The effect of cigarette smoke exposure on developing folate binding protein-2 null mice

Environmental tobacco smoke exposures have been linked to adverse health effects. Folate is essential for normal development, with deficiencies often causing fetal growth restriction. Mice lacking the folate binding protein-2 receptor (Folr2) exhibit increased susceptibility to teratogens. The purpose of the current study was to determine if the loss of Folr2 would increase sensitivity to cigarette smoke-induced effects on development. Pregnant Folr2^−/−, Folr2^+/+, and C57BL/6J mice were exposed to sidestream cigarette smoke during gestation. Exposure to sidestream smoke on gd 6–9 had no adverse effects on fetal outcomes. However, cigarette smoke exposure on gd 6–18.5 increased the number of fetal resorptions (Folr2^−/− cohort) and decreased crown-rump length (Folr2^+/+ fetuses). These data confirm an association between sidestream smoke exposure and fetal growth restriction, but do not suggest that loss of Folr2 increased susceptibility to these effects.     

The effect of cigarette smoke exposure on developing folate binding protein-2 null mice

Environmental tobacco smoke exposures have been linked to adverse health effects. Folate is essential for normal development, with deficiencies often causing fetal growth restriction. Mice lacking the folate binding protein-2 receptor (Folr2) exhibit increased susceptibility to teratogens. The purpose of the current study was to determine if the loss of Folr2 would increase sensitivity to cigarette smoke-induced effects on development. Pregnant Folr2^−/−, Folr2^+/+, and C57BL/6J mice were exposed to sidestream cigarette smoke during gestation. Exposure to sidestream smoke on gd 6–9 had no adverse effects on fetal outcomes. However, cigarette smoke exposure on gd 6–18.5 increased the number of fetal resorptions (Folr2^−/− cohort) and decreased crown-rump length (Folr2^+/+ fetuses). These data confirm an association between sidestream smoke exposure and fetal growth restriction, but do not suggest that loss of Folr2 increased susceptibility to these effects.     

In utero exposure to 1R4F reference cigarette smoke: evaluation of developmental toxicity.

The potential developmental effects of 1R4F reference cigarette smoke were examined using Sprague-Dawley rats exposed for 2 h/day, 7 days/week, by nose-only inhalation at target mainstream smoke concentrations of 150, 300, and 600 mg/m3 total particulate matter (TPM). Males were exposed 4 weeks prior to and during mating, with females exposed 2 weeks prior to mating and during mating, and through gestation day (GD) 20. Sham controls received filtered air to simulate nose-only exposure, while cage controls were maintained untreated. Smoke exposure was confirmed through biomarker evaluation (parental: carboxyhemoglobin, nicotine, and cotinine; fetal: nicotine and cotinine). Characteristic cigarette smoke-related histopathologic changes including nasal epithelial hyperplasia and squamous metaplasia and pigmented macrophages in the lung were observed in all exposed parental groups. Maternal toxicity during gestation was indicated at smoke concentrations of 300 and 600 mg TPM/m3, where corrected total body weight gain was significantly (p 相似文献   

妊娠中期可卡因对小鼠的发育毒性

目的:探讨可卡因对小鼠妊娠中期的发育毒性,尤其是对脑发育的影响.方法:建立妊娠中期给药的小鼠动物模型,体重相近的妊娠母鼠被分为三组:(1)可卡因注射自由饮食组(COC);(2)盐水注射伴有饮食对照组(SPF),饮食参考体重相近、妊娠时间相同的COC组母鼠;(3)盐水注射自由饮食组(SAL).从妊娠第8天(E8)至第12天(E12)给药,记录母鼠、胎鼠和仔鼠的各项生理指标,并用HPLC分析各组胎鼠纹状体中多巴胺、5-HT含量的变化.结果:尽管COC和 SPF组母鼠与 SAL组母鼠相比摄食量少,体重增加量少,但E17 天取材时,仅COC组胎鼠表现为脑和纹状体重量低;COC组仔鼠生后第 1天(P1)双顶径(BPD)也小于其它两组仔鼠.此外,COC组胎鼠表现出脑/体重比的降低,说明宫内暴露可卡因引起的胎鼠的发育迟缓是一个不平衡过程,脑组织的受累比其它组织严重.神经递质分析和组织学分析表明 COC组胎鼠脑内多巴胺和5-羟色胺的水平增高,肝脏呈现出形态学改变.结论:妊娠中期暴露可卡因可引起胎鼠宫内发育迟缓,尤其是脑发育迟缓.单纯母体营养不良在宫内暴露可卡因引起的后代发育迟缓过程中不能起决定性作用,而可能是药物直接作用的结果.     

Early postnatal exposure to cigarette smoke impairs the antigen-specific T-cell responses in the spleen

Annually, approximately two million babies are exposed to cigarette smoke in utero and postnatally through cigarette smoking of their mothers. Exposure to mainstream cigarette smoke is known to impair both innate and adaptive immunities, and it has been hypothesized that the effects of in utero exposure to cigarette smoke on children's health might primarily stem from the adverse effects of cigarette smoke on the immune system. To simulate the environment that babies from smoking mothers encounter, we examined the effects of prenatal mainstream and postnatal sidestream cigarette smoke on spleen cell responses. Results show that postnatal exposure of newborn Balb/c mouse pups to sidestream cigarette smoke through the first 6 weeks of life strongly suppresses the antibody response of spleen cells to the T-cell-dependent antigen, sheep red blood cells. The reduction in the antibody response seen within 6 weeks of postnatal smoke exposure is much quicker than the published data on the time 25 weeks) required to establish reproducible immunosuppression in adult rats and mice. Moreover, the immunosuppression is not associated with significant changes in T-cell numbers or subset distribution. While the postnatal exposure to cigarette smoke did not affect the mitogenic response of T and B cells, the exposure inhibited the T cell receptor-mediated rise in the intracellular calcium concentration. These results suggest that the early postnatal period is highly sensitive to the immunosuppressive effects of environmental tobacco smoke, and the effects are causally associated with impaired antigen-mediated signaling in T cells.     

Maternal passive smoking during pregnancy and fetal developmental toxicity. Part 1: gross morphological effects.

1. Prenatal exposure of human fetus to tobacco smoke through maternal passive smoking has been epidemiologically linked to reduced birth weight, enhanced susceptibility to respiratory diseases and changes in immune system. However, no data exists indicating teratogenicity of involuntary smoking. Since sidestream smoke of cigarettes makes the most constituent of whole smoke inhaled by nonsmokers, we performed experiments to determine whether passive inhalation of sidestream smoke by rats causes malformations in newborns. 2. Pregnant 230 - 300 g Wistar rats were each placed in a 150 dm3 glass chamber with two holes, each 3 cm in diameter in two opposite walls to provide unforced exchange of fresh air. A third hole was connected to an automatic smoking machine. The head of a commercial filter blond cigarette (13 mg Tar, 0.9 mg Nicotine) was introduced to the chamber through this later hole. Cigarettes were smoked by smoking machine at the rate and volume resembling human smoking and the mainstream smoke was separately collected and discarded. Each rat thus received the sidestream smoke self-diluted in the chamber air. Experiments were performed with either 1, 2, 3 or 4 cigarettes/day during either first, second or third week of a total 21-day pregnancy period. The interval between smoking of cigarettes was 2 h. 3. COHb in blood of negative controls was about 1.2% and after exposure to 1 or 4 cigarettes were 6% and 12.2%, respectively. A dose-dependent reduction of birth weight was observed in newborns (P<0.001); bitemporal diameters and body lengths were reduced accordingly. No macroscopically visible gross anomaly could be observed. After removing the fat tissue and staining the skeleton with alizarin, a widespread ossification retardation could be observed in all exposed groups regardless of the dose. Such a retardation was not limited to a particular bone. 4. These results support epidemiologic data on developmental toxicity of passive smoking and further provide evidence on an unfavorable osteopathic effect of sidestream exposure of mother on fetal development.     

Perinatal sidestream cigarette smoke exposure and the developing pulmonary surfactant system in rats.

1. Epidemiological studies have strongly implicated passive smoking with increased incidence of various respiratory diseases in children. Our earlier studies have shown that chronic exposure to tobacco smoke significantly changes the composition and the surface activity of the pulmonary surfactant in adult rats. The aim of the present study was to determine if perinatal exposure to sidestream cigarette smoke influences the composition and function of pulmonary surfactant system in developing rat pups. 2. Pregnant Sprague Dawley rats were exposed to sidestream cigarette smoke in a whole body exposure chamber for a total of 6 h each day and the pups born to these dams were further exposed to sidestream smoke for 2 h/day during postnatal period. Exposure of animals to smoke was ascertained by measuring their plasma cotinine. Surfactant analysis was performed on bronchoalveolar lavage fluids (BALF) collected from pups on postnatal day 1, 3, 7, 14, 21 and 35. The phospholipid (PL) content, percentage disaturated phosphatidylcholine (DSPC) and surfactant proteins (SP-A and SP-B) in BALF surfactant preparations from sham and smoke-exposed pups were compared. 3. Significant differences between the two groups were observed at two exposure points: a reduced level of SP-A on day 1, and, a higher level of SP-A and PLs on day 21, in smoke-exposed pups. Surface activity analysis of the surfactant films by pulsating bubble surfactometer did not show any significant differences between the sham and smoke-exposed groups at any exposure point. 4. The results indicate that perinatal exposure to sidestream smoke is capable of producing biochemical changes in the composition of pulmonary surfactant at different stages of development but these changes do not influence surface tension reducing properties of the surfactant.     

Evidence for carbon monoxide as the major factor contributing to lower fetal weights in rats exposed to cigarette smoke.

One of the major effects of cigarette smoking during pregnancy is bearing a child with lower birth weight. It has previously been demonstrated under experimental conditions in rats that exposure to reference cigarette smoke results in reduced birth weight (E. L. Carmines et al., 2003, Toxicol. Sci. 75, 134-147; C. L. Gaworski et al., 2004, Toxicol. Sci. 79, 157-169). The role of various smoke constituents on lower birth weight was evaluated by exposing time-pregnant Sprague-Dawley rats at the concentrations found in cigarette smoke. The rats were exposed for 2 h/day 7 days/week by nose-only inhalation. The target concentrations were designed to produce the same plasma levels of biomarkers as exposure to 2R4F reference cigarette smoke at a concentration of 600 mg/m(3) total particulate matter. The smoke constituents evaluated included carbon monoxide (CO), nicotine, and a mixture of aldehydes (acrolein, acetaldehyde, and formaldehyde). The smoke constituents were tested individually as well as in mixtures to evaluate potential interactions. Exposure to cigarette smoke during gestation produced a reduction in both maternal body weight gain and fetal weights. Exposure to nicotine reduced maternal body weight gain but had no effect on fetal weight. Exposure to CO had no effect on maternal body weight gain but reduced fetal weight to a degree comparable to cigarette smoke. Exposure to a mixture of aldehydes (acrolein, acetaldehyde, and formaldehyde) had no effect on either maternal body weight gain or fetal weight. Exposure to mixtures of nicotine and CO or nicotine, CO, and aldehydes did not demonstrate any interactions. The results of this study suggest that the observed reduction in fetal weight after exposure to cigarette smoke in rats is due to CO toxicity and not nicotine toxicity.     

Repeated administration of diphenyl diselenide to pregnant rats induces adverse effects on embryonic/fetal development

The present study was carried out to investigate the effects of diphenyl diselenide, (PhSe)(2), on embryo-fetal development. Dams were treated subcutaneously with 1.5, 3.0 and 6.0 mg/kg (PhSe)(2) from days 6 to 15 of pregnancy. After cesarean section at gestation day (GD) 20, external and skeletal abnormalities were evaluated. A decrease in maternal body weight gain was found in (PhSe)(2) groups, indicating maternal toxicity. There was a reduction in the fetal weight and in crown-rump (CR) length of fetuses at three doses tested. The occipito-nasal length decreased in fetuses from dams exposed to 3.0 mg/kg (PhSe)(2). Signs of delayed ossification in the skull, sternebrae and limbs were observed in all (PhSe)(2) groups, revealing a relation between morphological alterations and growth retardation in fetuses, but none of the changes appeared to be dose-dependent. Exposure of dams to (PhSe)(2) resulted in altered placental morphology that may have contributed to adverse reproductive outcomes. We concluded that (PhSe)(2) is toxic to dams and induces developmental delay of the fetal skeleton, but does not cause externally visible malformations in rat fetuses, in this experimental procedure.     

Simultaneous mainstream-sidestream smoke exposure systems II. The rat exposure system

A system for exposing rats to mainstream (MS) and sidestream (SS) smoke simultaneously from the same cigarette, and monitoring procedures, are described in detail. The equipment and procedures were used to expose Sprague-Dawley rats to mainstream smoke and to target deliveries of 10, 25, or 50% of the total SS smoke for 17 weeks. The estimated total particulate matter (TPM) dose was highly correlated with the increase in percent COHb for MS and SS smoke, but the COHb/TPM relationships were different for the 2 kinds of smoke. All SS TPM doses were much lower than the MS TPM dose, and the COHb/TPM ratio for SS smoke was much higher than for MS smoke. The TPM dose and per cent COHb for SS smoke were highly correlated with the per cent of SS sent to the exposure chambers. There were no significant differences in the total weight changes during the study for any of the smoke exposed groups, but weight changes during the 12-17-week period for sidestream exposed groups were inversely correlated with the level of sidestream exposure.     

In vitro genotoxicity assay of sidestream smoke using a human bronchial epithelial cell line.

Genotoxic effects of air contaminants, such as gaseous or particulate compounds, have been difficult to investigate due to inefficient methods for exposing cell cultures directly to these substances. New cultivation and exposure techniques enable treatment of epithelial cells with sample atmospheres with subsequent in vitro assays, as demonstrated by a new system called CULTEX (CULTEX: patent No. DE 19801763; PCT/EP99/00295), which uses a transwell membrane technique for direct exposure of complex mixtures, for example sidestream cigarette smoke, at the air/liquid interface. The sensitivity and susceptibility of human bronchial epithelial cells to this complex mixture have already been shown for cytotoxic endpoints. In this study, genotoxic effects of sidestream cigarette smoke at different concentrations were assessed using the alkaline comet assay. HFBE 21 cells were exposed for 1 h to clean air, nitrogen dioxide or sidestream smoke. Exposure of the cells to sidestream cigarette smoke induced DNA strand breaks in a dose-dependent manner. The combination of gas phase exposure and the comet assay provides a realistic and efficient model for sensitive detection of DNA strand breaks induced by airborne and inhalable compounds.     

Maternal passive smoking during pregnancy and foetal developmental toxicity. Part 2: histological changes.

1. Evidence has been accumulating on the growth suppressing effects of maternal passive smoking on foetus. Reviewing all literature released during the last two decades and screening for all possible variables such as previous smoking history, maternal age and weight gain, parity and length of gestation, placental weight, and diet, we found no reason to doubt the role of passive smoking during pregnancy in the induction of growth retardation. However, no literature indicates whether these birthweight deficits might hint at other possible hidden abnormalities in tissues. To verify this question, we performed an experiment on rats. 2. We have already reported that pups born to rats with previous exposure to cigarette's sidestream smoke during pregnancy showed a significant and dose-dependent growth retardation. Those pregnant rats were exposed each in a 150 dm3 glass chamber to diluted sidestream smoke of either 1, 2, 3 or 4 commercial blond filter brand cigarettes during either first, second or third week of pregnancy. We have selected a part of each group of pups at random and examined for possible histological changes of lung, liver, stomach, kidney and intestinal tissues. 3. Compared to controls, lung tissues of newborns of smoke exposed mothers showed an enhanced incidence of apoptosis, mesenchymal changes, and hyperplasia of bronchial muscles. Pronounced abnormal changes in haematopoiesis and proliferation of bile duct cells were the most variations from norm observed in liver tissues of exposed pups. Immature glomeruli of kidney, epithelhypoplasia of stomach, and hypoplasia of intestinal villi were common among newborns of exposed mothers than among controls. 4. These results indicate that passive smoking upon pregnancy causes abnormal morphological changes in internal tissues of newborns. At present, we can draw no conclusion as to whether these histological changes will result in functional malformations or possibly late effects, although they should be expected.     

Decreased Fetal Weights in Rats Exposed to Sidestream Cigarette Smoke

Pregnant Sprague-Dawley rats were exposed to sidestream Cigarettesmoke (SS) for 6 hr a day, at a concentration of 1 mg/m³ ofrespirable total suspended particulate material (TSP) on Days3, 6–10, and 13–17 of pregnancy. Controls were keptin an identical chamber without smoke exposure. The animalswere killed on Day 20 of gestation. No differences were foundin maternal body weight gain or average daily food consumptionbetween the smoke-exposed and control groups. The numbers offetuses and of implantation sites per litter were comparableamong the groups. None of the pups showed any gross malformationsand no difference was found between controls and SS-exposedpups when examined for reduced skeletal ossifications. However,there was a small but significant reduction in mean pup weight.We conclude that intermittent exposure of rats to sidestreamcigarette smoke at concentrations severalfold greater than thoseencountered in smokey public indoor environments causes intrauterinegrowth retardation.     

Sidestream cigarette smoke-exposure of mouse cells induces cell stress/heat shock-like proteins

Specific alterations in cellular protein synthesis have been identified in mouse L929 and B16 cells exposed to "passive" (sidestream) smoke freshly generated from unfiltered cigarettes. A decrease in both cell viability and protein synthesis was observed in monolayer cell cultures following exposure to increasing numbers (0-12) of puffs of sidestream smoke. With exposures that resulted in approximately 30% or higher loss in cell viability, there was an apparent induction of cell stress/heat shock-like polypeptides with approximate molecular weights of 88,000, 66,000 and 23,000. After exposure to higher numbers of puffs that led to a loss of cell viability of 80% or greater, a different set of polypeptides was synthesized, including a major new protein of 38,000 mol. wt and 2 other predominant proteins of 45,000 and 30,000 mol. wt. The same specific effects on cellular protein synthesis were also observed after exposure to a similar number of puffs of the gas phase of sidestream cigarette smoke (minus the particulate phase components).     

Prenatal exposure to environmental tobacco smoke alters gene expression in the developing murine hippocampus

BackgroundLittle is known about the effects of passive smoke exposures on the developing brain.ObjectiveThe purpose of the current study was to identify changes in gene expression in the murine hippocampus as a consequence of in utero exposure to sidestream cigarette smoke (an experimental equivalent of environmental tobacco smoke (ETS)) at exposure levels that do not result in fetal growth inhibition.MethodsA whole body smoke inhalation exposure system was utilized to deliver ETS to pregnant C57BL/6J mice for 6 h/day from gestational days 6–17 (gd 6–17) [for microarray] or gd 6–18.5 [for fetal phenotyping].ResultsThere were no significant effects of ETS exposure on fetal phenotype. However, 61 “expressed” genes in the gd 18.5 fetal hippocampus were differentially regulated (up- or down-regulated by 1.5-fold or greater) by maternal exposure to ETS. Of these 61 genes, 25 genes were upregulated while 36 genes were down-regulated. A systems biology approach, including computational methodologies, identified cellular response pathways, and biological themes, underlying altered fetal programming of the embryonic hippocampus by in utero cigarette smoke exposure.ConclusionsResults from the present study suggest that even in the absence of effects on fetal growth, prenatal smoke exposure can alter gene expression during the “early” period of hippocampal growth and may result in abnormal hippocampal morphology, connectivity, and function.     

Diazepam Metabolism in the Guinea Pig Materno-Fetal Model: Effects of Cigarette Smoke

ABSTRACT

The transplacental acquisition, disposition and biotransforma-tion of diazepam (DZ) was investigated in the pregnant guinea pig at 65–67 days of gestation following the administration of single oral doses of 10 mg/kg body weight, the dams and fetuses being euthanized 60 min post-treatment. Tissues (blood plasma, liver, brain, perirenal fat and placenta) were removed for drug residue analysis. Nordiazepam (NDZ) was the only metabolite produced by guinea pigs in vivo. Residues of DZ and NDZ were found in fetal tissues, indicating that the placenta was not an effective barrier. The influence of cigarette smoke on in vitro DZ biotransformation was studied by exposing pregnant guinea pigs (55–57 days of gestation) to ambient air (control) or cigarette smoke thrice daily for 10 consecutive days. At term (day 671, the fetuses were delivered by caesarian section for the preparation of hepatic and placental microsomes to measure the metabolism of DZ. DZ was converted at a slow rate into NDZ by fetal hepatic and placental microsomes in vitro. Exposure to cigarette smoke had no effect on DZ metabolism by the dam liver or by the placenta but a 2–4-fold increase in NDZ formation was observed in fetal hepatic microsomes.     

Diazepam metabolism in the guinea pig materno-fetal model: effects of cigarette smoke

The transplacental acquisition, disposition and biotransformation of diazepam (DZ) was investigated in the pregnant guinea pig at 65-67 days of gestation following the administration of single oral doses of 10 mg/kg body weight, the dams and fetuses being euthanized 60 min post-treatment. Tissues (blood plasma, liver, brain, perirenal fat and placenta) were removed for drug residue analysis. Nordiazepam (NDZ) was the only metabolite produced by guinea pigs in vivo. Residues of DZ and NDZ were found in fetal tissues, indicating that the placenta was not an effective barrier. The influence of cigarette smoke on in vitro DZ biotransformation was studied by exposing pregnant guinea pigs (55-57 days of gestation) to ambient air (control) or cigarette smoke thrice daily for 10 consecutive days. At term (day 67), the fetuses were delivered by caesarean section for the preparation of hepatic and placental microsomes to measure the metabolism of DZ. DZ was converted at a slow rate into NDZ by fetal hepatic and placental microsomes in vitro. Exposure to cigarette smoke had no effect on DZ metabolism by the dam liver or by the placenta but a 2-4-fold increase in NDZ formation was observed in fetal hepatic microsomes.     

Embryotoxicity and fetotoxicity from maternal inhalation of methyl methacrylate monomer in rats

Inhalation of methyl methacrylate (MMA) has been reported to produce systemic toxicity in laboratory animals, and parenteral administration of MMA has induced embryo-fetal growth retardation and some fetal malformations in rats. To ascertain whether or not inhalation of MMA might also have an effect on reproduction, pregnant rats were exposed to air containing approximately 110 mg/liter MMA. The acute LT50 was determined to be 72.2 min. Pregnant rats were exposed daily to approximately one-quarter and three-quarters of the acute LT50 on Days 6 through 15 of gestation. Data from MMA-treated groups were compared to two groups of controls, a group similarly exposed to air only, and an untreated group. Significant differences (p<0.05) were indicated between one or both treated groups and one or both controls for maternal weight and food consumption, and for fetal weight, crown-rump length, early fetal deaths, and for certain gross and skeletal anomalies, but not for numbers of fetuses per litter or resorptions.     

Human alpha-1-proteinase inhibitor is inactivated by exposure to sidestream cigarette smoke

Direct exposure of human alpha-1-proteinase inhibitor (alpha 1PI) to sidestream cigarette smoke causes an initial, rapid loss of elastase inhibitory capacity followed by a slow, gradual loss of activity as the protein is incubated in the smoke-exposed aqueous buffer solution. The exposure used here gives a total of 40% inactivation using one cigarette. This biphasic pattern of inactivation is similar to the inactivation seen following the direct exposure of alpha 1PI to mainstream smoke. We suggest that although exposures to sidestream smoke by nonsmokers are generally lower than the exposures to mainstream smoke experienced by smokers, sidestream smoke has the potential to produce similar types of damage as mainstream smoke, including emphysema-like damage, and should not be regarded as innocuous.     

CYTOTOXICITY ASSESSMENT OF WHOLE SMOKE AND VAPOR PHASE OF MAINSTREAM AND SIDESTREAM CIGARETTE SMOKE FROM THREE KENTUCKY REFERENCE CIGARETTES

Assessment of the cytotoxicity of mainstream and sidestream cigarette sm oke has traditionally involved exposure of cell cultures to the particulate m atter of smoke. For a m ore com plete assessment of cigarette sm oke cytotoxicity, a technique (cellular smoke exposure technique or CSET) was developed to directly expose mammalian cell cultures to either whole mainstream or sidestream cigarette sm oke. The objective of this study was to com pare the cytotoxicity of whole smoke or vapor phase from mainstream or sidestream sm oke of three Kentucky reference cigarettes. The cigarettes com pared were a high ''tar''cigarette (2R1), a low ''tar'' cigarette (1R4F), and an ultra low ''tar'' cigarette (1R5F). Cytotoxicity was assessed in two cell types (WB rat liver cells and CHO cells) using the neutral red cytotoxicity assay. The order of cytotoxicity of m ainstream smoke from the three cigarettes expressed on a per cigarette basis was 2R1 > 1R4F > 1R5F. Sidestream sm oke from all three reference cigarettes was more toxic than the respective mainstream smoke on a per cigarette basis. The vapor phase of mainstream or sidestream smoke was the major contributor to the cytotoxicity of the whole cigarette smoke. Finally, the com parative trends in cytotoxicity between the smoke from the three reference cigarettes was similar in the two cell types, but CHO cells were more sensitive. CSET is a useful system to assess the cytotoxicity of cigarette smoke and m ay serve as an appropriate adjunct to the use of isolated particulate matter for the in vitro toxicological assessment of cigarette smoke and other aerosols.