Biology subjects

Orellana, M.

Publications and source records attributed to Orellana, M..

4 recordsLinked to original sources

bioRxiv2025

Chronic Cervical Midline Contusion in Rats Disrupts Aerobic, Muscular, and Cardiovascular Function

Cardiovascular dysfunction significantly contributes to morbidity and mortality following cervical spinal cord injury (SCI). Unfortunately, only a limited number of preclinical models have been developed for investigating cardiovascular dysfunction following cervical SCI. Furthermore, the broader consequences of cervical SCI on aerobic capacity and muscle endurance during physiological stress testing also remains understudied preclinically. Therefore, in this study we assessed potential deficits across multiple physiological systems in a rat model of cervical SCI using a battery of stress tests. Female Sprague-Dawley rats (n = 20) received either a C8 midline contusion (cSCI) or laminectomy alone as a control (LAM). Exercise stress testing was conducted to evaluate cardiorespiratory fitness and recovery using a metabolic treadmill, or forelimb fitness using the isometric pull task. Orthostatic stress testing and pharmacological stress testing were also performed to more directly challenge the cardiovascular system. Our findings demonstrate a decline in aerobic fitness in cSCI rats, as evidenced by dysregulated excess post-exercise oxygen consumption. cSCI rats also exhibited impaired muscle endurance compared to LAM. During orthostatic stress testing, 70% of cSCI rats experienced an approximately 25 mmHg decrease in systolic blood pressure and 20 mmHg decrease in diastolic blood pressure, in addition to modest but significant decreases in heart rate, myocardial contractility index, stroke volume index, and cardiac output index. During dobutamine infusion, cardiac output index and stroke volume index were significantly reduced following cSCI compared to LAM. Overall, these stress testing results suggest that preclinical cervical SCI in rats can lead to, and therefore model, clinically relevant impairments in cardiopulmonary exercise performance, muscle endurance, and cardiovascular function.

physiology↗

bioRxiv2025

XBP1s as a Therapeutic Target to Preserve Retinal Function During Aging and Neurodegeneration

Loss of physiological complexity, characterized by reduced adaptive multiscale coordination among system components, is increasingly recognized as a hallmark of aging and neurodegenerative disease. The retina, a window into the brain, offers a unique, accessible platform to monitor neurodegenerative disorders such as Alzheimers disease (AD). Here, we investigate the therapeutic potential of the unfolded protein response transcription factor XBP1s in preserving retinal function during aging and AD-related pathology in murine models. Using micro-electroretinography with multielectrode arrays, we recorded retinal responses to chirp and white noise stimuli in four mouse models: wild-type (WT), XBP1s-overexpressing (TgXBP1s), AD model (5xFAD), and their crossbreed (TgXBP1s/5xFAD) at approximately 3 and 7 months of age. We assessed retinal signals through entropy-based complexity measures and wavelet coherence between stimulus and response. While WT and 5xFAD mice exhibited age-related decline in retinal complexity, TgXBP1s and TgXBP1s/5xFAD mice maintained higher complexity levels and increased Wcoh in adulthood, indicating functional preservation. These results demonstrate that sus-tained XBP1s expression protects retinal electrophysiological integrity and highlight the retinas value as a scalable, noninvasive biomarker platform to evaluate therapeutic efficacy targeting neurodegenerative mechanisms.

neuroscience↗

bioRxiv2020

Evolution of the SARS-CoV-2 proteome in three dimensions (3D) during the first six months of the COVID-19 pandemic

Three-dimensional structures of SARS-CoV-2 and other coronaviral proteins archived in the Protein Data Bank were used to analyze viral proteome evolution during the first six months of the COVID-19 pandemic. Analyses of spatial locations, chemical properties, and structural and energetic impacts of the observed amino acid changes in >48,000 viral proteome sequences showed how each one of the 29 viral study proteins have undergone amino acid changes. Structural models computed for every unique sequence variant revealed that most substitutions map to protein surfaces and boundary layers with a minority affecting hydrophobic cores. Conservative changes were observed more frequently in cores versus boundary layers/surfaces. Active sites and protein-protein interfaces showed modest numbers of substitutions. Energetics calculations showed that the impact of substitutions on the thermodynamic stability of the proteome follows a universal bi-Gaussian distribution. Detailed results are presented for six drug discovery targets and four structural proteins comprising the virion, highlighting substitutions with the potential to impact protein structure, enzyme activity, and functional interfaces. Characterizing the evolution of the virus in three dimensions provides testable insights into viral protein function and should aid in structure-based drug discovery efforts as well as the prospective identification of amino acid substitutions with potential for drug resistance.

molecular biology↗

bioRxiv2019

AML ImmunoPET: 64Cu-DOTA-anti-CD33 PET-CT imaging of AML in Xenograft mouse model

PurposeAcute myeloid leukemia (AML) is a highly aggressive form of leukemia that results in poor survival outcomes. Currently, diagnosis and prognosis are based on invasive single-point bone marrow biopsies (iliac crest). There is currently no AML-specific non-invasive imaging method to assess disease in the whole body, including in extramedullary organs, representing an unmet clinical need. About 85-90% of human myeloid leukemia cells express CD33 (an accepted biomarker for AML) cell surface receptors, highlighting CD33 as an ideal candidate for AML immunoPET.\n\nExperimental DesignIn this study, we evaluated if 64Cu-DOTA-anti-CD33 murine monoclonal antibody (mAb) can be used for ImmunoPET-CT imaging of AML in preclinical model. For translational purpose, a humanized anti-CD33 antibody was produced, and after confirming its anti-CD33 PET-CT imaging ability we further explored its therapeutic potential.\n\nResults64Cu-DOTA-anti-CD33 based PET-CT imaging detected CD33+ AML in mice with high sensitivity (95.65%) and specificity (100%). In the entire skeletal system, CD33+ PET activity was significantly high in the bones of AML bearing mice over non-leukemic control mice; femur (p<0.00001), tibia (p=0.0001), humerus (p=0.0014), and lumber spine (p<0.00001). Interestingly, the imaging showed CD33+ PET activity prevelant in epiphysis/diaphysis of the bones, indicating spatial heterogeneity. Anti-CD33 therapy using newly developed humanized anti-CD33 mAb as an ADC (p=0.02) and 225Ac-anti-CD33-RIT (p<0.00001), significantly reduced disease burden over that of respective controls.\n\nConclusionWe have successfully developed a novel anti-CD33 immunoPET-CT based non-invasive imaging tool for diagnosis of AML and its spatial distribution, which indicates a preferential skeletal niche.\n\nTranslational RelevanceAcute myeloid leukemia (AML) exhibits extensive heterogeneity in therapeutic response, even in patients sharing similar characteristics, indicating the inadequacy of currently used biopsy-based prognostic tools. There is a critical need for non-invasive quantitative imaging modality specific to AML, which is able to assess this disease in the whole body, including in extramedullary organs and to longitudinally monitor treatment response. CD33, an accepted AML biomarker is expressed on more than 85-90% of blast cells and Mylotarg (anti-CD33-ADC) is FDA approved immunotherapy for AML. In this preclinical study using anti-human CD33 mAb (64Cu-DOTA-anti-CD33), a CD33 PET-CT imaging modality was developed that detected AML with high sensitivity and specificity. The approach also indicated spatial heterogeneity in leukemic disease, dependent on disease burden, which warrants caution in analyzing results from single point bone marrow biopsies. Therefore, this imaging modality can be used to non-invasively detect AML in humans and also monitor treatment response, an unmet clinical need.

cancer biology↗