UTMB Health SHARED (Univ. of Texas Medical Branch at Galveston)
Not a member yet
12407 research outputs found
Sort by
Novel Biomarkers within Extracellular Vesicles for the Identification of Traumatic Brain Injury
No full textTraumatic brain injury (TBI) is defined by the National Institute of Neurological Disorders and Stroke (NINDS) as “…external physical forces cause damage to the brain, whether from impact, penetrating objects, blast waves or rapid movement of the brain within the skull”. According to the most recent CDC data, there were roughly 214,000 TBI-related hospitalizations and 70,000 TBI-related deaths in 2021. The current diagnosis of TBI includes a neurological exam such as Glasgow Coma Scale (GCS) and imaging tests (CT, MRI). However, these modalities have several limitations, including inter-rater reliability, inconsistencies in diagnosis, and lack of predictive prognosis, all of which highlights the complex pathophysiology of this disease process. Thus, there is an urgent need for identification of novel methods for an early detection and quantitative monitoring of TBI. In this project, we investigated extracellular vesicles (EVs) in blood plasma as a potential source of novel TBI biomarkers. Key characteristics of EVs, including the protection of the packaged cargo that reflects processes occurring in the cell of origin and their ability to cross the blood-brain-barrier (BBB), make them a highly valuable source of biomarkers. We subjected 10–12-week-old C57BL/6J male mice to moderate/severe TBI using the pre-clinical, closed head, weight drop model followed by EVs isolation from blood plasma at multiple time points post injury. We detected time-dependent qualitative and quantitative changes in the biophysical properties of EVs. Furthermore, we discovered TBI induced changes in specific EVs subpopulations of microglia/macrophage CD11b+ and astrocyte ACSA-2+ vesicles post-injury. These temporal dynamics of EVs are also reflected in both mitochondrial DNA content, nuclear DNA content, and brain-derived cellular markers NFL, GFAP, and Iba1. Additionally, we combined a global mass spectrometry proteomics approach with biostatistical analysis and computational Graph Neural Network (GNN)-based modeling to discover a panel of potential novel biomarkers for the detection and severity of TBI. Lastly, we confirmed the dynamic release of mtDNA and its fragments in EVs from neurons using an in-vitro TBI model and EVs derived from glucose oxidase stressed retinal pigment epithelial cells, respectively. Together, our findings indicate that a combination of DNA quantity, SAA, and CFD proteins in EVs may be used as diagnostic tools for the rapid, accurate assessment of TBI detection and its sequelae
Investigation of ARNT isoform-specific regulation of AHR signaling
No full textThe aryl hydrocarbon receptor nuclear translocator (ARNT) is alternatively spliced into two distinct isoforms, isoform 1 and 3. Although ARNT is found to be critical in immunity, xenobiotic, and hypoxic response, ARNT isoform-specific function has yet to be investigated. We previously demonstrated that primary lymphocytes express both of these isoforms, however malignant T cells overexpress ARNT isoform 1 to promote cell viability. In this study, we find that the ARNT isoforms have opposing roles in aryl hydrocarbon receptor (AHR) signaling, as ARNT isoform 1 suppresses AHR activity, whereas ARNT isoform 3 is needed for AHR target-gene transcription. Furthermore, to explore this suppressive role, we investigated a unique modification specific only to ARNT isoform 1 – phosphorylation of serine 77 (S77). We determined that phosphorylation at S77 is initiated following AHR activation and is critical for the augmentation of AHR-target gene transcription. These results further highlight the importance of investigating ARNT isoform-specific function and reveal an essential role of ARNT isoform 1 phosphorylation in AHR signaling. Collectively, these findings increase our understanding of a complex regulatory mechanism by which ARNT regulates AHR signaling, further aiding in the comprehension of their roles in immunity and supporting the potential of targeting ARNT alternative splicing as a means of therapeutic intervention in hematological diseases and malignancies
Investigating the Molecular Mechanism of Ribosome Recycling
No full textIn all living cells, the ribosome translates the genetic information carried by messenger RNAs (mRNAs) into proteins. The process of ribosome recycling, a key step during protein synthesis that ensures ribosomal subunits remain available for new rounds of translation, has been largely overlooked. Despite being essential to the survival of the cell, several mechanistic aspects of ribosome recycling remain unclear. Aminoglycosides are a class of antibiotics that bind to ribosomal RNA and exert pleiotropic effects on ribosome function, including recycling inhibition. Amikacin, the semisynthetic derivative of kanamycin, is commonly used for treating severe infections with multidrug-resistant, aerobic Gram-negative bacteria. Amikacin carries the 4-amino-2-hydroxy butyrate (AHB) moiety at the N1 amino group of the central 2-deoxystreptamine (2-DOS) ring, which may confer amikacin a unique ribosome inhibition profile. During stress conditions such as antibiotic exposure, ribosomes stall on messenger RNAs, leading to inhibition of protein synthesis. To remobilize ribosomes, bacteria use rescue factors such as HflXr, that catalyzes the dissociation of translationally inactive ribosomes into individual subunits. Here we use in vitro fast kinetics combined with X-ray crystallography and cryo-EM to dissect the mechanisms of ribosome inhibition by amikacin and the rescue of stalled ribosome through HflXr-mediated recycling. Amikacin interferes with tRNA translocation, release factor-mediated peptidyl-tRNA hydrolysis, and ribosome recycling, traits attributed to the additional interactions amikacin makes with the decoding center. The binding site in the large ribosomal subunit proximal to the 3’-end of tRNA in the peptidyl (P) site lays the groundwork for rational design of amikacin derivatives with improved antibacterial properties. Using time-resolved cryo-EM, we show that within the 70S ribosome, HflXr displaces helix H69 of the 50S subunit and induces long-range movements of the platform domain of the 30S subunit, disrupting inter-subunit bridges B2b, B2c, B4, B7a, and B7b. Our findings unveil a unique ribosome recycling strategy by HflXr which is distinct from that mediated by RRF and EF-G. The resemblance between HflXr and housekeeping HflX suggests that the alternative ribosome recycling mechanism reported is universal in the prokaryotic kingdom
The Impact of Acculturation on Quality of Life in African American Women Living with A Lung or Colorectal Cancer Diagnosis
No full textThe purpose of the proposed pilot study was to explore potential relationships between acculturation, selected demographic characteristics and perceived quality of life in African American women who have been diagnosed with and received treatment for colorectal or lung cancer. There is limited research examining potential cultural and demographic factors related to the ability to cope and maintain quality of life.
A descriptive, exploratory research design was used for this study and utilized three surveys to gather data including the African American Acculturation Scale-Revised World Health Organization Quality of Life Instrument – BREF, and a Demographic Data Form.
A total of 15 African American women who had been diagnosed with lung or colorectal cancer during the past five years were recruited for this pilot study.
Data were analyzed using descriptive statistics including measures of central tendency, interquartile ranges, variance, and standard deviation as well as tests of differences, Mann Whitney U, and linear regressions. A statistical significance of α < .05 was the standard used for this research.
Results of the research study provided baseline data about the impact of American women with colorectal or lung cancer . Published results will assist in filling the existing gap in research literature
A novel GC-MS/MS assay for the measurement of 2-hg enantiomers and the utility of 2-hg enantiomer levels as a biomarker for IDH mutant gliomas
No full textThe isocitrate dehydrogenase (IDH) gene has recently been identified to be mutated in gliomas, a malignant brain tumor. Mutant IDH (IDHmut) produces the oncometabolite, (R)-2-hydroxyglutarate (R-2-hg), resulting in a significant increase of intracellular concentrations above physiological levels. However, a lack of correlation between circulating 2-hg levels and IDH status has been observed. This is likely due to the lack of discrimination from the enantiomer of R-2-hg and (S)-2-hydroxyglutarate (S-2-hg). S-2-hg is also normally made in the body but can increase to levels comparable to R-2-hg during hypoxic and acidic conditions. Thus, it is important to differentiate between R-2-hg and S-2-hg to determine the utility of R-2-hg as a biomarker. Furthermore, the current mass spectrometry (MS) methods available for the separation and detection are lacking. Current assays use laborious methods that can result in interconversion of enantiomers during sample preparation, and since low-resolution mass spectrometry instruments have been utilized, incorrect characterization of 2-hg MS data has occurred.
A novel chiral gas chromatography-tandem mass spectrometry (GC-MS/MS) assay was developed which improves upon current methods. The assay utilizes a simplified ethyl acetate extraction, separates 2-hg enantiomers using a chiral column which avoids racemization, and quantifies 2-hg enantiomers using stable-isotope dilution MS. Using 2-hg isotopologues, unique EI fragmentation pathways for both 2-hg and the 2-hg lactone have also been described resulting in the ability to simultaneously detect both 2-hg and 2-hg lactone enantiomers.
The assay was then validated and serum 2-hg levels from healthy patients were measured, establishing a new, comprehensive reference range for normal levels of each enantiomer. Differences in basal levels of 2-hg enantiomers were observed between races but not sex. Finally, serum levels of 2hg enantiomers were measured in patients with and without IDHmut gliomas. An increase in R-2hg levels was observed for a number of patients with growing IDHmut gliomas, however, not all patients with IDHmut gliomas had an increase in R-2-hg levels. Increased S-2-hg levels were also observed in patients who received prior chemotherapy/radiotherapy. Further work is needed to fully understand circulating 2-hg enantiomer biology, but the work presented herein takes a significant first step in providing the tools and framework for understanding the clinical utility of R-2-hg as a biomarker for IDHmut gliomas
Managing Chaos by Sacrificing Self: Experiences of ICU Nurse Managers: A Classic Grounded Theory Study
No full textNurse managers in the Intensive Care Unit (ICU) are tasked with balancing the needs of critically ill patients and the nursing staff they serve. Nurse managers must balance the decreased availability of resources against the need to maintain an effective and safe environment for staff and patients. Ensuring an effective environment presents a challenge as ICU nurse managers balance their fiscal responsibilities with their commitment to patients and staff. Scant literature exists that explores the experiences of critical care nurse managers and the challenges that they face (Nasrabadi, et al, 2018). Glaser’s Classical Grounded Theory (CGT) approach was used to fill some of these gaps by exploring the experiences of ICU nurse managers as they navigate the day-to-day operations of managing an Intensive Care Unit that provides care to critically ill patients. Data for the study consisted of demographic data, semi-structured interviews with 11 ICU nurse managers that were conducted over Zoom, and the PI’s memos. The Classic Grounded Theory procedures of constant comparative analysis, coding, theoretical sampling, memoing, and writing up (Glaser, 1978, 1998, 2005, 2011, 2012, 2013, 2014; Glaser & Strauss, 1967) were used to analyze the study data. The theory that emerged from the study provides insight and enhances understanding of the day-to-day lives of ICU nurse managers as they balance the competing demands of their patients, their staff, their own needs, and the demands of the hospital organization. The theory that emerged from the data was Managing Chaos by Sacrificing Self. The participants’ main concern, Managing Chaos, is resolved by Sacrificing Self, a process consisting of three sub-categories: Making it Work, Stuck in the Middle, and Sacrificing Self
Essays on the impact of housing insecurity and other socioeconomic factors on health-related outcomes among Medicare beneficiaries during the Great Recession
No full textWhile previous recessions have informed much of our modern-day fiscal policy, they have informed less of relevant housing or healthcare policies focused on preventing or mitigating the effects of housing insecurity during economic crises. In this dissertation, I drew from nationally representative Health and Retirement Study (HRS) data to evaluate the role of housing insecurity on healthcare and health outcomes among Medicare beneficiaries ages 65+ during the Great Recession (2008-2012). In Paper 1, I assessed associations between housing insecurity and foregone medication due to cost. Findings indicated a greater odds of foregone medication among individuals experiencing onset versus persistent housing insecurity, suggesting that unexpected acute economic shocks leave households with little time to adapt and lead to forced trade-offs in basic needs. Guided by the disparities literature, in Paper 2, I examined racial differences in foregone medication among non-Hispanic White (NHW) and Black (NHB) beneficiaries during the 2008 Recession peak to evaluate the extent to which housing insecurity and predisposing, need-based and enabling factors within Andersen’s healthcare utilization model explained the Black-White racial difference. Findings indicated statistically significant associations between race and foregone medication that were explained with the addition of non-housing wealth. These findings suggest wealth was a stronger driver of racial disparities in foregone medication than housing insecurity during the Recession. Guided by stress-health frameworks, in Paper 3, I examined the association of housing insecurity with depressive symptoms among Medicare beneficiaries during the Recession and further assessed the extent to which Andersen’s factors explained this relationship. Findings indicated that baseline housing insecurity had a positive yet insignificant effect on average depressive symptoms during 2008-2012, however, this relationship became negative and significant with the addition of baseline wealth and tenure status, suggesting the strong confounding effect of these variables on the role of housing insecurity on depression. In summary, the three papers fill important gaps in our understanding of the health effects of the Great Recession, including the extent to which housing insecurity was associated with foregone medication due to cost and depression as well as how patterns in forgone medication differed by race and other socioeconomic characteristics
Ehrlichia chaffeensis mediates Hedgehog and Hippo signaling to activate an anti-apoptotic cellular program
No full textEhrlichia chaffeensis is a gram-negative intracellular bacterium responsible for the emerging zoonotic disease, human monocytic ehrlichiosis (HME). HME is the most prevalent and life-threatening tick-borne disease in the United States. In the past two decades, the incidence of HME has increased 10-fold; however, the number of reported cases is underestimated by 100-fold due to underreporting and underdiagnosis. Ehrlichia chaffeensis hijacks mononuclear phagocytes to escape host defenses through mechanisms executed by tandem repeat protein (TRP) effectors secreted by the type 1 secretion system. In the past decade, tandem repeat protein TRP120 has emerged as a model moonlighting effector. Remarkably, TRP120 has been defined as a nucleomodulin, ligand mimic and ubiquitin ligase.
Molecular mimicry is a survival strategy utilized by an array of pathogens to facilitate host-pathogen interactions and exploit host machinery. Recent publications from our laboratory demonstrate that TRP120 is a ligand mimic that directly interacts with various receptors to reprogram the host cell by activating the Wnt and Notch signaling pathways via a novel tandem repeat short linear motif (SLiM). Interestingly, we demonstrate that TRP120 utilizes a Hedgehog SLiM to activate Hedgehog signaling and the Wnt SLiM to mediate Hippo signaling during infection to prevent intrinsic apoptosis. We demonstrate the activation of Hedgehog and Hippo transcription factor and co-activator Gli-1 and Yap through the interaction of TRP120 with Hedgehog and Hippo receptors during infection. Further, studies demonstrate that E. chaffeensis regulates apoptotic downstream targets of Hedgehog and Hippo signaling, including GLUT-1 BCL-2, BCL-xL and Bax. In summary, we determined that E. chaffeensis TRP120 interacts with Hedgehog and Hippo receptors and modulates Hedgehog and Hippo signaling via tandem repeat SLiMs to maintain an anti-apoptotic profile for ehrlichial survival. This study reports the first example of bacterial mimicry of Hedgehog and Hippo pathway ligands and highlights a pathogenic signaling mechanisms which may be utilized for the development of antimicrobial therapeutics
Mechanisms of Innate Immune Dysfunction During Mycobacterium tuberculosis and HIV Co-infection
No full textMycobacterium tuberculosis (Mtb), the etiologic agent of Tuberculosis (TB), remains a significant public health threat causing over 1.4 million deaths annually. People living with HIV are among the most susceptible to contracting or reactivating Mtb infection due to a deterioration of essential immunity during co-infection. Although cell-mediated and innate immunity are known to contribute, the mechanisms leading to exacerbated pulmonary inflammation and increased pathogenesis are largely unknown. The long-term goal of this study is to characterize innate immune signaling responses of macrophages, which drive excessive inflammation during Mtb and HIV co-infection. We previously identified that synergistic inflammasome activation within macrophages, the cellular host
of both Mtb and HIV, leads to a caspase-1 dependent increase in IL-1β secretion and cell
death in vitro. To target the inflammasome pathway for host-directed therapy, the selective caspase-1 inhibitor, VX-765, was used. VX-765 treatment diminished caspase-1 enzyme activity within human macrophage cell lines in a dose-dependent manner. Although VX-765 was effective in vitro, only mild and non-significant effects on disease progression
during in vivo TB and TB/HIV co-infection models were observed.
Additionally, this work identified a novel role for the CLR Macrophage Galactose-type Lectin-1 (MGL-1) in a mouse model (C57BL/6 and MGL-1-/-) of experimental tuberculosis. Murine macrophages upregulated MGL-1 following in vitro and in vivo
exposure to Mtb, while MGL+ cells accumulated at sites of mycobacteria-driven inflammation in the lung. Pulmonary macrophages from MGL-1-deficient mice infected with Mtb displayed increased pro-inflammatory cytokine levels (IL-1β, IL-6, and IFN-g) associated with significant lipid accumulation. Surprisingly for a CLR, we also observed
MGL-1-dependent anti-mycobacterial activity, evidenced by greater Mtb proliferation in
BMDMs and the lung of MGL-1 deficient mice.
Human CLR expression was further evaluated in a humanized mouse model of Mtb, HIV, and co-infection. Surface expression of MGL was increased following early HIV infection (two weeks) but was later diminished seven weeks post-HIV as disease
progressed. In contrast, other CLRs (DC-SIGN) persisted through the course of HIV and
Mtb infections. Similar to the murine model, Mtb infection in humanized mice resulted in
significant MGL expression on pulmonary macrophages.
These results identify MGL and CLR signaling as a mechanism of innate immune regulation against Mtb which HIV may manipulate in the co-infection environment. Taken together, these studies serve as potential host-directed therapeutic targets to limit excessive inflammation and disease progression during Mtb and HIV co-infection
Elucidating Mechanisms of Immunity to Nipah Virus Infection through Generation of Attenuated Viruses and a Single-Cycle Vectored Vaccine
No full textNipah virus (NiV) is an emerging paramyxovirus that has caused outbreaks with high case-fatality rates in South and Southeast Asia. Mechanisms of NiV virulence are poorly understood, and there is no licensed vaccine nor treatment. Accessory proteins produced from the NiV P gene through co-transcriptional gene editing (V and W) inhibit multiple molecules in the type-I interferon (IFN-I) induction and response pathways to modulate the host innate immune response to NiV infection. Previously, ferrets infected with a recombinant NiV (rNiV) lacking V survived an otherwise lethal NiV challenge via an unknown mechanism. Mutation of the V gene of the related canine distemper virus prevented binding of V protein to melanoma differentiation-associated protein 5 (MDA5) and attenuated virulence in an otherwise lethal ferret model. The NiV V-MDA5 binding site and the effects of blocking this interaction on virulence were previously unknown. The work described here identified amino acid I414 in NiV V as a critical residue for binding to MDA5 through co-immunoprecipitation/western blot and IFN-β dual luciferase reporter assays in a plasmid overexpression system. Subsequently, rNiV lacking the ability to bind to MDA5 and signal transducer and activator of transcription 1 (STAT1) were recovered, characterized in cell culture with and without IFN-I pretreatment, and used in an experimental infection model in ferrets. Interestingly, 25% of ferrets infected with the rNiV lacking V survived challenge with a higher virus dose than in previous studies, while 75% of ferrets infected with a rNiV lacking the ability to bind to MDA5 and STAT1 survived. These experiments identified MDA5 and STAT1 together as important targets for NiV virulence. Additionally, previous NiV vaccine candidates have shown efficacy against NiV challenge in a variety of animal models, but no virus-vectored vaccines have been tested for efficacy shortly prior to challenge, as in an outbreak scenario. Therefore, a vesicular stomatitis virus-vectored NiV vaccine was rescued and tested in African green monkeys. Animals were protected from lethal challenge with NiV when the vaccine was given seven or three days prior. The vaccine is non-replicative and yet works rapidly in a single dose with no adjuvants. Combined, the experiments described here will advance understanding of NiV virulence and development of effective vaccines against this deadly infection