Knut Nordstoga

Canine neoplasia – Introductory paper

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‐Hodgkins 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.

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 lipopoly‐saccharide‐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 identifled 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 amyloidogenie in mink.

Protracted toxic effects caused by saline extracts of Aphanizomenon flos-aquae (Cyanophyceae/Cyanobacteria)

Abstract Secondary metabolites of toxic nature in cyanophytes exhibit a broad spectrum of effects versus other biota. Intoxications noticed during mouse bioassays, with death occurring 16–24 h or later after intraperitoneal injection, are designated protracted toxic effects. Nuisance blooms with protracted toxic strains of Aphanizomenon flos-aquae are frequent in Norway. Acute toxicity testing of 23 populations of A. flos-aquae from 12 localities of inland waters in South Norway, resulted in demonstration of 13 cases with protracted toxic response in the test animals. Material from waterblooms of non toxic and protracted toxic nature have been used in qualitative investigations with the objective to study the histopathological effects of the protracted toxic principle. Acute toxicity testing was performed (standard mouse bioassay) on saline extracts of the lyophilized cyanophyte material. Symptoms and death time were observed, and microscopical examination of organ damage was performed (using optical- and electron microscopy). Tissue samples of liver and lungs were used for detailed studies. Liver injury consisted of degenerative/necrotizing hepatocytic damage, with distinguishable cytoplasmic and nuclear vacuolation. The pulmonary lesions were characterized by thickening and hypercellularity of interalveolar septa, together with necrosis of bronchiolar and alveolar epithelium. Control animals injected with physiological saline did not exhibit histopathological damage in any organs.

Canine vascular neoplasia--a population-based clinicopathologic study of 439 tumours and tumour-like lesions in 420 dogs.

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.

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.

Canine vascular neoplasia – histologic classification and immunohistochemical analysis of 221 tumours and tumour‐like lesions

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.

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.

Splenic ellipsoids: an early target for deposition of AA amyloid induced in mink

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, nameb 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.

Pathological hepatic accumulation of long-chain n-alkanes (“paraffin liver”) in cows (Harbitz and Föling, 1940). An overlooked discovery*,**

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.

A comparative study of serum amyloid a protein (SAA) from mink and man.

Serum amyloid A protein (SAA) was isolated from mink and human serum by ultra-centrifugation and gel filtration and characterized by two-dimensional gel electrophoresis and Western blotting followed by autoradiography. SAA was found in similar quantities in the high density lipoprotein (HDL) fraction of serum from a patient suffering from systemic juvenile rheumatoid arthritis (JRA) and mink stimulated with lipopolysaccharide (LPS). Only very small quantities were present in normal human controls and not detectable in normal mink. Striking similarities were found in molecular weight, isoelectric point and degree of heterogeneity for human and mink SAA, while immunologic cross-reactivity between the two species was not found. In contrast to human HDL, mink HDL was found not to contain apoA-II and only minute amounts of apoC proteins.