Abstracts of the 24th international isotope society (UK group) symposium: synthesis and applications of labelled compounds 2015.

The 24th annual symposium of the International Isotope Society's United Kingdom Group took place at the Møller Centre, Churchill College, Cambridge, UK on Friday 6th November 2015. The meeting was attended by 77 delegates from academia and industry, the life sciences, chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral presentations, short 'flash' presentations in association with particular posters and poster presentations. The scientific areas covered included isotopic synthesis, regulatory issues, applications of labelled compounds in imaging, isotopic separation and novel chemistry with potential implications for isotopic synthesis. Both short-lived and long-lived isotopes were represented, as were stable isotopes. The symposium was divided into a morning session chaired by Dr Rebekka Hueting (University of Oxford, UK) and afternoon sessions chaired by Dr Sofia Pascu (University of Bath, UK) and by Dr Alan Dowling (Syngenta, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, UK).

Practically convenient and industrially-aligned methods for iridium-catalysed hydrogen isotope exchange processes.

The use of alternative solvents in the iridium-catalysed hydrogen isotope exchange reaction with developing phosphine/NHC Ir(I) complexes has identified reaction media which are more widely applicable and industrially acceptable than the commonly employed chlorinated solvent, dichloromethane. Deuterium incorporation into a variety of substrates has proceeded to deliver high levels of labelling (and regioselectivity) in the presence of low catalyst loadings and over short reaction times. The preparative outputs have been complemented by DFT studies to explore ligand orientation, as well as solvent and substrate binding energies within the catalyst system.

On-site determination of formaldehyde: a low cost measurement device for museum environments.

A trapping reagent for formaldehyde, based on the pararosaniline reaction, was evaluated as a method of determination of formaldehyde in the aqueous or vapour phase. Collection of formaldehyde vapour relied upon passive diffusion of formaldehyde into the trapping media and quantitative results were obtained without the need for liquid impingers, bubblers or active sampling pumps. Moreover, a novel, hand-held absorption spectrophotometric measurement device was designed to provide on-site, quantitative measurements. It is proposed that the full measurement system devised would be ideally suited to specific sampling applications such as those found in museum enclosures.

Maxillary retention: is longer better?

Two different maxillary retention regimes were compared to ascertain if differences in posttreatment relapse existed. The patient pool was derived from subjects being treated at two orthodontic departments in the west of Scotland. Group 1 (20 patients) followed a 6 month regime using removable upper Hawley retainers for a period of 3 months full time and 3 months nights only. Group 2 (18 patients) followed a 1 year regime of 6 months full time and 6 months nights only. The results revealed that maxillary incisor alignment, as determined by Little's irregularity index, had relapsed by an average of 50 per cent of the end of retention value 3 months out of retention in Group 1 but only 23 per cent in Group 2. Although the actual mean values for relapse were 0.77 and 0.23 mm, respectively, seven subjects in Group 1 showed relapse of more than 3 mm as compared with only one in Group 2. This suggests that retaining a case for 1 year rather than 6 months is clinically beneficial.

A clinical trial of light cure acrylic resin for orthodontic use.

OBJECTIVE: To ascertain whether or not the less porous surface associated with visible light cure appliances and the absence of free monomer had any measurable affect upon mucosal erythema, and to assess the durability of such appliances in a clinical context. DESIGN: A prospective randomized trial of visible light cure (Triad VLC) and autopolymerizing (Orthoresin) acrylic resin used as orthodontic base plate materials. SETTING: University Dental Hospital and School. SUBJECTS: Fifty subjects from a consecutively enrolled sample of 69 (19 drop outs) for removable appliance therapy (23 VLC, 27 AP). OUTCOME MEASURES: Erythema meter scores and appliance breakages. RESULTS: No statistical difference in mucosal erythema between the two materials was found. Fifty-two per cent of VLC appliances broke during a 6-month period, as opposed to 7 per cent of AP appliances. CONCLUSIONS: VLC appears to have no clinically beneficial effect on the oral mucosa compared with AP. VLC appliances are currently not sufficiently durable to make them a viable alternative to AP appliances.

Key tricyclic synthetic intermediates for the preparation of the sesquiterpenes alpha- and beta-cedrene.

A completely novel and direct route towards the synthesis of the natural sesquiterpenes alpha-cedrene and beta-cedrene delivered the compounds (3 beta,3a beta,7 beta)-(+/-)-6,6-ethylenedioxy-3,8,8-trimethyl-2,3,3a,4,5,6,7,8-octahydro-3a,7-methanoazulen-2-one, C(16)H(22)O(3), and (3 beta,3a beta,7 beta,8a alpha)-(+/-)-6,6-ethylenedioxy-3,8,8-trimethyl-1,2,3,3a,4,5,6,7,8,8a-decahydro-3a,7-methanoazulen-2-one, C(16)H(24)O(3), at key stages of the preparative programme. Structural elucidation showed the latter compound to have added an H atom to the same face of the cyclopentenone ring as that occupied by the methyl substituent, and also allowed correct isomer identification for further reaction.

Development of a three-dimensional imaging system for analysis of facial change.

The objective of this report is to present facial changes produced by the Twin Block appliance in three-dimensional visual and numerical formats. Using a C3D system, stereophotogrammetric records were made of two children with Class II division 1 malocclusions prescribed treatment with a Twin Block appliance. Three-dimensional images of their faces were captured. Comparison of specified regions of the three-dimensional images was made using landmark identification and superimpositions. In addition to obvious visual evidence, numerical data in the form of surface area measurements were also generated. The three-dimensional, C3D, system, provides a flexible imaging tool which should become increasingly useful as more improvements are made.

Formal total synthesis of (+/-)-alpha- and beta-cedrene by preparation of cedrone. Construction of the tricyclic carbon skeleton by the use of a highly efficient intramolecular Khand annulation.

The cedrene carbon skeleton was rapidly assembled from a simple monocyclic precursor by the strategic use of a high yielding intramolecular Khand cyclization reaction. Further synthetic manipulations provided a concise formal total synthesis of alpha- and beta-cedrene. Reaction: see text.

Magnesium bisamides as reagents in synthesis.

As part of the continued requirement for more selective reagents in organic synthesis, magnesium bisamides are becoming established as a class of organometallic bases with considerable potential. Their relatively mild reactivity, combined with their high degree of steric congestion, leads to a distinct class of reagents with significantly different chemo-, regio-, stereo- and enantioselectivities when compared with existing species and protocols.

Enantioselective deprotonation reactions using polymer-supported chiral magnesium amide bases.

Novel and readily accessible polymer-supported chiral magnesium amide reagents have been prepared and shown to be effective in the asymmetric deprotonation of a series of prochiral cyclohexanones, affording good to excellent levels of both conversion and enantiomeric ratio (up to 93:7); the Merrifield-based chiral amine species has been shown to be readily recyclable.

Describing shape changes in the human mandible using elliptical Fourier functions.

Elliptical Fourier functions (EFF) were generated for the boundary outline of the mandibular form in 24 non-orthodontic growth study subjects at 9, 11, 13, and 15 years of age. The mean residual fit (observed versus predicted points) of the mandibular form was 0.11 mm, with a range from 0.09 to 0.14 mm, suggesting an accurate fit. The mean plot for each of the four age groups was area standardized and superimposed on the centroid. Shape changes in males and females were found to be similar. No significant shape changes were found between 9 and 11 years. Shape changes were observed in the lower incisor area, the mental region, the body of the mandible, and the gonial angle area between 11 and 15 years. These changes coincided with the onset of the pubertal growth spurt.

Orthodontic treatment with fixed appliances in the General Dental Service in Scotland.

The records of 128 subjects treated by orthodontic specialists with fixed appliances in the General Dental Service in Scotland were randomly selected from the Scottish Dental Practice Board for analysis. The results of the study revealed that: (1) Mean post-treatment Peer Assessment Rating was 7.8 +/- 4.6 PAR points. (2) Mean reduction in PAR score was 14.9 +/- 10.6 PAR points. (3) Mean percentage reduction in PAR was 59 per cent. (4) Twenty-eight per cent of the cases were 'greatly improved', 15 per cent of the cases were made 'worse or no different'. (5) Median duration of treatment was 15 months, with a range of 2-41 months. (6) Multiple regression analysis showed that 82 per cent of the variability of PAR change could be predicted by the pretreatment PAR scores and the number of arches treated. Post-treatment PAR scores and duration of treatment could not be predicted with adequate reliability. It was concluded that although about 75 per cent of the cases were treated to at least acceptable alignment and occlusion, the modest average percentage reduction in PAR score could be explained by the low average initial PAR score and the borderline need for treatment in many cases.

The first orthodontic diploma.

The advent of the Inter-Collegiate Membership in Orthodontics in the year 2000 will mark the end of an orthodontic diploma specific to the Royal College of Physicians and Surgeons of Glasgow. The Diploma in Dental Orthopaedics (RCPS) was the first orthodontic diploma in the United Kingdom. The fact that such a diploma has existed first as a DDO and latterly as the MDO (Membership) for some 50 years is remarkable in view of the relative infancy of most dental specialties and the fact that the General Dental Council has instigated a specialist register in orthodontics as recently as 1998. It was 1965, before other specialty diplomas became available in the British Isles, with the introduction of the FFD by the Royal College of Surgeons in Ireland.

An evaluation of CASES--an educational audit programme for orthodontists.

A regional approach to a national clinical audit programme in orthodontics in the UK is described and evaluated. The programme was designed using the CRISIS criteria for effective continuing education. Programme participants completed duplicate questionnaires on 6 simulated patient scenarios, chosen for their relevance to everyday practice while posing important clinical dilemmas. The participation rate was 77% from hospital-based practitioners and 29% from specialist practitioners. Feedback to programme participants was given in the form of histograms, and provided a snapshot of national approaches to patient investigation, treatment and expected outcomes. A commentary on the data and references to appropriate articles in the literature were included. Evaluation of the programme by questionnaire survey showed that it was extensively used by hospital-based practitioners. It is concluded that the model used provided an effective and efficient framework for conducting clinical audit and delivering continuing education to the hospital-based group.

Light-curing acrylic resin as an orthodontic baseplate material.

Heat-curing autopolymerizing (self-cure or cold-cure), thermoplastic, and light-curing acrylic resin are the most commonly used orthodontic baseplate materials. While cured acrylic resins present few problems to the patient, in the laboratory acrylic resin has to be sprayed, mixed, or packed in a fume-extraction unit because of the harmful fumes emitted by the raw inflammable chemicals. Light-curing material, on the other hand, is virtually nonflammable and has virtually no aroma. A light-cure technique for the construction of orthodontic baseplates is described. While buildup of the baseplate is slightly slower than for self-cured material, the shorter time involved in trimming and polishing means that overall construction is faster. It is easier to obtain a uniform thickness with light-cured material, and it provides superior fit. These results, however, are subject to more extensive clinical trials. The only apparent disadvantage is the fine powder produced during trimming. Even with a bench equipped with an extraction unit, it is advisable to use a face mask to prevent the inhalation of dust.

An adult with a severe Class II division 1 malocclusion: Frances' case.

This article describes treatment options for an adult with a severe Class II division 1 malocclusion. The opinions of British orthodontists, as obtained through the CASES project, are summarized and the patient's actual treatment is discussed.