Evaluation of the iVET® birth monitoring system in primiparous dairy heifers.

The objective was to validate the iVET® birth monitoring system and to determine if it reduced fetal death in primiparous dairy heifers over a 1-y interval. There were 359 pregnant heifers enrolled; 167 heifers in the iVET® group were monitored electronically and the remaining 192 (controls) were monitored visually for onset of Stage 2 labor, according to routine farm management. In addition, as a reference, all heifers were observed throughout the study by two independent investigators. Calves born dead or that died within 24 h after birth were defined as stillborn. The interval from appearance of the chorioallantoic sac to recognition of onset of calving in the control group averaged 21 min longer than the iVET® signal (p = 0.0001) and rate of fetal death was numerically lower in the iVET® group (8.9%) than in the control group (10.4%, p = 0.65). Interestingly, dystocia occurred more often in the iVET® group (58.3%) than in the control group (40.9%, p = 0.001). The iVET® system detected onset of Stage 2 labor earlier than conventional monitoring by farm staff. However, the device was lacking in several aspects and should be improved before its use in primiparous heifers can be recommended.

Refining the risk assessment of metal-contaminated soils.

Determining the bioavailability of toxic metals (Pb, As, and Cd) in a diverse range of soils, allows scientifically derived data to dictate site-specific remedies to reduce the risk for sensitive human populations. Based on a series of dosing trials in a juvenile swine model, site-specific estimates of relative bioavailability of Pb in soil ranged from 3% to 86% compared to soluble lead acetate. Another experiment using a pregnant swine model revealed: 1) Pb accumulation in fetal tissues was 50% or more of maternal and; 2) pregnant females accumulated 2-to-4 times more lead in tissues than unbred females. Relative bioavailability results for arsenic- and cadmium-contaminated soils further support the view that soil metals are not always as well absorbed as soluble forms, therefore use of default toxicity factors for assessing human health risk may overestimate the hazard.

Bioavailability of lead to juvenile swine dosed with soil from the Smuggler Mountain NPL Site of Aspen, Colorado.

Bioavailability of lead (Pb) has become an issue in quantifying exposure of sensitive populations and, where necessary, establishing cleanup levels for contaminated soil. Immature swine were used as a model for young children to estimate the degree to which Pb from two fully characterized composite samples from the Smuggler Mountain Superfund Site in Aspen, Colorado may be bioavailable to resident children. The composite soils contained 14,200 and 3870 micrograms Pb/g of soil. Relative and absolute enteric bioavailabilities of Pb in soil (oral dose groups of 75,225, and 675 micrograms Pb/kg body wt/day) were estimated by comparison with an orally administered soluble Pb salt (lead acetate = PbAc2.3H2O) (dose groups of 0, 75, and 225 micrograms Pb/kg body wt/day) and an intravenously administered aqueous solution of Pb (100 micrograms Pb/kg/ day) from the same trihydrate salt administered daily for 15 days to 50 juvenile swine. The biological responses (area under the blood Pb concentration-time curve, and the terminal liver-, kidney-, and bone-lead concentrations) produced by Pb from PbAc2.3H2O and lead-contaminated soils were determined. This study revealed Pb from soil containing 14,200 micrograms Pb/g of soil had a bioavailability relative to Pb from PbAc (RBA), ranging from 56% based on the area under the blood lead concentration-time curve (AUC) versus dose, to 86% based on calculations from liver-Pb loading versus dose. Similarly, Pb from soil containing 3870 micrograms Pb/g of soil had an RBA ranging from 58% based on the AUC versus dose, to 74% based on calculations from liver- and kidney-Pb loading versus dose. Bioavailability of Pb in soils may be more or less than EPA's default RBA of 60%, therefore, measuring site-specific RBAs provides a basis for improved exposure and risk assessment.

Hypersensitivity reactions and specific antibodies in workers exposed to industrial enzymes at a biotechnology plant.

Thirty-six employees who produced industrial enzymes from selected strains of bacteria and fungi were evaluated by epicutaneous threshold testing and enzyme-linked immunosorbent assays (ELISA) for specific IgE and IgG antibodies. The workers complained of 'asthma- and flu-like' symptoms, which generally lessened away from work. The enzymes evaluated were: alpha-amylase (1,4-alpha-d-glucan glucanohydrolase) from Bacillus licheniformis (alpha ABl), B. subtilis formation 1 (alpha A1Bs) and B. subtilis formation 2 (alpha A2Bs); purified alpha-amylase from B. licheniformis (C alpha ABl) and A. oryzae (C alpha AAo); alkaline protease from B. licheniformis (APBl) and purified alkaline protease (CAPBl); amyloglucosidase (1,4-alpha-d-glucan glucohydrolase) from A. niger (AGAn) and purified amyloglucosidase (CAGAn). Statistically significant increases (P > 0.05) in the proportion of workers having positive skin tests to CAPBl, AGAn and CAGAn were found. Significantly elevated (P > 0.05) mean specific IgE results were observed for C alpha AAo CAGAn and AGAn, and elevated (P > 0.05) mean specific IgGs were observed for C alpha AAo, CAGAn, AGAn, alpha A1Bs, alpha AB1 and alpha A2Bs. These results indicate that occupational exposure to some industrial enzymes can cause immediate-onset cutaneous hypersensitivity reactions, pulmonary function deficits and significantly elevated specific antibody levels. Our results are equivocal as to whether work-related respiratory and cutaneous hypersensitivity reactions are antibody mediated, as there was no statistically significant association between these reactions and specific IgE or IgG levels.

Sequential ultrastructural and biochemical changes induced by microcystin-LR in isolated perfused rat livers.

The cyanobacterial hepatotoxin, microcystin-LR (MCLR), is a potent protein phosphatase inhibitor that disrupts actin microfilament, cytokeratin intermediate filament, and microtubule networks in hepatocytes. To determine ultrastructural and biochemical changes that develop concurrently with microcystin-induced cytoskeletal disorganization, isolated rat livers were perfused with MCLR at 0.1 to 5.0 micrograms/ml for 5 to 40 min. Lactate dehydrogenase, alanine aminotransferase, and aspartate aminotransferase changed over time, but trends for toxin-treated and control livers did not differ. The earliest toxin-induced ultrastructural changes, observed in livers perfused at 0.1 microgram/ml for 15-20 min or at 0.3 microgram/ml for 5-10 min, were loss of hepatocyte microvilli in the space of Disse, widening of sinusoidal fenestrae, disruption of sinusoidal endothelium, dilation of bile canaliculi with loss of microvilli, and widening of hepatocyte intercellular spaces. Lesions progressed with increasing toxin concentrations and exposure times. In livers perfused with MCLR at 0.5 microgram/ml for 10-20 min, hepatocytes had plasma membrane blebs and concentric whorls of rough endoplasmic reticulum, and there was marked disassociation of hepatocytes resulting in disrupted hepatic cords. At toxin concentrations of 2.0 or 5.0 micrograms/ml for 10-20 min, there was mild dilation of mitochondrial cristae, cytoplasmic vacuolization or invagination of plasma membranes, redistribution of organelles, and sometimes nuclear degenerative change. Some hepatocytes exhibited clusters of plasma membrane blebs radiating from round cytoplasmic structures, which may be composed primarily of condensed microfilaments.

Biological monitoring of commercial pesticide applicators for urine metabolites of the herbicide alachlor.

Alachlor (2-chloro-2',6'-diethyl-N-[methoxymethyl] acetanilide), the active ingredient in several trade name herbicides, is absorbed through the skin and readily excreted in the urine as conjugated metabolites. This paper presents the results of a study to measure alachlor metabolites in the urine of commercial pesticide applicators who were applying alachlor to corn and soybean crops under normal work conditions. Three spot urine samples, collected at the beginning and end of the work shift and the morning after the exposure survey, were collected from 20 applicators, 7 hauler-mixers, and 8 controls. Each sample was analyzed using both a competitive, solid-phase, enzyme-linked immunoassay (ELISA) and a high-performance liquid chromatography (HPLC) technique. Although the urine metabolite concentrations measured by ELISA were consistently higher than the respective HPLC measurements, a high correlation (r = 0.90) was observed between the ELISA and HPLC measurements. The controls, with little exposure to alachlor, had metabolite levels below or near the lower limits of detection for each analysis technique. Similar urine metabolite concentrations were observed for the applicators and hauler-mixers, suggesting similar work exposures. The average postexposure urine concentrations were not correlated with the amount of alachlor handled and applied, suggesting that other factors, such as work practices, are greater determinants of absorbed doses of alachlor.

Modulation of T-cell ontogeny by transplacental benzo(a)pyrene.

Transplacental exposure to the carcinogen, benzo(a)pyrene BaP, leads to depressed immune function and increased tumor incidence in mice. This paper reports ontogenetic T-cell changes in BALB/c mice after exposure to BaP in utero. Monoclonal antibodies (MAbs) were produced to fetal liver T-cells (FLT) and newborn spleen (NBS) lymphocytes purified from offspring of pregnant BALB/c mice that were given one injection of BaP (150 mg/kg body weight) in mid-gestation (day 11-13). The MAbs reacted with two T-cell membrane antigens (FLT and NBS) found in fetal liver, neonatal and adult thymus and spleen. Lymphocytes of BaP-exposed 19-day fetuses showed decreased subpopulation frequencies (P < 0.05) in fetal liver total T-cells (from 56% to 16%), Ly1 cells (from 33% to 9%), and Ly2 cells (from 56% to 1%) compared with untreated controls. In contrast, BaP increased the subpopulation frequencies (P < 0.05) in FLT cells in fetal liver (from 20% to 52%) and in newborn spleen (from 21% to 51%), and increased NBS cells in newborn spleen (from 24% to 59%). The increased frequency in FLT and NBS cells was due to their relative resistance to BaP toxicity and/or BaP-enhanced proliferation in the neonatal period. Compared with untreated controls, BaP treatment resulted in reduced numbers of T-cells in fetal liver and showed a selective toxicity for Ly1 cells (89% reduction) and Ly2 cells (99% reduction), whereas FLT cells were not reduced and NBS cells were reduced by 60%. Six-week-old juvenile mice exposed to BaP in utero showed recovery of total T-cells to control levels in spleen and thymus, but showed depletion (P < 0.01) in thymic FLT cells (from 81% to 12%) and in splenic NBS cells (from 55% to 16%). The monoclonal antibodies developed for this study recognize novel cellular changes in the murine immune system that are associated with transplacental BaP. The FLT and NBS antigens may be useful biomarkers for developmental immune dysfunctions in progeny exposed to BaP in utero.

Immunologic analyses of peripheral leukocytes from workers at an ethical narcotics manufacturing facility.

Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds. We have previously reported opiate-specific IgG antibodies, positive epicutaneous tests, and pulmonary function decrements in workers exposed occupationally to opiates. In the present work, we extended these findings to investigate the effect of occupational opiate exposure on lymphocyte subpopulations and mitogen-induced lymphoblastogenesis. Thirty-three opiate-exposed workers and 8 nonexposed control workers were evaluated for lymphocyte subpopulation absolute numbers and percentages, by evaluating cell surface antigen expression with flow cytometry. A complete blood count with differential, common clinical chemistry parameters, and serum immunoglobulin levels were also evaluated. Opiate-exposed workers showed significantly (p < .05) increased absolute numbers and percentages of HLA-DR+ cells (MHC class II histocompatibility antigen), significantly (p < .01) decreased percentages of T helper-inducer (CD4+) cells, and significantly (p < .05) decreased numbers of basophils, compared with nonexposed opiate workers from the same factory. A trend toward reduction in the T helper-inducer (CD4+)/T cytotoxic-suppressor (CD8+) lymphocyte ratio was also evident. There was also a significant decrease in lymphocyte activity stimulated by pokeweed mitogen (p < .05) in opiate-exposed workers. These data indicate that occupational opiate exposure may change the number and types of circulating peripheral blood leukocytes, or alternatively, alter the expression of receptors on the surface of these cells. In addition, occupational opiate exposure appears to decrease the sensitivity of B-cells to pokeweed mitogen stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Quinolone arthropathy in juvenile New Zealand white rabbits.

Twenty juvenile New Zealand white rabbits were dosed orally once daily with 1,000 mg of nalidixic acid/kg for 3, 7, and 14 consecutive days, then for 14 days followed by a 14-day recovery period. Eighteen age-matched rabbits were allotted to four groups and given corn oil vehicle to serve as controls for the various treatment durations. The articular cartilage from the stifle joints, shoulders, and elbows was studied by gross examination, light microscopy, and toluidine blue histochemistry, and the hips were studied by gross examination and transmission electron microscopy. When examined grossly, raised vesicles could be detected in the joints of some animals after 3 days of treatment. The distal portion of the femur and proximal portion of the ulna were predilection sites for gross lesions. Histologically, the vesicles were fluid-filled clefts in the intermediate layer of the articular cartilage. After 14 days, many of the lacunae in the areas of the defects contained chondrocyte clusters. When treated for 14 days and allowed a 14-day recovery period, territorial matrix had been deposited around individual chondrocytes within the clusters, compressing the matrix between the chondrocyte clusters into thin collagenous bands. For all treatment groups, decreased metachromasia, when stained with toluidine blue, provided histochemical evidence of loss of glycosaminoglycans in the matrix around the clefts.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of cutaneous responses and lung function from exposure to opiate compounds among ethical narcotics-manufacturing workers.

We recently demonstrated morphine-6-hemisuccinate-human serum albumin conjugate (M-6-HS-HSA)-specific IgG in serum from ethic narcotics-manufacturing workers. In this article, we present results of epicutaneous tests to opiate compounds and lung-function studies in these same workers. Thirty-nine workers, exposed to opiates, were evaluated for possible work-related changes in lung function and were administered a questionnaire concerning opiate exposure and health history in February 1988. In December 1988, 33 employees with occupational exposure to opiates, six other workers (New Jersey referent) employed at the same factory with minimal exposure to opiate compounds, and 17 nonexposed individuals from Cincinnati, Ohio, were subjected to epicutaneous threshold testing with a panel of six opiate compounds and nine common aeroallergens. In opiate-exposed workers, significantly lower epicutaneous threshold concentrations were detected (compared to New Jersey referent and Cincinnati control subjects) for dihydrocodeine (p less than 0.01), hydrocodone (p less than 0.05), codeine (p less than 0.01), and morphine (p less than 0.05). Significant associates existed among epicutaneous threshold concentrations between the agents tested; that is, individuals with a positive morphine skin test would generally have a positive codeine skin test, etc. Atopic status (positive cutaneous test results to two or more of nine common aeroallergens) was not significantly associated (p greater than 0.05) with positive opiate skin sensitivity. Although the mean cross-shift decrements in FEV1 for all workers were nonsignificant, five opiate-exposed individuals demonstrated cross-shift decrements in FEV1 of greater than 10%. Daily maximum-minus-minimum changes in workweek PEFR (PEFRmax-min) were significantly reduced for Monday through Thursday (p less than 0.05) compared to PEFRmax-min changes during a nonwork, nonexposure 3-day weekend. Ten exposed workers demonstrated daily PEFRmax-min changes of greater than 20%, suggesting acute airway obstruction. Increased cutaneous reactivity to opiate compounds among opiate-exposed workers may reflect development of pharmacologic hyperresponsiveness to opiate compounds.

Antibodies to morphine in workers exposed to opiates at a narcotics manufacturing facility and evidence for similar antibodies in heroin abusers.

According to the International Narcotics Control Board, over 45,000 kg of morphine and 54,000 kg of codeine were ethically manufactured in 1986 at three facilities in the United States. Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds in this industry. Because there are no specific federal standards for workplace exposure to narcotic dusts, exposure-control defaults to the nuisance dust standard (10 mg/m3, as an 8 hr time-weighted average). Narcotics manufacturing workers were evaluated for anti-morphine IgG before and 10 mo. after the implementation of an improved respiratory protection program (RPP). Significantly elevated IgG levels were measured before the improved RPP (P less than 0.005). After the improved RPP, a significant reduction was observed (P less than 0.001), suggesting that specific antibody levels could be used as biomarkers of exposure. Inhibition studies showed that the antibodies were specifically directed against morphine with some cross reactivity with morphine derivatives. Preliminary results are also shown which indicate that similar anti-morphine antibodies are present in the sera of intravenous heroin abusers. Elevated levels (P less than 0.05) of anti-morphine antibodies were detected in sera from heroin abusers, providing evidence that similar antibodies may be produced from non-occupational exposure to opiates. These finding have potentially far-reaching implications for addiction research and drug testing.

Subacute and subchronic toxicity of ethylene glycol administered in drinking water to Sprague-Dawley rats.

Subacute (10-day) and subchronic (90-day) toxicity studies of ethylene glycol (EG) were conducted in male and female Sprague-Dawley rats to provide the U.S. Environmental Protection Agency's (EPA) Office of Drinking Water with toxicity data for final preparation of a Health Advisory for the chemical. Ethylene glycol was administered in drinking water at concentrations of 0.5, 1.0, 2.0, and 4.0% for both sexes in the 10-day study. Based on a projected consumption rate of 100 ml/kg/day, the respective doses on a mg/kg/day basis would be 554, 1108, 2216, and 4432. These dose levels were also used in the 90-day study for females, but dose levels for the males in the 90-day study were 0.25, 0.5, 1.0, and 2.0% (227, 554, 1108, and 2216 mg/kg/day). At time of sacrifice necropsies were performed and tissues were prepared for histological evaluation. Blood samples were taken for hematology and clinical chemistry determinations. Body weights were measured weekly. Water and food consumption were determined three times weekly. No mortality occurred in the 10-day study. In the 90-day study 8/10 females and 2/10 males in the high dose group died prior to sacrifice. Body weights were suppressed in a dose response fashion for males and females. Hemoglobin, hematocrit, erythrocytes, and leukocytes were all significantly decreased in female rats receiving 4% EG for 10 days. The most significant histopathological findings, seen predominantly in males, were kidney lesions which included calcium oxalate crystals in tubules and pelvic epithelium; tubular dilation and degeneration; intratubular proteinaceous material; and inflammation in tubules and pelvic epithelium. At the same dose of ethylene glycol, males had more kidney lesions and much higher incidence and severity of lesions than the females.

Metabolism of nephrotoxic isopropylcyclohexane in male Fischer 344 rats.

The metabolism of isopropylcyclohexane and associated renal pathology were evaluated in male Fischer 344 rats exposed by oral gavage. The rats experienced moderate proximal tubular damage similar to that produced by acyclic, branched-chain hydrocarbons. The urinary metabolites of isopropylcyclohexane included cis-4-isopropylcyclohexanol, trans-4-isopropylcyclohexanol, 2-cyclohexylpropanoic acid, 2-cyclohexyl-1,3-propanediol, 2t-hydroxy-4t-isopropylcyclohexanol, 2c-hydroxy-4c-isopropyl-cyclohexanol, and 2c-hydroxy-4t-isopropylcyclohexanol. The extent and preferred sites of oxidative metabolism of nephrotoxic hydrocarbons could potentially prove useful in elucidating the pathogenic mechanisms.

The metabolism of t-butylcyclohexane in Fischer-344 male rats with hyaline droplet nephropathy.

The molecule t-butylcyclohexane is one of the first examples of a branched alkyl group attached to a hydrocarbon ring shown to be capable of producing renal damage at the corticomedullary junction of male rats. A metabolic study of t-butylcyclohexane yielded the following urinary metabolites: trans-4-t-butylcyclohexanol, 2c-hydroxy-4t-t-butylcyclohexanol, 2-methyl-2-cyclohexylpropanoic acid, 2c-hydroxy-4c-t-butylcyclohexanol, 2-methyl-2-cyclohexyl-1,3-propanediol, 2t-hydroxy-4t-t-butylcyclohexanol, and cis -4-t-butylcyclohexanol. As with other hydrocarbons of similar molecular weight that induce nephropathy in male rats, preferential sites of oxidative metabolism were observed that could potentially be related to the pathogenesis.

Immunotoxicity testing: an economical multiple-assay approach.

A model for assessing immunotoxicologic effects of chemicals and drugs was developed in the Sprague-Dawley rat whereby multiple concomitant immunoassays were performed in a single animal. The multiple parameters of immunity assessed in each rat included T cell-dependent IgG antibody production, delayed hypersensitivity, natural killer cell cytotoxicity, and production of three potent immune regulating immunocytokines: macrophage-derived interleukin 1 and prostaglandin E2, and lymphocyte-derived interleukin 2. Splenocyte and resident peritoneal macrophage numbers were also quantitated and spleen and thymus weights recorded. The sensitivity of this animal model was tested by treating rats with the immune-potentiating drugs, NPT 15392 (erythro-9-[2-hydroxy,3-nonyl]hypoxanthine) and avridine (N,N-dioctadecyl-N',N'-bis-[2-hydroxyethyl]propanediamine, or the immune-suppressive drugs, cyclophosphamide (N,N-bis[2-chloroethyl]tetrahydro-2H-1,3,2-oxazaphosphorin-2-amine -2-oxide) and dexamethasone. Rats treated with NPT 15392 or avridine generally had enhanced immune responses, while those treated with cyclophosphamide or dexamethasone had decreased immune responses. Differential responsiveness of various immunocyte populations within individual rats to different drugs, or to doses of the same drug, indicates the efficacy of measuring multiple responses within the same animal. The multiassay-single animal approach represents an economical, versatile, sensitive, and relatively comprehensive paradigm for assessing immunotoxicologic/pharmacologic properties of chemicals and drugs. The approach is extremely economical since multiple immune responses are evaluated in each animal. The approach is versatile because it is amenable to incorporation of a variety of in vitro and in vivo assays and could be applied to almost any species. The model is relatively comprehensive because major types of immune responses/immunocyte populations and immunoregulatory pathways are tested. Finally, the model is sensitive for detecting immunosuppression as well as immunoenhancement, as validated by the use of known immune response modifiers in this study.