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One of the largest river systems in South Africa, the Olifants River, has experienced significant changes in water quality due to anthropogenic activities. Since 2005, there have been various "outbreaks" of the inflammatory disease pansteatitis in several vertebrate species. Large-scale pansteatitis-related mortality events have decimated the crocodile population at Lake Loskop and decreased the population at Kruger National Park. Most pansteatitis-related diagnoses within the region are conducted post-mortem by either gross pathology or histology. The application of a non-lethal approach to assess the prevalence and pervasiveness of pansteatitis in the Olifants River region would be of great importance for the development of a management plan for this disease. In this study, several plasma-based biomarkers accurately classified pansteatitis in Mozambique tilapia (Oreochromis mossambicus) collected from Lake Loskop using a commercially available benchtop blood chemistry analyzer combined with data interpretation via artificial neural network analysis. According to the model, four blood chemistry parameters (calcium, sodium, total protein and albumin), in combination with total length, diagnose pansteatitis to a predictive accuracy of 92 percent. In addition, several morphometric traits (total length, age, weight) were also associated with pansteatitis. On-going research will focus on further evaluating the use of blood chemistry to classify pansteatitis across different species, trophic levels, and within different sites along the Olifants River.

The Oreochromis mossambicus (Peters) population inhabiting Lake Loskop, South Africa, is characterized by a high incidence of obesity and pansteatitis. We investigated potential links between the impaired health of Lake Loskop O. mossambicus and the endocrine system by assessing the expression of selected genes associated with the thyroid and adrenal endocrine axes as well as peroxisome proliferator-activated receptor gamma (pparg). Moreover, contaminant-induced thyroid and/or metabolic modulation in Lake Loskop water was evaluated using juvenile O. mossambicus in laboratory exposures. The expression of thyroid hormone receptor alpha (thra) and type 2 deiodinase (dio2) was higher in Lake Loskop O. mossambicus than fish from another population, suggesting a degree of thyroid disruption. The altered gene expression may be a consequence, rather than cause of obesity. Expression of dio2 and pparg was higher in juvenile O. mossambicus exposed to unfiltered compared to filtered lake water, and our data suggest fasting as causative factor. Micro-organism abundance can therefore be a confounding factor in studies applying molecular markers to test for thyroid modulation by environmental waters. Pansteatitis was not a significant source of variance in the expression of any of the genes investigated, suggesting that the disease is not associated with disrupted endocrine signalling., (© 2014 John Wiley & Sons Ltd.)

Annual mortality events in Nile crocodiles (Crocodylus niloticus) in the Olifants River Gorge in Kruger National Park, South Africa, were experienced between 2008 and 2012, during which at least 216 crocodiles died. Live crocodiles were lethargic. Necropsy examination of 56 affected crocodiles showed dark yellow-brown firm nodules in both somatic fat and the abdominal fat body. In all of the 11 crocodiles submitted for histology, degenerative, necrotic, and inflammatory changes supported a diagnosis of steatitis in both fat types. Crocodiles are apex predators in this anthropogenically changed aquatic ecosystem that is used by humans upstream and downstream from the park for domestic, agricultural, fishing, and recreational purposes. This pathologic review of pansteatitis in crocodiles in the Olifants River system was part of a broad multidisciplinary research program. To date, no definitive causative agent has been identified. Epidemiologic evidence suggests that this event may have been a one-time event with long-standing repercussions on the health of the crocodiles. Pathologic findings are rarely documented in wild crocodilians. This study also reports on other conditions, including the presence of coccidian oocysts, capillarid and filaroid nematodes, digenetic trematodes, and pentastomes.

Pansteatitis was confirmed in sharptooth catfish, Clarias gariepinus (Burchell), from three main locations within the Kruger National Park (KNP); the Olifants River Gorge, Engelhard Dam on the Letaba River and from the Sabie River in the Sabiepoort. An increasing prevalence of pansteatitis was observed in catfish during repeated samplings from the Olifants Gorge from 2009 to 2011 and co-existence of old and recent lesions indicated on-going incitement of pansteatitis. Only a low prevalence of pansteatitis was observed in catfish sampled from the Olifants River upstream of the Gorge in the KNP and no pansteatitis was observed in catfish sampled from a rain-filled dam not connected to the Olifants River. Common to both the Olifants Gorge and the Sabiepoort is the damming of the rivers in Mozambique to form lakes Massingir and Corumana respectively. Anthropogenic activities resulting in potential pollution of the rivers differ greatly between these two catchments, providing argument against a primary pollution-related aetiology of the pansteatitis found at these two sites. Compared with other sites, analysis of stomach contents of catfish from the Olifants Gorge and the Sabiepoort strongly suggested that consumption of a predominantly fish diet was associated with the development of pansteatitis in these fish. In a farmed population of catfish used as positive control, development of pansteatitis could be ascribed to consumption of rancid fish waste from a trout slaughterhouse. In the Olifants Gorge, alien invasive silver carp, Hypophthalmychthys molitrix (Valenciennes), seasonally migrate upstream out of Lake Massingir to spawn. This schooling species is an obligate phytoplankton feeder with consequent high levels of adipose tissue n-3 polyunsaturated fatty acids. In the Olifants Gorge, at least, this may explain seasonal exposure to levels of polyunsaturated fats in the diets of catfish and crocodiles to which these animals are not adapted. The possible roles of diet, membrane lipid composition and metabolic rate of fish, sediment pollution and seasonal drop in environmental temperature in the pathogenesis of pansteatitis in the catfish are discussed. Further studies are needed to verify some of these speculations.

Clinical, gross and histopathological investigations were carried out into large-scale mortalities on eastern Mediterranean bluefin tuna, Thunnus thynnus (L.), farms. Fish showed only nervous signs and darkened colour. At post-mortem the liver was bronze coloured and the pyloric area waxy in consistency. There was no evidence of any other gross pathology. Histopathology showed severe hepatic necrosis and lipidosis. Peri-pancreatic lipoid tissue was heavily infiltrated with an inflammatory round cell infiltrate. Fish on all three farms had been fed on a North African pilchard diet rather than traditional local or Baltic species. Once the diet was modified, losses ceased. A diagnosis of pan-steatitis as seen in other farmed fish species, as well as in terrestrial animals, on particular fish-based diets was made, although the actual factor within the diet which induced the inflammatory effect is not known.

The association of pancreatic disorders with fat necrosis in domestic animals is rare. This report concerns a case of cutaneous/subcutaneous necrotizing panniculitis and steatitis associated with a pancreatic adenocarcinoma in an 11-year-old male Siamese cat. Clinical investigation revealed variably sized nodules on the trunk, limbs and abdomen. Some of them were ulcerated; others showed a shiny yellow necrotic background featuring irregular sinus tracts. The cat was euthanized at the owner's request before a diagnosis could be made. At necropsy, abundant oily material resembling mustard replaced the subcutaneous tissue and small yellow nodules were disseminated in the omentum, mesentery and serosa of the abdomen. A multilobulated mass arising from the anterior pancreatic head was found along with liver and lymph node metastasis. Histopathology showed wide fistulous tracts draining necrotic fat from the subcutis toward the surface and multifocal areas of necrotic adipocytes replacing the panniculus. Duct-like structures and tubules lined by neoplastic epithelial cells were observed in the primary pancreatic tumour and in the metastatic sites. The aetiology of the fat necrosis was possibly the result of systemic release of lipolytic pancreatic enzymes.

Pansteatitis is caused by the consumption of high levels of unsaturated fatty acids and/or the insufficient intake of vitamin E, leading to inflammation of adipose tissue. This disease has been related to fish-based diets. However, non-conventional diets must also be considered. The authors present case records of two cats with pansteatitis, for which diet consisted mostly of pig's brain, comparing them with eight cases of disease in cats eating mainly oily fish. Cats fed pig's brain did not show clinical signs, while cats eating oily fish presented inappetence, depression, reluctance to move and subcutaneous nodules painful on palpation. Cats eating pig's brain did not show any change in blood parameters, while cats fed oily fish presented leukocytosis and anaemia. Histological examination confirmed pansteatitis in all cats, independently of the diet. All animals except one of the cats eating oily fish recovered after medical treatment and change of the feeding regime.

We examined the effects of early blockade of CD62 selectin-mediated adhesive interactions in steatotic rat liver models of ex vivo cold ischemia followed by reperfusion or transplantation by administration of P-selectin glycoprotein ligand-1 (rPSGL-Ig). In the model of cold ischemia/reperfusion, livers pretreated ex vivo with rPSGL-Ig at harvesting from obese Zucker rats showed significantly decreased portal resistance, increased bile production, and diminished hepatic endothelial neutrophil infiltration, as compared with untreated controls. Pretreatment of fatty livers with rPSGL-Ig prior to transplantation extended the survival of lean Zucker rat recipients from 40% to 90%. This effect correlated with significantly improved liver function, depressed neutrophil activity, and decreased histologic features of hepatocyte injury. Intragraft expression of CD62 P-selectin was similar in both recipient groups. rPSGL-Ig treatment decreased intragraft infiltration by CD3/CD25 cells, diminished expression of pro-inflammatory TNFalpha, IL-6, iNOS, IL-2 and IFN-gamma, without significantly affecting mRNA levels coding for anti-inflammatory IL-4. Thus, rPSGL-Ig blockade of CD62-mediated adhesive interactions protects against severe ischemia/reperfusion injury suffered otherwise by steatotic rat livers. These findings document the potential utility of rPSGL-Ig in increasing the transplant donor pool through modulation of marginal steatotic livers.

Steatitis due to vitamin E deficiency occurred in three 10-wk-old boat-billed herons (Cochlearius cochlearius) despite daily placement of a powdered vitamin supplement on the fish that was subsequently washed off by the parents. Physical findings included emaciation, yellow-brown subcutaneous nodules, a firm distended coelom, stomatitis, and yellow-white, submucosal pharyngeal nodules. Clinical pathology revealed heterophilic leukocytosis, anemia, hypoproteinemia, and low plasma alpha (alpha)-tocopherol levels (1.94 microg/ml and 2.14 microg/ml). Two of the chicks died of severe, diffuse pansteatitis and respiratory aspergillosis.

Medical records of 9 cats with chylous ascites that underwent exploratory celiotomy were reviewed. In 7 cats, chylous ascites was associated with intra-abdominal neoplasia: 4 cats had an unresectable tumor (hemangiosarcoma, 3 cats; paraganglioma, 1 cat) within the mesenteric root; 2 had malignant lymphoma of the small intestine and mesenteric lymph nodes; and 1 had lymphangiosarcoma of the abdominal wall. In 2 cats, chylous ascites was associated with nonneoplastic diseases: 1 cat had severe biliary cirrhosis and an extrahepatic portosystemic shunt; the other had steatitis caused by vitamin E deficiency. Three cats were euthanatized or died at the time of surgery, and 5 cats were euthanatized within 3 months of surgery. One cat with malignant lymphoma responded well to chemotherapy and lived for 14 months after surgery.

Young adult mice infected with MCMV were shown to develop inflammatory lesions in the peripancreatic and salivary gland adipose tissues. MCMV replication was detected by immunoperoxidase staining and electron microscopy in adipocytes, fibroblasts, endothelial cells and pericytes in brown and white adipose tissues. More infected cells were detected in C3H mice than in BALB/c, BALB.B, BALB.K or C57BL/6 mice. Peripancreatic steatitis consisted of a monocytic infiltrate surrounding focal necrosis of adipocytes, the severity of which was influenced by the route of inoculation, virus dose, and genetic susceptibility to disseminated MCMV-disease. C57BL/6 mice showed the greatest susceptibility with severe coalescing focal inflammation around areas of coagulative necrosis. Salivary gland adipose tissues exhibited lymphocytic steatitis, which was reduced in Nu/Nu mice.

Yellow fat disease was induced in young rats given a vitamin E-deficient diet supplemented with 15% fish oil. The changes in adipose tissue of this oil-induced disorder were different from those of natural yellow fat disease in horse, pig and mink. In the natural disease all fat depots had the early stage of yellow fat disease with interstitial lipofuscin-laden macrophages exclusively. In the rat, however, this change was seen only in the subcutaneous fat depot. Moreover, affected adipose tissue of animals with natural disease had extensive fibrosis, but in the rat fibrosis was always absent. Rats with fish oil-induced yellow fat disease had degenerative changes in various fat depots that occurred at various times but in the horse, pig and mink fat depots were affected simultaneously. Lipofuscin accumulated in the reticuloendothelial system in rats. Accumulation in spleen and liver was dependent on vitamin E deficiency, but only the accumulation in the Kupffer cells was correlated with yellow fat disease. Lipofuscin accumulation in the mesenteric lymph node did not depend on vitamin E deficiency.

Adipose tissue in various stages of fish oil-induced yellow fat disease in the rat had the same acid phosphatase and 5-nucleotidase activity pattern as similar stages of the disorder in mink and pig. A weak acid phosphatase and 5-nucleotidase activity was seen in interstitial lipofuscin-laden macrophages in "stage M" yellow fat disease without fat cell degeneration. Activity of these macrophagic enzymes increased when there was fat cell degeneration ("stage S" and "stage E" yellow fat disease). This different phosphatase activity in the same cell type may result from phagocytosis of substrates with variable digestibility. Macrophages directly surrounding affected fat cells in steatitis areas ("stage S" and "stage E") had strong acid phosphatase and 5-nucleotidase activity. As in the pig, increased 5-nucleotidase activity was found in affected fat cells, which probably indicates plasma membrane damage. Increased nonspecific esterase activity occurred around affected fat cells. Only a small part of this esterase activity originated from inflammatory cells. This indicates that an increase of esterase activity in degenerating adipose tissue may be an endogeneous process in this tissue.

Steatitis and fat necrosis were identified in a group of 123 American alligators (Alligator mississippiensis) kept in an enclosed pond and fed a diet of only fish for more than 10 years. All affected animals were outwardly healthy and had had no signs of disease in the period immediately before slaughter. The diagnosis was made at the time of commercial slaughter for harvest of meat and hides. Lesions consisted of firm yellow-brown masses distributed in fat tissue throughout the body. The histopathologic diagnosis was granulomatous steatitis, with fat necrosis, based on the finding of multinucleated giant cells, ceroid, and multiple foci of inflammatory cells.

Basal and hormone-stimulated lipolysis of adipose tissue was measured at successive stages during the development of fish oil-induced yellow fat disease in rats. Changes of lipolytic activity at an early stage of yellow fat disease were not seen. There was a significant increase of basal lipolysis and a decrease of stimulated lipolysis when many fat cells were affected (stage E). Since the increased basal lipolysis probably originates from degenerated fat cells, the mechanism of enzyme activation is not clear. The decreased stimulated lipolysis was proportional to the number of affected fat cells and resulted from membrane damage of these cells. Increased 5-nucleotidase activity, seen in affected fat cells, may be important, to this reduced stimulated lipolysis.