Biologically based validation of PC electrophysiology data collection systems utilizing the Good Automated Laboratory Practices.

Since there was a scientific need to conduct electrophysiology measurements to detect possible ocular (electroretinography, ERG), central neurotoxic (quantitative electroencephalography, qEEG), and cardiac (electrocardiography, ECG) effects in animals used in certain regulatory studies, the acquisition of suitable automated PC software systems were required. This article describes the process by which these systems were validated to ensure that they met the scientific requirements, while also addressing the principles of Good Automated Laboratory Practices (GALP). After a thorough search of existing commercial packages, a plan was developed specific for each PC-based collection system selected for evaluation. The common elements of each plan included consideration of both scientific and GALP elements, such as necessary biological response variables, raw data acquisition and identification, acceptance criteria, security, protection, storage media, data integrity, audit requirements and standard operating procedures. The authors' approach to validation for each electrophysiology system was to determine scientific needs for accuracy, precision, and detection limit of biological effects concurrent with GALP requirements. The selected software systems were employed in separate scientific GLP studies conducted in dogs, rats, and mini-pigs to demonstrate the ability to detect cholinesterase effects due to multiple infusions of physostigmine, based on parallel measurement of cholinesterase biomarkers. Since the systems were designed for human usage, certain adaptations were necessary. A critical assumption to be tested was the ability of the system's algorithms to adequately capture and assimilate the data in an accurate fashion. Concomitantly, the related GALP needs, such as data integrity, security, CD-ROM archive, and personnel training requirements were evaluated, implemented, and defined to accommodate the application and process needs. The biological approach to validation of these PC-based electrophysiology systems met the necessary scientific acceptance criteria as well as compliance requirements in order to be used in regulatory studies.

Tumor initiation and promotion effects of petroleum streams in mouse skin.

A furnace oil, a dewaxed heavy paraffinic distillate, and a solvent-extracted lubricant base oil induced skin tumors in 9/43, 26/48, and 1/47 male C3H mice, respectively, during lifetime skin-painting bioassays. An initiation/promotion (I/P) bioassay was conducted to assess the I/P potential of these materials. During a 28-week initiation bioassay, groups of 30 male CD-1 mice were first treated dermally once daily for 5 days with 25 or 50 microliter of test materials or 50 microliter of acetone, rested for 2 weeks, then treated twice per week for 25 weeks with 50 microliter (0.1 mg/ml) phorbol-12-myristate-13-acetate (PMA). Only groups treated with the heavy paraffinic distillate had a significantly higher incidence of papillomas relative to the acetone control group. During a 28-week promotion bioassay, groups of 30 male CD-1 mice were treated once with 50 microliter of either DMBA (1.0 mg/ml) or acetone, rested for 2 weeks, and then treated twice per week with test material for the remaining 25 weeks. The furnace oil and dewaxed heavy paraffinic distillate showed significantly higher incidences of carcinomas and papillomas in DMBA-initiated mice relative to their acetone-initiated controls. Together these bioassay data suggest that only the dewaxed heavy paraffinic distillate is a complete carcinogen, having both initiating and promoting activity; furnace oil is a promoter only, while the solvent-extracted lubricating oil is noncarcinogenic. Overall, the I/P bioassay correlated well with the results of the lifetime skin-painting bioassay.

Two-year inhalation toxicity study of petroleum coke in rats and monkeys.

Sprague-Dawley rats and Cynomolgus monkeys were exposed to dust aerosol concentrations (0, 10.2, and 30.7 mg/m3) of micronized delayed process petroleum coke for 6 hr/day, 5 days/week over 2 years. With the exception of pulmonary effects, particularly in the rats, no significant adverse treatment-related effects were observed. Both dust-exposed groups of both species exhibited a gray to black discoloration of the lung, an observation consistent with pulmonary deposition of the coke dust, as well as increased absolute and/or relative lung weight values. The pulmonary histopathology in the monkeys was limited to the deposition and phagocytosis of the test material by pulmonary macrophages. The rats also exhibited these responses, but with concomitant signs of chronic inflammation and focal areas of fibrosis, bronchiolization, sclerosis, squamous alveolar metaplasia, and keratin cyst formation. No difference in the mortality rate was observed between the control and exposed groups of rats. Lastly, no significant increases in chromosomal aberrations were observed in rodents of the 10.2 or 30.7 mg/m3 exposure groups when examined after 5 days, 12 months, and 22 months of exposure.

Absence of hydrocarbon-induced nephropathy in rats exposed subchronically to volatile hydrocarbon mixtures pertinent to gasoline.

Ninety-day inhalation studies were conducted on 50:50 weight percent (wt %) mixtures of n-butane:n-pentane and isobutane:isopentane, respectively, and on a distillation cut boiling below 145 degrees F of a reference unleaded gasoline blend to assess the nephrotoxicity of these volatile mixtures. The mixtures of butanes and pentanes were selected because these four hydrocarbons are the most prevalent components of gasoline vapors encountered under typical occupational exposures. The 0-145 degrees F gasoline distillation fraction was tested because it reasonably approximates the composition of gasoline vapors measured under occupational settings. Male and female F-344 rats were exposed to 2 levels of each mixture, 6 hours per day, 5 days per week, for 13 weeks. The target concentrations for the butane:pentane mixtures were 4500 and 1000 parts per million (ppm), while 5200 and 1200 ppm were set for the gasoline distillation fraction. An interim sacrifice was conducted after 28 days. The rats were not significantly affected by the exposures, and there was no evidence of hydrocarbon-induced nephropathy in either sex at the termination of each study. However, at the 28-day interim sacrifice period for both butane:pentane mixtures, mild, transient treatment-related but not exposure-related kidney effects were observed in the male rats. These perturbations were absent at the interim sacrifice period for the gasoline distillation fraction.

Gasoline vapor exposures. Part I. Characterization of workplace exposures.

Monitoring surveys of gasoline vapor exposures were conducted on truck drivers and terminal operators from five terminal loading facilities, on dockmen and seamen at two tanker/barge loading facilities, and on attendants at a single expressway service plaza. Results revealed wide variations in total C6+ hydrocarbon exposures for each location, with overall 8-hr time-weighted averaged (TWA) geometric means of 5.7 mg/m3 (1.4 ppm) for the terminals, and 4.0 mg/m3 (1.0 ppm) for the service plaza, respectively. The exposures ranged from 0.8 to 120.8 mg/m3 (0.2-30.1 ppm) for the terminals, and from 1.1 to 130.3 mg/m3 (0.3-32.5 ppm) for the service plaza. For the terminals, exposures were not significantly different regardless of loading method or the presence or absence of vapor recovery systems. Comprehensive chemical analyses of terminal employee exposure samples revealed that the C4 and C5 hydrocarbon components constituted 74.8 +/- 9.2% of the total exposure sample on a microgram/sample basis. The C6, C7, and C8+ components constituted 13.0 +/- 1.9, 6.2 +/- 3.0, and 5.9 +/- 7.2% of the total samples, respectively. Comprehensive analyses of the marine employee exposure samples resulted in a similar distribution of components; that is, 66.6 +/- 7.9, 17.5 +/- 4.7, 9.2 +/- 3.1, and 6.4 +/- 1.9% for the C4/C5, C6, C7, and C8+ components, respectively. The composition of the exposures, however, was weighted more toward the C5, C6 and C7 components when compared to the bulk terminal employee exposures.(ABSTRACT TRUNCATED AT 250 WORDS)

Gasoline vapor exposures. Part II. Evaluation of the nephrotoxicity of the major C4/C5 hydrocarbon components.

Analysis of workplace exposures to gasoline vapors revealed that C4 and C5 hydrocarbons constitute anywhere from 67 to 74% by weight of a typical vapor. Furthermore, it was found that n-butane, isobutane, n-pentane, and isopentane together comprise greater than 90% of all the C4/C5 vapor components and approximately 61 to 67% by weight of the total vapor. Accordingly, a 21-day inhalation toxicity study of a blend consisting of 25% (w/w) each of these four hydrocarbons was conducted using rats to assess the potential for these major gasoline vapor components to induce kidney damage. No evidence of the kidney lesions typically associated with hydrocarbon-induced nephropathy was observed in rats exposed at up to 11 800 mg/m3 (4437 ppm) of the blend.

Hydrocarbon nephropathy in male rats: identification of the nephrotoxic components of unleaded gasoline.

Previous subchronic and/or chronic inhalation studies of unleaded gasoline and a variety of petroleum naphthas, solvents, and distillates have shown that these complex materials are capable of inducing a distinctive nephropathy which appears limited to male rats. Therefore a series of gavage screening studies using male F-344 rats was conducted on components of gasoline to more clearly identify the major contributors to this nephrotoxicity. The dosing regimen consisted of 20 doses administered once daily, 5 days per wk for 4 wk. Tested were 15 pure hydrocarbon compounds typically found in unleaded gasoline boiling range, 4 naphtha streams representative of those commonly used to blend gasolines and 3 distillation fractions covering the less volatile portions of gasoline. The results revealed that the alkane (paraffin) components were primarily responsible for the nephrotoxic activity seen in unleaded gasoline, with a positive structure-activity response relating the degree of alkane branching to the potency of the nephrotoxic response. In addition, the nephrotoxic activity observed with the naphtha streams and distillation fraction correlated well with the proportion of branched alkanes contained in each.

Carcinogenicity of petroleum lubricating oil distillates: effects of solvent refining, hydroprocessing, and blending.

Certain refining processes were investigated to determine their influence on the dermal carcinogenic activity of petroleum-derived lubricating oil distillates. Specifically, the effects of solvent refining, hydroprocessing, a combination of both processes, and the blending of oils processed using each technique were evaluated in standard mouse skin-painting bioassays. The refining process used as well as the level or severity of treatment greatly influenced the carcinogenic outcome of processed lubricating oils. Solvent refining at severities normally used appeared to eliminate carcinogenicity. In contrast, hydroprocessing alone at mild levels of treatment was successful only in reducing the carcinogenic potency; severe hydroprocessing conditions were necessary to eliminate carcinogenic activity without the use of additional refining processes. Carcinogenic activity could also be eliminated by following moderate solvent refining with mild hydroprocessing. Blending of hydroprocessed oils with solvent-refined oils resulted in a substantial reduction or even elimination of carcinogenic activity. However, the degree of protection obtained varied with the particular distillates used and appeared largely dependent on the inherent biological activity of the hydroprocessed oil.

Absence of sporidesmin production by twelve Texas isolates of Pithomyces spp.

Twelve isolates of Pithomyces spp. from Texas were tested for sporidesmin toxin production, using both high-performance and thin-layer chromatography techniques. None of the Texas isolates produced the toxin under the conditions used. A control toxigenic New Zealand isolate, Pithomyces chartarum strain C, was grown simultaneously under the conditions tested and was found to produce sporidesmin in all cases.