A review of conflict of interest, competing interest, and bias for toxicologists.

One of the issues often associated with scientific misconduct is conflict of interest. Although there is a lack of uniformity in the definition of conflict of interest, many express concerns that competing interests may bias research methods and the interpretation of data and conclusions. In extreme cases, conflict of interest activity could contribute to scientific misconduct, hinder the training of scientists, delay the dissemination of research results, lead to the harming of human health and the environment, and misdirect society's decisions that rely on science. This article is not a commentary or editorial but an attempt to supply an overview of what has been said, researched, and accomplished in the area of conflict of interest for toxicologists. Discussion of the financial, professional, and philosophical concerns associated with conflict of interest will be followed by brief discussion of general management approaches and the roles of scientists and organizations from all sectors (i.e., academia, industry, non-profit organizations, and government).

Using base-specific Salmonella tester strains to characterize the types of mutation induced by benzidine and benzidine congeners after reductive metabolism.

Although benzidine (Bz), 4-aminobiphenyl (ABP), 3,3'-dichlorobenzidine HCl (DCBz), 3,3'-dimethylbenzidine (DMBz), 3,3'-dimethoxybenzidine (DMOBz) and the benzidine congener-based dye trypan blue (TB) produce primarily frameshift mutations in Salmonella typhimurium, the base-substitution strain TA100 also responds to these compounds when S9 is present. Performing DNA sequence analysis, other investigators have shown that ABP induces frameshift, base-pair and complex mutations. Also, it was found that an uninduced hamster liver S9 preparation with glucose-6-phosphate dehydrogenase, FMN, NADH and four times glucose 6-phosphate gave a stronger mutagenic response than the conventional plate incorporation with rat S9 activation mixture for all the compounds tested. Using the base-specific tester strains of S. typhimurium (TA7001-TA7006) with the above reductive metabolic activation system, we surveyed these compounds for the ability to produce specific base-pair substitutions after reductive metabolism. Bz was weakly mutagenic in TA7005 (0.04 revertants/microg). ABP was mutagenic in TA7002 (1.4 revertants/microg), TA7004 (0.6 revertants/microg), TA7005 (2.98 revertants/microg) and TA7006 (0.4 revertants/microg). DCBz was weakly mutagenic in TA7004 (0.01 revertants/microg). It was concluded that benzidine induced some CG->AT transversions in addition to frameshift mutations. ABP induced TA->AT, CG->AT, and CG->GC transversions as well as GC->AT transitions. DCBz induced only GC->AT transitions. Because DMBz, DMOBz and TB were not mutagenic in this base-substitution mutagen detection system, their mutagenic activity was attributed strictly to frameshift mechanisms.

A study of 2,4,6-trinitrotoluene inhibition of benzo[a]pyrene uptake and activation in a microbial mutagenicity assay.

A number of in vitro and in vivo studies have determined that binary and complex mixtures may interact to produce a toxicity that could not be predicted based on the individual chemicals. The present study was conducted with a binary mixture of model compounds to investigate possible interactions affecting their mutagenicity. The compounds included Benzo[a]pyrene (BAP), a polycyclic aromatic hydrocarbon that is an indirect-acting mutagen of great environmental concern, and 2,4,6-Trinitrotoluene (TNT), a nitro-aromatic compound that is a direct-acting mutagen frequently found as a soil contaminant at munitions sites. This study indicated that a binary mixture of BAP and TNT failed to induce the positive mutagenic response in Salmonella typhimurium strain TA98 characteristic of either compound alone. Spectrofluorometric analysis of BAP, and kinetic analyses of 3HBAP uptake in the presence or absence of TNT using TA98 cells that were treated or untreated with activated rat liver microsomes were performed. In cells preloaded with BAP, cellular BAP fluorescence was rapidly suppressed in the presence of TNT. Mass spectroscopy of BAP and TNT mixtures revealed a number of products, believed to be the result of complexation and nitration, that may account for the antagonistic action of TNT on BAP-induced mutagenicity in TA98 cells. Further, kinetic studies indicated that TNT inhibited the incorporation of BAP into cells.

A comparative assessment of Boise, Idaho, ambient air fine particle samples using the plate and microsuspension Salmonella mutagenicity assays.

The primary objective of this study is to characterize the genotoxic potential of the ambient air aerosols collected within an air shed impacted primarily by wood smoke and automotive emissions. The study also examines the relative merits of a microsuspension assay and the standard plate assay for monitoring the presence of airborne particle-bound mutagens. Wintertime ambient air particulate samples collected from Boise, Idaho, USA, were shown to contain extractable organic matter that is mutagenic in the Salmonella typhimurium microsuspension and plate-incorporation assays. Differences in the results from the primary sites, auxiliary sites and the background site demonstrate that the particle-bound mutagens are not evenly distributed within the air shed and are more associated with the location of sampling than with the time of sampling or the type of bioassay used to evaluate the samples. This study also demonstrates that the bioassay protocol used in such studies should depend upon the characteristics of the air shed's mutagens and the purpose of the study. For example, the microsuspension assay gave somewhat more variable results between samples but was approximately threefold more sensitive than the plate assay. When strain TA98 was used in the microsuspension assay, the mutagenic response was greater without an exogenous activation system. The reverse was true for the plate assay in which the use of an exogenous activation system increased the mutagenicity response. TA100 in the microsuspension assay provided results comparable to those with TA98. This is important because TA100 can also be used to bioassay semivolatile and volatile organics associated with ambient air mutagenicity. This, in turn, allows a comparison of the mutagenicity of organics collected by differing methods due to their volatility. Future studies should be directed toward correlation of mutagenicity results with other analytical results in order to further develop methods for better characterization of the genotoxicity of ambient air.

Methods for the spiral Salmonella mutagenicity assay including specialized applications.

An automated approach to bacterial mutagenicity testing - the spiral Salmonella assay - was developed to simplify testing and to reduce the labor and materials required to generate dose-responsive mutagenicity information. This document provides the reader with an overview of the spiral assay and a discussion of its application for examining the mutagenic potential of pure compounds, complex environmental mixtures, and interactive effects. Guidelines for performing a routine spiral assay are presented, and alternative test methods intended to overcome a variety of technical difficulties (such as restricted sample availability, sample viscosity or volatility, etc.) are recommended. Methods for the computerized analysis of data and the interpretation of results are discussed.

Mutagenicity in lung of big Blue((R)) mice and induction of tandem-base substitutions in Salmonella by the air pollutant peroxyacetyl nitrate (PAN): predicted formation of intrastrand cross-links.

Peroxyacetyl nitrate (PAN) is a ubiquitous air pollutant formed from NO(2) reacting with acetoxy radicals generated from ambient aldehydes in the presence of sunlight and ozone. It contributes to eye irritation associated with photochemical smog and is present in most urban air. PAN was generated in a chamber containing open petri dishes of Salmonella TA100 (gas-phase exposure). After subtraction of the background mutation spectrum, the spectrum of PAN-induced mutants selected at 3.1-fold above the background mutant yield was 59% GC-->TA, 29% GC-->AT, 2% GC-->CG, and 10% multiple mutations - primarily GG-->TT tandem-base substitutions. Using computational molecular modeling methods, a mechanism was developed for producing this unusual tandem-base substitution. The mechanism depends on the protonation of PAN near the polyanionic DNA to release NO(2)(+) resulting in intrastrand dimer formation. Insertion of AA opposite the dimerized GG would account for the tandem GG-->TT transversions. Nose-only exposure of Big Blue((R)) mice to PAN at 78ppm (near the MTD) was mutagenic at the lacI gene in the lung (mutant frequency +/-S.E. of 6.16+/-0.58/10(5) for controls versus 8.24+/-0.30/10(5) for PAN, P=0.016). No tandem-base mutations were detected among the 40 lacI mutants sequenced. Dosimetry with 3H-PAN showed that 24h after exposure, 3.9% of the radiolabel was in the nasal tissue, and only 0.3% was in the lung. However, based on the molecular modeling considerations, the labeled portion of the molecule would not have been expected to have been bound covalently to DNA. Our results indicate that PAN is weakly mutagenic in the lungs of mice and in Salmonella and that PAN produces a unique signature mutation (a tandem GG-->TT transversion) in Salmonella that is likely due to a GG intrastrand cross-link. Thus, PAN may pose a mutagenic and possible carcinogenic risk to humans, especially at the high concentrations at which it is present in some urban environments.

Comparison of the mutagenic specificity induced by four nitro-group-containing aromatic amines in Salmonella typhimurium his genes.

Four nitrated aromatic amines (2-nitro-p-phenylenediamine [2NPD], 3-nitro-o-phenylenediamine [3NPD], 4-nitro-o-phenylenediamine [4NPD] and 4,4'-dinitro-2-biphenylamine [DNBA]) are direct-acting mutagens in Salmonella typhimurium strain TA100. These compounds were tested further using the Xenometrix strains of S. typhimurium: TA7001, TA7002, TA7003, TA7004, TA7005, and TA7006, with and without S9 mix in the plate incorporation assay. The direct-acting mutagenicity of 2NPD, 4NPD, and DNBA was detected with TA7002, TA7004 and TA7005. 2NPD and DNBA showed some activity in TA7006; DNBA also showed some activity in TA7003. Mutagenicity was generally decreased in these strains when S9 was added. 3NPD was mutagenic in TA7004 without S9 and in TA7005 with and without S9. These data suggest that 2NPD, 4NPD and DNBA induced TA-->AT and CG-->AT transversions as well as GC-->AT transitions in the his gene. 3NPD induced CG-->AT transversions and GC-->AT transitions. 2NPD and DNBA also induced a small portion of CG-->GC transversions.

Genotoxicity of bioremediated soils from the Reilly Tar site, St. Louis Park, Minnesota.

An in vitro approach was used to measure the genotoxicity of creosote-contaminated soil before and after four bioremediation processes. The soil was taken from the Reilly Tar site, a closed Superfund site in Saint Louis Park, Minnesota. The creosote soil was bioremediated in bioslurry, biopile, compost, and land treatment, which were optimized for effective treatment. Mutagenicity profiles of dichloromethane extracts of the five soils were determined in the Spiral technique of the Salmonella assay with seven tester strains. Quantitative mutagenic responses in the plate incorporation technique were then determined in the most sensitive strains, YG1041 and YG1042. Mutagenic potency (revertants per microgram extract) in YG1041 suggested that compost, land treatment, and untreated creosote soil extracts were moderately mutagenic with Arochlor-induced rat liver (S9) but were nonmutagenic without S9. However, the bioslurry extract was strongly mutagenic and the biopile extract was moderately mutagenic either with or without S9. A similar trend was obtained in strain YG1042. The strong mutagenic activity in the bioslurry extract was reduced by 50% in TA98NR, which suggested the presence of mutagenic nitrohydrocarbons. Variation in reproducibility was 15% or less for the bioassay and extraction procedures. Bioavailability of mutagens in the biopile soil was determined with six solvents; water-soluble mutagens accounted for 40% of the total mutagenic activity and they were stable at room temperature. The mutagenic activity in the bioslurry and biopsile samples was due to either the processes themselves or to the added sludge/manure amendments. The in vitro approach was effective in monitoring bioremediated soils for genotoxicity and will be useful in future laboratory and in situ studies.

Bioassay-directed fractionation and chemical identification of mutagens in bioremediated soils.

Soil from a Superfund site (Reilly Tar Site, St. Louis Park, Minnesota) contaminated with polycyclic aromatic hydrocarbons (PAHs) from creosote was treated with several bioremediation technologies including bioslurry (BS), biopile (BP), compost (CMP), and land treatment (LT). These treatment technologies are being evaluated in pilot scale laboratory systems by the U.S. Environmental Protection Agency's National Risk Management Research Laboratory in Cincinnati, Ohio. To evaluate the genotoxicity and identify the mutagens in the soil before and after the various treatments, fractionated extracts of five soils were bioassayed for mutagenic activity with a microsuspension modification of the Salmonella histidine reversion assay. Soils were extracted by sonication using dichloromethane (DCM). The five extracts were fractionated in triplicate (two for bioassay and one for chemical analysis) by reverse-phase high-performance liquid chromatography (HPLC) using hexane/DCM/methanol, and the fraction for bioassay were solvent-exchanged into dimethyl sulfoxide by nitrogen evaporation. Forty HPLC fractions for each sample were bioassayed in strain YG1041 with and without exogenous liver metabolic activation. As shown in a companion paper, the mutagenicity of two treatments (BS and BP) was significantly greater than the mutagenicity of the untreated soil. Mutagenic fractions (> 500 revertants) were analyzed by gas chromatography/mass spectrometry (GC/MS). PAH analysis of the soils indicated that all treatments were effective in reducing the total PAH concentration (48-74%). Qualitative GC/MS analysis of the mutagenic fractions from the BS and BP treatments indicated that they contained azaarenes, which are mutagens. The CMP and LT processes were the most effective and least toxic bioremediation procedures based on mutagenic potency and chemical analysis. This research demonstrated that the combination of bioassays and chemical analysis provided a more accurate determination of toxicity in these complex environmental mixtures.

Mutagenic interactions of model chemical mixtures.

Although current methodology for human health risk assessment assumes additive interactions among the contaminants of a complex mixture, chemical interactions may occur which produce synergistic or antagonistic effects. In this study, the mutagenic response of three f2p4l compounds, benzo(a)pyrene (B(a)P), pentachlorophenol (PCP) and 2,4,6-trinitrotoluene (TNT), were tested individually and in binary and tertiary solutions, using the Salmonella/microsome assay with each of three bacterial tester strains (TA97a, TA98, and TA100). For all strains, B(a)P was mutagenic with metabolic activation (Arochlor 1254-induced Sprague-Dawley rat liver S9 fraction), TNT was mutagenic without metabolic activation, and pentachlorophenol was inactive both with and without metabolic activation. In binary and tertiary solutions, pentachlorophenol had no effect on the mutagenicity of B(a)P or TNT, independent of metabolic activation. For strain TA97a, the mutagenicity of B(a)P with metabolic activation was slightly decreased in the presence of TNT; the mutagenicity of TNT without metabolic activation was slightly decreased in the presence of B(a)P and PCP; and the mutagenicity of the tertiary solution (496 revertants/10 ug) with metabolic activation was lower than the mutagenicity of B(a)P alone (729 revertants/10 ug). The mutagenicity of B(a)P in strain TA98 with activation was inhibited by the addition of TNT. Studies conducted using several concentrations of TNT or B(a)P indicate that the inhibition of B(a)P mutagenicity was increased as the concentration of TNT increased. Assays performed using four concentrations of S9 indicated the inhibition of B(a)P mutagenicity was relatively unaffected by the level of S9. The data suggest that an interaction in the presence of TNT limits the concentration of B(a)P that is capable of reaching or binding with bacterial DNA.

The U.S. EPA Conference on Preventable Causes of Cancer in Children: a research agenda.

On 15-16 September 1997, the U.S. Environmental Protection Agency sponsored the Conference on Preventable Causes of Cancer in Children. The conference was convened to examine rising trends in reported incidence of childhood cancer and the association of these trends with environmental exposures. This paper summarizes recommendations for future research offered by participants. These recommendations included more collaborative research integrating epidemiology, molecular biology, toxicology, and risk assessment; the development of better protocols for toxicologic testing including carcinogenicity using young animals; and research focused on specific periods of development during which susceptibility to environmental agents may be enhanced. Also recommended was enhanced use and development of molecular biomarkers for identification of susceptible populations, and documentation of exposures and effects in epidemiologic and toxicologic studies. Although toxicologic testing is considered essential to determine the effects of potential carcinogens on biological organisms, participants emphasized the need to link these findings with epidemiologic and exposure assessment research.

Genotoxicity of industrial wastes and effluents.

In excess of several million pounds of genotoxic and/or carcinogenic industrial wastes are released into the U.S. environment each year. Chemical characterization of these waste materials can rarely provide an adequate assessment of their genotoxicity and potential hazard. Bioassays do not require prior information about chemical composition and can effectively assess the genotoxicity of complex waste materials. The most commonly used genotoxicity assay has been the Salmonella mutagenicity assay. Results with this system have shown that the genotoxic potency of industrial wastes can vary over 10 orders of magnitude, from virtually nondetectable to highly potent. Industries employing similar industrial processes generally release wastes of similar potency. Extremely high potency wastes include those from furazolidone and nitrofurfural production. Pulp and paper mills, steel foundries, and organic chemical manufacturing facilities also discharge wastes of noteworthy potency. Treatment and remediation of some wastes, such as pulp and paper mill effluents, have been shown to reduce or eliminate genotoxicity. However, in other cases, treatment and remediation have been shown to enhance genotoxicity, such as for fungal treatment of oils. Analyses of samples collected from areas known to receive industrial wastes and effluents have shown that genotoxins can accumulate in the receiving environment and have adverse effects on indigenous biota. The evaluation of hazardous wastes and effluents by genotoxicity assays may provide data useful not only for hazard identification but for comparative risk assessment.

Chemical and mutagenic analysis of volatile organic compounds in Raleigh air samples at three different elevations before, during, and after Hurricane Gordon.

Volatile organic compounds (VOCs) were collected and measured at a television tower 10 km southeast of downtown Raleigh, North Carolina at three different levels (Surface, < 1 m; Mid, 240 m; and Top, 433 m) during the summer and fall of 1994. The combined presence of ozone, arenes, and nitrogen oxides (NOx) suggested possible nitration of arenes during atmospheric mixing. Air samples, therefore, were collected using XAD-filled canisters at each level on the tower prior to, during, and after Hurricane Gordon. Collected air samples were Soxhlet extracted and analyzed with the Salmonella typhimurium microsuspension mutagenicity assay using strains YG1021 and YG1026 which are sensitive to nitrarenes. Significant mutagenicity was observed only in the Top and Mid level samples for the post-hurricane, normal weather air samples. Surface samples were not mutagenic, which suggests the long-range transport of these mutagenic nitrarenes.

Development of a standard reference material for diesel mutagenicity in the Salmonella plate incorporation assay.

The present study documents the mutagenicity of a new National Institute of Standards and Technology (NIST) standard reference material (SRM) in the Salmonella plate incorporation assay. This study is in response to a previous recommendation by the World Health Organization to develop large batches of new SRMs for biological and chemical research. SRM 1975 is a dichloromethane (DCM) extract of 5.6 kg of filter-collected combustion particulate matter (SRM 2975) from operating forklifts with diesel engines. The mutagenicity and a summary of the related chemical analysis of mutagens in SRM 1975 is presented in this paper, and are available from the NIST. Mutagenicity test conditions were: Salmonella typhimurium TA98, TA100 (standard strains); TA98NR, TA100NR (nitroreductase (NR) gene deficient); and YG1021 and YG1026 (NR gene addition); 10 dose levels in the linear portion of the dose-response curve; duplicate plates per dose; and S9 at 6.4% or 1.1 mg of protein/plate. Four rounds of testing were conducted. Rounds were conducted at least 1 week apart. Slopes (revertants/microg) were calculated by the linear regression rejection model of Bernstein and by the Stead and Krewski models which analyze non-linear data. The GeneTox Manager software package developed at the EPA was used to record the data and calculate the slopes. Results demonstrated: (1) the ranking of slopes without S9 was: YG1021 > TA98 > TA98NR > YG1026 > TA100 > TA100NR in all three statistical models; (2) the mutagenic activity of SRM 1975 was significantly increased by the presence of the NR gene; (3) the slope values for the TA100 series were significantly less than for the TA98 series; (4) in general, the addition of the S9 significantly reduced mutagenic activity; (5) the mutagenic activity of the SRM 1975 was stable over time and variability was low (generally less than 20% in slope values over the 4 rounds); and (6) agreement of the slope values among the three models was excellent due to the linear nature of the data. These data will be useful in ranking other diesel and air samples for mutagenic activity, for quality assurance of data generated in different laboratories, for quality control within a laboratory, and as positive control values for future air and automotive emission studies.

Glutathione S-transferase-mediated mutagenicity of trihalomethanes in Salmonella typhimurium: contrasting results with bromodichloromethane off chloroform.

Trihalomethanes (THMs) are the most prevalent disinfection by-products identified in chlorinated drinking water. Among the THMs, chloroform (CHCl3) generally occurs at the highest concentration in finished water, but the concentrations of each of the brominated THMs (CHBrCl2, CHBr2Cl, and CHBr3) can exceed that of CHCl3. Each of these four THMs was carcinogenic in rodents in chronic oral dosing studies. This study assessed THM mutagenicity in a strain of Salmonella typhimurium TA1535 that was transfected with rat theta-class glutathione S-transferase T1-1 (+GST). The +GST strain and its nontransfected parent strain (-GST) were employed in a plate-incorporation assay and exposed for 24 hr to the vapor of individual THMs at concentrations up to 25,600 ppm in sealed Tedlar bags. Base-substitution revertants were produced in the +GST strain in a dose-dependent fashion by CHBrCl2 but not by CHCl3. At 4800 ppm CHBrCl2, which produced a calculated agar concentration of 0.67 mM, there were 419 +/- 75 revertants per plate compared to a spontaneous level of 23 +/- 5. CHCl3 produced a doubling of revertants only at the two highest concentrations tested (19,200 and 25,600 ppm). These results indicate that bromination of THMs confers the capability for theta-class GST-mediated transformation to mutagenic intermediates at low substrate concentrations, suggesting the possibility of a similar activation route in humans. Further, the very low affinity of the GSH-dependent pathway for CHCl3 demonstrates that different THMs can induce adverse effects via different mechanisms, indicating that risk evaluations of THMs should not treat members of this class as if they shared a common mode of action.

Isolation and characterization of an attenuated strain of Pseudomonas aeruginosa AC869, a 3,5-dichlorobenzoate degrader.

Pseudomonas aeruginosa AC869, a 3,5-dichlorobenzoate degrader, is a mouse pathogen and has a reported 50% lethal dose (LD50) of 1.05 x 10(7) CFU when given intranasally to C3H/HeJ mice (S.E. George, M.J. Kohan, M.I. Gilmour, M.S. Taylor, H.G. Brooks, J.P. Creason, and L.D. Claxton, Appl. Environ, Microbiol. 59:3585-3591, 1993). AC869 was serotyped as O6 when grown in CD-1 mouse cecal and lung mucus but could not be assigned an O serotype when grown in Luria broth (LB). After growth in mouse cecal mucus, a less virulent mutant, AC869-11, was isolated from AC869 by using bacteriophage E79, which adsorbs to the O side chain of lipopolysaccharide (LPS). AC869-11 produced significantly less O antigen on its LPS than AC869 when grown in mouse lung and cecal mucus. The mutant also produced half the amount of exoenzyme S and 16-fold less extracellular protease than AC869 and was more sensitive than its parent to a number of antibiotics when grown either in LB or in mouse lung mucus. AC869-11 had ninefold higher LD50 than AC869 in CD-1 mice when administered intranasally. AC869-11 was found in the lungs, small intestine, cecum, and large intestine in numbers at least 100-fold below AC869, 3 h after intranasal exposure of mice to a sublethal dose of the two strains. Moreover, AC869-11 induced a decreased pulmonary inflammatory response relative to AC869. In contrast to AC869, AC869-11 did not translocate to the mesenteric lymph nodes, liver, and spleen following a sublethal dose. Despite attenuation, AC869-11 grew as well as AC869 with 3,5-dichlorobenzoate as the sole carbon and energy source. However, although AC869-11 survived in 3,5-dichlorobenzoate-contaminated soil as well as AC869 for 1 week, it failed to survive as well thereafter. These results suggest the possibility that mutations that lead to pulmonary attenuation of P. aeruginosa in mice also lead to weakness in the environment, despite such mutants maintaining the ability to degrade toxic substances under laboratory conditions.

Changes in mutagenicity during crude oil degradation by fungi.

Two fungal strains, Cunninghamella elegans and Penicillium zonatum, that grow with crude oil as a sole carbon source were exposed to three crude oils that exhibit a range of mutagenic activity. At regular time intervals following fungal incubation with the various crude oils, extracts were tested for the presence of mutagenic activity using the spiral Salmonella assay. When the most mutagenic of the oils, Pennsylvania crude oil, was degraded by C. elegans or by P. zonatum, its mutagenicity was significantly reduced; corresponding uninoculated (weathered) controls of Pennsylvania crude remained mutagenic. West Texas Sour crude oil, a moderately mutagenic oil, exhibited little change in mutagenicity when incubated with either C. elegans or P. zonatum. Swanson River Field crude oil from Cook Inlet, Alaska is a slightly mutagenic oil that became more mutagenic when incubated with C. elegans; weathered controls of this oil showed little change in mutagenicity. Mycelial mat weights measured during growth on crude oils increased corresponding to the biodegradation of about 25% of the crude oil.

GeneTox manager for bacterial mutagenicity assays: a personal computer and minicomputer system.

GeneTox Manager (GTM) is a data capture, data management, and statistical analysis program used for microbial mutagenicity data. Its main purpose is to provide a homogeneous environment for the collection, organization, and analysis of data generated in the laboratory while also supporting a quality assurance program. The complete system consists of both a personal computer (PC) system and a minicomputer (VAX) system. The joint PC/VAX version of the system is designed to function with both the PC and VAX FOCUS databases so that the VAX can be used for long-term storage, archiving of files, and the analysis of large groups of data. Because of the highly specialized use and nature of the PC/VAX version, this discussion is focused upon the PC stand-alone version. The user-friendly system uses a structured menu system, screen entry helps, and other help screens. GTM provides tabular and graphical summaries of the data and performs specialized statistical analyses. This public domain software was written primarily using Clipper. The manuals and programs are now available through the government's National Technical Information Service.

Pulmonary clearance and inflammatory response in C3H/HeJ mice after intranasal exposure to Pseudomonas spp.

The environmental release of engineered microorganisms has caused health and environmental concerns. In this study, an animal model was used to examine health effects following pulmonary exposure to environmental and clinical isolates. In order to rule out the possibility that an adverse response was caused by endotoxin, 50% lethal doses (LD50) were determined, when possible, with endotoxin-sensitive (C3HeB/FeJ) and endotoxin-resistant (C3H/HeJ) mice by using both environmental isolates (Pseudomonas aeruginosa BC16, BC17, BC18, and AC869 and Pseudomonas maltophilia BC6) and clinical isolates (P. aeruginosa PAO1 and DG1). The LD50 of strains AC869, DG1, and PAO1 are 1.05 x 10(7), 6.56 x 10(6), and 1.02 x 10(7) CFU, respectively, in C3HeB/FeJ mice and 1.05 x 10(7), 1.00 x 10(7), and 2.75 x 10(6) CFU, respectively, in C3H/HeJ mice. Strains BC17 and BC18 were not lethal to the animals. On the basis of the LD50 data, an appropriate sublethal dose (approximately 10(6) CFU) was selected. Animals were challenged intranasally with microorganisms, and clearance from the lungs and nasal cavity was determined. Strains BC17, BC18, and AC869 were not detected in lungs or nasal washes 14 days following treatment. Strains BC6, BC16, and DG1 were recovered from the nasal cavities at the end of the experiment. Only strain PAO1 was detected in lungs and in nasal cavities 14 days after treatment. At selected intervals following treatment, the percentages of polymorphonuclear leukocytes and lymphocytes in bronchoalveolar lavage samples were determined. P. aeruginosa AC869, PAO1, and DG1 elicited a relatively strong inflammatory response which was indirectly related to lung clearance.(ABSTRACT TRUNCATED AT 250 WORDS)