Nicotine yields of cigarettes, plasma nicotine in smokers, and public health

Nicotine increases the collagen-degrading ability of human gingival fibroblasts

BACKGROUND AND OBJECTIVE

The objective of this study was to determine the effects that nicotine and the combination of nicotine and Porphyromonas gingivalis supernatant have on human gingival fibroblast-mediated collagen degradation.

MATERIAL AND METHODS

Human gingival fibroblasts were cultured with 25-500 microg/ml of nicotine in collagen-coated six-well plates. On days 1-5, the conditioned media was collected for zymography and western blot analyses of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). The cells were then removed and the collagen cleavage visualized by Coomassie blue staining. To examine the combined effect, 250 microg/ml of nicotine and 10% v/v culture supernatant of P. gingivalis ATCC 33277 were added to the human gingival fibroblasts. The mRNA levels of multiple MMPs and TIMPs were monitored.

RESULTS

Nicotine increased the human gingival fibroblast-mediated collagen cleavage. The MMP-14 and MMP-2 produced by the nicotine-treated human gingival fibroblasts more readily underwent zymogen activation. Nicotine treatment resulted in TIMP-2 redistribution to the cell surface. The mRNAs of multiple MMPs and TIMPs were unaltered by nicotine. An additive collagen cleavage effect was observed when the human gingival fibroblasts were treated with both nicotine and P. gingivalis.

CONCLUSION

Nicotine increased human gingival fibroblast-mediated collagen degradation, in part through the activation of membrane-associated MMPs. Nicotine and P. gingivalis had an additive effect on human gingival fibroblast-mediated collagen degradation.

Smokers' misperceptions of light and ultra-light cigarettes may keep them smoking

INTRODUCTION

This study examined smokers' understanding of the relative tar deliveries of Ultra-light, Light, and Regular cigarettes, reasons for smoking Ultra-light/Light cigarettes, and the likelihood of both quitting smoking and switching to Regular cigarettes if they came to learn that one Ultra-light/Light cigarette gave the same amount of tar as one Regular cigarette.

DESIGN

Ten- to fifteen-minute random-digit-dialed, computer-assisted telephone interviews (CATI) were conducted with both a national probability sample (n = 788) and a state random sample (n = 266) of daily smokers over the age of 18.

RESULTS

Less than 10% of smokers in the national sample and only 14% of smokers in the state sample knew that one Light cigarette could give the same amount of tar as one Regular cigarette. Less than 10% of smokers in the state sample knew that one Ultra-light cigarette could give the same amount of tar as one Regular cigarette. Thirty-two percent of the Light and 26% of the Ultra-light smokers in the national sample, and 27% of Light and 25% of Ultra-light smokers in the state sample, said they would be likely to quit smoking if they learned one Light/Ultra-light equaled one Regular.

CONCLUSION

Many Light and Ultra-light smokers are smoking these cigarettes to reduce the risks of smoking and/or as a step toward quitting. However, these smokers are unaware that one Ultra-light/Light cigarette can give them the same amount of tar and nicotine as one Regular cigarette. Many of the Ultra-light/Light smokers sampled in this study stated that they would be likely to quit if they knew this information. Mistaken beliefs about low-yield brands are reducing intentions to quit smoking.

Weight gain after smoking cessation in women: the impact of dieting status

OBJECTIVE

The fear of weight gain appears to be a barrier to quitting in some smokers, particularly in women. However, not all female smokers have the same concerns about weight, and not all quitters are equally susceptible to gaining weight after cessation. We hypothesized that among females, dieters, compared to nondieters, would report more weight gain after smoking cessation and would tend to smoke more for weight control purpose.

METHOD

Undergraduate college students were surveyed to assess their smoking status, dieting status, postcessation weight gain, and their motivations to smoke.

RESULTS

Among former smokers, dieters reported considerably more weight gain than nondieters. Dieters were more likely to have started, and to have continued smoking in order to control their weight, and among current smokers, dieters reported having had shorter quit attempts.

DISCUSSION

The dieters/former smokers' comparatively high weight gain after smoking cessation is discussed in terms of possible changes in dietary intake, metabolic rate, and physical activity.

Effects of nicotine on proliferation and extracellular matrix production of human gingival fibroblasts in vitro

Normal function of gingival fibroblasts is essential for maintenance of the gingival extracellular matrix (ECM), but under inflammatory conditions in gingival tissue which may occur with tobacco use, they can also act in its destruction. The purpose of this study was to determine the effects of nicotine, a major component of tobacco, on gingival fibroblast proliferation, the production of fibronectin (FN), and the production and breakdown of type I collagen to elucidate its role in periodontal destruction associated with its use. A human gingival fibroblast strain derived from a healthy individual with non-inflamed gingiva was used in this study. Nicotine at concentrations > 0.075% caused cell death, and at 0.075% and 0.05% it caused transient vacuolization of the fibroblasts. At concentrations of 0.001% to 0.075%, nicotine significantly inhibited proliferation (P < or = 0.03), measured by the incorporation of [3H]-thymidine into DNA. The production of FN and type I collagen was significantly inhibited by nicotine at > or = 0.05% (P < or = 0.001), measured using specific ELISAs. On the other hand, nicotine at > or = 0.025% significantly increased collagenase activity (P < or = 0.008), using [3H]-gly and [14C]-pro-labeled type I collagen gels as substrate. The results show that, in vitro, nicotine inhibits the growth of gingival fibroblasts and their production of FN and collagen, while also promoting collagen breakdown. This suggests that nicotine itself may augment the destruction of the gingival ECM occurring during periodontal inflammation associated with smokeless tobacco use.

The Fagerström Test for Nicotine Dependence: a revision of the Fagerström Tolerance Questionnaire

We examine and refine the Fagerström Tolerance Questionnaire (FTQ: Fagerström, 1978). The relation between each FTQ item and biochemical measures of heaviness of smoking was examined in 254 smokers. We found that the nicotine rating item and the inhalation item were unrelated to any of our biochemical measures and these two items were primary contributors to psychometric deficiencies in the FTQ. We also found that a revised scoring of time to the first cigarette of the day (TTF) and number of cigarettes smoked per day (CPD) improved the scale. We present a revision of the FTQ: the Fagerström Test for Nicotine Dependence (FTND).

The presence of nicotine on root surfaces of periodontally diseased teeth in smokers

There is a growing body of scientific evidence to support the concept that the use of tobacco products significantly contributes to the progression of periodontal disease or is detrimental to healing following periodontal therapy. Several studies have shown toxic effects of nicotine on peripheral circulation and the immune response. The purpose of the present study was to identify and compare the quantity of nicotine present on root planed and nonroot planed surfaces of teeth from smokers. Twenty-nine single-rooted teeth from 11 smokers were extracted, brushed clean, and the roots sectioned longitudinally. The respective halves were either left untreated (Group A) or thoroughly root planed (Group B). Pulpal tissue was removed and the individual root sections weighed. Each half was extracted for nicotine using a methylene chloride technique. Quantification was performed using high pressure liquid chromatography (HPLC) and the sections compared on a nicotine per root weight basis. Results showed a greater amount of nicotine present on non-root planed sections than on treated sections, although some treated specimens revealed small amounts of the substance. These findings suggest that nicotine is present on the root surface but is largely removed by thorough root planing. Its presence is not surprising in light of the recent finding that nicotine and cotinine, the major metabolite of nicotine, are found in gingival crevicular fluid. Recent studies have shown a particularly harmful effect of nicotine on fibroblasts. Its presence on root surfaces may, therefore, impair wound healing and alter the host response in periodontal disease. The use of tobacco products in conjunction with periodontal therapy may interfere with optimal healing and/or lead to further periodontal breakdown.

Cotinine in saliva and gingival crevicular fluid of smokers with periodontal disease

A study was undertaken to determine the presence of cotinine, a metabolite of nicotine, in the saliva and gingival crevicular fluid of smokers with periodontal disease. Saliva and crevicular fluid samples were obtained from 16 habitual cigarette smokers and analyzed by High Performance Liquid Chromatography (HPLC) for the presence of cotinine. Thirteen non-smokers with periodontal disease served as controls. There was no evidence of cotinine (within our detection levels) in either the saliva or crevicular fluid of any of the nonsmokers. Cotinine, in a wide range of concentrations, was detected in the saliva and crevicular fluid in all of the 16 cigarette smokers. The presence of a nicotine metabolite in the saliva and gingival crevicular fluid reflects the extent of the systemic distribution of nicotine in smokers. The vasoactive properties of nicotine are well known and may possibly affect the pathogenesis of periodontal disease.

Evidence for limits on the acceptability of lowest-tar cigarettes

The sales of the lowest yield cigarettes (1-3 mg tar) seem to have been particularly resistant to the effects of promotion and advertising, while the sales of other low-yield cigarettes (4-9 mg tar) seem to have been increased by promotional efforts. This finding is consistent with the existence of a boundary of tar and nicotine acceptability below which consumers in general are not prepared to go. Use of lower tar cigarettes may be helpful for those who cannot stop smoking, but, since 1979, the percentage of cigarettes under 16 mg tar has changed little.

The effect of nicotine on the attachment of human fibroblasts to glass and human root surfaces in vitro

This study examined the effect of nicotine on fibroblast attachment to glass and nondiseased human root surfaces. Human foreskin fibroblasts (HFF) were trypsinized, suspended in RPMI 1640 medium, and incubated with autoclaved human root sections and nicotine concentrations of zero (control), 25, 50, 100, 200, or 400 ng/ml. The root sections were examined for fibroblast attachment at 24, 48, and 72 hours by light microscopy and scanning electron microscopy (SEM). Additional trypsinized HFF were incubated on glass surfaces with the same concentrations of nicotine and examined at one week by light microscopy. HFF attached and grew on glass and root surfaces at all concentrations of nicotine. Controls on glass surfaces exhibited a normal monolayer of long spindle-shaped fibroblasts with a parallel alignment and minimal overlapping. Nicotine-treated HFF exhibited a haphazard arrangement with cell overlapping and vacuolization of the cytoplasm. Under SEM, the controls had smooth surfaces and appeared firmly attached to the root surface via (1) microvilli and filopodia on the cell boundaries and (2) short, branched, thin-to-medium width cytoplasmic processes with microvilli and filopodia on their boundaries. Few microvilli were noted on the control cell surfaces. HFF exposed to nicotine had microvilli and filopodia on the cell surfaces and long thin and long broad cytoplasmic processes with many microvilli and filopodia that projected away from the root surface. These findings suggest that the nature of fibroblast attachment to glass and root surfaces is altered by nicotine. A similar disturbance in fibroblast attachment may occur in humans who use nicotine-containing products, making them more susceptible to destruction of the periodontium and less responsive to new attachment after periodontal therapy.

Effects of cigarette nicotine content on smoking behavior of baboons

Human cigarette smokers modify the way in which they smoke cigarettes of differing nicotine content, apparently to maintain nicotine exposure at a preferred level. The effects of changing from moderate to high or low nicotine content cigarettes were examined in 11 baboons (superspecies Papio cynocephalus) trained to smoke cigarettes for water rewards. Relative to the moderate nicotine content cigarette, the animals took significantly (p less than .05) more puffs on the high nicotine content cigarette, and the puffs on the high nicotine cigarette were significantly larger in volume. The animals made the same number of puffs, relative to the moderate nicotine content cigarette, on the low nicotine content cigarette, but the volume of the puffs was significantly smaller. The cotinine output in urine varied significantly and was directly related to cigarette nicotine content; cotinine is the primary metabolite of nicotine. Baboons, like people, prefer high nicotine content cigarettes. Nonhuman primates also regulate nicotine exposure by modification of their puffing behavior. These results indicate that the nonhuman primate also can be used as a model for the investigation of the behavioral aspects of cigarette smoking.

A comparison of the yields of tar, nicotine, and carbon monoxide of 36 brands of Canadian cigarettes tested under three conditions

A number of countries, including Canada, sponsor routine monitoring of cigarette tar, nicotine, and carbon monoxide yields which are evaluated by cigarette-smoking machines according to a standard protocol. These standardized yields continue to decline as tobacco companies modify their brands to meet consumers' demand for "light" products. This trend toward cigarettes with low average deliveries of toxic substances may reduce health risks for some people. However, switching to low-yield cigarettes may not result in reduced risks for smokers who smoke these cigarettes intensively. Thirty-six brands of Canadian cigarettes, including 28 with ventilated filters, were tested under standard conditions and 2 others in order to determine how yields of tar, nicotine, and carbon monoxide change when cigarettes are manipulated by smokers in order to increase their smoke intake. While the rank order yields of tar, nicotine, and carbon monoxide was preserved, the average yields of all three substances more than doubled when cigarettes were intensively smoked in comparison with standard smoking.