Dental amalgam and selenium in blood.

It has been suggested that selenium (Se) exhibits protective effects against mercury (Hg) toxicity in humans due to formation of a Hg-Se complex bound to selenoprotein P in blood. The aim of the present study was to investigate Se concentrations in persons who had been examined with respect to general health problems associated with dental amalgam fillings. The Se concentrations were determined in whole-blood samples of 80 individuals by hydride generation atomic absorption spectrometry. The subjects comprised two main groups: 21 healthy controls with amalgam fillings and 20 patients who claimed symptoms from existing amalgam fillings. The median concentration of Se in blood (119.2 microg/L) was statistically significantly lower in subjects who claimed symptoms of mercury amalgam illness than in healthy subjects with amalgam (130.3 microg/L). The difference was more evident in individuals with more than 35 amalgam surfaces (P=0.003). Additional control groups without amalgam fillings comprised 19 healthy controls without amalgam experience and 20 subjects who have had amalgam fillings removed due to suspected symptoms associated with amalgam. The Se concentrations in these groups were not different from those with amalgam. It is indicated that persons with ill health self-related to dental amalgam might have a Se metabolism different from that of healthy people.

Diagnostic value of a chelating agent in patients with symptoms allegedly caused by amalgam fillings.

The chelating agent 2,3 dimercaptopropane-1-sulfonate (DMPS) has been used in a mercury mobilization test for diagnoses in illnesses allegedly associated with the presence of amalgam restorations. DMPS is an accepted antidote to heavy metal poisoning. The aim of the present study was to evaluate the diagnostic value of DMPS in patients with symptoms self-related to their amalgam fillings. The subjects consisted of four groups: 19 healthy controls without amalgam experience; 21 healthy controls with amalgam fillings; 20 patients who claimed symptoms of "mercury poisoning" from dental amalgam; and 20 patients who had amalgam fillings removed because of such symptoms. DMPS (2 mg/kg body weight) was injected intravenously, and urine was collected prior to the injection, 30 and 120 min after the injection, and throughout the next 22 hrs. The samples were analyzed for total mercury by cold vapor atomic absorption spectrophotometry. The total median amounts of mercury excreted over 24 hrs for those with complaints allegedly associated with amalgam and for the healthy controls with amalgam fillings were similar. Persons with amalgam fillings excreted about three times more mercury than those without. The controls, who had never had amalgam fillings, and the subjects who had had their fillings removed excreted median amounts of 8.5 microg and 7.2 microg mercury, respectively. The present DMPS challenge test did not differentiate between patients with or those without complaints self-related to their amalgam fillings but did confirm the higher mercury values in patients with dental amalgam.

Dental gold alloys and contact hypersensitivity.

A total of 172 patients referred to the Norwegian National Adverse Reaction Group were patch-tested with a dental series. Of these, 25% showed a positive reaction to gold sodium thiosulfate or potassium dicyanoaurate. There was a statistically significant correlation (p=0.0019) between the presence of dental gold and a positive patch test to gold. There was a statistically significant correlation between ear piercing and a positive patch test to gold (p=0.04). In most cases, we did not find clinical correlates to positive patch tests to gold. 2 patients with objective and subjective oral/perioral and general symptoms are described as case reports. Their symptoms disappeared when gold restorations were removed. We conclude that there is an overrepresentation of gold allergies among those with dental restorations containing gold.

In vitro lymphocyte reactivity to gold compounds in the diagnosis of contact hypersensitivity.

The use of the lymphocyte transformation test (LTT) in the diagnosis of contact hypersensitivity to gold was studied in 8 patients who had positive patch tests to gold salts, and in 8 control subjects who were negative to such patch tests. Gold sodium thiosulfate and gold chloride were added to cultures of lymphocytes, which were labeled by 3H-thymidine after 96 h. The lymphocyte stimulation index was calculated as the beta-counts in stimulated cultures divided by those in control cultures. The index was statistically significantly higher for the patient group (p=0.005-0.04) than for the control group. Levels of interferon-gamma (IFN-gamma) were determined for the supernatants of the lymphocyte cultures. An index IFN-gamma, which is defined as the level of IFN-gamma in stimulated cultures divided by that in control cultures, was statistically significantly higher for the patient group (p=0.01-0.006). The LTT stimulation index showed specificity and sensitivity between 67 and 80%, the respective values for Index IFN-gamma being between 73 and 100% when the patch test was used as a reference method. Evaluation of lymphocyte reactivity might be of future interest in the diagnosis of allergic reactions to gold if the sensitivity and specificity can be improved.

Haemodynamic effects of high-dose vecuronium compared with pancuronium in beta-blocked patients with coronary artery disease during fentanyl-diazepam-nitrous oxide anaesthesia.

BACKGROUND: Different combinations of neuromuscular blockers and opioids have been used in patients with angina pectoris to provide cardiovascular stability and reduce risk of myocardial ischaemia during anaesthesia. METHODS: We have compared the haemodynamic effects of high-dose vecuronium (0.3 mg kg-1) with those of a standard dose of pancuronium (0.1 mg kg-1) in patients scheduled for coronary artery bypass grafting during fentanyl-diazepam-nitrous oxide anaesthesia. All patients were receiving beta-adrenergic blocking agents. The given doses of vecuronium and pancuronium are equieffective with respect to duration of neuromuscular blockade. RESULTS: During a 25-min experimental period following the administration of the randomly selected drug, no significant changes in the haemodynamic parameters were observed in the vecuronium group. The administration of pancuronium, however, resulted in a significant mean increase in heart rate (20%), rate-pressure product (23%) and cardiac index (21%). Following endotracheal intubation in the pancuronium group, we observed an additional significant increase in mean arterial pressure and rate-pressure product. CONCLUSION: High-dose administration of vecuronium has minimal haemodynamic effects and may thus offer a better alternative than pancuronium for long-lasting neuromuscular blockade in patients with coronary artery disease during fentanyl-diazepam-nitrous oxide anaesthesia.

Duration of vecuronium-induced neuromuscular blockade predicted by dose and onset time.

We investigated the adequacy of using dose and onset time as variables to predict the duration of action of vecuronium in patients. The onset time until 95% twitch depression and the duration until 25% twitch recovery were measured for doses ranging from 0.1 to 0.3 mg kg-1. Statistical analyses were performed by simple and multiple regressions. The duration of action was better predicted by dose (r2 = 0.61) than by onset time (r2 = 0.51). However, the predictability was significantly improved by a multiple regression model of the variables, and the explanatory power was largest when using the square root of duration as the dependent variable (r2 = 0.69). We conclude that the duration of neuromuscular blockade after vecuronium can be predicted more accurately by the combined use of dose and onset time than by dose alone.

Midazolam does not potentiate the effect of vecuronium in patients.

Reports of midazolam interaction with vecuronium in animals prompted us to compare midazolam (0.25 mg kg-1) with thiopentone (5 mg kg-1) for possible interactions with vecuronium in patients, when used for induction of anaesthesia. After the administration of either of the two induction agents, the patients received vecuronium 0.1 mg kg-1. The onset time, duration of action and 25-75% recovery index of the neuromuscular blockade were recorded by measuring the force of thumb adduction evoked by ulnar nerve stimulation. We found no differences between patients receiving either midazolam or thiopentone in their response to vecuronium. In three of the ten patients receiving midazolam, the injection of this drug produced a 8-29% reduction of the initial twitch height.

Comparison of large dose of vecuronium with pancuronium for prolonged neuromuscular blockade.

Dose-duration relationships for vecuronium were determined and the duration of action produced by vecuronium 0.3 mg kg-1 shown to equal that of pancuronium 0.1 mg kg-1. Using these doses, the neuromuscular blocking properties and cardiovascular effects of the two drugs were compared. With large dose administration of vecuronium (0.3 mg kg-1), both the onset time (mean 81 s) and the 25-75% recovery index (mean 13.9 min) were about one-half those associated with pancuronium (mean 168.5 s and 29.3 min, respectively). The duration of action until 25% recovery was similar with both drugs. There was no evidence of cardiovascular instability with the large dose of vecuronium. Heart rate, however, was significantly slower (range 89.7-94.2% of control) 2-20 min after the injection of vecuronium. Vecuronium 0.3 mg kg-1 may have more favourable neuromuscular blocking effects than pancuronium 0.1 mg kg-1 and may be preferable to pancuronium when prolonged neuromuscular blockade is required.