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Biomedical subjects

T T Wheeler

Publications and source records attributed to T T Wheeler.

At least 19 recordsLinked to original sources
PubMed2003

Bovine parotid secretory protein: structure, expression and relatedness to other BPI (bactericidal/permeability-increasing protein)-like proteins.

Members of the family of BPI (bactericidal/permeability-increasing protein)-like proteins are as yet incompletely characterized, particularly in cattle, where full-length sequence information is available for only three of the 13 family members known from other species. Structural bioinformatic analyses incorporating bovine homologues of several members of the BPI-like protein family, including two forms of bovine parotid secretory protein (PSP), showed that this family is also present in cattle. Expression analyses of several members of the BPI-like protein family in cattle, including PSP (Bsp30), von Ebner's minor salivary gland protein (VEMSGP) and lung-specific X protein (LUNX), showed a restricted pattern of expression, consistent with earlier hypotheses that these proteins function in the innate immune response to bacteria. The possible role of bovine PSP in susceptibility to pasture bloat in cattle is discussed.

Animals↗
PubMed2002

STAT5 binding contributes to lactational stimulation of promoter III expressing the bovine acetyl-CoA carboxylase alpha-encoding gene in the mammary gland.

Activity of acetyl-CoA carboxylase (ACC)-alpha is rate limiting for de novo synthesis of fatty acids. The encoding gene is expressed by three different promoters. We characterized promoter III (PIII) from cow, previously only known from sheep. Quantitation of transcripts by RNAse protection assays and real time PCR revealed that PIII is primarily expressed and strongly induced ( approximately 28-fold) in the lactating mammary gland. PIII transcripts are expressed in mammary epithelial cells (MEC) as shown by in situ hybridization. A 2999 bp segment of the PIII promoter conferred prolactin and dexamethasone inducibility to a luciferase reporter gene in stably transfected mouse MEC cells. Lactogenic induction was abolished if a unique signal transducer and activator of transcription (STAT)-binding site at position -797 was inactivated by two point mutations. An oligonucleotide probe harboring this STAT-site specifically bound nuclear proteins from the lactating mammary gland. Binding was abolished by those two point mutations and super-shift analyses showed that STAT5A factors are present in this complex. Hence, prolactin, acting through STAT5, contributes to the activation of ACC expression in the milk producing cells of the lactating mammary gland. We discuss that STAT5 might be important in determining the milk composition by coordinating fatty acid and protein synthesis during lactation.

Acetyl-CoA Carboxylase↗
PubMed2001

Stat5 phosphorylation status and DNA-binding activity in the bovine and murine mammary glands.

The transcription factors Stat5a and Stat5b are mediators of prolactin signalling in mammary epithelial cells, and are thought to play a role in lactogenesis. In cultured cells, activation of Stat5 activity through phosphorylation results in Stat5 binding to the promoters of at least some of the milk protein genes, thereby stimulating their transcription. However, the mammary biology of Stat5 differs between species, and the role of Stat5 in the bovine mammary gland is not fully understood. We have generated an antibody that specifically recognises the phosphorylated forms of Stat5a and Stat5b and used it to compare the levels of phosphorylated Stat5 with Stat5 DNA-binding activity in bovine and murine mammary tissue. Both Stat5 DNA-binding activity and phosphorylation status in the bovine mammary gland were at near-maximal levels at late pregnancy (27-35 days prior to calving), when at least three of the major milk proteins are not highly expressed. In addition, these studies revealed significant animal-to-animal variation in the level of Stat5 activity in both species. The results are consistent with a role in terminal differentiation of mammary epithelial cells. They also suggest that the stimulation of high-level expression of milk protein genes in the bovine mammary gland is not through activation of the prolactin receptor-Jak2-Stat5 pathway.

Animals↗
PubMed2001

Insulin Induction of SOCS-2 and SOCS-3 mRNA expression in C2C12 Skeletal Muscle Cells Is Mediated by Stat5*.

Previously, by a yeast 2-hybrid screen, we identified signal transducer and activator of transcription 5b (Stat5b) as a substrate of the insulin receptor (IR). We demonstrated that refeeding of fasted mice leads to rapid activation of Stat5 proteins in liver, skeletal muscle, and fat, suggesting that Stat5b is a physiological target of insulin. Here, we show that injection of glucose or insulin into fasted mice leads to robust activation of both Stat5a and Stat5b in skeletal muscle. In C2C12 myotubes, we find that insulin stimulates tyrosine phosphorylation of Stat5a and Stat5b by 3-5-fold. This degree of Stat5 activation in vitro is significantly lower than what we observe in vivo and inversely correlates with IRS-1/2 levels. We can recapitulate robust insulin activation of Stat5 in C2C12 cells by stable overexpression of the human IR (hIR). To identify insulin-activated genes that are Stat5 targets, we also overexpressed an IR mutant (LA-hIR) that signals normally for mitogen-activated protein kinase- and phosphatidylinositol 3-kinase-dependent pathways but is deficient in Stat5 signaling in response to insulin. We demonstrate that insulin induces the expression of SOCS-2 mRNA in the wild type hIR but not in the LA-hIR-overexpressing cells. The induction of SOCS-3 by insulin is reduced but not lost in the LA-hIR cells. Therefore, our results suggest that insulin induction of SOCS-2, and in part SOCS-3 mRNA expression, is mediated by Stat5 and can be independent of mitogen-activated protein kinase and phosphatidylinositol 3-kinase-signaling pathways.

Animals↗
PubMed2001

GH regulation of IGF-I and suppressor of cytokine signaling gene expression in C2C12 skeletal muscle cells.

GH is required for normal postnatal growth and metabolism. GH stimulates postnatal growth through induction of IGF-I gene expression. Although the liver is the major site of GH-regulated IGF-I, recent evidence indicates that GH-regulated IGF-I expression in nonhepatic tissues is sufficient for normal postnatal growth. One potentially important nonhepatic site of GH-stimulated IGF-I expression is skeletal muscle, as injection of GH into animals leads to increased IGF-I mRNA in this tissue. Nevertheless, direct effects of GH in skeletal muscle cells in culture have not been reported. We therefore tested the C2C12 myogenic cell line for its response to GH and demonstrate that C2C12 skeletal muscle cells rapidly respond to physiological levels of GH with increased tyrosine phosphorylation of the GH receptor, Janus kinase 2, signal transducer and activator of transcription-5a and -5b, insulin receptor substrate-1, and activation of MAPKs/ERKs and protein kinase B/Akt. In these cells, GH stimulates the expression of IGF-I and two members of the suppressors of cytokine signaling family, cytokine-inducible SH2-containing protein and suppressor of cytokine signaling-2. Treatment of C2C12 myoblasts with either the MAPK kinase inhibitor PD98059 or the PI3K inhibitor wortmannin results in higher levels of GH-induced IGF-I and suppressor of cytokine signaling-2 mRNA expression, suggesting that activation of MAPK and PI3K pathways has an inhibitory role in IGF-I and suppressor of cytokine signaling-2 gene regulation. Therefore, C2C12 cells provide the first in vitro model system to study various aspects of GH action in skeletal muscle.

Animals↗
PubMed2001

The p100 coactivator is present in the nuclei of mammary epithelial cells and its abundance is increased in response to prolactin in culture and in mammary tissue during lactation.

The p100 coactivator, first identified as a coactivator of the Epstein-Barr virus-encoded transcription factor, EBNA-2, in cultured cells, interacts with a number of transcription factors. However, the role of p100 in animals is unclear. We found that the abundance of p100 is closely associated with the lactating state in mammary tissue of mice and cows. Using two antibodies against independent parts of the protein, p100 immunoreactivity was localised to mammary epithelial cells, and was enriched in both nuclei and endoplasmic reticulum/organelle fractions. Stimulation of beta-casein expression in cultured mammary epithelial cells was associated with an increase in abundance of the p100 protein. The relative abundance of p100 mRNA was not altered in mammary tissue throughout the gestation-lactation cycle, indicating that the abundance of p100 is altered by a post-transcriptional mechanism. Further work is required to clarify the function of p100 in mammary epithelial cells.

Animals↗
PubMed2000

Molecular characterization of STAT5A- and STAT5B-encoding genes reveals extended intragenic sequence homogeneity in cattle and mouse and different degrees of divergent evolution of various domains.

The STAT transcription factors form a family of signal transducers and activators of transcription. We sequenced the bovine STAT5B cDNA and both STAT5-encoding genes, STAT5A and STAT5B, representing the first complete description of any STAT5-encoding gene. DNA fiber FISH hybridization revealed that the genes reside only 40 kbp apart on BTA19. Both genes are segmented into 19 exons and all but two of the homologous exons are of equal size. The genes harbor a central block of nearly identical DNA sequence (97.5% sequence identity over 3373 bp), spanning from intron 5 to intron 9. Isolation and sequencing of the homologous segments from mouse revealed the same unusually high degree of intronic sequence conservation in these segments of the murine STAT5-encoding genes. However, the respective sequences are completely divergent between the two species. A comparison of the inter- and intragenic cDNA sequence preservation at nonsynonymous sites reveals that the DNA-binding domain is under the strongest selection pressure for both intergenic and factor-specific intragenic sequence preservation. The so-called "SH3" segment of the linker domain, in contrast, shows species-specific sequence identity in all but one amino acid residues in both factors, in cattle, human, and mouse. This indicates that the same species-specific selection pressure occurs on the linker domain from both factors, STAT5A and STAT5B. Thus, the comparison of evolutionary selection pressures resting on various domains suggests that the DNA-binding domain might contribute to differential DNA binding of STAT5A and STAT5B factors, while both might interact equally well with other cellular factors through a segment of the linker domain.

Amino Acid Sequence↗
PubMed2000

Nuclear localisation of the transcription factor Stat5b is associated with ovine milk protein gene expression during lactation but not during late pregnancy or forced weaning.

Localisation patterns of the transcription factor Stat5b in the udders from pregnant, lactating and involuting ewes were compared with the expression patterns of two major milk protein genes alpha-lactalbumin and alphaS1 casein. Stat5b was detected in the cytoplasm and nuclei of epithelial cells at all stages of mammary gland development. A consistent positive relationship between the nuclear localisation of Stat5b in lactating mammary alveolar epithelial cells, and the presence of milk protein gene mRNA was apparent during lactation and early involution. Conversely, there was little evidence of nuclear localisation of Stat5b in non-lactating mammary alveolar epithelial cells during lactation and early involution. This supports the observation that during lactation, Stat5b may play a role in milk protein gene expression. However, during pregnancy and later involution, while Stat5b was observed to be present in mammary epithelial cell nuclei and cytoplasm, no relationship between this and the presence of milk protein gene mRNA was apparent. This suggests that during late pregnancy and in later involution, Stat5b may be involved in processes other than initiation of milk protein gene transcription.

Animals↗
PubMed1999

Evaluation of orthodontists' perception of treatment need and the peer assessment rating (PAR) index.

This paper examines the relationship between orthodontists' subjective assessment of treatment need and objective measurements obtained during standardized intra- and extraoral examinations. Logistic regression modeling was used to develop predictive models of treatment need. Data were obtained from 1155 eighth-grade students by four orthodontists who used standardized examination forms to assess demographics, trauma, skeletal relationships, morphologic malocclusion traits, and mandibular function. At the conclusion of the examination, the orthodontist rated the subjective treatment need as none, elective, recommended, soon, or immediate. For some analyses, the categories were collapsed to represent no need and need. The peer assessment rating (PAR) index (American validated version) was computed from the clinical exam findings and scoring of dental models; PAR scores were used to document malocclusion severity and treatment difficulty. Spearman rank correlation coefficients quantified the relationship between PAR scores and need categories. Logistic regression analysis modeled treatment need using components of the PAR index as well as other variables. The components of these models, as well as sensitivity and specificity, were compared with malocclusion severity/treatment difficulty scores obtained from malocclusion assessments using the PAR index. The five subjective treatment need categories and the PAR index scores were significantly correlated (rho = 0.62, p<0.001). Significant differences were detected between the need and no need groups for all PAR components (p<0.001). PAR index scores and predicted probabilities from logistic regression models performed equally well for classification purposes (no need, need). The data suggest that the PAR index is highly correlated with orthodontists' subjective assessment of treatment need when that assessment is made in the absence of financial considerations and patient desires.

Adolescent↗
PubMed1999

Identification of differentially expressed genes during a wool follicle growth cycle induced by prolactin.

The wool follicles of New Zealand Wiltshire sheep can be induced to undergo growth cycles by manipulating circulating prolactin levels. Altered patterns of gene expression through this cycle were examined using differential display, and nine sequence tags for differentially expressed genes were isolated. Four of these tags were identified as fragments of known genes, encoding a wool keratin, KRTAP3.2, a desmosome component, desmoglein 1, an epithelial cell marker, stratifin, and a protein kinase, Clk3. All four genes were shown to be downregulated in telogen skin compared with anagen. In situ hybridization showed that all had localization patterns which included cells that are absent in telogen. The stratifin tag was used to clone a cDNA that incorporated a complete open-reading frame for ovine stratifin. Ovine stratifin is similar to the human form, showing only six single residue differences in the predicted amino acid sequence. Stratifin probably acts as a regulator of other proteins involved in trichocyte cell cycling and differentiation. Clk3 is involved in regulating RNA splicing. KRTAP3.2 and Dsg1 both play structural roles in hair follicles. The other five tags, including two representing genes that were upregulated during catagen, could not be identified by homology. Differential display is an effective means of identifying genes involved in follicle function and, potentially, of genes controlling the growth cycle.

14-3-3 Proteins↗
PubMed1999

Orthodontists' perceptions of the impact of phase 1 treatment for Class II malocclusion on phase 2 needs.

The most appropriate timing for the treatment of Class II malocclusions is controversial. Some clinicians advocate starting a first phase in the mixed dentition, followed by a phase 2 in the permanent dentition. Others see no clear advantage to that approach and recommend that the entire treatment be done in the late mixed or early permanent dentition. This study examines how orthodontists, blinded to treatment approach, perceive the impact of phase 1 treatment on phase 2 needs. The sample consisted of 242 Class II subjects, aged 10 to 15, who had completed phase 1 or observation in a randomized clinical trial (RCT). For each subject, video orthodontic records, a questionnaire, a fact sheet, and a cephalometric tracing were sent to five randomly selected reviewing orthodontists blinded to subject group and study purpose. Reviewing orthodontists were asked to assess treatment need, general approach, need for extractions, priority, difficulty, and determinants. Orthodontists agreed highly on treatment need (95%) and moderately on treatment approach (84%) and extraction need (80%). They did not perceive differences in need, approach, or extractions between treated and control groups. Treated subjects were judged as less difficult (p = 0.0001) and to have a lower treatment priority (p = 0.0001) than controls. In ranking problems that affect treatment decisions, the orthodontists ranked dental Class II (p = 0.005) and skeletal relationships (p = 0.004) more highly in control than in treated patients. These data indicate that orthodontists do not perceive phase 1 treatment for Class II as preventing the need for a second phase or as offering any particular advantage with respect to preventing the need for extractions or other skeletal treatments in that second phase. They do view early Class II treatment as an effective means of reducing the difficulty of and priority for phase 2.

Adolescent↗
PubMed1998

Cloning and sequencing of the bovine STAT5A cDNA reveals significant sequence divergence with ovine.

The transcription factors STAT5 mediates prolactin signals in mammary epithelial cells. The cDNA of bovine STAT5A was cloned, sequenced and compared to other species. The encoded protein proves to be > 95% homologous to other mammals. We show that the STAT5A mRNA of the closely related ovine species contains an extended (by 130 nt) 5'-untranslated region, being encoded by an extra-exon, and accounts, possibly, for improved translation efficiency.

Amino Acid Sequence↗
PubMed1998

Anteroposterior skeletal and dental changes after early Class II treatment with bionators and headgear.

In this study we examined anteroposterior cephalometric changes in children enrolled in a randomized controlled trial of early treatment for Class II malocclusion. Children, aged 9.6 +/- 0.8 years at the start of study, were randomly assigned to control (n = 81), bionator (n = 78), and headgear/biteplane (n = 90) treatments. Cephalograms were obtained initially, after Class I molars were obtained or 2 years had elapsed, after an additional 6 months during which treated subjects were randomized to retention or no retention and after a final 6 months without appliances. Calibrated examiners, blinded to group, used Johnston's analysis to measure anteroposterior cephalometric changes. Statistical analysis was used to determine annual skeletal and dental changes during treatment, retention, and follow-up, and overall. Our data reveal that both bionator and head-gear treatments corrected Class II molar relationships, reduced overjets and apical base discrepancies, and caused posterior maxillary tooth movement. The skeletal changes, largely attributable to enhanced mandibular growth in both headgear and bionator subjects, were stable a year after the end of treatment, but dental movements relapsed.

Activator Appliances↗
PubMed1998

Prevalence of orthodontic asymmetries.

Epidemiological studies of the occlusal status of the US population do not include the prevalence of orthodontic asymmetries. To estimate the magnitude of dental and facial asymmetries in adolescents with no history of orthodontic treatment, data were analyzed from two mass orthodontic screenings that had been conducted on public schoolchildren in Florida. An analysis of orthodontic records of patients in treatment at the Virginia Commonwealth University graduate orthodontic clinic provided prevalence data on dental and facial asymmetries in a population of orthodontic patients. In the Florida studies, the two screenings yielded 5,817 untreated children (mean age, 9.3 +/- 0.8 years) and 861 untreated children (mean age, 14.4 +/- 0.5 years). Sagittal molar asymmetry was found in 30% of the children in the first screening and in 23% in the second screening. Additional asymmetry assessments in the second screening showed 12% facial asymmetry and 21% noncoincidence of dental midlines. Among orthodontic patients, the most common asymmetry trait was mandibular midline deviation from the facial midline. This occurred in 62% of patients, followed, in descending order of frequency, by lack of dental midline coincidence (46%), maxillary midline deviation from the facial midline (39%), molar classification asymmetry (22%), maxillary occlusal asymmetry (20%), mandibular occlusal asymmetry (18%), facial asymmetry (6%), chin deviation (4%), and nose deviation (3%).

Adolescent↗
PubMed1998

Occlusal traits and perception of orthodontic need in eighth grade students.

In 1994, 1155 eight-grade students in Alachua County, Fla., were asked about self-perception of and level of concern for their occlusal status. Clinical assessments of orthodontic parameters were also recorded. Twenty-five percent of the students had a history of orthodontic treatment. Of the remaining students who had no history of orthodontic treatment, 74% reported satisfaction with the way their teeth looked, 64% expressed no perceived need for braces, and 57% were judged clinically to have optional or no orthodontic needs. Sex, soft tissue profile, overjet, anterior crowding, and molar classification were significantly associated with the perception of need for braces while race and overbite were not. Clinical judgment of orthodontic need differed significantly among levels of satisfaction with teeth. Eighth graders with no history of orthodontic treatment were generally satisfied with the appearance of their teeth and perceived less need for braces than clinicians.

Adolescent↗