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Biomedical subjects

J P McDonald

Publications and source records attributed to J P McDonald.

At least 19 recordsLinked to original sources

Patients' and sleeping partners' experience of treatment for sleep-related breathing disorders with a mandibular repositioning splint.

AIM: To determine in detail the complications associated with the use of mandibular repositioning splints (MRS) to treat sleep-related breathing disorders. METHOD: This prospective cross-sectional cohort study audits the management with mandibular repositioning splints of 121 patients suffering from sleep-related breathing disorders. Investigation of patients' and sleeping partners' perspectives on treatment was undertaken with the use of a questionnaire based study. RESULTS: Sixty-eight per cent of respondents reported that they were compliant with treatment; various side effects were reported of which excess salivation was the most common. Investigation of sleeping partners' perspectives revealed that 70% felt that their partners' snoring was improved and 47% felt that their partner's breathing pauses during sleep were reduced. Sixty-four per cent of the sleeping partners also reported that their own sleep pattern had improved since their partner's treatment. CONCLUSION: Mandibular repositioning splints used in the manner described by this paper are demonstrated to have a good compliance rate, provide successful treatment and exhibit only minor, reversible side effects.

Adult↗

The role of the dental surgeon in an integrated care pathway for the treatment of breathing difficulties.

We live in a professional environment in which the role of the dental surgeon is changing more rapidly than perhaps ever before. The concept of team working towards more efficient and focused delivery of care to our patients is one of the major developments, both within the practice environment through professionals complementary to dentistry, and indeed through medical and surgical colleagues in dealing with some of the wider aspects of holistic healthcare.

Adult↗

The relationship between severity of obstructive sleep apnoea/hypopnoea syndrome (OSAHS) and lateral cephalometric radiograph values: a clinical diagnostic tool.

BACKGROUND: This prospective cross-sectional cohort study examined the relationship between radiographic anatomy and the severity of OSAHS. The severity of OSAHS can be measured subjectively in terms of the Epworth scale and objectively in terms of the apnoea/hypopnoea Index (AHI). METHODS: 121 lateral cephalometric radiographs were traced under uniform conditions and a series of 56 landmarks identified, from which 48 angular and linear measurements were made. Significant changes occurred when comparison of these measurements with the severity of OSAHS were made. RESULTS: Body mass index (BMI), the maxillary-mandibular planes angle (MMPA) and the linear measurement between points 7 and 12, (the pharyngeal dimension measured from the tip of the soft palate to the corresponding horizontal point on the posterior pharynx), increased significantly with increasing severity of OSAHS as measured by the Epworth score. Overjet, lower lip length, and the distance from the hyoid bone to a point B on the mandible all increased significantly with increasing severity of OSAHS, as measured by the AHI. The hyoid bone was found to rotate counter clockwise as the severity of OSAHS increased, as a result the distance between the most anterior superior point on the hyoid bone and the maxillary plane was seen to decrease as severity of OSAHS increased in terms of AHI. CONCLUSIONS: Some radiographic anatomical features show significant change as the severity of OSAHS increases and these features could be used in the identification of patients who have severe OSAHS. The Logit equation derived from the findings of this study may also be a useful clinical tool in predicting the likelihood of a subject suffering from severe OSAHS.

Body Mass Index↗

An investigation into the relationship between the severity of obstructive sleep apnoea/hypopnoea syndrome and the vertical position of the hyoid bone.

OBJECTIVE: This study aimed to identify a correlation of diagnostic clinical significance between the vertical position of the hyoid bone in relation to structures within the dentofacial skeleton and: (1) The severity of obstructive sleep apnoea hypopnoea syndrome, (OSAHS), (2) Decisions relating to the management of the condition. DESIGN AND SETTING: Randomised retrospective survey of cephalometric records of subjects having been diagnosed as suffering with OSAHS by in patient overnight polysomnographic testing at the Edinburgh Royal Infirmary Sleep Centre, 2001-2002. MATERIALS AND METHODS: Pre-polysomnograph orthoposition lateral cephalograms of 94 subjects tested, during the period from April 1996 to September 1997, were randomly selected and traced following strict adherence to standard protocol. Edentulous arches (one or both) formed the only exclusion criterion owing to obvious effects upon vertical dimensions of the cervico-pharyngeal region. Measurement of the vertical position of the hyoid bone was made relative to a number of planes validated by numerous previous cephalometric investigations, and these were recorded along with the apnoea/hypopnoea index (AHI), and subsequent management (mandibular repositioning appliances (MRA) / continuous positive airway pressure (CPAP)). Correlations between measurements and AHI were investigated using Spearman's Correlation Coefficients, and analysis of the relationship between hyoid bone position and management groups was undertaken using Wilcoxon Ranked Sum Testing. DISCUSSION AND RESULTS: Statistically significant correlations were found between all linear measurements locating the hyoid bone in the vertical plane and subject AHI. The linear relationships were less reliable for subjects with AHI > 100, possibly due to a breakdown in the body's ability to respond posturally in order to maintain airway patency in more extreme cases. When the treatment groups (MRA/CPAP) were considered independently there was found to be a clear delineation between the two groups at a length of 120 mm between the sella (S- a point upon the anterior cranial base) and the hyoid (H). This, in turn, may suggest that cephalometric radiographs may be used as a reproduciable diagnostic tool.

Cephalometry↗

A review of surgical treatment for obstructive sleep apnoea/hypopnoea syndrome.

Surgical intervention and treatment of OSAHS and snoring has a considerable history, encompassing a number of operations all of which have the intention of reducing or by-passing the pharyngeal resistance that occurs during sleep. Review of the published literature presents some problems, however, due to the ethical difficulties of undertaking randomised controlled trials in surgery. Uncontrolled trials are less satisfactory due to the large 'regression to the mean' and placebo effects. However, there is a considerable body of literature available relating to surgical intervention.

Humans↗

Altered nucleotide misinsertion fidelity associated with poliota-dependent replication at the end of a DNA template.

A hallmark of human DNA polymerase iota (poliota) is the asymmetric fidelity of replication at template A and T when the enzyme extends primers annealed to a single-stranded template. Here, we report on the efficiency and accuracy of poliota-dependent replication at a nick, a gap, the very end of a template and from a mispaired primer. Poliota cannot initiate synthesis on a nicked DNA substrate, but fills short gaps efficiently. Surprisingly, poliota's ability to blunt-end a 1 bp recessed terminus is dependent upon the template nucleotide encountered and is highly erroneous. At template G, both C and T are inserted with roughly equal efficiency, whilst at template C, C and A are misinserted 8- and 3-fold more often than the correct base, G. Using substrates containing mispaired primer termini, we show that poliota can extend all 12 mispairs, but with differing efficiencies. Poliota can also extend a tandem mispair, especially when it is located within a short gap. The enzymatic properties of poliota appear consistent with that of a somatic hypermutase and suggest that poliota may be one of the low-fidelity DNA polymerases hypothesized to participate in the hypermutation of immunoglobulin variable genes in vivo.

Animals↗

5'-Deoxyribose phosphate lyase activity of human DNA polymerase iota in vitro.

DNA polymerase iota (pol iota) is one of several recently discovered DNA polymerases in mammalian cells whose function is unknown. We report here that human pol iota has an intrinsic 5'-deoxyribose phosphate (dRP) lyase activity. In reactions reconstituted with uracil-DNA glycosylase (UDG), apurinic/apyrimidinic (AP) endonuclease and DNA ligase I, pol iota can use its dRP lyase and polymerase activities to repair G*U and A*U pairs in DNA. These data and three distinct catalytic properties of pol iota implicate it in specialized forms of base excision repair (BER).

Amino Acid Sequence↗

DNA polymerase iota and related rad30-like enzymes.

Until recently, the molecular mechanisms of translesion DNA synthesis (TLS), a process whereby a damaged base is used as a template for continued replication, was poorly understood. This area of scientific research has, however, been revolutionized by the finding that proteins long implicated in TLS are, in fact, DNA polymerases. Members of this so-called UmuC/DinB/Rev1/Rad30 superfamily of polymerases have been identified in prokaryotes, eukaryotes and archaea. Biochemical studies with the highly purified polymerases reveal that some, but not all, can traverse blocking lesions in template DNA. All of them share a common feature, however, in that they exhibit low fidelity when replicating undamaged DNA. Of particular interest to us is the Rad30 subfamily of polymerases found exclusively in eukaryotes. Humans possess two Rad30 paralogs, Rad30A and Rad30B. The RAD30A gene encodes DNA polymerase eta and defects in the protein lead to the xeroderma pigmentosum variant (XP-V) phenotype in humans. Very recently RAD30B has also been shown to encode a novel DNA polymerase, designated as Pol iota. Based upon in vitro studies, it appears that Pol iota has the lowest fidelity of any eukaryotic polymerase studied to date and we speculate as to the possible cellular functions of such a remarkably error-prone DNA polymerase.

Bacterial Proteins↗

Biochemical characterization of human DNA polymerase iota provides clues to its biological function.

The human RAD30B gene has recently been shown to encode a novel DNA polymerase, DNA polymerase iota (poliota). The role of poliota within the cell is presently unknown, and the only clues to its cellular function come from its biochemical characterization in vitro. The aim of this short review is, therefore, to summarize the known enzymic activities of poliota and to speculate as to how these biochemical properties might relate to its in vivo function.

Base Pair Mismatch↗

Misinsertion and bypass of thymine-thymine dimers by human DNA polymerase iota.

Human DNA polymerase iota (pol(iota)) is a recently discovered enzyme that exhibits extremely low fidelity on undamaged DNA templates. Here, we show that poliota is able to facilitate limited translesion replication of a thymine-thymine cyclobutane pyrimidine dimer (CPD). More importantly, however, the bypass event is highly erroneous. Gel kinetic assays reveal that pol(iota) misinserts T or G opposite the 3' T of the CPD approximately 1.5 times more frequently than the correct base, A. While pol(iota) is unable to extend the T.T mispair significantly, the G.T mispair is extended and the lesion completely bypassed, with the same efficiency as that of the correctly paired A. T base pair. By comparison, pol(iota) readily misinserts two bases opposite a 6-4 thymine-thymine pyrimidine-pyrimidone photoproduct (6-4PP), but complete lesion bypass is only a fraction of that observed with the CPD. Our data indicate, therefore, that poliota possesses the ability to insert nucleotides opposite UV photoproducts as well as to perform unassisted translesion replication that is likely to be highly mutagenic.

Base Pair Mismatch↗

poliota, a remarkably error-prone human DNA polymerase.

The Saccharomyces cerevisiae RAD30 gene encodes DNA polymerase eta. Humans possess two Rad30 homologs. One (RAD30A/POLH) has previously been characterized and shown to be defective in humans with the Xeroderma pigmentosum variant phenotype. Here, we report experiments demonstrating that the second human homolog (RAD30B), also encodes a novel DNA polymerase that we designate poliota. poliota, is a distributive enzyme that is highly error-prone when replicating undamaged DNA. At template G or C, the average error frequency was approximately 1 x 10(-2). Our studies revealed, however, a striking asymmetry in misincorporation frequency at template A and T. For example, template A was replicated with the greatest accuracy, with misincorporation of G, A, or C occurring with a frequency of approximately 1 x 10(-4) to 2 x 10(-4). In dramatic contrast, most errors occurred at template T, where the misincorporation of G was, in fact, favored approximately 3:1 over the correct nucleotide, A, and misincorporation of T occurred at a frequency of approximately 6.7 x 10(-1). These findings demonstrate that poliota is one of the most error-prone eukaryotic polymerases reported to date and exhibits an unusual misincorporation spectrum in vitro.

Base Sequence↗

Effect of rapid maxillary expansion on skeletal, dental, and nasal structures: a postero-anterior cephalometric study.

The purpose of this study was to compare the transverse dimensions of skeletal, dental, and nasal structures of a group of patients with maxillary narrowness before and after rapid maxillary expansion (RME) with an untreated control group using postero-anterior (PA) cephalometric radiographs. The material consisted of PA cephalograms of 25 children with a posterior crossbite (mean age 13 years 4 months), and 25 age- and sex-matched controls (mean age 13 years 11 months). Both groups consisted of 20 females and five males. Thirty-four reference points were digitized using the Dentofacial Planner software program. The 17 variables studied consisted of six skeletal, four dental, and seven intra-nasal linear measurements. Student's t-tests were used to compare the differences between the groups, and the effect of RME on skeletal, dental, and nasal structures. RME produced small, but statistically significant changes in maxillary width, upper and lower molar widths, the width between upper central incisor apices, and intra-nasal width. When compared with previous studies, the changes observed were similar for patients of a similar age group, but less than reported for a younger population. There is some evidence that the pattern of expansion produced by RME will vary depending on the age and maturity of the subject.

Adolescent↗

A survey of undergraduate orthodontic education in 23 European countries.

This paper reports on a survey of teaching contents and time allocation within the undergraduate orthodontic curriculum in European countries in 1997, and on whether or not these countries set a formal undergraduate examination in orthodontics. A questionnaire and an explanatory letter were mailed to all members of the EURO-QUAL BIOMED II project. Answers were validated during a meeting of project participants and by fax when necessary. Completed questionnaires, which were subsequently validated, were returned by orthodontists from 23 countries. They indicated that orthodontics was taught in all undergraduate curriculums of the countries surveyed. The number of hours in the undergraduate curriculum devoted to orthodontics was reported as varying from 135 to 500 hours with a mean of 245 hours. The time reported as allocated to theory, clinical practice, laboratory work, diagnosis, and treatment planning varied widely. In general, clinical practice and theory were reported as being allocated most curriculum hours, whilst diagnosis, laboratory work, and treatment planing were reported as receiving relatively less time. Removable appliances were reported to be taught in 22 of the 23 countries, functional appliances in 21 countries and fixed appliances in 17 countries. An undergraduate examination in orthodontics was reported by 20 countries. It was concluded that orthodontics occupies a small proportion of the undergraduate curriculum in dentistry in most countries, the emphasis is on theory and clinical work, and that removable appliances, functional appliances, and certain aspects of fixed appliances are taught in the majority of countries that responded to the questionnaire

Curriculum↗

A survey of postgraduate (specialist) orthodontic education in 23 European countries.

This paper reports on a survey of the duration, funding, and assessment of postgraduate specialist orthodontic training, the requirement for postgraduate training prior to entering specialist orthodontic training and registration of specialist orthodontists in Europe. A questionnaire and explanatory letter were mailed to all members of the EURO-QUAL BIOMED II project. Answers were validated during a meeting of project participants and by fax, when necessary. Completed questionnaires which were subsequently validated, were returned by orthodontists from 23 countries. The results indicated that a period of postgraduate training, prior to entering specialist orthodontic training was required in 12 of the responding countries. Specialist orthodontic training was reported as lasting 2 years in three countries, 3 years in 17, and for 4 years in three. Part-time training was reported as a possibility in four countries. In 21 of the 23 countries specialist training was reported to take place in full or part within universities, with some training taking place in government clinics in four countries. In five countries some or all training was reported to take place in specialist practices. Training was said to be funded solely or partially by governments in 15 of the 23 countries, to be solely self-funded in five countries, and partly or solely funded by universities in six countries. A final examination at the end of specialist training was reported to be held in 21 of the 23 countries. The nature of this examination varied widely and there was no such examination in two countries. Twelve of the 23 countries reported that they had a specialist register for orthodontics; 11 that they had no register. In none of the countries surveyed was there a requirement for those on a register to undergo periodic reassessment of competence once they are on the register. It was concluded that there was wide diversity in all aspects of specialist orthodontic training and registration within the countries surveyed.

Credentialing↗

A survey of perceived problems in orthodontic education in 23 European countries.

This paper reports on a survey of perceived problems in the provision of orthodontic education at the stages of undergraduate, postgraduate, and continuing professional education (CPE) in 23 European countries in 1997. A questionnaire, together with an explanatory letter, was mailed to all members of the EUROQUAL II BIOMED project. Answers were validated during a meeting of project participants and by further correspondence, when necessary. The topics covered in the questionnaire were adequacy of funding, numbers of orthodontic teachers, availability of equipment, regulations, training centres, numbers of orthodontists, availability of books, journals, and information technology. Completed questionnaires were returned by orthodontists from all 23 countries. Respondents from seven countries did not answer all questions. Respondents reported a perceived almost universal lack of adequate funding for postgraduate orthodontic training (from 18 out of 20 countries) and, to a lesser extent, at undergraduate (13 out of 20 countries) and CPE levels (17 out of 21 countries). Respondents from 12 of the 20 countries reported adequate numbers of qualified teachers at undergraduate level, but only seven out of 18 at postgraduate level and eight out of 19 for CPE. Lack of suitable equipment was reported as a more frequent problem by central and eastern European countries (six out of 20 countries at undergraduate level, eight out of 20 countries at postgraduate level, and 12 out of 19 at CPE level). Too few or too many regulations were only perceived to be a problem by the respondent from one country out of 19 at undergraduate level, by seven out of 19 at postgraduate level, and by eight out of 16 at CPE level). Lack of training centres was more frequently reported as a problem by respondents from central and eastern European countries, but was generally not perceived as a problem by respondents from west European countries. Respondents from seven countries reported a lack of training centres for CPE. Respondents from six countries reported that they perceived there to be too many orthodontists at postgraduate level, from seven countries that there were an appropriate number, and from seven that there were too few. A lack of books, journals, and information technology was reported to be a problem by respondents from four out of 19 countries at undergraduate level, eight out of 20 at postgraduate level, and 10 out of 20 at CPE level. At both undergraduate and postgraduate level, the majority of respondents from central and eastern European countries reported problems with books, journals, and information technology. The results of the survey confirmed many anecdotal impressions and provided an extremely useful background against which to formulate quality guidelines for orthodontic education in Europe.

Dental Equipment↗

Suggested guidelines for the provision and assessment of orthodontic education in Europe. A report from the Professional Development Group of the EURO-QUAL BIOMED II Project.

The suggested guidelines for the provision and assessment of Orthodontic education in Europe, which are introduced, set out, and discussed in this paper, resulted from the work of the Professional Development Group (PDG) of the EURO-QUAL BIOMED II project. They were published in the final report of the project, after comments had been received from a range of national and European bodies and societies, including the British and the European Orthodontic Societies, Royal Colleges, and the General Dental Council.

Curriculum↗

A survey of continuing professional education for orthodontists in 23 European countries.

This paper reports on a survey of the organization, forms and methods of funding continuing professional education (CPE) for those providing orthodontics in 23 European countries in 1997. A postal questionnaire was sent to all members of the EURO-QUAL II BIOMED project, who came from 28 countries, together with an explanatory letter. Answers were validated during a meeting of project participants and by further correspondence, when necessary. Completed questionnaires, which were subsequently validated, were returned by orthodontists from 23 countries and indicated that orthodontic CPE took place in 22 of the 23 countries surveyed. A number of different bodies were reported as organizing orthodontic CPE. This task was most frequently performed by orthodontic societies (in 22 out of 23 countries), but a number of other bodies were also involved. Practical technique courses were reported as taking place in 20 countries. Other frequently occurring forms of orthodontic CPE were lectures (in 18 countries) and study groups (in 15 countries). Orthodontists were reported as financing their CPE in 22 countries; others, who contributed to some or all of the costs, were the Government (in six countries), employers (in four countries), universities (in four countries), and a dental company (in one country). It was concluded that some orthodontic CPE took place in the vast majority of the countries surveyed, and was invariably organized by and paid for, wholly or in part by orthodontists themselves.

Curriculum↗

A survey of the delegation of orthodontic tasks and the training of chairside support staff in 22 European countries.

This paper reports on a survey which was undertaken to investigate the delegation of orthodontic tasks and the training of chairside support staff in Europe. Two questionnaires were posted to all members of the EURO-QUAL BIOMED II project together with an explanatory letter. The first dealt with the delegation of nine clinical tasks during orthodontic treatment. The second with the types of chairside assistant employed in each country and the training that they are given. Completed questionnaires, which were subsequently validated, were returned by orthodontists from 22 countries. They indicated that there was no delegation of clinical tasks in six of the 22 countries and delegation of all nine tasks in five countries. The most commonly delegated tasks were taking radiographs (in 14 of the 22 countries) and taking impressions (in 13 of the 22 countries). The least commonly delegated tasks were cementing bands (in five of the 22 countries) and trying on bands (in six of the 22 countries). Seven of the 22 countries provided chairside assistants with training in some clinical orthodontic tasks. Eighteen of the 22 countries provided general training for chairside assistants and offered a qualification for chairside assistants. Four of these 18 countries reported that they only employed qualified chairside assistants. Of the four countries which reported that they did not provide a qualification for chairside assistants, two indicated that they employed chairside assistants with no formal training and two that they did not employ chairside assistants. It was concluded that there were wide variations within Europe as far as the training and employment of chairside assistants, with or without formal qualifications, and in the delegation of clinical orthodontic tasks to auxiliaries was concerned.

Cementation↗