Pancreatitis in hyperlipemic mink (Mustela vison).

In both man and animals, inflammatory changes in the pancreas often occur with disturbances in lipid metabolism, including hypertriglyceridemia and an excess of free fatty acids. Hyperlipoproteinemia type I is a human condition caused by a deficiency of lipoprotein lipase. A similar metabolic disturbance that occurs in mink is of considerable comparative interest, as it is also followed by pancreatitis. Pancreatic lesions in hyperlipoproteinemic mink included overt variably sized nodules with hemorrhage and necrosis. These lesions began as intralobular necrosis of exocrine cells and progressed to total lobular destruction, with eventual involvement of interlobular tissue. Remnants of epithelial cells and lipid-filled macrophages were seen in necrotic areas, along with other types of inflammatory cells scattered in a lipid-rich exudate. Granulation tissue developed rapidly in necrotic areas. Additional observations included ductal proliferation, replacement of epithelial cells with fat, and mural arterial thickening, most conspicuously with vacuolated cells and endothelial proliferation. Extravasation of lipid-rich plasma is thought to be a major intensifier of the inflammatory response.

Inflammatory response to therapeutic gold bead implantation in canine hip joint osteoarthritis.

Inflammatory changes associated with periarticular pure gold bead implants were studied in dogs involved in a clinical trial investigating motor dysfunction and chronic pain owing to hip joint dysplasia and osteoarthritis. Gold beads were percutaneously implanted via a needle into different locations surrounding the greater trochanter of the femur. Nine dogs with implants were necropsied. In all examined animals, characteristic histologic lesions were observed in the tissue surrounding the gold implants--namely, a fibrous capsule composed of concentric fibroblasts intermixed with a variable number of inflammatory cells and a paucicellular innermost layer of collagen with a few fibrocyte-like cells in empty lacunae. Lymphocytes dominated the inflammatory infiltrate, with rarely observed macrophages present in close proximity to the implant site. No giant cells were observed. Immunohistochemistry showed mixed populations of lymphocytes, both CD3 positive (T cells) and CD79a positive (B cells), which in some cases formed lymphoid follicles. Diffuse inflammatory changes were present to a minor extent in the perimysium and surrounding fascia. The inflammation observed in dogs is similar to that observed with gold implants in humans. It is possible that the clinically beneficial effect of gold beads for chronic osteoarthritis depends on sustained localized inflammation with localized release of soluble mediators. The encapsulation of the implant by a paucicellular and poorly vascularized fibrous capsule may help prevent an exaggerated inflammatory reaction by sequestering the gold bead from the surrounding tissue.

Mesenteric chylothrombosis in hyperlipidaemic mink.

In the familial form of hyperlipoproteinaemia type I of mink (Mustela vison), mesenteric lipogranulomas are common findings in longstanding cases. Patho-morphological studies of early stages indicated that these lipogranulomas arose from stagnant chyle. The composition of fatty acids of a newly formed mesenteric granuloma was determined, together with fatty acids in liver, plasma and the feed. The results supported the pathological observations, as the fat of the granuloma differed from that of the liver and plasma, and contained only small amounts of the endogenous arachidonic acid, while the exogenous eicosenoic acid was present in amounts comparable with the dietary fat.

Pancreatitis associated with hyperlipoproteinaemia type I in mink (Mustela vison): earliest detectable changes occur in mitochondria of exocrine cells.

Pancreatic tissue from young mink homozygous for a mutation in the lipoprotein lipase gene was studied by light and electron microscopy, with the aim of describing the earliest detectable changes in a process which rapidly progresses into overt pancreatitis. The mutation leads to hyperlipoproteinaemia, corresponding to hyperlipoproteinaemia type I in man. Assessment of relevant hepatic and pancreatic enzymes were included in the investigation. The earliest detectable changes consisted of widespread swelling and vacuolation of exocrine cells, arising mainly from swollen mitochondria. To a lesser extent, vesiculation of endoplasmic reticulum occurred. Mitochondria exhibited various changes, including cavitation and dilution of the matrix, with shortened and disorganized cristae displaced towards the periphery. Lamellar figures that developed within mitochondria were numerous. Acinar lumina were somewhat dilated, while plasma membranes were relatively well preserved and secretory granules seemed unchanged. Exfoliative processes progressively occurred, resulting in total necrosis of groups of parenchymal cells, while intercalated ducts were spared. The necrosis was rapidly followed by inflammatory reactions. The activity of the mitochondrial enzyme carnitine O-palmitoyltransferase, essential for the transport of fatty acids into the mitochondria, was lower in the pancreas than in the liver. The activity of the peroxisomal fatty acid beta-oxidation was high in the liver and low in the pancreas of both lipoprotein lipase-deficient and control mink. It is concluded that pancreatic lesions associated with hyperlipoproteinaemia start in exocrine cells, and are most probably the result of a metabolic disturbance, possibly a toxic effect of an excess of free fatty acids.

Fox encephalitozoonosis: isolation of the agent from an outbreak in farmed blue foxes (Alopex lagopus) in Finland and some hitherto unreported pathologic lesions.

The farmed blue fox (Alopex lagopus) is particularly susceptible to congenital infections of the microsporidian species Encephalitozoon cuniculi. This report is based on an outbreak of the disease in Finland with high mortality. Five pups (four males and one female) with prolonged disease were examined. The pups had moderate pathological alterations in the kidneys and mild lesions were found in the brains, hearts, salivary and prostatic glands. Diagnosis of E. cuniculi infection was made from serological tests (ELISA, CIA, IFAT), and by in vitro isolation of the parasite from the brain of all five pups investigated. The identity was confirmed by molecular means as E. cuniculi strain II ('mouse strain'). Novel histopathological lesions not described as yet in fox encephalitozoonosis are presented. These include cerebral infarction and necrotizing inflammation of the renal pelvis. The sources and mechanisms of spreading of E. cuniculi to blue foxes are discussed.

Chylomicron metabolism in an animal model for hyperlipoproteinemia type I.

Mink homozygous for the mutation Pro214Leu in lipoprotein lipase (LPL) had only traces of LPL activity but amounts of LPL protein in their tissues similar to those of normal mink. In normal mink, lymph chylomicrons from rats given [3H]retinol (incorporated into retinyl esters, providing a core label) and [14C]oleic acid (incorporated mainly in triglycerides (TG)) were rapidly cleared from the circulation. In the homozygous mink, clearance was much retarded. The ratio of TG to core label in plasma did not decrease and much less [14C]oleic acid appeared in plasma. Still, half of the labeled material disappeared from the circulating blood within 30;-40 min and the calculated total turnover of TG in the hypertriglyceridemic mink was almost as large as in normal mink. The core label was distributed to the same tissues in hypertriglyceridemic mink as in normal mink. Half to two-thirds of the cleared core label was in the liver. The large difference was that in the hypertriglyceridemic mink, TG label (about 40% of the total amount removed) followed the core label to the liver and there was no preferential uptake of TG over core label in adipose or muscle tissue. In normal mink, only small amounts of TG label (<10%) appeared in the liver, while most was in adipose and muscle tissues. Apolipoprotein B-48 dominated in the accumulated TG-rich lipoproteins in blood of hypertriglyceridemic mink, even in fasted animals.

A mutation in the lipoprotein lipase gene associated with hyperlipoproteinemia type I in mink: studies on lipid and lipase levels in heterozygotes.

Severe hypertriglyceridemia was previously observed in mink. Affected animals had no detectable lipoprotein lipase activity, but normal amounts of lipoprotein lipase protein in post-heparin plasma. We have now cloned cDNA for lipoprotein lipase from normal mink and identified a single point mutation in the affected animals which most likely explains the deficiency of active lipase. The mutation is located in exon 6 and results in a Pro214Leu substitution. In heterozygote mink the levels of lipoprotein lipase activity and mass in post-heparin plasma were lower than in normal mink, but could not be used to identify carriers of the mutation. In some tissues (heart, muscle, kidney and lung), lipoprotein lipase activity was decreased to about 50%. In adipose tissue there seemed to be a mechanism to compensate for the mutation, resulting in increased mass and approximately the same activity of lipoprotein lipase as in animals not carrying the mutation. Mink had high lipoprotein lipase activity and mass in kidneys, although the levels of mRNA in kidney were many fold lower than in adipose tissue. Mink had very low levels of cholesteryl ester transfer protein activity in plasma. This may contribute to the high levels of HDL in this animal species.

Oral toxicity in mice of algal toxins from the diarrheic shellfish toxin (DST) complex and associated toxins.

Mussel samples from four locations along the Norweigian coast were extracted by methods for diarrheic shellfish toxins (DST) and tested by chemical and biological methods, including histopathology. All samples had previously been found to be highly toxic in mice, with symptoms indicating the presence of non-diarrheagenic toxins in the mouse bioassay. Chemical analysis revealed that the DST okadaic acid (OA) and dinophysistoxin-1 (DTX1) were present each one in one sample, but only a minor part of the total toxicity could be attributed to these toxions. In the other two samples, OA and DTX1 were absent. Incubation of the mussel extracts from all four samples with freshly prepared hepatocytes indicated the presence of unknown toxin(s) which may not be classified within the DST complex. Purified mussel samples were given to baby mice both via intraperitoneal (i.p.) injections and by oral intubation. Oral toxicity was about 25-50 times lower than toxicity obtained by i.p. injections, a result in accordance with acute toxic properties of many toxins. Risk assessment of the unknown toxin(s) requires chemical identification, but the preliminary results obtained indicate a large margin of safety, based on the large amounts of mussel extracts necessary to yield toxic effects in the intestine and liver in experimental animals upon oral exposure versus human intake.

Lipoprotein lipase deficiency with pancreatitis in mink: biochemical characterization and pathology.

A severe hyperlipemia in mink, with a pattern that suggested recessive inheritance, was observed at a farm in Norway. On a normal mink diet, affected animals had grossly elevated levels of plasma triglycerides which decreased towards normal on a low-fat diet. Normal minks had the main part of their plasma cholesterol in the HDL fraction. Affected minks, although severely hypertriglyceridaemic, had almost normal levels of both LDL and HDL. Affected minks frequently had lipogranulomas in the mesentery and the pancreas. The lipogranulomatous tissue contained spaces filled with an amorphous, sudanophilic substance with many foamy macrophages in the fibrous tissue between the lesions. Separation of postheparin plasma on heparin-agarose revealed that the affected minks had no detectable lipoprotein lipase activity but normal activity of hepatic lipase. Both normal and affected minks had inactive lipoprotein lipase protein in pre- and post-heparin plasma. This protein, which eluted before the active lipase from heparin-agarose, probably corresponds to lipase monomers. The presence of lipoprotein lipase mass in the affected minks, but no activity, indicates that there might be a point mutation in the lipase gene. The minks provide a new animal model for studies on pancreatitis induced by hypertriglyceridemia and on lipoprotein metabolism in the lipoprotein lipase-deficient state and show features similar to those found in human hyperlipoproteinemia type I.

Serum amyloid A protein in humans and four animal species: a comparison by two dimensional electrophoresis.

Two-dimensional electrophoresis and N-terminal analysis were used to study serum amyloid A protein (SAA) from humans, mink, fox, goat and rabbit. Previously uncharacterized SAA variants were demonstrated in fox, goat and rabbit, and considerable interspecies homology was seen. In rabbit, two novel SAAs were characterized, and SAA1 and SAA2 were demonstrated in mink and rabbit sera. The results confirm previous cDNA studies and indicate that SAA do possess an important function also in fox and goat.

[Registration of canine cancer]. / Registrering av kreft hos hund.

A Norwegian Canine Cancer Registry, covering four of 19 counties, has been operative since March 1990. Until the end of April 1994 about 6,000 tumours have been registered, more than 50% of these being manifestly or potentially malignant. Among 14 selected breeds the relative risk ratio for all tumours varies with factor 35 from boxer to dunker, the boxer having the highest tumour risk. The percentage distribution of specified tumour types also varies greatly between breeds, mammary cancer constituting 59% of all neoplasms in the dachshund, but only 4% in the Bernese mountain dog. Because of the genetic diversity between breeds the dog is a suitable species for differentiation between genetically determined predisposition and environmental influences in the etiology of cancer. Epidemiological surveillance of cancer morbidity in dogs may be a useful instrument for tracing carcinogens, even in the surroundings of man.

Bovine glomerular amyloidosis: morphological studies.

Bovine kidney material with advanced glomerular deposits of amyloid was studied immunohistochemically using the avidin biotin complex immunoperoxidase method, with rabbit anti-horse AA serum as primary antibody. Severely affected glomeruli consisted of strongly reacting positive material, obscuring all cellular structures. Transmission electron microscopy revealed that the amyloidotic areas, with evident amyloid fibrils, also contained a considerable admixture of cellular remnants. In this investigation it was found that such material was more abundant in the bovine glomerular amyloid masses than in amyloid laden organs from other animal species, and it is discussed to what extent this observation may explain the varying tinctorial properties of amyloid deposits in bovine tissues, and the relative high content of histones in bovine amyloid proteins.

Serum amyloid A protein in mink during endotoxin induced inflammation and amyloidogenesis.

Two-dimensional electrophoresis was used to study SAA and AA proteins in mink during lipopolysaccharide-induced inflammation and amyloidogenesis. Three isotypes, SAA pI 6.8 and SAA pI 6.5 (both SAA1-like), and SAA pI 6.0 (SAA1- and SAA2-like), were identified in serum after both single and multiple LPS injections. Total SAA serum levels were highest in the early phase of induction, followed by a decrease ranging from 1 to 50% of the peak value during the rest of the experiment. The variation in the total SAA levels correlated with the total SAA mRNA levels. Low total SAA levels were seen both in non-amyloidotic and amyloidotic animals, and a general decrease of all isotypes was demonstrated. In hepatic amyloid fibrils, several AA isotypes, with amino acid sequence homologous exclusively to that of SAA2, were found. In the corresponding splenic material, fragments of histones H2A and H2B constituted most of the low molecular mass proteins, and no protein AA was detected. In spite of low serum levels and a non-specific isotype removal, the results confirm that SAA2 is amyloidogenic in mink.

Glomerular lesions in fibrotic kidneys of Norwegian slaughter pigs. Light microscopic and immunohistochemical studies.

An abattoir survey of renal lesions in Norwegian slaughter pigs demonstrated the presence of a macroscopic evident nephropathy characterised by pale, slightly enlarged and fibrotic kidneys in 143 out of 668 (21.4%) examined carcasses. At light microscopy fibrotic kidneys revealed glomerular lesions characterised by a diffuse mesangial proliferative glomerulopathy. Immunohistochemical examination demonstrated mesangial and paramesangial immune complex deposition containing IgM and C3, and to a lesser degree IgA and IgG in the glomeruli of fibrotic kidneys. Our observation of glomerular lesions caused by immune complex depositions in fibrotic pig kidneys are compared with mesangial nephropathies in man.

Expression of serum amyloid A genes in mink during induction of inflammation and amyloidosis.

Serum amyloid A (SAA) is an acute phase protein and the precursor of amyloid protein A (AA) in deposits of secondary amyloidosis. Several isotypes exist in mink, but previous studies suggest that mink AA is derived from only one. To assess the effect of repeated episodes of inflammation and induction of amyloidosis, qualitative and quantitative changes in hepatic and extrahepatic SAA mRNA were studied. Young female mink received subcutaneous lipopolysaccharide injections for amyloid induction. Studies were performed using RNA probes and oligonucleotide probes specific for each of two SAA mRNA species. Northern blot hybridization showed that hepatic SAA1 and SAA2 mRNA levels increased dramatically after inflammatory stimulation, and were subsequently maintained at elevated levels, showing considerable interindividual variation, but only a slight decrease during repeated inflammatory stimuli and the early stages of amyloid deposition. No preferential accumulation of mRNA specifying a particular isotype was found during the experiment. Differential expression of mink SAA mRNA during repeated inflammatory stimulation does not seem to explain why only SAA2-derived AA is found in amyloid deposits. Extrahepatic SAA mRNA seemed to be independently regulated and may thus represent another, yet not characterized, SAA isotype.

Pathological hepatic accumulation of long-chain n-alkanes ("paraffin liver") in cows (Harbitz and Fölling, 1940). An overlooked discovery. Description of lesions and identification of alkanes.

About 50 years ago crystalline deposits of a substance representing approximately 7 per cent wet tissue weight and believed to be hentriacontane or a mixture of similar long-chain n-alkanes (30-34 carbon atoms) were detected in two discoloured and swollen cow livers. Stored purified extracts from these livers were recently reanalysed using gas chromatography and mass spectrometry. They were found to contain about equal amounts of nonacosane and hentriacontane with a small admixture of tritriacontane and other long carbon-chain alkanes. On the basis of histological findings, five additional cases of "paraffin liver" in cows have been recorded. In the discussion comparison is made with the only known case of a similar disorder in a human, visceral accumulation of the same three alkanes as in the cows, which was recently described in the literature. Concerning the origin of the deposits, importance is given to the fact that the long-chain alkanes with odd carbon numbers identified both in cattle and man predominate in the cuticular waxes of many dietary plants. The very large quantities of the abnormal substance in the cow livers indicate low toxicity, and evidently accumulation over long periods of time.

Mesangioproliferative glomerulonephritis in mink with encephalitozoonosis.

Renal specimens from 6 mink with encephalitozoonosis were studied by light and electron microscopy and immunohistochemistry. The glomeruli of affected kidneys had a mesangioproliferative glomerulonephritis which was characterized by an increase in mesangial cells and matrix in most glomeruli. Some glomeruli were partially or completely sclerosed. There were protein or granular casts in the cortical and medullary tubules. Interstitial nephritis, vasculitis and tubular cysts were found. Electron microscopy demonstrated extensive matrix and increased cellularity in the mesangial areas. Glomeruli showed segmentally thickened or wrinkled capillary basement membranes. Electron dense deposits were found in the glomerular basement membranes and mesangium. Peroxidase-anti-peroxidase immunohistochemistry demonstrated that IgG and IgM positive material was present as granular deposits in the glomerular basement membrane and occasionally in the mesangium.

Renal lesions in Norwegian slaughter pigs. Macroscopic and light microscopic studies.

Six hundred and sixty-eight consecutive carcasses of slaughtered swine were examined for renal lesions at meat inspection. The macroscopic lesions were divided into 7 categories: D1 = depressions of the external surface and partial persistence of fetal lobation; D2 = focal leukolymphocytic nephritis (acute focal tubulo-interstitial nephritis); D3 = cysts; D4 = interstitial fibrosis; D5 = infarct-like lesions; D6 = fatty degeneration, and D7 = hydronephrosis. 396 (59.3%) of the examined carcasses were diagnosed as having one or more of these renal lesions. Two hundred and seventy-two (40.7%) of the carcasses were macroscopically judged as having normal kidneys. A selected material of 250 kidneys representative for each group of lesions based on macroscopic examination and 50 normal kidneys were prepared for histological examination. In the group of kidneys with the macroscopic diagnosis interstitial fibrosis (D4), an accompanying histological finding was proliferative glomerular changes with fatty degeneration of the proximal tubules. Cortical infarct-like lesions (D5) were observed in the absence of thrombo-embolic disease and were considered to have developed in association with local arterial alterations similar to polyarteritis nodosa.

The complete amino acid sequence of bovine serum amyloid protein A (SAA) and of subspecies of the tissue-deposited amyloid fibril protein A.

Bovine serum amyloid A (SAA) was isolated from the acute phase high density lipoprotein (HDL) fraction of a cow suffering from acute mastitis. The elucidated primary structure revealed a protein consisting of 112 amino acid residues. Compared with SAA proteins from other species, the bovine protein was shown to have an insertion of nine amino acid residues between positions 69 and 70. No microheterogeneity could be observed in the protein. Amyloid fibrils extracted from the kidneys were found to contain at least three subspecies of protein AA, consisting of 68, 81 and about 110 amino acid residues. The amino acid sequences established for the protein AA subspecies revealed no microheterogeneity, and were identical to that elucidated for protein SAA.