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338 result(s) for "Pham, Jennifer"
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Mitochondria-associated endoplasmic reticulum membranes (MAMs) and their role in glaucomatous retinal ganglion cell degeneration—a mini review
Glaucoma is a leading cause of blindness worldwide, commonly associated with elevated intraocular pressure (IOP), leading to degeneration of the optic nerve and death of retinal ganglion cells, the output neurons in the eye. In recent years, many studies have implicated mitochondrial dysfunction as a crucial player in glaucomatous neurodegeneration. Mitochondrial function has been an increasingly researched topic in glaucoma, given its vital role in bioenergetics and propagation of action potentials. One of the most metabolically active tissues in the body characterized by high oxygen consumption is the retina, particularly the retinal ganglion cells (RGCs). RGCs, which have long axons that extend from the eyes to the brain, rely heavily on the energy generated by oxidative phosphorylation for signal transduction, rendering them more vulnerable to oxidative damage. In various glaucoma models, mitochondrial dysfunction and stress from protein aggregates in the endoplasmic reticulum (ER) have been observed in the RGCs. However, it has been shown that the two organelles are connected through a network called mitochondria-associated ER membranes (MAMs); hence this crosstalk in a pathophysiological condition such as glaucoma should be evaluated. Here, we review the current literature suggestive of mitochondrial and ER stress related to glaucoma, indicating potential cross-signaling and the potential roles of MAMs.
Hybrid molecule SA-10 and its PLGA nanosuspension protect human and rodent retinal ganglion cells against neuronal injury
Background Glaucoma is a leading cause of blindness characterized by retinal ganglion cell (RGC) degeneration. SA-10, a dual-acting compound with ROS scavenging and NO-donating properties, was evaluated to enhance RGC survival and function in models of oxidative stress, ischemia/reperfusion (I/R) injury, and neurotrophic factor (NF) deprivation. Methods SA-10-loaded nanoparticles (SA-10-NP) with a size of 279.6 ± 20.9 nm, polydispersity index of 0.34, and encapsulation efficiency of 80.6% were synthesized and tested for sustained release over 28 days. I/R injury was induced by elevating intraocular pressure to 120 mmHg for 60 min in C57BL/6J mice, followed by SA-10-NP treatment (1% w/v). Retinal ganglion cell function and survival were evaluated using PERG and PVEP. Oxidative stress in primary RGCs and retinal explants was induced using endothelin-3 (ET-3), and the effects of SA-10 (10 µM) on ROS levels were assessed. In ex vivo human retinal explants (HREs), SA-10 treatment effects on oxidative stress markers NRF2 and HMOX1 were analyzed. Results SA-10-NP improved PERG amplitudes (112.96% in females, p  < 0.01) and PVEP amplitudes (67.53% in females, p  < 0.01), preserving RGC density in both central and mid-peripheral regions. Immunohistochemistry showed upregulation of Hmox1 and downregulation of TNF-α in the SA-10-NP-treated group. SA-10 significantly reduced ROS levels in primary RGCs and retinal explants exposed to endothelin-3 (ET-3), decreasing fluorescence intensity by 25.9% ( p  < 0.01) and 14.7% ( p  < 0.0001), respectively. SA-10 upregulated oxidative stress markers (NRF2 and HMOX1) and enhanced RGC survival in NF-deprived HREs. Conclusions SA-10 demonstrated significant ROS reduction and preserved RGC survival and function in both I/R mouse models and HREs, with immunohistochemistry confirming upregulation of Hmox1 and downregulation of TNF-α in the SA-10-NP-treated group. SA-10-NP provided sustained drug delivery and bioavailability, showcasing strong neuroprotective effects and offering a potential therapeutic strategy for glaucomatous optic neuropathy and other neurodegenerative conditions.
Electrical detection of RNA cancer biomarkers at the single-molecule level
Cancer is a significant healthcare issue, and early screening methods based on biomarker analysis in liquid biopsies are promising avenues to reduce mortality rates. Electrical detection of nucleic acids at the single molecule level could enable these applications. We examine the electrical detection of RNA cancer biomarkers (KRAS mutants G12C and G12V) as a single-molecule proof-of-concept electrical biosensor for cancer screening applications. We show that the electrical conductance is highly sensitive to the sequence, allowing discrimination of the mutants from a wild-type KRAS sequence differing in just one base. In addition to this high specificity, our results also show that these biosensors are sensitive down to an individual molecule with a high signal-to-noise ratio. These results pave the way for future miniaturized single-molecule electrical biosensors that could be groundbreaking for cancer screening and other applications.
Neuroprotection of Rodent and Human Retinal Ganglion Cells In Vitro/Ex Vivo by the Hybrid Small Molecule SA-2
The mechanisms underlying the neuroprotective effects of the hybrid antioxidant-nitric oxide donating compound SA-2 in retinal ganglion cell (RGC) degeneration models were evaluated. The in vitro trophic factor (TF) deprivation model in primary rat RGCs and ex vivo human retinal explants were used to mimic glaucomatous neurodegeneration. Cell survival was assessed after treatment with vehicle or SA-2. In separate experiments, tert-Butyl hydroperoxide (TBHP) and endothelin-3 (ET-3) were used in ex vivo rat retinal explants and primary rat RGCs, respectively, to induce oxidative damage. Mitochondrial and intracellular reactive oxygen species (ROS) were assessed following treatments. In the TF deprivation model, SA-2 treatment produced a significant decrease in apoptotic and dead cell counts in primary RGCs and a significant increase in RGC survival in ex vivo human retinal explants. In the oxidative stress-induced models, a significant decrease in the production of ROS was observed in the SA-2-treated group compared to the vehicle-treated group. Compound SA-2 was neuroprotective against various glaucomatous insults in the rat and human RGCs by reducing apoptosis and decreasing ROS levels. Amelioration of mitochondrial and cellular oxidative stress by SA-2 may be a potential therapeutic strategy for preventing neurodegeneration in glaucomatous RGCs.
Plasmodium-encoded murine IL-6 impairs liver stage infection and elicits long-lasting sterilizing immunity
sporozoites (SPZ) inoculated by mosquitoes into the skin of the mammalian host migrate to the liver before infecting hepatocytes. Previous work demonstrated that early production of IL-6 in the liver is detrimental for the parasite growth, contributing to the acquisition of a long-lasting immune protection after immunization with live attenuated parasites. Considering that IL-6 as a critical pro-inflammatory signal, we explored a novel approach whereby the parasite itself encodes for the murine IL-6 gene. We generated transgenic parasites that express murine IL-6 during liver stage development. Though IL-6 transgenic SPZ developed into exo-erythrocytic forms in hepatocytes and , these parasites were not capable of inducing a blood stage infection in mice. Furthermore, immunization of mice with transgenic IL-6-expressing SPZ elicited a long-lasting CD8 T cell-mediated protective immunity against a subsequent infectious SPZ challenge. Collectively, this study demonstrates that parasite-encoded IL-6 attenuates parasite virulence with abortive liver stage of infection, forming the basis of a novel suicide vaccine strategy to elicit protective antimalarial immunity.
Mechanisms contributing to inhibition of retinal ganglion cell death by cell permeable peptain-1 under glaucomatous stress
This study assesses the neuroprotective potential of CPP-P1, a conjugate of an anti-apoptotic peptain-1 (P1) and a cell-penetrating peptide (CPP) in in vitro, in vivo, and ex vivo glaucoma models. Primary retinal ganglion cells (RGCs) were subjected to either neurotrophic factor (NF) deprivation for 48 h or endothelin-3 (ET-3) treatment for 24 h and received either CPP-P1 or vehicle. RGC survival was analyzed using a Live/Dead assay. Axotomized human retinal explants were treated with CPP-P1 or vehicle for seven days, stained with RGC marker RBPMS, and RGC survival was analyzed. Brown Norway (BN) rats with elevated intraocular pressure (IOP) received weekly intravitreal injections of CPP-P1 or vehicle for six weeks. RGC function was evaluated using a pattern electroretinogram (PERG). RGC and axonal damage were also assessed. RGCs from ocular hypertensive rats treated with CPP-P1 or vehicle for seven days were isolated for transcriptomic analysis. RGCs subjected to 48 h of NF deprivation were used for qPCR target confirmation. NF deprivation led to a significant loss of RGCs, which was markedly reduced by CPP-P1 treatment. CPP-P1 also decreased ET-3-mediated RGC death. In ex vivo human retinal explants, CPP-P1 decreased RGC loss. IOP elevation resulted in significant RGC loss in mid-peripheral and peripheral retinas compared to that in naive rats, which was significantly reduced by CPP-P1 treatment. PERG amplitude decline in IOP-elevated rats was mitigated by CPP-P1 treatment. Following IOP elevation in BN rats, the transcriptomic analysis showed over 6,000 differentially expressed genes in the CPP-P1 group compared to the vehicle-treated group. Upregulated pathways included CREB signaling and synaptogenesis. A significant increase in Creb1 mRNA and elevated phosphorylated Creb were observed in CPP-P1-treated RGCs. Our study showed that CPP-P1 is neuroprotective through CREB signaling enhancement in several settings that mimic glaucomatous conditions. The findings from this study are significant as they address the pressing need for the development of efficacious therapeutic strategies to maintain RGC viability and functionality associated with glaucoma.
Astroglial Cells: Emerging Therapeutic Targets in the Management of Traumatic Brain Injury
Traumatic Brain Injury (TBI) represents a significant health concern, necessitating advanced therapeutic interventions. This detailed review explores the critical roles of astrocytes, key cellular constituents of the central nervous system (CNS), in both the pathophysiology and possible rehabilitation of TBI. Following injury, astrocytes exhibit reactive transformations, differentiating into pro-inflammatory (A1) and neuroprotective (A2) phenotypes. This paper elucidates the interactions of astrocytes with neurons, their role in neuroinflammation, and the potential for their therapeutic exploitation. Emphasized strategies encompass the utilization of endocannabinoid and calcium signaling pathways, hormone-based treatments like 17β-estradiol, biological therapies employing anti-HBGB1 monoclonal antibodies, gene therapy targeting Connexin 43, and the innovative technique of astrocyte transplantation as a means to repair damaged neural tissues.
Macrophage Colony Stimulating Factor Derived from CD4+ T Cells Contributes to Control of a Blood-Borne Infection
Dynamic regulation of leukocyte population size and activation state is crucial for an effective immune response. In malaria, Plasmodium parasites elicit robust host expansion of macrophages and monocytes, but the underlying mechanisms remain unclear. Here we show that myeloid expansion during P. chabaudi infection is dependent upon both CD4+ T cells and the cytokine Macrophage Colony Stimulating Factor (MCSF). Single-cell RNA-Seq analysis on antigen-experienced T cells revealed robust expression of Csf1, the gene encoding MCSF, in a sub-population of CD4+ T cells with distinct transcriptional and surface phenotypes. Selective deletion of Csf1 in CD4+ cells during P. chabaudi infection diminished proliferation and activation of certain myeloid subsets, most notably lymph node-resident CD169+ macrophages, and resulted in increased parasite burden and impaired recovery of infected mice. Depletion of CD169+ macrophages during infection also led to increased parasitemia and significant host mortality, confirming a previously unappreciated role for these cells in control of P. chabaudi. This work establishes the CD4+ T cell as a physiologically relevant source of MCSF in vivo; probes the complexity of the CD4+ T cell response during type 1 infection; and delineates a novel mechanism by which T helper cells regulate myeloid cells to limit growth of a blood-borne intracellular pathogen.
The Diagnostic Accuracy of a Fecal Immunochemical Test in Detecting Colorectal Cancer and Advanced Precancerous Colorectal Neoplasia in Patients with Iron Deficiency: A Protocol for Systematic Review and Meta-Analysis
Background. Iron deficiency (ID) is a common micronutrient deficiency and the leading cause of anemia worldwide. ID can be caused by chronic occult blood loss from colorectal neoplasia including colorectal cancer (CRC) and advanced precancerous colorectal lesions. Current guidelines recommend colonoscopy in both men and postmenopausal women presenting with ID anemia (IDA). However, there is controversy on the investigation of patients presenting with a lower risk of CRC including younger women with ID and those with nonanemic ID (NAID). There is a need for a triaging tool to identify which ID patients may benefit from colonoscopy. The fecal immunochemical test (FIT) is sensitive for CRC screening in an asymptomatic population, but its role in ID patients is unclear. The aim of this study is to conduct a systematic review to determine the diagnostic accuracy of FIT for detecting CRC and advanced precancerous neoplasia in individuals presenting with ID with or without anemia. Methods and Analysis. This protocol conforms with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols and Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy. A comprehensive search of the MEDLINE, Embase, and Web of Science databases will be undertaken for studies published after 2010 which involve patients with ID, who completed a FIT in the 6 months prior to colonoscopy, with FIT sensitivity and specificity calculated against the reference standard colonoscopy. The search will be limited to studies conducted after 2010 to reduce variability in colonoscopy quality. Risk of bias assessment will be conducted using the Quality Assessment of Diagnostic Accuracy Studies version 2. FIT sensitivity and specificity will be the primary measure of diagnostic accuracy, and data will be analysed using a random effects meta-analysis. Discussion. This review and meta-analysis will be the first to systematically explore the value of the FIT as a triaging tool for patients with ID. This trial is registered with CRD42022367162.
Diagnostic and prognostic value of the left atrial myopathy evaluation in cardiac amyloidosis using echocardiography
Background Cardiac amyloidosis (CA) is an under‐recognized cause of heart failure. Left atrial (LA) myopathy contributes to a worse prognosis in heart failure and is a feature of transthyretin (ATTR) and light‐chain (AL) CA. LA mechanical dispersion (LA‐MD) is a novel marker of intra‐atrial dyssynchrony implicated in LA myopathy and the future development of atrial fibrillation (AF). Aims This study aimed to determine the characteristics and prognostic value of LA myopathy in ATTR and AL cardiomyopathy through a comprehensive LA echocardiographic evaluation. Methods ATTR (n = 86) and AL (n = 86) CA patients were compared with hypertensive heart disease (HHT) patients (n = 58). Transthoracic echocardiographic measurements including LA strain and LA‐MD were obtained with patient follow‐up for mortality. Results ATTR and AL patients had a median follow‐up of 66 months, with 26 mortality events. Left ventricular (LV) mass, diastolic function (average‐e′ and E/e′), LV global longitudinal strain, and LA volume and function (LA function index and strain) were more impaired in ATTR versus AL; these echocardiographic parameters were more impaired in both amyloid groups compared to HHT patients (P < 0.05). LA‐MD was increased in ATTR versus AL [median 72.2 (inter‐quartile range 55–88.9) vs. 54 (43.5–64.2), respectively, P < 0.001]. Multivariable logistic regression adjusted for age, presence of AF, LV mass, global and basal strain, and E/e′ demonstrated that LA‐MD was an independent determinant of ATTR CA (P = 0.014). On multivariable analysis, LA reservoir strain was independently associated with the presence of heart failure in the CA group (P < 0.001). LA minimum volume (cut‐off ≥18 mL/m2) was a determinant of mortality in AL CA [Cox proportional hazard ratio (HR) 1.042 (1.003–1.082), P = 0.034 and Kaplan–Meier analysis, P = 0.016]. Conclusion Characterizing LA myopathy has significant diagnostic and prognostic utility in CA. ATTR patients have increased atrial dyssynchrony, which may have implications for AF development. LA reservoir strain was associated with heart failure in CA, whilst LA minimum volume was a predictor of mortality in AL CA.