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in creator/contributor: "Tobey, R."

open access

Cell-cycle-related biosynthesis. [Sarkosyl, neocarzinostatin, adriamycin]

The state of chromatin during the cell cycle was examined using synchronized cultures of CHO hamster cells. Results support Mazia's dynamic chromosome cycle model and indicate that DNA-interactive chemotherapeutic agents elicit different types of kinetic responses in treated cells, suggesting a degree of specificity of interaction between various alkylating and intercalating agents and the genome. Effects of sarkosyl crystals, heparin, and chemotherapeutic agents, neocarzinostatin and adriamyci… more

Date: January 1, 1976

Creator: Tobey, R. A. & Hildebrand, C. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Chromatin Structural Changes Precede Replication in Initiated Replicons During Inhibition of Dna Elongation

Partial inhibition of replicative DNA synthesis by hydroxyurea or other agents produces changes in the composition and structure of bulk chromatin. We have begun to investigate the structural changes in specific regions of the genome using synchronized cells and cloned genomic probes. Current results indicate changes in chromatin structure occur preferentially in initiated replicons and can precede the replication fork during inhibition of DNA elongation. 4 refs., 2 figs.

Date: January 1, 1988

Creator: D'Anna, J. A.; Grady, D. L. & Tobey, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Inducible protective proteins: a potentially novel approach to chemotherapy

A number of toxic chemical and physical agents elicit the induction of a series of protein species, some of which react with the agents and render them non-toxic. A few of the induced species (e.g., metallothionein) are rich in thiol groups which might be expected to react with alkylating agents and render them non-toxic. If a safe means could be found for selectively enhancing the synthesis of alkylating agent-reactive species in normal but not tumor cells, such a procedure would have ramifica… more

Date: January 1, 1982

Creator: Tobey, R. A.; Enger, M. D.; Griffith, J. K. & Hildebrand, C. E.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Biological availability of nickel arsenides: toxic effects of particulate Ni/sub 5/As/sub 2/

Considerations of (1) oil shale retort operating conditions, (2) oil shale elemental composition, (3) nickel and arsenic physico-chemical properties, and (4) oil shale matrix structure lead to the suggestion that nickel arsenides may be formed during the oil shale retorting process. The biological effects of nickel arsenides have not been previously studied. However, similarities between nickel subarsenide and nickel subsulfide and nickel subselenimide, both of which are known potent carcinogen… more

Date: January 1, 1981

Creator: Gurley, L. R.; Tobey, R. A.; Valdez, J. G.; Halleck, M. S. & Barham, S. S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Flow microfluorometric approaches to cell kinetics

We have presented in this report data obtained by FMF analysis of in vivo model tumor systems and the in vitro CHO cell culture system in an effort to demonstrate a few of the biological applications of flow systems, particularly for use in cell kinetics and cell growth studies. Flow systems are no longer viewed as laboratory novelty items or ''electronic gadgets,'' as they were referred to a decade or so ago. Experiments performed in laboratories throughout the world have provided credibility … more

Date: January 1, 1976

Creator: Crissman, H. A.; Kissane, R. J.; Oka, M. S.; Tobey, R. A. & Steinkamp, J. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Method for distinguishing normal and transformed cells using G1 kinase inhibitors

A G{sub 1} phase kinase inhibitor is applied in a low concentration to a population of normal and transformed mammalian cells. The concentration of G{sub 1} phase kinase inhibitor is selected to reversibly arrest normal mammalian cells in the G{sub 1} cell cycle without arresting growth of transformed cells. The transformed cells may then be selectively identified and/or cloned for research or diagnostic purposes. The transformed cells may also be selectively killed by therapeutic agents that d… more

Date: December 31, 1991

Creator: Crissman, H. A.; Gadbois, D. M.; Tobey, R. A. & Bradbury, E. M.

Item Type: Patent

Partner: UNT Libraries Government Documents Department

open access

Phosphorylation of the Butyrate-Enhanced Protein, Histone h1/Sup 0/, in Chinese Hamster Cells. [Effects on h1 Configuration and on h1-Dna Interactions]

Although the model studies focus attention upon the ability of H1 phosphorylation to alter H1-DNA interactions, the molecular effects of H1 phosphorylation in chromatin remain unresolved. Part of the difficulty has been technical. For example, most H1 molecules become dephosphorylated during the isolation of chromatin and chromosomes; therefore, it has not been possible to compare the properties of fully phosphorylated chromatin or chromatin subunits with those of their unphosphorylated counter… more

Date: January 1, 1980

Creator: D'Anna, J. A.; Gurley, L. R.; Becker, R. R.; Barham, S. S.; Walters, R. A. & Tobey, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Histone phosphorylation related to chromatin strucuture. [Studies with cultured mammalian cells]

It has been proposed that the control of DNA activities (such as gene expression, gene replication, and gene segregation) may be mediated by changes in chromatin structure caused by modifications of the chromatin proteins. If this proposal is true, one might expect to find correlations between histone modifications and variations in chromatin structure. Using cultured mammalian cells, we have searched for such correlations and have found that, in general, growth-related histone phosphorylation … more

Date: January 1, 1976

Creator: Gurley, L. R.; Walters, R. A.; Hildebrand, C. E.; Hohmann, P. G.; Barham, S. S.; Deaven, L. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Relationships between histone phosphorylation and cell proliferation

From studies with various Peromyscus cell lines, correlations were made which led to the proposal that H2A phosphorylation is most active in constitutive heterochromatin. Recent studies on the two H2A variants found in these cells have revealed that the high level of H2A phosphorylation associated with heterochromatin is not the result of an increase in H2A phosphorylation rate or an increase in the number of phosphorylation sites, but rather, is due to an increase in the proportion of one of t… more

Date: January 1, 1980

Creator: Gurley, L. R.; D'Anna, J. A.; Halleck, M. S.; Barham, S. S.; Walters, R. A.; Jett, J. H. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Biological effects of negative pions

Most pion radiobiological work in the past was done at low dose rates using biological systems sensitive to small doses. Biological effects at the beam entrance were found to be nearly the same as conventional radiations, although some reports have indicated a higher RBE. LET distribution at the peak of a nearly monoenergetic pion beam is not much different from fast neutrons; therefore, one would expect similar biological responses, and the results are consistent with this hypothesis. The RBE … more

Date: January 1, 1976

Creator: Raju, M. R.; Amols, H. I.; Bain, E.; Carpenter, S. G.; Dicello, J. F.; Frank, J. F. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Time-resolved x-ray absorption spectroscopy of photoinduced insulator-metal transition in a colossal magnetoresistive manganite

We studied the ultrafast insulator-metal transition in a manganite by means of picosecond X-ray absorption at the O K- and Mn L-edges, probing photoinduced changes in O-2p and Mn-3d electronic states near the Fermi level.

Date: August 1, 2008

Creator: Rini, M.; Tobey, R.; Wall, S.; Zhu, Y.; Tomioka, Y.; Tokura, Y. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Time-resolved Studies of Phase Transition Dynamics in Strongly Correlated Manganites

Ultrafast light pulses can be used to control electronic, magnetic and structural phases of complex solids. Here, we investigate the dynamics of insulator-metal phase transitions in colossal magnetoresistive (CMR) manganites by a combination of femtosecond visible-to-midinfrared pump-probe techniques and transport measurements. We show that an insulator-metal transition can be stimulated in CMR manganites by both above bandgap excitation and selective excitation of individual vibrational degree… more

Date: December 5, 2008

Creator: Rini, M.; Tobey, R.; Dean, N.; Wall, S.; Ehrke, H.; Zhu, Y. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Transient electronic structure of the photoinduced phase of Pr0.7Ca0.3MnO3 probed with soft x-ray pulses

We use time-resolved x-ray absorption near-edge structure spectroscopy to investigate the electronic dynamics associated with the photoinduced insulator-to-metal phase transition in the colossal magnetoresistive manganite Pr{sub 0.7}Ca{sub 0.3}MnO{sub 3}. Absorption changes at the O K and Mn L edges directly monitor the evolution of the density of unoccupied states in the transient photoinduced phase. We show that the electronic structure of the photoinduced phase is remarkably similar to that … more

Date: April 1, 2009

Creator: Rini, M.; Zhu, Y.; Wall, S.; Tobey, R. I.; Ehrke, H.; Garl, T. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department