Clinical Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum infections in dogs.

Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum are related apicomplexans that can cause systemic illness in many species of animals, including dogs. We investigated one breeder's 25 Basset Hounds for these infections. In addition, tissues from dogs and other non-canine hosts previously reported as S. canis infections were studied retrospectively. Schizonts resembling those of S. neurona, and recognized by polyclonal rabbit anti-S. neurona antibodies, were found in six of eight retrospective cases, as well as in two additional dogs (one Basset Hound, one Springer Spaniel) not previously reported. S. neurona schizonts were found in several tissues including the central nervous system, lungs, and kidneys. Fatal toxoplasmosis was diagnosed in an adult dog, and neosporosis was diagnosed in an adult and a pup related to the one diagnosed with S. neurona. No serological reactivity to S. neurona antibodies occurred when S. canis-like liver schizonts were retrospectively assayed from two dogs, a dolphin, a sea lion, a horse, a chinchilla, a black or either of two polar bears. Sequencing conserved (18S) and variable (ITS-1) portions of nuclear ribosomal DNA isolated from the schizont-laden liver of a polar bear distinguished it from all previously characterized species of Sarcocystis. We take this genetic signature as provisionally representative of S. canis, an assumption that should be tested with future sequencing of similar liver infections in other mammalian hosts. These findings further extend the uncharacteristically broad intermediate host range for S. neurona, which also causes a neurologic disease in cats, mink, raccoons, skunks, Pacific harbor seals, ponies, zebras, lynxes, and sea otters. Further work is necessary to delineate the causative agent(s) of other cases of canine sarcocystosis, and in particular to specify the attributes of S. canis, which corresponds morphologically to infections reported from wide range of terrestrial and marine mammals.

Clinical muscular sarcocystosis in a dog.

Muscular sarcocystosis is a rare infection in dogs. Clinical myositis associated with an unidentified species of Sarcocystis was diagnosed in an adult dog from Canada. There was granulomatous myositis associated with numerous immature sarcocysts in a muscle biopsy obtained from the dog. The sarcocysts were up to 550 microm long and up to 45 microm wide. The sarcocyst wall was approximately 1 microm thick and contained short, stubby, villar protrusions that lacked microtubules. This is the first report on clinical muscular sarcocystosis in a dog.

Dermatitis in a dog associated with an unidentified Toxoplasma gondii-like parasite.

Protozoal dermatitis was diagnosed in a 6-year-old female Great Dane dog from Rio de Janeiro, Brazil. The dog died because of a chronic illness with an Ehrlichia-like organism. Numerous apicomplexan parasites were identified histologically in the section of dermal lesions. The protozoan reacted with Toxoplasma gondii polyclonal rabbit serum but not with Neospora caninum or Sarcocystis neurona antibodies. Ultrastructurally, the protozoa was not T. gondii because it had schizont-like structures with merozoites arranged around a prominent residual body, and the merozoites had several rhoptries with electron-dense contents; rhoptries in T. gondii tachyzoites are electron-lucent and a residual body is not found in groups of tachyzoites. This is the first report of unidentified T. gondii-like protozoa in the skin of a dog.

Toxoplasma gondii, Neospora caninum, Sarcocystis neurona, and Sarcocystis canis-like infections in marine mammals.

Toxoplasma gondii, Neospora caninum, Sarcocystis neurona, and S. canis are related protozoans that can cause mortality in many species of domestic and wild animals. Recently, T. gondii and S. neurona were recognized to cause encephalitis in marine mammals. As yet, there is no report of natural exposure of N. caninum in marine mammals. In the present study, antibodies to T. gondii and N. caninum were assayed in sera of several species of marine mammals. For T. gondii, sera were diluted 1:25, 1:50, and 1:500 and assayed in the T. gondii modified agglutination test (MAT). Antibodies (MAT > or =1:25) to T. gondii were found in 89 of 115 (77%) dead, and 18 of 30 (60%) apparently healthy sea otters (Enhydra lutris), 51 of 311 (16%) Pacific harbor seals (Phoca vitulina), 19 of 45 (42%) sea lions (Eumetopias jubatus) [corrected] 5 of 32 (16%) ringed seals (Phoca hispida), 4 of 8 (50%) bearded seals (Erignathus barbatus), 1 of 9 (11.1%) spotted seals (Phoca largha), 138 of 141 (98%) Atlantic bottlenose dolphins (Tursiops truncatus), and 3 of 53 (6%) walruses (Odobenus rosmarus). For N. caninum, sera were diluted 1:40, 1:80, 1:160, and 1:320 and examined with the Neospora agglutination test (NAT) using mouse-derived tachyzoites. NAT antibodies were found in 3 of 53 (6%) walruses, 28 of 145 (19%) sea otters, 11 of 311 (3.5%) harbor seals, 1 of 27 (3.7%) sea lions, 4 of 32 (12.5%) ringed seals, 1 of 8 (12.5%) bearded seals, and 43 of 47 (91%) bottlenose dolphins. To our knowledge, this is the first report of N. caninum antibodies in any marine mammal, and the first report of T. gondii antibodies in walruses and in ringed, bearded, spotted, and ribbon seals. Current information on T. gondii-like and Sarcocystis-like infections in marine mammals is reviewed. New cases of clinical S. canis and T. gondii infections are also reported in sea lions, and T. gondii infection in an Antillean manatee (Trichechus manatus manatus).

Toxoplasmosis in an elephant seal (Mirounga angustirostris).

Toxoplasma gondii infections in fish-eating marine mammals is intriguing and indicative of contamination of the sea environment with oocysts. Toxoplasma gondii was identified in an elephant seal (Mirounga angustirostris) that had encephalitis. Tissue cysts were found in sections of cerebrum, and the diagnosis was confirmed by immunohistochemical staining with T. gondii-specific polyclonal rabbit serum. This is the first report of T. gondii infection in an elephant seal.

Fatal toxoplasmosis in a bald eagle (Haliaeetus leucocephalus).

Toxoplasma gondii tachyzoites were identified in the myocardium of a bald eagle (Haliaeetus leucocephalus) that died of necrotizing myocarditis. The diagnosis was confirmed by immunohistochemical staining with T. gondii-specific polyclonal antibodies. This is a new host record for T. gondii.

Balloon cell melanoma in three dogs: a histopathological, immunohistochemical and ultrastructural study.

Balloon cell melanoma, a variant of malignant melanoma, has been reported on rare occasions in animals and is uncommon in man. Such tumours have variable numbers of large, round to polygonal cells with abundant, clear, often vacuolated cytoplasm containing fine melanin granules and variable amounts of lipid. This report describes balloon cell melanomas in three dogs. Immunohistochemically, these tumours showed reactions similar to those of human melanomas when tested with antibodies against S-100 protein, neuron-specific enolase (NSE) and vimentin. Electron microscopically, numerous heterogeneous melanosomes were demonstrated in the balloon cell cytoplasm of one tumour. Although balloon cell melanoma apparently occurs infrequently in dogs, it should always be considered in the differential diagnosis of neoplasms containing clear cells.

Bacteriologic and histologic features in mice after intranasal inoculation of Brucella melitensis.

OBJECTIVE: To characterize effects of intranasal inoculation of virulent Brucella melitensis strain 16M in mice. ANIMALS: Female Balb/c mice, 6 to 8 weeks old. PROCEDURE: Studies were designed to elucidate gross morphologic lesions, bacterial burden in target organs, and histologic changes in tissues following experimental intranasal inoculation of mice with B melitensis 16M, which could be used to characterize a model for testing vaccine efficacy. RESULTS: Measurable splenomegaly was evident at 3 and 7 weeks after inoculation. A demonstrable increase in splenic colony-forming units (CFU) from infected mice increased over time with increasing dose when comparing inocula of 10(3), 10(4), and 10(5) CFU. Recovery of brucellae from the lungs was possible early in infection with 10(1), 10(3), and 10(5) CFU, but only the group inoculated with 10(5) CFU consistently yielded quantifiable bacteria. At a dose of 10 CFU, few organisms were located in the spleen. Bacteria were recovered up to 140 days after inoculation in mice given 10(3) CFU. At an inoculum of 10(5) CFU, bacterial counts were highest early in infection. Histologic examination of tissues revealed an increase in white pulp and marginal zone in the spleen and lymphohistiocytic hepatitis. CONCLUSION AND CLINICAL RELEVANCE: Changes in the spleen and liver increased with increases in dose and with increased time following intranasal inoculation with B melitensis 16M. Surprisingly, histologic changes were not observed in the lungs of inoculated mice.

Chronic emesis caused by a nematode-induced gastric nodule in a cat.

A spirurid nematode-induced gastric nodule was believed to be responsible for chronic gastric irritation and vomiting in a domestic short-hair cat. Clinical improvement was noticed following surgical removal of the parasitic nodule in the wall of the pylorus. Morphologic characteristics of the parasite were most consistent with Spirocerca lupi. Infection with Spirocerca lupi is most commonly reported in Canids, often resulting in chronic granulomatous disease of the distal portion of the esophagus. In some animals, the lesions transform into fibrosarcomas and osteogenic sarcomas.

A study on the use of male animal models for developing a live vaccine for brucellosis.

To study the safety of Brucella melitensis WR201, a live vaccine candidate, we compared the course of infection of this strain with that of virulent 16M in male BALB/c mice. At various times after oral immunization with strains WR201 or 16M, lungs, liver, spleen, testis, epididymis, inguinal and cervical lymph nodes were removed. Tissues were divided for microbiologic culture and histopathological examination. WR201 infection in male BALB/c mice had lower intensity and shorter duration than infection caused by virulent 16M. Pathological examination of testis and epididymis revealed no inflammation following strain WR201 immunization. In contrast, animals given virulent 16M strain had substantial inflammation in infected tissues. These data confirm the marked attenuation of WR201 relative to 16M. In addition, these studies suggest that male mice may be useful to assess the safety of live, attenuated Brucella vaccine candidates.

Hermaphroditism in a Sprague-Dawley rat.

A spontaneous case of unilateral true hermaphroditism was observed during the routine necropsy of a 9-week-old presumed female Sprague-Dawley rat on a repeat-dose toxicity study. There were no drug-related effects observed. True hermaphroditism is rare in rats, and despite the large numbers of rats examined annually, few cases are reported in the literature.

Atrioventricular valvular angiectasis in Sprague-Dawley rats.

Subendothelial heart valve angiectasis has been reported in cows, dogs, pigs, rats, mice, and in human fetuses and newborns. We observed a high incidence (62 in 208 animals examined) of spontaneous angiectasis on the atrioventricular (AV) valves in 10- to 40-week-old Sprague-Dawley rats. The angiectasis was observed predominately on the septal cusp of the right AV valve and located near the AV ostium in 57 of 62 animals. Of the remaining 5 valvular angiectases, 2 were present on the parietal cusp of the right AV valve and 3 were on the left AV valve. The angiectases were single or multiple, ranging from 40 to 300 microm in diameter and were characterized by light microscopy as blood-filled dilatations lined by endothelium. Spontaneously occurring abnormalities in normal laboratory animals, such as the spontaneous valvular angiectasis reported here, need to be differentiated from drug-related lesions.

Ossifying fibroma in a miniature rex rabbit (Oryctolagus cuniculus).

In humans and animals, ossifying fibroma is a benign neoplasm that most frequently affects the mandible, often resulting in cosmetic deformities and malocclusion. It is considered rare in animals and most frequently affects young horses. A surgical biopsy of a solitary mass located beneath the gingiva in the right maxillary region, which had overgrown teeth and expanded the adjacent hard palate from a 6-year-old miniature Rex rabbit was submitted for light microscopic examination. The submitted incisional biopsy specimen was pale pink, firm, and nodular. Histopathologically, the neoplasm was composed of fibroblastic cells separated by abundant collagen. The neoplastic cells were interwoven with osteoblasts surrounding islands of mineralized, bony matrix containing few, widely spaced, often empty, lacunae. Minimal inflammation was present. Based on the histopathologic features, the tumor was diagnosed as an ossifying fibroma. To our knowledge, this is the first report of an ossifying fibroma in a rabbit.

Congenital bronchiolo-alveolar airway malformation in a cynomolgus macaque (Macaca fascicularis).

Pulmonary congenital anomalies in animals are rare. Previously reported malformations include accessory lung formation, pulmonary hypoplasia, pulmonary agenesis, and various forms of hamartoma. Congenital bronchiolo-alveolar airway malformation, a new entity, is described in a 1-day-old male cynomolgus macaque. This neonate experienced breathing difficulties shortly after birth and died while therapy was being administered. Grossly, the right lung was markedly increased in size, firm, and pink. Histopathologically, sections of right lung showed irregular bronchiole-like and alveolus-like structures. There was marked widening of alveolar septae by loosely arranged mesenchymal cells and many centrally located capillaries. Alveoli were lined by cuboidal epithelial cells. There were scattered islands of immature cartilage. A grossly enlarged lung containing bronchiole-like and alveolus-like structures, immature cartilage islands, and many capillaries within alveolar septae on histopathologic examination, is inconsistent with previously described congenital pulmonary anomalies in animals and humans.

Control of the CFTR channel's gates.

Unique among ABC (ATP-binding cassette) protein family members, CFTR (cystic fibrosis transmembrane conductance regulator), also termed ABCC7, encoded by the gene mutated in cystic fibrosis patients, functions as an ion channel. Opening and closing of its anion-selective pore are linked to ATP binding and hydrolysis at CFTR's two NBDs (nucleotide-binding domains), NBD1 and NBD2. Isolated NBDs of prokaryotic ABC proteins form homodimers upon binding ATP, but separate after hydrolysis of the ATP. By combining mutagenesis with single-channel recording and nucleotide photolabelling on intact CFTR molecules, we relate opening and closing of the channel gates to ATP-mediated events in the NBDs. In particular, we demonstrate that two CFTR residues, predicted to lie on opposite sides of its anticipated NBD1-NBD2 heterodimer interface, are energetically coupled when the channels open but are independent of each other in closed channels. This directly links ATP-driven tight dimerization of CFTR's cytoplasmic NBDs to opening of the ion channel in the transmembrane domains. Evolutionary conservation of the energetically coupled residues in a manner that preserves their ability to form a hydrogen bond argues that this molecular mechanism, involving dynamic restructuring of the NBD dimer interface, is shared by all members of the ABC protein superfamily.

Electrokinetic properties of the sarcoplasmic reticulum membrane obtained from reconstitution studies.

Electrophoretic mobility data of SR vesicles reconstituted with uncharged and two mixtures of charged and uncharged lipids (Brethes, D., Dulon, D., Johannin, G., Arrio, B., Gulik-Krzywicki, T., Chevallier, J. 1986. Study of the electrokinetic properties of reconstituted sarcoplasmic reticulum vesicles. Arch. Biochem. Biophys. 246:355-356) were analyzed in terms of four models of the membrane-water interface: (I) a smooth, negatively charged surface; (II) a negatively charged surface of lipid bilayer covered with an electrically neutral surface frictional layer; (III) an electrically neutral lipid bilayer covered with a neutral frictional layer containing a sheet of negative charge at some distance above the surface of the bilayer; (IV) an electrically neutral lipid bilayer covered with a homogeneously charged frictional layer. The electrophoretic mobility was predicted from the numerical integration of Poisson-Boltzmann and Navier-Stokes equations. Experimental results were consistent only with predictions based on Model-III with charged sheet about 4 nm above the bilayer and frictional layer about 10 nm thick. Assuming that the charge of the SR membrane is solely due to that on Ca++-ATPase pumps, the dominant SR protein, the mobility data of SR and reconstituted SR vesicles are consistent with 12 electron charges/ATPase. This value compares well to the net charge of the cytoplasmic portion of ATPase estimated from the amino acid sequence (-11e). The position of the charged sheet suggests that the charge on the ATPase is concentrated in the middle of the cytoplasmic portion. The frictional layer of SR can be also assigned to the cytoplasmic portion of Ca++-ATPase. The layer has been characterized with hydrodynamic shielding length of 1. 1 nm. Its thickness is comparable to the height of the cytoplasmic portion of Ca++-ATPase.

E5 oncoprotein transmembrane mutants dissociate fibroblast transforming activity from 16-kilodalton protein binding and platelet-derived growth factor receptor binding and phosphorylation.

The E5 oncoprotein of bovine papillomavirus type 1 is a 44-amino-acid, hydrophobic polypeptide which localizes predominantly in Golgi membranes and appears to transform cells through the activation of tyrosine kinase growth factor receptors. In fibroblasts, E5 interacts with both the 16-kilodalton vacuolar ATPase subunit and the platelet-derived growth factor receptor (PDGF-R) via its hydrophobic transmembrane domain and induces autophosphorylation of the receptor. To further analyze the correlation between E5 biological activity and its ability to bind these cellular proteins, a series of nine E5 transmembrane mutants was evaluated. In 32D mouse hematopoietic cells, there was an incomplete correlation between the abilities of the E5 mutant proteins to associate the PDGF-R and to transform cells. However, all transforming E5 mutant proteins induced PDGF-R tyrosine phosphorylation. In NIH 3T3 and C127 mouse fibroblasts, both transforming and nontransforming E5 mutant proteins were defective for PDGF-R binding. In addition, while most of the transforming E5 proteins induced PDGF-R phosphorylation, one hypertransforming mutant (serine 17) neither bound nor induced receptor autophosphorylation. These findings support the hypothesis that the transformation of fibroblasts by E5 transmembrane mutants can involve alternative cellular targets or potentially independent activities of the E5 protein. In addition, these results underscore the critical role of the transmembrane domain in mediating E5 biological activities.

Effects of free radicals on partial reactions of the Na,K-ATPase.

The function of the Na,K-ATPase is known to be considerably impaired in the presence of free radicals such as OH.. While previous experiments were largely based on the loss of enzymatic activity of the protein, this is the first communication dealing with partial reactions of the pump cycle in the presence of free radicals produced by water radiolysis. Three different system states, which are directly involved in ion transfer catalyzed by the enzyme, showed similar sensitivity to free radical action. This is indicated by largely identical D37-doses of the decay of the reaction amplitudes investigated. The decrease in the efficiency of the enzyme functions was largely due to a lethal damage of pump molecules. A kinetic analysis of the ATP-induced conformational transition E1-->E2 revealed, however, that a minor component of the inactivation is due to a reduction of the transition rate constant. The decrease of the enzymatic activity could be simulated by the decay of the rate-limiting conformational transition. This finding indicates the conservation of a close coupling between ATP-hydrolysis and sodium translocation process throughout free-radical induced inactivation. As a result of the tight coupling, enzyme modification at different system states leads to similar functional consequences for the protein.