ABSTRACT
PURPOSE: Periostin is highly expressed in craniopharyngioma (CP)-associated fibroblasts and has been identified as a marker for non-alcoholic fatty liver disease (NAFLD). Half of CP patients with hypothalamic syndrome develop NAFLD. We hypothesized that periostin concentration is elevated in biological fluids of CP and associated with pathological hepatic parameters, indicating increased risk for NAFLD. METHODS: A cross-sectional study on 35 patients with sellar masses (SMP) recruited in the German Childhood Craniopharyngioma Registry (32 CP, 2 xanthogranuloma, 1 pilocytic astrocytoma), three short-statured patients with isolated growth hormone deficiency, five short-statured patients with normal findings in GH-stimulating tests and decreased insulin-like growth factor (IGF)-1 and seven healthy controls. Periostin was measured by Elisa in serum, urine and saliva. RESULTS: Periostin serum, urine and saliva concentrations in CP were similar to concentrations of the other groups. Hypothalamic involvement/hypothalamic lesions, degree of obesity as well as hepatic enzymes were not associated with elevated periostin concentrations. Due to low patient numbers with pathological hepatic parameters, missing imaging data on the degree of steatosis hepatis and the lack of histological proof of NAFLD, no definitive conclusions can be drawn from measured periostin concentrations in serum. Interestingly, the subgroup of patients with decreased IGF-1 levels showed elevated concentrations of serum periostin when compared with other groups. CONCLUSIONS: In CP, periostin concentrations are not associated with known risk factors for NAFLD such as hepatic and metabolic parameters, obesity and hypothalamic lesions. Accordingly, periostin does not seem to be a suitable marker for NAFLD in CP.
Subject(s)
Biomarkers/metabolism , Cell Adhesion Molecules/metabolism , Craniopharyngioma/pathology , Non-alcoholic Fatty Liver Disease/epidemiology , Pituitary Neoplasms/pathology , Adolescent , Adult , Age of Onset , Case-Control Studies , Child , Child, Preschool , Cohort Studies , Craniopharyngioma/metabolism , Cross-Sectional Studies , Female , Humans , Incidence , Infant , Male , Non-alcoholic Fatty Liver Disease/metabolism , Pituitary Neoplasms/metabolism , Prognosis , Young AdultABSTRACT
Crater lakes provide a natural laboratory to study speciation of cichlid fishes by ecological divergence. Up to now, there has been a dearth of transcriptomic and genomic information that would aid in understanding the molecular basis of the phenotypic differentiation between young species. We used next-generation sequencing (Roche 454 massively parallel pyrosequencing) to characterize the diversity of expressed sequence tags between ecologically divergent, endemic and sympatric species of cichlid fishes from crater lake Apoyo, Nicaragua: benthic Amphilophus astorquii and limnetic Amphilophus zaliosus. We obtained 24 174 A. astorquii and 21 382 A. zaliosus high-quality expressed sequence tag contigs, of which 13 106 pairs are orthologous between species. Based on the ratio of nonsynonymous to synonymous substitutions, we identified six sequences exhibiting signals of strong diversifying selection (K(a)/K(s) > 1). These included genes involved in biosynthesis, metabolic processes and development. This transcriptome sequence variation may be reflective of natural selection acting on the genomes of these young, sympatric sister species. Based on Ks ratios and p-distances between 3'-untranslated regions (UTRs) calibrated to previously published species divergence times, we estimated a neutral transcriptome-wide substitutional mutation rate of approximately 1.25 x 10(-6) per site per year. We conclude that next-generation sequencing technologies allow us to infer natural selection acting to diversify the genomes of young species, such as crater lake cichlids, with much greater scope than previously possible.