Electrocardiographic alterations in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality, and its incidence has grown within several years, quickly becoming the third leading cause of mortality. The disease is characterized by alveolar destruction, air-trapping, and chronic inflammation due to persistent exposure to a large spectrum of harmful particles. The diagnosis of COPD is made by demonstration of persistent and not fully reversible airflow limitation, and different phenotypes may be recognized based on pathophysiological, clinical, and radiological features. However, COPD is a systemic disease with effects involving several organs. For example, mechanical and functional alterations secondary to COPD involve heart function. Indeed, cardiovascular diseases are highly prevalent in patients affected by COPD and represent the primary cause of mortality in such patients. An electrocardiogram is a simple and cheap test that gives much information about the heart status of COPD patients. Consequently, variations from "normality" can be appreciated in these patients, with the most frequent abnormalities being P-wave, QRS axis, and ventricular repolarization abnormalities, in addition to conduction alterations and a vast number of arrhythmias. As a result, ECG should be routinely performed as a valuable tool to recognize alterations due to COPD (i.e., mechanical and functional) and possible associated heart diseases. This review aims to describe the typical ECG features in most COPD patients and to provide a systematic summary that can be used in clinical practice.

Electrocardiogram Features in Non-Cardiac Diseases: From Mechanisms to Practical Aspects

Despite the noteworthy advancements and the introduction of new technologies in diagnostic tools for cardiovascular disorders, the electrocardiogram (ECG) remains a reliable, easily accessible, and affordable tool to use. In addition to its crucial role in cardiac emergencies, ECG can be considered a very useful ancillary tool for the diagnosis of many non-cardiac diseases as well. In this narrative review, we aimed to explore the potential contributions of ECG for the diagnosis of non-cardiac diseases such as stroke, migraine, pancreatitis, Kounis syndrome, hypothermia, esophageal disorders, pulmonary embolism, pulmonary diseases, electrolyte disturbances, anemia, coronavirus disease 2019, different intoxications and pregnancy.

Relationship between abnormal P-wave axis, chronic obstructive pulmonary disease and mortality in the general population

BACKGROUND

It is unclear whether the presence of a vertical P-wave axis on electrocardiogram modifies the association of COPD with mortality.

OBJECTIVE

To examine the association and interaction of abnormal P-wave axis and COPD with mortality.

STUDY DESIGN AND METHODS

The analysis included 7359 with ECG data from the Third National Health and Nutrition Examination Survey (NHANES-III) who were free of cardiovascular disease (CVD) at enrollment. Abnormal P-wave axis (aPWA) was defined as values above 75°. COPD was self-reported as either a diagnosis of emphysema or chronic bronchitis. National Death Index was used to identify the date of death and cause of death. Using multivariable Cox proportional hazard analysis, we examined the association of COPD with all-cause mortality by aPWA status.

RESULTS

Over a median follow-up of 14 years, 2435 deaths occurred. Participants with concomitant presence of aPWA and COPD experienced higher death rates (73.9 per 1000 person-years (PY)) compared to either COPD or aPWA alone (36.4 per 1000 PY and 31.1 per 1000 PY), respectively. In multivariable-adjusted models, a stronger association between COPD and mortality was noted in the presence compared to the absence of aPWA (HR 95% CI): 1.71 (1.37-2.13) vs. 1.22(1.00-1.49), respectively (interaction P-value = 0.02). Similarly, a stronger association between aPWA and mortality was observed in the presence compared to the absence of COPD (HR 95% CI): 1.66(1.26-2.19) vs. 1.18(1.06-1.31), respectively (interaction P-value = 0.02). Similar higher death rates and mortality risk was observed when spirometry-confirmed COPD and aPWA were present together than in isolation.

CONCLUSION

The concomitant presence of aPWA and COPD leads to a significantly higher mortality rate compared to the presence either COPD or aPWA alone as a clinical variable. P-wave axis, reported routinely on ECG printout, can potentially identify patients with COPD who need intensive control of risk factors and disease management.

Electrocardiographic alterations in patients with chronic obstructive pulmonary disease

Patients with chronic obstructive pulmonary disease (COPD) have an increased risk for cardiovascular events, and electrocardiography has an important role in detecting cardiac side effects of COPD-related hypoxia.

Perfluorooctanoic acid (PFOA) acts as a tumor promoter on Syrian hamster embryo (SHE) cells

Perfluorooctane sulfonate (PFOS) (C(8)F(17)SO(3)) and perfluorooctanoic acid (PFOA) (C(8)HF(15)O(2)) are synthetic chemicals widely used in industrial applications for their hydrophobic and oleophobic properties. They are persistent, bioaccumulative, and toxic to mammalian species. Their widespread distribution on earth and contamination of human serum raised concerns about long-term side effects. They are suspected to be carcinogenic through a nongenotoxic mode of action, a mechanism supported by recent findings that PFOS induced cell transformation but no genotoxicity in Syrian hamster embryo (SHE) cells. In the present study, we evaluated carcinogenic potential of PFOA using the cell transformation assay on SHE cells. The chemical was applied alone or in combination with a nontransformant concentration of benzo[a]pyrene (BaP, 0.4 μM) in order to detect PFOA ability to act as tumor initiator or tumor promoter. The results showed that PFOA tested alone in the range 3.7 × 10(-5) to 300 μM did not induce SHE cell transformation frequency in a 7-day treatment. On the other side, the combination BaP/PFOA induced cell transformation at all PFOA concentrations tested, which revealed synergistic effects. No genotoxicity of PFOA on SHE cells was detected using the comet assay after 5 and 24 h of exposure. No significant increase in DNA breakage was found in BaP-initiated cells exposed to PFOA in a 7-day treatment. The whole results showed that PFOA acts as a tumor promoter and a nongenotoxic carcinogen. Cell transformation in initiated cells was observed at concentrations equivalent to the ones found in human serum of nonoccupationally and occupationally exposed populations. An involvement of PFOA in increased incidence of cancer recorded in occupationally exposed population cannot be ruled out.

Alternative (non-animal) methods for cosmetics testing: current status and future prospects-2010

The 7th amendment to the EU Cosmetics Directive prohibits to put animal-tested cosmetics on the market in Europe after 2013. In that context, the European Commission invited stakeholder bodies (industry, non-governmental organisations, EU Member States, and the Commission's Scientific Committee on Consumer Safety) to identify scientific experts in five toxicological areas, i.e. toxicokinetics, repeated dose toxicity, carcinogenicity, skin sensitisation, and reproductive toxicity for which the Directive foresees that the 2013 deadline could be further extended in case alternative and validated methods would not be available in time. The selected experts were asked to analyse the status and prospects of alternative methods and to provide a scientifically sound estimate of the time necessary to achieve full replacement of animal testing. In summary, the experts confirmed that it will take at least another 7-9 years for the replacement of the current in vivo animal tests used for the safety assessment of cosmetic ingredients for skin sensitisation. However, the experts were also of the opinion that alternative methods may be able to give hazard information, i.e. to differentiate between sensitisers and non-sensitisers, ahead of 2017. This would, however, not provide the complete picture of what is a safe exposure because the relative potency of a sensitiser would not be known. For toxicokinetics, the timeframe was 5-7 years to develop the models still lacking to predict lung absorption and renal/biliary excretion, and even longer to integrate the methods to fully replace the animal toxicokinetic models. For the systemic toxicological endpoints of repeated dose toxicity, carcinogenicity and reproductive toxicity, the time horizon for full replacement could not be estimated.

A refined protocol for conducting the low pH 6.7 Syrian hamster embryo (SHE) cell transformation assay

The Syrian hamster embryo (SHE) cell transformation assay evaluates the potential of chemicals to induce morphological transformation in karyotypically normal primary cells. Induction of transformation has been shown to correlate well with the carcinogenicity of many compounds in the rodent bioassay. Historically the assay has not received wide-spread use due to technical difficulty. An improved protocol for a low pH 6.7 assay was developed by LeBoeuf et al. [R.A. LeBoeuf, G.A. Kerckaert, M.J. Aardema, D.P. Gibson, R. Brauninger, R.J. Isfort, Mutat. Res., 356 (1996) 85-127], that greatly reduced many of the technical difficulties associated with the SHE assay. The purpose of this paper is to describe the most current execution of the pH 6.70 protocol including protocol refinements made since the publication of a comprehensive protocol for this assay in Kerckaert et al. [G.A. Kerckaert, R.J. Isfort, G.J. Carr, M.J. Aardema, Mutat. Res., 356 (1996) 65-84].

Morphological transformation and effect on gap junction intercellular communication in Syrian hamster embryo cells as screening tests for carcinogens devoid of mutagenic activity

A large fraction of chemicals observed to cause cancer in experimental animals is devoid of mutagenic activity. It is therefore of importance to develop methods that can be used to detect and study environmental carcinogenic agents that do not interact directly with DNA. Previous studies have indicated that induction of in vitro cell transformation and inhibition of gap junction intercellular communication are endpoints that could be useful for the detection of non-genotoxic carcinogens. In the present work, 13 compounds [chlordane, Arochlor 1260, di(2-ethylhexyl)phthalate, 1,1,1-trichloro-2, 2-bis(4-chlorophenyl)ethane, limonene, sodium fluoride, ethionine, o-anisidine, benzoyl peroxide, o-vanadate, phenobarbital, 12-O-tetradecanoylphorbol 13-acetate and clofibrate] have been tested for their ability to induce morphological transformation and affect intercellular communication in Syrian hamster embryo cells. The substances were selected on the basis of being proven or suspected non-genotoxic carcinogens, and thus difficult to detect in short-term tests. The data show that nine of the 13 compounds induced morphological transformation, and seven of the 13 inhibited intercellular communication in hamster embryo cells. Taken together, 12 of the 13 substances either induced transformation or caused inhibition of communication. The data suggest that the combined use of morphological transformation and gap junction intercellular communication in Syrian hamster embryo cells may be beneficial when screening for non-genotoxic carcinogens.

The pH 6.7 Syrian hamster embryo cell transformation assay for assessing the carcinogenic potential of chemicals

Cell transformation models have been established for studying the cellular and molecular basis of the neoplastic process. Transformation models have also been utilized extensively for studying mechanisms of chemical carcinogenesis and, to a lesser degree, screening chemicals for their carcinogenic potential. Complexities associated with the conduct of cell transformation assays have been a significant factor in discouraging broad use of this approach despite their reported good predictivity for carcinogenicity. We previously reported that many of the experimental difficulties with the Syrian hamster embryo (SHE) cell transformation assay could be reduced or eliminated by culturing these cells at pH 6.7 culture conditions compared to the historically used pH 7.1-7.3. We and others have shown that morphological transformation (MT), the earliest recognizable phenotype in the multi-step transformation process and the endpoint used in the standard assay to indicate a chemical's transforming activity, represents a pre-neoplastic stage in this model system. In the collaborative study reported here, in which approx. 50% of the chemicals were tested under code in one laboratory (Hazelton) and the other 50% evaluated by several investigators in the second laboratory (P & G), we have evaluated 56 chemicals (30 carcinogens, 18 non-carcinogens, 8 of inconclusive carcinogenic activity) in the SHE cell transformation assay conducted at pH 6.7 culture conditions with a standardized, Good Laboratory Practices-quality protocol. An overall concordance of 85% (41/48) between SHE cell transformation and rodent bioassay results was observed with assay sensitivity of 87% (26/30) and specificity of 83% (15/18), respectively. The assay exhibited a sensitivity of 78% (14/18) for Salmonella assay negative carcinogens, supporting its value for detecting non-mutagenic carcinogens. For maximum assay sensitivity, two exposure durations were required, namely a 24-h exposure and a 7-day exposure assay. Depending on the duration of chemical treatment required to induce transformation, insight into the mechanism of transformation induction may also be gained. Based on the data reported here, as well as the larger historical dataset reviewed by Isfort et al. (1996), we conclude that the SHE cell transformation assay provides an improved method for screening chemicals for carcinogenicity relative to current standard genotoxicity assays.

Effect of glucocorticoids on TPA-induced inhibition of gap-junctional communication and morphological transformation in Syrian hamster embryo cells

The effect of glucocorticoids on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inhibition of gap-junctional intercellular communication (GJIC) and morphological transformation in Syrian hamster embryo (SHE) cells was examined. Fluocinolone acetonide (FA) and dexamethasone (DEX) almost completely suppressed the effect of TPA on induction of transformed morphology. On the other hand, up to 1000 times higher FA and DEX concentrations did not influence the inhibitory effect of TPA on GJIC. Neither treatment with these glucocorticoids for 4, 24 or 48 h before TPA exposure nor 24 h co-exposure with TPA altered the effect of TPA on GJIC. Thus the potent effect of glucocorticoids as inhibitors of the promotional effect of TPA on morphological transformation in SHE cells does not result in alterations of TPA-induced inhibition of GJIC.

Morphological transformation of Syrian hamster embryo cells by mezerein

Mezerein (MEZ) has been described as a weak complete tumor promoter but an effective stage II promoter in the mouse skin initiation-promotion tumor model. In this study MEZ produced a strong transformation response when tested under code in the Syrian hamster embryo (SHE) clonal morphological transformation assay. Using a standard 7-day exposure protocol designed to detect complete carcinogens, MEZ was active at non-toxic concentrations, producing a linear response between 0.3-10 ng/ml in a log-log plot of transformation activity versus concentration. These concentrations were in the same range as those which had been shown to elicit promotion activity in several in vitro cell culture systems. Our data suggest that the SHE assay has the ability to detect some tumor promoters under the same conditions used to test for complete carcinogens. The possibility that MEZ may possess in vivo carcinogenic activity cannot be excluded.

Role of catalase and oxidative stress in hepatic peroxisome proliferator-induced morphological transformation of Syrian hamster embryo cells

Several hepatic peroxisome proliferators (HHPs) such as di(2-ethylhexyl)phthalate (DEHP), mono(2-ethylhexyl)-phthalate, clofibrate and tiadenol, induce morphological transformation of Syrian hamster embryo (SHE) cells in vitro. According to one hypothesis, the hepatocarcinogenic effect of HPPs is caused by an oxidative stress due to increased H2O2-production from the strongly induced peroxisomal beta-oxidation of fatty acids. Thus, increased transformation frequencies by HPPs should be obtained when catalase was inhibited by 3-amino-1,2,4-triazole (amitrole). However, co-exposure to HPPs and amitrole did not enhance the transformation frequencies for any of the HPPs. The sensitivity of SHE cells for oxidative agents was studied by using menadione and H2O2. Menadione only induced transformation at a toxic concentration, while H2O2 induced transformation at non-toxic concentrations. To study the generation of oxidative radicals in SHE cells, electron spin resonance was employed. No oxidative radical formation was detected in tiadenol- or DEHP-exposed SHE cells. When menadione or H2O2 were added during the measurements, oxidative radicals were found. A transmission electron microscopic study showed a small number of peroxisomes, and did not reveal any increase in the number of peroxisomes in clofibrate-treated SHE cells.

Morphological transformation of Syrian hamster embryo cells by aminobenzyl alcohols and nitrobenzyl alcohols is correlated with intercellular communication

Two aminobenzyl alcohols (ABAs) and 3 nitrobenzyl alcohols (NBAs) were studied in the Syrian hamster embryo (SHE) cell transformation system. All compounds induced statistically significant increases in morphological transformation of SHE cells. 2-ABA and 3-ABA induced dose-dependent increases in transformation, while the transformation frequencies for 2-NBA and 4-NBA decreased when concentrations were increased above 0.2 mM. When tested in an intercellular communication assay using dye transfer between SHE cells, 2-ABA inhibited communication, and 2-NBA and 4-NBA enhanced communication. Thus, the inverse dose-response of 2-NBA related to an increased intercellular communication.

Vanadium compounds promote the induction of morphological transformation of hamster embryo cells with no effect on gap junctional cell communication

Vanadium compounds were found to promote the induction of morphological transformation of hamster embryo cells. Exposure of the cells to Na-O-vanadate, vanadin (V) oxide or vanadin (IV) oxide sulfate following pre-exposure to a low concentration of benzo[a]pyrene, potentiated the induction of transformed colonies similar to 12-O-tetradecanoylphorbol-13-acetate. Unlike this phorbol ester, vanadium compounds did not inhibit intercellular communication, or active protein kinase C. Nor did vanadate influence the reoccurrence of communication after removal of a communication blocking phorbol ester. On the other hand, vanadate showed strong synergism with the phorbol ester on induction of transformed morphology in the phorbol ester sensitive cell line BPNi. This suggests that vanadium and tumor promoting phorbol esters mediate their effect on the induction of morphological transformation of hamster embryo cells through different mechanisms.

The non-phorbol ester tumor promoter okadaic acid does not promote morphological transformation or inhibit junctional communication in hamster embryo cells

Okadaic acid is a potent non-phorbol ester mouse skin tumor promoter. Unlike the phorbol ester tumor promoters, okadaic acid is unable to promote the induction of morphological transformation in Syrian hamster embryo cell colonies. On the contrary, okadaic acid seems to counteract the effect of phorbol esters on transformation. Also unlike phorbol ester tumor promoters, okadaic acid does not inhibit intercellular communication, neither in primary hamster embryo cells, nor in the phorbol ester sensitive cell line BPNi. Furthermore, okadaic acid has no effect on the reoccurrence of communication following removal of 12-O-tetradecanoylphorbol-13-acetate.

Morphological transformation and catalase activity of Syrian hamster embryo cells treated with hepatic peroxisome proliferators, TPA and nickel sulphate

The abilities of the hepatic peroxisome proliferators (HPPs) clofibrate, di(2-ethylhexyl)phthalate (DEHP), mono(2-ethylhexyl)-phthalate (MEHP), 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichlorophenoxy acetic acid (2,4,5-T) and tiadenol to induce morphological transformation and to increase the catalase activity of Syrian hamster embryo (SHE) cells were studied. DEHP, MEHP, clofibrate and tiadenol induced morphological transformation of SHE cells and increased the catalase activity. DEHP was more potent than clofibrate and tiadenol in both inducing catalase and morphological transformation, while MEHP seemed more potent than DEHP in inducing catalase, but not morphological transformation, 2,4,5-T and 2,4-D did not induce morphological transformation, but 2,4,5-T was more potent than clofibrate in increasing the catalase activity. These results show that several HPPs induce morphological transformation of SHE cells and an increase in the catalase activity. There is, however, no direct connection between these two parameters, as seen from the results of 2,4,5-T. The tumor promoter TPA, and the metal salt nickel sulphate, induced morphological transformation of SHE cells without any appreciable increase in the catalase activity. These results further corroborate the dissociation between induction of morphological transformation and the increase in catalase activity.

Effects of dinitrotoluenes on morphological cell transformation and intercellular communication in Syrian hamster embryo cells

The effects of four isomers of dinitrotoluene (DNT) and technical DNT (a mixture of DNT isomers and other compounds, with 2,4-DNT as the major constituent) were studied in two short-term in vitro assays. None of the isomers or technical DNT induced an increase in morphological transformation of Syrian hamster embryo (SHE) cells. Four DNT metabolites (2,4-diaminotoluene, 2-amino-4-nitrotoluene, 2-amino-6-nitrotoluene, and 2,4-dinitobenzoic acid), representing different stages in reduction or oxidation of DNT isomers, were also negative for induction of morphological transformation. The DNT isomers were tested in an intercellular communication assay based on dye transfer. 2,4-DNT, 2,6-DNT, and technical DNT inhibited intercellular communication in the SHE cell line BPNi at toxic concentrations. This may be reminiscent of in vivo data showing promoting activity of these compound. 2,3-DNT and 3,4-DNT did not inhibit communication.

Multistage carcinogenesis: implications for risk estimation

In undertaking a quantitative estimation of carcinogenesis risk, it is essential to keep in mind that carcinogenesis is a multistage process, and that each stage can be affected by different classes of risk factors. Furthermore, different mechanisms are involved in the various stages of carcinogenesis. Thus, a dose-response analysis of one given factor cannot provide an accurate estimation of carcinogenic risk. Carcinogenic risk estimation is usually undertaken for a specific chemical or group of chemicals; however, the concept of multistage carcinogenesis is based on biological processes and not on the mechanisms of action of the agents involved. It is therefore important to consider three related, but different, factors involved in carcinogenesis: stage, agent, and activity of agent. This is especially important in developing a short-term test for stage-related risk factors, such as tumor-promoting agents. For this reason, carcinogens should not be classified according to only one chemical activity. This article briefly reviews the cellular and molecular mechanisms involved in multistage carcinogenesis, and discusses their implications for risk estimation. Special consideration is given to the effect of treatment frequency on the response of tumor-promoting agents, as seen in long-term tests in experimental animals. It is proposed that exposure frequency be taken into account together with exposure dose.

Cell transformation and promoter activity of insulation oils in the Syrian hamster embryo cell and in the C3H/10T1/2 mouse embryo fibroblast test systems

The ability of mineral-oil-based and synthetic cable insulating fluids to transform and promote transformation of mammalian cells in vitro have been studied. In experiments with the Syrian hamster embryo cell transformation assay, it was found that C15-C18 alkylbenzenes were the most potent inducers of transformation, followed by low-viscosity and residual mineral oils. No activity and low cytotoxicity were found for a low-viscosity polyisobutylene-based oil. In the two-stage transformation assay of C3H/10T1/2 cells, promoter activity was obtained with all fluids tested. A blend of residual and low-viscosity mineral oils showed the highest activity. This oil possessed a low cytotoxicity and was tested at a relatively high concentration. The alkylbenzenes were more potent than the polyisobutylene-based fluid. The alkylbenzenes were also found to possess initiating activity in the two-stage assay, when 12-O-tetradecanoylphorbol 13-acetate (TPA) was used as promoter. All the fluids showed low potency compared to benzo[a]pyrene and the tumor promoter TPA.

Modulation of benzo[a]pyrene-induced morphological transformation of Syrian hamster embryo cells by butylated hydroxytoluene and butylated hydroxyanisole

The Syrian hamster embryo cell transformation assay has been used to investigate the effect of two synthetic antioxidants on morphological transformation induced by the initiator benzo[a]pyrene (BP). A two-stage protocol was employed with an initiation phase of 2 days and a subsequent promotion phase of 5 days. When 10 microM butylated hydroxytoluene (BHT) were present in the promotion phase instead of the solvent the transformation frequency at 0.1 micrograms BP/ml increased from 0.27% to 0.55%; at 100 microM of BHT the transformation frequency was 0.77%. Butylated hydroxyanisole (BHA) also enhanced the percentage of transformed colonies from 0.40% (10 microM) to 0.49% (100 microM), respectively. No significant initiating activity was detected for both antioxidants when tested in the initiation phase instead of BP; when the antioxidants were applied simultaneously with BP (1 microgram/ml) during the initiation phase the transformation frequency was decreased from 0.64% to 0.15% (100 microM BHT) and to 0.17% (100 microM BHA), respectively. These results show that the dual action of phenolic antioxidants on chemical carcinogenesis, which depends on the administration schedule, can be imitated in an in vitro test system. In addition to their anti-initiation effect, BHT and BHA, while devoid of intrinsic initiator potency, exert a moderate promotional activity on hamster embryo cell cultures. Their ability to enhance tumorigenesis by various carcinogens in vivo is likely to be at least partially related to such promotion-like effects on cell growth and morphology.

Comparative genotoxicity and nephrotoxicity studies of the two halogenated flame retardants tris(1,3-dichloro-2-propyl)phosphate and tris(2,3-dibromopropyl)phosphate

Tris(1,3-dichloro-2-propyl)phosphate (Tris-CP) was metabolized to products which were mutagenic for Salmonella typhimurium TA100 in the presence of liver microsomes from phenobarbital (PB)-pretreated rats and NADPH. Effects of various inhibitors and inducers of cytochrome P-450 on Tris-CP mutagenicity were in accordance with PB-inducible forms of this enzyme system being responsible for the formation of mutagenic product(s). A comparison was made between the toxic potential of the two halogenated flame retardants Tris-CP and tris(2,3-dibromopropyl)phosphate (Tris-BP) in 5 in vitro tests. Tris-CP was much less potent than Tris-BP with respect to bacterial (Salmonella/microsome or Salmonella/hepatocyte assay) and mammalian (V79 cells) mutagenicity, as well as DNA repair synthesis in hepatocytes. On the other hand, Tris-CP and Tris-BP were both equally effective in transforming Syrian hamster embryo cells in vitro. Tris-CP was not nephrotoxic to rats after a single dose of 500 mg/kg intraperitoneally, whereas Tris-BP caused extensive tubular necrosis accompanied by elevated levels of plasma urea and creatinine.

Effects of incubation in an atmosphere of 20% CO2 in air on the Syrian hamster embryo clonal transformation assay

An atmosphere containing 10% CO2 has been generally accepted as optimal for the growth of Syrian hamster embryo cells in a clonal transformation assay. Data presented in this paper show that 10% CO2 may not be the optimum environment for this assay. Using 10 or 20% (analytically measured) CO2 in air (1 atm pressure), hamster embryo cell pools were examined for clonal growth characteristics and transformability using five known carcinogens and a single noncarcinogenic compound. At 10% CO2, only 2 of 11 pools were transformed by the five carcinogens but not by the noncarcinogen. At 20% CO2, six of seven pools were transformed by the five carcinogens and not by the noncarcinogen. Further, the transformation frequencies were found to be greater in cultures incubated in an atmosphere consisting of 20% CO2 in air. The data also show that 20% CO2 increased the cloning efficiency of these cells. A comparison of the 10 and 20% CO2 data to results reported from other laboratories suggests that conflicting interlaboratory results with this assay system may be due, in part, to variations of CO2 concentrations. In some instances, the CO2 levels indicated by incubator flow meters vary considerably from analytically determined CO2 values. To prevent these CO2 discrepancies and their resultant effects on transformation and cloning efficiency, methods for monitoring the CO2 environment other than flow meters are recommended. The observation of increased cloning efficiencies and transformation rates strongly suggests that culture incubation at 20% CO2 is a preferred environment for the conduct of this assay.

Short-term bioassays of fractionated emission samples from wood combustion

Extracts of an emission sample from wood burning, consisting of particles and volatiles, have been fractionated on an HPLC silica gel column into five fractions of increasing polarity. Nonfractionated samples and the individual fractions have been tested in three different short-term bioassays: the Ames Salmonella assay, the sister chromatid exchange (SCE) induction-test in Chinese hamster ovary cells (CHO), and the cell transformation test on Syrian hamster embryo (SHE) cells. Most of the total activity was found in the volatile part of the sample with all three bioassays, whereas the particle extract had the highest activity per unit mass extracted. The second most polar fraction contained most of the mass and was also highly active in all assays. The most polar fraction was very potent in the Salmonella assay, but showed only a weak response in the eukaryotic bioassays. Storage of the samples for several months at 0 degrees C revealed that the bacterial mutagens present in the most polar fraction were labile; the mutagenicity was almost totally lost after 1 year's storage.

Role of plasma fibronectin in the morphological transformation of hamster embryo cells

Replacement of fetal bovine serum (FBS) by newborn serum in the hamster embryo cell transformation assay blocks the induction of morphologically transformed colonies by chemical carcinogens. Moreover, the addition of newborn serum strongly inhibits the formation of morphologically transformed colonies in the standard assay using 20% FBS. The present experiments show that the inhibitory factor is heat labile and not dialyzable, but is removed when the newborn serum is submitted to gelatin affinity chromatography. The inhibitory factor is recovered in the eluted gelatin bound material which gives essentially one band in SDS electrophoresis corresponding to that of plasma fibronectin. In separate experiments fibronectin from bovine plasma is shown to inhibit cell transformation in a similar way. The experiments suggest that fibronectin plays a central role in the mechanism of morphological cell transformation.