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Biomedical subjects

R F Wilson

Publications and source records attributed to R F Wilson.

At least 73 records · Page 4Linked to original sources
PubMed1998

Respiratory sinus dysrhythmia persists in transplanted human hearts following autonomic blockade.

1. The present study was performed to test whether beat-to-beat cardiovascular control in cardiac allograft recipients resides in cholinergic and/or adrenergic nerves that are intrinsic to the heart. 2. Heart rate (HR) fluctuations synchronous with respiration during spontaneous, double tidal volume and metronome-synchronized breathing were quantified in 13 human heart transplant recipients. We also examined the effects of sequential cholinergic and beta-adrenoceptor (combined) autonomic blockade on respiratory sinus arrhythmia (RSA). We computed RSA amplitude and the correlation between respiration and changes in HR (cardiopulmonary synchronization; CPS). Group means were compared using repeated-measures analysis of variance. Transplant recipients served as their own controls. 3. In the basal state, moderate RSA amplitude and CPS were observed. During cholinergic and combined blockade, we observed no significant change in RSA amplitude, whereas CPS increased significantly during combined blockade (P < 0.05). The amplitude of RSA increased during respiration at double baseline tidal volume, but not at any of the other breathing manoeuvres (P < 0.01). In contrast, CPS increased significantly during both patterned breathing manoeuvres. No significant correlation was seen between mean right atrial pressure and RSA amplitude. In 23% of subjects with low CPS, HR oscillated with arterial pressure. These oscillations were independent of respiration. During all three patterns of respiration, a significant inverse correlation was observed between CPS and pulse pressure (r = -0.53 to -0.73). Thus, as the amplitude of pulse pressure increased, respiration accounted for a smaller percentage of HR variation. 4. In conclusion, RSA persists and the magnitude of CPS increases following combined autonomic blockade. These studies suggest that while RSA after cardiac transplantation is not cholinergically or adrenergically mediated, it may be related to mechanical stretch of the sinus node caused by changes in intrathoracic pressure and perfusion pressure.

Adrenergic beta-Antagonists↗
PubMed1998

The rôle of a dentine-bonding agent in reducing cervical dentine sensitivity.

This double-blind split-mouth trial with 16 adult patients investigated the ability of a dentine bonding agent (DBA) to reduce cervical dentine sensitivity. Following stimulation of pairs of teeth by conventional tactile and air blast stimuli, together with controlled evaporative and cold fluid stimuli, sensitivity was recorded using tactile threshold, visual-analogue scale (VAS) and short-form McGill pain questionnaire (SFMPQ), prior to and 1 week following treatment with DBA. Prior to assessment, subjects recorded their perceived overall sensitivity using VAS and SFMPQ. Application of each stimulus was separated by 10 min. Sensitivity was recorded by a clinician blinded to the treatment status of each tooth. The control tooth was treated by applying DBA to coronal enamel. Dietary information was collected after the post-treatment assessment. There was a significant (p<0.05) improvement in tactile threshold and air flow and air blast VAS scores, together with reductions in sensitivity to evaporative stimuli when assessed by SFMPQ. Treatment response was not influenced by the subjects' age, gender, diet, use of fluoride-containing or silica-based toothpastes or fluoride mouthwashes, or a history of previous sensitivity treatment. It is concluded that topical application of DBA is an effective way to reduce cervical dentine sensitivity.

Adult↗
PubMed1998

Contribution of individual drugs to gingival overgrowth in adult and juvenile renal transplant patients treated with multiple therapy.

Drug regimens for transplantation often consist of multiple therapeutic agents and may result in drug-induced gingival overgrowth (DIGO). The aim of this study was to investigate the contribution of individual drugs in renal transplant patients. 147 adults (19-84 years) and 60 juveniles (3-18 years) were scored for DIGO and other clinical variables. Duration of treatment, dosage of drugs per kg body weight and serum cyclosporin levels were recorded. 44% of adults and 27% of children had DIGO. All patients were receiving prednisolone. More adults than children were administered cyclosporin, the reverse was true of azathioprine (p<0.01). Explanatory models were evaluated by stepwise ordinal polynomial logistic regression. Statistically significant explanation (p<0.05) of DIGO was afforded by prednisolone, nifedipine and azathioprine concentrations in adults and by cyclosporin, nifedipine and azathioprine concentrations in juveniles. Prednisolone and azathioprine were inversely related to the degree of DIGO. Plaque and irregularity scores, lip coverage and mouthbreathing status showed significant additional explanation in adults, replacing nifedipine and azathioprine in the final model. Irregularity was additionally explanatory in children, but no other clinical variables. A larger proportion of the variance of DIGO was explained by the available variables in children than in adults (pseudo r2=0.50 versus 0.25). The degree of DIGO in renal transplant patients is influenced by the dosage of a number of individual components of multiple drug therapy independently of the presence of local clinical factors.

Adolescent↗
PubMed1997

An evaluation of the diagnostic yield from bitewing radiographs of small approximal and occlusal carious lesions in a low prevalence sample in vitro using different film types and speeds.

AIM: To compare diagnostic yield in caries diagnosis from D- and E-speed films. DESIGN: A laboratory study. SETTING: A UK dental school between 1992 and 1994. MATERIALS AND METHODS: 96 extracted teeth containing approximal and occlusal lesions, but representing a low caries prevalence sample, were set in occluding dental arches. Bitewing radiographs were taken and interpreted by 5 examiners for the presence or absence of caries. Each examiner was also asked which film image he or she subjectively liked best. MAIN OUTCOME MEASURES: The teeth were subsequently sectioned and histologically examined to validate diagnostic decisions. RESULTS: For all film types the percentage of lesions with caries histologically in dentine correctly identified radiologically (sensitivity) was low (approximal caries 8-22%; occlusal caries 0-30%). The number of sound dentine sites correctly identified (specificity) was high (approximal caries 98-100%; occlusal caries 79-100%). There were no significant differences between D- and E-speed films. Sensitivity was unaffected by each examiner's subjective preference for a particular film. The variation in sensitivity of diagnosis was due to differences between examiners. CONCLUSIONS: The reluctance of many GDPs to use E-speed film because they 'do not like the image' cannot be endorsed or supported. Both E-speed film types examined can be recommended for use in general practice.

Analysis of Variance↗
PubMed1997

A prospective, randomized study of open vs laparoscopic inguinal hernia repair. An assessment of postoperative pain.

OBJECTIVE: To compare postoperative pain after laparoscopic hernia repair and conventional open hernia repair. DESIGN: Prospective, randomized study. SETTING: Veterans Affairs Medical Center. PATIENTS: Sixty-two patients scheduled for elective inguinal hernia repair. INTERVENTIONS: Patients were randomized in the operating room to have a laparoscopic hernia repair (30 patients) or a conventional open hernia repair (32 patients). All operations were performed while the patient was under general anesthesia to avoid anesthesia as a confounding variable. MEASURES: Postoperative pain following laparoscopic hernia repair and open hernia repair were compared using the McGill Pain Score, the McGill Visual Analogue Pain Scale score, and the number of acetaminophen with 30-mg codeine sulfate (Tylenol 3) tablets needed for pain during the first and second 24-hour periods postoperatively. All of the patients were interviewed and the postoperative pain was evaluated by a special study nurse (P.M.L.) who was blinded to the repair technique. RESULTS: At 24 hours, the patients with laparoscopic hernia repair had 26% less pain by the McGill Pain Score (P = .02) and 31% less pain by the McGill Visual Analogue Scale (P = .006) than those who underwent an open hernia repair. At 48 hours the patients who underwent laparoscopic hernia repair had 28% less pain by the McGill Pain Score (P = .03), 42% less pain by the McGill Visual Analogue Scale (P = .002), and used 42% fewer analgesic tablets (P = .004). CONCLUSION: Patients with a laparoscopic hernia repair had significantly less pain postoperatively than those with standard open hernia repairs.

Aged↗
PubMed1997

Prognostic factors with the use of the transjugular intrahepatic portosystemic shunt for bleeding varices.

OBJECTIVES: To evaluate the outcome of patients undergoing the transjugular intrahepatic portosystemic shunt (TIPS) procedure for bleeding esophageal varices and to outline the factors affecting outcome. DESIGN: Uncontrolled, nonrandomized, retrospective study. SETTING: A 320-bed university-associated urban emergency adult hospital. PATIENTS: Thirty-three patients undergoing TIPS procedures for bleeding esophageal varices with at least 18 months of follow-up. Five patients (15%) had Child class B disease and 28 (85%) had Child class C disease. The mean transfusion requirements were 12.6 U of red blood cells, 18 U of fresh-frozen plasma, and 7 U of platelets. The mean portosystemic gradients before and after the initial TIPS procedure were 18 and 7 mm Hg, respectively. OUTCOME MEASURES: The incidence, time and causes of death, and recurrent variceal hemorrhage were correlated with various clinical and laboratory factors. RESULTS: By 18 months after the TIPS procedure, 16 patients (48%) died of rebleeding or hepatic failure. Subsequent upper gastrointestinal tract bleeding occurred in 14 patients (42%). Of 8 in whom occlusion or stenosis of the TIPS was promptly corrected, all 8 survived. Of 6 in whom occlusion or stenosis of the TIPS was not corrected, 5 (83%) died. Laboratory values (mean +/- SD) predictive of death before 18 months (compared with those of patients alive at 18 months) included a low initial serum albumin level (22 +/- 4 vs 29 +/- 5 g/L; P < .001); an increased initial total bilirubin level (68 +/- 75 vs 34 +/- 20 mumol/L [4.0 +/- 4.4 vs 2.0 +/- 1.2 mg/dL]; P = .001), and an elevated prothrombin time after attempts at correction (18.0 +/- 3.4 vs 14.6 +/- 1.2 seconds; P < .001). CONCLUSIONS: The TIPS procedure in patients with Child class C alcoholic cirrhosis was associated with a high incidence of death or rebleeding within 18 months. Prompt correction of TIPS abnormalities in patients with rebleeding increased survival. The albumin, bilirubin, and prothrombin time values obtained before performance of the TIPS procedure were predictive of outcome.

Adult↗
PubMed1997

Atherosclerotic vascular complications in diabetic transplant candidates.

Serious vascular complications limit the success of renal transplantation in diabetic patients. Nearly half of diabetic transplant recipients die within 3 years after transplantation from a vascular complication. However, it has been difficult to determine before transplantation which patients are likely to do poorly. Because atherosclerosis is a systemic disease, we hypothesized that diabetic transplant candidates with pretransplant coronary artery disease would be at high risk for vascular complications even if asymptomatic at the time of pretransplant evaluation. Our hypothesis was that insulin-dependent (IDDM) transplant candidates with coronary artery disease identified with pretransplant coronary angiography would have an increased number of vascular events (amputation, cerebral vascular accident [CVA], or myocardial infarction [MI]) within 3 years of follow-up. We prospectively studied 198 consecutive diabetic transplant candidates grouped on the basis of coronary artery disease. Group 1 patients had no stenosis that was 50% or greater, group 2 patients had one or more stenoses between 50% and 74%, and group 3 patients had one or more stenoses of 75% or greater. During median follow-up of 41 months, 64 patients experienced 98 amputations, 28 MIs, and seven CVAs. At 36 months of follow-up, 55% of group 3 patients, 30% of group 2 patients, and 11% of group 1 patients had experienced a vascular event (P < 0.001). Cox regression confirmed the association of coronary artery disease with subsequent vascular events. Patients with coronary artery disease had a sevenfold increased risk of amputation and a fourfold increased risk of myocardial infarction. Six of seven CVAs occurred in patients with coronary artery disease. We conclude that coronary artery disease identified at pretransplant evaluation is associated with an increased risk of noncoronary vascular complications within 3 years after evaluation.

Adult↗
PubMed1997

A randomized controlled trial of a 2% minocycline gel as an adjunct to non-surgical periodontal treatment, using a design with multiple matching criteria.

Topical locally delivered minocycline is an adjunctive to non-surgical periodontal treatment, but there are few reported trials. Previous trials have reported differences between changes in probing depth in treatment and control groups, but no differences in probing attachment level. In the present study, 30 subjects were paired according to gender, age, ethnic group, smoking habits, and probing depths. Both groups received intensive oral hygiene education and root planing with local anaesthesia. Active or placebo gel was placed subgingivally at planed sites in each subject according to a double-blind protocol, immediately after instrumentation, and 2 and 4 weeks later. A periodontal examination was made with a constant force probe before instrumentation, and 6 and 12 weeks later, 2 subjects failed to complete the study, and their pairs were therefore not included in the analysis. Results were tested with analysis of covariance. Differences between groups in mean probing depth did not reach statistical significance at any visit (baseline: test (T) = 5.93 mm, control (C) = 5.74 mm; 6 weeks: T = 3.53 mm, C = 3.63 mm; 12 weeks: T = 3.29 mm, C = 3.44 mm), but mean probing attachment levels were different (p < 0.05) at both reassessments (baseline: T = 6.86 mm, C = 6.83 mm; 6 weeks: T = 4.93 mm, C = 5.30 mm; 12 weeks T = 4.91 mm, C = 5.27 mm). There was also a difference in the number of sites with bleeding on deep probing at 12 weeks (p < 0.05). This trial showed that adjunctive minocycline gel provided a more advantageous outcome for nonsurgical periodontal treatment in terms of probing attachment level and bleeding on deep probing. This trial was a good example of experimental, as opposed to community, design, and used limited resources to show a clear result.

Administration, Topical↗
PubMed1997

Electronic diagnosis of occlusal caries in vitro: adaptation of the technique for epidemiological purposes.

Most studies on electronic diagnosis of occlusal caries have involved taking site-specific conductance measurements. Airflow around the electronic caries monitor probe removes superficial moisture and the conductance measurement reflects the caries status of that part of the fissure beneath the probe tip. This is an appropriate technique for a clinician to use to monitor caries status, and it could be adapted for use in epidemiological studies and clinical trials. The present work investigated an alternative technique using a jelly as a contact medium over the entire fissure system so that the probe might record the overall caries status of the tooth reflecting the worst affected site. Readings were taken on 96 extracted teeth with dye-coloured jelly acting as a contact medium. Readings were repeated on 32 teeth. Histological validation of caries status was carried out by visual examination of serial sections through each tooth to note the deepest lesion. The sensitivity and specificity of the overall electronic caries monitor readings were calculated for all lesions and dentine lesions only using selected resistance cut-off points and presented as a series of Receiver Operating Characteristic (ROC) curves. The optimum sensitivity and specificity values were, for all lesions: 61% and 86%, and for dentine lesions: 76% and 76% respectively. The reproducibility of the readings was acceptable (Kappa values for all lesions = 0.76, for dentine lesions = 0.55). The technique warrants further study as an overall reading may be more appropriate for epidemiological and clinical trial use.

Bicuspid↗
PubMed1997

Radiological assessment of the effects of potential root-end filling materials on healing after endodontic surgery.

The effects of three root-end filling materials on healing following endodontic surgery were assessed radiologically and correlated with histological findings reported elsewhere. The materials compared were a light-cured glass ionomer cement (Vitrebond), a reinforced zinc oxide-eugenol cement (Kalzinol) and amalgam. The root canals of 27 two-rooted mandibular premolar teeth of six beagle dogs were inoculated with endodontic pathogenic bacteria to induce periradicular lesions. The roots were apicected and root-end cavities filled with the tested filling materials. The teeth and surrounding jaw were removed after 4 weeks (30 roots) or 8 weeks (24 roots). Radiographs were taken of each jaw section and subjected to image analysis. Healing was evaluated based on measurements of the size of the periradicular radiolucent areas. ANOVA disclosed no statistically significant differences in the size of the periradicular areas either between time periods or between materials. These results did not correlate with the tissue responses in the same material as assessed histologically and previously reported. The use of radiographs alone to assess healing after endodontic surgery in the dog mandible is unsatisfactory, and should not be regarded as a substitute for histological examination for the determination of healing.

Analysis of Variance↗
PubMed1997

Myocardial perfusion reserve: assessment with multisection, quantitative, first-pass MR imaging.

PURPOSE: To demonstrate the feasibility of determining myocardial blood flow changes and the myocardial perfusion reserve with magnetic resonance (MR) first-pass imaging, to validate the MR results by means of comparison with radiolabeled microsphere flow measurements in an animal model, and to compare the coronary flow reserve with the perfusion reserve at MR imaging in patients with hemodynamically nonsignificant coronary lesions and angina. MATERIALS AND METHODS: Arrhythmia-insensitive, first-pass, multisection, T1-weighted MR imaging with contrast agent enhancement was performed in eight pigs with acute ischemia and in eight adult patients (six women, two men). In the pigs, microsphere flow measurements were obtained in parallel with the MR measurements. In the patients, the coronary flow reserve was measured with an intracoronary Doppler flow ultrasound probe for comparison with the MR perfusion reserve. RESULTS: In the animal studies, there was linear correlation between MR perfusion indexes and the microsphere flow measurements (r = .88, P < .01). In the patients, the regional perfusion reserve matched the coronary flow reserve (linear regression with a slope of 1.02 +/- 0.09, r = .80). CONCLUSION: The myocardial perfusion reserve can be quantified with first-pass MR imaging. In patients with microvascular dysfunction, the myocardial perfusion reserve matches the reduced coronary flow reserve.

Animals↗
PubMed1997

The effect of airflow on site-specific electrical conductance measurements used in the diagnosis of pit and fissure caries in vitro.

There has been renewed interest in the electronic diagnosis of occlusal caries using measurement of conductance or impedance. One of two previously manufactured electronic caries detectors (the Vanguard electronic caries detector, Massachusetts Manufacturing Corporation, Cambridge, Mass., USA) had a probe tip with an integral air supply. Airflow is essential for removing superficial moisture and preventing surface conduction to the gingival margin. The aim of this study was to determine the effect of airflow on electronic diagnosis of occlusal caries using a prototype electronic caries meter (ECM II. LODE, Groningen, The Netherlands) fitted with a flow meter. Stable conductance readings were taken at 76 discrete sites on 32 extracted teeth with no visible signs of cavitation, at 3 airflows: 5, 7.5 and 10 litres/min. The stable conductance scale was a continuous scale from -0.45 to 13.25 and set by the manufacturer. Histological validation was carried out on macroradiographs of sections cut to include each sample site. The histological picture was compared with the stable conductance readings taken at various airflows. Sensitivity and specificity were calculated using different conductance readings to differentiate sound and carious sites, and receiver operating characteristic (ROC) curves constructed. Of the sites, 32% had enamel and dentine caries and 33% had enamel caries. The ROC curves showed airflow to be highly relevant. An airflow of 5 litres/min was shown to be inadequate and led to large numbers of false-positive diagnoses. A minimum airflow of 7.5 litres/min was required to achieve optimum sensitivity (92%) and specificity (87%) for dentine caries diagnosis.

Air Movements↗
PubMed1997

The electronic diagnosis of caries in pits and fissures: site-specific stable conductance readings or cumulative resistance readings?

A prototype electronic caries meter (ECM II; LODE, Groningen. The Netherlands) was designed to deliver a conductance reading when the reading had remained stable for 3 consecutive seconds. The aim of this study was to determine whether this type of stable conductance reading was optimal for caries diagnosis. The ECM II was connected to a graphic recorder which enabled the continuous resistance to be recorded. The graphic recording was calibrated using a standard, variable resistance box. Stable conductance readings were taken for 76 sites on 32 extracted teeth with no visible sign of cavitation at an airflow of 7.5 l/min. Simultaneous graphic recording of resistance was continued for 10 s and cumulative resistance measurements were calculated by adding the resistance values at 1-second intervals. Histological validation of caries status was carried out on macroradiographs of sections cut to include sample sites. The histological picture was compared with the stable conductance reading and the cumulative resistance value for each site. Sensitivity and specificity values were calculated by randomly choosing stable conductance and cumulative resistance values to differentiate sound and carious sites. The results were presented as a series of receiver operating characteristics (ROC) curves and the optimum sensitivity and specificity values determined. 33% of sites had enamel caries and 32% had enamel and dentine caries. Results showed that both stable conductance readings and cumulative resistance measurements gave high and comparable sensitivity and specificity values for the diagnosis of dentine caries (sens. 92%, spec. 87% and sens. 88%, spec. 81%, respectively). However, when intra-examiner reproducibility was checked, stable conductance readings were more repeatable and achieved in shorter clinical time. In conclusion, stable conductance readings appear to be the most suitable for occlusal caries diagnosis.

Air Movements↗
PubMed1996

Measurement of pulmonary artery diastolic pressure from a right ventricular pressure transducer in patients with heart failure.

Recent studies have demonstrated that pulmonary artery diastolic (PAD) pressure can be measured from a transducer positioned in the right ventricle (RV) based on the finding that PAD and RV pressures are equal at the time of pulmonary valve opening, which is associated with the time of maximum positive rate of pressure development (dP/dtmax) in the ventricle. The objective of this study was to assess the correlation between estimated PAD (ePAD) pressure, obtained through a RV transducer, and actual PAD (aPAD) pressure in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of mitral regurgitation (MR) and tricuspid regurgitation (TR). Simultaneous measurements of pulmonary artery and RV pressures were obtained with a high-fidelity Millar catheter (Millar Instruments, Houston, TX) in 10 patients with New York Heart Association class III-IV heart failure who were being evaluated for cardiac transplantation. The overall correlation between ePAD and aPAD pressures was .92 (R2 = .878). This was not significantly different during the Valsalva maneuver (r = .96, R2 = .943), submaximal bicycle exercise (r = .87, R2 = .756), or infusions of dobutamine and nitroglycerin (r = .82, R2 = .730). The overall average difference between the average ePAD (24.6 +/- 7.0 mmHg) and aPAD (23.6 +/- 7.0 mmHg) pressures was 1.0 +/- 3.4 mmHg. The average difference between the two pressures in patients with mild to severe MR or TR was not different compared to those patients with no or trace MR or TR. The estimation of PAD pressure from an RV transducer is valid in patients with heart failure who have abnormal hemodynamics, reduced systolic function, and variable degrees of MR and TR. This correlation was observed at rest and during several provocative maneuvers. These data will be important for the development of a chronic, implantable hemodynamic monitor for patients with heart failure.

Adult↗