Nanogels as prospective Biomaterial: Radio-induced Synthesis, Characterization, and Biological Assays / Los nanogeles como biomateriales prospectivos: síntesis radioinducida, caracterización y ensayos biológicos

Nowadays, there is a growing interest in biodegradable polymers-based materials due to their diverse application in the biomedical field. Most studied systems involve biocompatible micro and nanodevices, such as liposomes, dendrimer, micelles or polymeric nanogels. The use of Radiation Technology, specifically gamma radiation, to produce micro and nanogels raises the possibility to obtain higher purity products, an important feature for biomedical and pharmaceutical applications. The radio-induced synthesis, characterization, cytotoxicity evaluation, and immunological response of nanogels are described in this study. Nanogel synthesis was performed in the absence of oxygen using aqueous polyvinylpyrrolidone solutions. Crosslinking reactions were carried out at 25 °C in a gamma irradiation chamber with a 60Co source. Nanogels properties were analysed by Scanning Electron Microscopy, Attenuated Total Reflection-Fourier Transform Spectroscopy, Dynamic Light Scattering, and Viscosimetry. The cytotoxicity and immunological response were evaluated by MTT test and analysis of the neutrophil respiratory burst. The results showed that nanogels formation strongly depends on the total absorbed dose. The nanogels have an elliptical shape and their chemical structure is similar to the initial polymer. The nanogels are biocompatible and promote a low-intensity neutrophil activation, similar to the well-characterized biomaterial TiO2, suggesting their potential biomedical uses(AU)

En la actualidad existe un interés creciente en los materiales biodegradables basados en polímeros, debido a sus diversas aplicaciones en la esfera de la biomedicina. En la mayoría de los sistemas estudiados participan micro- y nanodispositivos biocompatibles, tales como liposomas, dendrímeros, micelas o nanogeles poliméricos. El uso de la tecnología de radiaciones, en particular de radiaciones gamma, para producir micro- y nanogeles, eleva la posibilidad de obtener productos de mayor pureza, un rasgo importante con vistas a su aplicación biomédica y farmacéutica. El estudio describe la síntesis radioinducida, caracterización, evaluación de la citotoxicidad y respuesta inmunológica de los nanogeles. La síntesis de los nanogeles se realizó en ausencia de oxígeno, usando soluciones acuosas de polivinilpirrolidona. Las reacciones de entrecruzamiento se realizaron a 25 ºC en cámara de irradiación gamma con una fuente de 60Co. Las propiedades de los nanogeles se analizaron mediante microscopía electrónica de barrido, espectroscopia por transformada de Fourier total atenuada, dispersión dinámica de luz y viscosimetría. La citotoxicidad y la respuesta inmunológica se evaluaron mediante prueba MTT y análisis del estallido respiratorio de neutrófilos. Los resultados muestran que la formación de nanogeles depende en gran medida de la dosis total absorbida. Los nanogeles tienen forma elíptica y su estructura química es similar a la del polímero inicial. Los nanogeles son biocompatibles y promueven una activación de neutrófilos de baja intensidad similar al bien caracterizado material TiO2, lo que sugiere usos biomédicos potenciales(AU)

Gamma radiation treatment applied to microbial decontamination of products derived from eggs collected from the retail market in São Paulo / Tratamento por radiação gama aplicado na descontaminação microbiana de produtos derivados de ovos coletados no mercado varejista da cidade de São Paulo

The quality of products derived from eggs depends on the quality of the raw material source and the industrial production. The contamination by fungi and bacteria can occur after exposure of the product in the retail market. The objective of this study was to evaluate the microbiological quality of 60 samples of derivated egg products and evaluate the effects of gamma radiation of cobalt-60, using the dose of 5 and 10 kGy, for decontamination of products collected in the retail market in the São Paulo city. The bacterial count was performed by the most probable number (MPN) and the fungal counts by serial dilution after plating surface. It was observed a decrease in the humidity and water activity (Aw) values of irradiated whole egg powder and white egg powder samples (p<0.05), but there was no significant change in the pH of the same samples irradiated with 5 and 10 kGy (p>0.05). In the powdered yolk the values of pH and Aw presented a significant difference (p<0.05), but no significant difference in the humidity values of 5 and 10 kGy irradiated samples (p>0.05). Effective microbial sterilization of all products occurred at the dose of 10 kGy.(AU)

A qualidade dos produtos derivados de ovos depende da qualidade da matéria-prima e da produção industrial. A contaminação por fungos e bactérias pode ocorrer após a exposição do produto no mercado varejista. O objetivo deste estudo foi avaliar a qualidade microbiológica de 60 amostras de derivados de ovos e avaliar os efeitos da radiação gama de cobalto-60, utilizando-se as doses de 5 e 10 kGy, para descontaminação dos produtos coletados no mercado varejista da cidade de São Paulo. A contagem bacteriana foi realizada pelo número mais provável (MPN), e as contagens fúngicas por diluição seriada em plaqueamento de superfície. Foi observada uma diminuição dos valores da umidade e da atividade de água (Aa) das amostras irradiadas de ovo integral em pó e clara em pó (p<0,05), mas sem alteração significativa do pH nas mesmas amostras irradiadas com 5 e 10 kGy (p>0,05). Em gema em pó, observou-se diferença significativa (p<0,05) nos valores de pH e Aa, mas não houve mudança expressiva nos valores de umidade nas amostras irradiadas com 5 e 10 kGy (p>0,05). A esterilização microbiana eficaz de todos os produtos ocorreu com a dose de 10 kGy.(AU)

Sterilizing elastomeric chains without losing mechanical properties. Is it possible?

OBJECTIVE: To investigate the effects of different sterilization/disinfection methods on the mechanical properties of orthodontic elastomeric chains. METHODS: Segments of elastomeric chains with 5 links each were sent for sterilization by cobalt 60 (Co60) (20 KGy) gamma ray technology. After the procedure, the elastomeric chains were contaminated with clinical samples of Streptococcus mutans. Subsequently, the elastomeric chains were submitted to sterilization/disinfection tests carried out by means of different methods, forming six study groups, as follows: Group 1 (control - without contamination), Group 2 (70°GL alcohol), Group 3 (autoclave), Group 4 (ultraviolet), Group 5 (peracetic acid) and Group 6 (glutaraldehyde). After sterilization/disinfection, the effectiveness of these methods, by Colony forming units per mL (CFU/mL), and the mechanical properties of the material were assessed. Student's t-test was used to assess the number of CFUs while ANOVA and Tukey's test were used to assess elastic strength. RESULTS: Ultraviolet treatment was not completely effective for sterilization. No loss of mechanical properties occurred with the use of the different sterilization methods (p > 0.05). CONCLUSION: Biological control of elastomeric chains does not affect their mechanical properties. .

OBJETIVO: verificar os efeitos de diferentes métodos de esterilização/desinfecção nas propriedades mecânicas de elásticos ortodônticos em cadeia. MÉTODOS: segmentos de elástico em cadeia com 5 elos cada foram enviados para esterilização em radiação gama com cobalto 60 (20 KGy). Após esterilização, esses foram contaminados com amostras clínicas de Streptococcus mutans. Passado esse período, foram submetidos aos testes de esterilização/desinfecção por diferentes métodos, formando seis grupos de estudo, assim denominados: Grupo 1 (controle - sem ter sido contaminado), Grupo 2 (álcool 70°GL), Grupo 3 (autoclave), Grupo 4 (ultravioleta), Grupo 5 (ácido peracético) e Grupo 6 (glutaraldeído). Após esterilização/desinfecção, avaliou-se a efetividade desses métodos, por meio de contagem de unidades formadoras de colônias por mL (UFC/mL), e as propriedades mecânicas desses materiais. Utilizou-se o teste t de Student para avaliar o número de UFC, além do ANOVA e, posteriormente, do teste de Tukey para avaliação da força. RESULTADOS: verificou-se que o ultravioleta não obteve eficácia total quanto à esterilização. E não ocorreu perda das propriedades mecânicas dos elásticos, com os diferentes métodos de esterilização utilizados (p > 0,05). CONCLUSÃO: o controle biológico de elásticos em cadeia não interfere nas suas propriedades mecânicas. .

Tratamiento de quemaduras con películas obtenidas por radiación gamma que contienen extracto hidroalcohólico de tara (Caesalpinia spinosa) en animales de experimentación / Treatment of burns wound with films obtained by gamma radiation containing Caesalpinia spinosa in rabbits

Objetivo. Evaluar el efecto cicatrizante de hidrogeles obtenidos con radiación gamma embebidos con extracto hidroalcohólico de tara (Caesalpinia spinosa). Material y métodos. Se fabricaron hidrogeles de quitosano-alcohol polivinílico embebidos en extracto hidroalcohólico de tara (Q-APVEHAT), que se aplicaron sobre quemaduras en piel de conejas, para evaluar su capacidad cicatrizante frente al hidrogel solo, al extracto solo y nitrofural. La cicatrización de las heridas fue evaluada macroscópicamente y microscópicamente (biopsias) y con la medición del área y el porcentaje de retracción de la quemadura. La evaluación se realizó a los 7, 14 y 21 días posquemadura. Resultados. El día 7 de tratamiento se apreció diferencia estadísticamente significativa para el área de las heridas de los grupos (p =0,002). El área de las heridas tratadas con Q-APV-EHAT fue significativamente menor que la tratada con nitrofural (p = 0,001). Para el día 14, no hubo diferencia estadísticamente significativa entre los tratamientos (p = 0,063). Para el día 21 existió diferencia estadísticamente significativa entre tratamientos (p = 0,005), la piel tratada con Q-APV-EHAT tuvo significativamente menor área que la tratada connitrofural (p = 0,005) y la piel tratada con extracto de tara, significativamente menor área que la tratada con nitrofural (p = 0,033). La mayor retracción de las heridas, confirmada por microscopía se obtuvo con el Q-APV-EHAT tanto a los 7, 14 y 21 días de tratamiento. Conclusión. El hidrogel de quitosano-alcohol polivinílico embebido en extracto hidroalcohólico de tara mostró significativamente mayor actividad cicatrizante que el extracto hidroalcohólico de tara solo, las películas de quitosano (sin extracto de tara) y el nitrofural.

Objective. Evaluate the healing effect of hydrogels obtained by gamma radiation imbibed with hydroalcoholic extract of Caesalpinia spinosa, ætaraÆ in experimental animals. Material and methods. Experimental study. Hydroalcoholic extracts, chitosan-poly (vinyl alcohol) hydrogels films imbibed with hydroalcoholic extract of C. spinosa (HA-Q-CS) were made. This hydrogel was applied on burns in female rabbitÆs skin to evaluate its healing effects versus hydrogel alone, C. spinosa extract and nitrofural. Healing of wounds was evaluated, macroscopically a microscopically (biopsies) as well the evaluation of the area and percent of burn retraction. The evaluations were performed on days 7, 14 and 21 post burned. Results. At the day 7 of treatment, a significant statistic difference was observed for the burns area of the groups (p = 0,002). The area of wounds treated with HA-Q-CS was significantly lower than those treated with nitrofural (p = 0,001). On day 14 there was no significant statistic difference between groups (p = 0,063). On day 21 there was a significant statistic difference between treatments (p = 0,005), the skin treated with HA-Q-CS had an area significantly lower than the treated with furacin (p = 0,005); Also, the skin treated with ET hada significantly lower area than the skin treated with nitrofural (p =0,033). The major wounds retraction confirmed with the microscopy was obtained with HA-Q-CS at the day 7, 14 and 21 of treatment. Conclusion. HA-Q-CS showed a significantly major effect than the hdrialcoholic extract of C. spinosa alone, the chitosan-poly vinylalcohol (without C. spinosa) and the nitrofural.

Study of irradiated bothropstoxin-1 with60Co gamma rays: immune system behavior

Ionizing radiation has been successfully employed to modify the immunological properties of biomolecules. Very promising results were obtained when crude animal venoms, as well as isolated toxins, were treated with 60Co gamma rays, yielding toxoids with good immunogenicity. The achievement of modified antigens with lower toxicity and preserved or improved immunogenicity can be very useful. Ionizing radiation has already been proven to be a powerful tool to attenuate snake venom toxicity without affecting, and even increasing, their immunogenic properties. However, little is known about the modifications that irradiated molecules undergo and even less about the immunological response that such antigens elicit. In the present work, we investigated the immunological behavior of bothropstoxin-1, a K49 phospholipase, before and after irradiation. Structural modifications of the toxin were analyzed by SDS-PAGE. Isogenic mice were immunized with either the native or the irradiated toxin. The circulating antibodies were isotyped and titrated by ELISA. According to our data, irradiation promoted structural modifications in the toxin characterized by higher molecular weight forms of proteins (aggregates and oligomers). The results also indicated that irradiated toxins were immunogenic and antibodies elicited by them were able to recognize the native toxin in ELISA. These findings suggest that irradiation of toxic proteins can promote significant modifications in their structures; however they still retain many of the original antigenic and immunological properties of native proteins. Also, our data indicate that irradiated proteins induce higher titers of IgG2a and IgG2b, suggesting that Th1 cells are predominantly involved in the immune response.

Estudo sobre a eventual utilidade de raios gama na profilaxia da malária transmissível por transfusão de sangue / Utility of gamma rays in prophylaxis of transmissible malaria by blood transfusion

This study was carried out to evaluate the fortuitons advantage of using gamma irradiation in the prophylaxis of transmissible malaria by blood transfusion, with mice as the experimental model. In the first step, when the infected blood with Plasmodium berghei was submitted to 2,500 rad and 5,000 rad, with or without metronidazol, there was no success, because the animals presented parasitaemia and died after inoculation of irradiated blood. However, there was partial success in the second step, when the infected blood received 10,000 and 15,000 rad, and was inoculated in mice, which showed infection, and presented a survival rate of 20% and 40%, respectively, with later negativation of blood infected by P. berghei.

O estudo foi realizado com o objetivo de avaliar a eventual utilidade de raios gama na profilaxia da malária transmissível por transfusão de sangue, tendo sido, para isso, usados camundongos infectados pelo Plasmodium berghei. Na primeira fase, quando submetemos sangue deles retirado a 2.500 e 5.000rad, com associação ou não de metronidazol, não obtivemos sucesso, já que todos os animais antes sem a parasitose apresentaram parasitemia e morreram após inoculação do sangue irradiado. Porém, ocorreu êxito parcial na segunda fase, ao serem empregados 10.000 e 15.000rad, porquanto 20% e 40% dos roedores, respectivamente, embora tenham ficado infectados, sobreviveram, com posterior negativação quanto à presença do P. berghei.

Estudo sobre a eventual utilidade de raios gama na profilaxia da malária transmissível por transfusäo de sangue / Study to evaluate the utilization of gamma irradiation in the prophylaxis of transmissible malaria by blood transfusion

O estudo foi realizado com o objetivo de avaliar a eventual utilidade de raios gama na profilaxia da malária transmissísel por transfusäo de sangue, tendo sido, para isso, usados camundongos infectados pelo Plasmodium berghei. Na primeira fase, quando submetemos sangue deles retirado a 2.500 e 5.000 rad, com associaçäo ou näo de metronidazol, näo obtivemos sucesso, já que todos os animais antes sem a parasitose apresentaram parasitemia e morreram após inoculaçäo do sangue irradiado. Porém, ocorreu êxito parcial na segunda fase, ao serem empregados 10.000 e 15.000 rad, porquanto 20 por cento e 40 por cento dos roedores, respectivamente, embora tenham ficado infectados, sobreviveram, com posterior negativaçäo quanto à presença do P. berghei.

Efecto de la irradiación gamma Co 60 sobre el metacestodo de Taenia solium / Effect of gamma Co 60 on Taenia solium metacestodes

Con el propósito de interrumpir el ciclo de la Taenia solium, se estudió el efecto de la irradiacción gamma sobre el metacestodo. Se irradiaron larvas con dosis de 0.5 t 0.7 KGy y de 4 a 11 KGy. Todas las larvas irradiadas con dosis a partir de 6.5 KGy murieron; la muerte fue confirmada por la ausencia de evaginación. Cuando se alimentaron hámsters dorados (Mesocricetus auratus) inmunosuprimidos con larvas irradiadas con 7.0 KGy no se desarrollaron tenias en su intestino a los 10 y 30 días posinoculación. Las dosis de 0.5 y 0.7 KGy no afectaron la capacidad de evaginación de la larva, pero evitaron la infección en el hámster. A cada uno de 10 hámsters se les inocularon 5 larvas irradiadas con 0.5 KGy; se recuperó 1 tenia corta a los 10 días y ninguna a los 30. A cada uno de 20 hámsters se les administraron por vía oral 5 larvas irradiadas con 0.7 KGy; se recuperaron tenias poco desarrolladas a los 10 días y ninguna a los 30 días. Se notaron diferencias individuales en la susceptibilidad de los hámster a la infección y también diferencias de la capacidad de infectar de los metacestodos procedentes de diferentes cerdos. Se discuten los resultados y se concluye que, con base en la inoculación en hámster de larvas irradiadas, una dosis de 0.7 KGy suprime la infectividad de las mismas

Uso da dura-máter homóloga conservada em cirurgia plástica ocular / Use of homologous preserved dura-mater in ocular plastic surgery

Os autores apresentam o emprego da dura-máter homóloga em cirurgia plástica ocular e apontam as vantagens do método de esterilizaçäo e conservaçäo em glicemia à temperatura ambiente. O tratamento com raios gama proporciona maior segurança quanto à esterilizaçäo, especialmente no que concerne à presença de vírus contaminantes. Face a grande aplicabilidade deste material criam um Banco de Dura-Mater para forncecimento a todos os serviços que venham a se interessar pelo seu uso