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Biomedical subjects

A N Hamir

Publications and source records attributed to A N Hamir.

At least 91 records · Page 5Linked to original sources
PubMed1993

Detection of antibodies against Borna disease virus in sera and cerebrospinal fluid of horses in the USA.

Sera from 295 horses in the USA were examined by an indirect immunofluorescence assay and Western blot assays to determine the prevalence of Borna disease virus infection. Eight (2.7 per cent) of the samples were positive in both assays, and 18 (6.1 per cent) were positive only in the Western blot assay. The indirect fluorescence titres ranged from 1:20 to 1:80 of antibodies recognising the virus-specific antigen from Borna disease virus-infected cells. The purified virus-specific proteins isolated from infected rat brains were recognised by positive equine serum samples after immunostaining by a Western blot technique. Information obtained from the owners about the history of the seropositive horses revealed that they were either clinically normal or had a pathological diagnosis of disease unrelated to Borna disease. This is the first report of the detection of antibodies to Borna disease virus in horses in the USA. The disease may be more widespread in a subclinical form, with very long incubation periods, and may not necessarily be restricted to historically endemic areas.

Animals↗
PubMed1993

Immunohistochemical study to demonstrate Sarcocystis neurona in equine protozoal myeloencephalitis.

A 5-year (1985-1989) retrospective immunohistochemical study was conducted using an avidin-biotin complex (ABC) immunoperoxidase method to demonstrate Sarcocystis neurona in histologically suspect cases of equine protozoal myeloencephalitis (EPM). Primary antibodies against S. neurona and S. cruzi were utilized for the ABC technique. The findings were compared with those from cases in which the organisms were detected by examination of hematoxylin and eosin (HE)-stained neuronal sections. HE-stained sections detected the presence of the organisms in 20% of the suspect cases; whereas the ABC technique confirmed the presence of S. neurona in 51% and 67% of the cases by S. neurona and S. cruzi antibodies, respectively. A review of clinical case histories showed that 21/47 (45%) of the EPM horses with parasites in the tissue sections had prior treatment with antiprotozoal drugs and/or steroids. Using the test results of S. neurona and S. cruzi as a standard reference, HE test sensitivity based on examination of up to 30 neuronal sections per case was only 25%, and test specificity was 91%.

Animals↗
PubMed1993

First report of a Demodex sp. in raccoons (Procyon lotor).

Demodex spp. mites were seen in skin sections of 5 of 53 raccoons (Procyon lotor) necropsied on Parramore Island, Virginia (USA). In all infections, mites were present in the skin over the lower legs; in one raccoon they also were located in a follicle of a vibrissa. None of the raccoons had Demodex-related gross lesions. Histopathologically, minimal lesions were seen in the affected follicles. This is the first documentation of Demodex spp. in raccoons.

Animals↗
PubMed1993

Experimental Toxoplasma gondii infection in raccoons (Procyon lotor).

Six raccoons (Procyon lotor) without detectable Toxoplasma gondii antibodies were used. Four raccoons were inoculated orally (2 with oocysts and 2 with tissue cysts) with ME49 strain of T. gondii and 2 raccoons were not inoculated with T. gondii. All raccoons remained clinically normal. Raccoons were killed between 59 and 61 days after inoculation and portions of their heart, skeletal muscle, and brain were digested in pepsin solution, and homogenates were bioassayed in mice. Toxoplasma gondii was isolated from all 4 inoculated raccoons; from the heart of 3, skeletal muscles of 2 and the brain of none. All 4 inoculated raccoons developed antibody titers > or = 1:1,600 in the modified direct agglutination test (MAT) using whole formalinized tachyzoites. Toxoplasma gondii antibody titers of the raccoons not inoculated with T. gondii remained < 1:25, and T. gondii was not isolated from their tissues. It was concluded that muscle tissue from multiple sites including the heart was the tissue of choice for conducting parasitologic surveys for T. gondii in raccoons. Evaluation of the sera of the experimentally infected raccoons in the Sabin-Feldman dye test, latex agglutination test, and the indirect hemagglutination tests indicated that the MAT detected antibodies faster and in higher titers than did the other serological tests.

Agglutination Tests↗
PubMed1992

Gastric leiomyosarcoma in a horse.

Gastric leiomyosarcoma was diagnosed in a 12-year-old Thoroughbred gelding. The horse was examined because of anorexia, weight loss, and intermittent fever of 1.5 months' duration. Antemortem diagnostic testing was extensive, but a definitive diagnosis could not be reached with noninvasive methods. Exploratory celiotomy confirmed an intra-abdominal mass, and the horse was euthanatized. Necropsy revealed a firm mass associated with the distal portion of the esophagus, cranial two thirds of the stomach, and visceral surface of the liver. The histopathologic diagnosis was leiomyosarcoma.

Animals↗
PubMed1992

Prevalence of Toxoplasma gondii infection in raccoons.

Serum samples from 427 raccoons (93 from Pennsylvania, 45 from New Jersey, 72 from South Carolina, 68 from Virginia, 30 from Iowa, and 119 from Ohio) were evaluated for Toxoplasma gondii antibodies in dilutions of 1:25, 1:50, and 1:500. The distribution of T gondii antibody titers was less than 1:25 for 212 raccoons (49.6%), 1:25 for 34 raccoons (7.9%), 1:50 for 117 raccoons (27.4%), and greater than or equal to 1:500 for 64 raccoons (14.9%). Tissue cysts were seen in the liver, and tachyzoites were in the brain of a raccoon with abnormal neurologic signs and concurrent infection with canine distemper virus. Organisms in the liver were stained with anti-T gondii serum, and the raccoon had a T gondii titer of 1:160 in the agglutination test.

Animals↗
PubMed1992

A five year (1985-1989) retrospective study of equine neurological diseases with special reference to rabies.

A retrospective study of horses necropsied between 1985 and 1989 at a diagnostic laboratory of a veterinary school in North America is documented. In this investigation over 20 per cent of the horses had clinical neurological signs. Equine protozoal myeloencephalitis (caused by Sarcocystis neurona) and cervical stenotic myelopathy (wobbler syndrome) were the most common of these disorders. The veterinary school is located in the midst of a raccoon rabies enzootic area. However, only four cases of equine rabies were diagnosed during the 5-year study. The gross microscopical and immunohistochemical findings from these rabies-positive horses are documented. Immunoperoxidase tests for detection of rabies antigen in another 35 horses with non-specific encephalitis/encephalopathy did not reveal any positive cases. Based on this investigation, it appears that immunoperoxidase is a valid method for diagnosis of rabies when fresh tissues are not available for the fluorescent antibody test. It is also concluded that no cases of equine rabies were overlooked by the diagnostic laboratory during the period under investigation.

Animals↗
PubMed1992

Kinetics of virus spread and changes in levels of several cytokine mRNAs in the brain after intranasal infection of rats with Borna disease virus.

We have used the reverse transcriptase-polymerase chain reaction technique to gain insight into the pathogenesis of encephalitis caused by Borna disease virus (BDV). RNA specific for BDV was first detected in the olfactory bulb of intranasally infected rats at 6 days postinfection (p.i.). At 14 days p.i., high levels of BDV RNA were found in all brain regions, and at 26 days p.i., BDV-specific RNA was also present in the eye, nasal mucosa, and facial skin. In the chronic phase of the disease, BDV RNA was identified in many peripheral organs but not in blood. Analysis of brain tissue for the presence of cytokine mRNAs revealed that the mRNA levels of interleukin-6 (IL-6), tumor necrosis factor alpha, and IL-1 alpha had increased sharply at 14 and 26 days p.i. These cytokine mRNAs reached maximum levels at the peak of inflammatory reactions and decreased drastically in the chronic phase of the disease. Although IL-2 mRNA was also found in normal brain, it was markedly increased in BDV-infected brain at 14 days p.i. Expression of gamma interferon (IFN-gamma) mRNA, which was not observed in normal rat brain, was detected at 14 days p.i. and reached a maximum level at 38 days p.i. IL-2 and IFN-gamma mRNA expression correlated with expression of CD4 and CD8 mRNAs, indicating that both CD4+ and CD8+ T lymphocytes are induced in the early stages of BDV infection. Since IFN-gamma and CD8 mRNA levels were still highly elevated in the chronic phase of Borna disease, it is likely that CD8+ T lymphocytes act to reduce inflammation and to ameliorate neurological signs during the chronic phase of infection.

Animals↗
PubMed1992

Experimental oral administration of canine adenovirus (type 2) to raccoons (Procyon lotor).

Canine adenovirus type 2 (CAV2) has been proposed for recombinant vaccines to control rabies in wild animals. To evaluate the suitability of CAV2 as a safe vector for the genetically engineered vaccines, seven wild-caught raccoons (three males and four females) were administered CAV2 per os. Two of the animals were euthanatized on each of post-infection days 3, 6, and 14, and one was euthanatized on day 21. Two other control raccoons (a male and a female) were also euthanatized on day 21. Microscopic pulmonary lesions of multifocal necrotizing bronchiolitis with basophilic intranuclear inclusions were seen in 3/4 raccoons euthanatized on post-infection days 3 and 6. Ultrastructural examination of lungs with pulmonary lesions revealed hexagonal viral particles characteristic of adenoviruses. CAV2 is potentially pathogenic for raccoons, and this susceptibility should be of concern to developers of recombinant vaccines who intend to use CAV2 as a vaccine vector.

Adenoviridae↗
PubMed1992

Equine keratoma.

Explore the source record for details and available documents.

Animals↗
PubMed1992

Retrospective study of testicular degeneration in raccoons with canine distemper infection.

A 6-year (1985-1990) retrospective survey of raccoons with canine distemper infection and an outbreak of the disease in 1988 on South Island, South Carolina, are described. During this epizootic, 3 male raccoons with the clinical disease had gross testicular lesions that, on histopathologic examination, revealed severe diffuse degeneration and mineralization of seminiferous tubules. The testicular pathology of canine distemper in raccoons has not been previously reported.

Animals↗
PubMed1992

Morphologic and immunoperoxidase study of neurologic lesions in naturally acquired rabies of raccoons.

Histopathologic (hematoxylin and eosin [HE]) and immunoperoxidase (streptavidin-biotin complex) methods were used for examination of formalin-fixed tissues of rabid raccoons from an enzootic area of Pennsylvania. Extensive morphologic lesions of rabies encephalitis were present in the cerebrum and the brain stem regions. Negri bodies were detected by both methods and were present in the brain (cerebral cortex, hippocampus, brain stem, cerebellum, and cervical spinal cord) and in the ganglia of the trigeminal nerves. The viral inclusions were also seen in ganglion cells in the tongue, parotid salivary glands, pancreas, intestines, and adrenal glands. These sites were not associated with any inflammatory cellular infiltrate. The immunoperoxidase method was superior to HE for the detection of Negri bodies. Because lesions of rabies encephalitis were consistently observed in the cerebrum, brain stem, and cervical spinal cord regions, these areas of the brain should be included when raccoons are examined by the fluorescent antibody test for rabies.

Animals↗
PubMed1992

Prerequisites for oral immunization of free-ranging raccoons (Procyon lotor) with a recombinant rabies virus vaccine: study site ecology and bait system development.

A model baiting system suitable for the delivery of an oral rabies vaccine to free-ranging raccoons (Procyon lotor) was developed and tested on barrier islands in South Carolina (USA). Features of barrier island physiography and ecology were studied relative to selective bait deployment and site biosecurity. Capture-mark-recapture data were obtained from 228 raccoons. Raccoon density estimates, using a modified census assessment technique, were one raccoon per 1.8 to 2.7 ha. Mean (+/- SE) and range home area estimates of radio-collared raccoons were 84 (+/- 15.6) ha (27 to 176 ha) by a minimum convex polygon method and 138 (+/- 22.8) ha (43 to 241 ha), by a harmonic mean transformation method. Habitat utilization determinations of radio-collared raccoons were conducted to identify study areas to potentially maximize selectivity of bait towards raccoons and to reduce the absolute number of baits deployed. Island raccoons showed a habitat preference for maritime forest, maritime shrub and marsh areas. Additionally, there was no evidence of inter-island or mainland exchange of ear-tagged or radio-collared raccoons. A disease and mortality survey was conducted to identify baseline pathology and incidental lesions in the target raccoon population, prior to actual vaccination initiation. Thirty-eight percent of 30 clinically suspect raccoons sampled had intracytoplasmic eosinophilic inclusions diagnostic of canine distemper; no other lesions suggestive of viral etiologies were found. Serological surveys for raccoon poxvirus and rabies virus antibodies were negative. Antibody titers to canine adenovirus 1 and 2 indicated a moderate level of exposure (approximately 10 to 16%) in the raccoon population. Overall, 93 to 100% of placebo baits were consistently disturbed by 7 days post-bait deployment, and bait acceptance rates by raccoons ranged from 49 to 85%, by using a modular systems approach to select the optimum combination of bait attractant, biomarker, matrix, density, and distribution. These results suggest that a large proportion (up to 85%) of a free-ranging island raccoon population can be selectively and safely targeted, marked and monitored utilizing a proposed oral bait delivery system for recombinant or other rabies vaccines.

Administration, Oral↗
PubMed1992

Isolation of Mycobacterium paratuberculosis after oral inoculation in uninfected cattle.

Feces from cows naturally infected with Mycobacterium paratuberculosis was given to 6 uninfected heifers by orogastric intubation, to determine whether ingested organisms could be passively excreted and detected by bacteriologic culture of feces (ie, false-positive result). Heifers were paired, and each pair received a different dose of feces on days 1 and 2. Fecal samples were collected from the heifers 3 times daily. Mycobacterium paratuberculosis was detected in fecal samples of all heifers within 18 hours of being given the first dose of feces. The number of colony-forming units peaked on days 3 or 4, and organisms were no longer detected by day 7. The number of colony-forming units in fecal samples from the heifers was approximately proportional to the dose given. On days 15 and 16, the experiment was repeated with feces from a second infected cow. Results were similar to those in the first experiment. All heifers remained seronegative (agar-gel immunodiffusion test and ELISA) and had negative results to the intradermal johnin test throughout the experiment. Lymph node and intestinal tissues were obtained from all 6 heifers at slaughter on day 28. Mycobacterium paratuberculosis was not isolated from mesenteric lymph nodes from the ileocecal valve region, but was isolated from ileal mucosal samples from each heifer.

Animals↗
PubMed1992

Neospora caninum (Apicomplexa) in a stillborn goat.

Tissue cysts of Neospora caninum were found in sections of brain from a stillborn pygmy goat. The tissue cysts had 1-2-microns-thick cyst walls and stained with anti-N. caninum serum in an immunohistochemical test. Glial nodules, mononuclear perivascular cuffing, and foci of inflammation were associated with N. caninum tissue cysts throughout the brain. This report indicates that N. caninum can be transmitted transplacentally in goats.

Animals↗
PubMed1991

Lymphosarcoma with urinary bladder infiltration in a horse.

A 9-year-old Thoroughbred mare was examined because of pollakiuria, hematuria, and weight loss of 3 weeks' duration. Physical examination revealed a regular cardiac rhythm with occasional premature contractions, and a soft tissue mass in the pelvic canal palpable per rectum. Microscopic examination of urine sediment revealed numerous RBC and a large population of lymphocytes and lymphoblasts with characteristics of neoplasia. Similar cells were found in peritoneal fluid obtained by abdominocentesis. The horse was euthanatized without treatment. Necropsy revealed a soft tissue mass infiltrating the bladder, vagina, and uterus. Additional masses were found in the sublumbar muscles and myocardium. The histologic diagnosis was lymphosarcoma.

Animals↗