Browsing by Author "Iñiguez, Germán"

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    Deficiencia severa de vitamina D en niños de Punta Arenas, Chile : influencia de estado nutricional en la respuesta a suplementación
    (2015) Brinkmann, Karin; Le Roy, Catalina; Iñiguez, Germán; Borzutzky Schachter, Arturo
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    Differential methylation pattern in pubertal girls associated with biochemical premature adrenarche
    (2023) Ponce, Diana; Rodríguez, Fernando; Miranda, José P.; Binder, Alexandra M.; Santos, José L.; Michels, Karin B.; Cutler, Gordon B.; Pereira, Ana; Iñiguez, Germán; Mericq, Verónica
    Biochemical premature adrenarche is defined by elevated serum DHEAS [≥40 μg/dL] before age 8 y in girls. This condition is receiving more attention due to its association with obesity, hyper-insulinemia, dyslipidemia, and polycystic ovary syndrome. Nevertheless, the link between early androgen excess and these risk factors remains unknown. Epigenetic modifications, and specifi-cally DNA methylation, have been associated with the initiation and progression of numerous disorders, including obesity and insulin resistance. The aim of this study was to determine if prepubertal androgen exposure is associated with a different methylation profile in pubertal girls. Eighty-six healthy girls were studied. At age 7 y, anthropometric measurements were begun and DHEAS levels were determined. Girls were classified into Low DHEAS (LD) [<42 μg/dL] and High DHEAS (HD) [≥42 μg/dL] groups. At Tanner stages 2 and 4 a DNA methylation microarray was performed to identify differentially methylated CpG positions (DMPs) between HD and LD groups. We observed a differential methylation pattern between pubertal girls with and without bio-chemical PA. Moreover, a set of DNA methylation markers, selected by the LASSO method, successfully distinguished between HD and LD girls regardless of Tanner stage. Additionally, a subset of these markers were significantly associated with glucose-related measures such as insulin level, HOMA-IR, and glycaemia. This pilot study provides evidence consistent with the hypothesis that high DHEAS concentration, or its hormonally active metabolites, may induce a unique blood methylation signature in pubertal girls, and that this methylation pattern is associated with altered glucose metabolism.
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    Plasma insulin-like growth factor-II (IGF-II) and IGF-II/IGF-I ratio in a chilean case of Doege-Potter Syndrome
    (2023) Tobar Durán, Hugo Eduardo; Ibaceta Gómez, Rodrigo Andrés; Figueroa Toledo, Ana María; Quiñones Tobar, Verónica Pilar; Iñiguez, Germán; Salman, Patricio; Serrano Larrea, Valentina Paz; Salinas Fernández, Lorena Del Pilar; Santos Martin, José Luis
    Doege-Potter syndrome is a rare clinical entity characterized by recurrent hypoglycemic events caused by non-pancreatic tumors secreting an incompletely processed high-molecular-weight form of Insulin-like Growth factor-II (IGF-II). To report IGF-II and IGF-I circulating levels in a Chilean case of Doege-Potter syndrome and control individuals, and to identify the high-molecular-weight form of IGF-II. We measured IGF-II and IGF-I plasma levels using enzyme-linked immunoassays (ELISA) in the patient and ten controls. We identified the high-molecular-weight form of IGF-II performed by Western blot. The plasma concentration of IGF-II in the patient was 868.9 ng/mL, which is only slightly > 80th percentile of controls (681,4 ± 212,8 ng/mL; mean ± standard deviation). In contrast, IGF-I plasma concentration in the patient was 17.6 ng/mL, which is notoriously lower than the corresponding levels in controls (109.1 ± 19.1 ng/mL). The IGF-II/IGF-I ratio in the patient was 49.4 (normal value < 10), which is 7.8 times higher compared to the average ratio of controls (6.3 ± 1.5). The high-molecular form of IGF-II presence in samples was confirmed through Western blot.