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Biomedical subjects

R M Watson

Publications and source records attributed to R M Watson.

At least 19 recordsLinked to original sources
PubMed1996

Follow up and maintenance of implant supported prostheses: a comparison of 20 complete mandibular overdentures and 20 complete mandibular fixed cantilever prostheses.

Two independently selected groups of 20 patients who were edentulous in te mandible, were followed up on a regular basis over a 5-year period following restoration with a lower implant stabilised prosthesis and conventional upper denture. Significantly more treatment was required by those who received complete mandibular overdentures than those provided with complete fixed mandibular prostheses. In addition to adjustment for the relief of denture trauma to the mucosa, more mechanical problems arose with overdenture implant prostheses.

Dental Abutments↗
PubMed1996

Transesophageal echocardiography-guided transvenous endomyocardial biopsy used to diagnose primary cardiac angiosarcoma.

Primary cardiac tumors are rare clinical entities with the histologic diagnosis usually made from surgically obtained tissue or at postmortem examination. Transvenous endomyocardial biopsy has been used less frequently, under fluoroscopic or transthoracic echocardiographic guidance. In this case report, we utilized the transesophageal echocardiography to guide the endomyocardial biopsy from a right atrial tumor in a 35-year-old man.

Adult↗
PubMed1996

Effects of inhaled budesonide on allergen-induced airway responses and airway inflammation.

Allergen inhalation by sensitized subjects results in acute bronchoconstriction, which can be followed by a later bronchoconstrictor response, allergen-induced airway hyperresponsiveness, and increases in airway inflammatory cells. Treatment with inhaled glucocorticosteroids attenuates allergen-induced asthmatic airway responses. The purpose of this study was to determine whether a 1-wk pretreatment with inhaled budesonide influences allergen-induced changes in inflammatory cells in blood and induced sputum. Seven subjects with mild atopic asthma were treated in a double-blind, placebo-controlled, randomized, crossover fashion with either inhaled budesonide 400 microg/d, or placebo for 7 d. Allergen challenges were carried out the morning after treatment was discontinued and sputum samples were obtained 7 h after allergen inhalation. Methacholine airway responsiveness was measured, and blood and sputum samples were obtained 24 h post-allergen. Budesonide treatment attenuated the magnitude of both the early and the late asthmatic response, reduced allergen-induced methacholine airway hyperresponsiveness, and attenuated allergen-induced increases in total eosinophils and activated eosinophils. These results suggest that the effects of inhaled glucocorticosteroids on allergen-induced airway responses may be mediated through their inhibition of allergen-induced eosinophil migration and activation.

Administration, Inhalation↗
PubMed1996

Monitoring procedures for the single-tooth implant-stabilized crown with an internally located customized abutment.

Three procedures to ensure the correct location of components in the orifice of a hydroxyapatite-coated implant cylinder are presented. These facilitate recording of an accurate impression and the correct location of a customized abutment supporting a single-tooth crown. A technique is offered for obtaining the reproducible, comparable radiographs necessary for monitoring horizontal bone levels.

Alveolar Bone Loss↗
PubMed1996

The challenge of replacing complete dentures: Part 2.

The purpose of this article is to consider the challenges that arise in replacing complete dentures. The use of conventional techniques incorporating successful features of the existing dentures appropriate to general practice will be discussed and the problems peculiar to the replacement of implant-retained overdentures considered.

Dental Prosthesis, Implant-Supported↗
PubMed1995

Single tooth, implant-stabilized crowns replacing anterior teeth: a clinical comparison of two systems.

Implant-supported single-tooth crowns are suitable alternative restorations to partial dentures and bridges. A number of systems have been developed to create a good aesthetic result without the display of the standard titanium abutment traditionally used in restorations with complete fixed prostheses supported by titanium endosseous implants. This paper reviews two such systems.

Adult↗
PubMed1994

Implant supported fixed distal extension prostheses.

The distal extension fixed implant supported prosthesis is now available as an alternative to a partial denture. However, not all patients will be suitable for such treatment. Limitations imposed on fixture length, the effect of gape upon instrumentation, the size of abutment components and the design of the superstructure are discussed in this article, to assist the general practitioner in case referral.

Contraindications↗
PubMed1994

Neonatal lupus erythematosus. Report of serological and immunogenetic studies in twins discordant for congenital heart block.

Autoantibody, HLA studies and C4 phenotypes were performed on twins discordant for isolated congenital heart block. Serum from the mother and cord blood from the infants revealed Ro(SSA) and La(SSB) antibodies in all three sera. No significant difference in Ro(SSA) antibody titre was noted in the cord blood of either twin when compared with maternal titres, as detected by a sensitive ELISA assay. The infants' mother was HLA-DR3 positive. Both infants had identical HLA and C4 phenotypes. Immunoblot analysis revealed that sera from both mother and infants reacted with the 52-kDa Ro(SSA) macromolecule. Quantitative cord blood IgM levels were not elevated in either twin. This study indicates that placental transfer of anti-Ro(SSA) or anti-La(SSB) alone to the fetus is not sufficient for the expression of congenital complete heart block. We conclude from this experiment of Nature that there must be a second event determining which infant develops complete heart block, but this is unknown at present.

Adult↗
PubMed1994

Effect of inhaled PGE2 on exercise-induced bronchoconstriction in asthmatic subjects.

Previous studies have suggested that the endogenous release of inhibitory prostanoids limits the bronchoconstrictor response to repeated exercise. The aim of our study was to determine whether inhaled prostaglandin (PG)E2 attenuates exercise-induced bronchoconstriction or methacholine airway responsiveness in asthmatic subjects. Eight subjects with mild stable asthma and exercise bronchoconstriction were studied on 4 separate days, 48 h apart. Subjects inhaled PGE2 or placebo in a randomized, crossover, double-blind fashion, 30 min prior to an exercise challenge or a methacholine challenge. PGE2 inhalation significantly attenuated exercise bronchoconstriction. The mean maximal %fall in FEV1 after exercise was 26% (SEM 3.7%) after placebo, and was 9.7% (SEM 2.7%) after PGE2 (p < 0.001). PGE2 also significantly reduced the duration of exercise bronchoconstriction (p = 0.034). However, PGE2 did not significantly attenuate methacholine airway responsiveness. The geometric mean methacholine provocative concentration causing a 20% fall in FEV1 (PC20) was 0.77 (%SEM 1.48) after placebo day, and 1.41 (%SEM 2.20) after PGE2 (p = 0.30). These results demonstrate that inhaled PGE2 markedly attenuates exercise bronchoconstriction in asthmatic subjects and suggest that this effect is not occurring through functional antagonism of airway smooth muscle.

Administration, Inhalation↗
PubMed1994

Effect of magnitude of airway responsiveness and therapy with inhaled corticosteroid on histamine tachyphylaxis in asthma.

Histamine challenge testing is used to measure airway responsiveness in asthma. Histamine tachyphylaxis has been demonstrated after repeated challenges in mild asthmatics not using inhaled corticosteroid. Other studies, using subjects with variable severity of asthma, have not demonstrated histamine tachyphylaxis. Forty patients with stable asthma were studied and stratified according to severity of airway hyperresponsiveness and use of inhaled corticosteroid, to examine the effects of these factors on histamine tachyphylaxis. Airway responsiveness was measured as the histamine provocative concentration causing a 20 percent fall in FEV1 (PC20). Twenty subjects had mildly increased airway hyperresponsiveness (PC20 > 1 mg/ml), of whom 10 were using inhaled corticosteroid. Twenty subjects had moderate to severely increased airway hyperresponsiveness (PC20 < 1 mg/ml), of whom 10 were using inhaled corticosteroid. On each of two study days, 1 week apart, two histamine challenges were performed 1 h apart. Histamine tachyphylaxis was found for the entire group on both study days. The geometric mean PC20 increased from 1.0 mg/ml (percent SEM 1.2) to 1.3 mg/ml (percent SEM 1.2) 1 h later on day 1 (p < 0.0005), and 1.1 mg/ml (percent SEM 1.2) to 1.3 mg/ml (percent SEM 1.2) 1 h later on day 2 p < 0.05). Subgroup analysis demonstrated that tachyphylaxis only occurred consistently in subjects with mildly increased airway hyperresponsiveness not receiving inhaled corticosteroid. In this group, the PC20 increased from 2.2 mg/ml (percent SEM 1.2) to 3.2 mg/ml (percent SEM 1.2) on day 1 (p < 0.001), and from 2.5 mg/ml (percent SEM 1.3) to 3.4 mg/ml (percent SEM 1.2) on day 2 (p < 0.05). This study confirms that histamine tachyphylaxis occurs in asthmatics, but is consistently present only in mild, noncorticosteroid-dependent asthmatics.

Administration, Inhalation↗
PubMed1994

Modern solutions for limited tooth loss in the dental arch.

Replacement of small numbers of teeth in the dental arch has traditionally required the construction of a conventional bridge or a removable partial denture where sound reasons exist to favour restoration. Two alternative treatments now increase the choice; resin-bonded bridgework and implant-supported prostheses. A discussion of their indications and the principles of their use are given.

Alveolar Process↗
PubMed1993

The teaching of osseointegrated implant dentistry in the schools of the UK and Eire.

Implant dentistry is now a well recognised treatment modality. This paper examines the extent to which it is taught by dental schools in the United Kingdom and Eire to undergraduate and postgraduate students, hospital staff and general practitioners. The details of this teaching have been supplied by Heads of Departments of Prosthetic Dentistry.

Dental Implantation, Endosseous↗
PubMed1993

A retrospective study comparing duplication and conventionally made complete dentures for a group of elderly people.

The duplication technique is a well recognised method of replacing complete dentures. Advantages claimed for this technique are that patients adapt more easily to their new complete dentures and the numbers of treatment visits are reduced. The case notes of 100 patients were examined retrospectively, 50 of whom had had dentures constructed by undergraduates using a duplication technique and 50 with a conventional technique. In addition, a questionnaire was sent to the patients to obtain their views on the replacement dentures. The 'duplication group' required fewer visits for the delivery of the dentures, but there was no statistical difference between the numbers of post-insertion visits, for the two groups, needed to make the dentures comfortable. The only identifiable reason for selecting a duplication technique was the failure of construction of new dentures by a conventional method in 15 patients. Apart from this the two groups appeared remarkably similar when comparing age of dentures being replaced, period of edentulousness, number of previous complete dentures and medical histories. As judged by the questionnaire more patients in the duplication group continued to wear their new dentures compared to the conventional group.

Aged↗
PubMed1993

Criterion based audit in prosthetic dentistry.

A criterion based retrospective audit into the provision of complete dentures in an undergraduate teaching programme has been produced. This consisted of a series of questions related to the treatment of the patient and the satisfaction or otherwise expressed about the treatment. The audit revealed where treatment had been successful according to the established criteria. It has been found that an audit of this nature is demanding of clinicians' time but does show where improvements can be made in patient management which will result in better health care. Clinical audit is now recognized as forming an important part of health care. It is applicable to all areas of dentistry, ie general dental practice, the community dental services and the hospital services, and to all specialities eg prosthetics, orthodontics etc. An audit programme needs careful planning and a pilot study is worthwhile to indicate areas of difficulty. This audit has been used in an undergraduate training programme, however, the process by which the audit has been assembled is an example of how an audit could be established in any area of dentistry, provided that the criteria are modified to make them relevant to the clinical speciality.

Aged↗
PubMed1993

Effect of a platelet activating factor antagonist, WEB 2086, on allergen induced asthmatic responses.

BACKGROUND: Platelet activating factor (PAF) has been implicated in the pathogenesis of airway hyperresponsiveness in asthma. The purpose of this study was to evaluate the effects of a selective PAF antagonist (WEB 2086), given in doses known to antagonise the effects of inhaled PAF in human subjects, on allergen induced early and late asthmatic responses and on airway hyperresponsiveness. METHODS: Eight atopic, mildly asthmatic subjects were studied during a screening period and two treatment periods. During the screening period subjects inhaled an allergen to which they were known to be sensitised and the response was measured as the fall in the forced expired volume in one second (FEV1) to show the presence of early (0-1 h) and late (3-7 h) asthmatic responses. On another day the subjects inhaled allergen diluent. During the treatment periods subjects inhaled allergen after one week's pretreatment with WEB 2086 (100 mg three times a day) or placebo administered in a randomised, double blind, crossover fashion. Histamine airway responsiveness was measured 24 hours before and 24 hours after allergen and the results were expressed as the provocative concentration causing a 20% fall in FEV1 (PC20). RESULTS: The maximal early asthmatic response after allergen with placebo treatment was 18.4% (SE 4.4%) and with WEB 2086 18.9% (4.4%). The maximal late response with placebo treatment was 21.7% (5.3%) and with WEB 2086 21.2% (3.0%). The log difference (before and after allergen) in histamine PC20 was 0.35 (0.06) after placebo treatment and 0.30 (0.1) after WEB 2086. CONCLUSIONS: These results indicate that one week of treatment with an orally administered PAF antagonist (WEB 2086) does not attenuate allergen induced early or late responses or airway hyperresponsiveness.

Administration, Oral↗
PubMed1993

Exercise-induced refractoriness in asthmatic subjects involves leukotriene and prostaglandin interdependent mechanisms.

Exercise-induced bronchoconstriction is caused, in part, by leukotriene (LT)D4 release in asthmatic airways. Asthmatics become refractory to exercise bronchoconstriction with repeated challenges, due to inhibitory prostaglandin release. The purpose of this study was to test the hypothesis that exercise refractoriness is caused by LTD4-induced inhibitory prostaglandin release. Fourteen stable asthmatic subjects with exercise-induced bronchoconstriction were studied. On the first 2 days, subjects underwent two challenges, 1 h apart, with either exercise or inhaled LTD4. Eight subjects then took part in three double-blind, randomized, placebo-controlled, crossover studies with flurbiprofen, a prostaglandin synthetase inhibitor, to determine whether cross refractoriness occurs between exercise and LTD4, whether flurbiprofen attenuates this effect, and whether flurbiprofen attenuates LTD4 tachyphylaxis. There was a reduction in the intensity of bronchoconstriction to the second challenge both with exercise (refractoriness) and with LTD4 (tachyphylaxis). The degrees of refractoriness and tachyphylaxis were correlated (r = 0.72, p = 0.005). Flurbiprofen attenuated LTD4 tachyphylaxis. Cross refractoriness occurred between exercise and LTD4, and flurbiprofen treatment also attenuated this effect. One hour after LTD4 challenge, the mean fall in FEV1 after exercise was 12.3% (%SEM 2.3) on placebo and 17.1% (%SEM 3.8) on flurbiprofen (p = 0.027). Similarly, 1 h after exercise, the LTD4 PC20 increased to 0.73 (%SEM 1.4) microgram/ml on placebo and 0.30 (%SEM 1.8) microgram/ml on flurbiprofen (p = 0.026). These results suggest that LTD4 released in asthmatic airways as a result of exercise stimulates inhibitory prostaglandin release, resulting in exercise refractoriness.

Adult↗
PubMed1993

The use of two implant systems for providing implant supported overdentures in the mandible--a clinical appraisal.

The objective of this paper is to compare the Nobelpharma implant system with that designed by Astra-Tech. The main difference between the two is in the design of the fixture-abutment linkage. With the Astra system, the abutment and screw form one unit, whilst with the Nobelpharma system there is a separate abutment screw. Both systems have been used to support overdentures. Linked bar retention between two implants has been used with the Nobelpharma implants, and individual magnetic or stud retention has been used with the Astra system. Each attachment mechanism has produced patient satisfaction.

Dental Abutments↗