiparável ao do tratamento com Dox, com menos efeitos adversos, sobretudo no fígado; Já os tratamentos combinados com TFD e Dox não apresentaram efeitos sinérgico ou antagônico. Em geral, os melhores protocolos de MHT e TFD levaram a pelo menos 60% de necrose. Conclui-se que as nanoesferas de albumina, além de altamente biocompatíveis, representam material nanoestruturado eficaz na realização da MHT e TFD que, embora nem sempre tenham causado a remissão total do tumor, revelaram significativa atividade antiproliferativa, apresentando alto potencial para tratamento do câncer. _______________________________________________________________________________ ABSTRACTThe increasing incidence of cancer and the need to develop more effective therapies with minimal collateral effects have prompted the search for alternative treatments. Among these, two promising therapies are magnetohyperthermia (MHT) and photodynamic therapy (PDT), which can be even more efficient if performed with nanostructured materials. The present work was aimed to investigate the antitumor activity of two samples based on albumin nanospheres: one containing magnetic nanoparticles (PAM) and another containing zinc-phthalocyanine tetrasulfonated (PAF) while using the model of Ehrlich solid tumor (head for MHT and ear for PDT). PAM and PAF were used in different protocols of MHT and PDT, respectively. MHT was performed with the equipment operating at 1 MHz and 40 Oe, while PDT have used light source at 670nm. The evaluation of both procedures was made by clinical observations (weight of animal, weight, volume, and size of tumor), cytometry, haematological, and biochemical tests, and morphological analysis of the liver and kidney tissue to evaluate possible changes, and also morphology of tumor to assess the degree of necrosis induced. Two animals submitted to MHT showed 100% necrosis. In general, the best protocols of MHT and PDT led to at least 60% necrosis. To validate the PDT experiments, groups treated with the chemotherapeutic agent doxorubicin (Dox) were investigated. PDT and Dox induced comparable necrosis. PDT showed fewer side effects than Dox. PDT and Dox showed no synergistic or antagonistic effect. We conclude that the highly biocompatible albumin nanospheres represent nanostructured material efficient in performing the MHT and PDT procedures. Though they not caused total remission of the tumor, they showed significant antiproliferative activity evidencing a high potential for cancer treatment

Avaliação da biocompatibilidade de fluido magnético à base de nanopartículas de maghemita recobertas por polifosfato em camundongos

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Medicina, 2007.A nanotecnologia representa, atualmente, uma área de interesse crescente. Dentre os materiais nanoestruturados que vêm sendo desenvolvidas, as nanopartículas magnéticas (NPM) surgem como proposta promissora para várias aplicações na área biomédica como, por exemplo, magnetohipertermia para tratamentos de tumores, entrega de drogas alvo-específico, agente de contraste para a imagem por ressonância magnética. Considerando a necessidade de testar novos materiais antes de seu emprego clínico, o presente trabalho tem como objetivo avaliar a biocompatibilidade (toxicidade e genotoxicidade) de fluido magnético à base de nanopartículas de maghemita recobertas com polifosfato (FMF), em duas concentrações diferentes (0,7×1015 partículas em 50μL nomeada FMF-1 e 1,4×1015 partículas em 100μL, a FMF-2), por meio de testes de viabilidade de células peritoneais, citometria de sangue periférico, ensaio de micronúcleo (MN) e análise morfológica, em camundongos fêmeas Swiss. A amostra FMF, no período que abrangeu de 30 minutos a sete dias, não afetou a viabilidade de células peritoneais, apresentou brando e temporário processo inflamatório (análise citométrica), ausência de genotoxicidade e baixa citotoxicidade nas células da medula óssea (ensaio de MN). Estudos morfológicos revelaram, em microscópio de luz, a presença de aglomerados de NPM nos três órgãos analisados (pulmão, fígado e baço). Ainda assim, não foram observadas alterações morfológicas no baço, e apenas ligeiro infiltrado celular no fígado (também observado nos controles) e pulmão, órgão em que também foi encontrado espessamento temporário dos septos alveolares. A toxicidade induzida pela amostra FMF é tempo e dose dependente. Os resultados obtidos permitem concluir que FMF possui biocompatibilidade adequada para aplicações biomédicas, como magnetohipertermia e sistemas entregadores de drogas. _____________________________________________________________________________________ ABSTRACTNowadays, nanotechnology represents a broad area of increasing interest. Several kinds of nanostructured materials have been synthesized. Among them magnetic nanoparticles (MNPs) represent a promising class to be used in several biomedical applications, such as magnetohyperthermia for tumor therapy, target-specific drug delivery, and contrast agents for magnetic resonance images. New materials have to be pre-clinical tested before they can be used for clinical trials. Therefore, the aim of this work was to evaluate the biocompatibility (toxicity and genotoxicity) of a new magnetic sample based on maghemite nanoparticles coated with polyphosphate (FMF), using two different concentrations (0.7×1015 particle in 50μL named FMF-1 and 1.4×1015 particle in 100μL named FMF-2). FMF sample was tested using female Swiss mice through viability of peritoneal cells, cytometry of blood cells, micronucleus assay (MN), and morphological analysis. FMF sample effects were investigated from 30 minutes until 7 days after the administration. The viability of peritoneal cells was not affected. Light and temporary inflammatory process (cytometry analysis), absence of genotoxicity, and a slight cytotoxicity of bone marrow cells (MN assay) were found. Morphological studies performed under light microscope showed the presence of MNP clusters in three investigated organs: liver, lung, and spleen. Nevertheless, despite the observation of MNP clusters, no morphological alterations were found in the spleen, and only a slight cell infiltration was found in the liver (also observed in the control animals) and lungs. In was also found in the lungs a temporary alveolar septum enlargement. All the toxicity effects of FMF are time and doses dependent. The results allow concluding that the FMF sample presents biocompatibility adequate to be used in biomedical applications, such as magnetohyperthermia and drug delivery systems