What is the value of orthodontic treatment?

Orthodontic treatment is as popular as ever. Orthodontists frequently have long lists of people wanting treatment and the cost to the NHS in England was £258m in 2010-2011 (approximately 10% of the NHS annual spend on dentistry). It is important that clinicians and healthcare commissioners constantly question the contribution of interventions towards improving the health of the population. In this article, the authors outline some of the evidence for and against the claims that people with a malocclusion are at a disadvantage compared with those without a malocclusion and that orthodontic treatment has significant health benefits. The authors would like to point out that this is not a comprehensive and systematic review of the entire scientific literature. Rather the evidence is presented in order to stimulate discussion and debate

Assessment of the quality of measures of child oral health-related quality of life

Background Several measures of oral health-related quality of life have been developed for children. The most frequently used are the Child Perceptions Questionnaire (CPQ), the Child Oral Impacts on Daily Performances (C-OIDP) and the Child Oral Health Impact Profile (COHIP). The aim of this study was to assess the methodological quality of the development and testing of these three measures. Methods A systematic search strategy was used to identify eligible studies published up to December 2012, using both MEDLINE and Web of Science. Titles and abstracts were read independently by two investigators and full papers retrieved where the inclusion criteria were met. Data were extracted by two teams of two investigators using a piloted protocol. The data were used to describe the development of the measures and their use against existing criteria. The methodological quality and measurement properties of the measures were assessed using standards proposed by the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) group. Results The search strategy yielded 653 papers, of which 417 were duplicates. Following analysis of the abstracts, 119 papers met the inclusion criteria. The majority of papers reported cross-sectional studies (n = 117) with three of longitudinal design. Fifteen studies which had used the original version of the measures in their original language were included in the COSMIN analysis. The most frequently used measure was the CPQ. Reliability and construct validity appear to be adequate for all three measures. Children were not fully involved in item generation which may compromise their content validity. Internal consistency was measured using classic test theory with no evidence of modern psychometric techniques being used to test unidimensionality of the measures included in the COSMIN analysis. Conclusion The three measures evaluated appear to be able to discriminate between groups. CPQ has been most widely tested and several versions are available. COHIP employed a rigorous development strategy but has been tested in fewer populations. C-OIDP is shorter and has been used successfully in epidemiological studies. Further testing using modern psychometric techniques such as item response theory is recommended. Future developments should also focus on the development of measures which can evaluate longitudinal change

The tRNA-dependent activation of arginine by arginyl-tRNA synthetase requires inter-domain communication.

International audienceThe tRNA-dependent amino acid activation catalyzed by mammalian arginyl-tRNA synthetase has been characterized. A conditional lethal mutant of Chinese hamster ovary cells that exhibits reduced arginyl-tRNA synthetase activity (Arg-1), and two of its derived revertants (Arg-1R4 and Arg-1R5) were analyzed at the structural and functional levels. A single nucleotide change, resulting in a Cys to Tyr substitution at position 599 of arginyl-tRNA synthetase, is responsible for the defective phenotype of the thermosensitive and arginine hyper-auxotroph Arg-1 cell line. The two revertants have a single additional mutation resulting in a Met222 to Ile change for Arg-1R4 or a Tyr506 to Ser change for Arg-1R5. The corresponding mutant enzymes were expressed in yeast and purified. The Cys599 to Tyr mutation affects both the thermal stability of arginyl-tRNA synthetase and the kinetic parameters for arginine in the ATP-PP(i) exchange and tRNA aminoacylation reactions. This mutation is located underneath the floor of the Rossmann fold catalytic domain characteristic of class 1 aminoacyl-tRNA synthetases, near the end of a long helix belonging to the alpha-helix bundle C-terminal domain distinctive of class 1a synthetases. For the Met222 to Ile revertant, there is very little effect of the mutation on the interaction of arginyl-tRNA synthetase with either of its substrates. However, this mutation increases the thermal stability of arginyl-tRNA synthetase, thereby leading to reversion of the thermosensitive phenotype by increasing the steady-state level of the enzyme in vivo. In contrast, for the Arg-1R5 cell line, reversion of the phenotype is due to an increased catalytic efficiency of the C599Y/Y506S double mutant as compared to the initial C599Y enzyme. In light of the location of the mutations in the 3D structure of the enzyme modeled using the crystal structure of the closely related yeast arginyl-tRNA synthetase, the kinetic analysis of these mutants suggests that the obligatory tRNA-induced activation of the catalytic site of arginyl-tRNA synthetase involves interdomain signal transduction via the long helices that build the tRNA-binding domain of the enzyme and link the site of interaction of the anticodon domain of tRNA to the floor of the active site

Peptidic Determinants and Structural Model of Human NDP Kinase B (Nm23-H2) Bound to Single-Stranded DNA

International audienceIsoform B of human NDP kinase (NDPK-B) was previously identified as a transcription factor stimulating in vitro and ex vivo the transcription of the c-myc oncogene, which involves this enzyme in carcinogenesis. We have studied the enzymatic properties of NDPK-B in the presence of several single-stranded oligonucleotides. We show that the oligonucleotides are competitive inhibitors of the catalytic activity, indicating that the active site acts as a binding template for the anchorage of the oligonucleotide. Furthermore, the presence of a guanine at the 3'-end of several different aptamers increases its affinity 10-fold. To define the surface of the protein contacting the DNA within the nucleoprotein complex, we used single nanosecond laser pulses as the cross-linking reagent and MALDI-TOF mass spectrometry to identify cross-linked peptides purified from proteolytic digests of the cross-linked complex. Using 11-mer and 30-mer single-stranded oligonucleotides, the same three different nucleopeptides were identified after irradiation of the complexes, indicating a common binding mode for these two aptamers. Taken together, these results allowed us to propose a structural model of NDPK-B bound to single-stranded DNA

NEMO specifically recognizes K63-linked poly-ubiquitin chains through a new bipartite ubiquitin-binding domain

An important property of NEMO, the core element of the IKK complex involved in NF-κB activation, resides in its ability to specifically recognize poly-ubiquitin chains. A small domain called NOA/UBAN has been suggested to be responsible for this property. We recently demonstrated that the C-terminal Zinc Finger (ZF) of NEMO is also able to bind ubiquitin. We show here by ZF swapping and mutagenesis that this represents its only function. While neither NOA nor ZF shows any preference for K63-linked chains, we demonstrate that together they form a bipartite high-affinity K63-specific ubiquitin-binding domain. A similar domain can be found in two other proteins, Optineurin and ABIN2, and can be freely exchanged with that of NEMO without interfering with its activity. This suggests that the main function of the C-terminal half of NEMO is to specifically bind K63-linked poly-ubiquitin chains. We also demonstrate that the recently described binding of NEMO to linear poly-ubiquitin chains is dependent on the NOA alone and does not require the presence of the ZF

Natural Variation Can Significantly Alter the Sensitivity of Influenza A (H5N1) Viruses to Oseltamivir

Geographic spread of highly pathogenic avian H5N1 influenza viruses may give rise to an influenza pandemic. During the first months of a pandemic, control measures would rely mainly on antiviral drugs, such as the neuraminidase (NA) inhibitors oseltamivir and zanamivir. In this study, we compare the sensitivities to oseltamivir of the NAs of several highly pathogenic H5N1 viruses isolated in Asia from 1997 to 2005. The corresponding 50% inhibitory concentrations were determined using a standard in vitro NA inhibition assay. The K(m) for the substrate and the affinity for the inhibitor (K(i)) of NA were determined for a 1997 and a 2005 virus, using an NA inhibition assay on cells transiently expressing the viral enzyme. Our data show that the sensitivities of the NAs of H5N1 viruses isolated in 2004 and 2005 to oseltamivir are about 10-fold higher than those of earlier H5N1 viruses or currently circulating H1N1 viruses. Three-dimensional modeling of the N1 protein predicted that Glu248Gly and Tyr252His changes could account for increased sensitivity. Our data indicate that genetic variation in the absence of any drug-selective pressure may result in significant variations in sensitivity to anti-NA drugs. Although the clinical relevance of a 10-fold increase in the sensitivity of NA to oseltamivir needs to be investigated further, the possibility that sensitivity to anti-NA drugs could increase (or possibly decrease) significantly, even in the absence of treatment, underscores the need for continuous evaluation of the impact of genetic drift on this parameter, especially for influenza viruses with pandemic potential

Structural and catalytic properties and homology modelling of the human nucleoside diphosphate kinase C, product of the DRnm23 gene.

The human DRnm23 gene was identified by differential screening of a cDNA library obtained from chronic myeloid leukaemia-blast crisis primary cells. The over-expression of this gene inhibits differentiation and induces the apoptosis of myeloid precursor cell lines. We overproduced in bacteria a truncated form of the encoded protein lacking the first 17 N-terminal amino acids. This truncated protein was called nucleoside diphosphate (NDP) kinase CDelta. NDP kinase CDelta had similar kinetic properties to the major human NDP kinases A and B, but was significantly more stable to denaturation by urea and heat. Analysis of denaturation by urea, using size exclusion chromatography, indicated unfolding without the dissociation of subunits, whereas renaturation occurred via a folded monomer. The stability of the protein depended primarily on subunit interactions. Homology modelling of the structure of NDP kinase CDelta, based on the crystal structure of NDP kinase B, indicated that NDP kinase CDelta had several additional stabilizing interactions. The overall structure of the two enzymes appears to be identical because NDP kinase CDelta readily formed mixed hexamers with NDP kinase A. It is possible that mixed hexamers can be observed in vivo