RESUMO
Over the last decade tissue engineering has emerged as a key factor in bone regeneration within the field of cranio-maxillofacial surgery. Despite this in vivo analysis of tissue-engineered-constructs to monitor bone rehabilitation are difficult to conduct. Novel high-resolving flat-panel based volume CTs (fp-VCT) are increasingly used for imaging bone structures. This study compares the potential value of novel fp-VCT with conventional multidetector CT (MDCT) based on a sheep sinus floor elevation model. Calcium-hydroxyapatite reinforced collagen scaffolds were populated with autologous osteoblasts and implanted into sheep maxillary sinus. After 8, 16 and 24 weeks MDCT and fp-VCT scans were performed to investigate the volume of the augmented area; densities of cancellous and compact bone were assessed as comparative values. fp-VCT imaging resulted in higher spatial resolution, which was advantageous when separating closely related anatomical structures (i.e. trabecular and compact bone, biomaterials). Fp-VCT facilitated imaging of alterations occurring in test specimens over time. fp-VCTs therefore displayed high volume coverage, dynamic imaging potential and superior performance when investigating superfine bone structures and bone remodelling of biomaterials. Thus, fp-VCTs may be a suitable instrument for intraoperative imaging and future in vivo tissue-engineering studies.
Assuntos
Substitutos Ósseos/química , Tomografia Computadorizada Multidetectores/métodos , Levantamento do Assoalho do Seio Maxilar/métodos , Tomografia Computadorizada por Raios X/métodos , Animais , Apatitas/química , Autoenxertos/transplante , Densidade Óssea/fisiologia , Remodelação Óssea/fisiologia , Técnicas de Cultura de Células , Colágeno/química , Combinação de Medicamentos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Seio Maxilar/diagnóstico por imagem , Seio Maxilar/cirurgia , Tomografia Computadorizada Multidetectores/instrumentação , Osteoblastos/transplante , Distribuição Aleatória , Ovinos , Fatores de Tempo , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Tomografia Computadorizada por Raios X/instrumentaçãoRESUMO
Fluorescent amplified fragment length polymorphism analysis demonstrates a high level of gene exchange between Saccharomyces sensu stricto species, with some strains having undergone multiple interspecific hybridization events with subsequent changes in genome complexity. Two lager strains were shown to be hybrids between Saccharomyces cerevisiae and the alloploid species Saccharomyces pastorianus. The genome structure of CBS 380(T), the type strain of Saccharomyces bayanus, is also consistent with S. pastorianus gene transfer. The results indicate that the cider yeast, CID1, possesses nuclear DNA from three separate species. Mating experiments show that there are no barriers to interspecific conjugation of haploid cells. Furthermore, the allopolyploid strains were able to undergo further hybridizations with other Saccharomyces sensu stricto yeasts. These results demonstrate that introgression between the Saccharomyces sensu stricto species is likely.