PubMed · 7376377
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1980-03-22. Poor quality forage causes problems.. https://doi.org/10.1136/vr.106.12.258
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OBJECTIVE: To determine the association between a leak of sour natural gas (more than 30% hydrogen sulfide) from a pipeline in a river valley and the health of beef cattle in the intensively ranched surrounding area. DESIGN: Prospective cohort study. SAMPLE POPULATION: 13 herds of cattle within 4 km (2.5 miles) of the leak and 10 herds outside the 4-km zone. PROCEDURE: Distance of herds from the leak site was determined, using geographic information system technology. Information about speed and direction of winds was obtained from a local meteorologic station and an ambient air-quality monitoring trailer. Health and productivity data for surrounding beef herds, as well as exposure information, were collected and analyzed. RESULTS: An association was not found between total herd calf mortality and herd distance from the leak, wind-aided exposure, location in the river valley, signs of irritation consistent with exposure to the gas, or reports of odors of gas at the time of the leak. Management changes reported in response to the gas leak were identified as risk factors for total herd calf mortality. Other herd-level risk factors associated with increased calf mortality ratio included a median calving date in February and percentage of twin births for a herd. CLINICAL IMPLICATIONS: In this example, we did not detect an association between productivity of cattle and exposure to sour natural gas. Several methods can be used for ranking potential exposure after discovery of a leak.
PROBLEM: It has been proposed that high rates of resorption/spontaneous abortion may result from interaction in the decidua of gamma-interferon-producing natural killer (NK) cells and tumor necrosis factor (TNF)-alpha-producing macrophages. An increased release of TNF-alpha from placental tissue of resorptions has been reported, but macrophages producing TNF-alpha have so far not been demonstrated at the feto-maternal interface. Therefore, we have sought to identify TNF-alpha-producing cells by in situ hybridization at the feto-maternal interface in two inbred, well-characterized, and stable strains of laboratory rodents with high and low resorption rates. METHOD OF STUDY: Pregnant DBA/2-mated CBA/J mice with a resorption rate of 20% to 30% (dependent on NK cells and macrophages) and diabetes-resistant Bio-Breeding/Edinburgh (DR-BB/E) rats with low resorption rates (presumed to result from chromosomal abnormalities) were studied. AsialoGM1+ cells were detected by immunohistochemistry, and TNF-alpha mRNA+ cells were detected by in situ hybridization. RESULTS: TNF-alpha mRNA+ cells were detected in DBA/2-mated CBA/J mice at the time of resorption but only at the trophoblast-decidual junction. AsialoGM1+ cells were present in decidua, as assessed by immunohistochemistry, but few if any gave a positive signal for TNF-alpha. In rat resorptions, TNF-alpha mRNA-positive cells were present within the yolk sac and in contact with the trophoblast, but not at the trophoblast-decidual junction. In neither species did a significant accumulation of detectable TNF-alpha mRNA+ cells occur before the usual time of onset of resorption. CONCLUSIONS: In the DBA/2-mated CBA/J mouse, the removal of the placenta is associated with removal of a thin rim of adherent decidua similar to the location of the TNF-alpha mRNA+ cells detected in this study. Our data suggest that increased TNF-alpha in tissues associated with failing feto-placental units may arise from infiltration/activation of scavenger cells from decidua that are likely to be macrophages. Local TNF-alpha production in decidua, which occurs as a prelude to resorption in the CBA x DBA/2 model, could not be detected due to the insensitivity of the TNF-alpha probe we used; the release of TNF-alpha from decidual tissue left after the removal of the placenta does not differ between resorbing and healthy implant sites. AsialoGM1+ cells did not seem to be major producers of TNF-alpha. TNF-alpha mRNA+ cells in a low rate of resorption (rat) model were only found on the fetal side of the trophoblast, and they may also represent a macrophage response (to dying embryo tissue) derived from a nondecidual source. The location of TNF-alpha mRNA+ cells may identify distinct and different mechanisms of resorption in rodents.
An indirect fluorescent antibody test was applied to sera from normally calving and aborting cows and to samples of pleural fluid from their aborted calves, and the antibody titres were compared with histology and immunocytochemistry for the diagnosis of Neospora-associated abortion. Two groups of aborting cows and a third group of cows which had calved normally were used; group A consisted of 36 cows which aborted calves showing characteristic non-suppurative inflammatory lesions in which Neospora was demonstrated by immunocytochemistry, group B consisted of 100 cows which aborted calves without histological evidence of neosporosis, and group C consisted of 128 normally calved cows which were sampled within one month of calving. Serology on the maternal sera and fetal fluids was highly specific and sensitive for Neospora infection although 5 per cent of the cows which aborted Neospora-negative calves and 4.7 per cent of the normally calved cows were also seropositive. Anti-Neospora antibodies were also detected in 7 per cent of the samples of fetal fluid from Neospora-negative abortions.