Morphological alterations in oxidative muscles and mitochondrial structure associated with equine atypical myopathy.

REASONS FOR PERFORMING STUDY: There is a lack of well documented studies about muscular lesions in equine atypical myopathy (EAM). OBJECTIVES: To characterise morphopathological changes of striated muscles and myocardium, to progress understanding of this disease. METHODS: Thirty-two horses age 0.5-7 years kept on pasture were referred for a sudden ataxia/myoglobinuria syndrome. Clinical examination (stiffness, muscle pain, muscle fasciculations, abnormal gait, recumbency, myoglobinuria, tachycardia, sweating) and plasma CPK, LDH and AST levels were consistent with extensive myonecrosis and, together with anamnestic data, with so-called 'equine atypical myopathy' (EAM), a disease of unknown aetiology reported since 1939. Macroscopic and microscopic (histology, histoenzymology, ultrastructure) lesions were evaluated. RESULTS: Necropsic examination revealed large areas of muscle necrosis, the extent and severity of which varied between cases and muscles, but which were clearly more constant and severe in respiratory and postural muscles and in the myocardium. Histology highlighted a multifocal and monophasic process compatible with Zenker degeneration/necrosis that mostly and segmentally affected type 1 fibres. Histochemical evaluation revealed a weak and disorganised pattern of NADH tetrazolium reductase staining, the absence of calcium salts precipitates and a dramatic accumulation of lipid droplets. Ultrastructural examination often revealed fibres of which the sole modifications were altered mitochondria and sarcoplasmic lipidosis. CONCLUSIONS: Taken together, the data suggest that a primary alteration of mitochondria should be considered, although secondary mitochondrial abnormalities have yet to be ruled out. POTENTIAL RELEVANCE: The morphological features gathered here reveal that EAM shares most of the characteristics of toxic myopathies.

Population-level retrospective study of neurologically expressed disorders in ruminants before the onset of bovine spongiform encephalopathy (BSE) in Belgium, a BSE risk III country.

A retrospective epidemiological study (n = 7,875) of neurologically expressed disorders (NED) in ruminants before the onset of the bovine spongiform encephalopathy epidemic (years studied, 1980 to 1997) was carried out in Belgium. The archives of all veterinary laboratories and rabies and transmissible spongiform encephalopathy (TSE) epidemiosurveillance networks were consulted. For all species, a significantly higher number of NED with virological causes (rabies) was reported south of the Sambre-Meuse Valley. During the period 1992 to 1997, for which the data were complete, (i) the predicted annual incidence of NED varied significantly as a function of species and area (higher numbers in areas where rabies was present) but was always above 100 cases per million, and (ii) the mean incidence of suspected TSE cases and, among them, those investigated by histopathological examination varied significantly as a function of species and area. The positive predictive value of a presumptive clinical diagnosis of NED ranged from 0.13 (game) to 0.63 (sheep). Knowledge of the positive predictive value permits the definition of a reference point before certain actions (e.g., awareness and training campaigns) are undertaken. It also shows the usefulness of a systematic necropsy or complementary laboratory tests to establish an etiological diagnosis. TSE analysis of a small, targeted historical sampling (n = 48) permitted the confirmation of one case and uncovered another case of scrapie. The results of the present study help to develop and maintain the quality of the worldwide clinical epidemiological networks for TSE, especially in countries that in the past imported live animals, animal products, and feedstuffs from countries with TSE cases.

Post-mortem findings and causes of death of harbour porpoises (Phocoena phocoena) stranded from 1990 to 2000 along the coastlines of Belgium and Northern France.

Between the years 1990 and 2000, an attempt was made to determine the causes of death of 55 harbour porpoises stranded along the Belgian and northern French coasts. From 1990 to 1996, only five carcasses were collected as against seven in 1997, eight in 1998, 27 in 1999 and eight in 2000. The sex ratio was normal and most of the animals were juvenile. The most common findings were emaciation, severe parasitosis and pneumonia. A few cases of fishing net entanglement were observed. The main microscopical lesions were acute pneumonia, massive lung oedema, enteritis, hepatitis and gastritis. Encephalitis was observed in six cases. No evidence of morbillivirus infection was detected. Pneumonia was associated with bacteria or parasites, or both. The causes of death and the lesions were similar to those previously reported in other countries bordering the North Sea. The cause of the increased numbers of carcasses in 1999 was unclear but did not include viral epizootics or net entanglement. A temporary increase in the porpoise population in the southern North Sea may have been responsible.

Effect of intravenous platelet-activating factor on bovine pulmonary mast cells.

The effect of platelet-activating factor (PAF) on bovine pulmonary mast cells (MCs) was investigated in calves aged 1-4 months. PAF was administered over a 5-min period at a rate of 50 ng/kg/min to six animals, which were killed approximately 10 min later. No macroscopical lesions were observed in the lung tissue of five control calves. On semi-thin toluidine-blue stained sections, MC cytoplasm showed profuse deep-blue granulation. In the lung tissues of PAF-treated calves, striking interstitial, alveolar and interlobular oedema and emphysema were observed. MC granules occurred at the periphery of the cytoplasm and MC nuclei were easily detectable. Moreover, the number of granules in the MC cytoplasm was remarkably low. A few granules with some metachromatic material were sometimes detected outside the cell limits. Ultrastructurally, the matrix pattern of the MC granules in lung tissues of control calves was either amorphous or granular. In lung tissues of the PAF-treated calves, the granular matrix pattern was pronounced, varying from fine- to coarse-grained, and the MCs were of reduced size, with many filiform processes and exocytotic vesicles. These findings indicate that pulmonary MC degranulation was induced by PAF in healthy calves.

Comparative pathogenesis of acute and latent infections of calves with bovine herpesvirus types 1 and 5.

This study was conducted to compare the pathogenesis of acute and latent infections with closely related bovine herpesvirus types 1 (BHV-1) and 5 (BHV-5) in their natural host. Two groups of eight calves were inoculated intranasally with BHV-1 or BHV-5. Although BHV-1 and BHV-5 similarly replicate in the nasal mucosa after inoculation, both viruses differ markedly in their ability to cause disease, BHV-5 being responsible of some fatal encephalitis while BHV-1 inducing rhinotracheitis. Virus isolation and immunohistochemistry demonstrated that BHV-5 replicates extensively in neurons of the central nervous system (CNS) and in respiratory cells of lungs, tracheal and nasal mucosae. Invasion of the CNS likely occurs through the trigeminal and olfactory pathways. Both groups developed cross-neutralising antibodies during this experiment suggesting partial clinical cross-protection afforded by the two infections. Three months after primary infection, experimental reactivation showed that BHV-5 was able to establish latency in the trigeminal ganglia but also the CNS of surviving calves. Moreover, laboratory findings suggested that BHV-5 could also persist in the tracheal and nasal mucosae. These results indicate that, after primary infection, BHV-1 and BHV-5 displayed similar biological features and consequently need to be considered together for the control of BHV-1 infection.

Morbillivirus in common seals stranded on the coasts of Belgium and northern France during summer 1998.

Sixteen common seals (Phoca vitulina) were stranded on the Belgian and northern French coasts during the summer of 1998. Eleven (10 pups and one adult) were sampled for histopathological, immunohistochemical, serological, bacteriological, parasitological and virological investigations. The main gross findings were severe emaciation, acute haemorrhagic enteritis, acute pneumonia, interstitial pulmonary emphysema and oedema, and chronic ulcerative stomatitis. Microscopical lung findings were acute to subacute pneumonia with interstitial oedema and emphysema. Severe lymphocytic depletion was observed in lymph nodes. Severe acute to subacute meningoencephalitis was observed in one animal. Specific staining with two monoclonal antibodies directed against canine distemper virus (CDV) and phocine distemper virus was observed in a few lymphocytes in the spleen and lymph nodes of three seals. Anti-CDV neutralising antibodies were detected in sera from six animals. Seven of the seals were positive by reverse transcriptase-PCR for the morbillivirus phosphoprotein gene. The lesions observed were consistent with those in animals infected by a morbillivirus, and demonstrated that distemper has recently recurred in North Sea seals.

Heavy metals contamination and body condition of wintering guillemots (Uria aalge) at the Belgian coast from 1993 to 1998.

A sample of 166 common guillemots (Uria aalge) recovered from Belgian beaches during five wintering seasons, from 1993-1994 to 1997-1998, were examined. At necropsy, postmortem examination including body mass, fat reserves, presence or not of intestinal contents, eventual status of oiling, and pathological changes (cachexia, acute hemorrhagic gastroenteropathy (GEAH)) was attributed to each individual. Mild to severe cachexia, a pathology characterized by moderate to severe atrophy of the pectoral muscle as well as reduced amounts or absence of subcutaneous and/or abdominal fat, was observed for most specimens (85.8%). Heavy metal analyses (Cu, Zn, Fe, Cd, Ni, Cr, and Pb) of the tissues (typically liver, kidney, and pectoral muscle) were performed, and total lipids were determined (liver and pectoral muscle). The guillemots collected at the Belgian coast exhibited higher Cu and Zn concentrations compared to individuals collected in more preserved areas of the North Sea such as the northern colonies. A general decrease of their total body mass as well as liver, kidney, and pectoral muscle mass was associated to increasing cachexia severity. Moreover, significantly increasing heavy metal levels (Cu and Zn) in the tissues as well as depleted muscle lipid contents were observed parallel to increasing cachexia severity. On the contrary the organs' total metal burden barely correlates to this status. These observations tend to indicate a general redistribution of heavy metals within the organs as a result of prolonged starvation and protein catabolism (cachectic status). Such a redistribution could well be an additional stress to birds already experiencing stressfull conditions (starvation, oiling).

Pathological findings in two fin whales (Balaenoptera physalus) with evidence of morbillivirus infection.

Two immature female fin whales stranded on the Belgian and French coastlines, were examined post mortem. The main gross findings were massive parasitic infestation, associated with a large thrombus in one whale, and severe emaciation. Microscopical investigations revealed multinucleated syncytia with large intranuclear inclusion bodies in various tissues, and positive immunolabelling for morbillivirus antigens. Other evidence of morbillivirus infection was provided by the demonstration of specific viral structures in syncytia and in cell cultures, and the detection of neutralizing antibodies to canine distemper virus. To the authors>> knowledge, this is the first firm report of morbillivirus infection in baleen whales.

Enzyme-histochemical detection of a chymase-like proteinase within bovine mucosal and connective tissue mast cells.

The presence of chymase-like proteinase in bovine mast cells was investigated by an enzyme-histochemical technique (naphthol-AS-D-chloroacetate as substrate) in normal skin, primary bronchus, lung and duodenum. The counts and distribution of chymase-positive and toluidine blue-positive mast cells were compared by means of successive staining. Mast cells with chymase-like activity were detected in all areas, but their proportion was greater in connective than mucosal tissues, with the exception of the skin. These results contrast with those obtained in rodents, in which chymase-like proteinases are detected in all tissues and also in all mast cells. Bovine mast cells are closer to those of human beings, in which chymase-containing mast cells predominate in connective tissues, including skin. The results suggest that more than one chymase subset is present, at least in duodenum. The possible occurrence of dual-specific chymase mast cells, as in other ruminants, is discussed.

Experimental infection of specific pathogen-free New Zealand White rabbits with five strains of amyxomatous myxoma virus.

Myxomatosis is a specific disease of the European rabbit (Oryctolagus cuniculus) due to a virus belonging to the genus Leporipoxvirus. Forty-seven years after its deliberate introduction into Europe, the clinical aspects and the epizootiology of myxomatosis have changed. Two forms (nodular and amyxomatous) of the disease have been identified to date. A comparative study was made of the clinical signs, pathogenesis and gross lesions observed in male specific pathogen-free New Zealand White rabbits inoculated with five strains of amyxomatous myxoma virus. All five strains induced the characteristic amyxomatous myxomatosis clinical syndrome with clinical signs that differed only in intensity. The varying clinical intensity, together with the results of virological examination question the virulence of at least three of the five strains. Genomic analysis confirmed that the five strains came from the Lausanne strain introduced in 1952 in France and not from an unnoticed introduction of a Californian strain of myxoma virus. No link was found between the amyxomatous myxoma virus strains and the SG33 vaccine strain. 1999 Harcourt Publishers Ltd.

Histopathological pattern and humoral immune response to a crude exo-antigen and purified keratinase of Microsporum canis in symptomatic and asymptomatic infected cats.

In order to understand better the mechanisms involved in the diverse clinical patterns in Microsporum canis-infected cats, the histopathological features were compared in symptomatic and asymptomatic infected cats. Additionally, the IgG immune response to a crude exo-antigen and purified keratinase of M. canis was studied by ELISA in cats of various clinical and mycological status. Acute and subacute perifolliculitis and folliculitis occurred more frequently in symptomatic than asymptomatic cats. The latter usually displayed signs of chronic inflammation and a marked infiltration of superficial dermis by mast cells, which would suggest that these animals present similarities to chronically dermatophytic humans or animals. When using a crude M. canis antigen, all infected cats were shown to have significantly higher levels of specific IgG when compared to culture negative and mechanical carrier-cats. In these non-infected animals, specific IgG was more frequently detected in adults than in young animals. No difference in anti-crude antigen specific IgG was observed between symptomatic and asymptomatic infected cats, indicating that the presence of IgG is probably unrelated to the clinical status of cats. Anti-keratinase specific IgG was only detected in one of the infected cats.

Detection of tryptase in bovine mast cells: comparison of enzyme- and immuno-histochemistry.

Mast cell (MC) phenotypes may vary with respect to tissue site, sensitivity to degranulating agents, dependency on T lymphocytes and, above all, the composition of their granules. Proteinases (either trypsin-like or chymotrypsin-like) are granule constituents which provide an important means of distinguishing subtypes of MCs in man and rodents. The purpose of this study was to compare the distribution of MC trypsin-like protease (tryptase) in a variety of bovine tissues with the aim of examining MC heterogeneity. Tryptase was found in MCs regardless of their location within tissues. With respect to tryptase content, bovine MC distribution resembled more that of human and canine tissues than that of mice and rats. Comparison of the results yielded by enzyme- and immuno-histochemical staining suggested that a tryptase-negative, dual-specific chymase-positive MC subset occurred, at least in duodenal lamina propria, around bronchioles and within alveolar septa. The study also suggested that monoclonal antibodies raised against human tryptase can be used for quantitation of bovine tryptase in biological fluids; this offers a promising tool for evaluating the role of MC activation in disease.

Pathological investigations on guillemots (Uria aalge) stranded on the Belgian coast during the winter of 1993-94.

Pathological investigations were carried out on 67 guillemots (Uria aalge) washed up on the Belgian coast between November 1993 and March 1994. Emaciation and acute haemorrhagic gastroenteropathy were observed in more than 70 per cent of the birds. There was no statistical relationship between the level of oil contamination and the severity of the lesions. Differences in bodyweight were accounted for by age, sex, emaciation, and acute haemorrhagic gastroenteropathy. The birds had a severe weight deficit but the concentrations of pollutants were below acutely toxic levels.

Creation of the "thymoheart" allograft: implantation of autologous thymus into the heart prior to procurement.

BACKGROUND: A state of tolerance may be more easily achieved if fully vascularized and functional donor thymus is transferred to the recipient at the time of whole organ transplantation. METHODS: A composite "thymoheart" allograft was created by implanting autologous thymus into a donor heart 60-90 days before organ procurement. Successful intracardiac engraftment of autologous thymus was documented by histology and by flow cytometric analysis. RESULTS: Histology of the thymic autografts at explantation revealed viable thymus with preservation of normal thymic architecture. Cells retrieved from thymic autografts 60 days after implantation exhibited the same MHC class I and class II staining profiles by flow cytometry as cells taken from the residual native thymus. CONCLUSION: We have created a novel composite organ that confers vascularized and functional donor thymus to heart allograft recipients at the time of transplantation without affecting cardiac function.

[The current status of organ transplantation: the role of xenotransplantation?]. / Etat actuel des transplantations d'organes: place à la xénotransplantation?

In the last few years, transplantation was an area of intense research activity. However, there is a worldwide shortage of donor organs for clinical transplantations. Currently, interest in xenotransplantation research is growing not only because of the increased demand for organs but also because of advances in molecular biology techniques that make possible the genetic or immunological manipulations of the animal donor rather than the human recipient. The better definitions of the mechanisms responsible for xenograft rejection should facilitate appropriate therapeutic strategies for long xenograft survival.

In vitro effect of glucocorticoids on phagocytic function of sheep alveolar macrophages.

The potentiation of infection is a recognized adverse effect of steroids. This study examined the in vitro effect of glucocorticoids on sheep alveolar macrophage phagocytic function, an essential means of cellular defence in the lungs, by evaluating the phagocytosis of zymosan particles after 30 min of contact between alveolar macrophages and steroids. Hydrocortisone, dexamethasone phosphate and methylprednisolone significantly reduced the phagocytic capability of sheep alveolar macrophages, but the effects of dexamethasone isonicotinate, prednisolone and flumethasone were less marked.

Postmortem investigations on winter stranded sperm whales from the coasts of Belgium and The Netherlands.

During winter 1994-95, four and three sperm whales (Physeter macrocephalus) were stranded along the Belgian and the Dutch coasts, respectively. Necropsies and tissue samplings were collected 24 hrs post mortem. Lesions on several whales included round and linear skin scars, ventral skin abrasions, acute skin ulcers, acute ulcerative stomatitides, acute to chronic external otitides, and passive visceral congestion. In addition, these sperm whales appeared to be debilitated with severe weight deficit, had blubber thickness reduction, the absence of abdominal fat, and the intestinal tracts were almost empty. Three categories of lesions and their possible relation with the stranding were evaluated. Cutaneous scars observed on the seven whales appeared to have no relation with the stranding. The poor body condition and acute integument ulcerative lesions were present before the stranding. Ventral skin abrasions and visceral passive congestion were caused by the strandings. Absence of food in the alimentary tracts, evidence of weight loss and blubber thickness reduction were compatible with an extended presence of the sperm whales in the North Sea, where adequate food is not available. This might lead to progressive weakness, predisposing the animals to secondary pathogens such as viral diseases. Finally, the coastal configuration of the southern North Sea makes it a trap for sperm whales which have entered the area during their wanderings.