Quality assessment of clinical practice guidelines used in oral and maxillofacial surgery.

An assessment of the quality of oral and maxillofacial surgery clinical practice guidelines is lacking. The aim of this investigation was to assess the quality of guidelines using the RIGHT (Reporting Items for practice Guidelines in HealThcare) checklist. The primary outcome was to assess the score (quality) of guidelines based on the RIGHT checklist and to identify predictors (region, type, single or multi-centre, and speciality/non-speciality) influencing the quality score. In this review, following a search of electronic databases and national society websites, a total of 25 guidelines were independently assessed by two assessors against the 22-item RIGHT checklist. Inter-assessor reliability was assessed. Deficiencies in the reporting of items relating to limitations, funding, declaration and management of interests, healthcare questions, and quality assurance were evident. The median overall score for the guidelines was 28 (range 14-66). Guidelines produced by multiple centres (ß=57.15, 95% confidence interval -26.62 to 87.68, P= 0.001, multivariate analysis) and non-speciality societies (ß=20, 95% confidence interval -0.03 to 40.03, P=0.05, univariate analysis) tended to have higher quality scores. Overall, the quality of clinical practice guidelines used in oral and maxillofacial surgery was deemed suboptimal. If clinical practice guidelines are to be used in making treatment decisions for patients, clinicians should be aware of their possible limitations.

Information for oral and maxillofacial patients: can it be improved?

The aim and objective of this study was to evaluate the quality and readability of leaflet and online Oral and Maxillofacial Surgery patient information leaflets (PILs). The quality, readability and grade level of each PIL was assessed using the DISCERN, Flesch Reading Ease and Flesh-Kincaid Grade Level instruments respectively. In total, 140 patient information leaflets were assessed. For both leaflet and online PILs, many items of the DISCERN instrument were deemed of low quality and poorly reported. The median overall quality score was 30.2. Variation in the quality and readability scores between leaflet and online PILs and those produced by various societies was evident. Overall, PILs were deemed to be of moderate quality. Online PILs were of lower quality, more difficult to read and aimed at a higher reading age level.

National clinical guidelines for the management of unerupted maxillary incisors in children.

This article summarises recently updated guidelines produced by the Clinical Governance Directorate of the British Orthodontic Society through the Clinical Standards Committee of the Faculty of Dental Surgery, Royal College of Surgeons of England (FDSRCS) on the management of unerupted maxillary incisor teeth in children. The maxillary incisor teeth usually erupt in the early mixed dentition but eruption disturbances can occur and are often attributable to local factors. A failure of eruption will affect the developing occlusion and potentially influence psychological development of the child. The general principles of management for delayed eruption or impaction of these teeth is to ensure that adequate space exists in the dental arch and to remove any obstruction to eruption. Consideration should also be given to further promoting eruption through surgical exposure of the incisor, with or without subsequent orthodontic traction. A number of factors influence the decision-making process, including patient age, medical history, potential compliance, aetiology and position of the unerupted incisor. Treatment planning should be complemented by careful clinical assessment and the use of appropriate special investigations. To optimise the treatment outcome a multidisciplinary specialist approach is recommended.

A survey of undergraduate orthodontic teaching and factors affecting pursuit of postgraduate training.

Background Undergraduate orthodontic teaching has been focused on developing an understanding of occlusal development in an effort to equip practitioners to make appropriate referrals for specialist-delivered care. However, there is a growing interest among general dentists in delivering more specialised treatments, including short-term orthodontic alignment. This study aimed to assess the levels of knowledge of occlusal problems among final year undergraduate dental students, as well as their interest in various orthodontics techniques and training.Methods A 36-item electronic questionnaire was sent to all final year undergraduate students in four dental institutes in the UK (Barts and the London, Kings College London, Cardiff and Dundee). The questionnaire explored satisfaction with undergraduate orthodontic teaching; students' perception of knowledge, based on General Dental Council learning outcomes; perceptions of the need for specialist involvement in the management of dental problems; interest in further training in orthodontics; and potential barriers to undertaking specialist training.Results The overall response rate was 66% (239/362). The majority of students (84.1%) were aware of GDC guidance in terms of undergraduate teaching. Students reported a preference for case-based and practical teaching sessions in orthodontics, with less interest in lectures or problem-based learning approaches. A high percentage were interested in further teaching in interceptive orthodontics (60.3%) and fixed appliance therapy (55.7%). Further training including specialist orthodontic training (36.4%), Invisalign (59%) and Six Month Smiles (41%) courses appealed to undergraduates. Levels of student debt, course fees and geographical issues were seen as potential barriers to formal, specialist training pathways.Conclusions Satisfaction with undergraduate orthodontic teaching is high and interest in further training, including specialist training pathways, continues to be high. While short-term orthodontics is not taught at undergraduate level, there appears to be an appetite to undertake alternatives to conventional orthodontics among dental students.

A comparison of two different techniques for early correction of Class III malocclusion.

OBJECTIVE: To compare the effectiveness of Reverse Twin-Block therapy (RTB) and protraction face mask treatment (PFM) with respect to an untreated control in the correction of developing Class III malocclusion. MATERIALS AND METHODS: A retrospective comparative study of subjects treated cases with either PFM (n  =  9) or RTB (n  =  13) and untreated matched controls (n  =  10) was performed. Both the PFM and control group samples were derived from a previously conducted clinical trial, and the RTB group was formed of consecutively treated cases. The main outcome variables assessed were skeletal and dental changes. Lateral cephalograms were taken at the start and end of treatment or during the observation period. Analysis of variance was used to compare changes in cephalometric variables arising during the study period in the lateral group. Linear regression analysis and an unpaired t-test were used to determine the impacts of treatment duration and gender, respectively. RESULTS: Significantly greater skeletal changes arose with PFM therapy than with RTB therapy or in the control group (SNA, SNB, and ANB; P < .001). The dentoalveolar effects of RTB therapy exceeded those of PFM treatment, with significantly more maxillary incisor proclination (P < .001) and mandibular incisor retroclination (P < .006) arising with treatment. CONCLUSIONS: Both appliances are capable of correction of Class III dental relationships; however, the relative skeletal and dental contributions differ. Skeletal effects, chiefly anterior maxillary translation, predominated with PFM therapy. The RTB appliance induced Class III correction, primarily as a result of dentoalveolar effects.

Bullying in schoolchildren - its relationship to dental appearance and psychosocial implications: an update for GDPs.

Bullying in school-aged children is a global phenomenon. The effects of bullying can be both short- and long-term, resulting in both physiological and psychological symptoms. It is likely that dental care professionals will encounter children who are subjected to bullying. The aim of this narrative review is to discuss the incidence of bullying, the types of bullying, the effects of bullying and the interventions aimed at combating bullying in schoolchildren. The role of dentofacial aesthetics and the relationship of bullying and the presence of a malocclusion are also discussed.

Intraoral Spitz naevus: a case report.

Intraoral occurrences of Spitz naevus are very rare, there being only one previously documented case in the literature. Here is reported a case of a young male who presented with a pigmented lesion of the upper labial mucosa which had the clinical appearance of a simple naevus. Excision biopsy confirmed this to be a Spitz naevus. This lesion shares histopathological similarities with malignant melanoma. Spitz naevus is a benign lesion, but malignant transformation has been reported and close monitoring is recommended.

Arteriovenous malformation of the mandible--a case report.

Both arteriovenous malformations (AVMs) and solitary bone cysts of the mandible are uncommon lesions. The latter can be considered fairly innocuous but AVMs require careful management. The following is a description of a case where an arteriovenous malformation of the mandible presented with mental nerve paraesthesia. However, radiographically the features appeared to be consistent with a solitary bone cyst. It is important for clinicians in both a primary and secondary care setting to be aware that this type of lesion can have life threatening complications.

Crystal structure of the B7-1/CTLA-4 complex that inhibits human immune responses.

Optimal immune responses require both an antigen-specific and a co-stimulatory signal. The shared ligands B7-1 and B7-2 on antigen-presenting cells deliver the co-stimulatory signal through CD28 and CTLA-4 on T cells. Signalling through CD28 augments the T-cell response, whereas CTLA-4 signalling attenuates it. Numerous animal studies and recent clinical trials indicate that manipulating these interactions holds considerable promise for immunotherapy. With the consequences of these signals well established, and details of the downstream signalling events emerging, understanding the molecular nature of these extracellular interactions becomes crucial. Here we report the crystal structure of the human CTLA-4/B7-1 co-stimulatory complex at 3.0 A resolution. In contrast to other interacting cell-surface molecules, the relatively small CTLA-4/B7-1 binding interface exhibits an unusually high degree of shape complementarity. CTLA-4 forms homodimers through a newly defined interface of highly conserved residues. In the crystal lattice, CTLA-4 and B7-1 pack in a strikingly periodic arrangement in which bivalent CTLA-4 homodimers bridge bivalent B7-1 homodimers. This zipper-like oligomerization provides the structural basis for forming unusually stable signalling complexes at the T-cell surface, underscoring the importance of potent inhibitory signalling in human immune responses.

Crystal structures of substrate binding to Bacillus subtilis holo-(acyl carrier protein) synthase reveal a novel trimeric arrangement of molecules resulting in three active sites.

BACKGROUND: Holo-(acyl carrier protein) synthase (AcpS), a member of the phosphopantetheinyl transferase superfamily, plays a crucial role in the functional activation of acyl carrier protein (ACP) in the fatty acid biosynthesis pathway. AcpS catalyzes the attachment of the 4'-phosphopantetheinyl moiety of coenzyme A (CoA) to the sidechain of a conserved serine residue on apo-ACP. RESULTS: We describe here the first crystal structure of a type II ACP from Bacillus subtilis in complex with its activator AcpS at 2.3 A. We also have determined the structures of AcpS alone (at 1.8 A) and AcpS in complex with CoA (at 1.5 A). These structures reveal that AcpS exists as a trimer. A catalytic center is located at each of the solvent-exposed interfaces between AcpS molecules. Site-directed mutagenesis studies confirm the importance of trimer formation in AcpS activity. CONCLUSIONS: The active site in AcpS is only formed when two AcpS molecules dimerize. The addition of a third molecule allows for the formation of two additional active sites and also permits a large hydrophobic surface from each molecule of AcpS to be buried in the trimer. The mutations Ile5-->Arg, Gln113-->Glu and Gln113-->Arg show that AcpS is inactive when unable to form a trimer. The co-crystal structures of AcpS-CoA and AcpS-ACP allow us to propose a catalytic mechanism for this class of 4'-phosphopantetheinyl transferases.

The bacterial cell-division protein ZipA and its interaction with an FtsZ fragment revealed by X-ray crystallography.

In Escherichia coli, FtsZ, a homologue of eukaryotic tubulins, and ZipA, a membrane-anchored protein that binds to FtsZ, are two essential components of the septal ring structure that mediates cell division. Recent data indicate that ZipA is involved in the assembly of the ring by linking FtsZ to the cytoplasmic membrane and that the ZipA-FtsZ interaction is mediated by their C-terminal domains. We present the X-ray crystal structures of the C-terminal FtsZ-binding domain of ZipA and a complex between this domain and a C-terminal fragment of FtsZ. The ZipA domain is a six-stranded beta-sheet packed against three alpha-helices and contains the split beta-alpha-beta motif found in many RNA-binding proteins. The uncovered side of the sheet incorporates a shallow hydrophobic cavity exposed to solvent. In the complex, the 17-residue FtsZ fragment occupies this entire cavity of ZipA and binds as an extended beta-strand followed by alpha-helix. An alanine-scanning mutagenesis analysis of the FtsZ fragment was also performed, which shows that only a small cluster of the buried FtsZ side chains is critical in binding to ZipA.

Crystal structure of human cytosolic phospholipase A2 reveals a novel topology and catalytic mechanism.

Cytosolic phospholipase A2 initiates the biosynthesis of prostaglandins, leukotrienes, and platelet-activating factor (PAF), mediators of the pathophysiology of asthma and arthritis. Here, we report the X-ray crystal structure of human cPLA2 at 2.5 A. cPLA2 consists of an N-terminal calcium-dependent lipid-binding/C2 domain and a catalytic unit whose topology is distinct from that of other lipases. An unusual Ser-Asp dyad located in a deep cleft at the center of a predominantly hydrophobic funnel selectively cleaves arachidonyl phospholipids. The structure reveals a flexible lid that must move to allow substrate access to the active site, thus explaining the interfacial activation of this important lipase.

Independent folding and ligand specificity of the C2 calcium-dependent lipid binding domain of cytosolic phospholipase A2.

The Ca(2+)-dependent lipid binding domain of the 85-kDa cytosolic phospholipase A2 (cPLA2) is a homolog of C2 domains present in protein kinase C, synaptotagmin, and numerous other proteins involved in signal transduction. NH2-terminal fragments of cPLA2 spanning the C2 domain were expressed as inclusion bodies in Escherichia coli, extracted with solvent to remove phospholipids, and refolded to yield a domain capable of binding phospholipid vesicles in a Ca(2+)-dependent manner. Unlike other C2 domains characterized to date, the cPLA2 C2 domain bound preferentially to vesicles comprised of phosphatidylcholine in response to physiological concentrations of Ca2+. Binding of the cPLA2 C2 domain to vesicles in the presence of excess Ca2+ chelator was induced by high concentrations of salts that promote hydrophobic interactions. Despite the selective hydrolysis of arachidonyl-containing phospholipid vesicles by cPLA2, the cPLA2 C2 domain did not discriminate among phospholipid vesicles containing saturated or unsaturated sn-2 fatty acyl chains. Moreover, the cPLA2 C2 domain bound to phospholipid vesicles containing sn-1 and -2 ether linkages and sphingomyelin at Ca2+ concentrations that caused binding to vesicles containing ester linkages, demonstrating that the carbonyl oxygens of the sn-1 and -2 ester linkage are not critical for binding. These results suggest that the cPLA2 C2 domain interacts primarily with the headgroup of the phospholipid. The cPLA2 C2 domain displayed selectivity among group IIA cations, preferring Ca2+ approximately 50-fold over Sr2+ and nearly 10,000-fold over Ba2+ for vesicle binding. No binding to vesicles was observed in the presence of greater than 10 mM Mg2+. Such strong selectivity for Ca2+ over Mg2+ reinforces the view that C2 domains link second messenger Ca2+ to signal transduction events at the membrane.

1.9 A crystal structure of interleukin 6: implications for a novel mode of receptor dimerization and signaling.

Interleukin 6 (IL-6) has many biological activities in vivo, and deregulation has been implicated in many disease processes. IL-6, a 185 amino acid polypeptide was refolded, purified and crystallized. The crystals diffracted to beyond 1.9 A and the structure was solved using single isomorphous replacement. The X-ray structure of IL-6 is composed of a four helix bundle linked by loops and an additional mini-helix. 157 out of 185 residues are well defined in the final structure, with 18 N-terminal and 8 A-B loop amino acids displaying no interpretable electron density. The three-dimensional structure has been used to construct a model of IL-6 interacting with the IL-6 receptor (alpha-chain) and gp130 (beta-chain) that gives new insight into the process of molecular recognition and signaling. Based on this model, we predict a fourth binding site on IL-6, a low affinity IL-6-IL-6 interaction, which may be necessary for the sequential assembly of a functional hexameric IL-6 receptor complex.

A novel cytosolic calcium-independent phospholipase A2 contains eight ankyrin motifs.

We report the purification, molecular cloning, and expression of a novel cytosolic calcium-independent phospholipase A2 (iPLA2) from Chinese hamster ovary cells, which lacks extended homology to other phospholipases. iPLA2 is an 85-kDa protein that exists as a multimeric complex of 270-350 kDa with a specific activity of 1 micromol/min/mg. The full-length cDNA clone encodes a 752-amino acid cytoplasmic protein with one lipase motif (GXS465XG) and eight ankyrin repeats. Expression of the cDNA in mammalian cells generates an active 85-kDa protein. Mutagenesis studies show that Ser465 and the ankyrin repeats are required for activity. We demonstrate that iPLA2 selectively hydrolyzes the sn-2 over sn-1 fatty acid by 5-fold for 1,2-dipalmitoyl phosphatidylcholine in a mixed micelle. Moreover, we found the fatty acid preference at the sn-2 position to be highly dependent upon substrate presentation. However, iPLA2 does have a marked preference for 1,2-dipalmitoyl phosphatidic acid presented in a vesicle, generating the lipid second messenger lysophosphatidic acid. Finally the enzyme is able to hydrolyze the acetyl moiety at the sn-2 position of platelet-activating factor.

Complete 1H, 15N and 13C assignments, secondary structure, and topology of recombinant human interleukin-6.

Essentially complete backbone and side-chain 1H, 15N and 13C resonance assignments for the 185-amino-acid cytokine interleukin-6 (IL-6) are presented. NMR experiments were performed on uniformly [15N]- and [15N,13C]-labeled recombinant human IL-6 (rIL-6) using a variety of heteronuclear NMR experiments. A combination of 13C-chemical shift, amide hydrogen-bond exchange, and 15N-edited NOESY data allowed for analysis of the secondary structure of IL-6. The observed secondary structure of IL-6 is composed of loop regions connecting five alpha-helices, four of which are consistent in their length and disposition with the four-helix bundle motif present in other related cytokines and previously postulated for IL-6. In addition, the topology of the overall fold was found to be consistent with a left-handed up-up-down-down four-helix bundle based on a number of long-range interhelical NOEs. The results presented here provide deeper insight into structure-function relationships among members of the four-helix bundle family of proteins.

Characterization of an RNase H deficient mutant of human immunodeficiency virus-1 reverse transcriptase having an aspartate to asparagine change at position 498.

It has been proposed that Asp-443, Glu-478, and Asp-498 are important in RNase H mediated catalysis by human immunodeficiency virus-1 reverse transcriptase (Davies J.F., Hostomska, Z. Hostomsky, Z., Jordan, S.R. and Matthews, D.A. (1991) Science 251, 88-95; Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363). Single point mutations at either position 443 (Mizrahi, V., Usdin, M.T., Harington, A. and Dudding, L.R. (1990) Nucleic Acids Res. 18, 5359-5363) or 478 (Schatz, O., Cromme, F.V., Grüninger-Leitch, F. and Le Grice, S.F.J. (1989) FEBS Lett. 257, 311-314) severely inhibit RNase H activity but have only small effects on polymerase activity. We show here that a single mutation at position 498 of Asp to Asn (mutant D498N) results in a stable enzyme with a 20-fold reduction in the ratio of RNase H to polymerase activity. The mutant and wild type enzymes were equally processive, paused in the same locations, and extended primers at the same rate during DNA synthesis on a heteropolymeric RNA template. The rate of elongation on the homopolymeric template poly(rA) was also the same. The results indicate that the mutation does not affect normally measured catalytic parameters of the polymerase function of the enzyme. D498N catalyzed strand transfer synthesis on homopolymeric, but not heteropolymeric templates, indicating that RNase H activity is not required for the former activity, but is for the latter.

Human immunodeficiency virus 1 reverse transcriptase. Template binding, processivity, strand displacement synthesis, and template switching.

We have analyzed the kinetics of DNA synthesis catalyzed by reverse transcriptase from human immunodeficiency virus 1 (HIV-1). Reverse transcriptase, overproduced in Escherichia coli and purified to homogeneity, has polymerase and RNase H activity. Reverse transcriptase forms a stable complex with poly(rA).oligo(dT) primer-templates in the absence of Mg2+ and dTTP with an equilibrium dissociation constant of 3 nM. Synthesis from these preformed complexes can be initiated, and restricted to a single processive cycle, by the simultaneous addition of Mg2+, dTTP, and excess competitor RNA. Preformed complexes decay with a maximal half-life of 2-3 min. Synthesis on poly(rA) templates is processive with an incorporation rate of 10-15 nucleotides/s at 37 degrees C. Processivity varies widely with the template used, increasing from a few to greater than 300 nucleotides in the order: poly(dA) less than double-stranded DNA less than single-stranded DNA less than single-stranded RNA less than poly(rA). On double-stranded DNA reverse transcriptase catalyzes limited strand-displacement synthesis of up to 50 nucleotides. On RNA-DNA hybrids significant DNA synthesis is observed only after degradation of the RNA strand by the RNase H activity of reverse transcriptase. Intermolecular strand switching occurs with poly(rA) templates. At low ionic strength reverse transcriptase can use multiple templates with a single primer, leading to products of greater than template length. Reverse transcriptase and primer do not have to dissociate during the exchange of template strands, thus allowing processive DNA synthesis across template borders.