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Biomedical subjects

A N Hamir

Publications and source records attributed to A N Hamir.

At least 37 records · Page 2Linked to original sources
PubMed2001

Myocarditis and encephalitis associated with Sarcocystis neurona infection in raccoons (Procyon lotor).

Sarcocystis neurona associated granulomatous encephalitis was found in 2 of 84 adult raccoons. Both raccoons also had an extensive nonsuppurative myocarditis and one had S. neurona schizonts and merozoites in the myocardium. Only the asexual stages (schizonts and merozoites) of S. neurona are found in tissues of naturally infected animals (horse, mink, raccoons, cats, skunk, pony, seals, sea otters) and since these have not been reported outside the central nervous system, the presence of concurrent myocarditis in raccoons with the presence of S. neurona in the current study is of interest. Pathologists should consider the possible association of S. neurona with myocardial inflammation in other S. neurona susceptible animals.

Animals↗
PubMed2001

Prevalence of psammoma bodies in meninges and choroid plexuses of raccoons (Procyon lotor) from Parramore Island, Virginia.

Microscopic evidence of multifocal mineralizations (psammoma bodies) were seen in brains of 33/53 (62%) raccoons (Procyon lotor) necropsied on Parramore Island, Virginia. Most mineralized foci had concentric laminations and were present in small capillaries of meninges of the brain (15/33), in choroid plexus (3/33), or at both these sites (13/33). In 2 raccoons, the lesions were confined to the meninges of the proximal cervical spinal cord. In most cases, the affected vessels appeared to have been completely occluded. However, no evidence of ischemic changes in the brain parenchyma was seen, and none of the raccoons had abnormal neurologic signs prior to euthanasia. The condition appears to be a common incidental histopathologic finding in raccoons from the eastern United States. Although the exact cause of this condition is not known, a primary vascular insult with resultant dystrophic mineralization of the affected vessels is suspected.

Animals↗
PubMed2001

Preliminary findings on the experimental transmission of chronic wasting disease agent of mule deer to cattle.

To determine the transmissibility of chronic wasting disease (CWD) to cattle and to provide information about clinical course, lesions, and suitability of currently used diagnostic procedures for detection of CWD in cattle, 13 calves were inoculated intracerebrally with brain suspension from mule deer naturally affected with CWD. Between 24 and 27 months postinoculation, 3 animals became recumbent and were euthanized. Gross necropsies revealed emaciation in 2 animals and a large pulmonary abscess in the third. Brains were examined for protease-resistant prion protein (PrP(res)) by immunohistochemistry and Western blotting and for scrapie-associated fibrils (SAFs) by negative-stain electron microscopy. Microscopic lesions in the brain were subtle in 2 animals and absent in the third case. However, all 3 animals were positive for PrP(res) by immunohistochemistry and Western blot, and SAFs were detected in 2 of the animals. An uninoculated control animal euthanized during the same period did not have PrP(res) in its brain. These are preliminary observations from a currently in-progress experiment. Three years after the CWD challenge, the 10 remaining inoculated cattle are alive and apparently healthy. These preliminary findings demonstrate that diagnostic techniques currently used for bovine spongiform encephalopathy (BSE) surveillance would also detect CWD in cattle should it occur naturally.

Animals↗
PubMed2001

Diagnosis of preclinical and subclinical scrapie in a naturally infected sheep flock utilizing currently available postmortem diagnostic techniques.

Scrapie is a naturally occurring transmissible encephalopathy of sheep and goats. Currently available methods for diagnosis are the presence of characteristic histopathologic changes and detection of an abnormal form of prion protein (PrPres) in the brains of affected animals. This study documents preclinical and subclinical scrapie in a flock of 16 sheep utilizing histopathology, immunohistochemistry (IHC), western blot, and electron microscopy (for scrapie-associated fibrils) for confirmation of the disease. Prior to necropsy, none of the sheep showed signs of clinical scrapie. Based on the results of histopathology and positive PrPres tests, 3 ewes were found to have subclinical scrapie. An additional ewe, which did not have histopathologic changes in the brain but was positive by IHC and western blot,was considered a preclinical case of scrapie. None of the sheep had amyloid in the brain stem.

Animals↗
PubMed2001

Idiopathic disseminated intracytoplasmic neuronal vacuolation in a neonatal Holstein calf born in the USA.

Histopathologic, immunohistochemical, and ultrastructural evaluations were made of a 6-day-old Holstein calf with severe vacuolation of the neuronal perikarya that was widely distributed throughout the central nervous system. No evidence of storage material within the vacuoles was revealed by histopathologic and ultrastructural examinations. Immunohistochemical and electron microscopic examinations were negative for protease-resistant prion protein and scrapie-associated fibrils, respectively. These results indicate that the clinical signs in this calf were not associated with transmissible spongiform encephalopathy. Neuronal vacuolation has not previously been documented in calves.

Animals↗
PubMed2001

Naturally occurring spirochetes in the colonic mucosa of raccoons (Procyon lotor).

The large intestines of 21 raccoons (Procyon lotor; 11 wild caught, 10 laboratory confined) were examined for the presence of intestinal spirochetes. Light microscopy of sections stained with hematoxylin and eosin and Warthin-Starry stain showed the presence of spiral shaped organisms deep within the lumina of intestinal glands at the ileocolonic junction of 16 raccoons (76% prevalence). All laboratory-confined, group-housed raccoons harbored the organisms, but only 6/11 (55% prevalence) live-trapped raccoons were positive for these spirochetes. The organisms were free in the glandular lumina, and there were no microscopic lesions. Two types of spirochetes were identified in the colonic glands: a slender spirochete 10-13 microm in length, 0.3 microm in diameter, and possessing long, thin tapered ends and a larger, regularly waved spiral organism (0.5 microm in diameter). The slender spirochete did not resemble any of the known spirochete genera and failed to grow on medium used to propagate oral treponemes and members of the genus Brachyspira.

Animals↗
PubMed2001

Resistance of cattle to scrapie by the oral route.

Early epidemiological information indicated that bovine spongiform encephalopathy (BSE) originated from scrapie in sheep. The question arose if scrapie in North America would induce a BSE-like disease in cattle. Six years ago, we reported that brain tissue from sheep with scrapie caused a neurologic disease when injected directly into the brains of cattle, but the disease induced was different from BSE as it occurs in the United Kingdom and Europe. Here, we report that cattle fed raw brain or meat and bone meal and tallow prepared from sheep with scrapie remained normal for 8 years after exposure. This work indicates that cattle are highly resistant to North American scrapie by the oral route.

Animals↗
PubMed2001

The prevalence of interstitial nephritis and leptospirosis in 283 raccoons (Procyon lotor) from 5 different sites in the United States.

A retrospective histopathological study was carried out on tissues of 283 raccoons from 5 different geographical locations for presence of interstitial nephritis and renal leptospirosis. Results of this study indicate that although interstitial nephritis was common in raccoons from all locations, the presence of renal leptospiral spirochetes was not.

Animals↗
PubMed2000

Preclinical diagnosis of scrapie by immunohistochemistry of third eyelid lymphoid tissue.

Ovine scrapie is a member of the transmissible spongiform encephalopathies (TSEs), a heterogeneous family of fatal neurologic disorders characterized by deposition of an abnormal isoform (prion protein [PrP] PrP-Sc) of a cellular sialoglycoprotein in neural tissue. PrP-Sc is detectable in some lymphoid tissues of infected sheep months or years before development of clinical disease. Detection of PrP-Sc in these tissues is the basis for live-animal testing. In this study, we characterize the performance of a preclinical diagnostic test for ovine scrapie based on a monoclonal antibody (MAb)-based immunohistochemistry assay of nictitating membrane ("third eyelid")-associated lymphoid tissue. The results of third eyelid immunohistochemistry assay agreed with the scrapie status of the sheep for 41 of 42 clinical suspects with confirmed scrapie and 174 of 175 sheep without scrapie. Third eyelid sampling agreed with the scrapie status for 36 of 41 clinically normal sheep positive for PrP-Sc immunostaining of brain tissue, including 27 sheep with positive biopsy specimens that progressed to clinical disease with confirmed scrapie 3 to 20 months after biopsy. The assay used MAb F89/160.1.5, which binds to residues 142 to 145 of ovine PrP. This antibody can be used in combination with MAb F99/97. 6.1, which binds to residues 220 to 225. One or both MAbs in this cocktail recognize PrP sequences conserved in most mammalian species in which natural TSEs have been reported. Immunohistochemistry assay of routinely formalin-fixed lymphoid tissues with a cocktail of pan-specific MAbs is a practical, readily standardized live-animal and preclinical test for ovine scrapie.

Animals↗
PubMed2000

Hepatic capillariasis (Capillaria hepatica) in porcupines (Erethizon dorsatum) in Pennsylvania.

Tissues of 53 adult porcupines (Erethizon dorsatum) from Pennsylvania were obtained for histopathologic examination. Hepatic capillariasis was recorded in 9% of the porcupines. An additional 11% of the liver sections showed lesions that were compatible with migration by Capillaria hepatica. Because only 1 section of the liver per animal was examined microscopically, the documented prevalence of C. hepatica in Pennsylvania is considered conservatively low. However, this condition was subclinical, because none of the infected animals showed clinical signs, and none revealed severe pathologic changes in the affected livers. This seems to be the only report of C. hepatica in porcupines.

Animals↗
PubMed2000

Immunohistochemical confirmation of Sarcocystis neurona infections in raccoons, mink, cat, skunk, and pony.

In the central nervous system of 2 raccoons, 1 cat, 1 pony, 2 mink, and 1 skunk, protozoa previously thought to be Sarcocystis-like reacted positively to Sarcocystis neurona-specific antibodies in an immunohistochemical test. In addition, S. neurona was identified in the brain of another skunk. These observations indicate that S. neurona is not confined to opossums and horses.

Animals↗
PubMed1999

Use of capillary electrophoresis and fluorescent labeled peptides to detect the abnormal prion protein in the blood of animals that are infected with a transmissible spongiform encephalopathy.

Transmissible spongiform encephalopathies in humans and in animals are fatal neuro-degenerative diseases with long incubation times. The putative cause of these diseases is a normal host protein, the prion protein, that becomes altered. This abnormal prion protein is found mostly in the brains of infected individuals in later stages of the disease, but also can be found in lymphoid and other tissues in lower amounts. In order to eradicate this disease in animals, it is important to develop a system that can concentrate the abnormal prion protein and an assay that is very sensitive. The sensitivity that can be achieved with capillary electrophoresis makes it possible to detect the abnormal protein in blood. A peptide from the carboxyl terminal region, amino acid positions 218-232, was labeled with fluorescein during the synthesis of the peptide at the amino terminus. Antibodies that have been produced to this peptide were affinity purified and used in a capillary electrophoresis immunoassay. The amount of fluorescein labeled peptide in the capillary was 50 amol. Blood was obtained from normal sheep and elk, from sheep infected with scrapie and elk infected with chronic wasting disease. Buffy coats and plasma were prepared by a conventional method. After treatment with proteinase K, which destroys the normal protein but not the altered one, the blood fractions were extracted and tested in the capillary electrophoresis immunoassay for the abnormal prion protein. The abnormal prion protein was detected in fractions from blood from infected animals but not from normal animals. This assay makes a pre-clinical assay possible for these diseases and could be adapted to test for the abnormal prion protein in process materials that are used for manufacture of pharmaceuticals and products for human consumption.

Amino Acid Sequence↗
PubMed1999

Experimental lead toxicosis of raccoons (Procyon lotor).

Four pairs of raccoons were treated orally with the following doses of lead acetate (mg/kg; 5 days/week, for 8 weeks): 0 (control), 1, 2 and 4. In the six experimental animals, this treatment produced dose-dependent increases in blood lead, without clinical signs or changes in haematological parameters. After 8 weeks, the liver and kidney of all lead-treated animals and the calvarium and radius of those receiving doses of 2 and 4 mg/kg contained elevated concentrations of lead. Acid-fast inclusions were observed by light and electron microscopy in the kidneys of all raccoons receiving the two highest doses and in one animal receiving the lowest dose. Hepatic acid-fast inclusions were seen in only one animal (dose 4 mg/kg). No inclusions were seen in osteoclasts of the radius. It is suggested that the findings, which support earlier observations that raccoons are fairly resistant to lead, may be of value in studying interactions between lead exposure and oral vaccination of wildlife against rabies.

Administration, Oral↗
PubMed1999

Neuronal vacuolation in raccoons from Oregon.

During a 2-year period (1995-1997), vacuoles were detected in neurons of 21/50 (42% prevalence) raccoons (Procyon lotor) in Oregon. Age or sex predisposition was not apparent. Twenty of these raccoons were from within a radius of 40 km of Corvallis in western Oregon. Microscopically, the vacuoles were variable in size, were in the perikarya, and were consistently present in pontine nuclei. Brain tissues were negative for rabies virus antigen by fluorescent antibody test and for the protease-resistant protein prion by immunohistochemistry. Electron microscopic examination of the brain stem of selected animals revealed accumulation of electron-dense material within neuronal perikarya. Light and electron microscopic examination indicated that the accumulated intracellular material had a high lipid content. These lesions suggest a form of neuronal storage condition. Further research is required to identify the composition of the intracellular lipid material, to elucidate the mechanism of neuronal vacuolation in raccoons, and to understand the basis for the apparent geographic restriction of this lesion.

Animals↗