Browsing by Autor "Arias-Reyes, Christian"

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Clinical exposure thresholds associated with retinopathy of prematurity in preterm infants born at high altitude.
(2026) Guillén, Monica Villa; Copa, Martha Wilma Quispe; García, Dina Villanueva; Arias-Reyes, Christian; Soliz, Jorge
This study characterizes clinical and hematologic risk factors for retinopathy of prematurity (ROP) among preterm infants born at high altitude, where chronic environmental hypoxia represents a relevant physiological stressor but cannot be evaluated as an independent causal determinant. A retrospective cohort study was conducted in a tertiary neonatal intensive care unit located at 2240 m above sea level (Mexico City). Preterm infants with gestational age < 35 weeks and birthweight < 2000 g were included. Exclusion criteria were major congenital anomalies, death prior to ophthalmologic screening, and incomplete clinical data. Associations between clinical variables and ROP were assessed using univariate and multivariate logistic regression. Receiver operating characteristic (ROC) analyses were performed to identify cohort-specific exposure thresholds for respiratory support and transfusion burden. Among 76 infants, 22 (28.9%) developed ROP of any stage. Compared with infants without ROP, affected infants required longer supplemental oxygen therapy (median 42.5 vs. 20.0 days, p = 0.001), prolonged mechanical ventilation (17.0 vs. 5.0 days, p = 0.008), and more blood transfusions (6.0 vs. 2.0, p = 0.007). After reclassification, the incidence of necrotizing enterocolitis did not differ significantly between infants with and without ROP and was therefore retained only as a descriptive variable. Multivariate regression confirmed duration of oxygen exposure and transfusion burden as independent predictors of ROP. ROC analyses identified exposure thresholds associated with increased ROP risk: ≥ 35 days of oxygen therapy, ≥ 12 days of mechanical ventilation, and ≥ 6 transfusions. Preterm infants born and treated at high altitude exhibit clinically relevant associations between ROP and the duration and intensity of respiratory support and transfusion exposure. Although altitude itself cannot be evaluated as an independent risk factor in this single-cohort study, these findings underscore the importance of contextualized interpretation of established ROP risk factors in high-altitude neonatal care settings.
Erythropoietin Produces a Dual Effect on Carotid Body Chemoreception in Male Rats.
(2021) Arias-Reyes, Christian; Laouafa, Sofien; Zubieta-DeUrioste, Natalia; Joseph, Vincent; Bairam, Aida; Schneider Gasser, Edith M; Soliz, Jorge
Erythropoietin (EPO) regulates respiration under conditions of normoxia and hypoxia through interaction with the respiratory centers of the brainstem. Here we investigate the dose-dependent impact of EPO in the CB response to hypoxia and hypercapnia. We show, in isolated "en bloc" carotid body (CB) preparations containing the carotid sinus nerve (CSN) from adult male Sprague Dawley rats, that EPO acts as a stimulator of CSN activity in response to hypoxia at concentrations below 0.5 IU/ml. Under hypercapnic conditions, EPO did not influence the CSN response. EPO concentrations above 0.5 IU/ml decreased the response of the CSN to both hypoxia and hypercapnia, reaching complete inhibition at 2 IU/ml. The inhibitory action of high-dose EPO on the CSN activity might result from an increase in nitric oxide (NO) production. Accordingly, CB preparations were incubated with 2 IU/ml EPO and the unspecific NO synthase inhibitor (L-NAME), or the neuronal-specific NO synthase inhibitor (7NI). Both NO inhibitors fully restored the CSN activity in response to hypoxia and hypercapnia in presence of EPO. Our results show that EPO activates the CB response to hypoxia when its concentration does not exceed the threshold at which NO inhibitors masks EPO's action.
Re: "Mortality Attributed to COVID-19 in High-Altitude Populations" by Woolcott and Bergman.
(2021) Zubieta-Calleja, Gustavo; Merino-Luna, Alfredo; Zubieta-DeUrioste, Natalia; Armijo-Subieta, N Freddy; Soliz, Jorge; Arias-Reyes, Christian; Escalante-Kanashiro, Raffo; Carmona-Suazo, Jose Antonio; López-Bascope, Alberto; Calle-Aracena, Jose Manuel; Epstein, Murray; Maravi, Enrique
The ultrasound-based cardiac output monitoring is a useful tool to define baseline hemodynamic parameters in healthy permanent residents at high altitude: results of a monocentric pilot study.
(2023) Viruez-Soto, Antonio; Molano-Franco, Daniel; Merino-Luna, Alfredo; Bairam, Aida; Aliaga-Raduán, Fernanda; Sanchez, Lida; Arias-Reyes, Christian; Soliz, Jorge
Previous studies on the cardiac data of healthy permanent residents living in high-altitude regions such as Tibet and the Andes have yielded inconsistent findings and significant disparities. These discrepancies can be mainly attributed to the invasive methods conventionally used for parameter evaluation. However, with the introduction of cutting-edge ultrasound technology, there is now an innovative approach to addressing and reconciling these variations. In this pilot study, we employed an ultrasound-based cardiac output monitoring (USCOM) device to evaluate cardiac output and related hemodynamic variables in a group of 20 healthy high-altitude Andean residents (comprising 10 men and 10 women) aged between 26 and 35 years old. The monocentric study was carried out in La Paz, Bolivia, located between at an altitude of 3,600-4,000 m. A total of 60 hemodynamic measurements were evaluated, accounting for three technical replicates per subject. Our results showed strong intrasubject reproducibility and revealed important differences related to both sex and hemodynamic parameters in highlanders compared to individuals residing at sea level. We conclude that USCOM represents a highly reliable technology for performing hemodynamic measurements in high-altitude residents. Our preliminary findings underscore the need for larger studies, encompassing larger sample sizes, specifically tailored to gender considerations, and extendable to broader highland populations. These findings have special significant implications for the management of hemodynamics in intensive care and postoperative settings, warranting further comprehensive research efforts.