Papers by Thelma Dunnebacke
A Comparison of the Growth Properties of Coxsackie Virus Strains A-9 and A-10 with Poliovirus Strain Mahoney in Cultures of Primary Human Amnion Cells
Journal of Immunology, Jun 1, 1961
Summary Comparable cultures of primary human amnion cells were inoculated with poliovirus strain ... more Summary Comparable cultures of primary human amnion cells were inoculated with poliovirus strain Mahoney, Coxsackie virus strain A-9 and Coxsackie virus strain A-10TC. The intracellular virus reached a maximal titer between 8 to 12 hr after inoculation for each of the three viruses. The release of virus into the medium followed its production in the cell by about 4 hr, but the maximal amount released by 30 hr after infection did not exceed more than one-fifth of the amount produced (cell associated, intracellular). The cytopathic changes in primary human amnion cells which followed inoculation were identical for each of the three viruses. However, the temporal relationships between the production of these viruses and the appearance of cellular changes were markedly different. The early cytopathic changes preceded slightly the appearance of intracellular poliovirus. Only 30% of the cells were in early stages of cellular change when the maximal intracellular titers of Coxsackie virus A-9 were reached. At the time of the maximal production of Coxsackie A-10TC, less than 10% of the cells were damaged, although 90% eventually underwent characteristic cellular alterations and degeneration. The data for the Coxsackie viruses showed that the cellular changes occurred subsequent to virus formation. The amount of virus produced in individual cells of comparable size was similar for poliovirus strain Mahoney and Coxsackie virus A-10TC, while 4 to 7 times that amount was produced after inoculation with Coxsackie virus A-9.
Journal of Invertebrate Pathology, Mar 1, 1974
Naegleria gruberi amoebae, EGs strain, containing viruslike particles (VLP) were grown at tempera... more Naegleria gruberi amoebae, EGs strain, containing viruslike particles (VLP) were grown at temperatures of 21" and 37°C. At 21"C, the amoebae displayed the morphological structures associated with development of the VLP's. At 37"C, however, gross morphological modifications and new structures appeared. When amoebae were at 37°C for less than 12 hr, nuclei were found to have a larger number of VLP's than amoebae at 21°C. Exposure of the amoebae to the higher temperature for 1224 hr resulted in. a scarcity of particles. Large bundles of microtubulelike fibrils were present in the nucleoplasm of amoebae at 37"C, and, in addition, the nuclei showed degenerative modifications. The fibrillar changes were not due to the elevated temperature alone since a substrain of EGs ( = EGB) not infected with VLP's exhibited no nuclear modifications. It is assumed that the elevated temperature acaeleratrd upon the cells. and enhanced a lytic effect of the VLP's
The Journal of protozoology, May 1, 1974
t Thanks are due to Dr. William Balamuth who extended the hospitality of his laboratory to F. L. ... more t Thanks are due to Dr. William Balamuth who extended the hospitality of his laboratory to F. L. Schuster during the summer of 1972 when portions of this work were done, to Dr. R. C. Williams for his helpful advice, and to Miss Toni Klassen for technical assistance. castellanii obtained from R. N. Band, 1971; ( d ) pathogenic Acanthamoeba culbertsoni obtained from R. N. Band, 1971; ( e ) the slime mold Polysphondylium pallidum obtained from R. Berman, 1972, and Didymium nigripes obtained from N.
Infectious Agent from a Free-Living Soil Amoeba, <i>Naegleria gruberi</i>
Science, Oct 29, 1971
A subcellular infectious material has been found in a strain of the amoeba Naegleria gruberi, str... more A subcellular infectious material has been found in a strain of the amoeba Naegleria gruberi, strain EG, which is capable of infecting chick embryo cells and causing them to undergo cytopathic changes with the release of more infectious material. The material is present in two lines of the amoeba which were separated shortly after the isolation of the strain and subsequently maintained in separate laboratories.
Virology, Aug 1, 1958
The determination of the yield of poliovirus from isolated cells of varying sizes showed that the... more The determination of the yield of poliovirus from isolated cells of varying sizes showed that the size of a cell is related to the factors which determine whether or not a cell will release virus and to the factors which determine the amount of virus released per cell. The percentage of cells releasing virus was lower for the small cells than for the large cells, and total yield per cell was less for the small cells than for the large cells.
Virology, Dec 1, 1956
The cellular changes associated with polio virus infections in human amnion cultures differ from ... more The cellular changes associated with polio virus infections in human amnion cultures differ from previously studied cells (HeLa, monkey kidney, and human fetal cells) in that (1) the release of newly formed virus occurs 4-8 hours later, (2) the nucleolus becomes indistinguishable before other gross cellular changes occur, (3) spherical projections, or nodules, appear over the free surface of cells, (4) the time of appearance of such nodular cells is coincidental with the time of virus release, and ( ) occasional cultures of amnion undergo different terminal degenerative changes in which the cells become very highly vacuolated.
Journal of Molecular Biology, Nov 1, 1964
The RNA extracted from reovirus and wound tumor virus by phenol has been visualized in the electr... more The RNA extracted from reovirus and wound tumor virus by phenol has been visualized in the electron microscope. The general appearance and the stiffness of the filaments estimated from length measurements are similar to those of DNA and are consistent with previous observations indicating that the RNA's from both viruses are double-stranded. The lengths of the extracted RNA from both reovirus and wound tumor virus fall far short of the 5 f.L predicted from chemical analysis. The contour lengths of reovirus RNA exhibit a distinct 3-or 4-modal distribution pattern; those of wound tumor virus show a more random pattern.
Virology, Oct 1, 1963
The process of infection of liver cells with lipovirus apparently ends in the production of bodie... more The process of infection of liver cells with lipovirus apparently ends in the production of bodies appearing to be aggregates of hollow spheres. In thin sections these spheres appear like rings of very dense material. Nine days after infection, the nucleoplasm .of cells contained individual rings about 15 rnp in diameter with a 10 mp hole, as well as small clusters of rings. Large aggregates up to 100 mp in diameter, were found in the cytoplasm and just outside the cell membrane. The location of the rings and of their aggregates of various sizes suggests that the elements arise in the nucleoplasm, form into clusters, and move through the cytoplasm to the exterior of the cell. Pellets of cell-free material, known to be infective, were found to contain aggregates of ring elements similar in appearance to those found in the whole cells.
The Nature of a Cytopathogenic Material Present in Amebae of the genus Naegleria *
American Journal of Tropical Medicine and Hygiene, May 1, 1977
The Naegleria ameba cytopathogenic material (NACM) obtained from free-living and/or pathogenic am... more The Naegleria ameba cytopathogenic material (NACM) obtained from free-living and/or pathogenic amebae has been partially isolated and characterized. The evidence indicates that the material is a protein or has a protein component, and is in the estimated molecular weight range of 50,000 daltons. The partially isolated NACM, like its counterpart in the amebic lysates, is capable of sustaining itself in tissue cultures at a temperature which otherwise would inactivate it, and in serial passages through multiple dilutions. No distinctions between the NACMs from amebae of different Naegleria species or strains have been found in the biological response to the various treatments studied.
The maturation and release of infectious polio and Coxsackie viruses in individual tissue cultured cells
Archives of Virology, Aug 1, 1962
Summary Examination of the intracellular and extracellular virus yields from individual FL and pr... more Summary Examination of the intracellular and extracellular virus yields from individual FL and primary human amnion cells of uniform size, infected at a high multiplicity and incubated for specified time intervals, showed that the time of the onset of the appearance of mature infectious virus and the amount of accumulated infectious virus were variable from cell to cell. The duration
Virology, Oct 1, 1969
Primary human amnion, human chorion, and human embryonic kidney, continuous lines of human amnion... more Primary human amnion, human chorion, and human embryonic kidney, continuous lines of human amnion, human HEp-2, and HeLa, and continuous line monkey BS-C-1 cells were infected with poliovirus type 1, Brunhilde strain at a multiplicity of 2@-200 PFU/cell. After aldehyde fixation and digitonin permeabilisation, cells were reacted with rabbit antipoliovirus serum followed by ferritin-labeled goat antirabbit globulin. Full and empty particles, ferritin coated by this technique and presumed to represent complete and incomplete progeny virus, were found 3 or more hours after infection: (a) free in the extracellular medium, (b) emerging at the plasma membrane by way of a tubulovacuolar excretory system, (c) free in the cytoplasm near the plasma membrane and among clusters of vesicles, and (d) aligned on fibrils, in the cytoplasm and in cytoplasmic blebs. Fibrils, vesicles, and the smooth endoplasmic reticulum were progressively more heavily coated with ferritin over the 3-6period of poliovirus urotein nroduction. an observation interpreted as demonstrating iocal accumulations*of free viral protein.
Ultrastructural Observations of Experimental Naegleria Meningoencephalitis in Mice: Intranuclear Inclusions in Amebae and Host Cells*
The Journal of protozoology, Nov 1, 1977
Primary amebic meningoencephalitis was experimentallly produced in mice through intranasal instil... more Primary amebic meningoencephalitis was experimentallly produced in mice through intranasal instillation of pathogenic Naegleria fowleri. Experimental animals had a 64% mortality with average time of onset of symtoms of death occurring on the 7-8th day following inoculation. Ultrastructural studies of the olfactory lobes from brains of dead (or sacrificed) animals revealed major concentrations of amebae in the perivascular regions; amebae were also seen to be under attack by host polymorphonuclear leukocytes, and in the lumina of blood vessels. Amebae in brain tissue contained 30 nm intranuclear particles arranged in clusters. In the brains of some mice, dead presumably as a result of amebic meningoencephalitis, particles and crystalloids were observed in the nuclei of degenerating cells of the central nervous system. Some alternatives are examined to explain a possible relationship between ameba intranuclear particles and mouse brain cell intranuclear inclusions.
Experimental Biology and Medicine, Dec 1, 1960
International Journal of Developmental Neuroscience, Mar 12, 2001
Beginning from an undergraduate's perspective and continuing through graduate school, this studen... more Beginning from an undergraduate's perspective and continuing through graduate school, this student's experiences in the Department of Zoology at Washington University in St. Louis, Missouri was a time of many rewarding experiences. Now, on this occasion of his 100th birthday, I wish to express my appreciation to the Chairman, Dr. Viktor Hamburger, for his teachings, his encouragement, and his friendship that has lasted over the past 56 years.
Balamuthia mandrillaris is a protist pathogen that can cause encephalitis with a fatality rate of... more Balamuthia mandrillaris is a protist pathogen that can cause encephalitis with a fatality rate of >95%. This is due to our incomplete understanding of the pathogenesis and pathophysiology of B. mandrillaris encephalitis. B. mandrillaris has two stages in its life cycle, an active trophozoite stage during which it divides mitotically. However, under unfavorable conditions, the trophozoite transforms into a dormant cyst stage. A major concern during the course of therapy is that B. mandrillaris can transform into cysts. Cysts are highly resistant to physical and chemical conditions and present a problem in successful antimicrobial chemotherapy. Several lines of evidence suggest that B. mandrillaris encephalitis develops as a result of hematogenous spread, but it is unclear how circulating amoebae enter the central nervous system and cause inflammation, blood-brain barrier disruption, and neuronal injury. Recent studies have identified several parasite-host determinants for B. mandrillaris translocation of the blood-brain barrier, and host inflammatory markers that may be associated with neuronal injury. These determinants may provide important targets for the prevention and treatment of this devastating infection. Here, we present a brief overview of the current understanding of the morphology, biology, pathogenesis, and pathophysiology of B. mandrillaris encephalitis.
Proceedings of the National Academy of Sciences of the United States of America, May 1, 1967
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Papers by Thelma Dunnebacke