Browsing by Author "Barnafi, Esteban"

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    Active acetylcholine receptors prevent the atrophy of skeletal muscles and favor reinnervation
    (2020) Cisterna, Bruno A.; Vargas, Anibal A.; Puebla, Carlos; Fernandez, Paola; Escamilla, Rosalba; Lagos, Carlos F.; Matus, Maria F.; Vilos, Cristian; Cea, Luis A.; Barnafi, Esteban; Gaete, Hugo; Escobar, Daniel F.; Cardozo, Christopher P.; Saez, Juan C.
    Denervation of skeletal muscles induces severe muscle atrophy, which is preceded by cellular alterations such as increased plasma membrane permeability, reduced resting membrane potential and accelerated protein catabolism. The factors that induce these changes remain unknown. Conversely, functional recovery following denervation depends on successful reinnervation. Here, we show that activation of nicotinic acetylcholine receptors (nAChRs) by quantal release of acetylcholine (ACh) from motoneurons is sufficient to prevent changes induced by denervation. Using in vitro assays, ACh and non-hydrolysable ACh analogs repressed the expression of connexin43 and connexin45 hemichannels, which promote muscle atrophy. In co-culture studies, connexin43/45 hemichannel knockout or knockdown increased innervation of muscle fibers by dorsal root ganglion neurons. Our results show that ACh released by motoneurons exerts a hitherto unknown function independent of myofiber contraction. nAChRs and connexin hemichannels are potential molecular targets for therapeutic intervention in a variety of pathological conditions with reduced synaptic neuromuscular transmission.
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    Differential Methylation of CYP11B1 in Girls with High DHEAS Levels and Correlation with 11-Oxyandrogen Levels: A Pilot Study
    (S. Karger AG, 2024) Rodríguez, Fernando; Ponce, Diana; Miranda Marín, José Patricio; Santos Martín, José Luis; Cutler Jr., Gordon B.; Pereira, Ana; Barnafi, Esteban; Iniguez, Germán; Mericq, Verónica
    Introduction: Premature adrenarche in girls is defined biochemically by an increase in adrenal androgen (DHEAS) levels above the age-specific reference range before age 8 years. Recently, increased levels of 11-oxyandrogens have also been reported in girls with premature adrenarche. Epigenetic modifications, specifically CpG methylation, may affect gene expression and/or activity of steroidogenic enzymes during developmental changes in adrenal androgen secretion. Objective: The aim of the study was to determine whether circulating 11-oxyandrogen levels in post-menarcheal girls are associated with the methylation status of genes involved in 11- oxyandrogen steroidogenesis. Methods: Ninety-seven healthy girls followed since the age of 3 years were classified, according to DHEAS serum concentration at age 6.7 years, as normal DHEAS (<42 μg/dL [75th percentile for population]) or high DHEAS (≥42 μg/dL). At Tanner stage 2, themethylation status of CpG sites located in CYP11B1 and HSD11B2 genes was analyzed in genomic DNA from peripheral blood leukocytes by the melting curve analysis methylation assay. Eleven-oxyandrogen concentrations were assessed at 4 years post menarche. Results: Significantly lower methylation levels were detected in the CYP11B1 gene in girls with high versus normal serum DHEAS levels, with no differences found in HSD11B2 gene. Additionally, CYP11B1 methylation status correlated inversely with 11β-hydroxy-androstenedione and 11-ketotestosterone levels. Furthermore, CYP11B1 methylation in the full cohort correlated inversely with insulin concentration at Tanner 1 and with body mass index at Tanner stage 1 and 2. Conclusion: This pilot study proposes the hypothesis that a lowermethylation of CYP11B1 may be a mechanism contributing to increased concentrations of 11-oxyandrogens in premature adrenarche and its associated metabolic risk.
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    Moderate hypofractionated radiotherapy to the prostate bed with or without pelvic lymph nodes: a prospective trial
    (2024) Canales, Juan P.; Barnafi, Esteban; Salazar, Cristian; Reyes, Paula; Merino, Tomas; Calderon, David; Cortes, Analia
    Background: Hypofractionated radiotherapy in the treatment of prostate cancer has been widely studied. However, in the postoperative setting it has been less explored. The objective of this prospective study is to evaluate the safety and efficacy of hypofractionated radiotherapy in postoperative prostate cancer. Materials and methods: A prospective study was designed to include patients with prostate cancer with an indication of postoperative radiotherapy as adjuvant or salvage. A hypofractionated radiotherapy scheme of 51 Gy in 17 fractions was performed with the possibility of treating the pelvis at a dose of 36 Gy in 12 fractions sequentially. Safety was evaluated based on acute and late toxicity [according to the Radiation Therapy Oncology Group (RTOG) scale and Common Terminology Criteria Adverse Events (CTCAE) v4.03], International Prognostic Scoring System (IPSS) over time, and quality of life. Results: From August 2020 to June 2022, 31 patients completed treatment and were included in this report. 35.5% of patients received elective treatment of the pelvic nodal areas. Most patients reported minimal or low acute toxicity, with an acute gastrointestinal (GI) and genitourinary (GU) grade 3 or greater toxicity of 3.2% and 0%, respectively. The evolution in time of the IPSS remained without significant differences (p = 0.42). With the exception of a significant improvement in the domains of hormonal and sexual symptoms of the Expanded Prostate Cancer Index Composite (EPIC) questionnaire, the rest of the domains [EPIC, European Organization for Research and Treatment of Cancer (EORTC) Core quality of life questionnaire (C-30) and Prostate Cancer module (PR-25)] were maintained without significant differences over time. With a follow-up of 15.4 months, late GI and GU grade 2 toxicity was reported greater than 0% and 9.6%, respectively. Conclusions: Hypofractionated radiotherapy in postoperative prostate cancer appears to be safe with low reports of relevant acute or late toxicity. Further follow-up is required to confirm these results. Trial registration: The protocol was approved by the accredited Medical Ethical Committee of Pontificia Universidad Cat & oacute;lica de Chile. All participants accepted and wrote informed consent.