Browsing by Author "Salazar, Cristian"
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- ItemAccuracy Assessment of The Urban Land Surface Temperature Calculation Based on Landsat-8/Oli Data (Case Study: Coyhaique, Chile)(IEEE, 2019) Verichev, Konstantin; Mikhaylyukova, Polina; Salimova, Alisa; Salazar, Cristian; Carpio Martínez, ManuelThe relationship between the values of the surface temperature retrieved from the Landsat-8/OLI satellite data and the values of the atmospheric temperature measured by NETAMO sensors in the urban environment of the Coyhaique city (Oct.2017Sep.2018) was analyzed.Based on the five satellite (one winter, one spring and three summer) images, the coefficient of the linear relationship determination between the two types of temperature was 0.85.
- ItemAssociation between serum sphingolipids and eudaimonic well-being in white US adults(2021) Berkowitz, Loni; Henriquez, Marcela P.; Salazar, Cristian; Rojas, Eric; Echeverria, Guadalupe; Love, Gayle D.; Rigotti, Attilio; Coe, Christopher L.; Ryff, Carol D.Emerging research has linked psychological well-being with many physiological markers as well as morbidity and mortality. In this analysis, the relationship between components of eudaimonic well-being and serum sphingolipids levels was investigated using data from a large national survey of middle-aged American adults (Midlife in the United States). Health behaviors (i.e., diet, exercise, and sleep) were also examined as potential mediators of these relationships. Serum levels of total ceramides-the main molecular class of sphingolipids previously associated with several disease conditions-were inversely linked with environmental mastery. In addition, significant correlations were found between specific ceramide, dihydroceramide, and hexosylceramides species with environmental mastery, purpose in life, and self-acceptance. Using hierarchical regression and mediation analyses, health behaviors appeared to mediate these associations. However, the link between ceramides and environmental mastery was partially independent of health behaviors, suggesting the role of additional mediating factors. These findings point to sphingolipid metabolism as a novel pathway of health benefits associated with psychological well-being. In particular, having a sense of environmental mastery may promote restorative behaviors and benefit health via improved blood sphingolipid profiles.
- ItemDynamics of Built-Up Areas over The Past 30 Years According to Remote Sensing Data in the City of Valdivia, Chile(IEEE, 2018) Verichev, Konstantin; Mikhaylyukova, Polina; Salazar, Cristian; Carpio Martínez, ManuelThe dynamics of built-up areas over the last 30 years in the city of Valdivia was analyzed according to Landsat satellite imagery data. For ETM+/Landsat-7 and OLI/Landsat-8 instrumentation systems, method of automatic satellite image interpretation of build-up areas showed inaccuracy, less than 1%, compared to visual method. For TM/Landsat-5 instrumentation system, method of automatic satellite image interpretation of build-up areas demonstrated unsatisfactory results. Since 1987 and by the year 2017 the city's built-up areas increased by 61% with the population growth of 66% within the same time period.
- ItemLipidomic Signature of Healthy Diet Adherence and Its Association with Cardiometabolic Risk in American Adults(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Berkowitz, Loni; Echeverría, Guadalupe; Salazar, Cristian; Faúndez, Cristian; Coe, Christopher L.; Ryff, Carol; Rigotti, AttilioThe aim of this study was to identify the blood lipidomic profile associated with a healthy eating pattern in a middle-aged US population sample and to determine its relationship with metabolic disorders and cardiovascular risk (CVR). Self-reported information about diet and blood samples were obtained from 2114 adult participants in the Midlife in the United States study (MIDUS). Food intake data were used to design a Healthy Diet Index (MIDUS-HEI) and to evaluate the predictive value by examining its association with health variables. The associated lipid signature (HEI-LS) was constructed using Lasso regression, from lipidomic data (LC/MS). Associations between HEI-LS, cardiometabolic biomarkers, and estimated CVR were assessed using multiple linear regression. MIDUS-HEI score was a robust indicator of dietary quality and inversely associated with body mass index (p < 0.001) and metabolic syndrome (p = 0.012). A lipidomic signature comprising 57 distinct lipid species was highly correlated with the MIDUS-HEI score (r = 0.39, p < 10⁻16). It was characterized by lower levels of saturated fatty acid and adrenic acid (n-6) and higher levels of docosahexaenoic acid (n-3). Healthier HEI-LS scores were strongly associated with better cardiometabolic indicators and lower estimated CVR (OR 0.89 CI 95% 0.87–0.91). The MIDUS-HEI effectively assessed dietary quality, confirming the link between poor diet quality and metabolic disorders in American population. Lipidomic profiling offered an objective assessment of dietary patterns and provided insights into the relationship between diet quality, metabolic responses, and CVR. This approach supports precision nutrition strategies for at-risk populations.
- ItemModerate 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, AnaliaBackground: 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.
- ItemSerum sphingolipid profiling as a novel biomarker for metabolic syndrome characterization(2022) Berkowitz, Loni; Salazar, Cristian; Ryff, Carol D. D.; Coe, Christopher L. L.; Rigotti, AttilioBackgroundSphingolipids are components of cell membrane structure, but also circulate in serum and are essential mediators of many cellular functions. While ceramides have been proposed previously as a useful biomarker for cardiometabolic disease, the involvement of other sphingolipids is still controversial. The aim of this study was to investigate the cross-sectional association between blood sphingolipidomic profiles and metabolic syndrome (MetS) as well as other atherosclerotic risk factors in a large population-based study in the U.S. MethodsClinical data and serum sphingolipidomic profiling from 2,063 subjects who participated in the biomarker project of the Midlife in the United States (MIDUS) study were used. ResultsConsistent with previous reports, we found a positive association between most ceramide levels and obesity, atherogenic dyslipidemia, impaired glucose metabolism, and MetS prevalence. In contrast, most simple beta-glycosphingolipids (i.e., hexosylceramides and lactosylceramides) were inversely associated with dysmetabolic biomarkers. However, this latter sphingolipid class showed a positive link with inflammatory and vascular damage-associated biomarkers in subjects with MetS. Through metabolic network analysis, we found that the relationship between ceramides and simple beta-glycosphingolipids differed significantly not only according to MetS status, but also with respect to the participants' C-reactive protein levels. ConclusionOur findings suggest that a comprehensive sphingolipid profile is more informative about MetS than ceramides alone, and it may reveal new insights into the pathophysiology and further diabetic vs. cardiovascular risk in patients with MetS.