Oral Pharmacokinetics of a Chitosan-Based Nano- Drug Delivery System of Interferon Alpha.

Interferon alpha (IFNα) is a protein drug used to treat viral infections and cancer diseases. Due to its poor stability in the gastrointestinal tract, only parenteral administration ensures bioavailability, which is associated with severe side effects. We hypothesized that the nanoencapsulation of IFNα within nanoparticles of the mucoadhesive polysaccharide chitosan would improve the oral bioavailability of this drug. In this work, we produced IFNα-loaded chitosan nanoparticles by the ionotropic gelation method. Their hydrodynamic diameter, polydispersity index and concentration were characterized by dynamic light scattering and nanoparticle tracking analysis. After confirming their good cell compatibility in Caco-2 and WISH cells, the permeability of unmodified and poly(ethylene glycol) (PEG)-modified (PEGylated) nanoparticles was measured in monoculture (Caco-2) and co-culture (Caco-2/HT29-MTX) cell monolayers. Results indicated that the nanoparticles cross the intestinal epithelium mainly by the paracellular route. Finally, the study of the oral pharmacokinetics of nanoencapsulated IFNα in BalbC mice revealed two maxima and area-under-the-curve of 56.9 pg*h/mL.

Development of a Drug Delivery System Based on Chitosan Nanoparticles for Oral Administration of Interferon-α.

Despite the good clinical efficacy of interferon-alpha (IFNα) to treat some types of cancer and viral infections, this biological drug is underused given its severe adverse effects and high dosing parenteral regimens. Aiming to achieve a breakthrough in therapy with IFNα, this work reports for the first time on the design and full characterization of a novel nanomedicine of IFNα-2b-loaded chitosan nanoparticles (IFN-CT NPs) for oral delivery. IFN-CT NPs produced by ionotropic gelation, encapsulating approximately 100% of the drug, showed a size of 36 ± 8 nm, zeta potential of +30 mV (dynamic light scattering), and spherical morphology (transmission electron microscopy). The antiviral activity of IFN-CT NPs in vitro was comparable to that of commercial IFNα. Remarkably, both treatments stimulated the expression of IFN response genes to a similar extent in both noninfected and infected cells with Human Lymphotropic-T Virus type 1. Finally, oral administration of IFN-CT NPs (0.3 MIU) to CF1 mice showed detectable levels of IFNα in plasma after 1 h, whereas no IFNα was detected with a commercial formulation. These results are encouraging and open a new avenue for the administration of this biological drug in a minimally invasive, safer, and more patient-compliant way.

Long term bone alterations in aged rats suffering type 1 diabetes.

Increasing duration of type 1 diabetes mellitus alters bone metabolism. Clinical studies and experimental studies in long bones of rats with experimentally induced diabetes have reported a decrease in bone density. Few studies have explored this diabetes related alteration in the maxillae. Given that this finding could indicate the possible development of osteopenia in the maxilla in the long term, the present study sought to analyze alterations in alveolar bone in aged rats, 12, 18, and 24weeks after inducing diabetes, and compare alveolar bone response to that of tibial subchondral bone at the same experimental times. Thirty-six male Wistar rats, 130g body weight, were divided into 2 groups: an experimental group (E) receiving a single i.p. 60mg/kg dose of streptozotocin, and a control group (C). Both the control and experimental groups were divided into 3 sub-sets, according to the time of euthanasia: 12, 18 and 24weeks. The alveolar bone and tibiae were examined histologically and histomorphometrically. The results were analyzed using Student's t-test; a value of p<0.05 was considered statistically significant. RESULTS: Subchondral bone volume and bone activity/remodeling, mainly bone rest, were significantly lower in diabetic animals compared to controls, at both 12 and 18weeks. No differences in alveolar bone parameters were observed between diabetic and control animals at either of the experimental times. Animals surviving at 24weeks showed few trabeculae at rest and severe destruction of dental and periodontal tissues. The results of the present study show that diabetic osteopenia is evident in the tibia at 12 and at 18weeks, whereas its effects on the maxilla can be seen at 24weeks, with substantial destruction of alveolar bone and of the remaining periodontal and dental tissues. All the above observations highlight the need for preventive oral care in diabetic patients, before irreversible damage to dental and periodontal tissues occurs.

Histomorphometry of the tibia and mandible of healthy female Wistar rats at different stages of growth.

Female Wistar rats are frequently used in experimental models to study hormone and bone pathologies and treatments. Most experimental studies involving histomorphometric evaluation assessed long bones, and few reports also studied mandibular bone. The aim of this work was to clarify and distinguish the age-related histomorphometric changes that occur in the tibia (subchondral bone) and in the mandible (interradicular bone), and thus obtain reference histomorphometric data of healthy female Wistar rats at different growth stages. Three groups of 8 healthy female Wistar rats were euthanized at 6 (GI), 10 (GII), and 14 (GIII) weeks. The tibiae and mandible were resected and histologically processed to obtain H&E stained sections of the tibia and the lower first molar to analyze the following histomorphometric parameters: Bone volume, trabecular width, trabecular number (Th.N)(1/mm), growth cartilage width, hypertrophic cartilage width and number of osteoclasts per area in the tibiae, and bone volume and number of osteoclasts per area N.Oc/mm(2) in the interradicular bone of the first lower molar. A significant decrease in subchondral bone volume as a result of a decrease in trabecular number and growth cartilage width was observed in 14-week-old rats. Conversely, interradicular bone volume was found to increase with age. The results highlight the importance of analyzing both types of bone to better understand the response of two different trabecular bones, contributing in turn to decision making regarding treatment strategies and disease management.

Impairment of Bony Crypt Development Associated With Hexavalent Chromium Exposure During Tooth Eruption.

Improperly treated hexavalent chromium-containing industrial wastes contaminate drinking water, potentially affecting children taking breast milk or baby bottles prepared with infant formula. Thus, the aim of the present work was to determine the effect of this toxic on bone activity in the developing alveolus during tooth eruption of suckling Wistar rats intoxicated with potassium dichromate. Experimental animals received a daily dose of 12.5mg/kg body weight of potassium dichromate by gavage for 10 days; controls received an equivalent volume of saline solution. Histologic and histomorphometric studies of the mandible were performed. The data were statistically analyzed using Student's t test; statistical significance was set at a value of p <0.05. Experimental animals exhibited delayed tooth eruption, decreased periodontal width and bone volume, a lower percentage of bone formation surfaces, and higher percentage of quiescent surfaces (p<0.05) compared to controls. The delay in tooth eruption observed after exposure to hexavalent chromium is the result of a lower rate of bone remodeling in the developing alveolus. The obtained results show the importance of controlling toxic substances in drinking water, since their effects may alter the growth and development of subjects who were exposed during early infancy.

Desechos industriales que contienen cromo hexavalente inade- cuadamente tratados contaminan el agua de consumo pudiendo afectar a los niños por vía de la leche materna o de la preparación de mamaderas. Por lo tanto, el objetivo del presente trabajo fue determinar el efecto de este tóxico en la actividad del hueso en el alveolo en desarrollo durante la erupción dentaria de ratas Wistar lactantes expuestas a dicromato de potasio. Los animales experimentales recibieron una dosis diaria de 12,5 mg / kg de peso corporal de dicromato de potasio por alimentación forzada durante 10 días; mientras que los controles, un volumen equivalente de solución salina. Se llevaron a cabo estudios histológicos e histomorfométricos de la mandíbula. Los datos fueron analizados estadísticamente utilizando la prueba t de Student; estableciéndose un valor de p<0,05 como estadísticamente significativo. Los animales expuestos a cromo hexavalente mostraron retraso en la erupción dentaria, menor espacio periodontal y volumen óseo; encontrándose disminuidas las superficies en formación y en reabsorción óseas y aumentadas las superficies en reposo (p <0,05) en comparación con los controles. El retraso en la erupción dentaria observado luego de la exposición a cromo hexavalente es el resultado de una menor remodelación ósea en el alveolo en desarrollo. Los resultados obtenidos muestran la importancia del control de sustancias tóxicas en el agua potable, ya que sus efectos pueden alterar el crecimiento y el desarrollo de los individuos que fueron expuestos durante la infancia temprana.

Impairment of bony crypt development associated with hexavalent chromium exposure during tooth eruption

Improperly treated hexavalent chromium-containing industrial wastes contaminate drinking water, potentially affecting children taking breast milk or baby bottles prepared with infant formula. Thus, the aim of the present work was to determine the effect of this toxic on bone activity in the developing alveolus during tooth eruption of suckling Wistar rats intoxicated with potassium dichromate. Experimental animals received a daily dose of 12.5mg/kg body weight of potassium dichromate by gavage for 10 days; controls received an equivalent volume of saline solution. Histologic and histomorphometric studies of the mandible were performed. The data were statistically analyzed using Student's t test; statistical significance was set at a value of p <0.05. Experimental animals exhibited delayed tooth eruption, decreased periodontal width and bone volume, a lower percentage of bone formation surfaces, and higher percentage of quiescent surfaces (p<0.05) compared to controls. The delay in tooth eruption observed after exposure to hexavalent chromium is the result of a lower rate of bone remodeling in the developing alveolus. The obtained results show the importance of controlling toxic substances in drinking water, since their effects may alter the growth and development of subjects who were exposed during early infancy.

Desechos industriales que contienen cromo hexavalente inade - cua damente tratados contaminan el agua de consumo pudiendo afectar a los ninos por via de la leche materna o de la preparacion de mamaderas. Por lo tanto, el objetivo del presente trabajo fue determinar el efecto de este toxico en la actividad del hueso en el alveolo en desarrollo durante la erupcion dentaria de ratas Wistar lactantes expuestas a dicromato de potasio. Los animales experimentales recibieron una dosis diaria de 12,5 mg / kg de peso corporal de dicromato de potasio por alimentacion forzada durante 10 dias; mientras que los controles, un volumen equivalente de solucion salina. Se llevaron a cabo estudios histologicos e histomorfometricos de la mandibula. Los datos fueron analizados estadisticamente utilizando la prueba t de Student; estableciendose un valor de p<0,05 como esta - disticamente significativo. Los animales expuestos a cromo hexavalente mostraron retraso en la erupcion dentaria, menor espacio periodontal y volumen oseo; encontrandose disminuidas las superficies en formacion y en reabsorcion oseas y aumentadas las superficies en reposo (p <0,05) en comparacion con los controles. El retraso en la erupcion dentaria observado luego de la exposicion a cromo hexavalente es el resultado de una menor remodelacion osea en el alveolo en desarrollo. Los resultados obtenidos muestran la importancia del control de sustancias toxicas en el agua potable, ya que sus efectos pueden alterar el crecimiento y el desarrollo de los individuos que fueron expuestos durante la infancia temprana.

Plastination technique in laboratory rats: an alternative resource for teaching, surgical training and research development / Técnica de plastinación en ratas de laboratorio: un recurso alternativo para la enseñanza, entrenamiento quirúrgico y desarrollo de la investigación

Today, alternatives methods are developed for the use of laboratory animals for teaching, research and surgical training. In our work we present a novel alternative to the use of rats, by developing a technique of plastination at room temperature. High-quality rat preparations from the anatomical dissection point of view were obtained, in order to indefinitely preserve them dry, the thoracic and abdominal organs conserve its natural volume and shape, maintaining their texture and color. No odors or hassles and toxic vapors of conventional preserving agents were found. This technique allows the collection of dry, completely biosafe and durable specimens in a short time and with excellent quality. Plastination in laboratory rats complements undergraduate and postgraduate anatomy studies perfectly. Also, radiology and surgery may benefit from this technique.

En la actualidad, se desarrollan alternativas para el uso de animales de laboratorio para enseñanza, investigación y entrenamiento quirúrgico. En nuestro trabajo presentamos una novedosa alternativa para el uso de ratas, a través del desarrollo de una técnica de plastinación a temperatura ambiente. Se obtuvieron preparados de alta calidad desde el punto de vista de la disección anatómica, con órganos torácicos y abdominales que conservaron su volumen, forma, textura y color. Además, los especímenes carecen de olores y no emiten vapores tóxicos, debido a la ausencia de agentes conservantes convencionales. Esta técnica permite desarrollar especÌmenes secos de excelente calidad, completamente bioseguros y duraderos, en muy poco tiempo. La plastinación en ratas de laboratorio complementa los estudios de anatomía de pregrado y postgrado perfectamente. Además, las áreas de radiología y cirugía también pueden beneficiarse de esta técnica.

Experimental model of distraction osteogenesis in edentulous rats.

UNLABELLED: Distraction osteogenesis (DO) is a surgical technique producing bone lengthening by distraction of the fracture callus. Although a large number of experimental studies on the events associated with DO of craniofacial skeleton have been reported, the few employing rat mandibular bone DO used complicated designs and produced a small volume of newly formed bone. Thus, this study aims to present an original experimental model of mandibular DO in edentulous rats that produces a sufficient quantity and quality of intramembranous bone. Eight male Wistar rats, weighing 75 g, underwent extraction of lower molars. With rats weighing 350 g, right mandibular osteotomy was performed and the distraction device was placed. The distraction device was custom made using micro-implants, expansion screws, and acrylic resin. STUDY PROTOCOL: latency: 6 days, distraction: » turn (0.175 mm) once a day during 6 d, consolidation: 28 d after distraction phase, sacrifice. DO-treated and contralateral hemimandibles were dissected and compared macroscopically and using radiographic studies. Histological sections were obtained and stained with H&E. A distraction gap filled with newly formed and mature bone tissue was obtained. This model of mandibular DO proved useful to obtain adequate quantity and quality of bone to study bone regeneration.

Experimental model of distraction osteogenesis in edentulous rats

Distraction osteogenesis (DO) is a surgical technique producing bone lengthening by distraction of the fracture callus. Although a large number of experimental studies on the events associated with DO of craniofacial skeleton have been reported, the few employing rat mandibular bone DO used complicated designs and produced a small volume of newly formed bone. Thus, this study aims to present an original experimental model of mandibular DO in edentulous rats that produces a sufficient quantity and quality of intramembranous bone. Eight male Wistar rats, weighing 75 g, underwent extraction of lower molars. With rats weighing 350 g, right mandibular osteotomy was performed and the distraction device was placed. The distraction device was custom made using micro-implants, expansion screws, and acrylic resin. Study protocol: latency: 6 days, distraction: » turn (0.175 mm) once a day during 6 d, consolidation: 28 d after distraction phase, sacrifice. DO-treated and contralateral hemimandibles were dissected and compared macroscopically and using radiographic studies. Histological sections were obtained and stained with H&E. A distraction gap filled with newly formed and mature bone tissue was obtained. This model of mandibular DO proved useful to obtain adequate quantity and quality of bone to study bone regeneration.

Bone response to orthodontic forces in diabetic Wistar rats.

INTRODUCTION: Patients with type 1 diabetes have shown decreased bone mineral density (BMD) values. The need for orthodontic treatment in diabetic patients is usually associated with occlusal problems and the occurrence of abnormalities in the development of the jaws. The aim of this study was to analyze bone response of insulin-treated and untreated diabetic rats after applying orthodontic forces. METHODS: Wistar rats were divided into 3 groups: experimental orthodontics, experimental diabetes and orthodontics, and experimental diabetes treated with insulin and experimental orthodontics. Orthodontic forces were applied the first day of the seventh week. Forty-eight hours after placement, all the animals were killed, and the maxillae were excised and processed using routine histologic techniques. RESULTS: Bone activity in the periodontal cortex of the dental alveolus showed a significant decrease in bone formation and erosive areas in diabetic animals as compared with controls. A recovery of these parameters could be observed in the group with experimental diabetes treated with insulin and experimental orthodontics. Bone volume in the interradicular bone showed no significant differences among groups. CONCLUSIONS: People with diabetes should not receive orthodontic treatment until their metabolic status normalizes. Bone response to orthodontic forces in insulin-treated diabetic subjects does not differ significantly from that observed in healthy subjects.

Effect of lithium carbonate on subchondral bone in sexually mature Wistar rats.

Clinical and experimental studies have shown that lithium carbonate causes a number of clinical manifestations such as hyperparathyroidism, hypothyroidism, renal toxicity, and diabetes insipidus. The effect of this drug on the bone biology of experimental animals has not been studied to date. Therefore, the aim of the present experimental work was to study the effect of lithium on bone tissue in healthy sexually mature Wistar rats. Ten female Wistar rats, aged 312-412 months, 210-220 g body weight, were assigned to one of the following groups: untreated control group and experimental group receiving 45 mg/kg body weight/day of lithium carbonate in their drinking water during 3 months. Prior to euthanasia, blood samples were obtained in order to determine plasma phosphorus, calcium alkaline phosphatase, and lithium. After sacrifice, the tibiae were resected, processed, and embedded in paraffin. The following histomorphometric parameters were determined on digital photographs of the histologic sections: BV/TV (%), bone volume; Tb.Th (microm), trabecular thickness; Tb.N (mm(-2)/mm), trabecular number; Tb.Sp (microm), trabecular separation; Ob.S/BS (%), osteoblast surface; ES/BS (%), total erosive surface; Lc.S (%), lining cells surface; and GPC.Th (microm), thickness of growth plate cartilage. The results showed that administration of lithium carbonate cause bone loss in healthy sexually mature Wistar rats. Although the mechanism involved in bone toxicity remains to be clarified, the results obtained in the present study suggest that patients under long-term lithium therapy should be thoroughly evaluated, particularly those presenting other risk factors of osteopenia, such as menopause, low calcium intake, alcohol consumption, and glucocorticoid therapy.