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Ornithine decarboxylase (ODC) activity is used widely as a biomarker for tumor promotion in animal model systems. Several previous studies have reported increases in ODC activity in tissues of rats exposed to 60 Hz magnetic fields. The goals of this study were to confirm these findings and to determine whether ODC activity is increased in tissues of animals exposed to magnetic fields containing complex metrics. Three experiments were conducted in male F344 rats. Each study included a sham control group and a group exposed to pure continuous 60 Hz fields (0.2 mT). Additional groups included animals exposed to randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT); intermittent 60 Hz fields (2 mT) with on-off cycles ranging from 5 s to 5 min; pure continuous 180 Hz fields (2 mT); 60 Hz fields with a superimposed 3rd harmonic (total field strength, 2 mT); 60 Hz fields with superimposed third, fifth, and seventh harmonics (total field strength, 2 mT); 60 Hz fields (2 mT) with superimposed transients; and randomly time-varying 60 Hz fields (range of 0.02 to 0.2 mT) with superimposed transients. After 4 weeks of exposure (18.5 h/day), eight animals per group were euthanized within 1 h of magnetic field deactivation. Homogenates of liver, kidneys, spleen, and brain were prepared from each animal, quick-frozen, and shipped for analysis by four independent laboratories. No consistent pattern of differences in the ODC activity among experimental groups was found either within a laboratory or among laboratories. The results do not support the hypothesis that exposure to extremely low frequency magnetic fields stimulates ODC activity.

It was recently reported that low blood lead levels impaired kidney function in men. To develop a set of molecular markers of renal lead exposure and effect, we investigated changes in renal protein expression while approximating occupational lead exposure at subchronic, low blood levels. Lead was administered to male Dutch Belted rabbits as a lead acetate solution adjusted weekly to achieve and maintain the target blood lead levels of 0, 20, 40, and 80 microg/dL for 15 weeks. Lead exposure did not affect kidney or body weights. The effect of increasing blood lead on protein expression was evaluated in rabbit kidney by large-scale two-dimensional electrophoresis (2-DE). Significant quantitative changes (p0.05) occurred in a dose-related manner in 12 proteins at 20 microg/dL exposure, 25 at 40 microg/dL, and 102 at 80 microg/dL. At a higher level of significance (p0.001), 40 microg/dL blood lead resulted in one protein alteration and 80 microg/dL affected 14 proteins. A set of quantitatively altered charge variants was tentatively identified as glutathione-S-transferase (GST), based on similar observations in rodents subjected to short-term, very high lead exposure. The significance of the protein alterations observed as markers of toxicity awaits their conclusive identification. Investigation of the kidney 2-DE profile in lead-exposed rabbit may be useful in understanding the mechanism of lead nephrotoxicity in humans.

Alterations of the phosphorylation pattern of histones by the carcinogen, 4,4'-methylene-bis(2-chloroaniline) (MOCA) were investigated using rodent spleen cells. Spleen cells were isolated from Sprague-Dawley rats and treated with either 5, 10, 25, or 50 microM MOCA or acetone vehicle controls for 1, 2, 4, or 8 hours. Cells were incubated with 32P-phosphoric acid, and histones from these cells were fractionated utilizing two-dimensional polyacrylamide gel electrophoresis. Marked stimulation of histone phosphorylation was observed with the 10 microM MOCA treatment. A transient decrease in histone phosphorylation was observed at the 1 and 2 hour time points followed by a marked stimulation at 4 hours.

Epidemiological evidence that occupational exposure to o-toluidine and aniline is associated with an increased risk of bladder cancer led to efforts to identify biomarkers of workplace exposures to these aromatic amines. For the determination of o-toluidine and aniline in worker urine specimens, a method using high performance liquid chromatography (HPLC) followed by electrochemical detection was developed. The limits of detection were 0.6 microgram/l and 1.4 micrograms/l for o-toluidine and aniline, respectively. Recovery of o-toluidine and aniline from spiked urine averaged 86% and 93%, respectively, over a range of 4-100 micrograms/l. Reproducibility in the range 2-100 micrograms/l for analyses of split field samples was 13% (average RSD) for o-toluidine and 16% (average RSD) for aniline. Application of this method to pre- and post-shift samples collected from potentially exposed and unexposed workers indicated elevated concentrations of o-toluidine and aniline in urine from exposed workers. To develop methods for biomarkers of internal dose, o-toluidine binding to the blood proteins hemoglobin and albumin was investigated utilizing in-vivo (rodent) and in-vitro (hemoglobin and albumin) studies. Base-hydrolyzable protein adducts were analyzed by HPLC (fluorescence) and/or GC/electron capture (EC). The methods were compared for sample preparation requirements, selectivity and sensitivity. While the GC/EC method was more sensitive than HPLC, the presence of interfering peaks limited the utility of this approach. Results from these studies suggested that the HPLC method could be useful for determination of o-toluidine exposures in individuals acutely or chronically exposed to high levels.

The macromolecular binding of 4,4'-methylenebis(2-chloroaniline) (MOCA), a suspect human carcinogen, was studied in the adult male Sprague-Dawley rat after both oral and dermal administration. Rats were euthanized 1, 3, 7, 10, 14, and 29 days after a single 281 mumol/kg body wt dose of [14C]MOCA (oral, 213 muCi/kg; dermal, 904 muCi/kg). DNA from various tissues and hemoglobin were isolated for determination of the time course of MOCA macromolecular binding. After oral administration adduct formation was rapid with maximum levels appearing at 24 hr. The 24-hr covalent binding associated with the globin was 7.84 pmol/mg globin (t1/2 = 14.3 days). More extensive 24-hr covalent binding was detected for liver DNA with 49.11 pmol/mg DNA (t1/2 = 11.1 days). After dermal administration of MOCA the major portion of the dose, 86.2%, remained at the application site throughout the study. For these rats the 24-hr covalent binding determined for liver DNA was 0.38 pmol/mg DNA (t1/2 = 15.6 days). Although lower levels were detected after dermal application, similar stability of MOCA-DNA adducts indicates that quantification of such MOCA adducts may be useful for the long-term industrial biomonitoring of MOCA exposure and for the evaluation of human DNA-MOCA adduct formation, a lesion thought to be associated with the production of cancer.

Allium roots grown in C14-thymidine and H3-thymidine media were treated with N hydrochloric acid at 60°C. as in standard Feulgen hydrolysis. The retention of the radioactive thymidine in DNA as a function of hydrolysis time was studied autoradiographically. No significant loss of label was detected until hydrolysis was extended beyond the optimal time for Feulgen staining. The data are consistent with the assumption that there is no significant loss of DNA during normal Feulgen hydrolysis in the material used.

The chloroform mediated refractory state against ornithine decarboxylase induction in male and female rat liver was further studied. One aspect of the investigation was to determine the duration of the induced refractory period while the other component focused on the extent to which the inhibitory effect was dependent upon the concentration of the first dose. When the dosing interval between the first and second dose was varied from 1 to 31 days, the magnitude of the resistance to further stimulation by chloroform only decreased gradually. In studies where the concentration of the first dose was varied while the dosing interval was fixed, it was concluded that the extent of the inhibitory effect was dependent upon the concentration of the first dose.

Ornithine decarboxylase (ODC) in rat liver was separated into two species by DEAE-Sepharose CL-6B column chromatography. The activity of both species of ODC was increased at least 20-fold by chloroform treatment of the rats. The major species, Peak A, contained 65% of the ODC activity and possessed a half-life of 11 min. The second species, Peak B, accounted for 35% of the activity and possessed a half-life of 50 min. The long-lived species of ODC activity, induced in rat liver by chloroform, has not been reported previously and might be related to the prolonged induction of ODC activity by chloroform and to tumor promotion and growth.

Rat liver derived from animals receiving phenobarbital (80 mg/kg intraperitoneally) exhibited an increase in the cytoplasmic concentration of radioactive amino acid (initially injected as arginine) as early as 1 hour after the injection. This increase in uptake resulted in an unequal distribution of the radioactivity between the cytoplasmic and nuclear compartments; while other organelles retained their normal (per cent) allotment of the radioactivity. The cytoplasmic and nucleoplasmic protein profiles from gel chromatography show quantitative changes that may be due to increased synthesis and migration of a cytoplasmic protein to the nucleus where its nuclear function remains to be examined more thoroughly.

An enzymatic activity that hydrolyzes O,O-diisoproplyphosphofluoridate (DFP) and O-1,2,2-trimethylpropylmethylphosphonofluoridate (Soman) was discovered in the ciliate protozoan Tetrahymena thermophila. The enzymatic activity classifies the protein as Mazur-type similar to that found in hog kidney and Escherichia coli. The rate of hydrolysis of Soman by the Tetrahymena-extract is the highest, on a per gram of extract basis, of any eucaryote. The molecular weight is approximately 75,400 as determined by Sephacryl column chromatography. A maximum fifteen-fold purification has been achieved. Potential exists for the detoxification and one-step detection of common organofluorophosphate pollutants. Additionally, Tetrahymena should prove an easier subject for manipulation than mammalian or squid sources. Protozoa may be a potentially important source of detoxification and degradation enzymes for other environmental contaminants.

We have previously reported that chloroform is a very potent stimulator of rat hepatic Ornithine Decarboxylase (ODC) activity. At that time we conducted the obligatory time course and dose response studies in male and female rats. However, in an attempt to more thoroughly understand the mechanism of this stimulation, we have examined the effects of a series of pharmacologic, physiologic and toxicologic manipulations on the chloroform response. These studies involved: in vivo experiments in which animals were pretreated with compounds known to effect the various physiological systems and then challenged with chloroform and in vitro experiments in which chloroform was added to the incubation media with/without the compound of interest. The results did not allow the assignment of a specific effect of any of the manipulations to the mechanism of the chloroform response, although much data of significant interest evolved.

1. Mytilicola intestindlis (Steuer) was found in 100% of mussels examined from Blyth, Northumberland. These mussels varied in length between 3·5 and 7·5 cm.2. The degree of infestation varied from two to fifty-nine parasites per mussel.3. There was an inverse relationship between the condition of mussels of the size group 5·5–5·9 cm. and both the mean number of parasites per mussel and the mean number of parasites over 1·5 mm. in length per mussel.4. The mean weight of flesh per mussel in the size group 5·5–5·9 cm. (shell length) was 3·206 g. from Blyth (parasitized) and 5·975 g. from Conway (not parasitized).5. It is concluded that the presence of Mytilicola is associated with a serious reduction of condition in infested mussels.

SummaryA virus was recovered from throat materials of a chimpanzee with coryza during an epizootic of respiratory disease in a colony of these animals. The new agent produced degenerative changes in tissue culture, but was not pathogenic for common laboratory animals. The donor chimpanzee as well as other chimpanzees involved in the epizootic developed specific antibodies against the coryza agent during the months following the outbreak. Susceptible chimpanzees following intranasal instillation of tissue culture materials infected with the coryza agent developed clinical coryza and subsequently made specific antibody. A presumptive etiologic association was established between the new agent and respiratory illness in a laboratory worker, but has not been implicated in the illnesses of small groups of patients with several common types of respiratory disease. However, a number of human beings, particularly adolescents and young adults, have antibodies in their sera directed against the coryza agent suggest...