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T T Wheeler

Publications and source records attributed to T T Wheeler.

5 recordsLinked to original sources
PubMed1992

Gene expression during 3T3-L1 adipocyte differentiation. Characterization of initial responses to the inducing agents and changes during commitment to differentiation.

The mouse 3T3-L1 fibroblastic cell line rapidly differentiates to an adipocyte phenotype when post-confluent cells are treated for 48 h in fetal calf serum-containing medium supplemented with 1 microM dexamethasone (D), 0.5 mM methylisobutylxanthine (M) and 10 micrograms/ml insulin (I). D and I act synergistically to commit the cells to differentiate 24-48 h after initiating treatment, and this is blocked by the phorbol ester, 12-O-tetradecanoylphorbol-13-acetate. In order to identify cellular proteins involved in the differentiation process we analyzed differentiating 3T3-L1 cells using two-dimensional electrophoresis on large format gels. We observed changes in over 300 proteins during differentiation (over 100 within 5 h of initiating differentiation) and many of these are also changed at the level of mRNA (by analysis of in vitro translation products). About 75% of the initial changes were maximally induced by treatment with a combination of M and I, while no more than 10 proteins and their corresponding mRNAs were maximally induced by D within 3.5 h. Another 10 proteins were synergistically regulated by the combination of all three agents (DMI) within 3.5 h. Additional species were induced at later times. Five of these were synergistically induced by treatments that lead to differentiation, were first expressed at elevated levels during commitment and remained elevated in fully differentiated adipocytes. One or more of these proteins could well have a functional role in the commitment to and/or expression of the adipocyte differentiation program.

3T3 Cells↗
PubMed1991

Suppression of tumorigenicity of a Wilms' tumor cell line is associated with a decrease in synthesis of two proteins.

Wilms' tumor has been associated with deletions in two loci on chromosome 11, and the introduction of a translocated human chromosome [t(X;11)] into a Wilms' tumor cell line (G401.6TG.6) by microcell hybridization suppresses tumor formation in nude mice. The tumorigenic phenotype is restored in segregants of these microcell hybrids, in which the introduced chromosome is lost. We have used ultrahigh-resolution 'giant' two-dimensional gel electrophoresis of metabolically labeled cellular proteins and in vitro translation products of isolated mRNA to identify changes in cellular gene expression that occur in these cell lines. The changes in gene expression associated with these chromosomal manipulations per se are quite minimal. However, we have identified two proteins (p16 and p28) whose synthesis is consistently decreased in three non-tumorigenic (suppressed) microcell hybrid clones relative to parental and segregant tumorigenic lines. They are also decreased at the level of mRNA in at least two of the non-tumorigenic clones. The decrease of these proteins represents markers of the suppressed phenotype, and their down-regulation may conceivably mediate the suppression of tumorigenicity.

Child, Preschool↗
PubMed1990

The timing of treatment for Class II malocclusions in children: a literature review.

Two basic strategies for the timing of treatment for Class II malocclusions in children are common: (1) correction achieved in two phases, one during pre-adolescence (early treatment) and the other during the teen years; and (2) correction accomplished in one phase of active treatment during the adolescent years. The issues of efficacy and cost(risk)-benefit of these strategies have not been well delineated. Most clinical studies examining these issues have suffered serious methodological deficiencies, such as being retrospective, lacking adequate controls, and evaluating only successfully treated cases. However, despite a lack of objective data, clinicians have shown considerable interest in recent years in two-phase treatment. This paper reviews major issues of two-phase Class II treatment and concludes by delineating several important clinical questions which could be resolved by a carefully controlled prospective study.

Adolescent↗
PubMed1979

Adherence of Actinomyces viscosus T14V and T14AV to hydroxyapatite surfaces in vitro and human teeth in vivo.

Adsorption of Actinomyces viscosus strains T14V and T14AV to hydroxyapatite (HA) surfaces was studied, using an adsorption model based on the Langmuir adsorption isotherm. Data generally followed the adsorption model as judged by high correlation coefficients obtained for both strains to most of the treated surfaces studied. The number of binding sites for strains T14V and T14AV cells to human saliva-treated HA was similar to that for untreated HA. The affinity of strain T14V for saliva-treated HA was tenfold greater than the affinity of strain T14AV for that surface. To approximate the pellicle of the gingival crevice and margin and to determine whether adherence by strain T14V was to specific saliva or serum receptors, experimental pellicles were formed on HA by saliva/serum mixtures. The number of binding sites on the saliva/serum-treated HA remained the same as for the saliva-treated surface. Although the affinity of strain T14V cells for the saliva/serum HA surface remained generally the same as the affinity for the HA treated with saliva alone, the affinity of strain T14AV cells decreased further as the serum content increased. Strain T14V cell numbers adsorbed to serum-treated HA, and albumin-treated HA were less than those adsorbed to saliva-treated HA, indicating that the adherence by strain T14V was to specific saliva receptors. In vivo results from streptomycin-resistant mutants of both strains T14V and T14AV confirmed in vitro results using saliva-serum pellicles. Pretreatment of strain T14V with proteolytic enzymes and heat inhibited adherence to saliva-treated HA, suggesting that the adherence receptor(s) on the cell surface of strain T14V is protein in nature.

Actinomyces↗