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Graham Smith

Publications and source records attributed to Graham Smith.

34 records · Page 2Linked to original sources
PubMed2004

The effect of tobacco ingredients on smoke chemistry. Part II: casing ingredients.

This is the second part of a study in which the effects of adding a range of ingredients to tobacco on the chemistry of cigarette mainstream smoke are assessed. The examination of smoke chemistry has concentrated on those constituents in smoke that regulatory authorities in the USA and Canada believe to be relevant to smoking-related diseases. In this part of the study the effects of 29 casing ingredients and three humectants have been assessed at the maximum levels typically used on cigarettes by British American Tobacco. This brings the total number of ingredients assessed in Parts I and II of this study to 482. The casing ingredients were added at levels of up to 68 mg on the cigarettes. Their effects on smoke constituents were generally larger than the effects of flavouring ingredients, which were added at parts per million levels. Many of the casing ingredient mixtures either had no statistically significant effect on the level of the analytes investigated in smoke relative to a control cigarette, or they produced decreases of up to 44% in some cases. Those analytes that were increased in smoke are highlighted in this paper. The largest increases were for formaldehyde levels, up to 26 microg (73%) in one case, observed from casing mixtures containing sugar. This is most likely due to the generation of formaldehyde by pyrolysis of sugars. Occasional small increases were also observed for other analytes. However, the statistical significance of many of these increases was not present when the long-term variability of the analytical method was taken into account. The significance and possible reasons for the increases are discussed.

Canada↗
PubMed2004

An overview of the effects of tobacco ingredients on smoke chemistry and toxicity.

This paper presents an overview of a series of studies designed to assess the influence of 482 tobacco ingredients on cigarette smoke chemistry and toxicity. The studies are: pyrolysis of the ingredients; influence of the ingredients on smoke constituents believed by regulatory authorities to be relevant to smoking-related diseases ("Hoffmann analytes"); influence of the ingredients on in vitro genotoxicity and cytotoxicity of smoke partiulate matter; and influence of the ingredients on the inhalation toxicity of smoke. The present paper brings the salient features of these studies together. A pyrolysis technique has been developed which, as far as practicably possible, mimics the combustion conditions inside a burning cigarette. The results from 291 single-substance ingredients indicate that almost a third would transfer out of the cigarette burning zone at least 99% intact (i.e. less than 1% pyrolysis), and almost two thirds would transfer at least 95% intact. Of the ingredients that underwent some degree of pyrolysis, a few "Hoffmann analytes" were detected amongst the pyrolysis products of 19 ingredients. Taking into account maximum use levels, their maximum pyrolysis levels were generally small and often insignificant compared to the levels typically present in smoke. Possible exceptions were acetaldehyde and benzene from the pyrolysis of malic acid. However, subsequent smoke chemistry studies indicated that the maximum levels predicted from pyrolysis of this involatile substance were overestimated, suggesting that malic acid does not undergo complete pyrolysis in the burning cigarette and/or generates acetaldehyde and benzene at similar rates to that of tobacco on a per weight basis. When added to tobacco, many of the ingredient mixtures produced no significant effect on the levels of many of the "Hoffmann analytes" in smoke, while some produced increases or decreases relative to the relevant control cigarettes. The study has concentrated on the increases. Many of the differences were found to be not significant when the long-term variability of the analytical methodology was taken into account. However, even taking this into account, the smoke formaldehyde levels in two of the test cigarettes were significantly increased relative to their controls, by up to 26 microg (73%). These increases are likely to be due to the pyrolysis of sugars, cellulose and other polysaccharide materials. The activity of smoke particulate matter from cigarettes containing tobacco ingredients has been determined with three in vitro bioassays, two for genotoxicity and one for cytotoxicity. These were the Ames test, the mammalian cell micronucleus assay, and the neutral red uptake cytotoxicity assay. Within the sensitivity and specificity of these bioassays, the specific activity of the cigarette smoke particulate matter was not changed by the addition of ingredients to the cigarette. Three 90-day sub-chronic inhalation studies have been undertaken and histopathological and histomorphometric assessments made within the respiratory tracts of animals exposed to smoke from cigarettes containing the various ingredient mixtures and their control cigarettes. The response due to tobacco smoke exposure was not distinguishable between the test and control cigarettes, indicating that the presence of the ingredients had made no discernable differences to the type and severity of the treatment-related changes.

Administration, Inhalation↗
PubMed2004

The effect of tobacco ingredients on smoke chemistry. Part I: Flavourings and additives.

The effects of 450 tobacco ingredients added to tobacco on the forty-four "Hoffmann analytes" in mainstream cigarette smoke have been determined. These analytes are believed by regulatory authorities in the USA and Canada to be relevant to smoking-related diseases. They are based on lists published by D. Hoffmann and co-workers of the American Health Foundation in New York. The ingredients comprised 431 flavours, 1 flavour/solvent, 1 solvent, 7 preservatives, 5 binders, 2 humectants, 2 process aids and 1 filler. The cigarettes containing mixtures of the ingredients were smoked using the standard ISO smoking machine conditions. The levels of the "Hoffmann analytes" in the smoke from the test cigarettes containing the ingredient mixture were compared to those from control cigarettes without the ingredients. In practice, flavouring ingredients are typically added to tobacco that also contains casing ingredients and reconstituted tobacco materials. In order to keep the tobacco mixtures as authentic as possible, three comparisons have been made in this study. These are: (a) control cigarette containing a typical US blended, cased tobacco incorporating reconstituted tobacco versus test cigarettes that had flavouring ingredients added to this tobacco; (b) control cigarette containing tobacco only versus test cigarettes with the tobacco cased and incorporating flavourings; (c) control cigarette containing tobacco only versus test cigarette incorporating additives made in an experimental sheet material. The significances of differences between the test and control cigarettes were determined using both the variability of the data on the specific occasion of the measurement, and also taking into account the long-term variability of the analytical measurements over the one-year period in which analyses were determined in the present study. This long-term variability was determined by measuring the levels of the 44 "Hoffmann analytes" in a reference cigarette on many occasions over the one-year period of this study. The ingredients were added to the experimental cigarettes at or above the maximum levels used commercially by British American Tobacco. The effect of the ingredient mixtures on total particulate matter and carbon monoxide levels in smoke was not significantly different to the control in most cases, and was never more than 10% with any ingredient mixture. It was found that, in most cases, the mixtures of flavouring ingredients (generally added in parts per million levels) had no statistically significant effect on the analyte smoke yields relative to the control cigarette. Occasionally with some of the mixtures, both increases and decreases were observed for some smoke analyte levels relative to the control cigarette. These differences were generally up to about 15% with the mixtures containing flavouring ingredients. The significance of many of the differences was not present when the long-term variability of the analytical methodology was taken into account. For the test cigarettes with ingredient mixtures containing casing ingredients, there were again no significant changes in smoke analyte levels in most cases. Those changes that were observed are as follows. Decreases in smoke levels were observed with some ingredient mixtures for most of the tobacco specific nitrosamines (up to 24%), NO(x), most of the phenols (up to 34%), benzo[a]pyrene, and some of the aromatic amines and miscellaneous organic compounds on the "Hoffmann list". Increases were observed for some test cigarettes in smoke ammonia, HCN, formaldehyde and lead levels (up to 24%). The significance of the ammonia and lead increases was not present when the long-term variability of the analytical methodology was taken into account. The yields of some carbonyl compounds in smoke were increased in one comparison with an additives mixture containing cellulosic components; in particular, formaldehyde was increased by 68%. This was the largest single change seen in any smoke analyte level in this study. These carbonyls are produced from the pyrolysis of cellulosnyls are produced from the pyrolysis of cellulosic and other polysaccharide materials, present in the additives mixture. With this test cigarette, all tobacco specific nitrosamines, phenols, semi-volatile bases, NO(x) and some aromatic amines and miscellaneous organic compounds on the "Hoffmann list" were decreased, by up to 22%. The significance of many of these differences remained even when the long-term variability of the analytical methodology was taken into account. The levels of all other "Hoffmann analytes" in the smoke were not significantly different to those of the control cigarette. With the exception of the determinations of "tar", nicotine and carbon monoxide, there are currently no internationally recognised standard methods for measurement of the other "Hoffmann analytes". Each laboratory uses its own methods and there are large laboratory-to-laboratory variations, as well as variations over time in a given laboratory. Therefore, it is important that in any comparison of smoke analytes amongst different cigarettes, all the analytes should be measured in the same laboratory and at the same time. This was the case in the present study and all the methods have been validated internally.

Ammonia↗
PubMed2002

Effects of chronic nociceptin/orphanin FQ exposure on cAMP accumulation and receptor density in Chinese hamster ovary cells expressing human nociceptin/orphanin FQ receptors.

Nociceptin/orphanin FQ (N/OFQ) is the endogenous ligand for the G(i)-coupled N/OFQ receptor (NOP). We have examined the effects of chronic exposure of Chinese hamster ovary cells expressing the recombinant human NOP receptor (CHO(hNOP)) to 1 nM N/OFQ for up to 48 h in the absence and presence of the NOP selective antagonist [Nphe(1)]N/OFQ (1-13)NH(2) ([Nphe(1)]). Then, either a concentration-response curve for N/OFQ inhibition of cAMP formation was constructed or the cells were homogenized and membrane receptor density was determined using [(125)I]Y(14)N/OFQ. There was a time-dependent reduction in pEC(50) (without a change in maximum) for N/OFQ with significant differences observed following >24 h of exposure (control pEC(50) approximately 9.5; 48 h pretreatment approximately 8.7). In cells co-exposed to N/OFQ+[Nphe(1)] for 48 h, there was no reduction in pEC(50). There was a compensatory (approximately 2.5-fold), [Nphe(1)]-sensitive increase in cAMP mass in cells exposed to N/OFQ for 24-48 h. N/OFQ pretreatment also resulted in a time-dependent [Nphe(1)]-sensitive loss of cell surface receptors. At 48 h, B(max) was reduced from approximately 2.0 to approximately 1.3 pmol mg(-1) protein without a change in pK(d) for N/OFQ. There was a positive correlation between pEC(50) for cAMP inhibition and B(max). The lack of effect on maximum cAMP response probably results from receptor overexpression and the creation of a receptor reserve.

Animals↗
PubMed2002

Induction of anesthesia and insertion of a laryngeal mask airway in the prone position for minor surgery.

UNLABELLED: The use of the prone position for surgery presents potential obstacles to rapid tracking of patients during ambulatory anesthesia. We describe a prospective audit of 73 patients who placed themselves in the prone position; anesthesia was induced in this position and a laryngeal mask airway (LMA) was used to maintain the airway. Additional increments of propofol were given to one patient who had laryngospasm and to nine who required deepening of anesthesia before the LMA could be inserted. Of four cases with LMA malpositioning, the LMA was adjusted easily in three, but in one patient who was edentulous, it was necessary to hold the LMA for the duration of the procedure. Manual ventilation of the lungs via the LMA was required because of arterial oxygen desaturation and hypoventilation in four patients. Blood was noted outside the nostrils in two patients, presumably caused by soft tissue trauma after insertion of the LMA, and bradycardia occurred in five patients. In the postoperative period, hoarseness and sore throat were observed in one and six patients, respectively. With experience and appropriate patient selection, it is possible to induce and maintain anesthesia using a LMA in patients in the prone position for ambulatory surgery. IMPLICATIONS: With experience and appropriate patient selection, it is possible to induce and maintain anesthesia using a laryngeal mask airway in patients in the prone position for ambulatory surgery.

Anesthesia↗