Copper toxicosis in non-COMMD1 Bedlington terriers is associated with metal transport gene ABCA12

Wilson's disease, caused by a mutation in the ATP-ase 7B gene, is the only genetically characterised human disease with inhibition of biliary copper excretion and toxic copper accumulation in liver and occasionally brain. A similar copper toxicosis occurs in Bedlington terriers (CT) with liver damage only. Although CT has been associated with a defect in the COMMD1 gene (COMMD1 (del/del)), Bedlington terriers with CT and lacking this mutation are also recognised (non-COMMD1 (del/del)). A study was designed to identify any other gene polymorphisms associated with copper toxicity in Bedlington terriers employing genome wide association studies (GWAS) followed by deep sequencing of the candidate region. Blood for DNA analysis and liver for confirmation of the diagnosis was obtained from 30 non-COMMD1 (del/del) Bedlington terriers comprising equal numbers of CT-affected dogs and controls. DNA was initially subjected to GWAS screening and then further sequencing to target the putative mutant gene. The study has identified a significant disease association with a region on chromosome 37 containing identified SNP's which are highly significantly associated with non-COMMD1 (del/del) Bedlington terrier CT. This region contains the ABCA12 gene which bears a close functional relationship to ATP-ase 7B responsible for Wilson's disease in man.

Kinetics of gold nanoparticles in the human placenta

We studied the transfer of PEGylated gold nanoparticles through perfused human placenta. In 'once-through' perfusions using 15 and 30nm nanoparticles both maternal and fetal outflows were collected. Recirculating perfusions using 10 or 15nm nanoparticles lasted 6h. The gold concentration in samples was analysed on ICP-MS. The reference compound antipyrine crossed the placenta rapidly, as expected. In open perfusions nanoparticles were detected in maternal but not in fetal outflow, suggesting the lack of placental transfer. During 6h re-circulating perfusions, no particles were detected in fetal circulation. Using transmission electron microscopy (TEM) and silver enhancement, nanoparticles could be visualized in the placental tissue mainly in the trophoblastic cell layer. In in vitro experiments, nanoparticles were taken up by BeWo choriocarcinoma cells and retained inside the cells for an extended period of 48h. In conclusion, PEGylated gold nanoparticles of the size 10-30nm did not cross the perfused human placenta in detectable amounts into the fetal circulation within 6h. Whether PEGylated gold nanoparticles eventually are able to cross placenta and whether nanoparticles affect placental functions needs to be further studied.

Copper-induced hepatotoxicosis with hepatic stellate cell activation and severe fibrosis in North Ronaldsay lambs: a model for non-Wilsonian hepatic copper toxicosis of infants

Copper-sensitive North Ronaldsay sheep represent a possible model for certain hepatic-overload syndromes of infancy and childhood that are clinically, pathologically and genetically distinct from Wilson's disease. The purpose of this study was to simulate in artificially reared lambs the syndrome produced by copper exposure in susceptible human infants. Twenty four North Ronaldsay lambs were assigned to three groups of eight animals, namely, an unsupplemented control group and two trial groups given milk replacer to which copper (CuSO4) had been added at the rate of 5 mg/litre and 10 mg/litre. Four lambs from each group were killed at 40 or 69 days. Livers were fixed in 10% formalin and analysed for copper by mass spectrometry. Paraffin wax-embedded sections were stained with rhodanine for copper and labelled immunohistochemically for alpha smooth muscle actin (ASMA). At 40 days the maximum amounts of copper in the livers of both copper-supplemented groups was 1466-1605 microg/g dry weight (control group 172-201 microg/g Cu dry weight). Histochemically, copper was demonstrated within hepatocytes, together with marked apoptosis. At 69 days there was a florid pericellular fibrosis complemented by strong ASMA immunolabelling, confirming phenotypic modulation of hepatic stellate cells. Such primary copper-induced fibrogenesis confirms the unique status of this animal model in respect of childhood copper toxicosis.

Copper-associated liver disease: A proteomics study of copper challenge in a sheep model

Sheep display a variant phenotype with respect to their susceptibility to copper and derivative pathology. The North Ronaldsay sheep are acutely sensitive to environmental copper while the Cambridge breed is much more copper-tolerant. A study of protein expression in the liver of the two different breeds of sheep as a result of copper challenge would aid in the understanding of their differing pathophysiologies and contribute to knowledge of copper toxicosis in man. In this initial study, Cambridge breed sheep were challenged with oral copper and liver proteins were analyzed by two-dimensional (2-D) gel electrophoresis. Proteins whose expression pattern was modified by copper exposure were then identified by peptide mass fingerprinting using matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry. In conclusion, the pattern of changes in protein expression were consistent with an early adaptive response to oxidative challenge. This was followed by evidence of an impaired ability of the liver to compensate as copper loading increased, accompanied by oxidative stress-induced injury.

Molybdenum-associated Pituitary Endocrinopathy in Sheep Treated with Ammonium Tetrathiomolybdate

Ammonium tetrathiomolybdate (TTM) has hitherto been the treatment of choice for chronic copper poisoning in sheep, but the long-term consequences have not been evaluated. This study was based on a flock of copper-poisoned sheep which, after apparently successful treatment with TTM, became infertile and progressively unthrifty and eventually died 2-3 years later. The last five surviving animals were subjected to euthanasia and detailed study. Necropsy revealed marked wasting together with depletion of the pituitary and adrenal glands, testicular atrophy and ovarian cystic follicles. Histopathological examination revealed a non-inflammatory atrophy or degeneration of the adenohypophysis with loss of trophic cells; adrenocortical and testicular atrophy and ovarian degeneration. The regressive changes in the anterior lobe of the pituitary were confirmed by immunocytochemical labelling, which revealed a marked depletion of adrenocorticotrophic hormone (ACTH), follicle stimulating hormone (FSH) and luteinizing hormone (LH) in the affected pituitaries by comparison with healthy controls. Excess molybdenum (Mo) retention (P<0.02) was identified by inductively coupled plasma mass spectrometry (ICPMS) in the pituitaries and atomic absorption spectrometry (AAS) in the adrenals and brains of affected sheep. It was concluded that molybdenum introduced systemically as TTM is retained within the brain, pituitary and adrenal glands and is associated with a toxic endocrinopathy. It is postulated that Mo administered as thiomolybdate adversely affects the hypothalamo-adenohypophyseal system by interfering with trophic hormone release, leading to the cessation of reproductive activity and ultimately the failure of intermediary metabolism. Whether Mo exerts its effect centrally or directly on the pituitary was not established.