OESOPHAGEAL CONTRACTILITY DURING TOTAL I.V. ANAESTHESIA WITH AND WITHOUT GLYCOPYRRONIUM

Somatic movement and spontaneous and provoked oesophageal contractionswere noted at time of incision in 51 patients receiving totali.v. anaesthesia with alfentanil and propofol. Probit analysisof the dose of propofol required to prevent spontaneous movementrevealed an ED₅₀ (95% confidence limits) of 2.5 (1.8-2.9) mgkg^–1 h^–1 and ED₉₅ of 4.7 (4.0-7.5) mg kg^–1h^–1. Corresponding venous blood concentrations gave anEC₅₀ of 1.2 (0.4-1.6) µg ml^–1 and an EC₉₅ of 4.0(2.8-18.5) µg ml^minus;1. ED₅₀ of propofol for preventingspontaneous oesophageal contraction was 3.0 (1.9-3.6) mg kg^–1h^–1. ED₉₅ was 6.9 (5.0-27.3) mg kg^–1 h^–1;EC₅₀ for oesophageal contractions was 1.7 (0.7-2.3) µgml^–1 and EC₉₅ was 5.9 (3.7-70.6) µg ml^–1.Another group of 10 patients were given glycopyrronium 5 µgkg^–1 at induction; oesophageal contractility was significantlyreduced in this group. Preliminary results of this research were presented to the AnaestheticResearch Society, Nottingham, July 1990. ^*Department of Anaesthesia, Derriford Hospital, Plymouth, DevonPL6 8DH. Department of Anaesthesia, Darlington Memorial Hospital, Darlington,Durham DL3 6HX.     

Infection of left ventricular thrombus in a patient with silent myocardial infarction -- a unique complication

A 72-year-old male was admitted to hospital with exertionaldyspnoea of recent onset. Echocardiography showed a left ventriclewhich was severely hypokinetic on the anteroseptal and anteriorwall with an akinetic inferior wall and apex. A string of globularmasses was seen to be floating in the left ventricle, attachedto the septum near the apex. Coronary arteriography showed severetwo-vessel disease. Urgent surgery revealed degenerated thrombusin the left ventricle containing green pus. The infected thrombuswas attached to an area of septal infarction. The pus-filledthrombus was removed and by-pass grafting was effected. No infectiveorganism was identfled.     

Activated T Lymphocytes of the Synovial Membrane in Rheumatoid Arthritis and Other Arthropathies

Immunohistological techniques were used to identify activated T lymphocytes within the synovial membrane of patients with rheumatoid arthritis, using the monoclonal antibody (MoAb) RFT2, which identifies a 40-k dalton molecule preferentially expressed by T blasts or activated cells. Using this reagent together with a monoclonal 'cocktail' that stains all T cells, cell counts on consecutive sections of rheumatoid synovium revealed that up to 50% T lymphocytes were RFT2+ (range 9.3-50.2%, mean 25.4). Subsequent analysis using combination immunofluorescence demonstrated that over 90% of these activated cells were of the T4+ subset. Furthermore all these cells appeared to be Leu8-, suggesting that the activated population were exclusively 'true helpers' and not suppressor inducers. Studies indicated that 50% of the RFT2+ cells were positive with anti-Tac MoAb. Comparisons with tissues from other arthropathies demonstrated that this relatively high proportion of RFT2+ cells was a feature restricted to rheumatoid arthritis, although biopsies from patients with psoriatic arthritis and ankylosing spondylitis also contained activated cells. Biopsies of Reiter's syndrome, osteo-arthritis, and pigmented villonodular synovitis contained no activated cells, nor were any seen in sections of normal synovium. The presence in rheumatoid synovial membrane of activated T cells which are only of the T4+, Leu8- subset adds weight to the suggestion that local immunoregulatory dysfunction contributes to the chronic inflammation of rheumatoid arthritis.     

Efficacy of once daily bisoprolol in stable angina pectoris: an objective comparison with atenolol and long term follow-up

Bisoprolol is a new cardioselective beta-blocker with a longhalf-life. The efficacy of once daily bisoprolol (10 mg) andatenolol (100 mg) was assessed in 20 patients with stable anginausing a placebo controlled double-blind randomized crossoverprotocol. Efficacy was assessed by computer assisted treadmillexercise testing with monitoring of leads CMS and CC5, carriedout 22–24 h after the last dose. The mean±SEM exercisetime on placebo was 6.5±0.4 min increasing to 7.8±0.5min on bisoprolol (P<0.001) and 8.6±0.6 mins on atenolol(P<0.001). The time to 1 mm ST depession in CM5 and CC5 wasalso prolonged significantly with both drugs. The mean basalresting heart rate of 84±4 bpm decreased to 63±2bpm on bisoprolol ( P<0.001 )and 64±3 bpm on atenolol(P<0.001), with a significant decrease in the peak exerciseheart rate seen with both drugs (P<0.001). The peak rate-pressureproduct was 175±8 after placebo, 146±7 (P<0.001)with bisoprolol and 149±5 (P<0.001) after atenolol.One patient was withdrawn because he suffered a myocardial infarction.Eighteen patients were prescribed bisoprolol 10 mg once a dayfor 6 weeks and an exercise test was performed at the end ofthis period. Bisoprolol retained its efficacy at the end ofthis period and was well tolerated. This data suggests thatbisoprolol is an effective anti-anginal agent, comparable inefficacy and duration of action with atenolol, which is suitablefor once-daily administration.     

Comparison of radionuclide ventriculography and 2D echocardiography for the measurement of left ventricular ejection fraction following acute myocardial infarction

To compare the measurement of left ventricular ejection fractionobtained by two-dimensional echocardiography and by radionuclideventriculography in patients following acute myocardial infarction,49 consecutive patients with acute myocardial infarction underwentechocardiography and radionuclide ventriculography on the sameday, pre-discharge. Left ventricular ejection fraction was assessedby two blinded observers for each method and reproducibilitywas also assessed for each technique. The limits of agreementfor the differences in ejection fraction (%) between the twomethods was –11.4, 12.2; the mean difference 0.4 was notsignificantly different from zero. The limits of agreement forthe intra- and inter-observer differences in ejection fractionby radionuclide ventriculography were –9.4, 7.6 and –86,11.0, respectively; the mean differences –0.9 and 1.2were not significantly different from zero. The limits of agreementfor the intra- and inter-observer differences by echocardiographywere –5.8, 6.6 and –8.9, 9.5 respectively; the meandifferences 0.4 and 0.3 were not significantly different fromzero. Thus, two-dimensional echocardiography compares well withradionuclide ventriculography for the assessment of ejectionfraction without the disadvantage of radiation.     

Redox control of β2‐glycoprotein I–von Willebrand factor interaction by thioredoxin‐1

Summary. Background: β₂‐Glycoprotein I (β₂GPI) is an abundant plasma protein that is closely linked to blood clotting, as it interacts with various protein and cellular components of the coagulation system. However, the role of β₂GPI in thrombus formation is unknown. We have recently shown that β₂GPI is susceptible to reduction by the thiol oxidoreductases thioredoxin‐1 and protein disulfide isomerase, and that reduction of β₂GPI can take place on the platelet surface. Methods: β₂GPI, reduced by thioredoxin‐1, was labeled with the selective sulfhydryl probe N^a‐(3‐maleimidylpropionyl)biocytin and subjected to mass spectrometry to identify the specific cysteines involved in the thiol exchange reaction. Binding assays were used to examine the affinity of reduced β₂GPI for von Willebrand factor (VWF) and the effect of reduced β2GPI on glycoprotein (GP)Ibα binding to VWF. Platelet adhesion to ristocetin‐activated VWF was studied in the presence of reduced β₂GPI. Results: We demonstrate that the Cys288–Cys326 disulfide in domain V of β₂GPI is the predominant disulfide reduced by thioredoxin‐1. Reduced β₂GPI in vitro displays increased binding to VWF that is dependent on disulfide bond formation. β₂GPI reduced by thioredoxin‐1, in comparison with non‐reduced β₂GPI, leads to increased binding of GPIbα to VWF and increased platelet adhesion to activated VWF. Conclusions: Given the importance of thiol oxidoreductases in thrombus formation, we provide preliminary evidence that the thiol‐dependent interaction of β₂GPI with VWF may contribute to the redox regulation of platelet adhesion.     

RESPIRATORY COMPLICATIONS AND HYPOXIC EPISODES DURING INHALATION INDUCTION WITH ISOFLURANE IN CHILDREN

We have studied the incidence of respiratory complications andhypoxic episodes during inhalation induction with isofluranein 75 healthy unpremedicated children. Problems occurred lessfrequently when 4% isoflurane in oxygen was used from the outsetthan with traditional techniques using nitrous oxide and a graduallyincreasing inspired vapour concentration. The improved resultsobserved with the former method may be secondary to more rapiduptake of vapour so that the second stage of anaesthesia characteristicof anaesthetic ethers is shortened considerably.     

Simultaneous measurement of left ventricular function and myocardial perfusion during a single exercise test: dual isotope imaging with gold-195 m and thallium-201

The state of left ventricular function and myocardial perfusionare important determinants of prognosis in patients with coronaryartery disease and information on both can be valuable for planningindividual patient management. We have studied the feasibilityof simultaneous measurement of left ventricular ejection fractionwith ultra short-lived gold-195 m (half life 30.5 seconds) andmyocardial perfusion with thallium-201, at rest and after exercisewith a single-crystal gamma camera. The results with first-passradionuclide angiocardiography (RNA) using gold-195 m at restwere reproducible and agreed closely with the results obtainedusing technetium-99 m equilibrium radionuclide angiocardiography(r = 0.93). Ejection fraction by firstpass gold-195 m RNA duringsemi-supine ergometric exercise decreased by >5% in 13 outof 18patients with coronary artery disease and stable angina.Simultaneous myocardial imaging with thallium-201 was abnormalin all patients. The change in regional wall motion abnormalityscore during exercise correlated with the change in myocardialperfusion (r = 0.71, P<0.01) and with the change in globalleft ventricular ejection fraction (r = 0.77, P<0.001). Thewidely differing energy levels and half-lives of gold-195 mand thallium-201 made it possible to separate clearly the imagesdue to each radionuclide. This study has demonstrated the feasibilityof simultaneous or sequential assessment of left ventricularfunction and myocardial perfusion during a single exercise test,a technique which can offer advantages in clinical evaluationof patients with coronary artery disease.