Summary and conclusionsAn 11-week crossover study was carried out in which 12 subjects smoked high-nicotine (1-84 mg standard yield) and low-nicotine (0-6 mg) cigarettes after an initial period of smoking their usual brands with a medium-nicotine yield (mean 1-4 mg). Plasma and urine nicotine concentrations, carboxyhaemoglobin (COHb) concentration, puffing behaviour, 24-hour cigarette consumption, and butt nicotine content were measured. The changes in plasma nicotine and blood COHb concentrations showed that the smokers compensated for about two-thirds of the difference in standard yields when switched to either high-or low-nicotine cigarettes. Thus, compared with the medium-nicotine brand, the intake of nicotine and carbon monoxide was only about 10% higher when subjects smoked the high-nicotine cigarettes, which had a standard yield 30-40% higher than the medium brands; and only about 15% lower when they smoked the lownicotine cigarettes, which had a standard yield about 50% lower than the medium brands. Butt nicotine content and urine nicotine concentrations followed a similar pattern. Changes in puffing behaviour and in 24-hour cigarette consumption were only slight.The results show clear evidence of both upward and downward self-titration of nicotine and carbon monoxide (and tar) intakes when smokers change to cigarettes with standard yields that differ over the range studied.Introduction Do smokers adjust their nicotine intake to some habitual optimal level when smoking cigarettes of different strengths ? Evidence concerning this self-titration hypothesis is conflicting, but a clear answer is important in planning and evaluating the effects of safer-smoking strategies in which smokers are advised to switch to cigarettes of decreased nicotine, tar, and carbon

Attitudes towards transplantation were investigated in national surveys of the general public (n = 1471), the medical profession (n = 590) and key clinical staff in units referring potential organ donors (n = 380). A clear majority of doctors would like to see more transplants. Only 16 per cent of doctors opposed them on cost grounds, and a 50 per cent 5-year survival rate is seen as more than adequate clinical justification. However, doctors are less supportive of liver and heart grafts than of kidney and cornea grafts. Few lay people would refuse donation of specific organs, but 30 per cent worry that doctors might be pressured into removal of organs when they are not sure the patient is dead. Religious or moral objection is rare. Intensive care unit staff felt the most important factor restricting organ harvest in their own units was dislike of adding to relatives' distress, followed by lack of training in approaching relatives and adverse media publicity. Only 11 per cent thought reservations on brain stem death a likely or possible influence. Enhanced public awareness of the need for transplants was seen as the most important means of increasing organ harvest. Required request would be controversial and perhaps impossible to implement. We conclude that the time, effort and expense involved in potential organ donation do not play a substantial part in limiting referral. Neither do reservations about brain stem death. Increased training of staff (both in communication skills and in the professional responsibility to encourage donation) and greater public awareness are seen as the twin foundations of a realistic approach to enhancing referral.

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The relation between blood carboxyhaemoglobin (COHb) and plasma nicotine concentrations was studied in a group of 12 smokers smoking cigarettes of three levels of standard delivery. While the intake of carbon monoxide from a single cigarette was unrelated to the intake of nicotine, presmoking "trough" concentrations of the two substances (reflecting longer-term exposure) were highly correlated. Various other measures of nicotine exposure were at best only moderately correlated with blood nicotine concentrations.Thus trough COHb concentrations might be used to provide a reliable indication of the exposure to nicotine of individual smokers smoking the same type of cigarette, and of the relative exposure to nicotine of populations smoking cigarettes of different standard deliveries.

SummaryResponse to social cues was studied in two groups of smokers; 14 sedative smokers, who report smoking predominatly under high arousal conditions e.g. anxiety, and 14 stimulant smokers, whose ‘need’ to smoke is greatest under low arousal conditions e.g. boredom. The smoking behaviour of each group was studied in two experimental conditions, during which subjects watched one of two 30 minute video films. The videos were similar apart from the presence of clips of people smoking in one of the films. Seeing people smoke on the video significantly increased smoking rate and intensity in stimulant smokers only. This finding suggests that establishing the precise cues to which different kinds of smokers respond is important in broadening our understanding of the theoretical distinctions made between smokers.