Publications by authors named "Tim J Evans"

Background: Postpartum uterine disease (metritis) is common in dairy cows. The disease develops within 1 week after calving and is associated with microbial dysbiosis, fever, and fetid uterine discharge. Cows with metritis have a greater likelihood of developing endometritis and infertility later postpartum.

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Article Synopsis
  • - Fescue toxicosis and reproductive ergotism cause similar toxic effects in late-pregnant mares and potentially other equine species, stemming from ergopeptine alkaloids (EPAs) produced by fungi.
  • - These toxins originate from a harmful endophyte found in tall fescue and a nonendophytic fungus affecting grains and grasses.
  • - Symptoms of equine ergopeptine alkaloid toxicosis (EEPAT) include issues with milk production, prolonged pregnancies, and complications during birth, leading to challenges for both mares and their foals; prevention focuses on eliminating toxin exposure and addressing hormonal imbalances.
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Metal production industries are associated with positive economic benefits, however their activities are significantly resource and energy intensive, contributing to emission of pollutants and greenhouse gases to the environment. The balance between the economic inputs and environmental footprint of the metal production industries determines their contribution to sustainability. This work provides environmental impact assessment of the production of aluminium, copper, gold, iron and steel, lead, nickel and zinc, and considers their contribution to the economy.

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Preface.

Vet Clin North Am Food Anim Pract

November 2020

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This article addresses diagnostic challenges involving toxicology cases that are multifactorial in nature, often involving sublethal exposures to multiple toxicants and/or other etiologies that are not toxic. Gold standard diagnostic approaches were developed under the assumption that cases were undoubtedly intoxications, and they still are applicable to those cases. A more integrated diagnostic approach, focusing on the initial problem list, is consistent with how veterinarians diagnose most cases.

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Industrial sources, including iron ore sintering, municipal waste incineration and non-ferrous metal processing have been prominent emitters of dioxins to the environment. With the expanding industrial sectors, many international conventions were established in order to reduce the emission of dioxins in the past two decades. The Stockholm convention, a global monitoring treaty, entered into force in 2004 with the aim to promote development of strategies to reduce or eliminate dioxin emissions.

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Article Synopsis
  • Five Japanese Black embryo transfer calves (30-45 days old) were examined due to reduced milk intake and low protein levels; 4 were alive and 1 was necropsied.
  • The clinical evaluation revealed abnormalities such as high potassium and phosphorus levels, low protein and albumin levels, high bilirubin, and increased muscle enzyme activity.
  • Necropsy of the four calves showed signs of immune complex glomerulonephritis, likely triggered by a combination of transferred antibodies at birth and subsequent vaccination against Salmonella Typhimurium.
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Microbiological and histological analysis of a sample from a swollen testicle of a 2-year-old Border Collie dog revealed a mixed infection of the fungus Blastomyces dermatitidis and the Gram-negative bacterium Aureimonas altamirensis. When subjected to an automated microbial identification system, the latter isolate was provisionally identified as Psychrobacter phenylpyruvicus, but the organism shared several biochemical features with Brucella canis and exhibited agglutination, albeit weakly, with anti-B. canis antiserum.

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A 1-year-old female Boer goat was presented with a 1-day history of pigmenturia, anorexia, and shivering. Anemia was not present initially, but progressive hemolytic anemia developed subsequently and was characterized by the finding of Heinz bodies in both intact RBCs and in ghost cells and the presence of atypical fusiform RBCs. Plasma biochemical analysis revealed increased activities of aspartate aminotransferase and gamma-glutamyltransferase, hyperbilirubinemia, and azotemia.

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This article discusses reproductive toxicants as the potential, primary causes of observed reproductive abnormalities and other variables that can affect reproductive performance in ruminants. The causes of diminished reproductive performance in ruminants are often multifactorial. It is critical that producers and their veterinarians understand the potential effects of physiologic and genetic predispositions and nutritional, environmental, infectious, and toxic stressors, as well as interactions involving management.

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During equine gestation, ergopeptine alkaloid exposure is not uncommon, and pregnant mares are particularly sensitive to the endocrine disruptive effects of these compounds on lactogenesis and steroidogenesis. Agalactia, prolonged gestation, abortion, dystocia, and placental and fetal abnormalities are all clinical manifestations of changes in the endocrine milieu induced by the ingestion of ergopeptine alkaloid-contaminated feedstuffs by mares during late gestation. An understanding of the endocrine disruptive effects of gestational exposure to ergopeptine alkaloids is necessary for the diagnosis of potential exposures to these compounds and for effective prophylaxis and therapy.

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Ingestion of white snakeroot ( Ageratina altissima ) can cause trembles in livestock and milk sickness in humans. The toxicity has been associated with tremetol, a relatively crude, multicomponent lipophilic extract of the plant. In this study, 11 different compounds were isolated from white snakeroot-derived lipophilic extracts from 18 collections.

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Pronuclear injection has been a successful strategy for generating genetically engineered mouse models to better understand the functionality of genes. A characteristic of pronuclear injection is that random integration of the transgene into the genome can disturb a functional gene and result in a phenotype unrelated to the transgene itself. In this study, we have characterized a mouse model containing an insertional mutation that, in the homozygous state, severely affects spermatogenesis as characterized by lack of sperm motility and acrosomal aplasia.

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White snakeroot ( Ageratina altissima ) and rayless goldenrod ( Isocoma pluriflora ) can cause "trembles" and "milk sickness" in livestock and humans, respectively. Tremetol, a complex mixture of sterols and derivatives of methyl ketone benzofuran has been extracted from white snakeroot and rayless goldenrod and is reported to be the toxic substance in plant material. In this study, the three major benzofuran ketones, tremetone, dehydrotremetone, and 3-oxyangeloyl-tremetone, were isolated from rayless goldenrod.

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Acute and, particularly, chronic copper exposures, along with defects in hepatic copper metabolism, altered excretion of copper, and/or nutritional imbalances between copper and other trace elements, can lead to hepatic accumulation of copper and primary copper toxicosis. There is interspecies variation in susceptibility to copper toxicosis, with sheep being the species most likely to develop this condition. Adult dairy goats and Boer crosses are generally considered resistant to chronic copper toxicosis, especially the hemolytic stage of this disease.

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Paper sludge is a waste product from the paper and pulp manufacturing industry that is generally disposed of in landfills. Pyrolysis of paper sludge can potentially provide an option for managing this waste by thermal conversion to higher calorific value fuels, bio-gas, bio-oils and charcoal. This work investigates the properties of paper sludge during pyrolysis and energy required to perform thermal conversion.

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Objective: To determine associations between age, sex, breed, and month and year of admission and the diagnosis of lead toxicosis in cattle.

Design: Retrospective case-control study. Sample Population-Records of all cattle evaluated at North American veterinary teaching hospitals during the years 1963 to 2002, which were available through the Veterinary Medical Database.

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Elephant grass is an abundant, fast growing plant with significant potential as a renewable energy source and for conversion to higher calorific value fuels. This work investigates thermal conversion of elephant grass to bio-gas, bio-oil and charcoal under two heating rates of 10 and 50 degrees C/min. The energy required to pyrolyse elephant grass was evaluated using computer aided thermal analysis technique, while composition of the resultant bio-gas and bio-oil products were monitored with gas chromatographic and mass spectroscopic techniques.

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Intake of ergot alkaloids found in endophyte-infected tall fescue grass is associated with decreased feed intake and reduction in body weight gain. The liver is one of the target organs of fescue toxicosis with upregulation of genes involved in xenobiotic metabolism and downregulation of genes associated with antioxidant pathways. It was hypothesized that short-term exposure of rats to ergot alkaloids would change hepatic cytochrome P450 (CYP) and antioxidant expression, as well as reduce antioxidant enzyme activity and hepatocellular proliferation rates.

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Lufenuron is a benzoylphenyl urea-derived insecticide that has been recently introduced as a novel treatment for fungal infections in horses. The purposes of this study were to determine (1) the in vitro efficacy of lufenuron against Aspergillus and Fusarium spp. and (2) the ability of lufenuron to reach efficacious blood concentrations after PO administration in horses.

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Ergopeptine alkaloid exposure is common in pregnant mares. Many mares live in geographic areas where Neotyphodium coenophialum-infected tall fescue is the dominant grass in pastures and hay. A variety of grasses and cereal grains can be infected by Claviceps purpurea, and fungal sclerotia can contaminate forage and especially ground and pelleted feed.

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Within the placenta, a specialized Ca(2+) transport pathway develops in trophoblasts to promote growth of the fetus and hypothetically to enhance fetal uptake of Pb(2+). This hypothesis could not be tested until a method to monitor Pb(2+) influx by indo-1 fluorescence quench became available. We have applied this new method to cultured undifferentiated and differentiated Rcho-1 trophoblastic cells.

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