Matrix metalloproteinases: the most important pathway involved with periodontal destruction

Periodontitis is an infectious disease estimated to occur in approximately a third of adults over the age of 35, being the major cause of adult tooth loss. The tissue destruction seems to be regulated by four major pathways. Plasminogen-dependent, phagocytic, osteoclastic and matrix metalloproteinase pathway. The matrix metalloproteinases (MMPs) pathway seems to be the most relevant in periodontal disease. The purpose of the current study was to review the roles of MMPs on periodontal disease, with emphasis on periodontal ligament and alveolar bone destruction. Particular attention is given on the mechanisms that control MMPs genes transcription, the regulation of protein activity, and the influence of MMP genes polymorphisms in inflammatory diseases.

Loss of heterozygosity by mitotic recombination in diploid strain of Aspergillus nidulans in response to castor oil plant detergent

A recombinação somática em células diplóides heterozigotas pode atuar como agente promotor de neoplasias por induzir homozigose de genes deletéreos. Por meio desse processo, genes supressores de tumores podem ser completamente suprimidos em células recombinantes. O presente trabalho avaliou a genotoxicidade do detergente derivado do óleo da semente da mamona (Ricinus communis) em células diplóides heterozigotas do fungo filamentoso Aspergillus nidulans. Trabalhos anteriores avaliaram a aplicação dessa solução no tratamento de canais radiculares como líquido irrigador. O potencial recombinagênico desse composto foi estudado pela origem de células homozigotas para os marcadores nutricionais: riboA1, pabaA124, biA1, metA17 e piroA4. A solução, diluída em 1:40, 1:20 e 1:10, induziu alterações morfológicas e atraso no desenvolvimento dos conidióforos da linhagem UT448//UT196 e aumento nas freqüências de recombinação mitótica. Embora trabalhos anteriores relatem a atividade antimicrobiana da solução em estudo, nossos resultados evidenciam a citotoxicidade e o potencial recombinagênico dessa substância.

Loss of heterozygosity by mitotic recombination in diploid strain of Aspergillus nidulans in response to castor oil plant detergent.

Somatic recombination in heterozygous diploid cells may be a promotional agent of neoplasms by inducing homozygosity of defective genes. Tumor suppressor genes may in this way be completely suppressed in recombinant cells. In this work, the genotoxic effects of detergent derived from the castor oil plant (Ricinus communis) in heterozygous diploid cells of Aspergillus nidulans are evaluated. Previous studies have evaluated the application of this substance in endodontic treatments as an irrigating solution. The recombinogenic potential of the compound has been studied through the production of homozygous cells for nutritional markers riboA1, pabaA124, biA1, methA17, and pyroA4. Detergent was diluted to 1:10, 1:20, and 1:40, and morphologic alterations, delay in conidiophore development, and mitotic recombination occurrence were reported for the three dilutions. Although past studies have demonstrated the antimicrobial action of the detergent under analysis, our results revealed its cytotoxic effects and recombinogenic potential.

Histologic evaluation of the osteoinductive property of autogenous demineralized dentin matrix on surgical bone defects in rabbit skulls using human amniotic membrane for guided bone regeneration.

The aim of this investigation was to evaluate the osteoinductive property of autogenous demineralized dentin matrix (ADDM) on experimental surgical bone defects in the parietal bone of rabbits using the guided bone regeneration (GBR) technique incorporating human amniotic membrane (HAM). Thirty-six rabbits were divided into 2 groups, HAM and ADDM+HAM. It was possible to conclude that HAM did not interfere with bone repair and was resorbed. Slices of ADDM induced direct bone formation and were incorporated by the newly formed bone tissue and remodeled. The bone defects healed faster in the ADDM+HAM group than in the group with HAM only.

Assessment of the antiexudative and antiproliferative activities of non-steroidal anti-inflammatory drugs in inflammatory models developed in rats by subcutaneous implantation of bacterial cell walls from the dental plaque.

A purified bacterial cell walls suspension from human dental plaque were biochemically prepared to serve as flogogenous agent in producing experimental inflammatory models in rats. In the vascular permeability inhibition assay (edemogenic test), the subcutaneous implantation of the flogogenous agent elicited an acute inflammatory reaction highly susceptible to the effects of the non-steroidal anti-inflammatory drugs (NSAIDs). The intradermal injection of the flogogenous agent in the dorsum of rats developed experimental granulomas also susceptible to the anti-inflammatory effects of the NSAIDs. Otherwise, the antimitotic effect of drugs was carried out in the model of cellular proliferation of duodenal mucosa of rats by incorporation of tritiated thymidine (3H TdR) in the DNA. These models of acute and chronic inflammation, and the antimitotic model permitted us to evaluate the anti-inflammatory and antimitotic effects of sulindac, ibuprofen, naproxen and glucametacin. In the antiexudative activity, evaluated by the edemogenic test, naproxen was the more effective drug followed by sulindac, ibuprofen and glucametacin (in a decreasing order of potency) to inhibit the exudative response induced by the bacterial cell walls suspension, in all experimental periods. In the chronic anti-inflammatory activity, evaluated by the granuloma inhibition assay, all drugs were capable to demonstrate effectiveness against the development of the experimental granulomas induced by an intradermal injection of the flogogenous agent. In the model of cellular proliferation, all tested drugs demonstrated antimitotic activity in all experimental periods (4, 6 and 8 days), also. Sulindac induced the higher antimitotic effect, in all experimental periods, followed by ibuprofen, naproxen and glucametacin in a decreasing order of efficacy. There was a positive correlation between the antiexudative, anti-proliferative, and antimitotic effects.

Osteogenic potential of autogenic demineralized dentin implanted in bony defects in dogs.

The bone morphogenetic properties of implants of autogenic demineralized dentin were evaluated. The dentin matrix was implanted as small pieces and as thin slices in experimental mandibular osseous defects in dogs. The dentin implants were obtained from mandibular incisor teeth from the same dogs used in the experiment. Experimental interradicular osseous defects were surgically created in the mandibular premolars areas. 2 of the 3 defects were filled with either pieces or slices of prepared dentin. The 3rd defect served as an unfilled control. The results indicate that all demineralized autogenic dentin implants induce bone formation. There was an increase in the osteogenic capacity of the implant when the samples were used as thin slices. The slices of dentin matrix give no evidence of resorption and were readily incorporated into the new bone deposited. The end product was represented by a trabecular bone joined to the dentin matrix slices. In the case of the small piece samples, the specimens were readily resorbed and replaced by new deposits of cancelous bone. The osteogenic capacity of the small piece samples of the dentin matrix is less efficient comparable to the thin slice samples of the same implant material.