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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 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.

The paper gives a brief introduction to canine oncology, including its comparative aspects as basis for recording tumours in the animal kingdom. In an abbreviated presentation of the Norwegian Canine Cancer Project for the years 1990-1998, the data (n=14,401) were divided into age groups, each of two years, into different categories of tumours, and into age and gender. As expected, cutaneous histiocytoma was the dominant tumour type in both sexes during the two first years of life. In the age group 2-3.99 years histiocytoma was still the largest group in males, but was surpassed by benign epithelial skin tumours in females. After the age of 4 years, benign epithelial skin tumours constituted the greatest circumscribed group in males, and mammary tumours in females, although the summated other tumours, not explained in this survey, dominated overall in males. Maligancies (cancer) were shown in the same way, by corresponding groups of gender and age. While mastocytoma was the most common tumour and non-Hodgkin's lymphoma the second most common during the two first years of life in females, the situation was reversed in males. Later, mammary tumours dominated in females, while different tumour types not further specified in this summarized report dominated in males, until the end of the age registration (above 14 years). Number, sex and location of most common tumours are shown in a tabular outline. Comparative aspects between human and dog tumours are considered: mammary and testicular neoplasia seemed more frequent in dogs than in humans in Norway, while intestinal, pulmonary and prostatic malignancies were less common in dogs. In our study, vascular tumours and tumour-like lesions constituted about 3% of the total data. As benign vascular tumours are incompletely reported to the human Cancer Registry, no dependable comparison may be made, but malignant vascular tumours have been on the rise during the last decades in the Norwegian human population, more so in men then in women. Finally, the article deals briefly with the development of endothelial cells, and the sparse information on causal factors of vascular tumours.

A light microscopic evaluation of 221 canine vascular tumours and tumour-like lesions, supplemented by immunohistochemistry (von Willebrand Factor, CD31, vimentin), revealed a high degree of conformity with similar conditions in humans. Four main categories of tumours are reported, i.e. benign types: haemangiomas (n=127) and lymphangioma (n=1); tumour-like lesions: papillary endothelial hyperplasia (n=8) and vascular ectasias (n=2); neoplasms of intermediate malignancy: haemangioendotheliomas (n=27), and the obvious malignant form: angiosarcomas (n=57). Further classification showed that all subtypes had their human counterparts. Papillary endothelial hyperplasia and arteriovenous and venous haemangiomas are described for the first time in dogs. The combination of conventional histopathologic methods and immunohistochemistry was in many cases very useful diagnostically, the latter technique being in some cases indispensable for establishing a definite diagnosis. In general CD31 was the most useful marker for tumours originating from endothelial cells, especially for poorly differentiated haemangiosarcomas.

This paper deals with a population-based material collected during the years 1990-1998, and comprises 439 tumours and tumour-like vascular processes from 420 dogs. Anatomic location, age, breed and gender are reported. A distinction is made between benign neoplasms, tumours of intermediate malignancy, and obvious malignant processes (angiosarcomas). Clinical behaviour, comprising recurrence and metastatic disposition, is included. Subclassification is done according to criteria used in human oncology. More than one half (242 of 439) occurred in the skin, and a great majority of skin processes (223 of 242) represented benign tumours or tumour-like lesions. The next most common site of summarised lesions was the spleen, with 110 cases, with only 17 processes in this organ being defined as benign. Splenic involvement was followed by the liver, with 13 out of 17 processes being angiosarcomas. Eleven of 12 heart tumours were angiosarcomas. A majority of skin haemangiomas was of the cavernous type (108 of 211), and more than one half (10 of 14) of the capillary haemangiomas were located on dorsal sites of the extremities. The mixed capillary/cavernous haemangiomas had a more diffuse distribution, although 20 of 31 were found in the skin of the hind limbs. Only one lymphangioma and one case of angiomatosis were observed. Most tumour-like proliferations were papillary endothelial hyperplasias. Recurrence occurred in 17 dogs, some of which had received a primary benign diagnosis. Primary metastases were observed in 63 animals, the majority in the spleen and heart. Dissemination involved a further 23 cases (22 had angiosarcoma). The male/female rate of benign tumours was 0.78, for tumour-like processes 1.83, intermediate malignant tumours 1.65, and angiosarcomas 1.60. With few exceptions, there was an overweight of all subclassified vascular lesions in animals more than 6 years of age.

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.

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.

Much evidence points to a relationship among kidney disease, lipoprotein metabolism, and the enzyme lipoprotein lipase (LPL), but there is little information on LPL in the kidney. The range of LPL activity in the kidney in five species differed by >500-fold. The highest activity was in mink, followed by mice, Chinese hamsters, and rats, whereas the activity was low in guinea pigs. In contrast, the ranges for LPL activities in heart and adipose tissue were less than six- and fourfold, respectively. The activity in the kidney (in mice) decreased by >50% on food deprivation for 6 h without corresponding changes in mRNA or mass. This decrease in LPL activity did not occur when transcription was blocked with actinomycin D. Immunostaining for kidney LPL in mice and mink indicated that the enzyme is produced in tubular epithelial cells. To explore the previously suggested possibility that the negatively charged glomerular filter picks up LPL from the blood, bovine LPL was injected into rats and mice. This resulted in decoration of the glomerular capillary network with LPL. This study shows that in some species LPL is produced in the kidney and is subject to nutritional regulation by a posttranscriptional mechanism. In addition, LPL can be picked up from blood in the glomerulus.

The spontaneous occurrence of protein AA-type of amyloidosis varies among animal species. As reactive AA-type of amyloidosis has never been detected in the blue fox, we obtained acute phase sera to search for amyloid-protective elements. The purified SAA fraction was characterized by mass and sequence analyses to disclose any unique domains in the amino acid sequence. The data revealed an SAA protein with heterogeneities in several positions, and showed the typical insertion between positions 69 and 70. By comparing the amino acid sequence with that from other mammals, no unique sequence could be observed. However, a C-terminal fragment of apolipoprotein A-I (ApoA-I) was found attached to the SAA. The amino acid sequence of the ApoA-I fragment revealed a partially blocked and ragged N-terminus. A comparison of the amino acid sequence of ApoA-I with that from the dog showed that the ApoA-I fragment started about position 190, had an intact C-terminus, and showed an identical sequence in all positions, except one. Based on the data, we suggest an interaction of the C-terminal fragment of ApoA-I with the SAA protein that inhibits the AA fibrillogenesis in the blue fox.

The spleen is the primary target for spontaneous as well as experimental AA amyloidosis in animals such as mice and mink, and is therefore a valuable organ for study of the initial phases of amyloid fibrillogenesis and deposition. We have investigated splenic amyloid AA deposits induced in the mink, and we demonstrate a novel target for AA, namely the splenic ellipsoids. We show presence of amyloid P component (AP), glycosaminoglycans (GAGs) and apolipoprotein E (apoE), all well-known common elements of amyloid, co-localizing with AA. In addition, apolipoprotein AI (apoAI) was seen co-localized to the AA deposits in the ellipsoids. We hypothesize that the ellipsoids may be important splenic structures for initial AA formation. The apoAI in the ellipsoids could displace SAA from acute phase HDL at this site, thereby making SAA available for amyloid formation and deposition.

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.

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.

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.

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.

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.

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.

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 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.

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.

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.

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.

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.

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.

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.

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.

The elution pattern obtained when amyloid fibrils from amyloid-laden bovine kidneys were subjected to gel filtration under dissociating conditions revealed a larger amount of non-AA material (eluting between the void volume and protein AA) than usually seen in other species. SDS-PAGE of this non-AA fraction yielded several Coomassie blue stained bands. The most distinctive ones gave estimated molecular masses of 15 kDa, 18 kDa, 33 kDa and 43 kDa. These molecular species were electroblotted onto PVDF membranes, and were further characterized by amino acid composition analyses, cyanogen bromide cleavage and N-terminal analyses. The results revealed that the intermediate 'non-AA' fraction consisted of histones H2B, H3 and H4 in addition to protein AA also found in this fraction.

Extraglomerular renal lesions were studied by light and electron microscopy in 13 farmed mink which showed cataractous eyes associated with spontaneous encephalitozoonosis. The extraglomerular renal lesions consisted of multiple renal cysts, multifocal-to-coalescing interstitial nephritis and vasculitis. Tubular cysts of varying size were present in the corticomedullary junction and medulla. The inflammatory infiltrates were composed mostly of lymphocytes and plasma cells and usually accompanied an interstitial fibrosis. Vasculitis, perivasculitis and sclerotic arteries were frequently seen.

Serum activities of gamma-glutamyl transferase (GGT), alkaline phosphatase (AP), aspartate aminotransferase (AST), and concentrations of total bilirubin and total bile acids were screened during a 5 year period in 27 horses used for production of hyperimmune serum. The horses investigated were regularly immunized with live cultures of the endotoxin-releasing bacteria Escherichia coli or Pasteurella multocida, the individual animals having undergone such treatment for periods varying from 2 weeks to 10 years. In a majority of the horses, GGT-activity had increased within 6 to 7 years of first having undergone immunization. Constantly high values seemed to co-incide with the presence of advanced liver amyloidosis, as demonstrated by histopathological examination after slaughter. The AP activity was also increased but only moderately compared with GGT. Individual values more than 10-fold greater than the upper reference limit were recorded for GGT, while the highest AP values were less than double the upper reference limit. Activity of AST and bilirubin concentrations remained unaffected, whereas the concentration of total bile acids rose after 6 to 7 years of immunization compared to the baseline value. It is concluded that the determination of serum activities of GGT may serve as a practical routine test for the evaluation of liver amyloidosis status in serum horses.

Alveld is a hepatogenous photosensitization disease seen in lambs grazing Narthecium ossifragum pastures in Norway. Mycotoxins, possibly sporidesmin, have been suspected to cause the liver damage in alvled as in facial eczema. The histological changes in the liver of alveld cases and in lambs photosensitized after experimental sporidesmin intoxication were compared. The liver damage, characterized by necrosis in single centrilobular hepatocytes, was of the same type in both conditions. Minor to moderate portal fibroplasia and bile duct proliferation were almost always present. Accumulated glycogen was seen in hepatocytes in the centrilobular areas. This was significantly correlated to the enzymatically measured glycogen content and there was good correlation between parenchymal damage and glycogen accumulation. The glucose-6-phosphatase and glycogen phosphorylase activities were normal. These findings indicate that parenchymal damage, rather than obstruction of the bile ducts, caused the retention of phylloerythrin both in alveld cases and in experimentally sporidesmin-intoxicated lambs. The accumulation of glycogen could not be explained.

Six calves were infected per os with Salmonella dublin and killed nine hours to seven days later. Early changes included occlusion of capillaries with a hyaline material, particularly in the ileal Peyer's patch (PP). Central areas of the follicles contained hemorrhages and edema. In later stages the follicle-associated epithelium (FAE) of both the jejunal and ileal PP was fused with the adjacent epithelium and the follicles were collapsed. As judged from 5'nucleotidase histochemistry, follicles were depleted of lymphocytes whereas reticular cells were retained. Carbonic anhydrase (CA) histochemistry showed a decreased reaction in the ileal FAE and a reduced amount of CA reactive material in the follicles of the ileal PP, indicating loss of FAE differentiation and function. Hyaline material and fibrinous thrombi were seen occluding the blood capillaries and the lymphatics, respectively. The villi were atrophied and covered with thick fibrin deposits. Using antifibrinogen antibodies, immunoperoxidase stained fibrin in the lymphatics and the lumenal deposits but not the hyaline material in the capillaries. Reaction for CA indicated that this hyaline material originated from erythrocytes. Factors contributing to the follicle atrophy may include anoxia due to stasis in the microcirculation with the formation of erythrocyte thrombi, and reduced lymphopoiesis due to a decrease in the stimulating factors provided by the FAE.

Sheep livers with environmental pigmentation were examined histochemically and by electron microscopy. The pigment granules in hepatocytes and Kupffer cells had abundant lipid droplets; they were interpreted as being a variant of lipofuscins. It is concluded that the presently used descriptive term for the condition, "perilobular liver melanosis" should be replaced by the expression "liver lipofuscinosis".

The patho-morphological alterations in porcine intestinal adenomatosis were studied by light- and electron microscopy, and the pathogenetic mechanisms leading to the adenomatous lesions were discussed. The intestinal changes were partly interpreted as degenerative modifications, partly as hyperplastic processes. In some areas there seemed to be an uncontrolled proliferation of poorly differentiated crypt epithelium, resulting in adenomatous changes. These lesions were associated with intracellular location of bacteria. It was assumed that the epithelial hyperplasia in areas with normal differentiation of crypt cells was an expression of a regenerative reaction. It was further assumed that the faulty regeneration of intestinal mucosa occurred in areas where the mesenchymal destruction was too advanced to allow complete morphological restoration.

Amyloid was extracted from the liver of a horse that had developed amyloidosis after being used for several years for the production of antibodies to bacterial antigens. The amyloid fibrils were shown to be of the AA type. Two AA proteins with molecular weights of 9000 and 11,000 and with identical partial N-terminal amino acid sequences were identified. Marked structural homology with AA from other species including man was seen, although clear species-related antigenic specificity was observed. SAA isolated from an acute phase (septic abortion) horse serum was identical to AA with respect to antigenicity and the 10 first N-terminal amino acid residues that have been studied up to now. The bulk of SAA was present in the high-density lipoprotein complex in serum. Also SAA was heterogeneous with respect to size, most molecules having a molecular weight of 11,000, and a minority 9000.

The patho-morphological lesions in fox nosematosis (encephalitozoonosis) were studied in a material comprising 150 young blue foxes from 23 different farms. Disseminated nosematosis in blue fox pups was regularly accompanied by severe vasculitis, affecting medium-sized and small arteries in various organs. The acute damage has the form of a necrotizing angiitis, with mural necrosis and sometimes resultant thrombosis. The causative organism Nosema cuniculi, is frequently present in the freshly affected arterial walls, either in endothelial or in medial smooth muscle cells. Older lesions include nodular fibrous thickening of the arterial walls, and intimal proliferation, sometimes with luminal obliteration. The conclusion is drawn that the arterial lesions are morphologically equivalent to classical polyarteritis nodosa.

The patho-morphological lesions in the liver in late stages of canine endotoxin shock were studied by light and electron microscopy. Light microscopic lesions included sinusoidal dilatations, with accumulation of red cells and leucocytes, varying damage of the sinusoidal lining, microthrombi and widening of the space of Disse. Necrotic foci were in some cases recognized within a varying number of lobuli, at times in the centrilobular areas. Electron microscopy revealed severe hepatocytic damage. These lesions included formation of blebs and other surface protrusions corresponding to cytoplasmic ecdysis. The resulting cytoplasmic fragments seemed frequently to enter the sinusoids. It is suggested that the severe disturbances observed in the proteolytic enzyme systems of plasma during endotoxin shock are influenced by the hepatic parenchymal changes observed.

The composition of the occlusive material within dilated glomerular capillaries, following intravenous injections of Liquoid in blue foxes, was studied electron microscopically; it was found that it mainly consisted of a debris in which disintegrated red cells constituted the major component. Damaged platelets and necrotic endothelial remnants were other components. These observations were interpreted as a result of glomerular stasis, and it was concluded that stasis in glomerular capillaries is a basic event in the development of the renal lesions accompanying the generalized Shwartzman reaction.

The bovine serum amyloid A (SAA) and tissue amyloid A (AA) proteins were isolated and characterized. SAA was isolated from acute phase high density lipoprotein (HDL) of a cow suffering from acute mastitis, and was identified by amino acid sequence analysis. No AA-like protein was found in complex with HDL in serum. Amyloid fibrils isolated from a bovine kidney contained a 9 kDa AA protein and a considerable amount of a 14 kDa protein. Amino acid sequence analysis showed that the largest protein probably represents undegraded SAA. This is an interesting observation which confirms previous works indicating that SAA can be incorporated in the amyloid fibrils without a prior degradation to AA. The partial amino acid sequences of bovine SAA and AA were strikingly homologous to the sequences of corresponding proteins in man and other species.

The concentration of the amyloid AA-related serum protein (SAA) was markedly increased after endotoxin injections in mink, mouse, rabbit, and man. It was particularly studied during the development of endotoxin-induced amyloidosis of the mink. Protein SAA was markedly elevated in all mink 24 h after the first endotoxin injection but had fallen to relatively low levels before the onset of amyloidosis at about 4 wk. These results are consistent with SAA being a circulating precursor of the amyloid fibril protein, AA. However, both proteins may be derived by proteolysis from a common precursor.

Experimental amyloidosis was induced in mink by repeated injections with endotoxin. Amyloid fibrils extracted from liver and spleen were fractionated by gel filtration after treatment with guanidine-hydrochloride and a reducing agent, dithiothreitol. An elution profile very similar to that of human amyloid fibrils, having protein AA as a major component, was obtained. The mink amyloid protein eluted at a position similar to that of human protein AA was by amino acid composition and partial sequence studies shown to be very similar to the latter protein and was called mink protein AA. In addition, a protein AA-related component (protein SAA) was found in increased amounts in serum of amyloidotic mink, providing further evidence of the homology with human amyloids. Experimental amyloidosis in mink represents a suitable model for studying amyloid proteins and related serum components.