Browsing by Author "Hannon, Tamara"

Now showing 1 - 6 of 6
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    Associations between menarche-related genetic variants and pubertal growth in male and female adolescents
    (Elsevier, 2015-01) Tu, Wanzhu; Wagner, Erin K.; Eckert, George J.; Yu, Zhangsheng; Hannon, Tamara; Pratt, J. Howard; He, Chunyan; Department of Epidemiology, School of Public Health
    PURPOSE: Previous studies have identified novel genetic variants associated with age at menarche in females of European descent. The pubertal growth effects of these variants have not been carefully evaluated in non-European descent groups. We aimed to examine the effects of 31 newly identified menarche-related single-nucleotide polymorphisms (SNPs) on growth outcomes in African-American (AA) and European-American (EA) children in a prospective cohort. METHODS: We analyzed longitudinal data collected from 263 AAs and 338 EAs enrolled between ages 5 and 17 years; the subjects were followed semiannually for an average of 6 years. The associations between the SNPs and growth-related outcomes, including weight, height, and body mass index (BMI), were examined using mixed-effect models. RESULTS: Longitudinal analyses revealed that 4 (near or in genes VGLL3, PEX2, CA10, and SKOR2) of the 14 menarche-only-related SNPs were associated with changes in weight and BMI in EA and AA (p ≤ .0032), but none of them was associated with changes in height. Of the eight menarche-timing and BMI-related SNPs, none was associated with changes in height, but three (in or near genes NEGR1, ETV5, and FTO) were associated with more rapid increases in weight and/or BMI in EA (p ≤ .0059). Among the nine menarche-timing and height-related SNPs, four (in or near genes ZBTB38, LOC728666, TBX2, and CABLES) were associated with changes in weight or height in EA and AA (p ≤ .0042). CONCLUSIONS: Genetic variants related to age at menarche were found to be associated with various growth parameters in healthy adolescents. The identified associations were often race and sex specific.
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    Nonketotic hyperglycemic hemichorea-hemiballismus in a pediatric patient: A case report
    (Wiley, 2023-01-19) Saroufim, Rita; Hannon, Tamara; Pediatrics, School of Medicine
    Nonketotic hyperglycemic hemichorea-hemiballismus (NHHH) is an infrequent complication of diabetes mellitus, and rarely occurs in children. We present an adolescent boy with recent diagnosis of type 1 diabetes who presented with hemichorea and brain imaging findings consistent with NHHH. His symptoms resolved with euglycemia and valproic acid after few weeks.
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    Novel roles of sterol regulatory element-binding protein-1 in liver
    (2016-04-26) Jideonwo, Victoria N.; Morral, Núria; Considine, Robert V.; Elmendorf, Jeffrey S.; Hannon, Tamara; Herbert, Brittney-Shea
    Sterol Regulatory Element Binding Protein-1 (SREBP-1) is a conserved transcription factor of the basic helix-loop-helix leucine zipper family (bHLH-Zip) that primarily regulates glycolytic and lipogenic enzymes such as L-pyruvate kinase, acetyl-CoA carboxylase, fatty acid synthase, stearoyl-CoA desaturase 1, and mitochondrial glycerol-3-phosphate acyltransferase 1. SREBP-1c activity is higher in the liver of human obese patients, as well as ob/ob and db/db mouse models of obesity and type 2 diabetes, underscoring the role of this transcription factor as a contributor to hepatic steatosis and insulin resistance. Nonetheless, SREBP-1 deficient ob/ob mice, do not display improved glycemia despite a significant decrease in hepatic lipid accumulation, suggesting that SREBP-1 might play a role at regulating carbohydrate metabolism. By silencing SREBP-1 in the liver of normal and type 2 diabetes db/db mice, we showed that indeed, SREBP-1 is needed for appropriate regulation of glycogen synthesis and gluconeogenesis enzyme gene expression. Depleting SREBP-1 activity more than 90%, resulted in a significant loss of glycogen deposition and increased expression of Pck1 and G6pc. Hence, the benefits of reducing de novo lipogenesis in db/db mice were offset by the negative impact on gluconeogenesis and glycogen synthesis. Some studies had also indicated that SREBP-1 regulates the insulin signaling pathway, through regulation of IRS2 and a subunit of the PI3K complex, p55g. To gain insight on the consequences of silencing SREBP-1 on insulin sensitivity, we analyzed the insulin signaling and mTOR pathways, as both are interconnected through feedback mechanisms. These studies suggest that SREBP-1 regulates S6K1, a downstream effector of mTORC1, and a key molecule to activate the synthesis of protein. Furthermore, these analyses revealed that depletion of SREBP-1 leads to reduced insulin sensitivity. Overall, our data indicates that SREBP-1 regulates pathways important for the fed state, including lipogenesis, glycogen and protein synthesis, while inhibiting gluconeogenesis. Therefore, SREBP-1 coordinates multiple aspects of the anabolic response in response to nutrient abundance. These results are in agreement with emerging studies showing that SREBP-1 regulates a complex network of genes to coordinate metabolic responses needed for cell survival and growth, including fatty acid metabolism; phagocytosis and membrane biosynthesis; insulin signaling; and cell proliferation.
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    The obesity epidemic in children: Latino children are disproportionately affected at younger ages
    (Elsevier, 2015-03) Liu, Gilbert C.; Hannon, Tamara; Qi, Rong; Downs, Stephen M.; Marrero, David G.; Department of Medicine, IU School of Medicine
    Background and objectives National surveillance clearly illustrates that U.S. children are becoming increasingly overweight. However, the timing of the onset of childhood overweight has not been well-described. Patients and methods An accelerated failure time (AFT) model was used to describe the emergence of overweight based on a 12-year collection of height and weight data of over 40,000 children. Race, sex, insurance status and their interactions were specifically examined as predictors of earlier onset of overweight. The outcome of interest was an estimate of the age at which the model predicted that a subgroup would attain a 20% prevalence of overweight. Results The three-way interaction of race, sex, and insurance status was a significant predictor of onset of overweight. The model estimated that the publicly insured Latino male subgroup had the earliest onset of overweight, attaining a prevalence of 20% overweight by 4.3 years of age. The emergence of overweight in Latino subjects was significantly earlier than that for black or white subjects, irrespective of sex or insurance status. Conclusion Regardless of sex or insurance status, overweight emerges at significantly younger ages in Latino children when compared to black and white children. Substantial numbers of Latino male children are predicted to develop overweight at preschool ages. Obesity prevention may need to be directed toward parents or children well before children enter grade-school.
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    Pediatric Type 2 Diabetes Presentation During the COVID-19 Pandemic
    (Sage, 2022-02) Neyman, Anna; Nabhan, Zeina; Woerner, Stephanie; Hannon, Tamara; Medical and Molecular Genetics, School of Medicine
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    Unintended Consequences of COVID-19: Remember General Pediatrics
    (Elsevier, 2020) Cherubini, Valentino; Gohil, Anisha; Addala, Ananta; Zanfardino, Angela; Iafusco, Dario; Hannon, Tamara; Maahs, David M.; Pediatrics, School of Medicine