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Biomedical subjects

D A Miles

Publications and source records attributed to D A Miles.

At least 19 recordsLinked to original sources

Cloning, expression and purification of full length Rep78 of adeno-associated virus as a fusion protein with maltose binding protein in Escherichia coli.

The adeno-associated virus (AAV) Rep78 protein is required for many aspects of AAV's life cycle including its DNA replication and the regulation of its gene expression. Because of increasing utilization of AAV as a gene therapy vector and its possible use as an anti-cancer/anti-viral agent, the complete characterization of its Rep78 regulatory protein is important. In order to study various functional aspects of Rep78, we have cloned and expressed the Rep78 gene in Escherichia coli using an inducible expression plasmid. The entire Rep78 open reading frame (nt 321 to 2185) was cloned into the LacZ inducible expression vector pMALc2. Upon induction of the Ptac promoter with isopropyl thio-beta-D-galactopyranoside (IPTG), Rep78 is produced as a fusion protein with maltose binding protein (MBP). This recombinant MBP-Rep78 protein displayed all the biochemical activities which are described for the wild type protein including binding to the AAV terminal repeats (TR), endonuclease activity, and helicase activity. Furthermore, for the first time, ATP binding by Rep78 is demonstrated.

ATP-Binding Cassette Transporters

Development of sample size models for national general practice surveys.

The most cost-effective method to measure the morbidity managed and treatments provided in general practice is from records of a cluster of consultations (encounters) from each general practitioner (GP) in a random sample. A cluster sampling method is proposed for future surveys for analysis of encounter-based general practice data. The sample sizes needed to measure the most common problems managed and drugs prescribed were estimated using ratio-estimator models for cluster sample surveys. Morbidity and treatment rates were estimated from the Australian Morbidity and Treatment Survey in General Practice 1990-1991 (AMTS). The 20 most common problems in the AMTS were managed at estimated rates of 1.5 to 9.5 per 100 encounters. The 20 most common drugs were prescribed at estimated rates of 0.7 to 3.6 per 100 problems. These rates were used to determine precision as a percentage of each true value for future surveys, that is, as relative precision. If we want to be 95 per cent confident that these rates will be within 5 per cent of each true rate, sample sizes of 552 to 5675 GPs are needed. If we fix the sample size at 1000 GPs, relative precision lies within 12 per cent of these rates. If the sample size is increased to 1500 GPs, relative precision improves only marginally. The differences in sample size for each of the most frequent morbidity and treatment data are largely due to their variable distributions and relatively infrequent occurrence in general practice. A sample size of 1000 GPs will enable measurement of the most common morbidity and treatments at 95 per cent confidence.

Australia

Effects of filtration, collimation, and target-receptor distance on artificial approximal enamel lesion detection with the use of RadioVisioGraphy.

RadioVisioGraphy is an imaging modality that uses a charge-coupled device electronic sensor. Dental charge-coupled device imaging can be used to detect dental caries; however, it was not known what effect beam collimation, added filtration, or variable target-receptor distance has on this task. The purpose of this investigation was to study these effects were imaged by conventional radiography and RadioVisioGraphy varying exposure time, target-receptor distance, collimation, and filtration. Printed RadioVisioGraphy images without enhancement and E-speed radiographs were evaluated by five viewers. The number of true-positives and false-positives were compared as were sensitivity, specificity, positive and negative predictive values, accuracy, and entrance level radiation exposure. Added filtration reduced the false-positives regardless of collimation or target-receptor distance. True-positives and false-positives were greater at a target-receptor distance of 8 inch at exposures < 0.10 seconds (F < 0.0151). E-speed radiographs had a greater specificity and positive predictive value than RadioVisioGraphy images without image enhancement; however, no significant differences were found between RadioVisioGraphy images and E-speed radiographs in true-positive or false-positive identifications without image enhancement.

Analysis of Variance

Interpretation of periapical lesions using RadioVisioGraphy.

Density and gray-scale changes in radiographs are important visual features the clinician uses to evaluate changes in bone pattern. With the advent of a new direct digital radiology system, RadioVisioGraphy (RVG), the controlled adjustment of contrast is now possible. The purpose of this study was to compare RVG's diagnostic potential for detecting periapical lesions with that of conventional radiography. Lesions were created in human cadaver specimens and radiographed conventionally and with RVG. Images were evaluated by three endodontists. Results were: (a) when no lesion existed, conventional radiographs were more diagnostic than RVG at a significance level at p < or = 0.05; (b) when lesions were enlarged to involve lamina dura and medullary bone, RVG was superior at p < or = 0.05; and (c) no difference was found between conventional radiography and RVG when the lesion involved cortical bone.

Alveolar Bone Loss

Evaluation of the bond strength of dentin bonding agents used to seal resected root apices.

A number of improved dentin bonding agents have recently become available, but have not been evaluated on apical radicular dentin. The purpose of this study was to compare the tensile bond strengths of four adhesive resins on resected root ends before and after blood contamination. Forty single-rooted human incisors were cleaned and shaped and obturated. The apical 3 mm was then resected at a 45-degree angle, bonded, and tested for tensile bond strengths using an Instron machine. The bonding systems evaluated included Prisma Universal Bond 3, Scotchbond MultiPurpose Dental Adhesive, Amalgambond, and All Bond 2. All bonding systems were then covered with Prisma APH light-cure composite resin. Results indicated that the bond strengths of the blood contaminated groups were significantly less than those of the control groups, except in the case of Amalgambond where no significant difference was noted. When the surface was contaminated with blood, Prisma Universal Bond 3 had significantly lower bond strengths, whereas Amalgambond had significantly higher bond strengths than the other subgroups.

Analysis of Variance

Interpretation of endodontic file lengths using RadioVisiography.

The purpose of this investigation was to compare RadioVisioGraphy (RVG) imaging with conventional radiography in determining endodontic file length adjustment. Human cadaver sections with first or second molars were used. Files were inserted into canals at randomly selected lengths, from 4 mm short of the radiographic apex to 3 mm beyond. Radiographs and RVG images were evaluated to determine the adjustment needed to place the file 0.5 mm from the radiographic apex. Results showed no significant difference in the ability of endodontists to make accurate file length adjustments using conventional radiography versus RVG. In this study, it was found that: (a) accurate file length adjustments can be made from an image two times larger than the actual tooth; (b) RVG is not significantly better than conventional radiography; and (c) if both methods are available, RVG is preferred because of the significant reduction in radiation dose.

Analysis of Variance

A comparison of country and metropolitan general practice.

This paper is a summary of a report of a comparison of country and metropolitan general practice undertaken by the Family Medicine Research Unit, University of Sydney, and published as a supplement to the Medical Journal of Australia. The identified differences were not consistent across small medium and large country towns. The morbidity patterns were similar between all areas, but country GPs were generally busier and undertook more hospital and procedural work.

Adult

Disorders of the maxillary sinus.

The maxillary sinuses often are visualized on oral and maxillofacial radiographs, and the dentist should be able to interpret any signs of disease in the area. In addition, disorders of the sinuses may result in symptoms that the patient interprets to be of dental origin. Conversely, dental diseases may influence the radiographic appearance of the sinuses. This article reviews the radiographic signs of common sinus disorders to help the clinician accurately assess the patient.

Cysts

A comparison of country and metropolitan general practice.

OBJECTIVE: To provide a description of country general practice in Australia, and to determine the extent to which country and metropolitan general practice differ in terms of the characteristics of the practitioners, the morbidity managed, treatments provided and the availability of support services. METHOD: A survey requiring the recording of details of all direct and indirect patient encounters on encounter forms by a sample of general practitioners (GPs). Each GP recorded for two one-week periods separated by an interval of six months, between October 1990 and October 1991. The recording weeks were spread as evenly as possible throughout the year. SAMPLE: Participants were drawn from a list of medical practitioners in Queensland, NSW and Victoria who provided more than 1500 general practice Medicare items of service during the previous year. The sample was stratified within States by population of postcode, into metropolitan areas and three country strata: "small country towns" (population less than 5000); "medium country towns" (5000-15,000); and "large country towns" (more than 15,000). The total country sample is referred to as "country areas". Planned sample size was 180 country GPs (20 in each stratum in each State) and 60 metropolitan GPs (20 in each of the three State capital cities). The final data set was weighted to be representative of the distribution of the source population. DATA COLLECTION: The variables studied included: GP characteristics; practice isolation factors; patient age, sex and status to the practice; patient reasons for encounter (up to three per encounter); problems managed (up to four); drugs prescribed and other treatments provided (up to four per problem); tests and investigations ordered and referrals made at these encounters; and planned follow-up. Data were centrally coded. Participation rate: The final sample of 231 GPs (177 country and 54 metropolitan) recorded information during 435 recording weeks (336 country and 99 metropolitan). These practitioners represented 50.7% of those contacted and available, the response rate being better in country (57.5%) than in metropolitan (36.5%) areas. A practice profile questionnaire which included questions regarding the doctor and the practice was completed by 97.4% of participants, while a questionnaire on distance from support services was completed by 93.8% of country participants. The final weighted data set included 51,741 encounters with country GPs and 11,351 with metropolitan GPs. RESULTS: The general practitioners: Country GPs were less likely to be female or to conduct consultations in a language other than English, and were more likely to do some work on a salaried or sessional basis. GPs from small country towns were older, more likely to be in solo practice, and more likely to belong to a professional organisation. "Remoteness" of towns: Nearly all towns were within 25 km of a hospital, but far fewer small and medium country towns were within 50 km of a base hospital than large country towns. X-ray services were almost universally available within 50 km, and with the exception of small country towns so were pathology services. Access to medical specialists and to a lesser degree other health professionals decreased with population size--patients in 30% of small towns had to travel over 100 km to see many specialists and some health professionals. Self-reported procedural work: GPs in small and medium country towns were more likely than those in large towns to report performing procedural work, the largest difference being in the area of em

Adolescent

Triamcinolone acetonide versus chlorhexidine for treatment of recurrent stomatitis.

This study compared the efficacy of pain control of two medications, used to treat recurrent aphthous stomatitis, placed under a physical barrier of cyanoacrylate. Thirty patients with recurrent aphthous stomatitis were selected from the records of the Diagnostic Referral Clinic at Indiana University School of Dentistry and randomly divided into three groups; one group was a control. Experimental groups received a topical application of either triamcinolone acetonide (0.025%) or chlorhexidine digluconate (0.12%). Medications were covered by isobutyl cyanoacrylate (Iso-Dent). Controls received the Iso-Dent only. Patients kept a diary to record their pain level on a 10 cm visual analog scale until the lesion healed. Ulcer episodes were treated for 12 weeks. Because some patients had multiple episodes, a total of 35 ulcer episodes were available for analysis. The mean number of ulcer days for each group was not significantly different. ANOVA with repeated measures for 10 days on each patient was first performed. A highly significant difference in pain intensity and perception was found at different days (p < 0.0001). No significant difference was found between the triamcinolone acetonide and chlorhexidine gluconate (p < 0.49).

Adolescent

Hypodontia and nail dysplasia syndrome. Report of a case.

The ectodermal dysplasias are a clinically and genetically heterogeneous group of more than 120 syndromes involving ectodermally derived structures. The syndrome that is autosomal dominantly inherited and characterized by hypodontia, dysplastic nails, and normal hair is known as hypodontia-nail dysplasia syndrome, or tooth-and-nail syndrome. Because of the minimal manifestations, this syndrome may be difficult to diagnose. Patients with hypodontia should be examined for dysplastic nails of the hands and feet and referred to medical and dental genetic specialists for verification of the diagnosis and counseling. We report a case of tooth-and-nail syndrome in a young woman.

Adult