Oxidative modification, inflammation and amyloid in the normal and diabetic cat pancreas.

The pathogenesis of ß-cell dysfunction leading to pancreatic ß-cell failure seen in type 2 diabetes mellitus is incompletely understood. Pancreatic tissues were collected from nine control cats and nine diabetic cats and labelled immunohistochemically to examine expression of interleukin (IL)-1ß, insulin, islet amyloid polypeptide (IAPP) and 4-hydroxynonenal (4-HNE). Thioflavin-S was used to stain for amyloid. All control cats showed positive labelling for IL-1ß and 4-HNE. Diabetic cats showed varying degrees of inflammation and oxidative modification, owing in large part to the very small amount of islet structure remaining in the typical diabetic cat pancreas. Amyloid deposition was identified in 8/9 diabetic cats and 1/9 control cats. In order to validate these findings, paired biopsy samples taken from an additional group of cats enrolled in a study of obesity and hyperglycaemia (sampling at baseline and after 8-16 weeks of obesity and hyperglycaemia) were labelled for IL-1ß and 4-HNE. A similar pattern of labelling was identified in the baseline samples to that seen in control cats. A significant increase in IL-1ß and 4-HNE expression was seen after a period of hyperglycaemia and obesity. Taken together, these findings suggest that while present in normal cats, markers of inflammation and oxidative modification increase very early during the development of disease. Future studies focusing on these earlier time points are needed to understand the factors that function in protection of the islet ß cell and the development of islet pathology in type 2 diabetes mellitus in the cat.

Demonstration of transplacental transmission of a human isolate of Anaplasma phagocytophilum in an experimentally infected sheep.

Anaplasma phagocytophilum, first identified as a pathogen of sheep in Europe, more recently has been recognized as an emerging tick-borne pathogen of humans in the U.S. and Europe. Transmission of A. phagocytophilum is reported to be by ticks, primarily of the genus Ixodes. While mechanical and transplacental transmission of the type genus organism, A. marginale, occur in addition to tick transmission, these modes of transmission have not been considered for A. phagocytophilum. Recently, we developed a sheep model for studying host-tick-pathogen interactions of the human NY-18 A. phagocytophilum isolate. Sheep were susceptible to infection with this human isolate and served as a source of infection for I. scapularis ticks, but they did not display clinical signs of disease, and the pathogen was not apparent in stained blood smears. In the course of these experiments, one sheep unexpectedly gave birth to a lamb 5 weeks after being experimentally infected by inoculation with the pathogen propagated in HL-60 cells. The lamb was depressed and not feeding and was subsequently euthanized 18 h after birth. Tissues were collected at necropsy for microscopic examination and PCR to confirm A. phagocytophilum infection. At necropsy, the stomach contained colostrum, the spleen was moderately enlarged and thickened with conspicuous lymphoid follicles, and mesenteric lymph nodes were mildly enlarged and contained moderate infiltrates of eosinophils and neutrophils. Blood, spleen, heart, skin and cervical and mesenteric lymph nodes tested positive for A. phagocytophilum by PCR, and sequence analysis confirmed that the lamb was infected with the NY-18 isolate. Transplacental transmission should therefore be considered as a means of A. phagocytophilum transmission and may likely contribute to the epidemiology of tick-borne fever in sheep and other mammals, including humans.

Ambiguous genitalia in a fertile, unilaterally cryptorchid male miniature schnauzer dog.

A 7-year-old male miniature schnauzer dog with unilateral cryptorchidism was presented for elective orchiectomy. Surgery to remove the cryptorchid testis revealed a fully formed uterus with horns attached to both testis and the body and cervix terminating at the prostate gland. The gross and microscopic diagnosis for the genital tract was persistent Müllerian duct syndrome with unilateral cryptorchidism. Additional associated lesions included cystic endometrial hyperplasia and a solitary, intratubular seminoma within the undescended testis. Persistent Müllerian duct syndrome is rare among domestic animals but is more common in miniature schnauzer dogs because of inheritance as an autosomal recessive trait.

Gastritis in Alaskan racing sled dogs.

Alaskan racing sled dogs are a well-established model of exercise-induced gastric disease. The aim of this study was to define the temporal development of microscopical gastric lesions during long distance racing. Two groups of dogs were examined: group I comprised conditioned dogs that were exercising and group II were conditioned dogs not exercising. The gastric mucosa was examined endoscopically and sampled for routine histopathology and microscopical scoring, immunohistochemistry (IHC) and detection of apoptotic epithelial cells. Overall, group I dogs exhibited more significant epithelial lesions, including ulcers, compared with dogs in group II. Group II dogs exhibited the most severe mucosal inflammatory infiltrates. Although the intensity of inflammation differed, the nature of the inflammation was similar between groups, consisting of diffuse lymphocytic infiltration and a unique interface-type infiltrate that obscured the basement membrane zone and was accompanied by intraepithelial infiltration of lymphocytes. IHC confirmed the presence of CD3(+) T and CD79(+) B lymphocytes within the mucosal infiltrates; however, most of the intraepithelial and interface infiltrates were CD3(+) T cells. Spiral-shaped bacterial organisms were seen in the gastric tissues; however, their presence did not correlate with either the severity of epithelial lesions, inflammation or the pattern of interface inflammation. The number of apoptotic epithelial cells was widely variable and not significantly different between groups. These findings confirm previous observations that gastric ulcers develop in conditioned dogs under racing stress. The unique nature of the interface-type gastric inflammation is similar to that of human lymphocytic gastritis and may suggest an immune-mediated mechanism for the changes seen in Alaskan racing sled dogs.

Type I IFN response to Papiine herpesvirus 2 (Herpesvirus papio 2; HVP2) determines neuropathogenicity in mice.

Isolates of baboon alpha-herpesvirus Papiine herpesvirus 2 (HVP2) exhibit one of two distinct phenotypes in mice: extremely neurovirulent or apathogenic. Previous studies implicated the type I interferon (IFN) response as being a major factor in controlling infection by apathogenic isolates. To further investigate the possibility that the host IFN-beta response underlies the pathogenicity of the two HVP2 subtypes, the susceptibility of mice lacking the IFN-beta receptor (IFNAR(-/-)) to infection was examined. Apathogenic isolates of HVP2 (HVP2ap) replicated in IFNAR(-/-) primary mouse dermal fibroblast (PMDF) cultures as well as neurovirulent (HVP2nv) isolates. IFNAR(-/-) mice were also susceptible to lethal infection by HVP2ap isolates. Unlike Balb/c or parental 129 mice, LD(50) and ID(50) values for HVP2ap were the same in IFNAR(-/-) mice indicating that in these mice infection always progressed to death. HVP2ap replicated in the skin at the site of inoculation and invaded dorsal root ganglia as efficiently as HVP2nv in IFNAR(-/-) mice. Since the virion host shutoff (vhs) protein encoded by the UL41 gene of herpes simplex virus has been implicated in circumventing the host IFN-beta response and the phenotype of UL41 deletion mutants of HSV is very similar to that of HVP2ap isolates, the UL41 gene was deleted from HVP2nv (Delta 41) and replaced with the UL41 ORF from HVP2ap (Delta 41C). Like the parental HVP2nv virus, the Delta 41C recombinant replicated efficiently in Balb/c PMDFs and did not induce a strong IFN-beta response. The neuropathogenicity of the Delta 41C recombinant was also the same as the parental HVP2nv virus in Balb/c mice, indicating that the vhs protein does not underlie the different neuropathogenic phenotype of HVP2ap and HVP2nv. In contrast, the Delta 41 deletion virus induced a strong IFN-beta response but was still able to undergo multiple rounds of replication in PMDF cultures, albeit at a slower pace than the parental HVP2nv. This was reflected in vivo as the Delta 41 mutant had an LD(50) equivalent to that of the parental HVP2nv virus although the time to death was longer. These results indicate that while the vhs protein is involved in preventing and/or suppressing an IFN-beta response, it is not responsible for the ability of HVP2nv to overcome IFN-beta induced resistance of uninfected cells and does not underlie the divergent pathogenicity of the two HVP2 subtypes in mice.

Occult metastatic intestinal adenocarcinoma resulting in pathological fracture of the proximal humerus.

Intestinal adenocarcinomas are rare but have been described in the literature. The present case is unusual in both its clinical presentation and in the distribution of metastatic lesions. The sequestrum formation and pathological fracture present are most commonly associated with osteomyelitis in horses and the details of the case highlight the need for differential diagnosis in these particular circumstances and of which clinicians should be aware.

Systemic reactive angioendotheliomatosis-like syndrome in a steer presumed to be persistently infected with bovine viral diarrhea virus.

Unusual proliferative intravascular lesions were seen in multiple organs of a 2-year-old Corriente steer presumed to be persistently infected with bovine viral diarrhea virus (BVDV), based on widespread immunohistochemical detection of BVDV antigen. Proliferations of spindle cells, which were immunohistochemically positive for von Willebrand factor-related antigen, partially-to-completely occluded vessel lumens and were supported by cells that were immunohistochemically positive for smooth muscle actin. Distribution and character of the intraluminal proliferations are strikingly similar to those described in feline systemic reactive angioendotheliomatosis, a rare entity of unknown cause. The presence of occasional intravascular thrombi suggests that the proliferative vasculopathy was associated with an underlying thrombotic process with immunohistochemical similarities to thrombotic thrombocytopenic purpura of humans. Death of the steer was due to hemorrhage from a castration wound, which may indicate thrombocytopenia or platelet dysfunction. The role of persistent BVDV infection in the formation of the intravascular lesions is unknown.

Pulmonary aspergillosis and ischemic distal limb necrosis associated with enteric salmonellosis in a foal.

A 5-month-old mixed-breed filly presented with diarrhea due to Salmonella typhimurium infection and subsequently developed pneumonia in addition to ischemic necrosis of distal limbs. Pulmonary lesions were characterized by numerous discrete, disseminated pyogranulomas with intralesional fungal hyphae. The morphologic characteristics of fungal hyphae were consistent with Aspergillus spp., and large numbers of A fumigatus were isolated from lung tissue via fungal culture. Lesions in all 4 limbs were similar in distribution, duration, and severity and were characterized by coagulation necrosis accompanied by occasional thrombi in small vessels without evidence of thrombosis of larger limb arteries. Thus, limb lesions are consistent with symmetrical peripheral gangrene, a potential complication of sepsis.

Temporal progression of viral replication and gross and histological lesions in Balb/c mice inoculated epidermally with Saimiriine herpesvirus 1 (SaHV-1).

Saimiriine herpesvirus 1 (SaHV-1), an alphaherpesvirus enzootic in squirrel monkeys, is genetically related to monkey B virus and human herpes simplex virus (HSV). To study the temporal progression of viral spread and associated lesions, Balb/c mice were inoculated epidermally by scarification with a green fluorescent protein (GFP)-expressing recombinant strain of SaHV-1 and killed sequentially. Pinpoint ulcerative lesions in the inoculated epidermis progressed over a few days to unilateral or bilateral hindlimb paresis or paralysis, urinary and faecal incontinence, abdominal distension, hunched posture and eventual depression warranting euthanasia. Viral replication was present within epidermal keratinocytes, neurons of the dorsal root ganglia and thoracolumbar spinal cord, regional autonomic ganglia, lower urinary tract epithelium and colonic myenteric plexuses, as indicated by histological lesions and GFP expression. Almost all mice inoculated with 10(5) or 10(6) plaque-forming units (PFU) of SaHV-1 developed rapidly progressive disease. Two of eight mice given 10(4)PFU developed disease, but no mice receiving less than 10(4)PFU gave evidence of infection. Mice that showed no clinical signs also failed to develop an antiviral IgG response, indicating absence of active viral infection. For SaHV-1 inoculated epidermally, the ID(50), CNSD(50) and LD(50) values were identical (10(4.38)), indicating that successful infection by this route invariably resulted in lethal CNS (central nervous system) disease. Consistently severe disease in all infected animals, with regionally extensive distribution of viral replication, constituted a marked difference from the disease produced by intramuscular inoculation.

Construction and in vivo detection of an enhanced green fluorescent protein-expressing strain of Saimiriine herpesvirus 1 (SaHV-1).

Saimiriine herpesvirus 1 (SaHV-1) is an alpha-herpesvirus of squirrel monkeys used in mice to study neural pathogenesis of herpesviruses. To trace dissemination of virus from a peripheral site of inoculation to the central nervous system tissues, a recombinant strain of SaHV-1 expressing enhanced green fluorescent protein (GFP) was constructed by site-specific insertion of a GFP expression cassette into a transcriptionally null point in the SaHV-1 genome. PCR and Southern blot confirmed insertion of a single GFP expression cassette into the target site of the SaHV-1 genome. The recombinant virus was shown to produce strong fluorescence in the cytoplasm of infected cells in vitro. Growth kinetic experiments demonstrated no differences between recombinant and wild type SaHV-1 in producing infectious progeny virions. The recombinant virus was comparable to wild type SaHV-1 in development of clinical disease, microscopic lesions and induction of an antibody response in mice following intramuscular inoculation. Using confocal microscopy, GFP expression was easily observed in formalin fixed, paraffin-embedded tissues of mice infected with the recombinant SaHV-1. This simple specimen processing technique preserves tissue morphology and allows detection of viral replication within various tissues of experimentally infected animals.

Characterization of gross and histological lesions in Balb/c mice experimentally infected with herpesvirus saimiri 1 (HVS1).

Accidental B virus (Herpesvirus simiae) infection of human beings working with macaques is frequently fatal. However, the pathogenic potential of other similar simian alphaherpesviruses, such as the squirrel monkey virus Herpesvirus saimiri (HVS1), is virtually unknown. As part of an effort to develop a murine model for infections with these agents, Balb/c mice were inoculated intramuscularly in the left hindlimb with 10 to 10(6) plaque forming units (PFU) of HVS1. After observation for clinical signs of infection for 21 days, mice were killed and specimens collected for serology and histopathology. Mice receiving 510(3) PFU of HVS1 exhibited severe, pruritic, ulcerative skin lesions near the site of inoculation and developed unilateral or bilateral hindlimb paralysis with severe muscle atrophy. Histological lesions were characterized by a necrotizing dermatitis and folliculitis. Spinal cord lesions consisted of a non-suppurative myelitis affecting primarily the ipsilateral dorsal horn of the thoracolumbar spinal cord with occasional extension to ventral and contralateral spinal cord regions. Immunohistochemical labelling confirmed the presence of viral antigen within the lesions, and anti-HVS1 IgG concentrations were related to the occurrence of disease. HVS1 infection in some mice extended from the ipsilateral dorsal horn and funiculus into the ventral and contralateral grey and white matter, resulting in bilateral hindlimb paralysis. Thoracolumbar spinal cord lesions resolved without continued spread of the virus to cranial nervous system structures, i.e., cervical spinal cord and brain.

Observations on tissue stages of Hepatozoon americanum in 19 naturally infected dogs.

Lesions and associated tissue stages of Hepatozoon americanum in 19 naturally infected dogs are described. Schizogony takes place in an unidentified host cell which, during the early stages of the asexual cycle, is contained within a broad, multilamellar mucopolysaccharide 'cyst.' Material forming the cyst appears to be host-derived. An intense inflammatory response follows rupture of the schizont and disintegration of the cyst wall. There is unusually intense angiogenesis associated with the resulting granulomatous inflammation initiated by the freed merozoites. Phagocytized zoites enter the canine circulatory system through the walls of these vessels. Evidence is presented that suggests a single infecting episode can cause prolonged (> or = 9 months) infection, and further, that infection is perpetuated by repeated asexual cycles. Parasites in peripheral blood leukocytes include both those with and without a visible nucleus.