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D H Percy

Publications and source records attributed to D H Percy.

At least 55 records · Page 3Linked to original sources
PubMed1986

Activation of int-1 and int-2 loci in GRf mammary tumors.

The Mtv-2 locus is known to be associated with a high mammary tumor incidence (97%) and early development of mammary tumors (3-13 months) in GR mice. However, it was not previously known whether the provirus which resides at the Mtv-2 locus is tumorigenic in and of itself or whether reintegration of proviruses generated from Mtv-2 is required for tumorigenesis. Foster-nursing GR mice on C57/BL mice eliminates the milk-borne source of GR virus, and allows the study of Mtv-2 derived proviruses alone. Using this approach, we have tested predictions which follow from the "positional" versus "reintegrational" models of tumorigenesis. Specifically, we have examined tumors from primary foster-nursed (GRf) mice to determine if MMTV proviruses derived from Mtv-2 were scattered randomly throughout the genome or were clustered in the vicinity of the int-1 and int-2 loci, which are thought to be associated with mammary tumorigenesis. It was found that the majority of spontaneous GRf mammary tumors that were tested have MMTV proviral integrations in either or both of the int-1 and int-2 loci and have transcription of either or both of the int loci. Tumors induced by Mtv-2, therefore, appear to have arisen via a mechanism similar to the activation of the int loci by exogenous (milk-borne) MMTV proviruses.

Animals↗
PubMed1986

An unusual form of motor neuron disease following a cat bite.

A case of motor neuron disease with clinical and pathological resemblance to amyotrophic lateral sclerosis (ALS) in a woman who was severely bitten on the ankle by a cat is described. Weakness first appeared at the ankles and relentlessly advanced proximally, terminating in death from pulmonary failure in a year. A number of unusual features that are uncharacteristic of ALS were found that included a markedly elevated antinuclear antibody titre in the serum and the presence of prominent oligoclonal bands in the cerebrospinal fluid. The spinal cord showed loss of anterior horn cells and pyramidal degeneration that are characteristic of ALS, but an extraordinary finding was the presence of transmural granulomatous inflammation of numerous small and medium sized vessels, especially veins, in the subarachnoid space around the cord. There were also inflammatory changes in the brainstem and spinal cord consisting of microglial and astrocytic nodules and perivenous cuffing by mononuclear cells. Ill-defined hyaline eosinophilic cytoplasmic inclusions were seen in some remaining anterior horn cells. No viral particles were found by electron microscopy despite an extensive search. Virological studies were inconclusive but there is reason to believe that this patient's illness was caused by an as yet unidentified virus.

Amyotrophic Lateral Sclerosis↗
PubMed1986

Central nervous system lesions in suckling mice and rats inoculated intranasally with sialodacryoadenitis virus.

Suckling CD-1 and CFW mice and WI Wistar rats were inoculated intranasally with sialodacryoadenitis virus. In animals inoculated during the first week of life, there was an acute necrotizing encephalitis with malacia and minimal inflammatory cell response. In mice and rats which survived for up to 12 days post inoculation, loss of brain substance, gitter cells and occasionally mineralized debris were seen. Viral antigen was readily demonstrated in neurons and nasal epithelium in trypsin-treated, paraffin-embedded sections, and corresponded with the presence of lesions. There was no compelling evidence that sialodacryoadenitis virus invaded the central nervous system directly via the cribriform plate, and hematogenous spread was considered to be a likely route of spread to the brain. An age-related resistance to the encephalitic form was evident beginning at 10 days of age in both species. Thus it is conceivable that encephalitis could occur in young suckling rats exposed during naturally-occurring epizootics of sialodacryoadenitis.

Animals↗
PubMed1986

Sialodacryoadenitis virus-associated lesions in the lower respiratory tract of rats.

Eight- to 10-week-old outbred Wistar rats were inoculated intranasally with 10(2.9) medium mouse lethal infective doses of sialodacryoadenitis (SDA) virus. Sham inoculated control rats and challenged rats were killed at 1 day intervals for the first 8 days, then on days 10, 12, 14, and 20. Typical lesions associated with SDA were seen microscopically in the salivary and lacrimal glands of inoculated rats. In addition, laryngitis, tracheitis, bronchitis, bronchiolitis, and multifocal alveolitis were present during the acute stages of the disease. Viral antigen was demonstrated in epithelial cells lining airways by immunofluorescence microscopy. SDA virus was recovered from the lower respiratory tract from days 2 to 6 post-inoculation (PI). Serum antibodies to SDA virus, but not to Sendai virus or Mycoplasma pulmonis were present in rats tested at day 20 PI. These findings demonstrate that during the acute stages of the disease, significant lesions do occur in the lower respiratory tract of SDA virus-infected rats.

Animals↗
PubMed1986

Experimental pneumonia in rabbits inoculated with strains of Pasteurella multocida.

Domestic rabbits were inoculated with either a 3:A or 3:D serotype of Pasteurella multocida by aerosol, intravenous, or intratracheal inoculation. Different colony forming units of P. multocida were used. Animals which died or were killed after the 14 day observation period were examined macroscopically and microscopically for lesions in the lower respiratory tract. Pneumonic lesions were most consistently produced in rabbits inoculated intratracheally with serotype 3:A. Pulmonary and pleural lesions were observed in some animals inoculated intravenously with serotype 3:A. Lesions were minimal in rabbits inoculated with serotype 3:D. Of the three routes of inoculation evaluated, the intratracheal route appeared to be the best method to produce Pasteurella-associated lesions in the lower respiratory tract.

Animals↗
PubMed1985

Pasteurella multocida infection in the domestic rabbit: immunization with a streptomycin-dependent mutant.

Fourteen Pasteurella multocida-free rabbits were inoculated intranasally with a streptomycin-dependent mutant of P. multocida serotype 12:A. Vaccinations with approximately 10(8) colony forming units were done on days 0, 14 and 28. Two weeks later the animals were separated into groups, which included 12 rabbits divided into two control groups of six unvaccinated Pasteurella-free animals. Seven vaccinated rabbits were challenged intranasally with the homologous virulent parent strain and the other seven vaccinates were challenged with a virulent strain of serotype 3:A. Rabbits were necropsied two weeks later. The vaccinated group challenged with the parent strain showed a more rapid nasal clearance of the organism than the vaccinated group challenged with the heterologous strain. However, the number of positive cultures of P. multocida recovered from tissues post-challenge were similar in vaccinated and control animals. In a significant number of animals, vaccination with serotype 12:A induced detectable antibody production to somatic antigens of both 12:A and heterologous strain 3:A.

Animals↗
PubMed1984

Suppression of experimental allergic encephalomyelitis in Lewis rats treated with myelin basic protein-liposome complexes: clinical, histopathological, and cell-mediated immunity correlates.

Guinea pig myelin basic protein (MBP) was inserted into phosphatidylserine liposomes and Lewis rats were injected by the intracardiac (ic) route with 75 microgram doses of MBP-liposomes according to various schedules. After challenge with 75 microgram guinea pig MBP in complete Freund's adjuvant, the rats were followed for clinical signs, were tested for delayed hypersensitivity (DTH) and lymphocyte transformation (LT) to MBP. The animals were sacrificed 30 days after challenge and the central nervous system tissue was examined for histological modifications. Rats treated with two injections of MBP-liposomes, 7 days before and 7 days after challenge, showed the highest degree of protection from clinical manifestations. Histological lesions were not significantly reduced. DTH reactions to MBP were all positive, regardless of treatment. LT assays were positive overall in only 50% of the animals tested. The response to rat MBP was significantly lower than to guinea pig MBP, especially in the groups treated with MBP-liposomes. Adoptive transfer of spleen cells from MBP-liposome-treated donors reduced the clinical scores of actively induced EAE in syngeneic recipients by 40-50%. These results suggest that at least one mechanism responsible for antigen-specific protection in EAE by MBP-liposomes operates through active suppression transferable by spleen cells.

Animals↗
PubMed1984

Characterization of murine hepatitis virus (JHM) RNA from rats with experimental encephalomyelitis.

When Wistar Furth rats are inoculated intracerebrally with the murine hepatitis virus JHM they often develop a demyelinating disease with resulting hind leg paralysis. Using an RNA transfer procedure and hybridization kinetic analysis, the virus-specific RNA in these rats was characterized. The pattern of JHM-specific RNA varied with individual infections of Wistar Furth rats. However, two species of JHM-specific RNA, the nucleocapsid and a 2.1-2.4 X 10(6)-Da RNA species were generally present. A general decrease in JHM-specific RNA in brains and spinal cord samples taken later than 20 days postinoculation was observed; however, JHM-specific RNA persisted in the spinal cord longer than in the brain of these rats.

Animals↗
PubMed1984

Comparison of strain susceptibility to experimental sialodacryoadenitis in rats.

Wistar, Sprague-Dawley, and Long-Evans outbred rats, and the Fischer344 inbred strain were inoculated intranasally with 10(3) TCID50 of sialodacryoadenitis virus at approximately 9 weeks of age. Paired animals were killed at 2-day intervals post inoculation up to 2 weeks, then at 20 days. A comparison of strain susceptibility to sialodacryoadenitis virus was made using the following criteria: histopathology, immunofluorescent microscopy, serology and serum amylase activity. All four strains were susceptible to sialodacryoadenitis virus. The disease was frequently subclinical, although typical lesions were observed on histopathology. Focal bronchitis, bronchiolitis and pneumonitis were observed histologically during the acute stages of the disease. Immunohistochemistry was performed on trypsin-treated, paraffin-embedded sections, and viral antigen was readily demonstrated in salivary and lacrimal glands during the early stages of the disease. A rise in serum amylase was observed, and it was correlated with the first appearance of lesions in the salivary glands. Based on serology and immunofluorescence microscopy, the appearance of detectable antibody to sialodacryoadenitis virus, and the rate of viral clearance from infected glands, the course of the disease was similar in the four strains studied.

Amylases↗
PubMed1984

Sialodacryoadenitis in the rat: effects of immunosuppression on the course of the disease.

Eight-week-old outbred male and female Crl:CD(SD)BR rats were treated with prednisolone (PR) or cyclophosphamide (CY) and were inoculated intranasally with sialodacryoadenitis (SDA) virus. The course of the disease was compared with nonimmunosuppressed, SDA virus-inoculated rats of the same stock. Criteria used to compare SDA in the 3 groups, included histologic changes in salivary and lacrimal glands, immunofluorescent microscopy of paraffin-embedded tissues, serum amylase levels, and antibody response. Based on these criteria, there was little detectable difference in the course and intensity of SDA in PR-treated and nonimmunosuppressed rats. In CY-treated rats, there was a delay in the onset of SDA, in the appearance of inflammatory cells in affected glands, and in the reparative process in the salivary and lacrimal glands. Viral antigen persisted longer in CY-treated rats than in PR-treated and nonimmunosuppressed rats. Antibody to SDA virus was not detected in CY-treated rats. The efficacy of immunosuppression by PR and CY was confirmed by the sheep erythrocyte agglutination procedure performed in selected rats. Male and female rats of the same strain were immunosuppressed beginning 4 weeks after inoculation with SDA virus to produce recrudescence of the disease. Histologic examination of salivary and lacrimal glands, immunofluorescent microscopy, serum amylase values, and viral isolation studies did not reveal evidence of reactivation of a persistent viral infection or viral shedding. Based on these studies, there is no evidence that SDA virus may persist as an inapparent infection after recovery from the disease.

Amylases↗
PubMed1984

Experimental herpetic keratitis in rabbit corneal organ cultures.

An in-vitro method for maintaining rabbit corneal organ cultures for short periods of time is described. These cultures supported replication of strains of type 1 and 2 herpes simplex virus, and changes typical of herpetic infections of the cornea in vivo were observed by light microscopy, and by scanning and transmission electron microscopy. Infectious virus was readily recovered from inoculated corneal organ cultures. For practical, economic and humanitarian reasons, the full potential of this system warrants further investigation.

Animals↗
PubMed1984

Characterization of Pasteurella multocida isolated from rabbits in Canada.

In a survey for the somatic and capsular serotypes of Pasteurella multocida present in domestic rabbits in Canada, but mainly in Ontario, samples were obtained from research facilities, commercial rabbitries and from abattoir and necropsy specimens. Sources of isolates were upper respiratory tract infections, localized bronchopneumonias , acute fibrinous pneumonias, abscesses and otitis media. Of 59 isolates obtained, 47.0% were type 12:A, 30.5% 3:D and 12.0% were 3:A. Less common types were 12(4):A, 12:D, 4(12):A and 3:untypable. Somatic group 3 was most commonly isolated from acute pneumonic disease, while serogroup 12:A was most commonly found in upper respiratory tract infections and in localized chronic bronchopneumonia. Two serotypes of P. multocida were isolated from four pneumonic lungs collected from abattoir specimens. Most isolates were susceptible to the commonly used antibiotics.

Abattoirs↗
PubMed1983

Leptomeningitis and polycaryocyte formation in the CNS of rats inoculated subcutaneously with herpes simplex virus.

Wistar rats were inoculated subcutaneously with either type 1 (HSV1) or type 2 (HSV2) Herpes simplex virus at 5 days of age. Animals were killed in extremis or at the end of the 14-day observation period postinoculation. Acute destructive meningoencephalitis with hemorrhage and leukocytic infiltration was observed in both groups. Polycaryocytes comprised of cells of the internal granular layer of the cerebellum were observed in some animals inoculated with HSV1. These multinucleated cells appeared to be formed by fusion of virus-infected cells, and intranuclear inclusion bodies were observed. Lesions in the leptomeninges were particularly striking in animals inoculated with HSV2. Viral replication in resident cells of the leptomeninges was demonstrated by electron microscopy.

Animals↗