Biomedical subjects

D D Copeland

Publications and source records attributed to D D Copeland.

21 records · Page 2Linked to original sources

PubMed1977

Influence of age at inoculation on avian oncornavirus-induced brain tumor incidence, tumor morphology, and postinoculation survival in F344 rats.

Intracranial neoplasms were induced by intracerebral inoculation of a standardized, cell-free inoculum of the Bratislava-77 strain of avian sarcoma virus in F344 rats at 1, 9,97 to 99, and 528 days of age. Deaths from diseases that occur spontaneously in aged F344 rats complicated assessment of tumor incidence in rats inoculated at 528 days; 20 of 30 rats inoculated at this age developed brain tumors. All rats inoculated at age 1 day (47 rats), at age 9 days (37 rats), and at 97 to 99 days of age (41 rats) developed brain tumors. The incidence of animals developing tumors was 100% in these three groups, but the incidence of multiple tumors declined with increasing age at inoculation. The mean and variance of postinoculation survival increased from 83.8 +/- 21.5 days for rats inoculated at 1 day of age to 284.6 +/- 151.5 days for rats inoculated at 97 to 99 days of age. Poorly differentiated astrocytomas and astrocytomas of mixed morphology were common among rats inoculated as neonates. Solitary, pilocytic astrocytomas were the most common tumors among rats inoculated as adults.

Age Factors↗

PubMed1976

The fine structure of intracranial neoplasms induced by the inoculation of avian sarcoma virus in neonatal and adult rats.

Groups of F-344 rats were inoculated with the Bratislava-77 strain of avian sarcoma virus (B-77 ASV) within 24 hours of birth, at 9 days of age, or between 97 and 119 days of age. Intracranial tumors developed in each age group. Multiple tumors with mixed histologic patterns developed in rats inoculated at 1 or 9 days of age. Solitary tumors with a uniform histologic pattern developed in rats inoculated as adults. On the basis of light and electron microscopic study, the majority of tumors in each age group were classified as astrocytomas and divided into either poorly differentiated, gemistocytic, pilocytic, or polymorphic varieties. The polymorphic astrocytomas were most common among neonatally inoculated rats, while the pilocytic astrocytomas were most common among rats inoculated as adults. Ultrastructural characteristics of astrocytes, including gap junctions and 7- to 9-nm filaments, were present in the majority of tumors in each age groups. Astrocytomas induced in adult rats were remarkable for the presence of extensive basement membrane alone the astrocytic cell surfaces. Intracytoplasmic virus-like particles (R particles) were common in the tumor cells. These virus-like particles are morphologically distinct from C-type B-77 ASV, and no morphologic evidence of C-type virus replication was observed in any of the tumors.

Animals↗

PubMed1975

The induction of intractranial neoplasms by the inoculation of avian sarcoma virus in perinatal and adult rats.

The induction of intracranial neoplasms following the intracerebral inoculation of avian sarcoma virus (ASV) in neonatal mammals is well established. The present study demonstrates the susceptibility of adult rats and compares the incidence and morphology of tumors induced by a uniform inoculum of the Bratislava-77 strain of ASV in adult, neonatal, and fetal Fischer 344 rats. Post-inoculation mortality varied significantly between groups inoculated at 1, 10 and 100 days and was most precipitous in perinatally inoculated rats. Percentage of tumor induction declined from 100% among rats inoculated at 1 day of age to 50% among rats inoculated at 100 days of age. The mean number of tumors/animal was inversely proportional to the logarithm of the age at inoculation. A large majority of tumors in each group were glial; the remainder were mesenchymal and mixed glial and mesenchymal. Neuroglial tumors included: mixed gliomas with oligodendroglial and astrocytic elements; and gemistocytic, pilocytic, fibrillary, anaplastic and protoplasmic astrocytomas. Tumors induced in perinates were more heterogeneous in histological pattern while tumors induced in perinates were more heterogeneous in histological pattern while tumors induced in older animals tended to be purely astrocytic and of uniform cell type. Mesenchymal tumors occurred primarily in the meninges and were common among animals inoculated perinatally but were rare among animals inoculated as adults. No neuronal tumors were encountered even among rats inoculated as early as 16 days of gestation.

Age Factors↗