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Lynne L Levitsky

Publications and source records attributed to Lynne L Levitsky.

13 recordsLinked to original sources
PubMed2006

Intermittent growth attenuation: is this a sign of craniopharyngioma?

We present two young children eventually diagnosed with large craniopharyngiomas, who had a normal growth velocity for several years following an initial short period of growth attenuation. These cases suggest the need for a low threshold to undertake hormonal evaluation of patients who present with a past history of growth attenuation.

Age Determination by Skeleton↗
PubMed2005

Differential role of vagus nerve in maintaining diurnal gene expression rhythms in the proximal small intestine.

BACKGROUND: We have documented previously diurnal rhythms in intestinal sugar transporter expression. We set out to identify the role of the vagus nerve in these rhythms. MATERIALS AND METHODS: Sprague-Dawley rats underwent truncal vagotomy (V; n = 9) and were pair-fed with sham-operated (n = 4) and unoperated rats (n = 6). Rats were killed at ZT3 and ZT9 (ZT: Zeitgeber time with ZT0 set at lights-on), the time interval over which sucrase, SGLT1, GLUT2, and GLUT5 expression exhibit significant anticipatory increases. Jejunal RNA expression for the four genes were assessed by Northern blot analysis. SGLT1 and GLUT2 expression was further studied by Western blot analysis and in situ hybridization. RESULTS: Control rats (sham-operated plus unoperated rats) exhibited the expected increase in RNA levels at ZT9 versus ZT3 for SGLT1, GLUT2, GLUT5, and sucrase (P < 0.01 for each). The diurnal rhythm of mRNA levels for GLUT2 and sucrase, but not for SGLT1 or GLUT5, were blunted in V rats. At protein level, SGLT1 was induced 4.3-fold in control rats (P < 0.01) and 3.8-fold in V rats (P < 0.01), whereas GLUT2 was induced 3.3-fold in control rats (P < 0.01) but only 1.4-fold in V rats (N.S.). CONCLUSIONS: Our results indicate that signaling through the vagus nerve is necessary for the anticipatory induction of GLUT2 and sucrase. Persistence of normal rhythms in both SGLT1 and GLUT5 indicates that diurnal induction of these genes is independent of vagal innervation. Entrainment of anticipatory diurnal gene expression in the intestine occurs via two separate pathways that are differentially dependent on vagal input.

Animals↗
PubMed2004

Selective deletion of the Hnf1beta (MODY5) gene in beta-cells leads to altered gene expression and defective insulin release.

Hepatocyte nuclear factor 1alpha (HNF1alpha) and HNF1beta (or vHNF1) are closely related transcription factors expressed in liver, kidney, gut, and pancreatic beta-cells. Many HNF1 target genes are involved in carbohydrate metabolism. Human mutations in HNF1alpha or HNF1beta lead to maturity-onset diabetes of the young (MODY3 and MODY5, respectively), and patients present with impaired glucose-stimulated insulin secretion. The underlying defect in MODY5 is not known. Analysis of HNF1beta deficiency in mice has not been possible because HNF1beta null mice die in utero. To examine the role of HNF1beta in glucose homeostasis, viable mice deleted for HNF1beta selectively in beta-cells (beta/H1beta-KO mice) were generated using a Cre-LoxP strategy. beta/H1beta-KO mice had normal growth, fertility, fed or fasted plasma glucose and insulin levels, pancreatic insulin content, and insulin sensitivity. However, beta/H1beta-KO mice exhibited impaired glucose tolerance with reduced insulin secretion compared with wild-type mice but preserved a normal insulin secretory response to arginine. Moreover, beta/H1beta-KO islets had increased HNF1alpha and Pdx-1, decreased HNF4 mRNA levels, and reduced glucose-stimulated insulin release. These results indicate that HNF1beta is involved in regulating the beta-cell transcription factor network and is necessary for glucose sensing or glycolytic signaling.

Animals↗
PubMed2004

Developmental regulation of galactokinase in suckling mouse liver by the Egr-1 transcription factor.

The numerous changes in metabolic pathways that accompany liver development entail associated changes in gene expression. Egr-1 is a zinc-finger transcription factor that regulates genes involved in cellular growth, differentiation, stress response, and apoptosis in many cell types. Egr-1 is induced in liver regeneration in rodents, but its role in normal hepatocyte function has not been characterized. We examined the developmental expression of Egr-1 in mouse liver and found that its expression increased during the suckling period. In screening the sequences of the genes involved in lactose assimilation, we found that the galactokinase gene Glk contains four potential Egr-1 binding sites in its proximal promoter. A minimal promoter of 155 nucleotides encompassing the four Egr-1 sites exhibited activity in hepatoma cell lines by transient transfection assays. Moreover, co-transfection of an Egr-1 expression plasmid increased promoter activity. Finally, mutations introduced into three of the four Egr-1 binding sites decreased activity, whereas mutation of the remaining site increased promoter activity. These data tie Egr-1 and galactokinase together in a developmentally regulated chain to prepare the neonate for suckling.

Animals↗
PubMed2003

Regional body composition in adolescents with anorexia nervosa and changes with weight recovery.

BACKGROUND: Studies of regional fat distribution in adults with anorexia nervosa (AN) have shown decreased extremity fat at baseline and increased trunk fat with weight recovery, resulting in truncal adiposity. Little is known about fat distribution in adolescents with AN, especially with weight recovery. OBJECTIVE: We sought to determine whether regional fat distribution in adolescents with AN is comparable with that in healthy adolescents and whether weight recovery results in increased trunk fat and truncal adiposity. DESIGN: In 21 adolescent girls with AN and 21 control subjects matched for age and pubertal stage, we measured body-composition variables with dual-energy X-ray absorptiometry at baseline, 6 mo, and 12 mo. Weight recovery was defined as a > or = 10% increase in body mass index. RESULTS: At baseline, the girls with AN had a lower percentage of trunk fat than did the control subjects, whereas the percentage of extremity fat was not significantly different between the groups. Weight recovery in 13 subjects with AN resulted in an increased percentage of trunk fat and an increased ratio of trunk fat to extremity fat; however, this ratio did not exceed that of control subjects. CONCLUSIONS: In adolescents with AN, trunk fat rather than extremity fat is reduced. Weight recovery is associated with increased trunk fat and an increased ratio of trunk fat to extremity fat. In contrast with previous findings in adults, this most likely represents normalization of fat distribution rather than development of truncal adiposity.

Abdomen↗
PubMed2003

Type 2 diabetes: an epidemic disease in childhood.

Type 2 diabetes mellitus in the pediatric population is now a public health problem. It represents 8 to 45% of all diabetes reported among children and adolescents. Concurrently, childhood obesity has become an epidemic in the United States. Epidemiologic risk factors and diagnostic criteria have largely been established: The incidence of type 2 diabetes increases with age and obesity. Children and adolescents diagnosed with type 2 diabetes usually have a first- or second-degree relative with the disorder. Familial clustering and twin studies have suggested a genetic component for type 2 diabetes. However, the molecular mechanisms that promote diabetes in susceptible individuals, the best treatment plans, and methods of prevention of this disorder are not yet established.

Adolescent↗