Puffing Pattern Research Articles

Menthol versus tobacco e-liquid flavor: Impact on acute subjective effects, puff patterns, and intentions for use among Black and White menthol smokers

BackgroundThe proposed FDA product standard to prohibit menthol as a characterizing flavor in combustible cigarettes has the potential to significantly reduce tobacco-related health disparities. Whether a menthol e-liquid product standard would improve or hinder public health is unknown. No known research has directly examined the impact of menthol vs. tobacco flavored e-liquid use on acute e-cigarette use patterns, subjective experience, behavioral intentions, and craving and withdrawal among menthol cigarette smokers. MethodsBlack (n = 47) and White (n = 4) nicotine-deprived menthol smokers with limited e-cigarette experience completed two counterbalanced in-laboratory 30-minute ad libitum vaping sessions with menthol and tobacco nicotine salt-based e-liquid in a randomized crossover pilot trial design. Questionnaires assessed reductions in craving and withdrawal and post-session subjective experience and behavioral intentions. Puff topography was measured continuously throughout each vaping session. ResultsMeasures of puff topography did not differ significantly by e-liquid flavor (all p > .40). Similarly, menthol and tobacco flavored e-cigarettes were both rated positively in terms of subjective effects and behavioral intentions (all p > .10) and about 40 % of participants reported a preference for the tobacco-flavored e-liquid. Finally, participants showed comparable reductions in craving (p = .210) and withdrawal (p = .671) from pre- and post-session regardless of e-liquid flavor. ConclusionsAmong menthol smokers in a lab-based setting, findings suggest that menthol vs tobacco e-liquid flavor has little impact on acute changes in puff patterns, subjective experience, behavioral intentions, or craving and withdrawal.

CFPD-PK simulation of inhaled Delta-9-tetrahydrocannabinol aerosol dynamics: Transport, deposition, and translocation in a mouth-to-G10 subject-specific human airway

Medical cannabis is increasingly used as an alternative therapy for various conditions, including chronic pain, multiple sclerosis, epilepsy, and cancer-related symptoms. However, it is crucial to ensure that patients receive the intended dose of tetrahydrocannabinol (THC) from inhaled cannabis for optimal therapeutic effect without overdose risk. This requires a comprehensive understanding of the factors that influence the pharmacokinetics (PKs) of THC in the respiratory system. However, accurate estimation of lung dosimetry and blood concentration of inhaled THC remains challenging partially because the influence of diversified patient-specific puff patterns on inhaled THC transport, deposition, and translocation is still not well quantified. To address the knowledge gap mentioned above, this study employed a hybrid computational fluid-particle dynamics (CFPD) and PK model to evaluate factors that influence delivered doses of THC to the human respiratory system and the resultant THC-plasma concentration-time profile. Specifically, this study compared multiple puff waveforms for inhalation-holding-exhalation (IHE) with total puff volumes from 55 to 82 ml for 2 or 3 s, hold durations from 0 to 5 s, and three puff waveforms (i.e., square, sinusoidal, and realistic). THC deposition in the airways was recorded during all phases for each case using either 452,849 particles per second for the 1.128-μm monodisperse cases or 399,866 particles per second for the polydisperse cases, with the mass median aerodynamic diameter (MMAD) of 1.128 μm. Pulmonary air-THC particle flow transport dynamics, THC particle deposition data, and THC vapor absorption were predicted using CFPD for four airway regions, then scaled by region-specific bioavailability factors. The deposited THC mass in airway regions represents the initial mass entering a 3-compartment PK model, to predict the THC-plasma concentration-time profiles. The CFPD-PK results revealed significant variability in THC transport, deposition, and plasma concentration based on IHE factors. Specifically, larger puff volumes and longer holding times enhanced THC deposition in deeper airways and increased THC-plasma concentrations. Realistic transient puff waveforms predicted higher particle deposition and THC-plasma concentrations than simplified square waveforms. Polydisperse particle distributions show more realistic deposition patterns than monodisperse particle simulations. This study provides insights into the complexity of THC inhalation therapy, emphasizing the importance of considering individualized puff patterns and realistic particle size distributions in accurately predicting therapeutic outcomes, which is highly related to THC deposition in the lung and THC plasma concentration. These findings and the CFPD-PK modeling framework offer guidance for clinicians in prescribing personalized THC dosages, support regulatory science in evaluating inhalation devices, and contribute to ongoing research aimed at optimizing THC delivery for maximum therapeutic effectiveness while minimizing potential overdose risks.

Unraveling the regulating mechanisms of moisture content in the puffing of sweet potato starch gel

Starch-based puffed crisps are a major group of popular snacks. In this work, the effects and underlying mechanisms of moisture content (MC) on the puffing of sweet potato starch gels were explored. The results showed that the gel with 12 % MC generated the highest puffing ratio (8.96), then followed by gels with 16 % MC (8.45) and 8 % MC (8.28). All starch gels presented a two-stage puffing pattern, but their evolutions with the heating temperature were highly dependent on the MC of gels. The relative puffing area percentages of gels with 8 % MC, 12 % MC and 16 % MC in the first (second) stages were 57.64 % (42.36 %), 60.66 % (39.34 %), and 18.36 % (81.64 %), respectively. The final pores in puffed products originated from the small water clusters that were regionalized in gel cells. The air cells started to expand as the gels with 8 % MC, 12 % MC and 16 % MC respectively reached the glass transition temperatures of 158.45 °C, 142.15 °C and 111.03 °C. The puffing was a joint consequence of the extensibility of cell walls and the pressure of water vapor in cells and the MC of the gels could regulate both of them. This study would facilitate the production of starch snacks with higher quality.

Examination of Viscosity Effect on Cavitating Flow inside Poppet Valves Based on a Numerical Study

The higher susceptibility to cavitation in poppet valves due to the lower viscosity of water than the traditionally used mineral oil poses a challenge in fluid transmission technology. To reveal the underlying mechanism of cavitating flow physics associated with the variation in viscosity effect, the current paper examines both the water and oil cavitating flow dynamics inside poppet valves with varied structures through a numerical study. The simulation results are validated with a comparison to previous experimental data in terms of cavitation morphology and pressure distribution. According to the predicted cavitation distribution, three kinds of cavitation occurred at separated positions in both water- and oil-flow cases. The vortex cavitation, which in the oil-flow case displays a remarkable paired structure with favorable coherence, is featured with a scattered dispersion in the water-flow case, while the profound attached cavitation at the poppet trailing edge in the water-flow case almost disappears in the oil-flow case. Furthermore, the attached cavitation within the chamfered groove has higher stability in the oil-flow case, compared to the thorough detachment behavior featured with profound 3-dimensionality in the water-flow case. According to the potential core and vortex evolution, the strong 3-dimensionality due to the violent laminar-turbulent transition in the water-flow case together with the produced puff pattern of the potential core, to a large extent, interrupts the periodic behavior of cavitation, which is essentially preserved in the oil-flow case featured with favorable coherence.

Exposure to Potentially Harmful E-Cigarette Emissions via Vape Tricks: Protocol for a Mixed-Methods Study.

BackgroundThe number of adolescents and adults using e-cigarettes, referred to as vaping, has dramatically increased. E-cigarettes can be used to perform vape tricks by inhaling and exhaling the e-cigarette aerosol in patterns to create visual effects or large clouds. To create these effects, the puffing patterns associated with vape tricks may be different than standard ad-lib e-cigarette usage. The prevalence of vape tricks and the harm associated with exposure to e-cigarette emissions when performing vape tricks is currently unknown.ObjectiveOur objectives are to characterize duration, heart rate, respiratory rate, tidal volume, minute volume, and physical activity metrics associated with the performance of vape tricks and to characterize the emission of e-cigarettes when performing vape tricks in a manner suitable to inform novel exposure modeling.MethodsThe study will recruit e-cigarette users with a history of performing vape tricks. Data collection will occur in two different sessions. In the first session, participants will be asked to puff on their e-cigarette as they normally would for 20 minutes. The second session will be a vape tricks session, where users will be asked to perform a series of up to five different vape tricks with their e-cigarette. Data will be collected through screener surveys, in-person interviews, video recordings, a personal exposure monitor, and a biometric garment.ResultsData analysis is pending and scheduled to take place in the fall of 2019.ConclusionsThis study will be used to assess the feasibility of using a biometric garment to complement environmental and observational data. The approach may provide greater insight into the health risks of performing vape tricks compared to typical e-cigarette use.International Registered Report Identifier (IRRID)DERR1-10.2196/12304

JUUL electronic cigarette use patterns, other tobacco product use, and reasons for use among ever users: Results from a convenience sample

IntroductionJUUL, an e-cigarette from PAX Labs, has captured 70% of the e-cigarette market. The current study examines JUUL use patterns and reasons for initiation in a large convenience sample of U.S. adults. MethodsRespondents were 979 U.S. adults registered on Amazon Mechanical Turk (MTurk) who reported ever using JUUL. Items included frequency/quantity of JUUL use, reasons for trying JUUL, flavor preferences, and use of other tobacco products. ResultsThe majority of participants reported only trying JUUL once or twice (59.5%), 29.2% reported regular nondaily use and 10.3% reported daily use. The average quantity of JUUL pod use was low in the overall sample (4 pods per month). Daily users reported using ~10 pods per month and engaging in 4–9 separate vaping sessions per day. The most frequently reported reasons for JUUL use were because friends were using it (26.5%), curiosity (20.5%), and similarity to a cigarette (7.7%). Approximately 26% of current JUUL users reported current exclusive JUUL use, while 56% reported using JUUL and another e-cigarette. Of the entire sample, 37.1% were former smokers. Of those, 14.9% were daily JUUL users, 21.4% were nondaily JUUL users, and 63.8% were JUUL triers. ConclusionsThis is the first study to examine patterns and reasons for use of the most popular e-cigarette on the market. In this convenience sample, nearly 40% of those who ever tried JUUL reported current daily or daily use. JUUL use may be associated with limited puffing patterns compared to earlier generation e-cigarettes. Research is needed to investigate if JUUL puffing patterns result in decreased exposure to potentially harmful non-nicotine e-liquid constituents compared to other e-cigarettes.

Assessing electronic cigarette emissions: linking physico-chemical properties to product brand, e-liquid flavoring additives, operational voltage and user puffing patterns

Users of electronic cigarettes (e-cigs) are exposed to particles and other gaseous pollutants. However, major knowledge gaps on the physico-chemical properties of such exposures and contradictory data in published literature prohibit health risk assessment. Here, the effects of product brand, type, e-liquid flavoring additives, operational voltage, and user puffing patterns on emissions were systematically assessed using a recently developed, versatile, e-cig exposure generation platform and state-of-the-art analytical methods. Parameters of interest in this systematic evaluation included two brands (A and B), three flavors (tobacco, menthol, and fruit), three types of e-cigs (disposable, pre-filled, and refillable tanks), two puffing protocols (4 and 2 s/puff), and four operational voltages (2.2–5.7 V). Particles were generated at a high number concentration (106–107 particles/cm3). The particle size distribution was bi-modal (∼200 nm and 1 µm). Furthermore, organic species (humectants propylene glycol and glycerin, nicotine) that were present in e-liquid and trace metals (potassium and sodium) that were present on e-cig heating coil were also released into the emission. In addition, combustion-related byproducts, such as benzene and toluene, were also detected in the range of 100–38,000 ppbv/puff. Parametric analyzes performed in this study show the importance of e-cig brand, type, flavor additives, user puffing pattern (duration and frequency), and voltage on physico-chemical properties of emissions. This observed influence is indicative of the complexity associated with the toxicological screening of emissions from e-cigs and needs to be taken into consideration.

The critical point of the transition to turbulence in pipe flow

In pipes, turbulence sets in despite the linear stability of the laminar Hagen–Poiseuille flow. The Reynolds number ($Re$) for which turbulence first appears in a given experiment – the ‘natural transition point’ – depends on imperfections of the set-up, or, more precisely, on the magnitude of finite amplitude perturbations. At onset, turbulence typically only occupies a certain fraction of the flow, and this fraction equally is found to differ from experiment to experiment. Despite these findings, Reynolds proposed that after sufficiently long times, flows may settle to steady conditions: below a critical velocity, flows should (regardless of initial conditions) always return to laminar, while above this velocity, eddying motion should persist. As will be shown, even in pipes several thousand diameters long, the spatio-temporal intermittent flow patterns observed at the end of the pipe strongly depend on the initial conditions, and there is no indication that different flow patterns would eventually settle to a (statistical) steady state. Exploiting the fact that turbulent puffs do not age (i.e. they are memoryless), we continuously recreate the puff sequence exiting the pipe at the pipe entrance, and in doing so introduce periodic boundary conditions for the puff pattern. This procedure allows us to study the evolution of the flow patterns for arbitrary long times, and we find that after times in excess of $10^{7}$ advective time units, indeed a statistical steady state is reached. Although the resulting flows remain spatio-temporally intermittent, puff splitting and decay rates eventually reach a balance, so that the turbulent fraction fluctuates around a well-defined level which only depends on $Re$. In accordance with Reynolds’ proposition, we find that at lower $Re$ (here 2020), flows eventually always resume to laminar, while for higher $Re$ (${\geqslant}2060$), turbulence persists. The critical point for pipe flow hence falls in the interval of $2020<Re<2060$, which is in very good agreement with the recently proposed value of $Re_{c}=2040$. The latter estimate was based on single-puff statistics and entirely neglected puff interactions. Unlike in typical contact processes where such interactions strongly affect the percolation threshold, in pipe flow, the critical point is only marginally influenced. Interactions, on the other hand, are responsible for the approach to the statistical steady state. As shown, they strongly affect the resulting flow patterns, where they cause ‘puff clustering’, and these regions of large puff densities are observed to travel across the puff pattern in a wave-like fashion.

Changes in Puffing Topography and Nicotine Consumption Depending on the Power Setting of Electronic Cigarettes.

The study purpose was to evaluate changes in puffing topography of experienced electronic cigarette users (vapers) when changing power settings in electronic cigarette battery devices. Experienced adult vapers (n = 21) were recruited. Participants used their own liquids and an atomizer and battery provided by the researchers. Two 30-minute sessions were performed, with the device power set at 6 W and 10 W, in a randomized, crossover, participant-blinded design. Puff number and duration (mean [SD]) were recorded in the provided electronic cigarette battery device, whereas the atomizers were weighted before and after use to determine liquid and nicotine consumption. Puff number and puff duration were lower at 10 W (46 [16] puffs and 3.8 [0.8] s) compared with 6 W (57 [20] puffs and 4.6 [1.0] s). Liquid and nicotine consumption was higher at 10 W (373 [176] mg and 4.2 [2.4] mg, respectively) compared with 6 W (308 [165] mg and 3.5 [2.3] mg, respectively). Vapers reported more aerosol volume and ease of use at 10 W compared with 6 W. The study identified an attempt for compensatory puffing patterns and nicotine self-titration, with a change in puffing patterns (puff number and duration) observed when changing the power settings of an e-cigarette device. Compensatory smoking behavior and nicotine self-titration is a well-established phenomenon. In electronic cigarettes, changing nicotine concentration in the liquid has been shown to trigger a compensatory puffing pattern. Herein, power setting of the electronic cigarette device was found to be a parameter associated with changes in puffing behavior, whereas higher power was preferable for the participants. These findings could contribute to the understanding of patterns of electronic cigarette use and could explain the preference of dedicated vapers to higher power devices. Additionally, laboratory studies evaluating aerosol emissions should consider using different puffing patterns according to the power settings tested.

E-cigarette puffing patterns associated with high and low nicotine e-liquid strength: effects on toxicant and carcinogen exposure.

BackgroundContrary to intuition, use of lower strength nicotine e-liquids might not offer reduced health risk if compensatory puffing behaviour occurs. Compensatory puffing (e.g. more frequent, longer puffs) or user behaviour (increasing the wattage) can lead to higher temperatures at which glycerine and propylene glycol (solvents used in e-liquids) undergo decomposition to carbonyl compounds, including the carcinogens formaldehyde and acetaldehyde. This study aims to document puffing patterns and user behaviour associated with using high and low strength nicotine e-liquid and associated toxicant/carcinogen exposure in experienced e-cigarette users (known as vapers herein).Methods/designA counterbalanced repeated measures design. Participants: Non-tobacco smoking vapers; have used an e-cigarette for ≥3 months; currently using nicotine strength e-liquid ≥12mg/mL and a second or third generation device. Intervention: This study will measure puffing patterns in vapers whilst they use high and low strength nicotine e-liquid under fixed and user-defined settings, each for a week. The 4 counterbalanced conditions are: i) low strength (6mg/mL), fixed settings; ii) low strength user-defined settings; iii) high strength (18mg/mL) fixed settings; iv) high strength user-defined settings. Biomarkers of exposure to toxicants and carcinogens will be measured in urine. In the second phase of this study, toxicant yields will be measured in aerosol generated using a smoking machine operated to replicate the puffing behaviours of each participant. Primary outcomes: i) Puffing patterns (mean puff number, puff duration, inter-puff interval and mL of liquid consumed) and user behaviour (changes to device settings: voltage and air-flow) associated with using high and low strength nicotine e-liquid. ii) Toxicant/carcinogen exposure associated with the puffing patterns/device settings used by our participants. Secondary outcomes: i) Subjective effects. ii) comparisons with toxicant exposure from tobacco smoke (using documented evidence) and with recommended safety limits. Sample size: Twenty participants.DiscussionThe findings will have important implications for public health messaging regarding the relative risks and subjective effects associated with using high and low strength nicotine e-liquid, and for policy makers regarding regulations on nicotine concentrations in e-liquids.

Regulation and correlation of X chromosomal puff and glue protein synthesis in the larval salivary glands of Drosophila nasuta nasuta

We have attempted to identify the chromosomal region harboring genes encoding major glue fractions by correlating the glue protein synthesis with the puffing pattern of the X-chromosome of Drosophila nasuta nasuta during normal larval development and in the presence of exogenous 20-OH Ecdysone. The division 10 of the X-chromosome was characterized by the presence of a puff right from early third instar which attains its maximum size in the mid third instar stage and remains active till the onset of prepupal stage. The puff was found to regress when larvae/glands were exposed to exogenous 20-OH Ecdysone in vivo or in vitro, suggesting that it is an intermolt puff. Salivary glands treated with 20-OH Ecdysone revealed a significant reduction in the total protein content as well as X-linked glue fractions resolved by SDS–PAGE.

Respiratory metabolism of salivary glands during the late larval and prepupal development of Drosophila melanogaster

During the late larval period, the salivary glands (SG) of Drosophila show a cascade of cytological changes associated with exocytosis and the expectoration of the proteinaceous glue that is used to affix the pupariating larva to a substrate. After puparium formation (APF), SG undergo extensive cytoplasmic vacuolation due to endocytosis, vacuole consolidation and massive apocrine secretion. Here we investigated possible correlations between cytological changes, the puffing pattern in polytene chromosomes and respiratory metabolism of the SG. The carefully staged SG were explanted into small amounts (1 or 2μl) of tissue culture medium. The respiratory metabolism of single or up to 3 pairs of glands was evaluated by recording the rate of O2 consumption using a scanning microrespirographic technique sensitive to subnanoliter volumes of the respiratory O2 or CO2. The recordings were carried out at times between 8h before pupariation (BPF), until 16h APF, at which point the SG completely disintegrate. At the early wandering larval stage (8h BPF), the glands consume 2nl of O2/gland/min (=2500μl O2/g/h). This relatively high metabolic rate decreases down to 1.2–1.3nl of O2 during the endogenous peak in ecdysteroid concentration that culminates around pupariation. The metabolic decline coincides with the exocytosis of the proteinaceous glue. During and shortly after puparium formation, which is accompanied cytologically by intense vacuolation, O2 consumption in the SG temporarily increases to 1.6nl O2/gland/min. After this time, the metabolic rate of the SG decreases downward steadily until 16h APF, when the glands disintegrate and cease to consume oxygen. The SG we analyzed from Drosophila larvae were composed of 134 intrinsic cells, with the average volume of one lobe being 37nl. Therefore, a single SG cell of the wandering larva (with O2 consumption of 2nl/gland/min), consumes each about 16pl of O2/cell/min. A simultaneous analysis of the rate of protein and RNA synthesis in the SG shows a course similar to that found in respiratory metabolism.

Effects of microwaves on the puffing pattern of D. melanogaster

Abstract The influence of electromagnetic field exposure on puffing pattern of salivary gland polythene chromosomes, viability and fertility of Drosophila melanogaster of the wild type Canton-S line was studied. Experimental conditions: Electromagnetic field characteristics: frequency — 36.64 GHz, power density — 0.4 W/m2, exposure time −10 seconds. Electromagnetic field exposure was conducted on the egg stage. Results: in larvae developed from the exposed eggs 3 of 8 chromosomal puffs tested (71CE, 82EF, and 83E) had significantly smaller dimensions than these in control at the prepupal stage. Viability of Drosophila estimated by the number of adult flies hatched from exposed eggs decreased, while the number of dominant lethal mutations increased. Conclusion: the exposure to a low-level microwave irradiation suppressed puffing activity at ecdysone-inducible loci of Drosophila polythene chromosomes, increased frequency of dominant lethal mutations and decreased Drosophila viability but did not influence Drosophila fertility.

Biological models for studying and assessing tobacco use.

The purpose of this chapter on biological models for studying and assessing tobacco use is to provide an introduction to some of the common concepts and biomarkers in this arena to ultimately inform intervention research by nurse scientists. An overview of selected biomarkers of tobacco exposure in individuals includes exhaled carbon monoxide, cotinine (the proximate metabolite of nicotine), and measurement of an individual's puffing pattern termed smoking topography. Common tobacco contents discussed include tobacco specific nitrosamines (TSNA) and polycyclic aromatic hydrocarbons (PAH) some of which increase disease risk including cancer. Exemplars of additives to cigarettes by the tobacco industry will be described including menthol, one additive marketed by the industry. Genetics and tobacco addiction has emerged as a rapidly expanding field. Illustrative of this area are twin studies, nicotinic receptors, CYP2A6 polymorphisms, and genes that impact dopamine receptors. The cadre of nurse scientists conducting research in this much needed area is small. The opportunity for nurse scientists educated in biological inquiry in tobacco-related research is great. Nurse scientists actively involved in multidisciplinary translational teams to address nicotine addition are needed.

Response of puffing pattern to in vivo treatments with organomercurials in Drosophila melanogaster.

Survival rate and length of development time were used as indicators of toxicity of methoxyethylmercuric acetate, methoxyethylmercuric chloride and methylmercuric chloride in Drosophila melanogaster. The two methoxyethyl compounds exhibit toxic effects (prolongation of development time) only in the highest concentration tested (10.0 mg Hg/l), while methylmercury already has toxic effects (lethality and prolongation of development) in concentrations of ≥ 1.25 mg Hg/l. Similar concentrations were used to test the effects of mercuric compounds on genetic balance in 0-hour prepupae, as revealed by the puffing patterns of polytene salivary chromosomes. Four aspects of puffing pattern response were observed in 20% of the 300 inspected larvae: (1) regression of total gene activity, expressed in terms of decreases in puff sizes/chromosome, (2) inhibition of normal puff regression, characterized by puff activity in 2B, 74EF, 75B and 78D which, during normal development, should be regressed by this stage, (3) inhibition of normal puff activation, which is characterized by puffs 3A, 4F, 28A, 46F, 61C, 62C, 62F and 73B being inactive, though they normally should be induced by this stage, and (4) induction of a new locus (45AB) which is not normally observed in a puffed state. Changes in the puffing pattern have been observed when all three mercuric compounds were used, but mainly in concentrations ≥ 1.25 mg Hg/l. Consequently, puffing pattern response does not necessarily correlate with toxic concentrations; instead, the variability in puff response between individuals seems to indicate interindividual variations in sensitivity to mercuric compounds.

Effects of cadmium on development time and prepupal puffing pattern of Drosophila melanogaster.

Effects of cadmium on development time and prepupal puffing pattern of Drosophila melanogaster.

Stress goes Far East: meeting report of the Sixth International Workshop on the Molecular Biology of Stress Responses

The heat shock response was discovered in 1962 by mistake. F. Ritossa was studying the puffing pattern of Drosophila larvae when he discovered a new pattern 1 day (Ritossa 1962, 1996). It turned out that one of his colleagues had raised the temperature of the incubator from 25°C to 32°C leading to the new puffing pattern—and the heat shock response was born. Twelve years later, A. Tissieres studied the heat shock response at the level of proteins using a method of separating radioactively labeled proteins by the newly developed method of polyacrylamide gel electrophoresis. By comparing the protein pattern of different larval tissues grown either at 25°C or heat-shocked to 32°C, Tissieres detected several proteins present at 32°C but absent or nearly absent at 25°C. He coined the term heat shock proteins (Hsps; Larminat et al. 1992). At the end of the 1970s, the heat shock response was discovered in Escherichia coli (Neidhardt and VanBogelen 1981; Yamamori and Yura 1982), and we know now that it occurs in all organisms, from bacteria to man (Shamovsky and Nudler 2008). We also know that the heat shock response is genetically regulated. Important heat shock proteins are molecular chaperones (Saibil 2008) and adenosine triphosphate (ATP)-dependent proteases (Baker and Sauer 2006). But molecular chaperones also play an important role in causing diseases in humans, animals, and plants (Calderwood 2007). Recent books deal with their role in cancer (Calderwood et al. 2007), in inflammation and immunity (Asea and De Maio 2007), and in neurodegenerative diseases (Asea and Brown 2008).

Stress wars: the direct role of host and bacterial molecular chaperones in bacterial infection.

Stress wars: the direct role of host and bacterial molecular chaperones in bacterial infection.

The Canadian Slave Smoking Machine

In the debate over “light” cigarettes, recently released documents demonstrate that the Canadian tobacco companies were aware that smokers were compensating for nicotine years before it was recognized in the literature and well before the introduction of most “light” brands. Compensation is the process by which the smoker adjusts his or her smoking inhalation pattern to maintain a certain level of nicotine. Information on the deliveries of cigarettes is collected by the use of a smoking machine, a device that uses air pressure to “smoke” a cigarette. In many countries, including Canada, the International Organization for Standardization (ISO) provides a standard setting for the parameters of the machine. Although the ISO standard was never meant necessarily to provide correct individual dosage information, at the time of the development, the test method was supposed to reflect actual human smoking of cigarettes. However, by the 1960s, tobacco company researchers were questioning the validity of the ISO standard. Smokers were clearly not smoking like the ISO machine, but no one could accurately measure the yield a human smoker received. In 1966, work started on a machine that would reflect the real human delivery of cigarettes. The machine was to duplicate human smoking behaviour as accurately as possible from the motion of the cigarette to the variables of the puff. The human smoking duplicator or “slave smoking machine” was needed to test for the effects of compensation and the actual deliveries in low tar/nicotine cigarettes. Imperial Tobacco scientists stated that, “It was of vital importance, for product development, to confirm these compensating actions of smokers, and more particularly to measure the degree of success in compensation possibly to help in judging the extent of nicotine decrease which would be tolerated by smokers.” In 1972, after six years of work, the first working smoking duplicator, called the Freiri machine after the names of the inventors Frei-esleben and Ri-el, was finished. The Freiri machine was able to “simultaneously reproduce a subject’s smoking actions, so that the subject and the machine smoke matched cigarettes concurrently by the same puffing patterns with minimal interference in the subject’s smoking pleasure.” Tests on the Frieri smoking machine demonstrated that standard machine assays did not reflect the actual levels of tar, nicotine, or total particulate matter received by the smoker. For instance, a test of the cigarette brand Players demonstrated the differences between standard machine smoking and human smoking behaviour (see Table I). Every parameter tested by Imperial Tobacco on the Freiri was different from the standard machine smoking. A real smoker took more and harder puffs for a longer period of time. Many types of studies were conducted. Different brands were tried: high and low nicotine, high and low tar (see Table II). Different types of filters, papers, and ventilation were all examined. Each study added gave ITL more information on real human smoking habits, and it was clear that smokers compensated to maintain a steady nicotine level: “In each case, the smoker adjusted his smoking habits in order to duplicate his normal cigarette nicotine delivery.” It was now possible for Imperial Tobacco to design cigarettes that would seem to be low in tar and nicotine according to ISO testing, but that deliver much higher quantities of each with actual smoker behaviour. For example, Kozlowski and O’Connor (2001) demonstrated how BAT and ITL used filter ventilation, a feature not present in early 1960s cigarettes, to “cheat” the ISO standard. Pressure drop, or the ease of draw, was also manipulated in experiments to aid compensation. The development of the Freiri Slave Smoking machine enabled ITL to produce cigarettes that took advantage of the disCorrespondence: Michael O. Chaiton, 33 Invermay Avenue, Toronto, ON M3H 1Z1, E-mail: michael.chaiton@utoronto.ca Acknowledgements: Funding generously provided by Canadian Tobacco Control Research Initiative. Thanks go to Neil Collishaw, Physicians for a Smoke-Free Canada, for his comments on earlier drafts.

Genetic and cytogenetic analysis of the olive fruit fly Bactrocera oleae (Diptera: Tephritidae).

The genetic and cytogenetic characteristics of one of the major agricultural pests, the olive fruit fly Bactmcera oleae, are presented here. The mitotic metaphase complement of this insect consists of six pairs of chromosomes including one pair of heteromorphic sex chromosomes, with the male being the heterogametic sex. The analysis of the polytene complements of three larval tissues, the fat body, the salivary glands and the Malpighian tubules of this pest has shown (a) a total number of five long chromosomes (10 polytene arms) that correspond to the five autosomes of the mitotic nuclei and a heterochromatic mass corresponding to the sex chromosomes, (b) the constancy of the banding pattern of the three somatic tissues, (c) the absence of a typical chromocenter as an accumulation of heterochromatin, (d) the existence of reverse tandem duplications, and (e) the presence of toroid tips of the chromosome arms. The in situ hybridization of genes or DNA sequences to the salivary gland polytene chromosomes of B. oleae provided molecular markers for all five autosomes and permitted the establishment of chromosomal homologies among B. olea, B. tryoni and Ceratitis capitata. The heat shock response of B. oleae, as revealed by heat-inducible puffing and protein pattern, shows a higher thermotolerance than Drosophila melanogaster.