Biomedical subjects

R F Wilson

Publications and source records attributed to R F Wilson.

At least 91 records · Page 5Linked to original sources

PubMed1996

Antithrombin levels related to infections and outcome.

Antithrombin (AT) was measured in the plasma of 59 trauma patients at Detroit Receiving Hospital from July 1987 through December 1992 to determine how well low AT levels correlated with the outcome and development of later infections. The average lowest AT measured was 74 +/- 14% (SD) (normal = 75 to 120%). The mean lowest AT of the 11 trauma patients who developed sepsis (45 +/- 13%) was significantly lower than that of the 15 who developed an infection without sepsis (66 +/- 12%) (p < 0.001) and of the 33 who did not develop an infection (87 +/- 15%) (p <0.001). No patient with an AT always > or = 70% became septic or died, and no patient with an AT always > or = 90% developed an infection. In the 33 patients who did not develop infections, the mean AT levels rose progressively from 75 +/- 17% during the first 48 hours after admission to 91 +/- 11% during the next 48 hours. In contrast, the mean AT levels in the 26 patients who later developed infections were significantly lower (48 +/- 24%) during the first 48 hours and 60 +/- 16% during the next 48 hours (p < 0.016 and p <0.001). Of 10 patients with an AT < 60% in the first 96 hours, 9 (90%) developed an infection later. Low levels of AT, thus, may be of help in predicting infection, outcome, or both in severely injured patients.

Adult↗

PubMed1996

Intraoperative end-tidal carbon dioxide levels and derived calculations correlated with outcome in trauma patients.

BACKGROUND: To determine the relationship between the prognosis of seriously injured patients requiring emergency surgery and intraoperative end-tidal CO2 variables and "excess Pco2." METHOD: Retrospective chart review of 100 seriously injured patients admitted to Detroit Receiving Hospital and requiring major surgery (mortality rate of 40%). Standard intraoperative monitoring, including continuous capnography, plus arterial blood analyses every 15 to 30 minutes during surgery. RESULTS: After resuscitation for 45 to 90 minutes, 11 patients had a systolic blood pressure < 100 mm Hg and, of these patients, 10 (91%) died. Of the remaining 89 patients, mortality rates were 53% (16/30), with an end-tidal CO2 of 22 mm Hg or less, versus 24% (14/59) with an end-tidal CO2 of 23 mm Hg or more (p = 0.011). An arterial to end-tidal Pco2 difference of 13 mm Hg or more after resuscitation was associated with an increased mortality rate (50% (20/34 vs. 18% (20/55)) (p < 0.005). The mortality rate was particularly high, with a final arterial to end-tidal Pco2 difference of 12 mm Hg or more (73% (30/41) versus 17% (10/59) (p < 0.001). A final Paco2 excess (i.e., the amount by which the Paco2 was higher than expected from the bicarbonate) > 1.0 mm Hg was also associated with an increased mortality rate ((62% (33/53) vs. 15% (7/47)) (p < 0.001). CONCLUSION: Values derived from the end-tidal CO2 and the excess Pco2 should be monitored intraoperatively in critically injured patients. Efforts should be made to improve cardiac output and adjust ventilation to maintain an end-tidal Pco2 of 25 mm Hg or more, an arterial to end-tidal CO2 difference of 12 mm Hg or less, and an excess Paco2 of 1.0 mm Hg or less.

Adult↗

PubMed1996

An investigation of the validity of attachment level measurements with an automated periodontal probe.

There is a need for information on the validity of probing depth and attachment level measurements made with automated probes. In this study, 34 teeth in 9 patients were measured with the Florida probe from points marked with a bur prior to extraction. After extraction, connective tissue attachment levels were measured from the same points with a dissecting microscope. Mean measurements of attachment level were similar with probing (5.13 +/- 2.08 mm) and laboratory (5.18 +/- 2.26 mm) assessments. The correlation between these measurements was 0.72 (p < 0.001), and a t-test of the paired measurements showed no difference (t = 0.44; p = 0.66). The Florida probe thus showed satisfactory validity for this group of measurements of advanced periodontitis. However, there was substantial lack of agreement between individual probing measurements and the validity criterion of laboratory attachment level measurements, and the intra-class correlation coefficient was 0.46. It was concluded that the Florida probe was suitable for studies in which measurements were averaged, but not for longitudinal study of individual sites.

Adult↗

PubMed1996

A double-blind trial of tetracycline in the management of early onset periodontitis.

The aim of the study was to evaluate the adjunctive effect of systemic tetracycline (250 mg qds for 14 days) in sequential root planing and surgical phases of treatment in a randomised, double-blind controlled trial. 38 patients who were under 26 years of age, in good general health and with localised (15 test/15 control) or generalised (4 test/4 control) early onset periodontitis completed the non-surgical phase. Data were analysed by ANOVA using baseline covariates and transformations where appropriate. Improvements in probing depth, probing attachment level and bleeding on probing were significantly better in the group treated with adjunctive tetracycline, at 3 months post-treatment. 26 patients (13 test/13 control) subsequently completed the surgical phase (modified Widman flap surgery with adjunctive tetracycline or placebo as before) and were re-examined at 6 months and 12 months. In the test group, 58% of the originally affected teeth required surgery compared to 75% in the control group. Surgery produced further reductions in mean probing depths but no further gains in probing attachment. There were no further statistically significant differences between test and control groups for any of the clinical measures, although the tetracycline group appeared to maintain an advantage. In conclusion, systemically administered tetracycline is a useful adjunct in the management of early onset periodontitis, particularly in non-surgical treatment.

Administration, Oral↗

PubMed1996

Direct in vivo effects of nitric oxide on the coronary circulation.

To determine the direct in vivo effects of nitric oxide (NO) on the coronary circulation, we infused NO-saturated saline (1.0 +/- 0.1 mmol/l) into the coronary arteries of anesthetized dogs and measured changes in coronary blood flow velocity (CBFV) with a Doppler catheter, changes in coronary artery size with quantitative angiography, and transmural myocardial perfusion with radioactive microspheres. Boluses of NO (1-8 micromol) caused a stepwise increase in CBFV (3.1 +/- 0.3 x basal CBFV at 8 micromol) similar to that caused by adenosine (2.6 +/- 0.3 x basal CBFV, maximal dose). Continuous subselective infusions (0.1, 1.0, and 4.0 micromol/min) caused dose-dependent increases in CBFV (2.2 +/- 0.3 x basal CBFV at 4.0 micromol/min) and in epicardial artery diameter (+ 15 +/- 6% diam). Left main infusions (8 micromol/min) caused a stepwise increase in CBFV and in the endocardial-to-epicardial flow ratio without affecting systemic hemodynamics. Brief infusion of NO (2 min) did not significantly reduce acetylcholine-mediated endothelial NO release. Therefore, despite rapid metabolism, direct intra-arterial infusion of NO can be given at a rate sufficient to overwhelm metabolic elimination, providing direct evidence that NO is a potent in vivo coronary vasodilator. Moreover, the enhanced subendocardial vasodilator response to direct NO infusion suggests increased regional sensitivity to NO.

Animals↗

PubMed1996

Histological validation of electrical resistance measurements in the diagnosis of occlusal caries.

Diagnosis of occlusal caries is difficult from visual and radiographic examination. The use of electrical resistance measurement has been described previously and reported to be a potentially sensitive alternative technique. This is possibly due to the decreased resistance of carious pits and fissures. The aim of this study was to validate a prototype electrical caries monitor for the diagnosis of caries in pits and fissures in vitro using a microfocal radiographic technique. Thirty discrete sites were investigated in 10 extracted molar teeth. Electrical resistance measurements were recorded at each site and thick sections (approximately 0.65 mm) prepared for microfocal radiography. Microfocal radiography indicated that six sites were sound, 10 had enamel caries and 14 dentine caries. At a resistance value of 2.2 M(OMEGA), below which a site was regarded as carious and above which it was regarded as sound, electrical resistance measurements proved sensitive (92%) and specific (100%). Quantification of mineral content indicated that mineral loss in enamel may influence resistance measurement more than lesion depth.

Adult↗

PubMed1996

Metabolic and hemodynamic effects of a graded intracoronary insulin infusion in normal and fat anesthetized dogs: a preliminary study.

This study evaluated both cardiac hemodynamic and metabolic effects of a graded intracoronary artery infusion of insulin in four normal and five obese anesthetized dogs. Dogs were anesthetized with isoflurane, a catheter was advanced under fluoroscopic guidance into the coronary sinus and great cardiac vein, and a 20-MHz 3F coronary Doppler catheter was advanced into either the mid left anterior descending or circumflex coronary artery. A graded intracoronary insulin infusion was administered (starting at 0.3 mU/min and doubling every 40 minutes until a maximum dose of 2.4 mU/min was achieved). Coronary glucose extraction, coronary blood flow velocity, and coronary artery size were measured at each infusion rate. An intracoronary artery infusion of insulin stimulated myocardial glucose uptake in normal dogs. However, in high-fat-fed dogs, weight gain was associated with a reduction in the ability of insulin to promote glucose uptake by cardiac muscle and a rightward shift in the dose-response curve. In normal dogs, an intracoronary insulin infusion resulted in an increase in coronary blood flow and coronary vasodilation (with insulin coronary vascular resistance index decreases to 0.72 +/- 0.06, P<.01), whereas with weight gain the vasodilator response to insulin was lost. The loss of coronary artery vasodilation to local hyperinsulinemia in fat-fed dogs is consistent with other reports in obese or hypertensive humans that document an impairment in the action of insulin to increase skeletal muscle blood flow.

Animals↗

PubMed1996

Mnemonics.

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Education, Medical↗

PubMed1995

A re-evaluation of electrical resistance measurements for the diagnosis of occlusal caries.

Clinical and radiographic diagnosis of occlusal caries is difficult. Resistance measurements in pits and fissures have shown better sensitivity compared with the more conventional methods of diagnosis. Two machines have been manufactured for this purpose: the Vanguard and the Caries Meter L. The aims of this study were to calibrate the readouts of these machines against a variable standard resistance box and use the Vanguard to compare readings taken in vivo and in vitro after extraction of the teeth. The diagnostic accuracy of clinical, radiographic, Vanguard and Caries Meter L diagnoses were also assessed. One hundred occlusal sites in 40 teeth of 20 patients were investigated in vivo with the Vanguard, noting clinical and radiographic appearances. The teeth were then extracted and the Vanguard readings repeated in vitro, together with Caries Meter L readings. The in vivo/in vitro comparison between Vanguard readings showed excellent reproducibility (Cohen's Kappa = 0.80). The sensitivity and specificity for the different examination techniques at the enamel level of diagnosis were 27% and 89% for visual, 6% and 100% for radiographic, 81% and 78% for the Vanguard and 74% and 74% for the Caries Meter L. In conclusion, this study supports the renewed interest in resistance measurements as a diagnostic technique and indicates that the in vitro model used gives results comparable to those in vivo.

Adolescent↗

PubMed1995

Evidence for functional sympathetic reinnervation of left ventricle and coronary arteries after orthotopic cardiac transplantation in humans.

BACKGROUND: Structural sympathetic reinnervation of the transplanted human heart is believed to occur > 1 year after cardiac transplantation. The functional effects of reinnervating neurons, however, are undefined. METHODS AND RESULTS: To test directly for functional sympathetic reinnervation, we measured left ventricular or coronary hemodynamics in 11 patients < or = 4 months after transplantation, in 45 patients > or = 1 year after transplantation, and in 13 untransplanted, normally innervated patients. Sympathetic neurons were stimulated with left coronary injection of tyramine (10 micrograms/kg), which causes norepinephrine release from intact sympathetic nerve terminals. Reinnervation was defined as a measure of cardiac norepinephrine release after intracoronary tyramine injection. Left ventricular pressure was measured before and at 1-minute intervals after tyramine with a micromanometer-tipped catheter (Millar Instruments). Coronary blood flow velocity (CBFV) was measured with a 3F Doppler catheter (Numed), and coronary artery cross-sectional area was calculated using quantitative coronary angiography. In both early patients and patients studied > or = 4 months after transplantation without reinnervation (late denervated), there was no change in left ventricular function in response to tyramine (delta dP/dt = 31 +/- 61 and 49 +/- 54 mm Hg/s, respectively; P = NS). In transplant recipients with reinnervation (late reinnervated), left ventricular dP/dt rose significantly (delta dP/dt = 210 +/- 97 mm Hg/s; P < .05) but less than in healthy patients (delta dP/dt = 577 +/- 66 mm Hg/s; P < .05). In both early and late denervated patients, there was no change in CBFV in response to tyramine (CBFV = 1.02 +/- 0.1 and 1.0 +/- 0.1 x basal, respectively; P = NS). In late reinnervated patients, CBFV fell significantly (CBFV = 0.94 +/- 0.1 x basal; P < .05). In healthy patients, CBFV fell even more (CBFV = 0.88 +/- 0.1 x basal; P < .05). CONCLUSIONS: Stimulation of reinnervating sympathetic neurons with tyramine in transplant recipients causes a significant but subnormal increase in dP/dt and a transient decrease in CBFV, suggesting that reinnervating sympathetic neurons can produce physiologically meaningful changes in left ventricular function and coronary artery tone.

Angiography↗

PubMed1995

Coronary angioplasty, atherectomy and bypass surgery in cardiac transplant recipients.

OBJECTIVES: This study sought to analyze the outcomes of revascularization procedures in the treatment of allograft coronary disease. BACKGROUND: Allograft vasculopathy is the main factor limiting survival of heart transplant recipients. Because no medical therapy prevents allograft atherosclerosis, and retransplantation is associated with suboptimal allograft survival, palliative coronary revascularization has been attempted. METHODS: Thirteen medical centers retrospectively analyzed their complete experience with percutaneous transluminal coronary angioplasty, directional coronary atherectomy and coronary bypass graft surgery in allograft coronary disease. RESULTS: Sixty-six patients underwent coronary angioplasty. Angiographic success (< or = 50% residual stenosis) occurred in 153 (94%) of 162 lesions. Forty patients (61%) are alive without retransplantation at 19 +/- 14 (mean +/- SD) months after angioplasty. The consequences of failed revascularization were severe. Two patients sustained periprocedural myocardial infarction and died. Angiographic restenosis occurred in 42 (55%) of 76 lesions at 8 +/- 5 months after angioplasty. Angiographic distal arteriopathy adversely affected allograft survival. Eleven patients underwent directional coronary atherectomy. Angiographic success occurred in 9 (82%) of 11 lesions. Two periprocedural deaths occurred. Nine patients are alive without transplantation at 7 +/- 4 months after atherectomy. Bypass graft surgery was performed in 12 patients. Four patients died perioperatively. Seven patients are alive without retransplantation at 9 +/- 7 months after operation. CONCLUSIONS: Coronary revascularization may be an effective palliative therapy in suitable cardiac transplant recipients. Angioplasty has an acceptable survival in patients without angiographic distal arteriopathy. Because few patients underwent atherectomy and coronary bypass surgery, assessment of these procedures is limited. Angiographic distal arteriopathy is associated with decreased allograft survival in patients requiring revascularization.

Adolescent↗

PubMed1995

Intraoperative end-tidal carbon dioxide values and derived calculations correlated with outcome: prognosis and capnography.

OBJECTIVE: To determine how much information concerning resuscitation and outcome is provided by the end-tidal CO2 and derived variables obtained during surgery. DESIGN: Retrospective chart review. SETTING: Emergency hospital operating room. PATIENTS: One hundred critically ill or injured patients requiring major surgery and having a mortality rate of 41%. INTERVENTIONS: Standard intraoperative monitoring, including continuous capnography, plus arterial blood gas analyses every 1 to 1.5 hrs during surgery. MEASUREMENTS AND MAIN RESULTS: There was only a fair correlation between the PaCO2 and end-tidal CO2 (r2 = .14). The mortality rates in these patients were highest in those patients who had the lowest end-tidal CO2 values, the highest arterial to end-tidal CO2 differences, and the highest estimated alveolar deadspace fraction. A persistent end-tidal CO2 of < or = 28 torr (< or = 3.8 kPa) was associated with a mortality rate of 55% (vs. 17% in those patients with a higher end-tidal CO2). The mortality rate was also increased in patients with a persistent arterial to end-tidal CO2 difference of > or = 8 torr (> or = 1.1 kPa) (58% vs. 23%). CONCLUSIONS: End-tidal CO2 and derived values should be monitored closely in critically ill or injured patients. Efforts should be made--by increasing cardiac output and core temperature and by adjusting ventilation as needed--to maintain the end-tidal CO2 at > or = 29 torr (> or = 3.9 kPa) and the arterial to end-tidal CO2 difference at < or = 7 torr (< or = 1.0 kPa).

Adult↗

PubMed1995

Clinical and radiographic diagnosis of occlusal caries: a study in vitro.

Various methods of diagnosing occlusal caries have been described, but only visual, clinical examination and radiographic examination are commonly used in dental practice. This laboratory study investigated the ability of 12 examiners to detect the presence or absence of occlusal caries in 48 extracted molar teeth using these two techniques. The presence or absence of caries was subsequently verified by sectioning the teeth. Diagnosis from visual examination was poor, only 48.7% of lesions in dentine being detected. Radiographic diagnosis was better with 62.2% of dentine lesions being found. However, this increase in sensitivity of the diagnosis was accompanied by a decrease in specificity with the number of false positive diagnoses increasing when the radiograph was used. Therefore, although the bite-wing radiograph may be regarded as a safety net for the diagnosis of occlusal caries, it must be interpreted with caution bearing in mind the possibility of false positive diagnoses.

Dental Caries↗

PubMed1995

Occlusal variables, bruxism and temporomandibular disorders: a clinical and kinesiographic assessment.

Seventy-five patients suffering from myofascial pain, headaches and anterior disc displacement were assessed clinically and with a kinesiograph. Twenty-eight asymptomatic dental staff served as a control group. The prevalence of awareness of bruxism was significantly greater in our TMD patients than the controls. Bruxism patients recorded a higher prevalence of incisor dentine wear suggestive of a forward mandible posture. Class II, Division 1 malocclusions formed a significantly higher proportion of the TMD patient group than the controls. Kinesiographic recordings showed that the vertical and lateral components of movement from postural position to intercuspal were significantly greater in the patient group.

Adolescent↗

PubMed1995

Single-blind studies of the effects of improved periodontal health on metabolic control in type 1 diabetes mellitus.

Uncontrolled studies have suggested a beneficial effect of periodontal treatment on metabolic control of insulin-dependent diabetes mellitus (IDDM). We therefore conducted controlled single-blind studies, using current metabolic status indicators in IDDM subjects free of significant complications other than periodontal diseases. In the 1st study, 41 IDDM subjects with gingivitis and early periodontitis were randomly assigned to treatment (oral hygiene and scaling) or control groups. The study was completed by 16 experimental and 15 control subjects. Reassessment after 2 months showed a Hawthorne effect in the control group, and no difference between groups. However, further analysis showed a relationship between individual metabolic control variation and gingival inflammation. A 2nd study enrolled 23 IDDM subjects with advanced periodontitis, who were randomised to treatment (full initial therapy including root planning) or control groups. Only 1 subject failed to complete the study, owing to illness. In this study, a significant response to periodontal treatment was not accompanied by any improvement in metabolic control. These results support the concept that the effect of metabolic control may be predominant in the relationship between IDDM and periodontal health.

Adolescent↗

PubMed1995

Sealing ability of potential retrograde root filling materials.

The sealing ability of two potential retrograde root filling materials, a light-cured glass ionomer cement (Vitrebond) and a reinforced zinc oxide-eugenol cement (Kalzinol) was compared with that of amalgam using three methods of assessment: bacterial leakage, confocal microscopy and Indian ink leakage. the root canals of 80 extracted human single-rooted teeth were prepared. All the teeth were apicected, retrograde cavities were prepared and then divided into four equal groups of 20 teeth. The teeth were sterilised by autoclaving and the retrograde cavities filled with the test materials. In the control group, retrograde cavities in 10 teeth were left unfilled while cavities in another 10 teeth were sealed with cyanoacrylate cement. The teeth were first subjected to a bacterial leakage test using Enterococcus faecalis as a leakage marker. After which, the adaptation of the retrograde root fillings was assessed using a confocal optical microscope. Finally, the teeth were processed for the Indian ink leakage test. Bacterial leakage occurred in more teeth filled with amalgam compared with both Vitrebond and Kalzinol (P<0.001), between which there were no differences. With confocal microscopy, the size of the marginal gap was largest with amalgam and smallest with Vitrebond; all differences were statistically significant (<0.001). Finally, there was more Indian ink penetration with amalgam compared with both Vitrebond and Kalzinol (P<0.001) but there were no differences between Vitrebond and Kalzinol. Although there were individual differences within samples, overall, the three methods of assessment produced similar results. The sealing ability of Vitrebond and Kalzinol was similar and both materials were better than amalgam.

Carbon↗

PubMed1995

Elastase in gingival crevicular fluid from smokers and non-smokers with chronic inflammatory periodontal disease.

OBJECTIVE: To compare elastase concentrations in gingival crevicular fluid (GCF) from individual sites of smokers and non-smokers. MATERIALS AND METHODS: Twelve pairs of smokers and non-smokers with untreated, moderate to advanced chronic inflammatory periodontal disease were matched for gender, age, ethnicity and the clinical and radiographic extent of disease. Durapore filter strip samples were collected over 30 s from two mesiopalatal sites on upper left posterior teeth. Samples were analysed for: 1) polymorphonuclear neutrophil leucocyte (PMNL) cell counts; 2) PMNL elastase-alpha 1-antitrypsin complex in the GCF supernatant by ELISA; and 3) functional elastase, free or bound to alpha 2-macroglobulin, estimated from activity against N-tert-butoxycarbonyl-alanyl-prolyl-norvalyl-p-chlorothiobenzyl ester in supernatant and lysates of GCF PMNLs. RESULTS: There were no differences in disease parameters between groups except that bleeding on probing was less extensive in smokers (P<0.001). Cell counts and elastase content of crevicular PMNLs showed no differences between groups. Lower concentrations of elastase were found in GCF supernatants from smokers than non-smokers. This difference was observed for functional elastase (mean [s.d.] = 30.21 [17.60] against 73.77 [75.26] ng microliter(-1), p<0.05) and elastase complexed with alpha 1-antitrypsin (8.97 [6.54] ng microliter(-1) against 25.71 [22.07] ng microliter(-1), p<0.001). CONCLUSIONS: Smokers have lower elastase concentrations in GCF than non-smokers. Further investigation is required to elucidate the underlying cause and its relationship with periodontal disease.

Adult↗

PubMed1995

Direct effects of smooth muscle relaxation and contraction on in vivo human brachial artery elastic properties.

The direct effect of smooth muscle relaxation on arterial elastic properties is controversial. Studies in animals show both a decrease and an increase in elastic modulus. In human subjects, the contribution of smooth muscle to arterial elastic mechanics has been limited by difficulty in separating the direct effects of a vasodilator drug on the arterial wall from the indirect effects due to reduced blood pressure. The purpose of the present study was to assess the direct contribution of vascular smooth muscle to brachial artery elastic mechanics in normal human subjects in vivo. We measured brachial artery compliance and incremental elastic modulus (Einc) in eight normal subjects (age, 22 to 51 years) by using intravascular ultrasound. A 3.5F 30-MHz intravascular ultrasound catheter was placed through a sheath into the brachial artery, and intraarterial pressure, cross-sectional area, and wall thickness were measured simultaneously under baseline conditions and after the administration of intra-arterial nitroglycerin (100 micrograms) and norepinephrine (1.2 micrograms). A pressurized cuff surrounding the brachial artery was inflated to reduce transmural brachial artery pressure. Using this technique, we were able to measure the following arterial characteristics for the first time in human subjects in vivo: (1) the effective unstressed arterial radius and (2) the pressure-area, stress-strain, and pressure-Einc relations over a wide pressure range (0 to 100 mm Hg). Intra-arterial nitroglycerin increased brachial artery area by 22% and intraarterial norepinephrine decreased brachial artery area by 17% at 100 mm Hg transmural pressure (P < .001 versus baseline).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗