Management of the dentoalveolar effects of tongue hypertrophy in patients with Duchenne muscular dystrophy: A pilot study.

Subjects affected by Duchenne muscular dystrophy (DMD) develop severe malocclusions with the progression of the disease, due to changes in orofacial musculature and function, including tongue hypertrophy. We aimed to evaluate the benefits of maintaining mandibular interarch width with the help of a simple fixed orthodontic appliance. Three adolescent DMD boys were selected consecutively to receive a passive rigid mandibular lingual arch, and followed for 4-5 years. An untreated age-matched control group was chosen and followed for a similar period. Study casts were obtained at baseline and after follow-up. Outcomes measured were overjet, overbite, maxillary and mandibular intermolar widths, mandibular arch depth, molar relationships, and the presence of lateral crossbites and anterior or lateral openbites. Changes in measurements obtained between the two time points were compared in each age-matched pair. There was a clinically important increase in the mandibular intermolar width in the non-treated children ranging from 2.5 mm to 9 mm, but not in those treated. Malocclusions generally deteriorated in untreated children while they remained stable in treated children. The use of a rigid mandibular lingual arch in boys with DMD can help slow down the rapid deterioration of the developing malocclusions that accompanies the progression of the disease.

Growing patients with Duchenne muscular dystrophy: longitudinal changes in their dentofacial morphology and orofacial functional capacities.

Aim: The aim of this study was to describe the longitudinal changes in facial morphology, dental arch alterations and oral functional capacities that occur in growing patients with Duchenne muscular dystrophy (DMD) in order to identify the effects of the progression of the disease. Subjects and Methods: Twelve DMD patients (6.5-17.5 years of age) and 12 matched controls were screened on two different occasions (T1 and T2), 2 years apart. Dental casts, lateral cephalometric radiographs, maximal posterior bite force and labial force were measured to determine changes in their functional capacities and dentofacial morphology. Furthermore, the thickness and echogenicity of the masseter muscle were measured during clenching. Statistical evaluation: Unpaired t-tests were performed to evaluate the differences between the DMD patients and their healthy matched controls; paired t-tests were used to assess the changes that occurred within each group between T1 and T2. Results: Between T1 and T2 the following changes were observed: widening of the lower dental arch for the DMD patients of 2.6mm (±0.9mm) compared to a slight reduction of -0.1mm (±0.8mm) for the control group (P = 0.001). We found a statistically significant reduction of the sagittal skeletal intermaxillary relationship (ANB-angle) of 2.0° (±2.0°) in the DMD group (P = 0.012). In T1 and T2, the maximal posterior bite force and the labial force were lower for the DMD patients compared to the control group (P = 0.001), who showed an increase during this period. Conclusion: The results indicate that DMD influences the facial morphology, dental arch dimensions and oral functional capacities. The longitudinal perspective of this study revealed that the worsening of most of the measured parameters is associated with the progression of the disease. Besides the expected deterioration of the functional measurements, we found in all patients, a marked transverse increase of the posterior part of the dental arches, more in the lower than in the upper, resulting in posterior crossbites, as well as a tendency towards a skeletal Class III relationship.

Plasmid-like replication of a minimal streptococcal integrative and conjugative element.

Integrative and conjugative elements (ICEs) are mobile genetic elements encoding their own excision from a replicon of their bacterial host, transfer by conjugation to a recipient bacterium and reintegration for maintenance. The conjugation, recombination and regulation modules of ICEs of the ICESt3 family are grouped together in a region called the ICE 'core region'. In addition to this core region, elements belonging to this family carry a highly variable region including cargo genes that could be involved in bacterial adaptation or in the maintenance of the element. Although ICEs are a major class of mobile elements through bacterial genomes, the functionality of an element encoding only its excision, transfer, integration and regulation has never been demonstrated experimentally. We engineered MiniICESt3, an artificial ICE derived from ICESt3, devoid of its cargo genes and thus only harbouring the core region. The functionality of this minimal element was assessed. MiniICESt3 was found to be able to excise at a rate of 3.1 %, transfer with a frequency of 1.0 × 10- 5 transconjugants per donor cell and stably maintain by site-specific integration into the 3' end of the fda gene, the same as ICESt3. Furthermore, MiniICESt3 was found in ∼10 copies per chromosome, this multicopy state likely contributing to its stability for >100 generations even in the absence of selection. Therefore, although ICEs were primarily assumed to only replicate along with the chromosome, our results uncovered extrachromosomal rolling-circle replicating plasmid-like forms of MiniICESt3.

Differential regulation of two closely related integrative and conjugative elements from Streptococcus thermophilus.

BACKGROUND: Two closely related ICEs, ICESt1 and ICESt3, have been identified in the lactic acid bacterium Streptococcus thermophilus. While their conjugation and recombination modules are almost identical (95% nucleotide identity) and their regulation modules related, previous work has demonstrated that transconjugants carrying ICESt3 were generated at rate exceeding by a 1000 factor that of ICESt1. RESULTS: The functional regulation of ICESt1 and ICESt3 transcription, excision and replication were investigated under different conditions (exponential growth or stationary phase, DNA damage by exposition to mitomycin C). Analysis revealed an identical transcriptional organization of their recombination and conjugation modules (long unique transcript) whereas the transcriptional organization of their regulation modules were found to be different (two operons in ICESt1 but only one in ICESt3) and to depend on the conditions (promoter specific of stationary phase in ICESt3). For both elements, stationary phase and DNA damage lead to the rise of transcript levels of the conjugation-recombination and regulation modules. Whatever the growth culture conditions, excision of ICESt1 was found to be lower than that of ICESt3, which is consistent with weaker transfer frequencies. Furthermore, for both elements, excision increases in stationary phase (8.9-fold for ICESt1 and 1.31-fold for ICESt3) and is strongly enhanced by DNA damage (38-fold for ICESt1 and 18-fold for ICESt3). Although ICEs are generally not described as replicative elements, the copy number of ICESt3 exhibited a sharp increase (9.6-fold) after mitomycin C exposure of its harboring strain CNRZ385. This result was not observed when ICESt3 was introduced in a strain deriving ICESt1 host strain CNRZ368, deleted for this element. This finding suggests an impact of the host cell on ICE behavior. CONCLUSIONS: All together, these results suggest a novel mechanism of regulation shared by ICESt1, ICESt3 and closely related ICEs, which we identified by analysis of recently sequenced genomes of firmicutes. This is the first report of a partial shutdown of the activity of an ICE executed by a strain belonging to its primary host species. The sharp increase of ICESt3 copy number suggests an induction of replication; such conditional intracellular replication may be common among ICEs.

Site-specific accretion of an integrative conjugative element together with a related genomic island leads to cis mobilization and gene capture.

Genomic islands, flanked by attachment sites, devoid of conjugation and recombination modules and related to the integrative and conjugative element (ICE) ICESt3, were previously found in Streptococcus thermophilus. Here, we show that ICESt3 transfers to a recipient harbouring a similar engineered genomic island, CIMEL3catR3, and integrates by site-specific recombination into its attachment sites, leading to their accretion. The resulting composite island can excise, showing that ICESt3 mobilizes CIMEL3catR3, in cis. ICESt3, CIMEL3catR3, and the whole composite element can transfer from the strain harbouring the composite structure. The ICESt3 transfer to a recipient bearing CIMEL3catR3, can also lead to retromobilization, i.e. its capture by the donor. This is the first demonstration of specific conjugative mobilization of a genomic island in cis and the first report of ICE-mediated retromobilization. CIMEL3catR3, would be the prototype of a novel class of non-autonomous mobile elements (CIMEs: CIs mobilizable elements), which hijack the recombination and conjugation machinery of related ICEs to excise, transfer and integrate. Few genome analyses have shown that CIMEs could be widespread and have revealed internal repeats that could result from accretions in numerous genomic islands, suggesting that accretion and cis mobilization have a key role in evolution of genomic islands.

Conjugative transfer of the integrative conjugative elements ICESt1 and ICESt3 from Streptococcus thermophilus.

Integrative and conjugative elements (ICEs), also called conjugative transposons, are genomic islands that excise, self-transfer by conjugation, and integrate in the genome of the recipient bacterium. The current investigation shows the intraspecies conjugative transfer of the first described ICEs in Streptococcus thermophilus, ICESt1 and ICESt3. Mitomycin C, a DNA-damaging agent, derepresses ICESt3 conjugative transfer almost 25-fold. The ICESt3 host range was determined using various members of the Firmicutes as recipients. Whereas numerous ICESt3 transconjugants of Streptococcus pyogenes and Enterococcus faecalis were recovered, only one transconjugant of Lactococcus lactis was obtained. The newly incoming ICEs, except the one from L. lactis, are site-specifically integrated into the 3' end of the fda gene and are still able to excise in these transconjugants. Furthermore, ICESt3 was retransferred from E. faecalis to S. thermophilus. Recombinant plasmids carrying different parts of the ICESt1 recombination module were used to show that the integrase gene is required for the site-specific integration and excision of the ICEs, whereas the excisionase gene is required for the site-specific excision only.

Regulation of excision of integrative and potentially conjugative elements from Streptococcus thermophilus: role of the arp1 repressor.

The integrative and conjugative elements (ICEs) excise by site-specific recombination between attL and attR flanking sites, self-transfer the resulting circular form and integrate into the genome of the recipient cell. Two putative ICEs, ICESt1 and ICESt3, are integrated in the same locus in 2 strains of Streptococcusthermophilus. ICESt1 is a composite element harbouring an internal recombination site, attL'. The recombination between attL' and attR leads to the excision of a shorter putative ICE, ICESt2. ICESt1/ICESt2 and ICESt3 carry related regulation modules sharing the open reading frame arp1 that encodes a protein related to the cI repressor of the phage lambda. The repressors belonging to this family autoproteolyse in the presence of damaged DNA. Treatments with mitomycin C induce an increase in the excision of ICESt1, ICESt2 and ICESt3. Furthermore, the arp1 deletion leads to a 1,000-fold increase in the excision of ICESt1 and ICESt2 and to a decrease in the excision induction by mitomycin C. Thus, all together, these results suggest that the autocleavage of the arp1 repressor is involved in derepression of the S. thermophilus putative ICE excision by mitomycin C.

Derepression of excision of integrative and potentially conjugative elements from Streptococcus thermophilus by DNA damage response: implication of a cI-related repressor.

A DNA-damaging agent, mitomycin C, derepresses the site-specific excision of two integrative and potentially conjugative elements from Streptococcus thermophilus, ICESt1 and ICESt3. The regulation pathway involves a repressor related to phage lambda cI repressor. It could also involve a putative regulator related to another type of phage repressors, the "cI-like" repressors.

The constant gene orf14.9, which belongs to the variable eps (exopolysaccharide) cluster, is involved in the cell growth of Streptococcus thermophilus.

In Streptococcus thermophilus, the eps clusters involved in exopolysaccharide (EPS) biosynthesis are very polymorphic, nevertheless they all contain a highly conserved sequence corresponding to that of orf14.9. This open reading frame (ORF) is transcribed in a reverse direction with respect to eps genes. Amino acid sequence analysis showed a possible transmembrane location of the putative Orf14.9 protein but did not permit a proposed function. Insertional mutants of orf14.9 were obtained in strains NST2280 and A054 of S. thermophilus. EPS yields of these mutants are similar to those of their respective wild strains, suggesting that orf14.9 does not modify the quantity of produced EPS. Growth parameter determination for wild strains and their respective mutants showed that orf14.9 is involved in the cell growth of S. thermophilus.

Increased Wnt signaling triggers oncogenic conversion of human breast epithelial cells by a Notch-dependent mechanism.

Wnt and Notch signaling have long been established as strongly oncogenic in the mouse mammary gland. Aberrant expression of several Wnts and other components of this pathway in human breast carcinomas has been reported, but evidence for a causative role in the human disease has been missing. Here we report that increased Wnt signaling, as achieved by ectopic expression of Wnt-1, triggers the DNA damage response (DDR) and an ensuing cascade of events resulting in tumorigenic conversion of primary human mammary epithelial cells. Wnt-1-transformed cells have high telomerase activity and compromised p53 and Rb function, grow as spheres in suspension, and in mice form tumors that closely resemble medullary carcinomas of the breast. Notch signaling is up-regulated through a mechanism involving increased expression of the Notch ligands Dll1, Dll3, and Dll4 and is required for expression of the tumorigenic phenotype. Increased Notch signaling in primary human mammary epithelial cells is sufficient to reproduce some aspects of Wnt-induced transformation. The relevance of these findings for human breast cancer is supported by the fact that expression of Wnt-1 and Wnt-4 and of established Wnt target genes, such as Axin-2 and Lef-1, as well as the Notch ligands, such as Dll3 and Dll4, is up-regulated in human breast carcinomas.

Partial rhombencephalosynapsis.

We describe an infant in whom partial rhombencephalosynapsis was diagnosed by using MR imaging. The anterior vermis and nodulus were normally developed, but part of the posterior vermis was deficient. There was partial fusion of the hemispheres in the inferior part of the cerebellum. Partial rhombencephalosynapsis is described for the first time, and our findings support the recent embryologic observations.