Reconstruction of maxillary palatal defects after partial maxillectomy using a pedicled buccal fat pad and a nasolabial flap

Abstract The novelty of this procedure is the reconstruction of a maxillary palatal defect with two pedicled flaps: a pedicled buccal fat pad and a nasolabial flap. This use of combination flaps makes the surgery simple, short, and useful for a wide defect.The novelty of this procedure is the reconstruction of a maxillary palatal defect with two pedicled flaps: a pedicled buccal fat pad and a nasolabial flap. This use of combination flaps makes the surgery simple, short, and useful for a wide defect

Single Nucleotide Polymorphism in the Cytolethal Distending Toxin B Gene Confers Heterogeneity in the Cytotoxicity of Actinobacillus actinomycetemcomitans

Clinical Actinobacillus actinomycetemcomitans produces cytolethal distending toxin (CDT) with titers ranging from 10(2) to 10(8) U/mg. Single nucleotide polymorphism analysis of the cdt gene in clinical isolates identified a variation of a single amino acid at residue 281 of CdtB, which significantly affected CDT toxicity by modulating the chromatin-degrading activity of CdtB

Prevalence of Cytolethal Distending Toxin Production in Periodontopathogenic Bacteria

Cytolethal distending toxin (CDT) is a newly identified virulence factor produced by several pathogenic bacteria implicated in chronic infection. Seventy three strains of periodontopathogenic bacteria were examined for the production of CDT by a HeLa cell bioassay and for the presence of the cdt gene by PCR with degenerative oligonucleotide primers, which were designed based on various regions of the Escherichia coli and Campylobacter cdtB genes, which have been successfully used for the identification and cloning of cdtABC genes from Actinobacillus actinomycetemcomitans Y4 (M. Sugai et al., Infect. Immun. 66:5008-5019, 1998). CDT activity was found in culture supernatants of 40 of 45 tested A. actinomycetemcomintans strains, but the titer of the toxin varied considerably among these strains. PCR experiments indicated the presence of Y4-type cdt sequences in these strains, but the rest of A. actinomycetemcomitans were negative by PCR amplification and also by Southern blot analysis for the cdtABC gene. In the 40 CDT-positive strains, Southern hybridization with HindIII-digested genomic DNA revealed that there are at least 6 restriction fragment length polymorphism types. This suggests that the cdtABC flanking region is highly polymorphic, which may partly explain the variability of the CDT activity in the culture supernatants. The rest of tested strains of periodontopathogenic bacteria did not have detectable CDT production by the HeLa cell assay and for cdtB sequences by PCR analysis under our experimental conditions. These results strongly suggested that CDT is a unique toxin predominantly produced by A. actinomycetemcomitans among periodontopathogenic bacteria

DNA Damage-Dependent Acetylation and Ubiquitination of H2AX Enhances Chromatin Dynamics▿ †

Chromatin reorganization plays an important role in DNA repair, apoptosis, and cell cycle checkpoints. Among proteins involved in chromatin reorganization, TIP60 histone acetyltransferase has been shown to play a role in DNA repair and apoptosis. However, how TIP60 regulates chromatin reorganization in the response of human cells to DNA damage is largely unknown. Here, we show that ionizing irradiation induces TIP60 acetylation of histone H2AX, a variant form of H2A known to be phosphorylated following DNA damage. Furthermore, TIP60 regulates the ubiquitination of H2AX via the ubiquitin-conjugating enzyme UBC13, which is induced by DNA damage. This ubiquitination of H2AX requires its prior acetylation. We also demonstrate that acetylation-dependent ubiquitination by the TIP60-UBC13 complex leads to the release of H2AX from damaged chromatin. We conclude that the sequential acetylation and ubiquitination of H2AX by TIP60-UBC13 promote enhanced histone dynamics, which in turn stimulate a DNA damage response