Effects of anaesthetics on membrane mobility and locomotor responses of human neutrophils.

The morphological response of neutrophils to chemotactic factors is characterized by an immediate change (in seconds) from a spherical to an irregular shape. Within two or three minutes, the cells assume the head-tail polarity typical of locomotor cells. In this study the effects of the anaesthetic drugs, propofol and thiopentone, on the time-sequence of the morphological response of human neutrophils to the chemotactic peptide fMet-Leu-Phe were examined. At concentrations seen in the plasma during anaesthesia, both drugs inhibited both the rate and degree of the neutrophil chemotactic response. The effect of propofol was not attributable to its lipid vehicle, as 10% intralipid alone had no effect on neutrophil polarization. Plasma membrane reorganization occurs during polarization of neutrophils, resulting in morphological and functional changes which prepare the cells for chemotaxis and phagocytosis. Fluorescence recovery after photobleaching (FRAP) was used to investigate effects of the anaesthetics on membrane lipid behaviour. With a lipid probe, the proportion of mobile lipid in neutrophils exposed to propofol or thiopentone was reduced. There was a less significant reduction with intralipid which also caused reduction in velocity of lateral diffusion of the probe. These findings suggest that the inhibitory effects of anaesthetics on neutrophil locomotion are related to reductions in fluid mobility of the plasma membranes of anaesthetic-treated cells.

The occupational hazard of human immunodeficiency virus and hepatitis B virus infection. I. Perceived risks and preventive measures adopted by anaesthetists: a postal survey.

We have conducted a postal survey of members of the Association of Anaesthetists to ascertain perceived risks and preventive measures adopted with regard to the occupational hazard of Human Immunodeficiency Virus and Hepatitis B Virus infection. Despite recognition of the infection risk and the adoption of appropriate measures when managing known infected patients, the majority of anaesthetists have not implemented simple precautions in their daily routine work. Less than 16% of respondents routinely wear gloves and more than one in three still resheath needles. It would appear that the recommendations of the Association with regard to universal safety precautions have not been implemented by the majority of its members.

The occupational hazard of human immunodeficiency virus and hepatitis B virus infection. II. Effect of grade, age, sex and region of employment on perceived risks and preventive measures adopted by anaesthetists.

The effect of grade, age, sex and region of employment on the attitude of anaesthetists to the possible risk of Human Immunodeficiency Virus (HIV) and Hepatitis B Virus (HBV) infection and the measures adopted to minimise the risk were assessed. As a group, anaesthetists in training were more concerned than consultants about the risk of HIV or HBV infection and, as a consequence, were more likely to adopt protective measures. A similar variation was seen with age, younger anaesthetists being more concerned about the risk of infection and adopting preventive measures in greater numbers than their older colleagues. The sex of the anaesthetist had minimal effect on their attitude. Despite the marked variation in the incidence of both HIV and HBV, the attitude of anaesthetists to the risk of infection and the numbers adopting simple preventive measures did not vary significantly on a regional basis throughout the country. However, there was a significant inter-regional variation in the availability and uptake of HBV immunisation (p < 0.01) and knowledge of the existence of local policy guidelines for the management of known HIV or HBV positive patients (p < 0.01).

Comparison of the inhibitory effect of propofol, thiopentone and midazolam on neutrophil polarization in vitro in the presence or absence of human serum albumin.

Anaesthetic agents inhibit some aspects of immune function and this may be clinically important when prolonged infusions are used in an intensive care unit. We have studied the effects of propofol, thiopentone and midazolam on neutrophil polarization in vitro. At concentrations seen in plasma during anaesthesia, propofol and thiopentone produced significant (approximately 50%) and comparable degrees of inhibition. Inhibition was complete with greater concentrations of these drugs. When compared with equivalent concentrations of midazolam, propofol produced more inhibition (P less than 0.01) at all concentrations investigated, except the smallest. Midazolam produced no effect at clinically relevant concentrations. The effect of propofol was not attributable to its lipid carrier vehicle, as 10% Intralipid alone augmented neutrophil polarization. Human serum albumin conferred some degree of protection against the inhibition produced by clinically relevant concentrations of propofol and thiopentone, but not that produced by greater concentrations of these drugs.