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Biomedical subjects

A Koestner

Publications and source records attributed to A Koestner.

At least 55 records · Page 3Linked to original sources
PubMed1982

Immunoperoxidase labeling of canine distemper virus replication cycle in Vero cells.

An indirect immunocytochemical labeling technique, using horseradish peroxidase-conjugated antibody was used to detect the intracellular and surface membrane localization of canine distemper virus (R252-CDV) antigens during productive virus replication in infected Vero cells. Specific labeling of intracellular viral antigens was restricted to rough nucleocapsid aggregates. Surface membrane labeling correlated directly with the appearances both of virus-specific membrane spikes and buds and of mature virions. Syncytial cell formation was associated with labeled cytoplasmic nucleocapsid, but there was no evidence of productive CDV formation on surface membranes. The immunoperoxidase technique provided precise ultrastructural antigenic localization with concomitant preservation of excellent ultrastructural detail within single virus-infected cells during CDV replication cycle in vitro.

Animals↗
PubMed1982

Reduction of ethylnitrosourea-induced neoplastic proliferation in rat trigeminal nerves by nerve growth factor.

Ethylnitrosourea administered to pregnant rats on the 21st day of gestation at a dose of 50 mg/kg resulted in early neoplastic proliferation or neurinomas of trigeminal nerves in 90% of the offspring at 90 days of age. Treatment with nerve growth factor either postnatally following ethylnitrosourea administration or transplacentally prior to ethylnitrosourea treatment appeared to result in a reduction of neurinomas at 90 days of age.

Age Factors↗
PubMed1981

Effect of nerve growth factor producing cells on anaplastic glioma and pheochromocytoma clones: involvement of other factors.

When the NGF-secreting C-6 rat glioma cells were intracerebrally injected with F98 rat anaplastic glioma cells into rats syngeneic for the F98 cells, an increased mean survival time was observed for rats developing tumors compared with those injected with only anaplastic glioma cells. Thirty percent of the rats injected with both cell types showed no signs of tumor at 90 days. Pretreatment of the anaplastic glioma cells with conditioned medium of C-6 cells did not duplicate these results unless the C-6 cells were pretreated with 17 beta-estradiol, which appears to induce secretion of an adhesion factor as well as NGF. These rats survived even longer and 33% were free of tumors at 90 days. Histological examination of tumors of the nonsurviving rats revealed that they were basically well differentiated with only small anaplastic areas remaining. Both NGF and conditioned medium from C-6 and another NGF-secreting line, S-180 mouse sarcoma, induce process formation in F98 cells and in PC12 pheochromocytoma cells, but the processes that appear following NGF exposure are morphologically different from those induced by conditioned medium. Conditioned -medium-treated cells also have a flatter appearance. In F98 cells, NGF takes longer to induce processes than does conditioned medium. The NGF-induced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PCuced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PCuced effects observed in both cells are neutralized by anti-NGF IgG, but those induced by conditioned media are not. Nerve growth factor (NGF) induced increased adhesiveness in F98 rat anaplastic glioma and PC12 rat pheochromocytoma cells. Conditioned media are not. Nerve growth factor induced increased adhesive-and PC12 cells. Anti-NGF IgG did not influence this effect on F98 cells and only partially neutralized the effect on PC12 cells, indicating that other factors may be operative in this system. Conditioned medium collected from C-6 cells pretreated with 17 beta-estradiol induced the highest degree of adhesiveness observed in both F98 and PC12 cells, and this action was unaffected by anti-NGF IgG in either case. Conditioned media from other cell lines, a variety of selected proteins, and dBcAMP did not induce increased adhesiveness. The factor responsible for this effect is nondialyzable, heat-sensitive, and ammonium-sulfate-precipitable, and its secretion appears to be stimulated by 17 beta-estradiol.

Animals↗
PubMed1981

Shared antigenic determinants between brain and thymus-derived lymphocytes in dogs.

Canine anti-canine myelin, canine distemper convalescent, and control sera were tested for the presence of antilymphocyte antibodies in a complement-dependent microcytotoxicity assay. Sera were cytotoxic for CT 45-S cells, a canine origin thymic lymphoma, canine thymocytes, and phytomitogen-transformed canine peripheral blood lymphocytes. The cytotoxic effect was removed by absorption with canine white matter but not by absorption with galactocerebroside. The data suggests that the specificity of antimyelin and antilymphocyte antibodies is directed toward a common antigen (canine Thy-1). It is likely that, in canine distemper, these antibodies are produced following the lymphotropic phase of viral infection. The possibility that similar autoimmune phenomena observed in multiple sclerosis patients occur via an unrecognized infectious event in lymphoid tissues is raised.

Animals↗
PubMed1981

Interrelationships between cellular proliferation, DNA alkylation and age as determinants of ethylnitrosourea-induced neoplasia.

Thirty-day-old Sprague--Dawley rats were used to study the persistence of DNA lesions (e.g., O6-alkylguanine) induced by various doses of ethylnitrosourea (ENU). Cellular proliferation was measured as an increment of DNA content per organ at 7 days post-treatment. We observed that the persistence of O6-EtGua was not affected by the various dose levels. Comparing the 3 organs, the persistence of O6-EtGua ranked in the order of brain greater than kidney greater than liver, while the percent increase in DNA content was measured as liver greater than kidney greater than brain. When the target specificity of ENU carcinogenesis in 30-day-old rats was compared to that following transplacental exposure in terms of its relationship to the persistence of DNA lesions and the rate of target cellular proliferation, it permitted the conclusion that induction of neoplasia in target cells is not only determined by persistent DNA lesions but also by the rate of proliferation of target cells at the time of exposure.

Age Factors↗
PubMed1981

In vitro identification and characterization of a virus isolated from a dog with neurological dysfunction.

A virus, 78-238, isolated from the cerebrospinal fluid of a dog with neurological dysfunction, was characterized as a paramyxovirus. This conclusion was supported by viral cytopathic effects and morphological appearance of virions and nucleocapsids in infected cells. Nucleocapsids were found in the cytoplasm of all infected cells and in the nuclei of 0.001% of these cells. Growth curves revealed that a high percentage (>/=76%) of infectious progeny virus was cell released. Persistent infection of Vero cells with 78-238 showed a consistently high percentage of fluorescence-positive cells and a low proportion of hemadsorption-positive cells. Serological studies indicate that the virus was closely related to Simian virus 5 and reference canine parainfluenza virus.

Animals↗
PubMed1981

Canine distemper virus-associated cardiac necrosis in the dog.

An age-related canine distemper virus-associated cardiomyopathy characterized by multifocal myocardial degeneration necrosis and mineralization with minimal inflammatory cell response was found in gnotobiotic Beagle pups. Of the 30 dogs infected experimentally at 5 to 7 days of age with virulent R252 strain of canine distemper virus, 11 had gross or microscopic cardiac involvement as early as 16 days post-infection. The 25 dogs similarly infected at 10 to 21 days of age, the uninfected age-matched controls, and pups infected at 5 to 7 days of age with avirulent R252 canine distemper virus had no cardiac lesions. Although the lesions are attributed to a direct viral effect, they occur against a background of other canine distemper virus-related changes including immunosuppression, anemia and encephalomyelitis. All these factors may have a modifying role in the development of this age dependent susceptibility to virus-associated myocardial necrosis.

Animals↗
PubMed1980

In vivo demyelination by antimyelin antibodies.

Central nervous system (CNS) myelin-specific antiserum was capable of initiating primary demyelination within 24 h following injection into the dorsal column of guinea pig spinal cord. Control serum injected in the same manner did not produce demyelination. The demyelinating lesions occurred as focal linear plaques of completely denuded intact axons surrounded by partially demyelinated and myelinated normal axons. Antiserum-mediated demyelination was followed by mononuclear cell infiltration 7-10 days later. Ultrastructural examination revealed vesiculation of myelin followed by cleavage of myelin lamellae at the intraperiod line. Remyelination began between 7 and 10 days following injection and correlated well with clinical evidence of recovery. The results of this study point to the importance of circulating antimyelin antibodies in the pathogenesis of demyelinating encephalitis. The model represents an in vivo approach to the study of the pathogenesis of immune-mediated myelinolysis in demyelinating disorders like multiple sclerosis (MS), subacute sclerosing panencephalitis (SSPE), and canine distemper encephalitis (CDE).

Animals↗
PubMed1980

Characterization of cell cycle and biological parameters of transplantable glioma cell lines and clones.

Aberrant biological characteristics of established cell lines and clones, derived from nitrosourea-induced gliomas in CDF rats were compared with normal rat glial cells. Despite their tumorigenicity and unrestrained proliferation due to inherent cytogenetic anomalies, these neoplastic cells retained certain normal glial attributes to a variable degree. Differentiated glioma cells resembled normal glial cells to a greater extent than they resembled anaplastic glioma cells. They were also less malignant upon implantation. Cell cycle analyses revealed that considerable variations not only for the G1 phase but also for the S period were demonstrated among different tumor cell types. Shortening of the G1 phase may dictate a shorter generation time (shorter doubling time) since a larger potential proliferative pool may overcome the effect of a prolonged generation period may constitute a faster proliferation rate. Although the cell generation period of neoplastic cells is not necessarily shorter than that of normal glial cells, the lower proportion of nonproliferative cells results in a much faster growth rate when compared wo non-neoplastic glial cells in culture.

Animals↗
PubMed1980

Persistent in vitro interaction of virulent and attenuated canine distemper virus with bovine cells.

Bovine macrophage and non-macrophage cultures were infected with either virulent or attenuated canine distemper virus (CDV). Macrophages were resistant to virulent CDV; however, they supported growth of the attenuated virus. Non-macrophage cultures supported growth of both virus variants in a persistent, non-lytic manner. Major differences between these two systems of in vitro viral persistence were seen in the host cell spectrum of progeny virus and the outcome of cocultivation experiments with Vero cells. Results obtained indicate that in vivo virulence of CDV is not linked to maturation in a macrophage, but rather, propagation in a given cell culture system results in selective growth of virulent or attenuated viral mutants. It is further concluded that in vivo virulence and in vitro growth potential of CDV are disparate properties of the virion.

Animals↗
PubMed1980

The effect of nerve growth factor on undifferentiated glioma cells.

Nerve growth factor (NGF) treatment of rats bearing implanted cells of an anaplastic glioma clone (F-98) led to a decreased tumor growth rate and increased survival time. Similar, but less pronounced, effects were observed if the cells were pretreated with NGF for 24 h before implantation. NGF also reduced the in vitro growth rate of F-98 and contributed to cellular maturation. Several well differentiated cell lines and clones were not visibly affected by NGF using the above parameters. We concluded that NGF has little or no effect on differentiated glioma cells, but significantly affects undifferentiated glioma cells by retarding their growth and inducing maturation.

Animals↗
PubMed1980

Retention of promutagenic O6-ethylguanine in the DNA of various rat tissues following transplacental inoculation with ethylnitrosourea.

Pregnant Fischer rats at their 20th day of gestation were inoculated intravenously with [14C]ENU (75 mg/kg). The O6-ethylguanine content of liver, kidney, and brain DNA from both fetuses (offspring) and adults were quantitatively determined 3 h and 7 days after carcinogen treatment. Removal of O6-ethylguanine from the DNA of brain (target) was much slower than from liver (non-target) and kidney (low-target). Retention of O6-ethylguanine was found to be relatively similar in adult and fetal brains, although 100% of the offspring transplacentally exposed to 75 mg/kg ENU were shown to develop tumors of the nervous system, whereas the inoculated pregnant dams did not.

Alkylation↗
PubMed1980

Virulence of tissue culture-propagated canine distemper virus.

Virulence of canine distemper virus (CDV) adapted to in vitro growth in Vero or bovine cells was determined by inoculation into CDV-susceptible neonatal gnotobiotic dogs. When compared with dogs given virulent R252-CDV, Vero R252-CDV was attenuated at passage level 14. In contrast, dogs inoculated with bovine R252-CDV at the same passage level experienced rapid fatal neurological disease. Virulence was not linked to ability to infect or replicate in canine pulmonary macrophage cultures. Retention of virulence by bovine R252-CDV is unique and worthy of further study.

Animals↗
PubMed1980

Morphologic and morphometric analyses of butyrate-induced alterations of rat glioma cells in vitro.

The effect of butyrate on cellular morphologic features and morphometric parameters was examined in vitro with clonal glioma cells of the inbred CD Fischer rat. Untreated cells were multipolar with a high nuclear:cytoplasmic ratio, contained few attenuated rough endoplasmic reticular (RER) and cytoskeletal components in the cytoplasm, and were devoid of junctional complexes. Following exposure to butyrate, the glioma cells appeared epithelioid, and each was characterized by a polygonal cell body with a substantially reduced nuclear:cytoplasmic ratio. In contrast to the coarsely clumped nuclear chromatin of untreated glioma cells, the nuclei of the butyrate-exposed cells consisted of finely dispersed chromatin. The cytoplasm of treated cells contained numerous distended RER packed with proteinaceous material and had an elaborate cyto-skeletal network. Butyrate also induced the development of junctional devices between apposed surface membranes of adjacent cells. The acquisition of these phenotypic traits more characteristic of normal glial cells makes butyrate a potent, naturally occurring reverse transformation agent.

Animals↗