Diagnosis and treatment of nicotine dependence with emphasis on nicotine replacement therapy. A status report

Tobacco use is a global health care problem. Repetitive exposure to nicotine produces neuroadaptation resulting in nicotine dependence. Cigarette smoking is particularly addictive due to the repeated delivery of bolus doses of nicotine to the bloodstream. Although compulsive tobacco use is sustained by nicotine addiction, it is the toxic combustion products in tobacco smoke such as carbon monoxide and oxidant gases that adversely affect the cardiovascular system. Smoking cessation produces significant health benefits and is a very cost-effective intervention. Evidence that nicotine is the addictive component of tobacco provides the rationale for using nicotine replacement therapy to aid cessation. Nicotine replacement therapy doubles successful smoking cessation rates and evidence-based guidelines for the treatment of tobacco addiction recommend routine use of nicotine replacement therapy, particularly in heavily dependent smokers. Success rates of up to 40% can be achieved in specialist clinics. Despite early concerns regarding the safety of nicotine replacement therapy in smokers with heart disease, it is now clear that the health risks of using nicotine replacement therapy to assist such patients to stop, or significantly reduce, smoking far outweigh any treatment-related risks.

High refractive errors and the accident/incident rate in Canadian medical category 1 pilots

BACKGROUND

Since 1982, the Canadian Civil Aviation Medicine Division has medically certified to Category 1 standard commercial and airline transport pilots whose visual correction was in excess of +/- 3.5 diopters (D).

METHOD

A review between the years 1982 and 1991 of the 253 pilots who had been medically certified, although they were outside the standard, was conducted. We determined if there was any difference in the accident/incident rate in this group as compared with the Canadian general aviation population standardized to a rate per 100,000 flying hours. The 253 pilots were divided into two groups with Group A having a refractive error outside the range +/- 5.7 D and Group B having a refractive error range of +/- 3.5 to +/- 5.6 D.

RESULTS

The Group A rate was within the expected range of accidents and incidents per 100,000 flying hours. The accident/incident rate in Group B was significantly lower than the expected average.

CONCLUSION

In conclusion, the Canadian Civil Aviation Medicine Division's policy on granting "flexibility" to applicants with moderate to high refractive errors has not affected adversely the accident or incident rate and therefore has not compromised aviation safety.

Atrial natriuretic factor attenuates prostaglandin E2-stimulated plasma renin activity in humans

The effect of atrial natriuretic factor (ANF) 99-126 3 or 10 pmol/kg/min on increase in plasma renin activity (PRA) stimulated by a 30-min infusion of prostaglandin E2 (PGE2) 80 ng/kg/min was studied in healthy salt-replete male volunteers. PGE2 increased PRA to approximately 230% of basal levels (p less than 0.001). Concomitant infusion of ANF 3 pmol/kg/min significantly attenuated this rise in PRA to approximately 130% of baseline values (p = 0.02, n = 10). A quantitatively similar effect was observed with ANF 10 pmol/kg/min (n = 5). We suggest, in light of previous findings, that this inhibitory effect of ANF probably represents a nonspecific action rather than a specific effect of ANF on PGE2-mediated increases in PRA.

Studies on the disposition of Li+ in the guinea-pig and rat

Rats and guinea-pigs were given LiCl acutely (2 mmol/kg IP or intragastrically) or chronically (daily doses 0.6-4 mmol/kg) and plasma, erythrocytes, kidney, liver and brain were analysed for Li+. Generally, after acute LiCl, tissue Li+ levels followed changes in plasma Li+ levels. However, brain Li+ concentrations changed more slowly and in the rat, but not in the guinea-pig, paralleled erythrocyte Li+ concentrations. Li+ was absorbed more slowly from the gastrointestinal tract of the rat. After chronic LiCl, the erythrocyte:plasma Li+ ratio was about 0.1 in the guinea-pig and about 2 in the rat. Relative Li+ tissue concentrations were as follows: guinea-pig, plasma greater than kidney greater than liver greater than brain greater than erythrocyte;rat much greater than erythrocyte = brain greater than liver = plasma. A Na+-dependent Li+ efflux was demonstrated in the erythrocytes of the guinea-pig and human, but not the rat. This process was inhibited by phloretin (0.2 mM), but not frusemide (2.0 mM). The marked differences in the activity of the erythrocyte Na+-dependent Li+ countertransport process in the guinea-pig and rat could extend to other tissues and explain the observed interspecies differences in tissue Li+ distribution.