Tim J. Evans

Cancer transmission from organ donors-unavoidable but low risk.

Background Donor origin cancer (DOC) in transplant recipients may be transmitted with the graft (donor-transmitted cancer [DTC]) or develop subsequently from the graft (donor-derived cancer [DDC]). Methods Recipients with DOC between January 1, 2001, and December 31, 2010, were identified from the United Kingdom Transplant Registry and database search at transplantation centers. Results Of 30,765 transplants from 14,986 donors, 18 recipients developed DOC from 16 donors (0.06%): 3 were DDC (0.01%) and 15 were DTC (0.05%). Of the 15 DTCs, 6 were renal cell cancer; 5, lung cancer; 2, lymphoma; 1, neuroendocrine cancer; and 1, colon cancer. Recipients with DTC underwent explant/excision (11), chemotherapy (4), and radiotherapy (1). Of 15 recipients, 3 (20%) recipients with DTC died as a direct consequence of cancer. Early DTC (diagnosed ⩽6 weeks of transplantation) showed a better outcome (no DTC-related deaths in 11 cases) as opposed to late DTC (DTC-related deaths in 3 of 4 cases). Five-year survival was 83% for kidney recipients with DTC compared with 93% for recipients without DTC (P=0.077). None of the donors resulting in cancer transmission was known to have cancer at donation. Conclusions DTC is rare but frequently results in graft loss and death. The risk of cancer transmission cannot be eliminated because, in every case, the presence of cancer was not known at donation. This information will allow informed consent for prospective recipients. Explantation/excision is likely to benefit recipients with localized cancer, but in transplants other than kidney/pancreas, the benefits should be balanced against the risks of retransplantation.

Animal models got you puzzled?: think pig.

Swine are an excellent large animal model for human health and disease because their size and physiology are similar to humans, in particular, with respect to the skin, heart, gastrointestinal tract, and kidneys. In addition, the pig has many emerging technologies that will only enhance the development of the pig as the nonrodent biomedical model of choice.

Effect of ergot alkaloids associated with fescue toxicosis on hepatic cytochrome P450 and antioxidant proteins

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. Hepatic gene expression of various CYPs, selected nuclear receptors associated with the CYP induction, and antioxidant enzymes were measured using real-time PCR. Hepatic expression of CYP, antioxidant and proliferating cell nuclear antigen (PCNA) proteins were measured using Western blots. The CYP3A1 protein expression was evaluated using primary rat hepatocellular cultures treated with ergovaline, one of the major ergot alkaloids produced by fescue endophyte, in order to assess the direct role of ergot alkaloids in CYP induction. The enzyme activities of selected antioxidants were assayed spectrophotometrically. While hepatic CYP and nuclear receptor expression were increased in ergot alkaloid-exposed rats, the expression and activity of antioxidant enzymes were reduced. This could potentially lead to increased oxidative stress, which might be responsible for the decrease in hepatocellular proliferation after ergot alkaloid exposure. This study demonstrated that even short-term exposure to ergot alkaloids can potentially induce hepatic oxidative stress which can contribute to the pathogenesis of fescue toxicosis.

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.

Lead enters Rcho-1 trophoblastic cells by calcium transport mechanisms and complexes with cytosolic calcium-binding proteins

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. Pb(2+) concentrations of 1 and 10 microM are equivalent to blood levels of 20 and 200 microg/dl in pregnant women. Over this range, Pb(2+) uptake increased with time and concentration in medium containing 1 mM Ca(2+) but was greater in Ca(2+)-omitted solutions. Activation of capacitative Ca(2+) entry (CCE) with thapsigargin, an endoplasmic reticulum (ER) Ca(2+) pump inhibitor, increased Pb(2+) uptake, while inhibition of CCE by La(3+) decreased influx. Parathyroid hormone-related peptide (PTHrP) stimulates the synthesis of Ca(2+)-binding proteins (CaBPs), as well as Ca(2+) transporters, during trophoblastic differentiation. Pretreatment for 72 h with PTHrP increased Pb(2+) uptake by undifferentiated Rcho-1 cells but had little effect on the quench in differentiated cells, probably due to their greater content of CaBPs which competed for Pb(2+)-binding with indo-1. This competition was most evident in differentiated cells when 1 microM Pb(2+) caused an initial quench, followed by a rise in fluorescence. This rise was not inhibited by thapsigargin, thereby ruling out sequestration into the ER and leaving complexation of Pb(2+) by CaBPs as the most plausible interpretation. We conclude that trophoblasts have the ability to clear Pb(2+) from the maternal circulation and deliver it to the fetus.

Effects of short-term heat stress on endophytic ergot alkaloid-induced alterations in rat hepatic gene expression

Exposure to ergot alkaloids in endophyte-infected fescue (E+) is associated with impaired animal productivity, especially during heat stress, which is commonly referred to as fescue toxicosis. To elucidate the pathogenesis of this condition, the effects of short-term heat stress (HS) on hepatic gene expression in rats exposed to endophytic ergot alkaloids were evaluated. Rats implanted with telemetric transmitters to continuously measure core temperature were fed an E+ diet and maintained under thermoneutral (TN) conditions (21 degrees C) for 5 d, followed by TN or 31 degrees C (HS) conditions for 3 d. Feed intake (FI) and BW were monitored daily. The E+ and HS-induced alterations in hepatic genes were evaluated using DNA microarrays and PCR analyses. Hepatic antioxidant enzyme activities, as well as the incidence of apoptosis, were determined. As expected, intake of E+ reduced FI and BW from pretreatment levels under TN conditions, with greater reductions during short-term HS. Genes involved in gluconeogenesis and apoptosis were upregulated, whereas genes associated with oxidative phosphorylation, xenobiotic metabolism, antioxidative mechanisms, immune function, cellular proliferation, and chaperone activity were all downregulated with short-term HS. Hepatocytic apoptosis was increased and antioxidant enzyme activity decreased in the livers of rats exposed to HS. The hypothesized, exacerbating effects of HS on the direct, endophytic toxin-related and indirect, reduced caloric intake-associated alterations in hepatic gene expression were clearly demonstrated in rats and may help to elucidate the pathogenesis of fescue toxicosis in various animal species.

In vitro effects of nonylphenol on motility, mitochondrial, acrosomal and chromatin integrity of ram and boar spermatozoa.

The objective of this study was to determine the effects of nonylphenol (NP) on viability of ram and boar sperm in vitro. Ram or boar spermatozoa were exposed to 1, 10, 100, 250 and 500 μg NP ml−1 for 1, 2, 3 or 4 h. Computer‐assisted sperm motility analysis (CASA) system was used to evaluate sperm motility characteristics. Flow cytometry was used to determine mitochondrial membrane potential (MMP) and chromatin integrity, while epifluorescent microscopy was used to determine sperm acrosomal status. Exposure of both species spermatozoa to 250 and 500 μg NP ml−1 was detrimental to progressive motility (P < 0.05), and its adverse effect was significant at lower (100 μg NP ml−1) concentration (P < 0.05). The percentages of ram and boar spermatozoa with high MMP declined drastically after exposures to ≥250 μg ml−1 NP (P < 0.05). Unlike chromatin integrity, which did not appear to be altered by NP exposure, there were dose‐dependent NP effects (P < 0.05) on acrosomal integrity of both species at as low as 1 μg ml−1 NP for boar spermatozoa and 10 μg ml−1 NP for ram spermatozoa. These data show adverse effects of NP on ram and boar spermatozoa and thus its potential harmful effects on male reproduction as NP is found in fruits, vegetables, human milk, fish and livestock products.

Copper Toxicosis with Hemolysis and Hemoglobinuric Nephrosis in Three Adult Boer Goats

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. The current report is rather unusual in that it describes instances of naturally occurring copper toxicosis with hemolysis and hemoglobinuric nephrosis in 3 adult Boer goats. In 2 of these goats, a possible source of excessive dietary copper was investigated but not definitively identified. In the third goat, the etiologic factors associated with the copper toxicosis were not determined. It appears that mature Boer goats are susceptible to the hemolytic stage of chronic copper toxicosis, which was not observed in a recent, large-scale copper intoxication involving lactating dairy goats. Copper analyses on both liver and kidney samples were necessary to confirm the diagnosis of copper toxicosis in all 3 goats. All feedstuffs associated with instances of copper toxicosis should be analyzed for iron, molybdenum, sulphur, and zinc as well as copper to determine what nutritional factors are contributing to the pathogenesis of this disease. Consideration also should be given to the ingestion of hepatotoxic plants and other toxic exposures, which could predispose an animal to secondary chronic copper toxicosis.

In vitro efficacy of lufenuron against filamentous fungi and blood concentrations after PO administration in horses

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. Fungal colonies isolated from diseased equine corneas were tested against lufenuron solutions up to 700 microg/mL. Twenty-one adult horses received 1 of 3 PO lufenuron treatment regimens: 5 mg/kg body weight (BW) q24h for 3 days, 20 mg/kg BW q24h for 3 days, or 60 mg/ kg BW q24h for 1 day. Blood samples were collected up to 96 hours after drug administration and analyzed by high-performance liquid chromatography. Statistical analyses of lufenuron blood concentrations were performed by analysis of variance and Fischers Least Significant Difference test, with statistical significance set at P < .05. Lufenuron showed no effect on the in vitro growth of Aspergillus or Fusarium spp. Lufenuron was detected in the blood of all but 1 horse and showed no adverse effects. The maximum blood lufenuron concentration (83.5 +/- 58.7 microg/L) was lower than the concentrations proven to be ineffective in vitro in this study. Further therapeutic use of lufenuron as an antifungal agent in horses should be based on proven efficacy against specific strains of clinically relevant fungi with pharmacokinetic data demonstrating sufficient lufenuron concentrations in target tissues.

Endocrine alterations associated with ergopeptine alkaloid exposure during equine pregnancy

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. An understanding of the endocrine alterations associated with ergopeptine alkaloid exposure during pregnancy is necessary for the diagnosis of potential exposure to these compounds and for eective prophylaxis and therapy.