Hepatic toxicity caused by PLGA-microspheres containing usnic acid from the lichen C ladonia substellata (AHTI) during pregnancy in Wistar rats

ABSTRACT This study aimed to evaluate the teratogenic and hepatotoxic potential of the usnic acid encapsulated into PLGA-microspheres. In total, 12 female Wistar rats in pregnancy were randomly distributed in the control group (n= 6) that received 1.0 mL of physiological solution and treatment group (n= 6) that received 25 mg/kg of encapsulated usnic acid by oral administration. All females were euthanized at day 20 of pregnancy and their fetuses were removed and analyzed. During the pregnancy was observed a reduction in weight gain. There was no difference in serum transaminases levels analyzed as well as any difference in liver weight in both groups. The histomorphometric analysis of the liver from the treatment group revealed an increase in number of hepatocytes and a decrease in nuclear area of these cells. Moreover, no alteration was observed in cell area of hepatocytes or number of Kupffer cells. The fetuses had an increase in total number of hepatocytes and a reduction in the amount of megakaryocytes. These results show the hepatotoxic potential of usnic acid during pregnancy. However, its toxicity can be minimized by encapsulation in microspheres.

Engenharia tecidual dos biomateriais / Scaffolds in tissue engineering bone

Este trabalho visualiza os materiais usados em contato com os tecidos vivos que têm finalidade de restaurar ou substituir parte do organismo danificado. Dentre muitas indicações os biomateriais são recomendados nos reparos peri-implantares. Os biomateriais são classificados em conformidade com a sua origem, mecanismo de ação e comportamento fisiológico. Assim podem ser metálicos, cerâmicos ou polímeros e interagem como inertes bioativos ou reabsorvíveis. Entres os cerâmicos foi descrito a hidroxiapatita que devido a sua similaridade com o tecido ósseo é considerada um dos materiais mais biocompatíveis conhecidos favorecendo a proliferação de fibroblastos, osteoblastos e outras células ósseas. A hidroxiapatita sintética possui propriedades de osteointegração o que a torna substituta do osso humano em implantes dentários. As membranas são derivadas de polímeros e podem ser classificadas de absorvíveis quando produzidas do ácido polilático e poliglicólico e de não absorvíveis quando produzida em politetrafluoretileno. Ácido poliglicólico (PGA) exibe boas propriedades mecânicas e seu principal uso é como material de suporte. A habilidade de controlar o tamanho do poro no arcabouço permite usá-lo como um parâmetro importante para ser aplicado na bioengenharia tecidual. O poli L-ácido láctico (PLLA) derivado do ácido láctico possui alta resistência, comportamento termoplástico, biocompatibilidade, sensibilidade à água, visto que se degradam lentamente comparado com os polímeros solúveis que incham na água. O copolímero PLGA requerer um menor tempo para sua completa degradação, sua estrutura química é mais suscetível à reação de hidrólise, já que em sua cadeia polimérica existe o mero proveniente do ácido glicólico, que possui um impedimento menor ao ataque das moléculas de H2O...

This paper visualizes materials used in contact with live tissues to restore or replace a part of the damaged organism. Among the many indications, biomaterials are recommended for periimplant repairs, and classified according to their origin, action mechanism and physiological behavior. Thus, they can be metallic, ceramic or polymeric and interact as inert bioactive or resorbable ones. Similar to the osseous tissue, hydroxyapatite which favors the proliferation of fibroblasts, osteoblasts and other osseous cells is described and considered one of the most bio-compatible materials, among the ceramic ones. Synthetic hydroxyapatite presents osteointegration properties; therefore, it is a substitute for the human bone, in dental implants. Membranes derive from polymers and can be classified as resorbable when produced out of polylactic and polyglycolic acids, and as nonresorbable, when produced in polytetrafluoretilene. The polyglycolic acid (PGA), exhibits good mechanical properties and is mainly used as a support material. The ability to control the size of the pore in the framework allows one to use it as an important.

The construction and investigation of PLGA artificial bone by biomimetic mineralization / 华中科技大学学报（医学）（英德文版）

To modify the surface property of poly lactide-co-glycolide (PLGA) by biomimetic mineralization to construct a new kind of artificial bone. PLGA films and 3-diamensional (3-D) porous scaffolds hydrolyzed in alkaline solution were minerilized in SBF for 14 days. The morphology and composition of the mineral grown on PLGA were analyzed with SEM, FTIR and XRD. The porosity of the scaffolds was detected by using the liquid displacement method. The compressive strength of the scaffolds was detected by using a Shimadzu universal mechanic tester. An obvious mineral coating was detected on the surface of films and scaffolds. The main component of the mineral was carbonated hydroxyapatite (HA) similar to the major mineral component of bone tissues. The porosity of the un-mineralized and mineralized porous scaffolds was (84.86 +/- 8.52) % and (79.70 +/- 7.70) % respectively. The compressive strength was 0.784 +/- 0.156 N/mm2 in un-mineralized 3-D porous PLGA and 0.858 +/- 0.145 N/mm2 in mineralized 3-D porous PLGA. There were no significant differences between the mineralized and un-mineralized scaffolds (P > 0.05) in porosity and biomechanics. Biomimetic mineralization is a suitable method to construct artificial bone.

Comparación entre fijación metálica y reabsorbible sobre el crecimiento craneofacial: Estudio en conejos / Comparison between metallic and resorbable internal fixation over craniofacial growth. A study in rabbits

Se realizó un estudio longitudinal retrospectivo con un diseño experimental, cuyo objetivo fue comparar la influencia de la fijación rígida metálica y reabsorbible sobre el crecimiento óseo craneofacial. La muestra estuvo conformada por 10 conejos blancos neozelandeses de dos meses de edad. Exponiendo la sutura frontoparietal, se colocó al lado derecho una placa de material reabsorbible (Lactosorb, Walter Lorenz Surgical) de dos agujeros en sitema 1,5mm con tornillos de 3mm de longitud, y al lado izquierdo se colocó una placa metálica (Titanium, Walter Lorenz Surgical) de dos agujeros en sistema 1,5mm con tornillos de 3mm de longitud. Se instalaron marcadores de titanio a una distancia de 13mm. Se obtuvieron especímenes a los 2, 6, 9 y 12 meses., evaluando el crecimiento óseo. Se observaron los resultados clínicos e histológicos, concluyendo que el sistema reabsorbible se mantuvo sin cambios durante el tiempo suficiente para la consolidación de una fractura facial y luego se reabsorbió lentamente sin afectar el crecimiento óseo

Regeneración ósea guiada de cara al año 2000. Consideraciones clínicas y biológicas / Guided bone regeneration facing the year 2000. Clinical and biologic considerations

La regeneración ósea guiada representa hoy una de las terapias de mayor éxito para el manejo conjunto a la colocación de implantes. Durante los últimos años el uso de membranas para la regeneración ósea ha ido combinada desde membranas no reabsorbibles hasta membranas reabsorbibles. El presente artículo pretende mostrar a fondo los diferentes tipos de membranas que se tienen en el mercado, así como los resultados mostrados con el uso de las mismas. Asimismo, se hace un ligero repaso de las indicaciones para la regeneración ósea guiada y las propiedades que debe tener una membrana para poder ser utilizada en la regeneración ósea guiada