Cigarette smoking pharmacokinetics and its relationship to smoking behaviour.

The yield of a cigarette is determined by the tobacco blend, the length of the cigarette, the cigarette paper, the filter and air dilution. Cigarette yield has been defined by tradition and by law to be the yield of nicotine, tar and carbon monoxide obtained from a 35 ml puff volume of 2-second duration taken every minute during the burning time of the cigarette. Normally smokers draw a puff into their mouth and then inhale. Mouth delivery is largely determined by personal smoking behaviour. The puff volume, number of puffs taken per cigarette, and number of cigarettes smoked per day determine both the volume and the mass of daily mouth delivery. There are marked differences in smoking behaviour, and the delivery is substantially altered from the yield values obtained with the standardised test procedure. Body uptake of smoke ingredients is determined by smoke chemical parameters, smoker inhalation behaviour, lung morphology, and physiological parameters. The physiological parameters include tidal volume, vital capacity, rate of breathing, and rate of clearance for the lung. Given these behavioural and physiological differences in individual delivery and uptake it is not surprising that differences in measured parameters occur within smokers of cigarettes with a particular yield. Biological differences among individuals, such as metabolic and size differences, cause additional variations in these values. Therefore, the estimates of nicotine and tar delivery can vary widely in studies of individual uptake when the estimates are based upon sample population data. The variables in both smoking behaviour and in chemical and physiological factors which alter uptake make it essential to have a crossover design for any study. The large standard error for the plasma concentration of cotinine (a major metabolite of nicotine) within a sample population, and the log linear nature of the plasma cotinine concentration curve, requires a very large sample size for any study of cigarette delivery or uptake. When comparisons of brands are made, average values are misleading in that the skew to the high values obscures frequency differences among the lower values within the samples. It is important to remember that smoker compliance with study design is very essential.(ABSTRACT TRUNCATED AT 400 WORDS)

A clinical comparison of the effect on the gingiva of the Prophy-Jet and the rubber cup and paste techniques.

This clinical trial compared the effect on the gingiva of the Prophy-Jet and the rubber cup and paste techniques of stain and supragingival plaque removal. Twenty-one human subjects with healthy gingiva or slight gingivitis participated. A split mouth design was used. The Prophy-Jet caused a statistically significant increase (P less than 0.05) in gingival irritation immediately posttreatment, but the differences were not deemed clinically significant. There were no statistically significant (P less than 0.05) or clinically significant differences in the effect on the gingiva between the two techniques at 7 and 21 days posttreatment. There was no lasting difference in gingival trauma between the two methods of stain and supragingival plaque removal in subjects with healthy gingiva or slight gingivitis.

Biocompatibility test procedures for materials evaluation in vitro. II. Objective methods of toxicity assessment.

Methods of assessing the biocompatibility of materials for use in medical devices were evaluated. Ten materials were tested using quantitative, objectively graded in vitro biochemical and functional assays employing four cell lines (CCL 1, 74, 76, and 131) used in previous work and five primary cell types (human lymphocytes, polymorphonuclear leukocytes, and mixed leukocytes, mouse macrophages, and mouse embryo). The biochemical methods (DNA synthesis, protein synthesis, and ATP activity) demonstrated good agreement in toxicity ranking of the materials, regardless of which cell culture was used and, also, the cell cultures responded similarly for each method. Methods that measured functional characteristics of cells (adhesion and phagocytosis) were highly sensitive but had low toxicity ranking agreement and reproducibility. Assays (defined as method and cell culture combinations) using cell lines were more reproducible than assays using primary cell types. Significant differences in sensitivity were noted among the assay systems for particular material types. The in vitro assays were more sensitive to differences in material composition than was a 90-day assay by subcutaneous implantation in rats.