Browsing by Author " Caulier-Cisterna, Raul"

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    Interpretable Machine Learning Model for Characterizing Magnetic Susceptibility based Biomarkers in First Episode Psychosis
    (2025) Franco, Pamela ; Montalba Zalaquett, Cristian Andres; Caulier-Cisterna, Raul; Milovic Fabregat, Carlos Andrés; Gonzalez, Alfonso ; Ramirez Mahaluf, Juan Pablo; Undurraga, Juan ; Salas, Rodrigo ; Crossley, Nicolás; Tejos Núñez, Cristián Andrés; Uribe, Sergio
    Altered neurochemicals in deep-brain nuclei, especially dopamine dysfunction, arelinked to psychosis. Quantitative Susceptibility Mapping (QSM) measures brainmagnetic susceptibility changes, including iron concentration, which affects dopaminepathways. This study used machine learning (ML) to analyze MRI data and build aclassifier distinguishing healthy individuals from First-Episode Psychosis (FEP)patients while predicting their response to antipsychotic treatment. A random forestmodel was trained, with the SHAP framework assessing feature importance andinterpretability. Hierarchical clustering identified relationships among features. Themodel achieved performance, with 76.48 ± 10.73% accuracy for classifying FEPpatients (based on R2* values in the nucleus accumbens and amygdala, and QSM inthe thalamus) and 76.43 ± 12.57% accuracy for predicting treatment response (basedon R2* values in the hippocampus, caudate, and putamen, and QSM in the amygdala).MRI-based biomarkers and ML could help tailor personalized treatments for FEPpatients, especially those not responding to standard therapies.
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    Peri-spinal Neurovascular Response Triggered by a Painless Electrical Nerve Stimulation in Patients with Chronic Arterial Hypertension
    (2023) Appelgren, Juan Pablo Gonzalez; Caulier-Cisterna, Raul; Oyarzun, Juan Esteban; Uribe, Sergio; Eblen-Zajjur, Antonio
    PurposeAlterations of the central nervous system are frequent complications in patients with chronic arterial hypertension (AHT). However, functional spinal cord lesions are not often detected in these patients despite diagnostic advances in neuroimaging and electrophysiology. Recently, a new non-invasive functional near infrared spectroscopy (fNIRS) application was developed for assessment of the peri-spinal neurovascular response (NVR) as a functional test of the spinal cord.MethodsThe continuous wave fNIRS technique was applied to detect changes in O(2)Hb concentration during the peri-spinal NVR triggered by non-noxious electrical stimulation of the median nerve at the wrist, and recorded at cervical and thoracic spinal levels using three different stimulation protocols in subjects with AHT treated with losartan (n = 22; 142.14 +/- 133.9 months of disease) and compared to healthy control subjects (n = 37). The body mass index (BMI) and the median nerve conduction velocity (NCV) were also recorded.ResultsThe NVR of patients with AHT showed a significantly lower amplitude (- 70.4%; cervical), longer rise time (+ 22.2%; cervical), and longer duration (+ 28.0%; thoracic) than the control group (p < 0.01). The stimulus intensity-response in the AHT group was - 53.5%, - 55.9%, and - 63% lower in amplitude than the controls (p < 0.05) for the increasing stimulus intensity steps (5; 7.5 and 10 mA, respectively) at the cervical level. Patients with BMI > 30 showed more intense changes. The median NCV was normal for both groups.ConclusionThese data show, for the first time, the difference in peri-spinal NVR between normal subjects and losartan-treated ATH patients, indicating the potential of a non-invasive fNIRS technique to find sensory functional abnormalities of the spinal cord in these patients.
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    Using Near-Infrared Spectroscopy Wearable Devices to Identify Central Versus Peripheral Limitations During Exercise
    (2024) Carreño Román, Matías Ignacio; Ramos López, Daniel Benjamín; Carrillo Rapaport, Benjamín Andrés; Caulier-Cisterna, Raul; Espinosa Ramírez, Maximiliano Andrés; Contreras Briceño, Felipe
    The gold standard to assess the aerobic capacity in physically active subjects and athletes is the maximal oxygen consumption test (VO2-max), which involves analysis of exhaled-gases and cardiorespiratory variables obtained via the breath- by-breath method in an ergospirometer during an incremental exercise. However, this method cannot elucidate metabolic changes at the muscular level. Near-infrared spectroscopy (NIRS) has emerged as a valuable technology to evaluate local oxygen levels (Tissular Saturation Index, TSI) by quantifying the concentrations of oxygenated (O2-Hb) and deoxygenated (H-Hb) hemoglobin in the microvasculature of tissues. NIRS applications extend to respiratory and locomotor muscles, assessing metabolic changes associated with the cost of breathing (COB) and peripheral workload, respectively. Additionally, cerebral regions, such as the prefrontal cortex, have been explored with NIRS technology to assess physiological changes related to cognitive demand associated with planning or ideation of motor tasks linked to sports performance. Thus, by analyzing exercise-induced changes (D) in O2-Hb, H-Hb, and TSI, it is possible to identify central and peripheral exercise limitations, particularly when endurance training is the main component of physical fitness (e.g., running, cycling, triathlon, etc.). Addressing these factors is paramount for coaches and exercise physiologists to optimize athletic performance, incorporating training strategies focused on the primary exercise-limiting factors. This study outlines a protocol for utilizing wearables devices equipped with NIRS technology to analyze exercise changes in TSI, O2-Hb, and H-Hb, alongside cardiorespiratory variables typically registered in athletes during VO 2-max tests. This approach offers a comprehensive method for identifying the primary systems involved in stopping exercise progression and sports performance improvement.
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    Vulnerable newborn types: Analysis of population-based registries for 165 million births in 23 countries, 2000-2021
    (2023) Suarez-Idueta, Lorena; Yargawa, Judith; Blencowe, Hannah; Bradley, Ellen; Okwaraji, Yemisrach B.; Pingray, Veronica; Gibbons, Luz; Gordon, Adrienne; Warrilow, Kara; Paixao, Enny S.; Falcao, Ila Rocha; Lisonkova, Sarka; Wen, Qi; Mardones, Francisco; Caulier-Cisterna, Raul; Velebil, Petr; Jirova, Jitka; Horvath-Puho, Erzsebet; Sorensen, Henrik Toft; Sakkeus, Luule; Abuladze, Lili; Gissler, Mika; Heidarzadeh, Mohammad; Moradi-Lakeh, Maziar; Yunis, Khalid A.; Al Bizri, Ayah; Karalasingam, Shamala D.; Jeganathan, Ravichandran; Barranco, Arturo; Broeders, Lisa; van Dijk, Aimee E.; Huicho, Luis; Quezada-Pinedo, Hugo Guillermo; Cajachagua-Torres, Kim Nail; Alyafei, Fawziya; AlQubaisi, Mai; Cho, Geum Joon; Kim, Ho Yeon; Razaz, Neda; Soederling, Jonas; Smith, Lucy K.; Kurinczuk, Jennifer; Lowry, Estelle; Rowland, Neil; Wood, Rachael; Monteath, Kirsten; Pereyra, Isabel; Pravia, Gabriella; Ohuma, Eric O.; Lawn, Joy E.
    Objective: To examine the prevalence of novel newborn types among 165 million live births in 23 countries from 2000 to 2021.Design: Population-based, multi-country analysis.Setting: National data systems in 23 middle- and high-income countries.Population: Liveborn infants.Methods: Country teams with high-quality data were invited to be part of the Vulnerable Newborn Measurement Collaboration. We classified live births by six newborn types based on gestational age information (preterm <37 weeks versus term >= 37 weeks) and size for gestational age defined as small (SGA, <10th centile), appropriate (10th-90th centiles), or large (LGA, >90th centile) for gestational age, according to INTERGROWTH-21st standards. We considered small newborn types of any combination of preterm or SGA, and term + LGA was considered large. Time trends were analysed using 3-year moving averages for small and large types.Main outcome measures: Prevalence of six newborn types.Results: We analysed 165 017 419 live births and the median prevalence of small types was 11.7% - highest in Malaysia (26%) and Qatar (15.7%). Overall, 18.1% of newborns were large (term + LGA) and was highest in Estonia 28.8% and Denmark 25.9%. Time trends of small and large infants were relatively stable in most countries.Conclusions: The distribution of newborn types varies across the 23 middle- and high-income countries. Small newborn types were highest in west Asian countries and large types were highest in Europe. To better understand the global patterns of these novel newborn types, more information is needed, especially from low- and middle-income countries.